1 /* $OpenBSD: inet_ntop.c,v 1.8 2008/12/09 19:38:38 otto Exp $ */ 2 3 /* Copyright (c) 1996 by Internet Software Consortium. 4 * 5 * Permission to use, copy, modify, and distribute this software for any 6 * purpose with or without fee is hereby granted, provided that the above 7 * copyright notice and this permission notice appear in all copies. 8 * 9 * THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM DISCLAIMS 10 * ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES 11 * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE 12 * CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL 13 * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR 14 * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS 15 * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS 16 * SOFTWARE. 17 */ 18 19 /* OPENBSD ORIGINAL: lib/libc/net/inet_ntop.c */ 20 21 #include "includes.h" 22 23 #ifndef HAVE_INET_NTOP 24 25 #include <sys/types.h> 26 #include <sys/socket.h> 27 #include <netinet/in.h> 28 #include <arpa/inet.h> 29 #include <arpa/nameser.h> 30 #include <string.h> 31 #include <errno.h> 32 #include <stdio.h> 33 34 #ifndef IN6ADDRSZ 35 #define IN6ADDRSZ 16 /* IPv6 T_AAAA */ 36 #endif 37 38 #ifndef INT16SZ 39 #define INT16SZ 2 /* for systems without 16-bit ints */ 40 #endif 41 42 /* 43 * WARNING: Don't even consider trying to compile this on a system where 44 * sizeof(int) < 4. sizeof(int) > 4 is fine; all the world's not a VAX. 45 */ 46 47 static const char *inet_ntop4(const u_char *src, char *dst, size_t size); 48 static const char *inet_ntop6(const u_char *src, char *dst, size_t size); 49 50 /* char * 51 * inet_ntop(af, src, dst, size) 52 * convert a network format address to presentation format. 53 * return: 54 * pointer to presentation format address (`dst'), or NULL (see errno). 55 * author: 56 * Paul Vixie, 1996. 57 */ 58 const char * 59 inet_ntop(int af, const void *src, char *dst, socklen_t size) 60 { 61 switch (af) { 62 case AF_INET: 63 return (inet_ntop4(src, dst, (size_t)size)); 64 case AF_INET6: 65 return (inet_ntop6(src, dst, (size_t)size)); 66 default: 67 errno = EAFNOSUPPORT; 68 return (NULL); 69 } 70 /* NOTREACHED */ 71 } 72 73 /* const char * 74 * inet_ntop4(src, dst, size) 75 * format an IPv4 address, more or less like inet_ntoa() 76 * return: 77 * `dst' (as a const) 78 * notes: 79 * (1) uses no statics 80 * (2) takes a u_char* not an in_addr as input 81 * author: 82 * Paul Vixie, 1996. 83 */ 84 static const char * 85 inet_ntop4(const u_char *src, char *dst, size_t size) 86 { 87 static const char fmt[] = "%u.%u.%u.%u"; 88 char tmp[sizeof "255.255.255.255"]; 89 int l; 90 91 l = snprintf(tmp, size, fmt, src[0], src[1], src[2], src[3]); 92 if (l <= 0 || l >= size) { 93 errno = ENOSPC; 94 return (NULL); 95 } 96 strlcpy(dst, tmp, size); 97 return (dst); 98 } 99 100 /* const char * 101 * inet_ntop6(src, dst, size) 102 * convert IPv6 binary address into presentation (printable) format 103 * author: 104 * Paul Vixie, 1996. 105 */ 106 static const char * 107 inet_ntop6(const u_char *src, char *dst, size_t size) 108 { 109 /* 110 * Note that int32_t and int16_t need only be "at least" large enough 111 * to contain a value of the specified size. On some systems, like 112 * Crays, there is no such thing as an integer variable with 16 bits. 113 * Keep this in mind if you think this function should have been coded 114 * to use pointer overlays. All the world's not a VAX. 115 */ 116 char tmp[sizeof "ffff:ffff:ffff:ffff:ffff:ffff:255.255.255.255"]; 117 char *tp, *ep; 118 struct { int base, len; } best, cur; 119 u_int words[IN6ADDRSZ / INT16SZ]; 120 int i; 121 int advance; 122 123 /* 124 * Preprocess: 125 * Copy the input (bytewise) array into a wordwise array. 126 * Find the longest run of 0x00's in src[] for :: shorthanding. 127 */ 128 memset(words, '\0', sizeof words); 129 for (i = 0; i < IN6ADDRSZ; i++) 130 words[i / 2] |= (src[i] << ((1 - (i % 2)) << 3)); 131 best.base = -1; 132 cur.base = -1; 133 for (i = 0; i < (IN6ADDRSZ / INT16SZ); i++) { 134 if (words[i] == 0) { 135 if (cur.base == -1) 136 cur.base = i, cur.len = 1; 137 else 138 cur.len++; 139 } else { 140 if (cur.base != -1) { 141 if (best.base == -1 || cur.len > best.len) 142 best = cur; 143 cur.base = -1; 144 } 145 } 146 } 147 if (cur.base != -1) { 148 if (best.base == -1 || cur.len > best.len) 149 best = cur; 150 } 151 if (best.base != -1 && best.len < 2) 152 best.base = -1; 153 154 /* 155 * Format the result. 156 */ 157 tp = tmp; 158 ep = tmp + sizeof(tmp); 159 for (i = 0; i < (IN6ADDRSZ / INT16SZ) && tp < ep; i++) { 160 /* Are we inside the best run of 0x00's? */ 161 if (best.base != -1 && i >= best.base && 162 i < (best.base + best.len)) { 163 if (i == best.base) { 164 if (tp + 1 >= ep) 165 return (NULL); 166 *tp++ = ':'; 167 } 168 continue; 169 } 170 /* Are we following an initial run of 0x00s or any real hex? */ 171 if (i != 0) { 172 if (tp + 1 >= ep) 173 return (NULL); 174 *tp++ = ':'; 175 } 176 /* Is this address an encapsulated IPv4? */ 177 if (i == 6 && best.base == 0 && 178 (best.len == 6 || (best.len == 5 && words[5] == 0xffff))) { 179 if (!inet_ntop4(src+12, tp, (size_t)(ep - tp))) 180 return (NULL); 181 tp += strlen(tp); 182 break; 183 } 184 advance = snprintf(tp, ep - tp, "%x", words[i]); 185 if (advance <= 0 || advance >= ep - tp) 186 return (NULL); 187 tp += advance; 188 } 189 /* Was it a trailing run of 0x00's? */ 190 if (best.base != -1 && (best.base + best.len) == (IN6ADDRSZ / INT16SZ)) { 191 if (tp + 1 >= ep) 192 return (NULL); 193 *tp++ = ':'; 194 } 195 if (tp + 1 >= ep) 196 return (NULL); 197 *tp++ = '\0'; 198 199 /* 200 * Check for overflow, copy, and we're done. 201 */ 202 if ((size_t)(tp - tmp) > size) { 203 errno = ENOSPC; 204 return (NULL); 205 } 206 strlcpy(dst, tmp, size); 207 return (dst); 208 } 209 210 #endif /* !HAVE_INET_NTOP */ 211