1 /* $OpenBSD: inet_ntop.c,v 1.3 2015/03/14 03:38:51 jsg 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/systm.h> 21 #include <sys/socket.h> 22 23 #include <netinet/in.h> 24 25 #define IN6ADDRSZ 16 26 #define INT16SZ 2 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 #ifdef INET6 35 static const char *inet_ntop6(const u_char *src, char *dst, size_t size); 36 #endif /* INET6 */ 37 38 /* char * 39 * inet_ntop(af, src, dst, size) 40 * convert a network format address to presentation format. 41 * return: 42 * pointer to presentation format address (`dst'), or NULL (see errno). 43 * author: 44 * Paul Vixie, 1996. 45 */ 46 const char * 47 inet_ntop(int af, const void *src, char *dst, socklen_t size) 48 { 49 switch (af) { 50 case AF_INET: 51 return (inet_ntop4(src, dst, (size_t)size)); 52 #ifdef INET6 53 case AF_INET6: 54 return (inet_ntop6(src, dst, (size_t)size)); 55 #endif /* INET6 */ 56 default: 57 return (NULL); 58 } 59 /* NOTREACHED */ 60 } 61 62 /* const char * 63 * inet_ntop4(src, dst, size) 64 * format an IPv4 address, more or less like inet_ntoa() 65 * return: 66 * `dst' (as a const) 67 * notes: 68 * (1) uses no statics 69 * (2) takes a u_char* not an in_addr as input 70 * author: 71 * Paul Vixie, 1996. 72 */ 73 static const char * 74 inet_ntop4(const u_char *src, char *dst, size_t size) 75 { 76 char tmp[sizeof "255.255.255.255"]; 77 int l; 78 79 l = snprintf(tmp, sizeof(tmp), "%u.%u.%u.%u", 80 src[0], src[1], src[2], src[3]); 81 if (l <= 0 || l >= size) { 82 return (NULL); 83 } 84 strlcpy(dst, tmp, size); 85 return (dst); 86 } 87 88 #ifdef INET6 89 /* const char * 90 * inet_ntop6(src, dst, size) 91 * convert IPv6 binary address into presentation (printable) format 92 * author: 93 * Paul Vixie, 1996. 94 */ 95 static const char * 96 inet_ntop6(const u_char *src, char *dst, size_t size) 97 { 98 /* 99 * Note that int32_t and int16_t need only be "at least" large enough 100 * to contain a value of the specified size. On some systems, like 101 * Crays, there is no such thing as an integer variable with 16 bits. 102 * Keep this in mind if you think this function should have been coded 103 * to use pointer overlays. All the world's not a VAX. 104 */ 105 char tmp[sizeof "ffff:ffff:ffff:ffff:ffff:ffff:255.255.255.255"]; 106 char *tp, *ep; 107 struct { int base, len; } best, cur; 108 u_int words[IN6ADDRSZ / INT16SZ]; 109 int i; 110 int advance; 111 112 /* 113 * Preprocess: 114 * Copy the input (bytewise) array into a wordwise array. 115 * Find the longest run of 0x00's in src[] for :: shorthanding. 116 */ 117 memset(words, '\0', sizeof words); 118 for (i = 0; i < IN6ADDRSZ; i++) 119 words[i / 2] |= (src[i] << ((1 - (i % 2)) << 3)); 120 best.base = -1; 121 cur.base = -1; 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 return (NULL); 193 } 194 strlcpy(dst, tmp, size); 195 return (dst); 196 } 197 #endif /* INET6 */ 198