Index: services/outside_network.c

===================================================================

--- services/outside_network.c	(revision 2491)

+++ services/outside_network.c	(revision 2493)

@@ -1199,6 +1199,7 @@

 		if(sq->status == serviced_query_UDP_EDNS ||

 			sq->status == serviced_query_UDP ||

 			sq->status == serviced_query_PROBE_EDNS ||

+			sq->status == serviced_query_UDP_EDNS_FRAG ||

 			sq->status == serviced_query_UDP_EDNS_fallback) {

 			struct pending* p = (struct pending*)sq->pending;

 			if(p->pc)

@@ -1280,7 +1281,19 @@

 		edns.edns_present = 1;

 		edns.ext_rcode = 0;

 		edns.edns_version = EDNS_ADVERTISED_VERSION;

-		edns.udp_size = EDNS_ADVERTISED_SIZE;

+		if(sq->status == serviced_query_UDP_EDNS_FRAG) {

+			if(addr_is_ip6(&sq->addr, sq->addrlen)) {

+				if(EDNS_FRAG_SIZE_IP6 < EDNS_ADVERTISED_SIZE)

+					edns.udp_size = EDNS_FRAG_SIZE_IP6;

+				else	edns.udp_size = EDNS_ADVERTISED_SIZE;

+			} else {

+				if(EDNS_FRAG_SIZE_IP4 < EDNS_ADVERTISED_SIZE)

+					edns.udp_size = EDNS_FRAG_SIZE_IP4;

+				else	edns.udp_size = EDNS_ADVERTISED_SIZE;

+			}

+		} else {

+			edns.udp_size = EDNS_ADVERTISED_SIZE;

+		}

 		edns.bits = 0;

 		if(sq->dnssec & EDNS_DO)

 			edns.bits = EDNS_DO;

@@ -1324,7 +1337,8 @@

 			sq->status = serviced_query_UDP; 

 		}

 	}

-	serviced_encode(sq, buff, sq->status == serviced_query_UDP_EDNS);

+	serviced_encode(sq, buff, (sq->status == serviced_query_UDP_EDNS) ||

+		(sq->status == serviced_query_UDP_EDNS_FRAG));

 	sq->last_sent_time = *sq->outnet->now_tv;

 	sq->edns_lame_known = (int)edns_lame_known;

 	verbose(VERB_ALGO, "serviced query UDP timeout=%d msec", rtt);

@@ -1564,6 +1578,20 @@

 			 * by EDNS. */

 			sq->status = serviced_query_UDP_EDNS;

 		}

+		if(sq->status == serviced_query_UDP_EDNS) {

+			/* fallback to 1480/1280 */

+			sq->status = serviced_query_UDP_EDNS_FRAG;

+			log_name_addr(VERB_ALGO, "try edns1xx0", sq->qbuf+10,

+				&sq->addr, sq->addrlen);

+			if(!serviced_udp_send(sq, c->buffer)) {

+				serviced_callbacks(sq, NETEVENT_CLOSED, c, rep);

+			}

+			return 0;

+		}

+		if(sq->status == serviced_query_UDP_EDNS_FRAG) {

+			/* fragmentation size did not fix it */

+			sq->status = serviced_query_UDP_EDNS;

+		}

 		sq->retry++;

 		if(!(rto=infra_rtt_update(outnet->infra, &sq->addr, sq->addrlen,

 			-1, sq->last_rtt, (uint32_t)now.tv_sec)))

@@ -1589,7 +1617,8 @@

 		return 0;

 	}

 	if(!fallback_tcp) {

-	    if(sq->status == serviced_query_UDP_EDNS 

+	    if( (sq->status == serviced_query_UDP_EDNS 

+	        ||sq->status == serviced_query_UDP_EDNS_FRAG)

 		&& (LDNS_RCODE_WIRE(ldns_buffer_begin(c->buffer)) 

 			== LDNS_RCODE_FORMERR || LDNS_RCODE_WIRE(

 			ldns_buffer_begin(c->buffer)) == LDNS_RCODE_NOTIMPL)) {

@@ -1866,6 +1895,7 @@

 	if(sq->status == serviced_query_UDP_EDNS ||

 		sq->status == serviced_query_UDP ||

 		sq->status == serviced_query_PROBE_EDNS ||

+		sq->status == serviced_query_UDP_EDNS_FRAG ||

 		sq->status == serviced_query_UDP_EDNS_fallback) {

 		s += sizeof(struct pending);

 		s += comm_timer_get_mem(NULL);

Index: services/outside_network.h

===================================================================

--- services/outside_network.h	(revision 2491)

+++ services/outside_network.h	(revision 2493)

@@ -274,6 +274,11 @@

 	void* cb_arg;

 };

+/** fallback size for fragmentation for EDNS in IPv4 */

+#define EDNS_FRAG_SIZE_IP4 1480

+/** fallback size for EDNS in IPv6, fits one fragment with ip6-tunnel-ids */

+#define EDNS_FRAG_SIZE_IP6 1260

+

 /**

  * Query service record.

  * Contains query and destination. UDP, TCP, EDNS are all tried.

@@ -314,7 +319,9 @@

 		/** probe to test noEDNS0 (EDNS gives FORMERRorNOTIMP) */

 		serviced_query_UDP_EDNS_fallback,

 		/** probe to test TCP noEDNS0 (EDNS gives FORMERRorNOTIMP) */

-		serviced_query_TCP_EDNS_fallback

+		serviced_query_TCP_EDNS_fallback,

+		/** send UDP query with EDNS1480 (or 1280) */

+		serviced_query_UDP_EDNS_FRAG

 	} 	

 		/** variable with current status */ 

 		status;