Ability to send messages from Rialto to Millau (#525)

* relay Rialto messages to Millau

* impl SubmitRialtoToMillauMessage

* fmt

bridges/relays/substrate/src/cli.rs

@@ -108,6 +108,40 @@ pub enum Command {
 		#[structopt(long)]
 		fee: bp_millau::Balance,
 	},
+	/// Serve given lane of Rialto -> Millau messages.
+	RialtoMessagesToMillau {
+		#[structopt(flatten)]
+		rialto: RialtoConnectionParams,
+		#[structopt(flatten)]
+		rialto_sign: RialtoSigningParams,
+		#[structopt(flatten)]
+		millau: MillauConnectionParams,
+		#[structopt(flatten)]
+		millau_sign: MillauSigningParams,
+		#[structopt(flatten)]
+		prometheus_params: PrometheusParams,
+		/// Hex-encoded id of lane that should be served by relay.
+		#[structopt(long)]
+		lane: HexLaneId,
+	},
+	/// Submit message to given Rialto -> Millau lane.
+	SubmitRialtoToMillauMessage {
+		#[structopt(flatten)]
+		rialto: RialtoConnectionParams,
+		#[structopt(flatten)]
+		rialto_sign: RialtoSigningParams,
+		#[structopt(flatten)]
+		millau_sign: MillauSigningParams,
+		/// Hex-encoded lane id.
+		#[structopt(long)]
+		lane: HexLaneId,
+		/// Message type.
+		#[structopt(long, possible_values = &ToMillauMessage::variants())]
+		message: ToMillauMessage,
+		/// Delivery and dispatch fee.
+		#[structopt(long)]
+		fee: bp_rialto::Balance,
+	},
 }
 
 arg_enum! {
@@ -118,6 +152,14 @@ arg_enum! {
 	}
 }
 
+arg_enum! {
+	#[derive(Debug)]
+	/// All possible messages that may be delivered to the Millau chain.
+	pub enum ToMillauMessage {
+		Remark,
+	}
+}
+
 /// Lane id.
 #[derive(Debug)]
 pub struct HexLaneId(LaneId);