usr/src/lib/libc/port/nsl/inet_ntop.c

   1 /*
   2  * Copyright 2006 Sun Microsystems, Inc.  All rights reserved.
   3  * Use is subject to license terms.
   4  */
   5
   6 /*
   7  * Copyright (c) 1996 by Internet Software Consortium.
   8  *
   9  * Permission to use, copy, modify, and distribute this software for any
  10  * purpose with or without fee is hereby granted, provided that the above
  11  * copyright notice and this permission notice appear in all copies.
  12  *
  13  * THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM DISCLAIMS
  14  * ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
  15  * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE
  16  * CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
  17  * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
  18  * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
  19  * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
  20  * SOFTWARE.
  21  */
  22
  23 #pragma ident   "%Z%%M% %I%     %E% SMI"
  24
  25 #include "mt.h"
  26 #include <stdlib.h>
  27 #include <ctype.h>
  28 #include <string.h>
  29 #include <strings.h>
  30 #include <netdb.h>
  31 #include <stdio.h>
  32 #include <arpa/inet.h>
  33 #include <netinet/in.h>
  34 #include <sys/socket.h>
  35 #include <errno.h>
  36
  37 static const char *inet_ntop4(const uchar_t *, char *, socklen_t);
  38 static const char *inet_ntop6(const uchar_t *, char *, socklen_t);
  39
  40 /*
  41  * char *
  42  * inet_ntop(af, src, dst, size)
  43  *      convert a network format address to presentation format.
  44  * return:
  45  *      pointer to presentation format address (`dst'), or NULL (see errno).
  46  */
  47 const char *
  48 inet_ntop(int af, const void *src, char *dst, socklen_t size)
  49 {
  50         switch (af) {
  51         case AF_INET:
  52                 return (inet_ntop4(src, dst, size));
  53         case AF_INET6:
  54                 return (inet_ntop6(src, dst, size));
  55         default:
  56                 errno = EAFNOSUPPORT;
  57                 return (NULL);
  58         }
  59         /* NOTREACHED */
  60 }
  61
  62 /*
  63  * const char *
  64  * inet_ntop4(src, dst, size)
  65  *      format an IPv4 address, more or less like inet_ntoa()
  66  * return:
  67  *      `dst' (as a const)
  68  * notes:
  69  *      (1) uses no statics
  70  *      (2) takes a uchar_t* not an in_addr as input
  71  */
  72
  73 #ifdef SPRINTF_CHAR
  74 /* CSTYLED */
  75 #define SPRINTF(x) strlen(sprintf/**/x)
  76 #else
  77 #define SPRINTF(x) ((size_t)sprintf x)
  78 #endif
  79
  80 static const char *
  81 inet_ntop4(const uchar_t *src, char *dst, socklen_t size)
  82 {
  83         static const char fmt[] = "%u.%u.%u.%u";
  84         char tmp[sizeof ("255.255.255.255")];
  85
  86         if (SPRINTF((tmp, fmt, src[0], src[1], src[2], src[3])) > size) {
  87                 errno = ENOSPC;
  88                 return (NULL);
  89         }
  90         (void) strcpy(dst, tmp);
  91         return (dst);
  92 }
  93
  94 /*
  95  * const char *
  96  * inet_ntop6(src, dst, size)
  97  *      convert IPv6 binary address into presentation (printable) format
  98  */
  99 #define INADDRSZ        4
 100 #define IN6ADDRSZ       16
 101 #define INT16SZ         2
 102 static const char *
 103 inet_ntop6(const uchar_t *src, char *dst, socklen_t size)
 104 {
 105         /*
 106          * Note that int32_t and int16_t need only be "at least" large enough
 107          * to contain a value of the specified size.  On some systems, like
 108          * Crays, there is no such thing as an integer variable with 16 bits.
 109          * Keep this in mind if you think this function should have been coded
 110          * to use pointer overlays.  All the world's not a VAX.
 111          */
 112         char tmp[sizeof ("ffff:ffff:ffff:ffff:ffff:ffff:255.255.255.255")], *tp;
 113         struct { int base, len; } best, cur;
 114         uint_t words[IN6ADDRSZ / INT16SZ];
 115         int i;
 116
 117         /*
 118          * Preprocess:
 119          *      Copy the input (bytewise) array into a wordwise array.
 120          *      Find the longest run of 0x00's in src[] for :: shorthanding.
 121          */
 122         (void) memset(words, '\0', sizeof (words));
 123         for (i = 0; i < IN6ADDRSZ; i++)
 124                 words[i / 2] |= (src[i] << ((1 - (i % 2)) << 3));
 125         best.base = -1;
 126         cur.base = -1;
 127         for (i = 0; i < (IN6ADDRSZ / INT16SZ); i++) {
 128                 if (words[i] == 0) {
 129                         if (cur.base == -1)
 130                                 cur.base = i, cur.len = 1;
 131                         else
 132                                 cur.len++;
 133                 } else {
 134                         if (cur.base != -1) {
 135                                 if (best.base == -1 || cur.len > best.len)
 136                                         best = cur;
 137                                 cur.base = -1;
 138                         }
 139                 }
 140         }
 141         if (cur.base != -1) {
 142                 if (best.base == -1 || cur.len > best.len)
 143                         best = cur;
 144         }
 145         if (best.base != -1 && best.len < 2)
 146                 best.base = -1;
 147
 148         /*
 149          * Format the result.
 150          */
 151         tp = tmp;
 152         for (i = 0; i < (IN6ADDRSZ / INT16SZ); i++) {
 153                 /* Are we inside the best run of 0x00's? */
 154                 if (best.base != -1 && i >= best.base &&
 155                     i < (best.base + best.len)) {
 156                         if (i == best.base)
 157                                 *tp++ = ':';
 158                         continue;
 159                 }
 160                 /* Are we following an initial run of 0x00s or any real hex? */
 161                 if (i != 0)
 162                         *tp++ = ':';
 163                 /* Is this address an encapsulated IPv4? */
 164                 if (i == 6 && best.base == 0 &&
 165                     (best.len == 6 || (best.len == 5 && words[5] == 0xffff))) {
 166                         if (!inet_ntop4(src+12, tp, sizeof (tmp) - (tp - tmp)))
 167                                 return (NULL);
 168                         tp += strlen(tp);
 169                         break;
 170                 }
 171                 tp += SPRINTF((tp, "%x", words[i]));
 172         }
 173         /* Was it a trailing run of 0x00's? */
 174         if (best.base != -1 && (best.base + best.len) == (IN6ADDRSZ / INT16SZ))
 175                 *tp++ = ':';
 176         *tp++ = '\0';
 177
 178         /*
 179          * Check for overflow, copy, and we're done.
 180          */
 181         if ((int)(tp - tmp) > size) {
 182                 errno = ENOSPC;
 183                 return (NULL);
 184         }
 185         (void) strcpy(dst, tmp);
 186         return (dst);
 187 }