1 /* $OpenBSD: inet_ntop.c,v 1.4 2016/09/04 17:05:24 claudio 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 sockaddr_ntop(struct sockaddr *sa, char *dst, size_t size) 64 { 65 u_int8_t l; 66 size_t n; 67 68 if (sa->sa_len < 2) 69 return "bad sa"; 70 switch (sa->sa_family) { 71 case AF_INET: 72 return inet_ntop4((u_char *)&satosin(sa)->sin_addr, dst, size); 73 #ifdef INET6 74 case AF_INET6: 75 return inet_ntop6((u_char *)&satosin6(sa)->sin6_addr, dst, size); 76 #endif 77 default: 78 n = snprintf(dst, size, "%d ", sa->sa_family); 79 for (l = 0; l < sa->sa_len - offsetof(struct sockaddr, sa_data); l++) { 80 int r = snprintf(dst + n, size - n, "%02x", sa->sa_data[l]); 81 if (r == -1) 82 return "bad sa"; 83 n += r; 84 if (n > size) 85 n = size; 86 } 87 return (dst); 88 } 89 } 90 91 /* const char * 92 * inet_ntop4(src, dst, size) 93 * format an IPv4 address, more or less like inet_ntoa() 94 * return: 95 * `dst' (as a const) 96 * notes: 97 * (1) uses no statics 98 * (2) takes a u_char* not an in_addr as input 99 * author: 100 * Paul Vixie, 1996. 101 */ 102 static const char * 103 inet_ntop4(const u_char *src, char *dst, size_t size) 104 { 105 char tmp[sizeof "255.255.255.255"]; 106 int l; 107 108 l = snprintf(tmp, sizeof(tmp), "%u.%u.%u.%u", 109 src[0], src[1], src[2], src[3]); 110 if (l <= 0 || l >= size) { 111 return (NULL); 112 } 113 strlcpy(dst, tmp, size); 114 return (dst); 115 } 116 117 #ifdef INET6 118 /* const char * 119 * inet_ntop6(src, dst, size) 120 * convert IPv6 binary address into presentation (printable) format 121 * author: 122 * Paul Vixie, 1996. 123 */ 124 static const char * 125 inet_ntop6(const u_char *src, char *dst, size_t size) 126 { 127 /* 128 * Note that int32_t and int16_t need only be "at least" large enough 129 * to contain a value of the specified size. On some systems, like 130 * Crays, there is no such thing as an integer variable with 16 bits. 131 * Keep this in mind if you think this function should have been coded 132 * to use pointer overlays. All the world's not a VAX. 133 */ 134 char tmp[sizeof "ffff:ffff:ffff:ffff:ffff:ffff:255.255.255.255"]; 135 char *tp, *ep; 136 struct { int base, len; } best, cur; 137 u_int words[IN6ADDRSZ / INT16SZ]; 138 int i; 139 int advance; 140 141 /* 142 * Preprocess: 143 * Copy the input (bytewise) array into a wordwise array. 144 * Find the longest run of 0x00's in src[] for :: shorthanding. 145 */ 146 memset(words, '\0', sizeof words); 147 for (i = 0; i < IN6ADDRSZ; i++) 148 words[i / 2] |= (src[i] << ((1 - (i % 2)) << 3)); 149 best.base = -1; 150 cur.base = -1; 151 for (i = 0; i < (IN6ADDRSZ / INT16SZ); i++) { 152 if (words[i] == 0) { 153 if (cur.base == -1) 154 cur.base = i, cur.len = 1; 155 else 156 cur.len++; 157 } else { 158 if (cur.base != -1) { 159 if (best.base == -1 || cur.len > best.len) 160 best = cur; 161 cur.base = -1; 162 } 163 } 164 } 165 if (cur.base != -1) { 166 if (best.base == -1 || cur.len > best.len) 167 best = cur; 168 } 169 if (best.base != -1 && best.len < 2) 170 best.base = -1; 171 172 /* 173 * Format the result. 174 */ 175 tp = tmp; 176 ep = tmp + sizeof(tmp); 177 for (i = 0; i < (IN6ADDRSZ / INT16SZ) && tp < ep; i++) { 178 /* Are we inside the best run of 0x00's? */ 179 if (best.base != -1 && i >= best.base && 180 i < (best.base + best.len)) { 181 if (i == best.base) { 182 if (tp + 1 >= ep) 183 return (NULL); 184 *tp++ = ':'; 185 } 186 continue; 187 } 188 /* Are we following an initial run of 0x00s or any real hex? */ 189 if (i != 0) { 190 if (tp + 1 >= ep) 191 return (NULL); 192 *tp++ = ':'; 193 } 194 /* Is this address an encapsulated IPv4? */ 195 if (i == 6 && best.base == 0 && 196 (best.len == 6 || (best.len == 5 && words[5] == 0xffff))) { 197 if (!inet_ntop4(src+12, tp, (size_t)(ep - tp))) 198 return (NULL); 199 tp += strlen(tp); 200 break; 201 } 202 advance = snprintf(tp, ep - tp, "%x", words[i]); 203 if (advance <= 0 || advance >= ep - tp) 204 return (NULL); 205 tp += advance; 206 } 207 /* Was it a trailing run of 0x00's? */ 208 if (best.base != -1 && (best.base + best.len) == (IN6ADDRSZ / INT16SZ)) { 209 if (tp + 1 >= ep) 210 return (NULL); 211 *tp++ = ':'; 212 } 213 if (tp + 1 >= ep) 214 return (NULL); 215 *tp++ = '\0'; 216 217 /* 218 * Check for overflow, copy, and we're done. 219 */ 220 if ((size_t)(tp - tmp) > size) { 221 return (NULL); 222 } 223 strlcpy(dst, tmp, size); 224 return (dst); 225 } 226 #endif /* INET6 */ 227