Add detection of feature_static_remotekey support and print

This adds the ability to check for static_remotekey in appropriate
feature contexts and prints it at connect time. It is still
considered unknown for the purposes of requires_unknown_bits() as
we don't yet implement it.

Author: TheBlueMatt

lightning/src/ln/features.rs

@@ -97,7 +97,7 @@ mod sealed {
 			// Byte 0
 			DataLossProtect | InitialRoutingSync | UpfrontShutdownScript,
 			// Byte 1
-			VariableLengthOnion | PaymentSecret,
+			VariableLengthOnion | StaticRemoteKey | PaymentSecret,
 			// Byte 2
 			BasicMPP,
 		],
@@ -115,7 +115,7 @@ mod sealed {
 			// Byte 0
 			DataLossProtect | UpfrontShutdownScript,
 			// Byte 1
-			VariableLengthOnion | PaymentSecret,
+			VariableLengthOnion | StaticRemoteKey | PaymentSecret,
 			// Byte 2
 			BasicMPP,
 		],
@@ -215,6 +215,8 @@ mod sealed {
 		"Feature flags for `option_upfront_shutdown_script`.");
 	define_feature!(9, VariableLengthOnion, [InitContext, NodeContext],
 		"Feature flags for `var_onion_optin`.");
+	define_feature!(13, StaticRemoteKey, [InitContext, NodeContext],
+		"Feature flags for `option_static_remotekey`.");
 	define_feature!(15, PaymentSecret, [InitContext, NodeContext],
 		"Feature flags for `payment_secret`.");
 	define_feature!(17, BasicMPP, [InitContext, NodeContext],
@@ -418,6 +420,12 @@ impl<T: sealed::VariableLengthOnion> Features<T> {
 	}
 }
 
+impl<T: sealed::StaticRemoteKey> Features<T> {
+	pub(crate) fn supports_static_remote_key(&self) -> bool {
+		<T as sealed::StaticRemoteKey>::supports_feature(&self.flags)
+	}
+}
+
 impl<T: sealed::InitialRoutingSync> Features<T> {
 	pub(crate) fn initial_routing_sync(&self) -> bool {
 		<T as sealed::InitialRoutingSync>::supports_feature(&self.flags)
@@ -520,11 +528,11 @@ mod tests {
 		{
 			// Check that the flags are as expected:
 			// - option_data_loss_protect
-			// - var_onion_optin | payment_secret
+			// - var_onion_optin | static_remote_key | payment_secret
 			// - basic_mpp
 			assert_eq!(node_features.flags.len(), 3);
 			assert_eq!(node_features.flags[0], 0b00000010);
-			assert_eq!(node_features.flags[1], 0b10000010);
+			assert_eq!(node_features.flags[1], 0b10100010);
 			assert_eq!(node_features.flags[2], 0b00000010);
 		}
 

lightning/src/ln/peer_handler.rs

@@ -629,10 +629,11 @@ impl<Descriptor: SocketDescriptor, CM: Deref> PeerManager<Descriptor, CM> where
 													return Err(PeerHandleError{ no_connection_possible: false });
 												}
 
-												log_info!(self, "Received peer Init message: data_loss_protect: {}, initial_routing_sync: {}, upfront_shutdown_script: {}, unkown local flags: {}, unknown global flags: {}",
+												log_info!(self, "Received peer Init message: data_loss_protect: {}, initial_routing_sync: {}, upfront_shutdown_script: {}, static_remote_key: {}, unkown local flags: {}, unknown global flags: {}",
 													if msg.features.supports_data_loss_protect() { "supported" } else { "not supported"},
 													if msg.features.initial_routing_sync() { "requested" } else { "not requested" },
 													if msg.features.supports_upfront_shutdown_script() { "supported" } else { "not supported"},
+													if msg.features.supports_static_remote_key() { "supported" } else { "not supported"},
 													if msg.features.supports_unknown_bits() { "present" } else { "none" },
 													if msg.features.supports_unknown_bits() { "present" } else { "none" });