Merge pull request #1486 from TheBlueMatt/2022-05-revoked-txn-edge-cases

[rust-lightning] / lightning / src / ln / channel.rs

diff --git a/lightning/src/ln/channel.rs b/lightning/src/ln/channel.rs
index 8c237992ab75ebd64a9c2860fca0b1210b0fbe0e..b88a38b56504eb652c68fb445c29b5e4e4addb5b 100644 (file)
--- a/lightning/src/ln/channel.rs
+++ b/lightning/src/ln/channel.rs
@@ -500,9 +500,6 @@ pub(crate) const EXPIRE_PREV_CONFIG_TICKS: usize = 5;
 // Holder designates channel data owned for the benefice of the user client.
 // Counterparty designates channel data owned by the another channel participant entity.
 pub(super) struct Channel<Signer: Sign> {
-       #[cfg(any(test, feature = "_test_utils"))]
-       pub(crate) config: LegacyChannelConfig,
-       #[cfg(not(any(test, feature = "_test_utils")))]
        config: LegacyChannelConfig,
 
        // Track the previous `ChannelConfig` so that we can continue forwarding HTLCs that were
@@ -4551,6 +4548,43 @@ impl<Signer: Sign> Channel<Signer> {
                did_channel_update
        }
 
+       fn internal_htlc_satisfies_config(
+               &self, htlc: &msgs::UpdateAddHTLC, amt_to_forward: u64, outgoing_cltv_value: u32, config: &ChannelConfig,
+       ) -> Result<(), (&'static str, u16)> {
+               let fee = amt_to_forward.checked_mul(config.forwarding_fee_proportional_millionths as u64)
+                       .and_then(|prop_fee| (prop_fee / 1000000).checked_add(config.forwarding_fee_base_msat as u64));
+               if fee.is_none() || htlc.amount_msat < fee.unwrap() ||
+                       (htlc.amount_msat - fee.unwrap()) < amt_to_forward {
+                       return Err((
+                               "Prior hop has deviated from specified fees parameters or origin node has obsolete ones",
+                               0x1000 | 12, // fee_insufficient
+                       ));
+               }
+               if (htlc.cltv_expiry as u64) < outgoing_cltv_value as u64 + config.cltv_expiry_delta as u64 {
+                       return Err((
+                               "Forwarding node has tampered with the intended HTLC values or origin node has an obsolete cltv_expiry_delta",
+                               0x1000 | 13, // incorrect_cltv_expiry
+                       ));
+               }
+               Ok(())
+       }
+
+       /// Determines whether the parameters of an incoming HTLC to be forwarded satisfy the channel's
+       /// [`ChannelConfig`]. This first looks at the channel's current [`ChannelConfig`], and if
+       /// unsuccessful, falls back to the previous one if one exists.
+       pub fn htlc_satisfies_config(
+               &self, htlc: &msgs::UpdateAddHTLC, amt_to_forward: u64, outgoing_cltv_value: u32,
+       ) -> Result<(), (&'static str, u16)> {
+               self.internal_htlc_satisfies_config(&htlc, amt_to_forward, outgoing_cltv_value, &self.config())
+                       .or_else(|err| {
+                               if let Some(prev_config) = self.prev_config() {
+                                       self.internal_htlc_satisfies_config(htlc, amt_to_forward, outgoing_cltv_value, &prev_config)
+                               } else {
+                                       Err(err)
+                               }
+                       })
+       }
+
        pub fn get_feerate(&self) -> u32 {
                self.feerate_per_kw
        }