git.bitcoin.ninja Git - rust-lightning/blob - lightning/src/ln/channel_id.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 //! ChannelId definition.
  11
  12 use crate::chain::transaction::OutPoint;
  13 use crate::io;
  14 use crate::ln::msgs::DecodeError;
  15 use crate::sign::EntropySource;
  16 use crate::util::ser::{Readable, Writeable, Writer};
  17 use super::channel_keys::RevocationBasepoint;
  18
  19 use bitcoin::hashes::{
  20         Hash as _,
  21         HashEngine as _,
  22         sha256::Hash as Sha256,
  23 };
  24 use core::fmt;
  25 use core::ops::Deref;
  26
  27 /// A unique 32-byte identifier for a channel.
  28 /// Depending on how the ID is generated, several varieties are distinguished
  29 /// (but all are stored as 32 bytes):
  30 ///   _v1_ and _temporary_.
  31 /// A _v1_ channel ID is generated based on funding tx outpoint (txid & index).
  32 /// A _temporary_ ID is generated randomly.
  33 /// (Later revocation-point-based _v2_ is a possibility.)
  34 /// The variety (context) is not stored, it is relevant only at creation.
  35 ///
  36 /// This is not exported to bindings users as we just use [u8; 32] directly.
  37 #[derive(Clone, Copy, Debug, Eq, Hash, Ord, PartialEq, PartialOrd)]
  38 pub struct ChannelId(pub [u8; 32]);
  39
  40 impl ChannelId {
  41         /// Create _v1_ channel ID based on a funding TX ID and output index
  42         pub fn v1_from_funding_txid(txid: &[u8; 32], output_index: u16) -> Self {
  43                 let mut res = [0; 32];
  44                 res[..].copy_from_slice(&txid[..]);
  45                 res[30] ^= ((output_index >> 8) & 0xff) as u8;
  46                 res[31] ^= ((output_index >> 0) & 0xff) as u8;
  47                 Self(res)
  48         }
  49
  50         /// Create _v1_ channel ID from a funding tx outpoint
  51         pub fn v1_from_funding_outpoint(outpoint: OutPoint) -> Self {
  52                 Self::v1_from_funding_txid(outpoint.txid.as_byte_array(), outpoint.index)
  53         }
  54
  55         /// Create a _temporary_ channel ID randomly, based on an entropy source.
  56         pub fn temporary_from_entropy_source<ES: Deref>(entropy_source: &ES) -> Self
  57         where ES::Target: EntropySource {
  58                 Self(entropy_source.get_secure_random_bytes())
  59         }
  60
  61         /// Generic constructor; create a new channel ID from the provided data.
  62         /// Use a more specific `*_from_*` constructor when possible.
  63         pub fn from_bytes(data: [u8; 32]) -> Self {
  64                 Self(data)
  65         }
  66
  67         /// Create a channel ID consisting of all-zeros data (e.g. when uninitialized or a placeholder).
  68         pub fn new_zero() -> Self {
  69                 Self([0; 32])
  70         }
  71
  72         /// Check whether ID is consisting of all zeros (uninitialized)
  73         pub fn is_zero(&self) -> bool {
  74                 self.0[..] == [0; 32]
  75         }
  76
  77         /// Create _v2_ channel ID by concatenating the holder revocation basepoint with the counterparty
  78         /// revocation basepoint and hashing the result. The basepoints will be concatenated in increasing
  79         /// sorted order.
  80         pub fn v2_from_revocation_basepoints(
  81                 ours: &RevocationBasepoint,
  82                 theirs: &RevocationBasepoint,
  83         ) -> Self {
  84                 let ours = ours.0.serialize();
  85                 let theirs = theirs.0.serialize();
  86                 let (lesser, greater) = if ours < theirs {
  87                         (ours, theirs)
  88                 } else {
  89                         (theirs, ours)
  90                 };
  91                 let mut engine = Sha256::engine();
  92                 engine.input(&lesser[..]);
  93                 engine.input(&greater[..]);
  94                 Self(Sha256::from_engine(engine).to_byte_array())
  95         }
  96
  97         /// Create temporary _v2_ channel ID by concatenating a zeroed out basepoint with the holder
  98         /// revocation basepoint and hashing the result.
  99         pub fn temporary_v2_from_revocation_basepoint(our_revocation_basepoint: &RevocationBasepoint) -> Self {
 100                 Self(Sha256::hash(&[[0u8; 33], our_revocation_basepoint.0.serialize()].concat()).to_byte_array())
 101         }
 102 }
 103
 104 impl Writeable for ChannelId {
 105         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 106                 self.0.write(w)
 107         }
 108 }
 109
 110 impl Readable for ChannelId {
 111         fn read<R: io::Read>(r: &mut R) -> Result<Self, DecodeError> {
 112                 let buf: [u8; 32] = Readable::read(r)?;
 113                 Ok(ChannelId(buf))
 114         }
 115 }
 116
 117 impl fmt::Display for ChannelId {
 118         fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 119                 crate::util::logger::DebugBytes(&self.0).fmt(f)
 120         }
 121 }
 122
 123 #[cfg(test)]
 124 mod tests {
 125         use bitcoin::hashes::{
 126                 Hash as _,
 127                 HashEngine as _,
 128                 hex::FromHex as _,
 129                 sha256::Hash as Sha256,
 130         };
 131         use bitcoin::secp256k1::PublicKey;
 132         use hex::DisplayHex;
 133
 134         use crate::ln::ChannelId;
 135         use crate::ln::channel_keys::RevocationBasepoint;
 136         use crate::util::ser::{Readable, Writeable};
 137         use crate::util::test_utils;
 138         use crate::prelude::*;
 139         use crate::io;
 140
 141         #[test]
 142         fn test_channel_id_v1_from_funding_txid() {
 143                 let channel_id = ChannelId::v1_from_funding_txid(&[2; 32], 1);
 144                 assert_eq!(channel_id.0.as_hex().to_string(), "0202020202020202020202020202020202020202020202020202020202020203");
 145         }
 146
 147         #[test]
 148         fn test_channel_id_new_from_data() {
 149                 let data: [u8; 32] = [2; 32];
 150                 let channel_id = ChannelId::from_bytes(data.clone());
 151                 assert_eq!(channel_id.0, data);
 152         }
 153
 154         #[test]
 155         fn test_channel_id_equals() {
 156                 let channel_id11 = ChannelId::v1_from_funding_txid(&[2; 32], 2);
 157                 let channel_id12 = ChannelId::v1_from_funding_txid(&[2; 32], 2);
 158                 let channel_id21 = ChannelId::v1_from_funding_txid(&[2; 32], 42);
 159                 assert_eq!(channel_id11, channel_id12);
 160                 assert_ne!(channel_id11, channel_id21);
 161         }
 162
 163         #[test]
 164         fn test_channel_id_write_read() {
 165                 let data: [u8; 32] = [2; 32];
 166                 let channel_id = ChannelId::from_bytes(data.clone());
 167
 168                 let mut w = test_utils::TestVecWriter(Vec::new());
 169                 channel_id.write(&mut w).unwrap();
 170
 171                 let channel_id_2 = ChannelId::read(&mut io::Cursor::new(&w.0)).unwrap();
 172                 assert_eq!(channel_id_2, channel_id);
 173                 assert_eq!(channel_id_2.0, data);
 174         }
 175
 176         #[test]
 177         fn test_channel_id_display() {
 178                 let channel_id = ChannelId::v1_from_funding_txid(&[2; 32], 1);
 179                 assert_eq!(format!("{}", &channel_id), "0202020202020202020202020202020202020202020202020202020202020203");
 180         }
 181
 182         #[test]
 183         fn test_channel_id_v2_from_basepoints() {
 184                 // Ours greater than theirs
 185                 let ours = RevocationBasepoint(PublicKey::from_slice(&<Vec<u8>>::from_hex("0324653eac434488002cc06bbfb7f10fe18991e35f9fe4302dbea6d2353dc0ab1c").unwrap()[..]).unwrap());
 186                 let theirs = RevocationBasepoint(PublicKey::from_slice(&<Vec<u8>>::from_hex("02eec7245d6b7d2ccb30380bfbe2a3648cd7a942653f5aa340edcea1f283686619").unwrap()[..]).unwrap());
 187
 188                 let mut engine = Sha256::engine();
 189                 engine.input(&theirs.0.serialize());
 190                 engine.input(&ours.0.serialize());
 191                 let expected_id = ChannelId(Sha256::from_engine(engine).to_byte_array());
 192
 193                 assert_eq!(ChannelId::v2_from_revocation_basepoints(&ours, &theirs), expected_id);
 194
 195                 // Theirs greater than ours
 196                 let ours = RevocationBasepoint(PublicKey::from_slice(&<Vec<u8>>::from_hex("027f31ebc5462c1fdce1b737ecff52d37d75dea43ce11c74d25aa297165faa2007").unwrap()[..]).unwrap());
 197                 let theirs = RevocationBasepoint(PublicKey::from_slice(&<Vec<u8>>::from_hex("02eec7245d6b7d2ccb30380bfbe2a3648cd7a942653f5aa340edcea1f283686619").unwrap()[..]).unwrap());
 198
 199                 let mut engine = Sha256::engine();
 200                 engine.input(&ours.0.serialize());
 201                 engine.input(&theirs.0.serialize());
 202                 let expected_id = ChannelId(Sha256::from_engine(engine).to_byte_array());
 203
 204                 assert_eq!(ChannelId::v2_from_revocation_basepoints(&ours, &theirs), expected_id);
 205         }
 206 }