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have DNS return what matched on a T_CNAME query
[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.
*
* %sccs.include.redist.c%
*/
#include "sendmail.h"
#ifndef lint
#ifdef NAMED_BIND
static char sccsid[] = "@(#)domain.c 5.30 (Berkeley) %G% (with name server)";
#else
static char sccsid[] = "@(#)domain.c 5.30 (Berkeley) %G% (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((u_char *)&answer,
eom, cp, (u_char *)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((u_char *)&answer,
eom, cp, (u_char *)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);
}
/*
* Use query type of ANY if possible (NoWildcardMX), 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.
*/
bool
getcanonname(host, hbsize)
char *host;
int hbsize;
{
extern int h_errno;
register u_char *eom, *ap;
register char *cp;
register int n;
HEADER *hp;
querybuf answer;
int first, ancount, qdcount, loopcnt;
int ret;
int qtype = NoWildcardMX ? T_ANY : T_CNAME;
char **domain;
bool rval;
int type;
char nbuf[PACKETSZ];
extern char *__hostalias();
if (tTd(8, 2))
printf("getcanonname(%s)\n", host);
if ((_res.options & RES_INIT) == 0 && res_init() == -1)
return (FALSE);
loopcnt = 0;
rval = FALSE;
loop:
for (cp = host, n = 0; *cp; cp++)
if (*cp == '.')
n++;
if (n > 0 && *--cp == '.')
{
cp = host;
n = -1;
}
else if (n == 0 && (cp = __hostalias(host)))
n = -1;
/*
* We do at least one level of search if
* - there is no dot and RES_DEFNAME is set, or
* - there is at least one dot, there is no trailing dot,
* and RES_DNSRCH is set.
*/
ret = -1;
if ((n == 0 && _res.options & RES_DEFNAMES) ||
(n > 0 && *--cp != '.' && _res.options & RES_DNSRCH))
{
for (domain = _res.dnsrch; *domain; domain++)
{
(void) sprintf(nbuf, "%.*s.%.*s",
MAXDNAME, host, MAXDNAME, *domain);
if (tTd(8, 5))
printf("getcanonname: trying %s\n", nbuf);
ret = res_query(nbuf, C_IN, qtype, &answer, sizeof(answer));
if (ret > 0)
{
if (tTd(8, 8))
printf("\tYES\n");
cp = nbuf;
break;
}
else if (tTd(8, 8))
printf("\tNO: h_errno=%d\n", h_errno);
/*
* If no server present, give up.
* If name isn't found in this domain,
* keep trying higher domains in the search list
* (if that's enabled).
* On a NO_DATA error, keep trying, otherwise
* a wildcard entry of another type could keep us
* from finding this entry higher in the domain.
* If we get some other error (negative answer or
* server failure), then stop searching up,
* but try the input name below in case it's fully-qualified.
*/
if (errno == ECONNREFUSED) {
h_errno = TRY_AGAIN;
return rval;
}
if (h_errno == NO_DATA)
{
ret = 0;
cp = nbuf;
break;
}
if ((h_errno != HOST_NOT_FOUND) ||
(_res.options & RES_DNSRCH) == 0)
return rval;
}
}
if (ret < 0)
{
cp = host;
if (tTd(8, 5))
printf("getcanonname: trying %s\n", cp);
ret = res_query(cp, C_IN, qtype, &answer, sizeof(answer));
if (ret > 0)
{
if (tTd(8, 8))
printf("\tYES\n");
}
else
{
if (tTd(8, 8))
printf("\tNO: h_errno=%d\n", h_errno);
return rval;
}
}
/* find first satisfactory answer */
hp = (HEADER *)&answer;
ancount = ntohs(hp->ancount);
if (tTd(8, 3))
printf("rcode = %d, ancount=%d, qdcount=%d\n",
hp->rcode, ancount, ntohs(hp->qdcount));
/* we don't care about errors here, only if we got an answer */
if (ancount == 0)
{
strncpy(host, cp, hbsize);
host[hbsize - 1] = '\0';
return (TRUE);
}
ap = (u_char *)&answer + sizeof(HEADER);
eom = (u_char *)&answer + ret;
for (qdcount = ntohs(hp->qdcount); qdcount--; ap += ret + QFIXEDSZ)
{
if ((ret = dn_skipname(ap, eom)) < 0)
{
if (tTd(8, 20))
printf("qdcount failure (%d)\n",
ntohs(hp->qdcount));
return rval; /* ???XXX??? */
}
}
/*
* 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 && ap < eom; ap += ret)
{
if ((ret = dn_expand((u_char *)&answer,
eom, ap, (u_char *)nbuf, sizeof(nbuf))) < 0)
break;
if (first) { /* XXX */
(void)strncpy(host, nbuf, hbsize);
host[hbsize - 1] = '\0';
first = 0;
rval = TRUE;
}
ap += ret;
GETSHORT(type, ap);
ap += sizeof(u_short) + sizeof(u_long);
GETSHORT(ret, ap);
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 ((ret = dn_expand((u_char *)&answer,
eom, ap, (u_char *)nbuf, sizeof(nbuf))) < 0)
break;
(void)strncpy(host, nbuf, hbsize); /* XXX */
host[hbsize - 1] = '\0';
if (++loopcnt > 8) /* never be more than 1 */
return FALSE;
rval = TRUE;
goto loop;
}
}
return rval; /* ???XXX??? */
}
#else /* not NAMED_BIND */
#include <netdb.h>
bool
getcanonname(host, hbsize)
char *host;
int hbsize;
{
struct hostent *hp;
hp = gethostbyname(host);
if (hp == NULL)
return (FALSE);
if (strlen(hp->h_name) >= hbsize)
return (FALSE);
(void) strcpy(host, hp->h_name);
return (TRUE);
}
#endif /* not NAMED_BIND */
Continuous source code history from original PDP-7 UNIX to FreeBSD 2, the first fully unencumbered FreeBSD release.