1 /* $NetBSD: inet_ntop.c,v 1.2 2024/08/18 20:47:14 christos Exp $ */ 2 3 /* 4 * Copyright (C) 2004, 2005, 2007, 2009 Internet Systems Consortium, Inc. ("ISC") 5 * Copyright (C) 1996-2001 Internet Software Consortium. 6 * 7 * Permission to use, copy, modify, and/or 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 WITH 12 * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY 13 * AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT, 14 * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM 15 * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE 16 * OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR 17 * PERFORMANCE OF THIS SOFTWARE. 18 */ 19 20 /*! \file */ 21 22 #if defined(LIBC_SCCS) && !defined(lint) 23 static char rcsid[] = 24 "Id: inet_ntop.c,v 1.21 2009/07/17 23:47:41 tbox Exp "; 25 #endif /* LIBC_SCCS and not lint */ 26 27 #include <config.h> 28 29 #include <errno.h> 30 #include <stdio.h> 31 #include <string.h> 32 33 #include <isc/net.h> 34 #include <isc/print.h> 35 36 #define NS_INT16SZ 2 37 #define NS_IN6ADDRSZ 16 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 unsigned char *src, char *dst, 45 size_t size); 46 47 #ifdef AF_INET6 48 static const char *inet_ntop6(const unsigned char *src, char *dst, 49 size_t size); 50 #endif 51 const char *isc_net_ntop(int af, const void *src, char *dst, size_t size); 52 53 /*! char * 54 * isc_net_ntop(af, src, dst, size) 55 * convert a network format address to presentation format. 56 * \return 57 * pointer to presentation format address (`dst'), or NULL (see errno). 58 * \author 59 * Paul Vixie, 1996. 60 */ 61 const char * 62 isc_net_ntop(int af, const void *src, char *dst, size_t size) 63 { 64 switch (af) { 65 case AF_INET: 66 return (inet_ntop4(src, dst, size)); 67 #ifdef AF_INET6 68 case AF_INET6: 69 return (inet_ntop6(src, dst, size)); 70 #endif 71 default: 72 errno = EAFNOSUPPORT; 73 return (NULL); 74 } 75 /* NOTREACHED */ 76 } 77 78 /*! const char * 79 * inet_ntop4(src, dst, size) 80 * format an IPv4 address 81 * \return 82 * `dst' (as a const) 83 * \note 84 * (1) uses no statics 85 * \note 86 * (2) takes a unsigned char* not an in_addr as input 87 * \author 88 * Paul Vixie, 1996. 89 */ 90 static const char * 91 inet_ntop4(const unsigned char *src, char *dst, size_t size) 92 { 93 #define fmt "%u.%u.%u.%u" 94 char tmp[sizeof("255.255.255.255")]; 95 int len; 96 97 len = snprintf(tmp, sizeof(tmp), fmt, src[0], src[1], src[2], src[3]); 98 if (len < 0 || (size_t)len >= size) 99 { 100 errno = ENOSPC; 101 return (NULL); 102 } 103 memcpy(dst, tmp, 1 + len); 104 105 return (dst); 106 } 107 108 /*! const char * 109 * isc_inet_ntop6(src, dst, size) 110 * convert IPv6 binary address into presentation (printable) format 111 * \author 112 * Paul Vixie, 1996. 113 */ 114 #ifdef AF_INET6 115 static const char * 116 inet_ntop6(const unsigned char *src, char *dst, size_t size) 117 { 118 /* 119 * Note that int32_t and int16_t need only be "at least" large enough 120 * to contain a value of the specified size. On some systems, like 121 * Crays, there is no such thing as an integer variable with 16 bits. 122 * Keep this in mind if you think this function should have been coded 123 * to use pointer overlays. All the world's not a VAX. 124 */ 125 char tmp[sizeof("ffff:ffff:ffff:ffff:ffff:ffff:255.255.255.255")], *tp; 126 struct { int base, len; } best, cur; 127 unsigned int words[NS_IN6ADDRSZ / NS_INT16SZ]; 128 int i; 129 130 /* 131 * Preprocess: 132 * Copy the input (bytewise) array into a wordwise array. 133 * Find the longest run of 0x00's in src[] for :: shorthanding. 134 */ 135 memset(words, '\0', sizeof(words)); 136 for (i = 0; i < NS_IN6ADDRSZ; i++) 137 words[i / 2] |= (src[i] << ((1 - (i % 2)) << 3)); 138 best.base = -1; 139 cur.base = -1; 140 best.len = cur.len = 0; 141 for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) { 142 if (words[i] == 0) { 143 if (cur.base == -1) 144 cur.base = i, cur.len = 1; 145 else 146 cur.len++; 147 } else { 148 if (cur.base != -1) { 149 if (best.base == -1 || cur.len > best.len) 150 best = cur; 151 cur.base = -1; 152 } 153 } 154 } 155 if (cur.base != -1) { 156 if (best.base == -1 || cur.len > best.len) 157 best = cur; 158 } 159 if (best.base != -1 && best.len < 2) 160 best.base = -1; 161 162 /* 163 * Format the result. 164 */ 165 tp = tmp; 166 for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) { 167 /* Are we inside the best run of 0x00's? */ 168 if (best.base != -1 && i >= best.base && 169 i < (best.base + best.len)) { 170 if (i == best.base) 171 *tp++ = ':'; 172 continue; 173 } 174 /* Are we following an initial run of 0x00s or any real hex? */ 175 if (i != 0) 176 *tp++ = ':'; 177 /* Is this address an encapsulated IPv4? */ 178 if (i == 6 && best.base == 0 && (best.len == 6 || 179 (best.len == 7 && words[7] != 0x0001) || 180 (best.len == 5 && words[5] == 0xffff))) { 181 if (!inet_ntop4(src+12, tp, 182 sizeof(tmp) - (tp - tmp))) 183 return (NULL); 184 tp += strlen(tp); 185 break; 186 } 187 tp += snprintf(tp, sizeof(tmp) - (tp - tmp), "%x", words[i]); 188 } 189 /* Was it a trailing run of 0x00's? */ 190 if (best.base != -1 && (best.base + best.len) == 191 (NS_IN6ADDRSZ / NS_INT16SZ)) 192 *tp++ = ':'; 193 *tp++ = '\0'; 194 195 /* 196 * Check for overflow, copy, and we're done. 197 */ 198 if ((size_t)(tp - tmp) > size) { 199 errno = ENOSPC; 200 return (NULL); 201 } 202 memcpy(dst, tmp, (size_t)(tp - tmp)); 203 return (dst); 204 } 205 #endif /* AF_INET6 */ 206