multi: add new config options to tune gossip msg allocated bandwidth

We go with the defaults of if no values are set.

lncfg/gossip.go

@@ -5,6 +5,7 @@ import (
 	"time"
 
 	"github.com/lightningnetwork/lnd/discovery"
+	"github.com/lightningnetwork/lnd/lnwire"
 	"github.com/lightningnetwork/lnd/routing/route"
 )
 
@@ -32,6 +33,10 @@ type Gossip struct {
 	SubBatchDelay time.Duration `long:"sub-batch-delay" description:"The duration to wait before sending the next announcement batch if there are multiple. Use a small value if there are a lot announcements and they need to be broadcast quickly."`
 
 	AnnouncementConf uint32 `long:"announcement-conf" description:"The number of confirmations required before processing channel announcements."`
+
+	MsgRateBytes uint64 `long:"msg-rate-bytes" description:"The maximum number of bytes of gossip messages that will be sent per second. This is a global limit that applies to all peers."`
+
+	MsgBurstBytes uint64 `long:"msg-burst-bytes" description:"The maximum number of bytes of gossip messages that will be sent in a burst. This is a global limit that applies to all peers. This value should be set to something greater than 130 KB"`
 }
 
 // Parse the pubkeys for the pinned syncers.
@@ -58,6 +63,11 @@ func (g *Gossip) Validate() error {
 			"%v", g.AnnouncementConf, minAnnouncementConf)
 	}
 
+	if g.MsgBurstBytes < lnwire.MaxSliceLength {
+		return fmt.Errorf("msg-burst-bytes=%v must be at least %v",
+			g.MsgBurstBytes, lnwire.MaxSliceLength)
+	}
+
 	return nil
 }