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 /* OPENBSD ORIGINAL: lib/libc/net/inet_ntop.c */ 20 21 #include "includes.h" 22 23 #ifndef HAVE_INET_NTOP 24 25 #include <sys/param.h> 26 #include <sys/types.h> 27 #include <sys/socket.h> 28 #include <netinet/in.h> 29 #include <arpa/inet.h> 30 #include <arpa/nameser.h> 31 #include <string.h> 32 #include <errno.h> 33 #include <stdio.h> 34 35 #ifndef IN6ADDRSZ 36 #define IN6ADDRSZ 16 /* IPv6 T_AAAA */ 37 #endif 38 39 #ifndef INT16SZ 40 #define INT16SZ 2 /* for systems without 16-bit ints */ 41 #endif 42 43 /* 44 * WARNING: Don't even consider trying to compile this on a system where 45 * sizeof(int) < 4. sizeof(int) > 4 is fine; all the world's not a VAX. 46 */ 47 48 static const char *inet_ntop4(const u_char *src, char *dst, size_t size); 49 static const char *inet_ntop6(const u_char *src, char *dst, size_t size); 50 51 /* char * 52 * inet_ntop(af, src, dst, size) 53 * convert a network format address to presentation format. 54 * return: 55 * pointer to presentation format address (`dst'), or NULL (see errno). 56 * author: 57 * Paul Vixie, 1996. 58 */ 59 const char * 60 inet_ntop(int af, const void *src, char *dst, size_t size) 61 { 62 switch (af) { 63 case AF_INET: 64 return (inet_ntop4(src, dst, size)); 65 case AF_INET6: 66 return (inet_ntop6(src, dst, size)); 67 default: 68 errno = EAFNOSUPPORT; 69 return (NULL); 70 } 71 /* NOTREACHED */ 72 } 73 74 /* const char * 75 * inet_ntop4(src, dst, size) 76 * format an IPv4 address, more or less like inet_ntoa() 77 * return: 78 * `dst' (as a const) 79 * notes: 80 * (1) uses no statics 81 * (2) takes a u_char* not an in_addr as input 82 * author: 83 * Paul Vixie, 1996. 84 */ 85 static const char * 86 inet_ntop4(const u_char *src, char *dst, size_t size) 87 { 88 static const char fmt[] = "%u.%u.%u.%u"; 89 char tmp[sizeof "255.255.255.255"]; 90 int l; 91 92 l = snprintf(tmp, size, fmt, src[0], src[1], src[2], src[3]); 93 if (l <= 0 || l >= size) { 94 errno = ENOSPC; 95 return (NULL); 96 } 97 strlcpy(dst, tmp, size); 98 return (dst); 99 } 100 101 /* const char * 102 * inet_ntop6(src, dst, size) 103 * convert IPv6 binary address into presentation (printable) format 104 * author: 105 * Paul Vixie, 1996. 106 */ 107 static const char * 108 inet_ntop6(const u_char *src, char *dst, size_t size) 109 { 110 /* 111 * Note that int32_t and int16_t need only be "at least" large enough 112 * to contain a value of the specified size. On some systems, like 113 * Crays, there is no such thing as an integer variable with 16 bits. 114 * Keep this in mind if you think this function should have been coded 115 * to use pointer overlays. All the world's not a VAX. 116 */ 117 char tmp[sizeof "ffff:ffff:ffff:ffff:ffff:ffff:255.255.255.255"]; 118 char *tp, *ep; 119 struct { int base, len; } best, cur; 120 u_int words[IN6ADDRSZ / INT16SZ]; 121 int i; 122 int advance; 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 ep = tmp + sizeof(tmp); 160 for (i = 0; i < (IN6ADDRSZ / INT16SZ) && tp < ep; i++) { 161 /* Are we inside the best run of 0x00's? */ 162 if (best.base != -1 && i >= best.base && 163 i < (best.base + best.len)) { 164 if (i == best.base) { 165 if (tp + 1 >= ep) 166 return (NULL); 167 *tp++ = ':'; 168 } 169 continue; 170 } 171 /* Are we following an initial run of 0x00s or any real hex? */ 172 if (i != 0) { 173 if (tp + 1 >= ep) 174 return (NULL); 175 *tp++ = ':'; 176 } 177 /* Is this address an encapsulated IPv4? */ 178 if (i == 6 && best.base == 0 && 179 (best.len == 6 || (best.len == 5 && words[5] == 0xffff))) { 180 if (!inet_ntop4(src+12, tp, (size_t)(ep - tp))) 181 return (NULL); 182 tp += strlen(tp); 183 break; 184 } 185 advance = snprintf(tp, ep - tp, "%x", words[i]); 186 if (advance <= 0 || advance >= ep - tp) 187 return (NULL); 188 tp += advance; 189 } 190 /* Was it a trailing run of 0x00's? */ 191 if (best.base != -1 && (best.base + best.len) == (IN6ADDRSZ / INT16SZ)) { 192 if (tp + 1 >= ep) 193 return (NULL); 194 *tp++ = ':'; 195 } 196 if (tp + 1 >= ep) 197 return (NULL); 198 *tp++ = '\0'; 199 200 /* 201 * Check for overflow, copy, and we're done. 202 */ 203 if ((size_t)(tp - tmp) > size) { 204 errno = ENOSPC; 205 return (NULL); 206 } 207 strlcpy(dst, tmp, size); 208 return (dst); 209 } 210 211 #endif /* !HAVE_INET_NTOP */ 212