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getnameinfo.c revision 1.21 
      1 /*	$NetBSD: getnameinfo.c,v 1.21 2000/08/07 16:18:45 itojun Exp $	*/
      2 /*	$KAME: getnameinfo.c,v 1.44 2000/08/06 16:43:17 itojun Exp $	*/
      3 
      4 /*
      5  * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
      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) NI_WITHSCOPEID when called with global address,
     42  *   and sin6_scope_id filled
     43  */
     44 
     45 #include <sys/cdefs.h>
     46 #if defined(LIBC_SCCS) && !defined(lint)
     47 __RCSID("$NetBSD: getnameinfo.c,v 1.21 2000/08/07 16:18:45 itojun Exp $");
     48 #endif /* LIBC_SCCS and not lint */
     49 
     50 #include "namespace.h"
     51 #include <sys/types.h>
     52 #include <sys/socket.h>
     53 #include <net/if.h>
     54 #include <netinet/in.h>
     55 #include <arpa/inet.h>
     56 #include <arpa/nameser.h>
     57 #include <netdb.h>
     58 #include <resolv.h>
     59 #include <string.h>
     60 #include <stddef.h>
     61 
     62 #ifdef __weak_alias
     63 __weak_alias(getnameinfo,_getnameinfo)
     64 #endif
     65 
     66 #define SUCCESS 0
     67 #define ANY 0
     68 #define YES 1
     69 #define NO  0
     70 
     71 static struct afd {
     72 	int a_af;
     73 	int a_addrlen;
     74 	int a_socklen;
     75 	int a_off;
     76 } afdl [] = {
     77 #ifdef INET6
     78 	{PF_INET6, sizeof(struct in6_addr), sizeof(struct sockaddr_in6),
     79 		offsetof(struct sockaddr_in6, sin6_addr)},
     80 #endif
     81 	{PF_INET, sizeof(struct in_addr), sizeof(struct sockaddr_in),
     82 		offsetof(struct sockaddr_in, sin_addr)},
     83 	{0, 0, 0},
     84 };
     85 
     86 struct sockinet {
     87 	u_char	si_len;
     88 	u_char	si_family;
     89 	u_short	si_port;
     90 };
     91 
     92 #ifdef INET6
     93 static int ip6_parsenumeric __P((const struct sockaddr *, const char *, char *,
     94 				 size_t, int));
     95 static int ip6_sa2str __P((const struct sockaddr_in6 *, char *, size_t, int));
     96 #endif
     97 
     98 /* 2553bis: use EAI_xx for getnameinfo */
     99 #define ENI_NOSOCKET 	EAI_FAIL		/*XXX*/
    100 #define ENI_NOSERVNAME	EAI_NONAME
    101 #define ENI_NOHOSTNAME	EAI_NONAME
    102 #define ENI_MEMORY	EAI_MEMORY
    103 #define ENI_SYSTEM	EAI_SYSTEM
    104 #define ENI_FAMILY	EAI_FAMILY
    105 #define ENI_SALEN	EAI_FAMILY
    106 
    107 int
    108 getnameinfo(sa, salen, host, hostlen, serv, servlen, flags)
    109 	const struct sockaddr *sa;
    110 	socklen_t salen;
    111 	char *host;
    112 	size_t hostlen;
    113 	char *serv;
    114 	size_t servlen;
    115 	int flags;
    116 {
    117 	struct afd *afd;
    118 	struct servent *sp;
    119 	struct hostent *hp;
    120 	u_short port;
    121 	int family, i;
    122 	const char *addr;
    123 	u_int32_t v4a;
    124 	char numserv[512];
    125 	char numaddr[512];
    126 
    127 	if (sa == NULL)
    128 		return ENI_NOSOCKET;
    129 
    130 #ifdef BSD4_4
    131 	if (sa->sa_len != salen)
    132 		return ENI_SALEN;
    133 #endif
    134 
    135 	family = sa->sa_family;
    136 	for (i = 0; afdl[i].a_af; i++)
    137 		if (afdl[i].a_af == family) {
    138 			afd = &afdl[i];
    139 			goto found;
    140 		}
    141 	return ENI_FAMILY;
    142 
    143  found:
    144 	if (salen != afd->a_socklen)
    145 		return ENI_SALEN;
    146 
    147 	/* network byte order */
    148 	port = ((const struct sockinet *)(const void *)sa)->si_port;
    149 	addr = (const char *)(const void *)sa + afd->a_off;
    150 
    151 	if (serv == NULL || servlen == 0) {
    152 		/*
    153 		 * do nothing in this case.
    154 		 * in case you are wondering if "&&" is more correct than
    155 		 * "||" here: RFC2553 says that serv == NULL OR servlen == 0
    156 		 * means that the caller does not want the result.
    157 		 */
    158 	} else {
    159 		if (flags & NI_NUMERICSERV)
    160 			sp = NULL;
    161 		else {
    162 			sp = getservbyport(port,
    163 				(flags & NI_DGRAM) ? "udp" : "tcp");
    164 		}
    165 		if (sp) {
    166 			if (strlen(sp->s_name) > servlen)
    167 				return ENI_MEMORY;
    168 			strcpy(serv, sp->s_name);
    169 		} else {
    170 			snprintf(numserv, sizeof(numserv), "%d", ntohs(port));
    171 			if (strlen(numserv) > servlen)
    172 				return ENI_MEMORY;
    173 			strcpy(serv, numserv);
    174 		}
    175 	}
    176 
    177 	switch (sa->sa_family) {
    178 	case AF_INET:
    179 		v4a = (u_int32_t)
    180 		    ntohl(((const struct sockaddr_in *)
    181 		    (const void *)sa)->sin_addr.s_addr);
    182 		if (IN_MULTICAST(v4a) || IN_EXPERIMENTAL(v4a))
    183 			flags |= NI_NUMERICHOST;
    184 		v4a >>= IN_CLASSA_NSHIFT;
    185 		if (v4a == 0)
    186 			flags |= NI_NUMERICHOST;
    187 		break;
    188 #ifdef INET6
    189 	case AF_INET6:
    190 	    {
    191 		const struct sockaddr_in6 *sin6;
    192 		sin6 = (const struct sockaddr_in6 *)(const void *)sa;
    193 		switch (sin6->sin6_addr.s6_addr[0]) {
    194 		case 0x00:
    195 			if (IN6_IS_ADDR_V4MAPPED(&sin6->sin6_addr))
    196 				;
    197 			else if (IN6_IS_ADDR_LOOPBACK(&sin6->sin6_addr))
    198 				;
    199 			else
    200 				flags |= NI_NUMERICHOST;
    201 			break;
    202 		default:
    203 			if (IN6_IS_ADDR_LINKLOCAL(&sin6->sin6_addr)) {
    204 				flags |= NI_NUMERICHOST;
    205 			}
    206 			else if (IN6_IS_ADDR_MULTICAST(&sin6->sin6_addr))
    207 				flags |= NI_NUMERICHOST;
    208 			break;
    209 		}
    210 	    }
    211 		break;
    212 #endif
    213 	}
    214 	if (host == NULL || hostlen == 0) {
    215 		/*
    216 		 * do nothing in this case.
    217 		 * in case you are wondering if "&&" is more correct than
    218 		 * "||" here: RFC2553 says that host == NULL OR hostlen == 0
    219 		 * means that the caller does not want the result.
    220 		 */
    221 	} else if (flags & NI_NUMERICHOST) {
    222 		int numaddrlen;
    223 
    224 		/* NUMERICHOST and NAMEREQD conflicts with each other */
    225 		if (flags & NI_NAMEREQD)
    226 			return ENI_NOHOSTNAME;
    227 
    228 		switch(afd->a_af) {
    229 #ifdef INET6
    230 		case AF_INET6:
    231 		{
    232 			int error;
    233 
    234 			if ((error = ip6_parsenumeric(sa, addr, host,
    235 						      hostlen, flags)) != 0)
    236 				return(error);
    237 			break;
    238 		}
    239 #endif
    240 		default:
    241 			if (inet_ntop(afd->a_af, addr, numaddr, sizeof(numaddr))
    242 			    == NULL)
    243 				return ENI_SYSTEM;
    244 			numaddrlen = strlen(numaddr);
    245 			if (numaddrlen + 1 > hostlen) /* don't forget terminator */
    246 				return ENI_MEMORY;
    247 			strcpy(host, numaddr);
    248 			break;
    249 		}
    250 	} else {
    251 		hp = gethostbyaddr(addr, afd->a_addrlen, afd->a_af);
    252 
    253 		if (hp) {
    254 #if 0
    255 			/*
    256 			 * commented out, since "for local host" is not
    257 			 * implemented here - see RFC2553 p30
    258 			 */
    259 			if (flags & NI_NOFQDN) {
    260 				char *p;
    261 				p = strchr(hp->h_name, '.');
    262 				if (p)
    263 					*p = '\0';
    264 			}
    265 #endif
    266 			if (strlen(hp->h_name) > hostlen) {
    267 				return ENI_MEMORY;
    268 			}
    269 			strcpy(host, hp->h_name);
    270 		} else {
    271 			if (flags & NI_NAMEREQD)
    272 				return ENI_NOHOSTNAME;
    273 			switch(afd->a_af) {
    274 #ifdef INET6
    275 			case AF_INET6:
    276 			{
    277 				int error;
    278 
    279 				if ((error = ip6_parsenumeric(sa, addr, host,
    280 							      hostlen,
    281 							      flags)) != 0)
    282 					return(error);
    283 				break;
    284 			}
    285 #endif
    286 			default:
    287 				if (inet_ntop(afd->a_af, addr, host,
    288 				    hostlen) == NULL)
    289 					return ENI_SYSTEM;
    290 				break;
    291 			}
    292 		}
    293 	}
    294 	return SUCCESS;
    295 }
    296 
    297 #ifdef INET6
    298 static int
    299 ip6_parsenumeric(sa, addr, host, hostlen, flags)
    300 	const struct sockaddr *sa;
    301 	const char *addr;
    302 	char *host;
    303 	size_t hostlen;
    304 	int flags;
    305 {
    306 	int numaddrlen;
    307 	char numaddr[512];
    308 
    309 	if (inet_ntop(AF_INET6, addr, numaddr, sizeof(numaddr))
    310 	    == NULL)
    311 		return ENI_SYSTEM;
    312 
    313 	numaddrlen = strlen(numaddr);
    314 	if (numaddrlen + 1 > hostlen) /* don't forget terminator */
    315 		return ENI_MEMORY;
    316 	strcpy(host, numaddr);
    317 
    318 #ifdef NI_WITHSCOPEID
    319 	if (((const struct sockaddr_in6 *)(const void *)sa)->sin6_scope_id) {
    320 		if (flags & NI_WITHSCOPEID)
    321 		{
    322 			char scopebuf[MAXHOSTNAMELEN];
    323 			int scopelen;
    324 
    325 			/* ip6_sa2str never fails */
    326 			scopelen = ip6_sa2str(
    327 			    (const struct sockaddr_in6 *)(const void *)sa,
    328 			    scopebuf, sizeof(scopebuf), 0);
    329 			if (scopelen + 1 + numaddrlen + 1 > hostlen)
    330 				return ENI_MEMORY;
    331 			/*
    332 			 * construct <numeric-addr><delim><scopeid>
    333 			 */
    334 			memcpy(host + numaddrlen + 1, scopebuf,
    335 			    (size_t)scopelen);
    336 			host[numaddrlen] = SCOPE_DELIMITER;
    337 			host[numaddrlen + 1 + scopelen] = '\0';
    338 		}
    339 	}
    340 #endif /* NI_WITHSCOPEID */
    341 
    342 	return 0;
    343 }
    344 
    345 /* ARGSUSED */
    346 static int
    347 ip6_sa2str(sa6, buf, bufsiz, flags)
    348 	const struct sockaddr_in6 *sa6;
    349 	char *buf;
    350 	size_t bufsiz;
    351 	int flags;
    352 {
    353 	unsigned int ifindex = (unsigned int)sa6->sin6_scope_id;
    354 	const struct in6_addr *a6 = &sa6->sin6_addr;
    355 
    356 #ifdef notyet
    357 	if (flags & NI_NUMERICSCOPE) {
    358 		return(snprintf(buf, bufsiz, "%d", sa6->sin6_scope_id));
    359 	}
    360 #endif
    361 
    362 	/* if_indextoname() does not take buffer size.  not a good api... */
    363 	if ((IN6_IS_ADDR_LINKLOCAL(a6) || IN6_IS_ADDR_MC_LINKLOCAL(a6)) &&
    364 	    bufsiz >= IF_NAMESIZE) {
    365 		char *p = if_indextoname(ifindex, buf);
    366 		if (p) {
    367 			return(strlen(p));
    368 		}
    369 	}
    370 
    371 	/* last resort */
    372 	return(snprintf(buf, bufsiz, "%u", sa6->sin6_scope_id));
    373 }
    374 #endif /* INET6 */
    375