net-snmp 5.7
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00001 /* Id: inet_ntop.c,v 1.4 2001/04/17 07:53:47 lukem Exp */ 00002 /* $NetBSD: inet_ntop.c,v 1.9 2000/01/22 22:19:16 mycroft Exp $ */ 00003 00004 /* Copyright (c) 1996 by Internet Software Consortium. 00005 * 00006 * Permission to use, copy, modify, and distribute this software for any 00007 * purpose with or without fee is hereby granted, provided that the above 00008 * copyright notice and this permission notice appear in all copies. 00009 * 00010 * THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM DISCLAIMS 00011 * ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES 00012 * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE 00013 * CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL 00014 * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR 00015 * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS 00016 * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS 00017 * SOFTWARE. 00018 */ 00019 00020 #include <net-snmp/net-snmp-config.h> 00021 00022 #if HAVE_ARPA_NAMESER_H 00023 #include <arpa/nameser.h> 00024 #endif 00025 00026 #include <errno.h> 00027 #include <stdio.h> 00028 #if HAVE_STRING_H 00029 #include <string.h> 00030 #else 00031 #include <strings.h> 00032 #endif 00033 00034 #include <net-snmp/types.h> 00035 00036 #include "inet_ntop.h" 00037 00038 #ifndef EAFNOSUPPORT 00039 #define EAFNOSUPPORT WSAEAFNOSUPPORT 00040 #endif 00041 00042 #ifndef IN6ADDRSZ 00043 #define IN6ADDRSZ 16 00044 #endif 00045 00046 #ifndef INT16SZ 00047 #define INT16SZ 2 00048 #endif 00049 00050 #ifdef SPRINTF_CHAR 00051 # define SPRINTF(x) strlen(sprintfx) 00052 #else 00053 # define SPRINTF(x) ((size_t)sprintf x) 00054 #endif 00055 00056 /* 00057 * WARNING: Don't even consider trying to compile this on a system where 00058 * sizeof(int) < 4. sizeof(int) > 4 is fine; all the world's not a VAX. 00059 */ 00060 00061 static const char *inet_ntop4(const u_char *src, char *dst, size_t size); 00062 #ifdef NETSNMP_ENABLE_IPV6 00063 static const char *inet_ntop6(const u_char *src, char *dst, size_t size); 00064 #endif /* NETSNMP_ENABLE_IPV6 */ 00065 00066 /* char * 00067 * inet_ntop(af, src, dst, size) 00068 * convert a network format address to presentation format. 00069 * return: 00070 * pointer to presentation format address (`dst'), or NULL (see errno). 00071 * author: 00072 * Paul Vixie, 1996. 00073 */ 00074 const char * 00075 inet_ntop(int af, const void *src, char *dst, size_t size) 00076 { 00077 00078 switch (af) { 00079 case AF_INET: 00080 return (inet_ntop4(src, dst, size)); 00081 #ifdef NETSNMP_ENABLE_IPV6 00082 case AF_INET6: 00083 return (inet_ntop6(src, dst, size)); 00084 #endif 00085 default: 00086 errno = EAFNOSUPPORT; 00087 return (NULL); 00088 } 00089 /* NOTREACHED */ 00090 } 00091 00092 /* const char * 00093 * inet_ntop4(src, dst, size) 00094 * format an IPv4 address, more or less like inet_ntoa() 00095 * return: 00096 * `dst' (as a const) 00097 * notes: 00098 * (1) uses no statics 00099 * (2) takes a u_char* not an in_addr as input 00100 * author: 00101 * Paul Vixie, 1996. 00102 */ 00103 static const char * 00104 inet_ntop4(const u_char *src, char *dst, size_t size) 00105 { 00106 static const char fmt[] = "%u.%u.%u.%u"; 00107 char tmp[sizeof "255.255.255.255"]; 00108 00109 if (SPRINTF((tmp, fmt, src[0], src[1], src[2], src[3])) > size) { 00110 errno = ENOSPC; 00111 return (NULL); 00112 } 00113 strcpy(dst, tmp); 00114 return (dst); 00115 } 00116 00117 #ifdef NETSNMP_ENABLE_IPV6 00118 /* const char * 00119 * inet_ntop6(src, dst, size) 00120 * convert IPv6 binary address into presentation (printable) format 00121 * author: 00122 * Paul Vixie, 1996. 00123 */ 00124 static const char * 00125 inet_ntop6(const u_char *src, char *dst, size_t size) 00126 { 00127 /* 00128 * Note that int32_t and int16_t need only be "at least" large enough 00129 * to contain a value of the specified size. On some systems, like 00130 * Crays, there is no such thing as an integer variable with 16 bits. 00131 * Keep this in mind if you think this function should have been coded 00132 * to use pointer overlays. All the world's not a VAX. 00133 */ 00134 char tmp[sizeof "ffff:ffff:ffff:ffff:ffff:ffff:255.255.255.255"], *tp; 00135 struct { int base, len; } best, cur; 00136 u_int words[IN6ADDRSZ / INT16SZ]; 00137 int i; 00138 00139 /* 00140 * Preprocess: 00141 * Copy the input (bytewise) array into a wordwise array. 00142 * Find the longest run of 0x00's in src[] for :: shorthanding. 00143 */ 00144 memset(words, '\0', sizeof words); 00145 for (i = 0; i < IN6ADDRSZ; i++) 00146 words[i / 2] |= (src[i] << ((1 - (i % 2)) << 3)); 00147 best.base = -1; 00148 cur.base = -1; 00149 for (i = 0; i < (IN6ADDRSZ / INT16SZ); i++) { 00150 if (words[i] == 0) { 00151 if (cur.base == -1) 00152 cur.base = i, cur.len = 1; 00153 else 00154 cur.len++; 00155 } else { 00156 if (cur.base != -1) { 00157 if (best.base == -1 || cur.len > best.len) 00158 best = cur; 00159 cur.base = -1; 00160 } 00161 } 00162 } 00163 if (cur.base != -1) { 00164 if (best.base == -1 || cur.len > best.len) 00165 best = cur; 00166 } 00167 if (best.base != -1 && best.len < 2) 00168 best.base = -1; 00169 00170 /* 00171 * Format the result. 00172 */ 00173 tp = tmp; 00174 for (i = 0; i < (IN6ADDRSZ / INT16SZ); i++) { 00175 /* Are we inside the best run of 0x00's? */ 00176 if (best.base != -1 && i >= best.base && 00177 i < (best.base + best.len)) { 00178 if (i == best.base) 00179 *tp++ = ':'; 00180 continue; 00181 } 00182 /* Are we following an initial run of 0x00s or any real hex? */ 00183 if (i != 0) 00184 *tp++ = ':'; 00185 /* Is this address an encapsulated IPv4? */ 00186 if (i == 6 && best.base == 0 && 00187 (best.len == 6 || (best.len == 5 && words[5] == 0xffff))) { 00188 if (!inet_ntop4(src+12, tp, sizeof tmp - (tp - tmp))) 00189 return (NULL); 00190 tp += strlen(tp); 00191 break; 00192 } 00193 tp += SPRINTF((tp, "%x", words[i])); 00194 } 00195 /* Was it a trailing run of 0x00's? */ 00196 if (best.base != -1 && (best.base + best.len) == (IN6ADDRSZ / INT16SZ)) 00197 *tp++ = ':'; 00198 *tp++ = '\0'; 00199 00200 /* 00201 * Check for overflow, copy, and we're done. 00202 */ 00203 if ((size_t)(tp - tmp) > size) { 00204 errno = ENOSPC; 00205 return (NULL); 00206 } 00207 strcpy(dst, tmp); 00208 return (dst); 00209 } 00210 #endif