config+server: add ignore-historical-filters CLI option

This commit adds the ignore-historical-filters CLI option, initially
defaulting to false. Users may use this option to prevent lnd from doing
historical gossip dumps to peers that set their `gossip_timestamp_range`
in the past. Enabling this option will result in lower bandwidth and
memory consumption. Down the road the plan is to make this default to
true.

config.go

@@ -308,6 +308,8 @@ type config struct {
 	NumGraphSyncPeers      int           `long:"numgraphsyncpeers" description:"The number of peers that we should receive new graph updates from. This option can be tuned to save bandwidth for light clients or routing nodes."`
 	HistoricalSyncInterval time.Duration `long:"historicalsyncinterval" description:"The polling interval between historical graph sync attempts. Each historical graph sync attempt ensures we reconcile with the remote peer's graph from the genesis block."`
 
+	IgnoreHistoricalGossipFilters bool `long:"ignore-historical-gossip-filters" description:"If true, will not reply with historical data that matches the range specified by a remote peer's gossip_timestamp_filter. Doing so will result in lower memory and bandwidth requirements."`
+
 	RejectPush bool `long:"rejectpush" description:"If true, lnd will not accept channel opening requests with non-zero push amounts. This should prevent accidental pushes to merchant nodes."`
 
 	StaggerInitialReconnect bool `long:"stagger-initial-reconnect" description:"If true, will apply a randomized staggering between 0s and 30s when reconnecting to persistent peers on startup. The first 10 reconnections will be attempted instantly, regardless of the flag's value"`

server.go

@@ -730,6 +730,7 @@ func newServer(listenAddrs []net.Addr, chanDB *channeldb.DB,
 		NumActiveSyncers:        cfg.NumGraphSyncPeers,
 		MinimumBatchSize:        10,
 		SubBatchDelay:           time.Second * 5,
+		IgnoreHistoricalFilters: cfg.IgnoreHistoricalGossipFilters,
 	},
 		s.identityPriv.PubKey(),
 	)