diff --git a/bin/named/tcpclient.c b/bin/named/tcpclient.c
index 09e157dd31..3b4dd3165e 100644
--- a/bin/named/tcpclient.c
+++ b/bin/named/tcpclient.c
@@ -219,7 +219,7 @@ tcp_recv_len(isc_task_t *task, isc_event_t *event)
 	region.base = ctx->buf;
 	region.length = ctx->buflen;
 
-	isc_socket_recv(sock, &region, ISC_FALSE,
+	isc_socket_recv(sock, &region, 0,
 			task, tcp_recv_req, event->arg);
 
 	isc_event_free(&event);
@@ -349,7 +349,7 @@ tcp_accept(isc_task_t *task, isc_event_t *event)
 	region.length = 2;
 	region.base = (unsigned char *)&ctx->buflen;
 
-	RUNTIME_CHECK(isc_socket_recv(ctx->csock, &region, ISC_FALSE, task,
+	RUNTIME_CHECK(isc_socket_recv(ctx->csock, &region, 0, task,
 				      tcp_recv_len, ctx)
 		      == ISC_R_SUCCESS);
 
@@ -399,7 +399,7 @@ tcp_send(isc_task_t *task, isc_event_t *event)
 	 */
 	region.base = (unsigned char *)&ctx->buflen;
 	region.length = 2;
-	isc_socket_recv(sock, &region, ISC_FALSE, task, tcp_recv_len, ctx);
+	isc_socket_recv(sock, &region, 0, task, tcp_recv_len, ctx);
 
 	isc_event_free(&event);
 }
diff --git a/bin/named/udpclient.c b/bin/named/udpclient.c
index e2616019ae..e0ac602082 100644
--- a/bin/named/udpclient.c
+++ b/bin/named/udpclient.c
@@ -177,7 +177,7 @@ udp_recv(isc_task_t *task, isc_event_t *event)
 				  &dev->address);
 	} else {
 		/* Send no reply, just wait for the next request. */
-		isc_socket_recv(sock, &region, ISC_FALSE, task, udp_recv, ctx);
+		isc_socket_recv(sock, &region, 0, task, udp_recv, ctx);
 	}
 
 	isc_event_free(&event);
@@ -218,7 +218,7 @@ udp_send(isc_task_t *task, isc_event_t *event)
 
 	region.base = ctx->buf;
 	region.length = UDP_INPUT_BUFFER_SIZE;
-	isc_socket_recv(sock, &region, ISC_FALSE, task, udp_recv, ctx);
+	isc_socket_recv(sock, &region, 0, task, udp_recv, ctx);
 
 	isc_event_free(&event);
 }
@@ -309,7 +309,7 @@ udp_listener_start(udp_listener_t *l,
 		region.base = l->ctxs[i]->buf;
 
 		RUNTIME_CHECK(isc_socket_recv(sock, &region,
-					      ISC_FALSE, l->tasks[i],
+					      0, l->tasks[i],
 					      udp_recv, l->ctxs[i])
 			      == ISC_R_SUCCESS);
 
diff --git a/bin/tests/sock_test.c b/bin/tests/sock_test.c
index 5a865f5684..4d443598cc 100644
--- a/bin/tests/sock_test.c
+++ b/bin/tests/sock_test.c
@@ -84,7 +84,7 @@ my_recv(isc_task_t *task, isc_event_t *event)
 	if (strcmp(event->arg, "so2") != 0) {
 		region = dev->region;
 		sprintf(buf, "\r\nReceived: %.*s\r\n\r\n",
-			(int)region.length, (char *)region.base);
+			(int)dev->n, (char *)region.base);
 		region.base = isc_mem_get(mctx, strlen(buf) + 1);
 		region.length = strlen(buf) + 1;
 		strcpy((char *)region.base, buf);  /* strcpy is safe */
@@ -92,11 +92,10 @@ my_recv(isc_task_t *task, isc_event_t *event)
 	} else {
 		region = dev->region;
 		printf("\r\nReceived: %.*s\r\n\r\n",
-		       (int)region.length, (char *)region.base);
+		       (int)dev->n, (char *)region.base);
 	}
 
-	isc_socket_recv(sock, &dev->region, ISC_FALSE,
-			task, my_recv, event->arg);
+	isc_socket_recv(sock, &dev->region, 1, task, my_recv, event->arg);
 
 	isc_event_free(&event);
 }
@@ -146,8 +145,7 @@ my_http_get(isc_task_t *task, isc_event_t *event)
 		return;
 	}
 
-	isc_socket_recv(sock, &dev->region, ISC_FALSE, task, my_recv,
-			event->arg);
+	isc_socket_recv(sock, &dev->region, 1, task, my_recv, event->arg);
 
 	isc_event_free(&event);
 }
@@ -218,7 +216,7 @@ my_listen(isc_task_t *task, isc_event_t *event)
 		newtask = NULL;
 		RUNTIME_CHECK(isc_task_create(manager, NULL, 0, &newtask)
 			      == ISC_R_SUCCESS);
-		isc_socket_recv(dev->newsocket, &region, ISC_FALSE,
+		isc_socket_recv(dev->newsocket, &region, 1,
 				newtask, my_recv, event->arg);
 		isc_task_detach(&newtask);
 	} else {
diff --git a/lib/dns/dispatch.c b/lib/dns/dispatch.c
index 192e5c9663..5b6677027d 100644
--- a/lib/dns/dispatch.c
+++ b/lib/dns/dispatch.c
@@ -761,7 +761,7 @@ startrecv(dns_dispatch_t *disp)
 				return;
 			XDEBUG(("Recv into %p, length %d\n", region.base,
 				region.length));
-			res = isc_socket_recv(disp->socket, &region, ISC_TRUE,
+			res = isc_socket_recv(disp->socket, &region, 1,
 					      disp->task, udp_recv, disp);
 			if (res != ISC_R_SUCCESS) {
 				disp->shutdown_why = res;
diff --git a/lib/dns/tcpmsg.c b/lib/dns/tcpmsg.c
index d95bbafad1..922f2d7481 100644
--- a/lib/dns/tcpmsg.c
+++ b/lib/dns/tcpmsg.c
@@ -81,7 +81,7 @@ recv_length(isc_task_t *task, isc_event_t *ev_in)
 
 	isc_buffer_init(&tcpmsg->buffer, region.base, region.length,
 			ISC_BUFFERTYPE_BINARY);
-	result = isc_socket_recv(tcpmsg->sock, &region, ISC_FALSE,
+	result = isc_socket_recv(tcpmsg->sock, &region, 0,
 				 task, recv_message, tcpmsg);
 	if (result != ISC_R_SUCCESS) {
 		tcpmsg->result = result;
@@ -188,7 +188,7 @@ dns_tcpmsg_readmessage(dns_tcpmsg_t *tcpmsg,
 
 	region.base = (unsigned char *)&tcpmsg->size;
 	region.length = 2;  /* isc_uint16_t */
-	result = isc_socket_recv(tcpmsg->sock, &region, ISC_FALSE,
+	result = isc_socket_recv(tcpmsg->sock, &region, 0,
 				 tcpmsg->task, recv_length, tcpmsg);
 
 	if (result != ISC_R_SUCCESS)
diff --git a/lib/isc/include/isc/socket.h b/lib/isc/include/isc/socket.h
index c8b339ab1f..b0392f3dcb 100644
--- a/lib/isc/include/isc/socket.h
+++ b/lib/isc/include/isc/socket.h
@@ -82,7 +82,7 @@ typedef struct isc_socketevent  isc_socketevent_t;
 struct isc_socketevent {
 	ISC_EVENT_COMMON(isc_socketevent_t);
 	isc_result_t		result;		/* OK, EOF, whatever else */
-	isc_boolean_t		partial;	/* partial i/o ok */
+	unsigned int		minimum;	/* minimum i/o for event */
 	unsigned int		n;		/* bytes read or written */
 	isc_region_t		region;		/* the region info */
 	isc_sockaddr_t		address;	/* source address */
@@ -113,12 +113,8 @@ struct isc_socket_connev {
 /*
  * Internal events.
  */
-#define ISC_SOCKEVENT_INTRECV	(ISC_EVENTCLASS_SOCKET + 257)
-#define ISC_SOCKEVENT_INTSEND	(ISC_EVENTCLASS_SOCKET + 258)
-#define ISC_SOCKEVENT_INTACCEPT	(ISC_EVENTCLASS_SOCKET + 259)
-#define ISC_SOCKEVENT_INTCONN	(ISC_EVENTCLASS_SOCKET + 260)
-#define ISC_SOCKEVENT_INTR	(ISC_EVENTCLASS_SOCKET + 261)
-#define ISC_SOCKEVENT_INTW	(ISC_EVENTCLASS_SOCKET + 262)
+#define ISC_SOCKEVENT_INTR	(ISC_EVENTCLASS_SOCKET + 256)
+#define ISC_SOCKEVENT_INTW	(ISC_EVENTCLASS_SOCKET + 257)
 
 typedef enum {
 	isc_sockettype_udp = 1,
@@ -413,7 +409,7 @@ isc_socket_getsockname(isc_socket_t *sock, isc_sockaddr_t *addressp);
 
 isc_result_t
 isc_socket_recv(isc_socket_t *sock, isc_region_t *region,
-		isc_boolean_t partial,
+		unsigned int minimum,
 		isc_task_t *task, isc_taskaction_t action, void *arg);
 /*
  * Receive from 'socket', storing the results in region.
@@ -422,17 +418,17 @@ isc_socket_recv(isc_socket_t *sock, isc_region_t *region,
  *
  *	Let 'length' refer to the length of 'region'.
  *
- *	If 'partial' is true, then at most 'length' bytes will be read.
- *	Otherwise the read will not complete until exactly 'length' bytes
- *	have been read.
+ *	If 'minimum' is non-zero and at least that many bytes are read,
+ *	the completion event will be posted to the task 'task.'  If minimum
+ *	is zero, the exact number of bytes requested in the region must
+ * 	be read for an event to be posted.  This only makes sense for TCP
+ *	connections, and is always set to the full buffer for UDP.
  *
  *	The read will complete when the desired number of bytes have been
  *	read, if end-of-input occurs, or if an error occurs.  A read done
  *	event with the given 'action' and 'arg' will be posted to the
  *	event queue of 'task'.
  *
- *	Partial reads are always turned on for UDP.
- *
  *	The caller may neither read from nor write to 'region' until it
  *	has received the read completion event.
  *
diff --git a/lib/isc/unix/socket.c b/lib/isc/unix/socket.c
index b55feb55c9..9d501e7d51 100644
--- a/lib/isc/unix/socket.c
+++ b/lib/isc/unix/socket.c
@@ -359,7 +359,7 @@ allocate_socket(isc_socketmgr_t *manager, isc_sockettype_t type,
 		       ISC_EVENTATTR_NOPURGE, NULL, ISC_SOCKEVENT_INTR,
 		       NULL, sock, sock, NULL, NULL);
 	ISC_EVENT_INIT(&sock->writable_ev, sizeof(intev_t),
-		       ISC_EVENTATTR_NOPURGE, NULL, ISC_SOCKEVENT_INTR,
+		       ISC_EVENTATTR_NOPURGE, NULL, ISC_SOCKEVENT_INTW,
 		       NULL, sock, sock, NULL, NULL);
 
 	sock->magic = SOCKET_MAGIC;
@@ -835,6 +835,8 @@ internal_recv(isc_task_t *me, isc_event_t *ev)
 
 	(void)me;
 
+	INSIST(ev->type == ISC_SOCKEVENT_INTR);
+
 	sock = ev->sender;
 	REQUIRE(VALID_SOCKET(sock));
 
@@ -965,7 +967,7 @@ internal_recv(isc_task_t *me, isc_event_t *ev)
 			 * was read with a success result, and continue
 			 * the loop.
 			 */
-			if (dev->partial) {
+			if (dev->minimum >= dev->n) {
 				send_recvdone_event(sock, &task, &dev,
 						    ISC_R_SUCCESS, 1);
 				goto next;
@@ -1010,6 +1012,8 @@ internal_send(isc_task_t *me, isc_event_t *ev)
 
 	(void)me;
 
+	INSIST(ev->type == ISC_SOCKEVENT_INTW);
+
 	/*
 	 * Find out what socket this is and lock it.
 	 */
@@ -1544,9 +1548,8 @@ isc_socketmgr_destroy(isc_socketmgr_t **managerp)
 }
 
 isc_result_t
-isc_socket_recv(isc_socket_t *sock, isc_region_t *region,
-		isc_boolean_t partial, isc_task_t *task,
-		isc_taskaction_t action, void *arg)
+isc_socket_recv(isc_socket_t *sock, isc_region_t *region, unsigned int minimum,
+		isc_task_t *task, isc_taskaction_t action, void *arg)
 {
 	isc_socketevent_t *dev;
 	isc_socketmgr_t *manager;
@@ -1557,6 +1560,7 @@ isc_socket_recv(isc_socket_t *sock, isc_region_t *region,
 	REQUIRE(VALID_SOCKET(sock));
 	manager = sock->manager;
 	REQUIRE(VALID_MANAGER(manager));
+	REQUIRE(region->length >= minimum);
 
 	LOCK(&sock->lock);
 
@@ -1574,12 +1578,17 @@ isc_socket_recv(isc_socket_t *sock, isc_region_t *region,
 	 * UDP sockets are always partial read
 	 */
 	if (sock->type == isc_sockettype_udp)
-		partial = ISC_TRUE;
+		dev->minimum = 1;
+	else {
+		if (minimum == 0)
+			dev->minimum = region->length;
+		else
+			dev->minimum = minimum;
+	}
 
 	dev->region = *region;
 	dev->n = 0;
 	dev->result = ISC_R_SUCCESS;
-	dev->partial = partial;
 
 	was_empty = ISC_LIST_EMPTY(sock->recv_list);
 
@@ -1666,7 +1675,7 @@ isc_socket_recv(isc_socket_t *sock, isc_region_t *region,
 	/*
 	 * Partial reads need to be queued
 	 */
-	if ((size_t)cc != dev->region.length && !partial)
+	if (((size_t)cc != dev->region.length) && (dev->n < dev->minimum))
 		goto queue;
 
 	/*
@@ -1742,7 +1751,7 @@ isc_socket_sendto(isc_socket_t *sock, isc_region_t *region,
 	dev->region = *region;
 	dev->n = 0;
 	dev->result = ISC_R_SUCCESS;
-	dev->partial = ISC_FALSE; /* doesn't matter */
+	dev->minimum = region->length;
 
 	was_empty = ISC_LIST_EMPTY(sock->send_list);
 
@@ -2424,7 +2433,7 @@ isc_socket_recvmark(isc_socket_t *sock,
 	isc_task_attach(task, &ntask);
 
 	dev->result = ISC_R_SUCCESS;
-	dev->partial = ISC_FALSE; /* doesn't matter */
+	dev->minimum = 0;
 	dev->sender = ntask;
 
 	ISC_LIST_ENQUEUE(sock->recv_list, dev, link);
@@ -2481,7 +2490,7 @@ isc_socket_sendmark(isc_socket_t *sock,
 	isc_task_attach(task, &ntask);
 
 	dev->result = ISC_R_SUCCESS;
-	dev->partial = ISC_FALSE; /* doesn't matter */
+	dev->minimum = 0;
 	dev->sender = ntask;
 
 	ISC_LIST_ENQUEUE(sock->send_list, dev, link);