1 /* $OpenBSD: inet_ntop.c,v 1.2 2002/02/16 21:27:23 millert Exp $ */ 2 3 /* Copyright (c) 1996 by Internet Software Consortium. 4 * 5 * Permission to use, copy, modify, and distribute this software for any 6 * purpose with or without fee is hereby granted, provided that the above 7 * copyright notice and this permission notice appear in all copies. 8 * 9 * THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM DISCLAIMS 10 * ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES 11 * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE 12 * CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL 13 * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR 14 * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS 15 * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS 16 * SOFTWARE. 17 */ 18 19 #if defined(LIBC_SCCS) && !defined(lint) 20 #if 0 21 static char rcsid[] = "$From: inet_ntop.c,v 8.7 1996/08/05 08:41:18 vixie Exp $"; 22 #else 23 static char rcsid[] = "$OpenBSD: inet_ntop.c,v 1.2 2002/02/16 21:27:23 millert Exp $"; 24 #endif 25 #endif /* LIBC_SCCS and not lint */ 26 27 #include <sys/param.h> 28 #include <sys/types.h> 29 #include <sys/socket.h> 30 #include <netinet/in.h> 31 #include <arpa/inet.h> 32 #include <arpa/nameser.h> 33 #include <string.h> 34 #include <errno.h> 35 #include <stdio.h> 36 37 /* 38 * WARNING: Don't even consider trying to compile this on a system where 39 * sizeof(int) < 4. sizeof(int) > 4 is fine; all the world's not a VAX. 40 */ 41 42 static const char *inet_ntop4(const u_char *src, char *dst, size_t size); 43 static const char *inet_ntop6(const u_char *src, char *dst, size_t size); 44 45 /* char * 46 * inet_ntop(af, src, dst, size) 47 * convert a network format address to presentation format. 48 * return: 49 * pointer to presentation format address (`dst'), or NULL (see errno). 50 * author: 51 * Paul Vixie, 1996. 52 */ 53 const char * 54 inet_ntop(af, src, dst, size) 55 int af; 56 const void *src; 57 char *dst; 58 size_t size; 59 { 60 switch (af) { 61 case AF_INET: 62 return (inet_ntop4(src, dst, size)); 63 case AF_INET6: 64 return (inet_ntop6(src, dst, size)); 65 default: 66 errno = EAFNOSUPPORT; 67 return (NULL); 68 } 69 /* NOTREACHED */ 70 } 71 72 /* const char * 73 * inet_ntop4(src, dst, size) 74 * format an IPv4 address, more or less like inet_ntoa() 75 * return: 76 * `dst' (as a const) 77 * notes: 78 * (1) uses no statics 79 * (2) takes a u_char* not an in_addr as input 80 * author: 81 * Paul Vixie, 1996. 82 */ 83 static const char * 84 inet_ntop4(src, dst, size) 85 const u_char *src; 86 char *dst; 87 size_t size; 88 { 89 static const char fmt[] = "%u.%u.%u.%u"; 90 char tmp[sizeof "255.255.255.255"]; 91 92 if (sprintf(tmp, fmt, src[0], src[1], src[2], src[3]) > size) { 93 errno = ENOSPC; 94 return (NULL); 95 } 96 strcpy(dst, tmp); 97 return (dst); 98 } 99 100 /* const char * 101 * inet_ntop6(src, dst, size) 102 * convert IPv6 binary address into presentation (printable) format 103 * author: 104 * Paul Vixie, 1996. 105 */ 106 static const char * 107 inet_ntop6(src, dst, size) 108 const u_char *src; 109 char *dst; 110 size_t size; 111 { 112 /* 113 * Note that int32_t and int16_t need only be "at least" large enough 114 * to contain a value of the specified size. On some systems, like 115 * Crays, there is no such thing as an integer variable with 16 bits. 116 * Keep this in mind if you think this function should have been coded 117 * to use pointer overlays. All the world's not a VAX. 118 */ 119 char tmp[sizeof "ffff:ffff:ffff:ffff:ffff:ffff:255.255.255.255"], *tp; 120 struct { int base, len; } best, cur; 121 u_int words[IN6ADDRSZ / INT16SZ]; 122 int i; 123 124 /* 125 * Preprocess: 126 * Copy the input (bytewise) array into a wordwise array. 127 * Find the longest run of 0x00's in src[] for :: shorthanding. 128 */ 129 memset(words, '\0', sizeof words); 130 for (i = 0; i < IN6ADDRSZ; i++) 131 words[i / 2] |= (src[i] << ((1 - (i % 2)) << 3)); 132 best.base = -1; 133 cur.base = -1; 134 for (i = 0; i < (IN6ADDRSZ / INT16SZ); i++) { 135 if (words[i] == 0) { 136 if (cur.base == -1) 137 cur.base = i, cur.len = 1; 138 else 139 cur.len++; 140 } else { 141 if (cur.base != -1) { 142 if (best.base == -1 || cur.len > best.len) 143 best = cur; 144 cur.base = -1; 145 } 146 } 147 } 148 if (cur.base != -1) { 149 if (best.base == -1 || cur.len > best.len) 150 best = cur; 151 } 152 if (best.base != -1 && best.len < 2) 153 best.base = -1; 154 155 /* 156 * Format the result. 157 */ 158 tp = tmp; 159 for (i = 0; i < (IN6ADDRSZ / INT16SZ); i++) { 160 /* Are we inside the best run of 0x00's? */ 161 if (best.base != -1 && i >= best.base && 162 i < (best.base + best.len)) { 163 if (i == best.base) 164 *tp++ = ':'; 165 continue; 166 } 167 /* Are we following an initial run of 0x00s or any real hex? */ 168 if (i != 0) 169 *tp++ = ':'; 170 /* Is this address an encapsulated IPv4? */ 171 if (i == 6 && best.base == 0 && 172 (best.len == 6 || (best.len == 5 && words[5] == 0xffff))) { 173 if (!inet_ntop4(src+12, tp, sizeof tmp - (tp - tmp))) 174 return (NULL); 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) == (IN6ADDRSZ / INT16SZ)) 182 *tp++ = ':'; 183 *tp++ = '\0'; 184 185 /* 186 * Check for overflow, copy, and we're done. 187 */ 188 if ((size_t)(tp - tmp) > size) { 189 errno = ENOSPC; 190 return (NULL); 191 } 192 strcpy(dst, tmp); 193 return (dst); 194 } 195