_ Git - rust-lightning/blob - lightning/src/blinded_path/mod.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 //! Creating blinded paths and related utilities live here.
  11
  12 pub mod payment;
  13 pub mod message;
  14 pub(crate) mod utils;
  15
  16 use bitcoin::secp256k1::{self, PublicKey, Secp256k1, SecretKey};
  17 use core::ops::Deref;
  18
  19 use crate::ln::msgs::DecodeError;
  20 use crate::offers::invoice::BlindedPayInfo;
  21 use crate::routing::gossip::{NodeId, ReadOnlyNetworkGraph};
  22 use crate::sign::EntropySource;
  23 use crate::util::ser::{Readable, Writeable, Writer};
  24 use crate::util::scid_utils;
  25
  26 use crate::io;
  27 use crate::prelude::*;
  28
  29 /// The next hop to forward an onion message along its path.
  30 ///
  31 /// Note that payment blinded paths always specify their next hop using an explicit node id.
  32 #[derive(Clone, Debug, Hash, PartialEq, Eq)]
  33 pub enum NextMessageHop {
  34         /// The node id of the next hop.
  35         NodeId(PublicKey),
  36         /// The short channel id leading to the next hop.
  37         ShortChannelId(u64),
  38 }
  39
  40 /// Onion messages and payments can be sent and received to blinded paths, which serve to hide the
  41 /// identity of the recipient.
  42 #[derive(Clone, Debug, Hash, PartialEq, Eq)]
  43 pub struct BlindedPath {
  44         /// To send to a blinded path, the sender first finds a route to the unblinded
  45         /// `introduction_node`, which can unblind its [`encrypted_payload`] to find out the onion
  46         /// message or payment's next hop and forward it along.
  47         ///
  48         /// [`encrypted_payload`]: BlindedHop::encrypted_payload
  49         pub introduction_node: IntroductionNode,
  50         /// Used by the introduction node to decrypt its [`encrypted_payload`] to forward the onion
  51         /// message or payment.
  52         ///
  53         /// [`encrypted_payload`]: BlindedHop::encrypted_payload
  54         pub blinding_point: PublicKey,
  55         /// The hops composing the blinded path.
  56         pub blinded_hops: Vec<BlindedHop>,
  57 }
  58
  59 /// The unblinded node in a [`BlindedPath`].
  60 #[derive(Clone, Debug, Hash, PartialEq, Eq)]
  61 pub enum IntroductionNode {
  62         /// The node id of the introduction node.
  63         NodeId(PublicKey),
  64         /// The short channel id of the channel leading to the introduction node. The [`Direction`]
  65         /// identifies which side of the channel is the introduction node.
  66         DirectedShortChannelId(Direction, u64),
  67 }
  68
  69 /// The side of a channel that is the [`IntroductionNode`] in a [`BlindedPath`]. [BOLT 7] defines
  70 /// which nodes is which in the [`ChannelAnnouncement`] message.
  71 ///
  72 /// [BOLT 7]: https://github.com/lightning/bolts/blob/master/07-routing-gossip.md#the-channel_announcement-message
  73 /// [`ChannelAnnouncement`]: crate::ln::msgs::ChannelAnnouncement
  74 #[derive(Clone, Copy, Debug, Hash, PartialEq, Eq)]
  75 pub enum Direction {
  76         /// The lesser node id when compared lexicographically in ascending order.
  77         NodeOne,
  78         /// The greater node id when compared lexicographically in ascending order.
  79         NodeTwo,
  80 }
  81
  82 /// An interface for looking up the node id of a channel counterparty for the purpose of forwarding
  83 /// an [`OnionMessage`].
  84 ///
  85 /// [`OnionMessage`]: crate::ln::msgs::OnionMessage
  86 pub trait NodeIdLookUp {
  87         /// Returns the node id of the forwarding node's channel counterparty with `short_channel_id`.
  88         ///
  89         /// Here, the forwarding node is referring to the node of the [`OnionMessenger`] parameterized
  90         /// by the [`NodeIdLookUp`] and the counterparty to one of that node's peers.
  91         ///
  92         /// [`OnionMessenger`]: crate::onion_message::messenger::OnionMessenger
  93         fn next_node_id(&self, short_channel_id: u64) -> Option<PublicKey>;
  94 }
  95
  96 /// A [`NodeIdLookUp`] that always returns `None`.
  97 pub struct EmptyNodeIdLookUp {}
  98
  99 impl NodeIdLookUp for EmptyNodeIdLookUp {
 100         fn next_node_id(&self, _short_channel_id: u64) -> Option<PublicKey> {
 101                 None
 102         }
 103 }
 104
 105 impl Deref for EmptyNodeIdLookUp {
 106         type Target = EmptyNodeIdLookUp;
 107         fn deref(&self) -> &Self { self }
 108 }
 109
 110 /// An encrypted payload and node id corresponding to a hop in a payment or onion message path, to
 111 /// be encoded in the sender's onion packet. These hops cannot be identified by outside observers
 112 /// and thus can be used to hide the identity of the recipient.
 113 #[derive(Clone, Debug, Hash, PartialEq, Eq)]
 114 pub struct BlindedHop {
 115         /// The blinded node id of this hop in a [`BlindedPath`].
 116         pub blinded_node_id: PublicKey,
 117         /// The encrypted payload intended for this hop in a [`BlindedPath`].
 118         // The node sending to this blinded path will later encode this payload into the onion packet for
 119         // this hop.
 120         pub encrypted_payload: Vec<u8>,
 121 }
 122
 123 impl BlindedPath {
 124         /// Create a one-hop blinded path for a message.
 125         pub fn one_hop_for_message<ES: Deref, T: secp256k1::Signing + secp256k1::Verification>(
 126                 recipient_node_id: PublicKey, entropy_source: ES, secp_ctx: &Secp256k1<T>
 127         ) -> Result<Self, ()> where ES::Target: EntropySource {
 128                 Self::new_for_message(&[], recipient_node_id, entropy_source, secp_ctx)
 129         }
 130
 131         /// Create a blinded path for an onion message, to be forwarded along `node_pks`. The last node
 132         /// pubkey in `node_pks` will be the destination node.
 133         ///
 134         /// Errors if no hops are provided or if `node_pk`(s) are invalid.
 135         //  TODO: make all payloads the same size with padding + add dummy hops
 136         pub fn new_for_message<ES: Deref, T: secp256k1::Signing + secp256k1::Verification>(
 137                 intermediate_nodes: &[message::ForwardNode], recipient_node_id: PublicKey,
 138                 entropy_source: ES, secp_ctx: &Secp256k1<T>
 139         ) -> Result<Self, ()> where ES::Target: EntropySource {
 140                 let introduction_node = IntroductionNode::NodeId(
 141                         intermediate_nodes.first().map_or(recipient_node_id, |n| n.node_id)
 142                 );
 143                 let blinding_secret_bytes = entropy_source.get_secure_random_bytes();
 144                 let blinding_secret = SecretKey::from_slice(&blinding_secret_bytes[..]).expect("RNG is busted");
 145
 146                 Ok(BlindedPath {
 147                         introduction_node,
 148                         blinding_point: PublicKey::from_secret_key(secp_ctx, &blinding_secret),
 149                         blinded_hops: message::blinded_hops(
 150                                 secp_ctx, intermediate_nodes, recipient_node_id, &blinding_secret,
 151                         ).map_err(|_| ())?,
 152                 })
 153         }
 154
 155         /// Create a one-hop blinded path for a payment.
 156         pub fn one_hop_for_payment<ES: Deref, T: secp256k1::Signing + secp256k1::Verification>(
 157                 payee_node_id: PublicKey, payee_tlvs: payment::ReceiveTlvs, min_final_cltv_expiry_delta: u16,
 158                 entropy_source: ES, secp_ctx: &Secp256k1<T>
 159         ) -> Result<(BlindedPayInfo, Self), ()> where ES::Target: EntropySource {
 160                 // This value is not considered in pathfinding for 1-hop blinded paths, because it's intended to
 161                 // be in relation to a specific channel.
 162                 let htlc_maximum_msat = u64::max_value();
 163                 Self::new_for_payment(
 164                         &[], payee_node_id, payee_tlvs, htlc_maximum_msat, min_final_cltv_expiry_delta,
 165                         entropy_source, secp_ctx
 166                 )
 167         }
 168
 169         /// Create a blinded path for a payment, to be forwarded along `intermediate_nodes`.
 170         ///
 171         /// Errors if:
 172         /// * a provided node id is invalid
 173         /// * [`BlindedPayInfo`] calculation results in an integer overflow
 174         /// * any unknown features are required in the provided [`ForwardTlvs`]
 175         ///
 176         /// [`ForwardTlvs`]: crate::blinded_path::payment::ForwardTlvs
 177         //  TODO: make all payloads the same size with padding + add dummy hops
 178         pub fn new_for_payment<ES: Deref, T: secp256k1::Signing + secp256k1::Verification>(
 179                 intermediate_nodes: &[payment::ForwardNode], payee_node_id: PublicKey,
 180                 payee_tlvs: payment::ReceiveTlvs, htlc_maximum_msat: u64, min_final_cltv_expiry_delta: u16,
 181                 entropy_source: ES, secp_ctx: &Secp256k1<T>
 182         ) -> Result<(BlindedPayInfo, Self), ()> where ES::Target: EntropySource {
 183                 let introduction_node = IntroductionNode::NodeId(
 184                         intermediate_nodes.first().map_or(payee_node_id, |n| n.node_id)
 185                 );
 186                 let blinding_secret_bytes = entropy_source.get_secure_random_bytes();
 187                 let blinding_secret = SecretKey::from_slice(&blinding_secret_bytes[..]).expect("RNG is busted");
 188
 189                 let blinded_payinfo = payment::compute_payinfo(
 190                         intermediate_nodes, &payee_tlvs, htlc_maximum_msat, min_final_cltv_expiry_delta
 191                 )?;
 192                 Ok((blinded_payinfo, BlindedPath {
 193                         introduction_node,
 194                         blinding_point: PublicKey::from_secret_key(secp_ctx, &blinding_secret),
 195                         blinded_hops: payment::blinded_hops(
 196                                 secp_ctx, intermediate_nodes, payee_node_id, payee_tlvs, &blinding_secret
 197                         ).map_err(|_| ())?,
 198                 }))
 199         }
 200
 201         /// Returns the introduction [`NodeId`] of the blinded path, if it is publicly reachable (i.e.,
 202         /// it is found in the network graph).
 203         pub fn public_introduction_node_id<'a>(
 204                 &self, network_graph: &'a ReadOnlyNetworkGraph
 205         ) -> Option<&'a NodeId> {
 206                 match &self.introduction_node {
 207                         IntroductionNode::NodeId(pubkey) => {
 208                                 let node_id = NodeId::from_pubkey(pubkey);
 209                                 network_graph.nodes().get_key_value(&node_id).map(|(key, _)| key)
 210                         },
 211                         IntroductionNode::DirectedShortChannelId(direction, scid) => {
 212                                 network_graph
 213                                         .channel(*scid)
 214                                         .map(|c| match direction {
 215                                                 Direction::NodeOne => &c.node_one,
 216                                                 Direction::NodeTwo => &c.node_two,
 217                                         })
 218                         },
 219                 }
 220         }
 221
 222         /// Attempts to a use a compact representation for the [`IntroductionNode`] by using a directed
 223         /// short channel id from a channel in `network_graph` leading to the introduction node.
 224         ///
 225         /// While this may result in a smaller encoding, there is a trade off in that the path may
 226         /// become invalid if the channel is closed or hasn't been propagated via gossip. Therefore,
 227         /// calling this may not be suitable for long-lived blinded paths.
 228         pub fn use_compact_introduction_node(&mut self, network_graph: &ReadOnlyNetworkGraph) {
 229                 if let IntroductionNode::NodeId(pubkey) = &self.introduction_node {
 230                         let node_id = NodeId::from_pubkey(pubkey);
 231                         if let Some(node_info) = network_graph.node(&node_id) {
 232                                 if let Some((scid, channel_info)) = node_info
 233                                         .channels
 234                                         .iter()
 235                                         .filter_map(|scid| network_graph.channel(*scid).map(|info| (*scid, info)))
 236                                         .min_by_key(|(scid, _)| scid_utils::block_from_scid(*scid))
 237                                 {
 238                                         let direction = if node_id == channel_info.node_one {
 239                                                 Direction::NodeOne
 240                                         } else {
 241                                                 debug_assert_eq!(node_id, channel_info.node_two);
 242                                                 Direction::NodeTwo
 243                                         };
 244                                         self.introduction_node =
 245                                                 IntroductionNode::DirectedShortChannelId(direction, scid);
 246                                 }
 247                         }
 248                 }
 249         }
 250 }
 251
 252 impl Writeable for BlindedPath {
 253         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 254                 match &self.introduction_node {
 255                         IntroductionNode::NodeId(pubkey) => pubkey.write(w)?,
 256                         IntroductionNode::DirectedShortChannelId(direction, scid) => {
 257                                 match direction {
 258                                         Direction::NodeOne => 0u8.write(w)?,
 259                                         Direction::NodeTwo => 1u8.write(w)?,
 260                                 }
 261                                 scid.write(w)?;
 262                         },
 263                 }
 264
 265                 self.blinding_point.write(w)?;
 266                 (self.blinded_hops.len() as u8).write(w)?;
 267                 for hop in &self.blinded_hops {
 268                         hop.write(w)?;
 269                 }
 270                 Ok(())
 271         }
 272 }
 273
 274 impl Readable for BlindedPath {
 275         fn read<R: io::Read>(r: &mut R) -> Result<Self, DecodeError> {
 276                 let mut first_byte: u8 = Readable::read(r)?;
 277                 let introduction_node = match first_byte {
 278                         0 => IntroductionNode::DirectedShortChannelId(Direction::NodeOne, Readable::read(r)?),
 279                         1 => IntroductionNode::DirectedShortChannelId(Direction::NodeTwo, Readable::read(r)?),
 280                         2|3 => {
 281                                 use io::Read;
 282                                 let mut pubkey_read = core::slice::from_mut(&mut first_byte).chain(r.by_ref());
 283                                 IntroductionNode::NodeId(Readable::read(&mut pubkey_read)?)
 284                         },
 285                         _ => return Err(DecodeError::InvalidValue),
 286                 };
 287                 let blinding_point = Readable::read(r)?;
 288                 let num_hops: u8 = Readable::read(r)?;
 289                 if num_hops == 0 { return Err(DecodeError::InvalidValue) }
 290                 let mut blinded_hops: Vec<BlindedHop> = Vec::with_capacity(num_hops.into());
 291                 for _ in 0..num_hops {
 292                         blinded_hops.push(Readable::read(r)?);
 293                 }
 294                 Ok(BlindedPath {
 295                         introduction_node,
 296                         blinding_point,
 297                         blinded_hops,
 298                 })
 299         }
 300 }
 301
 302 impl_writeable!(BlindedHop, {
 303         blinded_node_id,
 304         encrypted_payload
 305 });
 306
 307 impl Direction {
 308         /// Returns the [`NodeId`] from the inputs corresponding to the direction.
 309         pub fn select_node_id<'a>(&self, node_a: &'a NodeId, node_b: &'a NodeId) -> &'a NodeId {
 310                 match self {
 311                         Direction::NodeOne => core::cmp::min(node_a, node_b),
 312                         Direction::NodeTwo => core::cmp::max(node_a, node_b),
 313                 }
 314         }
 315
 316         /// Returns the [`PublicKey`] from the inputs corresponding to the direction.
 317         pub fn select_pubkey<'a>(&self, node_a: &'a PublicKey, node_b: &'a PublicKey) -> &'a PublicKey {
 318                 let (node_one, node_two) = if NodeId::from_pubkey(node_a) < NodeId::from_pubkey(node_b) {
 319                         (node_a, node_b)
 320                 } else {
 321                         (node_b, node_a)
 322                 };
 323                 match self {
 324                         Direction::NodeOne => node_one,
 325                         Direction::NodeTwo => node_two,
 326                 }
 327         }
 328 }