xref: /freebsd/lib/libc/net/getnameinfo.c (revision ff0ba87247820afbdfdc1b307c803f7923d0e4d3) 
1 /*	$KAME: getnameinfo.c,v 1.61 2002/06/27 09:25:47 itojun Exp $	*/
2 
3 /*
4  * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
5  * Copyright (c) 2000 Ben Harris.
6  * All rights reserved.
7  *
8  * Redistribution and use in source and binary forms, with or without
9  * modification, are permitted provided that the following conditions
10  * are met:
11  * 1. Redistributions of source code must retain the above copyright
12  *    notice, this list of conditions and the following disclaimer.
13  * 2. Redistributions in binary form must reproduce the above copyright
14  *    notice, this list of conditions and the following disclaimer in the
15  *    documentation and/or other materials provided with the distribution.
16  * 3. Neither the name of the project nor the names of its contributors
17  *    may be used to endorse or promote products derived from this software
18  *    without specific prior written permission.
19  *
20  * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
21  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23  * ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
24  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30  * SUCH DAMAGE.
31  */
32 
33 /*
34  * Issues to be discussed:
35  * - Thread safe-ness must be checked
36  * - RFC2553 says that we should raise error on short buffer.  X/Open says
37  *   we need to truncate the result.  We obey RFC2553 (and X/Open should be
38  *   modified).  ipngwg rough consensus seems to follow RFC2553.
39  * - What is "local" in NI_FQDN?
40  * - NI_NAMEREQD and NI_NUMERICHOST conflict with each other.
41  * - (KAME extension) always attach textual scopeid (fe80::1%lo0), if
42  *   sin6_scope_id is filled - standardization status?
43  *   XXX breaks backward compat for code that expects no scopeid.
44  *   beware on merge.
45  */
46 
47 #include <sys/cdefs.h>
48 __FBSDID("$FreeBSD$");
49 
50 #include <sys/types.h>
51 #include <sys/socket.h>
52 #include <net/if.h>
53 #include <net/if_dl.h>
54 #include <net/if_types.h>
55 #include <net/firewire.h>
56 #include <netinet/in.h>
57 #include <arpa/inet.h>
58 #include <arpa/nameser.h>
59 #include <netdb.h>
60 #include <resolv.h>
61 #include <string.h>
62 #include <stddef.h>
63 #include <errno.h>
64 
65 static int	getnameinfo_inet(const struct sockaddr *, socklen_t, char *,
66     size_t, char *, size_t, int);
67 #ifdef INET6
68 static int ip6_parsenumeric(const struct sockaddr *, const char *, char *,
69     size_t, int);
70 static int ip6_sa2str(const struct sockaddr_in6 *, char *, size_t, int);
71 #endif
72 static int	getnameinfo_link(const struct sockaddr *, socklen_t, char *,
73     size_t, char *, size_t, int);
74 static int	hexname(const u_int8_t *, size_t, char *, size_t);
75 
76 int
77 getnameinfo(const struct sockaddr *sa, socklen_t salen,
78     char *host, size_t hostlen, char *serv, size_t servlen,
79     int flags)
80 {
81 
82 	switch (sa->sa_family) {
83 	case AF_INET:
84 #ifdef INET6
85 	case AF_INET6:
86 #endif
87 		return getnameinfo_inet(sa, salen, host, hostlen, serv,
88 		    servlen, flags);
89 	case AF_LINK:
90 		return getnameinfo_link(sa, salen, host, hostlen, serv,
91 		    servlen, flags);
92 	default:
93 		return EAI_FAMILY;
94 	}
95 }
96 
97 static const struct afd {
98 	int a_af;
99 	size_t a_addrlen;
100 	socklen_t a_socklen;
101 	int a_off;
102 } afdl [] = {
103 #ifdef INET6
104 	{PF_INET6, sizeof(struct in6_addr), sizeof(struct sockaddr_in6),
105 		offsetof(struct sockaddr_in6, sin6_addr)},
106 #endif
107 	{PF_INET, sizeof(struct in_addr), sizeof(struct sockaddr_in),
108 		offsetof(struct sockaddr_in, sin_addr)},
109 	{0, 0, 0},
110 };
111 
112 struct sockinet {
113 	u_char	si_len;
114 	u_char	si_family;
115 	u_short	si_port;
116 };
117 
118 static int
119 getnameinfo_inet(const struct sockaddr *sa, socklen_t salen,
120     char *host, size_t hostlen, char *serv, size_t servlen,
121     int flags)
122 {
123 	const struct afd *afd;
124 	struct servent *sp;
125 	struct hostent *hp;
126 	u_short port;
127 	int family, i;
128 	const char *addr;
129 	u_int32_t v4a;
130 	int h_error;
131 	char numserv[512];
132 	char numaddr[512];
133 
134 	if (sa == NULL)
135 		return EAI_FAIL;
136 
137 	family = sa->sa_family;
138 	for (i = 0; afdl[i].a_af; i++)
139 		if (afdl[i].a_af == family) {
140 			afd = &afdl[i];
141 			goto found;
142 		}
143 	return EAI_FAMILY;
144 
145  found:
146 	if (salen != afd->a_socklen)
147 		return EAI_FAIL;
148 
149 	/* network byte order */
150 	port = ((const struct sockinet *)sa)->si_port;
151 	addr = (const char *)sa + afd->a_off;
152 
153 	if (serv == NULL || servlen == 0) {
154 		/*
155 		 * do nothing in this case.
156 		 * in case you are wondering if "&&" is more correct than
157 		 * "||" here: rfc2553bis-03 says that serv == NULL OR
158 		 * servlen == 0 means that the caller does not want the result.
159 		 */
160 	} else {
161 		if (flags & NI_NUMERICSERV)
162 			sp = NULL;
163 		else {
164 			sp = getservbyport(port,
165 				(flags & NI_DGRAM) ? "udp" : "tcp");
166 		}
167 		if (sp) {
168 			if (strlen(sp->s_name) + 1 > servlen)
169 				return EAI_MEMORY;
170 			strlcpy(serv, sp->s_name, servlen);
171 		} else {
172 			snprintf(numserv, sizeof(numserv), "%u", ntohs(port));
173 			if (strlen(numserv) + 1 > servlen)
174 				return EAI_MEMORY;
175 			strlcpy(serv, numserv, servlen);
176 		}
177 	}
178 
179 	switch (sa->sa_family) {
180 	case AF_INET:
181 		v4a = (u_int32_t)
182 		    ntohl(((const struct sockaddr_in *)sa)->sin_addr.s_addr);
183 		if (IN_MULTICAST(v4a) || IN_EXPERIMENTAL(v4a))
184 			flags |= NI_NUMERICHOST;
185 		v4a >>= IN_CLASSA_NSHIFT;
186 		if (v4a == 0)
187 			flags |= NI_NUMERICHOST;
188 		break;
189 #ifdef INET6
190 	case AF_INET6:
191 	    {
192 		const struct sockaddr_in6 *sin6;
193 		sin6 = (const struct sockaddr_in6 *)sa;
194 		switch (sin6->sin6_addr.s6_addr[0]) {
195 		case 0x00:
196 			if (IN6_IS_ADDR_V4MAPPED(&sin6->sin6_addr))
197 				;
198 			else if (IN6_IS_ADDR_LOOPBACK(&sin6->sin6_addr))
199 				;
200 			else
201 				flags |= NI_NUMERICHOST;
202 			break;
203 		default:
204 			if (IN6_IS_ADDR_LINKLOCAL(&sin6->sin6_addr)) {
205 				flags |= NI_NUMERICHOST;
206 			}
207 			else if (IN6_IS_ADDR_MULTICAST(&sin6->sin6_addr))
208 				flags |= NI_NUMERICHOST;
209 			break;
210 		}
211 	    }
212 		break;
213 #endif
214 	}
215 	if (host == NULL || hostlen == 0) {
216 		/*
217 		 * do nothing in this case.
218 		 * in case you are wondering if "&&" is more correct than
219 		 * "||" here: rfc2553bis-03 says that host == NULL or
220 		 * hostlen == 0 means that the caller does not want the result.
221 		 */
222 	} else if (flags & NI_NUMERICHOST) {
223 		size_t numaddrlen;
224 
225 		/* NUMERICHOST and NAMEREQD conflicts with each other */
226 		if (flags & NI_NAMEREQD)
227 			return EAI_NONAME;
228 
229 		switch(afd->a_af) {
230 #ifdef INET6
231 		case AF_INET6:
232 		{
233 			int error;
234 
235 			if ((error = ip6_parsenumeric(sa, addr, host,
236 						      hostlen, flags)) != 0)
237 				return(error);
238 			break;
239 		}
240 #endif
241 		default:
242 			if (inet_ntop(afd->a_af, addr, numaddr, sizeof(numaddr))
243 			    == NULL)
244 				return EAI_SYSTEM;
245 			numaddrlen = strlen(numaddr);
246 			if (numaddrlen + 1 > hostlen) /* don't forget terminator */
247 				return EAI_MEMORY;
248 			strlcpy(host, numaddr, hostlen);
249 			break;
250 		}
251 	} else {
252 		hp = getipnodebyaddr(addr, afd->a_addrlen, afd->a_af, &h_error);
253 
254 		if (hp) {
255 #if 0
256 			/*
257 			 * commented out, since "for local host" is not
258 			 * implemented here - see RFC2553 p30
259 			 */
260 			if (flags & NI_NOFQDN) {
261 				char *p;
262 				p = strchr(hp->h_name, '.');
263 				if (p)
264 					*p = '\0';
265 			}
266 #endif
267 			if (strlen(hp->h_name) + 1 > hostlen) {
268 				freehostent(hp);
269 				return EAI_MEMORY;
270 			}
271 			strlcpy(host, hp->h_name, hostlen);
272 			freehostent(hp);
273 		} else {
274 			if (flags & NI_NAMEREQD)
275 				return EAI_NONAME;
276 			switch(afd->a_af) {
277 #ifdef INET6
278 			case AF_INET6:
279 			{
280 				int error;
281 
282 				if ((error = ip6_parsenumeric(sa, addr, host,
283 							      hostlen,
284 							      flags)) != 0)
285 					return(error);
286 				break;
287 			}
288 #endif
289 			default:
290 				if (inet_ntop(afd->a_af, addr, host,
291 				    hostlen) == NULL)
292 					return EAI_SYSTEM;
293 				break;
294 			}
295 		}
296 	}
297 	return(0);
298 }
299 
300 #ifdef INET6
301 static int
302 ip6_parsenumeric(const struct sockaddr *sa, const char *addr,
303     char *host, size_t hostlen, int flags)
304 {
305 	size_t numaddrlen;
306 	char numaddr[512];
307 
308 	if (inet_ntop(AF_INET6, addr, numaddr, sizeof(numaddr)) == NULL)
309 		return EAI_SYSTEM;
310 
311 	numaddrlen = strlen(numaddr);
312 	if (numaddrlen + 1 > hostlen) /* don't forget terminator */
313 		return EAI_OVERFLOW;
314 	strlcpy(host, numaddr, hostlen);
315 
316 	if (((const struct sockaddr_in6 *)sa)->sin6_scope_id) {
317 		char zonebuf[MAXHOSTNAMELEN];
318 		int zonelen;
319 
320 		zonelen = ip6_sa2str(
321 		    (const struct sockaddr_in6 *)(const void *)sa,
322 		    zonebuf, sizeof(zonebuf), flags);
323 		if (zonelen < 0)
324 			return EAI_OVERFLOW;
325 		if (zonelen + 1 + numaddrlen + 1 > hostlen)
326 			return EAI_OVERFLOW;
327 
328 		/* construct <numeric-addr><delim><zoneid> */
329 		memcpy(host + numaddrlen + 1, zonebuf,
330 		    (size_t)zonelen);
331 		host[numaddrlen] = SCOPE_DELIMITER;
332 		host[numaddrlen + 1 + zonelen] = '\0';
333 	}
334 
335 	return 0;
336 }
337 
338 /* ARGSUSED */
339 static int
340 ip6_sa2str(const struct sockaddr_in6 *sa6, char *buf, size_t bufsiz, int flags)
341 {
342 	unsigned int ifindex;
343 	const struct in6_addr *a6;
344 	int n;
345 
346 	ifindex = (unsigned int)sa6->sin6_scope_id;
347 	a6 = &sa6->sin6_addr;
348 
349 #ifdef NI_NUMERICSCOPE
350 	if ((flags & NI_NUMERICSCOPE) != 0) {
351 		n = snprintf(buf, bufsiz, "%u", sa6->sin6_scope_id);
352 		if (n < 0 || n >= bufsiz)
353 			return -1;
354 		else
355 			return n;
356 	}
357 #endif
358 
359 	/* if_indextoname() does not take buffer size.  not a good api... */
360 	if ((IN6_IS_ADDR_LINKLOCAL(a6) || IN6_IS_ADDR_MC_LINKLOCAL(a6) ||
361 	     IN6_IS_ADDR_MC_NODELOCAL(a6)) && bufsiz >= IF_NAMESIZE) {
362 		char *p = if_indextoname(ifindex, buf);
363 		if (p) {
364 			return(strlen(p));
365 		}
366 	}
367 
368 	/* last resort */
369 	n = snprintf(buf, bufsiz, "%u", sa6->sin6_scope_id);
370 	if (n < 0 || (size_t)n >= bufsiz)
371 		return -1;
372 	else
373 		return n;
374 }
375 #endif /* INET6 */
376 
377 /*
378  * getnameinfo_link():
379  * Format a link-layer address into a printable format, paying attention to
380  * the interface type.
381  */
382 /* ARGSUSED */
383 static int
384 getnameinfo_link(const struct sockaddr *sa, socklen_t salen,
385     char *host, size_t hostlen, char *serv, size_t servlen, int flags)
386 {
387 	const struct sockaddr_dl *sdl =
388 	    (const struct sockaddr_dl *)(const void *)sa;
389 	const struct fw_hwaddr *iha;
390 	int n;
391 
392 	if (serv != NULL && servlen > 0)
393 		*serv = '\0';
394 
395 	if (sdl->sdl_nlen == 0 && sdl->sdl_alen == 0 && sdl->sdl_slen == 0) {
396 		n = snprintf(host, hostlen, "link#%d", sdl->sdl_index);
397 		if (n > hostlen) {
398 			*host = '\0';
399 			return EAI_MEMORY;
400 		}
401 		return 0;
402 	}
403 
404 	switch (sdl->sdl_type) {
405 	case IFT_IEEE1394:
406 		if (sdl->sdl_alen < sizeof(iha->sender_unique_ID_hi) +
407 		    sizeof(iha->sender_unique_ID_lo))
408 			return EAI_FAMILY;
409 		iha = (const struct fw_hwaddr *)(const void *)LLADDR(sdl);
410 		return hexname((const u_int8_t *)&iha->sender_unique_ID_hi,
411 		    sizeof(iha->sender_unique_ID_hi) +
412 		    sizeof(iha->sender_unique_ID_lo),
413 		    host, hostlen);
414 	/*
415 	 * The following have zero-length addresses.
416 	 * IFT_ATM	(net/if_atmsubr.c)
417 	 * IFT_GIF	(net/if_gif.c)
418 	 * IFT_LOOP	(net/if_loop.c)
419 	 * IFT_PPP	(net/if_ppp.c, net/if_spppsubr.c)
420 	 * IFT_SLIP	(net/if_sl.c, net/if_strip.c)
421 	 * IFT_STF	(net/if_stf.c)
422 	 * IFT_L2VLAN	(net/if_vlan.c)
423 	 * IFT_BRIDGE (net/if_bridge.h>
424 	 */
425 	/*
426 	 * The following use IPv4 addresses as link-layer addresses:
427 	 * IFT_OTHER	(net/if_gre.c)
428 	 * IFT_OTHER	(netinet/ip_ipip.c)
429 	 */
430 	/* default below is believed correct for all these. */
431 	case IFT_ARCNET:
432 	case IFT_ETHER:
433 	case IFT_FDDI:
434 	case IFT_HIPPI:
435 	case IFT_ISO88025:
436 	default:
437 		return hexname((u_int8_t *)LLADDR(sdl), (size_t)sdl->sdl_alen,
438 		    host, hostlen);
439 	}
440 }
441 
442 static int
443 hexname(cp, len, host, hostlen)
444 	const u_int8_t *cp;
445 	char *host;
446 	size_t len, hostlen;
447 {
448 	int i, n;
449 	char *outp = host;
450 
451 	*outp = '\0';
452 	for (i = 0; i < len; i++) {
453 		n = snprintf(outp, hostlen, "%s%02x",
454 		    i ? ":" : "", cp[i]);
455 		if (n < 0 || n >= hostlen) {
456 			*host = '\0';
457 			return EAI_MEMORY;
458 		}
459 		outp += n;
460 		hostlen -= n;
461 	}
462 	return 0;
463 }
464