getnameinfo.c revision 100628 
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 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 *    notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 *    notice, this list of conditions and the following disclaimer in the
14 *    documentation and/or other materials provided with the distribution.
15 * 3. Neither the name of the project nor the names of its contributors
16 *    may be used to endorse or promote products derived from this software
17 *    without specific prior written permission.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22 * ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29 * SUCH DAMAGE.
30 */
31
32/*
33 * Issues to be discussed:
34 * - Thread safe-ness must be checked
35 * - RFC2553 says that we should raise error on short buffer.  X/Open says
36 *   we need to truncate the result.  We obey RFC2553 (and X/Open should be
37 *   modified).  ipngwg rough consensus seems to follow RFC2553.
38 * - What is "local" in NI_FQDN?
39 * - NI_NAMEREQD and NI_NUMERICHOST conflict with each other.
40 * - (KAME extension) always attach textual scopeid (fe80::1%lo0), if
41 *   sin6_scope_id is filled - standardization status?
42 *   XXX breaks backward compat for code that expects no scopeid.
43 *   beware on merge.
44 */
45
46#include <sys/cdefs.h>
47__FBSDID("$FreeBSD: head/lib/libc/net/getnameinfo.c 100628 2002-07-24 18:58:32Z ume $");
48
49#include <sys/types.h>
50#include <sys/socket.h>
51#include <net/if.h>
52#include <netinet/in.h>
53#include <arpa/inet.h>
54#include <arpa/nameser.h>
55#include <netdb.h>
56#include <resolv.h>
57#include <string.h>
58#include <stddef.h>
59#include <errno.h>
60
61static const struct afd {
62	int a_af;
63	int a_addrlen;
64	int a_socklen;
65	int a_off;
66} afdl [] = {
67#ifdef INET6
68	{PF_INET6, sizeof(struct in6_addr), sizeof(struct sockaddr_in6),
69		offsetof(struct sockaddr_in6, sin6_addr)},
70#endif
71	{PF_INET, sizeof(struct in_addr), sizeof(struct sockaddr_in),
72		offsetof(struct sockaddr_in, sin_addr)},
73	{0, 0, 0},
74};
75
76struct sockinet {
77	u_char	si_len;
78	u_char	si_family;
79	u_short	si_port;
80};
81
82#ifdef INET6
83static int ip6_parsenumeric(const struct sockaddr *, const char *, char *,
84    size_t, int);
85static int ip6_sa2str(const struct sockaddr_in6 *, char *, size_t, int);
86#endif
87
88int
89getnameinfo(sa, salen, host, hostlen, serv, servlen, flags)
90	const struct sockaddr *sa;
91	socklen_t salen;
92	char *host;
93	size_t hostlen;
94	char *serv;
95	size_t servlen;
96	int flags;
97{
98	const struct afd *afd;
99	struct servent *sp;
100	struct hostent *hp;
101	u_short port;
102	int family, i;
103	const char *addr;
104	u_int32_t v4a;
105	int h_error;
106	char numserv[512];
107	char numaddr[512];
108
109	if (sa == NULL)
110		return EAI_FAIL;
111
112	if (sa->sa_len != salen)
113		return EAI_FAIL;
114
115	family = sa->sa_family;
116	for (i = 0; afdl[i].a_af; i++)
117		if (afdl[i].a_af == family) {
118			afd = &afdl[i];
119			goto found;
120		}
121	return EAI_FAMILY;
122
123 found:
124	if (salen != afd->a_socklen)
125		return EAI_FAIL;
126
127	/* network byte order */
128	port = ((const struct sockinet *)sa)->si_port;
129	addr = (const char *)sa + afd->a_off;
130
131	if (serv == NULL || servlen == 0) {
132		/*
133		 * do nothing in this case.
134		 * in case you are wondering if "&&" is more correct than
135		 * "||" here: rfc2553bis-03 says that serv == NULL OR
136		 * servlen == 0 means that the caller does not want the result.
137		 */
138	} else {
139		if (flags & NI_NUMERICSERV)
140			sp = NULL;
141		else {
142			sp = getservbyport(port,
143				(flags & NI_DGRAM) ? "udp" : "tcp");
144		}
145		if (sp) {
146			if (strlen(sp->s_name) + 1 > servlen)
147				return EAI_MEMORY;
148			strlcpy(serv, sp->s_name, servlen);
149		} else {
150			snprintf(numserv, sizeof(numserv), "%u", ntohs(port));
151			if (strlen(numserv) + 1 > servlen)
152				return EAI_MEMORY;
153			strlcpy(serv, numserv, servlen);
154		}
155	}
156
157	switch (sa->sa_family) {
158	case AF_INET:
159		v4a = (u_int32_t)
160		    ntohl(((const struct sockaddr_in *)sa)->sin_addr.s_addr);
161		if (IN_MULTICAST(v4a) || IN_EXPERIMENTAL(v4a))
162			flags |= NI_NUMERICHOST;
163		v4a >>= IN_CLASSA_NSHIFT;
164		if (v4a == 0)
165			flags |= NI_NUMERICHOST;
166		break;
167#ifdef INET6
168	case AF_INET6:
169	    {
170		const struct sockaddr_in6 *sin6;
171		sin6 = (const struct sockaddr_in6 *)sa;
172		switch (sin6->sin6_addr.s6_addr[0]) {
173		case 0x00:
174			if (IN6_IS_ADDR_V4MAPPED(&sin6->sin6_addr))
175				;
176			else if (IN6_IS_ADDR_LOOPBACK(&sin6->sin6_addr))
177				;
178			else
179				flags |= NI_NUMERICHOST;
180			break;
181		default:
182			if (IN6_IS_ADDR_LINKLOCAL(&sin6->sin6_addr)) {
183				flags |= NI_NUMERICHOST;
184			}
185			else if (IN6_IS_ADDR_MULTICAST(&sin6->sin6_addr))
186				flags |= NI_NUMERICHOST;
187			break;
188		}
189	    }
190		break;
191#endif
192	}
193	if (host == NULL || hostlen == 0) {
194		/*
195		 * do nothing in this case.
196		 * in case you are wondering if "&&" is more correct than
197		 * "||" here: rfc2553bis-03 says that host == NULL or
198		 * hostlen == 0 means that the caller does not want the result.
199		 */
200	} else if (flags & NI_NUMERICHOST) {
201		int numaddrlen;
202
203		/* NUMERICHOST and NAMEREQD conflicts with each other */
204		if (flags & NI_NAMEREQD)
205			return EAI_NONAME;
206
207		switch(afd->a_af) {
208#ifdef INET6
209		case AF_INET6:
210		{
211			int error;
212
213			if ((error = ip6_parsenumeric(sa, addr, host,
214						      hostlen, flags)) != 0)
215				return(error);
216			break;
217		}
218#endif
219		default:
220			if (inet_ntop(afd->a_af, addr, numaddr, sizeof(numaddr))
221			    == NULL)
222				return EAI_SYSTEM;
223			numaddrlen = strlen(numaddr);
224			if (numaddrlen + 1 > hostlen) /* don't forget terminator */
225				return EAI_MEMORY;
226			strlcpy(host, numaddr, hostlen);
227			break;
228		}
229	} else {
230		hp = getipnodebyaddr(addr, afd->a_addrlen, afd->a_af, &h_error);
231
232		if (hp) {
233#if 0
234			/*
235			 * commented out, since "for local host" is not
236			 * implemented here - see RFC2553 p30
237			 */
238			if (flags & NI_NOFQDN) {
239				char *p;
240				p = strchr(hp->h_name, '.');
241				if (p)
242					*p = '\0';
243			}
244#endif
245			if (strlen(hp->h_name) + 1 > hostlen) {
246				freehostent(hp);
247				return EAI_MEMORY;
248			}
249			strlcpy(host, hp->h_name, hostlen);
250			freehostent(hp);
251		} else {
252			if (flags & NI_NAMEREQD)
253				return EAI_NONAME;
254			switch(afd->a_af) {
255#ifdef INET6
256			case AF_INET6:
257			{
258				int error;
259
260				if ((error = ip6_parsenumeric(sa, addr, host,
261							      hostlen,
262							      flags)) != 0)
263					return(error);
264				break;
265			}
266#endif
267			default:
268				if (inet_ntop(afd->a_af, addr, host,
269				    hostlen) == NULL)
270					return EAI_SYSTEM;
271				break;
272			}
273		}
274	}
275	return(0);
276}
277
278#ifdef INET6
279static int
280ip6_parsenumeric(sa, addr, host, hostlen, flags)
281	const struct sockaddr *sa;
282	const char *addr;
283	char *host;
284	size_t hostlen;
285	int flags;
286{
287	int numaddrlen;
288	char numaddr[512];
289
290	if (inet_ntop(AF_INET6, addr, numaddr, sizeof(numaddr)) == NULL)
291		return EAI_SYSTEM;
292
293	numaddrlen = strlen(numaddr);
294	if (numaddrlen + 1 > hostlen) /* don't forget terminator */
295		return EAI_MEMORY;
296	strlcpy(host, numaddr, hostlen);
297
298	if (((const struct sockaddr_in6 *)sa)->sin6_scope_id) {
299		char zonebuf[MAXHOSTNAMELEN];
300		int zonelen;
301
302		zonelen = ip6_sa2str(
303		    (const struct sockaddr_in6 *)(const void *)sa,
304		    zonebuf, sizeof(zonebuf), flags);
305		if (zonelen < 0)
306			return EAI_MEMORY;
307		if (zonelen + 1 + numaddrlen + 1 > hostlen)
308			return EAI_MEMORY;
309
310		/* construct <numeric-addr><delim><zoneid> */
311		memcpy(host + numaddrlen + 1, zonebuf,
312		    (size_t)zonelen);
313		host[numaddrlen] = SCOPE_DELIMITER;
314		host[numaddrlen + 1 + zonelen] = '\0';
315	}
316
317	return 0;
318}
319
320/* ARGSUSED */
321static int
322ip6_sa2str(sa6, buf, bufsiz, flags)
323	const struct sockaddr_in6 *sa6;
324	char *buf;
325	size_t bufsiz;
326	int flags;
327{
328	unsigned int ifindex;
329	const struct in6_addr *a6;
330	int n;
331
332	ifindex = (unsigned int)sa6->sin6_scope_id;
333	a6 = &sa6->sin6_addr;
334
335#ifdef NI_NUMERICSCOPE
336	if ((flags & NI_NUMERICSCOPE) != 0) {
337		n = snprintf(buf, bufsiz, "%u", sa6->sin6_scope_id);
338		if (n < 0 || n >= bufsiz)
339			return -1;
340		else
341			return n;
342	}
343#endif
344
345	/* if_indextoname() does not take buffer size.  not a good api... */
346	if ((IN6_IS_ADDR_LINKLOCAL(a6) || IN6_IS_ADDR_MC_LINKLOCAL(a6) ||
347	     IN6_IS_ADDR_MC_NODELOCAL(a6)) && bufsiz >= IF_NAMESIZE) {
348		char *p = if_indextoname(ifindex, buf);
349		if (p) {
350			return(strlen(p));
351		}
352	}
353
354	/* last resort */
355	n = snprintf(buf, bufsiz, "%u", sa6->sin6_scope_id);
356	if (n < 0 || n >= bufsiz)
357		return -1;
358	else
359		return n;
360}
361#endif /* INET6 */
362