usr/src/lib/libresolv/res_init.c

   1 /*
   2  * CDDL HEADER START
   3  *
   4  * The contents of this file are subject to the terms of the
   5  * Common Development and Distribution License (the "License").
   6  * You may not use this file except in compliance with the License.
   7  *
   8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
   9  * or http://www.opensolaris.org/os/licensing.
  10  * See the License for the specific language governing permissions
  11  * and limitations under the License.
  12  *
  13  * When distributing Covered Code, include this CDDL HEADER in each
  14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
  15  * If applicable, add the following below this CDDL HEADER, with the
  16  * fields enclosed by brackets "[]" replaced with your own identifying
  17  * information: Portions Copyright [yyyy] [name of copyright owner]
  18  *
  19  * CDDL HEADER END
  20  */
  21
  22 /*
  23  * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
  24  * Use is subject to license terms.
  25  */
  26
  27 /*      Copyright (c) 1984, 1986, 1987, 1988, 1989 AT&T */
  28 /*        All Rights Reserved   */
  29
  30 /*
  31  * University Copyright- Copyright (c) 1982, 1986, 1988
  32  * The Regents of the University of California
  33  * All Rights Reserved
  34  *
  35  * University Acknowledgment- Portions of this document are derived from
  36  * software developed by the University of California, Berkeley, and its
  37  * contributors.
  38  */
  39
  40 #pragma ident   "%Z%%M% %I%     %E% SMI"
  41
  42 #include <sys/types.h>
  43 #include <sys/sockio.h>
  44 #include <sys/socket.h>
  45 #include <netinet/in.h>
  46 #include <stdio.h>
  47 #include <arpa/nameser.h>
  48 #include <resolv.h>
  49
  50 #include <netinet/in.h>
  51 #include <net/if.h>
  52 #include <netinet/if_ether.h>
  53 #include <arpa/inet.h>
  54
  55 #define MAXIFS  256
  56
  57 /*
  58  * Resolver state default settings
  59  */
  60
  61 struct state _res = {
  62         RES_TIMEOUT,            /* retransmition time interval */
  63         4,                              /* number of times to retransmit */
  64         RES_DEFAULT,            /* options flags */
  65         1,                              /* number of name servers */
  66 };
  67
  68 /*
  69  * Set up default settings.  If the configuration file exist, the values
  70  * there will have precedence.  Otherwise, the server address is set to
  71  * INADDR_LOOPBACK and the default domain name comes from the gethostname().
  72  * BUT if the NIS/RPC domain name is set, that is used if all else fails.
  73  *
  74  * The configuration file should only be used if you want to redefine your
  75  * domain or run without a server on your machine.
  76  *
  77  * Note the user can always override then domain name with the environment
  78  * variable LOCALDOMAIN which has absolute priority.
  79  *
  80  *
  81  * Return 0 if completes successfully, -1 on error
  82  */
  83 int
  84 res_init(void)
  85 {
  86         register FILE *fp;
  87         register char *cp, **pp;
  88         register int n;
  89         char buf[BUFSIZ];
  90 #ifdef SYSV
  91         extern char *strchr();
  92 #else
  93         extern char *index();
  94 #endif
  95         extern char *strcpy(), *strncpy();
  96         extern char *getenv();
  97         int nserv = 0;    /* number of nameserver records read from file */
  98         int haveenv = 0;
  99         int havesearch = 0;
 100
 101         _res.nsaddr.sin_addr.s_addr =  htonl(INADDR_LOOPBACK); /* INADDR_ANY */
 102         _res.nsaddr.sin_family = AF_INET;
 103         _res.nsaddr.sin_port = htons(NAMESERVER_PORT);
 104         _res.nscount = 1;
 105
 106 #ifdef SIOCGIFNUM
 107         {       int numifs, s, n, int_up;
 108                 struct ifconf ifc;
 109                 register struct ifreq *ifrp;
 110                 struct ifreq ifr;
 111                 unsigned bufsize;
 112                 unsigned int flags;
 113                 char *buf;
 114                 extern void *malloc();
 115
 116                 if ((s = socket(AF_INET, SOCK_DGRAM, 0)) < 0) {
 117                         perror("socket");
 118                         return (-1);
 119                 }
 120                 if (ioctl(s, SIOCGIFNUM, (char *)&numifs) < 0) {
 121                         numifs = MAXIFS;
 122                 }
 123                 bufsize = numifs * sizeof (struct ifreq);
 124                 buf = (char *)malloc(bufsize);
 125                 if (buf == NULL) {
 126                         perror("out of memory");
 127                         close(s);
 128                         return (-1);
 129                 }
 130                 ifc.ifc_len = bufsize;
 131                 ifc.ifc_buf = buf;
 132                 if (ioctl(s, SIOCGIFCONF, (char *)&ifc) < 0) {
 133                         perror("ifconfig: SIOCGIFCONF");
 134                         close(s);
 135                         free(buf);
 136                         return (-1);
 137                 }
 138
 139                 int_up = 0;
 140                 ifrp = ifc.ifc_req;
 141                 for (n = ifc.ifc_len / sizeof (struct ifreq); n > 0;
 142                                                                 n--, ifrp++) {
 143                         memset((void *) &ifr, 0, sizeof (ifr));
 144                         strncpy(ifr.ifr_name, ifrp->ifr_name,
 145                                                         sizeof (ifr.ifr_name));
 146                         if (ioctl(s, SIOCGIFFLAGS, (char *)&ifr) < 0) {
 147                                 perror("SIOCGIFFLAGS");
 148                                 close(s);
 149                                 free(buf);
 150                                 return (-1);
 151                         }
 152                         flags = ifr.ifr_flags;
 153                         /* we are looking for a non-loopback interface */
 154                         if ((flags & IFF_UP) && ((flags & IFF_LOOPBACK) == 0))
 155                                 int_up = 1;
 156                 }
 157                 close(s);
 158                 free(buf);
 159                 if (int_up == 0) /* all the non-LOOPBACK interfaces are DOWN */
 160                         return (-1);
 161         }
 162 #endif /* SIOCGIFNUM */
 163
 164
 165         /*
 166          * for the benefit of hidden NIS domains, we use the same procedure
 167          * as sendmail: convert leading + to dot, then drop to first dot
 168          */
 169         getdomainname(buf, BUFSIZ);
 170         if (buf[0] == '+')
 171         buf[0] = '.';
 172 #ifdef SYSV
 173         cp = strchr(buf, (int)'.');
 174 #else
 175         cp = index(buf, '.');
 176 #endif
 177         if (cp == NULL)
 178                 strcpy(_res.defdname, buf);
 179         else
 180                 strcpy(_res.defdname, cp+1);
 181
 182         /* Allow user to override the local domain definition */
 183         if ((cp = getenv("LOCALDOMAIN")) != NULL) {
 184         (void) strncpy(_res.defdname, cp, sizeof (_res.defdname));
 185         haveenv++;
 186         }
 187
 188         if ((fp = fopen(_PATH_RESCONF, "r")) != NULL) {
 189         /* read the config file */
 190         while (fgets(buf, sizeof (buf), fp) != NULL) {
 191             /* read default domain name */
 192             if (!strncmp(buf, "domain", sizeof ("domain") - 1)) {
 193                 if (haveenv)    /* skip if have from environ */
 194                             continue;
 195                 cp = buf + sizeof ("domain") - 1;
 196                 while (*cp == ' ' || *cp == '\t')
 197                     cp++;
 198                 if ((*cp == '\0') || (*cp == '\n'))
 199                     continue;
 200                 (void) strncpy(_res.defdname, cp, sizeof (_res.defdname) - 1);
 201 #ifdef SYSV
 202                 if ((cp = strchr(_res.defdname, (int)'\n')) != NULL)
 203 #else
 204                 if ((cp = index(_res.defdname, '\n')) != NULL)
 205 #endif
 206                     *cp = '\0';
 207                 havesearch = 0;
 208                 continue;
 209             }
 210             /* set search list */
 211             if (!strncmp(buf, "search", sizeof ("search") - 1)) {
 212                 if (haveenv)    /* skip if have from environ */
 213                     continue;
 214                 cp = buf + sizeof ("search") - 1;
 215                 while (*cp == ' ' || *cp == '\t')
 216                     cp++;
 217                 if ((*cp == '\0') || (*cp == '\n'))
 218                     continue;
 219                 (void) strncpy(_res.defdname, cp, sizeof (_res.defdname) - 1);
 220 #ifdef SYSV
 221                 if ((cp = strchr(_res.defdname, (int)'\n')) != NULL)
 222 #else
 223                 if ((cp = index(_res.defdname, '\n')) != NULL)
 224 #endif
 225                     *cp = '\0';
 226                 /*
 227                  * Set search list to be blank-separated strings
 228                  * on rest of line.
 229                  */
 230                 cp = _res.defdname;
 231                 pp = _res.dnsrch;
 232                 *pp++ = cp;
 233                 for (n = 0; *cp && pp < _res.dnsrch + MAXDNSRCH; cp++) {
 234                     if (*cp == ' ' || *cp == '\t') {
 235                         *cp = 0;
 236                         n = 1;
 237                     } else if (n) {
 238                         *pp++ = cp;
 239                         n = 0;
 240                     }
 241                 }
 242                 /* null terminate last domain if there are excess */
 243                 while (*cp != '\0' && *cp != ' ' && *cp != '\t')
 244                     cp++;
 245                 *cp = '\0';
 246                 *pp++ = 0;
 247                 havesearch = 1;
 248                 continue;
 249             }
 250             /* read nameservers to query */
 251             if (!strncmp(buf, "nameserver", sizeof ("nameserver") - 1) &&
 252                 (nserv < MAXNS)) {
 253                 cp = buf + sizeof ("nameserver") - 1;
 254                 while (*cp == ' ' || *cp == '\t')
 255                     cp++;
 256                 if ((*cp == '\0') || (*cp == '\n'))
 257                     continue;
 258                 if ((_res.nsaddr_list[nserv].sin_addr.s_addr =
 259                                 inet_addr(cp)) == (unsigned) -1) {
 260                     _res.nsaddr_list[n].sin_addr.s_addr = INADDR_ANY;
 261                     continue;
 262                 }
 263                 _res.nsaddr_list[nserv].sin_family = AF_INET;
 264                 _res.nsaddr_list[nserv].sin_port = htons(NAMESERVER_PORT);
 265                 nserv++;
 266                 continue;
 267             }
 268         }
 269         if (nserv > 1)
 270             _res.nscount = nserv;
 271         (void) fclose(fp);
 272         }
 273         if (_res.defdname[0] == 0) {
 274         if (gethostname(buf, sizeof (_res.defdname)) == 0 &&
 275 #ifdef SYSV
 276             (cp = strchr(buf, (int)'.')))
 277 #else
 278             (cp = index(buf, '.')))
 279 #endif
 280                 (void) strcpy(_res.defdname, cp + 1);
 281         }
 282
 283         /* find components of local domain that might be searched */
 284         if (havesearch == 0) {
 285         pp = _res.dnsrch;
 286         *pp++ = _res.defdname;
 287         for (cp = _res.defdname, n = 0; *cp; cp++)
 288             if (*cp == '.')
 289                 n++;
 290         cp = _res.defdname;
 291         for (; n >= LOCALDOMAINPARTS && pp < _res.dnsrch + MAXDFLSRCH; n--) {
 292 #ifdef SYSV
 293             cp = strchr(cp, (int)'.');
 294 #else
 295             cp = index(cp, '.');
 296 #endif
 297             *pp++ = ++cp;
 298         }
 299         *pp++ = 0;
 300         }
 301         _res.options |= RES_INIT;
 302         return (0);
 303 }