1 /*
2 * Copyright (C) Internet Systems Consortium, Inc. ("ISC")
3 *
4 * This Source Code Form is subject to the terms of the Mozilla Public
5 * License, v. 2.0. If a copy of the MPL was not distributed with this
6 * file, you can obtain one at https://mozilla.org/MPL/2.0/.
7 *
8 * See the COPYRIGHT file distributed with this work for additional
9 * information regarding copyright ownership.
10 */
11
12 /*! \file lwinetntop.c */
13
14 #include <config.h>
15
16 #include <errno.h>
17 #include <stdio.h>
18 #include <string.h>
19
20 #include <lwres/net.h>
21 #include "print_p.h"
22
23 #define NS_INT16SZ 2
24 #define NS_IN6ADDRSZ 16
25
26 /*
27 * WARNING: Don't even consider trying to compile this on a system where
28 * sizeof(int) < 4. sizeof(int) > 4 is fine; all the world's not a VAX.
29 */
30
31 static const char *inet_ntop4(const unsigned char *src, char *dst,
32 size_t size);
33
34 #ifdef AF_INET6
35 static const char *inet_ntop6(const unsigned char *src, char *dst,
36 size_t size);
37 #endif
38
39 /*! char *
40 * lwres_net_ntop(af, src, dst, size)
41 * convert a network format address to presentation format.
42 * return:
43 * pointer to presentation format address (`dst'), or NULL (see errno).
44 * author:
45 * Paul Vixie, 1996.
46 */
47 const char *
lwres_net_ntop(int af,const void * src,char * dst,size_t size)48 lwres_net_ntop(int af, const void *src, char *dst, size_t size) {
49 switch (af) {
50 case AF_INET:
51 return (inet_ntop4(src, dst, size));
52 #ifdef AF_INET6
53 case AF_INET6:
54 return (inet_ntop6(src, dst, size));
55 #endif
56 default:
57 errno = EAFNOSUPPORT;
58 return (NULL);
59 }
60 /* NOTREACHED */
61 }
62
63 /*! const char *
64 * inet_ntop4(src, dst, size)
65 * format an IPv4 address
66 * return:
67 * `dst' (as a const)
68 * notes:
69 * (1) uses no statics
70 * (2) takes a unsigned char* not an in_addr as input
71 * author:
72 * Paul Vixie, 1996.
73 */
74 static const char *
inet_ntop4(const unsigned char * src,char * dst,size_t size)75 inet_ntop4(const unsigned char *src, char *dst, size_t size) {
76 static const char fmt[] = "%u.%u.%u.%u";
77 char tmp[sizeof("255.255.255.255")];
78 size_t len;
79
80 len = snprintf(tmp, sizeof(tmp), fmt, src[0], src[1], src[2], src[3]);
81 if (len >= size) {
82 errno = ENOSPC;
83 return (NULL);
84 }
85 strcpy(dst, tmp);
86
87 return (dst);
88 }
89
90 /*! const char *
91 * inet_ntop6(src, dst, size)
92 * convert IPv6 binary address into presentation (printable) format
93 * author:
94 * Paul Vixie, 1996.
95 */
96 #ifdef AF_INET6
97 static const char *
inet_ntop6(const unsigned char * src,char * dst,size_t size)98 inet_ntop6(const unsigned char *src, char *dst, size_t size) {
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 char tmp[sizeof("ffff:ffff:ffff:ffff:ffff:ffff:255.255.255.255")], *tp;
107 struct { int base, len; } best, cur;
108 unsigned int words[NS_IN6ADDRSZ / NS_INT16SZ];
109 int i;
110
111 /*
112 * Preprocess:
113 * Copy the input (bytewise) array into a wordwise array.
114 * Find the longest run of 0x00's in src[] for :: shorthanding.
115 */
116 memset(words, '\0', sizeof(words));
117 for (i = 0; i < NS_IN6ADDRSZ; i++)
118 words[i / 2] |= (src[i] << ((1 - (i % 2)) << 3));
119 best.base = -1;
120 best.len = 0;
121 cur.base = -1;
122 cur.len = 0;
123 for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) {
124 if (words[i] == 0) {
125 if (cur.base == -1)
126 cur.base = i, cur.len = 1;
127 else
128 cur.len++;
129 } else {
130 if (cur.base != -1) {
131 if (best.base == -1 || cur.len > best.len)
132 best = cur;
133 cur.base = -1;
134 }
135 }
136 }
137 if (cur.base != -1) {
138 if (best.base == -1 || cur.len > best.len)
139 best = cur;
140 }
141 if (best.base != -1 && best.len < 2)
142 best.base = -1;
143
144 /*
145 * Format the result.
146 */
147 tp = tmp;
148 for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) {
149 /* Are we inside the best run of 0x00's? */
150 if (best.base != -1 && i >= best.base &&
151 i < (best.base + best.len)) {
152 if (i == best.base)
153 *tp++ = ':';
154 continue;
155 }
156 /* Are we following an initial run of 0x00s or any real hex? */
157 if (i != 0)
158 *tp++ = ':';
159 /* Is this address an encapsulated IPv4? */
160 if (i == 6 && best.base == 0 &&
161 (best.len == 6 || (best.len == 5 && words[5] == 0xffff))) {
162 if (!inet_ntop4(src+12, tp,
163 sizeof(tmp) - (tp - tmp)))
164 return (NULL);
165 tp += strlen(tp);
166 break;
167 }
168 tp += sprintf(tp, "%x", words[i]); /* XXX */
169 }
170 /* Was it a trailing run of 0x00's? */
171 if (best.base != -1 && (best.base + best.len) ==
172 (NS_IN6ADDRSZ / NS_INT16SZ))
173 *tp++ = ':';
174 *tp++ = '\0';
175
176 /*
177 * Check for overflow, copy, and we're done.
178 */
179 if ((size_t)(tp - tmp) > size) {
180 errno = ENOSPC;
181 return (NULL);
182 }
183 strcpy(dst, tmp);
184 return (dst);
185 }
186 #endif /* AF_INET6 */
187