Introduce DTLS transport for NNG.

This introduces a new experimental transport for DTLS, that
provides encryption over UDP.  It has a simpler protocol than
the current UDP SP protocol (but we intend to fix that by making
the UDP transport simpler in a follow up!)

There are a few other fixes in the TLS layer itself, and in
the build, that were needed to accomplish this work.

Also there was an endianness bug in the UDP protocol handling, which
is fixed here.

1 files changed, 15 insertions, 10 deletions

diff --git a/src/supplemental/tls/tls_stream.c b/src/supplemental/tls/tls_stream.c
index 8a7f26d8..cd248686 100644
--- a/src/supplemental/tls/tls_stream.c
+++ b/src/supplemental/tls/tls_stream.c
@@ -110,9 +110,10 @@ tls_stream_recv(void *arg, nng_aio *aio)
 static void
 tls_stream_conn_cb(void *arg)
 {
-	tls_stream *ts = arg;
-	nng_stream *bio;
-	int         rv;
+	tls_stream  *ts = arg;
+	nng_stream  *bio;
+	int          rv;
+	nng_sockaddr sa;
 
 	if ((rv = nni_aio_result(&ts->conn_aio)) != 0) {
 		nni_aio_finish_error(ts->user_aio, rv);
@@ -121,8 +122,13 @@ tls_stream_conn_cb(void *arg)
 	}
 
 	bio = nni_aio_get_output(&ts->conn_aio, 0);
+	if ((rv = nng_stream_get_addr(bio, NNG_OPT_REMADDR, &sa)) != 0) {
+		nni_aio_finish_error(ts->user_aio, rv);
+		nni_tls_stream_free(ts);
+		return;
+	};
 
-	if ((rv = nni_tls_start(&ts->conn, &tls_stream_bio, bio)) != 0) {
+	if ((rv = nni_tls_start(&ts->conn, &tls_stream_bio, bio, &sa)) != 0) {
 		// NB: if this fails, it *will* have set the bio either way.
 		// So nni_tls_stream_free will also free the bio.
 		nni_aio_finish_error(ts->user_aio, rv);
@@ -140,13 +146,12 @@ static nng_err tls_stream_get(
 int
 nni_tls_stream_alloc(tls_stream **tsp, nng_tls_config *cfg, nng_aio *user_aio)
 {
-	tls_stream           *ts;
-	const nng_tls_engine *eng;
-	size_t                size;
-	int                   rv;
+	tls_stream *ts;
+	size_t      size;
+	int         rv;
 
-	eng  = cfg->engine;
-	size = NNI_ALIGN_UP(sizeof(*ts)) + eng->conn_ops->size;
+	size = NNI_ALIGN_UP(sizeof(*ts)) +
+	    NNI_ALIGN_UP(nni_tls_engine_conn_size());
 
 	if ((ts = nni_zalloc(size)) == NULL) {
 		return (NNG_ENOMEM);