lib/libc/net/getnameinfo.c

   1 /*      $FreeBSD: src/lib/libc/net/getnameinfo.c,v 1.4.2.5 2002/07/31 10:11:09 ume Exp $        */
   2 /*      $DragonFly: src/lib/libc/net/getnameinfo.c,v 1.5 2008/10/04 22:09:17 swildner Exp $     */
   3 /*      $KAME: getnameinfo.c,v 1.61 2002/06/27 09:25:47 itojun Exp $    */
   4
   5 /*
   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) 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 <netinet/in.h>
  52 #include <arpa/inet.h>
  53 #include <arpa/nameser.h>
  54 #include <netdb.h>
  55 #include <resolv.h>
  56 #include <string.h>
  57 #include <stddef.h>
  58 #include <errno.h>
  59
  60 static const struct afd {
  61         int a_af;
  62         int a_addrlen;
  63         int a_socklen;
  64         int a_off;
  65 } afdl [] = {
  66 #ifdef INET6
  67         {PF_INET6, sizeof(struct in6_addr), sizeof(struct sockaddr_in6),
  68                 offsetof(struct sockaddr_in6, sin6_addr)},
  69 #endif
  70         {PF_INET, sizeof(struct in_addr), sizeof(struct sockaddr_in),
  71                 offsetof(struct sockaddr_in, sin_addr)},
  72         {0, 0, 0},
  73 };
  74
  75 struct sockinet {
  76         u_char  si_len;
  77         u_char  si_family;
  78         u_short si_port;
  79 };
  80
  81 #ifdef INET6
  82 static int ip6_parsenumeric (const struct sockaddr *, const char *, char *,
  83     size_t, int);
  84 static int ip6_sa2str (const struct sockaddr_in6 *, char *, size_t, int);
  85 #endif
  86
  87 int
  88 getnameinfo(const struct sockaddr *sa, socklen_t salen, char *host,
  89             size_t hostlen, char *serv, size_t servlen, int flags)
  90 {
  91         const struct afd *afd;
  92         struct servent *sp;
  93         struct hostent *hp;
  94         u_short port;
  95         int family, i;
  96         const char *addr;
  97         u_int32_t v4a;
  98         int h_error;
  99         char numserv[512];
 100         char numaddr[512];
 101
 102         if (sa == NULL)
 103                 return EAI_FAIL;
 104
 105         if (sa->sa_len != salen)
 106                 return EAI_FAIL;
 107
 108         family = sa->sa_family;
 109         for (i = 0; afdl[i].a_af; i++)
 110                 if (afdl[i].a_af == family) {
 111                         afd = &afdl[i];
 112                         goto found;
 113                 }
 114         return EAI_FAMILY;
 115
 116  found:
 117         if (salen != afd->a_socklen)
 118                 return EAI_FAIL;
 119
 120         /* network byte order */
 121         port = ((const struct sockinet *)sa)->si_port;
 122         addr = (const char *)sa + afd->a_off;
 123
 124         if (serv == NULL || servlen == 0) {
 125                 /*
 126                  * do nothing in this case.
 127                  * in case you are wondering if "&&" is more correct than
 128                  * "||" here: rfc2553bis-03 says that serv == NULL OR
 129                  * servlen == 0 means that the caller does not want the result.
 130                  */
 131         } else {
 132                 if (flags & NI_NUMERICSERV)
 133                         sp = NULL;
 134                 else {
 135                         sp = getservbyport(port,
 136                                 (flags & NI_DGRAM) ? "udp" : "tcp");
 137                 }
 138                 if (sp) {
 139                         if (strlen(sp->s_name) + 1 > servlen)
 140                                 return EAI_MEMORY;
 141                         strlcpy(serv, sp->s_name, servlen);
 142                 } else {
 143                         snprintf(numserv, sizeof(numserv), "%u", ntohs(port));
 144                         if (strlen(numserv) + 1 > servlen)
 145                                 return EAI_MEMORY;
 146                         strlcpy(serv, numserv, servlen);
 147                 }
 148         }
 149
 150         switch (sa->sa_family) {
 151         case AF_INET:
 152                 v4a = (u_int32_t)
 153                     ntohl(((const struct sockaddr_in *)sa)->sin_addr.s_addr);
 154                 if (IN_MULTICAST(v4a) || IN_EXPERIMENTAL(v4a))
 155                         flags |= NI_NUMERICHOST;
 156                 v4a >>= IN_CLASSA_NSHIFT;
 157                 if (v4a == 0)
 158                         flags |= NI_NUMERICHOST;
 159                 break;
 160 #ifdef INET6
 161         case AF_INET6:
 162             {
 163                 const struct sockaddr_in6 *sin6;
 164                 sin6 = (const struct sockaddr_in6 *)sa;
 165                 switch (sin6->sin6_addr.s6_addr[0]) {
 166                 case 0x00:
 167                         if (IN6_IS_ADDR_V4MAPPED(&sin6->sin6_addr))
 168                                 ;
 169                         else if (IN6_IS_ADDR_LOOPBACK(&sin6->sin6_addr))
 170                                 ;
 171                         else
 172                                 flags |= NI_NUMERICHOST;
 173                         break;
 174                 default:
 175                         if (IN6_IS_ADDR_LINKLOCAL(&sin6->sin6_addr)) {
 176                                 flags |= NI_NUMERICHOST;
 177                         }
 178                         else if (IN6_IS_ADDR_MULTICAST(&sin6->sin6_addr))
 179                                 flags |= NI_NUMERICHOST;
 180                         break;
 181                 }
 182             }
 183                 break;
 184 #endif
 185         }
 186         if (host == NULL || hostlen == 0) {
 187                 /*
 188                  * do nothing in this case.
 189                  * in case you are wondering if "&&" is more correct than
 190                  * "||" here: rfc2553bis-03 says that host == NULL or
 191                  * hostlen == 0 means that the caller does not want the result.
 192                  */
 193         } else if (flags & NI_NUMERICHOST) {
 194                 int numaddrlen;
 195
 196                 /* NUMERICHOST and NAMEREQD conflicts with each other */
 197                 if (flags & NI_NAMEREQD)
 198                         return EAI_NONAME;
 199
 200                 switch(afd->a_af) {
 201 #ifdef INET6
 202                 case AF_INET6:
 203                 {
 204                         int error;
 205
 206                         if ((error = ip6_parsenumeric(sa, addr, host,
 207                                                       hostlen, flags)) != 0)
 208                                 return(error);
 209                         break;
 210                 }
 211 #endif
 212                 default:
 213                         if (inet_ntop(afd->a_af, addr, numaddr, sizeof(numaddr))
 214                             == NULL)
 215                                 return EAI_SYSTEM;
 216                         numaddrlen = strlen(numaddr);
 217                         if (numaddrlen + 1 > hostlen) /* don't forget terminator */
 218                                 return EAI_MEMORY;
 219                         strlcpy(host, numaddr, hostlen);
 220                         break;
 221                 }
 222         } else {
 223                 hp = getipnodebyaddr(addr, afd->a_addrlen, afd->a_af, &h_error);
 224
 225                 if (hp) {
 226 #if 0
 227                         /*
 228                          * commented out, since "for local host" is not
 229                          * implemented here - see RFC2553 p30
 230                          */
 231                         if (flags & NI_NOFQDN) {
 232                                 char *p;
 233                                 p = strchr(hp->h_name, '.');
 234                                 if (p)
 235                                         *p = '\0';
 236                         }
 237 #endif
 238                         if (strlen(hp->h_name) + 1 > hostlen) {
 239                                 freehostent(hp);
 240                                 return EAI_MEMORY;
 241                         }
 242                         strlcpy(host, hp->h_name, hostlen);
 243                         freehostent(hp);
 244                 } else {
 245                         if (flags & NI_NAMEREQD)
 246                                 return EAI_NONAME;
 247                         switch(afd->a_af) {
 248 #ifdef INET6
 249                         case AF_INET6:
 250                         {
 251                                 int error;
 252
 253                                 if ((error = ip6_parsenumeric(sa, addr, host,
 254                                                               hostlen,
 255                                                               flags)) != 0)
 256                                         return(error);
 257                                 break;
 258                         }
 259 #endif
 260                         default:
 261                                 if (inet_ntop(afd->a_af, addr, host,
 262                                     hostlen) == NULL)
 263                                         return EAI_SYSTEM;
 264                                 break;
 265                         }
 266                 }
 267         }
 268         return(0);
 269 }
 270
 271 #ifdef INET6
 272 static int
 273 ip6_parsenumeric(const struct sockaddr *sa, const char *addr, char *host,
 274                  size_t hostlen, int flags)
 275 {
 276         int numaddrlen;
 277         char numaddr[512];
 278
 279         if (inet_ntop(AF_INET6, addr, numaddr, sizeof(numaddr)) == NULL)
 280                 return EAI_SYSTEM;
 281
 282         numaddrlen = strlen(numaddr);
 283         if (numaddrlen + 1 > hostlen) /* don't forget terminator */
 284                 return EAI_OVERFLOW;
 285         strlcpy(host, numaddr, hostlen);
 286
 287         if (((const struct sockaddr_in6 *)sa)->sin6_scope_id) {
 288                 char zonebuf[MAXHOSTNAMELEN];
 289                 int zonelen;
 290
 291                 zonelen = ip6_sa2str(
 292                     (const struct sockaddr_in6 *)(const void *)sa,
 293                     zonebuf, sizeof(zonebuf), flags);
 294                 if (zonelen < 0)
 295                         return EAI_OVERFLOW;
 296                 if (zonelen + 1 + numaddrlen + 1 > hostlen)
 297                         return EAI_OVERFLOW;
 298
 299                 /* construct <numeric-addr><delim><zoneid> */
 300                 memcpy(host + numaddrlen + 1, zonebuf,
 301                     (size_t)zonelen);
 302                 host[numaddrlen] = SCOPE_DELIMITER;
 303                 host[numaddrlen + 1 + zonelen] = '\0';
 304         }
 305
 306         return 0;
 307 }
 308
 309 /* ARGSUSED */
 310 static int
 311 ip6_sa2str(const struct sockaddr_in6 *sa6, char *buf, size_t bufsiz, int flags)
 312 {
 313         unsigned int ifindex;
 314         const struct in6_addr *a6;
 315         int n;
 316
 317         ifindex = (unsigned int)sa6->sin6_scope_id;
 318         a6 = &sa6->sin6_addr;
 319
 320 #ifdef NI_NUMERICSCOPE
 321         if ((flags & NI_NUMERICSCOPE) != 0) {
 322                 n = snprintf(buf, bufsiz, "%u", sa6->sin6_scope_id);
 323                 if (n < 0 || n >= bufsiz)
 324                         return -1;
 325                 else
 326                         return n;
 327         }
 328 #endif
 329
 330         /* if_indextoname() does not take buffer size.  not a good api... */
 331         if ((IN6_IS_ADDR_LINKLOCAL(a6) || IN6_IS_ADDR_MC_LINKLOCAL(a6) ||
 332              IN6_IS_ADDR_MC_NODELOCAL(a6)) && bufsiz >= IF_NAMESIZE) {
 333                 char *p = if_indextoname(ifindex, buf);
 334                 if (p) {
 335                         return(strlen(p));
 336                 }
 337         }
 338
 339         /* last resort */
 340         n = snprintf(buf, bufsiz, "%u", sa6->sin6_scope_id);
 341         if (n < 0 || n >= bufsiz)
 342                 return -1;
 343         else
 344                 return n;
 345 }
 346 #endif /* INET6 */