net-test: packetdrill encap support: refactor packet receive loops into one loop

Factor out the packet sniffing loop that's common to local and remote
mode, since it is nearly identical in both cases. This is in
preparation for fixing a bug that is found in both loops, so we can
make the fix in just one place.


Change-Id: Ic9a9b84b66a9f812866b1e29cd7c897f7c1d40cf

gtests/net/packetdrill/netdev.c

@@ -370,21 +370,28 @@ static int local_netdev_receive(struct netdev *a_netdev,
 
 	DEBUGP("local_netdev_receive\n");
 
+	return netdev_receive_loop(netdev->psock, PACKET_LAYER_3_IP,
+				   packet, error);
+}
+
+int netdev_receive_loop(struct packet_socket *psock,
+			enum packet_layer_t layer,
+			struct packet **packet,
+			char **error)
+{
 	assert(*packet == NULL);	/* should be no packet yet */
 	*packet = packet_new(PACKET_READ_BYTES);
 
 	while (1) {
 		int in_bytes = 0;
+		enum packet_parse_result_t result;
 
 		/* Sniff the next outbound packet from the kernel under test. */
-		if (packet_socket_receive(netdev->psock,
-					  DIRECTION_OUTBOUND,
+		if (packet_socket_receive(psock, DIRECTION_OUTBOUND,
 					  *packet, &in_bytes))
 			continue;
 
-		enum packet_parse_result_t result =
-			parse_packet(*packet, in_bytes,
-					     PACKET_LAYER_3_IP, error);
+		result = parse_packet(*packet, in_bytes, layer, error);
 		if (result == PACKET_OK) {
 			return STATUS_OK;
 		} else if (result == PACKET_BAD) {
@@ -392,7 +399,8 @@ static int local_netdev_receive(struct netdev *a_netdev,
 			*packet = NULL;
 			return STATUS_ERR;
 		} else {
-			DEBUGP("error parsing packet: %s\n", *error);
+			DEBUGP("parse_result:%d; error parsing packet: %s\n",
+			       result, *error);
 		}
 	}
 

gtests/net/packetdrill/netdev.h

@@ -30,6 +30,8 @@
 
 #include "config.h"
 #include "packet.h"
+#include "packet_parser.h"
+#include "packet_socket.h"
 
 struct netdev_ops;
 
@@ -79,6 +81,16 @@ static inline int netdev_receive(struct netdev *netdev,
 	return netdev->ops->receive(netdev, packet, error);
 }
 
+
+/* Keep sniffing packets leaving the kernel until we see one we know
+ * about and can parse. Return a pointer to the newly-allocated
+ * packet. Caller must free the packet with packet_free().
+ */
+extern int netdev_receive_loop(struct packet_socket *psock,
+			       enum packet_layer_t layer,
+			       struct packet **packet,
+			       char **error);
+
 /* Allocate and return a new netdev for purely local tests. */
 extern struct netdev *local_netdev_new(struct config *config);
 

gtests/net/packetdrill/wire_server_netdev.c

@@ -191,36 +191,8 @@ static int wire_server_netdev_receive(struct netdev *a_netdev,
 
 	DEBUGP("wire_server_netdev_receive\n");
 
-	assert(*packet == NULL);	/* should be no packet yet */
-	*packet = packet_new(PACKET_READ_BYTES);
-
-	while (1) {
-		int in_bytes = 0;
-		enum packet_parse_result_t result;
-
-		/* Sniff the next inbound packet from the kernel under test. */
-		if (packet_socket_receive(netdev->psock,
-					  DIRECTION_INBOUND,
-					  *packet, &in_bytes))
-			continue;
-
-		result = parse_packet(*packet, in_bytes,
-					      PACKET_LAYER_2_ETHERNET,
-					      error);
-		if (result == PACKET_OK) {
-			return STATUS_OK;
-		} else if (result == PACKET_BAD) {
-			packet_free(*packet);
-			*packet = NULL;
-			return STATUS_ERR;
-		} else {
-			/* TODO: print these packets in verbose mode? */
-			DEBUGP("parse_result:%d; error parsing packet: %s\n",
-			       result, *error);
-		}
-	}
-
-	return STATUS_ERR;
+	return netdev_receive_loop(netdev->psock, PACKET_LAYER_2_ETHERNET,
+				   packet, error);
 }
 
 struct netdev_ops wire_server_netdev_ops = {