lib/libc/net/ether_addr.c

   1 /*
   2  * Copyright (c) 1995 Bill Paul <wpaul@ctr.columbia.edu>.
   3  * Copyright (c) 2007 Robert N. M. Watson
   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  * 1. Redistributions of source code must retain the above copyright
  10  *    notice, this list of conditions and the following disclaimer.
  11  * 2. Redistributions in binary form must reproduce the above copyright
  12  *    notice, this list of conditions and the following disclaimer in the
  13  *    documentation and/or other materials provided with the distribution.
  14  * 3. All advertising materials mentioning features or use of this software
  15  *    must display the following acknowledgement:
  16  *      This product includes software developed by Bill Paul.
  17  * 4. Neither the name of the author nor the names of any co-contributors
  18  *    may be used to endorse or promote products derived from this software
  19  *    without specific prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY Bill Paul AND CONTRIBUTORS ``AS IS'' AND
  22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  31  * SUCH DAMAGE.
  32  *
  33  * ethernet address conversion and lookup routines
  34  *
  35  * Written by Bill Paul <wpaul@ctr.columbia.edu>
  36  * Center for Telecommunications Research
  37  * Columbia University, New York City
  38  *
  39  * $FreeBSD: src/lib/libc/net/ether_addr.c,v 1.17 2007/05/13 13:57:44 rwatson Exp $
  40  * $DragonFly: src/lib/libc/net/ether_addr.c,v 1.4 2005/11/13 02:04:47 swildner Exp $
  41  */
  42
  43 #include <sys/types.h>
  44 #include <sys/param.h>
  45 #include <sys/socket.h>
  46
  47 #include <net/ethernet.h>
  48
  49 #ifdef YP
  50 #include <rpc/rpc.h>
  51 #include <rpcsvc/yp_prot.h>
  52 #include <rpcsvc/ypclnt.h>
  53 #endif
  54
  55 #include <paths.h>
  56 #include <stdio.h>
  57 #include <stdlib.h>
  58 #include <string.h>
  59
  60 #ifndef _PATH_ETHERS
  61 #define _PATH_ETHERS    "/etc/ethers"
  62 #endif
  63
  64 /*
  65  * Parse a string of text containing an ethernet address and hostname and
  66  * separate it into its component parts.
  67  *
  68  * XXX Hack, constrain hostname scan to 255 characters.  Hardwired from
  69  * MAXHOSTNAMELEN which is 256. The API is badly broken but cannot be
  70  * changed.
  71  */
  72 int
  73 ether_line(const char *l, struct ether_addr *e, char *hostname)
  74 {
  75         int i, o[6];
  76
  77         i = sscanf(l, "%x:%x:%x:%x:%x:%x %255s", &o[0], &o[1], &o[2], &o[3],
  78             &o[4], &o[5], hostname);
  79         if (i != 7)
  80                 return (i);
  81         for (i=0; i<6; i++)
  82                 e->octet[i] = o[i];
  83         return (0);
  84 }
  85
  86 /*
  87  * Convert an ASCII representation of an ethernet address to binary form.
  88  */
  89 struct ether_addr *
  90 ether_aton_r(const char *a, struct ether_addr *e)
  91 {
  92         int i;
  93         unsigned int o0, o1, o2, o3, o4, o5;
  94
  95         i = sscanf(a, "%x:%x:%x:%x:%x:%x", &o0, &o1, &o2, &o3, &o4, &o5);
  96         if (i != 6)
  97                 return (NULL);
  98         e->octet[0]=o0;
  99         e->octet[1]=o1;
 100         e->octet[2]=o2;
 101         e->octet[3]=o3;
 102         e->octet[4]=o4;
 103         e->octet[5]=o5;
 104         return (e);
 105 }
 106
 107 struct ether_addr *
 108 ether_aton(const char *a)
 109 {
 110         static struct ether_addr e;
 111
 112         return (ether_aton_r(a, &e));
 113 }
 114
 115 /*
 116  * Convert a binary representation of an ethernet address to an ASCII string.
 117  */
 118 char *
 119 ether_ntoa_r(const struct ether_addr *n, char *a)
 120 {
 121         int i;
 122
 123         i = sprintf(a, "%02x:%02x:%02x:%02x:%02x:%02x", n->octet[0],
 124             n->octet[1], n->octet[2], n->octet[3], n->octet[4], n->octet[5]);
 125         if (i < 17)
 126                 return (NULL);
 127         return (a);
 128 }
 129
 130 char *
 131 ether_ntoa(const struct ether_addr *n)
 132 {
 133         static char a[18];
 134
 135         return (ether_ntoa_r(n, a));
 136 }
 137
 138 /*
 139  * Map an ethernet address to a hostname. Use either /etc/ethers or NIS/YP.
 140  */
 141 int
 142 ether_ntohost(char *hostname, const struct ether_addr *e)
 143 {
 144         FILE *fp;
 145         char buf[BUFSIZ + 2];
 146         struct ether_addr local_ether;
 147         char local_host[MAXHOSTNAMELEN];
 148 #ifdef YP
 149         char *result;
 150         int resultlen;
 151         char *ether_a;
 152         char *yp_domain;
 153 #endif
 154
 155         if ((fp = fopen(_PATH_ETHERS, "r")) == NULL)
 156                 return (1);
 157         while (fgets(buf,BUFSIZ,fp)) {
 158                 if (buf[0] == '#')
 159                         continue;
 160 #ifdef YP
 161                 if (buf[0] == '+') {
 162                         if (yp_get_default_domain(&yp_domain))
 163                                 continue;
 164                         ether_a = ether_ntoa(e);
 165                         if (yp_match(yp_domain, "ethers.byaddr", ether_a,
 166                             strlen(ether_a), &result, &resultlen)) {
 167                                 continue;
 168                         }
 169                         strncpy(buf, result, resultlen);
 170                         buf[resultlen] = '\0';
 171                         free(result);
 172                 }
 173 #endif
 174                 if (!ether_line(buf, &local_ether, local_host)) {
 175                         if (!bcmp((char *)&local_ether.octet[0],
 176                             (char *)&e->octet[0], 6)) {
 177                                 /* We have a match. */
 178                                 strcpy(hostname, local_host);
 179                                 fclose(fp);
 180                                 return(0);
 181                         }
 182                 }
 183         }
 184         fclose(fp);
 185         return (1);
 186 }
 187
 188 /*
 189  * Map a hostname to an ethernet address using /etc/ethers or NIS/YP.
 190  */
 191 int
 192 ether_hostton(const char *hostname, struct ether_addr *e)
 193 {
 194         FILE *fp;
 195         char buf[BUFSIZ + 2];
 196         struct ether_addr local_ether;
 197         char local_host[MAXHOSTNAMELEN];
 198 #ifdef YP
 199         char *result;
 200         int resultlen;
 201         char *yp_domain;
 202 #endif
 203
 204         if ((fp = fopen(_PATH_ETHERS, "r")) == NULL)
 205                 return (1);
 206         while (fgets(buf,BUFSIZ,fp)) {
 207                 if (buf[0] == '#')
 208                         continue;
 209 #ifdef YP
 210                 if (buf[0] == '+') {
 211                         if (yp_get_default_domain(&yp_domain))
 212                                 continue;
 213                         if (yp_match(yp_domain, "ethers.byname", hostname,
 214                             strlen(hostname), &result, &resultlen)) {
 215                                 continue;
 216                         }
 217                         strncpy(buf, result, resultlen);
 218                         buf[resultlen] = '\0';
 219                         free(result);
 220                 }
 221 #endif
 222                 if (!ether_line(buf, &local_ether, local_host)) {
 223                         if (!strcmp(hostname, local_host)) {
 224                                 /* We have a match. */
 225                                 bcopy((char *)&local_ether.octet[0],
 226                                     (char *)&e->octet[0], 6);
 227                                 fclose(fp);
 228                                 return(0);
 229                         }
 230                 }
 231         }
 232         fclose(fp);
 233         return (1);
 234 }