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 2015 Gary Mills
  24  * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
  25  * Use is subject to license terms.
  26  */
  27
  28 /*      Copyright (c) 1984, 1986, 1987, 1988, 1989 AT&T */
  29 /*        All Rights Reserved   */
  30
  31 /*
  32  * University Copyright- Copyright (c) 1982, 1986, 1988
  33  * The Regents of the University of California
  34  * All Rights Reserved
  35  *
  36  * University Acknowledgment- Portions of this document are derived from
  37  * software developed by the University of California, Berkeley, and its
  38  * contributors.
  39  */
  40
  41 #include <sys/types.h>
  42 #include <sys/sockio.h>
  43 #include <sys/socket.h>
  44 #include <netinet/in.h>
  45 #include <stdio.h>
  46 #include <string.h>
  47 #include <stdlib.h>
  48 #include <unistd.h>
  49 #include <stropts.h>
  50 #include <arpa/nameser.h>
  51 #include <resolv.h>
  52
  53 #include <netinet/in.h>
  54 #include <net/if.h>
  55 #include <netinet/if_ether.h>
  56 #include <arpa/inet.h>
  57
  58 /*
  59  * Undocumented external function in libnsl
  60  */
  61 extern int
  62 getdomainname(char *, int);
  63
  64 #define MAXIFS  256
  65
  66 /*
  67  * Resolver state default settings
  68  */
  69
  70 struct state _res = {
  71         RES_TIMEOUT,            /* retransmition time interval */
  72         4,                              /* number of times to retransmit */
  73         RES_DEFAULT,            /* options flags */
  74         1,                              /* number of name servers */
  75 };
  76
  77 /*
  78  * Set up default settings.  If the configuration file exist, the values
  79  * there will have precedence.  Otherwise, the server address is set to
  80  * INADDR_LOOPBACK and the default domain name comes from the gethostname().
  81  * BUT if the NIS/RPC domain name is set, that is used if all else fails.
  82  *
  83  * The configuration file should only be used if you want to redefine your
  84  * domain or run without a server on your machine.
  85  *
  86  * Note the user can always override then domain name with the environment
  87  * variable LOCALDOMAIN which has absolute priority.
  88  *
  89  *
  90  * Return 0 if completes successfully, -1 on error
  91  */
  92 int
  93 res_init(void)
  94 {
  95         register FILE *fp;
  96         register char *cp, **pp;
  97         register int n;
  98         char buf[BUFSIZ];
  99         int nserv = 0;    /* number of nameserver records read from file */
 100         int haveenv = 0;
 101         int havesearch = 0;
 102
 103         _res.nsaddr.sin_addr.s_addr =  htonl(INADDR_LOOPBACK); /* INADDR_ANY */
 104         _res.nsaddr.sin_family = AF_INET;
 105         _res.nsaddr.sin_port = htons(NAMESERVER_PORT);
 106         _res.nscount = 1;
 107
 108 #ifdef SIOCGIFNUM
 109         {       int numifs, s, n, int_up;
 110                 struct ifconf ifc;
 111                 register struct ifreq *ifrp;
 112                 struct ifreq ifr;
 113                 unsigned bufsize;
 114                 unsigned int flags;
 115                 char *buf;
 116
 117                 if ((s = socket(AF_INET, SOCK_DGRAM, 0)) < 0) {
 118                         perror("socket");
 119                         return (-1);
 120                 }
 121                 if (ioctl(s, SIOCGIFNUM, (char *)&numifs) < 0) {
 122                         numifs = MAXIFS;
 123                 }
 124                 bufsize = numifs * sizeof (struct ifreq);
 125                 buf = (char *)malloc(bufsize);
 126                 if (buf == NULL) {
 127                         perror("out of memory");
 128                         (void) close(s);
 129                         return (-1);
 130                 }
 131                 ifc.ifc_len = bufsize;
 132                 ifc.ifc_buf = buf;
 133                 if (ioctl(s, SIOCGIFCONF, (char *)&ifc) < 0) {
 134                         perror("ifconfig: SIOCGIFCONF");
 135                         (void) close(s);
 136                         free(buf);
 137                         return (-1);
 138                 }
 139
 140                 int_up = 0;
 141                 ifrp = ifc.ifc_req;
 142                 for (n = ifc.ifc_len / sizeof (struct ifreq); n > 0;
 143                                                                 n--, ifrp++) {
 144                         (void) memset((void *) &ifr, 0, sizeof (ifr));
 145                         strncpy(ifr.ifr_name, ifrp->ifr_name,
 146                                                         sizeof (ifr.ifr_name));
 147                         if (ioctl(s, SIOCGIFFLAGS, (char *)&ifr) < 0) {
 148                                 perror("SIOCGIFFLAGS");
 149                                 (void) close(s);
 150                                 free(buf);
 151                                 return (-1);
 152                         }
 153                         flags = ifr.ifr_flags;
 154                         /* we are looking for a non-loopback interface */
 155                         if ((flags & IFF_UP) && ((flags & IFF_LOOPBACK) == 0))
 156                                 int_up = 1;
 157                 }
 158                 (void) close(s);
 159                 free(buf);
 160                 if (int_up == 0) /* all the non-LOOPBACK interfaces are DOWN */
 161                         return (-1);
 162         }
 163 #endif /* SIOCGIFNUM */
 164
 165
 166         /*
 167          * for the benefit of hidden NIS domains, we use the same procedure
 168          * as sendmail: convert leading + to dot, then drop to first dot
 169          */
 170         (void) getdomainname(buf, BUFSIZ);
 171         if (buf[0] == '+')
 172                 buf[0] = '.';
 173 #ifdef SYSV
 174         cp = strchr(buf, (int)'.');
 175 #else
 176         cp = index(buf, '.');
 177 #endif
 178         if (cp == NULL)
 179                 strcpy(_res.defdname, buf);
 180         else
 181                 strcpy(_res.defdname, cp+1);
 182
 183         /* Allow user to override the local domain definition */
 184         if ((cp = getenv("LOCALDOMAIN")) != NULL) {
 185         (void) strncpy(_res.defdname, cp, sizeof (_res.defdname));
 186         haveenv++;
 187         }
 188
 189         if ((fp = fopen(_PATH_RESCONF, "r")) != NULL) {
 190         /* read the config file */
 191         while (fgets(buf, sizeof (buf), fp) != NULL) {
 192             /* read default domain name */
 193             if (!strncmp(buf, "domain", sizeof ("domain") - 1)) {
 194                 if (haveenv)    /* skip if have from environ */
 195                             continue;
 196                 cp = buf + sizeof ("domain") - 1;
 197                 while (*cp == ' ' || *cp == '\t')
 198                     cp++;
 199                 if ((*cp == '\0') || (*cp == '\n'))
 200                     continue;
 201                 (void) strncpy(_res.defdname, cp, sizeof (_res.defdname) - 1);
 202 #ifdef SYSV
 203                 if ((cp = strchr(_res.defdname, (int)'\n')) != NULL)
 204 #else
 205                 if ((cp = index(_res.defdname, '\n')) != NULL)
 206 #endif
 207                     *cp = '\0';
 208                 havesearch = 0;
 209                 continue;
 210             }
 211             /* set search list */
 212             if (!strncmp(buf, "search", sizeof ("search") - 1)) {
 213                 if (haveenv)    /* skip if have from environ */
 214                     continue;
 215                 cp = buf + sizeof ("search") - 1;
 216                 while (*cp == ' ' || *cp == '\t')
 217                     cp++;
 218                 if ((*cp == '\0') || (*cp == '\n'))
 219                     continue;
 220                 (void) strncpy(_res.defdname, cp, sizeof (_res.defdname) - 1);
 221 #ifdef SYSV
 222                 if ((cp = strchr(_res.defdname, (int)'\n')) != NULL)
 223 #else
 224                 if ((cp = index(_res.defdname, '\n')) != NULL)
 225 #endif
 226                     *cp = '\0';
 227                 /*
 228                  * Set search list to be blank-separated strings
 229                  * on rest of line.
 230                  */
 231                 cp = _res.defdname;
 232                 pp = _res.dnsrch;
 233                 *pp++ = cp;
 234                 for (n = 0; *cp && pp < _res.dnsrch + MAXDNSRCH; cp++) {
 235                     if (*cp == ' ' || *cp == '\t') {
 236                         *cp = 0;
 237                         n = 1;
 238                     } else if (n) {
 239                         *pp++ = cp;
 240                         n = 0;
 241                     }
 242                 }
 243                 /* null terminate last domain if there are excess */
 244                 while (*cp != '\0' && *cp != ' ' && *cp != '\t')
 245                     cp++;
 246                 *cp = '\0';
 247                 *pp++ = 0;
 248                 havesearch = 1;
 249                 continue;
 250             }
 251             /* read nameservers to query */
 252             if (!strncmp(buf, "nameserver", sizeof ("nameserver") - 1) &&
 253                 (nserv < MAXNS)) {
 254                 cp = buf + sizeof ("nameserver") - 1;
 255                 while (*cp == ' ' || *cp == '\t')
 256                     cp++;
 257                 if ((*cp == '\0') || (*cp == '\n'))
 258                     continue;
 259                 if ((_res.nsaddr_list[nserv].sin_addr.s_addr =
 260                                 inet_addr(cp)) == (unsigned) -1) {
 261                     _res.nsaddr_list[n].sin_addr.s_addr = INADDR_ANY;
 262                     continue;
 263                 }
 264                 _res.nsaddr_list[nserv].sin_family = AF_INET;
 265                 _res.nsaddr_list[nserv].sin_port = htons(NAMESERVER_PORT);
 266                 nserv++;
 267                 continue;
 268             }
 269         }
 270         if (nserv > 1)
 271             _res.nscount = nserv;
 272         (void) fclose(fp);
 273         }
 274         if (_res.defdname[0] == 0) {
 275         if (gethostname(buf, sizeof (_res.defdname)) == 0 &&
 276 #ifdef SYSV
 277             (cp = strchr(buf, (int)'.')))
 278 #else
 279             (cp = index(buf, '.')))
 280 #endif
 281                 (void) strcpy(_res.defdname, cp + 1);
 282         }
 283
 284         /* find components of local domain that might be searched */
 285         if (havesearch == 0) {
 286         pp = _res.dnsrch;
 287         *pp++ = _res.defdname;
 288         for (cp = _res.defdname, n = 0; *cp; cp++)
 289             if (*cp == '.')
 290                 n++;
 291         cp = _res.defdname;
 292         for (; n >= LOCALDOMAINPARTS && pp < _res.dnsrch + MAXDFLSRCH; n--) {
 293 #ifdef SYSV
 294             cp = strchr(cp, (int)'.');
 295 #else
 296             cp = index(cp, '.');
 297 #endif
 298             *pp++ = ++cp;
 299         }
 300         *pp++ = 0;
 301         }
 302         _res.options |= RES_INIT;
 303         return (0);
 304 }