inet_cidr_ntop.c revision 1.8
1 /* $NetBSD: inet_cidr_ntop.c,v 1.8 2012/03/13 21:13:38 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 1.8 2012/03/13 21:13:38 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 <assert.h> 39 #include <errno.h> 40 #include <stdio.h> 41 #include <string.h> 42 #include <stdlib.h> 43 44 #include "port_after.h" 45 46 #ifdef __weak_alias 47 __weak_alias(inet_cidr_ntop,_inet_cidr_ntop) 48 #endif 49 50 #ifdef SPRINTF_CHAR 51 # define SPRINTF(x) strlen(sprintf/**/x) 52 #else 53 # define SPRINTF(x) ((size_t)sprintf x) 54 #endif 55 56 static char * 57 inet_cidr_ntop_ipv4(const u_char *src, int bits, char *dst, size_t size); 58 static char * 59 inet_cidr_ntop_ipv6(const u_char *src, int bits, char *dst, size_t size); 60 61 /*% 62 * char * 63 * inet_cidr_ntop(af, src, bits, dst, size) 64 * convert network address from network to presentation format. 65 * "src"'s size is determined from its "af". 66 * return: 67 * pointer to dst, or NULL if an error occurred (check errno). 68 * note: 69 * 192.5.5.1/28 has a nonzero host part, which means it isn't a network 70 * as called for by inet_net_ntop() but it can be a host address with 71 * an included netmask. 72 * author: 73 * Paul Vixie (ISC), October 1998 74 */ 75 char * 76 inet_cidr_ntop(int af, const void *src, int bits, char *dst, size_t size) { 77 switch (af) { 78 case AF_INET: 79 return (inet_cidr_ntop_ipv4(src, bits, dst, size)); 80 case AF_INET6: 81 return (inet_cidr_ntop_ipv6(src, bits, dst, size)); 82 default: 83 errno = EAFNOSUPPORT; 84 return (NULL); 85 } 86 } 87 88 static int 89 decoct(const u_char *src, size_t bytes, char *dst, size_t size) { 90 char *odst = dst; 91 char *t; 92 size_t b; 93 94 for (b = 1; b <= bytes; b++) { 95 if (size < sizeof "255.") 96 return (0); 97 t = dst; 98 dst += SPRINTF((dst, "%u", *src++)); 99 if (b != bytes) { 100 *dst++ = '.'; 101 *dst = '\0'; 102 } 103 size -= (size_t)(dst - t); 104 } 105 _DIAGASSERT(__type_fit(int, dst - odst)); 106 return (int)(dst - odst); 107 } 108 109 /*% 110 * static char * 111 * inet_cidr_ntop_ipv4(src, bits, dst, size) 112 * convert IPv4 network address from network to presentation format. 113 * "src"'s size is determined from its "af". 114 * return: 115 * pointer to dst, or NULL if an error occurred (check errno). 116 * note: 117 * network byte order assumed. this means 192.5.5.240/28 has 118 * 0b11110000 in its fourth octet. 119 * author: 120 * Paul Vixie (ISC), October 1998 121 */ 122 static char * 123 inet_cidr_ntop_ipv4(const u_char *src, int bits, char *dst, size_t size) { 124 char *odst = dst; 125 size_t len = 4; 126 size_t b; 127 size_t bytes; 128 129 if ((bits < -1) || (bits > 32)) { 130 errno = EINVAL; 131 return (NULL); 132 } 133 134 /* Find number of significant bytes in address. */ 135 if (bits == -1) 136 len = 4; 137 else 138 for (len = 1, b = 1 ; b < 4U; b++) 139 if (*(src + b)) 140 len = b + 1; 141 142 /* Format whole octets plus nonzero trailing octets. */ 143 bytes = (((bits <= 0) ? 1 : bits) + 7) / 8; 144 if (len > bytes) 145 bytes = len; 146 b = decoct(src, bytes, dst, size); 147 if (b == 0U) 148 goto emsgsize; 149 dst += b; 150 size -= b; 151 152 if (bits != -1) { 153 /* Format CIDR /width. */ 154 if (size < sizeof "/32") 155 goto emsgsize; 156 dst += SPRINTF((dst, "/%u", bits)); 157 } 158 159 return (odst); 160 161 emsgsize: 162 errno = EMSGSIZE; 163 return (NULL); 164 } 165 166 static char * 167 inet_cidr_ntop_ipv6(const u_char *src, int bits, char *dst, size_t size) { 168 /* 169 * Note that int32_t and int16_t need only be "at least" large enough 170 * to contain a value of the specified size. On some systems, like 171 * Crays, there is no such thing as an integer variable with 16 bits. 172 * Keep this in mind if you think this function should have been coded 173 * to use pointer overlays. All the world's not a VAX. 174 */ 175 char tmp[sizeof "ffff:ffff:ffff:ffff:ffff:ffff:255.255.255.255/128"]; 176 char *tp; 177 struct { int base, len; } best, cur; 178 u_int words[NS_IN6ADDRSZ / NS_INT16SZ]; 179 int i; 180 181 if ((bits < -1) || (bits > 128)) { 182 errno = EINVAL; 183 return (NULL); 184 } 185 186 /* 187 * Preprocess: 188 * Copy the input (bytewise) array into a wordwise array. 189 * Find the longest run of 0x00's in src[] for :: shorthanding. 190 */ 191 memset(words, '\0', sizeof words); 192 for (i = 0; i < NS_IN6ADDRSZ; i++) 193 words[i / 2] |= (src[i] << ((1 - (i % 2)) << 3)); 194 best.base = -1; 195 best.len = 0; 196 cur.base = -1; 197 cur.len = 0; 198 for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) { 199 if (words[i] == 0) { 200 if (cur.base == -1) 201 cur.base = i, cur.len = 1; 202 else 203 cur.len++; 204 } else { 205 if (cur.base != -1) { 206 if (best.base == -1 || cur.len > best.len) 207 best = cur; 208 cur.base = -1; 209 } 210 } 211 } 212 if (cur.base != -1) { 213 if (best.base == -1 || cur.len > best.len) 214 best = cur; 215 } 216 if (best.base != -1 && best.len < 2) 217 best.base = -1; 218 219 /* 220 * Format the result. 221 */ 222 tp = tmp; 223 for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) { 224 /* Are we inside the best run of 0x00's? */ 225 if (best.base != -1 && i >= best.base && 226 i < (best.base + best.len)) { 227 if (i == best.base) 228 *tp++ = ':'; 229 continue; 230 } 231 /* Are we following an initial run of 0x00s or any real hex? */ 232 if (i != 0) 233 *tp++ = ':'; 234 /* Is this address an encapsulated IPv4? */ 235 if (i == 6 && best.base == 0 && (best.len == 6 || 236 (best.len == 7 && words[7] != 0x0001) || 237 (best.len == 5 && words[5] == 0xffff))) { 238 size_t n; 239 240 if (src[15] || bits == -1 || bits > 120) 241 n = 4; 242 else if (src[14] || bits > 112) 243 n = 3; 244 else 245 n = 2; 246 n = decoct(src+12, n, tp, sizeof tmp - (tp - tmp)); 247 if (n == 0) { 248 errno = EMSGSIZE; 249 return (NULL); 250 } 251 tp += strlen(tp); 252 break; 253 } 254 tp += SPRINTF((tp, "%x", words[i])); 255 } 256 257 /* Was it a trailing run of 0x00's? */ 258 if (best.base != -1 && (best.base + best.len) == 259 (NS_IN6ADDRSZ / NS_INT16SZ)) 260 *tp++ = ':'; 261 *tp = '\0'; 262 263 if (bits != -1) 264 tp += SPRINTF((tp, "/%u", bits)); 265 266 /* 267 * Check for overflow, copy, and we're done. 268 */ 269 if ((size_t)(tp - tmp) > size) { 270 errno = EMSGSIZE; 271 return (NULL); 272 } 273 strcpy(dst, tmp); 274 return (dst); 275 } 276 277 /*! \file */ 278
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