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 <sys/cdefs.h> 24 #include "port_before.h" 25 26 #include <sys/param.h> 27 #include <sys/socket.h> 28 29 #include <netinet/in.h> 30 #include <arpa/inet.h> 31 #include <arpa/nameser.h> 32 33 #include <errno.h> 34 #include <stdio.h> 35 #include <string.h> 36 37 #include "port_after.h" 38 39 /*% 40 * WARNING: Don't even consider trying to compile this on a system where 41 * sizeof(int) < 4. sizeof(int) > 4 is fine; all the world's not a VAX. 42 */ 43 44 static const char *inet_ntop4(const u_char *src, char *dst, socklen_t size); 45 static const char *inet_ntop6(const u_char *src, char *dst, socklen_t size); 46 47 /* const char * 48 * inet_ntop(af, src, dst, size) 49 * convert a network format address to presentation format. 50 * return: 51 * pointer to presentation format address (`dst'), or NULL (see errno). 52 * author: 53 * Paul Vixie, 1996. 54 */ 55 const char * 56 inet_ntop(int af, const void * __restrict src, char * __restrict dst, 57 socklen_t size) 58 { 59 switch (af) { 60 case AF_INET: 61 return (inet_ntop4(src, dst, size)); 62 case AF_INET6: 63 return (inet_ntop6(src, dst, size)); 64 default: 65 errno = EAFNOSUPPORT; 66 return (NULL); 67 } 68 /* NOTREACHED */ 69 } 70 71 /* const char * 72 * inet_ntop4(src, dst, size) 73 * format an IPv4 address 74 * return: 75 * `dst' (as a const) 76 * notes: 77 * (1) uses no statics 78 * (2) takes a u_char* not an in_addr as input 79 * author: 80 * Paul Vixie, 1996. 81 */ 82 static const char * 83 inet_ntop4(const u_char *src, char *dst, socklen_t size) 84 { 85 static const char fmt[] = "%u.%u.%u.%u"; 86 char tmp[sizeof "255.255.255.255"]; 87 int l; 88 89 l = snprintf(tmp, sizeof(tmp), fmt, src[0], src[1], src[2], src[3]); 90 if (l <= 0 || (socklen_t) l >= size) { 91 errno = ENOSPC; 92 return (NULL); 93 } 94 strlcpy(dst, tmp, size); 95 return (dst); 96 } 97 98 /* const char * 99 * inet_ntop6(src, dst, size) 100 * convert IPv6 binary address into presentation (printable) format 101 * author: 102 * Paul Vixie, 1996. 103 */ 104 static const char * 105 inet_ntop6(const u_char *src, char *dst, socklen_t size) 106 { 107 /* 108 * Note that int32_t and int16_t need only be "at least" large enough 109 * to contain a value of the specified size. On some systems, like 110 * Crays, there is no such thing as an integer variable with 16 bits. 111 * Keep this in mind if you think this function should have been coded 112 * to use pointer overlays. All the world's not a VAX. 113 */ 114 char tmp[sizeof "ffff:ffff:ffff:ffff:ffff:ffff:255.255.255.255"], *tp; 115 struct { int base, len; } best, cur; 116 u_int words[NS_IN6ADDRSZ / NS_INT16SZ]; 117 int i; 118 119 /* 120 * Preprocess: 121 * Copy the input (bytewise) array into a wordwise array. 122 * Find the longest run of 0x00's in src[] for :: shorthanding. 123 */ 124 memset(words, '\0', sizeof words); 125 for (i = 0; i < NS_IN6ADDRSZ; i++) 126 words[i / 2] |= (src[i] << ((1 - (i % 2)) << 3)); 127 best.base = -1; 128 best.len = 0; 129 cur.base = -1; 130 cur.len = 0; 131 for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) { 132 if (words[i] == 0) { 133 if (cur.base == -1) 134 cur.base = i, cur.len = 1; 135 else 136 cur.len++; 137 } else { 138 if (cur.base != -1) { 139 if (best.base == -1 || cur.len > best.len) 140 best = cur; 141 cur.base = -1; 142 } 143 } 144 } 145 if (cur.base != -1) { 146 if (best.base == -1 || cur.len > best.len) 147 best = cur; 148 } 149 if (best.base != -1 && best.len < 2) 150 best.base = -1; 151 152 /* 153 * Format the result. 154 */ 155 tp = tmp; 156 for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) { 157 /* Are we inside the best run of 0x00's? */ 158 if (best.base != -1 && i >= best.base && 159 i < (best.base + best.len)) { 160 if (i == best.base) 161 *tp++ = ':'; 162 continue; 163 } 164 /* Are we following an initial run of 0x00s or any real hex? */ 165 if (i != 0) 166 *tp++ = ':'; 167 /* Is this address an encapsulated IPv4? */ 168 if (i == 6 && best.base == 0 && (best.len == 6 || 169 (best.len == 7 && words[7] != 0x0001) || 170 (best.len == 5 && words[5] == 0xffff))) { 171 if (!inet_ntop4(src+12, tp, sizeof tmp - (tp - tmp))) { 172 errno = ENOSPC; 173 return (NULL); 174 } 175 tp += strlen(tp); 176 break; 177 } 178 tp += sprintf(tp, "%x", words[i]); 179 } 180 /* Was it a trailing run of 0x00's? */ 181 if (best.base != -1 && (best.base + best.len) == 182 (NS_IN6ADDRSZ / NS_INT16SZ)) 183 *tp++ = ':'; 184 *tp++ = '\0'; 185 186 /* 187 * Check for overflow, copy, and we're done. 188 */ 189 if ((socklen_t)(tp - tmp) > size) { 190 errno = ENOSPC; 191 return (NULL); 192 } 193 strcpy(dst, tmp); 194 return (dst); 195 } 196 197 /* 198 * Weak aliases for applications that use certain private entry points, 199 * and fail to include <arpa/inet.h>. 200 */ 201 #undef inet_ntop 202 __weak_reference(__inet_ntop, inet_ntop); 203 204 /*! \file */ 205