xref: /dragonfly/lib/libc/net/getnameinfo.c (revision 73610d44) 
1 /*	$FreeBSD: src/lib/libc/net/getnameinfo.c,v 1.20 2007/02/28 21:18:38 bms Exp $	*/
2 /*	$KAME: getnameinfo.c,v 1.61 2002/06/27 09:25:47 itojun Exp $	*/
3 
4 /*
5  * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
6  * Copyright (c) 2000 Ben Harris.
7  * All rights reserved.
8  *
9  * Redistribution and use in source and binary forms, with or without
10  * modification, are permitted provided that the following conditions
11  * are met:
12  * 1. Redistributions of source code must retain the above copyright
13  *    notice, this list of conditions and the following disclaimer.
14  * 2. Redistributions in binary form must reproduce the above copyright
15  *    notice, this list of conditions and the following disclaimer in the
16  *    documentation and/or other materials provided with the distribution.
17  * 3. Neither the name of the project nor the names of its contributors
18  *    may be used to endorse or promote products derived from this software
19  *    without specific prior written permission.
20  *
21  * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31  * SUCH DAMAGE.
32  */
33 
34 /*
35  * Issues to be discussed:
36  * - Thread safe-ness must be checked
37  * - RFC2553 says that we should raise error on short buffer.  X/Open says
38  *   we need to truncate the result.  We obey RFC2553 (and X/Open should be
39  *   modified).  ipngwg rough consensus seems to follow RFC2553.
40  * - What is "local" in NI_FQDN?
41  * - NI_NAMEREQD and NI_NUMERICHOST conflict with each other.
42  * - (KAME extension) always attach textual scopeid (fe80::1%lo0), if
43  *   sin6_scope_id is filled - standardization status?
44  *   XXX breaks backward compat for code that expects no scopeid.
45  *   beware on merge.
46  */
47 
48 #include <sys/types.h>
49 #include <sys/socket.h>
50 #include <net/if.h>
51 #include <net/if_dl.h>
52 #include <net/if_types.h>
53 #include <netinet/in.h>
54 #include <arpa/inet.h>
55 #include <arpa/nameser.h>
56 #include <netdb.h>
57 #include <resolv.h>
58 #include <string.h>
59 #include <stddef.h>
60 #include <errno.h>
61 
62 static int	getnameinfo_inet(const struct sockaddr *, socklen_t, char *,
63 				 size_t, char *, size_t, int);
64 #ifdef INET6
65 static int	ip6_parsenumeric(const struct sockaddr *, const char *, char *,
66 				 size_t, int);
67 static int	ip6_sa2str(const struct sockaddr_in6 *, char *, size_t, int);
68 #endif
69 static int	getnameinfo_link(const struct sockaddr *, socklen_t, char *,
70 				 size_t, char *, size_t, int);
71 static int	hexname(const u_int8_t *, size_t, char *, size_t);
72 
73 int
74 getnameinfo(const struct sockaddr *sa, socklen_t salen, char *host,
75 	    size_t hostlen, char *serv, size_t servlen, int flags)
76 {
77 
78 	switch (sa->sa_family) {
79 	case AF_INET:
80 #ifdef INET6
81 	case AF_INET6:
82 #endif
83 		return getnameinfo_inet(sa, salen, host, hostlen, serv,
84 		    servlen, flags);
85 	case AF_LINK:
86 		return getnameinfo_link(sa, salen, host, hostlen, serv,
87 		    servlen, flags);
88 	default:
89 		return EAI_FAMILY;
90 	}
91 }
92 
93 static const struct afd {
94 	int a_af;
95 	size_t a_addrlen;
96 	socklen_t a_socklen;
97 	int a_off;
98 } afdl [] = {
99 #ifdef INET6
100 	{PF_INET6, sizeof(struct in6_addr), sizeof(struct sockaddr_in6),
101 		offsetof(struct sockaddr_in6, sin6_addr)},
102 #endif
103 	{PF_INET, sizeof(struct in_addr), sizeof(struct sockaddr_in),
104 		offsetof(struct sockaddr_in, sin_addr)},
105 	{ .a_af = 0 },
106 };
107 
108 struct sockinet {
109 	u_char	si_len;
110 	u_char	si_family;
111 	u_short	si_port;
112 };
113 
114 static int
115 getnameinfo_inet(const struct sockaddr *sa, socklen_t salen, char *host,
116 		 size_t hostlen, char *serv, size_t servlen, int flags)
117 {
118 	const struct afd *afd;
119 	struct servent *sp;
120 	struct hostent *hp;
121 	u_short port;
122 	int family, i;
123 	const char *addr;
124 	u_int32_t v4a;
125 	int h_error;
126 	char numserv[512];
127 	char numaddr[512];
128 
129 	if (sa == NULL)
130 		return EAI_FAIL;
131 
132 	family = sa->sa_family;
133 	for (i = 0; afdl[i].a_af; i++)
134 		if (afdl[i].a_af == family) {
135 			afd = &afdl[i];
136 			goto found;
137 		}
138 	return EAI_FAMILY;
139 
140  found:
141 	if (salen != afd->a_socklen)
142 		return EAI_FAIL;
143 
144 	/* network byte order */
145 	port = ((const struct sockinet *)sa)->si_port;
146 	addr = (const char *)sa + afd->a_off;
147 
148 	if (serv == NULL || servlen == 0) {
149 		/*
150 		 * do nothing in this case.
151 		 * in case you are wondering if "&&" is more correct than
152 		 * "||" here: rfc2553bis-03 says that serv == NULL OR
153 		 * servlen == 0 means that the caller does not want the result.
154 		 */
155 	} else {
156 		if (flags & NI_NUMERICSERV)
157 			sp = NULL;
158 		else {
159 			sp = getservbyport(port,
160 				(flags & NI_DGRAM) ? "udp" : "tcp");
161 		}
162 		if (sp) {
163 			if (strlen(sp->s_name) + 1 > servlen)
164 				return EAI_MEMORY;
165 			strlcpy(serv, sp->s_name, servlen);
166 		} else {
167 			snprintf(numserv, sizeof(numserv), "%u", ntohs(port));
168 			if (strlen(numserv) + 1 > servlen)
169 				return EAI_MEMORY;
170 			strlcpy(serv, numserv, servlen);
171 		}
172 	}
173 
174 	switch (sa->sa_family) {
175 	case AF_INET:
176 		v4a = (u_int32_t)
177 		    ntohl(((const struct sockaddr_in *)sa)->sin_addr.s_addr);
178 		if (IN_MULTICAST(v4a) || IN_EXPERIMENTAL(v4a))
179 			flags |= NI_NUMERICHOST;
180 		v4a >>= IN_CLASSA_NSHIFT;
181 		if (v4a == 0)
182 			flags |= NI_NUMERICHOST;
183 		break;
184 #ifdef INET6
185 	case AF_INET6:
186 	    {
187 		const struct sockaddr_in6 *sin6;
188 		sin6 = (const struct sockaddr_in6 *)sa;
189 		switch (sin6->sin6_addr.s6_addr[0]) {
190 		case 0x00:
191 			if (IN6_IS_ADDR_V4MAPPED(&sin6->sin6_addr))
192 				;
193 			else if (IN6_IS_ADDR_LOOPBACK(&sin6->sin6_addr))
194 				;
195 			else
196 				flags |= NI_NUMERICHOST;
197 			break;
198 		default:
199 			if (IN6_IS_ADDR_LINKLOCAL(&sin6->sin6_addr)) {
200 				flags |= NI_NUMERICHOST;
201 			}
202 			else if (IN6_IS_ADDR_MULTICAST(&sin6->sin6_addr))
203 				flags |= NI_NUMERICHOST;
204 			break;
205 		}
206 	    }
207 		break;
208 #endif
209 	}
210 	if (host == NULL || hostlen == 0) {
211 		/*
212 		 * do nothing in this case.
213 		 * in case you are wondering if "&&" is more correct than
214 		 * "||" here: rfc2553bis-03 says that host == NULL or
215 		 * hostlen == 0 means that the caller does not want the result.
216 		 */
217 	} else if (flags & NI_NUMERICHOST) {
218 		size_t numaddrlen;
219 
220 		/* NUMERICHOST and NAMEREQD conflicts with each other */
221 		if (flags & NI_NAMEREQD)
222 			return EAI_NONAME;
223 
224 		switch(afd->a_af) {
225 #ifdef INET6
226 		case AF_INET6:
227 		{
228 			int error;
229 
230 			if ((error = ip6_parsenumeric(sa, addr, host,
231 						      hostlen, flags)) != 0)
232 				return(error);
233 			break;
234 		}
235 #endif
236 		default:
237 			if (inet_ntop(afd->a_af, addr, numaddr, sizeof(numaddr))
238 			    == NULL)
239 				return EAI_SYSTEM;
240 			numaddrlen = strlen(numaddr);
241 			if (numaddrlen + 1 > hostlen) /* don't forget terminator */
242 				return EAI_MEMORY;
243 			strlcpy(host, numaddr, hostlen);
244 			break;
245 		}
246 	} else {
247 		hp = getipnodebyaddr(addr, afd->a_addrlen, afd->a_af, &h_error);
248 
249 		if (hp) {
250 #if 0
251 			/*
252 			 * commented out, since "for local host" is not
253 			 * implemented here - see RFC2553 p30
254 			 */
255 			if (flags & NI_NOFQDN) {
256 				char *p;
257 				p = strchr(hp->h_name, '.');
258 				if (p)
259 					*p = '\0';
260 			}
261 #endif
262 			if (strlen(hp->h_name) + 1 > hostlen) {
263 				freehostent(hp);
264 				return EAI_MEMORY;
265 			}
266 			strlcpy(host, hp->h_name, hostlen);
267 			freehostent(hp);
268 		} else {
269 			if (flags & NI_NAMEREQD)
270 				return EAI_NONAME;
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,
279 							      flags)) != 0)
280 					return(error);
281 				break;
282 			}
283 #endif
284 			default:
285 				if (inet_ntop(afd->a_af, addr, host,
286 				    hostlen) == NULL)
287 					return EAI_SYSTEM;
288 				break;
289 			}
290 		}
291 	}
292 	return(0);
293 }
294 
295 #ifdef INET6
296 static int
297 ip6_parsenumeric(const struct sockaddr *sa, const char *addr, char *host,
298 		 size_t hostlen, int flags)
299 {
300 	size_t numaddrlen;
301 	char numaddr[512];
302 
303 	if (inet_ntop(AF_INET6, addr, numaddr, sizeof(numaddr)) == NULL)
304 		return EAI_SYSTEM;
305 
306 	numaddrlen = strlen(numaddr);
307 	if (numaddrlen + 1 > hostlen) /* don't forget terminator */
308 		return EAI_OVERFLOW;
309 	strlcpy(host, numaddr, hostlen);
310 
311 	if (((const struct sockaddr_in6 *)sa)->sin6_scope_id) {
312 		char zonebuf[MAXHOSTNAMELEN];
313 		int zonelen;
314 
315 		zonelen = ip6_sa2str(
316 		    (const struct sockaddr_in6 *)(const void *)sa,
317 		    zonebuf, sizeof(zonebuf), flags);
318 		if (zonelen < 0)
319 			return EAI_OVERFLOW;
320 		if (zonelen + 1 + numaddrlen + 1 > hostlen)
321 			return EAI_OVERFLOW;
322 
323 		/* construct <numeric-addr><delim><zoneid> */
324 		memcpy(host + numaddrlen + 1, zonebuf,
325 		    (size_t)zonelen);
326 		host[numaddrlen] = SCOPE_DELIMITER;
327 		host[numaddrlen + 1 + zonelen] = '\0';
328 	}
329 
330 	return 0;
331 }
332 
333 /* ARGSUSED */
334 static int
335 ip6_sa2str(const struct sockaddr_in6 *sa6, char *buf, size_t bufsiz,
336 	   int flags __unused)
337 {
338 	unsigned int ifindex;
339 	const struct in6_addr *a6;
340 	int n;
341 
342 	ifindex = (unsigned int)sa6->sin6_scope_id;
343 	a6 = &sa6->sin6_addr;
344 
345 #ifdef NI_NUMERICSCOPE
346 	if ((flags & NI_NUMERICSCOPE) != 0) {
347 		n = snprintf(buf, bufsiz, "%u", sa6->sin6_scope_id);
348 		if (n < 0 || n >= bufsiz)
349 			return -1;
350 		else
351 			return n;
352 	}
353 #endif
354 
355 	/* if_indextoname() does not take buffer size.  not a good api... */
356 	if ((IN6_IS_ADDR_LINKLOCAL(a6) || IN6_IS_ADDR_MC_LINKLOCAL(a6) ||
357 	     IN6_IS_ADDR_MC_NODELOCAL(a6)) && bufsiz >= IF_NAMESIZE) {
358 		char *p = if_indextoname(ifindex, buf);
359 		if (p) {
360 			return(strlen(p));
361 		}
362 	}
363 
364 	/* last resort */
365 	n = snprintf(buf, bufsiz, "%u", sa6->sin6_scope_id);
366 	if (n < 0 || (size_t)n >= bufsiz)
367 		return -1;
368 	else
369 		return n;
370 }
371 #endif /* INET6 */
372 
373 /*
374  * getnameinfo_link():
375  * Format a link-layer address into a printable format, paying attention to
376  * the interface type.
377  */
378 /* ARGSUSED */
379 static int
380 getnameinfo_link(const struct sockaddr *sa, socklen_t salen __unused,
381 		 char *host, size_t hostlen, char *serv, size_t servlen,
382 		 int flags __unused)
383 {
384 	const struct sockaddr_dl *sdl =
385 	    (const struct sockaddr_dl *)(const void *)sa;
386 	int n;
387 
388 	if (serv != NULL && servlen > 0)
389 		*serv = '\0';
390 
391 	if (sdl->sdl_nlen == 0 && sdl->sdl_alen == 0 && sdl->sdl_slen == 0) {
392 		n = snprintf(host, hostlen, "link#%d", sdl->sdl_index);
393 		if (n > hostlen) {
394 			*host = '\0';
395 			return EAI_MEMORY;
396 		}
397 		return 0;
398 	}
399 
400 	switch (sdl->sdl_type) {
401 	/*
402 	 * The following have zero-length addresses.
403 	 * IFT_ATM	(net/if_atmsubr.c)
404 	 * IFT_FAITH	(net/if_faith.c)
405 	 * IFT_GIF	(net/if_gif.c)
406 	 * IFT_LOOP	(net/if_loop.c)
407 	 * IFT_PPP	(net/if_ppp.c, net/if_spppsubr.c)
408 	 * IFT_SLIP	(net/if_sl.c, net/if_strip.c)
409 	 * IFT_STF	(net/if_stf.c)
410 	 * IFT_L2VLAN	(net/if_vlan.c)
411 	 * IFT_BRIDGE (net/if_bridge.h>
412 	 */
413 	/*
414 	 * The following use IPv4 addresses as link-layer addresses:
415 	 * IFT_OTHER	(net/if_gre.c)
416 	 * IFT_OTHER	(netinet/ip_ipip.c)
417 	 */
418 	/* default below is believed correct for all these. */
419 	case IFT_ARCNET:
420 	case IFT_ETHER:
421 	case IFT_FDDI:
422 	case IFT_HIPPI:
423 	case IFT_ISO88025:
424 	default:
425 		return hexname((u_int8_t *)LLADDR(sdl), (size_t)sdl->sdl_alen,
426 		    host, hostlen);
427 	}
428 }
429 
430 static int
431 hexname(const u_int8_t *cp, size_t len, char *host, size_t hostlen)
432 {
433 	int i, n;
434 	char *outp = host;
435 
436 	*outp = '\0';
437 	for (i = 0; i < len; i++) {
438 		n = snprintf(outp, hostlen, "%s%02x",
439 		    i ? ":" : "", cp[i]);
440 		if (n < 0 || n >= hostlen) {
441 			*host = '\0';
442 			return EAI_MEMORY;
443 		}
444 		outp += n;
445 		hostlen -= n;
446 	}
447 	return 0;
448 }
449