1/*
2 * Copyright (c) 1999 Kungliga Tekniska Högskolan
3 * (Royal Institute of Technology, Stockholm, Sweden).
4 * All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 *
10 * 1. Redistributions of source code must retain the above copyright
11 *    notice, this list of conditions and the following disclaimer.
12 *
13 * 2. Redistributions in binary form must reproduce the above copyright
14 *    notice, this list of conditions and the following disclaimer in the
15 *    documentation and/or other materials provided with the distribution.
16 *
17 * 3. All advertising materials mentioning features or use of this software
18 *    must display the following acknowledgement:
19 *      This product includes software developed by the Kungliga Tekniska
20 *      Högskolan and its contributors.
21 *
22 * 4. Neither the name of the Institute nor the names of its contributors
23 *    may be used to endorse or promote products derived from this software
24 *    without specific prior written permission.
25 *
26 * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
27 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
28 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
29 * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
30 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
31 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
32 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
33 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
34 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
35 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
36 * SUCH DAMAGE.
37 */
38
39/* $Id: inet_ntop.c,v 1.8 2005/02/09 02:25:46 guy Exp $ */
40
41#ifndef lint
42static const char rcsid[] _U_ =
43     "@(#) $Header: /tcpdump/master/tcpdump/missing/inet_ntop.c,v 1.8 2005/02/09 02:25:46 guy Exp $";
44#endif
45
46#include <tcpdump-stdinc.h>
47
48#include <stdio.h>
49#include <errno.h>
50
51/*
52 *
53 */
54
55#ifndef IN6ADDRSZ
56#define IN6ADDRSZ   16   /* IPv6 T_AAAA */
57#endif
58
59#ifndef INT16SZ
60#define INT16SZ     2    /* word size */
61#endif
62
63static const char *
64inet_ntop_v4 (const void *src, char *dst, size_t size)
65{
66    const char digits[] = "0123456789";
67    int i;
68    struct in_addr *addr = (struct in_addr *)src;
69    u_long a = ntohl(addr->s_addr);
70    const char *orig_dst = dst;
71
72    if (size < INET_ADDRSTRLEN) {
73	errno = ENOSPC;
74	return NULL;
75    }
76    for (i = 0; i < 4; ++i) {
77	int n = (a >> (24 - i * 8)) & 0xFF;
78	int non_zerop = 0;
79
80	if (non_zerop || n / 100 > 0) {
81	    *dst++ = digits[n / 100];
82	    n %= 100;
83	    non_zerop = 1;
84	}
85	if (non_zerop || n / 10 > 0) {
86	    *dst++ = digits[n / 10];
87	    n %= 10;
88	    non_zerop = 1;
89	}
90	*dst++ = digits[n];
91	if (i != 3)
92	    *dst++ = '.';
93    }
94    *dst++ = '\0';
95    return orig_dst;
96}
97
98#ifdef INET6
99/*
100 * Convert IPv6 binary address into presentation (printable) format.
101 */
102static const char *
103inet_ntop_v6 (const u_char *src, char *dst, size_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 [INET6_ADDRSTRLEN+1];
113  char *tp;
114  struct {
115    long base;
116    long len;
117  } best, cur;
118  u_long words [IN6ADDRSZ / INT16SZ];
119  int    i;
120
121  /* Preprocess:
122   *  Copy the input (bytewise) array into a wordwise array.
123   *  Find the longest run of 0x00's in src[] for :: shorthanding.
124   */
125  memset (words, 0, sizeof(words));
126  for (i = 0; i < IN6ADDRSZ; i++)
127      words[i/2] |= (src[i] << ((1 - (i % 2)) << 3));
128
129  best.base = -1;
130  cur.base  = -1;
131  for (i = 0; i < (IN6ADDRSZ / INT16SZ); i++)
132  {
133    if (words[i] == 0)
134    {
135      if (cur.base == -1)
136           cur.base = i, cur.len = 1;
137      else cur.len++;
138    }
139    else if (cur.base != -1)
140    {
141      if (best.base == -1 || cur.len > best.len)
142         best = cur;
143      cur.base = -1;
144    }
145  }
146  if ((cur.base != -1) && (best.base == -1 || cur.len > best.len))
147     best = cur;
148  if (best.base != -1 && best.len < 2)
149     best.base = -1;
150
151  /* Format the result.
152   */
153  tp = tmp;
154  for (i = 0; i < (IN6ADDRSZ / INT16SZ); i++)
155  {
156    /* Are we inside the best run of 0x00's?
157     */
158    if (best.base != -1 && i >= best.base && i < (best.base + best.len))
159    {
160      if (i == best.base)
161         *tp++ = ':';
162      continue;
163    }
164
165    /* Are we following an initial run of 0x00s or any real hex?
166     */
167    if (i != 0)
168       *tp++ = ':';
169
170    /* Is this address an encapsulated IPv4?
171     */
172    if (i == 6 && best.base == 0 &&
173        (best.len == 6 || (best.len == 5 && words[5] == 0xffff)))
174    {
175      if (!inet_ntop_v4(src+12, tp, sizeof(tmp) - (tp - tmp)))
176      {
177        errno = ENOSPC;
178        return (NULL);
179      }
180      tp += strlen(tp);
181      break;
182    }
183    tp += sprintf (tp, "%lX", words[i]);
184  }
185
186  /* Was it a trailing run of 0x00's?
187   */
188  if (best.base != -1 && (best.base + best.len) == (IN6ADDRSZ / INT16SZ))
189     *tp++ = ':';
190  *tp++ = '\0';
191
192  /* Check for overflow, copy, and we're done.
193   */
194  if ((size_t)(tp - tmp) > size)
195  {
196    errno = ENOSPC;
197    return (NULL);
198  }
199  return strcpy (dst, tmp);
200  return (NULL);
201}
202#endif   /* INET6 */
203
204
205const char *
206inet_ntop(int af, const void *src, char *dst, size_t size)
207{
208    switch (af) {
209    case AF_INET :
210	return inet_ntop_v4 (src, dst, size);
211#ifdef INET6
212    case AF_INET6:
213         return inet_ntop_v6 ((const u_char*)src, dst, size);
214#endif
215    default :
216	errno = EAFNOSUPPORT;
217	return NULL;
218    }
219}
220