MGS: Start gateway-sp-comms crate with a ManagementSwitch

Cargo.toml

@@ -4,6 +4,7 @@ members = [
     "gateway",
     "gateway-client",
     "gateway-messages",
+    "gateway-sp-comms",
     "nexus",
     "nexus/src/db/db-macros",
     "nexus/test-utils",

gateway-sp-comms/Cargo.toml

@@ -0,0 +1,25 @@
+[package]
+name = "gateway-sp-comms"
+version = "0.1.0"
+edition = "2018"
+license = "MPL-2.0"
+
+[dependencies]
+futures = "0.3.21"
+ringbuffer = "0.8"
+serde = { version = "1.0", features = ["derive"] }
+thiserror = "1.0.30"
+uuid = "0.8"
+
+gateway-messages = { path = "../gateway-messages", features = ["std"] }
+
+[dependencies.slog]
+version = "2.7"
+features = [ "max_level_trace", "release_max_level_debug" ]
+
+[dependencies.tokio]
+version = "1.16"
+features = [ "full" ]
+
+[dev-dependencies]
+omicron-test-utils = { path = "../test-utils" }

gateway-sp-comms/src/error.rs

@@ -0,0 +1,15 @@
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this
+// file, You can obtain one at https://mozilla.org/MPL/2.0/.
+
+// Copyright 2022 Oxide Computer Company
+
+use std::io;
+use std::net::SocketAddr;
+use thiserror::Error;
+
+#[derive(Debug, Error)]
+pub enum StartupError {
+    #[error("error binding to UDP address {addr}: {err}")]
+    UdpBind { addr: SocketAddr, err: io::Error },
+}

gateway-sp-comms/src/lib.rs

@@ -0,0 +1,24 @@
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this
+// file, You can obtain one at https://mozilla.org/MPL/2.0/.
+
+// Copyright 2022 Oxide Computer Company
+
+pub mod error;
+mod management_switch;
+
+pub use management_switch::SpIdentifier;
+pub use management_switch::SpType;
+
+// TODO the following should probably not be pub once this crate is more
+// complete; for now make them pub so `gateway` can use them directly
+pub use management_switch::ManagementSwitch;
+pub use management_switch::ManagementSwitchDiscovery;
+pub use management_switch::SpSocket;
+pub use management_switch::SwitchPort;
+
+// TODO these will remain public for a while, but eventually will be removed
+// altogther; currently these provide a way to hard-code the rack topology,
+// which is not what we want.
+pub use management_switch::KnownSp;
+pub use management_switch::KnownSps;