Use RouteHop's new node_features to send TLV-encoded onion hops

This implements the new TLV variable-length encoding for onion hop
data, opting to send it if the RouteHop's node_features indicates
support. It also uses the new process_inline method in ChaCha20 to
optimize a few things (though it grows a new TODO for a
probably-important optimization).

Author: TheBlueMatt

lightning/src/ln/channelmanager.rs

@@ -1138,6 +1138,9 @@ impl<ChanSigner: ChannelKeys> ChannelManager<ChanSigner> {
 		let onion_keys = secp_call!(onion_utils::construct_onion_keys(&self.secp_ctx, &route, &session_priv),
 				APIError::RouteError{err: "Pubkey along hop was maliciously selected"});
 		let (onion_payloads, htlc_msat, htlc_cltv) = onion_utils::build_onion_payloads(&route, cur_height)?;
+		if onion_utils::route_size_insane(&onion_payloads) {
+			return Err(APIError::RouteError{err: "Route had too large size once"});
+		}
 		let onion_packet = onion_utils::construct_onion_packet(onion_payloads, onion_keys, prng_seed, &payment_hash);
 
 		let _ = self.total_consistency_lock.read().unwrap();

lightning/src/ln/features.rs

@@ -29,6 +29,10 @@ mod sealed { // You should just use the type aliases instead.
 	pub trait UpfrontShutdownScript: Context {}
 	impl UpfrontShutdownScript for InitContext {}
 	impl UpfrontShutdownScript for NodeContext {}
+
+	pub trait VariableLengthOnion: Context {}
+	impl VariableLengthOnion for InitContext {}
+	impl VariableLengthOnion for NodeContext {}
 }
 
 /// Tracks the set of features which a node implements, templated by the context in which it
@@ -69,7 +73,7 @@ impl InitFeatures {
 	/// Create a Features with the features we support
 	pub fn supported() -> InitFeatures {
 		InitFeatures {
-			flags: vec![2 | 1 << 5],
+			flags: vec![2 | 1 << 5, 1 << (9-8)],
 			mark: PhantomData,
 		}
 	}
@@ -132,14 +136,14 @@ impl NodeFeatures {
 	#[cfg(not(feature = "fuzztarget"))]
 	pub(crate) fn supported() -> NodeFeatures {
 		NodeFeatures {
-			flags: vec![2 | 1 << 5],
+			flags: vec![2 | 1 << 5, 1 << (9-8)],
 			mark: PhantomData,
 		}
 	}
 	#[cfg(feature = "fuzztarget")]
 	pub fn supported() -> NodeFeatures {
 		NodeFeatures {
-			flags: vec![2 | 1 << 5],
+			flags: vec![2 | 1 << 5, 1 << (9-8)],
 			mark: PhantomData,
 		}
 	}
@@ -240,6 +244,12 @@ impl<T: sealed::UpfrontShutdownScript> Features<T> {
 	}
 }
 
+impl<T: sealed::VariableLengthOnion> Features<T> {
+	pub(crate) fn supports_variable_length_onion(&self) -> bool {
+		self.flags.len() > 1 && (self.flags[1] & 3) != 0
+	}
+}
+
 impl<T: sealed::InitialRoutingSync> Features<T> {
 	pub(crate) fn initial_routing_sync(&self) -> bool {
 		self.flags.len() > 0 && (self.flags[0] & (1 << 3)) != 0

lightning/src/ln/onion_utils.rs

@@ -4,7 +4,7 @@ use ln::router::{Route,RouteHop};
 use util::byte_utils;
 use util::chacha20::ChaCha20;
 use util::errors::{self, APIError};
-use util::ser::{Readable, Writeable};
+use util::ser::{Readable, Writeable, LengthCalculatingWriter};
 use util::logger::{Logger, LogHolder};
 
 use bitcoin_hashes::{Hash, HashEngine};
@@ -114,15 +114,25 @@ pub(super) fn build_onion_payloads(route: &Route, starting_htlc_offset: u32) ->
 	let mut last_short_channel_id = 0;
 	let mut res: Vec<msgs::OnionHopData> = Vec::with_capacity(route.hops.len());
 
-	for hop in route.hops.iter().rev() {
+	for (idx, hop) in route.hops.iter().rev().enumerate() {
 		// First hop gets special values so that it can check, on receipt, that everything is
 		// exactly as it should be (and the next hop isn't trying to probe to find out if we're
 		// the intended recipient).
 		let value_msat = if cur_value_msat == 0 { hop.fee_msat } else { cur_value_msat };
 		let cltv = if cur_cltv == starting_htlc_offset { hop.cltv_expiry_delta + starting_htlc_offset } else { cur_cltv };
 		res.insert(0, msgs::OnionHopData {
-			format: msgs::OnionHopDataFormat::Legacy {
-				short_channel_id: last_short_channel_id,
+			format: if hop.node_features.supports_variable_length_onion() {
+				if idx == 0 {
+					msgs::OnionHopDataFormat::FinalNode
+				} else {
+					msgs::OnionHopDataFormat::NonFinalNode {
+						short_channel_id: last_short_channel_id,
+					}
+				}
+			} else {
+				msgs::OnionHopDataFormat::Legacy {
+					short_channel_id: last_short_channel_id,
+				}
 			},
 			amt_to_forward: value_msat,
 			outgoing_cltv_value: cltv,
@@ -141,26 +151,30 @@ pub(super) fn build_onion_payloads(route: &Route, starting_htlc_offset: u32) ->
 }
 
 #[inline]
-fn shift_arr_right(arr: &mut [u8; 20*65]) {
-	for i in (65..20*65).rev() {
-		arr[i] = arr[i-65];
+fn shift_arr_right(arr: &mut [u8; 20*65], amt: usize) {
+	for i in (amt..20*65).rev() {
+		arr[i] = arr[i-amt];
 	}
-	for i in 0..65 {
+	for i in 0..amt {
 		arr[i] = 0;
 	}
 }
 
-#[inline]
-fn xor_bufs(dst: &mut[u8], src: &[u8]) {
-	assert_eq!(dst.len(), src.len());
-
-	for i in 0..dst.len() {
-		dst[i] ^= src[i];
+pub(super) fn route_size_insane(payloads: &Vec<msgs::OnionHopData>) -> bool {
+	let mut len = 0;
+	for payload in payloads.iter() {
+		let mut payload_len = LengthCalculatingWriter(0);
+		payload.write(&mut payload_len).expect("Can't fail to calculate length");
+		assert!(payload_len.0 + 32 < 20*65);
+		len += payload_len.0 + 32;
+		if len > 20*65 {
+			return true;
+		}
 	}
+	false
 }
 
-
-const ZERO:[u8; 21*65] = [0; 21*65];
+/// panics if route_size_insane(paylods)
 pub(super) fn construct_onion_packet(payloads: Vec<msgs::OnionHopData>, onion_keys: Vec<OnionKeys>, prng_seed: [u8; 32], associated_data: &PaymentHash) -> msgs::OnionPacket {
 	let mut packet_data = [0; 20*65];
 
@@ -182,35 +196,42 @@ pub(super) fn construct_onion_packet_bogus_hopdata<HD: Writeable>(payloads: Vec<
 	construct_onion_packet_with_init_noise(payloads, onion_keys, packet_data, associated_data)
 }
 
+/// panics if route_size_insane(paylods)
 fn construct_onion_packet_with_init_noise<HD: Writeable>(mut payloads: Vec<HD>, onion_keys: Vec<OnionKeys>, mut packet_data: [u8; 20*65], associated_data: &PaymentHash) -> msgs::OnionPacket {
-	let mut buf = Vec::with_capacity(21*65);
-	buf.resize(21*65, 0);
-
 	let filler = {
-		let iters = payloads.len() - 1;
-		let end_len = iters * 65;
-		let mut res = Vec::with_capacity(end_len);
-		res.resize(end_len, 0);
+		let mut res = Vec::with_capacity(65 * (payloads.len() - 1)); // Even TLV len is close enough to 65
+
+		let mut pos = 0;
+		for (i, (payload, keys)) in payloads.iter().zip(onion_keys.iter()).enumerate() {
+			if i == payloads.len() - 1 { break; }
 
-		for (i, keys) in onion_keys.iter().enumerate() {
-			if i == payloads.len() - 1 { continue; }
 			let mut chacha = ChaCha20::new(&keys.rho, &[0u8; 8]);
-			chacha.process(&ZERO, &mut buf); // We don't have a seek function :(
-			xor_bufs(&mut res[0..(i + 1)*65], &buf[(20 - i)*65..21*65]);
+			for _ in 0..(20*65 - pos) { // TODO: Batch this.
+				let mut dummy = [0; 1];
+				chacha.process_inline(&mut dummy); // We don't have a seek function :(
+			}
+
+			let mut payload_len = LengthCalculatingWriter(0);
+			payload.write(&mut payload_len).expect("Can't fail to calculate length");
+			pos += payload_len.0 + 32;
+			assert!(pos <= 1300);
+
+			res.resize(pos, 0u8);
+			chacha.process_inline(&mut res);
 		}
 		res
 	};
 
 	let mut hmac_res = [0; 32];
-
 	for (i, (payload, keys)) in payloads.iter_mut().zip(onion_keys.iter()).rev().enumerate() {
-		shift_arr_right(&mut packet_data);
-		packet_data[0..33].copy_from_slice(&payload.encode()[..]);
-		packet_data[33..65].copy_from_slice(&hmac_res);
+		let mut payload_len = LengthCalculatingWriter(0);
+		payload.write(&mut payload_len).expect("Can't fail to calculate length");
+		shift_arr_right(&mut packet_data, payload_len.0 + 32);
+		packet_data[0..payload_len.0].copy_from_slice(&payload.encode()[..]);
+		packet_data[payload_len.0..(payload_len.0 + 32)].copy_from_slice(&hmac_res);
 
 		let mut chacha = ChaCha20::new(&keys.rho, &[0u8; 8]);
-		chacha.process(&packet_data, &mut buf[0..20*65]);
-		packet_data[..].copy_from_slice(&buf[0..20*65]);
+		chacha.process_inline(&mut packet_data);
 
 		if i == 0 {
 			packet_data[20*65 - filler.len()..20*65].copy_from_slice(&filler[..]);
@@ -222,7 +243,7 @@ fn construct_onion_packet_with_init_noise<HD: Writeable>(mut payloads: Vec<HD>,
 		hmac_res = Hmac::from_engine(hmac).into_inner();
 	}
 
-	msgs::OnionPacket{
+	msgs::OnionPacket {
 		version: 0,
 		public_key: Ok(onion_keys.first().unwrap().ephemeral_pubkey),
 		hop_data: packet_data,
@@ -438,7 +459,7 @@ mod tests {
 	use ln::features::{ChannelFeatures, NodeFeatures};
 	use ln::router::{Route, RouteHop};
 	use ln::msgs;
-	use util::ser::Writeable;
+	use util::ser::{Writeable, Writer};
 
 	use hex;
 
@@ -490,7 +511,7 @@ mod tests {
 
 	#[test]
 	fn onion_vectors() {
-		// Packet creation test vectors from BOLT 4
+		// Legacy packet creation test vectors from BOLT 4
 		let onion_keys = build_test_onion_keys();
 
 		assert_eq!(onion_keys[0].shared_secret[..], hex::decode("53eb63ea8a3fec3b3cd433b85cd62a4b145e1dda09391b348c4e1cd36a03ea66").unwrap()[..]);
@@ -562,8 +583,7 @@ mod tests {
 			},
 		);
 
-		let packet = [0; 20*65];
-		let packet = super::construct_onion_packet_with_init_noise(payloads, onion_keys, packet, &PaymentHash([0x42; 32]));
+		let packet = super::construct_onion_packet_with_init_noise(payloads, onion_keys, [0; 20*65], &PaymentHash([0x42; 32]));
 		// Just check the final packet encoding, as it includes all the per-hop vectors in it
 		// anyway...
 		assert_eq!(packet.encode(), hex::decode("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").unwrap());
@@ -592,4 +612,58 @@ mod tests {
 		let onion_packet_5 = super::encrypt_failure_packet(&onion_keys[0].shared_secret[..], &onion_packet_4.data[..]);
 		assert_eq!(onion_packet_5.data, hex::decode("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").unwrap());
 	}
+
+	struct RawOnionHopData {
+		data: Vec<u8>
+	}
+	impl RawOnionHopData {
+		fn new(orig: msgs::OnionHopData) -> Self {
+			Self { data: orig.encode() }
+		}
+	}
+	impl Writeable for RawOnionHopData {
+		fn write<W: Writer>(&self, writer: &mut W) -> Result<(), ::std::io::Error> {
+			writer.write_all(&self.data[..])
+		}
+	}
+
+	#[test]
+	fn tlv_onion_vectors() {
+		// Packet creation test vectors from BOLT 4
+		// Note that we use he RawOnionHopData for everything except Legacy hops, as even the hops
+		// with "type": "tlv" are not valid TLV, and, thus, cannot be directly represented in our
+		// in-memory enums.
+		let onion_keys = build_test_onion_keys();
+
+		let payloads = vec!(
+			RawOnionHopData::new(msgs::OnionHopData {
+				format: msgs::OnionHopDataFormat::Legacy {
+					short_channel_id: 0,
+				},
+				amt_to_forward: 0,
+				outgoing_cltv_value: 0,
+			}),
+			RawOnionHopData {
+				data: hex::decode("140101010101010101000000000000000100000001").unwrap(),
+			},
+			RawOnionHopData {
+				data: hex::decode("fd0100000102030405060708090a0b0c0d0e0f101112131415161718191a1b1c1d1e1f202122232425262728292a2b2c2d2e2f303132333435363738393a3b3c3d3e3f404142434445464748494a4b4c4d4e4f505152535455565758595a5b5c5d5e5f606162636465666768696a6b6c6d6e6f707172737475767778797a7b7c7d7e7f808182838485868788898a8b8c8d8e8f909192939495969798999a9b9c9d9e9fa0a1a2a3a4a5a6a7a8a9aaabacadaeafb0b1b2b3b4b5b6b7b8b9babbbcbdbebfc0c1c2c3c4c5c6c7c8c9cacbcccdcecfd0d1d2d3d4d5d6d7d8d9dadbdcdddedfe0e1e2e3e4e5e6e7e8e9eaebecedeeeff0f1f2f3f4f5f6f7f8f9fafbfcfdfeff").unwrap(),
+			},
+			RawOnionHopData {
+				data: hex::decode("140303030303030303000000000000000300000003").unwrap(),
+			},
+			RawOnionHopData::new(msgs::OnionHopData {
+				format: msgs::OnionHopDataFormat::Legacy {
+					short_channel_id: 0x0404040404040404,
+				},
+				amt_to_forward: 4,
+				outgoing_cltv_value: 4,
+			}),
+		);
+
+		let packet = super::construct_onion_packet_with_init_noise(payloads, onion_keys, [0; 20*65], &PaymentHash([0x42; 32]));
+		// Just check the final packet encoding, as it includes all the per-hop vectors in it
+		// anyway...
+		assert_eq!(packet.encode(), hex::decode("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").unwrap());
+	}
 }