1 /* $OpenBSD: inet_ntop.c,v 1.6 2005/03/25 13:24:12 otto 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 1.6 2005/03/25 13:24:12 otto 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(int af, const void *src, char *dst, size_t size) 55 { 56 switch (af) { 57 case AF_INET: 58 return (inet_ntop4(src, dst, size)); 59 case AF_INET6: 60 return (inet_ntop6(src, dst, size)); 61 default: 62 errno = EAFNOSUPPORT; 63 return (NULL); 64 } 65 /* NOTREACHED */ 66 } 67 68 /* const char * 69 * inet_ntop4(src, dst, size) 70 * format an IPv4 address, more or less like inet_ntoa() 71 * return: 72 * `dst' (as a const) 73 * notes: 74 * (1) uses no statics 75 * (2) takes a u_char* not an in_addr as input 76 * author: 77 * Paul Vixie, 1996. 78 */ 79 static const char * 80 inet_ntop4(const u_char *src, char *dst, size_t size) 81 { 82 static const char fmt[] = "%u.%u.%u.%u"; 83 char tmp[sizeof "255.255.255.255"]; 84 int l; 85 86 l = snprintf(tmp, size, fmt, src[0], src[1], src[2], src[3]); 87 if (l <= 0 || l >= size) { 88 errno = ENOSPC; 89 return (NULL); 90 } 91 strlcpy(dst, tmp, size); 92 return (dst); 93 } 94 95 /* const char * 96 * inet_ntop6(src, dst, size) 97 * convert IPv6 binary address into presentation (printable) format 98 * author: 99 * Paul Vixie, 1996. 100 */ 101 static const char * 102 inet_ntop6(const u_char *src, char *dst, size_t size) 103 { 104 /* 105 * Note that int32_t and int16_t need only be "at least" large enough 106 * to contain a value of the specified size. On some systems, like 107 * Crays, there is no such thing as an integer variable with 16 bits. 108 * Keep this in mind if you think this function should have been coded 109 * to use pointer overlays. All the world's not a VAX. 110 */ 111 char tmp[sizeof "ffff:ffff:ffff:ffff:ffff:ffff:255.255.255.255"]; 112 char *tp, *ep; 113 struct { int base, len; } best, cur; 114 u_int words[IN6ADDRSZ / INT16SZ]; 115 int i; 116 int advance; 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 < IN6ADDRSZ; i++) 125 words[i / 2] |= (src[i] << ((1 - (i % 2)) << 3)); 126 best.base = -1; 127 cur.base = -1; 128 for (i = 0; i < (IN6ADDRSZ / INT16SZ); i++) { 129 if (words[i] == 0) { 130 if (cur.base == -1) 131 cur.base = i, cur.len = 1; 132 else 133 cur.len++; 134 } else { 135 if (cur.base != -1) { 136 if (best.base == -1 || cur.len > best.len) 137 best = cur; 138 cur.base = -1; 139 } 140 } 141 } 142 if (cur.base != -1) { 143 if (best.base == -1 || cur.len > best.len) 144 best = cur; 145 } 146 if (best.base != -1 && best.len < 2) 147 best.base = -1; 148 149 /* 150 * Format the result. 151 */ 152 tp = tmp; 153 ep = tmp + sizeof(tmp); 154 for (i = 0; i < (IN6ADDRSZ / INT16SZ) && tp < ep; i++) { 155 /* Are we inside the best run of 0x00's? */ 156 if (best.base != -1 && i >= best.base && 157 i < (best.base + best.len)) { 158 if (i == best.base) { 159 if (tp + 1 >= ep) 160 return (NULL); 161 *tp++ = ':'; 162 } 163 continue; 164 } 165 /* Are we following an initial run of 0x00s or any real hex? */ 166 if (i != 0) { 167 if (tp + 1 >= ep) 168 return (NULL); 169 *tp++ = ':'; 170 } 171 /* Is this address an encapsulated IPv4? */ 172 if (i == 6 && best.base == 0 && 173 (best.len == 6 || (best.len == 5 && words[5] == 0xffff))) { 174 if (!inet_ntop4(src+12, tp, (size_t)(ep - tp))) 175 return (NULL); 176 tp += strlen(tp); 177 break; 178 } 179 advance = snprintf(tp, ep - tp, "%x", words[i]); 180 if (advance <= 0 || advance >= ep - tp) 181 return (NULL); 182 tp += advance; 183 } 184 /* Was it a trailing run of 0x00's? */ 185 if (best.base != -1 && (best.base + best.len) == (IN6ADDRSZ / INT16SZ)) { 186 if (tp + 1 >= ep) 187 return (NULL); 188 *tp++ = ':'; 189 } 190 if (tp + 1 >= ep) 191 return (NULL); 192 *tp++ = '\0'; 193 194 /* 195 * Check for overflow, copy, and we're done. 196 */ 197 if ((size_t)(tp - tmp) > size) { 198 errno = ENOSPC; 199 return (NULL); 200 } 201 strlcpy(dst, tmp, size); 202 return (dst); 203 } 204