Filter v4 and v6 Interface objects separately

src/address_family.rs

@@ -1,5 +1,5 @@
 use super::MDNS_PORT;
-use if_addrs::{get_if_addrs, Interface};
+use if_addrs::{get_if_addrs, IfAddr};
 use socket2::{Domain, Protocol, SockAddr, Socket, Type};
 use std::collections::HashSet;
 use std::io;
@@ -47,14 +47,13 @@ impl AddressFamily for Inet {
     const DOMAIN: Domain = Domain::IPV4;
 
     fn join_multicast(socket: &Socket, multiaddr: &Self::Addr) -> io::Result<()> {
-        let ifaces = get_iface_list()?;
-        if ifaces.is_empty() {
+        let addrs = get_one_nonloopback_ipv4_addr_per_iface()?;
+        if addrs.is_empty() {
             socket.join_multicast_v4(multiaddr, &Ipv4Addr::UNSPECIFIED)
         } else {
-            for iface in ifaces {
-                if let IpAddr::V4(ip) = iface.ip() {
-                    socket.join_multicast_v4(multiaddr, &ip)?;
-                }
+            // TODO: If any join succeeds return success (log failures)
+            for ip in addrs {
+                socket.join_multicast_v4(multiaddr, &ip)?;
             }
             Ok(())
         }
@@ -70,28 +69,62 @@ impl AddressFamily for Inet6 {
     const DOMAIN: Domain = Domain::IPV6;
 
     fn join_multicast(socket: &Socket, multiaddr: &Self::Addr) -> io::Result<()> {
-        let ifaces = get_iface_list()?;
-        if ifaces.is_empty() {
+        let indexes = get_one_nonloopback_ipv6_index_per_iface()?;
+        if indexes.is_empty() {
             socket.join_multicast_v6(multiaddr, 0)
         } else {
-            // TODO: Make each interface resilient to failures on another.
-            for iface in ifaces {
-                if let (IpAddr::V6(_), Some(ipv6_index)) = (iface.ip(), iface.index) {
-                    socket.join_multicast_v6(multiaddr, ipv6_index)?;
-                }
+            // TODO: If any join succeeds return success (log failures)
+            for ipv6_index in indexes {
+                socket.join_multicast_v6(multiaddr, ipv6_index)?;
             }
             Ok(())
         }
     }
 }
 
-fn get_iface_list() -> io::Result<Vec<Interface>> {
+fn get_one_nonloopback_ipv6_index_per_iface() -> io::Result<Vec<u32>> {
+    // There may be multiple ip addresses on a single interface and we join multicast by interface.
+    // Joining multicast on the same interface multiple times returns an error
+    // so we filter duplicate interfaces.
+    let mut collected_interfaces = HashSet::new();
+    Ok(get_if_addrs()?
+        .into_iter()
+        .filter_map(|iface| {
+            if iface.is_loopback() {
+                None
+            } else if matches!(iface.addr, IfAddr::V6(_)) {
+                if collected_interfaces.insert(iface.name.clone()) {
+                    iface.index
+                } else {
+                    None
+                }
+            } else {
+                None
+            }
+        })
+        .collect())
+}
+
+fn get_one_nonloopback_ipv4_addr_per_iface() -> io::Result<Vec<Ipv4Addr>> {
     // There may be multiple ip addresses on a single interface and we join multicast by interface.
     // Joining multicast on the same interface multiple times returns an error
     // so we filter duplicate interfaces.
     let mut collected_interfaces = HashSet::new();
     Ok(get_if_addrs()?
         .into_iter()
-        .filter(|iface| !iface.is_loopback() && collected_interfaces.insert(iface.name.clone()))
+        .filter_map(|iface| {
+            if iface.is_loopback() {
+                None
+            } else if let IpAddr::V4(ip) = iface.ip() {
+                if collected_interfaces.insert(iface.name.clone()) {
+                    Some(ip)
+                } else {
+                    None
+                }
+            } else {
+                None
+            }
+        })
         .collect())
 }
+