1 /* $OpenBSD: inet_ntop.c,v 1.7 2005/08/06 20:30:03 espie 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 #include <sys/param.h> 20 #include <sys/types.h> 21 #include <sys/socket.h> 22 #include <netinet/in.h> 23 #include <arpa/inet.h> 24 #include "arpa_nameser.h" 25 #include <string.h> 26 #include <errno.h> 27 #include <stdio.h> 28 29 /* 30 * WARNING: Don't even consider trying to compile this on a system where 31 * sizeof(int) < 4. sizeof(int) > 4 is fine; all the world's not a VAX. 32 */ 33 34 static const char *inet_ntop4(const u_char *src, char *dst, size_t size); 35 static const char *inet_ntop6(const u_char *src, char *dst, size_t size); 36 37 /* char * 38 * inet_ntop(af, src, dst, size) 39 * convert a network format address to presentation format. 40 * return: 41 * pointer to presentation format address (`dst'), or NULL (see errno). 42 * author: 43 * Paul Vixie, 1996. 44 */ 45 const char * 46 inet_ntop(int af, const void *src, char *dst, size_t size) 47 { 48 switch (af) { 49 case AF_INET: 50 return (inet_ntop4(src, dst, size)); 51 case AF_INET6: 52 return (inet_ntop6(src, dst, size)); 53 default: 54 errno = EAFNOSUPPORT; 55 return (NULL); 56 } 57 /* NOTREACHED */ 58 } 59 60 /* const char * 61 * inet_ntop4(src, dst, size) 62 * format an IPv4 address, more or less like inet_ntoa() 63 * return: 64 * `dst' (as a const) 65 * notes: 66 * (1) uses no statics 67 * (2) takes a u_char* not an in_addr as input 68 * author: 69 * Paul Vixie, 1996. 70 */ 71 static const char * 72 inet_ntop4(const u_char *src, char *dst, size_t size) 73 { 74 static const char fmt[] = "%u.%u.%u.%u"; 75 char tmp[sizeof "255.255.255.255"]; 76 int l; 77 78 l = snprintf(tmp, size, fmt, src[0], src[1], src[2], src[3]); 79 if (l <= 0 || (size_t)l >= size) { 80 errno = ENOSPC; 81 return (NULL); 82 } 83 strlcpy(dst, tmp, size); 84 return (dst); 85 } 86 87 /* const char * 88 * inet_ntop6(src, dst, size) 89 * convert IPv6 binary address into presentation (printable) format 90 * author: 91 * Paul Vixie, 1996. 92 */ 93 static const char * 94 inet_ntop6(const u_char *src, char *dst, size_t size) 95 { 96 /* 97 * Note that int32_t and int16_t need only be "at least" large enough 98 * to contain a value of the specified size. On some systems, like 99 * Crays, there is no such thing as an integer variable with 16 bits. 100 * Keep this in mind if you think this function should have been coded 101 * to use pointer overlays. All the world's not a VAX. 102 */ 103 char tmp[sizeof "ffff:ffff:ffff:ffff:ffff:ffff:255.255.255.255"]; 104 char *tp, *ep; 105 struct { int base, len; } best, cur; 106 u_int words[IN6ADDRSZ / INT16SZ]; 107 int i; 108 int advance; 109 110 /* 111 * Preprocess: 112 * Copy the input (bytewise) array into a wordwise array. 113 * Find the longest run of 0x00's in src[] for :: shorthanding. 114 */ 115 memset(words, '\0', sizeof words); 116 for (i = 0; i < IN6ADDRSZ; i++) 117 words[i / 2] |= (src[i] << ((1 - (i % 2)) << 3)); 118 best.base = -1; 119 best.len = 0; 120 cur.base = -1; 121 cur.len = 0; 122 for (i = 0; i < (IN6ADDRSZ / INT16SZ); i++) { 123 if (words[i] == 0) { 124 if (cur.base == -1) 125 cur.base = i, cur.len = 1; 126 else 127 cur.len++; 128 } else { 129 if (cur.base != -1) { 130 if (best.base == -1 || cur.len > best.len) 131 best = cur; 132 cur.base = -1; 133 } 134 } 135 } 136 if (cur.base != -1) { 137 if (best.base == -1 || cur.len > best.len) 138 best = cur; 139 } 140 if (best.base != -1 && best.len < 2) 141 best.base = -1; 142 143 /* 144 * Format the result. 145 */ 146 tp = tmp; 147 ep = tmp + sizeof(tmp); 148 for (i = 0; i < (IN6ADDRSZ / INT16SZ) && tp < ep; i++) { 149 /* Are we inside the best run of 0x00's? */ 150 if (best.base != -1 && i >= best.base && 151 i < (best.base + best.len)) { 152 if (i == best.base) { 153 if (tp + 1 >= ep) 154 return (NULL); 155 *tp++ = ':'; 156 } 157 continue; 158 } 159 /* Are we following an initial run of 0x00s or any real hex? */ 160 if (i != 0) { 161 if (tp + 1 >= ep) 162 return (NULL); 163 *tp++ = ':'; 164 } 165 /* Is this address an encapsulated IPv4? */ 166 if (i == 6 && best.base == 0 && 167 (best.len == 6 || (best.len == 5 && words[5] == 0xffff))) { 168 if (!inet_ntop4(src+12, tp, (size_t)(ep - tp))) 169 return (NULL); 170 tp += strlen(tp); 171 break; 172 } 173 advance = snprintf(tp, ep - tp, "%x", words[i]); 174 if (advance <= 0 || advance >= ep - tp) 175 return (NULL); 176 tp += advance; 177 } 178 /* Was it a trailing run of 0x00's? */ 179 if (best.base != -1 && (best.base + best.len) == (IN6ADDRSZ / INT16SZ)) { 180 if (tp + 1 >= ep) 181 return (NULL); 182 *tp++ = ':'; 183 } 184 if (tp + 1 >= ep) 185 return (NULL); 186 *tp++ = '\0'; 187 188 /* 189 * Check for overflow, copy, and we're done. 190 */ 191 if ((size_t)(tp - tmp) > size) { 192 errno = ENOSPC; 193 return (NULL); 194 } 195 strlcpy(dst, tmp, size); 196 return (dst); 197 } 198
