X-Git-Url: http://git.bitcoin.ninja/index.cgi?a=blobdiff_plain;f=lightning%2Fsrc%2Fonion_message%2Fmessenger.rs;h=3ee9d8fc4fabe81b9438367ac96bfcd903c97638;hb=3194d833b609e72b0b3cf0bcf988d37eadc75c74;hp=e2d7b51a9b5255703108e7c4e1563d8b2fceb13c;hpb=4c8dc2c2a0b9589298d937bf16061ae0ac99b31e;p=rust-lightning diff --git a/lightning/src/onion_message/messenger.rs b/lightning/src/onion_message/messenger.rs index e2d7b51a..3ee9d8fc 100644 --- a/lightning/src/onion_message/messenger.rs +++ b/lightning/src/onion_message/messenger.rs @@ -10,40 +10,191 @@ //! LDK sends, receives, and forwards onion messages via the [`OnionMessenger`]. See its docs for //! more information. -use bitcoin::secp256k1::{self, PublicKey, Secp256k1}; +use bitcoin::hashes::{Hash, HashEngine}; +use bitcoin::hashes::hmac::{Hmac, HmacEngine}; +use bitcoin::hashes::sha256::Hash as Sha256; +use bitcoin::secp256k1::{self, PublicKey, Scalar, Secp256k1, SecretKey}; -use chain::keysinterface::{InMemorySigner, KeysInterface, KeysManager, Sign}; -use ln::msgs; -use util::logger::Logger; +use crate::chain::keysinterface::{KeysInterface, KeysManager, Recipient}; +use crate::ln::features::{InitFeatures, NodeFeatures}; +use crate::ln::msgs::{self, OnionMessageHandler}; +use crate::ln::onion_utils; +use crate::ln::peer_handler::IgnoringMessageHandler; +use super::blinded_path::{BlindedPath, ForwardTlvs, ReceiveTlvs}; +use super::packet::{CustomOnionMessageContents, OnionMessageContents}; +use super::packet::{BIG_PACKET_HOP_DATA_LEN, ForwardControlTlvs, Packet, Payload, ReceiveControlTlvs, SMALL_PACKET_HOP_DATA_LEN}; +use super::utils; +use crate::util::events::OnionMessageProvider; +use crate::util::logger::Logger; +use crate::util::ser::Writeable; use core::ops::Deref; -use sync::{Arc, Mutex}; -use prelude::*; +use crate::io; +use crate::sync::{Arc, Mutex}; +use crate::prelude::*; /// A sender, receiver and forwarder of onion messages. In upcoming releases, this object will be -/// used to retrieve invoices and fulfill invoice requests from [offers]. +/// used to retrieve invoices and fulfill invoice requests from [offers]. Currently, only sending +/// and receiving custom onion messages is supported. +/// +/// # Example +/// +/// ``` +/// # extern crate bitcoin; +/// # use bitcoin::hashes::_export::_core::time::Duration; +/// # use bitcoin::secp256k1::{PublicKey, Secp256k1, SecretKey}; +/// # use lightning::chain::keysinterface::{InMemorySigner, KeysManager, KeysInterface}; +/// # use lightning::ln::msgs::DecodeError; +/// # use lightning::ln::peer_handler::IgnoringMessageHandler; +/// # use lightning::onion_message::blinded_path::BlindedPath; +/// # use lightning::onion_message::messenger::{CustomOnionMessageContents, Destination, OnionMessageContents, OnionMessenger}; +/// # use lightning::util::logger::{Logger, Record}; +/// # use lightning::util::ser::{Writeable, Writer}; +/// # use lightning::io; +/// # use std::sync::Arc; +/// # struct FakeLogger {}; +/// # impl Logger for FakeLogger { +/// # fn log(&self, record: &Record) { unimplemented!() } +/// # } +/// # let seed = [42u8; 32]; +/// # let time = Duration::from_secs(123456); +/// # let keys_manager = KeysManager::new(&seed, time.as_secs(), time.subsec_nanos()); +/// # let logger = Arc::new(FakeLogger {}); +/// # let node_secret = SecretKey::from_slice(&hex::decode("0101010101010101010101010101010101010101010101010101010101010101").unwrap()[..]).unwrap(); +/// # let secp_ctx = Secp256k1::new(); +/// # let hop_node_id1 = PublicKey::from_secret_key(&secp_ctx, &node_secret); +/// # let (hop_node_id2, hop_node_id3, hop_node_id4) = (hop_node_id1, hop_node_id1, hop_node_id1); +/// # let destination_node_id = hop_node_id1; +/// # let your_custom_message_handler = IgnoringMessageHandler {}; +/// // Create the onion messenger. This must use the same `keys_manager` as is passed to your +/// // ChannelManager. +/// let onion_messenger = OnionMessenger::new(&keys_manager, logger, your_custom_message_handler); +/// +/// # struct YourCustomMessage {} +/// impl Writeable for YourCustomMessage { +/// fn write(&self, w: &mut W) -> Result<(), io::Error> { +/// # Ok(()) +/// // Write your custom onion message to `w` +/// } +/// } +/// impl CustomOnionMessageContents for YourCustomMessage { +/// fn tlv_type(&self) -> u64 { +/// # let your_custom_message_type = 42; +/// your_custom_message_type +/// } +/// } +/// // Send a custom onion message to a node id. +/// let intermediate_hops = [hop_node_id1, hop_node_id2]; +/// let reply_path = None; +/// # let your_custom_message = YourCustomMessage {}; +/// let message = OnionMessageContents::Custom(your_custom_message); +/// onion_messenger.send_onion_message(&intermediate_hops, Destination::Node(destination_node_id), message, reply_path); +/// +/// // Create a blinded path to yourself, for someone to send an onion message to. +/// # let your_node_id = hop_node_id1; +/// let hops = [hop_node_id3, hop_node_id4, your_node_id]; +/// let blinded_path = BlindedPath::new(&hops, &keys_manager, &secp_ctx).unwrap(); +/// +/// // Send a custom onion message to a blinded path. +/// # let intermediate_hops = [hop_node_id1, hop_node_id2]; +/// let reply_path = None; +/// # let your_custom_message = YourCustomMessage {}; +/// let message = OnionMessageContents::Custom(your_custom_message); +/// onion_messenger.send_onion_message(&intermediate_hops, Destination::BlindedPath(blinded_path), message, reply_path); +/// ``` /// /// [offers]: -pub struct OnionMessenger - where K::Target: KeysInterface, +/// [`OnionMessenger`]: crate::onion_message::OnionMessenger +pub struct OnionMessenger + where K::Target: KeysInterface, L::Target: Logger, + CMH:: Target: CustomOnionMessageHandler, { keys_manager: K, logger: L, - pending_messages: Mutex>>, + pending_messages: Mutex>>, secp_ctx: Secp256k1, + custom_handler: CMH, // Coming soon: // invoice_handler: InvoiceHandler, - // custom_handler: CustomHandler, // handles custom onion messages } -impl OnionMessenger - where K::Target: KeysInterface, +/// The destination of an onion message. +pub enum Destination { + /// We're sending this onion message to a node. + Node(PublicKey), + /// We're sending this onion message to a blinded path. + BlindedPath(BlindedPath), +} + +impl Destination { + pub(super) fn num_hops(&self) -> usize { + match self { + Destination::Node(_) => 1, + Destination::BlindedPath(BlindedPath { blinded_hops, .. }) => blinded_hops.len(), + } + } +} + +/// Errors that may occur when [sending an onion message]. +/// +/// [sending an onion message]: OnionMessenger::send_onion_message +#[derive(Debug, PartialEq, Eq)] +pub enum SendError { + /// Errored computing onion message packet keys. + Secp256k1(secp256k1::Error), + /// Because implementations such as Eclair will drop onion messages where the message packet + /// exceeds 32834 bytes, we refuse to send messages where the packet exceeds this size. + TooBigPacket, + /// The provided [`Destination`] was an invalid [`BlindedPath`], due to having fewer than two + /// blinded hops. + TooFewBlindedHops, + /// Our next-hop peer was offline or does not support onion message forwarding. + InvalidFirstHop, + /// Onion message contents must have a TLV type >= 64. + InvalidMessage, + /// Our next-hop peer's buffer was full or our total outbound buffer was full. + BufferFull, + /// Failed to retrieve our node id from the provided [`KeysInterface`]. + /// + /// [`KeysInterface`]: crate::chain::keysinterface::KeysInterface + GetNodeIdFailed, + /// We attempted to send to a blinded path where we are the introduction node, and failed to + /// advance the blinded path to make the second hop the new introduction node. Either + /// [`KeysInterface::ecdh`] failed, we failed to tweak the current blinding point to get the + /// new blinding point, or we were attempting to send to ourselves. + BlindedPathAdvanceFailed, +} + +/// Handler for custom onion messages. If you are using [`SimpleArcOnionMessenger`], +/// [`SimpleRefOnionMessenger`], or prefer to ignore inbound custom onion messages, +/// [`IgnoringMessageHandler`] must be provided to [`OnionMessenger::new`]. Otherwise, a custom +/// implementation of this trait must be provided, with [`CustomMessage`] specifying the supported +/// message types. +/// +/// See [`OnionMessenger`] for example usage. +/// +/// [`IgnoringMessageHandler`]: crate::ln::peer_handler::IgnoringMessageHandler +/// [`CustomMessage`]: Self::CustomMessage +pub trait CustomOnionMessageHandler { + /// The message known to the handler. To support multiple message types, you may want to make this + /// an enum with a variant for each supported message. + type CustomMessage: CustomOnionMessageContents; + /// Called with the custom message that was received. + fn handle_custom_message(&self, msg: Self::CustomMessage); + /// Read a custom message of type `message_type` from `buffer`, returning `Ok(None)` if the + /// message type is unknown. + fn read_custom_message(&self, message_type: u64, buffer: &mut R) -> Result, msgs::DecodeError>; +} + +impl OnionMessenger + where K::Target: KeysInterface, L::Target: Logger, + CMH::Target: CustomOnionMessageHandler, { /// Constructs a new `OnionMessenger` to send, forward, and delegate received onion messages to /// their respective handlers. - pub fn new(keys_manager: K, logger: L) -> Self { + pub fn new(keys_manager: K, logger: L, custom_handler: CMH) -> Self { let mut secp_ctx = Secp256k1::new(); secp_ctx.seeded_randomize(&keys_manager.get_secure_random_bytes()); OnionMessenger { @@ -51,8 +202,256 @@ impl OnionMessenger pending_messages: Mutex::new(HashMap::new()), secp_ctx, logger, + custom_handler, } } + + /// Send an onion message with contents `message` to `destination`, routing it through `intermediate_nodes`. + /// See [`OnionMessenger`] for example usage. + pub fn send_onion_message(&self, intermediate_nodes: &[PublicKey], mut destination: Destination, message: OnionMessageContents, reply_path: Option) -> Result<(), SendError> { + if let Destination::BlindedPath(BlindedPath { ref blinded_hops, .. }) = destination { + if blinded_hops.len() < 2 { + return Err(SendError::TooFewBlindedHops); + } + } + let OnionMessageContents::Custom(ref msg) = message; + if msg.tlv_type() < 64 { return Err(SendError::InvalidMessage) } + + // If we are sending straight to a blinded path and we are the introduction node, we need to + // advance the blinded path by 1 hop so the second hop is the new introduction node. + if intermediate_nodes.len() == 0 { + if let Destination::BlindedPath(ref mut blinded_path) = destination { + let our_node_id = self.keys_manager.get_node_id(Recipient::Node) + .map_err(|()| SendError::GetNodeIdFailed)?; + if blinded_path.introduction_node_id == our_node_id { + blinded_path.advance_by_one(&self.keys_manager, &self.secp_ctx) + .map_err(|()| SendError::BlindedPathAdvanceFailed)?; + } + } + } + + let blinding_secret_bytes = self.keys_manager.get_secure_random_bytes(); + let blinding_secret = SecretKey::from_slice(&blinding_secret_bytes[..]).expect("RNG is busted"); + let (introduction_node_id, blinding_point) = if intermediate_nodes.len() != 0 { + (intermediate_nodes[0], PublicKey::from_secret_key(&self.secp_ctx, &blinding_secret)) + } else { + match destination { + Destination::Node(pk) => (pk, PublicKey::from_secret_key(&self.secp_ctx, &blinding_secret)), + Destination::BlindedPath(BlindedPath { introduction_node_id, blinding_point, .. }) => + (introduction_node_id, blinding_point), + } + }; + let (packet_payloads, packet_keys) = packet_payloads_and_keys( + &self.secp_ctx, intermediate_nodes, destination, message, reply_path, &blinding_secret) + .map_err(|e| SendError::Secp256k1(e))?; + + let prng_seed = self.keys_manager.get_secure_random_bytes(); + let onion_routing_packet = construct_onion_message_packet( + packet_payloads, packet_keys, prng_seed).map_err(|()| SendError::TooBigPacket)?; + + let mut pending_per_peer_msgs = self.pending_messages.lock().unwrap(); + if outbound_buffer_full(&introduction_node_id, &pending_per_peer_msgs) { return Err(SendError::BufferFull) } + match pending_per_peer_msgs.entry(introduction_node_id) { + hash_map::Entry::Vacant(_) => Err(SendError::InvalidFirstHop), + hash_map::Entry::Occupied(mut e) => { + e.get_mut().push_back(msgs::OnionMessage { blinding_point, onion_routing_packet }); + Ok(()) + } + } + } + + #[cfg(test)] + pub(super) fn release_pending_msgs(&self) -> HashMap> { + let mut pending_msgs = self.pending_messages.lock().unwrap(); + let mut msgs = HashMap::new(); + // We don't want to disconnect the peers by removing them entirely from the original map, so we + // swap the pending message buffers individually. + for (peer_node_id, pending_messages) in &mut *pending_msgs { + msgs.insert(*peer_node_id, core::mem::take(pending_messages)); + } + msgs + } +} + +fn outbound_buffer_full(peer_node_id: &PublicKey, buffer: &HashMap>) -> bool { + const MAX_TOTAL_BUFFER_SIZE: usize = (1 << 20) * 128; + const MAX_PER_PEER_BUFFER_SIZE: usize = (1 << 10) * 256; + let mut total_buffered_bytes = 0; + let mut peer_buffered_bytes = 0; + for (pk, peer_buf) in buffer { + for om in peer_buf { + let om_len = om.serialized_length(); + if pk == peer_node_id { + peer_buffered_bytes += om_len; + } + total_buffered_bytes += om_len; + + if total_buffered_bytes >= MAX_TOTAL_BUFFER_SIZE || + peer_buffered_bytes >= MAX_PER_PEER_BUFFER_SIZE + { + return true + } + } + } + false +} + +impl OnionMessageHandler for OnionMessenger + where K::Target: KeysInterface, + L::Target: Logger, + CMH::Target: CustomOnionMessageHandler + Sized, +{ + /// Handle an incoming onion message. Currently, if a message was destined for us we will log, but + /// soon we'll delegate the onion message to a handler that can generate invoices or send + /// payments. + fn handle_onion_message(&self, _peer_node_id: &PublicKey, msg: &msgs::OnionMessage) { + let control_tlvs_ss = match self.keys_manager.ecdh(Recipient::Node, &msg.blinding_point, None) { + Ok(ss) => ss, + Err(e) => { + log_error!(self.logger, "Failed to retrieve node secret: {:?}", e); + return + } + }; + let onion_decode_ss = { + let blinding_factor = { + let mut hmac = HmacEngine::::new(b"blinded_node_id"); + hmac.input(control_tlvs_ss.as_ref()); + Hmac::from_engine(hmac).into_inner() + }; + match self.keys_manager.ecdh(Recipient::Node, &msg.onion_routing_packet.public_key, + Some(&Scalar::from_be_bytes(blinding_factor).unwrap())) + { + Ok(ss) => ss.secret_bytes(), + Err(()) => { + log_trace!(self.logger, "Failed to compute onion packet shared secret"); + return + } + } + }; + match onion_utils::decode_next_untagged_hop(onion_decode_ss, &msg.onion_routing_packet.hop_data[..], + msg.onion_routing_packet.hmac, (control_tlvs_ss, &*self.custom_handler)) + { + Ok((Payload::Receive::<<::Target as CustomOnionMessageHandler>::CustomMessage> { + message, control_tlvs: ReceiveControlTlvs::Unblinded(ReceiveTlvs { path_id }), reply_path, + }, None)) => { + log_info!(self.logger, + "Received an onion message with path_id {:02x?} and {} reply_path", + path_id, if reply_path.is_some() { "a" } else { "no" }); + match message { + OnionMessageContents::Custom(msg) => self.custom_handler.handle_custom_message(msg), + } + }, + Ok((Payload::Forward(ForwardControlTlvs::Unblinded(ForwardTlvs { + next_node_id, next_blinding_override + })), Some((next_hop_hmac, new_packet_bytes)))) => { + // TODO: we need to check whether `next_node_id` is our node, in which case this is a dummy + // blinded hop and this onion message is destined for us. In this situation, we should keep + // unwrapping the onion layers to get to the final payload. Since we don't have the option + // of creating blinded paths with dummy hops currently, we should be ok to not handle this + // for now. + let new_pubkey = match onion_utils::next_hop_packet_pubkey(&self.secp_ctx, msg.onion_routing_packet.public_key, &onion_decode_ss) { + Ok(pk) => pk, + Err(e) => { + log_trace!(self.logger, "Failed to compute next hop packet pubkey: {}", e); + return + } + }; + let outgoing_packet = Packet { + version: 0, + public_key: new_pubkey, + hop_data: new_packet_bytes, + hmac: next_hop_hmac, + }; + let onion_message = msgs::OnionMessage { + blinding_point: match next_blinding_override { + Some(blinding_point) => blinding_point, + None => { + let blinding_factor = { + let mut sha = Sha256::engine(); + sha.input(&msg.blinding_point.serialize()[..]); + sha.input(control_tlvs_ss.as_ref()); + Sha256::from_engine(sha).into_inner() + }; + let next_blinding_point = msg.blinding_point; + match next_blinding_point.mul_tweak(&self.secp_ctx, &Scalar::from_be_bytes(blinding_factor).unwrap()) { + Ok(bp) => bp, + Err(e) => { + log_trace!(self.logger, "Failed to compute next blinding point: {}", e); + return + } + } + }, + }, + onion_routing_packet: outgoing_packet, + }; + + let mut pending_per_peer_msgs = self.pending_messages.lock().unwrap(); + if outbound_buffer_full(&next_node_id, &pending_per_peer_msgs) { + log_trace!(self.logger, "Dropping forwarded onion message to peer {:?}: outbound buffer full", next_node_id); + return + } + + #[cfg(fuzzing)] + pending_per_peer_msgs.entry(next_node_id).or_insert_with(VecDeque::new); + + match pending_per_peer_msgs.entry(next_node_id) { + hash_map::Entry::Vacant(_) => { + log_trace!(self.logger, "Dropping forwarded onion message to disconnected peer {:?}", next_node_id); + return + }, + hash_map::Entry::Occupied(mut e) => { + e.get_mut().push_back(onion_message); + log_trace!(self.logger, "Forwarding an onion message to peer {}", next_node_id); + } + }; + }, + Err(e) => { + log_trace!(self.logger, "Errored decoding onion message packet: {:?}", e); + }, + _ => { + log_trace!(self.logger, "Received bogus onion message packet, either the sender encoded a final hop as a forwarding hop or vice versa"); + }, + }; + } + + fn peer_connected(&self, their_node_id: &PublicKey, init: &msgs::Init) -> Result<(), ()> { + if init.features.supports_onion_messages() { + let mut peers = self.pending_messages.lock().unwrap(); + peers.insert(their_node_id.clone(), VecDeque::new()); + } + Ok(()) + } + + fn peer_disconnected(&self, their_node_id: &PublicKey, _no_connection_possible: bool) { + let mut pending_msgs = self.pending_messages.lock().unwrap(); + pending_msgs.remove(their_node_id); + } + + fn provided_node_features(&self) -> NodeFeatures { + let mut features = NodeFeatures::empty(); + features.set_onion_messages_optional(); + features + } + + fn provided_init_features(&self, _their_node_id: &PublicKey) -> InitFeatures { + let mut features = InitFeatures::empty(); + features.set_onion_messages_optional(); + features + } +} + +impl OnionMessageProvider for OnionMessenger + where K::Target: KeysInterface, + L::Target: Logger, + CMH::Target: CustomOnionMessageHandler, +{ + fn next_onion_message_for_peer(&self, peer_node_id: PublicKey) -> Option { + let mut pending_msgs = self.pending_messages.lock().unwrap(); + if let Some(msgs) = pending_msgs.get_mut(&peer_node_id) { + return msgs.pop_front() + } + None + } } // TODO: parameterize the below Simple* types with OnionMessenger and handle the messages it @@ -60,12 +459,110 @@ impl OnionMessenger /// Useful for simplifying the parameters of [`SimpleArcChannelManager`] and /// [`SimpleArcPeerManager`]. See their docs for more details. /// -///[`SimpleArcChannelManager`]: crate::ln::channelmanager::SimpleArcChannelManager -///[`SimpleArcPeerManager`]: crate::ln::peer_handler::SimpleArcPeerManager -pub type SimpleArcOnionMessenger = OnionMessenger, Arc>; +/// (C-not exported) as `Arc`s don't make sense in bindings. +/// +/// [`SimpleArcChannelManager`]: crate::ln::channelmanager::SimpleArcChannelManager +/// [`SimpleArcPeerManager`]: crate::ln::peer_handler::SimpleArcPeerManager +pub type SimpleArcOnionMessenger = OnionMessenger, Arc, IgnoringMessageHandler>; /// Useful for simplifying the parameters of [`SimpleRefChannelManager`] and /// [`SimpleRefPeerManager`]. See their docs for more details. /// -///[`SimpleRefChannelManager`]: crate::ln::channelmanager::SimpleRefChannelManager -///[`SimpleRefPeerManager`]: crate::ln::peer_handler::SimpleRefPeerManager -pub type SimpleRefOnionMessenger<'a, 'b, L> = OnionMessenger; +/// (C-not exported) as general type aliases don't make sense in bindings. +/// +/// [`SimpleRefChannelManager`]: crate::ln::channelmanager::SimpleRefChannelManager +/// [`SimpleRefPeerManager`]: crate::ln::peer_handler::SimpleRefPeerManager +pub type SimpleRefOnionMessenger<'a, 'b, L> = OnionMessenger<&'a KeysManager, &'b L, IgnoringMessageHandler>; + +/// Construct onion packet payloads and keys for sending an onion message along the given +/// `unblinded_path` to the given `destination`. +fn packet_payloads_and_keys( + secp_ctx: &Secp256k1, unblinded_path: &[PublicKey], destination: Destination, + message: OnionMessageContents, mut reply_path: Option, session_priv: &SecretKey +) -> Result<(Vec<(Payload, [u8; 32])>, Vec), secp256k1::Error> { + let num_hops = unblinded_path.len() + destination.num_hops(); + let mut payloads = Vec::with_capacity(num_hops); + let mut onion_packet_keys = Vec::with_capacity(num_hops); + + let (mut intro_node_id_blinding_pt, num_blinded_hops) = if let Destination::BlindedPath(BlindedPath { + introduction_node_id, blinding_point, blinded_hops }) = &destination { + (Some((*introduction_node_id, *blinding_point)), blinded_hops.len()) } else { (None, 0) }; + let num_unblinded_hops = num_hops - num_blinded_hops; + + let mut unblinded_path_idx = 0; + let mut blinded_path_idx = 0; + let mut prev_control_tlvs_ss = None; + let mut final_control_tlvs = None; + utils::construct_keys_callback(secp_ctx, unblinded_path, Some(destination), session_priv, |_, onion_packet_ss, ephemeral_pubkey, control_tlvs_ss, unblinded_pk_opt, enc_payload_opt| { + if num_unblinded_hops != 0 && unblinded_path_idx < num_unblinded_hops { + if let Some(ss) = prev_control_tlvs_ss.take() { + payloads.push((Payload::Forward(ForwardControlTlvs::Unblinded( + ForwardTlvs { + next_node_id: unblinded_pk_opt.unwrap(), + next_blinding_override: None, + } + )), ss)); + } + prev_control_tlvs_ss = Some(control_tlvs_ss); + unblinded_path_idx += 1; + } else if let Some((intro_node_id, blinding_pt)) = intro_node_id_blinding_pt.take() { + if let Some(control_tlvs_ss) = prev_control_tlvs_ss.take() { + payloads.push((Payload::Forward(ForwardControlTlvs::Unblinded(ForwardTlvs { + next_node_id: intro_node_id, + next_blinding_override: Some(blinding_pt), + })), control_tlvs_ss)); + } + } + if blinded_path_idx < num_blinded_hops.saturating_sub(1) && enc_payload_opt.is_some() { + payloads.push((Payload::Forward(ForwardControlTlvs::Blinded(enc_payload_opt.unwrap())), + control_tlvs_ss)); + blinded_path_idx += 1; + } else if let Some(encrypted_payload) = enc_payload_opt { + final_control_tlvs = Some(ReceiveControlTlvs::Blinded(encrypted_payload)); + prev_control_tlvs_ss = Some(control_tlvs_ss); + } + + let (rho, mu) = onion_utils::gen_rho_mu_from_shared_secret(onion_packet_ss.as_ref()); + onion_packet_keys.push(onion_utils::OnionKeys { + #[cfg(test)] + shared_secret: onion_packet_ss, + #[cfg(test)] + blinding_factor: [0; 32], + ephemeral_pubkey, + rho, + mu, + }); + })?; + + if let Some(control_tlvs) = final_control_tlvs { + payloads.push((Payload::Receive { + control_tlvs, + reply_path: reply_path.take(), + message, + }, prev_control_tlvs_ss.unwrap())); + } else { + payloads.push((Payload::Receive { + control_tlvs: ReceiveControlTlvs::Unblinded(ReceiveTlvs { path_id: None, }), + reply_path: reply_path.take(), + message, + }, prev_control_tlvs_ss.unwrap())); + } + + Ok((payloads, onion_packet_keys)) +} + +/// Errors if the serialized payload size exceeds onion_message::BIG_PACKET_HOP_DATA_LEN +fn construct_onion_message_packet(payloads: Vec<(Payload, [u8; 32])>, onion_keys: Vec, prng_seed: [u8; 32]) -> Result { + // Spec rationale: + // "`len` allows larger messages to be sent than the standard 1300 bytes allowed for an HTLC + // onion, but this should be used sparingly as it is reduces anonymity set, hence the + // recommendation that it either look like an HTLC onion, or if larger, be a fixed size." + let payloads_ser_len = onion_utils::payloads_serialized_length(&payloads); + let hop_data_len = if payloads_ser_len <= SMALL_PACKET_HOP_DATA_LEN { + SMALL_PACKET_HOP_DATA_LEN + } else if payloads_ser_len <= BIG_PACKET_HOP_DATA_LEN { + BIG_PACKET_HOP_DATA_LEN + } else { return Err(()) }; + + Ok(onion_utils::construct_onion_message_packet::<_, _>( + payloads, onion_keys, prng_seed, hop_data_len)) +}