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1 | .\" Copyright (c) 2007, 2008 Michael Kerrisk <mtk.manpages@gmail.com> |
2 | .\" and Copyright (c) 2006 Ulrich Drepper <drepper@redhat.com> | |
3 | .\" A few pieces of an earlier version remain: | |
4 | .\" Copyright 2000, Sam Varshavchik <mrsam@courier-mta.com> | |
fea681da | 5 | .\" |
93015253 | 6 | .\" %%%LICENSE_START(VERBATIM) |
fea681da MK |
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. | |
10 | .\" | |
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. | |
c13182ef | 15 | .\" |
fea681da MK |
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17 | .\" manual page may be incorrect or out-of-date.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 | |
22 | .\" professionally. | |
c13182ef | 23 | .\" |
fea681da MK |
24 | .\" Formatted or processed versions of this manual, if unaccompanied by |
25 | .\" the source, must acknowledge the copyright and authors of this work. | |
4b72fb64 | 26 | .\" %%%LICENSE_END |
fea681da MK |
27 | .\" |
28 | .\" References: RFC 2553 | |
8d18d6ed | 29 | .\" |
c13182ef | 30 | .\" 2005-08-09, mtk, added AI_ALL, AI_ADDRCONFIG, AI_V4MAPPED, |
8d18d6ed | 31 | .\" and AI_NUMERICSERV. |
a3edd71d MK |
32 | .\" 2006-11-25, Ulrich Drepper <drepper@redhat.com> |
33 | .\" Add text describing Internationalized Domain Name extensions. | |
35bf3cc8 | 34 | .\" 2007-06-08, mtk: added example programs |
0af804ac MK |
35 | .\" 2008-02-26, mtk; clarify discussion of NULL 'hints' argument; other |
36 | .\" minor rewrites. | |
a3edd71d | 37 | .\" 2008-06-18, mtk: many parts rewritten |
00269a5a PB |
38 | .\" 2008-12-04, Petr Baudis <pasky@suse.cz> |
39 | .\" Describe results ordering and reference /etc/gai.conf. | |
bea08fec | 40 | .\" |
273f6680 MK |
41 | .\" FIXME . glibc's 2.9 NEWS file documents DCCP and UDP-lite support |
42 | .\" and is SCTP support now also there? | |
8d18d6ed | 43 | .\" |
b8dbf73d | 44 | .TH GETADDRINFO 3 2014-04-06 "GNU" "Linux Programmer's Manual" |
fea681da | 45 | .SH NAME |
a3edd71d MK |
46 | getaddrinfo, freeaddrinfo, gai_strerror \- network address and |
47 | service translation | |
fea681da MK |
48 | .SH SYNOPSIS |
49 | .nf | |
50 | .B #include <sys/types.h> | |
51 | .B #include <sys/socket.h> | |
52 | .B #include <netdb.h> | |
53 | .sp | |
54 | .BI "int getaddrinfo(const char *" "node" ", const char *" "service" , | |
55 | .BI " const struct addrinfo *" "hints" , | |
56 | .BI " struct addrinfo **" "res" ); | |
57 | .sp | |
58 | .BI "void freeaddrinfo(struct addrinfo *" "res" ); | |
59 | .sp | |
60 | .BI "const char *gai_strerror(int " "errcode" ); | |
61 | .fi | |
0f200f07 MK |
62 | .sp |
63 | .in -4n | |
64 | Feature Test Macro Requirements for glibc (see | |
65 | .BR feature_test_macros (7)): | |
66 | .ad l | |
67 | .in | |
68 | .sp | |
69 | .BR getaddrinfo (), | |
70 | .BR freeaddrinfo (), | |
71 | .BR gai_strerror (): | |
b7f522a3 | 72 | .RS 4 |
0f200f07 | 73 | _POSIX_C_SOURCE\ >=\ 1 || _XOPEN_SOURCE || _POSIX_SOURCE |
b7f522a3 | 74 | .RE |
0f200f07 | 75 | .ad b |
fea681da | 76 | .SH DESCRIPTION |
0af804ac MK |
77 | Given |
78 | .I node | |
79 | and | |
80 | .IR service , | |
a3edd71d | 81 | which identify an Internet host and a service, |
0af804ac | 82 | .BR getaddrinfo () |
a3edd71d MK |
83 | returns one or more |
84 | .I addrinfo | |
85 | structures, each of which contains an Internet address | |
86 | that can be specified in a call to | |
0af804ac | 87 | .BR bind (2) |
a3edd71d MK |
88 | or |
89 | .BR connect (2). | |
fea681da | 90 | The |
2777b1ca | 91 | .BR getaddrinfo () |
fea681da | 92 | function combines the functionality provided by the |
823ecd0c MK |
93 | .\" .BR getipnodebyname (3), |
94 | .\" .BR getipnodebyaddr (3), | |
1be94306 | 95 | .BR gethostbyname (3) |
fea681da | 96 | and |
1d8d141a | 97 | .BR getservbyname (3) |
0af804ac | 98 | functions into a single interface, but unlike the latter functions, |
2777b1ca | 99 | .BR getaddrinfo () |
a3edd71d | 100 | is reentrant and allows programs to eliminate IPv4-versus-IPv6 dependencies. |
fea681da MK |
101 | .PP |
102 | The | |
8478ee02 | 103 | .I addrinfo |
a3edd71d MK |
104 | structure used by |
105 | .BR getaddrinfo () | |
106 | contains the following fields: | |
fea681da | 107 | .sp |
3ad4ddcd | 108 | .in +4n |
fea681da | 109 | .nf |
89f9f5b2 MK |
110 | struct addrinfo { |
111 | int ai_flags; | |
112 | int ai_family; | |
113 | int ai_socktype; | |
114 | int ai_protocol; | |
a05228ea | 115 | socklen_t ai_addrlen; |
89f9f5b2 MK |
116 | struct sockaddr *ai_addr; |
117 | char *ai_canonname; | |
118 | struct addrinfo *ai_next; | |
119 | }; | |
fea681da | 120 | .fi |
3ad4ddcd | 121 | .in |
fea681da | 122 | .PP |
fea681da | 123 | The |
fea681da | 124 | .I hints |
a3edd71d | 125 | argument points to an |
0af804ac MK |
126 | .I addrinfo |
127 | structure that specifies criteria for selecting the socket address | |
128 | structures returned in the list pointed to by | |
129 | .IR res . | |
a3edd71d MK |
130 | If |
131 | .I hints | |
132 | is not NULL it points to an | |
8478ee02 | 133 | .I addrinfo |
a3edd71d | 134 | structure whose |
fea681da MK |
135 | .IR ai_family , |
136 | .IR ai_socktype , | |
137 | and | |
138 | .I ai_protocol | |
a3edd71d MK |
139 | specify criteria that limit the set of socket addresses returned by |
140 | .BR getaddrinfo (), | |
141 | as follows: | |
142 | .TP 12 | |
fea681da | 143 | .I ai_family |
a3edd71d MK |
144 | This field specifies the desired address family for the returned addresses. |
145 | Valid values for this field include | |
146 | .BR AF_INET | |
147 | and | |
148 | .BR AF_INET6 . | |
149 | The value | |
150 | .B AF_UNSPEC | |
151 | indicates that | |
152 | .BR getaddrinfo () | |
153 | should return socket addresses for any address family | |
154 | (either IPv4 or IPv6, for example) that can be used with | |
155 | .I node | |
156 | and | |
157 | .IR service . | |
158 | .TP | |
fea681da | 159 | .I ai_socktype |
a3edd71d MK |
160 | This field specifies the preferred socket type, for example |
161 | .BR SOCK_STREAM | |
fea681da | 162 | or |
a3edd71d MK |
163 | .BR SOCK_DGRAM . |
164 | Specifying 0 in this field indicates that socket addresses of any type | |
165 | can be returned by | |
166 | .BR getaddrinfo (). | |
167 | .TP | |
fea681da | 168 | .I ai_protocol |
a3edd71d MK |
169 | This field specifies the protocol for the returned socket addresses. |
170 | Specifying 0 in this field indicates that socket addresses with | |
171 | any protocol can be returned by | |
172 | .BR getaddrinfo (). | |
173 | .TP | |
fea681da | 174 | .I ai_flags |
a3edd71d | 175 | This field specifies additional options, described below. |
414ed40c | 176 | Multiple flags are specified by bitwise OR-ing them together. |
a3edd71d MK |
177 | .PP |
178 | All the other fields in the structure pointed to by | |
fea681da | 179 | .I hints |
b437fdd9 | 180 | must contain either 0 or a null pointer, as appropriate. |
bf68db18 | 181 | .PP |
0af804ac MK |
182 | Specifying |
183 | .I hints | |
184 | as NULL is equivalent to setting | |
185 | .I ai_socktype | |
186 | and | |
187 | .I ai_protocol | |
188 | to 0; | |
189 | .I ai_family | |
190 | to | |
191 | .BR AF_UNSPEC ; | |
192 | and | |
193 | .I ai_flags | |
194 | to | |
195 | .BR "(AI_V4MAPPED\ |\ AI_ADDRCONFIG)" . | |
bf68db18 MK |
196 | (POSIX specifies different defaults for |
197 | .IR ai_flags ; | |
198 | see NOTES.) | |
fea681da MK |
199 | .I node |
200 | specifies either a numerical network address | |
a3edd71d MK |
201 | (for IPv4, numbers-and-dots notation as supported by |
202 | .BR inet_aton (3); | |
203 | for IPv6, hexadecimal string format as supported by | |
204 | .BR inet_pton (3)), | |
fea681da | 205 | or a network hostname, whose network addresses are looked up and resolved. |
8d18d6ed MK |
206 | If |
207 | .I hints.ai_flags | |
208 | contains the | |
fea681da | 209 | .B AI_NUMERICHOST |
4c3fac10 | 210 | flag, then |
fea681da | 211 | .I node |
a3edd71d | 212 | must be a numerical network address. |
fea681da MK |
213 | The |
214 | .B AI_NUMERICHOST | |
215 | flag suppresses any potentially lengthy network host address lookups. | |
216 | .PP | |
a3edd71d MK |
217 | If the |
218 | .B AI_PASSIVE | |
219 | flag is specified in | |
220 | .IR hints.ai_flags , | |
221 | and | |
222 | .I node | |
223 | is NULL, | |
224 | then the returned socket addresses will be suitable for | |
225 | .BR bind (2)ing | |
226 | a socket that will | |
227 | .BR accept (2) | |
228 | connections. | |
229 | The returned socket address will contain the "wildcard address" | |
230 | .RB ( INADDR_ANY | |
231 | for IPv4 addresses, | |
232 | .BR IN6ADDR_ANY_INIT | |
233 | for IPv6 address). | |
234 | The wildcard address is used by applications (typically servers) | |
235 | that intend to accept connections on any of the hosts's network addresses. | |
236 | If | |
237 | .I node | |
238 | is not NULL, then the | |
20f81e4b | 239 | .B AI_PASSIVE |
a3edd71d MK |
240 | flag is ignored. |
241 | .PP | |
242 | If the | |
243 | .B AI_PASSIVE | |
244 | flag is not set in | |
245 | .IR hints.ai_flags , | |
246 | then the returned socket addresses will be suitable for use with | |
247 | .BR connect (2), | |
248 | .BR sendto (2), | |
249 | or | |
250 | .BR sendmsg (2). | |
251 | If | |
252 | .I node | |
253 | is NULL, | |
254 | then the network address will be set to the loopback interface address | |
255 | .RB ( INADDR_LOOPBACK | |
256 | for IPv4 addresses, | |
257 | .BR IN6ADDR_LOOPBACK_INIT | |
258 | for IPv6 address); | |
259 | this is used by applications that intend to communicate | |
260 | with peers running on the same host. | |
261 | .PP | |
262 | .I service | |
263 | sets the port in each returned address structure. | |
264 | If this argument is a service name (see | |
265 | .BR services (5)), | |
266 | it is translated to the corresponding port number. | |
267 | This argument can also be specified as a decimal number, | |
268 | which is simply converted to binary. | |
269 | If | |
270 | .I service | |
271 | is NULL, then the port number of the returned socket addresses | |
272 | will be left uninitialized. | |
273 | If | |
274 | .B AI_NUMERICSERV | |
275 | is specified in | |
276 | .I hints.ai_flags | |
277 | and | |
278 | .I service | |
279 | is not NULL, then | |
280 | .I service | |
281 | must point to a string containing a numeric port number. | |
282 | This flag is used to inhibit the invocation of a name resolution service | |
283 | in cases where it is known not to be required. | |
284 | .PP | |
285 | Either | |
286 | .I node | |
287 | or | |
288 | .IR service , | |
289 | but not both, may be NULL. | |
290 | .PP | |
fea681da | 291 | The |
2777b1ca | 292 | .BR getaddrinfo () |
a3edd71d | 293 | function allocates and initializes a linked list of |
8478ee02 | 294 | .I addrinfo |
a3edd71d MK |
295 | structures, one for each network address that matches |
296 | .I node | |
297 | and | |
298 | .IR service , | |
299 | subject to any restrictions imposed by | |
300 | .IR hints , | |
301 | and returns a pointer to the start of the list in | |
3cf81850 | 302 | .IR res . |
a3edd71d MK |
303 | The items in the linked list are linked by the |
304 | .I ai_next | |
305 | field. | |
00269a5a | 306 | |
a3edd71d MK |
307 | There are several reasons why |
308 | the linked list may have more than one | |
c13182ef | 309 | .I addrinfo |
ae03dc66 | 310 | structure, including: the network host is multihomed, accessible |
43f72e1b | 311 | over multiple protocols (e.g., both |
00269a5a PB |
312 | .BR AF_INET |
313 | and | |
314 | .BR AF_INET6 ); | |
315 | or the same service is available from multiple socket types (one | |
a3edd71d MK |
316 | .B SOCK_STREAM |
317 | address and another | |
318 | .B SOCK_DGRAM | |
319 | address, for example). | |
00269a5a PB |
320 | Normally, the application should try |
321 | using the addresses in the order in which they are returned. | |
322 | The sorting function used within | |
323 | .BR getaddrinfo () | |
324 | is defined in RFC\ 3484; the order can be tweaked for a particular | |
325 | system by editing | |
8ccde1f0 | 326 | .IR /etc/gai.conf |
00269a5a | 327 | (available since glibc 2.5). |
a3edd71d MK |
328 | .PP |
329 | If | |
8d18d6ed | 330 | .I hints.ai_flags |
fea681da MK |
331 | includes the |
332 | .B AI_CANONNAME | |
a3edd71d MK |
333 | flag, then the |
334 | .I ai_canonname | |
335 | field of the first of the | |
336 | .I addrinfo | |
337 | structures in the returned list is set to point to the | |
338 | official name of the host. | |
c13182ef | 339 | .\" In glibc prior to 2.3.4, the ai_canonname of each addrinfo |
8194de33 | 340 | .\" structure was set pointing to the canonical name; that was |
c13182ef | 341 | .\" more than POSIX.1-2001 specified, or other implementations provided. |
8194de33 | 342 | .\" MTK, Aug 05 |
a3edd71d MK |
343 | |
344 | The remaining fields of each returned | |
345 | .I addrinfo | |
346 | structure are initialized as follows: | |
347 | .IP * 2 | |
348 | The | |
9d68eac8 | 349 | .IR ai_family , |
fea681da MK |
350 | .IR ai_socktype , |
351 | and | |
352 | .I ai_protocol | |
a3edd71d MK |
353 | fields return the socket creation parameters (i.e., these fields have |
354 | the same meaning as the corresponding arguments of | |
0af804ac | 355 | .BR socket (2)). |
a3edd71d MK |
356 | For example, |
357 | .I ai_family | |
358 | might return | |
359 | .B AF_INET | |
360 | or | |
361 | .BR AF_INET6 ; | |
362 | .I ai_socktype | |
363 | might return | |
364 | .B SOCK_DGRAM | |
365 | or | |
366 | .BR SOCK_STREAM ; | |
367 | and | |
368 | .I ai_protocol | |
369 | returns the protocol for the socket. | |
370 | .IP * | |
fea681da MK |
371 | A pointer to the socket address is placed in the |
372 | .I ai_addr | |
a3edd71d | 373 | field, and the length of the socket address, in bytes, |
fea681da MK |
374 | is placed in the |
375 | .I ai_addrlen | |
a3edd71d | 376 | field. |
fea681da | 377 | .PP |
8d18d6ed MK |
378 | If |
379 | .I hints.ai_flags | |
380 | includes the | |
381 | .B AI_ADDRCONFIG | |
382 | flag, then IPv4 addresses are returned in the list pointed to by | |
19f56c70 | 383 | .I res |
c13182ef | 384 | only if the local system has at least one |
33a0ccb2 MK |
385 | IPv4 address configured, and IPv6 addresses are returned |
386 | only if the local system has at least one IPv6 address configured. | |
712b0341 JMV |
387 | The loopback address is not considered for this case as valid |
388 | as a configured address. | |
2534ef15 MK |
389 | This flag is useful on, for example, |
390 | IPv4-only systems, to ensure that | |
391 | .BR getaddrinfo () | |
392 | does not return IPv6 socket addresses that would always fail in | |
393 | .BR connect (2) | |
394 | or | |
395 | .BR bind (2). | |
8d18d6ed MK |
396 | .PP |
397 | If | |
290e89bd | 398 | .I hints.ai_flags |
8d18d6ed MK |
399 | specifies the |
400 | .B AI_V4MAPPED | |
401 | flag, and | |
402 | .I hints.ai_family | |
403 | was specified as | |
404 | .BR AF_INET6 , | |
405 | and no matching IPv6 addresses could be found, | |
406 | then return IPv4-mapped IPv6 addresses in the list pointed to by | |
19f56c70 | 407 | .IR res . |
8d18d6ed MK |
408 | If both |
409 | .B AI_V4MAPPED | |
410 | and | |
411 | .B AI_ALL | |
412 | are specified in | |
af4a01eb | 413 | .IR hints.ai_flags , |
c13182ef | 414 | then return both IPv6 and IPv4-mapped IPv6 addresses |
8d18d6ed | 415 | in the list pointed to by |
19f56c70 | 416 | .IR res . |
8d18d6ed MK |
417 | .B AI_ALL |
418 | is ignored if | |
419 | .B AI_V4MAPPED | |
420 | is not also specified. | |
421 | .PP | |
fea681da | 422 | The |
2777b1ca | 423 | .BR freeaddrinfo () |
fea681da | 424 | function frees the memory that was allocated |
8194de33 | 425 | for the dynamically allocated linked list |
fea681da | 426 | .IR res . |
73d8cece | 427 | .SS Extensions to getaddrinfo() for Internationalized Domain Names |
22135cad MK |
428 | .PP |
429 | Starting with glibc 2.3.4, | |
c13182ef MK |
430 | .BR getaddrinfo () |
431 | has been extended to selectively allow the incoming and outgoing | |
ddaec46d | 432 | hostnames to be transparently converted to and from the |
22135cad MK |
433 | Internationalized Domain Name (IDN) format (see RFC 3490, |
434 | .IR "Internationalizing Domain Names in Applications (IDNA)" ). | |
435 | Four new flags are defined: | |
436 | .TP | |
437 | .B AI_IDN | |
438 | If this flag is specified, then the node name given in | |
439 | .I node | |
440 | is converted to IDN format if necessary. | |
441 | The source encoding is that of the current locale. | |
442 | ||
c13182ef MK |
443 | If the input name contains non-ASCII characters, then the IDN encoding |
444 | is used. | |
22135cad | 445 | Those parts of the node name (delimited by dots) that contain |
c13182ef | 446 | non-ASCII characters are encoded using ASCII Compatible Encoding (ACE) |
22135cad MK |
447 | before being passed to the name resolution functions. |
448 | .\" Implementation Detail: | |
449 | .\" To minimize effects on system performance the implementation might | |
450 | .\" want to check whether the input string contains any non-ASCII | |
451 | .\" characters. If there are none the IDN step can be skipped completely. | |
452 | .\" On systems which allow not-ASCII safe encodings for a locale this | |
453 | .\" might be a problem. | |
454 | .TP | |
455 | .B AI_CANONIDN | |
c13182ef MK |
456 | After a successful name lookup, and if the |
457 | .B AI_CANONNAME | |
22135cad MK |
458 | flag was specified, |
459 | .BR getaddrinfo () | |
460 | will return the canonical name of the | |
c13182ef MK |
461 | node corresponding to the |
462 | .I addrinfo | |
22135cad MK |
463 | structure value passed back. |
464 | The return value is an exact copy of the value returned by the name | |
465 | resolution function. | |
466 | ||
c13182ef | 467 | If the name is encoded using ACE, then it will contain the |
94e9d9fe | 468 | .I xn\-\- |
c13182ef MK |
469 | prefix for one or more components of the name. |
470 | To convert these components into a readable form the | |
471 | .B AI_CANONIDN | |
472 | flag can be passed in addition to | |
473 | .BR AI_CANONNAME . | |
22135cad MK |
474 | The resulting string is encoded using the current locale's encoding. |
475 | .\" | |
476 | .\"Implementation Detail: | |
94e9d9fe | 477 | .\"If no component of the returned name starts with xn\-\- the IDN |
22135cad MK |
478 | .\"step can be skipped, therefore avoiding unnecessary slowdowns. |
479 | .TP | |
480 | .BR AI_IDN_ALLOW_UNASSIGNED ", " AI_IDN_USE_STD3_ASCII_RULES | |
c13182ef | 481 | Setting these flags will enable the |
22135cad | 482 | IDNA_ALLOW_UNASSIGNED (allow unassigned Unicode code points) and |
c13182ef | 483 | IDNA_USE_STD3_ASCII_RULES (check output to make sure it is a STD3 |
ddaec46d | 484 | conforming hostname) |
22135cad | 485 | flags respectively to be used in the IDNA handling. |
47297adb | 486 | .SH RETURN VALUE |
d5da3c8d | 487 | .\" FIXME glibc defines the following additional errors, some which |
c13182ef | 488 | .\" can probably be returned by getaddrinfo(); they need to |
22135cad | 489 | .\" be documented. |
3d32fee8 MK |
490 | .\" #ifdef __USE_GNU |
491 | .\" #define EAI_INPROGRESS -100 /* Processing request in progress. */ | |
492 | .\" #define EAI_CANCELED -101 /* Request canceled. */ | |
493 | .\" #define EAI_NOTCANCELED -102 /* Request not canceled. */ | |
494 | .\" #define EAI_ALLDONE -103 /* All requests done. */ | |
495 | .\" #define EAI_INTR -104 /* Interrupted by a signal. */ | |
496 | .\" #define EAI_IDN_ENCODE -105 /* IDN encoding failed. */ | |
497 | .\" #endif | |
2777b1ca | 498 | .BR getaddrinfo () |
c7094399 | 499 | returns 0 if it succeeds, or one of the following nonzero error codes: |
fea681da | 500 | .TP |
a0aa388d | 501 | .B EAI_ADDRFAMILY |
a3edd71d | 502 | .\" Not in SUSv3 |
a0aa388d MK |
503 | The specified network host does not have any network addresses in the |
504 | requested address family. | |
fea681da | 505 | .TP |
a0aa388d MK |
506 | .B EAI_AGAIN |
507 | The name server returned a temporary failure indication. | |
508 | Try again later. | |
fea681da MK |
509 | .TP |
510 | .B EAI_BADFLAGS | |
a87c4a1d MK |
511 | .I hints.ai_flags |
512 | contains invalid flags; or, | |
513 | .I hints.ai_flags | |
514 | included | |
515 | .B AI_CANONNAME | |
516 | and | |
517 | .I name | |
518 | was NULL. | |
fea681da | 519 | .TP |
a0aa388d MK |
520 | .B EAI_FAIL |
521 | The name server returned a permanent failure indication. | |
522 | .TP | |
523 | .B EAI_FAMILY | |
a3edd71d | 524 | The requested address family is not supported. |
a0aa388d MK |
525 | .TP |
526 | .B EAI_MEMORY | |
527 | Out of memory. | |
528 | .TP | |
529 | .B EAI_NODATA | |
a3edd71d | 530 | .\" Not in SUSv3 |
a0aa388d MK |
531 | The specified network host exists, but does not have any |
532 | network addresses defined. | |
533 | .TP | |
fea681da MK |
534 | .B EAI_NONAME |
535 | The | |
536 | .I node | |
537 | or | |
538 | .I service | |
8d18d6ed | 539 | is not known; or both |
fea681da MK |
540 | .I node |
541 | and | |
542 | .I service | |
8d18d6ed MK |
543 | are NULL; or |
544 | .B AI_NUMERICSERV | |
545 | was specified in | |
546 | .I hints.ai_flags | |
c13182ef | 547 | and |
8d18d6ed MK |
548 | .I service |
549 | was not a numeric port-number string. | |
fea681da MK |
550 | .TP |
551 | .B EAI_SERVICE | |
552 | The requested service is not available for the requested socket type. | |
553 | It may be available through another socket type. | |
a87c4a1d MK |
554 | For example, this error could occur if |
555 | .I service | |
33a0ccb2 | 556 | was "shell" (a service available only on stream sockets), and either |
a87c4a1d MK |
557 | .I hints.ai_protocol |
558 | was | |
559 | .BR IPPROTO_UDP , | |
560 | or | |
561 | .I hints.ai_socktype | |
562 | was | |
563 | .BR SOCK_DGRAM ; | |
564 | or the error could occur if | |
565 | .I service | |
566 | was not NULL, and | |
567 | .I hints.ai_socktype | |
568 | was | |
569 | .BR SOCK_RAW | |
570 | (a socket type that does not support the concept of services). | |
fea681da | 571 | .TP |
a0aa388d | 572 | .B EAI_SOCKTYPE |
a3edd71d | 573 | The requested socket type is not supported. |
a87c4a1d MK |
574 | This could occur, for example, if |
575 | .I hints.ai_socktype | |
576 | and | |
577 | .I hints.ai_protocol | |
c5571b61 | 578 | are inconsistent (e.g., |
a87c4a1d MK |
579 | .BR SOCK_DGRAM |
580 | and | |
581 | .BR IPPROTO_TCP , | |
add478c1 | 582 | respectively). |
fea681da MK |
583 | .TP |
584 | .B EAI_SYSTEM | |
585 | Other system error, check | |
586 | .I errno | |
587 | for details. | |
588 | .PP | |
589 | The | |
2777b1ca | 590 | .BR gai_strerror () |
fea681da MK |
591 | function translates these error codes to a human readable string, |
592 | suitable for error reporting. | |
47297adb | 593 | .SH FILES |
00269a5a | 594 | .I /etc/gai.conf |
47297adb | 595 | .SH CONFORMING TO |
68e1685c | 596 | POSIX.1-2001. |
fea681da | 597 | The |
63aa9df0 | 598 | .BR getaddrinfo () |
331da7c3 | 599 | function is documented in RFC\ 2553. |
47297adb | 600 | .SH NOTES |
c783f237 MK |
601 | .BR getaddrinfo () |
602 | supports the | |
603 | .IB address % scope-id | |
604 | notation for specifying the IPv6 scope-ID. | |
605 | ||
8d18d6ed | 606 | .BR AI_ADDRCONFIG , |
d63f46e1 | 607 | .BR AI_ALL , |
8d18d6ed | 608 | and |
0daa9e92 | 609 | .B AI_V4MAPPED |
8d18d6ed | 610 | are available since glibc 2.3.3. |
0daa9e92 | 611 | .B AI_NUMERICSERV |
8d18d6ed | 612 | is available since glibc 2.3.4. |
f9d5775f MK |
613 | |
614 | According to POSIX.1-2001, specifying | |
615 | .I hints | |
616 | as NULL should cause | |
617 | .I ai_flags | |
618 | to be assumed as 0. | |
619 | The GNU C library instead assumes a value of | |
17e5e677 | 620 | .BR "(AI_V4MAPPED\ |\ AI_ADDRCONFIG)" |
f9d5775f MK |
621 | for this case, |
622 | since this value is considered an improvement on the specification. | |
35bf3cc8 | 623 | .SH EXAMPLE |
88a180b7 MK |
624 | .\" getnameinfo.3 refers to this example |
625 | .\" socket.2 refers to this example | |
626 | .\" bind.2 refers to this example | |
627 | .\" connect.2 refers to this example | |
628 | .\" recvfrom.2 refers to this example | |
629 | .\" sendto.2 refers to this example | |
35bf3cc8 MK |
630 | The following programs demonstrate the use of |
631 | .BR getaddrinfo (), | |
632 | .BR gai_strerror (), | |
633 | .BR freeaddrinfo (), | |
634 | and | |
635 | .BR getnameinfo (3). | |
636 | The programs are an echo server and client for UDP datagrams. | |
213bea67 | 637 | .SS Server program |
d84d0300 | 638 | \& |
35bf3cc8 | 639 | .nf |
988db661 | 640 | #include <sys/types.h> |
35bf3cc8 | 641 | #include <stdio.h> |
988db661 MK |
642 | #include <stdlib.h> |
643 | #include <unistd.h> | |
644 | #include <string.h> | |
645 | #include <sys/socket.h> | |
35bf3cc8 MK |
646 | #include <netdb.h> |
647 | ||
648 | #define BUF_SIZE 500 | |
649 | ||
650 | int | |
651 | main(int argc, char *argv[]) | |
652 | { | |
653 | struct addrinfo hints; | |
654 | struct addrinfo *result, *rp; | |
655 | int sfd, s; | |
656 | struct sockaddr_storage peer_addr; | |
657 | socklen_t peer_addr_len; | |
658 | ssize_t nread; | |
659 | char buf[BUF_SIZE]; | |
660 | ||
661 | if (argc != 2) { | |
662 | fprintf(stderr, "Usage: %s port\\n", argv[0]); | |
663 | exit(EXIT_FAILURE); | |
664 | } | |
665 | ||
666 | memset(&hints, 0, sizeof(struct addrinfo)); | |
667 | hints.ai_family = AF_UNSPEC; /* Allow IPv4 or IPv6 */ | |
668 | hints.ai_socktype = SOCK_DGRAM; /* Datagram socket */ | |
669 | hints.ai_flags = AI_PASSIVE; /* For wildcard IP address */ | |
670 | hints.ai_protocol = 0; /* Any protocol */ | |
59cef123 MK |
671 | hints.ai_canonname = NULL; |
672 | hints.ai_addr = NULL; | |
673 | hints.ai_next = NULL; | |
35bf3cc8 MK |
674 | |
675 | s = getaddrinfo(NULL, argv[1], &hints, &result); | |
676 | if (s != 0) { | |
677 | fprintf(stderr, "getaddrinfo: %s\\n", gai_strerror(s)); | |
678 | exit(EXIT_FAILURE); | |
679 | } | |
680 | ||
681 | /* getaddrinfo() returns a list of address structures. | |
7a056410 | 682 | Try each address until we successfully bind(2). |
988db661 | 683 | If socket(2) (or bind(2)) fails, we (close the socket |
35bf3cc8 MK |
684 | and) try the next address. */ |
685 | ||
29059a65 | 686 | for (rp = result; rp != NULL; rp = rp\->ai_next) { |
988db661 | 687 | sfd = socket(rp\->ai_family, rp\->ai_socktype, |
29059a65 MK |
688 | rp\->ai_protocol); |
689 | if (sfd == \-1) | |
35bf3cc8 MK |
690 | continue; |
691 | ||
29059a65 | 692 | if (bind(sfd, rp\->ai_addr, rp\->ai_addrlen) == 0) |
35bf3cc8 MK |
693 | break; /* Success */ |
694 | ||
695 | close(sfd); | |
696 | } | |
697 | ||
698 | if (rp == NULL) { /* No address succeeded */ | |
699 | fprintf(stderr, "Could not bind\\n"); | |
700 | exit(EXIT_FAILURE); | |
701 | } | |
702 | ||
703 | freeaddrinfo(result); /* No longer needed */ | |
704 | ||
705 | /* Read datagrams and echo them back to sender */ | |
706 | ||
707 | for (;;) { | |
708 | peer_addr_len = sizeof(struct sockaddr_storage); | |
988db661 | 709 | nread = recvfrom(sfd, buf, BUF_SIZE, 0, |
35bf3cc8 | 710 | (struct sockaddr *) &peer_addr, &peer_addr_len); |
29059a65 | 711 | if (nread == \-1) |
35bf3cc8 MK |
712 | continue; /* Ignore failed request */ |
713 | ||
714 | char host[NI_MAXHOST], service[NI_MAXSERV]; | |
988db661 MK |
715 | |
716 | s = getnameinfo((struct sockaddr *) &peer_addr, | |
35bf3cc8 MK |
717 | peer_addr_len, host, NI_MAXHOST, |
718 | service, NI_MAXSERV, NI_NUMERICSERV); | |
988db661 | 719 | if (s == 0) |
8c5fcd21 MK |
720 | printf("Received %zd bytes from %s:%s\\n", |
721 | nread, host, service); | |
35bf3cc8 MK |
722 | else |
723 | fprintf(stderr, "getnameinfo: %s\\n", gai_strerror(s)); | |
724 | ||
988db661 | 725 | if (sendto(sfd, buf, nread, 0, |
35bf3cc8 | 726 | (struct sockaddr *) &peer_addr, |
988db661 | 727 | peer_addr_len) != nread) |
35bf3cc8 MK |
728 | fprintf(stderr, "Error sending response\\n"); |
729 | } | |
730 | } | |
731 | .fi | |
213bea67 | 732 | .SS Client program |
1f79eca5 | 733 | \& |
35bf3cc8 | 734 | .nf |
988db661 | 735 | #include <sys/types.h> |
35bf3cc8 MK |
736 | #include <sys/socket.h> |
737 | #include <netdb.h> | |
738 | #include <stdio.h> | |
988db661 MK |
739 | #include <stdlib.h> |
740 | #include <unistd.h> | |
741 | #include <string.h> | |
35bf3cc8 MK |
742 | |
743 | #define BUF_SIZE 500 | |
744 | ||
745 | int | |
746 | main(int argc, char *argv[]) | |
747 | { | |
748 | struct addrinfo hints; | |
749 | struct addrinfo *result, *rp; | |
750 | int sfd, s, j; | |
751 | size_t len; | |
752 | ssize_t nread; | |
753 | char buf[BUF_SIZE]; | |
754 | ||
755 | if (argc < 3) { | |
756 | fprintf(stderr, "Usage: %s host port msg...\\n", argv[0]); | |
757 | exit(EXIT_FAILURE); | |
758 | } | |
759 | ||
760 | /* Obtain address(es) matching host/port */ | |
761 | ||
762 | memset(&hints, 0, sizeof(struct addrinfo)); | |
763 | hints.ai_family = AF_UNSPEC; /* Allow IPv4 or IPv6 */ | |
764 | hints.ai_socktype = SOCK_DGRAM; /* Datagram socket */ | |
765 | hints.ai_flags = 0; | |
766 | hints.ai_protocol = 0; /* Any protocol */ | |
767 | ||
768 | s = getaddrinfo(argv[1], argv[2], &hints, &result); | |
769 | if (s != 0) { | |
770 | fprintf(stderr, "getaddrinfo: %s\\n", gai_strerror(s)); | |
771 | exit(EXIT_FAILURE); | |
772 | } | |
773 | ||
774 | /* getaddrinfo() returns a list of address structures. | |
7a056410 MK |
775 | Try each address until we successfully connect(2). |
776 | If socket(2) (or connect(2)) fails, we (close the socket | |
35bf3cc8 MK |
777 | and) try the next address. */ |
778 | ||
29059a65 | 779 | for (rp = result; rp != NULL; rp = rp\->ai_next) { |
988db661 | 780 | sfd = socket(rp\->ai_family, rp\->ai_socktype, |
29059a65 MK |
781 | rp\->ai_protocol); |
782 | if (sfd == \-1) | |
35bf3cc8 | 783 | continue; |
988db661 | 784 | |
29059a65 | 785 | if (connect(sfd, rp\->ai_addr, rp\->ai_addrlen) != \-1) |
35bf3cc8 MK |
786 | break; /* Success */ |
787 | ||
788 | close(sfd); | |
789 | } | |
790 | ||
791 | if (rp == NULL) { /* No address succeeded */ | |
792 | fprintf(stderr, "Could not connect\\n"); | |
793 | exit(EXIT_FAILURE); | |
794 | } | |
795 | ||
796 | freeaddrinfo(result); /* No longer needed */ | |
797 | ||
988db661 | 798 | /* Send remaining command\-line arguments as separate |
35bf3cc8 MK |
799 | datagrams, and read responses from server */ |
800 | ||
801 | for (j = 3; j < argc; j++) { | |
988db661 | 802 | len = strlen(argv[j]) + 1; |
35bf3cc8 MK |
803 | /* +1 for terminating null byte */ |
804 | ||
805 | if (len + 1 > BUF_SIZE) { | |
988db661 | 806 | fprintf(stderr, |
35bf3cc8 MK |
807 | "Ignoring long message in argument %d\\n", j); |
808 | continue; | |
809 | } | |
810 | ||
811 | if (write(sfd, argv[j], len) != len) { | |
812 | fprintf(stderr, "partial/failed write\\n"); | |
813 | exit(EXIT_FAILURE); | |
814 | } | |
988db661 | 815 | |
35bf3cc8 | 816 | nread = read(sfd, buf, BUF_SIZE); |
29059a65 | 817 | if (nread == \-1) { |
35bf3cc8 MK |
818 | perror("read"); |
819 | exit(EXIT_FAILURE); | |
820 | } | |
821 | ||
8c5fcd21 | 822 | printf("Received %zd bytes: %s\\n", nread, buf); |
35bf3cc8 MK |
823 | } |
824 | ||
825 | exit(EXIT_SUCCESS); | |
826 | } | |
827 | .fi | |
47297adb | 828 | .SH SEE ALSO |
823ecd0c | 829 | .\" .BR getipnodebyaddr (3), |
ac5e6a36 | 830 | .\" .BR getipnodebyname (3), |
b27b1153 | 831 | .BR getaddrinfo_a (3), |
a3edd71d | 832 | .BR gethostbyname (3), |
60435a75 | 833 | .BR getnameinfo (3), |
a3edd71d | 834 | .BR inet (3), |
625526ef | 835 | .BR gai.conf (5), |
a3edd71d MK |
836 | .BR hostname (7), |
837 | .BR ip (7) |