Provide Dummy routing and channel message handlers for users

We currently "support" not having a router or channel in memory by
forcing users to implement the same, but its trivial to provide our
own dummy implementations.

Author: TheBlueMatt

lightning/src/ln/peer_handler.rs

@@ -33,22 +33,131 @@ use routing::network_graph::NetGraphMsgHandler;
 use std::collections::{HashMap,hash_map,HashSet,LinkedList};
 use std::sync::{Arc, Mutex};
 use std::sync::atomic::{AtomicUsize, Ordering};
-use std::{cmp,error,hash,fmt};
+use std::{cmp,error,hash,fmt,mem};
 use std::ops::Deref;
 
 use bitcoin::hashes::sha256::Hash as Sha256;
 use bitcoin::hashes::sha256::HashEngine as Sha256Engine;
 use bitcoin::hashes::{HashEngine, Hash};
 
+/// A dummy struct which implements `RoutingMessageHandler` without storing any routing information
+/// or doing any processing. You can provide one of these as the route_handler in a MessageHandler.
+pub struct DummyRouteHandler{}
+impl MessageSendEventsProvider for DummyRouteHandler {
+	fn get_and_clear_pending_msg_events(&self) -> Vec<MessageSendEvent> { Vec::new() }
+}
+impl RoutingMessageHandler for DummyRouteHandler {
+	fn handle_node_announcement(&self, _msg: &msgs::NodeAnnouncement) -> Result<bool, LightningError> { Ok(false) }
+	fn handle_channel_announcement(&self, _msg: &msgs::ChannelAnnouncement) -> Result<bool, LightningError> { Ok(false) }
+	fn handle_channel_update(&self, _msg: &msgs::ChannelUpdate) -> Result<bool, LightningError> { Ok(false) }
+	fn handle_htlc_fail_channel_update(&self, _update: &msgs::HTLCFailChannelUpdate) {}
+	fn get_next_channel_announcements(&self, _starting_point: u64, _batch_amount: u8) ->
+		Vec<(msgs::ChannelAnnouncement, Option<msgs::ChannelUpdate>, Option<msgs::ChannelUpdate>)> { Vec::new() }
+	fn get_next_node_announcements(&self, _starting_point: Option<&PublicKey>, _batch_amount: u8) -> Vec<msgs::NodeAnnouncement> { Vec::new() }
+	fn sync_routing_table(&self, _their_node_id: &PublicKey, _init: &msgs::Init) {}
+	fn handle_reply_channel_range(&self, _their_node_id: &PublicKey, _msg: msgs::ReplyChannelRange) -> Result<(), LightningError> { Ok(()) }
+	fn handle_reply_short_channel_ids_end(&self, _their_node_id: &PublicKey, _msg: msgs::ReplyShortChannelIdsEnd) -> Result<(), LightningError> { Ok(()) }
+	fn handle_query_channel_range(&self, _their_node_id: &PublicKey, _msg: msgs::QueryChannelRange) -> Result<(), LightningError> { Ok(()) }
+	fn handle_query_short_channel_ids(&self, _their_node_id: &PublicKey, _msg: msgs::QueryShortChannelIds) -> Result<(), LightningError> { Ok(()) }
+}
+impl Deref for DummyRouteHandler {
+	type Target = DummyRouteHandler;
+	fn deref(&self) -> &Self { self }
+}
+
+/// A dummy struct which implements `ChannelMessageHandler` without having any channels.
+/// You can provide one of these as the route_handler in a MessageHandler.
+pub struct DummyChannelHandler {
+	message_queue: Mutex<Vec<MessageSendEvent>>
+}
+impl DummyChannelHandler {
+	/// Constructs a new DummyChannelHandler
+	pub fn new() -> Self {
+		Self { message_queue: Mutex::new(Vec::new()) }
+	}
+	fn push_error(&self, node_id: &PublicKey, channel_id: [u8; 32]) {
+		self.message_queue.lock().unwrap().push(MessageSendEvent::HandleError {
+			action: msgs::ErrorAction::SendErrorMessage {
+				msg: msgs::ErrorMessage { channel_id, data: "We do not support channel messages, sorry.".to_owned() },
+			},
+			node_id: node_id.clone(),
+		});
+	}
+}
+impl MessageSendEventsProvider for DummyChannelHandler {
+	fn get_and_clear_pending_msg_events(&self) -> Vec<MessageSendEvent> {
+		let mut res = Vec::new();
+		mem::swap(&mut res, &mut self.message_queue.lock().unwrap());
+		res
+	}
+}
+impl ChannelMessageHandler for DummyChannelHandler {
+	fn handle_open_channel(&self, their_node_id: &PublicKey, _their_features: InitFeatures, msg: &msgs::OpenChannel) {
+		DummyChannelHandler::push_error(self, their_node_id, msg.temporary_channel_id);
+	}
+	fn handle_accept_channel(&self, their_node_id: &PublicKey, _their_features: InitFeatures, msg: &msgs::AcceptChannel) {
+		DummyChannelHandler::push_error(self, their_node_id, msg.temporary_channel_id);
+	}
+	fn handle_funding_created(&self, their_node_id: &PublicKey, msg: &msgs::FundingCreated) {
+		DummyChannelHandler::push_error(self, their_node_id, msg.temporary_channel_id);
+	}
+	fn handle_funding_signed(&self, their_node_id: &PublicKey, msg: &msgs::FundingSigned) {
+		DummyChannelHandler::push_error(self, their_node_id, msg.channel_id);
+	}
+	fn handle_funding_locked(&self, their_node_id: &PublicKey, msg: &msgs::FundingLocked) {
+		DummyChannelHandler::push_error(self, their_node_id, msg.channel_id);
+	}
+	fn handle_shutdown(&self, their_node_id: &PublicKey, _their_features: &InitFeatures, msg: &msgs::Shutdown) {
+		DummyChannelHandler::push_error(self, their_node_id, msg.channel_id);
+	}
+	fn handle_closing_signed(&self, their_node_id: &PublicKey, msg: &msgs::ClosingSigned) {
+		DummyChannelHandler::push_error(self, their_node_id, msg.channel_id);
+	}
+	fn handle_update_add_htlc(&self, their_node_id: &PublicKey, msg: &msgs::UpdateAddHTLC) {
+		DummyChannelHandler::push_error(self, their_node_id, msg.channel_id);
+	}
+	fn handle_update_fulfill_htlc(&self, their_node_id: &PublicKey, msg: &msgs::UpdateFulfillHTLC) {
+		DummyChannelHandler::push_error(self, their_node_id, msg.channel_id);
+	}
+	fn handle_update_fail_htlc(&self, their_node_id: &PublicKey, msg: &msgs::UpdateFailHTLC) {
+		DummyChannelHandler::push_error(self, their_node_id, msg.channel_id);
+	}
+	fn handle_update_fail_malformed_htlc(&self, their_node_id: &PublicKey, msg: &msgs::UpdateFailMalformedHTLC) {
+		DummyChannelHandler::push_error(self, their_node_id, msg.channel_id);
+	}
+	fn handle_commitment_signed(&self, their_node_id: &PublicKey, msg: &msgs::CommitmentSigned) {
+		DummyChannelHandler::push_error(self, their_node_id, msg.channel_id);
+	}
+	fn handle_revoke_and_ack(&self, their_node_id: &PublicKey, msg: &msgs::RevokeAndACK) {
+		DummyChannelHandler::push_error(self, their_node_id, msg.channel_id);
+	}
+	fn handle_update_fee(&self, their_node_id: &PublicKey, msg: &msgs::UpdateFee) {
+		DummyChannelHandler::push_error(self, their_node_id, msg.channel_id);
+	}
+	fn handle_announcement_signatures(&self, their_node_id: &PublicKey, msg: &msgs::AnnouncementSignatures) {
+		DummyChannelHandler::push_error(self, their_node_id, msg.channel_id);
+	}
+	fn peer_disconnected(&self, _their_node_id: &PublicKey, _no_connection_possible: bool) {}
+	fn peer_connected(&self, _their_node_id: &PublicKey, _msg: &msgs::Init) {}
+	fn handle_channel_reestablish(&self, their_node_id: &PublicKey, msg: &msgs::ChannelReestablish) {
+		DummyChannelHandler::push_error(self, their_node_id, msg.channel_id);
+	}
+	fn handle_error(&self, _their_node_id: &PublicKey, _msg: &msgs::ErrorMessage) {}
+}
+impl Deref for DummyChannelHandler {
+	type Target = DummyChannelHandler;
+	fn deref(&self) -> &Self { self }
+}
+
 /// Provides references to trait impls which handle different types of messages.
 pub struct MessageHandler<CM: Deref, RM: Deref> where
 		CM::Target: ChannelMessageHandler,
 		RM::Target: RoutingMessageHandler {
 	/// A message handler which handles messages specific to channels. Usually this is just a
-	/// ChannelManager object.
+	/// ChannelManager object or a DummyChannelHandler.
 	pub chan_handler: CM,
 	/// A message handler which handles messages updating our knowledge of the network channel
-	/// graph. Usually this is just a NetGraphMsgHandlerMonitor object.
+	/// graph. Usually this is just a NetGraphMsgHandlerMonitor object or a DummyRouteHandler.
 	pub route_handler: RM,
 }