X-Git-Url: http://git.bitcoin.ninja/index.cgi?a=blobdiff_plain;f=lightning%2Fsrc%2Futil%2Fscid_utils.rs;h=19e2f5527ccbcbcb7c997e8f628ef4cf292974e3;hb=c3de782a2baab0c742332bea4783c393edb83311;hp=f9dfd1b0320cb8308d91489928f3bdc1503504e0;hpb=de1aca5ca27ae372a4b240489ccdd49a8f4dc436;p=rust-lightning

diff --git a/lightning/src/util/scid_utils.rs b/lightning/src/util/scid_utils.rs
index f9dfd1b0..19e2f552 100644
--- a/lightning/src/util/scid_utils.rs
+++ b/lightning/src/util/scid_utils.rs
@@ -20,7 +20,7 @@ pub const MAX_SCID_TX_INDEX: u64 = 0x00ffffff;
 pub const MAX_SCID_VOUT_INDEX: u64 = 0xffff;
 
 /// A `short_channel_id` construction error
-#[derive(Debug, PartialEq)]
+#[derive(Debug, PartialEq, Eq)]
 pub enum ShortChannelIdError {
 	BlockOverflow,
 	TxIndexOverflow,
@@ -61,32 +61,39 @@ pub fn scid_from_parts(block: u64, tx_index: u64, vout_index: u64) -> Result<u64
 }
 
 /// LDK has multiple reasons to generate fake short channel ids:
-/// 1) zero-conf channels that don't have a confirmed channel id yet
+/// 1) outbound SCID aliases we use for private channels
 /// 2) phantom node payments, to get an scid for the phantom node's phantom channel
+/// 3) payments intended to be intercepted will route using a fake scid (this is typically used so
+///    the forwarding node can open a JIT channel to the next hop)
 pub(crate) mod fake_scid {
 	use bitcoin::hash_types::BlockHash;
 	use bitcoin::hashes::hex::FromHex;
-	use chain::keysinterface::{Sign, KeysInterface};
-	use util::chacha20::ChaCha20;
-	use util::scid_utils;
+	use crate::chain::keysinterface::EntropySource;
+	use crate::util::chacha20::ChaCha20;
+	use crate::util::scid_utils;
 
 	use core::convert::TryInto;
 	use core::ops::Deref;
 
-	const TEST_SEGWIT_ACTIVATION_HEIGHT: u32 = 0;
+	const TEST_SEGWIT_ACTIVATION_HEIGHT: u32 = 1;
 	const MAINNET_SEGWIT_ACTIVATION_HEIGHT: u32 = 481_824;
 	const MAX_TX_INDEX: u32 = 2_500;
 	const MAX_NAMESPACES: u8 = 8; // We allocate 3 bits for the namespace identifier.
 	const NAMESPACE_ID_BITMASK: u8 = 0b111;
 
+	const BLOCKS_PER_MONTH: u32 = 144 /* blocks per day */ * 30 /* days per month */;
+	pub(crate) const MAX_SCID_BLOCKS_FROM_NOW: u32 = BLOCKS_PER_MONTH;
+
+
 	/// Fake scids are divided into namespaces, with each namespace having its own identifier between
 	/// [0..7]. This allows us to identify what namespace a fake scid corresponds to upon HTLC
 	/// receipt, and handle the HTLC accordingly. The namespace identifier is encrypted when encoded
 	/// into the fake scid.
 	#[derive(Copy, Clone)]
-	pub(super) enum Namespace {
+	pub(crate) enum Namespace {
 		Phantom,
-		// Coming soon: a variant for the zero-conf scid namespace
+		OutboundAlias,
+		Intercept
 	}
 
 	impl Namespace {
@@ -94,28 +101,24 @@ pub(crate) mod fake_scid {
 		/// between segwit activation and the current best known height, and the tx index and output
 		/// index are also selected from a "reasonable" range. We add this logic because it makes it
 		/// non-obvious at a glance that the scid is fake, e.g. if it appears in invoice route hints.
-		pub(super) fn get_fake_scid<Signer: Sign, K: Deref>(&self, highest_seen_blockheight: u32, genesis_hash: &BlockHash, fake_scid_rand_bytes: &[u8; 32], keys_manager: &K) -> u64
-			where K::Target: KeysInterface<Signer = Signer>,
+		pub(crate) fn get_fake_scid<ES: Deref>(&self, highest_seen_blockheight: u32, genesis_hash: &BlockHash, fake_scid_rand_bytes: &[u8; 32], entropy_source: &ES) -> u64
+			where ES::Target: EntropySource,
 		{
 			// Ensure we haven't created a namespace that doesn't fit into the 3 bits we've allocated for
 			// namespaces.
 			assert!((*self as u8) < MAX_NAMESPACES);
-			const BLOCKS_PER_MONTH: u32 = 144 /* blocks per day */ * 30 /* days per month */;
-			let rand_bytes = keys_manager.get_secure_random_bytes();
+			let rand_bytes = entropy_source.get_secure_random_bytes();
 
 			let segwit_activation_height = segwit_activation_height(genesis_hash);
-			let mut valid_block_range = if highest_seen_blockheight > segwit_activation_height {
-				highest_seen_blockheight - segwit_activation_height
-			} else {
-				1
-			};
+			let mut blocks_since_segwit_activation = highest_seen_blockheight.saturating_sub(segwit_activation_height);
+
 			// We want to ensure that this fake channel won't conflict with any transactions we haven't
 			// seen yet, in case `highest_seen_blockheight` is updated before we get full information
 			// about transactions confirmed in the given block.
-			if valid_block_range > BLOCKS_PER_MONTH { valid_block_range -= BLOCKS_PER_MONTH; }
+			blocks_since_segwit_activation = blocks_since_segwit_activation.saturating_sub(MAX_SCID_BLOCKS_FROM_NOW);
 
 			let rand_for_height = u32::from_be_bytes(rand_bytes[..4].try_into().unwrap());
-			let fake_scid_height = segwit_activation_height + rand_for_height % valid_block_range;
+			let fake_scid_height = segwit_activation_height + rand_for_height % (blocks_since_segwit_activation + 1);
 
 			let rand_for_tx_index = u32::from_be_bytes(rand_bytes[4..8].try_into().unwrap());
 			let fake_scid_tx_index = rand_for_tx_index % MAX_TX_INDEX;
@@ -141,13 +144,6 @@ pub(crate) mod fake_scid {
 		}
 	}
 
-	pub fn get_phantom_scid<Signer: Sign, K: Deref>(fake_scid_rand_bytes: &[u8; 32], highest_seen_blockheight: u32, genesis_hash: &BlockHash, keys_manager: &K) -> u64
-		where K::Target: KeysInterface<Signer = Signer>,
-	{
-		let namespace = Namespace::Phantom;
-		namespace.get_fake_scid(highest_seen_blockheight, genesis_hash, fake_scid_rand_bytes, keys_manager)
-	}
-
 	fn segwit_activation_height(genesis: &BlockHash) -> u32 {
 		const MAINNET_GENESIS_STR: &'static str = "000000000019d6689c085ae165831e934ff763ae46a2a6c172b3f1b60a8ce26f";
 		if BlockHash::from_hex(MAINNET_GENESIS_STR).unwrap() == *genesis {
@@ -157,29 +153,44 @@ pub(crate) mod fake_scid {
 		}
 	}
 
-	/// Returns whether the given fake scid falls into the given namespace.
-	pub fn is_valid_phantom(fake_scid_rand_bytes: &[u8; 32], scid: u64) -> bool {
+	/// Returns whether the given fake scid falls into the phantom namespace.
+	pub fn is_valid_phantom(fake_scid_rand_bytes: &[u8; 32], scid: u64, genesis_hash: &BlockHash) -> bool {
 		let block_height = scid_utils::block_from_scid(&scid);
 		let tx_index = scid_utils::tx_index_from_scid(&scid);
 		let namespace = Namespace::Phantom;
 		let valid_vout = namespace.get_encrypted_vout(block_height, tx_index, fake_scid_rand_bytes);
-		valid_vout == scid_utils::vout_from_scid(&scid) as u8
+		block_height >= segwit_activation_height(genesis_hash)
+			&& valid_vout == scid_utils::vout_from_scid(&scid) as u8
+	}
+
+	/// Returns whether the given fake scid falls into the intercept namespace.
+	pub fn is_valid_intercept(fake_scid_rand_bytes: &[u8; 32], scid: u64, genesis_hash: &BlockHash) -> bool {
+		let block_height = scid_utils::block_from_scid(&scid);
+		let tx_index = scid_utils::tx_index_from_scid(&scid);
+		let namespace = Namespace::Intercept;
+		let valid_vout = namespace.get_encrypted_vout(block_height, tx_index, fake_scid_rand_bytes);
+		block_height >= segwit_activation_height(genesis_hash)
+			&& valid_vout == scid_utils::vout_from_scid(&scid) as u8
 	}
 
 	#[cfg(test)]
 	mod tests {
 		use bitcoin::blockdata::constants::genesis_block;
 		use bitcoin::network::constants::Network;
-		use util::scid_utils::fake_scid::{is_valid_phantom, MAINNET_SEGWIT_ACTIVATION_HEIGHT, MAX_TX_INDEX, MAX_NAMESPACES, Namespace, NAMESPACE_ID_BITMASK, segwit_activation_height, TEST_SEGWIT_ACTIVATION_HEIGHT};
-		use util::scid_utils;
-		use util::test_utils;
-		use sync::Arc;
+		use crate::util::scid_utils::fake_scid::{is_valid_intercept, is_valid_phantom, MAINNET_SEGWIT_ACTIVATION_HEIGHT, MAX_TX_INDEX, MAX_NAMESPACES, Namespace, NAMESPACE_ID_BITMASK, segwit_activation_height, TEST_SEGWIT_ACTIVATION_HEIGHT};
+		use crate::util::scid_utils;
+		use crate::util::test_utils;
+		use crate::sync::Arc;
 
 		#[test]
 		fn namespace_identifier_is_within_range() {
 			let phantom_namespace = Namespace::Phantom;
 			assert!((phantom_namespace as u8) < MAX_NAMESPACES);
 			assert!((phantom_namespace as u8) <= NAMESPACE_ID_BITMASK);
+
+			let intercept_namespace = Namespace::Intercept;
+			assert!((intercept_namespace as u8) < MAX_NAMESPACES);
+			assert!((intercept_namespace as u8) <= NAMESPACE_ID_BITMASK);
 		}
 
 		#[test]
@@ -201,11 +212,24 @@ pub(crate) mod fake_scid {
 		fn test_is_valid_phantom() {
 			let namespace = Namespace::Phantom;
 			let fake_scid_rand_bytes = [0; 32];
+			let testnet_genesis = genesis_block(Network::Testnet).header.block_hash();
+			let valid_encrypted_vout = namespace.get_encrypted_vout(0, 0, &fake_scid_rand_bytes);
+			let valid_fake_scid = scid_utils::scid_from_parts(1, 0, valid_encrypted_vout as u64).unwrap();
+			assert!(is_valid_phantom(&fake_scid_rand_bytes, valid_fake_scid, &testnet_genesis));
+			let invalid_fake_scid = scid_utils::scid_from_parts(1, 0, 12).unwrap();
+			assert!(!is_valid_phantom(&fake_scid_rand_bytes, invalid_fake_scid, &testnet_genesis));
+		}
+
+		#[test]
+		fn test_is_valid_intercept() {
+			let namespace = Namespace::Intercept;
+			let fake_scid_rand_bytes = [0; 32];
+			let testnet_genesis = genesis_block(Network::Testnet).header.block_hash();
 			let valid_encrypted_vout = namespace.get_encrypted_vout(0, 0, &fake_scid_rand_bytes);
-			let valid_fake_scid = scid_utils::scid_from_parts(0, 0, valid_encrypted_vout as u64).unwrap();
-			assert!(is_valid_phantom(&fake_scid_rand_bytes, valid_fake_scid));
-			let invalid_fake_scid = scid_utils::scid_from_parts(0, 0, 12).unwrap();
-			assert!(!is_valid_phantom(&fake_scid_rand_bytes, invalid_fake_scid));
+			let valid_fake_scid = scid_utils::scid_from_parts(1, 0, valid_encrypted_vout as u64).unwrap();
+			assert!(is_valid_intercept(&fake_scid_rand_bytes, valid_fake_scid, &testnet_genesis));
+			let invalid_fake_scid = scid_utils::scid_from_parts(1, 0, 12).unwrap();
+			assert!(!is_valid_intercept(&fake_scid_rand_bytes, invalid_fake_scid, &testnet_genesis));
 		}
 
 		#[test]