Begin implementing SPF support

git-svn-id: file:///svnroot/mailfromd/trunk@1250 7a8a7f39-df28-0410-adc6-e0d955640f24

14 files changed, 1838 insertions, 591 deletions

diff --git a/ChangeLog b/ChangeLog
index af64c1e8..0eaa275f 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,18 @@
+2007-02-17  Sergey Poznyakoff  <gray@gnu.org.ua>
+
+	* src/spf.c, src/spf.h: Templates for SPF support
+	* src/bi_spf.m4: Interface definitions for SPF support
+	* src/dns.c: Move generic DNS calls to dnsbase.c. Retain only
+	interface calls.
+	* src/dnsbase.c, src/dns.h: Generic DNS support
+
+	* src/mailfrom.h: Move generic DNS declarations to dns.h
+	* src/engine.c, src/bi_dns.m4, src/prog.c: Rename freemx to
+	dns_freemx
+	* src/main.c: Fix warning message wording
+	* src/Makefile.am: Add new sources
+	* bootstrap (MODLIST): Add memrchr
+
 2007-02-11  Sergey Poznyakoff  <gray@gnu.org.ua>
 
 	* gacopyz/trans.awk: Always quote /dev/stderr
diff --git a/bootstrap b/bootstrap
index 965652ae..ed5a5214 100644
--- a/bootstrap
+++ b/bootstrap
@@ -2,6 +2,7 @@
 MODLIST="argp\
  fprintftime\
  malloc\
+ memrchr\
  obstack\
  realloc\
  regex\
diff --git a/src/Makefile.am b/src/Makefile.am
index f5dbd509..7bd5c5c6 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -27,6 +27,7 @@ M4_FILES=\
  bi_mail.m4\
  bi_poll.m4\
  bi_sa.m4\
+ bi_spf.m4\
  bi_string.m4\
  bi_system.m4\
  bi_other.m4\
@@ -37,6 +38,7 @@ mailfromd_SOURCES = \
  dnscache.c\
  db.c\
  dns.c\
+ dnsbase.c\
  engine.c\
  gram.y\
  lex.l\
@@ -47,11 +49,12 @@ mailfromd_SOURCES = \
  optab.h\
  prog.c\
  prog.h\
+ spf.c\
  symtab.c\
  rate.c\
  $(M4_FILES:.m4=.c)
 
-noinst_HEADERS = mailfrom.h mu_dbm.h builtin.h
+noinst_HEADERS = mailfrom.h mu_dbm.h builtin.h dns.h
 EXTRA_DIST = gram.h snarf.m4 init.m4 $(M4_FILES) builtin.h builtin.def mf-status.mfi status.mfi mfstat.awk status.mfh optab.opc optab.oph opcode.awk opcodes
 BUILT_SOURCES=$(M4_FILES:.m4=.c) builtin.h mf-status.c optab.c optab.h
 
diff --git a/src/bi_dns.m4 b/src/bi_dns.m4
index 4fc2bcf6..2fa8e393 100644
--- a/src/bi_dns.m4
+++ b/src/bi_dns.m4
@@ -59,7 +59,7 @@ MF_DEFUN(hasmx, NUMBER, STRING string)
 		if (env_catch(env, mxstat) == 0)
 			return;
 	} else
-		freemx(mxbuf);
+		dns_freemx(mxbuf);
 
 	MF_RETURN(mxstat == mf_success);
 }
@@ -118,7 +118,7 @@ MF_DEFUN(ismx, NUMBER, STRING domain, STRING ipstr)
 				break;
 			}
 		}
-		freemx(mxbuf);
+		dns_freemx(mxbuf);
 	}
 	MF_RETURN(rc);
 }
diff --git a/src/bi_spf.m4 b/src/bi_spf.m4
new file mode 100644
index 00000000..f8864a51
--- /dev/null
+++ b/src/bi_spf.m4
@@ -0,0 +1,48 @@
+/* This file is part of mailfromd.             -*- c -*-
+   Copyright (C) 2007 Sergey Poznyakoff
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 2, or (at your option)
+   any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, write to the Free Software
+   Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
+   MA 02110-1301 USA */
+
+#include "spf.h"
+
+/* Function for testing SPF check_host. Does nothing useful so far. */
+MF_DEFUN(spf_check_host, NUMBER, STRING ip, STRING domain, STRING sender,
+	 STRING helo_domain, STRING my_domain)
+{
+	spf_result res;
+
+	res = spf_check_host(ip, domain, sender,
+			     helo_domain,
+			     my_domain);
+	MF_RETURN(res);
+}
+END
+
+/* Function for testing SPF check_host. Does nothing useful so far. */
+MF_DEFUN(spf_test_record, NUMBER, STRING record,
+	 STRING ip, STRING domain, STRING sender,
+	 STRING helo_domain, STRING my_domain)
+{
+	spf_result res;
+
+	res = spf_test_record(record,
+			      ip, domain, sender,
+			      helo_domain, my_domain);
+	MF_RETURN(res);
+}
+END
+
+MF_INIT
diff --git a/src/dns.c b/src/dns.c
index 8fc17868..7f820e91 100644
--- a/src/dns.c
+++ b/src/dns.c
@@ -30,197 +30,10 @@
 
 #include "mailfrom.h"
 
-struct mx_buffer {
-	unsigned pref;
-	char *name;
-};
-
-static int
-comp_pref(const void *a, const void *b)
-{
-	const struct mx_buffer *ma = a, *mb = b;
-	if (ma->pref > mb->pref)
-		return 1;
-	else if (ma->pref < mb->pref)
-		return -1;
-	return 0;
-}
-
-/* Obtain MX records for domain name HOST. Return them in mxbuf, sorted by
-   preference in ascending order.
-   Notice that we *have* to use old BIND-4-style method, since glibc folks
-   in their incredible wiseness have not exported new interface functions
-   from libresolve.so. The only way to access them would be to link with
-   -lresolve statically.
-   
-   Let's hope that someday this stupidity will change. */
-   
-static mf_status
-_getmx(char *host, char *answer, size_t answer_size, mxbuf_t mxbuf,
-       size_t *pcount, unsigned long *pttl)
-{
-	int i, n, nmx;
-	struct mx_buffer mx_buffer[MAXMXCOUNT];
-	HEADER *hp;
-	unsigned char *eom, *cp;
-	unsigned short qdcount, ancount;
-	struct __res_state stat;
-
-	debug1(80,"Getting MX records for %s", host);
-	memset((void *)&stat, 0, sizeof(struct __res_state));
-	res_ninit(&stat);
-	n = res_nquery (&stat, host, C_IN, T_MX, answer, answer_size);
-	res_nclose(&stat);
-	if (n < 0) {
-		debug2(10, "res_nquery failed (errno=%s, h_errno=%d)",
-			   mu_strerror(errno), h_errno);
-		switch (h_errno) {
-		case NO_DATA:
-		case NO_RECOVERY:
-		case HOST_NOT_FOUND:
-			return mf_not_found;
-
-		case TRY_AGAIN:
-		case -1:
-			return mf_temp_failure;
-
-		default:
-			mu_error("res_nquery(%s) failed with unexpected h_errno %d",
-				 host, h_errno);
-			return mf_failure;
-		}
-	}
-
-	if (n > answer_size)
-		n = answer_size;
-
-	hp = (HEADER*)answer;
-	cp = (unsigned char *) answer + HFIXEDSZ;
-	eom = (unsigned char *) answer + n;
-	
-	/* Skip query part */
-	for (qdcount = ntohs((unsigned short)hp->qdcount);
-	     qdcount--;
-	     cp += n + QFIXEDSZ) {
-		if ((n = dn_skipname(cp, eom)) < 0)
-			return mf_failure;
-	}
-
-	ancount = ntohs((unsigned short)hp->ancount);
-
-	/* Collect MX records */
-	for (i = nmx = 0; i < ancount; i++) {
-		unsigned short pref, type;
-		char tname[NS_MAXDNAME];
-		unsigned long ttl;
-		
-		if ((n = dn_expand((unsigned char *)answer,
-				   eom, cp, tname, sizeof tname)) < 0)
-			break;
-		cp += n;
-		GETSHORT(type, cp);
-		cp += INT16SZ;
-		GETLONG(ttl, cp);
-		if (*pttl > ttl)
-			*pttl = ttl;
-		GETSHORT(n, cp);
-		if (type != T_MX) {
-			debug2(90,"unexpected answer type %d, size %d\n",
-				   type, n);
-			cp += n;
-			continue;
-		}
-		GETSHORT(pref, cp);
-		if ((n = dn_expand((u_char *)answer, eom, cp,
-				   tname, sizeof tname)) < 0)
-			break;
-		cp += n;
-		mx_buffer[nmx].pref = pref;
-		mx_buffer[nmx].name = strdup(tname);
-		debug2(20,"MX %u %s", mx_buffer[nmx].pref,
-			   mx_buffer[nmx].name);
-		if (++nmx >= MAXMXCOUNT)
-			break;
-	}
-
-	/* Sort according to preference value */
-	qsort(mx_buffer, nmx, sizeof mx_buffer[0], comp_pref);
-
-	/* Prepare return value */
-	memset(mxbuf, 0, sizeof(mxbuf_t));
-	for (i = 0; i < nmx; i++) 
-		mxbuf[i] = mx_buffer[i].name;
-	*pcount = nmx;
-	return mf_success;
-}
-
-int
-is_ipaddr(char *addr)
-{
-        int dot_count;
-        int digit_count;
-
-        dot_count = 0;
-        digit_count = 0;
-        while (*addr != 0 && *addr != ' ') {
-                if (*addr == '.') {
-                        if (++dot_count > 3)
-                                break;
-                        digit_count = 0;
-                } else if (!(isdigit(*addr) && ++digit_count <= 3)) {
-                        return 0;
-                }
-                addr++;
-        }
-
-        return dot_count == 3;
-}
-
-MUTEX_DCL(mf_mutex)
-
-/* Return MX records for the given HOST. If no records were found, recurse
-   to its parent domains until any record is found or recursion depth reaches
-   MAXDEPTH */
-static mf_status
-get_mx_records(char *host, int maxdepth, mxbuf_t mxbuf, size_t *mxcount,
-	       unsigned long *ttl)
+mf_status
+dns_to_mf_status(dns_status stat)
 {
-	char *hbuf = NULL;
-	mf_status status = mf_failure;
-	
-	MUTEX_LOCK(mf_mutex);
-	if (is_ipaddr(host)) {
-		status = resolve_ipstr(host, &hbuf);
-		if (status != mf_success)
-			host = NULL;
-	}
-	
-	if (host) {		
-		unsigned char *answer = malloc(MAXPACKET);
-		if (!answer)
-			status = mf_failure;
-		else {
-			char *p;
-			int depth;
-			
-			for (p = host, depth = 0; p && depth < maxdepth;
-			     p++, depth++) {
-				*ttl = ~(unsigned long)0;
-				status = _getmx(p, answer, MAXPACKET, mxbuf,
-						mxcount, ttl);
-				if (status == mf_success 
-				    || status == mf_temp_failure)
-					break;
-				p = strchr(p, '.');
-				if (!p)
-					break;
-			}
-			free(answer);
-		}
-	}
-	MUTEX_UNLOCK(mf_mutex);
-	free(hbuf);
-	return status;
+	return (mf_status) stat;
 }
 
 mf_status
@@ -228,312 +41,20 @@ getmx(char *host, mxbuf_t mxbuf)
 {
 	mf_status rc = dns_cache_get(T_MX, host, mxbuf, MAXMXCOUNT);
 	if (!mf_resolved(rc)) {
+		dns_status status;
 		unsigned long ttl;
 		size_t mxcnt;
-		rc = get_mx_records(host, 1, mxbuf, &mxcnt, &ttl);
-		if (rc == mf_success) 
+		
+		status = dns_get_mx_records(host, 1, mxbuf, &mxcnt, &ttl);
+		if (status == dns_success) 
 			dns_cache_put(T_MX, host, ttl, mxbuf, mxcnt);
 		else
 			dns_cache_put(T_MX, host, 0, NULL, 0);
+		rc = dns_to_mf_status(status);
 	}
 	return rc;
 }
 
-void
-freemx(mxbuf_t mxbuf)
-{
-	int i;
-	for (i = 0; i < MAXMXCOUNT && mxbuf[i]; i++)
-		free(mxbuf[i]);
-}
-
-#define MAXCNAMEDEPTH 24 /* FIXME */
-
-#define LOOKUP_FAILURE  -1
-#define LOOKUP_SUCCESS 0
-#define LOOKUP_CNAME   1
-
-struct loop_data {
-	int qtype;
-	char *name;
-	size_t name_size;
-	char *domain;
-	size_t domain_size;
-	char *answer;
-	size_t answer_size;
-	char *hbuf;
-	size_t hbsize;
-	time_t ttl;
-	mf_status status;
-	size_t loopcnt;
-	int atype;
-};
-
-#define NSIZE MAX(MAXPACKET, MAXDNAME*2+2)
-#define SET_STATUS(lp,s) if ((lp)->status != mf_success) (lp)->status = s
-
-typedef struct {
-	GACOPYZ_UINT32_T x; 
-	char a;
-} align;
-
-static int
-domain_name_cmp(const char *ptr, const char *name, const char *domain)
-{
-	int c;
-	while (*name)
-		if (c = *ptr++ - *name++)
-			return c;
-	if (*domain && *ptr != '.')
-		return *ptr - *domain;
-	ptr++;
-	while (*domain)
-		if (c = *ptr++ - *domain++)
-			return c;
-	return 0;
-}
-
-int
-cnameloop(struct loop_data *lp)
-{
-	int i, n, rc;
-	HEADER *hp;
-	unsigned char *eom, *cp;
-	unsigned short qdcount, ancount;
-	char *p;
-	size_t len;
-	struct __res_state statb;
-	char *hap = lp->hbuf; /*FIXME*/
-		
-	memset((void *)&statb, 0, sizeof(struct __res_state));
-	res_ninit(&statb);
-	n = res_nquerydomain (&statb, lp->name, lp->domain, C_IN, lp->qtype,
-			     lp->answer, lp->answer_size);
-	res_nclose(&statb);
-	if (n < 0) {
-		debug2(10, "res_nquerydomain failed (errno=%s, h_errno=%d)",
-		       mu_strerror(errno), h_errno);
-		switch (h_errno) {
-		case NO_DATA:
-		case NO_RECOVERY:
-		case HOST_NOT_FOUND:
-			SET_STATUS(lp, mf_not_found);
-			return LOOKUP_FAILURE;
-
-		case TRY_AGAIN:
-		case -1:
-			SET_STATUS(lp, mf_temp_failure);
-			return LOOKUP_FAILURE;
-
-		default:
-			mu_error("res_nquerydomain(%s) failed with unexpected h_errno %d",
-				 lp->name, h_errno);
-			SET_STATUS(lp, mf_failure);
-			return LOOKUP_FAILURE;
-		}
-	}
-
-	if (n > lp->answer_size)
-		n = lp->answer_size;
-
-	hp = (HEADER*) lp->answer;
-	cp = (unsigned char *) lp->answer + HFIXEDSZ;
-	eom = (unsigned char *) lp->answer + n;
-	
-	/* Skip query part */
-	for (qdcount = ntohs((unsigned short)hp->qdcount);
-	     qdcount--;
-	     cp += n + QFIXEDSZ) {
-		if ((n = dn_skipname(cp, eom)) < 0) {
-			SET_STATUS(lp, mf_failure);
-			return LOOKUP_FAILURE;
-		}
-	}
-
-	for (ancount = ntohs((unsigned short) hp->ancount), i = 0;
-	     i < ancount && cp < eom;
-	     cp += n, i++) {
-		unsigned short type;
-		unsigned long ttl = ~(unsigned long)0;
-		char nbuf[NSIZE];
-		char *bp = nbuf;
-		size_t blen = sizeof nbuf;
-		size_t l;
-		
-		n = dn_expand((unsigned char *) lp->answer, eom, cp,
-			      nbuf, sizeof nbuf);
-		if (n < 0)
-			break;
-		cp += n;
-		GETSHORT(type, cp);
-		cp += INT16SZ;		/* skip over class */
-		GETLONG(ttl, cp);
-		if (lp->ttl > ttl)
-			lp->ttl = ttl;
-		GETSHORT(n, cp);	/* rdlength */
-		switch (type) {
-		case T_A:
-			if (domain_name_cmp(bp, lp->name, lp->domain) != 0) {
-				cp += n;
-				continue;
-			}
-			/* Skip host name */
-			l = strlen(bp) + 1;
-			bp += l;
-			blen -= l;
-
-			blen -= sizeof(align) - ((u_long)bp % sizeof(align));
-			bp += sizeof(align) - ((u_long)bp % sizeof(align));
-
-			if (bp + n >= nbuf + blen) {
-				printf("size (%d) too big\n", n);
-				continue;
-			}
-			/* FIXME: This is not ncessary now that we retrieve
-			   only the first A record, but will be necessary in
-			   the future, when the entire array of A records will
-			   be returned */
-			if (hap >= lp->hbuf + lp->hbsize) {
-				printf("Too many addresses\n");
-				cp += n;
-				continue;
-			}
-			memmove(hap, cp, n);
-			bp += n;
-			blen -= n;
-			cp += n;
-			hap += n;
-			lp->atype = T_A;
-			SET_STATUS(lp, mf_success);
-			return LOOKUP_SUCCESS;
-				
-		case T_PTR:
-			if ((rc = dn_expand((unsigned char *)lp->answer,
-					    eom, cp,
-					    nbuf, sizeof(nbuf))) < 0) {
-				SET_STATUS(lp, mf_failure);
-				return LOOKUP_FAILURE;
-			}
-			
-			strncpy(lp->hbuf, nbuf, lp->hbsize);
-			lp->hbuf[lp->hbsize-1] = 0;
-			lp->atype = T_PTR;
-			SET_STATUS(lp, mf_success);
-			return LOOKUP_SUCCESS;
-			
-		case T_CNAME:
-			if (--lp->loopcnt == 0) {
-				mu_error ("DNS failure: CNAME loop for %s",
-					  lp->name);
-				SET_STATUS(lp, mf_failure);
-				return LOOKUP_FAILURE;
-			}
-
-			if ((rc = dn_expand((unsigned char *)lp->answer,
-					    eom, cp,
-					    nbuf, sizeof(nbuf))) < 0) {
-				SET_STATUS(lp, mf_failure);
-				return LOOKUP_FAILURE;
-			}
-			
-			strncpy(lp->hbuf, nbuf, lp->hbsize);
-			lp->hbuf[lp->hbsize-1] = 0;
-			/* RFC 1034 section 3.6 specifies that CNAME
-			   should point at the canonical name -- but
-			   urges software to try again anyway.
-			*/
-			p = strchr (lp->hbuf, '.');
-			if (!p)
-				return LOOKUP_SUCCESS;
-			len = p - lp->hbuf;
-			if (len + 1 >= lp->name_size)
-				return LOOKUP_FAILURE;
-			memcpy(lp->name, lp->hbuf, len);
-			lp->name[len] = 0;
-			len = strlen (p + 1);
-			if (len + 1 >= lp->domain_size)
-				return LOOKUP_FAILURE;
-			strcpy(lp->domain, p + 1);
-			lp->atype = T_CNAME;
-			SET_STATUS(lp, mf_success);
-			return LOOKUP_CNAME;
-		}
-	}	
-	SET_STATUS(lp, mf_not_found);
-	return LOOKUP_FAILURE;
-}
-
-mf_status
-_resolve_ipstr(const char *ipstr, const char *domain,
-	       char *answer, size_t answer_size,
-	       char *hbuf, size_t hbsize, unsigned long *ttl)
-{
-	int i;
-	char revipstr[3*4+3+1];
-	char namebuf[NSIZE];
-	char domainbuf[NSIZE];
-	const char *p;
-	char *q;
-	struct loop_data ld;
-
-	ld.qtype = T_ANY;
-
-	if (!domain) {
-		q = revipstr + strlen (ipstr);
-		*q = 0;
-		for (i = 0, p = ipstr; *p && i < 4; i++) {
-			int len;
-			
-			for (len = 0; p[len] && p[len] != '.'; len++)
-				;
-			q -= len;
-			memcpy(q, p, len);
-			if (q > revipstr)
-				*--q = '.';
-			p += len;
-			if (*p == '.')
-				p++;
-		}
-
-		if (*p || i != 4)
-			return mf_failure;
-		
-		ld.name = namebuf;
-		ld.name_size = sizeof namebuf;
-		strcpy(namebuf, revipstr);
-	} else {
-		strncpy(namebuf, ipstr, sizeof(namebuf)-1);
-		namebuf[sizeof(namebuf)-1] = 0;
-		ld.name = namebuf;
-		ld.name_size = strlen(ld.name);
-	}
-	
-	ld.domain = domainbuf;
-	strcpy(domainbuf, domain ? domain : "in-addr.arpa");
-	ld.domain_size = sizeof domainbuf;
-	ld.answer = answer;
-	ld.answer_size = answer_size;
-	ld.hbuf = hbuf;
-	ld.hbsize = hbsize;
-	ld.ttl = ~(unsigned long)0;
-	ld.status = mf_failure;
-	ld.loopcnt = MAXCNAMEDEPTH;
-
-	while (cnameloop(&ld) == LOOKUP_CNAME)
-		;
-
-	if (ld.status == mf_success && ld.atype == T_A) {
-		struct in_addr s;
-		char *p;
-		s.s_addr = *(GACOPYZ_UINT32_T*)hbuf;
-		p = inet_ntoa(s);
-		strncpy(hbuf, p, hbsize);
-	}
-	
-	*ttl = ld.ttl;
-	return ld.status;
-}
-
 mf_status
 resolve_ipstr_domain(const char *ipstr, const char *domain, char **phbuf)
 {
@@ -542,7 +63,7 @@ resolve_ipstr_domain(const char *ipstr, const char *domain, char **phbuf)
 	char *hbuf;
 	
 	if (!answer)
-		answer = malloc(MAXPACKET);
+		answer = xmalloc(MAXPACKET);
 	debug1(80,"Getting canonical name for %s", ipstr);
 
 	status = dns_cache_get(T_PTR, ipstr, &hbuf, 1);
@@ -554,23 +75,24 @@ resolve_ipstr_domain(const char *ipstr, const char *domain, char **phbuf)
 	} else {
 		unsigned long ttl;
 		char buffer[256];
+		dns_status dstat;
 		
-		MUTEX_LOCK(mf_mutex);
-		status = _resolve_ipstr(ipstr, domain, answer, MAXPACKET,
-					buffer, sizeof buffer, &ttl);
-		MUTEX_UNLOCK(mf_mutex);
-		switch (status) {
-		case mf_success:
+		dstat = dns_resolve_ipstr(ipstr, domain, answer, MAXPACKET,
+					  buffer, sizeof buffer, &ttl);
+
+		switch (dstat) {
+		case dns_success:
 			debug2(80, "%s resolved to %s", ipstr, buffer);
 			*phbuf = xstrdup(buffer);
 			dns_cache_put(T_PTR, ipstr, ttl, phbuf, 1);
 			break;
 
-		case mf_not_found:
+		case dns_not_found:
 			dns_cache_put(T_PTR, ipstr, 0, NULL, 0);
 		default:
 			debug1(80, "%s not resolved", ipstr);
 		}
+		status = dns_to_mf_status(dstat);
 	}
 	return status;
 }
@@ -582,41 +104,6 @@ resolve_ipstr(const char *ipstr, char **phbuf)
 }
 
 mf_status
-_resolve_hostname(char *host, char *answer, size_t answer_size,
-		  char *ipbuf, size_t ipbsize, unsigned long *ttl)
-{
-	struct loop_data ld;
-	char domainbuf[256] = "";
-	
-	ld.qtype = T_A;
-	ld.name = host;
-	ld.name_size = strlen(host);
-	ld.domain = domainbuf;
-	ld.domain_size = sizeof domainbuf;
-	ld.answer = answer;
-	ld.answer_size = answer_size;
-	ld.hbuf = ipbuf;
-	ld.hbsize = ipbsize;
-	ld.ttl = ~(unsigned long)0;
-	ld.status = mf_failure;
-	ld.loopcnt = MAXCNAMEDEPTH;
-
-	while (cnameloop(&ld) == LOOKUP_CNAME)
-		;
-
-	if (ld.status == mf_success && ld.atype == T_A) {
-		struct in_addr s;
-		char *p;
-		s.s_addr = *(GACOPYZ_UINT32_T*)ipbuf;
-		p = inet_ntoa(s);
-		strncpy(ipbuf, p, ipbsize);
-	}
-	
-	*ttl = ld.ttl;
-	return ld.status;
-}
-
-mf_status
 resolve_hostname(const char *host, char **pipbuf)	
 {
 	mf_status status;
@@ -636,27 +123,26 @@ resolve_hostname(const char *host, char **pipbuf)
 	} else {
 		unsigned long ttl;
 		char *tmphost = xstrdup(host);
+		dns_status dstat;
 		
-		MUTEX_LOCK(mf_mutex);
-		status = _resolve_hostname(tmphost, answer, MAXPACKET,
-					   buffer, sizeof buffer,
-					   &ttl);
-		MUTEX_UNLOCK(mf_mutex);
+		dstat = dns_resolve_hostname(tmphost, answer, MAXPACKET,
+					     buffer, sizeof buffer,
+					     &ttl);
 		free(tmphost);
-		switch (status) {
-		case mf_success:
+		switch (dstat) {
+		case dns_success:
 			ipbuf = xstrdup(buffer);
 			debug2(80, "%s resolved to %s", host, ipbuf);
 			*pipbuf = ipbuf;
 			dns_cache_put(T_A, host, ttl, &ipbuf, 1);
 			break;
 			
-		case mf_not_found:
+		case dns_not_found:
 			dns_cache_put(T_A, host, 0, NULL, 0);
 		default:
 			debug1(80, "%s not resolved", host);
 		}
+		status = dns_to_mf_status(dstat);
 	}
 	return status;
 }
-
diff --git a/src/dns.h b/src/dns.h
new file mode 100644
index 00000000..7b7fd7b4
--- /dev/null
+++ b/src/dns.h
@@ -0,0 +1,95 @@
+/* This file is part of mailfromd.
+   Copyright (C) 2005, 2006, 2007 Sergey Poznyakoff
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 2, or (at your option)
+   any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, write to the Free Software
+   Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
+   MA 02110-1301 USA */
+
+typedef enum {
+	dns_success,
+	dns_not_found,
+	dns_failure,
+	dns_temp_failure,
+} dns_status;
+
+#define NELEMS(c) (sizeof(c)/sizeof((c)[0]))
+
+/* Libresolv-related defines and DNS functions */
+#ifndef MAXPACKET
+# define MAXPACKET 8192	/* max packet size used internally by BIND */
+#endif 
+
+#define MAXMXCOUNT 32
+typedef char *mxbuf_t[MAXMXCOUNT];
+
+#define MAXCNAMEDEPTH 24 /* FIXME */
+
+#ifdef HAVE_PTHREAD
+# define MUTEX_DCL(name) \
+ static pthread_mutex_t name = PTHREAD_MUTEX_INITIALIZER;
+# define MUTEX_LOCK(name) \
+ pthread_mutex_lock(&name)
+# define MUTEX_UNLOCK(name) \
+ pthread_mutex_unlock(&name);
+#else
+# define MUTEX_DCL(name)
+# define MUTEX_LOCK(name)
+# define MUTEX_UNLOCK(name)
+#endif
+
+#if !defined res_ninit && !defined HAVE_RES_NINIT
+# define res_ninit(s)
+#endif
+
+#if !defined res_nclose && !defined HAVE_RES_NCLOSE
+# define res_nclose(s)
+#endif
+
+#if !defined res_nquery && !defined HAVE_RES_NQUERY
+# define res_nquery(stat,name,class,type,answer,anslen) \
+ res_query(name,class,type,answer,anslen)
+#endif
+
+#if !defined res_nquerydomain && !defined HAVE_RES_NQUERYDOMAIN
+# define res_nquerydomain(stat,name,domain,class,type,answer,anslen) \
+ res_querydomain(name,domain,class,type,answer,anslen)
+#endif
+
+int dns_str_is_ipv4(char *addr);
+dns_status dns_get_mx_records(char *host, int maxdepth, mxbuf_t mxbuf,
+			      size_t *mxcount, unsigned long *ttl);
+void dns_freemx(mxbuf_t mxbuf);
+
+int dns_reverse_ipstr(const char *ipstr, char *revipstr);
+
+dns_status dns_resolve_ipstr(const char *ipstr, const char *domain,
+			     char *answer, size_t answer_size,
+			     char *hbuf, size_t hbsize, unsigned long *ttl);
+
+dns_status dns_resolve_hostname(char *host, char *answer, size_t answer_size,
+				char *ipbuf, size_t ipbsize,
+				unsigned long *ttl);
+dns_status a_lookup(char *host, 
+		    GACOPYZ_UINT32_T *ipbuf, size_t ipbsize, size_t *ipcount,
+		    unsigned long *ttl, char *answer, size_t answer_size);
+
+dns_status ptr_lookup(struct in_addr ip,
+		      char **names, size_t maxnames, unsigned long *ttl,
+		      char *answer, size_t answer_size);
+dns_status txt_lookup(char *name,
+		      char **names, size_t maxnames, unsigned long *ttl,
+		      char *answer, size_t answer_size);
+
+dns_status ptr_validate(const char *ipstr, char ***vnptr, size_t *vcount);
+	
diff --git a/src/dnsbase.c b/src/dnsbase.c
new file mode 100644
index 00000000..49c86f03
--- /dev/null
+++ b/src/dnsbase.c
@@ -0,0 +1,789 @@
+/* This file is part of mailfromd.
+   Copyright (C) 2005, 2006, 2007 Sergey Poznyakoff
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 2, or (at your option)
+   any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, write to the Free Software
+   Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
+   MA 02110-1301 USA */
+
+#ifdef HAVE_CONFIG_H
+# include <config.h>
+#endif
+
+#include <sys/types.h>
+#include <stdlib.h>
+#include <netinet/in.h>
+#include <arpa/inet.h>
+#include <arpa/nameser.h>
+#include <netdb.h>
+#include <resolv.h>
+#include "mailfrom.h"
+
+struct mx_buffer {
+	unsigned pref;
+	char *name;
+};
+
+static int
+comp_pref(const void *a, const void *b)
+{
+	const struct mx_buffer *ma = a, *mb = b;
+	if (ma->pref > mb->pref)
+		return 1;
+	else if (ma->pref < mb->pref)
+		return -1;
+	return 0;
+}
+
+/* Obtain MX records for domain name HOST. Return them in mxbuf, sorted by
+   preference in ascending order.
+   Notice that we *have* to use old BIND-4-style method, since glibc folks
+   in their incredible wiseness have not exported new interface functions
+   from libresolve.so. The only way to access them would be to link with
+   -lresolve statically.
+   
+   Let's hope that someday this stupidity will change. */
+   
+static dns_status
+_getmx(char *host, char *answer, size_t answer_size, mxbuf_t mxbuf,
+       size_t *pcount, unsigned long *pttl)
+{
+	int i, n, nmx;
+	struct mx_buffer mx_buffer[MAXMXCOUNT];
+	HEADER *hp;
+	unsigned char *eom, *cp;
+	unsigned short qdcount, ancount;
+	struct __res_state stat;
+
+	debug1(80,"Getting MX records for %s", host);
+	memset((void *)&stat, 0, sizeof(struct __res_state));
+	res_ninit(&stat);
+	n = res_nquery (&stat, host, C_IN, T_MX, answer, answer_size);
+	res_nclose(&stat);
+	if (n < 0) {
+		debug2(10, "res_nquery failed (errno=%s, h_errno=%d)",
+		       mu_strerror(errno), h_errno);
+		switch (h_errno) {
+		case NO_DATA:
+		case NO_RECOVERY:
+		case HOST_NOT_FOUND:
+			return dns_not_found;
+
+		case TRY_AGAIN:
+		case -1:
+			return dns_temp_failure;
+
+		default:
+			mu_error("res_nquery(%s) failed with unexpected h_errno %d",
+				 host, h_errno);
+			return dns_failure;
+		}
+	}
+
+	if (n > answer_size)
+		n = answer_size;
+
+	hp = (HEADER*)answer;
+	cp = (unsigned char *) answer + HFIXEDSZ;
+	eom = (unsigned char *) answer + n;
+	
+	/* Skip query part */
+	for (qdcount = ntohs((unsigned short)hp->qdcount);
+	     qdcount--;
+	     cp += n + QFIXEDSZ) {
+		if ((n = dn_skipname(cp, eom)) < 0)
+			return dns_failure;
+	}
+
+	ancount = ntohs((unsigned short)hp->ancount);
+
+	/* Collect MX records */
+	for (i = nmx = 0; i < ancount; i++) {
+		unsigned short pref, type;
+		char tname[NS_MAXDNAME];
+		unsigned long ttl;
+		
+		if ((n = dn_expand((unsigned char *)answer,
+				   eom, cp, tname, sizeof tname)) < 0)
+			break;
+		cp += n;
+		GETSHORT(type, cp);
+		cp += INT16SZ;
+		GETLONG(ttl, cp);
+		if (*pttl > ttl)
+			*pttl = ttl;
+		GETSHORT(n, cp);
+		if (type != T_MX) {
+			debug2(90,"unexpected answer type %d, size %d\n",
+				   type, n);
+			cp += n;
+			continue;
+		}
+		GETSHORT(pref, cp);
+		if ((n = dn_expand((u_char *)answer, eom, cp,
+				   tname, sizeof tname)) < 0)
+			break;
+		cp += n;
+		mx_buffer[nmx].pref = pref;
+		mx_buffer[nmx].name = strdup(tname);
+		debug2(20,"MX %u %s", mx_buffer[nmx].pref,
+			   mx_buffer[nmx].name);
+		if (++nmx >= MAXMXCOUNT)
+			break;
+	}
+
+	/* Sort according to preference value */
+	qsort(mx_buffer, nmx, sizeof mx_buffer[0], comp_pref);
+
+	/* Prepare return value */
+	memset(mxbuf, 0, sizeof(mxbuf_t));
+	for (i = 0; i < nmx; i++) 
+		mxbuf[i] = mx_buffer[i].name;
+	*pcount = nmx;
+	return dns_success;
+}
+
+int
+dns_str_is_ipv4(char *addr)
+{
+        int dot_count;
+        int digit_count;
+
+        dot_count = 0;
+        digit_count = 0;
+        while (*addr != 0 && *addr != ' ') {
+                if (*addr == '.') {
+                        if (++dot_count > 3)
+                                break;
+                        digit_count = 0;
+                } else if (!(isdigit(*addr) && ++digit_count <= 3)) {
+                        return 0;
+                }
+                addr++;
+        }
+
+        return dot_count == 3;
+}
+
+MUTEX_DCL(dns_mutex)
+
+/* Return MX records for the given HOST. If no records were found, recurse
+   to its parent domains until any record is found or recursion depth reaches
+   MAXDEPTH */
+dns_status
+dns_get_mx_records(char *host, int maxdepth, mxbuf_t mxbuf, size_t *mxcount,
+		   unsigned long *ttl)
+{
+	char *hbuf = NULL;
+	dns_status status = dns_failure;
+	
+	MUTEX_LOCK(dns_mutex);
+	if (dns_str_is_ipv4(host)) {