gossipd: don't create redundant node_announcements.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

CHANGELOG.md

@@ -18,6 +18,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 ### Changed
 
 - Protocol: `channel_update` sent to disable channel only if we reject an HTLC.
+- Protocol: we don't send redundant `node_announcement` on every new channel.
 
 ### Deprecated
 

gossipd/gossipd.c

@@ -339,13 +339,49 @@ static void send_node_announcement(struct daemon *daemon)
 			      tal_hex(tmpctx, err));
 }
 
+/* Return true if the only change would be the timestamp. */
+static bool node_announcement_redundant(struct daemon *daemon)
+{
+	struct node *n = get_node(daemon->rstate, &daemon->id);
+	if (!n)
+		return false;
+
+	if (n->last_timestamp == -1)
+		return false;
+
+	if (tal_count(n->addresses) != tal_count(daemon->announcable))
+		return false;
+
+	for (size_t i = 0; i < tal_count(n->addresses); i++)
+		if (!wireaddr_eq(&n->addresses[i], &daemon->announcable[i]))
+			return false;
+
+	BUILD_ASSERT(ARRAY_SIZE(daemon->alias) == ARRAY_SIZE(n->alias));
+	if (!memeq(daemon->alias, ARRAY_SIZE(daemon->alias),
+		   n->alias, ARRAY_SIZE(n->alias)))
+		return false;
+
+	BUILD_ASSERT(ARRAY_SIZE(daemon->rgb) == ARRAY_SIZE(n->rgb_color));
+	if (!memeq(daemon->rgb, ARRAY_SIZE(daemon->rgb),
+		   n->rgb_color, ARRAY_SIZE(n->rgb_color)))
+		return false;
+
+	if (!memeq(daemon->globalfeatures, tal_count(daemon->globalfeatures),
+		   n->gfeatures, tal_count(n->gfeatures)))
+		return false;
+
+	return true;
+}
+
 /* Should we announce our own node? */
 static void maybe_send_own_node_announce(struct daemon *daemon)
 {
 	if (!daemon->rstate->local_channel_announced)
 		return;
 
-	/* FIXME: We may not need to retransmit here, if previous still valid. */
+	if (node_announcement_redundant(daemon))
+		return;
+
 	send_node_announcement(daemon);
 	daemon->rstate->local_channel_announced = false;
 }

tests/test_gossip.py

@@ -4,7 +4,6 @@ from utils import wait_for, TIMEOUT, only_one
 import json
 import logging
 import os
-import pytest
 import struct
 import subprocess
 import time
@@ -843,7 +842,6 @@ def test_gossip_store_load(node_factory):
     assert not l1.daemon.is_in_log('gossip_store.*truncating')
 
 
-@pytest.mark.xfail(strict=True)
 @unittest.skipIf(not DEVELOPER, "Needs fast gossip propagation")
 def test_node_reannounce(node_factory, bitcoind):
     "Test that we reannounce a node when parameters change"