Merge pull request #1709 from tnull/2022-09-make-access-error-debug
[rust-lightning] / lightning / src / ln / features.rs
index 775e070ed76798d4082a77e097fb0d770568b3b0..91922f1a45f26748f9fdaf8c7ba009a068f6d6b9 100644 (file)
 //! supports a feature if it advertises the feature (as either required or optional) to its peers.
 //! And the implementation can interpret a feature if the feature is known to it.
 //!
+//! The following features are currently required in the LDK:
+//! - `VariableLengthOnion` - requires/supports variable-length routing onion payloads
+//!     (see [BOLT-4](https://github.com/lightning/bolts/blob/master/04-onion-routing.md) for more information).
+//! - `StaticRemoteKey` - requires/supports static key for remote output
+//!     (see [BOLT-3](https://github.com/lightning/bolts/blob/master/03-transactions.md) for more information).
+//!
+//! The following features are currently supported in the LDK:
+//! - `DataLossProtect` - requires/supports that a node which has somehow fallen behind, e.g., has been restored from an old backup,
+//!     can detect that it has fallen behind
+//!     (see [BOLT-2](https://github.com/lightning/bolts/blob/master/02-peer-protocol.md) for more information).
+//! - `InitialRoutingSync` - requires/supports that the sending node needs a complete routing information dump
+//!     (see [BOLT-7](https://github.com/lightning/bolts/blob/master/07-routing-gossip.md#initial-sync) for more information).
+//! - `UpfrontShutdownScript` - commits to a shutdown scriptpubkey when opening a channel
+//!     (see [BOLT-2](https://github.com/lightning/bolts/blob/master/02-peer-protocol.md#the-open_channel-message) for more information).
+//! - `GossipQueries` - requires/supports more sophisticated gossip control
+//!     (see [BOLT-7](https://github.com/lightning/bolts/blob/master/07-routing-gossip.md) for more information).
+//! - `PaymentSecret` - requires/supports that a node supports payment_secret field
+//!     (see [BOLT-4](https://github.com/lightning/bolts/blob/master/04-onion-routing.md) for more information).
+//! - `BasicMPP` - requires/supports that a node can receive basic multi-part payments
+//!     (see [BOLT-4](https://github.com/lightning/bolts/blob/master/04-onion-routing.md#basic-multi-part-payments) 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).
+//! - `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).
+//! - `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).
+//!
 //! [BOLT #9]: https://github.com/lightning/bolts/blob/master/09-features.md
 //! [messages]: crate::ln::msgs
 
@@ -134,6 +163,8 @@ mod sealed {
                        ,
                ],
                optional_features: [
+                       // Note that if new "non-channel-related" flags are added here they should be
+                       // explicitly cleared in InitFeatures::known_channel_features.
                        // Byte 0
                        DataLossProtect | InitialRoutingSync | UpfrontShutdownScript | GossipQueries,
                        // Byte 1
@@ -404,6 +435,11 @@ mod sealed {
        define_feature!(27, ShutdownAnySegwit, [InitContext, NodeContext],
                "Feature flags for `opt_shutdown_anysegwit`.", set_shutdown_any_segwit_optional,
                set_shutdown_any_segwit_required, supports_shutdown_anysegwit, requires_shutdown_anysegwit);
+       // We do not yet advertise the onion messages feature bit, but we need to detect when peers
+       // support it.
+       define_feature!(39, OnionMessages, [InitContext, NodeContext],
+               "Feature flags for `option_onion_messages`.", set_onion_messages_optional,
+               set_onion_messages_required, supports_onion_messages, requires_onion_messages);
        define_feature!(45, ChannelType, [InitContext, NodeContext],
                "Feature flags for `option_channel_type`.", set_channel_type_optional,
                set_channel_type_required, supports_channel_type, requires_channel_type);
@@ -511,6 +547,14 @@ impl InitFeatures {
        pub(crate) fn to_context<C: sealed::Context>(&self) -> Features<C> {
                self.to_context_internal()
        }
+
+       /// Returns the set of known init features that are related to channels. At least some of
+       /// these features are likely required for peers to talk to us.
+       pub fn known_channel_features() -> InitFeatures {
+               Self::known()
+                       .clear_initial_routing_sync()
+                       .clear_gossip_queries()
+       }
 }
 
 impl InvoiceFeatures {
@@ -729,7 +773,6 @@ impl<T: sealed::UpfrontShutdownScript> Features<T> {
 
 
 impl<T: sealed::GossipQueries> Features<T> {
-       #[cfg(test)]
        pub(crate) fn clear_gossip_queries(mut self) -> Self {
                <T as sealed::GossipQueries>::clear_bits(&mut self.flags);
                self
@@ -737,12 +780,10 @@ impl<T: sealed::GossipQueries> Features<T> {
 }
 
 impl<T: sealed::InitialRoutingSync> Features<T> {
-       // We are no longer setting initial_routing_sync now that gossip_queries
-       // is enabled. This feature is ignored by a peer when gossip_queries has 
-       // been negotiated.
-       #[cfg(test)]
-       pub(crate) fn clear_initial_routing_sync(&mut self) {
-               <T as sealed::InitialRoutingSync>::clear_bits(&mut self.flags)
+       // Note that initial_routing_sync is ignored if gossip_queries is set.
+       pub(crate) fn clear_initial_routing_sync(mut self) -> Self {
+               <T as sealed::InitialRoutingSync>::clear_bits(&mut self.flags);
+               self
        }
 }
 
@@ -881,7 +922,7 @@ mod tests {
 
                let mut init_features = InitFeatures::known();
                assert!(init_features.initial_routing_sync());
-               init_features.clear_initial_routing_sync();
+               init_features = init_features.clear_initial_routing_sync();
                assert!(!init_features.initial_routing_sync());
        }