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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"><html><head><meta name="generator" content="HTML Tidy, see www.w3.org"><meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1"><link type="text/css" rel="stylesheet" href="style.css"><!-- Generated by The Open Group's rhtm tool v1.2.1 --><!-- Copyright (c) 2001-2003 The Open Group, All Rights Reserved --><title>inet_ntop</title></head><body bgcolor="white"><script type="text/javascript" language="JavaScript" src="../jscript/codes.js"></script><basefont size="3"> <a name="inet_ntop"></a> <a name="tag_03_279"></a><!-- inet_ntop --> <!--header start--><center><font size="2">The Open Group Base Specifications Issue 6<br>IEEE Std 1003.1, 2003 Edition<br>Copyright © 2001-2003 The IEEE and The Open Group, All Rights reserved.</font></center><!--header end--><hr size="2" noshade><h4><a name="tag_03_279_01"></a>NAME</h4><blockquote>inet_ntop, inet_pton - convert IPv4 and IPv6 addresses between binary and text form</blockquote><h4><a name="tag_03_279_02"></a>SYNOPSIS</h4><blockquote class="synopsis"><p><code><tt>#include <<a href="../basedefs/arpa/inet.h.html">arpa/inet.h</a>><br><br> const char *inet_ntop(int</tt> <i>af</i><tt>, const void *restrict</tt> <i>src</i><tt>,<br> char *restrict</tt> <i>dst</i><tt>, socklen_t</tt> <i>size</i><tt>);<br> int inet_pton(int</tt> <i>af</i><tt>, const char *restrict</tt> <i>src</i><tt>, void *restrict</tt> <i>dst</i><tt>);<br></tt></code></p></blockquote><h4><a name="tag_03_279_03"></a>DESCRIPTION</h4><blockquote><p>The <i>inet_ntop</i>() function shall convert a numeric address into a text string suitable for presentation. The <i>af</i>argument shall specify the family of the address. This can be AF_INET <sup>[<a href="javascript:open_code('IP6')">IP6</a>]</sup><img src="../images/opt-start.gif" alt="[Option Start]" border="0"> or AF_INET6. <img src="../images/opt-end.gif" alt="[Option End]" border="0"> The <i>src</i> argument points to a buffer holding an IPv4 address if the <i>af</i> argument is AF_INET,<sup>[<a href="javascript:open_code('IP6')">IP6</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0"> or an IPv6 address if the <i>af</i> argument is AF_INET6; <img src="../images/opt-end.gif" alt="[Option End]" border="0"> theaddress must be in network byte order. The <i>dst</i> argument points to a buffer where the function stores the resulting textstring; it shall not be NULL. The <i>size</i> argument specifies the size of this buffer, which shall be large enough to hold thetext string (INET_ADDRSTRLEN characters for IPv4, <sup>[<a href="javascript:open_code('IP6')">IP6</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0"> INET6_ADDRSTRLEN characters for IPv6). <img src="../images/opt-end.gif" alt="[Option End]" border="0"></p><p>The <i>inet_pton</i>() function shall convert an address in its standard text presentation form into its numeric binary form.The <i>af</i> argument shall specify the family of the address. The AF_INET <sup>[<a href="javascript:open_code('IP6')">IP6</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0"> and AF_INET6<img src="../images/opt-end.gif" alt="[Option End]" border="0"> address families shall be supported. The <i>src</i> argument pointsto the string being passed in. The <i>dst</i> argument points to a buffer into which the function stores the numeric address; thisshall be large enough to hold the numeric address (32 bits for AF_INET, <sup>[<a href="javascript:open_code('IP6')">IP6</a>]</sup><img src="../images/opt-start.gif" alt="[Option Start]" border="0"> 128 bits for AF_INET6). <img src="../images/opt-end.gif"alt="[Option End]" border="0"></p><p>If the <i>af</i> argument of <i>inet_pton</i>() is AF_INET, the <i>src</i> string shall be in the standard IPv4 dotted-decimalform:</p><pre><tt>ddd.ddd.ddd.ddd</tt></pre><p>where <tt>"ddd"</tt> is a one to three digit decimal number between 0 and 255 (see <a href="inet_addr.html"><i>inet_addr</i>()</a> ). The <i>inet_pton</i>() function does not accept other formats (such as the octalnumbers, hexadecimal numbers, and fewer than four numbers that <a href="../functions/inet_addr.html"><i>inet_addr</i>()</a>accepts).</p><p><sup>[<a href="javascript:open_code('IP6')">IP6</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0">If the <i>af</i> argument of <i>inet_pton</i>() is AF_INET6, the <i>src</i> string shall be in one of the following standard IPv6text forms:</p><ol><li><p>The preferred form is <tt>"x:x:x:x:x:x:x:x"</tt> , where the <tt>'x'</tt> s are the hexadecimal values of the eight 16-bitpieces of the address. Leading zeros in individual fields can be omitted, but there shall be at least one numeral in everyfield.</p></li><li><p>A string of contiguous zero fields in the preferred form can be shown as <tt>"::"</tt> . The <tt>"::"</tt> can only appear oncein an address. Unspecified addresses ( <tt>"0:0:0:0:0:0:0:0"</tt> ) may be represented simply as <tt>"::"</tt> .</p></li><li><p>A third form that is sometimes more convenient when dealing with a mixed environment of IPv4 and IPv6 nodes is<tt>"x:x:x:x:x:x:d.d.d.d"</tt> , where the <tt>'x'</tt> s are the hexadecimal values of the six high-order 16-bit pieces of theaddress, and the <tt>'d'</tt> s are the decimal values of the four low-order 8-bit pieces of the address (standard IPv4representation).</p></li></ol><basefont size="2"> <dl><dt><b>Note:</b></dt><dd>A more extensive description of the standard representations of IPv6 addresses can be found in RFC 2373.</dd></dl><basefont size="3"> <img src="../images/opt-end.gif" alt="[Option End]" border="0"></blockquote><h4><a name="tag_03_279_04"></a>RETURN VALUE</h4><blockquote><p>The <i>inet_ntop</i>() function shall return a pointer to the buffer containing the text string if the conversion succeeds, andNULL otherwise, and set <i>errno</i> to indicate the error.</p><p>The <i>inet_pton</i>() function shall return 1 if the conversion succeeds, with the address pointed to by <i>dst</i> in networkbyte order. It shall return 0 if the input is not a valid IPv4 dotted-decimal string <sup>[<a href="javascript:open_code('IP6')">IP6</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0"> or a validIPv6 address string, <img src="../images/opt-end.gif" alt="[Option End]" border="0"> or -1 with <i>errno</i> set to [EAFNOSUPPORT]if the <i>af</i> argument is unknown.</p></blockquote><h4><a name="tag_03_279_05"></a>ERRORS</h4><blockquote><p>The <i>inet_ntop</i>() and <i>inet_pton</i>() functions shall fail if:</p><dl compact><dt>[EAFNOSUPPORT]</dt><dd><br>The <i>af</i> argument is invalid.</dd><dt>[ENOSPC]</dt><dd>The size of the <i>inet_ntop</i>() result buffer is inadequate.</dd></dl></blockquote><hr><div class="box"><em>The following sections are informative.</em></div><h4><a name="tag_03_279_06"></a>EXAMPLES</h4><blockquote><p>None.</p></blockquote><h4><a name="tag_03_279_07"></a>APPLICATION USAGE</h4><blockquote><p>None.</p></blockquote><h4><a name="tag_03_279_08"></a>RATIONALE</h4><blockquote><p>None.</p></blockquote><h4><a name="tag_03_279_09"></a>FUTURE DIRECTIONS</h4><blockquote><p>None.</p></blockquote><h4><a name="tag_03_279_10"></a>SEE ALSO</h4><blockquote><p>The Base Definitions volume of IEEE Std 1003.1-2001, <a href="../basedefs/arpa/inet.h.html"><i><arpa/inet.h></i></a></p></blockquote><h4><a name="tag_03_279_11"></a>CHANGE HISTORY</h4><blockquote><p>First released in Issue 6. Derived from the XNS, Issue 5.2 specification.</p><p>IPv6 extensions are marked.</p><p>The <b>restrict</b> keyword is added to the <i>inet_ntop</i>() and <i>inet_pton</i>() prototypes for alignment with theISO/IEC 9899:1999 standard.</p><p>IEEE Std 1003.1-2001/Cor 1-2002, item XSH/TC1/D6/29 is applied, adding ``the address must be in network byte order''to the end of the fourth sentence of the first paragraph in the DESCRIPTION.</p></blockquote><div class="box"><em>End of informative text.</em></div><hr><hr size="2" noshade><center><font size="2"><!--footer start-->UNIX ® is a registered Trademark of The Open Group.<br>POSIX ® is a registered Trademark of The IEEE.<br>[ <a href="../mindex.html">Main Index</a> | <a href="../basedefs/contents.html">XBD</a> | <a href="../utilities/contents.html">XCU</a> | <a href="../functions/contents.html">XSH</a> | <a href="../xrat/contents.html">XRAT</a>]</font></center><!--footer end--><hr size="2" noshade></body></html>⌨️ 快捷键说明
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