feat(mmserver): mDNS service discovery

Author: colinmarc

mm-server/Cargo.lock

@@ -38,6 +38,7 @@ lazy_static = "1.4"
 libc = "0.2"
 libloading = "0.8"
 listenfd = "1"
+mdns-sd = "0.11"
 mio = { version = "1", features = ["net", "os-ext", "os-poll"] }
 mio-timerfd = "0.2"
 mktemp = "0.5"

mm-server/Cargo.toml

@@ -84,6 +84,8 @@ mod parsed {
         pub(super) tls_key: Option<PathBuf>,
         pub(super) worker_threads: Option<NonZeroU32>,
         pub(super) max_connections: Option<MaxConnections>,
+        pub(super) mdns: Option<bool>,
+        pub(super) mdns_hostname: Option<String>,
     }
 
     #[derive(Debug, Clone, PartialEq, Deserialize, Converge)]
@@ -126,6 +128,8 @@ pub struct ServerConfig {
     pub tls_key: Option<PathBuf>,
     pub worker_threads: NonZeroU32,
     pub max_connections: Option<NonZeroU32>,
+    pub mdns: bool,
+    pub mdns_hostname: Option<String>,
 }
 
 #[derive(Debug, Clone, PartialEq)]
@@ -216,6 +220,8 @@ impl Config {
                     parsed::MaxConnections::Value(n) => Some(n),
                     parsed::MaxConnections::Infinity => None,
                 },
+                mdns: server.mdns.unwrap(),
+                mdns_hostname: server.mdns_hostname,
             },
             data_home: data_home.clone(),
             apps: BTreeMap::new(), // Handled below.

mm-server/src/config.rs

@@ -3,6 +3,7 @@
 // SPDX-License-Identifier: BUSL-1.1
 
 mod handlers;
+mod mdns;
 mod sendmmsg;
 
 use std::collections::{BTreeMap, VecDeque};
@@ -50,6 +51,8 @@ pub struct Server {
     state: SharedState,
     close_recv: Receiver<()>,
     close_send: WakingSender<()>,
+
+    _mdns: Option<mdns::MdnsService>,
     shutting_down: bool,
 }
 
@@ -138,6 +141,19 @@ impl Server {
 
         let thread_pool = threadpool::ThreadPool::new(server_config.worker_threads.get() as usize);
 
+        let addr = socket.local_addr()?;
+        let mdns = if server_config.mdns {
+            match mdns::MdnsService::new(addr, server_config.mdns_hostname.as_deref()) {
+                Ok(sd) => Some(sd),
+                Err(e) => {
+                    error!("failed to enable mDNS service discovery: {e:#}");
+                    None
+                }
+            }
+        } else {
+            None
+        };
+
         Ok(Self {
             server_config,
             quiche_config: config,
@@ -155,6 +171,8 @@ impl Server {
             state,
             close_send,
             close_recv,
+
+            _mdns: mdns,
             shutting_down: false,
         })
     }