From 9ece2f9ded8c65c7f20826f2ec9ae1f0527bdd7c Mon Sep 17 00:00:00 2001
From: Guus Sliepen <guus@meshlink.io>
Date: Thu, 31 Oct 2019 20:46:36 +0100
Subject: [PATCH] Try to get a new reflexive UDP address if UDP probes failed.

If we are sending data to a node, but we don't have working UDP, it could
be because we don't have a good reflexive UDP address. Send a dummy ANS_KEY
once in a while as long as we still want to exchange data.
---
 src/net_packet.c   |  7 +++++++
 src/node.h         |  1 +
 src/protocol_key.c | 26 ++++++++++++++------------
 3 files changed, 22 insertions(+), 12 deletions(-)

diff --git a/src/net_packet.c b/src/net_packet.c
index 53228369..0510b54b 100644
--- a/src/net_packet.c
+++ b/src/net_packet.c
@@ -102,6 +102,12 @@ static void send_mtu_probe_handler(event_loop_t *loop, void *data) {
 	}
 
 	if(n->mtuprobes == 31) {
+		if(!n->minmtu && n->status.want_udp) {
+			/* Send a dummy ANS_KEY to try to update the reflexive UDP address */
+			send_request(mesh, n->nexthop->connection, NULL, "%d %s %s . -1 -1 -1 0", ANS_KEY, mesh->self->name, n->name);
+			n->status.want_udp = false;
+		}
+
 		timeout = mesh->dev_class_traits[n->devclass].pinginterval;
 		goto end;
 	} else if(n->mtuprobes == 32) {
@@ -472,6 +478,7 @@ void send_packet(meshlink_handle_t *mesh, node_t *n, vpn_packet_t *packet) {
 
 	n->out_packets++;
 	n->out_bytes += packet->len;
+	n->status.want_udp = true;
 
 	send_sptps_packet(mesh, n, packet);
 	return;
diff --git a/src/node.h b/src/node.h
index 50ee141c..28464520 100644
--- a/src/node.h
+++ b/src/node.h
@@ -37,6 +37,7 @@ typedef struct node_status_t {
 	uint16_t destroyed: 1;              /* 1 if the node is being destroyed, deallocate channels when any callback is triggered */
 	uint16_t duplicate: 1;              /* 1 if the node is duplicate, ie. multiple nodes using the same Name are online */
 	uint16_t dirty: 1;                  /* 1 if the configuration of the node is dirty and needs to be written out */
+	uint16_t want_udp: 1;               /* 1 if we want working UDP because we have data to send */
 } node_status_t;
 
 typedef struct node_t {
diff --git a/src/protocol_key.c b/src/protocol_key.c
index 1d708e4a..f912c0fb 100644
--- a/src/protocol_key.c
+++ b/src/protocol_key.c
@@ -338,22 +338,24 @@ bool ans_key_h(meshlink_handle_t *mesh, connection_t *c, const char *request) {
 		return send_request(mesh, to->nexthop->connection, NULL, "%s", request);
 	}
 
-	/* Don't use key material until every check has passed. */
-	from->status.validkey = false;
+	/* Process SPTPS data if present */
 
-	/* Compression is not supported. */
-	if(compression != 0) {
-		logger(mesh, MESHLINK_ERROR, "Node %s uses bogus compression level!", from->name);
-		return true;
-	}
+	if(*key != '.') {
+		/* Don't use key material until every check has passed. */
+		from->status.validkey = false;
 
-	/* SPTPS or old-style key exchange? */
+		/* Compression is not supported. */
+		if(compression != 0) {
+			logger(mesh, MESHLINK_ERROR, "Node %s uses bogus compression level!", from->name);
+			return true;
+		}
 
-	char buf[strlen(key)];
-	int len = b64decode(key, buf, strlen(key));
+		char buf[strlen(key)];
+		int len = b64decode(key, buf, strlen(key));
 
-	if(!len || !sptps_receive_data(&from->sptps, buf, len)) {
-		logger(mesh, MESHLINK_ERROR, "Error processing SPTPS data from %s", from->name);
+		if(!len || !sptps_receive_data(&from->sptps, buf, len)) {
+			logger(mesh, MESHLINK_ERROR, "Error processing SPTPS data from %s", from->name);
+		}
 	}
 
 	if(from->status.validkey) {
-- 
2.39.2