126 lines
No EOL
65 KiB
HTML
126 lines
No EOL
65 KiB
HTML
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
|
|
<html><head><meta http-equiv="content-type" content="text/html; charset=utf-8"/><meta name="viewport" content="width=device-width, initial-scale=0.8"/><title>15.3.1 TCP</title><link rel="stylesheet" type="text/css" href="../scribble.css" title="default"/><link rel="stylesheet" type="text/css" href="extras.css" title="default"/><link rel="stylesheet" type="text/css" href="../racket.css" title="default"/><link rel="stylesheet" type="text/css" href="../manual-style.css" title="default"/><link rel="stylesheet" type="text/css" href="../manual-racket.css" title="default"/><link rel="stylesheet" type="text/css" href="../manual-racket.css" title="default"/><link rel="stylesheet" type="text/css" href="../doc-site.css" title="default"/><script type="text/javascript" src="../scribble-common.js"></script><script type="text/javascript" src="../manual-racket.js"></script><script type="text/javascript" src="../manual-racket.js"></script><script type="text/javascript" src="../doc-site.js"></script><script type="text/javascript" src="../local-redirect/local-redirect.js"></script><script type="text/javascript" src="../local-redirect/local-user-redirect.js"></script><!--[if IE 6]><style type="text/css">.SIEHidden { overflow: hidden; }</style><![endif]--></head><body id="doc-racket-lang-org"><div class="tocset"><div class="tocview"><div class="tocviewlist tocviewlisttopspace"><div class="tocviewtitle"><table cellspacing="0" cellpadding="0"><tr><td style="width: 1em;"><a href="javascript:void(0);" title="Expand/Collapse" class="tocviewtoggle" onclick="TocviewToggle(this,"tocview_0");">►</a></td><td></td><td><a href="index.html" class="tocviewlink" data-pltdoc="x">The Racket Reference</a></td></tr></table></div><div class="tocviewsublisttop" style="display: none;" id="tocview_0"><table cellspacing="0" cellpadding="0"><tr><td align="right">1 </td><td><a href="model.html" class="tocviewlink" data-pltdoc="x">Language Model</a></td></tr><tr><td align="right">2 </td><td><a href="notation.html" class="tocviewlink" data-pltdoc="x">Notation for Documentation</a></td></tr><tr><td align="right">3 </td><td><a href="syntax.html" class="tocviewlink" data-pltdoc="x">Syntactic Forms</a></td></tr><tr><td align="right">4 </td><td><a href="data.html" class="tocviewlink" data-pltdoc="x">Datatypes</a></td></tr><tr><td align="right">5 </td><td><a href="structures.html" class="tocviewlink" data-pltdoc="x">Structures</a></td></tr><tr><td align="right">6 </td><td><a href="mzlib_class.html" class="tocviewlink" data-pltdoc="x">Classes and Objects</a></td></tr><tr><td align="right">7 </td><td><a href="mzlib_unit.html" class="tocviewlink" data-pltdoc="x">Units</a></td></tr><tr><td align="right">8 </td><td><a href="contracts.html" class="tocviewlink" data-pltdoc="x">Contracts</a></td></tr><tr><td align="right">9 </td><td><a href="match.html" class="tocviewlink" data-pltdoc="x">Pattern Matching</a></td></tr><tr><td align="right">10 </td><td><a href="control.html" class="tocviewlink" data-pltdoc="x">Control Flow</a></td></tr><tr><td align="right">11 </td><td><a href="concurrency.html" class="tocviewlink" data-pltdoc="x">Concurrency and Parallelism</a></td></tr><tr><td align="right">12 </td><td><a href="Macros.html" class="tocviewlink" data-pltdoc="x">Macros</a></td></tr><tr><td align="right">13 </td><td><a href="input-and-output.html" class="tocviewlink" data-pltdoc="x">Input and Output</a></td></tr><tr><td align="right">14 </td><td><a href="security.html" class="tocviewlink" data-pltdoc="x">Reflection and Security</a></td></tr><tr><td align="right">15 </td><td><a href="os.html" class="tocviewselflink" data-pltdoc="x">Operating System</a></td></tr><tr><td align="right">16 </td><td><a href="memory.html" class="tocviewlink" data-pltdoc="x">Memory Management</a></td></tr><tr><td align="right">17 </td><td><a href="unsafe.html" class="tocviewlink" data-pltdoc="x">Unsafe Operations</a></td></tr><tr><td align="right">18 </td><td><a href="running.html" class="tocviewlink" data-pltdoc="x">Running Racket</a></td></tr><tr><td align="right"></td><td><a href="doc-bibliography.html" class="tocviewlink" data-pltdoc="x">Bibliography</a></td></tr><tr><td align="right"></td><td><a href="doc-index.html" class="tocviewlink" data-pltdoc="x">Index</a></td></tr></table></div></div><div class="tocviewlist"><table cellspacing="0" cellpadding="0"><tr><td style="width: 1em;"><a href="javascript:void(0);" title="Expand/Collapse" class="tocviewtoggle" onclick="TocviewToggle(this,"tocview_1");">►</a></td><td>15 </td><td><a href="os.html" class="tocviewlink" data-pltdoc="x">Operating System</a></td></tr></table><div class="tocviewsublist" style="display: none;" id="tocview_1"><table cellspacing="0" cellpadding="0"><tr><td align="right">15.1 </td><td><a href="pathutils.html" class="tocviewlink" data-pltdoc="x">Paths</a></td></tr><tr><td align="right">15.2 </td><td><a href="Filesystem.html" class="tocviewlink" data-pltdoc="x">Filesystem</a></td></tr><tr><td align="right">15.3 </td><td><a href="networking.html" class="tocviewselflink" data-pltdoc="x">Networking</a></td></tr><tr><td align="right">15.4 </td><td><a href="subprocess.html" class="tocviewlink" data-pltdoc="x">Processes</a></td></tr><tr><td align="right">15.5 </td><td><a href="logging.html" class="tocviewlink" data-pltdoc="x">Logging</a></td></tr><tr><td align="right">15.6 </td><td><a href="time.html" class="tocviewlink" data-pltdoc="x">Time</a></td></tr><tr><td align="right">15.7 </td><td><a href="envvars.html" class="tocviewlink" data-pltdoc="x">Environment Variables</a></td></tr><tr><td align="right">15.8 </td><td><a href="runtime.html" class="tocviewlink" data-pltdoc="x">Environment and Runtime Information</a></td></tr><tr><td align="right">15.9 </td><td><a href="Command-Line_Parsing.html" class="tocviewlink" data-pltdoc="x">Command-<wbr></wbr>Line Parsing</a></td></tr><tr><td align="right">15.10 </td><td><a href="os-lib.html" class="tocviewlink" data-pltdoc="x">Additional Operating System Functions</a></td></tr></table></div></div><div class="tocviewlist"><table cellspacing="0" cellpadding="0"><tr><td style="width: 1em;"><a href="javascript:void(0);" title="Expand/Collapse" class="tocviewtoggle" onclick="TocviewToggle(this,"tocview_2");">▼</a></td><td>15.3 </td><td><a href="networking.html" class="tocviewlink" data-pltdoc="x">Networking</a></td></tr></table><div class="tocviewsublistbottom" style="display: block;" id="tocview_2"><table cellspacing="0" cellpadding="0"><tr><td align="right">15.3.1 </td><td><a href="tcp.html" class="tocviewselflink" data-pltdoc="x">TCP</a></td></tr><tr><td align="right">15.3.2 </td><td><a href="udp.html" class="tocviewlink" data-pltdoc="x">UDP</a></td></tr></table></div></div></div><div class="tocsub"><div class="tocsubtitle">On this page:</div><table class="tocsublist" cellspacing="0"><tr><td><a href="tcp.html#%28def._%28%28lib._racket%2Ftcp..rkt%29._tcp-listen%29%29" class="tocsublink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">tcp-<wbr></wbr>listen</span></span></a></td></tr><tr><td><a href="tcp.html#%28def._%28%28lib._racket%2Ftcp..rkt%29._tcp-connect%29%29" class="tocsublink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">tcp-<wbr></wbr>connect</span></span></a></td></tr><tr><td><a href="tcp.html#%28def._%28%28lib._racket%2Ftcp..rkt%29._tcp-connect%2Fenable-break%29%29" class="tocsublink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">tcp-<wbr></wbr>connect/<span class="mywbr"> </span>enable-<wbr></wbr>break</span></span></a></td></tr><tr><td><a href="tcp.html#%28def._%28%28lib._racket%2Ftcp..rkt%29._tcp-accept%29%29" class="tocsublink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">tcp-<wbr></wbr>accept</span></span></a></td></tr><tr><td><a href="tcp.html#%28def._%28%28lib._racket%2Ftcp..rkt%29._tcp-accept%2Fenable-break%29%29" class="tocsublink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">tcp-<wbr></wbr>accept/<span class="mywbr"> </span>enable-<wbr></wbr>break</span></span></a></td></tr><tr><td><a href="tcp.html#%28def._%28%28lib._racket%2Ftcp..rkt%29._tcp-accept-ready~3f%29%29" class="tocsublink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">tcp-<wbr></wbr>accept-<wbr></wbr>ready?</span></span></a></td></tr><tr><td><a href="tcp.html#%28def._%28%28lib._racket%2Ftcp..rkt%29._tcp-close%29%29" class="tocsublink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">tcp-<wbr></wbr>close</span></span></a></td></tr><tr><td><a href="tcp.html#%28def._%28%28lib._racket%2Ftcp..rkt%29._tcp-listener~3f%29%29" class="tocsublink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">tcp-<wbr></wbr>listener?</span></span></a></td></tr><tr><td><a href="tcp.html#%28def._%28%28lib._racket%2Ftcp..rkt%29._tcp-accept-evt%29%29" class="tocsublink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">tcp-<wbr></wbr>accept-<wbr></wbr>evt</span></span></a></td></tr><tr><td><a href="tcp.html#%28def._%28%28lib._racket%2Ftcp..rkt%29._tcp-abandon-port%29%29" class="tocsublink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">tcp-<wbr></wbr>abandon-<wbr></wbr>port</span></span></a></td></tr><tr><td><a href="tcp.html#%28def._%28%28lib._racket%2Ftcp..rkt%29._tcp-addresses%29%29" class="tocsublink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">tcp-<wbr></wbr>addresses</span></span></a></td></tr><tr><td><a href="tcp.html#%28def._%28%28lib._racket%2Ftcp..rkt%29._tcp-port~3f%29%29" class="tocsublink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">tcp-<wbr></wbr>port?</span></span></a></td></tr><tr><td><a href="tcp.html#%28def._%28%28lib._racket%2Ftcp..rkt%29._port-number~3f%29%29" class="tocsublink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">port-<wbr></wbr>number?</span></span></a></td></tr><tr><td><a href="tcp.html#%28def._%28%28lib._racket%2Ftcp..rkt%29._listen-port-number~3f%29%29" class="tocsublink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">listen-<wbr></wbr>port-<wbr></wbr>number?</span></span></a></td></tr></table></div></div><div class="maincolumn"><div class="main"><div class="navsettop"><span class="navleft"><form class="searchform"><input class="searchbox" id="searchbox" type="text" tabindex="1" placeholder="...search manuals..." title="Enter a search string to search the manuals" onkeypress="return DoSearchKey(event, this, "8.6", "../");"/></form> <a href="https://docs.racket-lang.org/index.html" title="up to the documentation top" data-pltdoc="x" onclick="return GotoPLTRoot("8.6");">top</a><span class="tocsettoggle"> <a href="javascript:void(0);" title="show/hide table of contents" onclick="TocsetToggle();">contents</a></span></span><span class="navright"> <a href="networking.html" title="backward to "15.3 Networking"" data-pltdoc="x">← prev</a> <a href="networking.html" title="up to "15.3 Networking"" data-pltdoc="x">up</a> <a href="udp.html" title="forward to "15.3.2 UDP"" data-pltdoc="x">next →</a></span> </div><h5 x-source-module="(lib "scribblings/reference/reference.scrbl")" x-source-pkg="racket-doc" x-part-tag=""tcp"">15.3.1<tt> </tt><a name="(part._tcp)"></a><a name="(mod-path._racket/tcp)"></a>TCP</h5><p><div class="SIntrapara"><table cellspacing="0" cellpadding="0" class="defmodule"><tr><td align="left"><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="require.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._require%29%29" class="RktStxLink" data-pltdoc="x">require</a></span><span class="stt"> </span><a href="tcp.html" class="RktModLink" data-pltdoc="x"><span class="RktSym">racket/tcp</span></a><span class="RktPn">)</span></td><td align="right"><span class="RpackageSpec"><span class="Smaller"> package:</span> <a href="https://pkgs.racket-lang.org/package/base" title="Install this package using `raco pkg install base`"><span class="stt">base</span></a></span></td></tr></table></div><div class="SIntrapara">The bindings documented in this section are provided by the <a href="tcp.html" class="RktModLink" data-pltdoc="x"><span class="RktSym">racket/tcp</span></a> and <a href="index.html" class="RktModLink" data-pltdoc="x"><span class="RktSym">racket</span></a> libraries, but not <a href="index.html" class="RktModLink" data-pltdoc="x"><span class="RktSym">racket/base</span></a>.</div></p><p>For information about TCP in general, see <span style="font-style: italic">TCP/IP Illustrated,
|
|
Volume 1</span> by W. Richard Stevens.</p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>procedure</p></div></div><table cellspacing="0" cellpadding="0" class="prototype RForeground"><tr><td valign="top"><span class="RktPn">(</span><a name="(def._((lib._racket/tcp..rkt)._tcp-listen))"></a><span title="Provided from: racket/tcp, racket | Package: base"><span class="RktSym"><a href="tcp.html#%28def._%28%28lib._racket%2Ftcp..rkt%29._tcp-listen%29%29" class="RktValDef RktValLink" data-pltdoc="x">tcp-listen</a></span></span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="RktVar">port-no</span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="hspace"> </span></td></tr><tr><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="hspace"> </span><span class="RktOpt">[</span></td><td valign="top"><span class="RktVar">max-allow-wait</span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="hspace"> </span></td></tr><tr><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="RktVar">reuse?</span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="hspace"> </span></td></tr><tr><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="RktVar">hostname</span><span class="RktOpt">]</span><span class="RktPn">)</span></td><td valign="top"><span class="hspace"> </span></td><td valign="top">→</td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="RktSym"><a href="tcp.html#%28def._%28%28lib._racket%2Ftcp..rkt%29._tcp-listener~3f%29%29" class="RktValLink" data-pltdoc="x">tcp-listener?</a></span></td></tr></table></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">port-no</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="tcp.html#%28def._%28%28lib._racket%2Ftcp..rkt%29._listen-port-number~3f%29%29" class="RktValLink" data-pltdoc="x">listen-port-number?</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">max-allow-wait</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="number-types.html#%28def._%28%28quote._~23~25kernel%29._exact-nonnegative-integer~3f%29%29" class="RktValLink" data-pltdoc="x">exact-nonnegative-integer?</a></span><span class="hspace"> </span>=<span class="hspace"> </span><span class="RktVal">4</span></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">reuse?</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._any%2Fc%29%29" class="RktValLink" data-pltdoc="x">any/c</a></span><span class="hspace"> </span>=<span class="hspace"> </span><span class="RktVal">#f</span></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">hostname</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fbase..rkt%29._or%2Fc%29%29" class="RktValLink" data-pltdoc="x">or/c</a></span><span class="hspace"> </span><span class="RktSym"><a href="strings.html#%28def._%28%28quote._~23~25kernel%29._string~3f%29%29" class="RktValLink" data-pltdoc="x">string?</a></span><span class="hspace"> </span><span class="RktVal">#f</span><span class="RktPn">)</span><span class="hspace"> </span>=<span class="hspace"> </span><span class="RktVal">#f</span></td></tr></table></blockquote></div><div class="SIntrapara">Creates a “listening” server on the local machine at the port number
|
|
specified by <span class="RktVar">port-no</span>. If <span class="RktVar">port-no</span> is 0 the socket binds
|
|
to an ephemeral port, which can be determined by calling
|
|
<span class="RktSym"><a href="tcp.html#%28def._%28%28lib._racket%2Ftcp..rkt%29._tcp-addresses%29%29" class="RktValLink" data-pltdoc="x">tcp-addresses</a></span>. The <span class="RktVar">max-allow-wait</span> argument
|
|
determines the maximum number of client connections that can be
|
|
waiting for acceptance. (When <span class="RktVar">max-allow-wait</span> clients are
|
|
waiting acceptance, no new client connections can be made.)</div></p><p>If the <span class="RktVar">reuse?</span> argument is true, then <span class="RktSym"><a href="tcp.html#%28def._%28%28lib._racket%2Ftcp..rkt%29._tcp-listen%29%29" class="RktValLink" data-pltdoc="x">tcp-listen</a></span> will
|
|
create a listener even if the port is involved in a <span class="stt">TIME_WAIT</span>
|
|
state. Such a use of <span class="RktVar">reuse?</span> defeats certain guarantees of the
|
|
TCP protocol; see Stevens’s book for details. Furthermore, on many
|
|
modern platforms, a true value for <span class="RktVar">reuse?</span> overrides
|
|
<span class="stt">TIME_WAIT</span> only if the listener was previously created with a true
|
|
value for <span class="RktVar">reuse?</span>.</p><p>If <span class="RktVar">hostname</span> is <span class="RktVal">#f</span> (the default), then the listener
|
|
accepts connections to all of the listening machine’s addresses.
|
|
Otherwise, the listener accepts connections only at the interface(s)
|
|
associated with the given hostname. For example, providing
|
|
<span class="RktVal">"127.0.0.1"</span> as <span class="RktVar">hostname</span> creates a listener that
|
|
accepts only connections to <span class="RktVal">"127.0.0.1"</span> (the loopback
|
|
interface) from the local machine.</p><p>(Racket implements a listener with multiple sockets, if necessary, to
|
|
accommodate multiple addresses with different protocol families. On
|
|
Linux, if <span class="RktVar">hostname</span> maps to both IPv4 and IPv6 addresses, then
|
|
the behavior depends on whether IPv6 is supported and IPv6 sockets can
|
|
be configured to listen to only IPv6 connections: if IPv6 is not
|
|
supported or IPv6 sockets are not configurable, then the IPv6
|
|
addresses are ignored; otherwise, each IPv6 listener accepts only IPv6
|
|
connections.)</p><p>The return value of <span class="RktSym"><a href="tcp.html#%28def._%28%28lib._racket%2Ftcp..rkt%29._tcp-listen%29%29" class="RktValLink" data-pltdoc="x">tcp-listen</a></span> is a <a name="(tech._tcp._listener)"></a><span style="font-style: italic">TCP
|
|
listener</span>. This value can be used in future calls to
|
|
<span class="RktSym"><a href="tcp.html#%28def._%28%28lib._racket%2Ftcp..rkt%29._tcp-accept%29%29" class="RktValLink" data-pltdoc="x">tcp-accept</a></span>, <span class="RktSym"><a href="tcp.html#%28def._%28%28lib._racket%2Ftcp..rkt%29._tcp-accept-ready~3f%29%29" class="RktValLink" data-pltdoc="x">tcp-accept-ready?</a></span>, and
|
|
<span class="RktSym"><a href="tcp.html#%28def._%28%28lib._racket%2Ftcp..rkt%29._tcp-close%29%29" class="RktValLink" data-pltdoc="x">tcp-close</a></span>. Each new TCP listener value is placed into the
|
|
management of the current custodian (see <a href="custodians.html" data-pltdoc="x">Custodians</a>).</p><p>If the server cannot be started by <span class="RktSym"><a href="tcp.html#%28def._%28%28lib._racket%2Ftcp..rkt%29._tcp-listen%29%29" class="RktValLink" data-pltdoc="x">tcp-listen</a></span>, the
|
|
<span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._exn~3afail~3anetwork%29%29" class="RktValLink" data-pltdoc="x">exn:fail:network</a></span> exception is raised.</p><p>A TCP listener can be used as a <a href="sync.html#%28tech._synchronizable._event%29" class="techoutside" data-pltdoc="x"><span class="techinside">synchronizable event</span></a> (see <a href="sync.html" data-pltdoc="x">Events</a>).
|
|
A TCP listener is <a href="sync.html#%28tech._ready._for._synchronization%29" class="techoutside" data-pltdoc="x"><span class="techinside">ready for synchronization</span></a> when
|
|
<span class="RktSym"><a href="tcp.html#%28def._%28%28lib._racket%2Ftcp..rkt%29._tcp-accept%29%29" class="RktValLink" data-pltdoc="x">tcp-accept</a></span> would not block; the <a href="sync.html#%28tech._synchronization._result%29" class="techoutside" data-pltdoc="x"><span class="techinside">synchronization result</span></a> of a TCP listener is the TCP listener itself.</p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>procedure</p></div></div><table cellspacing="0" cellpadding="0" class="prototype RForeground"><tr><td valign="top"><span class="RktPn">(</span><a name="(def._((lib._racket/tcp..rkt)._tcp-connect))"></a><span title="Provided from: racket/tcp, racket | Package: base"><span class="RktSym"><a href="tcp.html#%28def._%28%28lib._racket%2Ftcp..rkt%29._tcp-connect%29%29" class="RktValDef RktValLink" data-pltdoc="x">tcp-connect</a></span></span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="RktVar">hostname</span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="hspace"> </span></td></tr><tr><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="RktVar">port-no</span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="hspace"> </span></td></tr><tr><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="hspace"> </span><span class="RktOpt">[</span></td><td valign="top"><span class="RktVar">local-hostname</span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="hspace"> </span></td></tr><tr><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="RktVar">local-port-no</span><span class="RktOpt">]</span><span class="RktPn">)</span></td><td valign="top"><span class="hspace"> </span></td><td valign="top">→</td><td valign="top"><span class="hspace"> </span></td><td valign="top"><table cellspacing="0" cellpadding="0"><tr><td><span class="RktSym"><a href="port-ops.html#%28def._%28%28quote._~23~25kernel%29._input-port~3f%29%29" class="RktValLink" data-pltdoc="x">input-port?</a></span></td><td><span class="hspace"> </span></td><td><span class="RktSym"><a href="port-ops.html#%28def._%28%28quote._~23~25kernel%29._output-port~3f%29%29" class="RktValLink" data-pltdoc="x">output-port?</a></span></td></tr></table></td></tr></table></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">hostname</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="strings.html#%28def._%28%28quote._~23~25kernel%29._string~3f%29%29" class="RktValLink" data-pltdoc="x">string?</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">port-no</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="tcp.html#%28def._%28%28lib._racket%2Ftcp..rkt%29._port-number~3f%29%29" class="RktValLink" data-pltdoc="x">port-number?</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">local-hostname</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fbase..rkt%29._or%2Fc%29%29" class="RktValLink" data-pltdoc="x">or/c</a></span><span class="hspace"> </span><span class="RktSym"><a href="strings.html#%28def._%28%28quote._~23~25kernel%29._string~3f%29%29" class="RktValLink" data-pltdoc="x">string?</a></span><span class="hspace"> </span><span class="RktVal">#f</span><span class="RktPn">)</span><span class="hspace"> </span>=<span class="hspace"> </span><span class="RktVal">#f</span></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">local-port-no</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fbase..rkt%29._or%2Fc%29%29" class="RktValLink" data-pltdoc="x">or/c</a></span><span class="hspace"> </span><span class="RktSym"><a href="tcp.html#%28def._%28%28lib._racket%2Ftcp..rkt%29._port-number~3f%29%29" class="RktValLink" data-pltdoc="x">port-number?</a></span><span class="hspace"> </span><span class="RktVal">#f</span><span class="RktPn">)</span><span class="hspace"> </span>=<span class="hspace"> </span><span class="RktVal">#f</span></td></tr></table></blockquote></div><div class="SIntrapara">Attempts to connect as a client to a listening server. The
|
|
<span class="RktVar">hostname</span> argument is the server host’s Internet address name,
|
|
and <span class="RktVar">port-no</span> is the port number where the server is listening.</div></p><p>(If <span class="RktVar">hostname</span> is associated with multiple addresses, they are
|
|
tried one at a time until a connection succeeds. The name
|
|
<span class="RktVal">"localhost"</span> generally specifies the local machine.)</p><p>The optional <span class="RktVar">local-hostname</span> and <span class="RktVar">local-port-no</span>
|
|
specify the client’s address and port. If both are <span class="RktVal">#f</span> (the
|
|
default), the client’s address and port are selected automatically. If
|
|
<span class="RktVar">local-hostname</span> is not <span class="RktVal">#f</span>, then
|
|
<span class="RktVar">local-port-no</span> must be non-<span class="RktVal">#f</span>. If
|
|
<span class="RktVar">local-port-no</span> is non-<span class="RktVal">#f</span> and <span class="RktVar">local-hostname</span>
|
|
is <span class="RktVal">#f</span>, then the given port is used but the address is
|
|
selected automatically.</p><p>Two values are returned by <span class="RktSym"><a href="tcp.html#%28def._%28%28lib._racket%2Ftcp..rkt%29._tcp-connect%29%29" class="RktValLink" data-pltdoc="x">tcp-connect</a></span>: an input port and an
|
|
output port. Data can be received from the server through the input
|
|
port and sent to the server through the output port. If the server is
|
|
a Racket program, it can obtain ports to communicate to the
|
|
client with <span class="RktSym"><a href="tcp.html#%28def._%28%28lib._racket%2Ftcp..rkt%29._tcp-accept%29%29" class="RktValLink" data-pltdoc="x">tcp-accept</a></span>. These ports are placed into the
|
|
management of the current custodian (see <a href="custodians.html" data-pltdoc="x">Custodians</a>).</p><p>Initially, the returned input port is block-buffered, and the returned
|
|
output port is block-buffered. Change the buffer mode using
|
|
<span class="RktSym"><a href="port-buffers.html#%28def._%28%28quote._~23~25kernel%29._file-stream-buffer-mode%29%29" class="RktValLink" data-pltdoc="x">file-stream-buffer-mode</a></span>.</p><p>Both of the returned ports must be closed to terminate the TCP
|
|
connection. When both ports are still open, closing the output port
|
|
with <span class="RktSym"><a href="port-ops.html#%28def._%28%28quote._~23~25kernel%29._close-output-port%29%29" class="RktValLink" data-pltdoc="x">close-output-port</a></span> sends a TCP close to the server (which
|
|
is seen as an end-of-file if the server reads the connection through a
|
|
port). In contrast, <span class="RktSym"><a href="tcp.html#%28def._%28%28lib._racket%2Ftcp..rkt%29._tcp-abandon-port%29%29" class="RktValLink" data-pltdoc="x">tcp-abandon-port</a></span> (see below) closes the
|
|
output port, but does not send a TCP close until the input port is
|
|
also closed.</p><p>Note that the TCP protocol does not support a state where one end is
|
|
willing to send but not read, nor does it include an automatic message
|
|
when one end of a connection is fully closed. Instead, the other end
|
|
of a connection discovers that one end is fully closed only as a
|
|
response to sending data; in particular, some number of writes on the
|
|
still-open end may appear to succeed, though writes will eventually
|
|
produce an error.</p><p>If a connection cannot be established by <span class="RktSym"><a href="tcp.html#%28def._%28%28lib._racket%2Ftcp..rkt%29._tcp-connect%29%29" class="RktValLink" data-pltdoc="x">tcp-connect</a></span>, the
|
|
<span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._exn~3afail~3anetwork%29%29" class="RktValLink" data-pltdoc="x">exn:fail:network</a></span> exception is raised.</p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>procedure</p></div></div><table cellspacing="0" cellpadding="0" class="prototype RForeground"><tr><td valign="top"><span class="RktPn">(</span><a name="(def._((lib._racket/tcp..rkt)._tcp-connect/enable-break))"></a><span title="Provided from: racket/tcp, racket | Package: base"><span class="RktSym"><a href="tcp.html#%28def._%28%28lib._racket%2Ftcp..rkt%29._tcp-connect%2Fenable-break%29%29" class="RktValDef RktValLink" data-pltdoc="x">tcp-connect/enable-break</a></span></span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="RktVar">hostname</span></td><td valign="top"><span class="hspace"> </span></td></tr><tr><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="RktVar">port-no</span></td><td valign="top"><span class="hspace"> </span></td></tr><tr><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="hspace"> </span><span class="RktOpt">[</span></td><td valign="top"><span class="RktVar">local-hostname</span><span class="RktOpt">]</span></td><td valign="top"><span class="hspace"> </span></td></tr><tr><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="RktVar">local-port-no</span><span class="RktPn">)</span></td><td valign="top"><span class="hspace"> </span></td></tr></table></blockquote></td></tr><tr><td><table cellspacing="0" cellpadding="0" class="prototype"><tr><td valign="top"><span class="hspace"> </span></td><td valign="top">→</td><td valign="top"><span class="hspace"> </span></td><td valign="top"><table cellspacing="0" cellpadding="0"><tr><td><span class="RktSym"><a href="port-ops.html#%28def._%28%28quote._~23~25kernel%29._input-port~3f%29%29" class="RktValLink" data-pltdoc="x">input-port?</a></span></td><td><span class="hspace"> </span></td><td><span class="RktSym"><a href="port-ops.html#%28def._%28%28quote._~23~25kernel%29._output-port~3f%29%29" class="RktValLink" data-pltdoc="x">output-port?</a></span></td></tr></table></td></tr></table></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">hostname</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="strings.html#%28def._%28%28quote._~23~25kernel%29._string~3f%29%29" class="RktValLink" data-pltdoc="x">string?</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">port-no</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="tcp.html#%28def._%28%28lib._racket%2Ftcp..rkt%29._port-number~3f%29%29" class="RktValLink" data-pltdoc="x">port-number?</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">local-hostname</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fbase..rkt%29._or%2Fc%29%29" class="RktValLink" data-pltdoc="x">or/c</a></span><span class="hspace"> </span><span class="RktSym"><a href="strings.html#%28def._%28%28quote._~23~25kernel%29._string~3f%29%29" class="RktValLink" data-pltdoc="x">string?</a></span><span class="hspace"> </span><span class="RktVal">#f</span><span class="RktPn">)</span><span class="hspace"> </span>=<span class="hspace"> </span><span class="RktVal">#f</span></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">local-port-no</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fbase..rkt%29._or%2Fc%29%29" class="RktValLink" data-pltdoc="x">or/c</a></span><span class="hspace"> </span><span class="RktSym"><a href="tcp.html#%28def._%28%28lib._racket%2Ftcp..rkt%29._port-number~3f%29%29" class="RktValLink" data-pltdoc="x">port-number?</a></span><span class="hspace"> </span><span class="RktVal">#f</span><span class="RktPn">)</span></td></tr></table></blockquote></div><div class="SIntrapara">Like <span class="RktSym"><a href="tcp.html#%28def._%28%28lib._racket%2Ftcp..rkt%29._tcp-connect%29%29" class="RktValLink" data-pltdoc="x">tcp-connect</a></span>, but breaking is enabled (see
|
|
<a href="breakhandler.html" data-pltdoc="x">Breaks</a>) while trying to connect. If breaking is
|
|
disabled when <span class="RktSym"><a href="tcp.html#%28def._%28%28lib._racket%2Ftcp..rkt%29._tcp-connect%2Fenable-break%29%29" class="RktValLink" data-pltdoc="x">tcp-connect/enable-break</a></span> is called, then either
|
|
ports are returned or the <span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._exn~3abreak%29%29" class="RktValLink" data-pltdoc="x">exn:break</a></span> exception is raised, but
|
|
not both.</div></p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>procedure</p></div></div><table cellspacing="0" cellpadding="0" class="prototype RForeground"><tr><td valign="top"><span class="RktPn">(</span><a name="(def._((lib._racket/tcp..rkt)._tcp-accept))"></a><span title="Provided from: racket/tcp, racket | Package: base"><span class="RktSym"><a href="tcp.html#%28def._%28%28lib._racket%2Ftcp..rkt%29._tcp-accept%29%29" class="RktValDef RktValLink" data-pltdoc="x">tcp-accept</a></span></span><span class="hspace"> </span><span class="RktVar">listener</span><span class="RktPn">)</span></td><td valign="top"><span class="hspace"> </span></td><td valign="top">→</td><td valign="top"><span class="hspace"> </span></td><td valign="top"><table cellspacing="0" cellpadding="0"><tr><td><span class="RktSym"><a href="port-ops.html#%28def._%28%28quote._~23~25kernel%29._input-port~3f%29%29" class="RktValLink" data-pltdoc="x">input-port?</a></span></td><td><span class="hspace"> </span></td><td><span class="RktSym"><a href="port-ops.html#%28def._%28%28quote._~23~25kernel%29._output-port~3f%29%29" class="RktValLink" data-pltdoc="x">output-port?</a></span></td></tr></table></td></tr></table></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">listener</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="tcp.html#%28def._%28%28lib._racket%2Ftcp..rkt%29._tcp-listener~3f%29%29" class="RktValLink" data-pltdoc="x">tcp-listener?</a></span></td></tr></table></blockquote></div><div class="SIntrapara">Accepts a client connection for the server associated with
|
|
<span class="RktVar">listener</span>. If no client connection is waiting on the
|
|
listening port, the call to <span class="RktSym"><a href="tcp.html#%28def._%28%28lib._racket%2Ftcp..rkt%29._tcp-accept%29%29" class="RktValLink" data-pltdoc="x">tcp-accept</a></span> will block. (See also
|
|
<span class="RktSym"><a href="tcp.html#%28def._%28%28lib._racket%2Ftcp..rkt%29._tcp-accept-ready~3f%29%29" class="RktValLink" data-pltdoc="x">tcp-accept-ready?</a></span>.)</div></p><p>Two values are returned by <span class="RktSym"><a href="tcp.html#%28def._%28%28lib._racket%2Ftcp..rkt%29._tcp-accept%29%29" class="RktValLink" data-pltdoc="x">tcp-accept</a></span>: an input port and an
|
|
output port. Data can be received from the client through the input
|
|
port and sent to the client through the output port. These ports are
|
|
placed into the management of the current custodian (see
|
|
<a href="custodians.html" data-pltdoc="x">Custodians</a>).</p><p>In terms of buffering and connection states, the ports act the same as
|
|
ports from <span class="RktSym"><a href="tcp.html#%28def._%28%28lib._racket%2Ftcp..rkt%29._tcp-connect%29%29" class="RktValLink" data-pltdoc="x">tcp-connect</a></span>.</p><p>If a connection cannot be accepted by <span class="RktSym"><a href="tcp.html#%28def._%28%28lib._racket%2Ftcp..rkt%29._tcp-accept%29%29" class="RktValLink" data-pltdoc="x">tcp-accept</a></span>, or if the
|
|
listener has been closed, the <span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._exn~3afail~3anetwork%29%29" class="RktValLink" data-pltdoc="x">exn:fail:network</a></span> exception is raised.</p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>procedure</p></div></div><table cellspacing="0" cellpadding="0" class="prototype RForeground"><tr><td valign="top"><span class="RktPn">(</span><a name="(def._((lib._racket/tcp..rkt)._tcp-accept/enable-break))"></a><span title="Provided from: racket/tcp, racket | Package: base"><span class="RktSym"><a href="tcp.html#%28def._%28%28lib._racket%2Ftcp..rkt%29._tcp-accept%2Fenable-break%29%29" class="RktValDef RktValLink" data-pltdoc="x">tcp-accept/enable-break</a></span></span><span class="hspace"> </span><span class="RktVar">listener</span><span class="RktPn">)</span></td><td valign="top"><span class="hspace"> </span></td><td valign="top">→</td><td valign="top"><span class="hspace"> </span></td><td valign="top"><table cellspacing="0" cellpadding="0"><tr><td><span class="RktSym"><a href="port-ops.html#%28def._%28%28quote._~23~25kernel%29._input-port~3f%29%29" class="RktValLink" data-pltdoc="x">input-port?</a></span></td><td><span class="hspace"> </span></td><td><span class="RktSym"><a href="port-ops.html#%28def._%28%28quote._~23~25kernel%29._output-port~3f%29%29" class="RktValLink" data-pltdoc="x">output-port?</a></span></td></tr></table></td></tr></table></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">listener</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="tcp.html#%28def._%28%28lib._racket%2Ftcp..rkt%29._tcp-listener~3f%29%29" class="RktValLink" data-pltdoc="x">tcp-listener?</a></span></td></tr></table></blockquote></div><div class="SIntrapara">Like <span class="RktSym"><a href="tcp.html#%28def._%28%28lib._racket%2Ftcp..rkt%29._tcp-accept%29%29" class="RktValLink" data-pltdoc="x">tcp-accept</a></span>, but breaking is enabled (see
|
|
<a href="breakhandler.html" data-pltdoc="x">Breaks</a>) while trying to accept a connection. If
|
|
breaking is disabled when <span class="RktSym"><a href="tcp.html#%28def._%28%28lib._racket%2Ftcp..rkt%29._tcp-accept%2Fenable-break%29%29" class="RktValLink" data-pltdoc="x">tcp-accept/enable-break</a></span> is called,
|
|
then either ports are returned or the <span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._exn~3abreak%29%29" class="RktValLink" data-pltdoc="x">exn:break</a></span> exception is
|
|
raised, but not both.</div></p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>procedure</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((lib._racket/tcp..rkt)._tcp-accept-ready~3f))"></a><span title="Provided from: racket/tcp, racket | Package: base"><span class="RktSym"><a href="tcp.html#%28def._%28%28lib._racket%2Ftcp..rkt%29._tcp-accept-ready~3f%29%29" class="RktValDef RktValLink" data-pltdoc="x">tcp-accept-ready?</a></span></span><span class="hspace"> </span><span class="RktVar">listener</span><span class="RktPn">)</span><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktSym"><a href="booleans.html#%28def._%28%28quote._~23~25kernel%29._boolean~3f%29%29" class="RktValLink" data-pltdoc="x">boolean?</a></span></p></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">listener</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="tcp.html#%28def._%28%28lib._racket%2Ftcp..rkt%29._tcp-listener~3f%29%29" class="RktValLink" data-pltdoc="x">tcp-listener?</a></span></td></tr></table></blockquote></div><div class="SIntrapara">Tests whether an unaccepted client has connected to the server
|
|
associated with <span class="RktVar">listener</span>. If a client is
|
|
waiting, the return value is <span class="RktVal">#t</span>, otherwise it is
|
|
<span class="RktVal">#f</span>. A client is accepted with the <span class="RktSym"><a href="tcp.html#%28def._%28%28lib._racket%2Ftcp..rkt%29._tcp-accept%29%29" class="RktValLink" data-pltdoc="x">tcp-accept</a></span>
|
|
procedure, which returns ports for communicating with the client and
|
|
removes the client from the list of unaccepted clients.</div></p><p>If the listener has been closed, the <span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._exn~3afail~3anetwork%29%29" class="RktValLink" data-pltdoc="x">exn:fail:network</a></span> exception is raised.</p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>procedure</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((lib._racket/tcp..rkt)._tcp-close))"></a><span title="Provided from: racket/tcp, racket | Package: base"><span class="RktSym"><a href="tcp.html#%28def._%28%28lib._racket%2Ftcp..rkt%29._tcp-close%29%29" class="RktValDef RktValLink" data-pltdoc="x">tcp-close</a></span></span><span class="hspace"> </span><span class="RktVar">listener</span><span class="RktPn">)</span><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktSym"><a href="void.html#%28def._%28%28quote._~23~25kernel%29._void~3f%29%29" class="RktValLink" data-pltdoc="x">void?</a></span></p></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">listener</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="tcp.html#%28def._%28%28lib._racket%2Ftcp..rkt%29._tcp-listener~3f%29%29" class="RktValLink" data-pltdoc="x">tcp-listener?</a></span></td></tr></table></blockquote></div><div class="SIntrapara">Shuts down the server associated with <span class="RktVar">listener</span>. All
|
|
unaccepted clients receive an end-of-file from the server; connections
|
|
to accepted clients are unaffected.</div></p><p>If the listener has already been closed, the <span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._exn~3afail~3anetwork%29%29" class="RktValLink" data-pltdoc="x">exn:fail:network</a></span> exception is raised.</p><p>The listener’s port number may not become immediately available for
|
|
new listeners (with the default <span class="RktVar">reuse?</span> argument of
|
|
<span class="RktSym"><a href="tcp.html#%28def._%28%28lib._racket%2Ftcp..rkt%29._tcp-listen%29%29" class="RktValLink" data-pltdoc="x">tcp-listen</a></span>). For further information, see Stevens’s
|
|
explanation of the <span class="stt">TIME_WAIT</span> TCP state.</p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>procedure</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((lib._racket/tcp..rkt)._tcp-listener~3f))"></a><span title="Provided from: racket/tcp, racket | Package: base"><span class="RktSym"><a href="tcp.html#%28def._%28%28lib._racket%2Ftcp..rkt%29._tcp-listener~3f%29%29" class="RktValDef RktValLink" data-pltdoc="x">tcp-listener?</a></span></span><span class="hspace"> </span><span class="RktVar">v</span><span class="RktPn">)</span><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktSym"><a href="booleans.html#%28def._%28%28quote._~23~25kernel%29._boolean~3f%29%29" class="RktValLink" data-pltdoc="x">boolean?</a></span></p></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">v</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._any%2Fc%29%29" class="RktValLink" data-pltdoc="x">any/c</a></span></td></tr></table></blockquote></div><div class="SIntrapara">Returns <span class="RktVal">#t</span> if <span class="RktVar">v</span> is a <a href="tcp.html#%28tech._tcp._listener%29" class="techoutside" data-pltdoc="x"><span class="techinside">TCP listener</span></a> created by
|
|
<span class="RktSym"><a href="tcp.html#%28def._%28%28lib._racket%2Ftcp..rkt%29._tcp-listen%29%29" class="RktValLink" data-pltdoc="x">tcp-listen</a></span>, <span class="RktVal">#f</span> otherwise.</div></p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>procedure</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((lib._racket/tcp..rkt)._tcp-accept-evt))"></a><span title="Provided from: racket/tcp, racket | Package: base"><span class="RktSym"><a href="tcp.html#%28def._%28%28lib._racket%2Ftcp..rkt%29._tcp-accept-evt%29%29" class="RktValDef RktValLink" data-pltdoc="x">tcp-accept-evt</a></span></span><span class="hspace"> </span><span class="RktVar">listener</span><span class="RktPn">)</span><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktSym"><a href="sync.html#%28def._%28%28quote._~23~25kernel%29._evt~3f%29%29" class="RktValLink" data-pltdoc="x">evt?</a></span></p></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">listener</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="tcp.html#%28def._%28%28lib._racket%2Ftcp..rkt%29._tcp-listener~3f%29%29" class="RktValLink" data-pltdoc="x">tcp-listener?</a></span></td></tr></table></blockquote></div><div class="SIntrapara">Returns a <a href="sync.html#%28tech._synchronizable._event%29" class="techoutside" data-pltdoc="x"><span class="techinside">synchronizable event</span></a> (see <a href="sync.html" data-pltdoc="x">Events</a>) that is
|
|
<a href="sync.html#%28tech._ready._for._synchronization%29" class="techoutside" data-pltdoc="x"><span class="techinside">ready for synchronization</span></a> when <span class="RktSym"><a href="tcp.html#%28def._%28%28lib._racket%2Ftcp..rkt%29._tcp-accept%29%29" class="RktValLink" data-pltdoc="x">tcp-accept</a></span> on <span class="RktVar">listener</span> would
|
|
not block. The <a href="sync.html#%28tech._synchronization._result%29" class="techoutside" data-pltdoc="x"><span class="techinside">synchronization result</span></a> is a
|
|
list of two items, which correspond to the two results of
|
|
<span class="RktSym"><a href="tcp.html#%28def._%28%28lib._racket%2Ftcp..rkt%29._tcp-accept%29%29" class="RktValLink" data-pltdoc="x">tcp-accept</a></span>. (If the event is not chosen in a <span class="RktSym"><a href="sync.html#%28def._%28%28quote._~23~25kernel%29._sync%29%29" class="RktValLink" data-pltdoc="x">sync</a></span>, no connections are
|
|
accepted.) The ports are placed into the management of the custodian
|
|
that is the current custodian (see <a href="custodians.html" data-pltdoc="x">Custodians</a>) at the time that
|
|
<span class="RktSym"><a href="tcp.html#%28def._%28%28lib._racket%2Ftcp..rkt%29._tcp-accept-evt%29%29" class="RktValLink" data-pltdoc="x">tcp-accept-evt</a></span> is called.</div></p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>procedure</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((lib._racket/tcp..rkt)._tcp-abandon-port))"></a><span title="Provided from: racket/tcp, racket | Package: base"><span class="RktSym"><a href="tcp.html#%28def._%28%28lib._racket%2Ftcp..rkt%29._tcp-abandon-port%29%29" class="RktValDef RktValLink" data-pltdoc="x">tcp-abandon-port</a></span></span><span class="hspace"> </span><span class="RktVar">tcp-port</span><span class="RktPn">)</span><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktSym"><a href="void.html#%28def._%28%28quote._~23~25kernel%29._void~3f%29%29" class="RktValLink" data-pltdoc="x">void?</a></span></p></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">tcp-port</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="tcp.html#%28def._%28%28lib._racket%2Ftcp..rkt%29._tcp-port~3f%29%29" class="RktValLink" data-pltdoc="x">tcp-port?</a></span></td></tr></table></blockquote></div><div class="SIntrapara">Like <span class="RktSym"><a href="port-ops.html#%28def._%28%28quote._~23~25kernel%29._close-output-port%29%29" class="RktValLink" data-pltdoc="x">close-output-port</a></span> or <span class="RktSym"><a href="port-ops.html#%28def._%28%28quote._~23~25kernel%29._close-input-port%29%29" class="RktValLink" data-pltdoc="x">close-input-port</a></span>
|
|
(depending on whether <span class="RktVar">tcp-port</span> is an input or output port),
|
|
but if <span class="RktVar">tcp-port</span> is an output port and its associated input
|
|
port is not yet closed, then the other end of the TCP connection does
|
|
not receive a TCP close message until the input port is also
|
|
closed.</div></p><p>The TCP protocol does not include a “no longer reading” state on
|
|
connections, so <span class="RktSym"><a href="tcp.html#%28def._%28%28lib._racket%2Ftcp..rkt%29._tcp-abandon-port%29%29" class="RktValLink" data-pltdoc="x">tcp-abandon-port</a></span> is equivalent to
|
|
<span class="RktSym"><a href="port-ops.html#%28def._%28%28quote._~23~25kernel%29._close-input-port%29%29" class="RktValLink" data-pltdoc="x">close-input-port</a></span> on input <a href="tcp.html#%28tech._tcp._port%29" class="techoutside" data-pltdoc="x"><span class="techinside">TCP ports</span></a>.</p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>procedure</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((lib._racket/tcp..rkt)._tcp-addresses))"></a><span title="Provided from: racket/tcp, racket | Package: base"><span class="RktSym"><a href="tcp.html#%28def._%28%28lib._racket%2Ftcp..rkt%29._tcp-addresses%29%29" class="RktValDef RktValLink" data-pltdoc="x">tcp-addresses</a></span></span><span class="hspace"> </span><span class="RktVar">tcp-port</span><span class="hspace"> </span><span class="RktOpt">[</span><span class="RktVar">port-numbers?</span><span class="RktOpt">]</span><span class="RktPn">)</span></p></blockquote></td></tr><tr><td><table cellspacing="0" cellpadding="0" class="prototype"><tr><td valign="top"><span class="hspace"> </span></td><td valign="top">→</td><td valign="top"><span class="hspace"> </span></td><td valign="top"><table cellspacing="0" cellpadding="0" class="RktBlk"><tr><td><span class="RktPn">(</span><span class="RktSym"><a href="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fbase..rkt%29._or%2Fc%29%29" class="RktValLink" data-pltdoc="x">or/c</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="values.html#%28def._%28%28quote._~23~25kernel%29._values%29%29" class="RktValLink" data-pltdoc="x">values</a></span><span class="hspace"> </span><span class="RktSym"><a href="strings.html#%28def._%28%28quote._~23~25kernel%29._string~3f%29%29" class="RktValLink" data-pltdoc="x">string?</a></span><span class="hspace"> </span><span class="RktSym"><a href="strings.html#%28def._%28%28quote._~23~25kernel%29._string~3f%29%29" class="RktValLink" data-pltdoc="x">string?</a></span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="values.html#%28def._%28%28quote._~23~25kernel%29._values%29%29" class="RktValLink" data-pltdoc="x">values</a></span><span class="hspace"> </span><span class="RktSym"><a href="strings.html#%28def._%28%28quote._~23~25kernel%29._string~3f%29%29" class="RktValLink" data-pltdoc="x">string?</a></span><span class="hspace"> </span><span class="RktSym"><a href="tcp.html#%28def._%28%28lib._racket%2Ftcp..rkt%29._port-number~3f%29%29" class="RktValLink" data-pltdoc="x">port-number?</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktSym"><a href="strings.html#%28def._%28%28quote._~23~25kernel%29._string~3f%29%29" class="RktValLink" data-pltdoc="x">string?</a></span><span class="hspace"> </span><span class="RktSym"><a href="tcp.html#%28def._%28%28lib._racket%2Ftcp..rkt%29._listen-port-number~3f%29%29" class="RktValLink" data-pltdoc="x">listen-port-number?</a></span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr></table></td></tr></table></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">tcp-port</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fbase..rkt%29._or%2Fc%29%29" class="RktValLink" data-pltdoc="x">or/c</a></span><span class="hspace"> </span><span class="RktSym"><a href="tcp.html#%28def._%28%28lib._racket%2Ftcp..rkt%29._tcp-port~3f%29%29" class="RktValLink" data-pltdoc="x">tcp-port?</a></span><span class="hspace"> </span><span class="RktSym"><a href="tcp.html#%28def._%28%28lib._racket%2Ftcp..rkt%29._tcp-listener~3f%29%29" class="RktValLink" data-pltdoc="x">tcp-listener?</a></span><span class="hspace"> </span><span class="RktSym"><a href="udp.html#%28def._%28%28lib._racket%2Fudp..rkt%29._udp~3f%29%29" class="RktValLink" data-pltdoc="x">udp?</a></span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">port-numbers?</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._any%2Fc%29%29" class="RktValLink" data-pltdoc="x">any/c</a></span><span class="hspace"> </span>=<span class="hspace"> </span><span class="RktVal">#f</span></td></tr></table></blockquote></div><div class="SIntrapara">Returns two strings when <span class="RktVar">port-numbers?</span> is <span class="RktVal">#f</span> (the
|
|
default). The first string is the Internet address for the local
|
|
machine as viewed by the given <a href="tcp.html#%28tech._tcp._port%29" class="techoutside" data-pltdoc="x"><span class="techinside">TCP port</span></a>’s connection, for the
|
|
TCP listener, or the UDP socket. (When a machine serves
|
|
multiple addresses, as it usually does if you count the loopback
|
|
device, the result is connection-specific or
|
|
listener-specific.) If a listener or UDP socket is given and it has no specific
|
|
host, the first string result is <span class="RktVal">"0.0.0.0"</span>. The second string
|
|
is the Internet address for the other end of the connection, or always
|
|
<span class="RktVal">"0.0.0.0"</span> for a listener or unconnected UDP socket.</div></p><p>If <span class="RktVar">port-numbers?</span> is true, then four results are returned: a
|
|
string for the local machine’s address, an exact integer between
|
|
<span class="RktVal">1</span> and <span class="RktVal">65535</span> for the local machine’s port number, a
|
|
string for the remote machine’s address, and an exact integer between
|
|
<span class="RktVal">1</span> and <span class="RktVal">65535</span> for the remote machine’s port number or
|
|
<span class="RktVal">0</span> for a listener.</p><p>If the given port, listener, or socket has been closed, the
|
|
<span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._exn~3afail~3anetwork%29%29" class="RktValLink" data-pltdoc="x">exn:fail:network</a></span> exception is raised.</p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>procedure</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((lib._racket/tcp..rkt)._tcp-port~3f))"></a><span title="Provided from: racket/tcp, racket | Package: base"><span class="RktSym"><a href="tcp.html#%28def._%28%28lib._racket%2Ftcp..rkt%29._tcp-port~3f%29%29" class="RktValDef RktValLink" data-pltdoc="x">tcp-port?</a></span></span><span class="hspace"> </span><span class="RktVar">v</span><span class="RktPn">)</span><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktSym"><a href="booleans.html#%28def._%28%28quote._~23~25kernel%29._boolean~3f%29%29" class="RktValLink" data-pltdoc="x">boolean?</a></span></p></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">v</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._any%2Fc%29%29" class="RktValLink" data-pltdoc="x">any/c</a></span></td></tr></table></blockquote></div><div class="SIntrapara">Returns <span class="RktVal">#t</span> if <span class="RktVar">v</span> is a <a name="(tech._tcp._port)"></a><span style="font-style: italic">TCP port</span>—<wbr></wbr>which is a
|
|
port returned by <span class="RktSym"><a href="tcp.html#%28def._%28%28lib._racket%2Ftcp..rkt%29._tcp-accept%29%29" class="RktValLink" data-pltdoc="x">tcp-accept</a></span>, <span class="RktSym"><a href="tcp.html#%28def._%28%28lib._racket%2Ftcp..rkt%29._tcp-connect%29%29" class="RktValLink" data-pltdoc="x">tcp-connect</a></span>,
|
|
<span class="RktSym"><a href="tcp.html#%28def._%28%28lib._racket%2Ftcp..rkt%29._tcp-accept%2Fenable-break%29%29" class="RktValLink" data-pltdoc="x">tcp-accept/enable-break</a></span>, or
|
|
<span class="RktSym"><a href="tcp.html#%28def._%28%28lib._racket%2Ftcp..rkt%29._tcp-connect%2Fenable-break%29%29" class="RktValLink" data-pltdoc="x">tcp-connect/enable-break</a></span>—<wbr></wbr><span class="RktVal">#f</span> otherwise.</div></p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>value</p></div></div><p class="RForeground"><a name="(def._((lib._racket/tcp..rkt)._port-number~3f))"></a><span title="Provided from: racket/tcp, racket | Package: base"><span class="RktSym"><a href="tcp.html#%28def._%28%28lib._racket%2Ftcp..rkt%29._port-number~3f%29%29" class="RktValDef RktValLink" data-pltdoc="x">port-number?</a></span></span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="contract-utilities.html#%28def._%28%28lib._racket%2Fcontract%2Fprivate%2Fguts..rkt%29._contract~3f%29%29" class="RktValLink" data-pltdoc="x">contract?</a></span></p></blockquote></td></tr></table></blockquote></div><div class="SIntrapara">Equivalent to <span class="RktPn">(</span><span class="RktSym"><a href="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fbase..rkt%29._integer-in%29%29" class="RktValLink" data-pltdoc="x">integer-in</a></span><span class="stt"> </span><span class="RktVal">1</span><span class="stt"> </span><span class="RktVal">65535</span><span class="RktPn">)</span>.</div></p><p class="SHistory">Added in version 6.3 of package <span class="stt">base</span>.</p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>value</p></div></div><p class="RForeground"><a name="(def._((lib._racket/tcp..rkt)._listen-port-number~3f))"></a><span title="Provided from: racket/tcp, racket | Package: base"><span class="RktSym"><a href="tcp.html#%28def._%28%28lib._racket%2Ftcp..rkt%29._listen-port-number~3f%29%29" class="RktValDef RktValLink" data-pltdoc="x">listen-port-number?</a></span></span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="contract-utilities.html#%28def._%28%28lib._racket%2Fcontract%2Fprivate%2Fguts..rkt%29._contract~3f%29%29" class="RktValLink" data-pltdoc="x">contract?</a></span></p></blockquote></td></tr></table></blockquote></div><div class="SIntrapara">Equivalent to <span class="RktPn">(</span><span class="RktSym"><a href="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fbase..rkt%29._integer-in%29%29" class="RktValLink" data-pltdoc="x">integer-in</a></span><span class="stt"> </span><span class="RktVal">0</span><span class="stt"> </span><span class="RktVal">65535</span><span class="RktPn">)</span>.</div></p><p class="SHistory">Added in version 6.3 of package <span class="stt">base</span>.</p><div class="navsetbottom"><span class="navleft"><form class="searchform"><input class="searchbox" id="searchbox" type="text" tabindex="1" placeholder="...search manuals..." title="Enter a search string to search the manuals" onkeypress="return DoSearchKey(event, this, "8.6", "../");"/></form> <a href="https://docs.racket-lang.org/index.html" title="up to the documentation top" data-pltdoc="x" onclick="return GotoPLTRoot("8.6");">top</a><span class="tocsettoggle"> <a href="javascript:void(0);" title="show/hide table of contents" onclick="TocsetToggle();">contents</a></span></span><span class="navright"> <a href="networking.html" title="backward to "15.3 Networking"" data-pltdoc="x">← prev</a> <a href="networking.html" title="up to "15.3 Networking"" data-pltdoc="x">up</a> <a href="udp.html" title="forward to "15.3.2 UDP"" data-pltdoc="x">next →</a></span> </div></div></div><div id="contextindicator"> </div></body></html> |