1 /* $NetBSD: inet_cidr_ntop.c,v 1.9 2026/04/08 14:12:06 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 1.9 2026/04/08 14:12:06 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 static char * 51 inet_cidr_ntop_ipv4(const u_char *src, int bits, char *dst, size_t size); 52 static char * 53 inet_cidr_ntop_ipv6(const u_char *src, int bits, char *dst, size_t size); 54 55 /*% 56 * char * 57 * inet_cidr_ntop(af, src, bits, dst, size) 58 * convert network address from network to presentation format. 59 * "src"'s size is determined from its "af". 60 * return: 61 * pointer to dst, or NULL if an error occurred (check errno). 62 * note: 63 * 192.5.5.1/28 has a nonzero host part, which means it isn't a network 64 * as called for by inet_net_ntop() but it can be a host address with 65 * an included netmask. 66 * author: 67 * Paul Vixie (ISC), October 1998 68 */ 69 char * 70 inet_cidr_ntop(int af, const void *src, int bits, char *dst, size_t size) { 71 switch (af) { 72 case AF_INET: 73 return (inet_cidr_ntop_ipv4(src, bits, dst, size)); 74 case AF_INET6: 75 return (inet_cidr_ntop_ipv6(src, bits, dst, size)); 76 default: 77 errno = EAFNOSUPPORT; 78 return (NULL); 79 } 80 } 81 82 static int 83 decoct(const u_char *src, size_t bytes, char *dst, size_t size) { 84 size_t b; 85 int l, t = 0; 86 87 for (b = 1; b <= bytes; b++) { 88 ADDS(snprintf(dst + t, size - t, "%u", *src++)); 89 if (b != bytes) 90 ADDC('.'); 91 } 92 return t; 93 emsgsize: 94 return l < 0 ? l : l + t; 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 size_t len = 4, b, bytes, t = 0; 113 int l; 114 115 if ((bits < -1) || (bits > 32)) { 116 errno = EINVAL; 117 return (NULL); 118 } 119 120 /* Find number of significant bytes in address. */ 121 if (bits == -1) 122 len = 4; 123 else 124 for (len = 1, b = 1 ; b < 4U; b++) 125 if (*(src + b)) 126 len = b + 1; 127 128 /* Format whole octets plus nonzero trailing octets. */ 129 bytes = (((bits <= 0) ? 1 : bits) + 7) / 8; 130 if (len > bytes) 131 bytes = len; 132 ADDS(decoct(src, bytes, dst + t, size - t)); 133 134 if (bits != -1) { 135 /* Format CIDR /width. */ 136 ADDS(snprintf(dst + t, size - t, "/%u", bits)); 137 } 138 139 return (dst); 140 141 emsgsize: 142 errno = EMSGSIZE; 143 return (NULL); 144 } 145 146 static char * 147 inet_cidr_ntop_ipv6(const u_char *src, int bits, char *dst, size_t size) { 148 /* 149 * Note that int32_t and int16_t need only be "at least" large enough 150 * to contain a value of the specified size. On some systems, like 151 * Crays, there is no such thing as an integer variable with 16 bits. 152 * Keep this in mind if you think this function should have been coded 153 * to use pointer overlays. All the world's not a VAX. 154 */ 155 struct { int base, len; } best, cur; 156 u_int words[NS_IN6ADDRSZ / NS_INT16SZ]; 157 int i, l; 158 size_t t; 159 160 if ((bits < -1) || (bits > 128)) { 161 errno = EINVAL; 162 return (NULL); 163 } 164 165 /* 166 * Preprocess: 167 * Copy the input (bytewise) array into a wordwise array. 168 * Find the longest run of 0x00's in src[] for :: shorthanding. 169 */ 170 memset(words, '\0', sizeof words); 171 for (i = 0; i < NS_IN6ADDRSZ; i++) 172 words[i / 2] |= (src[i] << ((1 - (i % 2)) << 3)); 173 best.base = -1; 174 best.len = 0; 175 cur.base = -1; 176 cur.len = 0; 177 for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) { 178 if (words[i] == 0) { 179 if (cur.base == -1) 180 cur.base = i, cur.len = 1; 181 else 182 cur.len++; 183 } else { 184 if (cur.base != -1) { 185 if (best.base == -1 || cur.len > best.len) 186 best = cur; 187 cur.base = -1; 188 } 189 } 190 } 191 if (cur.base != -1) { 192 if (best.base == -1 || cur.len > best.len) 193 best = cur; 194 } 195 if (best.base != -1 && best.len < 2) 196 best.base = -1; 197 198 /* 199 * Format the result. 200 */ 201 t = 0; 202 for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) { 203 /* Are we inside the best run of 0x00's? */ 204 if (best.base != -1 && i >= best.base && 205 i < (best.base + best.len)) { 206 if (i == best.base) 207 ADDC(':'); 208 continue; 209 } 210 /* Are we following an initial run of 0x00s or any real hex? */ 211 if (i != 0) 212 ADDC(':'); 213 /* Is this address an encapsulated IPv4? */ 214 if (i == 6 && best.base == 0 && (best.len == 6 || 215 (best.len == 7 && words[7] != 0x0001) || 216 (best.len == 5 && words[5] == 0xffff))) { 217 size_t n; 218 219 if (src[15] || bits == -1 || bits > 120) 220 n = 4; 221 else if (src[14] || bits > 112) 222 n = 3; 223 else 224 n = 2; 225 ADDS(decoct(src+12, n, dst + t, size - t)); 226 break; 227 } 228 ADDS(snprintf(dst + t, size - t, "%x", words[i])); 229 } 230 231 /* Was it a trailing run of 0x00's? */ 232 if (best.base != -1 && (best.base + best.len) == 233 (NS_IN6ADDRSZ / NS_INT16SZ)) { 234 ADDC(':'); 235 } 236 237 if (bits != -1) 238 ADDS(snprintf(dst + t, size - t, "/%u", bits)); 239 240 return dst; 241 emsgsize: 242 errno = EMSGSIZE; 243 return (NULL); 244 } 245 246 /*! \file */ 247
Indexes created Sun Oct 25 00:26:45 UTC 2026