gossipd: prune channels unless *both* peers have refreshed.

See https://github.com/lightningnetwork/lightning-rfc/pull/767

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Changelog-Changed: Protocol: channels now pruned after two weeks unless both peers refresh it (see lightning-rfc#767)

Makefile

@@ -24,7 +24,7 @@ CCANDIR := ccan
 
 # Where we keep the BOLT RFCs
 BOLTDIR := ../lightning-rfc/
-BOLTVERSION := b4132ff24025742ad8e175d52b68380520e9f0b7
+BOLTVERSION := 7e8c478aef0d23a445845b7d297b0e804583697c
 
 -include config.vars
 

common/gossip_constants.h

@@ -58,7 +58,7 @@
 /* BOLT #7:
  *
  * A node:
- *   - if a channel's latest `channel_update`s `timestamp` is older than two weeks
+ *   - if a channel's oldest `channel_update`s `timestamp` is older than two weeks
  *   (1209600 seconds):
  *     - MAY prune the channel.
  *     - MAY ignore the channel.

gossipd/gossipd.c

@@ -725,7 +725,7 @@ static void gossip_send_keepalive_update(struct daemon *daemon,
 /* BOLT #7:
  *
  * A node:
- *  - if a channel's latest `channel_update`s `timestamp` is older than two weeks
+ *  - if a channel's oldest `channel_update`s `timestamp` is older than two weeks
  *    (1209600 seconds):
  *     - MAY prune the channel.
  *     - MAY ignore the channel.

gossipd/routing.c

@@ -2777,10 +2777,16 @@ void route_prune(struct routing_state *rstate)
 		if (!is_chan_public(chan))
 			continue;
 
-		if ((!is_halfchan_defined(&chan->half[0])
+		/* BOLT #7:
-		     || chan->half[0].bcast.timestamp < highwater)
+		 *   - if a channel's oldest `channel_update`s `timestamp` is
-		    && (!is_halfchan_defined(&chan->half[1])
+		 *     older than two weeks (1209600 seconds):
-			|| chan->half[1].bcast.timestamp < highwater)) {
+		 *    - MAY prune the channel.
+		 */
+		/* This is a fancy way of saying "both ends must refresh!" */
+		if (!is_halfchan_defined(&chan->half[0])
+		    || chan->half[0].bcast.timestamp < highwater
+		    || !is_halfchan_defined(&chan->half[1])
+		    || chan->half[1].bcast.timestamp < highwater) {
 			status_debug(
 			    "Pruning channel %s from network view (ages %"PRIu64" and %"PRIu64"s)",
 			    type_to_string(tmpctx, struct short_channel_id,