From 52aecbdef7c7a38df7926e2e789649567e5951fe Mon Sep 17 00:00:00 2001
From: Matt Corallo <git@bluematt.me>
Date: Thu, 30 Aug 2018 14:33:30 -0400
Subject: [PATCH] fixup!

---
 src/chain/chaininterface.rs | 49 +++++++++----------------------------
 src/ln/router.rs            | 20 ++++++++++-----
 2 files changed, 26 insertions(+), 43 deletions(-)

diff --git a/src/chain/chaininterface.rs b/src/chain/chaininterface.rs
index 533b007fe..78a40099c 100644
--- a/src/chain/chaininterface.rs
+++ b/src/chain/chaininterface.rs
@@ -11,14 +11,12 @@ use std::sync::atomic::{AtomicUsize, Ordering};
 
 /// Used to give chain error details upstream
 pub enum ChainError {
-	/// Chain isn't supported
+	/// Client doesn't support UTXO lookup (but the chain hash matches our genesis block hash)
 	NotSupported,
 	/// Chain isn't the one watched
 	NotWatched,
-	/// Tx isn't there
+	/// Tx doesn't exist or is unconfirmed
 	UnknownTx,
-	/// Tx isn't confirmed
-	UnconfirmedTx,
 }
 
 /// An interface to request notification of certain scripts as they appear the
@@ -40,14 +38,11 @@ pub trait ChainWatchInterface: Sync + Send {
 	fn register_listener(&self, listener: Weak<ChainListener>);
 	//TODO: unregister
 
-	/// Gets the chain currently watched
-	fn get_network(&self) -> Network;
-
-	/// Gets the script and value in satoshis for a given txid and outpoint index
-	fn get_chain_txo(&self, genesis_hash: Sha256dHash, txid: Sha256dHash, output_index: u16) -> Result<(Script, u64), ChainError>;
-
-	/// Gets if outpoint is among UTXO
-	fn get_spendable_outpoint(&self, genesis_hash: Sha256dHash, txid: Sha256dHash, output_index: u16) -> Result<bool, ChainError>;
+	/// Gets the script and value in satoshis for a given unspent transaction output given a
+	/// short_channel_id (aka unspent_tx_output_identier). For BTC/tBTC channels the top three
+	/// bytes are the block height, the next 3 the transaction index within the block, and the
+	/// final two the output within the transaction.
+	fn get_chain_utxo(&self, genesis_hash: Sha256dHash, unspent_tx_output_identifier: u64) -> Result<(Script, u64), ChainError>;
 }
 
 /// An interface to send a transaction to the Bitcoin network.
@@ -100,14 +95,6 @@ pub struct ChainWatchInterfaceUtil {
 	logger: Arc<Logger>,
 }
 
-macro_rules! watched_chain {
-	($self: ident, $hash: expr) => {
-		if $hash != genesis_block($self.get_network()).header.bitcoin_hash() {
-			return Err(ChainError::NotWatched);
-		}
-	}
-}
-
 /// Register listener
 impl ChainWatchInterface for ChainWatchInterfaceUtil {
 	fn install_watch_script(&self, script_pub_key: &Script) {
@@ -133,23 +120,11 @@ impl ChainWatchInterface for ChainWatchInterfaceUtil {
 		vec.push(listener);
 	}
 
-	fn get_network(&self) -> Network {
-		self.network
-	}
-
-
-	fn get_chain_txo(&self, genesis_hash: Sha256dHash, _txid: Sha256dHash, _output_index: u16) -> Result<(Script, u64), ChainError> {
-		watched_chain!(self, genesis_hash);
-
-		//TODO: self.BlockchainStore.get_txo(txid, output_index)
-		Err(ChainError::UnknownTx)
-	}
-
-	fn get_spendable_outpoint(&self, genesis_hash: Sha256dHash, _txid: Sha256dHash, _output_index: u16) -> Result<bool, ChainError> {
-		watched_chain!(self, genesis_hash);
-
-		//TODO: self.BlockchainStore.is_utxo(txid, output_index)
-		Err(ChainError::UnknownTx)
+	fn get_chain_utxo(&self, genesis_hash: Sha256dHash, _unspent_tx_output_identifier: u64) -> Result<(Script, u64), ChainError> {
+		if genesis_hash != genesis_block(self.network).header.bitcoin_hash() {
+			return Err(ChainError::NotWatched);
+		}
+		Err(ChainError::NotSupported)
 	}
 }
 
diff --git a/src/ln/router.rs b/src/ln/router.rs
index 620008b4b..e249913ec 100644
--- a/src/ln/router.rs
+++ b/src/ln/router.rs
@@ -3,10 +3,8 @@ use secp256k1::{Secp256k1,Message};
 use secp256k1;
 
 use bitcoin::util::hash::Sha256dHash;
-use bitcoin::blockdata::constants::genesis_block;
-use bitcoin::network::serialize::BitcoinHash;
 
-use chain::chaininterface::ChainWatchInterface;
+use chain::chaininterface::{ChainError, ChainWatchInterface};
 use ln::channelmanager;
 use ln::msgs::{ErrorAction,HandleError,RoutingMessageHandler,MsgEncodable,NetAddress,GlobalFeatures};
 use ln::msgs;
@@ -209,9 +207,19 @@ impl RoutingMessageHandler for Router {
 			panic!("Unknown-required-features ChannelAnnouncements should never deserialize!");
 		}
 
-		//TODO: Call blockchain thing to ask if the short_channel_id is valid
-		if msg.contents.chain_hash != genesis_block(self.chain_monitor.get_network()).header.bitcoin_hash() {
-			return Err(HandleError{err: "Channel announced on an unknown chain", action: Some(ErrorAction::IgnoreError)});
+		match self.chain_monitor.get_chain_utxo(msg.contents.chain_hash, msg.contents.short_channel_id) {
+			Ok((script_pubkey, _value)) => {
+				//TODO: Check if script_pubkey matches bitcoin_key_1 and bitcoin_key_2
+			},
+			Err(ChainError::NotSupported) => {
+				// Tenatively accept, potentially exposing us to DoS attacks
+			},
+			Err(ChainError::NotWatched) => {
+				return Err(HandleError{err: "Channel announced on an unknown chain", action: Some(ErrorAction::IgnoreError)});
+			},
+			Err(ChainError::UnknownTx) => {
+				return Err(HandleError{err: "Channel announced without corresponding UTXO entry", action: Some(ErrorAction::IgnoreError)});
+			},
 		}
 
 		let mut network = self.network_map.write().unwrap();
-- 
2.39.5