lightning: Add provide_peer_backup_storage to InitContext and NodeContext.

Author: Aditya Sharma

lightning-types/src/features.rs

@@ -68,6 +68,8 @@
 //!     (see the [`Keysend` feature assignment proposal](https://github.com/lightning/bolts/issues/605#issuecomment-606679798) for more information).
 //! - `Trampoline` - supports receiving and forwarding Trampoline payments
 //!     (see the [`Trampoline` feature proposal](https://github.com/lightning/bolts/pull/836) for more information).
+//! - `provide_peer_backup_storage` - Indicates that we offer the capability to store data of our peers
+//! 	(see https://github.com/lightning/bolts/pull/1110 for more info).
 //!
 //! LDK knows about the following features, but does not support them:
 //! - `AnchorsNonzeroFeeHtlcTx` - the initial version of anchor outputs, which was later found to be
@@ -151,7 +153,7 @@ mod sealed {
 			// Byte 4
 			OnionMessages,
 			// Byte 5
-			ChannelType | SCIDPrivacy,
+			ProvidePeerBackupStorage | ChannelType | SCIDPrivacy,
 			// Byte 6
 			ZeroConf,
 			// Byte 7
@@ -172,7 +174,7 @@ mod sealed {
 			// Byte 4
 			OnionMessages,
 			// Byte 5
-			ChannelType | SCIDPrivacy,
+			ProvidePeerBackupStorage | ChannelType | SCIDPrivacy,
 			// Byte 6
 			ZeroConf | Keysend,
 			// Byte 7
@@ -519,6 +521,16 @@ mod sealed {
 		supports_onion_messages,
 		requires_onion_messages
 	);
+	define_feature!(
+		43,
+		ProvidePeerBackupStorage,
+		[InitContext, NodeContext],
+		"Feature flags for `provide_peer_backup_storage`.",
+		set_provide_peer_backup_storage_optional,
+		set_provide_peer_backup_storage_required,
+		supports_provide_peer_storage,
+		requires_provide_peer_storage
+	);
 	define_feature!(
 		45,
 		ChannelType,
@@ -1157,6 +1169,14 @@ mod tests {
 		assert!(!features1.requires_unknown_bits_from(&features2));
 		assert!(!features2.requires_unknown_bits_from(&features1));
 
+		features1.set_provide_peer_backup_storage_required();
+		assert!(features1.requires_unknown_bits_from(&features2));
+		assert!(!features2.requires_unknown_bits_from(&features1));
+
+		features2.set_provide_peer_backup_storage_optional();
+		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));

lightning/src/ln/channelmanager.rs

@@ -11076,6 +11076,7 @@ pub fn provided_init_features(config: &UserConfig) -> InitFeatures {
 	features.set_scid_privacy_optional();
 	features.set_zero_conf_optional();
 	features.set_route_blinding_optional();
+	features.set_provide_peer_backup_storage_optional();
 	if config.channel_handshake_config.negotiate_anchors_zero_fee_htlc_tx {
 		features.set_anchors_zero_fee_htlc_tx_optional();
 	}