Bug 1567201 - Join multicast group on all interfaces; r=mjf

We need to join the multicast group on all network interfaces or we may end up
missing packets. There is a limit on the number of groups joinable by a single
socket (20 on my Linux system) but it doesn't seem worth worrying about
hitting that limit at the moment as it seems unlikely that many users would
have more than 20 network interfaces on a system on which they are running
Firefox.

Differential Revision: https://phabricator.services.mozilla.com/D46981

--HG--
extra : moz-landing-system : lando

media/mtransport/ipc/StunAddrsRequestParent.cpp

@@ -170,17 +170,21 @@ void StunAddrsRequestParent::SendStunAddrs_m(const NrIceStunAddrArray& addrs) {
   // registered after UnregisterHostname is called, and if so, stop the mDNS
   // service at that time (see Bug 1569955.)
   if (!mSharedMDNSService) {
+    std::ostringstream o;
+    char buffer[16];
     for (auto& addr : addrs) {
       nr_transport_addr* local_addr =
           const_cast<nr_transport_addr*>(&addr.localAddr().addr);
       if (addr.localAddr().addr.ip_version == NR_IPV4 &&
           !nr_transport_addr_is_loopback(local_addr)) {
-        char addrstring[16];
-        nr_transport_addr_get_addrstring(local_addr, addrstring, 16);
-        mSharedMDNSService = new MDNSServiceWrapper(addrstring);
-        break;
+        nr_transport_addr_get_addrstring(local_addr, buffer, 16);
+        o << buffer << ";";
       }
     }
+    std::string addrstring = o.str();
+    if (!addrstring.empty()) {
+      mSharedMDNSService = new MDNSServiceWrapper(addrstring);
+    }
   }
 
   // send the new addresses back to the child

media/mtransport/mdns_service/src/lib.rs

@@ -236,10 +236,11 @@ impl MDNSService {
         }
     }
 
-    fn start(&mut self, addr: std::net::Ipv4Addr) -> io::Result<()> {
+    fn start(&mut self, addrs: Vec<std::net::Ipv4Addr>) -> io::Result<()> {
         let (sender, receiver) = channel();
         self.sender = Some(sender);
 
+        let mdns_addr = std::net::Ipv4Addr::new(224, 0, 0, 251);
         let port = 5353;
 
         let socket = Socket::new(Domain::ipv4(), Type::dgram(), None).unwrap();
@@ -255,7 +256,14 @@ impl MDNSService {
         let socket = socket.into_udp_socket();
         socket.set_multicast_loop_v4(true)?;
         socket.set_read_timeout(Some(time::Duration::from_millis(10)))?;
-        socket.join_multicast_v4(&std::net::Ipv4Addr::new(224, 0, 0, 251), &addr)?;
+        for addr in addrs {
+            if let Err(err) = socket.join_multicast_v4(&mdns_addr, &addr) {
+                warn!(
+                    "Could not join multicast group on interface: {:?}: {}",
+                    addr, err
+                );
+            }
+        }
 
         let builder = thread::Builder::new().name("mdns_service".to_string());
         self.handle = Some(builder.spawn(move || {
@@ -500,17 +508,18 @@ pub extern "C" fn mdns_service_register_hostname(
 }
 
 #[no_mangle]
-pub extern "C" fn mdns_service_start(ifaddr: *const c_char) -> *mut MDNSService {
-    assert!(!ifaddr.is_null());
+pub extern "C" fn mdns_service_start(ifaddrs: *const c_char) -> *mut MDNSService {
+    assert!(!ifaddrs.is_null());
     let mut r = Box::new(MDNSService::new());
     unsafe {
-        let ifaddr = CStr::from_ptr(ifaddr).to_string_lossy();
-        if let Ok(addr) = ifaddr.parse() {
-            if let Err(err) = r.start(addr) {
-                warn!("Could not start mDNS Service: {}", err);
-            }
-        } else {
-            warn!("Could not parse interface address: {}", ifaddr);
+        let ifaddrs = CStr::from_ptr(ifaddrs).to_string_lossy();
+        let addrs: Vec<std::net::Ipv4Addr> =
+            ifaddrs.split(';').filter_map(|x| x.parse().ok()).collect();
+
+        if addrs.len() == 0 {
+            warn!("Could not parse interface addresses from: {}", ifaddrs);
+        } else if let Err(err) = r.start(addrs) {
+            warn!("Could not start mDNS Service: {}", err);
         }
     }
     Box::into_raw(r)
@@ -685,7 +694,7 @@ mod tests {
     fn start_stop() {
         let mut service = MDNSService::new();
         let addr = "127.0.0.1".parse().unwrap();
-        service.start(addr).unwrap();
+        service.start(vec![addr]).unwrap();
         service.stop();
     }
 
@@ -695,7 +704,7 @@ mod tests {
         let addr = "127.0.0.1".parse().unwrap();
         let handle = listen_until(&addr, 1);
 
-        service.start(addr).unwrap();
+        service.start(vec![addr]).unwrap();
 
         let callback = Callback {
             data: 0 as *const c_void,
@@ -714,7 +723,7 @@ mod tests {
         let addr = "127.0.0.1".parse().unwrap();
         let handle = listen_until(&addr, 1);
 
-        service.start(addr).unwrap();
+        service.start(vec![addr]).unwrap();
 
         let mut hostnames = HashSet::new();
         for _ in 0..100 {
@@ -738,7 +747,7 @@ mod tests {
         let addr = "127.0.0.1".parse().unwrap();
         let handle = listen_until(&addr, 4);
 
-        service.start(addr).unwrap();
+        service.start(vec![addr]).unwrap();
 
         let hostname = Uuid::new_v4().to_hyphenated().to_string() + ".local";
         let callback = Callback {