1 /* $OpenBSD: inet_ntop.c,v 1.2 2014/05/20 09:16:43 mpi 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 <net/if.h> 24 #include <netinet/in.h> 25 26 #define IN6ADDRSZ 16 27 #define INT16SZ 2 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 #ifdef INET6 36 static const char *inet_ntop6(const u_char *src, char *dst, size_t size); 37 #endif /* INET6 */ 38 39 /* char * 40 * inet_ntop(af, src, dst, size) 41 * convert a network format address to presentation format. 42 * return: 43 * pointer to presentation format address (`dst'), or NULL (see errno). 44 * author: 45 * Paul Vixie, 1996. 46 */ 47 const char * 48 inet_ntop(int af, const void *src, char *dst, socklen_t size) 49 { 50 switch (af) { 51 case AF_INET: 52 return (inet_ntop4(src, dst, (size_t)size)); 53 #ifdef INET6 54 case AF_INET6: 55 return (inet_ntop6(src, dst, (size_t)size)); 56 #endif /* INET6 */ 57 default: 58 return (NULL); 59 } 60 /* NOTREACHED */ 61 } 62 63 /* const char * 64 * inet_ntop4(src, dst, size) 65 * format an IPv4 address, more or less like inet_ntoa() 66 * return: 67 * `dst' (as a const) 68 * notes: 69 * (1) uses no statics 70 * (2) takes a u_char* not an in_addr as input 71 * author: 72 * Paul Vixie, 1996. 73 */ 74 static const char * 75 inet_ntop4(const u_char *src, char *dst, size_t size) 76 { 77 char tmp[sizeof "255.255.255.255"]; 78 int l; 79 80 l = snprintf(tmp, sizeof(tmp), "%u.%u.%u.%u", 81 src[0], src[1], src[2], src[3]); 82 if (l <= 0 || l >= size) { 83 return (NULL); 84 } 85 strlcpy(dst, tmp, size); 86 return (dst); 87 } 88 89 #ifdef INET6 90 /* const char * 91 * inet_ntop6(src, dst, size) 92 * convert IPv6 binary address into presentation (printable) format 93 * author: 94 * Paul Vixie, 1996. 95 */ 96 static const char * 97 inet_ntop6(const u_char *src, char *dst, size_t size) 98 { 99 /* 100 * Note that int32_t and int16_t need only be "at least" large enough 101 * to contain a value of the specified size. On some systems, like 102 * Crays, there is no such thing as an integer variable with 16 bits. 103 * Keep this in mind if you think this function should have been coded 104 * to use pointer overlays. All the world's not a VAX. 105 */ 106 char tmp[sizeof "ffff:ffff:ffff:ffff:ffff:ffff:255.255.255.255"]; 107 char *tp, *ep; 108 struct { int base, len; } best, cur; 109 u_int words[IN6ADDRSZ / INT16SZ]; 110 int i; 111 int advance; 112 113 /* 114 * Preprocess: 115 * Copy the input (bytewise) array into a wordwise array. 116 * Find the longest run of 0x00's in src[] for :: shorthanding. 117 */ 118 memset(words, '\0', sizeof words); 119 for (i = 0; i < IN6ADDRSZ; i++) 120 words[i / 2] |= (src[i] << ((1 - (i % 2)) << 3)); 121 best.base = -1; 122 cur.base = -1; 123 for (i = 0; i < (IN6ADDRSZ / INT16SZ); i++) { 124 if (words[i] == 0) { 125 if (cur.base == -1) 126 cur.base = i, cur.len = 1; 127 else 128 cur.len++; 129 } else { 130 if (cur.base != -1) { 131 if (best.base == -1 || cur.len > best.len) 132 best = cur; 133 cur.base = -1; 134 } 135 } 136 } 137 if (cur.base != -1) { 138 if (best.base == -1 || cur.len > best.len) 139 best = cur; 140 } 141 if (best.base != -1 && best.len < 2) 142 best.base = -1; 143 144 /* 145 * Format the result. 146 */ 147 tp = tmp; 148 ep = tmp + sizeof(tmp); 149 for (i = 0; i < (IN6ADDRSZ / INT16SZ) && tp < ep; i++) { 150 /* Are we inside the best run of 0x00's? */ 151 if (best.base != -1 && i >= best.base && 152 i < (best.base + best.len)) { 153 if (i == best.base) { 154 if (tp + 1 >= ep) 155 return (NULL); 156 *tp++ = ':'; 157 } 158 continue; 159 } 160 /* Are we following an initial run of 0x00s or any real hex? */ 161 if (i != 0) { 162 if (tp + 1 >= ep) 163 return (NULL); 164 *tp++ = ':'; 165 } 166 /* Is this address an encapsulated IPv4? */ 167 if (i == 6 && best.base == 0 && 168 (best.len == 6 || (best.len == 5 && words[5] == 0xffff))) { 169 if (!inet_ntop4(src+12, tp, (size_t)(ep - tp))) 170 return (NULL); 171 tp += strlen(tp); 172 break; 173 } 174 advance = snprintf(tp, ep - tp, "%x", words[i]); 175 if (advance <= 0 || advance >= ep - tp) 176 return (NULL); 177 tp += advance; 178 } 179 /* Was it a trailing run of 0x00's? */ 180 if (best.base != -1 && (best.base + best.len) == (IN6ADDRSZ / INT16SZ)) { 181 if (tp + 1 >= ep) 182 return (NULL); 183 *tp++ = ':'; 184 } 185 if (tp + 1 >= ep) 186 return (NULL); 187 *tp++ = '\0'; 188 189 /* 190 * Check for overflow, copy, and we're done. 191 */ 192 if ((size_t)(tp - tmp) > size) { 193 return (NULL); 194 } 195 strlcpy(dst, tmp, size); 196 return (dst); 197 } 198 #endif /* INET6 */ 199