xref: /illumos-gate/usr/src/lib/libresolv2/common/irs/getnameinfo.c (revision 9b9d39d2a32ff806d2431dbcc50968ef1e6d46b2)
1 /*
2  * Issues to be discussed:
3  * - Thread safe-ness must be checked
4  */
5 
6 #if ( defined(__linux__) || defined(__linux) || defined(LINUX) )
7 #ifndef IF_NAMESIZE
8 # ifdef IFNAMSIZ
9 #  define IF_NAMESIZE  IFNAMSIZ
10 # else
11 #  define IF_NAMESIZE 16
12 # endif
13 #endif
14 #endif
15 
16 /*
17  * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
18  * All rights reserved.
19  *
20  * Redistribution and use in source and binary forms, with or without
21  * modification, are permitted provided that the following conditions
22  * are met:
23  * 1. Redistributions of source code must retain the above copyright
24  *    notice, this list of conditions and the following disclaimer.
25  * 2. Redistributions in binary form must reproduce the above copyright
26  *    notice, this list of conditions and the following disclaimer in the
27  *    documentation and/or other materials provided with the distribution.
28  * 3. All advertising materials mentioning features or use of this software
29  *    must display the following acknowledgement:
30  *    This product includes software developed by WIDE Project and
31  *    its contributors.
32  * 4. Neither the name of the project nor the names of its contributors
33  *    may be used to endorse or promote products derived from this software
34  *    without specific prior written permission.
35  *
36  * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
37  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
38  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
39  * ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
40  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
41  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
42  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
43  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
44  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
45  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
46  * SUCH DAMAGE.
47  */
48 
49 #include <port_before.h>
50 
51 #include <sys/types.h>
52 #include <sys/socket.h>
53 
54 #include <netinet/in.h>
55 #include <arpa/nameser.h>
56 #include <arpa/inet.h>
57 #include <net/if.h>
58 
59 #include <netdb.h>
60 #include <resolv.h>
61 #include <string.h>
62 #include <stddef.h>
63 
64 #include <port_after.h>
65 
66 /*%
67  * Note that a_off will be dynamically adjusted so that to be consistent
68  * with the definition of sockaddr_in{,6}.
69  * The value presented below is just a guess.
70  */
71 static struct afd {
72 	int a_af;
73 	int a_addrlen;
74 	size_t a_socklen;
75 	int a_off;
76 } afdl [] = {
77 	/* first entry is linked last... */
78 	{PF_INET, sizeof(struct in_addr), sizeof(struct sockaddr_in),
79 	 offsetof(struct sockaddr_in, sin_addr)},
80 	{PF_INET6, sizeof(struct in6_addr), sizeof(struct sockaddr_in6),
81 	 offsetof(struct sockaddr_in6, sin6_addr)},
82 	{0, 0, 0, 0},
83 };
84 
85 struct sockinet {
86 #ifdef HAVE_SA_LEN
87 	u_char	si_len;
88 #endif
89 	u_char	si_family;
90 	u_short	si_port;
91 };
92 
93 static int ip6_parsenumeric __P((const struct sockaddr *, const char *, char *,
94 				 size_t, int));
95 #ifdef HAVE_SIN6_SCOPE_ID
96 static int ip6_sa2str __P((const struct sockaddr_in6 *, char *, size_t, int));
97 #endif
98 
99 int
100 getnameinfo(sa, salen, host, hostlen, serv, servlen, flags)
101 	const struct sockaddr *sa;
102 	size_t salen;
103 	char *host;
104 	size_t hostlen;
105 	char *serv;
106 	size_t servlen;
107 	int flags;
108 {
109 	struct afd *afd;
110 	struct servent *sp;
111 	struct hostent *hp;
112 	u_short port;
113 #ifdef HAVE_SA_LEN
114 	size_t len;
115 #endif
116 	int family, i;
117 	const char *addr;
118 	char *p;
119 	char numserv[512];
120 	char numaddr[512];
121 	const struct sockaddr_in6 *sin6;
122 
123 	if (sa == NULL)
124 		return EAI_FAIL;
125 
126 #ifdef HAVE_SA_LEN
127 	len = sa->sa_len;
128 	if (len != salen) return EAI_FAIL;
129 #endif
130 
131 	family = sa->sa_family;
132 	for (i = 0; afdl[i].a_af; i++)
133 		if (afdl[i].a_af == family) {
134 			afd = &afdl[i];
135 			goto found;
136 		}
137 	return EAI_FAMILY;
138 
139  found:
140 	if (salen != afd->a_socklen) return EAI_FAIL;
141 
142 	port = ((const struct sockinet *)sa)->si_port; /*%< network byte order */
143 	addr = (const char *)sa + afd->a_off;
144 
145 	if (serv == NULL || servlen == 0U) {
146 		/*
147 		 * rfc2553bis says that serv == NULL or servlen == 0 means that
148 		 * the caller does not want the result.
149 		 */
150 	} else if (flags & NI_NUMERICSERV) {
151 		sprintf(numserv, "%d", ntohs(port));
152 		if (strlen(numserv) > servlen)
153 			return EAI_MEMORY;
154 		strcpy(serv, numserv);
155 	} else {
156 		sp = getservbyport(port, (flags & NI_DGRAM) ? "udp" : "tcp");
157 		if (sp) {
158 			if (strlen(sp->s_name) + 1 > servlen)
159 				return EAI_MEMORY;
160 			strcpy(serv, sp->s_name);
161 		} else
162 			return EAI_NONAME;
163 	}
164 
165 	switch (sa->sa_family) {
166 	case AF_INET:
167 		if (ntohl(*(const u_int32_t *)addr) >> IN_CLASSA_NSHIFT == 0)
168 			flags |= NI_NUMERICHOST;
169 		break;
170 	case AF_INET6:
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 			else if (IN6_IS_ADDR_MULTICAST(&sin6->sin6_addr))
185 				flags |= NI_NUMERICHOST;
186 			break;
187 		}
188 		break;
189 	}
190 	if (host == NULL || hostlen == 0U) {
191 		/*
192 		 * rfc2553bis says that host == NULL or hostlen == 0 means that
193 		 * the caller does not want the result.
194 		 */
195 	} else if (flags & NI_NUMERICHOST) {
196 		goto numeric;
197 	} else {
198 		hp = gethostbyaddr(addr, afd->a_addrlen, afd->a_af);
199 
200 		if (hp) {
201 			if (flags & NI_NOFQDN) {
202 				p = strchr(hp->h_name, '.');
203 				if (p) *p = '\0';
204 			}
205 			if (strlen(hp->h_name) + 1 > hostlen)
206 				return EAI_MEMORY;
207 			strcpy(host, hp->h_name);
208 		} else {
209 			if (flags & NI_NAMEREQD)
210 				return EAI_NONAME;
211 		  numeric:
212 			switch(afd->a_af) {
213 			case AF_INET6:
214 			{
215 				int error;
216 
217 				if ((error = ip6_parsenumeric(sa, addr, host,
218 							      hostlen,
219 							      flags)) != 0)
220 					return(error);
221 				break;
222 			}
223 
224 			default:
225 				if (inet_ntop(afd->a_af, addr, numaddr,
226 					      sizeof(numaddr)) == NULL)
227 					return EAI_NONAME;
228 				if (strlen(numaddr) + 1 > hostlen)
229 					return EAI_MEMORY;
230 				strcpy(host, numaddr);
231 			}
232 		}
233 	}
234 	return(0);
235 }
236 
237 static int
238 ip6_parsenumeric(const struct sockaddr *sa, const char *addr, char *host,
239 		 size_t hostlen, int flags)
240 {
241 	size_t numaddrlen;
242 	char numaddr[512];
243 
244 #ifndef HAVE_SIN6_SCOPE_ID
245 	UNUSED(sa);
246 	UNUSED(flags);
247 #endif
248 
249 	if (inet_ntop(AF_INET6, addr, numaddr, sizeof(numaddr))
250 	    == NULL)
251 		return EAI_SYSTEM;
252 
253 	numaddrlen = strlen(numaddr);
254 	if (numaddrlen + 1 > hostlen) /*%< don't forget terminator */
255 		return EAI_MEMORY;
256 	strcpy(host, numaddr);
257 
258 #ifdef HAVE_SIN6_SCOPE_ID
259 	if (((const struct sockaddr_in6 *)sa)->sin6_scope_id) {
260 		char scopebuf[MAXHOSTNAMELEN]; /*%< XXX */
261 		int scopelen;
262 
263 		/* ip6_sa2str never fails */
264 		scopelen = ip6_sa2str((const struct sockaddr_in6 *)sa,
265 				      scopebuf, sizeof(scopebuf), flags);
266 
267 		if (scopelen + 1 + numaddrlen + 1 > hostlen)
268 			return EAI_MEMORY;
269 
270 		/* construct <numeric-addr><delim><scopeid> */
271 		memcpy(host + numaddrlen + 1, scopebuf,
272 		       scopelen);
273 		host[numaddrlen] = SCOPE_DELIMITER;
274 		host[numaddrlen + 1 + scopelen] = '\0';
275 	}
276 #endif
277 
278 	return 0;
279 }
280 
281 #ifdef HAVE_SIN6_SCOPE_ID
282 /* ARGSUSED */
283 static int
284 ip6_sa2str(const struct sockaddr_in6 *sa6, char *buf,
285 	   size_t bufsiz, int flags)
286 {
287 #ifdef USE_IFNAMELINKID
288 	unsigned int ifindex = (unsigned int)sa6->sin6_scope_id;
289 	const struct in6_addr *a6 = &sa6->sin6_addr;
290 #endif
291 	char tmp[64];
292 
293 #ifdef NI_NUMERICSCOPE
294 	if (flags & NI_NUMERICSCOPE) {
295 		sprintf(tmp, "%u", sa6->sin6_scope_id);
296 		if (bufsiz != 0U) {
297 			strncpy(buf, tmp, bufsiz - 1);
298 			buf[bufsiz - 1] = '\0';
299 		}
300 		return(strlen(tmp));
301 	}
302 #endif
303 
304 #ifdef USE_IFNAMELINKID
305 	/*
306 	 * For a link-local address, convert the index to an interface
307 	 * name, assuming a one-to-one mapping between links and interfaces.
308 	 * Note, however, that this assumption is stronger than the
309 	 * specification of the scoped address architecture;  the
310 	 * specficication says that more than one interfaces can belong to
311 	 * a single link.
312 	 */
313 
314 	/* if_indextoname() does not take buffer size.  not a good api... */
315 	if ((IN6_IS_ADDR_LINKLOCAL(a6) || IN6_IS_ADDR_MC_LINKLOCAL(a6)) &&
316 	    bufsiz >= IF_NAMESIZE) {
317 		char *p = if_indextoname(ifindex, buf);
318 		if (p) {
319 			return(strlen(p));
320 		}
321 	}
322 #endif
323 
324 	/* last resort */
325 	sprintf(tmp, "%u", sa6->sin6_scope_id);
326 	if (bufsiz != 0U) {
327 		strncpy(buf, tmp, bufsiz - 1);
328 		buf[bufsiz - 1] = '\0';
329 	}
330 	return(strlen(tmp));
331 }
332 #endif
333 
334 /*! \file */
335