1 /* $NetBSD: inet_ntop.c,v 1.2 2004/05/20 23:12:33 christos Exp $ */ 2 3 /* 4 * Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC") 5 * Copyright (c) 1996-1999 by Internet Software Consortium. 6 * 7 * Permission to use, copy, modify, and distribute this software for any 8 * purpose with or without fee is hereby granted, provided that the above 9 * copyright notice and this permission notice appear in all copies. 10 * 11 * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES 12 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 13 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR 14 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 15 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN 16 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT 17 * OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 18 */ 19 20 #include <sys/cdefs.h> 21 #if defined(LIBC_SCCS) && !defined(lint) 22 #if 0 23 static const char rcsid[] = "Id: inet_ntop.c,v 1.1.2.1.8.1 2004/03/09 08:33:33 marka Exp"; 24 #else 25 __RCSID("$NetBSD: inet_ntop.c,v 1.2 2004/05/20 23:12:33 christos Exp $"); 26 #endif 27 #endif /* LIBC_SCCS and not lint */ 28 29 #include "port_before.h" 30 31 #include "namespace.h" 32 #include <sys/param.h> 33 #include <sys/types.h> 34 #include <sys/socket.h> 35 36 #include <netinet/in.h> 37 #include <arpa/inet.h> 38 #include <arpa/nameser.h> 39 40 #include <assert.h> 41 #include <errno.h> 42 #include <stdio.h> 43 #include <stdlib.h> 44 #include <string.h> 45 46 #include "port_after.h" 47 48 #ifdef __weak_alias 49 __weak_alias(inet_ntop,_inet_ntop) 50 #endif 51 52 /* 53 * WARNING: Don't even consider trying to compile this on a system where 54 * sizeof(int) < 4. sizeof(int) > 4 is fine; all the world's not a VAX. 55 */ 56 57 static const char *inet_ntop4(const u_char *src, char *dst, socklen_t size); 58 static const char *inet_ntop6(const u_char *src, char *dst, socklen_t size); 59 60 /* char * 61 * inet_ntop(af, src, dst, size) 62 * convert a network format address to presentation format. 63 * return: 64 * pointer to presentation format address (`dst'), or NULL (see errno). 65 * author: 66 * Paul Vixie, 1996. 67 */ 68 const char * 69 inet_ntop(af, src, dst, size) 70 int af; 71 const void *src; 72 char *dst; 73 socklen_t size; 74 { 75 76 _DIAGASSERT(src != NULL); 77 _DIAGASSERT(dst != NULL); 78 79 switch (af) { 80 case AF_INET: 81 return (inet_ntop4(src, dst, size)); 82 case AF_INET6: 83 return (inet_ntop6(src, dst, size)); 84 default: 85 errno = EAFNOSUPPORT; 86 return (NULL); 87 } 88 /* NOTREACHED */ 89 } 90 91 /* const char * 92 * inet_ntop4(src, dst, size) 93 * format an IPv4 address, more or less like inet_ntoa() 94 * return: 95 * `dst' (as a const) 96 * notes: 97 * (1) uses no statics 98 * (2) takes a u_char* not an in_addr as input 99 * author: 100 * Paul Vixie, 1996. 101 */ 102 static const char * 103 inet_ntop4(src, dst, size) 104 const u_char *src; 105 char *dst; 106 socklen_t size; 107 { 108 char tmp[sizeof "255.255.255.255"]; 109 int l; 110 111 _DIAGASSERT(src != NULL); 112 _DIAGASSERT(dst != NULL); 113 114 l = snprintf(tmp, sizeof(tmp), "%u.%u.%u.%u", 115 src[0], src[1], src[2], src[3]); 116 if (l <= 0 || (socklen_t) l >= size) { 117 errno = ENOSPC; 118 return (NULL); 119 } 120 strlcpy(dst, tmp, size); 121 return (dst); 122 } 123 124 /* const char * 125 * inet_ntop6(src, dst, size) 126 * convert IPv6 binary address into presentation (printable) format 127 * author: 128 * Paul Vixie, 1996. 129 */ 130 static const char * 131 inet_ntop6(src, dst, size) 132 const u_char *src; 133 char *dst; 134 socklen_t size; 135 { 136 /* 137 * Note that int32_t and int16_t need only be "at least" large enough 138 * to contain a value of the specified size. On some systems, like 139 * Crays, there is no such thing as an integer variable with 16 bits. 140 * Keep this in mind if you think this function should have been coded 141 * to use pointer overlays. All the world's not a VAX. 142 */ 143 char tmp[sizeof "ffff:ffff:ffff:ffff:ffff:ffff:255.255.255.255"]; 144 char *tp, *ep; 145 struct { int base, len; } best, cur; 146 u_int words[NS_IN6ADDRSZ / NS_INT16SZ]; 147 int i; 148 int advance; 149 150 _DIAGASSERT(src != NULL); 151 _DIAGASSERT(dst != NULL); 152 153 /* 154 * Preprocess: 155 * Copy the input (bytewise) array into a wordwise array. 156 * Find the longest run of 0x00's in src[] for :: shorthanding. 157 */ 158 memset(words, '\0', sizeof words); 159 for (i = 0; i < NS_IN6ADDRSZ; i++) 160 words[i / 2] |= (src[i] << ((1 - (i % 2)) << 3)); 161 best.base = -1; 162 cur.base = -1; 163 for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) { 164 if (words[i] == 0) { 165 if (cur.base == -1) 166 cur.base = i, cur.len = 1; 167 else 168 cur.len++; 169 } else { 170 if (cur.base != -1) { 171 if (best.base == -1 || cur.len > best.len) 172 best = cur; 173 cur.base = -1; 174 } 175 } 176 } 177 if (cur.base != -1) { 178 if (best.base == -1 || cur.len > best.len) 179 best = cur; 180 } 181 if (best.base != -1 && best.len < 2) 182 best.base = -1; 183 184 /* 185 * Format the result. 186 */ 187 tp = tmp; 188 ep = tmp + sizeof(tmp); 189 for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) { 190 /* Are we inside the best run of 0x00's? */ 191 if (best.base != -1 && i >= best.base && 192 i < (best.base + best.len)) { 193 if (i == best.base) 194 *tp++ = ':'; 195 continue; 196 } 197 /* Are we following an initial run of 0x00s or any real hex? */ 198 if (i != 0) { 199 if (tp + 1 >= ep) 200 return (NULL); 201 *tp++ = ':'; 202 } 203 /* Is this address an encapsulated IPv4? */ 204 if (i == 6 && best.base == 0 && 205 (best.len == 6 || 206 (best.len == 7 && words[7] != 0x0001) || 207 (best.len == 5 && words[5] == 0xffff))) { 208 if (!inet_ntop4(src+12, tp, (socklen_t)(ep - tp))) 209 return (NULL); 210 tp += strlen(tp); 211 break; 212 } 213 advance = snprintf(tp, (size_t)(ep - tp), "%x", words[i]); 214 if (advance <= 0 || advance >= ep - tp) 215 return (NULL); 216 tp += advance; 217 } 218 /* Was it a trailing run of 0x00's? */ 219 if (best.base != -1 && (best.base + best.len) == 220 (NS_IN6ADDRSZ / NS_INT16SZ)) { 221 if (tp + 1 >= ep) 222 return (NULL); 223 *tp++ = ':'; 224 } 225 if (tp + 1 >= ep) 226 return (NULL); 227 *tp++ = '\0'; 228 229 /* 230 * Check for overflow, copy, and we're done. 231 */ 232 if ((size_t)(tp - tmp) > size) { 233 errno = ENOSPC; 234 return (NULL); 235 } 236 strlcpy(dst, tmp, size); 237 return (dst); 238 } 239