1 /* $NetBSD: inet_ntop.c,v 1.12 2018/03/02 06:31:53 lukem Exp $ */ 2 3 /* 4 * Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC") 5 * Copyright (c) 1996-1999 by Internet Software Consortium. 6 * 7 * Permission to use, copy, modify, and distribute this software for any 8 * purpose with or without fee is hereby granted, provided that the above 9 * copyright notice and this permission notice appear in all copies. 10 * 11 * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES 12 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 13 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR 14 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 15 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN 16 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT 17 * OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 18 */ 19 20 #include <sys/cdefs.h> 21 #if defined(LIBC_SCCS) && !defined(lint) 22 #if 0 23 static const char rcsid[] = "Id: inet_ntop.c,v 1.5 2005/11/03 22:59:52 marka Exp"; 24 #else 25 __RCSID("$NetBSD: inet_ntop.c,v 1.12 2018/03/02 06:31:53 lukem Exp $"); 26 #endif 27 #endif /* LIBC_SCCS and not lint */ 28 29 #include "port_before.h" 30 31 #include "namespace.h" 32 #include <sys/param.h> 33 #include <sys/types.h> 34 #include <sys/socket.h> 35 36 #include <netinet/in.h> 37 #include <arpa/inet.h> 38 #include <arpa/nameser.h> 39 40 #include <assert.h> 41 #include <errno.h> 42 #include <stdio.h> 43 #include <stdlib.h> 44 #include <string.h> 45 46 #include "port_after.h" 47 48 #ifdef __weak_alias 49 __weak_alias(inet_ntop,_inet_ntop) 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(const u_char *src, char *dst, socklen_t size); 58 static const char *inet_ntop6(const u_char *src, char *dst, socklen_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(int af, const void *src, char *dst, socklen_t size) 70 { 71 72 _DIAGASSERT(src != NULL); 73 _DIAGASSERT(dst != NULL); 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(const u_char *src, char *dst, socklen_t size) 100 { 101 char tmp[sizeof "255.255.255.255"]; 102 int l; 103 104 _DIAGASSERT(src != NULL); 105 _DIAGASSERT(dst != NULL); 106 107 l = snprintf(tmp, sizeof(tmp), "%u.%u.%u.%u", 108 src[0], src[1], src[2], src[3]); 109 if (l <= 0 || (socklen_t) l >= size) { 110 errno = ENOSPC; 111 return NULL; 112 } 113 strlcpy(dst, tmp, size); 114 return dst; 115 } 116 117 /* const char * 118 * inet_ntop6(src, dst, size) 119 * convert IPv6 binary address into presentation (printable) format 120 * author: 121 * Paul Vixie, 1996. 122 */ 123 static const char * 124 inet_ntop6(const u_char *src, char *dst, socklen_t size) 125 { 126 /* 127 * Note that int32_t and int16_t need only be "at least" large enough 128 * to contain a value of the specified size. On some systems, like 129 * Crays, there is no such thing as an integer variable with 16 bits. 130 * Keep this in mind if you think this function should have been coded 131 * to use pointer overlays. All the world's not a VAX. 132 */ 133 char tmp[sizeof "ffff:ffff:ffff:ffff:ffff:ffff:255.255.255.255"]; 134 char *tp, *ep; 135 struct { int base, len; } best, cur; 136 u_int words[NS_IN6ADDRSZ / NS_INT16SZ]; 137 int i; 138 int advance; 139 140 _DIAGASSERT(src != NULL); 141 _DIAGASSERT(dst != NULL); 142 143 /* 144 * Preprocess: 145 * Copy the input (bytewise) array into a wordwise array. 146 * Find the longest run of 0x00's in src[] for :: shorthanding. 147 */ 148 memset(words, '\0', sizeof words); 149 for (i = 0; i < NS_IN6ADDRSZ; i++) 150 words[i / 2] |= (src[i] << ((1 - (i % 2)) << 3)); 151 best.base = -1; 152 best.len = 0; 153 cur.base = -1; 154 cur.len = 0; 155 for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) { 156 if (words[i] == 0) { 157 if (cur.base == -1) 158 cur.base = i, cur.len = 1; 159 else 160 cur.len++; 161 } else { 162 if (cur.base != -1) { 163 if (best.base == -1 || cur.len > best.len) 164 best = cur; 165 cur.base = -1; 166 } 167 } 168 } 169 if (cur.base != -1) { 170 if (best.base == -1 || cur.len > best.len) 171 best = cur; 172 } 173 if (best.base != -1 && best.len < 2) 174 best.base = -1; 175 176 /* 177 * Format the result. 178 */ 179 tp = tmp; 180 ep = tmp + sizeof(tmp); 181 for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) { 182 /* Are we inside the best run of 0x00's? */ 183 if (best.base != -1 && i >= best.base && 184 i < (best.base + best.len)) { 185 if (i == best.base) 186 *tp++ = ':'; 187 continue; 188 } 189 /* Are we following an initial run of 0x00s or any real hex? */ 190 if (i != 0) { 191 if (tp + 1 >= ep) 192 goto out; 193 *tp++ = ':'; 194 } 195 /* Is this address an encapsulated IPv4? */ 196 if (i == 6 && best.base == 0 && 197 (best.len == 6 || 198 (best.len == 7 && words[7] != 0x0001) || 199 (best.len == 5 && words[5] == 0xffff))) { 200 if (!inet_ntop4(src + 12, tp, (socklen_t)(ep - tp))) 201 goto out; 202 tp += strlen(tp); 203 break; 204 } 205 advance = snprintf(tp, (size_t)(ep - tp), "%x", words[i]); 206 if (advance <= 0 || advance >= ep - tp) 207 goto out; 208 tp += advance; 209 } 210 /* Was it a trailing run of 0x00's? */ 211 if (best.base != -1 && (best.base + best.len) == 212 (NS_IN6ADDRSZ / NS_INT16SZ)) { 213 if (tp + 1 >= ep) 214 goto out; 215 *tp++ = ':'; 216 } 217 if (tp + 1 >= ep) 218 goto out; 219 *tp++ = '\0'; 220 221 /* 222 * Check for overflow, copy, and we're done. 223 */ 224 if ((size_t)(tp - tmp) > size) 225 goto out; 226 strlcpy(dst, tmp, size); 227 return dst; 228 out: 229 errno = ENOSPC; 230 return NULL; 231 } 232 233 /*! \file */ 234