Add Features::requires_unknown_bits_from
[rust-lightning] / lightning / src / ln / features.rs
index b4a5c5ae52d5282135b6e664819c2b5962ea0b2c..4b49a56eacf73d5f4fe39c033a2206affbd889db 100644 (file)
 //!     (see [BOLT-2](https://github.com/lightning/bolts/blob/master/02-peer-protocol.md) for more information).
 //! - `OnionMessages` - requires/supports forwarding onion messages
 //!     (see [BOLT-7](https://github.com/lightning/bolts/pull/759/files) for more information).
-//!     TODO: update link
+//     TODO: update link
 //! - `ChannelType` - node supports the channel_type field in open/accept
 //!     (see [BOLT-2](https://github.com/lightning/bolts/blob/master/02-peer-protocol.md) for more information).
 //! - `SCIDPrivacy` - supply channel aliases for routing
 //!     (see [BOLT-2](https://github.com/lightning/bolts/blob/master/02-peer-protocol.md) for more information).
+//! - `PaymentMetadata` - include additional data in invoices which is passed to recipients in the
+//!      onion.
+//!      (see [BOLT-11](https://github.com/lightning/bolts/blob/master/11-payment-encoding.md) for
+//!      more).
+//! - `ZeroConf` - supports accepting HTLCs and using channels prior to funding confirmation
+//!      (see
+//!      [BOLT-2](https://github.com/lightning/bolts/blob/master/02-peer-protocol.md#the-channel_ready-message)
+//!      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).
+//!     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).
 //!
 //! [BOLT #9]: https://github.com/lightning/bolts/blob/master/09-features.md
 //! [messages]: crate::ln::msgs
@@ -160,6 +168,14 @@ mod sealed {
                VariableLengthOnion | PaymentSecret,
                // Byte 2
                BasicMPP,
+               // Byte 3
+               ,
+               // Byte 4
+               ,
+               // Byte 5
+               ,
+               // Byte 6
+               PaymentMetadata,
        ]);
        define_context!(OfferContext, []);
        define_context!(InvoiceRequestContext, []);
@@ -259,6 +275,7 @@ mod sealed {
                                        }
 
                                        flags[Self::BYTE_OFFSET] |= Self::REQUIRED_MASK;
+                                       flags[Self::BYTE_OFFSET] &= !Self::OPTIONAL_MASK;
                                }
 
                                /// Sets the feature's optional (odd) bit in the given flags.
@@ -376,12 +393,16 @@ mod sealed {
        define_feature!(47, SCIDPrivacy, [InitContext, NodeContext, ChannelTypeContext],
                "Feature flags for only forwarding with SCID aliasing. Called `option_scid_alias` in the BOLTs",
                set_scid_privacy_optional, set_scid_privacy_required, supports_scid_privacy, requires_scid_privacy);
+       define_feature!(49, PaymentMetadata, [InvoiceContext],
+               "Feature flags for payment metadata in invoices.", set_payment_metadata_optional,
+               set_payment_metadata_required, supports_payment_metadata, requires_payment_metadata);
        define_feature!(51, ZeroConf, [InitContext, NodeContext, ChannelTypeContext],
                "Feature flags for accepting channels with zero confirmations. Called `option_zeroconf` in the BOLTs",
                set_zero_conf_optional, set_zero_conf_required, supports_zero_conf, requires_zero_conf);
        define_feature!(55, Keysend, [NodeContext],
                "Feature flags for keysend payments.", set_keysend_optional, set_keysend_required,
                supports_keysend, requires_keysend);
+       // Note: update the module-level docs when a new feature bit is added!
 
        #[cfg(test)]
        define_feature!(123456789, UnknownFeature,
@@ -401,8 +422,10 @@ pub struct Features<T: sealed::Context> {
        mark: PhantomData<T>,
 }
 
-impl <T: sealed::Context> Features<T> {
-       pub(crate) fn or(mut self, o: Self) -> Self {
+impl<T: sealed::Context> core::ops::BitOr for Features<T> {
+       type Output = Self;
+
+       fn bitor(mut self, o: Self) -> Self {
                let total_feature_len = cmp::max(self.flags.len(), o.flags.len());
                self.flags.resize(total_feature_len, 0u8);
                for (byte, o_byte) in self.flags.iter_mut().zip(o.flags.iter()) {
@@ -656,6 +679,25 @@ impl<T: sealed::Context> Features<T> {
                self.flags.iter().any(|&byte| (byte & 0b10_10_10_10) != 0)
        }
 
+       /// Returns true if this `Features` object contains required features unknown by `other`.
+       pub fn requires_unknown_bits_from(&self, other: &Features<T>) -> bool {
+               // Bitwise AND-ing with all even bits set except for known features will select required
+               // unknown features.
+               self.flags.iter().enumerate().any(|(i, &byte)| {
+                       const REQUIRED_FEATURES: u8 = 0b01_01_01_01;
+                       const OPTIONAL_FEATURES: u8 = 0b10_10_10_10;
+                       let unknown_features = if i < other.flags.len() {
+                               // Form a mask similar to !T::KNOWN_FEATURE_MASK only for `other`
+                               !(other.flags[i]
+                                       | ((other.flags[i] >> 1) & REQUIRED_FEATURES)
+                                       | ((other.flags[i] << 1) & OPTIONAL_FEATURES))
+                       } else {
+                               0b11_11_11_11
+                       };
+                       (byte & (REQUIRED_FEATURES & unknown_features)) != 0
+               })
+       }
+
        /// Returns true if this `Features` object contains unknown feature flags which are set as
        /// "required".
        pub fn requires_unknown_bits(&self) -> bool {
@@ -829,13 +871,50 @@ mod tests {
                assert!(features.supports_unknown_bits());
        }
 
+       #[test]
+       fn requires_unknown_bits_from() {
+               let mut features1 = InitFeatures::empty();
+               let mut features2 = InitFeatures::empty();
+               assert!(!features1.requires_unknown_bits_from(&features2));
+               assert!(!features2.requires_unknown_bits_from(&features1));
+
+               features1.set_data_loss_protect_required();
+               assert!(features1.requires_unknown_bits_from(&features2));
+               assert!(!features2.requires_unknown_bits_from(&features1));
+
+               features2.set_data_loss_protect_optional();
+               assert!(!features1.requires_unknown_bits_from(&features2));
+               assert!(!features2.requires_unknown_bits_from(&features1));
+
+               features2.set_gossip_queries_required();
+               assert!(!features1.requires_unknown_bits_from(&features2));
+               assert!(features2.requires_unknown_bits_from(&features1));
+
+               features1.set_gossip_queries_optional();
+               assert!(!features1.requires_unknown_bits_from(&features2));
+               assert!(!features2.requires_unknown_bits_from(&features1));
+
+               features1.set_variable_length_onion_required();
+               assert!(features1.requires_unknown_bits_from(&features2));
+               assert!(!features2.requires_unknown_bits_from(&features1));
+
+               features2.set_variable_length_onion_optional();
+               assert!(!features1.requires_unknown_bits_from(&features2));
+               assert!(!features2.requires_unknown_bits_from(&features1));
+
+               features1.set_basic_mpp_required();
+               features2.set_wumbo_required();
+               assert!(features1.requires_unknown_bits_from(&features2));
+               assert!(features2.requires_unknown_bits_from(&features1));
+       }
+
        #[test]
        fn convert_to_context_with_relevant_flags() {
                let mut init_features = InitFeatures::empty();
                // Set a bunch of features we use, plus initial_routing_sync_required (which shouldn't get
                // converted as it's only relevant in an init context).
                init_features.set_initial_routing_sync_required();
-               init_features.set_data_loss_protect_optional();
+               init_features.set_data_loss_protect_required();
                init_features.set_variable_length_onion_required();
                init_features.set_static_remote_key_required();
                init_features.set_payment_secret_required();
@@ -855,7 +934,7 @@ mod tests {
                let node_features: NodeFeatures = init_features.to_context();
                {
                        // Check that the flags are as expected:
-                       // - option_data_loss_protect
+                       // - option_data_loss_protect (req)
                        // - var_onion_optin (req) | static_remote_key (req) | payment_secret(req)
                        // - basic_mpp | wumbo
                        // - opt_shutdown_anysegwit
@@ -863,7 +942,7 @@ mod tests {
                        // - option_channel_type | option_scid_alias
                        // - option_zeroconf
                        assert_eq!(node_features.flags.len(), 7);
-                       assert_eq!(node_features.flags[0], 0b00000010);
+                       assert_eq!(node_features.flags[0], 0b00000001);
                        assert_eq!(node_features.flags[1], 0b01010001);
                        assert_eq!(node_features.flags[2], 0b10001010);
                        assert_eq!(node_features.flags[3], 0b00001000);
@@ -885,13 +964,13 @@ mod tests {
        #[test]
        fn convert_to_context_with_unknown_flags() {
                // Ensure the `from` context has fewer known feature bytes than the `to` context.
-               assert!(<sealed::InvoiceContext as sealed::Context>::KNOWN_FEATURE_MASK.len() <
-                       <sealed::NodeContext as sealed::Context>::KNOWN_FEATURE_MASK.len());
-               let mut invoice_features = InvoiceFeatures::empty();
-               invoice_features.set_unknown_feature_optional();
-               assert!(invoice_features.supports_unknown_bits());
-               let node_features: NodeFeatures = invoice_features.to_context();
-               assert!(!node_features.supports_unknown_bits());
+               assert!(<sealed::ChannelContext as sealed::Context>::KNOWN_FEATURE_MASK.len() <
+                       <sealed::InvoiceContext as sealed::Context>::KNOWN_FEATURE_MASK.len());
+               let mut channel_features = ChannelFeatures::empty();
+               channel_features.set_unknown_feature_optional();
+               assert!(channel_features.supports_unknown_bits());
+               let invoice_features: InvoiceFeatures = channel_features.to_context_internal();
+               assert!(!invoice_features.supports_unknown_bits());
        }
 
        #[test]