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  <title>P1861R1: Secure Networking in C++</title>
<style data-fill-with="stylesheet">/******************************************************************************
 *                   Style sheet for the W3C specifications                   *
 *
 * Special classes handled by this style sheet include:
 *
 * Indices
 *   - .toc for the Table of Contents (<ol class="toc">)
 *     + <span class="secno"> for the section numbers
 *   - #toc for the Table of Contents (<nav id="toc">)
 *   - ul.index for Indices (<a href="#ref">term</a><span>, in §N.M</span>)
 *   - table.index for Index Tables (e.g. for properties or elements)
 *
 * Structural Markup
 *   - table.data for general data tables
 *     -> use 'scope' attribute, <colgroup>, <thead>, and <tbody> for best results !
 *     -> use <table class='complex data'> for extra-complex tables
 *     -> use <td class='long'> for paragraph-length cell content
 *     -> use <td class='pre'> when manual line breaks/indentation would help readability
 *   - dl.switch for switch statements
 *   - ol.algorithm for algorithms (helps to visualize nesting)
 *   - .figure and .caption (HTML4) and figure and figcaption (HTML5)
 *     -> .sidefigure for right-floated figures
 *   - ins/del
 *
 * Code
 *   - pre and code
 *
 * Special Sections
 *   - .note       for informative notes             (div, p, span, aside, details)
 *   - .example    for informative examples          (div, p, pre, span)
 *   - .issue      for issues                        (div, p, span)
 *   - .assertion  for assertions                    (div, p, span)
 *   - .advisement for loud normative statements     (div, p, strong)
 *   - .annoying-warning for spec obsoletion notices (div, aside, details)
 *
 * Definition Boxes
 *   - pre.def   for WebIDL definitions
 *   - table.def for tables that define other entities (e.g. CSS properties)
 *   - dl.def    for definition lists that define other entitles (e.g. HTML elements)
 *
 * Numbering
 *   - .secno for section numbers in .toc and headings (<span class='secno'>3.2</span>)
 *   - .marker for source-inserted example/figure/issue numbers (<span class='marker'>Issue 4</span>)
 *   - ::before styled for CSS-generated issue/example/figure numbers:
 *     -> Documents wishing to use this only need to add
 *        figcaption::before,
 *        .caption::before { content: "Figure "  counter(figure) " ";  }
 *        .example::before { content: "Example " counter(example) " "; }
 *        .issue::before   { content: "Issue "   counter(issue) " ";   }
 *
 * Header Stuff (ignore, just don't conflict with these classes)
 *   - .head for the header
 *   - .copyright for the copyright
 *
 * Miscellaneous
 *   - .overlarge for things that should be as wide as possible, even if
 *     that overflows the body text area. This can be used on an item or
 *     on its container, depending on the effect desired.
 *     Note that this styling basically doesn't help at all when printing,
 *     since A4 paper isn't much wider than the max-width here.
 *     It's better to design things to fit into a narrower measure if possible.
 *   - js-added ToC jump links (see fixup.js)
 *
 ******************************************************************************/

/******************************************************************************/
/*                                   Body                                     */
/******************************************************************************/

	body {
		counter-reset: example figure issue;

		/* Layout */
		max-width: 50em;               /* limit line length to 50em for readability   */
		margin: 0 auto;                /* center text within page                     */
		padding: 1.6em 1.5em 2em 50px; /* assume 16px font size for downlevel clients */
		padding: 1.6em 1.5em 2em calc(26px + 1.5em); /* leave space for status flag     */

		/* Typography */
		line-height: 1.5;
		font-family: sans-serif;
		widows: 2;
		orphans: 2;
		word-wrap: break-word;
		overflow-wrap: break-word;
		hyphens: auto;

		/* Colors */
		color: black;
		background: white top left fixed no-repeat;
		background-size: 25px auto;
	}


/******************************************************************************/
/*                         Front Matter & Navigation                          */
/******************************************************************************/

/** Header ********************************************************************/

	div.head { margin-bottom: 1em }
	div.head hr { border-style: solid; }

	div.head h1 {
		font-weight: bold;
		margin: 0 0 .1em;
		font-size: 220%;
	}

	div.head h2 { margin-bottom: 1.5em;}

/** W3C Logo ******************************************************************/

	.head .logo {
		float: right;
		margin: 0.4rem 0 0.2rem .4rem;
	}

	.head img[src*="logos/W3C"] {
		display: block;
		border: solid #1a5e9a;
		border-width: .65rem .7rem .6rem;
		border-radius: .4rem;
		background: #1a5e9a;
		color: white;
		font-weight: bold;
	}

	.head a:hover > img[src*="logos/W3C"],
	.head a:focus > img[src*="logos/W3C"] {
		opacity: .8;
	}

	.head a:active > img[src*="logos/W3C"] {
		background: #c00;
		border-color: #c00;
	}

	/* see also additional rules in Link Styling section */

/** Copyright *****************************************************************/

	p.copyright,
	p.copyright small { font-size: small }

/** Back to Top / ToC Toggle **************************************************/

	@media print {
		#toc-nav {
			display: none;
		}
	}
	@media not print {
		#toc-nav {
			position: fixed;
			z-index: 2;
			bottom: 0; left: 0;
			margin: 0;
			min-width: 1.33em;
			border-top-right-radius: 2rem;
			box-shadow: 0 0 2px;
			font-size: 1.5em;
			color: black;
		}
		#toc-nav > a {
			display: block;
			white-space: nowrap;

			height: 1.33em;
			padding: .1em 0.3em;
			margin: 0;

			background: white;
			box-shadow: 0 0 2px;
			border: none;
			border-top-right-radius: 1.33em;
			background: white;
		}
		#toc-nav > #toc-jump {
			padding-bottom: 2em;
			margin-bottom: -1.9em;
		}

		#toc-nav > a:hover,
		#toc-nav > a:focus {
			background: #f8f8f8;
		}
		#toc-nav > a:not(:hover):not(:focus) {
			color: #707070;
		}

		/* statusbar gets in the way on keyboard focus; remove once browsers fix */
		#toc-nav > a[href="#toc"]:not(:hover):focus:last-child {
			padding-bottom: 1.5rem;
		}

		#toc-nav:not(:hover) > a:not(:focus) > span + span {
			/* Ideally this uses :focus-within on #toc-nav */
			display: none;
		}
		#toc-nav > a > span + span {
			padding-right: 0.2em;
		}

		#toc-toggle-inline {
			vertical-align: 0.05em;
			font-size: 80%;
			color: gray;
			color: hsla(203,20%,40%,.7);
			border-style: none;
			background: transparent;
			position: relative;
		}
		#toc-toggle-inline:hover:not(:active),
		#toc-toggle-inline:focus:not(:active) {
			text-shadow: 1px 1px silver;
			top: -1px;
			left: -1px;
		}

		#toc-nav :active {
			color: #C00;
		}
	}

/** ToC Sidebar ***************************************************************/

	/* Floating sidebar */
	@media screen {
		body.toc-sidebar #toc {
			position: fixed;
			top: 0; bottom: 0;
			left: 0;
			width: 23.5em;
			max-width: 80%;
			max-width: calc(100% - 2em - 26px);
			overflow: auto;
			padding: 0 1em;
			padding-left: 42px;
			padding-left: calc(1em + 26px);
			background: inherit;
			background-color: #f7f8f9;
			z-index: 1;
			box-shadow: -.1em 0 .25em rgba(0,0,0,.1) inset;
		}
		body.toc-sidebar #toc h2 {
			margin-top: .8rem;
			font-variant: small-caps;
			font-variant: all-small-caps;
			text-transform: lowercase;
			font-weight: bold;
			color: gray;
			color: hsla(203,20%,40%,.7);
		}
		body.toc-sidebar #toc-jump:not(:focus) {
			width: 0;
			height: 0;
			padding: 0;
			position: absolute;
			overflow: hidden;
		}
	}
	/* Hide main scroller when only the ToC is visible anyway */
	@media screen and (max-width: 28em) {
		body.toc-sidebar {
			overflow: hidden;
		}
	}

	/* Sidebar with its own space */
	@media screen and (min-width: 78em) {
		body:not(.toc-inline) #toc {
			position: fixed;
			top: 0; bottom: 0;
			left: 0;
			width: 23.5em;
			overflow: auto;
			padding: 0 1em;
			padding-left: 42px;
			padding-left: calc(1em + 26px);
			background: inherit;
			background-color: #f7f8f9;
			z-index: 1;
			box-shadow: -.1em 0 .25em rgba(0,0,0,.1) inset;
		}
		body:not(.toc-inline) #toc h2 {
			margin-top: .8rem;
			font-variant: small-caps;
			font-variant: all-small-caps;
			text-transform: lowercase;
			font-weight: bold;
			color: gray;
			color: hsla(203,20%,40%,.7);
		}

		body:not(.toc-inline) {
			padding-left: 29em;
		}
		/* See also Overflow section at the bottom */

		body:not(.toc-inline) #toc-jump:not(:focus) {
			width: 0;
			height: 0;
			padding: 0;
			position: absolute;
			overflow: hidden;
		}
	}
	@media screen and (min-width: 90em) {
		body:not(.toc-inline) {
			margin: 0 4em;
		}
	}

/******************************************************************************/
/*                                Sectioning                                  */
/******************************************************************************/

/** Headings ******************************************************************/

	h1, h2, h3, h4, h5, h6, dt {
		page-break-after: avoid;
		page-break-inside: avoid;
		font: 100% sans-serif;   /* Reset all font styling to clear out UA styles */
		font-family: inherit;    /* Inherit the font family. */
		line-height: 1.2;        /* Keep wrapped headings compact */
		hyphens: manual;         /* Hyphenated headings look weird */
	}

	h2, h3, h4, h5, h6 {
		margin-top: 3rem;
	}

	h1, h2, h3 {
		color: #005A9C;
		background: transparent;
	}

	h1 { font-size: 170%; }
	h2 { font-size: 140%; }
	h3 { font-size: 120%; }
	h4 { font-weight: bold; }
	h5 { font-style: italic; }
	h6 { font-variant: small-caps; }
	dt { font-weight: bold; }

/** Subheadings ***************************************************************/

	h1 + h2,
	#subtitle {
		/* #subtitle is a subtitle in an H2 under the H1 */
		margin-top: 0;
	}
	h2 + h3,
	h3 + h4,
	h4 + h5,
	h5 + h6 {
		margin-top: 1.2em; /* = 1 x line-height */
	}

/** Section divider ***********************************************************/

	:not(.head) > hr {
		font-size: 1.5em;
		text-align: center;
		margin: 1em auto;
		height: auto;
		border: transparent solid 0;
		background: transparent;
	}
	:not(.head) > hr::before {
		content: "\2727\2003\2003\2727\2003\2003\2727";
	}

/******************************************************************************/
/*                            Paragraphs and Lists                            */
/******************************************************************************/

	p {
		margin: 1em 0;
	}

	dd > p:first-child,
	li > p:first-child {
		margin-top: 0;
	}

	ul, ol {
		margin-left: 0;
		padding-left: 2em;
	}

	li {
		margin: 0.25em 0 0.5em;
		padding: 0;
	}

	dl dd {
		margin: 0 0 .5em 2em;
	}

	.head dd + dd { /* compact for header */
		margin-top: -.5em;
	}

	/* Style for algorithms */
	ol.algorithm ol:not(.algorithm),
	.algorithm > ol ol:not(.algorithm) {
	 border-left: 0.5em solid #DEF;
	}

	/* Put nice boxes around each algorithm. */
	[data-algorithm]:not(.heading) {
	  padding: .5em;
	  border: thin solid #ddd; border-radius: .5em;
	  margin: .5em calc(-0.5em - 1px);
	}
	[data-algorithm]:not(.heading) > :first-child {
	  margin-top: 0;
	}
	[data-algorithm]:not(.heading) > :last-child {
	  margin-bottom: 0;
	}

	/* Style for switch/case <dl>s */
	dl.switch > dd > ol.only,
	dl.switch > dd > .only > ol {
	 margin-left: 0;
	}
	dl.switch > dd > ol.algorithm,
	dl.switch > dd > .algorithm > ol {
	 margin-left: -2em;
	}
	dl.switch {
	 padding-left: 2em;
	}
	dl.switch > dt {
	 text-indent: -1.5em;
	 margin-top: 1em;
	}
	dl.switch > dt + dt {
	 margin-top: 0;
	}
	dl.switch > dt::before {
	 content: '\21AA';
	 padding: 0 0.5em 0 0;
	 display: inline-block;
	 width: 1em;
	 text-align: right;
	 line-height: 0.5em;
	}

/** Terminology Markup ********************************************************/


/******************************************************************************/
/*                                 Inline Markup                              */
/******************************************************************************/

/** Terminology Markup ********************************************************/
	dfn   { /* Defining instance */
		font-weight: bolder;
	}
	a > i { /* Instance of term */
		font-style: normal;
	}
	dt dfn code, code.idl {
		font-size: medium;
	}
	dfn var {
		font-style: normal;
	}

/** Change Marking ************************************************************/

	del { color: red;  text-decoration: line-through; }
	ins { color: #080; text-decoration: underline;    }

/** Miscellaneous improvements to inline formatting ***************************/

	sup {
		vertical-align: super;
		font-size: 80%
	}

/******************************************************************************/
/*                                    Code                                    */
/******************************************************************************/

/** General monospace/pre rules ***********************************************/

	pre, code, samp {
		font-family: Menlo, Consolas, "DejaVu Sans Mono", Monaco, monospace;
		font-size: .9em;
		page-break-inside: avoid;
		hyphens: none;
		text-transform: none;
	}
	pre code,
	code code {
		font-size: 100%;
	}

	pre {
		margin-top: 1em;
		margin-bottom: 1em;
		overflow: auto;
	}

/** Inline Code fragments *****************************************************/

  /* Do something nice. */

/******************************************************************************/
/*                                    Links                                   */
/******************************************************************************/

/** General Hyperlinks ********************************************************/

	/* We hyperlink a lot, so make it less intrusive */
	a[href] {
		color: #034575;
		text-decoration: none;
		border-bottom: 1px solid #707070;
		/* Need a bit of extending for it to look okay */
		padding: 0 1px 0;
		margin: 0 -1px 0;
	}
	a:visited {
		border-bottom-color: #BBB;
	}

	/* Use distinguishing colors when user is interacting with the link */
	a[href]:focus,
	a[href]:hover {
		background: #f8f8f8;
		background: rgba(75%, 75%, 75%, .25);
		border-bottom-width: 3px;
		margin-bottom: -2px;
	}
	a[href]:active {
		color: #C00;
		border-color: #C00;
	}

	/* Backout above styling for W3C logo */
	.head .logo,
	.head .logo a {
		border: none;
		text-decoration: none;
		background: transparent;
	}

/******************************************************************************/
/*                                    Images                                  */
/******************************************************************************/

	img {
		border-style: none;
	}

	/* For autogen numbers, add
	   .caption::before, figcaption::before { content: "Figure " counter(figure) ". "; }
	*/

	figure, .figure, .sidefigure {
		page-break-inside: avoid;
		text-align: center;
		margin: 2.5em 0;
	}
	.figure img,    .sidefigure img,    figure img,
	.figure object, .sidefigure object, figure object {
		max-width: 100%;
		margin: auto;
	}
	.figure pre, .sidefigure pre, figure pre {
		text-align: left;
		display: table;
		margin: 1em auto;
	}
	.figure table, figure table {
		margin: auto;
	}
	@media screen and (min-width: 20em) {
		.sidefigure {
			float: right;
			width: 50%;
			margin: 0 0 0.5em 0.5em
		}
	}
	.caption, figcaption, caption {
		font-style: italic;
		font-size: 90%;
	}
	.caption::before, figcaption::before, figcaption > .marker {
		font-weight: bold;
	}
	.caption, figcaption {
		counter-increment: figure;
	}

	/* DL list is indented 2em, but figure inside it is not */
	dd > .figure, dd > figure { margin-left: -2em }

/******************************************************************************/
/*                             Colored Boxes                                  */
/******************************************************************************/

	.issue, .note, .example, .assertion, .advisement, blockquote {
		padding: .5em;
		border: .5em;
		border-left-style: solid;
		page-break-inside: avoid;
	}
	span.issue, span.note {
		padding: .1em .5em .15em;
		border-right-style: solid;
	}

	.issue,
	.note,
	.example,
	.advisement,
	.assertion,
	blockquote {
		margin: 1em auto;
	}
	.note  > p:first-child,
	.issue > p:first-child,
	blockquote > :first-child {
		margin-top: 0;
	}
	blockquote > :last-child {
		margin-bottom: 0;
	}

/** Blockquotes ***************************************************************/

	blockquote {
		border-color: silver;
	}

/** Open issue ****************************************************************/

	.issue {
		border-color: #E05252;
		background: #FBE9E9;
		counter-increment: issue;
		overflow: auto;
	}
	.issue::before, .issue > .marker {
		text-transform: uppercase;
		color: #AE1E1E;
		padding-right: 1em;
		text-transform: uppercase;
	}
	/* Add .issue::before { content: "Issue " counter(issue) " "; } for autogen numbers,
	   or use class="marker" to mark up the issue number in source. */

/** Example *******************************************************************/

	.example {
		border-color: #E0CB52;
		background: #FCFAEE;
		counter-increment: example;
		overflow: auto;
		clear: both;
	}
	.example::before, .example > .marker {
		text-transform: uppercase;
		color: #827017;
		min-width: 7.5em;
		display: block;
	}
	/* Add .example::before { content: "Example " counter(example) " "; } for autogen numbers,
	   or use class="marker" to mark up the example number in source. */

/** Non-normative Note ********************************************************/

	.note {
		border-color: #52E052;
		background: #E9FBE9;
		overflow: auto;
	}

	.note::before, .note > .marker,
	details.note > summary::before,
	details.note > summary > .marker {
		text-transform: uppercase;
		display: block;
		color: hsl(120, 70%, 30%);
	}
	/* Add .note::before { content: "Note"; } for autogen label,
	   or use class="marker" to mark up the label in source. */

	details.note > summary {
		display: block;
		color: hsl(120, 70%, 30%);
	}
	details.note[open] > summary {
		border-bottom: 1px silver solid;
	}

/** Assertion Box *************************************************************/
	/*  for assertions in algorithms */

	.assertion {
		border-color: #AAA;
		background: #EEE;
	}

/** Advisement Box ************************************************************/
	/*  for attention-grabbing normative statements */

	.advisement {
		border-color: orange;
		border-style: none solid;
		background: #FFEECC;
	}
	strong.advisement {
		display: block;
		text-align: center;
	}
	.advisement > .marker {
		color: #B35F00;
	}

/** Spec Obsoletion Notice ****************************************************/
	/* obnoxious obsoletion notice for older/abandoned specs. */

	details {
		display: block;
	}
	summary {
		font-weight: bolder;
	}

	.annoying-warning:not(details),
	details.annoying-warning:not([open]) > summary,
	details.annoying-warning[open] {
		background: #fdd;
		color: red;
		font-weight: bold;
		padding: .75em 1em;
		border: thick red;
		border-style: solid;
		border-radius: 1em;
	}
	.annoying-warning :last-child {
		margin-bottom: 0;
	}

@media not print {
	details.annoying-warning[open] {
		position: fixed;
		left: 1em;
		right: 1em;
		bottom: 1em;
		z-index: 1000;
	}
}

	details.annoying-warning:not([open]) > summary {
		text-align: center;
	}

/** Entity Definition Boxes ***************************************************/

	.def {
		padding: .5em 1em;
		background: #DEF;
		margin: 1.2em 0;
		border-left: 0.5em solid #8CCBF2;
	}

/******************************************************************************/
/*                                    Tables                                  */
/******************************************************************************/

	th, td {
		text-align: left;
		text-align: start;
	}

/** Property/Descriptor Definition Tables *************************************/

	table.def {
		/* inherits .def box styling, see above */
		width: 100%;
		border-spacing: 0;
	}

	table.def td,
	table.def th {
		padding: 0.5em;
		vertical-align: baseline;
		border-bottom: 1px solid #bbd7e9;
	}

	table.def > tbody > tr:last-child th,
	table.def > tbody > tr:last-child td {
		border-bottom: 0;
	}

	table.def th {
		font-style: italic;
		font-weight: normal;
		padding-left: 1em;
		width: 3em;
	}

	/* For when values are extra-complex and need formatting for readability */
	table td.pre {
		white-space: pre-wrap;
	}

	/* A footnote at the bottom of a def table */
	table.def           td.footnote {
		padding-top: 0.6em;
	}
	table.def           td.footnote::before {
		content: " ";
		display: block;
		height: 0.6em;
		width: 4em;
		border-top: thin solid;
	}

/** Data tables (and properly marked-up index tables) *************************/
	/*
		 <table class="data"> highlights structural relationships in a table
		 when correct markup is used (e.g. thead/tbody, th vs. td, scope attribute)

		 Use class="complex data" for particularly complicated tables --
		 (This will draw more lines: busier, but clearer.)

		 Use class="long" on table cells with paragraph-like contents
		 (This will adjust text alignment accordingly.)
		 Alternately use class="longlastcol" on tables, to have the last column assume "long".
	*/

	table {
		word-wrap: normal;
		overflow-wrap: normal;
		hyphens: manual;
	}

	table.data,
	table.index {
		margin: 1em auto;
		border-collapse: collapse;
		border: hidden;
		width: 100%;
	}
	table.data caption,
	table.index caption {
		max-width: 50em;
		margin: 0 auto 1em;
	}

	table.data td,  table.data th,
	table.index td, table.index th {
		padding: 0.5em 1em;
		border-width: 1px;
		border-color: silver;
		border-top-style: solid;
	}

	table.data thead td:empty {
		padding: 0;
		border: 0;
	}

	table.data  thead,
	table.index thead,
	table.data  tbody,
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/******************************************************************************/
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 <body class="h-entry">
  <div class="head">
   <p data-fill-with="logo"></p>
   <h1 class="p-name no-ref" id="title">P1861R1<br>Secure Networking in C++</h1>
   <h2 class="no-num no-toc no-ref heading settled" id="subtitle"><span class="content">Published Proposal, <time class="dt-updated" datetime="2020-05-11">2020-05-11</time></span></h2>
   <div data-fill-with="spec-metadata">
    <dl>
     <dt>This version:
     <dd><a class="u-url" href="http://wg21.link/P1861R1">http://wg21.link/P1861R1</a>
     <dt>Authors:
     <dd>
      <dd class="editor p-author h-card vcard"><a class="p-name fn u-email email" href="mailto:achristensen@apple.com">Alex Christensen</a> (<span class="p-org org">Apple</span>)
     <dd>
      <dd class="editor p-author h-card vcard"><a class="p-name fn u-email email" href="mailto:jfbastien@apple.com">JF Bastien</a> (<span class="p-org org">Apple</span>)
     <dd>
      <dd class="editor p-author h-card vcard"><a class="p-name fn u-email email" href="mailto:scott_herscher@apple.com">Scott Herscher</a> (<span class="p-org org">Apple</span>)
     <dt>Audience:
     <dd>SG4, LEWG
     <dt>Project:
     <dd>ISO/IEC JTC1/SC22/WG21 14882: Programming Language — C++
     <dt>Source:
     <dd><a href="https://github.com/achristensen07/papers/blob/master/source/p1861r1.bs">https://github.com/achristensen07/papers/blob/master/source/p1861r1.bs</a>
    </dl>
   </div>
   <div data-fill-with="warning"></div>
   <hr title="Separator for header">
  </div>
  <nav data-fill-with="table-of-contents" id="toc">
   <h2 class="no-num no-toc no-ref" id="contents">Table of Contents</h2>
   <ol class="toc" role="directory">
    <li><a href="#abstract"><span class="secno">1</span> <span class="content">Abstract</span></a>
    <li><a href="#intro"><span class="secno">2</span> <span class="content">Introduction</span></a>
    <li><a href="#versionhistory"><span class="secno">3</span> <span class="content">Version History</span></a>
    <li><a href="#disclaimer"><span class="secno">4</span> <span class="content">Disclaimer</span></a>
    <li>
     <a href="#api"><span class="secno">5</span> <span class="content">Suggested API</span></a>
     <ol class="toc">
      <li><a href="#awaitable"><span class="secno">5.1</span> <span class="content"><code class="highlight"><c- n>net</c-><c- o>::</c-><c- n>awaitable</c-></code></span></a>
      <li><a href="#buffer"><span class="secno">5.2</span> <span class="content"><code class="highlight"><c- n>net</c-><c- o>::</c-><c- n>buffer</c-></code></span></a>
      <li><a href="#connection"><span class="secno">5.3</span> <span class="content"><code class="highlight"><c- n>net</c-><c- o>::</c-><c- n>connection</c-></code></span></a>
      <li><a href="#endpoint"><span class="secno">5.4</span> <span class="content"><code class="highlight"><c- n>net</c-><c- o>::</c-><c- n>endpoint</c-></code></span></a>
      <li><a href="#expected"><span class="secno">5.5</span> <span class="content"><code class="highlight"><c- n>net</c-><c- o>::</c-><c- n>expected</c-></code></span></a>
      <li><a href="#interface"><span class="secno">5.6</span> <span class="content"><code class="highlight"><c- n>net</c-><c- o>::</c-><c- n>interface</c-></code></span></a>
      <li><a href="#listener"><span class="secno">5.7</span> <span class="content"><code class="highlight"><c- n>net</c-><c- o>::</c-><c- n>listener</c-></code></span></a>
      <li><a href="#messagecontext"><span class="secno">5.8</span> <span class="content"><code class="highlight"><c- n>net</c-><c- o>::</c-><c- n>message</c-><c- o>::</c-><c- n>context</c-></code></span></a>
      <li><a href="#message"><span class="secno">5.9</span> <span class="content"><code class="highlight"><c- n>net</c-><c- o>::</c-><c- n>message</c-></code></span></a>
      <li><a href="#parameters"><span class="secno">5.10</span> <span class="content"><code class="highlight"><c- n>net</c-><c- o>::</c-><c- n>parameters</c-></code></span></a>
      <li><a href="#path"><span class="secno">5.11</span> <span class="content"><code class="highlight"><c- n>net</c-><c- o>::</c-><c- n>path</c-></code></span></a>
      <li><a href="#pathmonitor"><span class="secno">5.12</span> <span class="content"><code class="highlight"><c- n>net</c-><c- o>::</c-><c- n>path_monitor</c-></code></span></a>
      <li><a href="#protocol"><span class="secno">5.13</span> <span class="content"><code class="highlight"><c- n>net</c-><c- o>::</c-><c- n>protocol</c-></code></span></a>
      <li><a href="#protocolframer"><span class="secno">5.14</span> <span class="content"><code class="highlight"><c- n>net</c-><c- o>::</c-><c- n>protocol</c-><c- o>::</c-><c- n>framer</c-></code></span></a>
      <li><a href="#workqueue"><span class="secno">5.15</span> <span class="content"><code class="highlight"><c- n>net</c-><c- o>::</c-><c- n>workqueue</c-></code></span></a>
     </ol>
    <li>
     <a href="#examples"><span class="secno">6</span> <span class="content">Examples</span></a>
     <ol class="toc">
      <li><a href="#client"><span class="secno">6.1</span> <span class="content">Client</span></a>
      <li><a href="#server"><span class="secno">6.2</span> <span class="content">Server</span></a>
      <li><a href="#pathlistener"><span class="secno">6.3</span> <span class="content">Path Listener</span></a>
      <li><a href="#framer"><span class="secno">6.4</span> <span class="content">Protocol Framer</span></a>
     </ol>
    <li><a href="#notes"><span class="secno">7</span> <span class="content">Notes</span></a>
    <li><a href="#implementability"><span class="secno">8</span> <span class="content">Implementability</span></a>
    <li>
     <a href="#references"><span class="secno"></span> <span class="content">References</span></a>
     <ol class="toc">
      <li><a href="#informative"><span class="secno"></span> <span class="content">Informative References</span></a>
     </ol>
   </ol>
  </nav>
  <main>
   <h2 class="heading settled" data-level="1" id="abstract"><span class="secno">1. </span><span class="content">Abstract</span><a class="self-link" href="#abstract"></a></h2>
   <p>A description of how a C++ networking library can elegantly support Transport Layer Security (TLS) and Datagram Transport Layer Security (DTLS) by default, as well as allow future expansion to include protocols such as <a href="https://tools.ietf.org/html/draft-ietf-quic-transport-27">QUIC</a>.</p>
   <h2 class="heading settled" data-level="2" id="intro"><span class="secno">2. </span><span class="content">Introduction</span><a class="self-link" href="#intro"></a></h2>
   <p>An interface to modern computer networks that is intended to maintain API and ABI stability must be designed for modern protocols. Indeed, networking protocols have evolved substantially since the Berkeley Socket APIs were originally created. Of utmost importance is support for security by default, as outlined in <a data-link-type="biblio" href="#biblio-p1860r0">[p1860R0]</a>.</p>
   <p>These design principles were discussed with the Committee’s networking study group, which asked the authors to what extent the <a href="https://datatracker.ietf.org/wg/taps/documents/">IETF TAPS</a> framework could be used as a basis, and what the resulting API would look like. This document presents an embodiment of TAPS into a modern C++ paradigm. We believe it also matches well with current industry practice (such as Apple’s <a href="https://developer.apple.com/documentation/network">Network.framework</a> API). As a proof of feasibility, a working implementation of this interface was written as a wrapper around Network.framework. Other implementations are possible, as discussed in <a href="#implementability">§ 8 Implementability</a>. The suggested API poses very little burden on C++ Standard Library maintainers.</p>
   <p>Notable differences between this approach and the current networking proposal in <a data-link-type="biblio" href="#biblio-n4771">[N4771]</a> include:</p>
   <ol>
    <li data-md>
     <p><a href="https://developer.apple.com/bonjour/">zero-configuration networking</a> endpoints in the <code class="highlight"><c- n>dnssd</c-></code> class.</p>
    <li data-md>
     <p>The <code class="highlight"><c- n>path_monitor</c-></code> class, which allows programs to receive notifications of changes in WiFi connectivity, or use of cellular data.</p>
    <li data-md>
     <p><code class="highlight"><c- n>options</c-></code> and <code class="highlight"><c- n>metadata</c-></code> objects that allow configuration and reading of protocol-specific properties.</p>
    <li data-md>
     <p>A clean interface to add security by default as described in <a data-link-type="biblio" href="#biblio-p1860r0">[p1860R0]</a>.</p>
   </ol>
   <p>These differences stem from following the IETF TAPS design.</p>
   <p>Additionally, this suggested API has integration with coroutines, which allows elegant asynchronous programming. Coroutines were added to C++20, it is therefore sensible to use them.</p>
   <p>The <a href="#api">§ 5 Suggested API</a> and be used to create a variety of applications. We offer a few examples:</p>
   <ul>
    <li data-md>
     <p><a href="#client">§ 6.1 Client</a></p>
    <li data-md>
     <p><a href="#server">§ 6.2 Server</a></p>
    <li data-md>
     <p><a href="#pathlistener">§ 6.3 Path Listener</a></p>
    <li data-md>
     <p><a href="#framer">§ 6.4 Protocol Framer</a></p>
   </ul>
   <h2 class="heading settled" data-level="3" id="versionhistory"><span class="secno">3. </span><span class="content">Version History</span><a class="self-link" href="#versionhistory"></a></h2>
   <ul>
    <li data-md>
     <p><a data-link-type="biblio" href="#biblio-p1861r0">[P1861R0]</a>: Minimal diff from <a data-link-type="biblio" href="#biblio-n4771">[N4771]</a> to support TLS and DTLS in a way that is not great.</p>
    <li data-md>
     <p>P1861R1: Initial suggested API based on IETF TAPS.</p>
   </ul>
   <h2 class="heading settled" data-level="4" id="disclaimer"><span class="secno">4. </span><span class="content">Disclaimer</span><a class="self-link" href="#disclaimer"></a></h2>
   <p>This paper uses <code class="highlight"><c- n>std</c-><c- o>::</c-><c- n>is_invocable_r_v</c-></code> instead of concepts, and it uses <code class="highlight"><c- n>std</c-><c- o>::</c-><c- n>string_view</c-></code> and <code class="highlight"><c- n>std</c-><c- o>::</c-><c- n>vector</c-></code> in some places instead of ranges.
The author was working with an incomplete implementation of C++20 at the time, and these could easily be updated in a future revision.
It also doesn’t have all the <code class="highlight"><c- k>noexcept</c-></code> annotations that it could.
Please try to look past that at the shape of an interface to the network.</p>
   <h2 class="heading settled" data-level="5" id="api"><span class="secno">5. </span><span class="content">Suggested API</span><a class="self-link" href="#api"></a></h2>
   <h3 class="heading settled" data-level="5.1" id="awaitable"><span class="secno">5.1. </span><span class="content"><code class="highlight"><c- n>net</c-><c- o>::</c-><c- n>awaitable</c-></code></span><a class="self-link" href="#awaitable"></a></h3>
    This object is a simple template that is returned when there is a possibility of asynchrony, which allows the caller to either <code class="highlight"><c- n>co_await</c-></code> the result when using coroutines or call <code class="highlight"><c- p>.</c-><c- n>then</c-></code> on the result when not using coroutines.  This could probably use another awaitable type in the STL, and this is not directly related
to networking, but networking does need a medium of asynchrony such as this. 
<pre class="highlight"><code class="highlight"><c- k><c- k>namespace</c-></c-> <c- n><c- n>net</c-></c-> <c- p><c- p>{</c-></c->

<c- k><c- k>template</c-></c-><c- o><c- o>&lt;</c-></c-><c- k><c- k>typename</c-></c-> <c- n><c- n>T</c-></c-><c- o><c- o>></c-></c->
<c- k><c- k>class</c-></c-> <c- nc><c- nc>awaitable</c-></c-> <c- p><c- p>{</c-></c->
<c- k><c- k>public</c-></c-><c- o><c- o>:</c-></c->
  <c- n><c- n>awaitable</c-></c-><c- p><c- p>();</c-></c->
  <c- n><c- n>awaitable</c-></c-><c- p><c- p>(</c-></c-><c- k><c- k>const</c-></c-> <c- n><c- n>awaitable</c-></c-><c- o><c- o>&amp;</c-></c-><c- p><c- p>);</c-></c->
  <c- n><c- n>awaitable</c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>awaitable</c-></c-><c- o><c- o>&amp;&amp;</c-></c-><c- p><c- p>);</c-></c->
  <c- n><c- n>awaitable</c-></c-><c- o><c- o>&amp;</c-></c-> <c- k><c- k>operator</c-></c-><c- o><c- o>=</c-></c-><c- p><c- p>(</c-></c-><c- k><c- k>const</c-></c-> <c- n><c- n>awaitable</c-></c-><c- o><c- o>&amp;</c-></c-><c- p><c- p>);</c-></c->
  <c- n><c- n>awaitable</c-></c-><c- o><c- o>&amp;</c-></c-> <c- k><c- k>operator</c-></c-><c- o><c- o>=</c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>awaitable</c-></c-><c- o><c- o>&amp;&amp;</c-></c-><c- p><c- p>);</c-></c->

  <c- b><c- b>bool</c-></c-> <c- nf><c- nf>await_ready</c-></c-><c- p><c- p>()</c-></c-> <c- k><c- k>const</c-></c-> <c- k><c- k>noexcept</c-></c-><c- p><c- p>;</c-></c->
  <c- b><c- b>void</c-></c-> <c- nf><c- nf>await_suspend</c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>experimental</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>coroutine_handle</c-></c-><c- o><c- o>&lt;></c-></c-><c- p><c- p>);</c-></c->
  <c- n><c- n>T</c-></c-><c- o><c- o>&amp;&amp;</c-></c-> <c- n><c- n>await_resume</c-></c-><c- p><c- p>();</c-></c->

  <c- k><c- k>template</c-></c-><c- o><c- o>&lt;</c-></c-><c- k><c- k>typename</c-></c-> <c- n><c- n>Handler</c-></c-><c- p><c- p>,</c-></c-> <c- k><c- k>typename</c-></c-> <c- o><c- o>=</c-></c->
    <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>enable_if_t</c-></c-><c- o><c- o>&lt;</c-></c-><c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>is_invocable_r_v</c-></c-><c- o><c- o>&lt;</c-></c-><c- b><c- b>void</c-></c-><c- p><c- p>,</c-></c-> <c- n><c- n>Handler</c-></c-><c- p><c- p>,</c-></c-> <c- n><c- n>T</c-></c-><c- o><c- o>>>></c-></c->
  <c- b><c- b>void</c-></c-> <c- n><c- n>then</c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>Handler</c-></c-><c- o><c- o>&amp;&amp;</c-></c-><c- p><c- p>);</c-></c->
<c- p><c- p>};</c-></c->

<c- p><c- p>}</c-></c->
</code></pre>
   <h3 class="heading settled" data-level="5.2" id="buffer"><span class="secno">5.2. </span><span class="content"><code class="highlight"><c- n>net</c-><c- o>::</c-><c- n>buffer</c-></code></span><a class="self-link" href="#buffer"></a></h3>
    This object represents 0 or more sections of contiguous memory used for sending and receiving data. 
<pre class="highlight"><code class="highlight"><c- k><c- k>namespace</c-></c-> <c- n><c- n>net</c-></c-> <c- p><c- p>{</c-></c->

<c- k><c- k>class</c-></c-> <c- nc><c- nc>buffer</c-></c-> <c- p><c- p>{</c-></c->
<c- k><c- k>public</c-></c-><c- o><c- o>:</c-></c->
  <c- n><c- n>buffer</c-></c-><c- p><c- p>();</c-></c->
  <c- n><c- n>buffer</c-></c-><c- p><c- p>(</c-></c-><c- k><c- k>const</c-></c-> <c- b><c- b>void</c-></c-><c- o><c- o>*</c-></c-><c- p><c- p>,</c-></c-> <c- b><c- b>size_t</c-></c-><c- p><c- p>);</c-></c->
  <c- n><c- n>buffer</c-></c-><c- p><c- p>(</c-></c-><c- k><c- k>const</c-></c-> <c- b><c- b>char</c-></c-><c- o><c- o>*</c-></c-><c- p><c- p>);</c-></c->
  <c- n><c- n>buffer</c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>string_view</c-></c-><c- p><c- p>);</c-></c->
  <c- n><c- n>buffer</c-></c-><c- p><c- p>(</c-></c-><c- k><c- k>const</c-></c-> <c- n><c- n>buffer</c-></c-><c- o><c- o>&amp;</c-></c-><c- p><c- p>);</c-></c->
  <c- n><c- n>buffer</c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>buffer</c-></c-><c- o><c- o>&amp;&amp;</c-></c-><c- p><c- p>);</c-></c->
  <c- n><c- n>buffer</c-></c-><c- o><c- o>&amp;</c-></c-> <c- k><c- k>operator</c-></c-><c- o><c- o>=</c-></c-><c- p><c- p>(</c-></c-><c- k><c- k>const</c-></c-> <c- n><c- n>buffer</c-></c-><c- o><c- o>&amp;</c-></c-><c- p><c- p>);</c-></c->
  <c- n><c- n>buffer</c-></c-><c- o><c- o>&amp;</c-></c-> <c- k><c- k>operator</c-></c-><c- o><c- o>=</c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>buffer</c-></c-><c- o><c- o>&amp;&amp;</c-></c-><c- p><c- p>);</c-></c->

  <c- k><c- k>template</c-></c-><c- o><c- o>&lt;</c-></c-><c- k><c- k>typename</c-></c-> <c- n><c- n>Handler</c-></c-><c- p><c- p>,</c-></c-> <c- k><c- k>typename</c-></c-> <c- o><c- o>=</c-></c->
    <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>enable_if_t</c-></c-><c- o><c- o>&lt;</c-></c-><c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>is_invocable_r_v</c-></c-><c- o><c- o>&lt;</c-></c-><c- b><c- b>void</c-></c-><c- p><c- p>,</c-></c-> <c- n><c- n>Handler</c-></c-><c- p><c- p>,</c-></c-> <c- k><c- k>const</c-></c-> <c- b><c- b>uint8_t</c-></c-><c- o><c- o>*</c-></c-><c- p><c- p>,</c-></c-> <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- b><c- b>size_t</c-></c-><c- o><c- o>>>></c-></c->
  <c- b><c- b>void</c-></c-> <c- n><c- n>get</c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>Handler</c-></c-><c- o><c- o>&amp;&amp;</c-></c-> <c- n><c- n>handler</c-></c-><c- p><c- p>)</c-></c-> <c- k><c- k>const</c-></c-><c- p><c- p>;</c-></c->
<c- p><c- p>};</c-></c->

<c- p><c- p>}</c-></c->
</code></pre>
   <h3 class="heading settled" data-level="5.3" id="connection"><span class="secno">5.3. </span><span class="content"><code class="highlight"><c- n>net</c-><c- o>::</c-><c- n>connection</c-></code></span><a class="self-link" href="#connection"></a></h3>
   <p>This object represents a connection with an external client or server.  This connection can be used to send or receive messages.  Note that UDP also uses connections in this model even though UDP is a "connectionless" protocol.  This object still sends and receives UDP packets even though no handshake is necessary.</p>
   <p>The <code class="highlight"><c- n>receive</c-></code> method receives data even if the data is incomplete.  This is much more common on the internet, where streams of data that never complete are common.  The <code class="highlight"><c- n>receive_complete</c-></code> method will only resume the awaitable when the connected peer indicates the complete method has been sent.</p>
<pre class="highlight"><code class="highlight"><c- k><c- k>namespace</c-></c-> <c- n><c- n>net</c-></c-> <c- p><c- p>{</c-></c->

<c- k><c- k>class</c-></c-> <c- nc><c- nc>connection</c-></c-> <c- p><c- p>{</c-></c->
<c- k><c- k>public</c-></c-><c- o><c- o>:</c-></c->
  <c- k><c- k>enum</c-></c-> <c- k><c- k>class</c-></c-> <c- nc><c- nc>state</c-></c-> <c- p><c- p>{</c-></c->
    <c- n><c- n>setup</c-></c-><c- p><c- p>,</c-></c->
    <c- n><c- n>waiting</c-></c-><c- p><c- p>,</c-></c->
    <c- n><c- n>preparing</c-></c-><c- p><c- p>,</c-></c->
    <c- n><c- n>ready</c-></c-><c- p><c- p>,</c-></c->
    <c- n><c- n>failed</c-></c-><c- p><c- p>,</c-></c->
    <c- n><c- n>cancelled</c-></c->
  <c- p><c- p>};</c-></c->

  <c- n><c- n>connection</c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>endpoint</c-></c-><c- p><c- p>,</c-></c-> <c- n><c- n>parameters</c-></c-><c- p><c- p>,</c-></c-> <c- n><c- n>workqueue</c-></c-><c- p><c- p>);</c-></c->

  <c- k><c- k>template</c-></c-><c- o><c- o>&lt;</c-></c-><c- k><c- k>typename</c-></c-> <c- n><c- n>Handler</c-></c-><c- p><c- p>,</c-></c-> <c- k><c- k>typename</c-></c-> <c- o><c- o>=</c-></c->
    <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>enable_if_t</c-></c-><c- o><c- o>&lt;</c-></c-><c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>is_invocable_r_v</c-></c-><c- o><c- o>&lt;</c-></c-><c- b><c- b>void</c-></c-><c- p><c- p>,</c-></c-> <c- n><c- n>Handler</c-></c-><c- p><c- p>,</c-></c-> <c- n><c- n>state</c-></c-><c- p><c- p>,</c-></c-> <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>error_code</c-></c-><c- o><c- o>>>></c-></c->
  <c- n><c- n>connection</c-></c-><c- o><c- o>&amp;</c-></c-> <c- n><c- n>on_state_changed</c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>Handler</c-></c-><c- o><c- o>&amp;&amp;</c-></c-><c- p><c- p>);</c-></c->

  <c- k><c- k>template</c-></c-><c- o><c- o>&lt;</c-></c-><c- k><c- k>typename</c-></c-> <c- n><c- n>Handler</c-></c-><c- p><c- p>,</c-></c-> <c- k><c- k>typename</c-></c-> <c- o><c- o>=</c-></c->
    <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>enable_if_t</c-></c-><c- o><c- o>&lt;</c-></c-><c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>is_invocable_r_v</c-></c-><c- o><c- o>&lt;</c-></c-><c- b><c- b>void</c-></c-><c- p><c- p>,</c-></c-> <c- n><c- n>Handler</c-></c-><c- p><c- p>,</c-></c-> <c- b><c- b>bool</c-></c-><c- o><c- o>>>></c-></c->
  <c- n><c- n>connection</c-></c-><c- o><c- o>&amp;</c-></c-> <c- n><c- n>on_viability_changed</c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>Handler</c-></c-><c- o><c- o>&amp;&amp;</c-></c-><c- p><c- p>);</c-></c->

  <c- k><c- k>template</c-></c-><c- o><c- o>&lt;</c-></c-><c- k><c- k>typename</c-></c-> <c- n><c- n>Handler</c-></c-><c- p><c- p>,</c-></c-> <c- k><c- k>typename</c-></c-> <c- o><c- o>=</c-></c->
    <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>enable_if_t</c-></c-><c- o><c- o>&lt;</c-></c-><c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>is_invocable_r_v</c-></c-><c- o><c- o>&lt;</c-></c-><c- b><c- b>void</c-></c-><c- p><c- p>,</c-></c-> <c- n><c- n>Handler</c-></c-><c- p><c- p>,</c-></c-> <c- b><c- b>bool</c-></c-><c- o><c- o>>>></c-></c->
  <c- n><c- n>connection</c-></c-><c- o><c- o>&amp;</c-></c-> <c- n><c- n>on_better_path_changed</c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>Handler</c-></c-><c- o><c- o>&amp;&amp;</c-></c-><c- p><c- p>);</c-></c->

  <c- n><c- n>connection</c-></c-><c- o><c- o>&amp;</c-></c-> <c- n><c- n>start</c-></c-><c- p><c- p>();</c-></c->

  <c- n><c- n>awaitable</c-></c-><c- o><c- o>&lt;</c-></c-><c- n><c- n>expected</c-></c-><c- o><c- o>&lt;</c-></c-><c- b><c- b>void</c-></c-><c- p><c- p>,</c-></c-> <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>error_code</c-></c-><c- o><c- o>>></c-></c->
    <c- n><c- n>send</c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>message</c-></c-><c- p><c- p>);</c-></c->
  <c- n><c- n>awaitable</c-></c-><c- o><c- o>&lt;</c-></c-><c- n><c- n>expected</c-></c-><c- o><c- o>&lt;</c-></c-><c- b><c- b>void</c-></c-><c- p><c- p>,</c-></c-> <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>error_code</c-></c-><c- o><c- o>>></c-></c->
    <c- n><c- n>send</c-></c-><c- p><c- p>(</c-></c-><c- k><c- k>const</c-></c-> <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>vector</c-></c-><c- o><c- o>&lt;</c-></c-><c- n><c- n>protocol</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>metadata</c-></c-><c- o><c- o>>&amp;</c-></c-><c- p><c- p>,</c-></c-> <c- b><c- b>bool</c-></c-> <c- n><c- n>is_complete</c-></c-> <c- o><c- o>=</c-></c-> true<c- p><c- p>);</c-></c->
  <c- n><c- n>awaitable</c-></c-><c- o><c- o>&lt;</c-></c-><c- n><c- n>expected</c-></c-><c- o><c- o>&lt;</c-></c-><c- b><c- b>void</c-></c-><c- p><c- p>,</c-></c-> <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>error_code</c-></c-><c- o><c- o>>></c-></c->
    <c- n><c- n>send</c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>buffer</c-></c-><c- p><c- p>,</c-></c-> <c- k><c- k>const</c-></c-> <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>vector</c-></c-><c- o><c- o>&lt;</c-></c-><c- n><c- n>protocol</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>metadata</c-></c-><c- o><c- o>>&amp;</c-></c-><c- p><c- p>,</c-></c-> <c- b><c- b>bool</c-></c-> <c- n><c- n>is_complete</c-></c-> <c- o><c- o>=</c-></c-> true<c- p><c- p>)</c-></c->
  <c- n><c- n>awaitable</c-></c-><c- o><c- o>&lt;</c-></c-><c- n><c- n>expected</c-></c-><c- o><c- o>&lt;</c-></c-><c- b><c- b>void</c-></c-><c- p><c- p>,</c-></c-> <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>error_code</c-></c-><c- o><c- o>>></c-></c->
    <c- n><c- n>send</c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>buffer</c-></c-><c- p><c- p>,</c-></c-> <c- n><c- n>message</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>context</c-></c-><c- p><c- p>,</c-></c-> <c- b><c- b>bool</c-></c-> <c- n><c- n>is_complete</c-></c-> <c- o><c- o>=</c-></c-> true<c- p><c- p>)</c-></c->

  <c- n><c- n>awaitable</c-></c-><c- o><c- o>&lt;</c-></c-><c- n><c- n>expected</c-></c-><c- o><c- o>&lt;</c-></c-><c- n><c- n>message</c-></c-><c- p><c- p>,</c-></c-> <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>error_code</c-></c-><c- o><c- o>>></c-></c->
    <c- n><c- n>receive_complete</c-></c-><c- p><c- p>();</c-></c->
  <c- n><c- n>awaitable</c-></c-><c- o><c- o>&lt;</c-></c-><c- n><c- n>expected</c-></c-><c- o><c- o>&lt;</c-></c-><c- n><c- n>message</c-></c-><c- p><c- p>,</c-></c-> <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>error_code</c-></c-><c- o><c- o>>></c-></c->
    <c- n><c- n>receive</c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- b><c- b>size_t</c-></c-> <c- n><c- n>min_incomplete_length</c-></c-> <c- o><c- o>=</c-></c-> <c- mi><c- mi>1</c-></c-><c- p><c- p>,</c-></c->
      <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- b><c- b>size_t</c-></c-> <c- n><c- n>max_length</c-></c-> <c- o><c- o>=</c-></c-> <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>numeric_limits</c-></c-><c- o><c- o>&lt;</c-></c-><c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- b><c- b>size_t</c-></c-><c- o><c- o>>::</c-></c-><c- n><c- n>max</c-></c-><c- p><c- p>());</c-></c->
  <c- b><c- b>void</c-></c-> <c- nf><c- nf>cancel</c-></c-><c- p><c- p>();</c-></c->
<c- p><c- p>};</c-></c->

<c- p><c- p>}</c-></c->
</code></pre>
   <h3 class="heading settled" data-level="5.4" id="endpoint"><span class="secno">5.4. </span><span class="content"><code class="highlight"><c- n>net</c-><c- o>::</c-><c- n>endpoint</c-></code></span><a class="self-link" href="#endpoint"></a></h3>
    This object represents an endpoint to be connected with.  There are currently three types: host (such as <code class="highlight"><c- n>www</c-><c- p>.</c-><c- n>apple</c-><c- p>.</c-><c- n>com</c-></code>), address (such as <code class="highlight"><c- mf>127.0.0.1</c-></code>) and dnssd (such as a Bonjour service).  All three can be used to initiate a connection. 
<pre class="highlight"><code class="highlight"><c- k><c- k>namespace</c-></c-> <c- n><c- n>net</c-></c-> <c- p><c- p>{</c-></c->

<c- k><c- k>class</c-></c-> <c- nc><c- nc>endpoint</c-></c-> <c- p><c- p>{</c-></c->
<c- k><c- k>public</c-></c-><c- o><c- o>:</c-></c->
  <c- k><c- k>class</c-></c-> <c- nc><c- nc>host</c-></c-><c- p><c- p>;</c-></c->
  <c- k><c- k>class</c-></c-> <c- nc><c- nc>address</c-></c-><c- p><c- p>;</c-></c->
  <c- k><c- k>class</c-></c-> <c- nc><c- nc>dnssd</c-></c-><c- p><c- p>;</c-></c->
<c- p><c- p>};</c-></c->

<c- k><c- k>class</c-></c-> <c- nc><c- nc>endpoint</c-></c-><c- o><c- o>::</c-></c-><c- nl><c- nl>host</c-></c-> <c- p><c- p>:</c-></c-> <c- k><c- k>public</c-></c-> <c- n><c- n>endpoint</c-></c-> <c- p><c- p>{</c-></c->
<c- k><c- k>public</c-></c-><c- o><c- o>:</c-></c->
  <c- n><c- n>host</c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>string_view</c-></c-> <c- n><c- n>name</c-></c-><c- p><c- p>,</c-></c-> <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- b><c- b>uint16_t</c-></c-> <c- n><c- n>port</c-></c-><c- p><c- p>);</c-></c->
<c- p><c- p>};</c-></c->

<c- k><c- k>class</c-></c-> <c- nc><c- nc>endpoint</c-></c-><c- o><c- o>::</c-></c-><c- nl><c- nl>address</c-></c-> <c- p><c- p>:</c-></c-> <c- k><c- k>public</c-></c-> <c- n><c- n>endpoint</c-></c-> <c- p><c- p>{</c-></c->
<c- k><c- k>public</c-></c-><c- o><c- o>:</c-></c->
  <c- n><c- n>address</c-></c-><c- p><c- p>(</c-></c-><c- k><c- k>const</c-></c-> <c- n><c- n>sockaddr</c-></c-><c- o><c- o>&amp;</c-></c-><c- p><c- p>);</c-></c->
<c- p><c- p>};</c-></c->

<c- k><c- k>class</c-></c-> <c- nc><c- nc>endpoint</c-></c-><c- o><c- o>::</c-></c-><c- nl><c- nl>dnssd</c-></c-> <c- p><c- p>:</c-></c-> <c- k><c- k>public</c-></c-> <c- n><c- n>endpoint</c-></c-> <c- p><c- p>{</c-></c->
<c- k><c- k>public</c-></c-><c- o><c- o>:</c-></c->
  <c- n><c- n>dnssd</c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>string_view</c-></c-> <c- n><c- n>name</c-></c-><c- p><c- p>,</c-></c-> <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>string_view</c-></c-> <c- n><c- n>type</c-></c-><c- p><c- p>,</c-></c-> <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>string_view</c-></c-> <c- n><c- n>domain</c-></c-><c- p><c- p>);</c-></c->
<c- p><c- p>};</c-></c->

<c- p><c- p>}</c-></c->
</code></pre>
   <h3 class="heading settled" data-level="5.5" id="expected"><span class="secno">5.5. </span><span class="content"><code class="highlight"><c- n>net</c-><c- o>::</c-><c- n>expected</c-></code></span><a class="self-link" href="#expected"></a></h3>
    This object contains <a data-link-type="biblio" href="#biblio-p0323r7">[p0323r7]</a> in the <code class="highlight"><c- n>net</c-></code> namespace.  It is perfect for networking, when sending can either result in nothing or an error, and receiving can either result in a message or an error. It should be standardized and its references in the connection object should be changed to use <code class="highlight"><c- n>std</c-><c- o>::</c-><c- n>expected</c-></code> instead of <code class="highlight"><c- n>net</c-><c- o>::</c-><c- n>expected</c-></code>. 
   <h3 class="heading settled" data-level="5.6" id="interface"><span class="secno">5.6. </span><span class="content"><code class="highlight"><c- n>net</c-><c- o>::</c-><c- n>interface</c-></code></span><a class="self-link" href="#interface"></a></h3>
    This object represents a network interface, such as WiFi or ethernet.  Modern devices often have more than one such interface, and it is useful to be able to specify which one to use or to listen for events indicating when interface viability changes, such as when the WiFi is turned off but ethernet is still plugged in. 
<pre class="highlight"><code class="highlight"><c- k><c- k>namespace</c-></c-> <c- n><c- n>net</c-></c-> <c- p><c- p>{</c-></c->

<c- k><c- k>class</c-></c-> <c- nc><c- nc>interface</c-></c-> <c- p><c- p>{</c-></c->
<c- k><c- k>public</c-></c-><c- o><c- o>:</c-></c->
  <c- k><c- k>enum</c-></c-> <c- k><c- k>class</c-></c-> <c- nc><c- nc>type</c-></c-> <c- p><c- p>{</c-></c->
    <c- n><c- n>other</c-></c-><c- p><c- p>,</c-></c->
    <c- n><c- n>wifi</c-></c-><c- p><c- p>,</c-></c->
    <c- n><c- n>cellular</c-></c-><c- p><c- p>,</c-></c->
    <c- n><c- n>wired_ethernet</c-></c-><c- p><c- p>,</c-></c->
    <c- n><c- n>loopback</c-></c->
  <c- p><c- p>};</c-></c->

  <c- n><c- n>interface</c-></c-><c- p><c- p>(</c-></c-><c- k><c- k>const</c-></c-> <c- n><c- n>interface</c-></c-><c- o><c- o>&amp;</c-></c-><c- p><c- p>);</c-></c->
  <c- n><c- n>interface</c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>interface</c-></c-><c- o><c- o>&amp;&amp;</c-></c-><c- p><c- p>);</c-></c->
  <c- n><c- n>interface</c-></c-><c- o><c- o>&amp;</c-></c-> <c- k><c- k>operator</c-></c-><c- o><c- o>=</c-></c-><c- p><c- p>(</c-></c-><c- k><c- k>const</c-></c-> <c- n><c- n>interface</c-></c-><c- o><c- o>&amp;</c-></c-><c- p><c- p>);</c-></c->
  <c- n><c- n>interface</c-></c-><c- o><c- o>&amp;</c-></c-> <c- k><c- k>operator</c-></c-><c- o><c- o>=</c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>interface</c-></c-><c- o><c- o>&amp;&amp;</c-></c-><c- p><c- p>);</c-></c->

  <c- n><c- n>type</c-></c-> <c- nf><c- nf>type</c-></c-><c- p><c- p>()</c-></c-> <c- k><c- k>const</c-></c-><c- p><c- p>;</c-></c->
  <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>string</c-></c-> <c- n><c- n>name</c-></c-><c- p><c- p>()</c-></c-> <c- k><c- k>const</c-></c-><c- p><c- p>;</c-></c->
  <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- b><c- b>size_t</c-></c-> <c- n><c- n>index</c-></c-><c- p><c- p>()</c-></c-> <c- k><c- k>const</c-></c-><c- p><c- p>;</c-></c->
<c- p><c- p>};</c-></c->

<c- p><c- p>}</c-></c->
</code></pre>
   <h3 class="heading settled" data-level="5.7" id="listener"><span class="secno">5.7. </span><span class="content"><code class="highlight"><c- n>net</c-><c- o>::</c-><c- n>listener</c-></code></span><a class="self-link" href="#listener"></a></h3>
    This object that can be used to listen for incoming connections.  The constructor without a port receives a port assigned from the system, which can then be queried with the port getter. 
<pre class="highlight"><code class="highlight"><c- k><c- k>namespace</c-></c-> <c- n><c- n>net</c-></c-> <c- p><c- p>{</c-></c->

<c- k><c- k>class</c-></c-> <c- nc><c- nc>listener</c-></c-> <c- p><c- p>{</c-></c->
<c- k><c- k>public</c-></c-><c- o><c- o>:</c-></c->
  <c- k><c- k>enum</c-></c-> <c- k><c- k>class</c-></c-> <c- nc><c- nc>state</c-></c-> <c- p><c- p>{</c-></c->
    <c- n><c- n>setup</c-></c-><c- p><c- p>,</c-></c->
    <c- n><c- n>waiting</c-></c-><c- p><c- p>,</c-></c->
    <c- n><c- n>ready</c-></c-><c- p><c- p>,</c-></c->
    <c- n><c- n>failed</c-></c-><c- p><c- p>,</c-></c->
    <c- n><c- n>cancelled</c-></c->
  <c- p><c- p>};</c-></c->

  <c- n><c- n>listener</c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>parameters</c-></c-><c- p><c- p>,</c-></c-> <c- n><c- n>workqueue</c-></c-><c- p><c- p>);</c-></c->
  <c- n><c- n>listener</c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- b><c- b>uint16_t</c-></c-> <c- n><c- n>port</c-></c-><c- p><c- p>,</c-></c-> <c- n><c- n>parameters</c-></c-><c- p><c- p>,</c-></c-> <c- n><c- n>workqueue</c-></c-><c- p><c- p>);</c-></c->
  <c- n><c- n>listener</c-></c-><c- p><c- p>(</c-></c-><c- k><c- k>const</c-></c-> <c- n><c- n>listener</c-></c-><c- o><c- o>&amp;</c-></c-><c- p><c- p>);</c-></c->
  <c- n><c- n>listener</c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>listener</c-></c-><c- o><c- o>&amp;&amp;</c-></c-><c- p><c- p>);</c-></c->
  <c- n><c- n>listener</c-></c-><c- o><c- o>&amp;</c-></c-> <c- k><c- k>operator</c-></c-><c- o><c- o>=</c-></c-><c- p><c- p>(</c-></c-><c- k><c- k>const</c-></c-> <c- n><c- n>listener</c-></c-><c- o><c- o>&amp;</c-></c-><c- p><c- p>);</c-></c->
  <c- n><c- n>listener</c-></c-><c- o><c- o>&amp;</c-></c-> <c- k><c- k>operator</c-></c-><c- o><c- o>=</c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>listener</c-></c-><c- o><c- o>&amp;&amp;</c-></c-><c- p><c- p>);</c-></c->

  <c- k><c- k>template</c-></c-><c- o><c- o>&lt;</c-></c-><c- k><c- k>typename</c-></c-> <c- n><c- n>Handler</c-></c-><c- p><c- p>,</c-></c-> <c- k><c- k>typename</c-></c-> <c- o><c- o>=</c-></c->
    <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>enable_if_t</c-></c-><c- o><c- o>&lt;</c-></c-><c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>is_invocable_r_v</c-></c-><c- o><c- o>&lt;</c-></c-><c- b><c- b>void</c-></c-><c- p><c- p>,</c-></c-> <c- n><c- n>Handler</c-></c-><c- p><c- p>,</c-></c-> <c- n><c- n>connection</c-></c-><c- o><c- o>>>></c-></c->
  <c- n><c- n>listener</c-></c-><c- o><c- o>&amp;</c-></c-> <c- n><c- n>on_new_connection</c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>Handler</c-></c-><c- o><c- o>&amp;&amp;</c-></c-><c- p><c- p>);</c-></c->

  <c- k><c- k>template</c-></c-><c- o><c- o>&lt;</c-></c-><c- k><c- k>typename</c-></c-> <c- n><c- n>Handler</c-></c-><c- p><c- p>,</c-></c-> <c- k><c- k>typename</c-></c-> <c- o><c- o>=</c-></c->
    <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>enable_if_t</c-></c-><c- o><c- o>&lt;</c-></c-><c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>is_invocable_r_v</c-></c-><c- o><c- o>&lt;</c-></c-><c- b><c- b>void</c-></c-><c- p><c- p>,</c-></c-> <c- n><c- n>Handler</c-></c-><c- p><c- p>,</c-></c-> <c- n><c- n>state</c-></c-><c- p><c- p>,</c-></c-> <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>error_code</c-></c-><c- o><c- o>>>></c-></c->
  <c- n><c- n>listener</c-></c-><c- o><c- o>&amp;</c-></c-> <c- n><c- n>on_state_changed</c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>Handler</c-></c-><c- o><c- o>&amp;&amp;</c-></c-><c- p><c- p>);</c-></c->

  <c- b><c- b>void</c-></c-> <c- nf><c- nf>start</c-></c-><c- p><c- p>();</c-></c->
  <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- b><c- b>uint16_t</c-></c-> <c- n><c- n>port</c-></c-><c- p><c- p>()</c-></c-> <c- k><c- k>const</c-></c-><c- p><c- p>;</c-></c->
<c- p><c- p>};</c-></c->

<c- p><c- p>}</c-></c->
</code></pre>
   <h3 class="heading settled" data-level="5.8" id="messagecontext"><span class="secno">5.8. </span><span class="content"><code class="highlight"><c- n>net</c-><c- o>::</c-><c- n>message</c-><c- o>::</c-><c- n>context</c-></code></span><a class="self-link" href="#messagecontext"></a></h3>
    This object represents a set of protocol metadata associated with the act of
sending or receiving data on a connection. 
<pre class="highlight"><code class="highlight"><c- k><c- k>namespace</c-></c-> <c- n><c- n>net</c-></c-> <c- p><c- p>{</c-></c->

<c- k><c- k>class</c-></c-> <c- nc><c- nc>message</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>context</c-></c-> <c- p><c- p>{</c-></c->
<c- k><c- k>public</c-></c-><c- o><c- o>:</c-></c->

    <c- k><c- k>static</c-></c-> <c- n><c- n>context</c-></c-> <c- n><c- n>final_message</c-></c-><c- p><c- p>();</c-></c->
    <c- k><c- k>static</c-></c-> <c- n><c- n>context</c-></c-> <c- nf><c- nf>default_stream</c-></c-><c- p><c- p>();</c-></c->
    <c- k><c- k>static</c-></c-> <c- n><c- n>context</c-></c-> <c- nf><c- nf>default_message</c-></c-><c- p><c- p>();</c-></c->

    <c- n><c- n>context</c-></c-><c- p><c- p>();</c-></c->

    <c- k><c- k>template</c-></c-><c- o><c- o>&lt;</c-></c-><c- k><c- k>typename</c-></c-> <c- n><c- n>Protocol</c-></c-><c- o><c- o>></c-></c-> <c- k><c- k>typename</c-></c-> <c- n><c- n>Protocol</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>metadata</c-></c-> <c- n><c- n>metadata</c-></c-><c- p><c- p>();</c-></c->

    <c- k><c- k>template</c-></c-><c- o><c- o>&lt;</c-></c-><c- k><c- k>typename</c-></c-> <c- n><c- n>Protocol</c-></c-><c- o><c- o>></c-></c-> <c- k><c- k>const</c-></c-> <c- k><c- k>typename</c-></c-> <c- n><c- n>Protocol</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>metadata</c-></c-> <c- n><c- n>metadata</c-></c-><c- p><c- p>()</c-></c-> <c- k><c- k>const</c-></c-><c- p><c- p>;</c-></c->

    <c- b><c- b>void</c-></c-> <c- nf><c- nf>set_metadata</c-></c-><c- p><c- p>(</c-></c-><c- k><c- k>const</c-></c-> <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>vector</c-></c-><c- o><c- o>&lt;</c-></c-><c- n><c- n>protocol</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>metadata</c-></c-><c- o><c- o>>&amp;</c-></c-><c- p><c- p>);</c-></c->

    <c- b><c- b>bool</c-></c-> <c- nf><c- nf>is_final</c-></c-><c- p><c- p>()</c-></c-> <c- k><c- k>const</c-></c-><c- p><c- p>;</c-></c->

    <c- b><c- b>void</c-></c-> <c- nf><c- nf>set_is_final</c-></c-><c- p><c- p>(</c-></c-><c- b><c- b>bool</c-></c-><c- p><c- p>);</c-></c->
  <c- p><c- p>};</c-></c->
<c- p><c- p>}</c-></c->
</code></pre>
   <h3 class="heading settled" data-level="5.9" id="message"><span class="secno">5.9. </span><span class="content"><code class="highlight"><c- n>net</c-><c- o>::</c-><c- n>message</c-></code></span><a class="self-link" href="#message"></a></h3>
    This object represents a message sent or received on the network. Messages have an associated context, data, and 
a flag denoting whether this message can be considered complete (<code class="highlight"><c- n>is_complete</c-></code>). Messages that are marked as complete
will close the underlying connection if the context associated with the message is marked as final. For example, TCP
will issue a FIN if a message is marked as complete and the context associated with the message is marked as final. 
<pre class="highlight"><code class="highlight"><c- k><c- k>namespace</c-></c-> <c- n><c- n>net</c-></c-> <c- p><c- p>{</c-></c->

<c- k><c- k>class</c-></c-> <c- nc><c- nc>message</c-></c-> <c- p><c- p>{</c-></c->
<c- k><c- k>public</c-></c-><c- o><c- o>:</c-></c->
  <c- n><c- n>message</c-></c-><c- p><c- p>();</c-></c->
  <c- n><c- n>message</c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>buffer</c-></c-><c- p><c- p>,</c-></c-> <c- b><c- b>bool</c-></c-> <c- n><c- n>is_complete</c-></c-> <c- o><c- o>=</c-></c-> true<c- p><c- p>);</c-></c->
  <c- n><c- n>message</c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>buffer</c-></c-><c- p><c- p>,</c-></c-> <c- n><c- n>context</c-></c-><c- p><c- p>,</c-></c-> <c- b><c- b>bool</c-></c-> <c- n><c- n>is_complete</c-></c-> <c- o><c- o>=</c-></c-> true<c- p><c- p>)</c-></c->
  <c- n><c- n>message</c-></c-><c- p><c- p>(</c-></c-><c- k><c- k>const</c-></c-> <c- n><c- n>message</c-></c-><c- o><c- o>&amp;</c-></c-><c- p><c- p>);</c-></c->
  <c- n><c- n>message</c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>message</c-></c-><c- o><c- o>&amp;&amp;</c-></c-><c- p><c- p>);</c-></c->
  <c- n><c- n>message</c-></c-><c- o><c- o>&amp;</c-></c-> <c- k><c- k>operator</c-></c-><c- o><c- o>=</c-></c-><c- p><c- p>(</c-></c-><c- k><c- k>const</c-></c-> <c- n><c- n>message</c-></c-><c- o><c- o>&amp;</c-></c-><c- p><c- p>);</c-></c->
  <c- n><c- n>message</c-></c-><c- o><c- o>&amp;</c-></c-> <c- k><c- k>operator</c-></c-><c- o><c- o>=</c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>message</c-></c-><c- o><c- o>&amp;&amp;</c-></c-><c- p><c- p>);</c-></c->

  <c- k><c- k>template</c-></c-><c- o><c- o>&lt;</c-></c-><c- k><c- k>typename</c-></c-> <c- n><c- n>Protocol</c-></c-><c- o><c- o>></c-></c->
  <c- k><c- k>typename</c-></c-> <c- n><c- n>Protocol</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>metadata</c-></c-> <c- n><c- n>metadata</c-></c-><c- p><c- p>();</c-></c->
  <c- k><c- k>template</c-></c-><c- o><c- o>&lt;</c-></c-><c- k><c- k>typename</c-></c-> <c- n><c- n>Protocol</c-></c-><c- o><c- o>></c-></c->
  <c- k><c- k>const</c-></c-> <c- k><c- k>typename</c-></c-> <c- n><c- n>Protocol</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>metadata</c-></c-> <c- n><c- n>metadata</c-></c-><c- p><c- p>()</c-></c-> <c- k><c- k>const</c-></c-><c- p><c- p>;</c-></c->

  <c- n><c- n>context</c-></c-> <c- nf><c- nf>get_context</c-></c-><c- p><c- p>()</c-></c-> <c- k><c- k>const</c-></c-><c- p><c- p>;</c-></c->
  <c- n><c- n>buffer</c-></c-> <c- nf><c- nf>data</c-></c-><c- p><c- p>()</c-></c-> <c- k><c- k>const</c-></c-><c- p><c- p>;</c-></c->
  <c- b><c- b>bool</c-></c-> <c- nf><c- nf>is_complete</c-></c-><c- p><c- p>()</c-></c-> <c- k><c- k>const</c-></c-><c- p><c- p>;</c-></c->
<c- p><c- p>};</c-></c->

<c- p><c- p>}</c-></c->
</code></pre>
   <h3 class="heading settled" data-level="5.10" id="parameters"><span class="secno">5.10. </span><span class="content"><code class="highlight"><c- n>net</c-><c- o>::</c-><c- n>parameters</c-></code></span><a class="self-link" href="#parameters"></a></h3>
    This object represents parameters for network protocols. 
<pre class="highlight"><code class="highlight"><c- k><c- k>namespace</c-></c-> <c- n><c- n>net</c-></c-> <c- p><c- p>{</c-></c->

<c- k><c- k>class</c-></c-> <c- nc><c- nc>parameters</c-></c-> <c- p><c- p>{</c-></c->
<c- k><c- k>public</c-></c-><c- o><c- o>:</c-></c->
  <c- k><c- k>enum</c-></c-> <c- k><c- k>class</c-></c-> <c- nc><c- nc>multipath_service_type</c-></c-> <c- p><c- p>{</c-></c->
    <c- n><c- n>disabled</c-></c-><c- p><c- p>,</c-></c->
    <c- n><c- n>handover</c-></c-><c- p><c- p>,</c-></c->
    <c- n><c- n>interactive</c-></c-><c- p><c- p>,</c-></c->
    <c- n><c- n>aggregate</c-></c->
  <c- p><c- p>};</c-></c->
  <c- k><c- k>enum</c-></c-> <c- k><c- k>class</c-></c-> <c- nc><c- nc>expired_dns_behavior</c-></c-> <c- p><c- p>{</c-></c->
    <c- n><c- n>system_default</c-></c-><c- p><c- p>,</c-></c->
    <c- n><c- n>allow</c-></c-><c- p><c- p>,</c-></c->
    <c- n><c- n>prohibit</c-></c->
  <c- p><c- p>};</c-></c->

  <c- k><c- k>static</c-></c-> <c- n><c- n>parameters</c-></c-> <c- nf><c- nf>tls</c-></c-><c- p><c- p>();</c-></c->
  <c- k><c- k>static</c-></c-> <c- n><c- n>parameters</c-></c-> <c- nf><c- nf>dtls</c-></c-><c- p><c- p>();</c-></c->

  <c- k><c- k>static</c-></c-> <c- n><c- n>parameters</c-></c-> <c- nf><c- nf>tcp</c-></c-><c- p><c- p>();</c-></c->
  <c- k><c- k>static</c-></c-> <c- n><c- n>parameters</c-></c-> <c- nf><c- nf>udp</c-></c-><c- p><c- p>();</c-></c->

  <c- n><c- n>parameters</c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>protocol</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>security</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>options</c-></c-><c- p><c- p>,</c-></c-> <c- n><c- n>protocol</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>tcp</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>options</c-></c-><c- p><c- p>);</c-></c->
  <c- n><c- n>parameters</c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>protocol</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>security</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>options</c-></c-><c- p><c- p>,</c-></c-> <c- n><c- n>protocol</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>udp</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>options</c-></c-><c- p><c- p>);</c-></c->

  <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>vector</c-></c-><c- o><c- o>&lt;</c-></c-><c- n><c- n>protocol</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>options</c-></c-><c- o><c- o>></c-></c-> <c- n><c- n>application_protocols</c-></c-><c- p><c- p>()</c-></c-> <c- k><c- k>const</c-></c-><c- p><c- p>;</c-></c->
  <c- n><c- n>parameters</c-></c-><c- o><c- o>&amp;</c-></c-> <c- n><c- n>set_application_protocols</c-></c-><c- p><c- p>(</c-></c-><c- k><c- k>const</c-></c-> <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>vector</c-></c-><c- o><c- o>&lt;</c-></c-><c- n><c- n>protocol</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>options</c-></c-><c- o><c- o>>&amp;</c-></c-><c- p><c- p>);</c-></c->

  <c- n><c- n>interface</c-></c-> <c- nf><c- nf>require_interface</c-></c-><c- p><c- p>()</c-></c-> <c- k><c- k>const</c-></c-><c- p><c- p>;</c-></c->
  <c- n><c- n>parameters</c-></c-><c- o><c- o>&amp;</c-></c-> <c- n><c- n>set_require_interface</c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>interface</c-></c-><c- p><c- p>);</c-></c->

  <c- k><c- k>enum</c-></c-> <c- n><c- n>interface</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>type</c-></c-> <c- n><c- n>required_interface_type</c-></c-><c- p><c- p>()</c-></c-> <c- k><c- k>const</c-></c-><c- p><c- p>;</c-></c->
  <c- n><c- n>parameters</c-></c-><c- o><c- o>&amp;</c-></c-> <c- n><c- n>set_required_interface_type</c-></c-><c- p><c- p>(</c-></c-><c- k><c- k>enum</c-></c-> <c- n><c- n>interface</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>type</c-></c-><c- p><c- p>);</c-></c->

  <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>vector</c-></c-><c- o><c- o>&lt;</c-></c-><c- n><c- n>interface</c-></c-><c- o><c- o>></c-></c-> <c- n><c- n>prohibited_interfaces</c-></c-><c- p><c- p>()</c-></c-> <c- k><c- k>const</c-></c-><c- p><c- p>;</c-></c->
  <c- n><c- n>parameters</c-></c-><c- o><c- o>&amp;</c-></c-> <c- n><c- n>set_prohibited_interfaces</c-></c-><c- p><c- p>(</c-></c-><c- k><c- k>const</c-></c-> <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>vector</c-></c-><c- o><c- o>&lt;</c-></c-><c- n><c- n>interface</c-></c-><c- o><c- o>>&amp;</c-></c-><c- p><c- p>);</c-></c->

  <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>vector</c-></c-><c- o><c- o>&lt;</c-></c-><c- k><c- k>enum</c-></c-> <c- n><c- n>interface</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>type</c-></c-><c- o><c- o>></c-></c-> <c- n><c- n>prohibited_interface_types</c-></c-><c- p><c- p>()</c-></c-> <c- k><c- k>const</c-></c-><c- p><c- p>;</c-></c->
  <c- n><c- n>parameters</c-></c-><c- o><c- o>&amp;</c-></c-> <c- n><c- n>set_prohibited_interface_types</c-></c-><c- p><c- p>(</c-></c-><c- k><c- k>const</c-></c-> <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>vector</c-></c-><c- o><c- o>&lt;</c-></c-><c- k><c- k>enum</c-></c-> <c- n><c- n>interface</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>type</c-></c-><c- o><c- o>>&amp;</c-></c-><c- p><c- p>);</c-></c->

  <c- b><c- b>bool</c-></c-> <c- nf><c- nf>prohibit_constrained_paths</c-></c-><c- p><c- p>()</c-></c-> <c- k><c- k>const</c-></c-><c- p><c- p>;</c-></c->
  <c- n><c- n>parameters</c-></c-><c- o><c- o>&amp;</c-></c-> <c- n><c- n>set_prohibit_constrained_paths</c-></c-><c- p><c- p>(</c-></c-><c- b><c- b>bool</c-></c-><c- p><c- p>);</c-></c->

  <c- b><c- b>bool</c-></c-> <c- nf><c- nf>prefer_no_proxies</c-></c-><c- p><c- p>()</c-></c-> <c- k><c- k>const</c-></c-><c- p><c- p>;</c-></c->
  <c- n><c- n>parameters</c-></c-><c- o><c- o>&amp;</c-></c-> <c- n><c- n>set_prefer_no_proxies</c-></c-><c- p><c- p>(</c-></c-><c- b><c- b>bool</c-></c-><c- p><c- p>);</c-></c->

  <c- n><c- n>endpoint</c-></c-> <c- nf><c- nf>required_local_endpoint</c-></c-><c- p><c- p>()</c-></c-> <c- k><c- k>const</c-></c-><c- p><c- p>;</c-></c->
  <c- n><c- n>parameters</c-></c-><c- o><c- o>&amp;</c-></c-> <c- n><c- n>set_required_local_endpoint</c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>endpoint</c-></c-><c- p><c- p>);</c-></c->

  <c- b><c- b>bool</c-></c-> <c- nf><c- nf>allow_local_endpoint_reuse</c-></c-><c- p><c- p>()</c-></c-> <c- k><c- k>const</c-></c-><c- p><c- p>;</c-></c->
  <c- n><c- n>parameters</c-></c-><c- o><c- o>&amp;</c-></c-> <c- n><c- n>set_allow_local_endpoint_reuse</c-></c-><c- p><c- p>(</c-></c-><c- b><c- b>bool</c-></c-><c- p><c- p>);</c-></c->

  <c- b><c- b>bool</c-></c-> <c- nf><c- nf>accept_local_only</c-></c-><c- p><c- p>()</c-></c-> <c- k><c- k>const</c-></c-><c- p><c- p>;</c-></c->
  <c- n><c- n>parameters</c-></c-><c- o><c- o>&amp;</c-></c-> <c- n><c- n>set_accept_local_only</c-></c-><c- p><c- p>(</c-></c-><c- b><c- b>bool</c-></c-><c- p><c- p>);</c-></c->

  <c- b><c- b>bool</c-></c-> <c- nf><c- nf>include_peer_to_peer</c-></c-><c- p><c- p>()</c-></c-> <c- k><c- k>const</c-></c-><c- p><c- p>;</c-></c->
  <c- n><c- n>parameters</c-></c-><c- o><c- o>&amp;</c-></c-> <c- n><c- n>set_include_peer_to_peer</c-></c-><c- p><c- p>(</c-></c-><c- b><c- b>bool</c-></c-><c- p><c- p>);</c-></c->

  <c- k><c- k>enum</c-></c-> <c- n><c- n>multipath_service_type</c-></c-> <c- nf><c- nf>multipath_service_type</c-></c-><c- p><c- p>()</c-></c-> <c- k><c- k>const</c-></c-><c- p><c- p>;</c-></c->
  <c- n><c- n>parameters</c-></c-><c- o><c- o>&amp;</c-></c-> <c- n><c- n>set_multipath_service_type</c-></c-><c- p><c- p>(</c-></c-><c- b><c- b>bool</c-></c-><c- p><c- p>);</c-></c->

  <c- b><c- b>bool</c-></c-> <c- nf><c- nf>allow_fast_open</c-></c-><c- p><c- p>()</c-></c-> <c- k><c- k>const</c-></c-><c- p><c- p>;</c-></c->
  <c- n><c- n>parameters</c-></c-><c- o><c- o>&amp;</c-></c-> <c- n><c- n>set_allow_fast_open</c-></c-><c- p><c- p>(</c-></c-><c- b><c- b>bool</c-></c-><c- p><c- p>);</c-></c->

  <c- k><c- k>enum</c-></c-> <c- n><c- n>expired_dns_behavior</c-></c-> <c- nf><c- nf>expired_dns_behavior</c-></c-><c- p><c- p>()</c-></c-> <c- k><c- k>const</c-></c-><c- p><c- p>;</c-></c->
  <c- n><c- n>parameters</c-></c-><c- o><c- o>&amp;</c-></c-> <c- n><c- n>set_expired_dns_behavior</c-></c-><c- p><c- p>(</c-></c-><c- k><c- k>enum</c-></c-> <c- n><c- n>expired_dns_behavior</c-></c-><c- p><c- p>);</c-></c->
<c- p><c- p>};</c-></c->

<c- p><c- p>}</c-></c->
</code></pre>
   <h3 class="heading settled" data-level="5.11" id="path"><span class="secno">5.11. </span><span class="content"><code class="highlight"><c- n>net</c-><c- o>::</c-><c- n>path</c-></code></span><a class="self-link" href="#path"></a></h3>
    This object represents the known information about a local interface and routes that may
be used to send and receive data. 
<pre class="highlight"><code class="highlight"><c- k><c- k>namespace</c-></c-> <c- n><c- n>net</c-></c-> <c- p><c- p>{</c-></c->

<c- k><c- k>class</c-></c-> <c- nc><c- nc>path</c-></c-> <c- p><c- p>{</c-></c->
<c- k><c- k>public</c-></c-><c- o><c- o>:</c-></c->
  <c- k><c- k>enum</c-></c-> <c- k><c- k>class</c-></c-> <c- nc><c- nc>status</c-></c-> <c- p><c- p>{</c-></c->
    <c- n><c- n>satisfied</c-></c-><c- p><c- p>,</c-></c->
    <c- n><c- n>unsatisfied</c-></c-><c- p><c- p>,</c-></c->
    <c- n><c- n>requires_connection</c-></c-><c- p><c- p>,</c-></c->
  <c- p><c- p>};</c-></c->

  <c- n><c- n>path</c-></c-><c- p><c- p>(</c-></c-><c- k><c- k>const</c-></c-> <c- n><c- n>path</c-></c-><c- o><c- o>&amp;</c-></c-><c- p><c- p>);</c-></c->
  <c- n><c- n>path</c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>path</c-></c-><c- o><c- o>&amp;&amp;</c-></c-><c- p><c- p>)</c-></c->
  <c- n><c- n>path</c-></c-><c- o><c- o>&amp;</c-></c-> <c- k><c- k>operator</c-></c-><c- o><c- o>=</c-></c-><c- p><c- p>(</c-></c-><c- k><c- k>const</c-></c-> <c- n><c- n>path</c-></c-><c- o><c- o>&amp;</c-></c-><c- p><c- p>);</c-></c->
  <c- n><c- n>path</c-></c-><c- o><c- o>&amp;</c-></c-> <c- k><c- k>operator</c-></c-><c- o><c- o>=</c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>path</c-></c-><c- o><c- o>&amp;&amp;</c-></c-><c- p><c- p>);</c-></c->
  <c- b><c- b>bool</c-></c-> <c- k><c- k>operator</c-></c-><c- o><c- o>==</c-></c-><c- p><c- p>(</c-></c-><c- k><c- k>const</c-></c-> <c- n><c- n>path</c-></c-><c- o><c- o>&amp;</c-></c-><c- p><c- p>)</c-></c-> <c- k><c- k>const</c-></c-><c- p><c- p>;</c-></c->

  <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>vector</c-></c-><interface> <c- n><c- n>available_interfaces</c-></c-><c- p><c- p>()</c-></c-> <c- k><c- k>const</c-></c-><c- p><c- p>;</c-></c->
  <c- b><c- b>bool</c-></c-> <c- nf><c- nf>is_constrained</c-></c-><c- p><c- p>()</c-></c-> <c- k><c- k>const</c-></c-><c- p><c- p>;</c-></c->
  <c- b><c- b>bool</c-></c-> <c- nf><c- nf>has_ipv4</c-></c-><c- p><c- p>()</c-></c-> <c- k><c- k>const</c-></c-><c- p><c- p>;</c-></c->
  <c- b><c- b>bool</c-></c-> <c- nf><c- nf>has_ipv6</c-></c-><c- p><c- p>()</c-></c-> <c- k><c- k>const</c-></c-><c- p><c- p>;</c-></c->
  <c- b><c- b>bool</c-></c-> <c- nf><c- nf>has_dns</c-></c-><c- p><c- p>()</c-></c-> <c- k><c- k>const</c-></c-><c- p><c- p>;</c-></c->
  <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>vector</c-></c-><c- o><c- o>&lt;</c-></c-><c- n><c- n>endpoint</c-></c-><c- o><c- o>></c-></c-> <c- n><c- n>gateways</c-></c-><c- p><c- p>()</c-></c-> <c- k><c- k>const</c-></c-><c- p><c- p>;</c-></c->
  <c- n><c- n>endpoint</c-></c-> <c- nf><c- nf>local_endpoint</c-></c-><c- p><c- p>()</c-></c-> <c- k><c- k>const</c-></c-><c- p><c- p>;</c-></c->
  <c- n><c- n>endpoint</c-></c-> <c- nf><c- nf>remote_endpoint</c-></c-><c- p><c- p>()</c-></c-> <c- k><c- k>const</c-></c-><c- p><c- p>;</c-></c->
  <c- b><c- b>bool</c-></c-> <c- nf><c- nf>uses_interface_type</c-></c-><c- p><c- p>(</c-></c-><c- k><c- k>enum</c-></c-> <c- n><c- n>interface</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>type</c-></c-> <c- n><c- n>type</c-></c-><c- p><c- p>)</c-></c-> <c- k><c- k>const</c-></c-><c- p><c- p>;</c-></c->
  <c- n><c- n>status</c-></c-> <c- nf><c- nf>status</c-></c-><c- p><c- p>()</c-></c-> <c- k><c- k>const</c-></c-><c- p><c- p>;</c-></c->
<c- p><c- p>};</c-></c->

<c- p><c- p>}</c-></c->
</interface></code></pre>
   <h3 class="heading settled" data-level="5.12" id="pathmonitor"><span class="secno">5.12. </span><span class="content"><code class="highlight"><c- n>net</c-><c- o>::</c-><c- n>path_monitor</c-></code></span><a class="self-link" href="#pathmonitor"></a></h3>
    This object can be used to listen to events related to changing network conditions. 
<pre class="highlight"><code class="highlight"><c- k><c- k>namespace</c-></c-> <c- n><c- n>net</c-></c-> <c- p><c- p>{</c-></c->

<c- k><c- k>class</c-></c-> <c- nc><c- nc>path_monitor</c-></c-> <c- p><c- p>{</c-></c->
<c- k><c- k>public</c-></c-><c- o><c- o>:</c-></c->
  <c- n><c- n>path_monitor</c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>workqueue</c-></c-> <c- n><c- n>queue</c-></c-><c- p><c- p>);</c-></c->
  <c- n><c- n>path_monitor</c-></c-><c- p><c- p>(</c-></c-><c- k><c- k>enum</c-></c-> <c- n><c- n>interface</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>type</c-></c-> <c- n><c- n>type</c-></c-><c- p><c- p>,</c-></c-> <c- n><c- n>workqueue</c-></c-> <c- n><c- n>queue</c-></c-><c- p><c- p>);</c-></c->

  <c- k><c- k>template</c-></c-><c- o><c- o>&lt;</c-></c-><c- k><c- k>typename</c-></c-> <c- n><c- n>Handler</c-></c-><c- p><c- p>,</c-></c-> <c- k><c- k>typename</c-></c-> <c- o><c- o>=</c-></c->
    <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>enable_if_t</c-></c-><c- o><c- o>&lt;</c-></c-><c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>is_invocable_r_v</c-></c-><c- o><c- o>&lt;</c-></c-><c- b><c- b>void</c-></c-><c- p><c- p>,</c-></c-> <c- n><c- n>Handler</c-></c-><c- p><c- p>,</c-></c-> <c- n><c- n>path</c-></c-><c- o><c- o>>>></c-></c->
  <c- n><c- n>path_monitor</c-></c-><c- o><c- o>&amp;</c-></c-> <c- n><c- n>on_update</c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>Handler</c-></c-><c- o><c- o>&amp;&amp;</c-></c-><c- p><c- p>);</c-></c->
<c- p><c- p>};</c-></c->

<c- p><c- p>}</c-></c->
</code></pre>
   <h3 class="heading settled" data-level="5.13" id="protocol"><span class="secno">5.13. </span><span class="content"><code class="highlight"><c- n>net</c-><c- o>::</c-><c- n>protocol</c-></code></span><a class="self-link" href="#protocol"></a></h3>
    These objects contain the network protocol definitions, as well as their metadata and options. 
<pre class="highlight"><code class="highlight"><c- k><c- k>namespace</c-></c-> <c- n><c- n>net</c-></c-> <c- p><c- p>{</c-></c->

<c- k><c- k>class</c-></c-> <c- nc><c- nc>protocol</c-></c-> <c- p><c- p>{</c-></c->
<c- k><c- k>public</c-></c-><c- o><c- o>:</c-></c->
  <c- k><c- k>class</c-></c-> <c- nc><c- nc>definition</c-></c-> <c- p><c- p>{</c-></c->
  <c- k><c- k>public</c-></c-><c- o><c- o>:</c-></c->
    <c- b><c- b>bool</c-></c-> <c- k><c- k>operator</c-></c-><c- o><c- o>==</c-></c-><c- p><c- p>(</c-></c-><c- k><c- k>const</c-></c-> <c- n><c- n>definition</c-></c-><c- o><c- o>&amp;</c-></c-><c- p><c- p>)</c-></c-> <c- k><c- k>const</c-></c-><c- p><c- p>;</c-></c->
  <c- p><c- p>};</c-></c->

  <c- k><c- k>class</c-></c-> <c- nc><c- nc>options</c-></c-> <c- p><c- p>{</c-></c->
  <c- p><c- p>};</c-></c->

  <c- k><c- k>class</c-></c-> <c- nc><c- nc>metadata</c-></c-> <c- p><c- p>{</c-></c->
  <c- k><c- k>protected</c-></c-><c- o><c- o>:</c-></c->
    <c- n><c- n>metadata</c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>message</c-></c-><c- p><c- p>,</c-></c-> <c- n><c- n>definition</c-></c-><c- p><c- p>);</c-></c->
  <c- p><c- p>};</c-></c->

  <c- k><c- k>class</c-></c-> <c- nc><c- nc>ip</c-></c-><c- p><c- p>;</c-></c->
  <c- k><c- k>class</c-></c-> <c- nc><c- nc>tcp</c-></c-><c- p><c- p>;</c-></c->
  <c- k><c- k>class</c-></c-> <c- nc><c- nc>udp</c-></c-><c- p><c- p>;</c-></c->
  <c- k><c- k>class</c-></c-> <c- nc><c- nc>security</c-></c-><c- p><c- p>;</c-></c->
<c- p><c- p>};</c-></c->

<c- k><c- k>class</c-></c-> <c- nc><c- nc>protocol</c-></c-><c- o><c- o>::</c-></c-><c- nl><c- nl>ip</c-></c-> <c- p><c- p>:</c-></c-> <c- k><c- k>public</c-></c-> <c- n><c- n>protocol</c-></c-> <c- p><c- p>{</c-></c->
<c- k><c- k>public</c-></c-><c- o><c- o>:</c-></c->
  <c- k><c- k>static</c-></c-> <c- n><c- n>protocol</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>definition</c-></c-> <c- n><c- n>definition</c-></c-><c- p><c- p>();</c-></c->

  <c- k><c- k>class</c-></c-> <c- nc><c- nc>options</c-></c-> <c- o><c- o>:</c-></c-> <c- k><c- k>public</c-></c-> <c- n><c- n>protocol</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>options</c-></c-> <c- p><c- p>{</c-></c->
  <c- k><c- k>public</c-></c-><c- o><c- o>:</c-></c->
    <c- k><c- k>enum</c-></c-> <c- k><c- k>class</c-></c-> <c- nc><c- nc>version</c-></c-> <c- p><c- p>{</c-></c->
      <c- n><c- n>any</c-></c-><c- p><c- p>,</c-></c->
      <c- n><c- n>v4</c-></c-><c- p><c- p>,</c-></c->
      <c- n><c- n>v6</c-></c->
    <c- p><c- p>};</c-></c->

    <c- n><c- n>version</c-></c-> <c- nf><c- nf>version</c-></c-><c- p><c- p>()</c-></c-> <c- k><c- k>const</c-></c-><c- p><c- p>;</c-></c->
    <c- n><c- n>options</c-></c-><c- o><c- o>&amp;</c-></c-> <c- n><c- n>set_version</c-></c-><c- p><c- p>(</c-></c-><c- k><c- k>enum</c-></c-> <c- n><c- n>version</c-></c-><c- p><c- p>);</c-></c->

    <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- b><c- b>uint8_t</c-></c-> <c- n><c- n>hop_limit</c-></c-><c- p><c- p>()</c-></c-> <c- k><c- k>const</c-></c-><c- p><c- p>;</c-></c->
    <c- n><c- n>options</c-></c-><c- o><c- o>&amp;</c-></c-> <c- n><c- n>set_hop_limit</c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- b><c- b>uint8_t</c-></c-><c- p><c- p>);</c-></c->

    <c- b><c- b>bool</c-></c-> <c- nf><c- nf>use_minimum_mtu</c-></c-><c- p><c- p>()</c-></c-> <c- k><c- k>const</c-></c-><c- p><c- p>;</c-></c->
    <c- n><c- n>options</c-></c-><c- o><c- o>&amp;</c-></c-> <c- n><c- n>set_use_minimum_mtu</c-></c-><c- p><c- p>(</c-></c-><c- b><c- b>bool</c-></c-><c- p><c- p>);</c-></c->

    <c- b><c- b>bool</c-></c-> <c- nf><c- nf>disable_fragmentation</c-></c-><c- p><c- p>()</c-></c-> <c- k><c- k>const</c-></c-><c- p><c- p>;</c-></c->
    <c- n><c- n>options</c-></c-><c- o><c- o>&amp;</c-></c-> <c- n><c- n>set_disable_fragmentation</c-></c-><c- p><c- p>(</c-></c-><c- b><c- b>bool</c-></c-><c- p><c- p>);</c-></c->

    <c- b><c- b>bool</c-></c-> <c- nf><c- nf>should_calculate_receive_time</c-></c-><c- p><c- p>()</c-></c-> <c- k><c- k>const</c-></c-><c- p><c- p>;</c-></c->
    <c- n><c- n>options</c-></c-><c- o><c- o>&amp;</c-></c-> <c- n><c- n>set_should_calculate_receive_time</c-></c-><c- p><c- p>(</c-></c-><c- b><c- b>bool</c-></c-><c- p><c- p>);</c-></c->
  <c- p><c- p>};</c-></c->

  <c- k><c- k>enum</c-></c-> <c- k><c- k>class</c-></c-> <c- nc><c- nc>ecn</c-></c-> <c- p><c- p>{</c-></c->
    <c- n><c- n>non_ect</c-></c-><c- p><c- p>,</c-></c->
    <c- n><c- n>ect0</c-></c-><c- p><c- p>,</c-></c->
    <c- n><c- n>ect1</c-></c-><c- p><c- p>,</c-></c->
    <c- n><c- n>ce</c-></c->
  <c- p><c- p>};</c-></c->

  <c- k><c- k>enum</c-></c-> <c- k><c- k>class</c-></c-> <c- nc><c- nc>service_class</c-></c-> <c- p><c- p>{</c-></c->
    <c- n><c- n>best_effort</c-></c-><c- p><c- p>,</c-></c->
    <c- n><c- n>background</c-></c-><c- p><c- p>,</c-></c->
    <c- n><c- n>interactive_video</c-></c-><c- p><c- p>,</c-></c->
    <c- n><c- n>interactive_voice</c-></c-><c- p><c- p>,</c-></c->
    <c- n><c- n>responsive_data</c-></c-><c- p><c- p>,</c-></c->
    <c- n><c- n>signaling</c-></c->
  <c- p><c- p>};</c-></c->

  <c- k><c- k>class</c-></c-> <c- nc><c- nc>metadata</c-></c-> <c- o><c- o>:</c-></c-> <c- k><c- k>public</c-></c-> <c- n><c- n>protocol</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>metadata</c-></c-> <c- p><c- p>{</c-></c->
  <c- k><c- k>public</c-></c-><c- o><c- o>:</c-></c->
    <c- n><c- n>metadata</c-></c-><c- p><c- p>();</c-></c->
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    <c- n><c- n>metadata</c-></c-><c- p><c- p>(</c-></c-><c- k><c- k>const</c-></c-> <c- n><c- n>metadata</c-></c-><c- o><c- o>&amp;</c-></c-><c- p><c- p>);</c-></c->
    <c- n><c- n>metadata</c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>metadata</c-></c-><c- o><c- o>&amp;&amp;</c-></c-><c- p><c- p>);</c-></c->
    <c- n><c- n>metadata</c-></c-><c- o><c- o>&amp;</c-></c-> <c- k><c- k>operator</c-></c-><c- o><c- o>=</c-></c-><c- p><c- p>(</c-></c-><c- k><c- k>const</c-></c-> <c- n><c- n>metadata</c-></c-><c- o><c- o>&amp;</c-></c-><c- p><c- p>);</c-></c->
    <c- n><c- n>metadata</c-></c-><c- o><c- o>&amp;</c-></c-> <c- k><c- k>operator</c-></c-><c- o><c- o>=</c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>metadata</c-></c-><c- o><c- o>&amp;&amp;</c-></c-><c- p><c- p>);</c-></c->

    <c- n><c- n>ecn</c-></c-> <c- nf><c- nf>ecn</c-></c-><c- p><c- p>()</c-></c-> <c- k><c- k>const</c-></c->
    <c- n><c- n>metadata</c-></c-><c- o><c- o>&amp;</c-></c-> <c- n><c- n>set_ecn</c-></c-><c- p><c- p>(</c-></c-><c- k><c- k>enum</c-></c-> <c- n><c- n>ecn</c-></c-><c- p><c- p>);</c-></c->

    <c- n><c- n>service_class</c-></c-> <c- nf><c- nf>service_class</c-></c-><c- p><c- p>()</c-></c-> <c- k><c- k>const</c-></c-><c- p><c- p>;</c-></c->
    <c- n><c- n>metadata</c-></c-><c- o><c- o>&amp;</c-></c-> <c- n><c- n>set_service_class</c-></c-><c- p><c- p>(</c-></c-><c- k><c- k>enum</c-></c-> <c- n><c- n>service_class</c-></c-><c- p><c- p>);</c-></c->

    <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- b><c- b>uint64_t</c-></c-> <c- n><c- n>receive_time</c-></c-><c- p><c- p>()</c-></c-> <c- k><c- k>const</c-></c-><c- p><c- p>;</c-></c->
  <c- p><c- p>};</c-></c->
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  <c- k><c- k>public</c-></c-><c- o><c- o>:</c-></c->
    <c- b><c- b>bool</c-></c-> <c- n><c- n>no_delay</c-></c-><c- p><c- p>()</c-></c-> <c- k><c- k>const</c-></c-><c- p><c- p>;</c-></c->
    <c- n><c- n>options</c-></c-><c- o><c- o>&amp;</c-></c-> <c- n><c- n>set_no_delay</c-></c-><c- p><c- p>(</c-></c-><c- b><c- b>bool</c-></c-><c- p><c- p>);</c-></c->

    <c- b><c- b>bool</c-></c-> <c- nf><c- nf>no_push</c-></c-><c- p><c- p>()</c-></c-> <c- k><c- k>const</c-></c-><c- p><c- p>;</c-></c->
    <c- n><c- n>options</c-></c-><c- o><c- o>&amp;</c-></c-> <c- n><c- n>set_no_push</c-></c-><c- p><c- p>(</c-></c-><c- b><c- b>bool</c-></c-><c- p><c- p>);</c-></c->

    <c- b><c- b>bool</c-></c-> <c- nf><c- nf>no_options</c-></c-><c- p><c- p>()</c-></c-> <c- k><c- k>const</c-></c-><c- p><c- p>;</c-></c->
    <c- n><c- n>options</c-></c-><c- o><c- o>&amp;</c-></c-> <c- n><c- n>set_no_options</c-></c-><c- p><c- p>(</c-></c-><c- b><c- b>bool</c-></c-><c- p><c- p>);</c-></c->

    <c- b><c- b>bool</c-></c-> <c- nf><c- nf>keep_alive</c-></c-><c- p><c- p>()</c-></c-> <c- k><c- k>const</c-></c-><c- p><c- p>;</c-></c->
    <c- n><c- n>options</c-></c-><c- o><c- o>&amp;</c-></c-> <c- n><c- n>set_keep_alive</c-></c-><c- p><c- p>(</c-></c-><c- b><c- b>bool</c-></c-><c- p><c- p>);</c-></c->

    <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- b><c- b>size_t</c-></c-> <c- n><c- n>keep_alive_count</c-></c-><c- p><c- p>()</c-></c-> <c- k><c- k>const</c-></c-><c- p><c- p>;</c-></c->
    <c- n><c- n>options</c-></c-><c- o><c- o>&amp;</c-></c-> <c- n><c- n>set_keep_alive_count</c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- b><c- b>size_t</c-></c-><c- p><c- p>);</c-></c->

    <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>chrono</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>seconds</c-></c-> <c- n><c- n>keep_alive_idle</c-></c-><c- p><c- p>()</c-></c-> <c- k><c- k>const</c-></c-><c- p><c- p>;</c-></c->
    <c- n><c- n>options</c-></c-><c- o><c- o>&amp;</c-></c-> <c- n><c- n>set_keep_alive_idle</c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- b><c- b>uint32_t</c-></c-><c- p><c- p>);</c-></c->

    <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>chrono</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>seconds</c-></c-> <c- n><c- n>keep_alive_interval</c-></c-><c- p><c- p>()</c-></c-> <c- k><c- k>const</c-></c-><c- p><c- p>;</c-></c->
    <c- n><c- n>options</c-></c-><c- o><c- o>&amp;</c-></c-> <c- n><c- n>set_keep_alive_interval</c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>chrono</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>seconds</c-></c-><c- p><c- p>);</c-></c->

    <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- b><c- b>size_t</c-></c-> <c- n><c- n>maximum_segment_size</c-></c-><c- p><c- p>()</c-></c-> <c- k><c- k>const</c-></c-><c- p><c- p>;</c-></c->
    <c- n><c- n>options</c-></c-><c- o><c- o>&amp;</c-></c-> <c- n><c- n>set_maximum_segment_size</c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- b><c- b>size_t</c-></c-><c- p><c- p>);</c-></c->

    <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>chrono</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>seconds</c-></c-> <c- n><c- n>connection_timeout</c-></c-><c- p><c- p>()</c-></c-> <c- k><c- k>const</c-></c-><c- p><c- p>;</c-></c->
    <c- n><c- n>options</c-></c-><c- o><c- o>&amp;</c-></c-> <c- n><c- n>set_connection_timeout</c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>chrono</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>seconds</c-></c-><c- p><c- p>);</c-></c->

    <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>chrono</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>seconds</c-></c-> <c- n><c- n>persist_timeout</c-></c-><c- p><c- p>()</c-></c-> <c- k><c- k>const</c-></c-><c- p><c- p>;</c-></c->
    <c- n><c- n>options</c-></c-><c- o><c- o>&amp;</c-></c-> <c- n><c- n>set_persist_timeout</c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>chrono</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>seconds</c-></c-><c- p><c- p>);</c-></c->

    <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>chrono</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>seconds</c-></c-> <c- n><c- n>connection_drop_time</c-></c-><c- p><c- p>()</c-></c-> <c- k><c- k>const</c-></c-><c- p><c- p>;</c-></c->
    <c- n><c- n>options</c-></c-><c- o><c- o>&amp;</c-></c-> <c- n><c- n>set_connection_drop_time</c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>chrono</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>seconds</c-></c-><c- p><c- p>);</c-></c->

    <c- b><c- b>bool</c-></c-> <c- nf><c- nf>retransmit_fin_drop</c-></c-><c- p><c- p>()</c-></c-> <c- k><c- k>const</c-></c-><c- p><c- p>;</c-></c->
    <c- n><c- n>options</c-></c-><c- o><c- o>&amp;</c-></c-> <c- n><c- n>set_retransmit_fin_drop</c-></c-><c- p><c- p>(</c-></c-><c- b><c- b>bool</c-></c-><c- p><c- p>);</c-></c->

    <c- b><c- b>bool</c-></c-> <c- nf><c- nf>disable_ack_stretching</c-></c-><c- p><c- p>()</c-></c-> <c- k><c- k>const</c-></c-><c- p><c- p>;</c-></c->
    <c- n><c- n>options</c-></c-><c- o><c- o>&amp;</c-></c-> <c- n><c- n>set_disable_ack_stretching</c-></c-><c- p><c- p>(</c-></c-><c- b><c- b>bool</c-></c-><c- p><c- p>);</c-></c->

    <c- b><c- b>bool</c-></c-> <c- nf><c- nf>enable_fast_open</c-></c-><c- p><c- p>()</c-></c-> <c- k><c- k>const</c-></c-><c- p><c- p>;</c-></c->
    <c- n><c- n>options</c-></c-><c- o><c- o>&amp;</c-></c-> <c- n><c- n>set_enable_fast_open</c-></c-><c- p><c- p>(</c-></c-><c- b><c- b>bool</c-></c-><c- p><c- p>);</c-></c->

    <c- b><c- b>bool</c-></c-> <c- nf><c- nf>disable_ecn</c-></c-><c- p><c- p>()</c-></c-> <c- k><c- k>const</c-></c-><c- p><c- p>;</c-></c->
    <c- n><c- n>options</c-></c-><c- o><c- o>&amp;</c-></c-> <c- n><c- n>set_disable_ecn</c-></c-><c- p><c- p>(</c-></c-><c- b><c- b>bool</c-></c-><c- p><c- p>);</c-></c->
  <c- p><c- p>};</c-></c->

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    <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- b><c- b>uint32_t</c-></c-> <c- n><c- n>available_send_buffer</c-></c-><c- p><c- p>()</c-></c-> <c- k><c- k>const</c-></c-><c- p><c- p>;</c-></c->
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  <c- p><c- p>};</c-></c->

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    <c- n><c- n>certificate</c-></c-><c- p><c- p>(</c-></c-><c- k><c- k>const</c-></c-> <c- n><c- n>certificate</c-></c-><c- o><c- o>&amp;</c-></c-><c- p><c- p>);</c-></c->
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    <c- n><c- n>certificate</c-></c-><c- o><c- o>&amp;</c-></c-> <c- k><c- k>operator</c-></c-><c- o><c- o>=</c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>certificate</c-></c-><c- o><c- o>&amp;&amp;</c-></c-><c- p><c- p>);</c-></c->

    <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>string</c-></c-> <c- n><c- n>common_name</c-></c-><c- p><c- p>()</c-></c-> <c- k><c- k>const</c-></c-><c- p><c- p>;</c-></c->
    <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>vector</c-></c-><c- o><c- o>&lt;</c-></c-><c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- b><c- b>uint8_t</c-></c-><c- o><c- o>></c-></c-> <c- n><c- n>der_bytes</c-></c-><c- p><c- p>()</c-></c-> <c- k><c- k>const</c-></c-><c- p><c- p>;</c-></c->
    <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>vector</c-></c-><c- o><c- o>&lt;</c-></c-><c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- b><c- b>uint8_t</c-></c-><c- o><c- o>></c-></c-> <c- n><c- n>public_key</c-></c-><c- p><c- p>()</c-></c-> <c- k><c- k>const</c-></c-><c- p><c- p>;</c-></c->
  <c- p><c- p>};</c-></c->

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    <c- n><c- n>identity</c-></c-><c- p><c- p>();</c-></c->
    <c- n><c- n>identity</c-></c-><c- p><c- p>(</c-></c-><c- k><c- k>const</c-></c-> <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>vector</c-></c-><c- o><c- o>&lt;</c-></c-><c- n><c- n>certificate</c-></c-><c- o><c- o>>&amp;</c-></c-><c- p><c- p>,</c-></c-> <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>string_view</c-></c-><c- p><c- p>);</c-></c->
  <c- p><c- p>};</c-></c->

  <c- k><c- k>class</c-></c-> <c- nc><c- nc>options</c-></c-> <c- o><c- o>:</c-></c-> <c- k><c- k>public</c-></c-> <c- n><c- n>protocol</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>options</c-></c-> <c- p><c- p>{</c-></c->
  <c- k><c- k>public</c-></c-><c- o><c- o>:</c-></c->
    <c- n><c- n>identity</c-></c-> <c- n><c- n>get_local_identity</c-></c-><c- p><c- p>()</c-></c-> <c- k><c- k>const</c-></c-><c- p><c- p>;</c-></c->
    <c- n><c- n>options</c-></c-><c- o><c- o>&amp;</c-></c-> <c- n><c- n>set_local_identity</c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>identity</c-></c-><c- p><c- p>);</c-></c->

    <c- k><c- k>template</c-></c-><c- o><c- o>&lt;</c-></c-><c- k><c- k>typename</c-></c-> <c- n><c- n>Handler</c-></c-><c- p><c- p>,</c-></c-> <c- k><c- k>typename</c-></c-> <c- o><c- o>=</c-></c->
      <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>enable_if_t</c-></c-><c- o><c- o>&lt;</c-></c-><c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>is_invocable_r_v</c-></c-><c- o><c- o>&lt;</c-></c-><c- b><c- b>void</c-></c-><c- p><c- p>,</c-></c-> <c- n><c- n>Handler</c-></c-><c- p><c- p>,</c-></c->
        <c- n><c- n>metadata</c-></c-><c- p><c- p>,</c-></c-> <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>function</c-></c-><c- o><c- o>&lt;</c-></c-><c- b><c- b>void</c-></c-><c- p><c- p>(</c-></c-><c- b><c- b>bool</c-></c-><c- p><c- p>)</c-></c-><c- o><c- o>>>>></c-></c->
    <c- n><c- n>options</c-></c-><c- o><c- o>&amp;</c-></c-> <c- n><c- n>on_verify</c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>Handler</c-></c-><c- p><c- p>,</c-></c-> <c- n><c- n>workqueue</c-></c-><c- p><c- p>);</c-></c->
  <c- p><c- p>};</c-></c->

  <c- k><c- k>class</c-></c-> <c- nc><c- nc>metadata</c-></c-> <c- o><c- o>:</c-></c-> <c- k><c- k>public</c-></c-> <c- n><c- n>protocol</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>metadata</c-></c-> <c- p><c- p>{</c-></c->
  <c- k><c- k>public</c-></c-><c- o><c- o>:</c-></c->
    <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>string_view</c-></c-> <c- n><c- n>negotiated_protocol</c-></c-><c- p><c- p>()</c-></c-> <c- k><c- k>const</c-></c-><c- p><c- p>;</c-></c->
    <c- b><c- b>bool</c-></c-> <c- nf><c- nf>early_data_accepted</c-></c-><c- p><c- p>()</c-></c-> <c- k><c- k>const</c-></c-><c- p><c- p>;</c-></c->
    <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>vector</c-></c-><c- o><c- o>&lt;</c-></c-><c- n><c- n>certificate</c-></c-><c- o><c- o>></c-></c-> <c- n><c- n>certificate_chain</c-></c-><c- p><c- p>()</c-></c-> <c- k><c- k>const</c-></c-><c- p><c- p>;</c-></c->
    <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>string_view</c-></c-> <c- n><c- n>server_name</c-></c-><c- p><c- p>()</c-></c-> <c- k><c- k>const</c-></c-><c- p><c- p>;</c-></c->

    <c- k><c- k>template</c-></c-><c- o><c- o>&lt;</c-></c-><c- k><c- k>typename</c-></c-> <c- n><c- n>Handler</c-></c-><c- p><c- p>,</c-></c-> <c- k><c- k>typename</c-></c-> <c- o><c- o>=</c-></c->
      <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>enable_if_t</c-></c-><c- o><c- o>&lt;</c-></c-><c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>is_invocable_r_v</c-></c-><c- o><c- o>&lt;</c-></c-><c- b><c- b>void</c-></c-><c- p><c- p>,</c-></c-> <c- n><c- n>Handler</c-></c-><c- p><c- p>,</c-></c-> <c- n><c- n>buffer</c-></c-><c- o><c- o>>>></c-></c->
    <c- b><c- b>bool</c-></c-> <c- n><c- n>oscp_response</c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>Handler</c-></c-><c- p><c- p>)</c-></c-> <c- k><c- k>const</c-></c-><c- p><c- p>;</c-></c->
  <c- p><c- p>};</c-></c->
<c- p><c- p>};</c-></c->

<c- p><c- p>}</c-></c->

<c- cp><c- cp>#endif</c-></c->
</code></pre>
   <h3 class="heading settled" data-level="5.14" id="protocolframer"><span class="secno">5.14. </span><span class="content"><code class="highlight"><c- n>net</c-><c- o>::</c-><c- n>protocol</c-><c- o>::</c-><c- n>framer</c-></code></span><a class="self-link" href="#protocolframer"></a></h3>
   <p>A framer defines a protocol in a connection’s protocol stack
that parses and writes messages on top of a transport protocol, such
as a TCP stream. A framer can add and parse headers or delimiters around
application data to provide a message-oriented abstraction.</p>
   <p>The framer is templated with an implementation class that must have the
following traits:</p>
   <ul>
    <li>
     <p><code class="highlight"><c- k>class</c-> <c- nc>T</c-><c- o>::</c-><c- n>options</c-></code></p>
      An options class derived from <code class="highlight"><c- n>protocol</c-><c- o>::</c-><c- n>framer</c-><c- o>&amp;</c-><c- n>lt</c-><c- p>;</c-><c- n>T</c-><c- o>&amp;</c-><c- n>gt</c-><c- p>;</c-></code> that defines protocol
specific options 
    <li>
     <p><code class="highlight"><c- k>class</c-> <c- nc>T</c-><c- o>::</c-><c- n>metadata</c-></code></p>
      A metadata class derived from <code class="highlight"><c- n>protocol</c-><c- o>::</c-><c- n>framer</c-><c- o>&amp;</c-><c- n>lt</c-><c- p>;</c-><c- n>T</c-><c- o>&amp;</c-><c- n>gt</c-><c- p>;</c-></code> that defines protocol
specific metadata 
    <li>
     <p><code class="highlight"><c- n>start_result</c-> <c- n>T</c-><c- o>::</c-><c- n>start</c-><c- p>()</c-></code></p>
      This will be called during connection establishment. Return <code class="highlight"><c- n>start_result</c-><c- o>::</c-><c- n>ready</c-></code> to indicate that the framer instance is ready to begin sending/receiving data.
Return <code class="highlight"><c- n>start_result</c-><c- o>::</c-><c- n>will_mark_ready</c-></code> to indicate that the framer instance needs
to complete handshaking before it is able to send/receive data. If there is no <code class="highlight"><c- n>T</c-><c- o>::</c-><c- n>start</c-></code> it is assumed no handshake is necessary, which will behave the same as if <code class="highlight"><c- n>T</c-><c- o>::</c-><c- n>start</c-></code> always returned <code class="highlight"><c- n>start_result</c-><c- o>::</c-><c- n>ready</c-></code>. 
    <li>
     <p><code class="highlight"><c- b>size_t</c-> <c- n>T</c-><c- o>::</c-><c- n>handle_input</c-><c- p>()</c-></code></p>
      This function will be invoked whenever new input
data is available to be parsed. When this block is
run, the implementation should call functions like <code class="highlight"><c- n>parse_input</c-><c- p>()</c-></code> and <code class="highlight"><c- n>deliver_input</c-><c- p>()</c-></code>. 
     <p>Each invocation represents new data being available
to read from the network. This data may be insufficient
to complete a message, or may contain multiple messages.
Implementations are expected to try to parse messages
in a loop until parsing fails to read enough to continue.</p>
     <p>Return a hint of the number of bytes that should be present
before invoking this handler again. Returning 0 indicates
that the handler should be invoked once any data is available.</p>
    <li>
     <p><code class="highlight"><c- b>void</c-> <c- n>T</c-><c- o>::</c-><c- n>handle_output</c-><c- p>(</c-><c- n>net</c-><c- o>::</c-><c- n>protocol</c-><c- o>::</c-><c- n>metadata</c-><c- p>,</c-> <c- b>size_t</c-> <c- n>message_length</c-><c- p>,</c-> <c- b>bool</c-> <c- n>is_complete</c-><c- p>)</c-></code></p>
      This function will be invoked whenever an output
message is ready to be sent. When this block is
run, the implementation should call functions like <code class="highlight"><c- n>parse_output</c-><c- p>()</c-></code> and <code class="highlight"><c- n>write_output</c-><c- p>()</c-></code>. 
     <p>Each invocation represents a single complete or partial
message that is being sent. The implementation is
expected to write this message or let it be dropped
in this handler.</p>
    <li>
     <p><code class="highlight"><c- b>bool</c-> <c- n>T</c-><c- o>::</c-><c- n>stop</c-><c- p>()</c-></code></p>
      This function will be invoked when the connection
is being disconnected, to allow the framer implementation
a chance to send any final data. 
     <p>Return true if the framer is done and the connection
can be fully disconnected, or false the stop should
be delayed. If false, the implementation must later
call <code class="highlight"><c- n>mark_failed</c-><c- p>(</c-><c- n>std</c-><c- o>::</c-><c- n>error_code</c-><c- p>)</c-></code> on the instance.</p>
    <li>
     <p><code class="highlight"><c- b>void</c-> <c- n>T</c-><c- o>::</c-><c- n>wakeup</c-><c- p>()</c-></code></p>
      This optional function will be invoked whenever the wakeup timer
set via <code class="highlight"><c- n>schedule_wakeup</c-><c- p>()</c-></code> fires. This is intended to
be used for sending keepalives or other control traffic. 
   </ul>
<pre class="highlight"><code class="highlight"><c- k><c- k>namespace</c-></c-> <c- n><c- n>net</c-></c-> <c- p><c- p>{</c-></c->

<c- k><c- k>template</c-></c-><c- o><c- o>&lt;</c-></c-><c- k><c- k>typename</c-></c-> <c- n><c- n>T</c-></c-><c- o><c- o>></c-></c-> <c- k><c- k>class</c-></c-> <c- nc><c- nc>protocol</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>framer</c-></c->
<c- k><c- k>public</c-></c-><c- o><c- o>:</c-></c->
  <c- k><c- k>enum</c-></c-> <c- k><c- k>class</c-></c-> <c- nc><c- nc>start_result</c-></c-> <c- p><c- p>{</c-></c->
    <c- n><c- n>ready</c-></c-><c- p><c- p>,</c-></c->
    <c- n><c- n>will_mark_ready</c-></c->
  <c- p><c- p>};</c-></c->

  <c- k><c- k>static</c-></c-> <c- n><c- n>protocol</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>definition</c-></c-> <c- n><c- n>definition</c-></c-><c- p><c- p>();</c-></c->
  <c- k><c- k>class</c-></c-> <c- nc><c- nc>options</c-></c-> <c- o><c- o>:</c-></c-> <c- k><c- k>public</c-></c-> <c- n><c- n>protocol</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>options</c-></c-> <c- p><c- p>{</c-></c->
  <c- k><c- k>public</c-></c-><c- o><c- o>:</c-></c->
    <c- n><c- n>options</c-></c-><c- p><c- p>();</c-></c->
  <c- p><c- p>};</c-></c->

  <c- k><c- k>class</c-></c-> <c- nc><c- nc>metadata</c-></c-> <c- o><c- o>:</c-></c-> <c- k><c- k>public</c-></c-> <c- n><c- n>protocol</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>metadata</c-></c-> <c- p><c- p>{</c-></c->
  <c- k><c- k>public</c-></c-><c- o><c- o>:</c-></c->
    <c- n><c- n>metadata</c-></c-><c- p><c- p>();</c-></c->
    <c- n><c- n>metadata</c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>framer</c-></c-><c- p><c- p>);</c-></c->

    <c- k><c- k>template</c-></c-><c- o><c- o>&lt;</c-></c-><c- k><c- k>typename</c-></c-> <c- n><c- n>Value</c-></c-><c- o><c- o>></c-></c->
    <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>optional</c-></c-><c- o><c- o>&lt;</c-></c-><c- n><c- n>Value</c-></c-><c- o><c- o>></c-></c-> <c- n><c- n>get_value</c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>string_view</c-></c-> <c- n><c- n>key</c-></c-><c- p><c- p>)</c-></c-> <c- k><c- k>const</c-></c-><c- p><c- p>;</c-></c->

    <c- k><c- k>template</c-></c-><c- o><c- o>&lt;</c-></c-><c- k><c- k>typename</c-></c-> <c- n><c- n>Value</c-></c-><c- o><c- o>></c-></c->
    <c- b><c- b>void</c-></c-> <c- n><c- n>set_value</c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>string_view</c-></c-> <c- n><c- n>key</c-></c-><c- p><c- p>,</c-></c-> <c- n><c- n>Value</c-></c-><c- p><c- p>);</c-></c->
  <c- p><c- p>};</c-></c->

  <c- n><c- n>framer</c-></c-><c- p><c- p>();</c-></c->

  <c- b><c- b>void</c-></c-> <c- nf><c- nf>mark_ready</c-></c-><c- p><c- p>();</c-></c->
  <c- b><c- b>void</c-></c-> <c- nf><c- nf>mark_failed</c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>error_code</c-></c-><c- p><c- p>);</c-></c->

  <c- k><c- k>template</c-></c-><c- o><c- o>&lt;</c-></c-><c- k><c- k>typename</c-></c-> <c- n><c- n>Parser</c-></c-><c- p><c- p>,</c-></c-> <c- k><c- k>typename</c-></c-> <c- o><c- o>=</c-></c->
    <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>enable_if_t</c-></c-><c- o><c- o>&lt;</c-></c-><c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>is_invocable_r_v</c-></c-><c- o><c- o>&lt;</c-></c-><c- b><c- b>void</c-></c-><c- p><c- p>,</c-></c-> <c- n><c- n>Parser</c-></c-><c- p><c- p>,</c-></c->
      <c- k><c- k>const</c-></c-> <c- b><c- b>void</c-></c-><c- o><c- o>*</c-></c-><c- p><c- p>,</c-></c-> <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- b><c- b>size_t</c-></c-><c- p><c- p>,</c-></c-> <c- b><c- b>bool</c-></c-><c- o><c- o>>>></c-></c->
  <c- b><c- b>bool</c-></c-> <c- n><c- n>parse_input</c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- b><c- b>size_t</c-></c-> <c- n><c- n>min_length</c-></c-><c- p><c- p>,</c-></c-> <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- b><c- b>size_t</c-></c-> <c- n><c- n>max_length</c-></c-><c- p><c- p>,</c-></c-> <c- n><c- n>Parser</c-></c-><c- o><c- o>&amp;&amp;</c-></c-><c- p><c- p>);</c-></c->

  <c- b><c- b>void</c-></c-> <c- nf><c- nf>deliver_input</c-></c-><c- p><c- p>(</c-></c-><c- k><c- k>const</c-></c-> <c- b><c- b>void</c-></c-><c- o><c- o>*</c-></c-><c- p><c- p>,</c-></c-> <c- b><c- b>size_t</c-></c-><c- p><c- p>,</c-></c-> <c- n><c- n>metadata</c-></c-><c- p><c- p>,</c-></c-> <c- b><c- b>bool</c-></c-> <c- n><c- n>is_complete</c-></c-><c- p><c- p>);</c-></c->
  <c- b><c- b>bool</c-></c-> <c- nf><c- nf>deliver_input_no_copy</c-></c-><c- p><c- p>(</c-></c-><c- b><c- b>size_t</c-></c-><c- p><c- p>,</c-></c-> <c- n><c- n>metadata</c-></c-><c- p><c- p>,</c-></c-> <c- b><c- b>bool</c-></c-> <c- n><c- n>is_complete</c-></c-><c- p><c- p>);</c-></c->
  <c- b><c- b>void</c-></c-> <c- nf><c- nf>pass_through_input</c-></c-><c- p><c- p>();</c-></c->

  <c- k><c- k>template</c-></c-><c- o><c- o>&lt;</c-></c-><c- k><c- k>typename</c-></c-> <c- n><c- n>Parser</c-></c-><c- p><c- p>,</c-></c-> <c- k><c- k>typename</c-></c-> <c- o><c- o>=</c-></c->
    <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>enable_if_t</c-></c-><c- o><c- o>&lt;</c-></c-><c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>is_invocable_r_v</c-></c-><c- o><c- o>&lt;</c-></c-><c- b><c- b>void</c-></c-><c- p><c- p>,</c-></c-> <c- n><c- n>Parser</c-></c-><c- p><c- p>,</c-></c->
      <c- k><c- k>const</c-></c-> <c- b><c- b>void</c-></c-><c- o><c- o>*</c-></c-><c- p><c- p>,</c-></c-> <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- b><c- b>size_t</c-></c-><c- p><c- p>,</c-></c-> <c- b><c- b>bool</c-></c-><c- o><c- o>>>></c-></c->
  <c- b><c- b>bool</c-></c-> <c- n><c- n>parse_output</c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- b><c- b>size_t</c-></c-> <c- n><c- n>min_length</c-></c-><c- p><c- p>,</c-></c-> <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- b><c- b>size_t</c-></c-> <c- n><c- n>max_length</c-></c-><c- p><c- p>,</c-></c-> <c- n><c- n>Parser</c-></c-><c- o><c- o>&amp;&amp;</c-></c-><c- p><c- p>);</c-></c->

  <c- b><c- b>void</c-></c-> <c- nf><c- nf>write_output</c-></c-><c- p><c- p>(</c-></c-><c- k><c- k>const</c-></c-> <c- b><c- b>void</c-></c-><c- o><c- o>*</c-></c-><c- p><c- p>,</c-></c-> <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- b><c- b>size_t</c-></c-><c- p><c- p>);</c-></c->
  <c- b><c- b>void</c-></c-> <c- nf><c- nf>write_output_no_copy</c-></c-><c- p><c- p>(</c-></c-><c- b><c- b>size_t</c-></c-><c- p><c- p>);</c-></c->
  <c- b><c- b>void</c-></c-> <c- nf><c- nf>pass_through_output</c-></c-><c- p><c- p>();</c-></c->
  <c- b><c- b>void</c-></c-> <c- nf><c- nf>schedule_wakeup</c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>chrono</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>milliseconds</c-></c-><c- p><c- p>);</c-></c->

  <c- k><c- k>template</c-></c-><c- o><c- o>&lt;</c-></c-><c- k><c- k>typename</c-></c-> <c- n><c- n>Handler</c-></c-><c- p><c- p>,</c-></c-> <c- k><c- k>typename</c-></c-> <c- o><c- o>=</c-></c->
    <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>enable_if_t</c-></c-><c- o><c- o>&lt;</c-></c-><c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>is_invocable_r_v</c-></c-><c- o><c- o>&lt;</c-></c-><c- b><c- b>void</c-></c-><c- p><c- p>,</c-></c-> <c- n><c- n>Handler</c-></c-><c- o><c- o>>>></c-></c->
  <c- b><c- b>void</c-></c-> <c- n><c- n>async</c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>Handler</c-></c-><c- o><c- o>&amp;&amp;</c-></c-><c- p><c- p>);</c-></c->

  <c- n><c- n>endpoint</c-></c-> <c- nf><c- nf>remote_endpoint</c-></c-><c- p><c- p>()</c-></c-> <c- k><c- k>const</c-></c-><c- p><c- p>;</c-></c->
  <c- n><c- n>endpoint</c-></c-> <c- nf><c- nf>local_endpoint</c-></c-><c- p><c- p>()</c-></c-> <c- k><c- k>const</c-></c-><c- p><c- p>;</c-></c->
  <c- n><c- n>parameters</c-></c-> <c- nf><c- nf>parameters</c-></c-><c- p><c- p>();</c-></c->
  <c- b><c- b>void</c-></c-> <c- nf><c- nf>prepend_appplication_protocol</c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>protocol</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>options</c-></c-><c- p><c- p>);</c-></c->
<c- p><c- p>};</c-></c->

<c- p><c- p>}</c-></c->
</code></pre>
   <h3 class="heading settled" data-level="5.15" id="workqueue"><span class="secno">5.15. </span><span class="content"><code class="highlight"><c- n>net</c-><c- o>::</c-><c- n>workqueue</c-></code></span><a class="self-link" href="#workqueue"></a></h3>
    This object is basically an executor that works well on Apple platforms.  We should just use executor instead, but here’s what this suggested API was developed with.  This is not the important part of this suggested API. 
<pre class="highlight"><code class="highlight"><c- k><c- k>namespace</c-></c-> <c- n><c- n>net</c-></c-> <c- p><c- p>{</c-></c->

<c- k><c- k>class</c-></c-> <c- nc><c- nc>workqueue</c-></c-> <c- p><c- p>{</c-></c->
<c- k><c- k>public</c-></c-><c- o><c- o>:</c-></c->
  <c- k><c- k>static</c-></c-> <c- b><c- b>void</c-></c-> <c- n><c- n>main</c-></c-><c- p><c- p>();</c-></c->
  <c- k><c- k>static</c-></c-> <c- n><c- n>workqueue</c-></c-> <c- nf><c- nf>main_queue</c-></c-><c- p><c- p>();</c-></c->

  <c- n><c- n>workqueue</c-></c-><c- p><c- p>(</c-></c-><c- k><c- k>const</c-></c-> <c- n><c- n>workqueue</c-></c-><c- o><c- o>&amp;</c-></c-><c- p><c- p>);</c-></c->
  <c- n><c- n>workqueue</c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>workqueue</c-></c-><c- o><c- o>&amp;&amp;</c-></c-><c- p><c- p>);</c-></c->
  <c- n><c- n>workqueue</c-></c-><c- o><c- o>&amp;</c-></c-> <c- k><c- k>operator</c-></c-><c- o><c- o>=</c-></c-><c- p><c- p>(</c-></c-><c- k><c- k>const</c-></c-> <c- n><c- n>workqueue</c-></c-><c- o><c- o>&amp;</c-></c-><c- p><c- p>);</c-></c->
  <c- n><c- n>workqueue</c-></c-><c- o><c- o>&amp;</c-></c-> <c- k><c- k>operator</c-></c-><c- o><c- o>=</c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>workqueue</c-></c-><c- o><c- o>&amp;&amp;</c-></c-><c- p><c- p>);</c-></c->

  <c- k><c- k>template</c-></c-><c- o><c- o>&lt;</c-></c-><c- k><c- k>typename</c-></c-> <c- n><c- n>Work</c-></c-><c- p><c- p>,</c-></c-> <c- k><c- k>typename</c-></c-> <c- o><c- o>=</c-></c->
    <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>enable_if_t</c-></c-><c- o><c- o>&lt;</c-></c-><c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>is_invocable_r_v</c-></c-><c- o><c- o>&lt;</c-></c-><c- b><c- b>void</c-></c-><c- p><c- p>,</c-></c-> <c- n><c- n>Work</c-></c-><c- o><c- o>>>></c-></c->
  <c- b><c- b>void</c-></c-> <c- n><c- n>dispatch</c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>Work</c-></c-><c- p><c- p>)</c-></c->
<c- p><c- p>};</c-></c->

<c- p><c- p>}</c-></c->
</code></pre>
   <h2 class="heading settled" data-level="6" id="examples"><span class="secno">6. </span><span class="content">Examples</span><a class="self-link" href="#examples"></a></h2>
   <h3 class="heading settled" data-level="6.1" id="client"><span class="secno">6.1. </span><span class="content">Client</span><a class="self-link" href="#client"></a></h3>
   <p>A simple TCP/HTTP client can be written using coroutines.  This example uses <code class="highlight"><c- n>std</c-><c- o>::</c-><c- n>lazy</c-></code> from <a data-link-type="biblio" href="#biblio-p1056r1">[p1056r1]</a>.</p>
<pre class="highlight"><code class="highlight"><c- cp><c- cp>#include</c-></c-> &lt;iostream>
<c- cp><c- cp>#include</c-></c-> &lt;net>

<c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>lazy</c-></c-><c- o><c- o>&lt;</c-></c-><c- b><c- b>void</c-></c-><c- o><c- o>></c-></c-> <c- n><c- n>run</c-></c-><c- p><c- p>()</c-></c->
<c- p><c- p>{</c-></c->
  <c- n><c- n>net</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>workqueue</c-></c-> <c- n><c- n>queue</c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>net</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>workqueue</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>main_queue</c-></c-><c- p><c- p>());</c-></c->
  <c- n><c- n>net</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>endpoint</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>host</c-></c-> <c- n><c- n>host</c-></c-><c- p><c- p>(</c-></c-><c- s><c- s>"www.apple.com"</c-></c-><c- p><c- p>,</c-></c-> <c- mi><c- mi>80</c-></c-><c- p><c- p>);</c-></c->
  <c- n><c- n>net</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>connection</c-></c-> <c- n><c- n>connection</c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>host</c-></c-><c- p><c- p>,</c-></c-> <c- n><c- n>net</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>parameters</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>tcp</c-></c-><c- p><c- p>(),</c-></c-> <c- n><c- n>queue</c-></c-><c- p><c- p>);</c-></c->
  <c- n><c- n>connection</c-></c-><c- p><c- p>.</c-></c-><c- n><c- n>start</c-></c-><c- p><c- p>();</c-></c->

  <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>cout</c-></c-> <c- o><c- o>&lt;&lt;</c-></c-> <c- s><c- s>"Sending request"</c-></c-> <c- o><c- o>&lt;&lt;</c-></c-> <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>endl</c-></c-><c- p><c- p>;</c-></c->
  <c- n><c- n>net</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>message</c-></c-> <c- n><c- n>message</c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>net</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>buffer</c-></c-><c- p><c- p>(</c-></c-><c- s><c- s>"GET / HTTP/1.1</c-></c-><c- se><c- se>\r\n</c-></c-><c- s><c- s>Host: www.apple.com</c-></c-><c- se><c- se>\r\n\r\n</c-></c-><c- s><c- s>"</c-></c-><c- p><c- p>));</c-></c->
  <c- k><c- k>auto</c-></c-> <c- n><c- n>sendResult</c-></c-> <c- o><c- o>=</c-></c-> <c- n><c- n>co_await</c-></c-> <c- n><c- n>connection</c-></c-><c- p><c- p>.</c-></c-><c- n><c- n>send</c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>message</c-></c-><c- p><c- p>);</c-></c->
  <c- k><c- k>if</c-></c-> <c- p><c- p>(</c-></c-><c- o><c- o>!</c-></c-><c- n><c- n>sendResult</c-></c-><c- p><c- p>)</c-></c-> <c- p><c- p>{</c-></c->
    <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>cerr</c-></c-> <c- o><c- o>&lt;&lt;</c-></c-> <c- s><c- s>"failed to send request"</c-></c-> <c- o><c- o>&lt;&lt;</c-></c-> <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>endl</c-></c-><c- p><c- p>;</c-></c->
    <c- n><c- n>co_return</c-></c-><c- p><c- p>;</c-></c->
  <c- p><c- p>}</c-></c->

  <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>cout</c-></c-> <c- o><c- o>&lt;&lt;</c-></c-> <c- s><c- s>"Sent request, waiting for response"</c-></c-> <c- o><c- o>&lt;&lt;</c-></c-> <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>endl</c-></c-><c- p><c- p>;</c-></c->
  <c- k><c- k>auto</c-></c-> <c- n><c- n>message</c-></c-> <c- o><c- o>=</c-></c-> <c- n><c- n>co_await</c-></c-> <c- n><c- n>connection</c-></c-><c- p><c- p>.</c-></c-><c- n><c- n>receive</c-></c-><c- p><c- p>();</c-></c->
  <c- k><c- k>if</c-></c-> <c- p><c- p>(</c-></c-><c- o><c- o>!</c-></c-><c- n><c- n>message</c-></c-><c- p><c- p>)</c-></c-> <c- p><c- p>{</c-></c->
    <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>cerr</c-></c-> <c- o><c- o>&lt;&lt;</c-></c-> <c- s><c- s>"failed to receive response"</c-></c-> <c- o><c- o>&lt;&lt;</c-></c-> <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>endl</c-></c-><c- p><c- p>;</c-></c->
    <c- n><c- n>co_return</c-></c-><c- p><c- p>;</c-></c->
  <c- p><c- p>}</c-></c->

  <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>cout</c-></c-> <c- o><c- o>&lt;&lt;</c-></c-> <c- s><c- s>"Received response"</c-></c-> <c- o><c- o>&lt;&lt;</c-></c-> <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>endl</c-></c-><c- p><c- p>;</c-></c->
  <c- n><c- n>message</c-></c-><c- o><c- o>-></c-></c-><c- n><c- n>data</c-></c-><c- p><c- p>().</c-></c-><c- n><c- n>get</c-></c-><c- p><c- p>([](</c-></c-><c- k><c- k>const</c-></c-> <c- b><c- b>uint8_t</c-></c-> <c- o><c- o>*</c-></c-><c- n><c- n>bytes</c-></c-><c- p><c- p>,</c-></c-> <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- b><c- b>size_t</c-></c-> <c- n><c- n>size</c-></c-><c- p><c- p>)</c-></c-> <c- p><c- p>{</c-></c->
    <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>cout</c-></c-> <c- o><c- o>&lt;&lt;</c-></c-> <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>string</c-></c-><c- p><c- p>(</c-></c-><c- k><c- k>reinterpret_cast</c-></c-><c- o><c- o>&lt;</c-></c-><c- k><c- k>const</c-></c-> <c- b><c- b>char</c-></c-> <c- o><c- o>*></c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>bytes</c-></c-><c- p><c- p>),</c-></c-> <c- n><c- n>size</c-></c-><c- p><c- p>);</c-></c->
  <c- p><c- p>});</c-></c->
  <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>cout</c-></c-> <c- o><c- o>&lt;&lt;</c-></c-> <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>endl</c-></c-><c- p><c- p>;</c-></c->
  <c- n><c- n>co_return</c-></c-><c- p><c- p>;</c-></c->
<c- p><c- p>}</c-></c->

<c- b><c- b>int</c-></c-> <c- n><c- n>main</c-></c-><c- p><c- p>(</c-></c-><c- b><c- b>int</c-></c-><c- p><c- p>,</c-></c-> <c- b><c- b>char</c-></c-><c- o><c- o>**</c-></c-><c- p><c- p>)</c-></c->
<c- p><c- p>{</c-></c->
  <c- k><c- k>auto</c-></c-> <c- n><c- n>lazy</c-></c-> <c- o><c- o>=</c-></c-> <c- n><c- n>run</c-></c-><c- p><c- p>();</c-></c->
  <c- n><c- n>net</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>workqueue</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>main</c-></c-><c- p><c- p>();</c-></c->
<c- p><c- p>}</c-></c->
</code></pre>
   <p>All that is needed to make the request use TLS is to change <code class="highlight"><c- n>net</c-><c- o>::</c-><c- n>parameters</c-><c- o>::</c-><c- n>tcp</c-><c- p>()</c-></code> to <code class="highlight"><c- n>net</c-><c- o>::</c-><c- n>parameters</c-><c- o>::</c-><c- n>tls</c-><c- p>()</c-></code>.  Port 80 should also be changed to port 443 for this particular server.</p>
   <h3 class="heading settled" data-level="6.2" id="server"><span class="secno">6.2. </span><span class="content">Server</span><a class="self-link" href="#server"></a></h3>
   <p>Using this suggested API, one can make a simple TCP/HTTP server as follows:</p>
<pre class="highlight"><code class="highlight"><c- cp><c- cp>#include</c-></c-> &lt;iostream>
<c- cp><c- cp>#include</c-></c-> &lt;net>

<c- b><c- b>int</c-></c-> <c- nf><c- nf>main</c-></c-><c- p><c- p>(</c-></c-><c- b><c- b>int</c-></c-><c- p><c- p>,</c-></c-> <c- b><c- b>char</c-></c-><c- o><c- o>**</c-></c-><c- p><c- p>)</c-></c->
<c- p><c- p>{</c-></c->
  <c- n><c- n>net</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>parameters</c-></c-> <c- n><c- n>listener_parameters</c-></c-> <c- o><c- o>=</c-></c-> <c- n><c- n>net</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>parameters</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>tcp</c-></c-><c- p><c- p>();</c-></c->

  <c- n><c- n>net</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>listener</c-></c-> <c- n><c- n>listener</c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>listener_parameters</c-></c-><c- p><c- p>,</c-></c-> <c- n><c- n>net</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>workqueue</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>main_queue</c-></c-><c- p><c- p>());</c-></c->
  <c- n><c- n>listener</c-></c-><c- p><c- p>.</c-></c-><c- n><c- n>on_new_connection</c-></c-><c- p><c- p>([]</c-></c-> <c- p><c- p>(</c-></c-><c- k><c- k>auto</c-></c-> <c- n><c- n>connection</c-></c-><c- p><c- p>)</c-></c-> <c- p><c- p>{</c-></c->
    <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>cout</c-></c-> <c- o><c- o>&lt;&lt;</c-></c-> <c- s><c- s>"Received new connection from a client!"</c-></c-> <c- o><c- o>&lt;&lt;</c-></c-> <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>endl</c-></c-><c- p><c- p>;</c-></c->
    <c- n><c- n>connection</c-></c-><c- p><c- p>.</c-></c-><c- n><c- n>start</c-></c-><c- p><c- p>();</c-></c->

    <c- n><c- n>connection</c-></c-><c- p><c- p>.</c-></c-><c- n><c- n>receive</c-></c-><c- p><c- p>().</c-></c-><c- n><c- n>then</c-></c-><c- p><c- p>([</c-></c-><c- n><c- n>connection</c-></c-><c- p><c- p>]</c-></c-> <c- p><c- p>(</c-></c-><c- k><c- k>auto</c-></c-> <c- n><c- n>request</c-></c-><c- p><c- p>)</c-></c-> <c- k><c- k>mutable</c-></c-> <c- p><c- p>{</c-></c->
      <c- k><c- k>if</c-></c-> <c- p><c- p>(</c-></c-><c- o><c- o>!</c-></c-><c- n><c- n>request</c-></c-><c- p><c- p>)</c-></c-> <c- p><c- p>{</c-></c->
        <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>cerr</c-></c-> <c- o><c- o>&lt;&lt;</c-></c-> <c- s><c- s>"Failed to receive request"</c-></c-> <c- o><c- o>&lt;&lt;</c-></c-> <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>endl</c-></c-><c- p><c- p>;</c-></c->
        <c- k><c- k>return</c-></c-><c- p><c- p>;</c-></c->
      <c- p><c- p>}</c-></c->

      <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>cout</c-></c-> <c- o><c- o>&lt;&lt;</c-></c-> <c- s><c- s>"Received request:"</c-></c-> <c- o><c- o>&lt;&lt;</c-></c-> <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>endl</c-></c-><c- p><c- p>;</c-></c->
      <c- n><c- n>request</c-></c-><c- o><c- o>-></c-></c-><c- n><c- n>data</c-></c-><c- p><c- p>().</c-></c-><c- n><c- n>get</c-></c-><c- p><c- p>([](</c-></c-><c- k><c- k>const</c-></c-> <c- b><c- b>uint8_t</c-></c-> <c- o><c- o>*</c-></c-><c- n><c- n>bytes</c-></c-><c- p><c- p>,</c-></c-> <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- b><c- b>size_t</c-></c-> <c- n><c- n>size</c-></c-><c- p><c- p>)</c-></c-> <c- p><c- p>{</c-></c->
        <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>cout</c-></c-> <c- o><c- o>&lt;&lt;</c-></c-> <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>string</c-></c-><c- p><c- p>(</c-></c-><c- k><c- k>reinterpret_cast</c-></c-><c- o><c- o>&lt;</c-></c-><c- k><c- k>const</c-></c-> <c- b><c- b>char</c-></c-> <c- o><c- o>*></c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>bytes</c-></c-><c- p><c- p>),</c-></c-> <c- n><c- n>size</c-></c-><c- p><c- p>);</c-></c->
      <c- p><c- p>});</c-></c->
      <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>cout</c-></c-> <c- o><c- o>&lt;&lt;</c-></c-> <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>endl</c-></c-><c- p><c- p>;</c-></c->

      <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>cout</c-></c-> <c- o><c- o>&lt;&lt;</c-></c-> <c- s><c- s>"Sending response"</c-></c-> <c- o><c- o>&lt;&lt;</c-></c-> <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>endl</c-></c-><c- p><c- p>;</c-></c->
      <c- n><c- n>net</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>buffer</c-></c-> <c- n><c- n>buffer</c-></c-><c- p><c- p>(</c-></c->
        <c- s><c- s>"HTTP/1.1 200 OK</c-></c-><c- se><c- se>\r\n</c-></c-><c- s><c- s>Content-Length: 23</c-></c-><c- se><c- se>\r\n\r\n</c-></c-><c- s><c- s>"</c-></c->
        <c- s><c- s>"The server says hello!</c-></c-><c- se><c- se>\n</c-></c-><c- s><c- s>"</c-></c->
      <c- p><c- p>);</c-></c->
      <c- n><c- n>connection</c-></c-><c- p><c- p>.</c-></c-><c- n><c- n>send</c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>net</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>message</c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>buffer</c-></c-><c- p><c- p>)).</c-></c-><c- n><c- n>then</c-></c-><c- p><c- p>([]</c-></c-> <c- p><c- p>(</c-></c-><c- k><c- k>auto</c-></c-> <c- n><c- n>result</c-></c-><c- p><c- p>)</c-></c-> <c- p><c- p>{</c-></c->
        <c- k><c- k>if</c-></c-> <c- p><c- p>(</c-></c-><c- o><c- o>!</c-></c-><c- n><c- n>result</c-></c-><c- p><c- p>)</c-></c-> <c- p><c- p>{</c-></c->
          <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>cerr</c-></c-> <c- o><c- o>&lt;&lt;</c-></c-> <c- s><c- s>"Failed to send response"</c-></c-> <c- o><c- o>&lt;&lt;</c-></c-> <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>endl</c-></c-><c- p><c- p>;</c-></c->
          <c- k><c- k>return</c-></c-><c- p><c- p>;</c-></c->
        <c- p><c- p>}</c-></c->
        <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>cout</c-></c-> <c- o><c- o>&lt;&lt;</c-></c-> <c- s><c- s>"Successfully sent response"</c-></c-> <c- o><c- o>&lt;&lt;</c-></c-> <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>endl</c-></c-><c- p><c- p>;</c-></c->
      <c- p><c- p>});</c-></c->
    <c- p><c- p>});</c-></c->
  <c- p><c- p>});</c-></c->

  <c- n><c- n>listener</c-></c-><c- p><c- p>.</c-></c-><c- n><c- n>on_state_changed</c-></c-><c- p><c- p>([</c-></c-><c- n><c- n>listener</c-></c-><c- p><c- p>](</c-></c-><c- k><c- k>auto</c-></c-> <c- n><c- n>state</c-></c-><c- p><c- p>,</c-></c-> <c- k><c- k>auto</c-></c-> <c- n><c- n>error</c-></c-><c- p><c- p>)</c-></c-> <c- p><c- p>{</c-></c->
    <c- k><c- k>if</c-></c-> <c- p><c- p>(</c-></c-><c- o><c- o>!</c-></c-><c- n><c- n>error</c-></c-> <c- o><c- o>&amp;&amp;</c-></c-> <c- n><c- n>state</c-></c-> <c- o><c- o>==</c-></c-> <c- n><c- n>net</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>listener</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>state</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>ready</c-></c-><c- p><c- p>)</c-></c-> <c- p><c- p>{</c-></c->
      <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>cout</c-></c-> <c- o><c- o>&lt;&lt;</c-></c-> <c- s><c- s>"server is now ready and listening. "</c-></c-><c- p><c- p>;</c-></c->
      <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>cout</c-></c-> <c- o><c- o>&lt;&lt;</c-></c-> <c- s><c- s>"curl http://127.0.0.1:"</c-></c-> <c- o><c- o>&lt;&lt;</c-></c-> <c- n><c- n>listener</c-></c-><c- p><c- p>.</c-></c-><c- n><c- n>port</c-></c-><c- p><c- p>();</c-></c->
      <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>cout</c-></c-> <c- o><c- o>&lt;&lt;</c-></c-> <c- s><c- s>"/ -v"</c-></c-> <c- o><c- o>&lt;&lt;</c-></c-> <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>endl</c-></c-><c- p><c- p>;</c-></c->
    <c- p><c- p>}</c-></c->
  <c- p><c- p>});</c-></c->

  <c- n><c- n>listener</c-></c-><c- p><c- p>.</c-></c-><c- n><c- n>start</c-></c-><c- p><c- p>();</c-></c->

  <c- n><c- n>net</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>workqueue</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>main</c-></c-><c- p><c- p>();</c-></c->
<c- p><c- p>}</c-></c->
</code></pre>
   <p>Which can be changed into a TLS server by adding these lines after the declaration of <code class="highlight"><c- n>listener_parameters</c-></code>:</p>
<pre class="highlight"><code class="highlight"><c- c1><c- c1>// This is a test RSA private key from BoringSSL.</c-></c->
<c- k><c- k>auto</c-></c-> <c- n><c- n>rsa_private_key</c-></c-> <c- o><c- o>=</c-></c-> <c- n><c- n>base64_decode</c-></c-><c- p><c- p>(</c-></c->
  <c- s><c- s>"MIICXgIBAAKBgQDYK8imMuRi/03z0K1Zi0WnvfFHvwlYeyK9Na6XJYaUoIDAtB92"</c-></c->
  <c- s><c- s>"kWdGMdAQhLciHnAjkXLI6W15OoV3gA/ElRZ1xUpxTMhjP6PyY5wqT5r6y8FxbiiF"</c-></c->
  <c- s><c- s>"KKAnHmUcrgfVW28tQ+0rkLGMryRtrukXOgXBv7gcrmU7G1jC2a7WqmeI8QIDAQAB"</c-></c->
  <c- s><c- s>"AoGBAIBy09Fd4DOq/Ijp8HeKuCMKTHqTW1xGHshLQ6jwVV2vWZIn9aIgmDsvkjCe"</c-></c->
  <c- s><c- s>"i6ssZvnbjVcwzSoByhjN8ZCf/i15HECWDFFh6gt0P5z0MnChwzZmvatV/FXCT0j+"</c-></c->
  <c- s><c- s>"WmGNB/gkehKjGXLLcjTb6dRYVJSCZhVuOLLcbWIV10gggJQBAkEA8S8sGe4ezyyZ"</c-></c->
  <c- s><c- s>"m4e9r95g6s43kPqtj5rewTsUxt+2n4eVodD+ZUlCULWVNAFLkYRTBCASlSrm9Xhj"</c-></c->
  <c- s><c- s>"QpmWAHJUkQJBAOVzQdFUaewLtdOJoPCtpYoY1zd22eae8TQEmpGOR11L6kbxLQsk"</c-></c->
  <c- s><c- s>"aMly/DOnOaa82tqAGTdqDEZgSNmCeKKknmECQAvpnY8GUOVAubGR6c+W90iBuQLj"</c-></c->
  <c- s><c- s>"LtFp/9ihd2w/PoDwrHZaoUYVcT4VSfJQog/k7kjE4MYXYWL8eEKg3WTWQNECQQDk"</c-></c->
  <c- s><c- s>"104Wi91Umd1PzF0ijd2jXOERJU1wEKe6XLkYYNHWQAe5l4J4MWj9OdxFXAxIuuR/"</c-></c->
  <c- s><c- s>"tfDwbqkta4xcux67//khAkEAvvRXLHTaa6VFzTaiiO8SaFsHV3lQyXOtMrBpB5jd"</c-></c->
  <c- s><c- s>"moZWgjHvB2W9Ckn7sDqsPB+U2tyX0joDdQEyuiMECDY8oQ=="</c-></c->
<c- p><c- p>);</c-></c->
  
<c- c1><c- c1>// This is a test self-signed certificate from BoringSSL.</c-></c->
<c- k><c- k>auto</c-></c-> <c- n><c- n>certificate_bytes</c-></c-> <c- o><c- o>=</c-></c-> <c- n><c- n>base64_decode</c-></c-><c- p><c- p>(</c-></c->
  <c- s><c- s>"MIICWDCCAcGgAwIBAgIJAPuwTC6rEJsMMA0GCSqGSIb3DQEBBQUAMEUxCzAJBgNV"</c-></c->
  <c- s><c- s>"BAYTAkFVMRMwEQYDVQQIDApTb21lLVN0YXRlMSEwHwYDVQQKDBhJbnRlcm5ldCBX"</c-></c->
  <c- s><c- s>"aWRnaXRzIFB0eSBMdGQwHhcNMTQwNDIzMjA1MDQwWhcNMTcwNDIyMjA1MDQwWjBF"</c-></c->
  <c- s><c- s>"MQswCQYDVQQGEwJBVTETMBEGA1UECAwKU29tZS1TdGF0ZTEhMB8GA1UECgwYSW50"</c-></c->
  <c- s><c- s>"ZXJuZXQgV2lkZ2l0cyBQdHkgTHRkMIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKB"</c-></c->
  <c- s><c- s>"gQDYK8imMuRi/03z0K1Zi0WnvfFHvwlYeyK9Na6XJYaUoIDAtB92kWdGMdAQhLci"</c-></c->
  <c- s><c- s>"HnAjkXLI6W15OoV3gA/ElRZ1xUpxTMhjP6PyY5wqT5r6y8FxbiiFKKAnHmUcrgfV"</c-></c->
  <c- s><c- s>"W28tQ+0rkLGMryRtrukXOgXBv7gcrmU7G1jC2a7WqmeI8QIDAQABo1AwTjAdBgNV"</c-></c->
  <c- s><c- s>"HQ4EFgQUi3XVrMsIvg4fZbf6Vr5sp3Xaha8wHwYDVR0jBBgwFoAUi3XVrMsIvg4f"</c-></c->
  <c- s><c- s>"Zbf6Vr5sp3Xaha8wDAYDVR0TBAUwAwEB/zANBgkqhkiG9w0BAQUFAAOBgQA76Hht"</c-></c->
  <c- s><c- s>"ldY9avcTGSwbwoiuIqv0jTL1fHFnzy3RHMLDh+Lpvolc5DSrSJHCP5WuK0eeJXhr"</c-></c->
  <c- s><c- s>"T5oQpHL9z/cCDLAKCKRa4uV0fhEdOWBqyR9p8y5jJtye72t6CuFUV5iqcpF4BH4f"</c-></c->
  <c- s><c- s>"j2VNHwsSrJwkD4QUGlUtH7vwnQmyCFxZMmWAJg=="</c-></c->
<c- p><c- p>);</c-></c->

<c- n><c- n>net</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>protocol</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>security</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>certificate</c-></c-> <c- n><c- n>certificate</c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>certificate_bytes</c-></c-><c- p><c- p>);</c-></c->
<c- n><c- n>net</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>protocol</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>security</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>identity</c-></c-> <c- n><c- n>identity</c-></c-><c- p><c- p>({</c-></c-> <c- n><c- n>certificate</c-></c-> <c- p><c- p>},</c-></c-> <c- n><c- n>rsa_private_key</c-></c-><c- p><c- p>);</c-></c->
<c- n><c- n>net</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>protocol</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>security</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>options</c-></c-> <c- n><c- n>tls_options</c-></c-><c- p><c- p>;</c-></c->
<c- n><c- n>tls_options</c-></c-><c- p><c- p>.</c-></c-><c- n><c- n>set_local_identity</c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>identity</c-></c-><c- p><c- p>);</c-></c->
<c- n><c- n>listener_parameters</c-></c-><c- p><c- p>.</c-></c-><c- n><c- n>set_application_protocols</c-></c-><c- p><c- p>({</c-></c-> <c- n><c- n>tls_options</c-></c-> <c- p><c- p>});</c-></c->
</code></pre>
   <p><code class="highlight"><c- n>http</c-></code> would need to be changed to <code class="highlight"><c- n>https</c-></code> and <code class="highlight"><c- o>-</c-><c- n>v</c-></code> would need to be changed to <code class="highlight"><c- o>-</c-><c- n>v</c-> <c- o>--</c-><c- n>insecure</c-></code> to allow curl to connect to this server successfully.
It requires curl’s <code class="highlight"><c- n>insecure</c-></code> flag because it uses a self-signed certificate instead of a certificate chain with a trusted root certificate authority. This is useful for local development, but obviously requires a certificate for production usage.</p>
   <h3 class="heading settled" data-level="6.3" id="pathlistener"><span class="secno">6.3. </span><span class="content">Path Listener</span><a class="self-link" href="#pathlistener"></a></h3>
   <p>This is one of the great advantages of this suggested API.  It allows people to write programs that are common today but unheard of in the 1980’s when sockets were designed.</p>
<pre class="highlight"><code class="highlight"><c- cp><c- cp>#include</c-></c-> &lt;iostream>
<c- cp><c- cp>#include</c-></c-> &lt;net>

<c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>ostream</c-></c-><c- o><c- o>&amp;</c-></c-> <c- k><c- k>operator</c-></c-><c- o><c- o>&lt;&lt;</c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>ostream</c-></c-><c- o><c- o>&amp;</c-></c-> <c- n><c- n>os</c-></c-><c- p><c- p>,</c-></c-> <c- k><c- k>const</c-></c-> <c- n><c- n>net</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>path</c-></c-><c- o><c- o>&amp;</c-></c-> <c- n><c- n>path</c-></c-><c- p><c- p>)</c-></c->
<c- p><c- p>{</c-></c->
  <c- k><c- k>for</c-></c-> <c- p><c- p>(</c-></c-><c- k><c- k>auto</c-></c-><c- o><c- o>&amp;</c-></c-> <c- nl><c- nl>interface</c-></c-> <c- p><c- p>:</c-></c-> <c- n><c- n>path</c-></c-><c- p><c- p>.</c-></c-><c- n><c- n>available_interfaces</c-></c-><c- p><c- p>())</c-></c->
    <c- n><c- n>os</c-></c-> <c- o><c- o>&lt;&lt;</c-></c-> <c- s><c- s>"interface: "</c-></c-> <c- o><c- o>&lt;&lt;</c-></c-> <c- n><c- n>interface</c-></c-><c- p><c- p>.</c-></c-><c- n><c- n>name</c-></c-><c- p><c- p>()</c-></c-> <c- o><c- o>&lt;&lt;</c-></c-> <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>endl</c-></c-><c- p><c- p>;</c-></c->
  <c- k><c- k>return</c-></c-> <c- n><c- n>os</c-></c-><c- p><c- p>;</c-></c->
<c- p><c- p>}</c-></c->

<c- b><c- b>int</c-></c-> <c- n><c- n>main</c-></c-><c- p><c- p>(</c-></c-><c- b><c- b>int</c-></c-><c- p><c- p>,</c-></c-> <c- b><c- b>char</c-></c-> <c- o><c- o>**</c-></c-><c- p><c- p>)</c-></c->
<c- p><c- p>{</c-></c->
  <c- n><c- n>net</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>path_monitor</c-></c-> <c- n><c- n>monitor</c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>net</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>workqueue</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>main_queue</c-></c-><c- p><c- p>());</c-></c->
  <c- n><c- n>monitor</c-></c-><c- p><c- p>.</c-></c-><c- n><c- n>on_update</c-></c-><c- p><c- p>([](</c-></c-><c- k><c- k>auto</c-></c-> <c- n><c- n>path</c-></c-><c- p><c- p>)</c-></c-> <c- p><c- p>{</c-></c->
    <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>cout</c-></c-> <c- o><c- o>&lt;&lt;</c-></c-> <c- s><c- s>"path update: "</c-></c-> <c- o><c- o>&lt;&lt;</c-></c-> <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>endl</c-></c-> <c- o><c- o>&lt;&lt;</c-></c-> <c- n><c- n>path</c-></c-><c- p><c- p>;</c-></c->
  <c- p><c- p>});</c-></c->

  <c- n><c- n>net</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>workqueue</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>main</c-></c-><c- p><c- p>();</c-></c->
<c- p><c- p>}</c-></c->
</code></pre>
   <p>This simple program will print status updates when the network interfaces changes, such as when WiFi is connected or when a mobile device enters an area
without cellular data availability.</p>
   <h3 class="heading settled" data-level="6.4" id="framer"><span class="secno">6.4. </span><span class="content">Protocol Framer</span><a class="self-link" href="#framer"></a></h3>
   <p>This is an implementation of a subset of HTTP.  It allows setting method, path, and header fields of HTTP requests, and it parses the response header all as one string in the metadata and the passes the body through to <code class="highlight"><c- n>connection</c-><c- p>.</c-><c- n>receive</c-><c- p>()</c-></code>.  This example also uses <code class="highlight"><c- n>std</c-><c- o>::</c-><c- n>lazy</c-></code> from <a data-link-type="biblio" href="#biblio-p1056r1">[p1056r1]</a>.</p>
<pre class="highlight"><code class="highlight"><c- cp><c- cp>#include</c-></c-> &lt;net>
<c- cp><c- cp>#include</c-></c-> &lt;stdio.h>
<c- cp><c- cp>#include</c-></c-> &lt;unordered_map>
<c- cp><c- cp>#include</c-></c-> &lt;sstream>

<c- k><c- k>class</c-></c-> <c- nc><c- nc>http</c-></c-> <c- p><c- p>{</c-></c->
<c- k><c- k>public</c-></c-><c- o><c- o>:</c-></c->
  <c- k><c- k>using</c-></c-> <c- n><c- n>framer</c-></c-> <c- o><c- o>=</c-></c-> <c- n><c- n>net</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>protocol</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>framer</c-></c-><c- o><c- o>&lt;</c-></c-><c- n><c- n>http</c-></c-><c- o><c- o>></c-></c-><c- p><c- p>;</c-></c->

  <c- k><c- k>enum</c-></c-> <c- k><c- k>class</c-></c-> <c- nc><c- nc>method</c-></c-> <c- p><c- p>{</c-></c-> <c- n><c- n>get</c-></c-><c- p><c- p>,</c-></c-> <c- n><c- n>post</c-></c-> <c- p><c- p>};</c-></c->

  <c- k><c- k>enum</c-></c-> <c- k><c- k>class</c-></c-> <c- nc><c- nc>response_parsing_state</c-></c-> <c- p><c- p>{</c-></c->
    <c- n><c- n>looking_for_first_carriage_return</c-></c-><c- p><c- p>,</c-></c->
    <c- n><c- n>looking_for_first_newline</c-></c-><c- p><c- p>,</c-></c->
    <c- n><c- n>looking_for_second_carriage_return</c-></c-><c- p><c- p>,</c-></c->
    <c- n><c- n>looking_for_second_newline</c-></c-><c- p><c- p>,</c-></c->
    <c- n><c- n>body</c-></c->
  <c- p><c- p>};</c-></c->

  <c- k><c- k>static</c-></c-> <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>string_view</c-></c-> <c- n><c- n>label</c-></c-><c- p><c- p>()</c-></c-> <c- p><c- p>{</c-></c-> <c- k><c- k>return</c-></c-> <c- s><c- s>"http"</c-></c-><c- p><c- p>;</c-></c-> <c- p><c- p>}</c-></c->
  <c- k><c- k>static</c-></c-> <c- n><c- n>net</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>protocol</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>definition</c-></c-> <c- n><c- n>definition</c-></c-><c- p><c- p>()</c-></c-> <c- p><c- p>{</c-></c-> <c- k><c- k>return</c-></c-> <c- n><c- n>framer</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>definition</c-></c-><c- p><c- p>();</c-></c-> <c- p><c- p>}</c-></c->
  <c- k><c- k>class</c-></c-> <c- nc><c- nc>options</c-></c-> <c- o><c- o>:</c-></c-> <c- k><c- k>public</c-></c-> <c- n><c- n>framer</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>options</c-></c-> <c- p><c- p>{</c-></c-> <c- p><c- p>};</c-></c->

  <c- k><c- k>class</c-></c-> <c- nc><c- nc>metadata</c-></c-> <c- o><c- o>:</c-></c-> <c- k><c- k>public</c-></c-> <c- n><c- n>framer</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>metadata</c-></c-> <c- p><c- p>{</c-></c->
  <c- k><c- k>public</c-></c-><c- o><c- o>:</c-></c->
    <c- k><c- k>using</c-></c-> <c- n><c- n>framer</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>metadata</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>metadata</c-></c-><c- p><c- p>;</c-></c->

    <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>string</c-></c-> <c- n><c- n>path</c-></c-><c- p><c- p>()</c-></c-> <c- k><c- k>const</c-></c->
    <c- p><c- p>{</c-></c->
      <c- k><c- k>if</c-></c-> <c- p><c- p>(</c-></c-><c- k><c- k>auto</c-></c-> <c- n><c- n>value</c-></c-> <c- o><c- o>=</c-></c-> <c- n><c- n>get_value</c-></c-><c- o><c- o>&lt;</c-></c-><c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>string</c-></c-><c- o><c- o>></c-></c-><c- p><c- p>(</c-></c-><c- s><c- s>"path"</c-></c-><c- p><c- p>))</c-></c->
        <c- k><c- k>return</c-></c-> <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>move</c-></c-><c- p><c- p>(</c-></c-><c- o><c- o>*</c-></c-><c- n><c- n>value</c-></c-><c- p><c- p>);</c-></c->
      <c- k><c- k>return</c-></c-> <c- s><c- s>"/"</c-></c-><c- p><c- p>;</c-></c->
    <c- p><c- p>}</c-></c->
    <c- n><c- n>metadata</c-></c-><c- o><c- o>&amp;</c-></c-> <c- n><c- n>set_path</c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>string</c-></c-> <c- n><c- n>path</c-></c-><c- p><c- p>)</c-></c->
    <c- p><c- p>{</c-></c->
      <c- n><c- n>set_value</c-></c-><c- p><c- p>(</c-></c-><c- s><c- s>"path"</c-></c-><c- p><c- p>,</c-></c-> <c- n><c- n>path</c-></c-><c- p><c- p>);</c-></c->
      <c- k><c- k>return</c-></c-> <c- o><c- o>*</c-></c-><c- k><c- k>this</c-></c-><c- p><c- p>;</c-></c->
    <c- p><c- p>}</c-></c->

    <c- n><c- n>method</c-></c-> <c- n><c- n>method</c-></c-><c- p><c- p>()</c-></c-> <c- k><c- k>const</c-></c->
    <c- p><c- p>{</c-></c->
      <c- k><c- k>if</c-></c-> <c- p><c- p>(</c-></c-><c- k><c- k>auto</c-></c-> <c- n><c- n>value</c-></c-> <c- o><c- o>=</c-></c-> <c- n><c- n>get_value</c-></c-><c- o><c- o>&lt;</c-></c-><c- k><c- k>enum</c-></c-> <c- n><c- n>method</c-></c-><c- o><c- o>></c-></c-><c- p><c- p>(</c-></c-><c- s><c- s>"method"</c-></c-><c- p><c- p>))</c-></c->
        <c- k><c- k>return</c-></c-> <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>move</c-></c-><c- p><c- p>(</c-></c-><c- o><c- o>*</c-></c-><c- n><c- n>value</c-></c-><c- p><c- p>);</c-></c->
      <c- k><c- k>return</c-></c-> <c- n><c- n>method</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>get</c-></c-><c- p><c- p>;</c-></c->
    <c- p><c- p>}</c-></c->
    <c- n><c- n>metadata</c-></c-><c- o><c- o>&amp;</c-></c-> <c- n><c- n>set_method</c-></c-><c- p><c- p>(</c-></c-><c- k><c- k>enum</c-></c-> <c- n><c- n>method</c-></c-> <c- n><c- n>method</c-></c-><c- p><c- p>)</c-></c->
    <c- p><c- p>{</c-></c->
      <c- n><c- n>set_value</c-></c-><c- p><c- p>(</c-></c-><c- s><c- s>"method"</c-></c-><c- p><c- p>,</c-></c-> <c- n><c- n>method</c-></c-><c- p><c- p>);</c-></c->
      <c- k><c- k>return</c-></c-> <c- o><c- o>*</c-></c-><c- k><c- k>this</c-></c-><c- p><c- p>;</c-></c->
    <c- p><c- p>}</c-></c->
    
    <c- k><c- k>using</c-></c-> <c- n><c- n>header_fields_t</c-></c-> <c- o><c- o>=</c-></c-> <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>unordered_map</c-></c-><c- o><c- o>&lt;</c-></c-><c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>string</c-></c-><c- p><c- p>,</c-></c-> <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>string</c-></c-><c- o><c- o>></c-></c-><c- p><c- p>;</c-></c->
    <c- n><c- n>header_fields_t</c-></c-> <c- nf><c- nf>header_fields</c-></c-><c- p><c- p>()</c-></c-> <c- k><c- k>const</c-></c->
    <c- p><c- p>{</c-></c->
      <c- k><c- k>if</c-></c-> <c- p><c- p>(</c-></c-><c- k><c- k>auto</c-></c-> <c- n><c- n>value</c-></c-> <c- o><c- o>=</c-></c-> <c- n><c- n>get_value</c-></c-><c- o><c- o>&lt;</c-></c-><c- n><c- n>header_fields_t</c-></c-><c- o><c- o>></c-></c-><c- p><c- p>(</c-></c-><c- s><c- s>"header_fields"</c-></c-><c- p><c- p>))</c-></c->
        <c- k><c- k>return</c-></c-> <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>move</c-></c-><c- p><c- p>(</c-></c-><c- o><c- o>*</c-></c-><c- n><c- n>value</c-></c-><c- p><c- p>);</c-></c->
      <c- k><c- k>return</c-></c-> <c- p><c- p>{</c-></c-> <c- p><c- p>};</c-></c->
    <c- p><c- p>}</c-></c->
    <c- n><c- n>metadata</c-></c-><c- o><c- o>&amp;</c-></c-> <c- n><c- n>set_header_fields</c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>header_fields_t</c-></c-> <c- n><c- n>fields</c-></c-><c- p><c- p>)</c-></c->
    <c- p><c- p>{</c-></c->
      <c- n><c- n>set_value</c-></c-><c- p><c- p>(</c-></c-><c- s><c- s>"header_fields"</c-></c-><c- p><c- p>,</c-></c-> <c- n><c- n>fields</c-></c-><c- p><c- p>);</c-></c->
      <c- k><c- k>return</c-></c-> <c- o><c- o>*</c-></c-><c- k><c- k>this</c-></c-><c- p><c- p>;</c-></c->
    <c- p><c- p>}</c-></c->

    <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>string</c-></c-> <c- n><c- n>response_header</c-></c-><c- p><c- p>()</c-></c-> <c- k><c- k>const</c-></c->
    <c- p><c- p>{</c-></c->
      <c- k><c- k>if</c-></c-> <c- p><c- p>(</c-></c-><c- k><c- k>auto</c-></c-> <c- n><c- n>value</c-></c-> <c- o><c- o>=</c-></c-> <c- n><c- n>get_value</c-></c-><c- o><c- o>&lt;</c-></c-><c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>string</c-></c-><c- o><c- o>></c-></c-><c- p><c- p>(</c-></c-><c- s><c- s>"response_header"</c-></c-><c- p><c- p>))</c-></c->
        <c- k><c- k>return</c-></c-> <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>move</c-></c-><c- p><c- p>(</c-></c-><c- o><c- o>*</c-></c-><c- n><c- n>value</c-></c-><c- p><c- p>);</c-></c->
      <c- k><c- k>return</c-></c-> <c- p><c- p>{</c-></c-> <c- p><c- p>};</c-></c->
    <c- p><c- p>}</c-></c->
    <c- n><c- n>metadata</c-></c-><c- o><c- o>&amp;</c-></c-> <c- n><c- n>set_response_header</c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>string</c-></c-> <c- n><c- n>header</c-></c-><c- p><c- p>)</c-></c->
    <c- p><c- p>{</c-></c->
      <c- n><c- n>set_value</c-></c-><c- p><c- p>(</c-></c-><c- s><c- s>"response_header"</c-></c-><c- p><c- p>,</c-></c-> <c- n><c- n>header</c-></c-><c- p><c- p>);</c-></c->
      <c- k><c- k>return</c-></c-> <c- o><c- o>*</c-></c-><c- k><c- k>this</c-></c-><c- p><c- p>;</c-></c->
    <c- p><c- p>}</c-></c->
  <c- p><c- p>};</c-></c->

  <c- n><c- n>http</c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>framer</c-></c-> <c- n><c- n>framer</c-></c-><c- p><c- p>)</c-></c-> <c- o><c- o>:</c-></c-> <c- n><c- n>m_framer</c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>move</c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>framer</c-></c-><c- p><c- p>))</c-></c-> <c- p><c- p>{</c-></c-> <c- p><c- p>}</c-></c->

  <c- b><c- b>size_t</c-></c-> <c- n><c- n>handle_input</c-></c-><c- p><c- p>();</c-></c->

  <c- b><c- b>void</c-></c-> <c- nf><c- nf>handle_output</c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>net</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>protocol</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>metadata</c-></c-><c- p><c- p>,</c-></c-> <c- b><c- b>size_t</c-></c-><c- p><c- p>,</c-></c-> <c- b><c- b>bool</c-></c-><c- p><c- p>);</c-></c->

<c- k><c- k>private</c-></c-><c- o><c- o>:</c-></c->
  <c- n><c- n>framer</c-></c-> <c- n><c- n>m_framer</c-></c-><c- p><c- p>;</c-></c->
  <c- n><c- n>response_parsing_state</c-></c-> <c- n><c- n>m_state</c-></c-> <c- p><c- p>{</c-></c->
    <c- n><c- n>response_parsing_state</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>looking_for_first_carriage_return</c-></c->
  <c- p><c- p>};</c-></c->

  <c- n><c- n>metadata</c-></c-> <c- n><c- n>m_response_metadata</c-></c-><c- p><c- p>;</c-></c->
  <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>ostringstream</c-></c-> <c- n><c- n>m_response_header_stream</c-></c-><c- p><c- p>;</c-></c->
<c- p><c- p>};</c-></c->

<c- b><c- b>size_t</c-></c-> <c- n><c- n>http</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>handle_input</c-></c-><c- p><c- p>()</c-></c->
<c- p><c- p>{</c-></c->
  <c- k><c- k>auto</c-></c-> <c- n><c- n>ok</c-></c-> <c- o><c- o>=</c-></c-> <c- n><c- n>m_framer</c-></c-><c- p><c- p>.</c-></c-><c- n><c- n>parse_input</c-></c-><c- p><c- p>(</c-></c-><c- mi><c- mi>1</c-></c-><c- p><c- p>,</c-></c-> <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>numeric_limits</c-></c-><c- o><c- o>&lt;</c-></c-><c- b><c- b>size_t</c-></c-><c- o><c- o>>::</c-></c-><c- n><c- n>max</c-></c-><c- p><c- p>(),</c-></c->
    <c- p><c- p>[</c-></c-><c- o><c- o>&amp;</c-></c-><c- p><c- p>](</c-></c-><c- k><c- k>const</c-></c-> <c- b><c- b>void</c-></c-> <c- o><c- o>*</c-></c-><c- n><c- n>buffer</c-></c-><c- p><c- p>,</c-></c-> <c- b><c- b>size_t</c-></c-> <c- n><c- n>length</c-></c-><c- p><c- p>,</c-></c-> <c- b><c- b>bool</c-></c-> <c- n><c- n>is_complete</c-></c-><c- p><c- p>)</c-></c-> <c- o><c- o>-></c-></c-> <c- b><c- b>size_t</c-></c-> <c- p><c- p>{</c-></c->
    <c- c1><c- c1>// "\r\n\r\n" indicates the end of the header and beginning of body,</c-></c->
    <c- c1><c- c1>// which we want to deliver. This is just a state machine looking for that,</c-></c->
    <c- c1><c- c1>// which may be in two different input pieces.</c-></c->
    <c- k><c- k>const</c-></c-> <c- b><c- b>char</c-></c-><c- o><c- o>*</c-></c-> <c- n><c- n>char_buffer</c-></c-> <c- o><c- o>=</c-></c-> <c- k><c- k>static_cast</c-></c-><c- o><c- o>&lt;</c-></c-><c- k><c- k>const</c-></c-> <c- b><c- b>char</c-></c-><c- o><c- o>*></c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>buffer</c-></c-><c- p><c- p>);</c-></c->
    <c- k><c- k>for</c-></c-> <c- p><c- p>(</c-></c-><c- b><c- b>size_t</c-></c-> <c- n><c- n>i</c-></c-> <c- o><c- o>=</c-></c-> <c- mi><c- mi>0</c-></c-><c- p><c- p>;</c-></c-> <c- n><c- n>i</c-></c-> <c- o><c- o>&lt;</c-></c-> <c- n><c- n>length</c-></c-><c- p><c- p>;</c-></c-> <c- o><c- o>++</c-></c-><c- n><c- n>i</c-></c-><c- p><c- p>)</c-></c-> <c- p><c- p>{</c-></c->
      <c- b><c- b>char</c-></c-> <c- n><c- n>c</c-></c-> <c- o><c- o>=</c-></c-> <c- n><c- n>char_buffer</c-></c-><c- p><c- p>[</c-></c-><c- n><c- n>i</c-></c-><c- p><c- p>];</c-></c->
      <c- n><c- n>m_response_header_stream</c-></c-> <c- o><c- o>&lt;&lt;</c-></c-> <c- n><c- n>c</c-></c-><c- p><c- p>;</c-></c->
      <c- k><c- k>switch</c-></c-> <c- p><c- p>(</c-></c-><c- n><c- n>m_state</c-></c-><c- p><c- p>)</c-></c-> <c- p><c- p>{</c-></c->
        <c- k><c- k>case</c-></c-> <c- n><c- n>response_parsing_state</c-></c-><c- o><c- o>::</c-></c-><c- nl><c- nl>looking_for_first_carriage_return</c-></c-><c- p><c- p>:</c-></c->
          <c- k><c- k>if</c-></c-> <c- p><c- p>(</c-></c-><c- n><c- n>c</c-></c-> <c- o><c- o>==</c-></c-> <c- sc><c- sc>'\r'</c-></c-><c- p><c- p>)</c-></c->
            <c- n><c- n>m_state</c-></c-> <c- o><c- o>=</c-></c-> <c- n><c- n>response_parsing_state</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>looking_for_first_newline</c-></c-><c- p><c- p>;</c-></c->
          <c- k><c- k>break</c-></c-><c- p><c- p>;</c-></c->
        <c- k><c- k>case</c-></c-> <c- n><c- n>response_parsing_state</c-></c-><c- o><c- o>::</c-></c-><c- nl><c- nl>looking_for_first_newline</c-></c-><c- p><c- p>:</c-></c->
          <c- k><c- k>if</c-></c-> <c- p><c- p>(</c-></c-><c- n><c- n>c</c-></c-> <c- o><c- o>==</c-></c-> <c- sc><c- sc>'\n'</c-></c-><c- p><c- p>)</c-></c->
            <c- n><c- n>m_state</c-></c-> <c- o><c- o>=</c-></c-> <c- n><c- n>response_parsing_state</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>looking_for_second_carriage_return</c-></c-><c- p><c- p>;</c-></c->
          <c- k><c- k>else</c-></c->
            <c- n><c- n>m_state</c-></c-> <c- o><c- o>=</c-></c-> <c- n><c- n>response_parsing_state</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>looking_for_first_carriage_return</c-></c-><c- p><c- p>;</c-></c->
          <c- k><c- k>break</c-></c-><c- p><c- p>;</c-></c->
        <c- k><c- k>case</c-></c-> <c- n><c- n>response_parsing_state</c-></c-><c- o><c- o>::</c-></c-><c- nl><c- nl>looking_for_second_carriage_return</c-></c-><c- p><c- p>:</c-></c->
          <c- k><c- k>if</c-></c-> <c- p><c- p>(</c-></c-><c- n><c- n>c</c-></c-> <c- o><c- o>==</c-></c-> <c- sc><c- sc>'\r'</c-></c-><c- p><c- p>)</c-></c->
            <c- n><c- n>m_state</c-></c-> <c- o><c- o>=</c-></c-> <c- n><c- n>response_parsing_state</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>looking_for_second_newline</c-></c-><c- p><c- p>;</c-></c->
          <c- k><c- k>else</c-></c->
            <c- n><c- n>m_state</c-></c-> <c- o><c- o>=</c-></c-> <c- n><c- n>response_parsing_state</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>looking_for_first_carriage_return</c-></c-><c- p><c- p>;</c-></c->
          <c- k><c- k>break</c-></c-><c- p><c- p>;</c-></c->
        <c- k><c- k>case</c-></c-> <c- n><c- n>response_parsing_state</c-></c-><c- o><c- o>::</c-></c-><c- nl><c- nl>looking_for_second_newline</c-></c-><c- p><c- p>:</c-></c->
          <c- k><c- k>if</c-></c-> <c- p><c- p>(</c-></c-><c- n><c- n>c</c-></c-> <c- o><c- o>==</c-></c-> <c- sc><c- sc>'\n'</c-></c-><c- p><c- p>)</c-></c-> <c- p><c- p>{</c-></c->
            <c- n><c- n>m_state</c-></c-> <c- o><c- o>=</c-></c-> <c- n><c- n>response_parsing_state</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>body</c-></c-><c- p><c- p>;</c-></c->
            <c- n><c- n>m_response_metadata</c-></c-><c- p><c- p>.</c-></c-><c- n><c- n>set_response_header</c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>m_response_header_stream</c-></c-><c- p><c- p>.</c-></c-><c- n><c- n>str</c-></c-><c- p><c- p>());</c-></c->
          <c- p><c- p>}</c-></c-> <c- k><c- k>else</c-></c->
            <c- n><c- n>m_state</c-></c-> <c- o><c- o>=</c-></c-> <c- n><c- n>response_parsing_state</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>looking_for_first_carriage_return</c-></c-><c- p><c- p>;</c-></c->
          <c- k><c- k>break</c-></c-><c- p><c- p>;</c-></c->
        <c- k><c- k>case</c-></c-> <c- n><c- n>response_parsing_state</c-></c-><c- o><c- o>::</c-></c-><c- nl><c- nl>body</c-></c-><c- p><c- p>:</c-></c->
          <c- n><c- n>m_framer</c-></c-><c- p><c- p>.</c-></c-><c- n><c- n>deliver_input</c-></c-><c- p><c- p>(</c-></c->
            <c- n><c- n>char_buffer</c-></c-> <c- o><c- o>+</c-></c-> <c- n><c- n>i</c-></c-><c- p><c- p>,</c-></c->
            <c- n><c- n>length</c-></c-> <c- o><c- o>-</c-></c-> <c- n><c- n>i</c-></c-><c- p><c- p>,</c-></c->
            <c- n><c- n>m_response_metadata</c-></c-><c- p><c- p>,</c-></c->
            <c- n><c- n>is_complete</c-></c->
          <c- p><c- p>);</c-></c->
          <c- k><c- k>return</c-></c-> <c- n><c- n>length</c-></c-><c- p><c- p>;</c-></c->
      <c- p><c- p>}</c-></c->
    <c- p><c- p>}</c-></c->
    <c- k><c- k>return</c-></c-> <c- n><c- n>length</c-></c-><c- p><c- p>;</c-></c->
  <c- p><c- p>});</c-></c->

  <c- k><c- k>if</c-></c-> <c- p><c- p>(</c-></c-><c- o><c- o>!</c-></c-><c- n><c- n>ok</c-></c-><c- p><c- p>)</c-></c->
    <c- n><c- n>m_framer</c-></c-><c- p><c- p>.</c-></c-><c- n><c- n>mark_failed</c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>make_error_code</c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>errc</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>protocol_error</c-></c-><c- p><c- p>));</c-></c->

  <c- k><c- k>return</c-></c-> <c- mi><c- mi>0</c-></c-><c- p><c- p>;</c-></c->
<c- p><c- p>}</c-></c->

<c- b><c- b>void</c-></c-> <c- n><c- n>handle_output</c-></c-><c- p><c- p>(</c-></c->
  <c- n><c- n>net</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>protocol</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>metadata</c-></c-> <c- n><c- n>metadata</c-></c-><c- p><c- p>,</c-></c->
  <c- b><c- b>size_t</c-></c-> <c- n><c- n>message_length</c-></c-><c- p><c- p>,</c-></c->
  <c- b><c- b>bool</c-></c-> <c- n><c- n>is_complete</c-></c-><c- p><c- p>)</c-></c->
<c- p><c- p>{</c-></c->
  <c- k><c- k>auto</c-></c-> <c- n><c- n>method_string</c-></c-> <c- o><c- o>=</c-></c-> <c- p><c- p>[]</c-></c-> <c- p><c- p>(</c-></c-><c- k><c- k>auto</c-></c-> <c- n><c- n>method</c-></c-><c- p><c- p>)</c-></c-> <c- p><c- p>{</c-></c->
    <c- k><c- k>switch</c-></c-> <c- p><c- p>(</c-></c-><c- n><c- n>method</c-></c-><c- p><c- p>)</c-></c-> <c- p><c- p>{</c-></c->
    <c- k><c- k>case</c-></c-> <c- n><c- n>method</c-></c-><c- o><c- o>::</c-></c-><c- nl><c- nl>get</c-></c-><c- p><c- p>:</c-></c->
      <c- k><c- k>return</c-></c-> <c- s><c- s>"GET"</c-></c-><c- p><c- p>;</c-></c->
    <c- k><c- k>case</c-></c-> <c- n><c- n>method</c-></c-><c- o><c- o>::</c-></c-><c- nl><c- nl>post</c-></c-><c- p><c- p>:</c-></c->
      <c- k><c- k>return</c-></c-> <c- s><c- s>"POST"</c-></c-><c- p><c- p>;</c-></c->
    <c- p><c- p>}</c-></c->
  <c- p><c- p>};</c-></c->

  <c- k><c- k>auto</c-></c-> <c- n><c- n>http_metadata</c-></c-> <c- o><c- o>=</c-></c-> <c- k><c- k>dynamic_cast</c-></c-><c- o><c- o>&lt;</c-></c-><c- k><c- k>const</c-></c-> <c- n><c- n>http</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>metadata</c-></c-><c- o><c- o>&amp;></c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>metadata</c-></c-><c- p><c- p>);</c-></c->
  <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>ostringstream</c-></c-> <c- n><c- n>os</c-></c-><c- p><c- p>;</c-></c->
  <c- n><c- n>os</c-></c-> <c- o><c- o>&lt;&lt;</c-></c-> <c- n><c- n>method_string</c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>http_metadata</c-></c-><c- p><c- p>.</c-></c-><c- n><c- n>method</c-></c-><c- p><c- p>())</c-></c->
    <c- o><c- o>&lt;&lt;</c-></c-> <c- s><c- s>" "</c-></c-> <c- o><c- o>&lt;&lt;</c-></c-> <c- n><c- n>http_metadata</c-></c-><c- p><c- p>.</c-></c-><c- n><c- n>path</c-></c-><c- p><c- p>()</c-></c-> <c- o><c- o>&lt;&lt;</c-></c-> <c- s><c- s>" HTTP/1.1</c-></c-><c- se><c- se>\r\n</c-></c-><c- s><c- s>"</c-></c-><c- p><c- p>;</c-></c->

  <c- k><c- k>auto</c-></c-> <c- n><c- n>header_fields</c-></c-> <c- o><c- o>=</c-></c-> <c- n><c- n>http_metadata</c-></c-><c- p><c- p>.</c-></c-><c- n><c- n>header_fields</c-></c-><c- p><c- p>();</c-></c->
  <c- k><c- k>for</c-></c-> <c- p><c- p>(</c-></c-><c- k><c- k>auto</c-></c-><c- o><c- o>&amp;</c-></c-> <c- nl><c- nl>kv</c-></c-> <c- p><c- p>:</c-></c-> <c- n><c- n>header_fields</c-></c-><c- p><c- p>)</c-></c->
      <c- n><c- n>os</c-></c-> <c- o><c- o>&lt;&lt;</c-></c-> <c- n><c- n>kv</c-></c-><c- p><c- p>.</c-></c-><c- n><c- n>first</c-></c-> <c- o><c- o>&lt;&lt;</c-></c-> <c- s><c- s>": "</c-></c-> <c- o><c- o>&lt;&lt;</c-></c-> <c- n><c- n>kv</c-></c-><c- p><c- p>.</c-></c-><c- n><c- n>second</c-></c-> <c- o><c- o>&lt;&lt;</c-></c-> <c- s><c- s>"</c-></c-><c- se><c- se>\r\n</c-></c-><c- s><c- s>"</c-></c-><c- p><c- p>;</c-></c->
  <c- n><c- n>os</c-></c-> <c- o><c- o>&lt;&lt;</c-></c-> <c- s><c- s>"</c-></c-><c- se><c- se>\r\n</c-></c-><c- s><c- s>"</c-></c-><c- p><c- p>;</c-></c->

  <c- k><c- k>auto</c-></c-> <c- n><c- n>header</c-></c-> <c- o><c- o>=</c-></c-> <c- n><c- n>os</c-></c-><c- p><c- p>.</c-></c-><c- n><c- n>str</c-></c-><c- p><c- p>();</c-></c->
  <c- n><c- n>m_framer</c-></c-><c- p><c- p>.</c-></c-><c- n><c- n>write_output</c-></c-><c- p><c- p>(</c-></c->
    <c- k><c- k>reinterpret_cast</c-></c-><c- o><c- o>&lt;</c-></c-><c- k><c- k>const</c-></c-> <c- b><c- b>uint8_t</c-></c-> <c- o><c- o>*></c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>header</c-></c-><c- p><c- p>.</c-></c-><c- n><c- n>c_str</c-></c-><c- p><c- p>()),</c-></c-> <c- n><c- n>header</c-></c-><c- p><c- p>.</c-></c-><c- n><c- n>size</c-></c-><c- p><c- p>());</c-></c->
<c- p><c- p>}</c-></c->

<c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>lazy</c-></c-><c- o><c- o>&lt;</c-></c-><c- b><c- b>void</c-></c-><c- o><c- o>></c-></c-> <c- n><c- n>run</c-></c-><c- p><c- p>()</c-></c->
<c- p><c- p>{</c-></c->
  <c- n><c- n>net</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>parameters</c-></c-> <c- n><c- n>parameters</c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>net</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>parameters</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>tcp</c-></c-><c- p><c- p>());</c-></c->
  <c- n><c- n>parameters</c-></c-><c- p><c- p>.</c-></c-><c- n><c- n>set_application_protocols</c-></c-><c- p><c- p>({</c-></c->
    <c- n><c- n>net</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>protocol</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>security</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>options</c-></c-><c- p><c- p>(),</c-></c->
    <c- n><c- n>http</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>options</c-></c-><c- p><c- p>()</c-></c->
  <c- p><c- p>});</c-></c->
  <c- n><c- n>net</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>connection</c-></c-> <c- n><c- n>connection</c-></c-><c- p><c- p>(</c-></c->
    <c- n><c- n>net</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>endpoint</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>host</c-></c-><c- p><c- p>(</c-></c-><c- s><c- s>"www.apple.com"</c-></c-><c- p><c- p>,</c-></c-> <c- mi><c- mi>443</c-></c-><c- p><c- p>),</c-></c->
    <c- n><c- n>parameters</c-></c-><c- p><c- p>,</c-></c->
    <c- n><c- n>net</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>workqueue</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>main_queue</c-></c-><c- p><c- p>()</c-></c->
  <c- p><c- p>);</c-></c->
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  <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>cout</c-></c-> <c- o><c- o>&lt;&lt;</c-></c-> <c- s><c- s>"Sending request"</c-></c-> <c- o><c- o>&lt;&lt;</c-></c-> <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>endl</c-></c-><c- p><c- p>;</c-></c->
  <c- n><c- n>http</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>metadata</c-></c-> <c- n><c- n>http_metadata</c-></c-><c- p><c- p>;</c-></c->
  <c- n><c- n>http_metadata</c-></c-><c- p><c- p>.</c-></c-><c- n><c- n>set_method</c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>http</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>method</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>get</c-></c-><c- p><c- p>).</c-></c-><c- n><c- n>set_path</c-></c-><c- p><c- p>(</c-></c-><c- s><c- s>"/"</c-></c-><c- p><c- p>).</c-></c-><c- n><c- n>set_header_fields</c-></c-><c- p><c- p>({</c-></c->
    <c- p><c- p>{</c-></c-> <c- s><c- s>"Host"</c-></c-><c- p><c- p>,</c-></c-> <c- s><c- s>"www.apple.com"</c-></c-> <c- p><c- p>},</c-></c->
    <c- p><c- p>{</c-></c-> <c- s><c- s>"Connection"</c-></c-><c- p><c- p>,</c-></c-> <c- s><c- s>"Close"</c-></c-> <c- p><c- p>}</c-></c->
  <c- p><c- p>});</c-></c->
  <c- k><c- k>auto</c-></c-> <c- n><c- n>sendResult</c-></c-> <c- o><c- o>=</c-></c-> <c- n><c- n>co_await</c-></c-> <c- n><c- n>connection</c-></c-><c- p><c- p>.</c-></c-><c- n><c- n>send</c-></c-><c- p><c- p>({</c-></c-> <c- n><c- n>http_metadata</c-></c-> <c- p><c- p>});</c-></c->
  <c- k><c- k>if</c-></c-> <c- p><c- p>(</c-></c-><c- o><c- o>!</c-></c-><c- n><c- n>sendResult</c-></c-><c- p><c- p>)</c-></c-> <c- p><c- p>{</c-></c->
    <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>cerr</c-></c-> <c- o><c- o>&lt;&lt;</c-></c-> <c- s><c- s>"failed to send request"</c-></c-> <c- o><c- o>&lt;&lt;</c-></c-> <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>endl</c-></c-><c- p><c- p>;</c-></c->
    <c- n><c- n>co_return</c-></c-><c- p><c- p>;</c-></c->
  <c- p><c- p>}</c-></c->
  <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>cout</c-></c-> <c- o><c- o>&lt;&lt;</c-></c-> <c- s><c- s>"Sent request, waiting for response"</c-></c-> <c- o><c- o>&lt;&lt;</c-></c-> <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>endl</c-></c-><c- p><c- p>;</c-></c->
  <c- k><c- k>auto</c-></c-> <c- n><c- n>message</c-></c-> <c- o><c- o>=</c-></c-> <c- n><c- n>co_await</c-></c-> <c- n><c- n>connection</c-></c-><c- p><c- p>.</c-></c-><c- n><c- n>receive</c-></c-><c- p><c- p>();</c-></c->
  <c- k><c- k>if</c-></c-> <c- p><c- p>(</c-></c-><c- o><c- o>!</c-></c-><c- n><c- n>message</c-></c-><c- p><c- p>)</c-></c-> <c- p><c- p>{</c-></c->
    <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>cerr</c-></c-> <c- o><c- o>&lt;&lt;</c-></c-> <c- s><c- s>"failed to receive response"</c-></c-> <c- o><c- o>&lt;&lt;</c-></c-> <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>endl</c-></c-><c- p><c- p>;</c-></c->
    <c- n><c- n>co_return</c-></c-><c- p><c- p>;</c-></c->
  <c- p><c- p>}</c-></c->
  <c- k><c- k>auto</c-></c-> <c- n><c- n>received_metadata</c-></c-> <c- o><c- o>=</c-></c-> <c- n><c- n>message</c-></c-><c- o><c- o>-></c-></c-><c- n><c- n>metadata</c-></c-><c- o><c- o>&lt;</c-></c-><c- n><c- n>http</c-></c-><c- o><c- o>></c-></c-><c- p><c- p>();</c-></c->
  <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>cout</c-></c-> <c- o><c- o>&lt;&lt;</c-></c-> <c- s><c- s>"http response header:"</c-></c-> <c- o><c- o>&lt;&lt;</c-></c-> <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>endl</c-></c-><c- p><c- p>;</c-></c->
  <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>cout</c-></c-> <c- o><c- o>&lt;&lt;</c-></c-> <c- n><c- n>received_metadata</c-></c-><c- p><c- p>.</c-></c-><c- n><c- n>response_header</c-></c-><c- p><c- p>()</c-></c-> <c- o><c- o>&lt;&lt;</c-></c-> <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>endl</c-></c-><c- p><c- p>;</c-></c->
  <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>cout</c-></c-> <c- o><c- o>&lt;&lt;</c-></c-> <c- s><c- s>"http response body:"</c-></c-> <c- o><c- o>&lt;&lt;</c-></c-> <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>endl</c-></c-><c- p><c- p>;</c-></c->
  <c- n><c- n>message</c-></c-><c- o><c- o>-></c-></c-><c- n><c- n>data</c-></c-><c- p><c- p>().</c-></c-><c- n><c- n>get</c-></c-><c- p><c- p>([](</c-></c-><c- k><c- k>const</c-></c-> <c- b><c- b>uint8_t</c-></c-> <c- o><c- o>*</c-></c-><c- n><c- n>bytes</c-></c-><c- p><c- p>,</c-></c-> <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- b><c- b>size_t</c-></c-> <c- n><c- n>size</c-></c-><c- p><c- p>)</c-></c-> <c- p><c- p>{</c-></c->
    <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>cout</c-></c-> <c- o><c- o>&lt;&lt;</c-></c->
      <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>string</c-></c-><c- p><c- p>(</c-></c-><c- k><c- k>reinterpret_cast</c-></c-><c- o><c- o>&lt;</c-></c-><c- k><c- k>const</c-></c-> <c- b><c- b>char</c-></c-> <c- o><c- o>*></c-></c-><c- p><c- p>(</c-></c-><c- n><c- n>bytes</c-></c-><c- p><c- p>),</c-></c-> <c- n><c- n>size</c-></c-><c- p><c- p>)</c-></c->
      <c- o><c- o>&lt;&lt;</c-></c-> <c- n><c- n>std</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>endl</c-></c-><c- p><c- p>;</c-></c->
  <c- p><c- p>});</c-></c->
  <c- n><c- n>co_return</c-></c-><c- p><c- p>;</c-></c->
<c- p><c- p>}</c-></c->

<c- b><c- b>int</c-></c-> <c- n><c- n>main</c-></c-><c- p><c- p>(</c-></c-><c- b><c- b>int</c-></c-><c- p><c- p>,</c-></c-> <c- b><c- b>char</c-></c-><c- o><c- o>**</c-></c-><c- p><c- p>)</c-></c->
<c- p><c- p>{</c-></c->
  <c- k><c- k>auto</c-></c-> <c- n><c- n>lazy</c-></c-> <c- o><c- o>=</c-></c-> <c- n><c- n>run</c-></c-><c- p><c- p>();</c-></c->
  <c- n><c- n>net</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>workqueue</c-></c-><c- o><c- o>::</c-></c-><c- n><c- n>main</c-></c-><c- p><c- p>();</c-></c->
  <c- k><c- k>return</c-></c-> <c- mi><c- mi>0</c-></c-><c- p><c- p>;</c-></c->
<c- p><c- p>}</c-></c->
</code></pre>
   <h2 class="heading settled" data-level="7" id="notes"><span class="secno">7. </span><span class="content">Notes</span><a class="self-link" href="#notes"></a></h2>
   <p>Identities consisting of certificate chains and private keys are commonly used, but there are also things like hardware keys which sign data upon request but never allow access to the private key.  This will need to be developed further to support such devices.</p>
   <p>TLS version and cipher suite are intentionally not exposed because they would not allow crypto agility without breaking ABI.  Users who need such control will have to implement their own TLS on top of TCP or DTLS on top of UDP.</p>
   <p>Relatedly, the allowance for custom transport and application protocols has not yet been included but can.  It is tricky to do so without mandating interitance from STL types, which would be undesirable.</p>
   <p>The storage mechanism on <code class="highlight"><c- n>framer</c-><c- o>::</c-><c- n>metadata</c-></code> is not optimal because it requires a string key to set or access its values.  Don’t let that be a distraction from the design of <code class="highlight"><c- n>framer</c-></code> allowing implementation of custom protocols.</p>
   <h2 class="heading settled" data-level="8" id="implementability"><span class="secno">8. </span><span class="content">Implementability</span><a class="self-link" href="#implementability"></a></h2>
   <p>We implemented the suggested API using Apple’s <a href="https://developer.apple.com/documentation/network">Network.framework</a> API, available on iOS and macOS. This implementation currently stands at 2350 lines of code (without counting <code class="highlight"><c- n>std</c-><c- o>::</c-><c- n>expected</c-></code>). All examples function as described.</p>
   <p>Undue implementation burden was a severe concern in the Committee, particularly when it comes to the cryptography used in modern secure networking protocols. Our implementation needs little to no experience with cryptography. Indeed, the implementation simply needs to wrap existing APIs. Our experience makes us confident that modern operating systems and userspace libraries are more than adequate to implement this suggested API fully.</p>
   <p>Much of this can be implemented on top of the Berkeley Sockets API. It’s merely a different shape for the API with the important addition of metadata, which provides a mechanism to configure protocol properties in a way that can be elegantly extended to protocols with security in the transport layer, such as QUIC.</p>
   <p>The <code class="highlight"><c- n>path_monitor</c-></code> class requires OS support that many operating systems already have internally.</p>
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  <h2 class="no-num no-ref heading settled" id="references"><span class="content">References</span><a class="self-link" href="#references"></a></h2>
  <h3 class="no-num no-ref heading settled" id="informative"><span class="content">Informative References</span><a class="self-link" href="#informative"></a></h3>
  <dl>
   <dt id="biblio-n4771">[N4771]
   <dd>Jonathan Wakely. <a href="https://wg21.link/n4771">Working Draft, C++ Extensions for Networking</a>. 8 October 2018. URL: <a href="https://wg21.link/n4771">https://wg21.link/n4771</a>
   <dt id="biblio-p0323r7">[P0323R7]
   <dd>Vicente Botet, JF Bastien. <a href="https://wg21.link/p0323r7">std::expected</a>. 22 June 2018. URL: <a href="https://wg21.link/p0323r7">https://wg21.link/p0323r7</a>
   <dt id="biblio-p1056r1">[P1056R1]
   <dd>Lewis Baker, Gor Nishanov. <a href="https://wg21.link/p1056r1">Add lazy coroutine (coroutine task) type</a>. 7 October 2018. URL: <a href="https://wg21.link/p1056r1">https://wg21.link/p1056r1</a>
   <dt id="biblio-p1860r0">[p1860R0]
   <dd>JF Bastien, Alex Christensen. <a href="https://wg21.link/p1860r0">C++ Networking Must Be Secure By Default</a>. 7 October 2019. URL: <a href="https://wg21.link/p1860r0">https://wg21.link/p1860r0</a>
   <dt id="biblio-p1861r0">[P1861R0]
   <dd>JF Bastien, Alex Christensen. <a href="https://wg21.link/p1861r0">Secure Connections in Networking TS</a>. 7 October 2019. URL: <a href="https://wg21.link/p1861r0">https://wg21.link/p1861r0</a>
  </dl>