xref: /freebsd/lib/libc/net/getnameinfo.c (revision d5b0e70f7e04d971691517ce1304d86a1e367e2e) 
1 /*	$KAME: getnameinfo.c,v 1.61 2002/06/27 09:25:47 itojun Exp $	*/
2 
3 /*-
4  * SPDX-License-Identifier: BSD-3-Clause
5  *
6  * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
7  * Copyright (c) 2000 Ben Harris.
8  * All rights reserved.
9  *
10  * Redistribution and use in source and binary forms, with or without
11  * modification, are permitted provided that the following conditions
12  * are met:
13  * 1. Redistributions of source code must retain the above copyright
14  *    notice, this list of conditions and the following disclaimer.
15  * 2. Redistributions in binary form must reproduce the above copyright
16  *    notice, this list of conditions and the following disclaimer in the
17  *    documentation and/or other materials provided with the distribution.
18  * 3. Neither the name of the project nor the names of its contributors
19  *    may be used to endorse or promote products derived from this software
20  *    without specific prior written permission.
21  *
22  * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
23  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25  * ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
26  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32  * SUCH DAMAGE.
33  */
34 
35 /*
36  * Issues to be discussed:
37  * - Thread safe-ness must be checked
38  * - RFC2553 says that we should raise error on short buffer.  X/Open says
39  *   we need to truncate the result.  We obey RFC2553 (and X/Open should be
40  *   modified).  ipngwg rough consensus seems to follow RFC2553.
41  * - What is "local" in NI_FQDN?
42  * - NI_NAMEREQD and NI_NUMERICHOST conflict with each other.
43  * - (KAME extension) always attach textual scopeid (fe80::1%lo0), if
44  *   sin6_scope_id is filled - standardization status?
45  *   XXX breaks backward compat for code that expects no scopeid.
46  *   beware on merge.
47  */
48 
49 #include <sys/cdefs.h>
50 __FBSDID("$FreeBSD$");
51 
52 #include <sys/types.h>
53 #include <sys/socket.h>
54 #include <sys/un.h>
55 #include <net/if.h>
56 #include <net/if_dl.h>
57 #include <net/if_types.h>
58 #include <net/firewire.h>
59 #include <netinet/in.h>
60 #include <arpa/inet.h>
61 #include <arpa/nameser.h>
62 #include <netdb.h>
63 #include <resolv.h>
64 #include <string.h>
65 #include <stddef.h>
66 #include <errno.h>
67 
68 static const struct afd *find_afd(int);
69 static int getnameinfo_inet(const struct afd *,
70     const struct sockaddr *, socklen_t, char *,
71     size_t, char *, size_t, int);
72 #ifdef INET6
73 static int ip6_parsenumeric(const struct sockaddr *, const char *, char *,
74     size_t, int);
75 static int ip6_sa2str(const struct sockaddr_in6 *, char *, size_t, int);
76 #endif
77 static int getnameinfo_link(const struct afd *,
78     const struct sockaddr *, socklen_t, char *,
79     size_t, char *, size_t, int);
80 static int hexname(const u_int8_t *, size_t, char *, size_t);
81 static int getnameinfo_un(const struct afd *,
82     const struct sockaddr *, socklen_t, char *,
83     size_t, char *, size_t, int);
84 
85 static const struct afd {
86 	int a_af;
87 	size_t a_addrlen;
88 	socklen_t a_socklen;
89 	int a_off;
90 	int (*a_func)(const struct afd *,
91 	    const struct sockaddr *, socklen_t, char *,
92 	    size_t, char *, size_t, int);
93 } afdl [] = {
94 #ifdef INET6
95 	{PF_INET6, sizeof(struct in6_addr), sizeof(struct sockaddr_in6),
96 	    offsetof(struct sockaddr_in6, sin6_addr),
97 	    getnameinfo_inet},
98 #endif
99 	{PF_INET, sizeof(struct in_addr), sizeof(struct sockaddr_in),
100 	    offsetof(struct sockaddr_in, sin_addr),
101 	    getnameinfo_inet},
102 #define	sizeofmember(type, member)	(sizeof(((type *)0)->member))
103 	{PF_LOCAL, sizeofmember(struct sockaddr_un, sun_path),
104 	    sizeof(struct sockaddr_un),
105 	    offsetof(struct sockaddr_un, sun_path),
106 	    getnameinfo_un},
107 	{PF_LINK, sizeofmember(struct sockaddr_dl, sdl_data),
108 	    sizeof(struct sockaddr_dl),
109 	    offsetof(struct sockaddr_dl, sdl_data),
110 	    getnameinfo_link},
111 	{0, 0, 0},
112 };
113 
114 int
115 getnameinfo(const struct sockaddr *sa, socklen_t salen,
116     char *host, size_t hostlen, char *serv, size_t servlen,
117     int flags)
118 {
119 	const struct afd *afd;
120 
121 	if (sa == NULL)
122 		return (EAI_FAIL);
123 
124 	afd = find_afd(sa->sa_family);
125 	if (afd == NULL)
126 		return (EAI_FAMILY);
127 	/*
128 	 * getnameinfo() accepts an salen of sizeof(struct sockaddr_storage)
129 	 * at maximum as shown in RFC 4038 Sec.6.2.3.
130 	 */
131 	if (salen > sizeof(struct sockaddr_storage))
132 		return (EAI_FAMILY);
133 
134 	switch (sa->sa_family) {
135 	case PF_LOCAL:
136 		/*
137 		 * PF_LOCAL uses variable salen depending on the
138 		 * content length of sun_path.  Require 1 byte in
139 		 * sun_path at least.
140 		 */
141 		if (salen <= afd->a_socklen -
142 			sizeofmember(struct sockaddr_un, sun_path))
143 			return (EAI_FAMILY);
144 		else if (salen > afd->a_socklen)
145 			salen = afd->a_socklen;
146 		break;
147 	case PF_LINK:
148 		if (salen <= afd->a_socklen -
149 			sizeofmember(struct sockaddr_dl, sdl_data))
150 			return (EAI_FAMILY);
151 		break;
152 	default:
153 		if (salen < afd->a_socklen)
154 			return (EAI_FAMILY);
155 		else
156 			salen = afd->a_socklen;
157 		break;
158 	}
159 
160 	return ((*afd->a_func)(afd, sa, salen, host, hostlen,
161 	    serv, servlen, flags));
162 }
163 
164 static const struct afd *
165 find_afd(int af)
166 {
167 	const struct afd *afd;
168 
169 	if (af == PF_UNSPEC)
170 		return (NULL);
171 	for (afd = &afdl[0]; afd->a_af > 0; afd++) {
172 		if (afd->a_af == af)
173 			return (afd);
174 	}
175 	return (NULL);
176 }
177 
178 static int
179 getnameinfo_inet(const struct afd *afd,
180     const struct sockaddr *sa, socklen_t salen,
181     char *host, size_t hostlen, char *serv, size_t servlen,
182     int flags)
183 {
184 	struct servent *sp;
185 	struct hostent *hp;
186 	u_short port;
187 	const char *addr;
188 	u_int32_t v4a;
189 	int h_error;
190 	char numserv[512];
191 	char numaddr[512];
192 
193 	/* network byte order */
194 	port = ((const struct sockaddr_in *)sa)->sin_port;
195 	addr = (const char *)sa + afd->a_off;
196 
197 	if (serv == NULL || servlen == 0) {
198 		/*
199 		 * do nothing in this case.
200 		 * in case you are wondering if "&&" is more correct than
201 		 * "||" here: rfc2553bis-03 says that serv == NULL OR
202 		 * servlen == 0 means that the caller does not want the result.
203 		 */
204 	} else {
205 		if (flags & NI_NUMERICSERV)
206 			sp = NULL;
207 		else {
208 			sp = getservbyport(port,
209 				(flags & NI_DGRAM) ? "udp" : "tcp");
210 		}
211 		if (sp) {
212 			if (strlen(sp->s_name) + 1 > servlen)
213 				return EAI_MEMORY;
214 			strlcpy(serv, sp->s_name, servlen);
215 		} else {
216 			snprintf(numserv, sizeof(numserv), "%u", ntohs(port));
217 			if (strlen(numserv) + 1 > servlen)
218 				return EAI_MEMORY;
219 			strlcpy(serv, numserv, servlen);
220 		}
221 	}
222 
223 	switch (sa->sa_family) {
224 	case AF_INET:
225 		v4a = (u_int32_t)
226 		    ntohl(((const struct sockaddr_in *)sa)->sin_addr.s_addr);
227 		if (IN_MULTICAST(v4a) || IN_EXPERIMENTAL(v4a) ||
228 		    IN_ZERONET(v4a))
229 			flags |= NI_NUMERICHOST;
230 		break;
231 #ifdef INET6
232 	case AF_INET6:
233 	    {
234 		const struct sockaddr_in6 *sin6;
235 		sin6 = (const struct sockaddr_in6 *)sa;
236 		switch (sin6->sin6_addr.s6_addr[0]) {
237 		case 0x00:
238 			if (IN6_IS_ADDR_V4MAPPED(&sin6->sin6_addr))
239 				;
240 			else if (IN6_IS_ADDR_LOOPBACK(&sin6->sin6_addr))
241 				;
242 			else
243 				flags |= NI_NUMERICHOST;
244 			break;
245 		default:
246 			if (IN6_IS_ADDR_LINKLOCAL(&sin6->sin6_addr)) {
247 				flags |= NI_NUMERICHOST;
248 			}
249 			else if (IN6_IS_ADDR_MULTICAST(&sin6->sin6_addr))
250 				flags |= NI_NUMERICHOST;
251 			break;
252 		}
253 	    }
254 		break;
255 #endif
256 	}
257 	if (host == NULL || hostlen == 0) {
258 		/*
259 		 * do nothing in this case.
260 		 * in case you are wondering if "&&" is more correct than
261 		 * "||" here: rfc2553bis-03 says that host == NULL or
262 		 * hostlen == 0 means that the caller does not want the result.
263 		 */
264 	} else if (flags & NI_NUMERICHOST) {
265 		size_t numaddrlen;
266 
267 		/* NUMERICHOST and NAMEREQD conflicts with each other */
268 		if (flags & NI_NAMEREQD)
269 			return EAI_NONAME;
270 
271 		switch(afd->a_af) {
272 #ifdef INET6
273 		case AF_INET6:
274 		{
275 			int error;
276 
277 			if ((error = ip6_parsenumeric(sa, addr, host,
278 						      hostlen, flags)) != 0)
279 				return(error);
280 			break;
281 		}
282 #endif
283 		default:
284 			if (inet_ntop(afd->a_af, addr, numaddr, sizeof(numaddr))
285 			    == NULL)
286 				return EAI_SYSTEM;
287 			numaddrlen = strlen(numaddr);
288 			if (numaddrlen + 1 > hostlen) /* don't forget terminator */
289 				return EAI_MEMORY;
290 			strlcpy(host, numaddr, hostlen);
291 			break;
292 		}
293 	} else {
294 		hp = getipnodebyaddr(addr, afd->a_addrlen, afd->a_af, &h_error);
295 
296 		if (hp) {
297 #if 0
298 			/*
299 			 * commented out, since "for local host" is not
300 			 * implemented here - see RFC2553 p30
301 			 */
302 			if (flags & NI_NOFQDN) {
303 				char *p;
304 				p = strchr(hp->h_name, '.');
305 				if (p)
306 					*p = '\0';
307 			}
308 #endif
309 			if (strlen(hp->h_name) + 1 > hostlen) {
310 				freehostent(hp);
311 				return EAI_MEMORY;
312 			}
313 			strlcpy(host, hp->h_name, hostlen);
314 			freehostent(hp);
315 		} else {
316 			if (flags & NI_NAMEREQD)
317 				return EAI_NONAME;
318 			switch(afd->a_af) {
319 #ifdef INET6
320 			case AF_INET6:
321 			{
322 				int error;
323 
324 				if ((error = ip6_parsenumeric(sa, addr, host,
325 							      hostlen,
326 							      flags)) != 0)
327 					return(error);
328 				break;
329 			}
330 #endif
331 			default:
332 				if (inet_ntop(afd->a_af, addr, host,
333 				    hostlen) == NULL)
334 					return EAI_SYSTEM;
335 				break;
336 			}
337 		}
338 	}
339 	return(0);
340 }
341 
342 #ifdef INET6
343 static int
344 ip6_parsenumeric(const struct sockaddr *sa, const char *addr,
345     char *host, size_t hostlen, int flags)
346 {
347 	size_t numaddrlen;
348 	char numaddr[512];
349 
350 	if (inet_ntop(AF_INET6, addr, numaddr, sizeof(numaddr)) == NULL)
351 		return EAI_SYSTEM;
352 
353 	numaddrlen = strlen(numaddr);
354 	if (numaddrlen + 1 > hostlen) /* don't forget terminator */
355 		return EAI_OVERFLOW;
356 	strlcpy(host, numaddr, hostlen);
357 
358 	if (((const struct sockaddr_in6 *)sa)->sin6_scope_id) {
359 		char zonebuf[MAXHOSTNAMELEN];
360 		int zonelen;
361 
362 		zonelen = ip6_sa2str(
363 		    (const struct sockaddr_in6 *)(const void *)sa,
364 		    zonebuf, sizeof(zonebuf), flags);
365 		if (zonelen < 0)
366 			return EAI_OVERFLOW;
367 		if (zonelen + 1 + numaddrlen + 1 > hostlen)
368 			return EAI_OVERFLOW;
369 
370 		/* construct <numeric-addr><delim><zoneid> */
371 		memcpy(host + numaddrlen + 1, zonebuf,
372 		    (size_t)zonelen);
373 		host[numaddrlen] = SCOPE_DELIMITER;
374 		host[numaddrlen + 1 + zonelen] = '\0';
375 	}
376 
377 	return 0;
378 }
379 
380 /* ARGSUSED */
381 static int
382 ip6_sa2str(const struct sockaddr_in6 *sa6, char *buf, size_t bufsiz, int flags)
383 {
384 	unsigned int ifindex;
385 	const struct in6_addr *a6;
386 	int n;
387 
388 	ifindex = (unsigned int)sa6->sin6_scope_id;
389 	a6 = &sa6->sin6_addr;
390 
391 	if ((flags & NI_NUMERICSCOPE) != 0) {
392 		n = snprintf(buf, bufsiz, "%u", sa6->sin6_scope_id);
393 		if (n < 0 || n >= bufsiz)
394 			return -1;
395 		else
396 			return n;
397 	}
398 
399 	/* if_indextoname() does not take buffer size.  not a good api... */
400 	if ((IN6_IS_ADDR_LINKLOCAL(a6) || IN6_IS_ADDR_MC_LINKLOCAL(a6) ||
401 	     IN6_IS_ADDR_MC_NODELOCAL(a6)) && bufsiz >= IF_NAMESIZE) {
402 		char *p = if_indextoname(ifindex, buf);
403 		if (p) {
404 			return(strlen(p));
405 		}
406 	}
407 
408 	/* last resort */
409 	n = snprintf(buf, bufsiz, "%u", sa6->sin6_scope_id);
410 	if (n < 0 || (size_t)n >= bufsiz)
411 		return -1;
412 	else
413 		return n;
414 }
415 #endif /* INET6 */
416 
417 /*
418  * getnameinfo_link():
419  * Format a link-layer address into a printable format, paying attention to
420  * the interface type.
421  */
422 /* ARGSUSED */
423 static int
424 getnameinfo_link(const struct afd *afd,
425     const struct sockaddr *sa, socklen_t salen,
426     char *host, size_t hostlen, char *serv, size_t servlen, int flags)
427 {
428 	const struct sockaddr_dl *sdl =
429 	    (const struct sockaddr_dl *)(const void *)sa;
430 	const struct fw_hwaddr *iha;
431 	int n;
432 
433 	if (serv != NULL && servlen > 0)
434 		*serv = '\0';
435 
436 	if (sdl->sdl_nlen == 0 && sdl->sdl_alen == 0 && sdl->sdl_slen == 0) {
437 		n = snprintf(host, hostlen, "link#%d", sdl->sdl_index);
438 		if (n >= hostlen) {
439 			*host = '\0';
440 			return (EAI_MEMORY);
441 		}
442 		return (0);
443 	}
444 
445 	if (sdl->sdl_nlen > 0 && sdl->sdl_alen == 0) {
446 		n = sdl->sdl_nlen;
447 		if (n >= hostlen) {
448 			*host = '\0';
449 			return (EAI_MEMORY);
450 		}
451 		memcpy(host, sdl->sdl_data, sdl->sdl_nlen);
452 		host[n] = '\0';
453 		return (0);
454 	}
455 
456 	switch (sdl->sdl_type) {
457 	case IFT_IEEE1394:
458 		if (sdl->sdl_alen < sizeof(iha->sender_unique_ID_hi) +
459 		    sizeof(iha->sender_unique_ID_lo))
460 			return EAI_FAMILY;
461 		iha = (const struct fw_hwaddr *)(const void *)LLADDR(sdl);
462 		return hexname((const u_int8_t *)&iha->sender_unique_ID_hi,
463 		    sizeof(iha->sender_unique_ID_hi) +
464 		    sizeof(iha->sender_unique_ID_lo),
465 		    host, hostlen);
466 	/*
467 	 * The following have zero-length addresses.
468 	 * IFT_GIF	(net/if_gif.c)
469 	 * IFT_LOOP	(net/if_loop.c)
470 	 * IFT_PPP	(net/if_tuntap.c)
471 	 * IFT_SLIP	(net/if_sl.c, net/if_strip.c)
472 	 * IFT_STF	(net/if_stf.c)
473 	 * IFT_L2VLAN	(net/if_vlan.c)
474 	 * IFT_BRIDGE (net/if_bridge.h>
475 	 */
476 	/*
477 	 * The following use IPv4 addresses as link-layer addresses:
478 	 * IFT_OTHER	(net/if_gre.c)
479 	 * IFT_OTHER	(netinet/ip_ipip.c)
480 	 */
481 	/* default below is believed correct for all these. */
482 	case IFT_ETHER:
483 	case IFT_FDDI:
484 	case IFT_HIPPI:
485 	case IFT_ISO88025:
486 	default:
487 		return hexname((u_int8_t *)LLADDR(sdl), (size_t)sdl->sdl_alen,
488 		    host, hostlen);
489 	}
490 }
491 
492 static int
493 hexname(const u_int8_t *cp, size_t len, char *host, size_t hostlen)
494 {
495 	int i, n;
496 	char *outp = host;
497 
498 	*outp = '\0';
499 	for (i = 0; i < len; i++) {
500 		n = snprintf(outp, hostlen, "%s%02x",
501 		    i ? ":" : "", cp[i]);
502 		if (n < 0 || n >= hostlen) {
503 			*host = '\0';
504 			return EAI_MEMORY;
505 		}
506 		outp += n;
507 		hostlen -= n;
508 	}
509 	return 0;
510 }
511 
512 /*
513  * getnameinfo_un():
514  * Format a UNIX IPC domain address (pathname).
515  */
516 /* ARGSUSED */
517 static int
518 getnameinfo_un(const struct afd *afd,
519     const struct sockaddr *sa, socklen_t salen,
520     char *host, size_t hostlen, char *serv, size_t servlen, int flags)
521 {
522 	size_t pathlen;
523 
524 	if (serv != NULL && servlen > 0)
525 		*serv = '\0';
526 	if (host != NULL && hostlen > 0) {
527 		pathlen = salen - afd->a_off;
528 
529 		if (pathlen + 1 > hostlen) {
530 			*host = '\0';
531 			return (EAI_MEMORY);
532 		}
533 		strlcpy(host, (const char *)sa + afd->a_off, pathlen + 1);
534 	}
535 
536 	return (0);
537 }
538