Document better optional features.

Author: mattfaltyn

lightning/src/ln/features.rs

@@ -18,6 +18,81 @@
 //! the term "supports" is used in reference to a particular set of [`Features`]. That is, a node
 //! 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 supported in the LDK:
+//! - `DataLossProtect` - requires/supports that a node, which has somehow fallen behind (e.g. has been restored from 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).
+//! 	- `set_data_loss_protect_optional` - sets this feature to optional.
+//! 	- `set_data_loss_protect_required` - sets this feature to required.
+//! 	- `supports_data_loss_protect` - checks if this feature is supported.
+//! 	- `requires_data_loss_protect` - checks if this feature is required.
+//! - `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).
+//! 	- `set_initial_routing_sync_optional` - sets this feature to optional.
+//! 	- `set_initial_routing_sync_required` - sets this feature to required.
+//! 	- `initial_routing_sync` - checks if this feature is supported.
+//! - `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).
+//! 	- `set_upfront_shutdown_script_optional` - sets this feature to optional.
+//! 	- `set_upfront_shutdown_script_required` - sets this feature to required.
+//! 	- `supports_upfront_shutdown_script` - checks if this feature is supported.
+//! 	- `requires_upfront_shutdown_script` - checks if this feature is required.
+//! - `GossipQueries` - requires/supports more sophisticated gossip control
+//! 	(see [BOLT-7](https://github.com/lightning/bolts/blob/master/07-routing-gossip.md)
+//! 	for more information).
+//! 	- `set_gossip_queries_optional` - sets this feature to optional.
+//! 	- `set_gossip_queries_required` - sets this feature to required.
+//! 	- `supports_gossip_queries` - checks if this feature is supported.
+//! 	- `requires_gossip_queries` - checks if this feature is required.
+//! - `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).
+//! 	- `set_variable_length_onion_optional` - sets this feature to optional.
+//! 	- `set_variable_length_onion_required` - sets this feature to required.
+//! 	- `supports_variable_length_onion`- checks if this feature is supported.
+//! 	- `requires_variable_length_onion` - checks if this feature is required.
+//! - `StaticRemoteKey` - requires/supports static key for remote output
+//! 	(see [BOLT-3](https://github.com/lightning/bolts/blob/master/03-transactions.md) for more information).
+//! 	- `set_static_remote_key_optional` - sets this feature to optional.
+//! 	- `set_static_remote_key_required` - sets this feature to required.
+//! 	- `supports_static_remote_key` - checks if this feature is supported.
+//! 	- `requires_static_remote_key` - checks if this feature is required.
+//! - `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).
+//! 	- `set_payment_secret_optional` - sets this feature to optional.
+//! 	- `set_payment_secret_required` - sets this feature to required.
+//! 	- `supports_payment_secret` - checks if the feature is supported.
+//! 	- `requires_payment_secret` - checks if the feature is required.
+//! - `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).
+//! 	- `set_basic_mpp_optional` - sets this feature to optional.
+//! 	- `set_basic_mpp_required` - sets this feature to required.
+//! 	- `supports_basic_mpp` - checks if the feature is supported.
+//! 	- `requires_basic_mpp` - checks if the feature is required.
+//! - `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#closing-initiation-shutdown) for more information).
+//! 	- `set_shutdown_any_segwit_optional` - sets this feature to optional.
+//! 	- `set_shutdown_any_segwit_required` - sets this feature to required.
+//! 	- `supports_shutdown_anysegwit` - checks if the feature is supported.
+//! 	- `requires_shutdown_anysegwit` - checks if the feature is required.
+//! - `ChannelType` - node supports the channel_type field in open/accept
+//! 	(see [BOLT-2](https://github.com/lightning/bolts/blob/master/02-peer-protocol.md#closing-initiation-shutdown) for more information).
+//! 	- `set_channel_type_optional` - sets this feature to optional.
+//! 	- `set_channel_type_required` - sets this feature to required.
+//! 	- `supports_channel_type` - checks if the feature is supported.
+//! 	- `requires_channel_type` - checks if the feature is required.
+//! - `SCIDPrivacy` - supply channel aliases for routing
+//! 	(see [BOLT-2](https://github.com/lightning/bolts/blob/master/02-peer-protocol.md#closing-initiation-shutdown) for more information).
+//! 	- `set_scid_privacy_optional` - sets this feature to optional.
+//! 	- `set_scid_privacy_required` - sets this feature to required.
+//! 	- `supports_scid_privacy` - checks if the feature is supported.
+//! 	- `requires_scid_privacy` - checks if the feature is required.
+//! - `Keysend` - send funds to a node without an invoice
+//! 	(see [BOLT-11](https://github.com/lightning/bolts/blob/master/11-payment-encoding.md) for more information).
+//! 	- `set_keysend_optional` - sets this feature to optional.
+//! 	- `set_keysend_required` - sets this feature to required.
+//! 	- `supports_keysend` - checks if the feature is supported.
+//! 	- `requires_keysend` - checks if the feature is required.
 //!
 //! [BOLT #9]: https://github.com/lightning/bolts/blob/master/09-features.md
 //! [messages]: crate::ln::msgs