inet_cidr_ntop.c revision 1.6
1 /* $NetBSD: inet_cidr_ntop.c,v 1.6 2008/06/21 20:41:48 christos Exp $ */ 2 3 /* 4 * Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC") 5 * Copyright (c) 1998,1999 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_cidr_ntop.c,v 1.7 2006/10/11 02:18:18 marka Exp"; 24 #else 25 __RCSID("$NetBSD: inet_cidr_ntop.c,v 1.6 2008/06/21 20:41:48 christos Exp $"); 26 #endif 27 #endif 28 29 #include "port_before.h" 30 31 #include "namespace.h" 32 #include <sys/types.h> 33 #include <sys/socket.h> 34 #include <netinet/in.h> 35 #include <arpa/nameser.h> 36 #include <arpa/inet.h> 37 38 #include <errno.h> 39 #include <stdio.h> 40 #include <string.h> 41 #include <stdlib.h> 42 43 #include "port_after.h" 44 45 #ifdef __weak_alias 46 __weak_alias(inet_cidr_ntop,_inet_cidr_ntop) 47 #endif 48 49 #ifdef SPRINTF_CHAR 50 # define SPRINTF(x) strlen(sprintf/**/x) 51 #else 52 # define SPRINTF(x) ((size_t)sprintf x) 53 #endif 54 55 static char * 56 inet_cidr_ntop_ipv4(const u_char *src, int bits, char *dst, size_t size); 57 static char * 58 inet_cidr_ntop_ipv6(const u_char *src, int bits, char *dst, size_t size); 59 60 /*% 61 * char * 62 * inet_cidr_ntop(af, src, bits, dst, size) 63 * convert network address from network to presentation format. 64 * "src"'s size is determined from its "af". 65 * return: 66 * pointer to dst, or NULL if an error occurred (check errno). 67 * note: 68 * 192.5.5.1/28 has a nonzero host part, which means it isn't a network 69 * as called for by inet_net_ntop() but it can be a host address with 70 * an included netmask. 71 * author: 72 * Paul Vixie (ISC), October 1998 73 */ 74 char * 75 inet_cidr_ntop(int af, const void *src, int bits, char *dst, size_t size) { 76 switch (af) { 77 case AF_INET: 78 return (inet_cidr_ntop_ipv4(src, bits, dst, size)); 79 case AF_INET6: 80 return (inet_cidr_ntop_ipv6(src, bits, dst, size)); 81 default: 82 errno = EAFNOSUPPORT; 83 return (NULL); 84 } 85 } 86 87 static int 88 decoct(const u_char *src, size_t bytes, char *dst, size_t size) { 89 char *odst = dst; 90 char *t; 91 size_t b; 92 93 for (b = 1; b <= bytes; b++) { 94 if (size < sizeof "255.") 95 return (0); 96 t = dst; 97 dst += SPRINTF((dst, "%u", *src++)); 98 if (b != bytes) { 99 *dst++ = '.'; 100 *dst = '\0'; 101 } 102 size -= (size_t)(dst - t); 103 } 104 return (dst - odst); 105 } 106 107 /*% 108 * static char * 109 * inet_cidr_ntop_ipv4(src, bits, dst, size) 110 * convert IPv4 network address from network to presentation format. 111 * "src"'s size is determined from its "af". 112 * return: 113 * pointer to dst, or NULL if an error occurred (check errno). 114 * note: 115 * network byte order assumed. this means 192.5.5.240/28 has 116 * 0b11110000 in its fourth octet. 117 * author: 118 * Paul Vixie (ISC), October 1998 119 */ 120 static char * 121 inet_cidr_ntop_ipv4(const u_char *src, int bits, char *dst, size_t size) { 122 char *odst = dst; 123 size_t len = 4; 124 size_t b; 125 size_t bytes; 126 127 if ((bits < -1) || (bits > 32)) { 128 errno = EINVAL; 129 return (NULL); 130 } 131 132 /* Find number of significant bytes in address. */ 133 if (bits == -1) 134 len = 4; 135 else 136 for (len = 1, b = 1 ; b < 4U; b++) 137 if (*(src + b)) 138 len = b + 1; 139 140 /* Format whole octets plus nonzero trailing octets. */ 141 bytes = (((bits <= 0) ? 1 : bits) + 7) / 8; 142 if (len > bytes) 143 bytes = len; 144 b = decoct(src, bytes, dst, size); 145 if (b == 0U) 146 goto emsgsize; 147 dst += b; 148 size -= b; 149 150 if (bits != -1) { 151 /* Format CIDR /width. */ 152 if (size < sizeof "/32") 153 goto emsgsize; 154 dst += SPRINTF((dst, "/%u", bits)); 155 } 156 157 return (odst); 158 159 emsgsize: 160 errno = EMSGSIZE; 161 return (NULL); 162 } 163 164 static char * 165 inet_cidr_ntop_ipv6(const u_char *src, int bits, char *dst, size_t size) { 166 /* 167 * Note that int32_t and int16_t need only be "at least" large enough 168 * to contain a value of the specified size. On some systems, like 169 * Crays, there is no such thing as an integer variable with 16 bits. 170 * Keep this in mind if you think this function should have been coded 171 * to use pointer overlays. All the world's not a VAX. 172 */ 173 char tmp[sizeof "ffff:ffff:ffff:ffff:ffff:ffff:255.255.255.255/128"]; 174 char *tp; 175 struct { int base, len; } best, cur; 176 u_int words[NS_IN6ADDRSZ / NS_INT16SZ]; 177 int i; 178 179 if ((bits < -1) || (bits > 128)) { 180 errno = EINVAL; 181 return (NULL); 182 } 183 184 /* 185 * Preprocess: 186 * Copy the input (bytewise) array into a wordwise array. 187 * Find the longest run of 0x00's in src[] for :: shorthanding. 188 */ 189 memset(words, '\0', sizeof words); 190 for (i = 0; i < NS_IN6ADDRSZ; i++) 191 words[i / 2] |= (src[i] << ((1 - (i % 2)) << 3)); 192 best.base = -1; 193 best.len = 0; 194 cur.base = -1; 195 cur.len = 0; 196 for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) { 197 if (words[i] == 0) { 198 if (cur.base == -1) 199 cur.base = i, cur.len = 1; 200 else 201 cur.len++; 202 } else { 203 if (cur.base != -1) { 204 if (best.base == -1 || cur.len > best.len) 205 best = cur; 206 cur.base = -1; 207 } 208 } 209 } 210 if (cur.base != -1) { 211 if (best.base == -1 || cur.len > best.len) 212 best = cur; 213 } 214 if (best.base != -1 && best.len < 2) 215 best.base = -1; 216 217 /* 218 * Format the result. 219 */ 220 tp = tmp; 221 for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) { 222 /* Are we inside the best run of 0x00's? */ 223 if (best.base != -1 && i >= best.base && 224 i < (best.base + best.len)) { 225 if (i == best.base) 226 *tp++ = ':'; 227 continue; 228 } 229 /* Are we following an initial run of 0x00s or any real hex? */ 230 if (i != 0) 231 *tp++ = ':'; 232 /* Is this address an encapsulated IPv4? */ 233 if (i == 6 && best.base == 0 && (best.len == 6 || 234 (best.len == 7 && words[7] != 0x0001) || 235 (best.len == 5 && words[5] == 0xffff))) { 236 size_t n; 237 238 if (src[15] || bits == -1 || bits > 120) 239 n = 4; 240 else if (src[14] || bits > 112) 241 n = 3; 242 else 243 n = 2; 244 n = decoct(src+12, n, tp, sizeof tmp - (tp - tmp)); 245 if (n == 0) { 246 errno = EMSGSIZE; 247 return (NULL); 248 } 249 tp += strlen(tp); 250 break; 251 } 252 tp += SPRINTF((tp, "%x", words[i])); 253 } 254 255 /* Was it a trailing run of 0x00's? */ 256 if (best.base != -1 && (best.base + best.len) == 257 (NS_IN6ADDRSZ / NS_INT16SZ)) 258 *tp++ = ':'; 259 *tp = '\0'; 260 261 if (bits != -1) 262 tp += SPRINTF((tp, "/%u", bits)); 263 264 /* 265 * Check for overflow, copy, and we're done. 266 */ 267 if ((size_t)(tp - tmp) > size) { 268 errno = EMSGSIZE; 269 return (NULL); 270 } 271 strcpy(dst, tmp); 272 return (dst); 273 } 274 275 /*! \file */ 276
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