inet_ntop.c revision 124208
1/* $OpenBSD: inet_ntop.c,v 1.5 2002/08/23 16:27:31 itojun 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#include "includes.h" 20 21#ifndef HAVE_INET_NTOP 22 23#if defined(LIBC_SCCS) && !defined(lint) 24#if 0 25static char rcsid[] = "$From: inet_ntop.c,v 8.7 1996/08/05 08:41:18 vixie Exp $"; 26#else 27static char rcsid[] = "$OpenBSD: inet_ntop.c,v 1.5 2002/08/23 16:27:31 itojun Exp $"; 28#endif 29#endif /* LIBC_SCCS and not lint */ 30 31#include <sys/param.h> 32#include <sys/types.h> 33#include <sys/socket.h> 34#include <netinet/in.h> 35#include <arpa/inet.h> 36#ifndef HAVE_CYGWIN 37#include <arpa/nameser.h> 38#endif 39#include <string.h> 40#include <errno.h> 41#include <stdio.h> 42 43#ifndef IN6ADDRSZ 44#define IN6ADDRSZ 16 /* IPv6 T_AAAA */ 45#endif 46 47#ifndef INT16SZ 48#define INT16SZ 2 /* for systems without 16-bit ints */ 49#endif 50 51/* 52 * WARNING: Don't even consider trying to compile this on a system where 53 * sizeof(int) < 4. sizeof(int) > 4 is fine; all the world's not a VAX. 54 */ 55 56static const char *inet_ntop4(const u_char *src, char *dst, size_t size); 57static const char *inet_ntop6(const u_char *src, char *dst, size_t size); 58 59/* char * 60 * inet_ntop(af, src, dst, size) 61 * convert a network format address to presentation format. 62 * return: 63 * pointer to presentation format address (`dst'), or NULL (see errno). 64 * author: 65 * Paul Vixie, 1996. 66 */ 67const char * 68inet_ntop(af, src, dst, size) 69 int af; 70 const void *src; 71 char *dst; 72 size_t size; 73{ 74 switch (af) { 75 case AF_INET: 76 return (inet_ntop4(src, dst, size)); 77 case AF_INET6: 78 return (inet_ntop6(src, dst, size)); 79 default: 80 errno = EAFNOSUPPORT; 81 return (NULL); 82 } 83 /* NOTREACHED */ 84} 85 86/* const char * 87 * inet_ntop4(src, dst, size) 88 * format an IPv4 address, more or less like inet_ntoa() 89 * return: 90 * `dst' (as a const) 91 * notes: 92 * (1) uses no statics 93 * (2) takes a u_char* not an in_addr as input 94 * author: 95 * Paul Vixie, 1996. 96 */ 97static const char * 98inet_ntop4(src, dst, size) 99 const u_char *src; 100 char *dst; 101 size_t size; 102{ 103 static const char fmt[] = "%u.%u.%u.%u"; 104 char tmp[sizeof "255.255.255.255"]; 105 int l; 106 107 l = snprintf(tmp, size, fmt, src[0], src[1], src[2], src[3]); 108 if (l <= 0 || l >= size) { 109 errno = ENOSPC; 110 return (NULL); 111 } 112 strlcpy(dst, tmp, size); 113 return (dst); 114} 115 116/* const char * 117 * inet_ntop6(src, dst, size) 118 * convert IPv6 binary address into presentation (printable) format 119 * author: 120 * Paul Vixie, 1996. 121 */ 122static const char * 123inet_ntop6(src, dst, size) 124 const u_char *src; 125 char *dst; 126 size_t size; 127{ 128 /* 129 * Note that int32_t and int16_t need only be "at least" large enough 130 * to contain a value of the specified size. On some systems, like 131 * Crays, there is no such thing as an integer variable with 16 bits. 132 * Keep this in mind if you think this function should have been coded 133 * to use pointer overlays. All the world's not a VAX. 134 */ 135 char tmp[sizeof "ffff:ffff:ffff:ffff:ffff:ffff:255.255.255.255"]; 136 char *tp, *ep; 137 struct { int base, len; } best, cur; 138 u_int words[IN6ADDRSZ / INT16SZ]; 139 int i; 140 int advance; 141 142 /* 143 * Preprocess: 144 * Copy the input (bytewise) array into a wordwise array. 145 * Find the longest run of 0x00's in src[] for :: shorthanding. 146 */ 147 memset(words, '\0', sizeof words); 148 for (i = 0; i < IN6ADDRSZ; i++) 149 words[i / 2] |= (src[i] << ((1 - (i % 2)) << 3)); 150 best.base = -1; 151 cur.base = -1; 152 for (i = 0; i < (IN6ADDRSZ / INT16SZ); i++) { 153 if (words[i] == 0) { 154 if (cur.base == -1) 155 cur.base = i, cur.len = 1; 156 else 157 cur.len++; 158 } else { 159 if (cur.base != -1) { 160 if (best.base == -1 || cur.len > best.len) 161 best = cur; 162 cur.base = -1; 163 } 164 } 165 } 166 if (cur.base != -1) { 167 if (best.base == -1 || cur.len > best.len) 168 best = cur; 169 } 170 if (best.base != -1 && best.len < 2) 171 best.base = -1; 172 173 /* 174 * Format the result. 175 */ 176 tp = tmp; 177 ep = tmp + sizeof(tmp); 178 for (i = 0; i < (IN6ADDRSZ / INT16SZ) && tp < ep; i++) { 179 /* Are we inside the best run of 0x00's? */ 180 if (best.base != -1 && i >= best.base && 181 i < (best.base + best.len)) { 182 if (i == best.base) { 183 if (tp + 1 >= ep) 184 return (NULL); 185 *tp++ = ':'; 186 } 187 continue; 188 } 189 /* Are we following an initial run of 0x00s or any real hex? */ 190 if (i != 0) { 191 if (tp + 1 >= ep) 192 return (NULL); 193 *tp++ = ':'; 194 } 195 /* Is this address an encapsulated IPv4? */ 196 if (i == 6 && best.base == 0 && 197 (best.len == 6 || (best.len == 5 && words[5] == 0xffff))) { 198 if (!inet_ntop4(src+12, tp, (size_t)(ep - tp))) 199 return (NULL); 200 tp += strlen(tp); 201 break; 202 } 203 advance = snprintf(tp, ep - tp, "%x", words[i]); 204 if (advance <= 0 || advance >= ep - tp) 205 return (NULL); 206 tp += advance; 207 } 208 /* Was it a trailing run of 0x00's? */ 209 if (best.base != -1 && (best.base + best.len) == (IN6ADDRSZ / INT16SZ)) { 210 if (tp + 1 >= ep) 211 return (NULL); 212 *tp++ = ':'; 213 } 214 if (tp + 1 >= ep) 215 return (NULL); 216 *tp++ = '\0'; 217 218 /* 219 * Check for overflow, copy, and we're done. 220 */ 221 if ((size_t)(tp - tmp) > size) { 222 errno = ENOSPC; 223 return (NULL); 224 } 225 strlcpy(dst, tmp, size); 226 return (dst); 227} 228 229#endif /* !HAVE_INET_NTOP */ 230