diff --git a/CHANGES b/CHANGES
index 08e484f196..98d39f8d3f 100644
--- a/CHANGES
+++ b/CHANGES
@@ -1,3 +1,7 @@
+ 856.	[func]		Allow partial rdatasets to be returned in answer and
+			authority sections to help non-TCP capable clients
+			recover from truncation.  [RT #1301]
+
  855.	[bug]		Stop spurious "using RFC 1035 TTL semantics" warnings.
 
  854.	[bug]		The config parser didn't properly handle config
diff --git a/bin/named/client.c b/bin/named/client.c
index 0e880ab8fe..deda02f00e 100644
--- a/bin/named/client.c
+++ b/bin/named/client.c
@@ -15,7 +15,7 @@
  * WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  */
 
-/* $Id: client.c,v 1.170 2001/06/04 19:32:52 tale Exp $ */
+/* $Id: client.c,v 1.171 2001/06/05 09:02:10 marka Exp $ */
 
 #include <config.h>
 
@@ -865,7 +865,8 @@ ns_client_send(ns_client_t *client) {
 	if (result != ISC_R_SUCCESS)
 		goto done;
 	result = dns_message_rendersection(client->message,
-					   DNS_SECTION_ANSWER, 0);
+					   DNS_SECTION_ANSWER,
+					   DNS_MESSAGERENDER_PARTIAL);
 	if (result == ISC_R_NOSPACE) {
 		client->message->flags |= DNS_MESSAGEFLAG_TC;
 		goto renderend;
@@ -873,7 +874,8 @@ ns_client_send(ns_client_t *client) {
 	if (result != ISC_R_SUCCESS)
 		goto done;
 	result = dns_message_rendersection(client->message,
-					   DNS_SECTION_AUTHORITY, 0);
+					   DNS_SECTION_AUTHORITY,
+					   DNS_MESSAGERENDER_PARTIAL);
 	if (result == ISC_R_NOSPACE) {
 		client->message->flags |= DNS_MESSAGEFLAG_TC;
 		goto renderend;
diff --git a/lib/dns/include/dns/message.h b/lib/dns/include/dns/message.h
index eadcfc2d93..d891ccd1f2 100644
--- a/lib/dns/include/dns/message.h
+++ b/lib/dns/include/dns/message.h
@@ -15,7 +15,7 @@
  * WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  */
 
-/* $Id: message.h,v 1.97 2001/03/28 02:42:56 bwelling Exp $ */
+/* $Id: message.h,v 1.98 2001/06/05 09:02:14 marka Exp $ */
 
 #ifndef DNS_MESSAGE_H
 #define DNS_MESSAGE_H 1
@@ -157,6 +157,7 @@ typedef int dns_messagetextflag_t;
  * Control behavior of rendering
  */
 #define DNS_MESSAGERENDER_ORDERED	0x0001	/* don't change order */
+#define DNS_MESSAGERENDER_PARTIAL	0x0002	/* allow a partial rdataset */
 
 typedef struct dns_msgblock dns_msgblock_t;
 
diff --git a/lib/dns/include/dns/rdataset.h b/lib/dns/include/dns/rdataset.h
index e5b15b75fe..70b3ba00c0 100644
--- a/lib/dns/include/dns/rdataset.h
+++ b/lib/dns/include/dns/rdataset.h
@@ -15,7 +15,7 @@
  * WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  */
 
-/* $Id: rdataset.h,v 1.39 2001/03/28 00:22:16 gson Exp $ */
+/* $Id: rdataset.h,v 1.40 2001/06/05 09:02:16 marka Exp $ */
 
 #ifndef DNS_RDATASET_H
 #define DNS_RDATASET_H 1
@@ -355,6 +355,34 @@ dns_rdataset_towiresorted(dns_rdataset_t *rdataset,
  *	that order_arg is NULL if and only if order is NULL.
  */
 
+isc_result_t
+dns_rdataset_towirepartial(dns_rdataset_t *rdataset,
+			   dns_name_t *owner_name,
+			   dns_compress_t *cctx,
+			   isc_buffer_t *target,
+			   dns_rdatasetorderfunc_t order,
+			   void *order_arg,
+			   unsigned int *countp,
+			   void **state);
+/*
+ * Like dns_rdataset_towiresorted() except that a partial rdataset
+ * may be written.
+ *
+ * Requires:
+ *	All the requirements of dns_rdataset_towiresorted().
+ *	If 'state' is non NULL then the current position in the
+ *	rdataset will be remembered if the rdataset in not
+ *	completely written and should be passed on on subsequent
+ *	calls (NOT CURRENTLY IMPLEMENTED).
+ *
+ * Returns:
+ *	ISC_R_SUCCESS if all of the records were written.
+ *	ISC_R_NOSPACE if unable to fit in all of the records. *countp
+ *		      will be updated to reflect the number of records
+ *		      written.
+ */
+
+
 isc_result_t
 dns_rdataset_additionaldata(dns_rdataset_t *rdataset,
 			    dns_additionaldatafunc_t add, void *arg);
diff --git a/lib/dns/message.c b/lib/dns/message.c
index 979ee6d893..6410fb1341 100644
--- a/lib/dns/message.c
+++ b/lib/dns/message.c
@@ -15,7 +15,7 @@
  * WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  */
 
-/* $Id: message.c,v 1.190 2001/04/19 18:28:35 bwelling Exp $ */
+/* $Id: message.c,v 1.191 2001/06/05 09:02:11 marka Exp $ */
 
 /***
  *** Imports
@@ -1723,6 +1723,7 @@ dns_message_rendersection(dns_message_t *msg, dns_section_t sectionid,
 	isc_result_t result;
 	isc_buffer_t st; /* for rollbacks */
 	int pass;
+	isc_boolean_t partial = ISC_FALSE;
 
 	REQUIRE(DNS_MESSAGE_VALID(msg));
 	REQUIRE(msg->buffer != NULL);
@@ -1742,6 +1743,8 @@ dns_message_rendersection(dns_message_t *msg, dns_section_t sectionid,
 	msg->buffer->length -= msg->reserved;
 
 	total = 0;
+	if (msg->reserved == 0 && (options & DNS_MESSAGERENDER_PARTIAL) != 0)
+		partial = ISC_TRUE;
 
 	do {
 		name = ISC_LIST_HEAD(*section);
@@ -1771,7 +1774,19 @@ dns_message_rendersection(dns_message_t *msg, dns_section_t sectionid,
 				st = *(msg->buffer);
 
 				count = 0;
-				result = dns_rdataset_towiresorted(rdataset,
+				if (partial)
+					result = dns_rdataset_towirepartial(
+							  rdataset,
+							  name,
+							  msg->cctx,
+							  msg->buffer,
+							  msg->order,
+							  msg->order_arg,
+							  &count,
+							  NULL);
+				else
+					result = dns_rdataset_towiresorted(
+							  rdataset,
 							  name,
 							  msg->cctx,
 							  msg->buffer,
@@ -1794,6 +1809,11 @@ dns_message_rendersection(dns_message_t *msg, dns_section_t sectionid,
 				 * somewhere (probably in the message struct)
 				 * to indicate where to continue from.
 				 */
+				if (partial && result == ISC_R_NOSPACE) {
+					msg->buffer->length += msg->reserved;
+					msg->counts[sectionid] += total;
+					return (result);
+				}
 				if (result != ISC_R_SUCCESS) {
 					INSIST(st.used < 65536);
 					dns_compress_rollback(msg->cctx,
diff --git a/lib/dns/rdataset.c b/lib/dns/rdataset.c
index 96b0f984a1..166c66cf90 100644
--- a/lib/dns/rdataset.c
+++ b/lib/dns/rdataset.c
@@ -15,7 +15,7 @@
  * WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  */
 
-/* $Id: rdataset.c,v 1.55 2001/01/09 21:51:23 bwelling Exp $ */
+/* $Id: rdataset.c,v 1.56 2001/06/05 09:02:13 marka Exp $ */
 
 #include <config.h>
 
@@ -269,19 +269,17 @@ towire_compare(const void *av, const void *bv) {
 	return (a->key - b->key);
 }
 
-isc_result_t
-dns_rdataset_towiresorted(dns_rdataset_t *rdataset,
-			  dns_name_t *owner_name,
-			  dns_compress_t *cctx,
-			  isc_buffer_t *target,
-			  dns_rdatasetorderfunc_t order,
-			  void *order_arg,
-			  unsigned int *countp)
+static isc_result_t
+towiresorted(dns_rdataset_t *rdataset, dns_name_t *owner_name,
+	     dns_compress_t *cctx, isc_buffer_t *target,
+	     dns_rdatasetorderfunc_t order, void *order_arg,
+	     isc_boolean_t partial, unsigned int *countp,
+	     void **state)
 {
 	dns_rdata_t rdata = DNS_RDATA_INIT;
 	isc_region_t r;
 	isc_result_t result;
-	unsigned int i, count;
+	unsigned int i, count, added;
 	isc_buffer_t savedbuffer, rdlen;
 	unsigned int headlen;
 	isc_boolean_t question = ISC_FALSE;
@@ -289,6 +287,8 @@ dns_rdataset_towiresorted(dns_rdataset_t *rdataset,
 	dns_rdata_t shuffled[MAX_SHUFFLE];
 	struct towire_sort sorted[MAX_SHUFFLE];
 
+	UNUSED(state);
+
 	/*
 	 * Convert 'rdataset' to wire format, compressing names as specified
 	 * in cctx, and storing the result in 'target'.
@@ -376,6 +376,7 @@ dns_rdataset_towiresorted(dns_rdataset_t *rdataset,
 
 	savedbuffer = *target;
 	i = 0;
+	added = 0;
 
 	do {
 		/*
@@ -422,6 +423,7 @@ dns_rdataset_towiresorted(dns_rdataset_t *rdataset,
 			isc_buffer_putuint16(&rdlen,
 					     (isc_uint16_t)(target->used -
 							    rdlen.used - 2));
+			added++;
 		}
 
 		if (shuffle) {
@@ -443,6 +445,10 @@ dns_rdataset_towiresorted(dns_rdataset_t *rdataset,
 	return (ISC_R_SUCCESS);
 
  rollback:
+	if (partial && result == ISC_R_NOSPACE) {
+		*countp += added;
+		return (result);
+	}
 	INSIST(savedbuffer.used < 65536);
 	dns_compress_rollback(cctx, (isc_uint16_t)savedbuffer.used);
 	*countp = 0;
@@ -451,6 +457,34 @@ dns_rdataset_towiresorted(dns_rdataset_t *rdataset,
 	return (result);
 }
 
+isc_result_t
+dns_rdataset_towiresorted(dns_rdataset_t *rdataset,
+			  dns_name_t *owner_name,
+			  dns_compress_t *cctx,
+			  isc_buffer_t *target,
+			  dns_rdatasetorderfunc_t order,
+			  void *order_arg,
+			  unsigned int *countp)
+{
+	return (towiresorted(rdataset, owner_name, cctx, target,
+			     order, order_arg, ISC_FALSE, countp, NULL));
+}
+
+isc_result_t
+dns_rdataset_towirepartial(dns_rdataset_t *rdataset,
+			   dns_name_t *owner_name,
+			   dns_compress_t *cctx,
+			   isc_buffer_t *target,
+			   dns_rdatasetorderfunc_t order,
+			   void *order_arg,
+			   unsigned int *countp,
+			   void **state)
+{
+	REQUIRE(state == NULL);	/* XXX remove when implemented */
+	return (towiresorted(rdataset, owner_name, cctx, target,
+			     order, order_arg, ISC_TRUE, countp, state));
+}
+
 isc_result_t
 dns_rdataset_towire(dns_rdataset_t *rdataset,
 		    dns_name_t *owner_name,
@@ -458,8 +492,8 @@ dns_rdataset_towire(dns_rdataset_t *rdataset,
 		    isc_buffer_t *target,
 		    unsigned int *countp)
 {
-	return (dns_rdataset_towiresorted(rdataset, owner_name, cctx, target,
-					  NULL, NULL, countp));
+	return (towiresorted(rdataset, owner_name, cctx, target,
+			     NULL, NULL, ISC_FALSE, countp, NULL));
 }
 
 isc_result_t