Fix reporting of permanent/temporary failures for MX lookups.

Simplify code a bit while there.

ok gilles@

3 files changed, 50 insertions, 26 deletions

diff --git a/usr.sbin/smtpd/dns.c b/usr.sbin/smtpd/dns.c
index f587eed5a08..e1a66e92a06 100644
--- a/usr.sbin/smtpd/dns.c
+++ b/usr.sbin/smtpd/dns.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: dns.c,v 1.43 2011/07/03 17:48:40 nicm Exp $	*/
+/*	$OpenBSD: dns.c,v 1.44 2011/07/20 10:22:54 eric Exp $	*/
 
 /*
  * Copyright (c) 2008 Gilles Chehade <gilles@openbsd.org>
@@ -72,6 +72,7 @@ static void dns_asr_handler(int, short, void *);
 static void dns_asr_dispatch_host(struct dnssession *);
 static void dns_asr_dispatch_mx(struct dnssession *);
 static void dns_asr_dispatch_cname(struct dnssession *);
+static void dns_reply(struct dns *, int);
 
 struct asr *asr = NULL;
 
@@ -168,10 +169,14 @@ dns_async(struct imsgev *asker, int type, struct dns *query)
 	env->stats->lka.queries_failure++;
 	dnssession_destroy(dnssession);
 noasr:
-	query->error = EAI_AGAIN;
-	if (type != IMSG_DNS_PTR)
-		type = IMSG_DNS_HOST_END;
-	imsg_compose_event(asker, type, 0, 0, -1, query, sizeof(*query));
+	query->error = DNS_RETRY;
+	dns_reply(query, type != IMSG_DNS_PTR ? IMSG_DNS_HOST_END : type);
+}
+
+static void
+dns_reply(struct dns *query, int type)
+{
+	imsg_compose_event(query->asker, type, 0, 0, -1, query, sizeof(*query));
 }
 
 static void
@@ -222,13 +227,27 @@ dns_asr_dispatch_mx(struct dnssession *dnssession)
 		return;
 	}
 
-	if (ar.ar_err)
-		goto hosts;  /* empty list */
+	if (ar.ar_err) {
+		/* temporary internal error, except for invalid name */
+		query->error = (ar.ar_err == EASR_NAME) ? DNS_EINVAL : DNS_RETRY;
+		dns_reply(query, IMSG_DNS_HOST_END);
+		dnssession_destroy(dnssession);
+		return;
+	}
 
 	packed_init(&pack, ar.ar_data, ar.ar_datalen);
 	unpack_header(&pack, &h);
 	unpack_query(&pack, &q);
 
+	/* check if the domain name exists */
+	/* XXX what about other DNS error codes? */
+	if (RCODE(h.flags) == ERR_NAME) {
+		query->error = DNS_ENONAME;
+		dns_reply(query, IMSG_DNS_HOST_END);
+		dnssession_destroy(dnssession);
+		return;
+	}
+
 	if (h.ancount == 0)
 		/* fallback to host if no MX is found. */
 		dnssession_mx_insert(dnssession, query->host, 0);
@@ -243,7 +262,6 @@ dns_asr_dispatch_mx(struct dnssession *dnssession)
 	free(ar.ar_data);
 	ar.ar_data = NULL;
 
-hosts:
 	/* Now we have a sorted list of MX to resolve. Simply "turn" this
 	 * MX session into a regular host session.
 	 */
@@ -264,11 +282,11 @@ next:
 	/* query all listed hosts in turn */
 	while (dnssession->aq == NULL) {
 		if (dnssession->mxcurrent == dnssession->mxarraysz) {
-			query->error = (dnssession->mxfound) ? 0 : EAI_NONAME;
+			/* XXX although not likely, this can still be temporary */
+			query->error = (dnssession->mxfound) ? DNS_OK : DNS_ENOTFOUND;
 			if (query->error)
 				env->stats->lka.queries_failure++;
-			imsg_compose_event(query->asker, IMSG_DNS_HOST_END, 0,
-			    0, -1, query, sizeof(*query));
+			dns_reply(query, IMSG_DNS_HOST_END);
 			dnssession_destroy(dnssession);
 			return;
 		}
@@ -280,8 +298,7 @@ next:
 		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_reply(query, IMSG_DNS_HOST);
 		dnssession->mxfound++;
 	}
 
@@ -317,8 +334,7 @@ dns_asr_dispatch_cname(struct dnssession *dnssession)
 		query->error = ar.ar_err;
 		break;
 	}
-	imsg_compose_event(query->asker, IMSG_DNS_PTR, 0, 0, -1, query,
-	    sizeof(*query));
+	dns_reply(query, IMSG_DNS_PTR);
 	dnssession_destroy(dnssession);
 }
 
diff --git a/usr.sbin/smtpd/mta.c b/usr.sbin/smtpd/mta.c
index 935131b5e8d..7959cc09407 100644
--- a/usr.sbin/smtpd/mta.c
+++ b/usr.sbin/smtpd/mta.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: mta.c,v 1.109 2011/07/19 13:15:54 eric Exp $	*/
+/*	$OpenBSD: mta.c,v 1.110 2011/07/20 10:22:54 eric Exp $	*/
 
 /*
  * Copyright (c) 2008 Pierre-Yves Ritschard <pyr@openbsd.org>
@@ -552,15 +552,15 @@ mta_pickup(struct mta_session *s, void *p)
 
 	case MTA_MX:
 		/* LKA responded to DNS lookup. */
-		error = *(int *)p;
-		if (error == EAI_AGAIN) {
-			mta_status(s, "100 MX lookup failed temporarily");
-			mta_enter_state(s, MTA_DONE, NULL);
-		} else if (error == EAI_NONAME) {
-			mta_status(s, "600 Domain does not exist");
-			mta_enter_state(s, MTA_DONE, NULL);
-		} else if (error) {
-			mta_status(s, "600 Unable to resolve DNS for domain");
+		if ((error = *(int *)p)) {
+			if (error == DNS_RETRY)
+				mta_status(s, "100 MX lookup failed temporarily");
+			else if (error == DNS_EINVAL)
+				mta_status(s, "600 Invalid domain name");
+			else if (error == DNS_ENONAME)
+				mta_status(s, "600 Domain does not exist");
+			else if (error == DNS_ENOTFOUND)
+				mta_status(s, "600 No MX address found for domain");
 			mta_enter_state(s, MTA_DONE, NULL);
 		} else
 			mta_enter_state(s, MTA_DATA, NULL);
diff --git a/usr.sbin/smtpd/smtpd.h b/usr.sbin/smtpd/smtpd.h
index f2a92a0e976..1be8b5c8c8b 100644
--- a/usr.sbin/smtpd/smtpd.h
+++ b/usr.sbin/smtpd/smtpd.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: smtpd.h,v 1.227 2011/06/09 17:41:52 gilles Exp $	*/
+/*	$OpenBSD: smtpd.h,v 1.228 2011/07/20 10:22:54 eric Exp $	*/
 
 /*
  * Copyright (c) 2008 Gilles Chehade <gilles@openbsd.org>
@@ -745,6 +745,14 @@ struct forward_req {
 	struct envelope			 envelope;
 };
 
+enum dns_status {
+	DNS_OK = 0,
+	DNS_RETRY,
+	DNS_EINVAL,
+	DNS_ENONAME,
+	DNS_ENOTFOUND,
+};
+
 struct dns {
 	u_int64_t		 id;
 	char			 host[MAXHOSTNAMELEN];