Add an option to specify IPs that zeroconf will bind to (#1071)

* added an option to specify ip addresses to which mDNS should bind (ignored by `DNS-SD`)
* changed command line option to `zeroconf-interface` to be consistent with `zeroconf-port`
use builder pattern to DRY up the code
used macro to print warning message
* fixing register error
* renamed `bind_ip` variables to match the option to `zeroconf_ip`, to be more consistent
* Changed user help
Modified comments
Added block for condition to clean the code
Added new modification to the change log

Co-authored-by: setime <timeframe1@gmx.de>

CHANGELOG.md

@@ -68,6 +68,7 @@ https://github.com/librespot-org/librespot
 
 - [all] Check that array indexes are within bounds (panic safety)
 - [all] Wrap errors in librespot `Error` type (breaking)
+- [connect] Add option on which zeroconf will bind. Defaults to all interfaces. Ignored by DNS-SD.
 - [connect] Add session events
 - [connect] Add `repeat`, `set_position_ms` and `set_volume` to `spirc.rs`
 - [contrib] Add `event_handler_example.py`

discovery/src/lib.rs

@@ -47,6 +47,7 @@ pub struct Discovery {
 pub struct Builder {
     server_config: server::Config,
     port: u16,
+    zeroconf_ip: Vec<std::net::IpAddr>,
 }
 
 /// Errors that can occur while setting up a [`Discovery`] instance.
@@ -87,6 +88,7 @@ impl Builder {
                 client_id: client_id.into(),
             },
             port: 0,
+            zeroconf_ip: vec![],
         }
     }
 
@@ -102,6 +104,12 @@ impl Builder {
         self
     }
 
+    /// Set the ip addresses on which it should listen to incoming connections. The default is all interfaces.
+    pub fn zeroconf_ip(mut self, zeroconf_ip: Vec<std::net::IpAddr>) -> Self {
+        self.zeroconf_ip = zeroconf_ip;
+        self
+    }
+
     /// Sets the port on which it should listen to incoming connections.
     /// The default value `0` means any port.
     pub fn port(mut self, port: u16) -> Self {
@@ -117,24 +125,38 @@ impl Builder {
         let mut port = self.port;
         let name = self.server_config.name.clone().into_owned();
         let server = DiscoveryServer::new(self.server_config, &mut port)??;
+        let _zeroconf_ip = self.zeroconf_ip;
+        let svc;
 
         #[cfg(feature = "with-dns-sd")]
-        let svc = dns_sd::DNSService::register(
-            Some(name.as_ref()),
-            "_spotify-connect._tcp",
-            None,
-            None,
-            port,
-            &["VERSION=1.0", "CPath=/"],
-        )?;
+        {
+            svc = dns_sd::DNSService::register(
+                Some(name.as_ref()),
+                "_spotify-connect._tcp",
+                None,
+                None,
+                port,
+                &["VERSION=1.0", "CPath=/"],
+            )?;
+        }
 
         #[cfg(not(feature = "with-dns-sd"))]
-        let svc = libmdns::Responder::spawn(&tokio::runtime::Handle::current())?.register(
-            "_spotify-connect._tcp".to_owned(),
-            name,
-            port,
-            &["VERSION=1.0", "CPath=/"],
-        );
+        {
+            let _svc = if !_zeroconf_ip.is_empty() {
+                libmdns::Responder::spawn_with_ip_list(
+                    &tokio::runtime::Handle::current(),
+                    _zeroconf_ip,
+                )?
+            } else {
+                libmdns::Responder::spawn(&tokio::runtime::Handle::current())?
+            };
+            svc = _svc.register(
+                "_spotify-connect._tcp".to_owned(),
+                name,
+                port,
+                &["VERSION=1.0", "CPath=/"],
+            );
+        }
 
         Ok(Discovery { server, _svc: svc })
     }

src/main.rs

@@ -185,6 +185,7 @@ struct Setup {
     zeroconf_port: u16,
     player_event_program: Option<String>,
     emit_sink_events: bool,
+    zeroconf_ip: Vec<std::net::IpAddr>,
 }
 
 fn get_setup() -> Setup {
@@ -240,6 +241,7 @@ fn get_setup() -> Setup {
     const VOLUME_CTRL: &str = "volume-ctrl";
     const VOLUME_RANGE: &str = "volume-range";
     const ZEROCONF_PORT: &str = "zeroconf-port";
+    const ZEROCONF_INTERFACE: &str = "zeroconf-interface";
 
     // Mostly arbitrary.
     const AP_PORT_SHORT: &str = "a";
@@ -258,6 +260,7 @@ fn get_setup() -> Setup {
     const DISABLE_GAPLESS_SHORT: &str = "g";
     const DISABLE_CREDENTIAL_CACHE_SHORT: &str = "H";
     const HELP_SHORT: &str = "h";
+    const ZEROCONF_INTERFACE_SHORT: &str = "i";
     const CACHE_SIZE_LIMIT_SHORT: &str = "M";
     const MIXER_TYPE_SHORT: &str = "m";
     const ENABLE_VOLUME_NORMALISATION_SHORT: &str = "N";
@@ -570,6 +573,12 @@ fn get_setup() -> Setup {
         AUTOPLAY,
         "Explicitly set autoplay {on|off}. Defaults to following the client setting.",
         "OVERRIDE",
+    )
+    .optopt(
+        ZEROCONF_INTERFACE_SHORT,
+        ZEROCONF_INTERFACE,
+        "Comma-separated interface IP addresses on which zeroconf will bind. Defaults to all interfaces. Ignored by DNS-SD.",
+        "IP"
     );
 
     #[cfg(feature = "passthrough-decoder")]
@@ -1168,6 +1177,31 @@ fn get_setup() -> Setup {
         None => SessionConfig::default().autoplay,
     };
 
+    let zeroconf_ip: Vec<std::net::IpAddr> = if opt_present(ZEROCONF_INTERFACE) {
+        if let Some(zeroconf_ip) = opt_str(ZEROCONF_INTERFACE) {
+            zeroconf_ip
+                .split(',')
+                .map(|s| {
+                    s.trim().parse::<std::net::IpAddr>().unwrap_or_else(|_| {
+                        invalid_error_msg(
+                            ZEROCONF_INTERFACE,
+                            ZEROCONF_INTERFACE_SHORT,
+                            s,
+                            "IPv4 and IPv6 addresses",
+                            "",
+                        );
+                        exit(1);
+                    })
+                })
+                .collect()
+        } else {
+            warn!("Unable to use zeroconf-interface option, default to all interfaces.");
+            vec![]
+        }
+    } else {
+        vec![]
+    };
+
     let connect_config = {
         let connect_default_config = ConnectConfig::default();
 
@@ -1608,6 +1642,7 @@ fn get_setup() -> Setup {
         zeroconf_port,
         player_event_program,
         emit_sink_events,
+        zeroconf_ip,
     }
 }
 
@@ -1640,6 +1675,7 @@ async fn main() {
             .name(setup.connect_config.name.clone())
             .device_type(setup.connect_config.device_type)
             .port(setup.zeroconf_port)
+            .zeroconf_ip(setup.zeroconf_ip)
             .launch()
         {
             Ok(d) => discovery = Some(d),