test/vsock: new skbuff appending test

This adds test which checks case when data of newly received skbuff is
appended to the last skbuff in the socket's queue. It looks like simple
test with 'send()' and 'recv()', but internally it triggers logic which
appends one received skbuff to another. Test checks that this feature
works correctly.

This test is actual only for virtio transport.
Signed-off-by: Arseniy Krasnov <AVKrasnov@sberdevices.ru>
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

tools/testing/vsock/vsock_test.c

@@ -968,6 +968,91 @@ static void test_seqpacket_inv_buf_server(const struct test_opts *opts)
 	test_inv_buf_server(opts, false);
 }
 
+#define HELLO_STR "HELLO"
+#define WORLD_STR "WORLD"
+
+static void test_stream_virtio_skb_merge_client(const struct test_opts *opts)
+{
+	ssize_t res;
+	int fd;
+
+	fd = vsock_stream_connect(opts->peer_cid, 1234);
+	if (fd < 0) {
+		perror("connect");
+		exit(EXIT_FAILURE);
+	}
+
+	/* Send first skbuff. */
+	res = send(fd, HELLO_STR, strlen(HELLO_STR), 0);
+	if (res != strlen(HELLO_STR)) {
+		fprintf(stderr, "unexpected send(2) result %zi\n", res);
+		exit(EXIT_FAILURE);
+	}
+
+	control_writeln("SEND0");
+	/* Peer reads part of first skbuff. */
+	control_expectln("REPLY0");
+
+	/* Send second skbuff, it will be appended to the first. */
+	res = send(fd, WORLD_STR, strlen(WORLD_STR), 0);
+	if (res != strlen(WORLD_STR)) {
+		fprintf(stderr, "unexpected send(2) result %zi\n", res);
+		exit(EXIT_FAILURE);
+	}
+
+	control_writeln("SEND1");
+	/* Peer reads merged skbuff packet. */
+	control_expectln("REPLY1");
+
+	close(fd);
+}
+
+static void test_stream_virtio_skb_merge_server(const struct test_opts *opts)
+{
+	unsigned char buf[64];
+	ssize_t res;
+	int fd;
+
+	fd = vsock_stream_accept(VMADDR_CID_ANY, 1234, NULL);
+	if (fd < 0) {
+		perror("accept");
+		exit(EXIT_FAILURE);
+	}
+
+	control_expectln("SEND0");
+
+	/* Read skbuff partially. */
+	res = recv(fd, buf, 2, 0);
+	if (res != 2) {
+		fprintf(stderr, "expected recv(2) returns 2 bytes, got %zi\n", res);
+		exit(EXIT_FAILURE);
+	}
+
+	control_writeln("REPLY0");
+	control_expectln("SEND1");
+
+	res = recv(fd, buf + 2, sizeof(buf) - 2, 0);
+	if (res != 8) {
+		fprintf(stderr, "expected recv(2) returns 8 bytes, got %zi\n", res);
+		exit(EXIT_FAILURE);
+	}
+
+	res = recv(fd, buf, sizeof(buf) - 8 - 2, MSG_DONTWAIT);
+	if (res != -1) {
+		fprintf(stderr, "expected recv(2) failure, got %zi\n", res);
+		exit(EXIT_FAILURE);
+	}
+
+	if (memcmp(buf, HELLO_STR WORLD_STR, strlen(HELLO_STR WORLD_STR))) {
+		fprintf(stderr, "pattern mismatch\n");
+		exit(EXIT_FAILURE);
+	}
+
+	control_writeln("REPLY1");
+
+	close(fd);
+}
+
 static struct test_case test_cases[] = {
 	{
 		.name = "SOCK_STREAM connection reset",
@@ -1038,6 +1123,11 @@ static struct test_case test_cases[] = {
 		.run_client = test_seqpacket_inv_buf_client,
 		.run_server = test_seqpacket_inv_buf_server,
 	},
+	{
+		.name = "SOCK_STREAM virtio skb merge",
+		.run_client = test_stream_virtio_skb_merge_client,
+		.run_server = test_stream_virtio_skb_merge_server,
+	},
 	{},
 };