1 .\" Hey Emacs! This file is -*- nroff -*- source.
3 .\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
4 .\" and Copyright (c) 2008 Linux Foundation, written by Michael Kerrisk
5 .\" <mtk.manpages@gmail.com>
7 .\" Permission is granted to make and distribute verbatim copies of this
8 .\" manual provided the copyright notice and this permission notice are
9 .\" preserved on all copies.
11 .\" Permission is granted to copy and distribute modified versions of this
12 .\" manual under the conditions for verbatim copying, provided that the
13 .\" entire resulting derived work is distributed under the terms of a
14 .\" permission notice identical to this one.
16 .\" Since the Linux kernel and libraries are constantly changing, this
17 .\" manual page may be incorrect or out-of-date. The author(s) assume no
18 .\" responsibility for errors or omissions, or for damages resulting from
19 .\" the use of the information contained herein. The author(s) may not
20 .\" have taken the same level of care in the production of this manual,
21 .\" which is licensed free of charge, as they might when working
24 .\" Formatted or processed versions of this manual, if unaccompanied by
25 .\" the source, must acknowledge the copyright and authors of this work.
27 .\" References consulted:
28 .\" Linux libc source code
29 .\" Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
31 .\" libc.info (from glibc distribution)
32 .\" Modified Sat Jul 24 19:12:00 1993 by Rik Faith <faith@cs.unc.edu>
33 .\" Modified Sun Sep 3 20:29:36 1995 by Jim Van Zandt <jrv@vanzandt.mv.com>
34 .\" Changed network into host byte order (for inet_network),
35 .\" Andreas Jaeger <aj@arthur.rhein-neckar.de>, 980130.
37 .\" Describe the various address forms supported by inet_aton().
38 .\" Clarify discussion of inet_lnaof(), inet_netof(), and inet_makeaddr().
39 .\" Add discussion of Classful Addressing, noting that it is obsolete.
40 .\" Added an EXAMPLE program.
42 .\" Japanese Version Copyright (c) 1998 Ueyama Rui
43 .\" all rights reserved.
44 .\" Translated 1998-05-23, Ueyama Rui <rui@linux.or.jp>
45 .\" Updated & Modefied 1999-02-26, Shouichi Saito
46 .\" Updated 1999-12-26, Kentaro Shirakata <argrath@ub32.org>
47 .\" Updated 2005-10-04, Kentaro Shirakata <argrath@ub32.org>
48 .\" Updated 2007-05-01, Akihiro MOTOKI <amotoki@dd.iij4u.or.jp>, LDP v2.46
49 .\" Updated 2008-08-13, Akihiro MOTOKI, LDP v3.05
51 .\"WORD: numbers-and-dots notation ¿ôÃͤȥɥåȤˤè¤ëµË¡
52 .\"WORD: dotted-decimal notation ¥É¥Ã¥È¶èÀÚ¤ê¤Î 10 ¿Ê¿ôµË¡
53 .\"WORD: feature test macro µ¡Ç½¸¡ºº¥Þ¥¯¥í
55 .TH INET 3 2008-06-19 "GNU" "Linux Programmer's Manual"
57 inet_aton, inet_addr, inet_network, inet_ntoa, inet_makeaddr, inet_lnaof,
58 inet_netof \- ¥¤¥ó¥¿¡¼¥Í¥Ã¥È¥¢¥É¥ì¥¹Áàºî¥ë¡¼¥Á¥ó
61 .B #include <sys/socket.h>
62 .B #include <netinet/in.h>
63 .B #include <arpa/inet.h>
65 .BI "int inet_aton(const char *" cp ", struct in_addr *" inp );
67 .BI "in_addr_t inet_addr(const char *" cp );
69 .BI "in_addr_t inet_network(const char *" cp );
71 .BI "char *inet_ntoa(struct in_addr " in );
73 .BI "struct in_addr inet_makeaddr(int " net ", int " host );
75 .BI "in_addr_t inet_lnaof(struct in_addr " in );
77 .BI "in_addr_t inet_netof(struct in_addr " in );
81 glibc ¸þ¤±¤Îµ¡Ç½¸¡ºº¥Þ¥¯¥í¤ÎÍ×·ï
82 .RB ( feature_test_macros (7)
88 _BSD_SOURCE || _SVID_SOURCE
91 ¤Ï¡¢¥¤¥ó¥¿¡¼¥Í¥Ã¥È¥Û¥¹¥È¤Î¥¢¥É¥ì¥¹ \fIcp\fP ¤ò¡¢
92 IPv4 ¤Î¿ôÃͤȥɥåȤˤè¤ëɽµ¤«¤é (¥Í¥Ã¥È¥ï¡¼¥¯¥Ð¥¤¥È¥ª¡¼¥À¤Î) ¥Ð¥¤¥Ê¥êÃͤØ
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94 ¥¢¥É¥ì¥¹¤¬Í¸ú¤Ê¾ì¹ç 0 °Ê³°¤òÊÖ¤·¡¢¤½¤¦¤Ç¤Ê¤¤¾ì¹ç¤Ï 0 ¤òÊÖ¤¹¡£
96 ¤ÇÅϤ¹¥¢¥É¥ì¥¹¤È¤·¤Æ¡¢°Ê²¼¤Î·Á¼°¤òÍѤ¤¤ë¤³¤È¤¬¤Ç¤¤ë¡£
99 4 ¤Ä¤Î¿ô»ú¤Î¤½¤ì¤¾¤ì¤Ï¥¢¥É¥ì¥¹¤Î³Æ¥Ð¥¤¥È¤ò¼¨¤¹¡£
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108 ¤Ï 16 ¥Ó¥Ã¥ÈÃͤȲò¼á¤µ¤ì¡¢¥Ð¥¤¥Ê¥ê¥¢¥É¥ì¥¹¤Î±¦Â¦¤Î 2 ¥Ð¥¤¥È¤òɽ¤¹¡£
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117 ¤³¤Îɽµ¤Ï¡¢(²áµî¤Î¤â¤Î¤È¤Ê¤Ã¤¿) ¥¯¥é¥¹ C ¥Í¥Ã¥È¥ï¡¼¥¯¥¢¥É¥ì¥¹¤ò
118 »ØÄꤹ¤ë¤Î¤ËŬ¤·¤Æ¤¤¤ë¡£
123 ¤Ï 32 ¥Ó¥Ã¥ÈÃͤȲò¼á¤µ¤ì¡¢¥Ð¥¤¥È¤ÎºÆÇÛÃ֤ϹԤï¤ì¤º¡¢
124 ¤½¤Î¤Þ¤Þ¥Ð¥¤¥Ê¥ê¥¢¥É¥ì¥¹¤È¤·¤Æ³ÊǼ¤µ¤ì¤ë¡£
126 ¾åµ¤ÎÁ´¤Æ¤Î·Á¼°¤Ç¡¢¥É¥Ã¥È¶èÀÚ¤ê¤Î¥¢¥É¥ì¥¹¤Î³ÆÍ×ÁǤϡ¢10 ¿Ê¿ô¡¢
132 ¤òÉÕ¤±¤ë) ¤Ç»ØÄê¤Ç¤¤ë¡£
133 ¤³¤ì¤é¤Î·Á¼°¤Î¥¢¥É¥ì¥¹¤ò¤Þ¤È¤á¤Æ
134 .I "IPv4 ¤Î¿ôÃͤȥɥåȤˤè¤ëɽµ (IPv4 numbers-and-dots notation)"
136 ¤Þ¤¿¡¢10 ¿Ê¿ô 4 ¤Ä¤À¤±¤ò»È¤Ã¤¿·Á¼°¤ò
137 .I "IPv4 ¤Î¥É¥Ã¥È¶èÀÚ¤ê¤Î 10 ¿Ê¿ôɽµ (IPv4 dotted-decimal notation)"
139 .RI ( "IPv4 ¤Î¥É¥Ã¥È¶èÀÚ¤ê 4 ʬ³äɽµ (IPv4 dotted-decimal notation)"
143 ´Ø¿ô¤Ï¡¢¥¤¥ó¥¿¡¼¥Í¥Ã¥È¥Û¥¹¥È¤Î¥¢¥É¥ì¥¹ \fIcp\fP ¤ò¡¢
144 IPv4 ¤Î¿ôÃͤȥɥåȤˤè¤ëɽµ¤«¤é¥Í¥Ã¥È¥ï¡¼¥¯¥Ð¥¤¥È¥ª¡¼¥À¤Ç¤Î
145 ¥Ð¥¤¥Ê¥êÃͤØÊÑ´¹¤·¤ÆÊÖ¤¹¡£
148 (ÉáÄÌ¤Ï \-1) ¤òÊÖ¤¹¡£
149 \-1 ¤Ï͸ú¤Ê¥¢¥É¥ì¥¹ (255.255.255.255) ¤Ê¤Î¤Ç¡¢¤³¤Î´Ø¿ô¤ò»È¤¦¤È
150 ÌäÂê¤Ë¤Ê¤ë¤«¤â¤·¤ì¤Ê¤¤¡£
151 ¤³¤Î´Ø¿ô¤ò»È¤¦¤Î¤ÏÈò¤±¡¢Âå¤ï¤ê¤Ë
156 ¤³¤ì¤é¤Î´Ø¿ô¤ÎÊý¤¬¡¢¥¨¥é¡¼¤ÎÄÌÃΤ¬¤è¤ê¤¤ì¤¤¤ÊÊýË¡¤Ç¹Ô¤ï¤ì¤ë¡£
160 IPv4 ¤Î¿ôÃͤȥɥåȤˤè¤ëɽµ¤Îʸ»úÎó \fIcp\fP ¤ò¡¢
161 ¥¤¥ó¥¿¡¼¥Í¥Ã¥È¥¢¥É¥ì¥¹¤È¤·¤Æ¤Î»ÈÍѤËŬ¤·¤¿
162 ¥Û¥¹¥È¥Ð¥¤¥È¥ª¡¼¥À¤Î¿ôÃͤËÊÑ´¹¤¹¤ë¡£
163 À®¸ù¤¹¤ë¤È¡¢ÊÑ´¹¤µ¤ì¤¿¥¢¥É¥ì¥¹¤òÊÖ¤¹¡£
164 ÆþÎϤ¬ÉÔÀµ¤Ê¾ì¹ç¤Ï \-1 ¤òÊÖ¤¹¡£
167 ´Ø¿ô¤Ï¡¢¥Í¥Ã¥È¥ï¡¼¥¯¥Ð¥¤¥È¥ª¡¼¥À¤ÇÅϤµ¤ì¤¿¥¤¥ó¥¿¡¼¥Í¥Ã¥È¥Û¥¹¥È¥¢¥É¥ì¥¹
168 \fIin\fP ¤ò¡¢ IPv4 ¤Î¥É¥Ã¥È¶èÀÚ¤ê¤Î 10 ¿Ê¿ôɽµ¤Îʸ»úÎó¤ËÊÑ´¹¤¹¤ë¡£
169 ʸ»úÎó¤ÏÀÅŪ¤Ë³äÅö¤Æ¤é¤ì¤¿¥Ð¥Ã¥Õ¥¡¤Ë³ÊǼ¤µ¤ì¤ÆÊÖ¤µ¤ì¤ë¤Î¤Ç¡¢
170 ¤³¤Î¸å¤Ç¤³¤Î´Ø¿ô¤òºÆÅٸƤӽФ¹¤Èʸ»úÎó¤Ï¾å½ñ¤¤µ¤ì¤ë¡£
173 ´Ø¿ô¤Ï¡¢¥¤¥ó¥¿¡¼¥Í¥Ã¥È¥¢¥É¥ì¥¹ \fIin\fP ¤Î¥í¡¼¥«¥ë¥Í¥Ã¥È¥ï¡¼¥¯Éôʬ¤òÊÖ¤¹¡£
174 ¤³¤ÎÊÖ¤êÃͤϥۥ¹¥È¥Ð¥¤¥È¥ª¡¼¥À¤Ç¤¢¤ë¡£
177 ´Ø¿ô¤Ï¡¢¥¤¥ó¥¿¡¼¥Í¥Ã¥È¥¢¥É¥ì¥¹ \fIin\fP ¤Î¥Í¥Ã¥È¥ï¡¼¥¯Éôʬ¤òÊÖ¤¹¡£
178 ¤³¤ÎÊÖ¤êÃͤϥۥ¹¥È¥Ð¥¤¥È¥ª¡¼¥À¤Ç¤¢¤ë¡£
186 ¥Í¥Ã¥È¥ï¡¼¥¯ÈÖ¹æ \fInet\fP ¤È¡¢¥í¡¼¥«¥ë¥¢¥É¥ì¥¹ \fIhost\fP ¤ò
187 ÁȤ߹ç¤ï¤»¤ÆÀ¸À®¤·¤¿¡¢¥¤¥ó¥¿¡¼¥Í¥Ã¥È¥Û¥¹¥È¥¢¥É¥ì¥¹¤ò
188 ¥Í¥Ã¥È¥ï¡¼¥¯¥Ð¥¤¥È¥ª¡¼¥À¤ÇÊÖ¤¹¡£
189 \fIhost\fP, \fInet\fP ¤Ï¤È¤â¤Ë¥Û¥¹¥È¥Ð¥¤¥È¥ª¡¼¥À¤Ç¤¢¤ë¡£
192 .BR inet_makeaddr (),
195 ¤Ç»ÈÍѤ¹¤ë¹½Â¤ÂÎ \fIin_addr\fP ¤Ï
197 ¤Ç¼¡¤Î¤è¤¦¤ËÄêµÁ¤µ¤ì¤Æ¤¤¤ë:
201 typedef uint32_t in_addr_t;
212 ¤Ï POSIX.1-2001 ¤Çµ¬Äꤵ¤ì¤Æ¤¤¤ë¡£
214 ¤Ï POSIX.1-2001 ¤Çµ¬Äꤵ¤ì¤Æ¤¤¤Ê¤¤¤¬¡¢¤Û¤È¤ó¤É¤Î¥·¥¹¥Æ¥à¤ÇÍøÍѲÄǽ¤Ç¤¢¤ë¡£
216 i386 ¤Ç¤Ï¥Û¥¹¥È¥Ð¥¤¥È¥ª¡¼¥À¤Ï Least Significant Byte (LSB) first
217 (¥ê¥È¥ë¥¨¥ó¥Ç¥£¥¢¥ó) ¤À¤¬¡¢
218 ¥¤¥ó¥¿¡¼¥Í¥Ã¥È¤Ç»È¤ï¤ì¤ë¥Í¥Ã¥È¥ï¡¼¥¯¥Ð¥¤¥È¥ª¡¼¥À¤Ï
219 Most Significant Byte (MSB) first (¥Ó¥Ã¥°¥¨¥ó¥Ç¥£¥¢¥ó)
220 ¤Ç¤¢¤ëÅÀ¤ËÃí°Õ¤¹¤ë¤³¤È¡£
225 ¤Ï²áµî¤Î̾»Ä¤Ç¤¢¤ê¡¢ÅϤµ¤ì¤¿¥¢¥É¥ì¥¹¤¬
226 .I "¥¯¥é¥¹¥Õ¥ë¡¦¥Í¥Ã¥È¥ï¡¼¥¯¥¢¥É¥ì¥¹ (classful network addresses)"
227 ¤Ç¤¢¤ë¤È²¾Äꤷ¤Æ½èÍý¤ò¹Ô¤¦¡£
228 ¥¯¥é¥¹¥Õ¥ë¡¦¥Í¥Ã¥È¥ï¡¼¥¯¥¢¥É¥ì¥¹¤Ç¤Ï¡¢°Ê²¼¤Ë¤¢¤ë¤è¤¦¤Ë¡¢
229 IPv4 ¥Í¥Ã¥È¥ï¡¼¥¯¥¢¥É¥ì¥¹¤ò¥Ð¥¤¥È¶³¦¤Ç¥Í¥Ã¥È¥ï¡¼¥¯Éô¤È¥Û¥¹¥ÈÉô¤Ëʬ³ä¤¹¤ë¡£
232 (¥Í¥Ã¥È¥ï¡¼¥¯¥Ð¥¤¥È¥ª¡¼¥À¤Î) ¥¢¥É¥ì¥¹¤ÎºÇ¾å°Ì¥Ó¥Ã¥È¤¬ 0 ¤Î¾ì¹ç¡¢
233 ¤³¤Î¥¢¥É¥ì¥¹¼ïÊ̤Ȥʤ롣¤³¤Î¥¢¥É¥ì¥¹¼ïÊ̤Ǥϡ¢
234 ºÇ¾å°Ì¥Ð¥¤¥È¤¬¥Í¥Ã¥È¥ï¡¼¥¯¥¢¥É¥ì¥¹¤òɽ¤·¡¢
235 »Ä¤ê¤Î 3 ¥Ð¥¤¥È¤¬¥Û¥¹¥È¥¢¥É¥ì¥¹¤òɽ¤¹¡£
238 (¥Í¥Ã¥È¥ï¡¼¥¯¥Ð¥¤¥È¥ª¡¼¥À¤Î) ¥¢¥É¥ì¥¹¤Î¾å°Ì¦ 2 ¥Ó¥Ã¥È¤¬¥Ð¥¤¥Ê¥êÃͤÇ
239 10 ¤Î¾ì¹ç¡¢¤³¤Î¥¢¥É¥ì¥¹¼ïÊ̤Ȥʤ롣¤³¤Î¥¢¥É¥ì¥¹¼ïÊ̤Ǥϡ¢
240 ¾å°Ì 2 ¥Ð¥¤¥È¤¬¥Í¥Ã¥È¥ï¡¼¥¯¥¢¥É¥ì¥¹¤òɽ¤·¡¢
241 »Ä¤ê¤Î 2 ¥Ð¥¤¥È¤¬¥Û¥¹¥È¥¢¥É¥ì¥¹¤òɽ¤¹¡£
244 (¥Í¥Ã¥È¥ï¡¼¥¯¥Ð¥¤¥È¥ª¡¼¥À¤Î) ¥¢¥É¥ì¥¹¤Î¾å°Ì¦ 3 ¥Ó¥Ã¥È¤¬¥Ð¥¤¥Ê¥êÃͤÇ
245 110 ¤Î¾ì¹ç¡¢¤³¤Î¥¢¥É¥ì¥¹¼ïÊ̤Ȥʤ롣¤³¤Î¥¢¥É¥ì¥¹¼ïÊ̤Ǥϡ¢
246 ¾å°Ì 3 ¥Ð¥¤¥È¤¬¥Í¥Ã¥È¥ï¡¼¥¯¥¢¥É¥ì¥¹¤òɽ¤·¡¢
247 »Ä¤ê¤Î 1 ¥Ð¥¤¥È¤¬¥Û¥¹¥È¥¢¥É¥ì¥¹¤òɽ¤¹¡£
249 ¥¯¥é¥¹¥Õ¥ë¡¦¥Í¥Ã¥È¥ï¡¼¥¯¥¢¥É¥ì¥¹¤Ï¸½ºß¤Ç¤ÏÇѻߤµ¤ì¡¢
250 ¥¯¥é¥¹¥ì¥¹¡¦¥É¥á¥¤¥ó´Ö¥ë¡¼¥Á¥ó (CIDR) ¤Ë¼è¤Ã¤ÆÂå¤ï¤é¤ì¤¿¡£
251 CIDR ¤Ç¤Ï¡¢¥¢¥É¥ì¥¹¤òǤ°Õ¤Î¥Ó¥Ã¥È¶³¦ (¥Ð¥¤¥È¶³¦¤Ç¤Ï¤Ê¤¤) ¤Ç
252 ¥Í¥Ã¥È¥ï¡¼¥¯Éô¤È¥Û¥¹¥ÈÉô¤Ëʬ³ä¤¹¤ë¡£
258 ¤Î»ÈÍÑÎã¤Ç¤¢¤ë¡£¤³¤Î¤è¤¦¤Ë¼Â¹Ô¤¹¤ë¡£
262 .RB "$" " ./a.out 226.000.000.037" " # Last byte is in octal"
264 .RB "$" " ./a.out 0x7f.1 " " # First byte is in hex"
268 .SS ¥×¥í¥°¥é¥à¤Î¥½¡¼¥¹
272 #include <arpa/inet.h>
277 main(int argc, char *argv[])
282 fprintf(stderr, "%s <dotted\-address>\\n", argv[0]);
286 if (inet_aton(argv[1], &addr) == 0) {
291 printf("%s\\n", inet_ntoa(addr));
298 .BR gethostbyname (3),