1/* inet_ntop.c -- convert IPv4 and IPv6 addresses from binary to text form
2
3   Copyright (C) 2005-2006, 2008-2014 Free Software Foundation, Inc.
4
5   This program is free software; you can redistribute it and/or modify
6   it under the terms of the GNU General Public License as published by
7   the Free Software Foundation; either version 3, or (at your option)
8   any later version.
9
10   This program is distributed in the hope that it will be useful,
11   but WITHOUT ANY WARRANTY; without even the implied warranty of
12   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
13   GNU General Public License for more details.
14
15   You should have received a copy of the GNU General Public License
16   along with this program; if not, see <http://www.gnu.org/licenses/>.  */
17
18/*
19 * Copyright (c) 1996-1999 by Internet Software Consortium.
20 *
21 * Permission to use, copy, modify, and distribute this software for any
22 * purpose with or without fee is hereby granted, provided that the above
23 * copyright notice and this permission notice appear in all copies.
24 *
25 * THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM DISCLAIMS
26 * ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
27 * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE
28 * CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
29 * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
30 * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
31 * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
32 * SOFTWARE.
33 */
34
35#include <config.h>
36
37/* Specification.  */
38#include <arpa/inet.h>
39
40/* Use this to suppress gcc's "...may be used before initialized" warnings.
41   Beware: The Code argument must not contain commas.  */
42#ifndef IF_LINT
43# ifdef lint
44#  define IF_LINT(Code) Code
45# else
46#  define IF_LINT(Code) /* empty */
47# endif
48#endif
49
50#if HAVE_DECL_INET_NTOP
51
52# undef inet_ntop
53
54const char *
55rpl_inet_ntop (int af, const void *restrict src,
56               char *restrict dst, socklen_t cnt)
57{
58  return inet_ntop (af, src, dst, cnt);
59}
60
61#else
62
63# include <stdio.h>
64# include <string.h>
65# include <errno.h>
66
67# define NS_IN6ADDRSZ 16
68# define NS_INT16SZ 2
69
70/*
71 * WARNING: Don't even consider trying to compile this on a system where
72 * sizeof(int) < 4.  sizeof(int) > 4 is fine; all the world's not a VAX.
73 */
74typedef int verify_int_size[4 <= sizeof (int) ? 1 : -1];
75
76static const char *inet_ntop4 (const unsigned char *src, char *dst, socklen_t size);
77# if HAVE_IPV6
78static const char *inet_ntop6 (const unsigned char *src, char *dst, socklen_t size);
79# endif
80
81
82/* char *
83 * inet_ntop(af, src, dst, size)
84 *      convert a network format address to presentation format.
85 * return:
86 *      pointer to presentation format address ('dst'), or NULL (see errno).
87 * author:
88 *      Paul Vixie, 1996.
89 */
90const char *
91inet_ntop (int af, const void *restrict src,
92           char *restrict dst, socklen_t cnt)
93{
94  switch (af)
95    {
96# if HAVE_IPV4
97    case AF_INET:
98      return (inet_ntop4 (src, dst, cnt));
99# endif
100
101# if HAVE_IPV6
102    case AF_INET6:
103      return (inet_ntop6 (src, dst, cnt));
104# endif
105
106    default:
107      errno = EAFNOSUPPORT;
108      return (NULL);
109    }
110  /* NOTREACHED */
111}
112
113/* const char *
114 * inet_ntop4(src, dst, size)
115 *      format an IPv4 address
116 * return:
117 *      'dst' (as a const)
118 * notes:
119 *      (1) uses no statics
120 *      (2) takes a u_char* not an in_addr as input
121 * author:
122 *      Paul Vixie, 1996.
123 */
124static const char *
125inet_ntop4 (const unsigned char *src, char *dst, socklen_t size)
126{
127  char tmp[sizeof "255.255.255.255"];
128  int len;
129
130  len = sprintf (tmp, "%u.%u.%u.%u", src[0], src[1], src[2], src[3]);
131  if (len < 0)
132    return NULL;
133
134  if (len > size)
135    {
136      errno = ENOSPC;
137      return NULL;
138    }
139
140  return strcpy (dst, tmp);
141}
142
143# if HAVE_IPV6
144
145/* const char *
146 * inet_ntop6(src, dst, size)
147 *      convert IPv6 binary address into presentation (printable) format
148 * author:
149 *      Paul Vixie, 1996.
150 */
151static const char *
152inet_ntop6 (const unsigned char *src, char *dst, socklen_t size)
153{
154  /*
155   * Note that int32_t and int16_t need only be "at least" large enough
156   * to contain a value of the specified size.  On some systems, like
157   * Crays, there is no such thing as an integer variable with 16 bits.
158   * Keep this in mind if you think this function should have been coded
159   * to use pointer overlays.  All the world's not a VAX.
160   */
161  char tmp[sizeof "ffff:ffff:ffff:ffff:ffff:ffff:255.255.255.255"], *tp;
162  struct
163  {
164    int base, len;
165  } best, cur;
166  unsigned int words[NS_IN6ADDRSZ / NS_INT16SZ];
167  int i;
168
169  /*
170   * Preprocess:
171   *      Copy the input (bytewise) array into a wordwise array.
172   *      Find the longest run of 0x00's in src[] for :: shorthanding.
173   */
174  memset (words, '\0', sizeof words);
175  for (i = 0; i < NS_IN6ADDRSZ; i += 2)
176    words[i / 2] = (src[i] << 8) | src[i + 1];
177  best.base = -1;
178  cur.base = -1;
179  IF_LINT(best.len = 0);
180  IF_LINT(cur.len = 0);
181  for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++)
182    {
183      if (words[i] == 0)
184        {
185          if (cur.base == -1)
186            cur.base = i, cur.len = 1;
187          else
188            cur.len++;
189        }
190      else
191        {
192          if (cur.base != -1)
193            {
194              if (best.base == -1 || cur.len > best.len)
195                best = cur;
196              cur.base = -1;
197            }
198        }
199    }
200  if (cur.base != -1)
201    {
202      if (best.base == -1 || cur.len > best.len)
203        best = cur;
204    }
205  if (best.base != -1 && best.len < 2)
206    best.base = -1;
207
208  /*
209   * Format the result.
210   */
211  tp = tmp;
212  for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++)
213    {
214      /* Are we inside the best run of 0x00's? */
215      if (best.base != -1 && i >= best.base && i < (best.base + best.len))
216        {
217          if (i == best.base)
218            *tp++ = ':';
219          continue;
220        }
221      /* Are we following an initial run of 0x00s or any real hex? */
222      if (i != 0)
223        *tp++ = ':';
224      /* Is this address an encapsulated IPv4? */
225      if (i == 6 && best.base == 0 &&
226          (best.len == 6 || (best.len == 5 && words[5] == 0xffff)))
227        {
228          if (!inet_ntop4 (src + 12, tp, sizeof tmp - (tp - tmp)))
229            return (NULL);
230          tp += strlen (tp);
231          break;
232        }
233      {
234        int len = sprintf (tp, "%x", words[i]);
235        if (len < 0)
236          return NULL;
237        tp += len;
238      }
239    }
240  /* Was it a trailing run of 0x00's? */
241  if (best.base != -1 && (best.base + best.len) ==
242      (NS_IN6ADDRSZ / NS_INT16SZ))
243    *tp++ = ':';
244  *tp++ = '\0';
245
246  /*
247   * Check for overflow, copy, and we're done.
248   */
249  if ((socklen_t) (tp - tmp) > size)
250    {
251      errno = ENOSPC;
252      return NULL;
253    }
254
255  return strcpy (dst, tmp);
256}
257
258# endif
259
260#endif
261