inet_cidr_ntop.c revision 1.1
1 /* $NetBSD: inet_cidr_ntop.c,v 1.1 2004/05/20 22:29:02 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 #if defined(LIBC_SCCS) && !defined(lint) 21 static const char rcsid[] = "Id: inet_cidr_ntop.c,v 1.1.2.1.8.2 2004/03/17 00:29:46 marka Exp"; 22 #endif 23 24 #include "port_before.h" 25 26 #include <sys/types.h> 27 #include <sys/socket.h> 28 #include <netinet/in.h> 29 #include <arpa/nameser.h> 30 #include <arpa/inet.h> 31 32 #include <errno.h> 33 #include <stdio.h> 34 #include <string.h> 35 #include <stdlib.h> 36 37 #include "port_after.h" 38 39 #ifdef SPRINTF_CHAR 40 # define SPRINTF(x) strlen(sprintf/**/x) 41 #else 42 # define SPRINTF(x) ((size_t)sprintf x) 43 #endif 44 45 static char * inet_cidr_ntop_ipv4 __P((const u_char *src, int bits, 46 char *dst, size_t size)); 47 static char * inet_cidr_ntop_ipv6 __P((const u_char *src, int bits, 48 char *dst, size_t size)); 49 50 /* 51 * char * 52 * inet_cidr_ntop(af, src, bits, dst, size) 53 * convert network address from network to presentation format. 54 * "src"'s size is determined from its "af". 55 * return: 56 * pointer to dst, or NULL if an error occurred (check errno). 57 * note: 58 * 192.5.5.1/28 has a nonzero host part, which means it isn't a network 59 * as called for by inet_net_ntop() but it can be a host address with 60 * an included netmask. 61 * author: 62 * Paul Vixie (ISC), October 1998 63 */ 64 char * 65 inet_cidr_ntop(int af, const void *src, int bits, char *dst, size_t size) { 66 switch (af) { 67 case AF_INET: 68 return (inet_cidr_ntop_ipv4(src, bits, dst, size)); 69 case AF_INET6: 70 return (inet_cidr_ntop_ipv6(src, bits, dst, size)); 71 default: 72 errno = EAFNOSUPPORT; 73 return (NULL); 74 } 75 } 76 77 static int 78 decoct(const u_char *src, int bytes, char *dst, size_t size) { 79 char *odst = dst; 80 char *t; 81 int b; 82 83 for (b = 1; b <= bytes; b++) { 84 if (size < sizeof "255.") 85 return (0); 86 t = dst; 87 dst += SPRINTF((dst, "%u", *src++)); 88 if (b != bytes) { 89 *dst++ = '.'; 90 *dst = '\0'; 91 } 92 size -= (size_t)(dst - t); 93 } 94 return (dst - odst); 95 } 96 97 /* 98 * static char * 99 * inet_cidr_ntop_ipv4(src, bits, dst, size) 100 * convert IPv4 network address from network to presentation format. 101 * "src"'s size is determined from its "af". 102 * return: 103 * pointer to dst, or NULL if an error occurred (check errno). 104 * note: 105 * network byte order assumed. this means 192.5.5.240/28 has 106 * 0b11110000 in its fourth octet. 107 * author: 108 * Paul Vixie (ISC), October 1998 109 */ 110 static char * 111 inet_cidr_ntop_ipv4(const u_char *src, int bits, char *dst, size_t size) { 112 char *odst = dst; 113 size_t len = 4; 114 size_t b; 115 size_t bytes; 116 117 if ((bits < -1) || (bits > 32)) { 118 errno = EINVAL; 119 return (NULL); 120 } 121 122 /* Find number of significant bytes in address. */ 123 if (bits == -1) 124 len = 4; 125 else 126 for (len = 1, b = 1 ; b < 4U; b++) 127 if (*(src + b)) 128 len = b + 1; 129 130 /* Format whole octets plus nonzero trailing octets. */ 131 bytes = (((bits <= 0) ? 1 : bits) + 7) / 8; 132 if (len > bytes) 133 bytes = len; 134 b = decoct(src, bytes, dst, size); 135 if (b == 0U) 136 goto emsgsize; 137 dst += b; 138 size -= b; 139 140 if (bits != -1) { 141 /* Format CIDR /width. */ 142 if (size < sizeof "/32") 143 goto emsgsize; 144 dst += SPRINTF((dst, "/%u", bits)); 145 } 146 147 return (odst); 148 149 emsgsize: 150 errno = EMSGSIZE; 151 return (NULL); 152 } 153 154 static char * 155 inet_cidr_ntop_ipv6(const u_char *src, int bits, char *dst, size_t size) { 156 /* 157 * Note that int32_t and int16_t need only be "at least" large enough 158 * to contain a value of the specified size. On some systems, like 159 * Crays, there is no such thing as an integer variable with 16 bits. 160 * Keep this in mind if you think this function should have been coded 161 * to use pointer overlays. All the world's not a VAX. 162 */ 163 char tmp[sizeof "ffff:ffff:ffff:ffff:ffff:ffff:255.255.255.255/128"]; 164 char *tp; 165 struct { int base, len; } best, cur; 166 u_int words[NS_IN6ADDRSZ / NS_INT16SZ]; 167 int i; 168 169 if ((bits < -1) || (bits > 128)) { 170 errno = EINVAL; 171 return (NULL); 172 } 173 174 /* 175 * Preprocess: 176 * Copy the input (bytewise) array into a wordwise array. 177 * Find the longest run of 0x00's in src[] for :: shorthanding. 178 */ 179 memset(words, '\0', sizeof words); 180 for (i = 0; i < NS_IN6ADDRSZ; i++) 181 words[i / 2] |= (src[i] << ((1 - (i % 2)) << 3)); 182 best.base = -1; 183 cur.base = -1; 184 for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) { 185 if (words[i] == 0) { 186 if (cur.base == -1) 187 cur.base = i, cur.len = 1; 188 else 189 cur.len++; 190 } else { 191 if (cur.base != -1) { 192 if (best.base == -1 || cur.len > best.len) 193 best = cur; 194 cur.base = -1; 195 } 196 } 197 } 198 if (cur.base != -1) { 199 if (best.base == -1 || cur.len > best.len) 200 best = cur; 201 } 202 if (best.base != -1 && best.len < 2) 203 best.base = -1; 204 205 /* 206 * Format the result. 207 */ 208 tp = tmp; 209 for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) { 210 /* Are we inside the best run of 0x00's? */ 211 if (best.base != -1 && i >= best.base && 212 i < (best.base + best.len)) { 213 if (i == best.base) 214 *tp++ = ':'; 215 continue; 216 } 217 /* Are we following an initial run of 0x00s or any real hex? */ 218 if (i != 0) 219 *tp++ = ':'; 220 /* Is this address an encapsulated IPv4? */ 221 if (i == 6 && best.base == 0 && (best.len == 6 || 222 (best.len == 7 && words[7] != 0x0001) || 223 (best.len == 5 && words[5] == 0xffff))) { 224 int n; 225 226 if (src[15] || bits == -1 || bits > 120) 227 n = 4; 228 else if (src[14] || bits > 112) 229 n = 3; 230 else 231 n = 2; 232 n = decoct(src+12, n, tp, sizeof tmp - (tp - tmp)); 233 if (n == 0) { 234 errno = EMSGSIZE; 235 return (NULL); 236 } 237 tp += strlen(tp); 238 break; 239 } 240 tp += SPRINTF((tp, "%x", words[i])); 241 } 242 243 /* Was it a trailing run of 0x00's? */ 244 if (best.base != -1 && (best.base + best.len) == 245 (NS_IN6ADDRSZ / NS_INT16SZ)) 246 *tp++ = ':'; 247 *tp = '\0'; 248 249 if (bits != -1) 250 tp += SPRINTF((tp, "/%u", bits)); 251 252 /* 253 * Check for overflow, copy, and we're done. 254 */ 255 if ((size_t)(tp - tmp) > size) { 256 errno = EMSGSIZE; 257 return (NULL); 258 } 259 strcpy(dst, tmp); 260 return (dst); 261 } 262
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