server: Direct peer banning for old cfilter reqs.

This modifies the logic that bans peers for knowingly violating the
protocol by sending old committed filter requests to make use of the
newer BanPeer function directly and gives it a more descriptive ban
reason while here.

Author: davecgh

server.go

@@ -1663,12 +1663,15 @@ func (sp *serverPeer) enforceNodeCFFlag(cmd string) {
 	// Ban the peer if the protocol version is high enough that the peer is
 	// knowingly violating the protocol and banning is enabled.
 	//
-	// NOTE: Even though the addBanScore function already examines whether
-	// or not banning is enabled, it is checked here as well to ensure the
-	// violation is logged and the peer is disconnected regardless.
+	// NOTE: Even though BanPeer already examines whether or not banning is
+	// enabled, it is checked here as well to ensure the violation is logged and
+	// the peer is disconnected regardless.
 	if sp.ProtocolVersion() >= wire.NodeCFVersion && !cfg.DisableBanning {
-		// Disconnect the peer regardless of whether it was banned.
-		sp.addBanScore(100, 0, cmd)
+		reason := fmt.Sprintf("sent %s request with protocol version %d >= %d",
+			cmd, sp.ProtocolVersion(), wire.NodeCFVersion)
+		sp.server.BanPeer(sp, reason)
+
+		// Disconnect the peer regardless of whether it gets banned.
 		sp.Disconnect()
 		return
 	}