_ Git - rust-lightning/blob - lightning/src/onion_message/messenger.rs

   1 // This file is Copyright its original authors, visible in version control
   2 // history.
   3 //
   4 // This file is licensed under the Apache License, Version 2.0 <LICENSE-APACHE
   5 // or http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
   6 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your option.
   7 // You may not use this file except in accordance with one or both of these
   8 // licenses.
   9
  10 //! LDK sends, receives, and forwards onion messages via the [`OnionMessenger`]. See its docs for
  11 //! more information.
  12
  13 use bitcoin::secp256k1::{self, PublicKey, Secp256k1, SecretKey};
  14
  15 use chain::keysinterface::{InMemorySigner, KeysInterface, KeysManager, Sign};
  16 use ln::msgs;
  17 use ln::onion_utils;
  18 use super::blinded_route::{BlindedRoute, ForwardTlvs, ReceiveTlvs};
  19 use super::packet::{BIG_PACKET_HOP_DATA_LEN, ForwardControlTlvs, Packet, Payload, ReceiveControlTlvs, SMALL_PACKET_HOP_DATA_LEN};
  20 use super::utils;
  21 use util::logger::Logger;
  22
  23 use core::ops::Deref;
  24 use sync::{Arc, Mutex};
  25 use prelude::*;
  26
  27 /// A sender, receiver and forwarder of onion messages. In upcoming releases, this object will be
  28 /// used to retrieve invoices and fulfill invoice requests from [offers].
  29 ///
  30 /// [offers]: <https://github.com/lightning/bolts/pull/798>
  31 pub struct OnionMessenger<Signer: Sign, K: Deref, L: Deref>
  32         where K::Target: KeysInterface<Signer = Signer>,
  33               L::Target: Logger,
  34 {
  35         keys_manager: K,
  36         logger: L,
  37         pending_messages: Mutex<HashMap<PublicKey, Vec<msgs::OnionMessage>>>,
  38         secp_ctx: Secp256k1<secp256k1::All>,
  39         // Coming soon:
  40         // invoice_handler: InvoiceHandler,
  41         // custom_handler: CustomHandler, // handles custom onion messages
  42 }
  43
  44 /// The destination of an onion message.
  45 pub enum Destination {
  46         /// We're sending this onion message to a node.
  47         Node(PublicKey),
  48         /// We're sending this onion message to a blinded route.
  49         BlindedRoute(BlindedRoute),
  50 }
  51
  52 impl Destination {
  53         pub(super) fn num_hops(&self) -> usize {
  54                 match self {
  55                         Destination::Node(_) => 1,
  56                         Destination::BlindedRoute(BlindedRoute { blinded_hops, .. }) => blinded_hops.len(),
  57                 }
  58         }
  59 }
  60
  61 impl<Signer: Sign, K: Deref, L: Deref> OnionMessenger<Signer, K, L>
  62         where K::Target: KeysInterface<Signer = Signer>,
  63               L::Target: Logger,
  64 {
  65         /// Constructs a new `OnionMessenger` to send, forward, and delegate received onion messages to
  66         /// their respective handlers.
  67         pub fn new(keys_manager: K, logger: L) -> Self {
  68                 let mut secp_ctx = Secp256k1::new();
  69                 secp_ctx.seeded_randomize(&keys_manager.get_secure_random_bytes());
  70                 OnionMessenger {
  71                         keys_manager,
  72                         pending_messages: Mutex::new(HashMap::new()),
  73                         secp_ctx,
  74                         logger,
  75                 }
  76         }
  77
  78         /// Send an empty onion message to `destination`, routing it through `intermediate_nodes`.
  79         pub fn send_onion_message(&self, intermediate_nodes: &[PublicKey], destination: Destination) -> Result<(), secp256k1::Error> {
  80                 let blinding_secret_bytes = self.keys_manager.get_secure_random_bytes();
  81                 let blinding_secret = SecretKey::from_slice(&blinding_secret_bytes[..]).expect("RNG is busted");
  82                 let (introduction_node_id, blinding_point) = if intermediate_nodes.len() != 0 {
  83                         (intermediate_nodes[0], PublicKey::from_secret_key(&self.secp_ctx, &blinding_secret))
  84                 } else {
  85                         match destination {
  86                                 Destination::Node(pk) => (pk, PublicKey::from_secret_key(&self.secp_ctx, &blinding_secret)),
  87                                 Destination::BlindedRoute(BlindedRoute { introduction_node_id, blinding_point, .. }) =>
  88                                         (introduction_node_id, blinding_point),
  89                         }
  90                 };
  91                 let (packet_payloads, packet_keys) = packet_payloads_and_keys(
  92                         &self.secp_ctx, intermediate_nodes, destination, &blinding_secret)?;
  93
  94                 let prng_seed = self.keys_manager.get_secure_random_bytes();
  95                 let onion_packet = construct_onion_message_packet(packet_payloads, packet_keys, prng_seed);
  96
  97                 let mut pending_per_peer_msgs = self.pending_messages.lock().unwrap();
  98                 let pending_msgs = pending_per_peer_msgs.entry(introduction_node_id).or_insert(Vec::new());
  99                 pending_msgs.push(
 100                         msgs::OnionMessage {
 101                                 blinding_point,
 102                                 onion_routing_packet: onion_packet,
 103                         }
 104                 );
 105                 Ok(())
 106         }
 107 }
 108
 109 // TODO: parameterize the below Simple* types with OnionMessenger and handle the messages it
 110 // produces
 111 /// Useful for simplifying the parameters of [`SimpleArcChannelManager`] and
 112 /// [`SimpleArcPeerManager`]. See their docs for more details.
 113 ///
 114 ///[`SimpleArcChannelManager`]: crate::ln::channelmanager::SimpleArcChannelManager
 115 ///[`SimpleArcPeerManager`]: crate::ln::peer_handler::SimpleArcPeerManager
 116 pub type SimpleArcOnionMessenger<L> = OnionMessenger<InMemorySigner, Arc<KeysManager>, Arc<L>>;
 117 /// Useful for simplifying the parameters of [`SimpleRefChannelManager`] and
 118 /// [`SimpleRefPeerManager`]. See their docs for more details.
 119 ///
 120 ///[`SimpleRefChannelManager`]: crate::ln::channelmanager::SimpleRefChannelManager
 121 ///[`SimpleRefPeerManager`]: crate::ln::peer_handler::SimpleRefPeerManager
 122 pub type SimpleRefOnionMessenger<'a, 'b, L> = OnionMessenger<InMemorySigner, &'a KeysManager, &'b L>;
 123
 124 /// Construct onion packet payloads and keys for sending an onion message along the given
 125 /// `unblinded_path` to the given `destination`.
 126 fn packet_payloads_and_keys<T: secp256k1::Signing + secp256k1::Verification>(
 127         secp_ctx: &Secp256k1<T>, unblinded_path: &[PublicKey], destination: Destination, session_priv: &SecretKey
 128 ) -> Result<(Vec<(Payload, [u8; 32])>, Vec<onion_utils::OnionKeys>), secp256k1::Error> {
 129         let num_hops = unblinded_path.len() + destination.num_hops();
 130         let mut payloads = Vec::with_capacity(num_hops);
 131         let mut onion_packet_keys = Vec::with_capacity(num_hops);
 132
 133         let (mut intro_node_id_blinding_pt, num_blinded_hops) = if let Destination::BlindedRoute(BlindedRoute {
 134                 introduction_node_id, blinding_point, blinded_hops }) = &destination {
 135                 (Some((*introduction_node_id, *blinding_point)), blinded_hops.len()) } else { (None, 0) };
 136         let num_unblinded_hops = num_hops - num_blinded_hops;
 137
 138         let mut unblinded_path_idx = 0;
 139         let mut blinded_path_idx = 0;
 140         let mut prev_control_tlvs_ss = None;
 141         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| {
 142                 if num_unblinded_hops != 0 && unblinded_path_idx < num_unblinded_hops {
 143                         if let Some(ss) = prev_control_tlvs_ss.take() {
 144                                 payloads.push((Payload::Forward(ForwardControlTlvs::Unblinded(
 145                                         ForwardTlvs {
 146                                                 next_node_id: unblinded_pk_opt.unwrap(),
 147                                                 next_blinding_override: None,
 148                                         }
 149                                 )), ss));
 150                         }
 151                         prev_control_tlvs_ss = Some(control_tlvs_ss);
 152                         unblinded_path_idx += 1;
 153                 } else if let Some((intro_node_id, blinding_pt)) = intro_node_id_blinding_pt.take() {
 154                         if let Some(control_tlvs_ss) = prev_control_tlvs_ss.take() {
 155                                 payloads.push((Payload::Forward(ForwardControlTlvs::Unblinded(ForwardTlvs {
 156                                         next_node_id: intro_node_id,
 157                                         next_blinding_override: Some(blinding_pt),
 158                                 })), control_tlvs_ss));
 159                         }
 160                         if let Some(encrypted_payload) = enc_payload_opt {
 161                                 payloads.push((Payload::Forward(ForwardControlTlvs::Blinded(encrypted_payload)),
 162                                         control_tlvs_ss));
 163                         } else { debug_assert!(false); }
 164                         blinded_path_idx += 1;
 165                 } else if blinded_path_idx < num_blinded_hops - 1 && enc_payload_opt.is_some() {
 166                         payloads.push((Payload::Forward(ForwardControlTlvs::Blinded(enc_payload_opt.unwrap())),
 167                                 control_tlvs_ss));
 168                         blinded_path_idx += 1;
 169                 } else if let Some(encrypted_payload) = enc_payload_opt {
 170                         payloads.push((Payload::Receive {
 171                                 control_tlvs: ReceiveControlTlvs::Blinded(encrypted_payload),
 172                         }, control_tlvs_ss));
 173                 }
 174
 175                 let (rho, mu) = onion_utils::gen_rho_mu_from_shared_secret(onion_packet_ss.as_ref());
 176                 onion_packet_keys.push(onion_utils::OnionKeys {
 177                         #[cfg(test)]
 178                         shared_secret: onion_packet_ss,
 179                         #[cfg(test)]
 180                         blinding_factor: [0; 32],
 181                         ephemeral_pubkey,
 182                         rho,
 183                         mu,
 184                 });
 185         })?;
 186
 187         if let Some(control_tlvs_ss) = prev_control_tlvs_ss {
 188                 payloads.push((Payload::Receive {
 189                         control_tlvs: ReceiveControlTlvs::Unblinded(ReceiveTlvs { path_id: None, })
 190                 }, control_tlvs_ss));
 191         }
 192
 193         Ok((payloads, onion_packet_keys))
 194 }
 195
 196 fn construct_onion_message_packet(payloads: Vec<(Payload, [u8; 32])>, onion_keys: Vec<onion_utils::OnionKeys>, prng_seed: [u8; 32]) -> Packet {
 197         // Spec rationale:
 198         // "`len` allows larger messages to be sent than the standard 1300 bytes allowed for an HTLC
 199         // onion, but this should be used sparingly as it is reduces anonymity set, hence the
 200         // recommendation that it either look like an HTLC onion, or if larger, be a fixed size."
 201         let payloads_ser_len = onion_utils::payloads_serialized_length(&payloads);
 202         let hop_data_len = if payloads_ser_len <= SMALL_PACKET_HOP_DATA_LEN {
 203                 SMALL_PACKET_HOP_DATA_LEN
 204         } else if payloads_ser_len <= BIG_PACKET_HOP_DATA_LEN {
 205                 BIG_PACKET_HOP_DATA_LEN
 206         } else { payloads_ser_len };
 207
 208         onion_utils::construct_onion_message_packet::<_, _>(payloads, onion_keys, prng_seed, hop_data_len)
 209 }