1: /*
    2:  * Copyright (c) 1996-1999 by Internet Software Consortium.
    3:  *
    4:  * Permission to use, copy, modify, and distribute this software for any
    5:  * purpose with or without fee is hereby granted, provided that the above
    6:  * copyright notice and this permission notice appear in all copies.
    7:  *
    8:  * THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM DISCLAIMS
    9:  * ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
   10:  * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE
   11:  * CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
   12:  * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
   13:  * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
   14:  * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
   15:  * SOFTWARE.
   16:  */
   17: 
   18: #if defined(LIBC_SCCS) && !defined(lint)
   19: static const char rcsid[] = "$BINDId: inet_ntop.c,v 1.8 1999/10/13 16:39:28 vixie Exp $";
   20: #endif /* LIBC_SCCS and not lint */
   21: 
   22: #include <sys/param.h>
   23: #include <sys/types.h>
   24: #include <sys/socket.h>
   25: 
   26: #include <netinet/in.h>
   27: #include <arpa/inet.h>
   28: #include <arpa/nameser.h>
   29: 
   30: #include <errno.h>
   31: #include <stdio.h>
   32: #include <string.h>
   33: 
   34: #ifdef SPRINTF_CHAR
   35: # define SPRINTF(x) strlen(sprintf/**/x)
   36: #else
   37: # define SPRINTF(x) ((size_t)sprintf x)
   38: #endif
   39: 
   40: /*
   41:  * WARNING: Don't even consider trying to compile this on a system where
   42:  * sizeof(int) < 4.  sizeof(int) > 4 is fine; all the world's not a VAX.
   43:  */
   44: 
   45: static const char *inet_ntop4 (const u_char *src, char *dst, socklen_t size)
   46:      internal_function;
   47: static const char *inet_ntop6 (const u_char *src, char *dst, socklen_t size)
   48:      internal_function;
   49: 
   50: /* char *
   51:  * inet_ntop(af, src, dst, size)
   52:  *      convert a network format address to presentation format.
   53:  * return:
   54:  *      pointer to presentation format address (`dst'), or NULL (see errno).
   55:  * author:
   56:  *      Paul Vixie, 1996.
   57:  */
   58: const char *
   59: inet_ntop(af, src, dst, size)
   60:         int af;
   61:         const void *src;
   62:         char *dst;
   63:         socklen_t size;
   64: {
   65:         switch (af) {
   66:         case AF_INET:
   67:                 return (inet_ntop4(src, dst, size));
   68:         case AF_INET6:
   69:                 return (inet_ntop6(src, dst, size));
   70:         default:
   71:                 __set_errno (EAFNOSUPPORT);
   72:                 return (NULL);
   73:         }
   74:         /* NOTREACHED */
   75: }
   76: libc_hidden_def (inet_ntop)
   77: 
   78: /* const char *
   79:  * inet_ntop4(src, dst, size)
   80:  *      format an IPv4 address
   81:  * return:
   82:  *      `dst' (as a const)
   83:  * notes:
   84:  *      (1) uses no statics
   85:  *      (2) takes a u_char* not an in_addr as input
   86:  * author:
   87:  *      Paul Vixie, 1996.
   88:  */
   89: static const char *
   90: internal_function
   91: inet_ntop4(src, dst, size)
   92:         const u_char *src;
   93:         char *dst;
   94:         socklen_t size;
   95: {
   96:         static const char fmt[] = "%u.%u.%u.%u";
   97:         char tmp[sizeof "255.255.255.255"];
   98: 
   99:         if (SPRINTF((tmp, fmt, src[0], src[1], src[2], src[3])) >= size) {
  100:                 __set_errno (ENOSPC);
  101:                 return (NULL);
  102:         }
  103:         return strcpy(dst, tmp);
  104: }
  105: 
  106: /* const char *
  107:  * inet_ntop6(src, dst, size)
  108:  *      convert IPv6 binary address into presentation (printable) format
  109:  * author:
  110:  *      Paul Vixie, 1996.
  111:  */
  112: static const char *
  113: internal_function
  114: inet_ntop6(src, dst, size)
  115:         const u_char *src;
  116:         char *dst;
  117:         socklen_t size;
  118: {
  119:         /*
  120:          * Note that int32_t and int16_t need only be "at least" large enough
  121:          * to contain a value of the specified size.  On some systems, like
  122:          * Crays, there is no such thing as an integer variable with 16 bits.
  123:          * Keep this in mind if you think this function should have been coded
  124:          * to use pointer overlays.  All the world's not a VAX.
  125:          */
  126:         char tmp[sizeof "ffff:ffff:ffff:ffff:ffff:ffff:255.255.255.255"], *tp;
  127:         struct { int base, len; } best, cur;
  128:         u_int words[NS_IN6ADDRSZ / NS_INT16SZ];
  129:         int i;
  130: 
  131:         /*
  132:          * Preprocess:
  133:          *     Copy the input (bytewise) array into a wordwise array.
  134:          *     Find the longest run of 0x00's in src[] for :: shorthanding.
  135:          */
  136:         memset(words, '\0', sizeof words);
  137:         for (i = 0; i < NS_IN6ADDRSZ; i += 2)
  138:                 words[i / 2] = (src[i] << 8) | src[i + 1];
  139:         best.base = -1;
  140:         cur.base = -1;
  141:         best.len = 0;
  142:         cur.len = 0;
  143:         for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) {
  144:                 if (words[i] == 0) {
  145:                         if (cur.base == -1)
  146:                                 cur.base = i, cur.len = 1;
  147:                         else
  148:                                 cur.len++;
  149:                 } else {
  150:                         if (cur.base != -1) {
  151:                                 if (best.base == -1 || cur.len > best.len)
  152:                                         best = cur;
  153:                                 cur.base = -1;
  154:                         }
  155:                 }
  156:         }
  157:         if (cur.base != -1) {
  158:                 if (best.base == -1 || cur.len > best.len)
  159:                         best = cur;
  160:         }
  161:         if (best.base != -1 && best.len < 2)
  162:                 best.base = -1;
  163: 
  164:         /*
  165:          * Format the result.
  166:          */
  167:         tp = tmp;
  168:         for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) {
  169:                 /* Are we inside the best run of 0x00's? */
  170:                 if (best.base != -1 && i >= best.base &&
  171:                     i < (best.base + best.len)) {
  172:                         if (i == best.base)
  173:                                 *tp++ = ':';
  174:                         continue;
  175:                 }
  176:                 /* Are we following an initial run of 0x00s or any real hex? */
  177:                 if (i != 0)
  178:                         *tp++ = ':';
  179:                 /* Is this address an encapsulated IPv4? */
  180:                 if (i == 6 && best.base == 0 &&
  181:                     (best.len == 6 || (best.len == 5 && words[5] == 0xffff))) {
  182:                         if (!inet_ntop4(src+12, tp, sizeof tmp - (tp - tmp)))
  183:                                 return (NULL);
  184:                         tp += strlen(tp);
  185:                         break;
  186:                 }
  187:                 tp += SPRINTF((tp, "%x", words[i]));
  188:         }
  189:         /* Was it a trailing run of 0x00's? */
  190:         if (best.base != -1 && (best.base + best.len) ==
  191:             (NS_IN6ADDRSZ / NS_INT16SZ))
  192:                 *tp++ = ':';
  193:         *tp++ = '\0';
  194: 
  195:         /*
  196:          * Check for overflow, copy, and we're done.
  197:          */
  198:         if ((socklen_t)(tp - tmp) > size) {
  199:                 __set_errno (ENOSPC);
  200:                 return (NULL);
  201:         }
  202:         return strcpy(dst, tmp);
  203: }