BSD 4_3_Reno release

[unix-history] / usr / src / usr.sbin / sendmail / src / domain.c

/*
* Copyright (c) 1986 Eric P. Allman
* Copyright (c) 1988 Regents of the University of California.
* All rights reserved.
*
* Redistribution and use in source and binary forms are permitted provided
* that: (1) source distributions retain this entire copyright notice and
* comment, and (2) distributions including binaries display the following
* acknowledgement:  ``This product includes software developed by the
* University of California, Berkeley and its contributors'' in the
* documentation or other materials provided with the distribution and in
* all advertising materials mentioning features or use of this software.
* 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 ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
* WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
*/

#include "sendmail.h"

#ifndef lint
#ifdef NAMED_BIND
static char sccsid[] = "@(#)domain.c    5.22 (Berkeley) 6/1/90 (with name server)";
#else
static char sccsid[] = "@(#)domain.c    5.22 (Berkeley) 6/1/90 (without name server)";
#endif
#endif /* not lint */

#ifdef NAMED_BIND

#include <sys/param.h>
#include <errno.h>
#include <arpa/nameser.h>
#include <resolv.h>
#include <netdb.h>

typedef union {
       HEADER qb1;
       char qb2[PACKETSZ];
} querybuf;

static char hostbuf[MAXMXHOSTS*PACKETSZ];

getmxrr(host, mxhosts, localhost, rcode)
       char *host, **mxhosts, *localhost;
       int *rcode;
{
       extern int h_errno;
       register u_char *eom, *cp;
       register int i, j, n, nmx;
       register char *bp;
       HEADER *hp;
       querybuf answer;
       int ancount, qdcount, buflen, seenlocal;
       u_short pref, localpref, type, prefer[MAXMXHOSTS];

       errno = 0;
       n = res_search(host, C_IN, T_MX, (char *)&answer, sizeof(answer));
       if (n < 0)
       {
               if (tTd(8, 1))
                       printf("getmxrr: res_search failed (errno=%d, h_errno=%d)\n",
                           errno, h_errno);
               switch (h_errno)
               {
                 case NO_DATA:
                 case NO_RECOVERY:
                       /* no MX data on this host */
                       goto punt;

                 case HOST_NOT_FOUND:
                       /* the host just doesn't exist */
                       *rcode = EX_NOHOST;
                       break;

                 case TRY_AGAIN:
                       /* couldn't connect to the name server */
                       if (!UseNameServer && errno == ECONNREFUSED)
                               goto punt;

                       /* it might come up later; better queue it up */
                       *rcode = EX_TEMPFAIL;
                       break;
               }

               /* irreconcilable differences */
               return (-1);
       }

       /* find first satisfactory answer */
       hp = (HEADER *)&answer;
       cp = (u_char *)&answer + sizeof(HEADER);
       eom = (u_char *)&answer + n;
       for (qdcount = ntohs(hp->qdcount); qdcount--; cp += n + QFIXEDSZ)
               if ((n = dn_skipname(cp, eom)) < 0)
                       goto punt;
       nmx = 0;
       seenlocal = 0;
       buflen = sizeof(hostbuf);
       bp = hostbuf;
       ancount = ntohs(hp->ancount);
       while (--ancount >= 0 && cp < eom && nmx < MAXMXHOSTS) {
               if ((n = dn_expand((char *)&answer, eom, cp, bp, buflen)) < 0)
                       break;
               cp += n;
               GETSHORT(type, cp);
               cp += sizeof(u_short) + sizeof(u_long);
               GETSHORT(n, cp);
               if (type != T_MX)  {
                       if (tTd(8, 1) || _res.options & RES_DEBUG)
                               printf("unexpected answer type %d, size %d\n",
                                   type, n);
                       cp += n;
                       continue;
               }
               GETSHORT(pref, cp);
               if ((n = dn_expand((char *)&answer, eom, cp, bp, buflen)) < 0)
                       break;
               cp += n;
               if (!strcasecmp(bp, localhost)) {
                       if (seenlocal == 0 || pref < localpref)
                               localpref = pref;
                       seenlocal = 1;
                       continue;
               }
               prefer[nmx] = pref;
               mxhosts[nmx++] = bp;
               n = strlen(bp) + 1;
               bp += n;
               buflen -= n;
       }
       if (nmx == 0) {
punt:           mxhosts[0] = strcpy(hostbuf, host);
               return(1);
       }

       /* sort the records */
       for (i = 0; i < nmx; i++) {
               for (j = i + 1; j < nmx; j++) {
                       if (prefer[i] > prefer[j] ||
                           (prefer[i] == prefer[j] && rand() % 1 == 0)) {
                               register int temp;
                               register char *temp1;

                               temp = prefer[i];
                               prefer[i] = prefer[j];
                               prefer[j] = temp;
                               temp1 = mxhosts[i];
                               mxhosts[i] = mxhosts[j];
                               mxhosts[j] = temp1;
                       }
               }
               if (seenlocal && prefer[i] >= localpref) {
                       /*
                        * truncate higher pref part of list; if we're
                        * the best choice left, we should have realized
                        * awhile ago that this was a local delivery.
                        */
                       if (i == 0) {
                               *rcode = EX_CONFIG;
                               return(-1);
                       }
                       nmx = i;
                       break;
               }
       }
       return(nmx);
}

getcanonname(host, hbsize)
       char *host;
       int hbsize;
{
       extern int h_errno;
       register u_char *eom, *cp;
       register int n; 
       HEADER *hp;
       querybuf answer;
       u_short type;
       int first, ancount, qdcount, loopcnt;
       char nbuf[PACKETSZ];

       loopcnt = 0;
loop:
       /*
        * Use query type of ANY if possible (NO_WILDCARD_MX), which will
        * find types CNAME, A, and MX, and will cause all existing records
        * to be cached by our local server.  If there is (might be) a
        * wildcard MX record in the local domain or its parents that are
        * searched, we can't use ANY; it would cause fully-qualified names
        * to match as names in a local domain.
        */
# ifdef NO_WILDCARD_MX
       n = res_search(host, C_IN, T_ANY, (char *)&answer, sizeof(answer));
# else
       n = res_search(host, C_IN, T_CNAME, (char *)&answer, sizeof(answer));
# endif
       if (n < 0) {
               if (tTd(8, 1))
                       printf("getcanonname:  res_search failed (errno=%d, h_errno=%d)\n",
                           errno, h_errno);
               return;
       }

       /* find first satisfactory answer */
       hp = (HEADER *)&answer;
       ancount = ntohs(hp->ancount);

       /* we don't care about errors here, only if we got an answer */
       if (ancount == 0) {
               if (tTd(8, 1))
                       printf("rcode = %d, ancount=%d\n", hp->rcode, ancount);
               return;
       }
       cp = (u_char *)&answer + sizeof(HEADER);
       eom = (u_char *)&answer + n;
       for (qdcount = ntohs(hp->qdcount); qdcount--; cp += n + QFIXEDSZ)
               if ((n = dn_skipname(cp, eom)) < 0)
                       return;

       /*
        * just in case someone puts a CNAME record after another record,
        * check all records for CNAME; otherwise, just take the first
        * name found.
        */
       for (first = 1; --ancount >= 0 && cp < eom; cp += n) {
               if ((n = dn_expand((char *)&answer, eom, cp, nbuf,
                   sizeof(nbuf))) < 0)
                       break;
               if (first) {                    /* XXX */
                       (void)strncpy(host, nbuf, hbsize);
                       host[hbsize - 1] = '\0';
                       first = 0;
               }
               cp += n;
               GETSHORT(type, cp);
               cp += sizeof(u_short) + sizeof(u_long);
               GETSHORT(n, cp);
               if (type == T_CNAME)  {
                       /*
                        * assume that only one cname will be found.  More
                        * than one is undefined.  Copy so that if dn_expand
                        * fails, `host' is still okay.
                        */
                       if ((n = dn_expand((char *)&answer, eom, cp, nbuf,
                           sizeof(nbuf))) < 0)
                               break;
                       (void)strncpy(host, nbuf, hbsize); /* XXX */
                       host[hbsize - 1] = '\0';
                       if (++loopcnt > 8)      /* never be more than 1 */
                               return;
                       goto loop;
               }
       }
}

#else /* not NAMED_BIND */

#include <netdb.h>

getcanonname(host, hbsize)
       char *host;
       int hbsize;
{
       struct hostent *hp;

       hp = gethostbyname(host);
       if (hp == NULL)
               return;

       if (strlen(hp->h_name) >= hbsize)
               return;

       (void) strcpy(host, hp->h_name);
}

#endif /* not NAMED_BIND */