Re-order AnchorsZeroFeeHtlcTx in module docs/tests

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

diff --git a/lightning/src/ln/features.rs b/lightning/src/ln/features.rs
index 1992b8db9e565b7696e60bc286581583ca8beed7..08df63e7033b03f92c88aeb8b133a47b6cb8ef2e 100644 (file)
--- a/lightning/src/ln/features.rs
+++ b/lightning/src/ln/features.rs
@@ -41,6 +41,10 @@
 //!     (see [BOLT-4](https://github.com/lightning/bolts/blob/master/04-onion-routing.md#basic-multi-part-payments) for more information).
 //! - `Wumbo` - requires/supports that a node create large channels. Called `option_support_large_channel` in the spec.
 //!     (see [BOLT-2](https://github.com/lightning/bolts/blob/master/02-peer-protocol.md#the-open_channel-message) for more information).
+//! - `AnchorsZeroFeeHtlcTx` - requires/supports that commitment transactions include anchor outputs
+//!     and HTLC transactions are pre-signed with zero fee (see
+//!     [BOLT-3](https://github.com/lightning/bolts/blob/master/03-transactions.md) for more
+//!     information).
 //! - `ShutdownAnySegwit` - requires/supports that future segwit versions are allowed in `shutdown`
 //!     (see [BOLT-2](https://github.com/lightning/bolts/blob/master/02-peer-protocol.md) for more information).
 //! - `OnionMessages` - requires/supports forwarding onion messages
@@ -60,10 +64,6 @@
 //!      for more info).
 //! - `Keysend` - send funds to a node without an invoice
 //!     (see the [`Keysend` feature assignment proposal](https://github.com/lightning/bolts/issues/605#issuecomment-606679798) for more information).
-//! - `AnchorsZeroFeeHtlcTx` - requires/supports that commitment transactions include anchor outputs
-//!     and HTLC transactions are pre-signed with zero fee (see
-//!     [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
@@ -718,7 +718,11 @@ impl<T: sealed::Context> Features<T> {
                Ok(())
        }
 
-       fn from_be_bytes(mut flags: Vec<u8>) -> Features<T> {
+       /// Create a [`Features`] given a set of flags, in big-endian. This is in byte order from
+       /// most on-the-wire encodings.
+       ///
+       /// This is not exported to bindings users as we don't support export across multiple T
+       pub fn from_be_bytes(mut flags: Vec<u8>) -> Features<T> {
                flags.reverse(); // Swap to little-endian
                Self {
                        flags,
@@ -798,6 +802,35 @@ impl<T: sealed::Context> Features<T> {
                true
        }
 
+       /// Sets a required feature bit. Errors if `bit` is outside the feature range as defined
+       /// by [BOLT 9].
+       ///
+       /// Note: Required bits are even. If an odd bit is given, then the corresponding even bit will
+       /// be set instead (i.e., `bit - 1`).
+       ///
+       /// [BOLT 9]: https://github.com/lightning/bolts/blob/master/09-features.md
+       pub fn set_required_feature_bit(&mut self, bit: usize) -> Result<(), ()> {
+               self.set_feature_bit(bit - (bit % 2))
+       }
+
+       /// Sets an optional feature bit. Errors if `bit` is outside the feature range as defined
+       /// by [BOLT 9].
+       ///
+       /// Note: Optional bits are odd. If an even bit is given, then the corresponding odd bit will be
+       /// set instead (i.e., `bit + 1`).
+       ///
+       /// [BOLT 9]: https://github.com/lightning/bolts/blob/master/09-features.md
+       pub fn set_optional_feature_bit(&mut self, bit: usize) -> Result<(), ()> {
+               self.set_feature_bit(bit + (1 - (bit % 2)))
+       }
+
+       fn set_feature_bit(&mut self, bit: usize) -> Result<(), ()> {
+               if bit > 255 {
+                       return Err(());
+               }
+               self.set_bit(bit, false)
+       }
+
        /// Sets a required custom feature bit. Errors if `bit` is outside the custom range as defined
        /// by [bLIP 2] or if it is a known `T` feature.
        ///
@@ -824,10 +857,13 @@ impl<T: sealed::Context> Features<T> {
                if bit < 256 {
                        return Err(());
                }
+               self.set_bit(bit, true)
+       }
 
+       fn set_bit(&mut self, bit: usize, custom: bool) -> Result<(), ()> {
                let byte_offset = bit / 8;
                let mask = 1 << (bit - 8 * byte_offset);
-               if byte_offset < T::KNOWN_FEATURE_MASK.len() {
+               if byte_offset < T::KNOWN_FEATURE_MASK.len() && custom {
                        if (T::KNOWN_FEATURE_MASK[byte_offset] & mask) != 0 {
                                return Err(());
                        }
@@ -1032,7 +1068,7 @@ mod tests {
                        // Check that the flags are as expected:
                        // - option_data_loss_protect (req)
                        // - var_onion_optin (req) | static_remote_key (req) | payment_secret(req)
-                       // - basic_mpp | wumbo | anchors_zero_fee_htlc_tx
+                       // - basic_mpp | wumbo | option_anchors_zero_fee_htlc_tx
                        // - opt_shutdown_anysegwit
                        // - onion_messages
                        // - option_channel_type | option_scid_alias
@@ -1078,6 +1114,13 @@ mod tests {
                assert!(!features.requires_basic_mpp());
                assert!(features.requires_payment_secret());
                assert!(features.supports_payment_secret());
+
+               // Set flags manually
+               let mut features = NodeFeatures::empty();
+               assert!(features.set_optional_feature_bit(55).is_ok());
+               assert!(features.supports_keysend());
+               assert!(features.set_optional_feature_bit(255).is_ok());
+               assert!(features.set_required_feature_bit(256).is_err());
        }
 
        #[test]