Merge pull request #58 from eladyn/duplicate_joins_ipv4

avoid joining multiple times on the same interface for ipv4

Cargo.toml

@@ -21,12 +21,6 @@ thiserror = "1.0"
 tokio = { version = "1.0", features = ["sync", "net", "rt"] }
 socket2 = { version = "0.5", features = ["all"] }
 
-[target.'cfg(windows)'.dependencies]
-winapi = { version = "0.3", features = ["netioapi"] }
-
-[target.'cfg(not(windows))'.dependencies]
-nix = { version = "0.28", features = ["net"] }
-
 [dev-dependencies]
 env_logger = { version = "0.10.2", default-features = false, features = [
   "color",

src/address_family.rs

@@ -1,15 +1,10 @@
 use super::MDNS_PORT;
-use if_addrs::get_if_addrs;
+use if_addrs::{get_if_addrs, Interface};
 use socket2::{Domain, Protocol, SockAddr, Socket, Type};
+use std::collections::HashSet;
 use std::io;
 use std::net::{IpAddr, Ipv4Addr, Ipv6Addr, SocketAddr, UdpSocket};
 
-#[cfg(not(windows))]
-use nix::net::if_::if_nametoindex;
-
-#[cfg(windows)]
-use win::if_nametoindex;
-
 pub enum Inet {}
 
 pub enum Inet6 {}
@@ -52,12 +47,12 @@ impl AddressFamily for Inet {
     const DOMAIN: Domain = Domain::IPV4;
 
     fn join_multicast(socket: &Socket, multiaddr: &Self::Addr) -> io::Result<()> {
-        let addresses = get_address_list()?;
-        if addresses.is_empty() {
+        let ifaces = get_iface_list()?;
+        if ifaces.is_empty() {
             socket.join_multicast_v4(multiaddr, &Ipv4Addr::UNSPECIFIED)
         } else {
-            for (_, address) in addresses {
-                if let IpAddr::V4(ip) = address {
+            for iface in ifaces {
+                if let IpAddr::V4(ip) = iface.ip() {
                     socket.join_multicast_v4(multiaddr, &ip)?;
                 }
             }
@@ -75,44 +70,28 @@ impl AddressFamily for Inet6 {
     const DOMAIN: Domain = Domain::IPV6;
 
     fn join_multicast(socket: &Socket, multiaddr: &Self::Addr) -> io::Result<()> {
-        let addresses = get_address_list()?;
-        if addresses.is_empty() {
+        let ifaces = get_iface_list()?;
+        if ifaces.is_empty() {
             socket.join_multicast_v6(multiaddr, 0)
         } else {
-            // We join multicast by interface, but each interface can have more than one ipv6 address.
-            // So we have to check we're not registering more than once, as the resulting error is then
-            // fatal to ipv6 listening.
             // TODO: Make each interface resilient to failures on another.
-            let mut registered = Vec::new();
-            for (iface_name, address) in addresses {
-                if let IpAddr::V6(_) = address {
-                    let ipv6_index = if_nametoindex(iface_name.as_str()).unwrap_or(0);
-                    if ipv6_index != 0 && !registered.contains(&ipv6_index) {
-                        socket.join_multicast_v6(multiaddr, ipv6_index)?;
-                        registered.push(ipv6_index);
-                    }
+            for iface in ifaces {
+                if let (IpAddr::V6(_), Some(ipv6_index)) = (iface.ip(), iface.index) {
+                    socket.join_multicast_v6(multiaddr, ipv6_index)?;
                 }
             }
             Ok(())
         }
     }
 }
 
-fn get_address_list() -> io::Result<Vec<(String, IpAddr)>> {
+fn get_iface_list() -> io::Result<Vec<Interface>> {
+    // 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()?
-        .iter()
-        .filter(|iface| !iface.is_loopback())
-        .map(|iface| (iface.name.clone(), iface.ip()))
+        .into_iter()
+        .filter(|iface| !iface.is_loopback() && collected_interfaces.insert(iface.name.clone()))
         .collect())
 }
-
-#[cfg(windows)]
-mod win {
-    use std::ffi::{CString, NulError};
-    use winapi::shared::netioapi;
-
-    pub fn if_nametoindex(ifname: &str) -> Result<u32, NulError> {
-        let c_str = CString::new(ifname)?;
-        Ok(unsafe { netioapi::if_nametoindex(c_str.as_ptr()) })
-    }
-}