1 /* $OpenBSD: inet_ntop.c,v 1.1 1997/03/13 19:07:32 downsj 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 "config.h" 20 21 #ifndef HAVE_INET_NTOP 22 23 #if defined(LIBC_SCCS) && !defined(lint) 24 #if 0 25 static char rcsid[] = "$From: inet_ntop.c,v 8.7 1996/08/05 08:41:18 vixie Exp $"; 26 #else 27 static char rcsid[] = "$OpenBSD: inet_ntop.c,v 1.1 1997/03/13 19:07:32 downsj Exp $"; 28 #endif 29 #endif /* LIBC_SCCS and not lint */ 30 31 #include <sys/param.h> 32 #include <sys/types.h> 33 #include <sys/socket.h> 34 #include "openbsd-compat/fake-socket.h" 35 #include <netinet/in.h> 36 #include <arpa/inet.h> 37 #ifndef HAVE_CYGWIN 38 #include <arpa/nameser.h> 39 #endif 40 #include <string.h> 41 #include <errno.h> 42 #include <stdio.h> 43 44 #ifndef IN6ADDRSZ 45 #define IN6ADDRSZ 16 /* IPv6 T_AAAA */ 46 #endif 47 48 #ifndef INT16SZ 49 #define INT16SZ 2 /* for systems without 16-bit ints */ 50 #endif 51 52 /* 53 * WARNING: Don't even consider trying to compile this on a system where 54 * sizeof(int) < 4. sizeof(int) > 4 is fine; all the world's not a VAX. 55 */ 56 57 static const char *inet_ntop4 __P((const u_char *src, char *dst, size_t size)); 58 static const char *inet_ntop6 __P((const u_char *src, char *dst, size_t size)); 59 60 /* char * 61 * inet_ntop(af, src, dst, size) 62 * convert a network format address to presentation format. 63 * return: 64 * pointer to presentation format address (`dst'), or NULL (see errno). 65 * author: 66 * Paul Vixie, 1996. 67 */ 68 const char * 69 inet_ntop(af, src, dst, size) 70 int af; 71 const void *src; 72 char *dst; 73 size_t size; 74 { 75 switch (af) { 76 case AF_INET: 77 return (inet_ntop4(src, dst, size)); 78 case AF_INET6: 79 return (inet_ntop6(src, dst, size)); 80 default: 81 errno = EAFNOSUPPORT; 82 return (NULL); 83 } 84 /* NOTREACHED */ 85 } 86 87 /* const char * 88 * inet_ntop4(src, dst, size) 89 * format an IPv4 address, more or less like inet_ntoa() 90 * return: 91 * `dst' (as a const) 92 * notes: 93 * (1) uses no statics 94 * (2) takes a u_char* not an in_addr as input 95 * author: 96 * Paul Vixie, 1996. 97 */ 98 static const char * 99 inet_ntop4(src, dst, size) 100 const u_char *src; 101 char *dst; 102 size_t size; 103 { 104 static const char fmt[] = "%u.%u.%u.%u"; 105 char tmp[sizeof "255.255.255.255"]; 106 107 if (snprintf(tmp, sizeof(tmp), fmt, src[0], src[1], src[2], 108 src[3]) > size) { 109 errno = ENOSPC; 110 return (NULL); 111 } 112 strcpy(dst, tmp); 113 return (dst); 114 } 115 116 /* const char * 117 * inet_ntop6(src, dst, size) 118 * convert IPv6 binary address into presentation (printable) format 119 * author: 120 * Paul Vixie, 1996. 121 */ 122 static const char * 123 inet_ntop6(src, dst, size) 124 const u_char *src; 125 char *dst; 126 size_t size; 127 { 128 /* 129 * Note that int32_t and int16_t need only be "at least" large enough 130 * to contain a value of the specified size. On some systems, like 131 * Crays, there is no such thing as an integer variable with 16 bits. 132 * Keep this in mind if you think this function should have been coded 133 * to use pointer overlays. All the world's not a VAX. 134 */ 135 char tmp[sizeof "ffff:ffff:ffff:ffff:ffff:ffff:255.255.255.255"], *tp; 136 struct { int base, len; } best, cur; 137 u_int words[IN6ADDRSZ / INT16SZ]; 138 int i; 139 140 /* 141 * Preprocess: 142 * Copy the input (bytewise) array into a wordwise array. 143 * Find the longest run of 0x00's in src[] for :: shorthanding. 144 */ 145 memset(words, '\0', sizeof words); 146 for (i = 0; i < IN6ADDRSZ; i++) 147 words[i / 2] |= (src[i] << ((1 - (i % 2)) << 3)); 148 best.base = -1; 149 cur.base = -1; 150 for (i = 0; i < (IN6ADDRSZ / INT16SZ); i++) { 151 if (words[i] == 0) { 152 if (cur.base == -1) 153 cur.base = i, cur.len = 1; 154 else 155 cur.len++; 156 } else { 157 if (cur.base != -1) { 158 if (best.base == -1 || cur.len > best.len) 159 best = cur; 160 cur.base = -1; 161 } 162 } 163 } 164 if (cur.base != -1) { 165 if (best.base == -1 || cur.len > best.len) 166 best = cur; 167 } 168 if (best.base != -1 && best.len < 2) 169 best.base = -1; 170 171 /* 172 * Format the result. 173 */ 174 tp = tmp; 175 for (i = 0; i < (IN6ADDRSZ / INT16SZ); i++) { 176 /* Are we inside the best run of 0x00's? */ 177 if (best.base != -1 && i >= best.base && 178 i < (best.base + best.len)) { 179 if (i == best.base) 180 *tp++ = ':'; 181 continue; 182 } 183 /* Are we following an initial run of 0x00s or any real hex? */ 184 if (i != 0) 185 *tp++ = ':'; 186 /* Is this address an encapsulated IPv4? */ 187 if (i == 6 && best.base == 0 && 188 (best.len == 6 || (best.len == 5 && words[5] == 0xffff))) { 189 if (!inet_ntop4(src+12, tp, sizeof tmp - (tp - tmp))) 190 return (NULL); 191 tp += strlen(tp); 192 break; 193 } 194 snprintf(tp, sizeof(tmp - (tp - tmp)), "%x", words[i]); 195 tp += strlen(tp); 196 } 197 /* Was it a trailing run of 0x00's? */ 198 if (best.base != -1 && (best.base + best.len) == (IN6ADDRSZ / INT16SZ)) 199 *tp++ = ':'; 200 *tp++ = '\0'; 201 202 /* 203 * Check for overflow, copy, and we're done. 204 */ 205 if ((size_t)(tp - tmp) > size) { 206 errno = ENOSPC; 207 return (NULL); 208 } 209 strcpy(dst, tmp); 210 return (dst); 211 } 212 213 #endif /* !HAVE_INET_NTOP */ 214