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res_init.c

/*
 * Copyright (c) 1985, 1989, 1993
 *    The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

/*
 * Portions Copyright (c) 1993 by Digital Equipment Corporation.
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies, and that
 * the name of Digital Equipment Corporation not be used in advertising or
 * publicity pertaining to distribution of the document or software without
 * specific, written prior permission.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND DIGITAL EQUIPMENT CORP. DISCLAIMS ALL
 * WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS.   IN NO EVENT SHALL DIGITAL EQUIPMENT
 * CORPORATION BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
 * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
 * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
 * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
 * SOFTWARE.
 */

/*
 * Portions Copyright (c) 1996-1999 by Internet Software Consortium.
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM DISCLAIMS
 * ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE
 * CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
 * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
 * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
 * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
 * SOFTWARE.
 */

#if defined(LIBC_SCCS) && !defined(lint)
static const char sccsid[] = "@(#)res_init.c    8.1 (Berkeley) 6/7/93";
static const char rcsid[] = "$BINDId: res_init.c,v 8.16 2000/05/09 07:10:12 vixie Exp $";
#endif /* LIBC_SCCS and not lint */

#include <sys/types.h>
#include <sys/param.h>
#include <sys/socket.h>
#include <sys/time.h>

#include <netinet/in.h>
#include <arpa/inet.h>
#include <arpa/nameser.h>

#include <ctype.h>
#include <resolv.h>
#include <stdio.h>
#include <stdio_ext.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

/* Options.  Should all be left alone. */
#define RESOLVSORT
#define RFC1535
/* #undef DEBUG */

static void res_setoptions (res_state, const char *, const char *)
     internal_function;

#ifdef RESOLVSORT
static const char sort_mask_chars[] = "/&";
#define ISSORTMASK(ch) (strchr(sort_mask_chars, ch) != NULL)
static u_int32_t net_mask __P((struct in_addr));
#endif

#if !defined(isascii)   /* XXX - could be a function */
# define isascii(c) (!(c & 0200))
#endif

/*
 * Resolver state default settings.
 */

/*
 * Set up default settings.  If the configuration file exist, the values
 * there will have precedence.  Otherwise, the server address is set to
 * INADDR_ANY and the default domain name comes from the gethostname().
 *
 * An interrim version of this code (BIND 4.9, pre-4.4BSD) used 127.0.0.1
 * rather than INADDR_ANY ("0.0.0.0") as the default name server address
 * since it was noted that INADDR_ANY actually meant ``the first interface
 * you "ifconfig"'d at boot time'' and if this was a SLIP or PPP interface,
 * it had to be "up" in order for you to reach your own name server.  It
 * was later decided that since the recommended practice is to always
 * install local static routes through 127.0.0.1 for all your network
 * interfaces, that we could solve this problem without a code change.
 *
 * The configuration file should always be used, since it is the only way
 * to specify a default domain.  If you are running a server on your local
 * machine, you should say "nameserver 0.0.0.0" or "nameserver 127.0.0.1"
 * in the configuration file.
 *
 * Return 0 if completes successfully, -1 on error
 */
int
res_ninit(res_state statp) {
      extern int __res_vinit(res_state, int);

      return (__res_vinit(statp, 0));
}
#ifdef _LIBC
libc_hidden_def (__res_ninit)
#endif

/* This function has to be reachable by res_data.c but not publically. */
int
__res_vinit(res_state statp, int preinit) {
      register FILE *fp;
      register char *cp, **pp;
      register int n;
      char buf[BUFSIZ];
      int nserv = 0;    /* number of nameserver records read from file */
#ifdef _LIBC
      int nservall = 0; /* number of NS records read, nserv IPv4 only */
#endif
      int haveenv = 0;
      int havesearch = 0;
#ifdef RESOLVSORT
      int nsort = 0;
      char *net;
#endif
#ifndef RFC1535
      int dots;
#endif

      if (!preinit) {
            statp->retrans = RES_TIMEOUT;
            statp->retry = RES_DFLRETRY;
            statp->options = RES_DEFAULT;
            statp->id = res_randomid();
      }

#ifdef USELOOPBACK
      statp->nsaddr.sin_addr = inet_makeaddr(IN_LOOPBACKNET, 1);
#else
      statp->nsaddr.sin_addr.s_addr = INADDR_ANY;
#endif
      statp->nsaddr.sin_family = AF_INET;
      statp->nsaddr.sin_port = htons(NAMESERVER_PORT);
      statp->nscount = 1;
      statp->ndots = 1;
      statp->pfcode = 0;
      statp->_vcsock = -1;
      statp->_flags = 0;
      statp->qhook = NULL;
      statp->rhook = NULL;
      statp->_u._ext.nsinit = 0;
      statp->_u._ext.nscount = 0;
#ifdef _LIBC
      statp->_u._ext.nscount6 = 0;
      for (n = 0; n < MAXNS; n++) {
            statp->_u._ext.nsaddrs[n] = NULL;
            statp->_u._ext.nsmap[n] = MAXNS;
      }
#endif

      /* Allow user to override the local domain definition */
      if ((cp = getenv("LOCALDOMAIN")) != NULL) {
            (void)strncpy(statp->defdname, cp, sizeof(statp->defdname) - 1);
            statp->defdname[sizeof(statp->defdname) - 1] = '\0';
            haveenv++;

            /*
             * Set search list to be blank-separated strings
             * from rest of env value.  Permits users of LOCALDOMAIN
             * to still have a search list, and anyone to set the
             * one that they want to use as an individual (even more
             * important now that the rfc1535 stuff restricts searches)
             */
            cp = statp->defdname;
            pp = statp->dnsrch;
            *pp++ = cp;
            for (n = 0; *cp && pp < statp->dnsrch + MAXDNSRCH; cp++) {
                  if (*cp == '\n')  /* silly backwards compat */
                        break;
                  else if (*cp == ' ' || *cp == '\t') {
                        *cp = 0;
                        n = 1;
                  } else if (n) {
                        *pp++ = cp;
                        n = 0;
                        havesearch = 1;
                  }
            }
            /* null terminate last domain if there are excess */
            while (*cp != '\0' && *cp != ' ' && *cp != '\t' && *cp != '\n')
                  cp++;
            *cp = '\0';
            *pp++ = 0;
      }

#define     MATCH(line, name) \
      (!strncmp(line, name, sizeof(name) - 1) && \
      (line[sizeof(name) - 1] == ' ' || \
       line[sizeof(name) - 1] == '\t'))

      if ((fp = fopen(_PATH_RESCONF, "r")) != NULL) {
            /* No threads use this stream.  */
            __fsetlocking (fp, FSETLOCKING_BYCALLER);
          /* read the config file */
          while (fgets_unlocked(buf, sizeof(buf), fp) != NULL) {
            /* skip comments */
            if (*buf == ';' || *buf == '#')
                  continue;
            /* read default domain name */
            if (MATCH(buf, "domain")) {
                if (haveenv)  /* skip if have from environ */
                      continue;
                cp = buf + sizeof("domain") - 1;
                while (*cp == ' ' || *cp == '\t')
                      cp++;
                if ((*cp == '\0') || (*cp == '\n'))
                      continue;
                strncpy(statp->defdname, cp, sizeof(statp->defdname) - 1);
                statp->defdname[sizeof(statp->defdname) - 1] = '\0';
                if ((cp = strpbrk(statp->defdname, " \t\n")) != NULL)
                      *cp = '\0';
                havesearch = 0;
                continue;
            }
            /* set search list */
            if (MATCH(buf, "search")) {
                if (haveenv)  /* skip if have from environ */
                      continue;
                cp = buf + sizeof("search") - 1;
                while (*cp == ' ' || *cp == '\t')
                      cp++;
                if ((*cp == '\0') || (*cp == '\n'))
                      continue;
                strncpy(statp->defdname, cp, sizeof(statp->defdname) - 1);
                statp->defdname[sizeof(statp->defdname) - 1] = '\0';
                if ((cp = strchr(statp->defdname, '\n')) != NULL)
                      *cp = '\0';
                /*
                 * Set search list to be blank-separated strings
                 * on rest of line.
                 */
                cp = statp->defdname;
                pp = statp->dnsrch;
                *pp++ = cp;
                for (n = 0; *cp && pp < statp->dnsrch + MAXDNSRCH; cp++) {
                      if (*cp == ' ' || *cp == '\t') {
                            *cp = 0;
                            n = 1;
                      } else if (n) {
                            *pp++ = cp;
                            n = 0;
                      }
                }
                /* null terminate last domain if there are excess */
                while (*cp != '\0' && *cp != ' ' && *cp != '\t')
                      cp++;
                *cp = '\0';
                *pp++ = 0;
                havesearch = 1;
                continue;
            }
            /* read nameservers to query */
#ifdef _LIBC
            if (MATCH(buf, "nameserver") && nservall < MAXNS) {
#else
            if (MATCH(buf, "nameserver") && nserv < MAXNS) {
#endif
                struct in_addr a;

                cp = buf + sizeof("nameserver") - 1;
                while (*cp == ' ' || *cp == '\t')
                  cp++;
                if ((*cp != '\0') && (*cp != '\n')
                  && __inet_aton(cp, &a)) {
                  statp->nsaddr_list[nserv].sin_addr = a;
                  statp->nsaddr_list[nserv].sin_family = AF_INET;
                  statp->nsaddr_list[nserv].sin_port =
                        htons(NAMESERVER_PORT);
                  nserv++;
#ifdef _LIBC
                  nservall++;
                    } else {
                        struct in6_addr a6;
                        char *el;

                        if ((el = strchr(cp, '\n')) != NULL)
                            *el = '\0';
                        if ((*cp != '\0') &&
                            (inet_pton(AF_INET6, cp, &a6) > 0)) {
                            struct sockaddr_in6 *sa6;

                            sa6 = malloc(sizeof(*sa6));
                            if (sa6 != NULL) {
                                sa6->sin6_addr = a6;
                                sa6->sin6_family = AF_INET6;
                                sa6->sin6_port = htons(NAMESERVER_PORT);
                        statp->_u._ext.nsaddrs[nservall] = sa6;
                        statp->_u._ext.nssocks[nservall] = -1;
                        statp->_u._ext.nsmap[nservall] = MAXNS + 1;
                                nservall++;
                            }
                        }
#endif
                }
                continue;
            }
#ifdef RESOLVSORT
            if (MATCH(buf, "sortlist")) {
                struct in_addr a;

                cp = buf + sizeof("sortlist") - 1;
                while (nsort < MAXRESOLVSORT) {
                  while (*cp == ' ' || *cp == '\t')
                      cp++;
                  if (*cp == '\0' || *cp == '\n' || *cp == ';')
                      break;
                  net = cp;
                  while (*cp && !ISSORTMASK(*cp) && *cp != ';' &&
                         isascii(*cp) && !isspace(*cp))
                        cp++;
                  n = *cp;
                  *cp = 0;
                  if (__inet_aton(net, &a)) {
                      statp->sort_list[nsort].addr = a;
                      if (ISSORTMASK(n)) {
                        *cp++ = n;
                        net = cp;
                        while (*cp && *cp != ';' &&
                              isascii(*cp) && !isspace(*cp))
                            cp++;
                        n = *cp;
                        *cp = 0;
                        if (__inet_aton(net, &a)) {
                            statp->sort_list[nsort].mask = a.s_addr;
                        } else {
                            statp->sort_list[nsort].mask =
                              net_mask(statp->sort_list[nsort].addr);
                        }
                      } else {
                        statp->sort_list[nsort].mask =
                            net_mask(statp->sort_list[nsort].addr);
                      }
                      nsort++;
                  }
                  *cp = n;
                }
                continue;
            }
#endif
            if (MATCH(buf, "options")) {
                res_setoptions(statp, buf + sizeof("options") - 1, "conf");
                continue;
            }
          }
          if (nserv > 1)
            statp->nscount = nserv;
#ifdef _LIBC
          if (nservall - nserv > 0)
            statp->_u._ext.nscount6 = nservall - nserv;
#endif
#ifdef RESOLVSORT
          statp->nsort = nsort;
#endif
          (void) fclose(fp);
      }
      if (statp->defdname[0] == 0 &&
          __gethostname(buf, sizeof(statp->defdname) - 1) == 0 &&
          (cp = strchr(buf, '.')) != NULL)
            strcpy(statp->defdname, cp + 1);

      /* find components of local domain that might be searched */
      if (havesearch == 0) {
            pp = statp->dnsrch;
            *pp++ = statp->defdname;
            *pp = NULL;

#ifndef RFC1535
            dots = 0;
            for (cp = statp->defdname; *cp; cp++)
                  dots += (*cp == '.');

            cp = statp->defdname;
            while (pp < statp->dnsrch + MAXDFLSRCH) {
                  if (dots < LOCALDOMAINPARTS)
                        break;
                  cp = __rawmemchr(cp, '.') + 1;    /* we know there is one */
                  *pp++ = cp;
                  dots--;
            }
            *pp = NULL;
#ifdef DEBUG
            if (statp->options & RES_DEBUG) {
                  printf(";; res_init()... default dnsrch list:\n");
                  for (pp = statp->dnsrch; *pp; pp++)
                        printf(";;\t%s\n", *pp);
                  printf(";;\t..END..\n");
            }
#endif
#endif /* !RFC1535 */
      }

      if ((cp = getenv("RES_OPTIONS")) != NULL)
            res_setoptions(statp, cp, "env");
      statp->options |= RES_INIT;
      return (0);
}

static void
internal_function
res_setoptions(res_state statp, const char *options, const char *source) {
      const char *cp = options;
      int i;

#ifdef DEBUG
      if (statp->options & RES_DEBUG)
            printf(";; res_setoptions(\"%s\", \"%s\")...\n",
                   options, source);
#endif
      while (*cp) {
            /* skip leading and inner runs of spaces */
            while (*cp == ' ' || *cp == '\t')
                  cp++;
            /* search for and process individual options */
            if (!strncmp(cp, "ndots:", sizeof("ndots:") - 1)) {
                  i = atoi(cp + sizeof("ndots:") - 1);
                  if (i <= RES_MAXNDOTS)
                        statp->ndots = i;
                  else
                        statp->ndots = RES_MAXNDOTS;
#ifdef DEBUG
                  if (statp->options & RES_DEBUG)
                        printf(";;\tndots=%d\n", statp->ndots);
#endif
            } else if (!strncmp(cp, "timeout:", sizeof("timeout:") - 1)) {
                  i = atoi(cp + sizeof("timeout:") - 1);
                  if (i <= RES_MAXRETRANS)
                        statp->retrans = i;
                  else
                        statp->retrans = RES_MAXRETRANS;
            } else if (!strncmp(cp, "attempts:", sizeof("attempts:") - 1)){
                  i = atoi(cp + sizeof("attempts:") - 1);
                  if (i <= RES_MAXRETRY)
                        statp->retry = i;
                  else
                        statp->retry = RES_MAXRETRY;
            } else if (!strncmp(cp, "debug", sizeof("debug") - 1)) {
#ifdef DEBUG
                  if (!(statp->options & RES_DEBUG)) {
                        printf(";; res_setoptions(\"%s\", \"%s\")..\n",
                               options, source);
                        statp->options |= RES_DEBUG;
                  }
                  printf(";;\tdebug\n");
#endif
            } else if (!strncmp(cp, "inet6", sizeof("inet6") - 1)) {
                  statp->options |= RES_USE_INET6;
            } else if (!strncmp(cp, "rotate", sizeof("rotate") - 1)) {
                  statp->options |= RES_ROTATE;
            } else if (!strncmp(cp, "no-check-names",
                            sizeof("no-check-names") - 1)) {
                  statp->options |= RES_NOCHECKNAME;
            } else {
                  /* XXX - print a warning here? */
            }
            /* skip to next run of spaces */
            while (*cp && *cp != ' ' && *cp != '\t')
                  cp++;
      }
}

#ifdef RESOLVSORT
/* XXX - should really support CIDR which means explicit masks always. */
static u_int32_t
net_mask(in)            /* XXX - should really use system's version of this */
      struct in_addr in;
{
      register u_int32_t i = ntohl(in.s_addr);

      if (IN_CLASSA(i))
            return (htonl(IN_CLASSA_NET));
      else if (IN_CLASSB(i))
            return (htonl(IN_CLASSB_NET));
      return (htonl(IN_CLASSC_NET));
}
#endif

u_int
res_randomid(void) {
      struct timeval now;

      __gettimeofday(&now, NULL);
      return (0xffff & (now.tv_sec ^ now.tv_usec ^ __getpid()));
}
#ifdef _LIBC
libc_hidden_def (__res_randomid)
#endif


/*
 * This routine is for closing the socket if a virtual circuit is used and
 * the program wants to close it.  This provides support for endhostent()
 * which expects to close the socket.
 *
 * This routine is not expected to be user visible.
 */
void
res_nclose(res_state statp) {
      int ns;

      if (statp->_vcsock >= 0) {
            (void) __close(statp->_vcsock);
            statp->_vcsock = -1;
            statp->_flags &= ~(RES_F_VC | RES_F_CONN);
      }
#ifdef _LIBC
      for (ns = 0; ns < MAXNS; ns++)
#else
      for (ns = 0; ns < statp->_u._ext.nscount; ns++)
#endif
            if (statp->_u._ext.nsaddrs[ns]
                && statp->_u._ext.nssocks[ns] != -1) {
                  (void) __close(statp->_u._ext.nssocks[ns]);
                  statp->_u._ext.nssocks[ns] = -1;
            }
      statp->_u._ext.nsinit = 0;
}
#ifdef _LIBC
libc_hidden_def (__res_nclose)
#endif

#ifdef _LIBC
# ifdef _LIBC_REENTRANT
/* This is called when a thread is exiting to free resources held in _res.  */
static void __attribute__ ((section ("__libc_thread_freeres_fn")))
res_thread_freeres (void)
{
  if (_res.nscount == 0)
    /* Never called res_ninit.  */
    return;

  __res_nclose (&_res);       /* Close any VC sockets.  */

  for (int ns = 0; ns < MAXNS; ns++)
    if (_res._u._ext.nsaddrs[ns] != NULL)
      {
      free (_res._u._ext.nsaddrs[ns]);
      _res._u._ext.nsaddrs[ns] = NULL;
      }
}
text_set_element (__libc_thread_subfreeres, res_thread_freeres);
text_set_element (__libc_subfreeres, res_thread_freeres);
# endif
#endif

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