- Be lenient and accept imgw.pl malformed packet (like BIND).

git-svn-id: file:///svn/unbound/trunk@2339 be551aaa-1e26-0410-a405-d3ace91eadb9

doc/Changelog

@@ -1,6 +1,7 @@
 8 November 2010: Wouter
 	- release tag 1.4.7.
 	- trunk is version 1.4.8.
+	- Be lenient and accept imgw.pl malformed packet (like BIND).
 
 5 November 2010: Wouter
 	- do not synthesize a CNAME message from cache for qtype DS.

testcode/unitmsgparse.c

@@ -53,6 +53,8 @@
 
 /** verbose message parse unit test */
 static int vbmp = 0;
+/** do not accept formerr */
+static int check_formerr_gone = 0;
 /** if matching within a section should disregard the order of RRs. */
 static int matches_nolocation = 0;
 /** see if RRSIGs are properly matched to RRsets. */
@@ -415,10 +417,12 @@ testpkt(ldns_buffer* pkt, struct alloc_cache* alloc, ldns_buffer* out,
 	if(ret != 0) {
 		if(vbmp) printf("parse code %d: %s\n", ret, 
 			ldns_lookup_by_id(ldns_rcodes, ret)->name);
-		if(ret == LDNS_RCODE_FORMERR)
+		if(ret == LDNS_RCODE_FORMERR) {
+			unit_assert(!check_formerr_gone);
 			checkformerr(pkt);
+		}
 		unit_assert(ret != LDNS_RCODE_SERVFAIL);
-	} else {
+	} else if(!check_formerr_gone) {
 		const size_t lim = 512;
 		ret = reply_info_encode(&qi, rep, id, flags, out, timenow,
 			region, 65535, (int)(edns.bits & EDNS_DO) );
@@ -599,6 +603,10 @@ void msgparse_test(void)
 	check_rrsigs = 0;
 	matches_nolocation = 0; 
 
+	check_formerr_gone = 1;
+	testfromdrillfile(pkt, &alloc, out, "testdata/test_packets.8");
+	check_formerr_gone = 0;
+
 	/* cleanup */
 	alloc_clear(&alloc);
 	alloc_clear(&super_a);

testdata/test_packets.8

@@ -0,0 +1,13 @@
+; Test that FORMERR no longer happens.
+;-- next packet --
+; bad packet, had arcount=1 but EDNS record is missing.
+; from imgw.pl.  BIND accepts it (but dig notes 'it is malformed').
+; therefore we leniently accept this.
+; header
+75D684100001000200000001
+; qd section
+04696D677702706C0000010001
+; answer section 
+04696D677702706C000001000100000E100004C3BB560E
+04696D677702706C000001000100000E100004C3BB560D
+

util/data/msgparse.c

@@ -903,8 +903,11 @@ parse_packet(ldns_buffer* pkt, struct msg_parse* msg, struct regional* region)
 	if((ret = parse_section(pkt, msg, region, LDNS_SECTION_AUTHORITY,
 		msg->nscount, &msg->ns_rrsets)) != 0)
 		return ret;
-	if((ret = parse_section(pkt, msg, region, LDNS_SECTION_ADDITIONAL, 
-		msg->arcount, &msg->ar_rrsets)) != 0)
+	if(ldns_buffer_remaining(pkt) == 0 && msg->arcount == 1) {
+		/* BIND accepts leniently that an EDNS record is missing.
+		 * so, we do too. */
+	} else if((ret = parse_section(pkt, msg, region,
+		LDNS_SECTION_ADDITIONAL, msg->arcount, &msg->ar_rrsets)) != 0)
 		return ret;
 	/* if(ldns_buffer_remaining(pkt) > 0) { */
 		/* there is spurious data at end of packet. ignore */