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 #if defined(LIBC_SCCS) && !defined(lint) 21 static const char rcsid[] = "$Id: inet_ntop.c,v 1.5 2005/11/03 22:59:52 marka Exp $"; 22 #endif /* LIBC_SCCS and not lint */ 23 #include "port_before.h" 24 25 #include <sys/param.h> 26 #include <sys/socket.h> 27 28 #include <netinet/in.h> 29 #include <arpa/inet.h> 30 #include <arpa/nameser.h> 31 32 #include <errno.h> 33 #include <stdio.h> 34 #include <string.h> 35 36 #include "port_after.h" 37 38 /*% 39 * WARNING: Don't even consider trying to compile this on a system where 40 * sizeof(int) < 4. sizeof(int) > 4 is fine; all the world's not a VAX. 41 */ 42 43 static const char *inet_ntop4(const u_char *src, char *dst, socklen_t size); 44 static const char *inet_ntop6(const u_char *src, char *dst, socklen_t size); 45 46 /* const char * 47 * inet_ntop(af, src, dst, size) 48 * convert a network format address to presentation format. 49 * return: 50 * pointer to presentation format address (`dst'), or NULL (see errno). 51 * author: 52 * Paul Vixie, 1996. 53 */ 54 const char * 55 inet_ntop(int af, const void * __restrict src, char * __restrict dst, 56 socklen_t size) 57 { 58 switch (af) { 59 case AF_INET: 60 return (inet_ntop4(src, dst, size)); 61 case AF_INET6: 62 return (inet_ntop6(src, dst, size)); 63 default: 64 errno = EAFNOSUPPORT; 65 return (NULL); 66 } 67 /* NOTREACHED */ 68 } 69 70 /* const char * 71 * inet_ntop4(src, dst, size) 72 * format an IPv4 address 73 * return: 74 * `dst' (as a const) 75 * notes: 76 * (1) uses no statics 77 * (2) takes a u_char* not an in_addr as input 78 * author: 79 * Paul Vixie, 1996. 80 */ 81 static const char * 82 inet_ntop4(const u_char *src, char *dst, socklen_t size) 83 { 84 static const char fmt[] = "%u.%u.%u.%u"; 85 char tmp[sizeof "255.255.255.255"]; 86 int l; 87 88 l = snprintf(tmp, sizeof(tmp), fmt, src[0], src[1], src[2], src[3]); 89 if (l <= 0 || (socklen_t) l >= size) { 90 errno = ENOSPC; 91 return (NULL); 92 } 93 strlcpy(dst, tmp, size); 94 return (dst); 95 } 96 97 /* const char * 98 * inet_ntop6(src, dst, size) 99 * convert IPv6 binary address into presentation (printable) format 100 * author: 101 * Paul Vixie, 1996. 102 */ 103 static const char * 104 inet_ntop6(const u_char *src, char *dst, socklen_t size) 105 { 106 /* 107 * Note that int32_t and int16_t need only be "at least" large enough 108 * to contain a value of the specified size. On some systems, like 109 * Crays, there is no such thing as an integer variable with 16 bits. 110 * Keep this in mind if you think this function should have been coded 111 * to use pointer overlays. All the world's not a VAX. 112 */ 113 char tmp[sizeof "ffff:ffff:ffff:ffff:ffff:ffff:255.255.255.255"], *tp; 114 struct { int base, len; } best, cur; 115 u_int words[NS_IN6ADDRSZ / NS_INT16SZ]; 116 int i; 117 118 /* 119 * Preprocess: 120 * Copy the input (bytewise) array into a wordwise array. 121 * Find the longest run of 0x00's in src[] for :: shorthanding. 122 */ 123 memset(words, '\0', sizeof words); 124 for (i = 0; i < NS_IN6ADDRSZ; i++) 125 words[i / 2] |= (src[i] << ((1 - (i % 2)) << 3)); 126 best.base = -1; 127 best.len = 0; 128 cur.base = -1; 129 cur.len = 0; 130 for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) { 131 if (words[i] == 0) { 132 if (cur.base == -1) 133 cur.base = i, cur.len = 1; 134 else 135 cur.len++; 136 } else { 137 if (cur.base != -1) { 138 if (best.base == -1 || cur.len > best.len) 139 best = cur; 140 cur.base = -1; 141 } 142 } 143 } 144 if (cur.base != -1) { 145 if (best.base == -1 || cur.len > best.len) 146 best = cur; 147 } 148 if (best.base != -1 && best.len < 2) 149 best.base = -1; 150 151 /* 152 * Format the result. 153 */ 154 tp = tmp; 155 for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) { 156 /* Are we inside the best run of 0x00's? */ 157 if (best.base != -1 && i >= best.base && 158 i < (best.base + best.len)) { 159 if (i == best.base) 160 *tp++ = ':'; 161 continue; 162 } 163 /* Are we following an initial run of 0x00s or any real hex? */ 164 if (i != 0) 165 *tp++ = ':'; 166 /* Is this address an encapsulated IPv4? */ 167 if (i == 6 && best.base == 0 && (best.len == 6 || 168 (best.len == 7 && words[7] != 0x0001) || 169 (best.len == 5 && words[5] == 0xffff))) { 170 if (!inet_ntop4(src+12, tp, sizeof tmp - (tp - tmp))) { 171 errno = ENOSPC; 172 return (NULL); 173 } 174 tp += strlen(tp); 175 break; 176 } 177 tp += sprintf(tp, "%x", words[i]); 178 } 179 /* Was it a trailing run of 0x00's? */ 180 if (best.base != -1 && (best.base + best.len) == 181 (NS_IN6ADDRSZ / NS_INT16SZ)) 182 *tp++ = ':'; 183 *tp++ = '\0'; 184 185 /* 186 * Check for overflow, copy, and we're done. 187 */ 188 if ((socklen_t)(tp - tmp) > size) { 189 errno = ENOSPC; 190 return (NULL); 191 } 192 strcpy(dst, tmp); 193 return (dst); 194 } 195 196 /* 197 * Weak aliases for applications that use certain private entry points, 198 * and fail to include <arpa/inet.h>. 199 */ 200 #undef inet_ntop 201 __weak_reference(__inet_ntop, inet_ntop); 202 203 /*! \file */ 204