Add helper functions to verify node and channel annoucements

Author: benthecarman

lightning/src/routing/gossip.rs

@@ -10,7 +10,7 @@
 //! The [`NetworkGraph`] stores the network gossip and [`P2PGossipSync`] fetches it from peers
 
 use bitcoin::secp256k1::constants::PUBLIC_KEY_SIZE;
-use bitcoin::secp256k1::PublicKey;
+use bitcoin::secp256k1::{PublicKey, Verification};
 use bitcoin::secp256k1::Secp256k1;
 use bitcoin::secp256k1;
 
@@ -404,6 +404,25 @@ macro_rules! get_pubkey_from_node_id {
 	}
 }
 
+/// Verifies the signature of a [NodeAnnouncement]. Returns an error if it is invalid.
+pub fn verify_node_announcement<C: Verification>(msg: &NodeAnnouncement, secp_ctx: &Secp256k1<C>) -> Result<(), LightningError> {
+	let msg_hash = hash_to_message!(&Sha256dHash::hash(&msg.contents.encode()[..])[..]);
+	secp_verify_sig!(secp_ctx, &msg_hash, &msg.signature, &get_pubkey_from_node_id!(msg.contents.node_id, "node_announcement"), "node_announcement");
+
+	Ok(())
+}
+
+/// Verifies the signature of a [ChannelAnnouncement]. Returns an error if it is invalid.
+pub fn verify_channel_announcement<C: Verification>(msg: &ChannelAnnouncement, secp_ctx: &Secp256k1<C>) -> Result<(), LightningError> {
+	let msg_hash = hash_to_message!(&Sha256dHash::hash(&msg.contents.encode()[..])[..]);
+	secp_verify_sig!(secp_ctx, &msg_hash, &msg.node_signature_1, &get_pubkey_from_node_id!(msg.contents.node_id_1, "channel_announcement"), "channel_announcement");
+	secp_verify_sig!(secp_ctx, &msg_hash, &msg.node_signature_2, &get_pubkey_from_node_id!(msg.contents.node_id_2, "channel_announcement"), "channel_announcement");
+	secp_verify_sig!(secp_ctx, &msg_hash, &msg.bitcoin_signature_1, &get_pubkey_from_node_id!(msg.contents.bitcoin_key_1, "channel_announcement"), "channel_announcement");
+	secp_verify_sig!(secp_ctx, &msg_hash, &msg.bitcoin_signature_2, &get_pubkey_from_node_id!(msg.contents.bitcoin_key_2, "channel_announcement"), "channel_announcement");
+
+	Ok(())
+}
+
 impl<G: Deref<Target=NetworkGraph<L>>, U: Deref, L: Deref> RoutingMessageHandler for P2PGossipSync<G, U, L>
 where U::Target: UtxoLookup, L::Target: Logger
 {
@@ -1387,8 +1406,7 @@ impl<L: Deref> NetworkGraph<L> where L::Target: Logger {
 	/// RoutingMessageHandler implementation to call it indirectly. This may be useful to accept
 	/// routing messages from a source using a protocol other than the lightning P2P protocol.
 	pub fn update_node_from_announcement(&self, msg: &msgs::NodeAnnouncement) -> Result<(), LightningError> {
-		let msg_hash = hash_to_message!(&Sha256dHash::hash(&msg.contents.encode()[..])[..]);
-		secp_verify_sig!(self.secp_ctx, &msg_hash, &msg.signature, &get_pubkey_from_node_id!(msg.contents.node_id, "node_announcement"), "node_announcement");
+		verify_node_announcement(msg, &self.secp_ctx)?;
 		self.update_node_from_announcement_intern(&msg.contents, Some(&msg))
 	}
 
@@ -1451,11 +1469,7 @@ impl<L: Deref> NetworkGraph<L> where L::Target: Logger {
 	where
 		U::Target: UtxoLookup,
 	{
-		let msg_hash = hash_to_message!(&Sha256dHash::hash(&msg.contents.encode()[..])[..]);
-		secp_verify_sig!(self.secp_ctx, &msg_hash, &msg.node_signature_1, &get_pubkey_from_node_id!(msg.contents.node_id_1, "channel_announcement"), "channel_announcement");
-		secp_verify_sig!(self.secp_ctx, &msg_hash, &msg.node_signature_2, &get_pubkey_from_node_id!(msg.contents.node_id_2, "channel_announcement"), "channel_announcement");
-		secp_verify_sig!(self.secp_ctx, &msg_hash, &msg.bitcoin_signature_1, &get_pubkey_from_node_id!(msg.contents.bitcoin_key_1, "channel_announcement"), "channel_announcement");
-		secp_verify_sig!(self.secp_ctx, &msg_hash, &msg.bitcoin_signature_2, &get_pubkey_from_node_id!(msg.contents.bitcoin_key_2, "channel_announcement"), "channel_announcement");
+		verify_channel_announcement(msg, &self.secp_ctx)?;
 		self.update_channel_from_unsigned_announcement_intern(&msg.contents, Some(msg), utxo_lookup)
 	}