cleanup and simplification following the asr update.

- use a specific dispatch function for each type of query
- make the host handler work on a list of hosts by default (single host
  queries are just a particular case) and use that to resolve the MX list
- various other code cleanup
- remove unused headers
- remove orphaned prototypes
- update copyright

ok gilles@

1 files changed, 102 insertions, 168 deletions

diff --git a/usr.sbin/smtpd/dns.c b/usr.sbin/smtpd/dns.c
index f5079c73ab1..ed244452099 100644
--- a/usr.sbin/smtpd/dns.c
+++ b/usr.sbin/smtpd/dns.c
@@ -1,8 +1,9 @@
-/*	$OpenBSD: dns.c,v 1.37 2011/03/29 20:43:51 eric Exp $	*/
+/*	$OpenBSD: dns.c,v 1.38 2011/03/31 10:40:59 eric Exp $	*/
 
 /*
  * Copyright (c) 2008 Gilles Chehade <gilles@openbsd.org>
  * Copyright (c) 2009 Jacek Masiulaniec <jacekm@dobremiasto.net>
+ * Copyright (c) 2011 Eric Faurot <eric@faurot.net>
  *
  * Permission to use, copy, modify, and distribute this software for any
  * purpose with or without fee is hereby granted, provided that the above
@@ -19,22 +20,16 @@
 
 #include <sys/types.h>
 #include <sys/socket.h>
-#include <sys/queue.h>
 #include <sys/tree.h>
-#include <sys/stat.h>
 
 #include <netinet/in.h>
 #include <arpa/inet.h>
-#include <arpa/nameser.h>
 
 #include <event.h>
 #include <imsg.h>
-#include <netdb.h>
-#include <resolv.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
-#include <unistd.h>
 
 #include "asr.h"
 #include "dnsdefs.h"
@@ -44,14 +39,12 @@
 
 struct dnssession *dnssession_init(struct smtpd *, struct dns *);
 void	dnssession_destroy(struct smtpd *, struct dnssession *);
-void	dnssession_mx_insert(struct dnssession *, struct mx *);
-void	dns_asr_event_set(struct dnssession *, struct asr_result *, void(*)(int, short, void*));
+void	dnssession_mx_insert(struct dnssession *, const char *, int);
+void	dns_asr_event_set(struct dnssession *, struct asr_result *);
 void	dns_asr_handler(int, short, void *);
-void	dns_asr_mx_handler(int, short, void *);
+void	dns_asr_dispatch_host(struct dnssession *);
+void	dns_asr_dispatch_mx(struct dnssession *);
 void	dns_asr_dispatch_cname(struct dnssession *);
-void	lookup_host(struct imsgev *, struct dns *, int, int);
-void	lookup_mx(struct imsgev *, struct dns *);
-void	lookup_ptr(struct imsgev *, struct dns *);
 
 struct asr *asr = NULL;
 
@@ -115,33 +108,35 @@ dns_async(struct smtpd *env, struct imsgev *asker, int type, struct dns *query)
 	query->type  = type;
 	query->asker = asker;
 	dnssession = dnssession_init(env, query);
-	
+
 	switch (type) {
 	case IMSG_DNS_HOST:
-		dnssession->aq = asr_query_host(asr, query->host, AF_UNSPEC);
-		break;
+		dnssession_mx_insert(dnssession, query->host, 0);
+		dns_asr_dispatch_host(dnssession);
+		return;
 	case IMSG_DNS_PTR:
 		dnssession->aq = asr_query_cname(asr,
 		    (struct sockaddr*)&query->ss, query->ss.ss_len);
-		break;
+		if (dnssession->aq == NULL) {
+			log_debug("dns_async: asr_query_cname error");
+			break;
+		}
+		dns_asr_dispatch_cname(dnssession);
+		return;
 	case IMSG_DNS_MX:
 		dnssession->aq = asr_query_dns(asr, T_MX, C_IN, query->host, 0);
-		break;
+		if (dnssession->aq == NULL) {
+			log_debug("dns_async: asr_query_dns error");
+			break;
+		}
+		dns_asr_dispatch_mx(dnssession);
+		return;
 	default:
-		goto err;
+		log_debug("dns_async: bad request");
+		break;
 	}
 
-	/* query and set up event to handle answer */
-	if (dnssession->aq == NULL)
-		goto err;
-	dns_asr_handler(-1, -1, dnssession);
-	return;
-
-err:
-	log_debug("dns_async: ASR error while attempting to resolve `%s'",
-	    query->host);
 	dnssession_destroy(env, dnssession);
-
 noasr:
 	query->error = EAI_AGAIN;
 	if (type != IMSG_DNS_PTR)
@@ -150,15 +145,14 @@ noasr:
 }
 
 void
-dns_asr_event_set(struct dnssession *dnssession, struct asr_result *ar,
-		  void (*handler)(int, short, void*))
+dns_asr_event_set(struct dnssession *dnssession, struct asr_result *ar)
 {
 	struct timeval tv = { 0, 0 };
 	
 	tv.tv_usec = ar->ar_timeout * 1000;
 	event_set(&dnssession->ev, ar->ar_fd,
 	    ar->ar_cond == ASR_READ ? EV_READ : EV_WRITE,
-	    handler, dnssession);
+	    dns_asr_handler, dnssession);
 	event_add(&dnssession->ev, &tv);
 }
 
@@ -166,168 +160,106 @@ void
 dns_asr_handler(int fd, short event, void *arg)
 {
 	struct dnssession *dnssession = arg;
-	struct dns *query = &dnssession->query;
-	struct smtpd *env = query->env;
-	struct packed pack;
-	struct header	h;
-	struct query	q;
-	struct rr rr;
-	struct mx mx;
-	struct asr_result ar;
-	char *p;
-	int ret;
-
-	if (dnssession->query.type == IMSG_DNS_PTR) {
-		dns_asr_dispatch_cname(dnssession);
-		return;
-	}
-
-	switch ((ret = asr_run(dnssession->aq, &ar))) {
-	case ASR_COND:
-		dns_asr_event_set(dnssession, &ar, dns_asr_handler);
-		return;
 
-	case ASR_YIELD:
-	case ASR_DONE:
+	switch(dnssession->query.type) {
+	case IMSG_DNS_HOST:
+		dns_asr_dispatch_host(dnssession);
+		break;
+	case IMSG_DNS_PTR:
+		dns_asr_dispatch_cname(dnssession);
 		break;
+	case IMSG_DNS_MX:
+		dns_asr_dispatch_mx(dnssession);
+		break;
+	default:
+		fatalx("bad query type");
 	}
+}
 
-	query->error = EAI_AGAIN;
-
-	if (ret == ASR_YIELD) {
-		free(ar.ar_cname);
-		memcpy(&query->ss, &ar.ar_sa.sa, ar.ar_sa.sa.sa_len);
-		query->error = 0;
-		imsg_compose_event(query->asker, IMSG_DNS_HOST, 0, 0, -1, query,
-		    sizeof(*query));
-		dns_asr_handler(-1, -1, dnssession);
+void
+dns_asr_dispatch_mx(struct dnssession *dnssession)
+{
+	struct dns		*query = &dnssession->query;
+	struct asr_result	 ar;
+	struct packed		 pack;
+	struct header		 h;
+	struct query		 q;
+	struct rr		 rr;
+	char			 buf[512];
+
+	if (asr_run(dnssession->aq, &ar) == ASR_COND) {
+		dns_asr_event_set(dnssession, &ar);
 		return;
 	}
 
-	/* ASR_DONE */
-	if (ar.ar_err) {
-		query->error = ar.ar_err;
-		goto err;
-	}
-
-	if (query->type == IMSG_DNS_HOST) {
-		query->error = 0;
-		imsg_compose_event(query->asker, IMSG_DNS_HOST_END, 0, 0, -1,
-		    query, sizeof(*query));
-		dnssession_destroy(env, dnssession);
-		return;
-	}
+	if (ar.ar_err)
+		goto hosts;  /* empty list */
 
-	/* MX */
 	packed_init(&pack, ar.ar_data, ar.ar_datalen);
-	if (unpack_header(&pack, &h) < 0 || unpack_query(&pack, &q) < 0)
-		goto err;
-
-	if (h.ancount == 0) {
-		/* we were looking for MX and got no answer,
-		 * fallback to host.
-		 */
-		query->type = IMSG_DNS_HOST;
-		dnssession->aq = asr_query_host(asr, query->host,
-		    AF_UNSPEC);
-		if (dnssession->aq == NULL)
-			goto err;
-		dns_asr_handler(-1, -1, dnssession);
-		return;
-	}
-
-	for (; h.ancount; h.ancount--) {
-		if (unpack_rr(&pack, &rr) < 0)
-			goto err;
+	unpack_header(&pack, &h);
+	unpack_query(&pack, &q);
 
-		print_dname(rr.rr.mx.exchange, mx.host, sizeof (mx.host));
-		if ((p = strrchr(mx.host, '.')) != NULL)
-			*p = '\0';
-		mx.prio =  rr.rr.mx.preference;
+	if (h.ancount == 0)
+		/* fallback to host if no MX is found. */
+		dnssession_mx_insert(dnssession, query->host, 0);
 
-		/* sorted insert that will not overflow MAX_MX_COUNT */
-		dnssession_mx_insert(dnssession, &mx);
+	for (; h.ancount; h.ancount--) {
+		unpack_rr(&pack, &rr);
+		print_dname(rr.rr.mx.exchange, buf, sizeof(buf));
+		buf[strlen(buf) - 1] = '\0';
+		dnssession_mx_insert(dnssession, buf, rr.rr.mx.preference);
 	}
+
 	free(ar.ar_data);
 	ar.ar_data = NULL;
 
-	/* The T_MX scenario is a bit tricky.
-	 * Rather than forwarding the answers to the process that queried,
-	 * we retrieve a set of MX hosts ... that need to be resolved. The
-	 * loop above sorts them by priority, all we have left to do is to
-	 * perform T_A lookups on all of them sequentially and provide the
-	 * process that queried with the answers.
-	 *
-	 * To make it easier, we do this in another handler.
-	 *
-	 * -- gilles@
+hosts:
+	/* Now we have a sorted list of MX to resolve. Simply "turn" this
+	 * MX session into a regular host session.
 	 */
-	dnssession->mxfound = 0;
-	dnssession->mxcurrent = 0;
-	dnssession->aq = asr_query_host(asr,
-	    dnssession->mxarray[dnssession->mxcurrent].host, AF_UNSPEC);
-	if (dnssession->aq == NULL)
-		goto err;
-
-	dns_asr_mx_handler(-1, -1, dnssession);
-	return;
-
-err:
-	free(ar.ar_data);
-	query->type = IMSG_DNS_HOST_END;
-	imsg_compose_event(query->asker, query->type, 0, 0, -1, query,
-	    sizeof(*query));
-	dnssession_destroy(env, dnssession);
+	dnssession->aq = NULL;
+	dnssession->query.type = IMSG_DNS_HOST;
+	dns_asr_dispatch_host(dnssession);
 }
 
-/* only handle MX requests */
 void
-dns_asr_mx_handler(int fd, short event, void *arg)
+dns_asr_dispatch_host(struct dnssession *dnssession)
 {
-	struct dnssession *dnssession = arg;
-	struct dns *query = &dnssession->query;
-	struct smtpd *env = query->env;
-	struct asr_result ar;
-	int ret;
-
-	switch ((ret = asr_run(dnssession->aq, &ar))) {
-	case ASR_COND:
-		dns_asr_event_set(dnssession, &ar, dns_asr_mx_handler);
-		return;
+	struct dns		*query = &dnssession->query;
+	struct mx		*mx;
+	struct asr_result	 ar;
+	int			 ret;
+
+next:
+	/* query all listed hosts in turn */
+	while (dnssession->aq == NULL) {
+		if (dnssession->mxcurrent == dnssession->mxarraysz) {
+			query->error = (dnssession->mxfound) ? 0 : EAI_NONAME;
+			imsg_compose_event(query->asker, IMSG_DNS_HOST_END, 0,
+			    0, -1, query, sizeof(*query));
+			dnssession_destroy(query->env, dnssession);
+			return;
+		}
+		mx = dnssession->mxarray + dnssession->mxcurrent++;
+		dnssession->aq = asr_query_host(asr, mx->host, AF_UNSPEC);
+	}
 
-	case ASR_YIELD:
+	while ((ret = asr_run(dnssession->aq, &ar)) == ASR_YIELD) {
 		free(ar.ar_cname);
 		memcpy(&query->ss, &ar.ar_sa.sa, ar.ar_sa.sa.sa_len);
 		query->error = 0;
 		imsg_compose_event(query->asker, IMSG_DNS_HOST, 0, 0, -1, query,
 		    sizeof(*query));
 		dnssession->mxfound++;
-		dns_asr_mx_handler(-1, -1, dnssession);
-		return;
-
-	case ASR_DONE:
-		break;
 	}
 
-	if (++dnssession->mxcurrent == dnssession->mxarraysz)
-		goto end;
-
-	dnssession->aq = asr_query_host(asr,
-	    dnssession->mxarray[dnssession->mxcurrent].host, AF_UNSPEC);
-	if (dnssession->aq == NULL)
-		goto end;
-	dns_asr_mx_handler(-1, -1, dnssession);
-	return;
+	if (ret == ASR_COND) {
+		dns_asr_event_set(dnssession, &ar);
+		return;
+	}
 
-end:
-	if (dnssession->mxfound == 0)
-		query->error = EAI_NONAME;
-	else
-		query->error = 0;
-	imsg_compose_event(query->asker, IMSG_DNS_HOST_END, 0, 0, -1, query,
-	    sizeof(*query));
-	dnssession_destroy(env, dnssession);
-	return;
+	dnssession->aq  = NULL;
+	goto next;
 }
 
 void
@@ -338,7 +270,7 @@ dns_asr_dispatch_cname(struct dnssession *dnssession)
 
 	switch (asr_run(dnssession->aq, &ar)) {
 	case ASR_COND:
-		dns_asr_event_set(dnssession, &ar, dns_asr_handler);
+		dns_asr_event_set(dnssession, &ar);
 		return;
 	case ASR_YIELD:
 		/* Only return the first answer */
@@ -381,12 +313,12 @@ dnssession_destroy(struct smtpd *env, struct dnssession *dnssession)
 }
 
 void
-dnssession_mx_insert(struct dnssession *dnssession, struct mx *mx)
+dnssession_mx_insert(struct dnssession *dnssession, const char *host, int prio)
 {
 	size_t i, j;
 
 	for (i = 0; i < dnssession->mxarraysz; i++)
-		if (mx->prio < dnssession->mxarray[i].prio)
+		if (prio < dnssession->mxarray[i].prio)
 			break;
 
 	if (i == MAX_MX_COUNT)
@@ -398,7 +330,9 @@ dnssession_mx_insert(struct dnssession *dnssession, struct mx *mx)
 	for (j = dnssession->mxarraysz - 1; j > i; j--)
 		dnssession->mxarray[j] = dnssession->mxarray[j - 1];
 
-        dnssession->mxarray[i] = *mx;
+        dnssession->mxarray[i].prio = prio;
+	strlcpy(dnssession->mxarray[i].host, host,
+	    sizeof (dnssession->mxarray[i].host));
 }
 
 int