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getnameinfo.c revision 1.29 
      1 /*	$NetBSD: getnameinfo.c,v 1.29 2001/10/04 23:09:04 bjh21 Exp $	*/
      2 /*	$KAME: getnameinfo.c,v 1.45 2000/09/25 22:43:56 itojun Exp $	*/
      3 
      4 /*
      5  * Copyright (c) 2000 Ben Harris.
      6  * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
      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) NI_WITHSCOPEID when called with global address,
     43  *   and sin6_scope_id filled
     44  */
     45 
     46 #include <sys/cdefs.h>
     47 #if defined(LIBC_SCCS) && !defined(lint)
     48 __RCSID("$NetBSD: getnameinfo.c,v 1.29 2001/10/04 23:09:04 bjh21 Exp $");
     49 #endif /* LIBC_SCCS and not lint */
     50 
     51 #include "namespace.h"
     52 #include <sys/types.h>
     53 #include <sys/socket.h>
     54 #include <net/if.h>
     55 #include <net/if_dl.h>
     56 #include <net/if_ieee1394.h>
     57 #include <net/if_types.h>
     58 #include <netinet/in.h>
     59 #include <arpa/inet.h>
     60 #include <arpa/nameser.h>
     61 #include <assert.h>
     62 #include <netdb.h>
     63 #include <resolv.h>
     64 #include <stddef.h>
     65 #include <string.h>
     66 
     67 #ifdef __weak_alias
     68 __weak_alias(getnameinfo,_getnameinfo)
     69 #endif
     70 
     71 #define SUCCESS 0
     72 #define ANY 0
     73 #define YES 1
     74 #define NO  0
     75 
     76 static const struct afd {
     77 	int		a_af;
     78 	socklen_t	a_addrlen;
     79 	socklen_t	a_socklen;
     80 	int		a_off;
     81 } afdl [] = {
     82 #ifdef INET6
     83 	{PF_INET6, sizeof(struct in6_addr), sizeof(struct sockaddr_in6),
     84 		offsetof(struct sockaddr_in6, sin6_addr)},
     85 #endif
     86 	{PF_INET, sizeof(struct in_addr), sizeof(struct sockaddr_in),
     87 		offsetof(struct sockaddr_in, sin_addr)},
     88 	{0, 0, 0},
     89 };
     90 
     91 struct sockinet {
     92 	u_char	si_len;
     93 	u_char	si_family;
     94 	u_short	si_port;
     95 };
     96 
     97 static int getnameinfo_inet __P((const struct sockaddr *, socklen_t, char *,
     98     size_t, char *, size_t, int));
     99 #ifdef INET6
    100 static int ip6_parsenumeric __P((const struct sockaddr *, const char *, char *,
    101 				 size_t, int));
    102 static int ip6_sa2str __P((const struct sockaddr_in6 *, char *, size_t, int));
    103 #endif
    104 static int getnameinfo_link __P((const struct sockaddr *, socklen_t, char *,
    105     size_t, char *, size_t, int));
    106 static int hexname __P((u_int8_t *, size_t, char *, size_t));
    107 
    108 /* 2553bis: use EAI_xx for getnameinfo */
    109 #define ENI_NOSOCKET 	EAI_FAIL		/*XXX*/
    110 #define ENI_NOSERVNAME	EAI_NONAME
    111 #define ENI_NOHOSTNAME	EAI_NONAME
    112 #define ENI_MEMORY	EAI_MEMORY
    113 #define ENI_SYSTEM	EAI_SYSTEM
    114 #define ENI_FAMILY	EAI_FAMILY
    115 #define ENI_SALEN	EAI_FAMILY
    116 
    117 /*
    118  * Top-level getnameinfo() code.  Look at the address family, and pick an
    119  * appropriate function to call.
    120  */
    121 int
    122 getnameinfo(sa, salen, host, hostlen, serv, servlen, flags)
    123 	const struct sockaddr *sa;
    124 	socklen_t salen;
    125 	char *host, *serv;
    126 	size_t hostlen, servlen;
    127 	int flags;
    128 {
    129 
    130 	switch (sa->sa_family) {
    131 	case AF_INET:
    132 	case AF_INET6:
    133 		return getnameinfo_inet(sa, salen, host, hostlen,
    134 		    serv, servlen, flags);
    135 	case AF_LINK:
    136 		return getnameinfo_link(sa, salen, host, hostlen,
    137 		    serv, servlen, flags);
    138 	default:
    139 		return EAI_FAMILY;
    140 	}
    141 }
    142 
    143 
    144 /*
    145  * getnameinfo_inet():
    146  * Format an IPv4 or IPv6 sockaddr into a printable string.
    147  */
    148 static int
    149 getnameinfo_inet(sa, salen, host, hostlen, serv, servlen, flags)
    150 	const struct sockaddr *sa;
    151 	socklen_t salen;
    152 	char *host;
    153 	size_t hostlen;
    154 	char *serv;
    155 	size_t servlen;
    156 	int flags;
    157 {
    158 	const struct afd *afd;
    159 	struct servent *sp;
    160 	struct hostent *hp;
    161 	u_short port;
    162 	int family, i;
    163 	const char *addr;
    164 	u_int32_t v4a;
    165 	char numserv[512];
    166 	char numaddr[512];
    167 
    168 	/* sa is checked below */
    169 	/* host may be NULL */
    170 	/* serv may be NULL */
    171 
    172 	if (sa == NULL)
    173 		return ENI_NOSOCKET;
    174 
    175 #ifdef BSD4_4
    176 	if (sa->sa_len != salen)
    177 		return ENI_SALEN;
    178 #endif
    179 
    180 	family = sa->sa_family;
    181 	for (i = 0; afdl[i].a_af; i++)
    182 		if (afdl[i].a_af == family) {
    183 			afd = &afdl[i];
    184 			goto found;
    185 		}
    186 	return ENI_FAMILY;
    187 
    188  found:
    189 	if (salen != afd->a_socklen)
    190 		return ENI_SALEN;
    191 
    192 	/* network byte order */
    193 	port = ((const struct sockinet *)(const void *)sa)->si_port;
    194 	addr = (const char *)(const void *)sa + afd->a_off;
    195 
    196 	if (serv == NULL || servlen == 0) {
    197 		/*
    198 		 * do nothing in this case.
    199 		 * in case you are wondering if "&&" is more correct than
    200 		 * "||" here: RFC2553 says that serv == NULL OR servlen == 0
    201 		 * means that the caller does not want the result.
    202 		 */
    203 	} else {
    204 		if (flags & NI_NUMERICSERV)
    205 			sp = NULL;
    206 		else {
    207 			sp = getservbyport(port,
    208 				(flags & NI_DGRAM) ? "udp" : "tcp");
    209 		}
    210 		if (sp) {
    211 			if (strlen(sp->s_name) + 1 > servlen)
    212 				return ENI_MEMORY;
    213 			strcpy(serv, sp->s_name);
    214 		} else {
    215 			snprintf(numserv, sizeof(numserv), "%d", ntohs(port));
    216 			if (strlen(numserv) + 1 > servlen)
    217 				return ENI_MEMORY;
    218 			strcpy(serv, numserv);
    219 		}
    220 	}
    221 
    222 	switch (sa->sa_family) {
    223 	case AF_INET:
    224 		v4a = (u_int32_t)
    225 		    ntohl(((const struct sockaddr_in *)
    226 		    (const void *)sa)->sin_addr.s_addr);
    227 		if (IN_MULTICAST(v4a) || IN_EXPERIMENTAL(v4a))
    228 			flags |= NI_NUMERICHOST;
    229 		v4a >>= IN_CLASSA_NSHIFT;
    230 		if (v4a == 0)
    231 			flags |= NI_NUMERICHOST;
    232 		break;
    233 #ifdef INET6
    234 	case AF_INET6:
    235 	    {
    236 		const struct sockaddr_in6 *sin6;
    237 		sin6 = (const struct sockaddr_in6 *)(const void *)sa;
    238 		switch (sin6->sin6_addr.s6_addr[0]) {
    239 		case 0x00:
    240 			if (IN6_IS_ADDR_V4MAPPED(&sin6->sin6_addr))
    241 				;
    242 			else if (IN6_IS_ADDR_LOOPBACK(&sin6->sin6_addr))
    243 				;
    244 			else
    245 				flags |= NI_NUMERICHOST;
    246 			break;
    247 		default:
    248 			if (IN6_IS_ADDR_LINKLOCAL(&sin6->sin6_addr)) {
    249 				flags |= NI_NUMERICHOST;
    250 			}
    251 			else if (IN6_IS_ADDR_MULTICAST(&sin6->sin6_addr))
    252 				flags |= NI_NUMERICHOST;
    253 			break;
    254 		}
    255 	    }
    256 		break;
    257 #endif
    258 	}
    259 	if (host == NULL || hostlen == 0) {
    260 		/*
    261 		 * do nothing in this case.
    262 		 * in case you are wondering if "&&" is more correct than
    263 		 * "||" here: RFC2553 says that host == NULL OR hostlen == 0
    264 		 * means that the caller does not want the result.
    265 		 */
    266 	} else if (flags & NI_NUMERICHOST) {
    267 		int numaddrlen;
    268 
    269 		/* NUMERICHOST and NAMEREQD conflicts with each other */
    270 		if (flags & NI_NAMEREQD)
    271 			return ENI_NOHOSTNAME;
    272 
    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, flags)) != 0)
    281 				return(error);
    282 			break;
    283 		}
    284 #endif
    285 		default:
    286 			if (inet_ntop(afd->a_af, addr, numaddr, sizeof(numaddr))
    287 			    == NULL)
    288 				return ENI_SYSTEM;
    289 			numaddrlen = strlen(numaddr);
    290 			if (numaddrlen + 1 > hostlen) /* don't forget terminator */
    291 				return ENI_MEMORY;
    292 			strcpy(host, numaddr);
    293 			break;
    294 		}
    295 	} else {
    296 		hp = gethostbyaddr(addr, afd->a_addrlen, afd->a_af);
    297 
    298 		if (hp) {
    299 #if 0
    300 			/*
    301 			 * commented out, since "for local host" is not
    302 			 * implemented here - see RFC2553 p30
    303 			 */
    304 			if (flags & NI_NOFQDN) {
    305 				char *p;
    306 				p = strchr(hp->h_name, '.');
    307 				if (p)
    308 					*p = '\0';
    309 			}
    310 #endif
    311 			if (strlen(hp->h_name) + 1 > hostlen) {
    312 				return ENI_MEMORY;
    313 			}
    314 			strcpy(host, hp->h_name);
    315 		} else {
    316 			if (flags & NI_NAMEREQD)
    317 				return ENI_NOHOSTNAME;
    318 			switch(afd->a_af) {
    319 #ifdef INET6
    320 			case AF_INET6:
    321 			{
    322 				int error;
    323 
    324 				if ((error = ip6_parsenumeric(sa, addr, host,
    325 							      hostlen,
    326 							      flags)) != 0)
    327 					return(error);
    328 				break;
    329 			}
    330 #endif
    331 			default:
    332 				if (inet_ntop(afd->a_af, addr, host,
    333 				    hostlen) == NULL)
    334 					return ENI_SYSTEM;
    335 				break;
    336 			}
    337 		}
    338 	}
    339 	return SUCCESS;
    340 }
    341 
    342 #ifdef INET6
    343 static int
    344 ip6_parsenumeric(sa, addr, host, hostlen, flags)
    345 	const struct sockaddr *sa;
    346 	const char *addr;
    347 	char *host;
    348 	size_t hostlen;
    349 	int flags;
    350 {
    351 	int numaddrlen;
    352 	char numaddr[512];
    353 
    354 	_DIAGASSERT(sa != NULL);
    355 	_DIAGASSERT(addr != NULL);
    356 	_DIAGASSERT(host != NULL);
    357 
    358 	if (inet_ntop(AF_INET6, addr, numaddr, sizeof(numaddr))
    359 	    == NULL)
    360 		return ENI_SYSTEM;
    361 
    362 	numaddrlen = strlen(numaddr);
    363 	if (numaddrlen + 1 > hostlen) /* don't forget terminator */
    364 		return ENI_MEMORY;
    365 	strcpy(host, numaddr);
    366 
    367 #ifdef NI_WITHSCOPEID
    368 	if (((const struct sockaddr_in6 *)(const void *)sa)->sin6_scope_id) {
    369 		if (flags & NI_WITHSCOPEID)
    370 		{
    371 			char scopebuf[MAXHOSTNAMELEN];
    372 			int scopelen;
    373 
    374 			scopelen = ip6_sa2str(
    375 			    (const struct sockaddr_in6 *)(const void *)sa,
    376 			    scopebuf, sizeof(scopebuf), 0);
    377 			if (scopelen < 0)
    378 				return ENI_MEMORY;
    379 			if (scopelen + 1 + numaddrlen + 1 > hostlen)
    380 				return ENI_MEMORY;
    381 			/*
    382 			 * construct <numeric-addr><delim><scopeid>
    383 			 */
    384 			memcpy(host + numaddrlen + 1, scopebuf,
    385 			    (size_t)scopelen);
    386 			host[numaddrlen] = SCOPE_DELIMITER;
    387 			host[numaddrlen + 1 + scopelen] = '\0';
    388 		}
    389 	}
    390 #endif /* NI_WITHSCOPEID */
    391 
    392 	return 0;
    393 }
    394 
    395 /* ARGSUSED */
    396 static int
    397 ip6_sa2str(sa6, buf, bufsiz, flags)
    398 	const struct sockaddr_in6 *sa6;
    399 	char *buf;
    400 	size_t bufsiz;
    401 	int flags;
    402 {
    403 	unsigned int ifindex;
    404 	const struct in6_addr *a6;
    405 	int n;
    406 
    407 	_DIAGASSERT(sa6 != NULL);
    408 	_DIAGASSERT(buf != NULL);
    409 
    410 	ifindex = (unsigned int)sa6->sin6_scope_id;
    411 	a6 = &sa6->sin6_addr;
    412 
    413 #ifdef NI_NUMERICSCOPE
    414 	if ((flags & NI_NUMERICSCOPE) != 0) {
    415 		n = snprintf(buf, bufsiz, "%u", sa6->sin6_scope_id);
    416 		if (n < 0 || n >= bufsiz)
    417 			return -1;
    418 		else
    419 			return n;
    420 	}
    421 #endif
    422 
    423 	/* if_indextoname() does not take buffer size.  not a good api... */
    424 	if ((IN6_IS_ADDR_LINKLOCAL(a6) || IN6_IS_ADDR_MC_LINKLOCAL(a6)) &&
    425 	    bufsiz >= IF_NAMESIZE) {
    426 		char *p = if_indextoname(ifindex, buf);
    427 		if (p) {
    428 			return(strlen(p));
    429 		}
    430 	}
    431 
    432 	/* last resort */
    433 	n = snprintf(buf, bufsiz, "%u", sa6->sin6_scope_id);
    434 	if (n < 0 || n >= bufsiz)
    435 		return -1;
    436 	else
    437 		return n;
    438 }
    439 #endif /* INET6 */
    440 
    441 
    442 /*
    443  * getnameinfo_link():
    444  * Format a link-layer address into a printable format, paying attention to
    445  * the interface type.
    446  */
    447 static int
    448 getnameinfo_link(const struct sockaddr *sa, socklen_t salen,
    449     char *host, size_t hostlen, char *serv, size_t servlen, int flags)
    450 {
    451 	const struct sockaddr_dl *sdl = (const struct sockaddr_dl *)sa;
    452 	struct ieee1394_hwaddr *iha;
    453 	int n;
    454 
    455 	if (serv != NULL && servlen > 0)
    456 		*serv = '\0';
    457 
    458 	if (sdl->sdl_nlen == 0 && sdl->sdl_alen == 0 && sdl->sdl_slen == 0) {
    459 		n = snprintf(host, hostlen, "link#%d", sdl->sdl_index);
    460 		if (n > hostlen) {
    461 			*host = '\0';
    462 			return EAI_MEMORY;
    463 		}
    464 		return 0;
    465 	}
    466 
    467 	switch (sdl->sdl_type) {
    468 #ifdef IFT_ECONET
    469 	case IFT_ECONET:
    470 		if (sdl->sdl_alen < 2)
    471 			return EAI_FAMILY;
    472 		if (LLADDR(sdl)[1] == 0)
    473 			n = snprintf(host, hostlen, "%d", LLADDR(sdl)[0]);
    474 		else
    475 			n = snprintf(host, hostlen, "%d.%d",
    476 			    LLADDR(sdl)[1], LLADDR(sdl)[0]);
    477 		if (n >= hostlen) {
    478 			*host = '\0';
    479 			return EAI_MEMORY;
    480 		} else
    481 			return 0;
    482 #endif
    483 	case IFT_IEEE1394:
    484 		if (sdl->sdl_alen < sizeof(iha->iha_uid))
    485 			return EAI_FAMILY;
    486 		iha = (struct ieee1394_hwaddr *)LLADDR(sdl);
    487 		return hexname(iha->iha_uid, sizeof(iha->iha_uid),
    488 		    host, hostlen);
    489 	/*
    490 	 * The following have zero-length addresses.
    491 	 * IFT_ATM	(net/if_atmsubr.c)
    492 	 * IFT_FAITH	(net/if_faith.c)
    493 	 * IFT_GIF	(net/if_gif.c)
    494 	 * IFT_LOOP	(net/if_loop.c)
    495 	 * IFT_PPP	(net/if_ppp.c, net/if_spppsubr.c)
    496 	 * IFT_SLIP	(net/if_sl.c, net/if_strip.c)
    497 	 * IFT_STF	(net/if_stf.c)
    498 	 * IFT_L2VLAN	(net/if_vlan.c)
    499 	 * IFT_PROPVIRTUAL (net/if_bridge.h>
    500 	 */
    501 	/*
    502 	 * The following use IPv4 addresses as link-layer addresses:
    503 	 * IFT_OTHER	(net/if_gre.c)
    504 	 * IFT_OTHER	(netinet/ip_ipip.c)
    505 	 */
    506 	case IFT_ARCNET: /* default below is believed correct for all these. */
    507 	case IFT_ETHER:
    508 	case IFT_FDDI:
    509 	case IFT_HIPPI:
    510 	case IFT_ISO88025:
    511 	default:
    512 		return hexname(LLADDR(sdl), sdl->sdl_alen, host, hostlen);
    513 	}
    514 }
    515 
    516 static int
    517 hexname(cp, len, host, hostlen)
    518 	u_int8_t *cp;
    519 	char *host;
    520 	size_t len, hostlen;
    521 {
    522 	int i, n, space = hostlen;
    523 	char *outp = host;
    524 
    525 	*outp = '\0';
    526 	for (i = 0; i < len; i++) {
    527 		n = snprintf(outp, hostlen, "%s%02x", i ? ":" : "", cp[i]);
    528 		outp += n;
    529 		space -= n;
    530 		if (space <= 0) {
    531 			*host = '\0';
    532 			return EAI_MEMORY;
    533 		}
    534 	}
    535 	return 0;
    536 }
    537