change the signature of recv callbacks to include a result code

this will allow recv event handlers to distinguish between cases
in which the region is NULL because of error, shutdown, or cancelation.

lib/isc/include/isc/netmgr.h

@@ -122,26 +122,27 @@ isc_nmhandle_netmgr(isc_nmhandle_t *handle);
  * Return a pointer to the netmgr object for the given handle.
  */
 
-typedef void (*isc_nm_recv_cb_t)(isc_nmhandle_t *handle, isc_region_t *region,
-				 void *cbarg);
+typedef void (*isc_nm_recv_cb_t)(isc_nmhandle_t *handle, isc_result_t eresult,
+				 isc_region_t *region, void *cbarg);
 /*%<
  * Callback function to be used when receiving a packet.
  *
  * 'handle' the handle that can be used to send back the answer.
- * 'region' contains the received data. It will be freed after
- *          return by caller.
+ * 'eresult' the result of the event.
+ * 'region' contains the received data, if any. It will be freed
+ *          after return by caller.
  * 'cbarg'  the callback argument passed to isc_nm_listenudp(),
  *          isc_nm_listentcpdns(), or isc_nm_read().
  */
 
-typedef void (*isc_nm_cb_t)(isc_nmhandle_t *handle, isc_result_t result,
+typedef void (*isc_nm_cb_t)(isc_nmhandle_t *handle, isc_result_t eresult,
 			    void *cbarg);
 /*%<
  * Callback function for other network completion events (send, connect,
  * accept).
  *
  * 'handle' the handle on which the event took place.
- * 'result' the result of the event.
+ * 'eresult' the result of the event.
  * 'cbarg'  the callback argument passed to isc_nm_send(),
  *          isc_nm_tcp_connect(), or isc_nm_listentcp()
  */

lib/isc/netmgr/tcp.c

@@ -582,7 +582,8 @@ readtimeout_cb(uv_timer_t *handle) {
 		isc_quota_detach(&sock->quota);
 	}
 	if (sock->rcb.recv != NULL) {
-		sock->rcb.recv(sock->tcphandle, NULL, sock->rcbarg);
+		sock->rcb.recv(sock->tcphandle, ISC_R_TIMEDOUT, NULL,
+			       sock->rcbarg);
 	}
 }
 
@@ -716,7 +717,8 @@ read_cb(uv_stream_t *stream, ssize_t nread, const uv_buf_t *buf) {
 					.length = nread };
 
 		if (sock->rcb.recv != NULL) {
-			sock->rcb.recv(sock->tcphandle, &region, sock->rcbarg);
+			sock->rcb.recv(sock->tcphandle, ISC_R_SUCCESS, &region,
+				       sock->rcbarg);
 		}
 
 		sock->read_timeout = (atomic_load(&sock->keepalive)
@@ -741,7 +743,7 @@ read_cb(uv_stream_t *stream, ssize_t nread, const uv_buf_t *buf) {
 	 */
 	if (sock->rcb.recv != NULL) {
 		isc__nm_incstats(sock->mgr, sock->statsindex[STATID_RECVFAIL]);
-		sock->rcb.recv(sock->tcphandle, NULL, sock->rcbarg);
+		sock->rcb.recv(sock->tcphandle, ISC_R_EOF, NULL, sock->rcbarg);
 	}
 
 	/*
@@ -1076,7 +1078,8 @@ isc__nm_tcp_shutdown(isc_nmsocket_t *sock) {
 	if (sock->type == isc_nm_tcpsocket && sock->tcphandle != NULL &&
 	    sock->rcb.recv != NULL)
 	{
-		sock->rcb.recv(sock->tcphandle, NULL, sock->rcbarg);
+		sock->rcb.recv(sock->tcphandle, ISC_R_CANCELED, NULL,
+			       sock->rcbarg);
 	}
 }
 

lib/isc/netmgr/tcpdns.c

@@ -38,7 +38,8 @@
  */
 
 static void
-dnslisten_readcb(isc_nmhandle_t *handle, isc_region_t *region, void *arg);
+dnslisten_readcb(isc_nmhandle_t *handle, isc_result_t eresult,
+		 isc_region_t *region, void *arg);
 
 static void
 resume_processing(void *arg);
@@ -187,7 +188,7 @@ processbuffer(isc_nmsocket_t *dnssock, isc_nmhandle_t **handlep) {
 
 		if (listener != NULL && listener->rcb.recv != NULL) {
 			listener->rcb.recv(
-				dnshandle,
+				dnshandle, ISC_R_SUCCESS,
 				&(isc_region_t){ .base = dnssock->buf + 2,
 						 .length = len },
 				listener->rcbarg);
@@ -212,7 +213,8 @@ processbuffer(isc_nmsocket_t *dnssock, isc_nmhandle_t **handlep) {
  * a complete DNS packet and, if so - call the callback
  */
 static void
-dnslisten_readcb(isc_nmhandle_t *handle, isc_region_t *region, void *arg) {
+dnslisten_readcb(isc_nmhandle_t *handle, isc_result_t eresult,
+		 isc_region_t *region, void *arg) {
 	isc_nmsocket_t *dnssock = (isc_nmsocket_t *)arg;
 	unsigned char *base = NULL;
 	bool done = false;
@@ -222,9 +224,10 @@ dnslisten_readcb(isc_nmhandle_t *handle, isc_region_t *region, void *arg) {
 	REQUIRE(VALID_NMHANDLE(handle));
 	REQUIRE(dnssock->tid == isc_nm_tid());
 
-	if (region == NULL) {
+	if (region == NULL || eresult != ISC_R_SUCCESS) {
 		/* Connection closed */
 		isc_nmhandle_unref(handle);
+		dnssock->result = eresult;
 		if (dnssock->self != NULL) {
 			isc__nmsocket_detach(&dnssock->self);
 		}

lib/isc/netmgr/udp.c

@@ -364,7 +364,7 @@ udp_recv_cb(uv_udp_t *handle, ssize_t nrecv, const uv_buf_t *buf,
 	region.length = nrecv;
 
 	INSIST(sock->rcb.recv != NULL);
-	sock->rcb.recv(nmhandle, &region, sock->rcbarg);
+	sock->rcb.recv(nmhandle, ISC_R_SUCCESS, &region, sock->rcbarg);
 	if (free_buf) {
 		isc__nm_free_uvbuf(sock, buf);
 	}

lib/ns/client.c

@@ -1620,7 +1620,8 @@ ns__client_put_cb(void *client0) {
  * or tcpmsg (TCP case).
  */
 void
-ns__client_request(isc_nmhandle_t *handle, isc_region_t *region, void *arg) {
+ns__client_request(isc_nmhandle_t *handle, isc_result_t eresult,
+		   isc_region_t *region, void *arg) {
 	ns_client_t *client;
 	bool newclient = false;
 	ns_clientmgr_t *mgr;
@@ -1644,6 +1645,8 @@ ns__client_request(isc_nmhandle_t *handle, isc_region_t *region, void *arg) {
 #endif /* ifdef HAVE_DNSTAP */
 	ifp = (ns_interface_t *)arg;
 
+	UNUSED(eresult);
+
 	mgr = ifp->clientmgr;
 	if (mgr == NULL) {
 		/* The interface was shut down in the meantime, just bail */

lib/ns/include/ns/client.h

@@ -468,7 +468,8 @@ ns_client_addopt(ns_client_t *client, dns_message_t *message,
  */
 
 void
-ns__client_request(isc_nmhandle_t *handle, isc_region_t *region, void *arg);
+ns__client_request(isc_nmhandle_t *handle, isc_result_t eresult,
+		   isc_region_t *region, void *arg);
 
 /*%<
  * Handle client requests.