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<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>15.3.2 UDP</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
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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/udp..rkt)._udp-open-socket))"></a><span title="Provided from: racket/udp, racket | Package: base"><span class="RktSym"><a href="udp.html#%28def._%28%28lib._racket%2Fudp..rkt%29._udp-open-socket%29%29" class="RktValDef RktValLink" data-pltdoc="x">udp-open-socket</a></span></span></td><td valign="top"><span class="hspace"> </span><span class="RktOpt">[</span></td><td valign="top"><span class="RktVar">family-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">family-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"><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></td></tr></table></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">family-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">family-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">Creates and returns a <a name="(tech._udp._socket)"></a><span style="font-style: italic">UDP socket</span> to send and receive
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datagrams (broadcasting is allowed). Initially, the socket is not
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bound or connected to any address or port.</div></p><p>If <span class="RktVar">family-hostname</span> or <span class="RktVar">family-port-no</span> is not
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<span class="RktVal">#f</span>, then the socket’s protocol family is determined from
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these arguments. The socket is <span style="font-style: italic">not</span> bound to the hostname
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or port number. For example, the arguments might be the hostname
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and port to which messages will be sent through the socket, which
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ensures that the socket’s protocol family is consistent with the
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destination. Alternately, the arguments might be the same as for
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a future call to <span class="RktSym"><a href="udp.html#%28def._%28%28lib._racket%2Fudp..rkt%29._udp-bind%21%29%29" class="RktValLink" data-pltdoc="x">udp-bind!</a></span>, which ensures that the
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socket’s protocol family is consistent with the binding. If
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neither <span class="RktVar">family-hostname</span> nor <span class="RktVar">family-port-no</span> is
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non-<span class="RktVal">#f</span>, then the socket’s protocol family is IPv4.</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/udp..rkt)._udp-bind!))"></a><span title="Provided from: racket/udp, racket | Package: base"><span class="RktSym"><a href="udp.html#%28def._%28%28lib._racket%2Fudp..rkt%29._udp-bind%21%29%29" class="RktValDef RktValLink" data-pltdoc="x">udp-bind!</a></span></span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="RktVar">udp-socket</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-string</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">reuse?</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="void.html#%28def._%28%28quote._~23~25kernel%29._void~3f%29%29" class="RktValLink" data-pltdoc="x">void?</a></span></td></tr></table></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">udp-socket</span><span class="hspace"> </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></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">hostname-string</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></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">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%2F
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<span class="RktVar">port-no</span>. If <span class="RktVar">port-no</span> is 0 the <span class="RktVar">udp-socket</span> is
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bound to an ephemeral port, which can be determined by calling
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<span class="RktSym"><a href="udp.html#%28def._%28%28lib._racket%2Fudp..rkt%29._udp-addresses%29%29" class="RktValLink" data-pltdoc="x">udp-addresses</a></span>.</div></p><p>If <span class="RktVar">hostname-string</span> is <span class="RktVal">#f</span>, then the socket
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accepts connections to all of the listening machine’s IP
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addresses at <span class="RktVar">port-no</span>. Otherwise, the socket accepts
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connections only at the IP address associated with the given
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name. For example, providing <span class="RktVal">"127.0.0.1"</span> as
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<span class="RktVar">hostname-string</span> typically creates a listener that
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accepts only connections to <span class="RktVal">"127.0.0.1"</span> from the local
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machine.</p><p>A socket cannot receive datagrams until it is bound to a local address
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and port. If a socket is not bound before it is used with a sending
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procedure <span class="RktSym"><a href="udp.html#%28def._%28%28lib._racket%2Fudp..rkt%29._udp-send%29%29" class="RktValLink" data-pltdoc="x">udp-send</a></span>, <span class="RktSym"><a href="udp.html#%28def._%28%28lib._racket%2Fudp..rkt%29._udp-send-to%29%29" class="RktValLink" data-pltdoc="x">udp-send-to</a></span>, etc., the sending
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procedure binds the socket to a random local port. Similarly, if an
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event from <span class="RktSym"><a href="udp.html#%28def._%28%28lib._racket%2Fudp..rkt%29._udp-send-evt%29%29" class="RktValLink" data-pltdoc="x">udp-send-evt</a></span> or <span class="RktSym"><a href="udp.html#%28def._%28%28lib._racket%2Fudp..rkt%29._udp-send-to-evt%29%29" class="RktValLink" data-pltdoc="x">udp-send-to-evt</a></span> is chosen
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for a synchronization (see <a href="sync.html" data-pltdoc="x">Events</a>), the socket is bound; if
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the event is not chosen, the socket may or may not become bound.</p><p>The binding of a bound socket cannot be changed, with one exception:
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on some systems, if the socket is bound automatically when sending, if
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the socket is disconnected via <span class="RktSym"><a href="udp.html#%28def._%28%28lib._racket%2Fudp..rkt%29._udp-connect%21%29%29" class="RktValLink" data-pltdoc="x">udp-connect!</a></span>, and if the
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socket is later used again in a send, then the later send may change
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the socket’s automatic binding.</p><p>If <span class="RktVar">udp-socket</span> is already bound or closed, the
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<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>If the <span class="RktVar">reuse?</span> argument is true, then <span class="RktSym"><a href="udp.html#%28def._%28%28lib._racket%2Fudp..rkt%29._udp-bind%21%29%29" class="RktValLink" data-pltdoc="x">udp-bind!</a></span> will
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set the <span class="stt">SO_REUSEADDR</span> socket option before binding, permitting the
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sharing of access to a UDP port between many processes on a single
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machine when using UDP multicast.</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/udp..rkt)._udp-connect!))"></a><span title="Provided from: racket/udp, racket | Package: base"><span class="RktSym"><a href="udp.html#%28def._%28%28lib._racket%2Fudp..rkt%29._udp-connect%21%29%29" class="RktValDef RktValLink" data-pltdoc="x">udp-connect!</a></span></span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="RktVar">udp-socket</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-string</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><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="void.html#%28def._%28%28quote._~23~25kernel%29._void~3f%29%29" class="RktValLink" data-pltdoc="x">void?</a></span></td></tr></table></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">udp-socket</span><span class="hspace"> </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></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">hostname-string</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></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">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">Connects the socket to the indicated remote address and port if
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<span class="RktVar">hostname-string</span> is a string and <span class="RktVar">port-no</span> is an exact
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integer.</div></p><p>If <span class="RktVar">hostname-string</span> is <span class="RktVal">#f</span>, then <span class="RktVar">port-no</span> also
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must be <span class="RktVal">#f</span>, and the port is disconnected (if connected). If
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one of <span class="RktVar">hostname-string</span> or <span class="RktVar">port-no</span> is <span class="RktVal">#f</span> and
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the other is not, the <span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._exn~3afail~3acontract%29%29" class="RktValLink" data-pltdoc="x">exn:fail:contract</a></span> exception is raised.</p><p>A connected socket can be used with <span class="RktSym"><a href="udp.html#%28def._%28%28lib._racket%2Fudp..rkt%29._udp-send%29%29" class="RktValLink" data-pltdoc="x">udp-send</a></span> (not
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<span class="RktSym"><a href="udp.html#%28def._%28%28lib._racket%2Fudp..rkt%29._udp-send-to%29%29" class="RktValLink" data-pltdoc="x">udp-send-to</a></span>), and it accepts datagrams only from the
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connected address and port. A socket need not be connected to receive
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datagrams. A socket can be connected, re-connected, and disconnected
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any number of times.</p><p>If <span class="RktVar">udp-socket</span> is 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/udp..rkt)._udp-send-to))"></a><span title="Provided from: racket/udp, racket | Package: base"><span class="RktSym"><a href="udp.html#%28def._%28%28lib._racket%2Fudp..rkt%29._udp-send-to%29%29" class="RktValDef RktValLink" data-pltdoc="x">udp-send-to</a></span></span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="RktVar">udp-socket</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></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></td><td valign="top"><span class="RktVar">bstr</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">start-pos</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">end-pos</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="void.html#%28def._%28%28quote._~23~25kernel%29._void~3f%29%29" class="RktValLink" data-pltdoc="x">void?</a></span></td></tr></table></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">udp-socket</span><span class="hspace"> </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></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="RktVal
|
||
|
|
the unconnected <span class="RktVar">udp-socket</span> to the socket at the remote
|
||
|
|
machine <span class="RktSym">hostname-address</span> on the port <span class="RktVar">port-no</span>. The
|
||
|
|
<span class="RktVar">udp-socket</span> need not be bound or connected; if it is not
|
||
|
|
bound, <span class="RktSym"><a href="udp.html#%28def._%28%28lib._racket%2Fudp..rkt%29._udp-send-to%29%29" class="RktValLink" data-pltdoc="x">udp-send-to</a></span> binds it to a random local port. If the
|
||
|
|
socket’s outgoing datagram queue is too full to support the send,
|
||
|
|
<span class="RktSym"><a href="udp.html#%28def._%28%28lib._racket%2Fudp..rkt%29._udp-send-to%29%29" class="RktValLink" data-pltdoc="x">udp-send-to</a></span> blocks until the datagram can be queued.</div></p><p>If <span class="RktVar">start-pos</span> is greater than the length of <span class="RktVar">bstr</span>, or
|
||
|
|
if <span class="RktVar">end-pos</span> is less than <span class="RktVar">start-pos</span> or greater than
|
||
|
|
the length of <span class="RktVar">bstr</span>, the <span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._exn~3afail~3acontract%29%29" class="RktValLink" data-pltdoc="x">exn:fail:contract</a></span> exception is raised.</p><p>If <span class="RktVar">udp-socket</span> is closed or connected, 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/udp..rkt)._udp-send))"></a><span title="Provided from: racket/udp, racket | Package: base"><span class="RktSym"><a href="udp.html#%28def._%28%28lib._racket%2Fudp..rkt%29._udp-send%29%29" class="RktValDef RktValLink" data-pltdoc="x">udp-send</a></span></span><span class="hspace"> </span><span class="RktVar">udp-socket</span><span class="hspace"> </span><span class="RktVar">bstr</span><span class="hspace"> </span><span class="RktOpt">[</span><span class="RktVar">start-pos</span><span class="hspace"> </span><span class="RktVar">end-pos</span><span class="RktOpt">]</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">udp-socket</span><span class="hspace"> </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></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">bstr</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="bytestrings.html#%28def._%28%28quote._~23~25kernel%29._bytes~3f%29%29" class="RktValLink" data-pltdoc="x">bytes?</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">start-pos</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">0</span></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">end-pos</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="RktPn">(</span><span class="RktSym"><a href="bytestrings.html#%28def._%28%28quote._~23~25kernel%29._bytes-length%29%29" class="RktValLink" data-pltdoc="x">bytes-length</a></span><span class="hspace"> </span><span class="RktVar">bstr</span><span class="RktPn">)</span></td></tr></table></blockquote></div><div class="SIntrapara">Like <span class="RktSym"><a href="udp.html#%28def._%28%28lib._racket%2Fudp..rkt%29._udp-send-to%29%29" class="RktValLink" data-pltdoc="x">udp-send-to</a></span>, except that <span class="RktVar">udp-socket</span> must be
|
||
|
|
connected, and the datagram goes to the connection target. If
|
||
|
|
<span class="RktVar">udp-socket</span> is closed or unconnected, 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.</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/udp..rkt)._udp-send-to*))"></a><span title="Provided from: racket/udp, racket | Package: base"><span class="RktSym"><a href="udp.html#%28def._%28%28lib._racket%2Fudp..rkt%29._udp-send-to%2A%29%29" class="RktValDef RktValLink" data-pltdoc="x">udp-send-to*</a></span></span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="RktVar">udp-socket</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></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></td><td valign="top"><span class="RktVar">bstr</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">start-pos</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">end-pos</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="booleans.html#%28def._%28%28quote._~23~25kernel%29._boolean~3f%29%29" class="RktValLink" data-pltdoc="x">boolean?</a></span></td></tr></table></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">udp-socket</span><span class="hspace"> </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></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
|
||
|
|
queue is too full to support the send, <span class="RktVal">#f</span> is returned,
|
||
|
|
otherwise the datagram is queued and the result is <span class="RktVal">#t</span>.</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/udp..rkt)._udp-send*))"></a><span title="Provided from: racket/udp, racket | Package: base"><span class="RktSym"><a href="udp.html#%28def._%28%28lib._racket%2Fudp..rkt%29._udp-send%2A%29%29" class="RktValDef RktValLink" data-pltdoc="x">udp-send*</a></span></span><span class="hspace"> </span><span class="RktVar">udp-socket</span><span class="hspace"> </span><span class="RktVar">bstr</span><span class="hspace"> </span><span class="RktOpt">[</span><span class="RktVar">start-pos</span><span class="hspace"> </span><span class="RktVar">end-pos</span><span class="RktOpt">]</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">udp-socket</span><span class="hspace"> </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></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">bstr</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="bytestrings.html#%28def._%28%28quote._~23~25kernel%29._bytes~3f%29%29" class="RktValLink" data-pltdoc="x">bytes?</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">start-pos</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">0</span></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">end-pos</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="RktPn">(</span><span class="RktSym"><a href="bytestrings.html#%28def._%28%28quote._~23~25kernel%29._bytes-length%29%29" class="RktValLink" data-pltdoc="x">bytes-length</a></span><span class="hspace"> </span><span class="RktVar">bstr</span><span class="RktPn">)</span></td></tr></table></blockquote></div><div class="SIntrapara">Like <span class="RktSym"><a href="udp.html#%28def._%28%28lib._racket%2Fudp..rkt%29._udp-send%29%29" class="RktValLink" data-pltdoc="x">udp-send</a></span>, except that (like <span class="RktSym"><a href="udp.html#%28def._%28%28lib._racket%2Fudp..rkt%29._udp-send-to%29%29" class="RktValLink" data-pltdoc="x">udp-send-to</a></span>) it
|
||
|
|
never blocks and returns <span class="RktVal">#f</span> or <span class="RktVal">#t</span>.</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/udp..rkt)._udp-send-to/enable-break))"></a><span title="Provided from: racket/udp, racket | Package: base"><span class="RktSym"><a href="udp.html#%28def._%28%28lib._racket%2Fudp..rkt%29._udp-send-to%2Fenable-break%29%29" class="RktValDef RktValLink" data-pltdoc="x">udp-send-to/enable-break</a></span></span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="RktVar">udp-socket</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></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></td><td valign="top"><span class="RktVar">bstr</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">start-pos</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">end-pos</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="void.html#%28def._%28%28quote._~23~25kernel%29._void~3f%29%29" class="RktValLink" data-pltdoc="x">void?</a></span></td></tr></table></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">udp-socket</span><span class="hspace"> </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></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="hspa
|
||
|
|
<a href="breakhandler.html" data-pltdoc="x">Breaks</a>) while trying to send the datagram. If
|
||
|
|
breaking is disabled when <span class="RktSym"><a href="udp.html#%28def._%28%28lib._racket%2Fudp..rkt%29._udp-send-to%2Fenable-break%29%29" class="RktValLink" data-pltdoc="x">udp-send-to/enable-break</a></span> is called,
|
||
|
|
then either the datagram is sent 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/udp..rkt)._udp-send/enable-break))"></a><span title="Provided from: racket/udp, racket | Package: base"><span class="RktSym"><a href="udp.html#%28def._%28%28lib._racket%2Fudp..rkt%29._udp-send%2Fenable-break%29%29" class="RktValDef RktValLink" data-pltdoc="x">udp-send/enable-break</a></span></span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="RktVar">udp-socket</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">bstr</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">start-pos</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">end-pos</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="void.html#%28def._%28%28quote._~23~25kernel%29._void~3f%29%29" class="RktValLink" data-pltdoc="x">void?</a></span></td></tr></table></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">udp-socket</span><span class="hspace"> </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></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">bstr</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="bytestrings.html#%28def._%28%28quote._~23~25kernel%29._bytes~3f%29%29" class="RktValLink" data-pltdoc="x">bytes?</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">start-pos</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">0</span></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">end-pos</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="RktPn">(</span><span class="RktSym"><a href="bytestrings.html#%28def._%28%28quote._~23~25kernel%29
|
||
|
|
<span class="RktSym"><a href="udp.html#%28def._%28%28lib._racket%2Fudp..rkt%29._udp-send-to%2Fenable-break%29%29" class="RktValLink" data-pltdoc="x">udp-send-to/enable-break</a></span>.</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/udp..rkt)._udp-receive!))"></a><span title="Provided from: racket/udp, racket | Package: base"><span class="RktSym"><a href="udp.html#%28def._%28%28lib._racket%2Fudp..rkt%29._udp-receive%21%29%29" class="RktValDef RktValLink" data-pltdoc="x">udp-receive!</a></span></span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="RktVar">udp-socket</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">bstr</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">start-pos</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">end-pos</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="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></td></tr><tr><td><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="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></table></td></tr></table></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">udp-socket</span><span class="hspace"> </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></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">bstr</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._and%2Fc%29%29" class="RktValLink" data-pltdoc="x">and/c</a></span><span class="hspace"> </span><span class="RktSym"><a href="bytestrings.html#%28def._%28%28quote._~23~25kernel%29._bytes~3f%29%29" class="RktValLink" data-pltdoc="x">bytes?</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="booleans.html#%28def._%28%28quote._~23~25kernel%29._not%29%29"
|
||
|
|
<span class="RktVar">udp-socket</span>’s next incoming datagram into <span class="RktVar">bstr</span>,
|
||
|
|
writing the datagram bytes starting at position <span class="RktVar">start-pos</span>
|
||
|
|
within <span class="RktVar">bstr</span>. The <span class="RktVar">udp-socket</span> must be bound to a local
|
||
|
|
address and port (but need not be connected). If no incoming datagram
|
||
|
|
is immediately available, <span class="RktSym"><a href="udp.html#%28def._%28%28lib._racket%2Fudp..rkt%29._udp-receive%21%29%29" class="RktValLink" data-pltdoc="x">udp-receive!</a></span> blocks until one is
|
||
|
|
available.</div></p><p>Three values are returned: the number of received bytes (between
|
||
|
|
<span class="RktVal">0</span> and <span class="RktVar">end-pos</span><span style="font-style: italic">-</span><span class="RktVar">start-pos</span>, a hostname
|
||
|
|
string indicating the source address of the datagram, and an integer
|
||
|
|
indicating the source port of the datagram. If the received datagram
|
||
|
|
is longer than <span class="RktVar">end-pos</span><span style="font-style: italic">-</span><span class="RktVar">start-pos</span> bytes, the
|
||
|
|
remainder is discarded.</p><p>If <span class="RktVar">start-pos</span> is greater than the length of <span class="RktVar">bstr</span>, or
|
||
|
|
if <span class="RktVar">end-pos</span> is less than <span class="RktVar">start-pos</span> or greater than
|
||
|
|
the length of <span class="RktVar">bstr</span>, the <span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._exn~3afail~3acontract%29%29" class="RktValLink" data-pltdoc="x">exn:fail:contract</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/udp..rkt)._udp-receive!*))"></a><span title="Provided from: racket/udp, racket | Package: base"><span class="RktSym"><a href="udp.html#%28def._%28%28lib._racket%2Fudp..rkt%29._udp-receive%21%2A%29%29" class="RktValDef RktValLink" data-pltdoc="x">udp-receive!*</a></span></span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="RktVar">udp-socket</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">bstr</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">start-pos</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">end-pos</span><span class="RktOpt">]</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="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="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="RktVal">#f</span><span class="RktPn">)</span></td></tr><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="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></td></tr><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="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></td></tr></table></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">udp-socket</span><span class="hspace"> </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>
|
||
|
|
datagram is available, the three result values are all <span class="RktVal">#f</span>.</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/udp..rkt)._udp-receive!/enable-break))"></a><span title="Provided from: racket/udp, racket | Package: base"><span class="RktSym"><a href="udp.html#%28def._%28%28lib._racket%2Fudp..rkt%29._udp-receive%21%2Fenable-break%29%29" class="RktValDef RktValLink" data-pltdoc="x">udp-receive!/enable-break</a></span></span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="RktVar">udp-socket</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">bstr</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">start-pos</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">end-pos</span><span class="RktOpt">]</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="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></td></tr><tr><td><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="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></table></td></tr></table></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">udp-socket</span><span class="hspace"> </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></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">bstr</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._and%2Fc%29%29" class="RktValLink" data-pltdoc="x">and/c</a></span><span class="hspace"> </span><span class="RktSym"><a href="bytestrings.html#%28def._%28%28quote._~23~25kernel%29._bytes~3f%29%29" class="RktValLink" data-pltdoc="x">bytes?</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="booleans.html#%28def._%28%28quote._~23~25kernel%29._not%29%29" class="RktValLink" data-pltdoc="x">not</a></span><span class="hspace"> </span><span class="RktSym"><a href="booleans.html#%28def._%28%28quote._~23~25kernel%29._immutable~3f%29%29" class="RktValLink" data-pltdoc="x">immutable?</a></span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">start-pos</span><span class="hspace">&
|
||
|
|
<a href="breakhandler.html" data-pltdoc="x">Breaks</a>) while trying to receive the datagram. If
|
||
|
|
breaking is disabled when <span class="RktSym"><a href="udp.html#%28def._%28%28lib._racket%2Fudp..rkt%29._udp-receive%21%2Fenable-break%29%29" class="RktValLink" data-pltdoc="x">udp-receive!/enable-break</a></span> is
|
||
|
|
called, then either a datagram is received 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/udp..rkt)._udp-set-receive-buffer-size!))"></a><span title="Provided from: racket/udp, racket | Package: base"><span class="RktSym"><a href="udp.html#%28def._%28%28lib._racket%2Fudp..rkt%29._udp-set-receive-buffer-size%21%29%29" class="RktValDef RktValLink" data-pltdoc="x">udp-set-receive-buffer-size!</a></span></span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="RktVar">udp-socket</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">size</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="void.html#%28def._%28%28quote._~23~25kernel%29._void~3f%29%29" class="RktValLink" data-pltdoc="x">void?</a></span></td></tr></table></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">udp-socket</span><span class="hspace"> </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></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">size</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="number-types.html#%28def._%28%28quote._~23~25kernel%29._exact-positive-integer~3f%29%29" class="RktValLink" data-pltdoc="x">exact-positive-integer?</a></span></td></tr></table></blockquote></div><div class="SIntrapara">Set the receive buffer size (<span class="stt">SO_RCVBUF</span>) for <span class="RktVar">udp-socket</span>.
|
||
|
|
Using a larger buffer can minimize packet loss that can occur due to
|
||
|
|
slow polling of a connection, including during a major garbage
|
||
|
|
collection.</div></p><p>If <span class="RktVar">size</span> is greater than the maximum allowed by the system,
|
||
|
|
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 class="SHistory">Added in version 7.1.0.11 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>procedure</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((lib._racket/udp..rkt)._udp-close))"></a><span title="Provided from: racket/udp, racket | Package: base"><span class="RktSym"><a href="udp.html#%28def._%28%28lib._racket%2Fudp..rkt%29._udp-close%29%29" class="RktValDef RktValLink" data-pltdoc="x">udp-close</a></span></span><span class="hspace"> </span><span class="RktVar">udp-socket</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">udp-socket</span><span class="hspace"> </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></td></tr></table></blockquote></div><div class="SIntrapara">Closes <span class="RktVar">udp-socket</span>, discarding unreceived datagrams. If the
|
||
|
|
socket is already 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.</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/udp..rkt)._udp~3f))"></a><span title="Provided from: racket/udp, racket | Package: base"><span class="RktSym"><a href="udp.html#%28def._%28%28lib._racket%2Fudp..rkt%29._udp~3f%29%29" class="RktValDef RktValLink" data-pltdoc="x">udp?</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 socket created by
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<span class="RktSym"><a href="udp.html#%28def._%28%28lib._racket%2Fudp..rkt%29._udp-open-socket%29%29" class="RktValLink" data-pltdoc="x">udp-open-socket</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/udp..rkt)._udp-bound~3f))"></a><span title="Provided from: racket/udp, racket | Package: base"><span class="RktSym"><a href="udp.html#%28def._%28%28lib._racket%2Fudp..rkt%29._udp-bound~3f%29%29" class="RktValDef RktValLink" data-pltdoc="x">udp-bound?</a></span></span><span class="hspace"> </span><span class="RktVar">udp-socket</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">udp-socket</span><span class="hspace"> </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></td></tr></table></blockquote></div><div class="SIntrapara">Returns <span class="RktVal">#t</span> if <span class="RktVar">udp-socket</span> is bound to a local address
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and port, <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/udp..rkt)._udp-connected~3f))"></a><span title="Provided from: racket/udp, racket | Package: base"><span class="RktSym"><a href="udp.html#%28def._%28%28lib._racket%2Fudp..rkt%29._udp-connected~3f%29%29" class="RktValDef RktValLink" data-pltdoc="x">udp-connected?</a></span></span><span class="hspace"> </span><span class="RktVar">udp-socket</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">udp-socket</span><span class="hspace"> </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></td></tr></table></blockquote></div><div class="SIntrapara">Returns <span class="RktVal">#t</span> if <span class="RktVar">udp-socket</span> is connected to a remote
|
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address and port, <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/udp..rkt)._udp-send-ready-evt))"></a><span title="Provided from: racket/udp, racket | Package: base"><span class="RktSym"><a href="udp.html#%28def._%28%28lib._racket%2Fudp..rkt%29._udp-send-ready-evt%29%29" class="RktValDef RktValLink" data-pltdoc="x">udp-send-ready-evt</a></span></span><span class="hspace"> </span><span class="RktVar">udp-socket</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">udp-socket</span><span class="hspace"> </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></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
|
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in a blocking state when <span class="RktSym"><a href="udp.html#%28def._%28%28lib._racket%2Fudp..rkt%29._udp-send-to%29%29" class="RktValLink" data-pltdoc="x">udp-send-to</a></span> on <span class="RktVar">udp-socket</span>
|
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would block. The <a href="sync.html#%28tech._synchronization._result%29" class="techoutside" data-pltdoc="x"><span class="techinside">synchronization result</span></a> is the event itself.</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/udp..rkt)._udp-receive-ready-evt))"></a><span title="Provided from: racket/udp, racket | Package: base"><span class="RktSym"><a href="udp.html#%28def._%28%28lib._racket%2Fudp..rkt%29._udp-receive-ready-evt%29%29" class="RktValDef RktValLink" data-pltdoc="x">udp-receive-ready-evt</a></span></span><span class="hspace"> </span><span class="RktVar">udp-socket</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">udp-socket</span><span class="hspace"> </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></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
|
||
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in a blocking state when <span class="RktSym"><a href="udp.html#%28def._%28%28lib._racket%2Fudp..rkt%29._udp-receive%21%29%29" class="RktValLink" data-pltdoc="x">udp-receive!</a></span> on <span class="RktVar">udp-socket</span>
|
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would block. The <a href="sync.html#%28tech._synchronization._result%29" class="techoutside" data-pltdoc="x"><span class="techinside">synchronization result</span></a> is the event itself.</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/udp..rkt)._udp-send-to-evt))"></a><span title="Provided from: racket/udp, racket | Package: base"><span class="RktSym"><a href="udp.html#%28def._%28%28lib._racket%2Fudp..rkt%29._udp-send-to-evt%29%29" class="RktValDef RktValLink" data-pltdoc="x">udp-send-to-evt</a></span></span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="RktVar">udp-socket</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></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></td><td valign="top"><span class="RktVar">bstr</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">start-pos</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">end-pos</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="sync.html#%28def._%28%28quote._~23~25kernel%29._evt~3f%29%29" class="RktValLink" data-pltdoc="x">evt?</a></span></td></tr></table></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">udp-socket</span><span class="hspace"> </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></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">&nbs
|
||
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state when <span class="RktSym"><a href="udp.html#%28def._%28%28lib._racket%2Fudp..rkt%29._udp-send-to%29%29" class="RktValLink" data-pltdoc="x">udp-send-to</a></span> on <span class="RktVar">udp-socket</span> would
|
||
|
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block. Otherwise, if the event is chosen in a synchronization, data is
|
||
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sent as for <span class="RktPn">(</span><span class="RktSym"><a href="udp.html#%28def._%28%28lib._racket%2Fudp..rkt%29._udp-send-to%29%29" class="RktValLink" data-pltdoc="x">udp-send-to</a></span><span class="stt"> </span><span class="RktVar">udp-socket</span><span class="stt"> </span><span class="RktSym">hostname-address</span><span class="stt"> </span><span class="RktVar">port-no</span><span class="stt"> </span><span class="RktVar">bstr</span><span class="stt"> </span><span class="RktVar">start-pos</span><span class="stt"> </span><span class="RktVar">end-pos</span><span class="RktPn">)</span>, and the synchronization result is
|
||
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<a href="https://download.racket-lang.org/releases/8.6/doc/local-redirect/index.html?doc=guide&rel=void_undefined.html&version=8.6" class="RktModLink Sq" data-pltdoc="x"><span class="nobreak"><span class="RktRes">#<void></span></span></a>. (No bytes are sent if the event is not chosen.)</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/udp..rkt)._udp-send-evt))"></a><span title="Provided from: racket/udp, racket | Package: base"><span class="RktSym"><a href="udp.html#%28def._%28%28lib._racket%2Fudp..rkt%29._udp-send-evt%29%29" class="RktValDef RktValLink" data-pltdoc="x">udp-send-evt</a></span></span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="RktVar">udp-socket</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">bstr</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">start-pos</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">end-pos</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="sync.html#%28def._%28%28quote._~23~25kernel%29._evt~3f%29%29" class="RktValLink" data-pltdoc="x">evt?</a></span></td></tr></table></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">udp-socket</span><span class="hspace"> </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></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">bstr</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="bytestrings.html#%28def._%28%28quote._~23~25kernel%29._bytes~3f%29%29" class="RktValLink" data-pltdoc="x">bytes?</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">start-pos</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">0</span></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">end-pos</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=
|
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|
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when <span class="RktSym"><a href="udp.html#%28def._%28%28lib._racket%2Fudp..rkt%29._udp-send%29%29" class="RktValLink" data-pltdoc="x">udp-send</a></span> on <span class="RktVar">udp-socket</span> would
|
||
|
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not block. Otherwise, if the event is chosen in a synchronization, data is
|
||
|
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sent as for <span class="RktPn">(</span><span class="RktSym"><a href="udp.html#%28def._%28%28lib._racket%2Fudp..rkt%29._udp-send-to%29%29" class="RktValLink" data-pltdoc="x">udp-send-to</a></span><span class="stt"> </span><span class="RktVar">udp-socket</span><span class="stt"> </span><span class="RktVar">bstr</span><span class="stt"> </span><span class="RktVar">start-pos</span><span class="stt"> </span><span class="RktVar">end-pos</span><span class="RktPn">)</span>,
|
||
|
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and the <a href="sync.html#%28tech._synchronization._result%29" class="techoutside" data-pltdoc="x"><span class="techinside">synchronization result</span></a> is <a href="https://download.racket-lang.org/releases/8.6/doc/local-redirect/index.html?doc=guide&rel=void_undefined.html&version=8.6" class="RktModLink Sq" data-pltdoc="x"><span class="nobreak"><span class="RktRes">#<void></span></span></a>. (No bytes are sent if
|
||
|
|
the event is not chosen.) If <span class="RktVar">udp-socket</span> is closed or
|
||
|
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unconnected, 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 during a synchronization
|
||
|
|
attempt.</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/udp..rkt)._udp-receive!-evt))"></a><span title="Provided from: racket/udp, racket | Package: base"><span class="RktSym"><a href="udp.html#%28def._%28%28lib._racket%2Fudp..rkt%29._udp-receive%21-evt%29%29" class="RktValDef RktValLink" data-pltdoc="x">udp-receive!-evt</a></span></span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="RktVar">udp-socket</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">bstr</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">start-pos</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">end-pos</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="sync.html#%28def._%28%28quote._~23~25kernel%29._evt~3f%29%29" class="RktValLink" data-pltdoc="x">evt?</a></span></td></tr></table></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">udp-socket</span><span class="hspace"> </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></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">bstr</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._and%2Fc%29%29" class="RktValLink" data-pltdoc="x">and/c</a></span><span class="hspace"> </span><span class="RktSym"><a href="bytestrings.html#%28def._%28%28quote._~23~25kernel%29._bytes~3f%29%29" class="RktValLink" data-pltdoc="x">bytes?</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="booleans.html#%28def._%28%28quote._~23~25kernel%29._not%29%29" class="RktValLink" data-pltdoc="x">not</a></span><span class="hspace"> </span><span class="RktSym"><a href="booleans.html#%28def._%28%28quote._~23~25kernel%29._immutable~3f%29%29" class="RktValLink" data-pltdoc="x">immutable?</a></span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">start-pos</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-nonne
|
||
|
|
when <span class="RktSym">udp-receive</span> on <span class="RktVar">udp-socket</span> would not
|
||
|
|
block. Otherwise, if the event is chosen in a synchronization, data is
|
||
|
|
received into <span class="RktVar">bstr</span> as for <span class="RktPn">(</span><span class="RktSym"><a href="udp.html#%28def._%28%28lib._racket%2Fudp..rkt%29._udp-receive%21%29%29" class="RktValLink" data-pltdoc="x">udp-receive!</a></span><span class="stt"> </span><span class="RktVar">udp-socket</span><span class="stt"> </span><span class="RktSym"><a href="bytestrings.html#%28def._%28%28quote._~23~25kernel%29._bytes%29%29" class="RktValLink" data-pltdoc="x">bytes</a></span><span class="stt"> </span><span class="RktVar">start-pos</span><span class="stt"> </span><span class="RktVar">end-pos</span><span class="RktPn">)</span>, and 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
|
||
|
|
three values, corresponding to the three results from
|
||
|
|
<span class="RktSym"><a href="udp.html#%28def._%28%28lib._racket%2Fudp..rkt%29._udp-receive%21%29%29" class="RktValLink" data-pltdoc="x">udp-receive!</a></span>. (No bytes are received and the <span class="RktVar">bstr</span>
|
||
|
|
content is not modified if the event is not chosen.)</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/udp..rkt)._udp-addresses))"></a><span title="Provided from: racket/udp, racket | Package: base"><span class="RktSym"><a href="udp.html#%28def._%28%28lib._racket%2Fudp..rkt%29._udp-addresses%29%29" class="RktValDef RktValLink" data-pltdoc="x">udp-addresses</a></span></span><span class="hspace"> </span><span class="RktVar">udp-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._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="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">udp-port</span><span class="hspace"> </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></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
|
||
|
|
default). The first string is the Internet address for the local
|
||
|
|
machine a viewed by the given <a href="udp.html#%28tech._udp._socket%29" class="techoutside" data-pltdoc="x"><span class="techinside">UDP socket</span></a>’s connection. (For most
|
||
|
|
machines, the answer corresponds to the current machine’s only
|
||
|
|
Internet address, but when a machine serves multiple addresses, the
|
||
|
|
result is connection-specific.) The second string is the Internet
|
||
|
|
address for the other end of the connection.</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
|
||
|
|
or <span class="RktVal">0</span> if the socket is unbound, 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> if the socket is unconnected.</p><p>If the given port 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><table cellspacing="0" cellpadding="0" class="together"><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/udp..rkt)._udp-set-ttl!))"></a><span title="Provided from: racket/udp, racket | Package: base"><span class="RktSym"><a href="udp.html#%28def._%28%28lib._racket%2Fudp..rkt%29._udp-set-ttl%21%29%29" class="RktValDef RktValLink" data-pltdoc="x">udp-set-ttl!</a></span></span><span class="hspace"> </span><span class="RktVar">udp-socket</span><span class="hspace"> </span><span class="RktVar">ttl</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">udp-socket</span><span class="hspace"> </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></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">ttl</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="bytestrings.html#%28def._%28%28quote._~23~25kernel%29._byte~3f%29%29" class="RktValLink" data-pltdoc="x">byte?</a></span></td></tr></table></td></tr><tr><td><table cellspacing="0" cellpadding="0" class="together"><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/udp..rkt)._udp-ttl))"></a><span title="Provided from: racket/udp, racket | Package: base"><span class="RktSym"><a href="udp.html#%28def._%28%28lib._racket%2Fudp..rkt%29._udp-ttl%29%29" class="RktValDef RktValLink" data-pltdoc="x">udp-ttl</a></span></span><span class="hspace"> </span><span class="RktVar">udp-socket</span><span class="RktPn">)</span><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktSym"><a href="bytestrings.html#%28def._%28%28quote._~23~25kernel%29._byte~3f%29%29" class="RktValLink" data-pltdoc="x">byte?</a></span></p></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">udp-socket</span><span class="hspace"> </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></td></tr></table></td></tr></table></blockquote></div><div class="SIntrapara"><blockquote class="refpara"><blockquote class="refcolumn"><blockquote class="refcontent"><p>Time-to-live settings correspond to the
|
||
|
|
<a name="(idx._(gentag._381._(lib._scribblings/reference/reference..scrbl)))"></a><span class="stt">IP_TTL</span> setting of the socket.</p></blockquote></blockquote></blockquote></div></p><p>Sets or retrieves the current time-to-live setting of
|
||
|
|
<span class="RktVar">udp-socket</span>.</p><p class="SHistory">Added in version 7.5.0.5 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><table cellspacing="0" cellpadding="0" class="together"><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/udp..rkt)._udp-multicast-join-group!))"></a><span title="Provided from: racket/udp, racket | Package: base"><span class="RktSym"><a href="udp.html#%28def._%28%28lib._racket%2Fudp..rkt%29._udp-multicast-join-group%21%29%29" class="RktValDef RktValLink" data-pltdoc="x">udp-multicast-join-group!</a></span></span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="RktVar">udp-socket</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">multicast-addr</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="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="void.html#%28def._%28%28quote._~23~25kernel%29._void~3f%29%29" class="RktValLink" data-pltdoc="x">void?</a></span></td></tr></table></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">udp-socket</span><span class="hspace"> </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></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">multicast-addr</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">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></td></tr></table></td></tr><tr><td><table cellspacing="0" cellpadding="0" class="together"><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/udp..rkt)._udp-multicast-leave-group!))"></a><span title="Provided from: racket/udp, racket | Package: base"><span class="RktSym"><a href="udp.html#%28def._%28%28lib._racket%2Fudp..rkt%29._udp-multicast-leave-group%21%29%29" class="RktVa
|
||
|
|
IP address; for example, <span class="RktVal">"224.0.0.251"</span> is the appropriate
|
||
|
|
address for the mDNS protocol. The <span class="RktVar">hostname</span> argument selects the
|
||
|
|
interface that the socket uses to receive (not send) multicast datagrams;
|
||
|
|
if <span class="RktVar">hostname</span> is <span class="RktVal">#f</span> or <span class="RktVal">"0.0.0.0"</span>, the kernel
|
||
|
|
selects an interface automatically.</p><p>Leaving a group requires the same <span class="RktVar">multicast-addr</span> and
|
||
|
|
<span class="RktVar">hostname</span> arguments that were used to join the group.</p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><table cellspacing="0" cellpadding="0" class="together"><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/udp..rkt)._udp-multicast-interface))"></a><span title="Provided from: racket/udp, racket | Package: base"><span class="RktSym"><a href="udp.html#%28def._%28%28lib._racket%2Fudp..rkt%29._udp-multicast-interface%29%29" class="RktValDef RktValLink" data-pltdoc="x">udp-multicast-interface</a></span></span><span class="hspace"> </span><span class="RktVar">udp-socket</span><span class="RktPn">)</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></p></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">udp-socket</span><span class="hspace"> </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></td></tr></table></td></tr><tr><td><table cellspacing="0" cellpadding="0" class="together"><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/udp..rkt)._udp-multicast-set-interface!))"></a><span title="Provided from: racket/udp, racket | Package: base"><span class="RktSym"><a href="udp.html#%28def._%28%28lib._racket%2Fudp..rkt%29._udp-multicast-set-interface%21%29%29" class="RktValDef RktValLink" data-pltdoc="x">udp-multicast-set-interface!</a></span></span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="RktVar">udp-socket</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="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="void.html#%28def._%28%28quote._~23~25kernel%29._void~3f%29%29" class="RktValLink" data-pltdoc="x">void?</a></span></td></tr></table></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">udp-socket</span><span class="hspace"> </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></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></td></tr></table></td></tr></table></blockquote></div><div class="SIntrapara">Retrieves or sets the interface that <sp
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send (not receive) multicast datagrams. If the result or <span class="RktVar">hostname</span> is either
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<span class="RktVal">#f</span> or <span class="RktVal">"0.0.0.0"</span>, the kernel automatically selects an
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interface when a multicast datagram is sent.</div></p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><table cellspacing="0" cellpadding="0" class="together"><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/udp..rkt)._udp-multicast-set-loopback!))"></a><span title="Provided from: racket/udp, racket | Package: base"><span class="RktSym"><a href="udp.html#%28def._%28%28lib._racket%2Fudp..rkt%29._udp-multicast-set-loopback%21%29%29" class="RktValDef RktValLink" data-pltdoc="x">udp-multicast-set-loopback!</a></span></span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="RktVar">udp-socket</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">loopback?</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="void.html#%28def._%28%28quote._~23~25kernel%29._void~3f%29%29" class="RktValLink" data-pltdoc="x">void?</a></span></td></tr></table></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">udp-socket</span><span class="hspace"> </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></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">loopback?</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></td></tr><tr><td><table cellspacing="0" cellpadding="0" class="together"><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/udp..rkt)._udp-multicast-loopback~3f))"></a><span title="Provided from: racket/udp, racket | Package: base"><span class="RktSym"><a href="udp.html#%28def._%28%28lib._racket%2Fudp..rkt%29._udp-multicast-loopback~3f%29%29" class="RktValDef RktValLink" data-pltdoc="x">udp-multicast-loopback?</a></span></span><span class="hspace"> </span><span class="RktVar">udp-socket</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">udp-socket</span><span class="hspace"> </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></td></tr></table></td></tr></table></blockquote></div><div class="SIntrapara"><blockquote class="refpara"><blockquote class="refcolumn"><blockquote class="refcontent"><p>Loopback settings correspond to the
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<a name="(idx._(gentag._382._(lib._scribblings/reference/reference..scrbl)))"></a><span class="stt">IP_MULTICAST_LOOP</span> setting of the socket.</p></blockquote></blockquote></blockquote></div></p><p>Sets or checks whether <span class="RktVar">udp-socket</span> receives its own multicast
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datagrams: a <span class="RktVal">#t</span> result or a true value for <span class="RktVar">loopback?</span>
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indicates that self-receipt is enabled, and <span class="RktVal">#f</span> indicates that
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self-receipt is disabled.</p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><table cellspacing="0" cellpadding="0" class="together"><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/udp..rkt)._udp-multicast-set-ttl!))"></a><span title="Provided from: racket/udp, racket | Package: base"><span class="RktSym"><a href="udp.html#%28def._%28%28lib._racket%2Fudp..rkt%29._udp-multicast-set-ttl%21%29%29" class="RktValDef RktValLink" data-pltdoc="x">udp-multicast-set-ttl!</a></span></span><span class="hspace"> </span><span class="RktVar">udp-socket</span><span class="hspace"> </span><span class="RktVar">ttl</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">udp-socket</span><span class="hspace"> </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></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">ttl</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="bytestrings.html#%28def._%28%28quote._~23~25kernel%29._byte~3f%29%29" class="RktValLink" data-pltdoc="x">byte?</a></span></td></tr></table></td></tr><tr><td><table cellspacing="0" cellpadding="0" class="together"><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/udp..rkt)._udp-multicast-ttl))"></a><span title="Provided from: racket/udp, racket | Package: base"><span class="RktSym"><a href="udp.html#%28def._%28%28lib._racket%2Fudp..rkt%29._udp-multicast-ttl%29%29" class="RktValDef RktValLink" data-pltdoc="x">udp-multicast-ttl</a></span></span><span class="hspace"> </span><span class="RktVar">udp-socket</span><span class="RktPn">)</span><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktSym"><a href="bytestrings.html#%28def._%28%28quote._~23~25kernel%29._byte~3f%29%29" class="RktValLink" data-pltdoc="x">byte?</a></span></p></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">udp-socket</span><span class="hspace"> </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></td></tr></table></td></tr></table></blockquote></div><div class="SIntrapara"><blockquote class="refpara"><blockquote class="refcolumn"><blockquote class="refcontent"><p>Time-to-live settings correspond to the
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<a name="(idx._(gentag._383._(lib._scribblings/reference/reference..scrbl)))"></a><span class="stt">IP_MULTICAST_TTL</span> setting of the socket.</p></blockquote></blockquote></blockquote></div></p><p>Sets or retrieves the current time-to-live setting of
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<span class="RktVar">udp-socket</span>.</p><p>The time-to-live setting should almost always be 1, and it is
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important that this number is as low as possible. In fact, these
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functions seldom should be used at all. See the documentation for your
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platform’s IP stack.</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="tcp.html" title="backward to "15.3.1 TCP"" data-pltdoc="x">← prev</a> <a href="networking.html" title="up to "15.3 Networking"" data-pltdoc="x">up</a> <a href="subprocess.html" title="forward to "15.4 Processes"" data-pltdoc="x">next →</a></span> </div></div></div><div id="contextindicator"> </div></body></html>
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