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

/*
**  Sendmail
**  Copyright (c) 1986  Eric P. Allman
**  Berkeley, California
**
**  Copyright (c) 1986 Regents of the University of California.
**  All rights reserved.  The Berkeley software License Agreement
**  specifies the terms and conditions for redistribution.
*/

#include "sendmail.h"

#ifndef MXDOMAIN
#ifndef lint
static char     SccsId[] = "@(#)domain.c        5.6 (Berkeley) %G% (no MXDOMAIN)";
#endif not lint
#else MXDOMAIN

#ifndef lint
static char     SccsId[] = "@(#)domain.c        5.6 (Berkeley) %G%";
#endif not lint

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

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

static char     hostbuf[BUFSIZ];
int             h_errno;
extern u_short  getshort();

getmxrr(host, mxhosts, maxmx, localhost)
       char *host, **mxhosts;
       int maxmx;
       char *localhost;
{

       HEADER *hp;
       char *eom, *bp, *cp;
       querybuf buf, answer;
       int n, n1, i, j, nmx, ancount, qdcount, buflen;
       int seenlocal;
       u_short prefer[BUFSIZ];
       u_short pref, localpref, type, class;

       n = res_mkquery(QUERY, host, C_IN, T_MX, (char *)NULL, 0, NULL,
               (char *)&buf, sizeof(buf));
       if (n < 0) {
#ifdef DEBUG
               if (tTd(8, 1) || _res.options & RES_DEBUG)
                       printf("res_mkquery failed\n");
#endif
               h_errno = NO_RECOVERY;
               return(-2);
       }
       n = res_send((char *)&buf, n, (char *)&answer, sizeof(answer));
       if (n < 0) {
#ifdef DEBUG
               if (tTd(8, 1) || _res.options & RES_DEBUG)
                       printf("res_send failed\n");
#endif
               h_errno = TRY_AGAIN;
               return (-1);
       }
       eom = (char *)&answer + n;
       /*
        * find first satisfactory answer
        */
       hp = (HEADER *) &answer;
       ancount = ntohs(hp->ancount);
       qdcount = ntohs(hp->qdcount);
       if (hp->rcode != NOERROR || ancount == 0) {
#ifdef DEBUG
               if (tTd(8, 1) || _res.options & RES_DEBUG)
                       printf("rcode = %d, ancount=%d\n", hp->rcode, ancount);
#endif
               switch (hp->rcode) {
                       case NXDOMAIN:
                               /* Check if it's an authoritive answer */
                               if (hp->aa) {
                                       h_errno = HOST_NOT_FOUND;
                                       return(-3);
                               } else {
                                       h_errno = TRY_AGAIN;
                                       return(-1);
                               }
                       case SERVFAIL:
                               h_errno = TRY_AGAIN;
                               return(-1);
#ifdef OLDJEEVES
                       /*
                        * Jeeves (TOPS-20 server) still does not
                        * support MX records.  For the time being,
                        * we must accept FORMERRs as the same as
                        * NOERROR.
                        */
                       case FORMERR:
#endif OLDJEEVES
                       case NOERROR:
                               (void) strcpy(hostbuf, host);
                               mxhosts[0] = hostbuf;
                               return(1);
#ifndef OLDJEEVES
                       case FORMERR:
#endif OLDJEEVES
                       case NOTIMP:
                       case REFUSED:
                               h_errno = NO_RECOVERY;
                               return(-2);
               }
               return (-1);
       }
       bp = hostbuf;
       nmx = 0;
       seenlocal = 0;
       buflen = sizeof(hostbuf);
       cp = (char *)&answer + sizeof(HEADER);
       if (qdcount) {
               cp += dn_skip(cp) + QFIXEDSZ;
               while (--qdcount > 0)
                       cp += dn_skip(cp) + QFIXEDSZ;
       }
       while (--ancount >= 0 && cp < eom && nmx < maxmx) {
               if ((n = dn_expand((char *)&answer, eom, cp, bp, buflen)) < 0)
                       break;
               cp += n;
               type = getshort(cp);
               cp += sizeof(u_short);
               /*
               class = getshort(cp);
               */
               cp += sizeof(u_short) + sizeof(u_long);
               n = getshort(cp);
               cp += sizeof(u_short);
               if (type != T_MX)  {
#ifdef DEBUG
                       if (tTd(8, 1) || _res.options & RES_DEBUG)
                               printf("unexpected answer type %d, size %d\n",
                                       type, n);
#endif
                       cp += n;
                       continue;
               }
               pref = getshort(cp);
               cp += sizeof(u_short);
               if ((n = dn_expand((char *)&answer, eom, cp, bp, buflen)) < 0)
                       break;
               cp += n;
               if (sameword(bp, localhost))
               {
                       seenlocal = 1;
                       localpref = pref;
                       continue;
               }
               prefer[nmx] = pref;
               mxhosts[nmx++] = bp;
               n1 = strlen(bp)+1;
               bp += n1;
               buflen -= n1;
       }
       if (nmx == 0) {
               (void) strcpy(hostbuf, host);
               mxhosts[0] = hostbuf;
               return(1);
       }
       /* sort the records */
       for (i = 0; i < nmx; i++) {
               for (j = i + 1; j < nmx; j++) {
                       if (prefer[i] > prefer[j]) {
                               int temp;
                               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))
               {
                       nmx = i;
                       /*
                        * We are the first MX, might as well try delivering
                        * since nobody is supposed to have more info.
                        */
                       if (nmx == 0)
                       {
                               (void) strcpy(hostbuf, host);
                               mxhosts[0] = hostbuf;
                               return(1);
                       }
                       break;
               }
       }
       return(nmx);
}


getcanonname(host, hbsize)
       char *host;
       int hbsize;
{

       HEADER *hp;
       char *eom, *cp;
       querybuf buf, answer;
       int n, ancount, qdcount;
       u_short type;
       char nbuf[BUFSIZ];
       int first;

       n = res_mkquery(QUERY, host, C_IN, T_ANY, (char *)NULL, 0, NULL,
               (char *)&buf, sizeof(buf));
       if (n < 0) {
#ifdef DEBUG
               if (tTd(8, 1) || _res.options & RES_DEBUG)
                       printf("res_mkquery failed\n");
#endif
               h_errno = NO_RECOVERY;
               return;
       }
       n = res_send((char *)&buf, n, (char *)&answer, sizeof(answer));
       if (n < 0) {
#ifdef DEBUG
               if (tTd(8, 1) || _res.options & RES_DEBUG)
                       printf("res_send failed\n");
#endif
               h_errno = TRY_AGAIN;
               return;
       }
       eom = (char *)&answer + n;
       /*
        * find first satisfactory answer
        */
       hp = (HEADER *) &answer;
       ancount = ntohs(hp->ancount);
       qdcount = ntohs(hp->qdcount);
       /*
        * We don't care about errors here, only if we got an answer
        */
       if (ancount == 0) {
#ifdef DEBUG
               if (tTd(8, 1) || _res.options & RES_DEBUG)
                       printf("rcode = %d, ancount=%d\n", hp->rcode, ancount);
#endif
               return;
       }
       cp = (char *)&answer + sizeof(HEADER);
       if (qdcount) {
               cp += dn_skip(cp) + QFIXEDSZ;
               while (--qdcount > 0)
                       cp += dn_skip(cp) + QFIXEDSZ;
       }
       first = 1;
       while (--ancount >= 0 && cp < eom) {
               if ((n = dn_expand((char *)&answer, eom, cp, nbuf,
                   sizeof(nbuf))) < 0)
                       break;
               if (first) {
                       (void)strncpy(host, nbuf, hbsize);
                       host[hbsize - 1] = '\0';
                       first = 0;
               }
               cp += n;
               type = getshort(cp);
               cp += sizeof(u_short);
               cp += sizeof(u_short) + sizeof(u_long);
               n = getshort(cp);
               cp += sizeof(u_short);
               if (type == T_CNAME)  {
                       /*
                        * Assume that only one cname will be found.  More
                        * than one is undefined.
                        */
                       if ((n = dn_expand((char *)&answer, eom, cp, nbuf,
                           sizeof(nbuf))) < 0)
                               break;
                       (void)strncpy(host, nbuf, hbsize);
                       host[hbsize - 1] = '\0';
                       getcanonname(host, hbsize);
                       break;
               }
               cp += n;
       }
       return;
}

u_short
getshort(msgp)
       char *msgp;
{
       register u_char *p = (u_char *) msgp;
       register int u;

       u = *p++ << 8;
       return ((u_short)(u | *p));
}

#endif MXDOMAIN