fix: legacy unicast mDNS responder for Android .local

Cargo.toml

@@ -23,6 +23,7 @@ mdns-sd = "0.20"
 nix = { version = "0.29", features = ["signal", "fs"] }
 thiserror = "2"
 libc = "0.2"
+socket2 = "0.6"
 notify = "8.2.0"
 log = "0.4"
 env_logger = "0.11"

README.md

@@ -9,15 +9,24 @@ unavailable. Always starts successfully.
 
 - Static DNS-SD services from `$DATA_DIR/etc/microdns.json` (default `/data`)
 - Hostname A records for configured `host` values (e.g. `bigfred` → `bigfred.local`)
-- Legacy unicast / one-shot mDNS replies (RFC 6762 §6.7) so browsers and OS
-  resolvers can resolve `.local` names — not only DNS-SD service browsers
+- Own legacy unicast / one-shot mDNS responder (RFC 6762 §6.7) so browsers and OS
+  resolvers (Android `getaddrinfo`) can resolve `.local` names — not only DNS-SD
+  browsers. Needed because **mdns-sd 0.20.3** answers unicast but hardcodes
+  transaction ID=`0` (`dns_parser.rs`: `let id = if self.multicast { 0 } else { self.id }`
+  while `DnsOutgoing.multicast` is never set false). Remove `legacy_unicast` when
+  upstream fixes that encoding.
 - Optional dcc-bus discovery: when enabled, watches microinit for a running
   `dcc-bus` process and advertises `_z21._udp` / `_withrottle._tcp` only when
   those ports are empirically listening
 - Optional Z21 UDP LAN discovery beacon (LAN_GET_SERIAL_NUMBER reply broadcast)
 - Hot-reload via inotify on the config file
 - Static musl builds for linux/arm64 and linux/amd64
 
+## Tests
+
+Integration-style unit tests live under `tests/` (one file per module), matching
+the microinit layout. Run with `cargo test` / `make test`.
+
 ## Config
 
 Default path: `$DATA_DIR/etc/microdns.json`. Created with defaults if missing.

src/beacon.rs

@@ -108,28 +108,3 @@ fn run_beacon(port: u16, frame: &[u8], stop: Arc<AtomicBool>) -> Result<()> {
     }
     Ok(())
 }
-
-#[cfg(test)]
-mod tests {
-    use super::*;
-
-    #[test]
-    fn default_serial_frame() {
-        let frame = serial_reply(DEFAULT_VIRTUAL_SERIAL);
-        // length=8, header=0x0010, serial LE
-        assert_eq!(frame.len(), 8);
-        assert_eq!(u16::from_le_bytes([frame[0], frame[1]]), 8);
-        assert_eq!(u16::from_le_bytes([frame[2], frame[3]]), 0x0010);
-        assert_eq!(
-            u32::from_le_bytes([frame[4], frame[5], frame[6], frame[7]]),
-            258_000_000
-        );
-    }
-
-    #[test]
-    fn virtual_serial_matches_go() {
-        assert_eq!(virtual_serial(0, 0), 258_000_000);
-        assert_eq!(virtual_serial(2, 1), 258_002_001);
-        assert_eq!(virtual_serial(1, 2), 258_001_002);
-    }
-}

src/config.rs

@@ -271,69 +271,3 @@ pub fn save(path: &Path, cfg: &Config) -> Result<()> {
     fs::write(path, data).map_err(|e| Error::io_at(path, e))?;
     Ok(())
 }
-
-#[cfg(test)]
-mod tests {
-    use super::*;
-    use std::time::{SystemTime, UNIX_EPOCH};
-
-    fn tmp_path(name: &str) -> PathBuf {
-        let nanos = SystemTime::now()
-            .duration_since(UNIX_EPOCH)
-            .unwrap()
-            .as_nanos();
-        std::env::temp_dir().join(format!("microdns-cfg-{name}-{nanos}.json"))
-    }
-
-    #[test]
-    fn default_roundtrip() {
-        let cfg = Config::default();
-        let json = serde_json::to_string_pretty(&cfg).unwrap();
-        let back: Config = serde_json::from_str(&json).unwrap();
-        assert_eq!(cfg, back);
-        assert!(!back.dcc_bus.enabled);
-        assert_eq!(back.dcc_bus.z21_port, 21105);
-        assert_eq!(back.retry.mdns_ms, 3000);
-    }
-
-    #[test]
-    fn load_or_create_seeds_default() {
-        let path = tmp_path("seed");
-        let _ = fs::remove_file(&path);
-        let cfg = load_or_create(&path).unwrap();
-        assert_eq!(cfg.services.len(), 1);
-        assert_eq!(cfg.services[0].name, "bigfred");
-        assert!(path.exists());
-        let again = load_or_create(&path).unwrap();
-        assert_eq!(cfg, again);
-        let _ = fs::remove_file(&path);
-    }
-
-    #[test]
-    fn type_field_renames() {
-        let json = r#"{
-            "services": [
-                {"name":"x","type":"_http._tcp","protocol":"tcp","port":80}
-            ]
-        }"#;
-        let cfg: Config = serde_json::from_str(json).unwrap();
-        assert_eq!(cfg.services[0].type_, "_http._tcp");
-    }
-
-    #[test]
-    fn validate_rejects_bad_dns_sd_type() {
-        let mut cfg = Config::default();
-        cfg.services[0].type_ = "_http._sctp".into();
-        assert!(cfg.validate().is_err());
-        cfg.services[0].type_ = "_http._tcp".into();
-        cfg.services[0].protocol = "udp".into();
-        assert!(cfg.validate().is_err());
-    }
-
-    #[test]
-    fn validate_rejects_duplicate_names() {
-        let mut cfg = Config::default();
-        cfg.services.push(cfg.services[0].clone());
-        assert!(cfg.validate().is_err());
-    }
-}

src/config_watch.rs

@@ -141,28 +141,3 @@ fn watch_loop(
     }
     Ok(())
 }
-
-#[cfg(test)]
-mod tests {
-    use super::*;
-
-    #[test]
-    fn relevant_filters() {
-        assert!(is_relevant_path(
-            Path::new("/data/etc/microdns.json"),
-            "microdns.json"
-        ));
-        assert!(!is_relevant_path(
-            Path::new("/data/etc/.microdns.json"),
-            "microdns.json"
-        ));
-        assert!(!is_relevant_path(
-            Path::new("/data/etc/microdns.json~"),
-            "microdns.json"
-        ));
-        assert!(!is_relevant_path(
-            Path::new("/data/etc/other.json"),
-            "microdns.json"
-        ));
-    }
-}

src/datadir.rs

@@ -54,18 +54,3 @@ where
     }
     out
 }
-
-#[cfg(test)]
-mod tests {
-    use super::*;
-
-    #[test]
-    fn default_root_is_data() {
-        // Cannot safely mutate env in parallel tests; just check absolute join.
-        let p = PathBuf::from(DEFAULT_ROOT)
-            .join("etc")
-            .join("microdns.json");
-        assert!(p.is_absolute());
-        assert!(p.ends_with("etc/microdns.json"));
-    }
-}