From ddb6ad5e4757c872d8153072fed52de54561c6a6 Mon Sep 17 00:00:00 2001
From: "Eric S. Raymond" <esr@thyrsus.com>
Date: Fri, 8 Nov 1996 22:11:54 +0000
Subject: We no longer attempt delivery to multidrop mailboxes in the presence
 of DNS errors.

svn path=/trunk/; revision=519
---
 NEWS        |  5 +++--
 driver.c    | 28 +++++++++++++++++++++-------
 fetchmail.c | 54 +++++++++++++++++++++++++++---------------------------
 3 files changed, 51 insertions(+), 36 deletions(-)

diff --git a/NEWS b/NEWS
index fa31b809..ef1b473f 100644
--- a/NEWS
+++ b/NEWS
@@ -1,9 +1,10 @@
 			Release Notes:
 
-pl 1.9.10 ():
-* Better error messages on SMTP failure. 
+pl 1.9.9 ():
 * Accept Resent-From & Apparently-From a la RFC822.
 * Include file fixes for Solaris 2.5 and FreeBSD 2.2.
+* Improved error notification on SMTP and no-matching-local-address errors.
+* Delivery to multidrop mailboxes now always aborts on DNS errors.
 
 pl 1.9.8 (Wed Nov  6 16:40:34 EST 1996):
 * Don't append spurious NUL to the headers, qmail actually notices it.
diff --git a/driver.c b/driver.c
index 325383ce..11cde20a 100644
--- a/driver.c
+++ b/driver.c
@@ -120,12 +120,16 @@ static int is_host_alias(const char *name, struct query *ctl)
 	return(TRUE);
 
     /*
-     * We treat DNS lookup failure as a negative on the theory that
-     * the mailserver's DNS server is `nearby' and should be able
-     * to respond quickly and reliably.  Ergo if we get failure,
-     * the name isn't a mailserver alias.
+     * We know DNS service was up at the beginning of this poll cycle.
+     * If it's down, our nameserver has crashed.  We don't want to try
+     * delivering the current message or anything else from this
+     * mailbox until it's back up.
      */
-    else if ((he = gethostbyname(name)) && strcmp(ctl->canonical_name, he->h_name) == 0)
+    else if ((he = gethostbyname(name)) == (struct hostent *)NULL)
+	longjmp(restart, 2);
+
+    /* DNS response is OK */
+    else if (strcmp(ctl->canonical_name, he->h_name) == 0)
 	return(TRUE);
 
     /*
@@ -138,12 +142,15 @@ static int is_host_alias(const char *name, struct query *ctl)
 
 	mxrecords = getmxrecords(name);
 
+	h_errno = 0;
 	if (mxrecords == (struct mxentry *)NULL)
 	    if (h_errno == TRY_AGAIN)
 	    {
 		sleep(1);
 		continue;
 	    }
+	    else if (h_errno)		/* fatal error */
+		longjmp(restart, 2);
 	    else
 		break;
 
@@ -628,7 +635,7 @@ int do_protocol(ctl, proto)
 struct query *ctl;		/* parsed options with merged-in defaults */
 const struct method *proto;	/* protocol method table */
 {
-    int ok;
+    int ok, js;
     void (*sigsave)();
 
 #ifndef KERBEROS_V4
@@ -673,13 +680,20 @@ const struct method *proto;	/* protocol method table */
     sigsave = signal(SIGVTALRM, vtalarm_handler);
     vtalarm(mytimeout = ctl->timeout);
 
-    if (setjmp(restart) == 1)
+    if ((js = setjmp(restart)) == 1)
     {
 	fprintf(stderr,
 		"fetchmail: timeout after %d seconds waiting for %s.\n",
 		ctl->timeout, ctl->servername);
 	ok = PS_ERROR;
     }
+    else if (js == 2)
+    {
+	fprintf(stderr,
+		"fetchmail: nameserver evaporated during poll of %s.\n",
+		ctl->servername);
+	ok = PS_ERROR;
+    }
     else
     {
 	char buf [POPBUFSIZE+1];
diff --git a/fetchmail.c b/fetchmail.c
index 47620dfe..e22568a5 100644
--- a/fetchmail.c
+++ b/fetchmail.c
@@ -307,6 +307,33 @@ int main (int argc, char **argv)
 	{
 	    if (ctl->active && !(implicitmode && ctl->skip))
 	    {
+#ifdef HAVE_GETHOSTBYNAME
+		/*
+		 * This functions partly as an optimization and partly
+		 * as a probe to make sure our nameserver is still up.
+		 * The multidrop case (especially) needs it.
+		 */
+		if (ctl->authenticate == A_KERBEROS || MULTIDROP(ctl))
+		{
+		    struct hostent	*namerec;
+
+		    /* compute the canonical name of the host */
+		    namerec = gethostbyname(ctl->servername);
+		    if (namerec == (struct hostent *)NULL)
+		    {
+			fprintf(stderr,
+				"fetchmail: skipping %s poll, nameserver isn't responding\n",
+				ctl->servername);
+			continue;
+		    }
+		    else
+		    {
+			free(ctl->canonical_name);
+			ctl->canonical_name = xstrdup((char *)namerec->h_name);
+		    }
+		}
+#endif /* HAVE_GETHOSTBYNAME */
+
 		popstatus = query_host(ctl);
 		if (!check_only)
 		    update_uid_lists(ctl);
@@ -439,10 +466,6 @@ static int load_params(int argc, char **argv, int optind)
     {
 	if (ctl->active && !(implicitmode && ctl->skip))
 	{
-#ifdef HAVE_GETHOSTBYNAME
-	    struct hostent	*namerec;
-#endif /* HAVE_GETHOSTBYNAME */
-
 	    /* merge in defaults */
 	    optmerge(ctl, &def_opts);
 
@@ -463,29 +486,6 @@ static int load_params(int argc, char **argv, int optind)
 	    else
 		ctl->uid = pw->pw_uid;
 
-#ifdef HAVE_GETHOSTBYNAME
-	    /*
-	     * Don't do DNS lookup unless we need to because we're going
-	     * to use Kerberos or process a multidrop box.  Some sites
-	     * won't have DNS up at fetchmail initialization time but aren't
-	     * using these features -- avoid hosing them unnecessarily.
-	     */
-	    if (ctl->authenticate == A_KERBEROS || MULTIDROP(ctl))
-	    {
-		/* compute the canonical name of the host */
-		namerec = gethostbyname(ctl->servername);
-		if (namerec == (struct hostent *)NULL)
-		{
-		    fprintf(stderr,
-			    "fetchmail: can't get canonical name of host %s\n",
-			    ctl->servername);
-		    exit(PS_SYNTAX);
-		}
-		else
-		    ctl->canonical_name = xstrdup((char *)namerec->h_name);
-	    }
-#endif /* HAVE_GETHOSTBYNAME */
-
 #if !defined(HAVE_GETHOSTBYNAME) || !defined(HAVE_RES_SEARCH)
 	    /* can't handle multidrop mailboxes unless we can do DNS lookups */
 	    if (ctl->localnames && ctl->localnames->next)
-- 
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