UDP: Signficant refactoring and simplification.

This work is inspired by the DTLS work, and harmonizes the UDP implementation
with DTLS somewhat.

This should make it more resilient to failures, although there is no longer any
attempt to guard against sequencing (reorders, dupes) errors.  Applications that
need such protection should either add it themselves, or use a transport which
provides that guarantee (such as TCP).  Note that with devices and and such in
the way, such guarantees have never been perfect with SP anyway.

The UDP transport header sizes for this are now just 8 bytes (beyond the UDP header
itself.

1 files changed, 61 insertions, 0 deletions

diff --git a/src/sp/transport/udp/udp_tran_test.c b/src/sp/transport/udp/udp_tran_test.c
index 0b4b180d..56a25cce 100644
--- a/src/sp/transport/udp/udp_tran_test.c
+++ b/src/sp/transport/udp/udp_tran_test.c
@@ -496,6 +496,66 @@ test_udp_pipe(void)
 	NUTS_CLOSE(s0);
 	NUTS_CLOSE(s1);
 }
+
+void
+test_udp_reconnect_dialer(void)
+{
+	nng_socket   s0;
+	nng_socket   s1;
+	nng_listener l;
+	nng_dialer   d;
+	char        *addr;
+	nng_msg     *msg;
+	nng_sockaddr sa0;
+
+	NUTS_LOGGING();
+	NUTS_ADDR(addr, "udp4");
+
+	// For this test, using PUB sub is better to avoid fighting the pair
+	// exclusion. Generally speaking pair is probably a poor fit for UDP
+	// anyway.
+
+	NUTS_PASS(nng_pub0_open(&s0));
+	NUTS_PASS(nng_socket_set_ms(s0, NNG_OPT_SENDTIMEO, 2000));
+	NUTS_PASS(nng_listener_create(&l, s0, addr));
+	NUTS_PASS(nng_listener_start(l, 0));
+	NUTS_PASS(nng_listener_get_addr(l, NNG_OPT_LOCADDR, &sa0));
+
+	NUTS_PASS(nng_sub0_open(&s1));
+	NUTS_PASS(nng_sub0_socket_subscribe(s1, "", 0));
+	NUTS_PASS(nng_socket_set_ms(s1, NNG_OPT_RECVTIMEO, 2000));
+	NUTS_PASS(nng_dialer_create(&d, s1, addr));
+	NUTS_PASS(nng_dialer_start(d, 0));
+
+	nng_msleep(500);
+
+	NUTS_PASS(nng_msg_alloc(&msg, 0));
+	NUTS_PASS(nng_sendmsg(s0, msg, 0));
+	NUTS_PASS(nng_recvmsg(s1, &msg, 0));
+	nng_msg_free(msg);
+
+	// now close the dialer
+	NUTS_PASS(nng_dialer_close(d));
+
+	// wait a bit before starting a new one -- allow for the old one to
+	// tear down completely on both ends.
+	nng_msleep(500);
+
+	// and create and start a new one
+	NUTS_PASS(nng_dialer_create(&d, s1, addr));
+	NUTS_PASS(nng_dialer_start(d, 0));
+	nng_msleep(500);
+
+	// show that we still send and receive
+	NUTS_PASS(nng_msg_alloc(&msg, 0));
+	NUTS_PASS(nng_sendmsg(s0, msg, 0));
+	NUTS_PASS(nng_recvmsg(s1, &msg, 0));
+	nng_msg_free(msg);
+
+	NUTS_CLOSE(s0);
+	NUTS_CLOSE(s1);
+}
+
 void
 test_udp_stats(void)
 {
@@ -559,6 +619,7 @@ NUTS_TESTS = {
 	{ "udp multi small burst", test_udp_multi_small_burst },
 	{ "udp crush", test_udp_crush },
 	{ "udp pipe", test_udp_pipe },
+	{ "udp reconnect dialer", test_udp_reconnect_dialer },
 	{ "udp stats", test_udp_stats },
 	{ NULL, NULL },
 };