1 /*- 2 * SPDX-License-Identifier: ISC 3 * 4 * Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC") 5 * Copyright (c) 1996-1999 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 "port_before.h" 21 22 #include <sys/param.h> 23 #include <sys/socket.h> 24 25 #include <netinet/in.h> 26 #include <arpa/inet.h> 27 #include <arpa/nameser.h> 28 29 #include <errno.h> 30 #include <stdio.h> 31 #include <string.h> 32 33 #include "port_after.h" 34 35 /*% 36 * WARNING: Don't even consider trying to compile this on a system where 37 * sizeof(int) < 4. sizeof(int) > 4 is fine; all the world's not a VAX. 38 */ 39 40 static const char *inet_ntop4(const u_char *src, char *dst, socklen_t size); 41 static const char *inet_ntop6(const u_char *src, char *dst, socklen_t size); 42 43 /* const char * 44 * inet_ntop(af, src, dst, size) 45 * convert a network format address to presentation format. 46 * return: 47 * pointer to presentation format address (`dst'), or NULL (see errno). 48 * author: 49 * Paul Vixie, 1996. 50 */ 51 const char * 52 inet_ntop(int af, const void * __restrict src, char * __restrict dst, 53 socklen_t size) 54 { 55 switch (af) { 56 case AF_INET: 57 return (inet_ntop4(src, dst, size)); 58 case AF_INET6: 59 return (inet_ntop6(src, dst, size)); 60 default: 61 errno = EAFNOSUPPORT; 62 return (NULL); 63 } 64 /* NOTREACHED */ 65 } 66 67 /* const char * 68 * inet_ntop4(src, dst, size) 69 * format an IPv4 address 70 * return: 71 * `dst' (as a const) 72 * notes: 73 * (1) uses no statics 74 * (2) takes a u_char* not an in_addr as input 75 * author: 76 * Paul Vixie, 1996. 77 */ 78 static const char * 79 inet_ntop4(const u_char *src, char *dst, socklen_t size) 80 { 81 static const char fmt[] = "%u.%u.%u.%u"; 82 char tmp[sizeof "255.255.255.255"]; 83 int l; 84 85 l = snprintf(tmp, sizeof(tmp), fmt, src[0], src[1], src[2], src[3]); 86 if (l <= 0 || (socklen_t) l >= size) { 87 errno = ENOSPC; 88 return (NULL); 89 } 90 strlcpy(dst, tmp, size); 91 return (dst); 92 } 93 94 /* const char * 95 * inet_ntop6(src, dst, size) 96 * convert IPv6 binary address into presentation (printable) format 97 * author: 98 * Paul Vixie, 1996. 99 */ 100 static const char * 101 inet_ntop6(const u_char *src, char *dst, socklen_t size) 102 { 103 /* 104 * Note that int32_t and int16_t need only be "at least" large enough 105 * to contain a value of the specified size. On some systems, like 106 * Crays, there is no such thing as an integer variable with 16 bits. 107 * Keep this in mind if you think this function should have been coded 108 * to use pointer overlays. All the world's not a VAX. 109 */ 110 char tmp[sizeof "ffff:ffff:ffff:ffff:ffff:ffff:255.255.255.255"], *tp; 111 struct { int base, len; } best, cur; 112 u_int words[NS_IN6ADDRSZ / NS_INT16SZ]; 113 int i; 114 115 /* 116 * Preprocess: 117 * Copy the input (bytewise) array into a wordwise array. 118 * Find the longest run of 0x00's in src[] for :: shorthanding. 119 */ 120 memset(words, '\0', sizeof words); 121 for (i = 0; i < NS_IN6ADDRSZ; i++) 122 words[i / 2] |= (src[i] << ((1 - (i % 2)) << 3)); 123 best.base = -1; 124 best.len = 0; 125 cur.base = -1; 126 cur.len = 0; 127 for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) { 128 if (words[i] == 0) { 129 if (cur.base == -1) 130 cur.base = i, cur.len = 1; 131 else 132 cur.len++; 133 } else { 134 if (cur.base != -1) { 135 if (best.base == -1 || cur.len > best.len) 136 best = cur; 137 cur.base = -1; 138 } 139 } 140 } 141 if (cur.base != -1) { 142 if (best.base == -1 || cur.len > best.len) 143 best = cur; 144 } 145 if (best.base != -1 && best.len < 2) 146 best.base = -1; 147 148 /* 149 * Format the result. 150 */ 151 tp = tmp; 152 for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) { 153 /* Are we inside the best run of 0x00's? */ 154 if (best.base != -1 && i >= best.base && 155 i < (best.base + best.len)) { 156 if (i == best.base) 157 *tp++ = ':'; 158 continue; 159 } 160 /* Are we following an initial run of 0x00s or any real hex? */ 161 if (i != 0) 162 *tp++ = ':'; 163 /* Is this address an encapsulated IPv4? */ 164 if (i == 6 && best.base == 0 && (best.len == 6 || 165 (best.len == 7 && words[7] != 0x0001) || 166 (best.len == 5 && words[5] == 0xffff))) { 167 if (!inet_ntop4(src+12, tp, sizeof tmp - (tp - tmp))) { 168 errno = ENOSPC; 169 return (NULL); 170 } 171 tp += strlen(tp); 172 break; 173 } 174 tp += sprintf(tp, "%x", words[i]); 175 } 176 /* Was it a trailing run of 0x00's? */ 177 if (best.base != -1 && (best.base + best.len) == 178 (NS_IN6ADDRSZ / NS_INT16SZ)) 179 *tp++ = ':'; 180 *tp++ = '\0'; 181 182 /* 183 * Check for overflow, copy, and we're done. 184 */ 185 if ((socklen_t)(tp - tmp) > size) { 186 errno = ENOSPC; 187 return (NULL); 188 } 189 strcpy(dst, tmp); 190 return (dst); 191 } 192 193 /* 194 * Weak aliases for applications that use certain private entry points, 195 * and fail to include <arpa/inet.h>. 196 */ 197 #undef inet_ntop 198 __weak_reference(__inet_ntop, inet_ntop); 199 200 /*! \file */ 201