lib/libc/net/getnameinfo.c

   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 * __restrict sa, socklen_t salen,
  75     char * __restrict host, size_t hostlen, char * __restrict serv,
  76     size_t servlen, int flags)
  77 {
  78
  79         switch (sa->sa_family) {
  80         case AF_INET:
  81 #ifdef INET6
  82         case AF_INET6:
  83 #endif
  84                 return getnameinfo_inet(sa, salen, host, hostlen, serv,
  85                     servlen, flags);
  86         case AF_LINK:
  87                 return getnameinfo_link(sa, salen, host, hostlen, serv,
  88                     servlen, flags);
  89         default:
  90                 return EAI_FAMILY;
  91         }
  92 }
  93
  94 static const struct afd {
  95         int a_af;
  96         size_t a_addrlen;
  97         socklen_t a_socklen;
  98         int a_off;
  99 } afdl [] = {
 100 #ifdef INET6
 101         {PF_INET6, sizeof(struct in6_addr), sizeof(struct sockaddr_in6),
 102                 offsetof(struct sockaddr_in6, sin6_addr)},
 103 #endif
 104         {PF_INET, sizeof(struct in_addr), sizeof(struct sockaddr_in),
 105                 offsetof(struct sockaddr_in, sin_addr)},
 106         { .a_af = 0 },
 107 };
 108
 109 struct sockinet {
 110         u_char  si_len;
 111         u_char  si_family;
 112         u_short si_port;
 113 };
 114
 115 static int
 116 getnameinfo_inet(const struct sockaddr *sa, socklen_t salen, char *host,
 117                  size_t hostlen, char *serv, size_t servlen, int flags)
 118 {
 119         const struct afd *afd;
 120         struct servent *sp;
 121         struct hostent *hp;
 122         u_short port;
 123         int family, i;
 124         const char *addr;
 125         u_int32_t v4a;
 126         int h_error;
 127         char numserv[512];
 128         char numaddr[512];
 129
 130         if (sa == NULL)
 131                 return EAI_FAIL;
 132
 133         family = sa->sa_family;
 134         for (i = 0; afdl[i].a_af; i++)
 135                 if (afdl[i].a_af == family) {
 136                         afd = &afdl[i];
 137                         goto found;
 138                 }
 139         return EAI_FAMILY;
 140
 141  found:
 142         if (salen != afd->a_socklen)
 143                 return EAI_FAIL;
 144
 145         /* network byte order */
 146         port = ((const struct sockinet *)sa)->si_port;
 147         addr = (const char *)sa + afd->a_off;
 148
 149         if (serv == NULL || servlen == 0) {
 150                 /*
 151                  * do nothing in this case.
 152                  * in case you are wondering if "&&" is more correct than
 153                  * "||" here: rfc2553bis-03 says that serv == NULL OR
 154                  * servlen == 0 means that the caller does not want the result.
 155                  */
 156         } else {
 157                 if (flags & NI_NUMERICSERV)
 158                         sp = NULL;
 159                 else {
 160                         sp = getservbyport(port,
 161                                 (flags & NI_DGRAM) ? "udp" : "tcp");
 162                 }
 163                 if (sp) {
 164                         if (strlen(sp->s_name) + 1 > servlen)
 165                                 return EAI_MEMORY;
 166                         strlcpy(serv, sp->s_name, servlen);
 167                 } else {
 168                         snprintf(numserv, sizeof(numserv), "%u", ntohs(port));
 169                         if (strlen(numserv) + 1 > servlen)
 170                                 return EAI_MEMORY;
 171                         strlcpy(serv, numserv, servlen);
 172                 }
 173         }
 174
 175         switch (sa->sa_family) {
 176         case AF_INET:
 177                 v4a = (u_int32_t)
 178                     ntohl(((const struct sockaddr_in *)sa)->sin_addr.s_addr);
 179                 if (IN_MULTICAST(v4a) || IN_EXPERIMENTAL(v4a))
 180                         flags |= NI_NUMERICHOST;
 181                 v4a >>= IN_CLASSA_NSHIFT;
 182                 if (v4a == 0)
 183                         flags |= NI_NUMERICHOST;
 184                 break;
 185 #ifdef INET6
 186         case AF_INET6:
 187             {
 188                 const struct sockaddr_in6 *sin6;
 189                 sin6 = (const struct sockaddr_in6 *)sa;
 190                 switch (sin6->sin6_addr.s6_addr[0]) {
 191                 case 0x00:
 192                         if (IN6_IS_ADDR_V4MAPPED(&sin6->sin6_addr))
 193                                 ;
 194                         else if (IN6_IS_ADDR_LOOPBACK(&sin6->sin6_addr))
 195                                 ;
 196                         else
 197                                 flags |= NI_NUMERICHOST;
 198                         break;
 199                 default:
 200                         if (IN6_IS_ADDR_LINKLOCAL(&sin6->sin6_addr)) {
 201                                 flags |= NI_NUMERICHOST;
 202                         }
 203                         else if (IN6_IS_ADDR_MULTICAST(&sin6->sin6_addr))
 204                                 flags |= NI_NUMERICHOST;
 205                         break;
 206                 }
 207             }
 208                 break;
 209 #endif
 210         }
 211         if (host == NULL || hostlen == 0) {
 212                 /*
 213                  * do nothing in this case.
 214                  * in case you are wondering if "&&" is more correct than
 215                  * "||" here: rfc2553bis-03 says that host == NULL or
 216                  * hostlen == 0 means that the caller does not want the result.
 217                  */
 218         } else if (flags & NI_NUMERICHOST) {
 219                 size_t numaddrlen;
 220
 221                 /* NUMERICHOST and NAMEREQD conflicts with each other */
 222                 if (flags & NI_NAMEREQD)
 223                         return EAI_NONAME;
 224
 225                 switch(afd->a_af) {
 226 #ifdef INET6
 227                 case AF_INET6:
 228                 {
 229                         int error;
 230
 231                         if ((error = ip6_parsenumeric(sa, addr, host,
 232                                                       hostlen, flags)) != 0)
 233                                 return(error);
 234                         break;
 235                 }
 236 #endif
 237                 default:
 238                         if (inet_ntop(afd->a_af, addr, numaddr, sizeof(numaddr))
 239                             == NULL)
 240                                 return EAI_SYSTEM;
 241                         numaddrlen = strlen(numaddr);
 242                         if (numaddrlen + 1 > hostlen) /* don't forget terminator */
 243                                 return EAI_MEMORY;
 244                         strlcpy(host, numaddr, hostlen);
 245                         break;
 246                 }
 247         } else {
 248                 hp = getipnodebyaddr(addr, afd->a_addrlen, afd->a_af, &h_error);
 249
 250                 if (hp) {
 251 #if 0
 252                         /*
 253                          * commented out, since "for local host" is not
 254                          * implemented here - see RFC2553 p30
 255                          */
 256                         if (flags & NI_NOFQDN) {
 257                                 char *p;
 258                                 p = strchr(hp->h_name, '.');
 259                                 if (p)
 260                                         *p = '\0';
 261                         }
 262 #endif
 263                         if (strlen(hp->h_name) + 1 > hostlen) {
 264                                 freehostent(hp);
 265                                 return EAI_MEMORY;
 266                         }
 267                         strlcpy(host, hp->h_name, hostlen);
 268                         freehostent(hp);
 269                 } else {
 270                         if (flags & NI_NAMEREQD)
 271                                 return EAI_NONAME;
 272                         switch(afd->a_af) {
 273 #ifdef INET6
 274                         case AF_INET6:
 275                         {
 276                                 int error;
 277
 278                                 if ((error = ip6_parsenumeric(sa, addr, host,
 279                                                               hostlen,
 280                                                               flags)) != 0)
 281                                         return(error);
 282                                 break;
 283                         }
 284 #endif
 285                         default:
 286                                 if (inet_ntop(afd->a_af, addr, host,
 287                                     hostlen) == NULL)
 288                                         return EAI_SYSTEM;
 289                                 break;
 290                         }
 291                 }
 292         }
 293         return(0);
 294 }
 295
 296 #ifdef INET6
 297 static int
 298 ip6_parsenumeric(const struct sockaddr *sa, const char *addr, char *host,
 299                  size_t hostlen, int flags)
 300 {
 301         size_t numaddrlen;
 302         char numaddr[512];
 303
 304         if (inet_ntop(AF_INET6, addr, numaddr, sizeof(numaddr)) == NULL)
 305                 return EAI_SYSTEM;
 306
 307         numaddrlen = strlen(numaddr);
 308         if (numaddrlen + 1 > hostlen) /* don't forget terminator */
 309                 return EAI_OVERFLOW;
 310         strlcpy(host, numaddr, hostlen);
 311
 312         if (((const struct sockaddr_in6 *)sa)->sin6_scope_id) {
 313                 char zonebuf[MAXHOSTNAMELEN];
 314                 int zonelen;
 315
 316                 zonelen = ip6_sa2str(
 317                     (const struct sockaddr_in6 *)(const void *)sa,
 318                     zonebuf, sizeof(zonebuf), flags);
 319                 if (zonelen < 0)
 320                         return EAI_OVERFLOW;
 321                 if (zonelen + 1 + numaddrlen + 1 > hostlen)
 322                         return EAI_OVERFLOW;
 323
 324                 /* construct <numeric-addr><delim><zoneid> */
 325                 memcpy(host + numaddrlen + 1, zonebuf,
 326                     (size_t)zonelen);
 327                 host[numaddrlen] = SCOPE_DELIMITER;
 328                 host[numaddrlen + 1 + zonelen] = '\0';
 329         }
 330
 331         return 0;
 332 }
 333
 334 /* ARGSUSED */
 335 static int
 336 ip6_sa2str(const struct sockaddr_in6 *sa6, char *buf, size_t bufsiz,
 337            int flags __unused)
 338 {
 339         unsigned int ifindex;
 340         const struct in6_addr *a6;
 341         int n;
 342
 343         ifindex = (unsigned int)sa6->sin6_scope_id;
 344         a6 = &sa6->sin6_addr;
 345
 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
 354         /* if_indextoname() does not take buffer size.  not a good api... */
 355         if ((IN6_IS_ADDR_LINKLOCAL(a6) || IN6_IS_ADDR_MC_LINKLOCAL(a6) ||
 356              IN6_IS_ADDR_MC_NODELOCAL(a6)) && bufsiz >= IF_NAMESIZE) {
 357                 char *p = if_indextoname(ifindex, buf);
 358                 if (p) {
 359                         return(strlen(p));
 360                 }
 361         }
 362
 363         /* last resort */
 364         n = snprintf(buf, bufsiz, "%u", sa6->sin6_scope_id);
 365         if (n < 0 || (size_t)n >= bufsiz)
 366                 return -1;
 367         else
 368                 return n;
 369 }
 370 #endif /* INET6 */
 371
 372 /*
 373  * getnameinfo_link():
 374  * Format a link-layer address into a printable format, paying attention to
 375  * the interface type.
 376  */
 377 /* ARGSUSED */
 378 static int
 379 getnameinfo_link(const struct sockaddr *sa, socklen_t salen __unused,
 380                  char *host, size_t hostlen, char *serv, size_t servlen,
 381                  int flags __unused)
 382 {
 383         const struct sockaddr_dl *sdl =
 384             (const struct sockaddr_dl *)(const void *)sa;
 385         int n;
 386
 387         if (serv != NULL && servlen > 0)
 388                 *serv = '\0';
 389
 390         if (sdl->sdl_nlen == 0 && sdl->sdl_alen == 0 && sdl->sdl_slen == 0) {
 391                 n = snprintf(host, hostlen, "link#%d", sdl->sdl_index);
 392                 if (n > hostlen) {
 393                         *host = '\0';
 394                         return EAI_MEMORY;
 395                 }
 396                 return 0;
 397         }
 398
 399         switch (sdl->sdl_type) {
 400         /*
 401          * The following have zero-length addresses.
 402          * IFT_GIF      (net/gif/if_gif.c)
 403          * IFT_LOOP     (net/if_loop.c, net/disc/if_disc.c)
 404          * IFT_PPP      (net/sppp/if_spppsubr.c)
 405          * IFT_SLIP     (net/sl/if_sl.c)
 406          * IFT_STF      (net/stf/if_stf.c)
 407          * IFT_L2VLAN   (net/vlan/if_vlan.c)
 408          * IFT_BRIDGE   (net/bridge/if_bridge.c)
 409          */
 410         /*
 411          * The following use IPv4 addresses as link-layer addresses:
 412          * IFT_OTHER    (net/gre/if_gre.c)
 413          */
 414         /* default below is believed correct for all these. */
 415         case IFT_ARCNET:
 416         case IFT_ETHER:
 417         case IFT_FDDI:
 418         case IFT_HIPPI:
 419         case IFT_ISO88025:
 420         default:
 421                 return hexname((u_int8_t *)LLADDR(sdl), (size_t)sdl->sdl_alen,
 422                     host, hostlen);
 423         }
 424 }
 425
 426 static int
 427 hexname(const u_int8_t *cp, size_t len, char *host, size_t hostlen)
 428 {
 429         int i, n;
 430         char *outp = host;
 431
 432         *outp = '\0';
 433         for (i = 0; i < len; i++) {
 434                 n = snprintf(outp, hostlen, "%s%02x",
 435                     i ? ":" : "", cp[i]);
 436                 if (n < 0 || n >= hostlen) {
 437                         *host = '\0';
 438                         return EAI_MEMORY;
 439                 }
 440                 outp += n;
 441                 hostlen -= n;
 442         }
 443         return 0;
 444 }