Document nonzero anchors in features module.

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

diff --git a/lightning/src/ln/features.rs b/lightning/src/ln/features.rs
index b8087546c7445060230a5ad776a9b3f13c113d37..400888ff9784ff0f8217de151f5b4f24d23509a7 100644 (file)
--- a/lightning/src/ln/features.rs
+++ b/lightning/src/ln/features.rs
@@ -65,6 +65,12 @@
 //!     [BOLT-3](https://github.com/lightning/bolts/blob/master/03-transactions.md) for more
 //!     information).
 //!
+//! LDK knows about the following features, but does not support them:
+//! - `AnchorsNonzeroFeeHtlcTx` - the initial version of anchor outputs, which was later found to be
+//!     vulnerable (see this
+//!     [mailing list post](https://lists.linuxfoundation.org/pipermail/lightning-dev/2020-September/002796.html)
+//!     for more information).
+//!
 //! [BOLT #9]: https://github.com/lightning/bolts/blob/master/09-features.md
 //! [messages]: crate::ln::msgs
 
@@ -134,7 +140,7 @@ mod sealed {
                // Byte 1
                VariableLengthOnion | StaticRemoteKey | PaymentSecret,
                // Byte 2
-               BasicMPP | Wumbo | AnchorsZeroFeeHtlcTx,
+               BasicMPP | Wumbo | AnchorsNonzeroFeeHtlcTx | AnchorsZeroFeeHtlcTx,
                // Byte 3
                ShutdownAnySegwit,
                // Byte 4
@@ -150,7 +156,7 @@ mod sealed {
                // Byte 1
                VariableLengthOnion | StaticRemoteKey | PaymentSecret,
                // Byte 2
-               BasicMPP | Wumbo | AnchorsZeroFeeHtlcTx,
+               BasicMPP | Wumbo | AnchorsNonzeroFeeHtlcTx | AnchorsZeroFeeHtlcTx,
                // Byte 3
                ShutdownAnySegwit,
                // Byte 4
@@ -196,7 +202,7 @@ mod sealed {
                // Byte 1
                StaticRemoteKey,
                // Byte 2
-               AnchorsZeroFeeHtlcTx,
+               AnchorsNonzeroFeeHtlcTx | AnchorsZeroFeeHtlcTx,
                // Byte 3
                ,
                // Byte 4
@@ -378,6 +384,9 @@ mod sealed {
        define_feature!(19, Wumbo, [InitContext, NodeContext],
                "Feature flags for `option_support_large_channel` (aka wumbo channels).", set_wumbo_optional, set_wumbo_required,
                supports_wumbo, requires_wumbo);
+       define_feature!(21, AnchorsNonzeroFeeHtlcTx, [InitContext, NodeContext, ChannelTypeContext],
+               "Feature flags for `option_anchors_nonzero_fee_htlc_tx`.", set_anchors_nonzero_fee_htlc_tx_optional,
+               set_anchors_nonzero_fee_htlc_tx_required, supports_anchors_nonzero_fee_htlc_tx, requires_anchors_nonzero_fee_htlc_tx);
        define_feature!(23, AnchorsZeroFeeHtlcTx, [InitContext, NodeContext, ChannelTypeContext],
                "Feature flags for `option_anchors_zero_fee_htlc_tx`.", set_anchors_zero_fee_htlc_tx_optional,
                set_anchors_zero_fee_htlc_tx_required, supports_anchors_zero_fee_htlc_tx, requires_anchors_zero_fee_htlc_tx);
@@ -535,11 +544,17 @@ impl InvoiceFeatures {
        /// [`PaymentParameters::for_keysend`], thus omitting the need for payers to manually construct an
        /// `InvoiceFeatures` for [`find_route`].
        ///
+       /// MPP keysend is not widely supported yet, so we parameterize support to allow the user to
+       /// choose whether their router should find multi-part routes.
+       ///
        /// [`PaymentParameters::for_keysend`]: crate::routing::router::PaymentParameters::for_keysend
        /// [`find_route`]: crate::routing::router::find_route
-       pub(crate) fn for_keysend() -> InvoiceFeatures {
+       pub(crate) fn for_keysend(allow_mpp: bool) -> InvoiceFeatures {
                let mut res = InvoiceFeatures::empty();
                res.set_variable_length_onion_optional();
+               if allow_mpp {
+                       res.set_basic_mpp_optional();
+               }
                res
        }
 }