1 /* $OpenBSD: inet_ntop.c,v 1.13 2016/09/21 04:38:56 guenther 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/types.h> 20 #include <sys/socket.h> 21 #include <netinet/in.h> 22 #include <arpa/inet.h> 23 #include <arpa/nameser.h> 24 #include <string.h> 25 #include <errno.h> 26 #include <stdio.h> 27 28 /* 29 * WARNING: Don't even consider trying to compile this on a system where 30 * sizeof(int) < 4. sizeof(int) > 4 is fine; all the world's not a VAX. 31 */ 32 33 static const char *inet_ntop4(const u_char *src, char *dst, size_t size); 34 static const char *inet_ntop6(const u_char *src, char *dst, size_t size); 35 36 /* const char * 37 * inet_ntop(af, src, dst, size) 38 * convert a network format address to presentation format. 39 * return: 40 * pointer to presentation format address (`dst'), or NULL (see errno). 41 * author: 42 * Paul Vixie, 1996. 43 */ 44 const char * 45 inet_ntop(int af, const void *src, char *dst, socklen_t size) 46 { 47 switch (af) { 48 case AF_INET: 49 return (inet_ntop4(src, dst, size)); 50 case AF_INET6: 51 return (inet_ntop6(src, dst, size)); 52 default: 53 errno = EAFNOSUPPORT; 54 return (NULL); 55 } 56 /* NOTREACHED */ 57 } 58 DEF_WEAK(inet_ntop); 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 char tmp[sizeof "255.255.255.255"]; 75 int l; 76 77 l = snprintf(tmp, sizeof(tmp), "%u.%u.%u.%u", 78 src[0], src[1], src[2], src[3]); 79 if (l <= 0 || 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 cur.base = -1; 120 for (i = 0; i < (IN6ADDRSZ / INT16SZ); i++) { 121 if (words[i] == 0) { 122 if (cur.base == -1) 123 cur.base = i, cur.len = 1; 124 else 125 cur.len++; 126 } else { 127 if (cur.base != -1) { 128 if (best.base == -1 || cur.len > best.len) 129 best = cur; 130 cur.base = -1; 131 } 132 } 133 } 134 if (cur.base != -1) { 135 if (best.base == -1 || cur.len > best.len) 136 best = cur; 137 } 138 if (best.base != -1 && best.len < 2) 139 best.base = -1; 140 141 /* 142 * Format the result. 143 */ 144 tp = tmp; 145 ep = tmp + sizeof(tmp); 146 for (i = 0; i < (IN6ADDRSZ / INT16SZ) && tp < ep; i++) { 147 /* Are we inside the best run of 0x00's? */ 148 if (best.base != -1 && i >= best.base && 149 i < (best.base + best.len)) { 150 if (i == best.base) { 151 if (tp + 1 >= ep) { 152 errno = ENOSPC; 153 return (NULL); 154 } 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 errno = ENOSPC; 163 return (NULL); 164 } 165 *tp++ = ':'; 166 } 167 /* Is this address an encapsulated IPv4? */ 168 if (i == 6 && best.base == 0 && 169 (best.len == 6 || (best.len == 5 && words[5] == 0xffff))) { 170 if (!inet_ntop4(src+12, tp, ep - tp)) 171 return (NULL); 172 tp += strlen(tp); 173 break; 174 } 175 advance = snprintf(tp, ep - tp, "%x", words[i]); 176 if (advance <= 0 || advance >= ep - tp) { 177 errno = ENOSPC; 178 return (NULL); 179 } 180 tp += advance; 181 } 182 /* Was it a trailing run of 0x00's? */ 183 if (best.base != -1 && (best.base + best.len) == (IN6ADDRSZ / INT16SZ)) { 184 if (tp + 1 >= ep) { 185 errno = ENOSPC; 186 return (NULL); 187 } 188 *tp++ = ':'; 189 } 190 if (tp + 1 >= ep) { 191 errno = ENOSPC; 192 return (NULL); 193 } 194 *tp++ = '\0'; 195 196 /* 197 * Check for overflow, copy, and we're done. 198 */ 199 if ((size_t)(tp - tmp) > size) { 200 errno = ENOSPC; 201 return (NULL); 202 } 203 strlcpy(dst, tmp, size); 204 return (dst); 205 } 206
