1 /* 2 * Copyright (c) 1999 Kungliga Tekniska Hgskolan 3 * (Royal Institute of Technology, Stockholm, Sweden). 4 * All rights reserved. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 17 * 3. All advertising materials mentioning features or use of this software 18 * must display the following acknowledgement: 19 * This product includes software developed by the Kungliga Tekniska 20 * Hgskolan and its contributors. 21 * 22 * 4. Neither the name of the Institute nor the names of its contributors 23 * may be used to endorse or promote products derived from this software 24 * without specific prior written permission. 25 * 26 * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND 27 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 28 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 29 * ARE DISCLAIMED. IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE 30 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 31 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 32 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 33 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 34 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 35 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 36 * SUCH DAMAGE. 37 */ 38 39 #include <sys/cdefs.h> 40 #ifndef lint 41 __RCSID("$NetBSD: addrtostr.c,v 1.7 2026/03/19 00:05:13 christos Exp $"); 42 #endif 43 44 #include <config.h> 45 46 #include "netdissect-stdinc.h" 47 #include "addrtostr.h" 48 49 #include <stdio.h> 50 #include <string.h> 51 52 /* 53 * 54 */ 55 56 #ifndef IN6ADDRSZ 57 #define IN6ADDRSZ 16 /* IPv6 T_AAAA */ 58 #endif 59 60 #ifndef INT16SZ 61 #define INT16SZ 2 /* word size */ 62 #endif 63 64 const char * 65 addrtostr (const void *src, char *dst, size_t size) 66 { 67 const u_char *srcaddr = (const u_char *)src; 68 const char digits[] = "0123456789"; 69 int i; 70 const char *orig_dst = dst; 71 72 if (size < INET_ADDRSTRLEN) { 73 errno = ENOSPC; 74 return NULL; 75 } 76 for (i = 0; i < 4; ++i) { 77 int n = *srcaddr++; 78 int non_zerop = 0; 79 80 if (non_zerop || n / 100 > 0) { 81 *dst++ = digits[n / 100]; 82 n %= 100; 83 non_zerop = 1; 84 } 85 if (non_zerop || n / 10 > 0) { 86 *dst++ = digits[n / 10]; 87 n %= 10; 88 non_zerop = 1; 89 } 90 *dst++ = digits[n]; 91 if (i != 3) 92 *dst++ = '.'; 93 } 94 *dst++ = '\0'; 95 return orig_dst; 96 } 97 98 /* 99 * Convert IPv6 binary address into presentation (printable) format. 100 */ 101 const char * 102 addrtostr6 (const void *src, char *dst, size_t size) 103 { 104 /* 105 * Note that int32_t and int16_t need only be "at least" large enough 106 * to contain a value of the specified size. On some systems, like 107 * Crays, there is no such thing as an integer variable with 16 bits. 108 * Keep this in mind if you think this function should have been coded 109 * to use pointer overlays. All the world's not a VAX. 110 */ 111 const u_char *srcaddr = (const u_char *)src; 112 char *dp; 113 size_t space_left, added_space; 114 int snprintfed; 115 struct { 116 int base; 117 int len; 118 } best, cur; 119 uint16_t words [IN6ADDRSZ / INT16SZ]; 120 int i; 121 122 /* Preprocess: 123 * Copy the input (bytewise) array into a wordwise array. 124 * Find the longest run of 0x00's in src[] for :: shorthanding. 125 */ 126 for (i = 0; i < (IN6ADDRSZ / INT16SZ); i++) 127 words[i] = (srcaddr[2*i] << 8) | srcaddr[2*i + 1]; 128 129 best.len = 0; 130 best.base = -1; 131 cur.len = 0; 132 cur.base = -1; 133 for (i = 0; i < (IN6ADDRSZ / INT16SZ); i++) { 134 if (words[i] == 0) { 135 if (cur.base == -1) { 136 cur.base = i; 137 cur.len = 1; 138 } else 139 cur.len++; 140 } else if (cur.base != -1) { 141 if (best.base == -1 || cur.len > best.len) 142 best = cur; 143 cur.base = -1; 144 } 145 } 146 if ((cur.base != -1) && (best.base == -1 || cur.len > best.len)) 147 best = cur; 148 if (best.base != -1 && best.len < 2) 149 best.base = -1; 150 151 /* Format the result. 152 */ 153 dp = dst; 154 space_left = size; 155 #define APPEND_CHAR(c) \ 156 { \ 157 if (space_left == 0) { \ 158 errno = ENOSPC; \ 159 return (NULL); \ 160 } \ 161 *dp++ = c; \ 162 space_left--; \ 163 } 164 for (i = 0; i < (IN6ADDRSZ / INT16SZ); i++) { 165 /* Are we inside the best run of 0x00's? 166 */ 167 if (best.base != -1 && i >= best.base && i < (best.base + best.len)) { 168 if (i == best.base) 169 APPEND_CHAR(':'); 170 continue; 171 } 172 173 /* Are we following an initial run of 0x00s or any real hex? 174 */ 175 if (i != 0) 176 APPEND_CHAR(':'); 177 178 /* Is this address an encapsulated IPv4? 179 */ 180 if (i == 6 && best.base == 0 && 181 (best.len == 6 || (best.len == 5 && words[5] == 0xffff))) 182 { 183 if (!addrtostr(srcaddr+12, dp, space_left)) { 184 errno = ENOSPC; 185 return (NULL); 186 } 187 added_space = strlen(dp); 188 dp += added_space; 189 space_left -= added_space; 190 break; 191 } 192 snprintfed = snprintf (dp, space_left, "%x", words[i]); 193 if (snprintfed < 0) 194 return (NULL); 195 if ((size_t) snprintfed >= space_left) { 196 errno = ENOSPC; 197 return (NULL); 198 } 199 dp += snprintfed; 200 space_left -= snprintfed; 201 } 202 203 /* Was it a trailing run of 0x00's? 204 */ 205 if (best.base != -1 && (best.base + best.len) == (IN6ADDRSZ / INT16SZ)) 206 APPEND_CHAR(':'); 207 APPEND_CHAR('\0'); 208 209 return (dst); 210 } 211
Indexes created Wed Aug 19 00:25:20 UTC 2026