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