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 #ifdef HAVE_CONFIG_H
40 #include <config.h>
41 #endif
42
43 #include "netdissect-stdinc.h"
44 #include "addrtostr.h"
45
46 #include <stdio.h>
47 #include <string.h>
48
49 /*
50 *
51 */
52
53 #ifndef IN6ADDRSZ
54 #define IN6ADDRSZ 16 /* IPv6 T_AAAA */
55 #endif
56
57 #ifndef INT16SZ
58 #define INT16SZ 2 /* word size */
59 #endif
60
61 const char *
addrtostr(const void * src,char * dst,size_t size)62 addrtostr (const void *src, char *dst, size_t size)
63 {
64 const u_char *srcaddr = (const u_char *)src;
65 const char digits[] = "0123456789";
66 int i;
67 const char *orig_dst = dst;
68
69 if (size < INET_ADDRSTRLEN) {
70 errno = ENOSPC;
71 return NULL;
72 }
73 for (i = 0; i < 4; ++i) {
74 int n = *srcaddr++;
75 int non_zerop = 0;
76
77 if (non_zerop || n / 100 > 0) {
78 *dst++ = digits[n / 100];
79 n %= 100;
80 non_zerop = 1;
81 }
82 if (non_zerop || n / 10 > 0) {
83 *dst++ = digits[n / 10];
84 n %= 10;
85 non_zerop = 1;
86 }
87 *dst++ = digits[n];
88 if (i != 3)
89 *dst++ = '.';
90 }
91 *dst++ = '\0';
92 return orig_dst;
93 }
94
95 /*
96 * Convert IPv6 binary address into presentation (printable) format.
97 */
98 const char *
addrtostr6(const void * src,char * dst,size_t size)99 addrtostr6 (const void *src, char *dst, size_t size)
100 {
101 /*
102 * Note that int32_t and int16_t need only be "at least" large enough
103 * to contain a value of the specified size. On some systems, like
104 * Crays, there is no such thing as an integer variable with 16 bits.
105 * Keep this in mind if you think this function should have been coded
106 * to use pointer overlays. All the world's not a VAX.
107 */
108 const u_char *srcaddr = (const u_char *)src;
109 char *dp;
110 size_t space_left, added_space;
111 int snprintfed;
112 struct {
113 int base;
114 int len;
115 } best, cur;
116 uint16_t words [IN6ADDRSZ / INT16SZ];
117 int i;
118
119 /* Preprocess:
120 * Copy the input (bytewise) array into a wordwise array.
121 * Find the longest run of 0x00's in src[] for :: shorthanding.
122 */
123 for (i = 0; i < (IN6ADDRSZ / INT16SZ); i++)
124 words[i] = (srcaddr[2*i] << 8) | srcaddr[2*i + 1];
125
126 best.len = 0;
127 best.base = -1;
128 cur.len = 0;
129 cur.base = -1;
130 for (i = 0; i < (IN6ADDRSZ / INT16SZ); i++)
131 {
132 if (words[i] == 0)
133 {
134 if (cur.base == -1)
135 cur.base = i, cur.len = 1;
136 else cur.len++;
137 }
138 else if (cur.base != -1)
139 {
140 if (best.base == -1 || cur.len > best.len)
141 best = cur;
142 cur.base = -1;
143 }
144 }
145 if ((cur.base != -1) && (best.base == -1 || cur.len > best.len))
146 best = cur;
147 if (best.base != -1 && best.len < 2)
148 best.base = -1;
149
150 /* Format the result.
151 */
152 dp = dst;
153 space_left = size;
154 #define APPEND_CHAR(c) \
155 { \
156 if (space_left == 0) { \
157 errno = ENOSPC; \
158 return (NULL); \
159 } \
160 *dp++ = c; \
161 space_left--; \
162 }
163 for (i = 0; i < (IN6ADDRSZ / INT16SZ); i++)
164 {
165 /* Are we inside the best run of 0x00's?
166 */
167 if (best.base != -1 && i >= best.base && i < (best.base + best.len))
168 {
169 if (i == best.base)
170 APPEND_CHAR(':');
171 continue;
172 }
173
174 /* Are we following an initial run of 0x00s or any real hex?
175 */
176 if (i != 0)
177 APPEND_CHAR(':');
178
179 /* Is this address an encapsulated IPv4?
180 */
181 if (i == 6 && best.base == 0 &&
182 (best.len == 6 || (best.len == 5 && words[5] == 0xffff)))
183 {
184 if (!addrtostr(srcaddr+12, dp, space_left))
185 {
186 errno = ENOSPC;
187 return (NULL);
188 }
189 added_space = strlen(dp);
190 dp += added_space;
191 space_left -= added_space;
192 break;
193 }
194 snprintfed = snprintf (dp, space_left, "%x", words[i]);
195 if (snprintfed < 0)
196 return (NULL);
197 if ((size_t) snprintfed >= space_left)
198 {
199 errno = ENOSPC;
200 return (NULL);
201 }
202 dp += snprintfed;
203 space_left -= snprintfed;
204 }
205
206 /* Was it a trailing run of 0x00's?
207 */
208 if (best.base != -1 && (best.base + best.len) == (IN6ADDRSZ / INT16SZ))
209 APPEND_CHAR(':');
210 APPEND_CHAR('\0');
211
212 return (dst);
213 }
214