add interface_id in ScopedIpV4

src/dns_parser.rs

@@ -33,6 +33,18 @@ pub struct InterfaceId {
     pub index: u32,
 }
 
+impl InterfaceId {
+    /// Returns all IP addresses associated with this interface by querying the OS.
+    pub fn get_addrs(&self) -> Vec<IpAddr> {
+        if_addrs::get_if_addrs()
+            .unwrap_or_default()
+            .into_iter()
+            .filter(|iface| iface.index == Some(self.index))
+            .map(|iface| iface.ip())
+            .collect()
+    }
+}
+
 impl fmt::Display for InterfaceId {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         write!(f, "{}('{}')", self.index, self.name)
@@ -48,20 +60,24 @@ impl From<&Interface> for InterfaceId {
     }
 }
 
-/// An IPv4 address used in `ScopedIp`.
-///
-/// Note: IPv4 addresses don't have scope IDs, but this type is named for consistency
-/// with the rest of the addressing system.
+/// An IPv4 address with an interface identifier.
 #[derive(Debug, Clone, Eq, PartialEq, Hash)]
 pub struct ScopedIpV4 {
     addr: Ipv4Addr,
+    /// The `interface_id` indicates which interface this address is associated with.
+    interface_id: InterfaceId,
 }
 
 impl ScopedIpV4 {
     /// Returns the IPv4 address.
     pub const fn addr(&self) -> &Ipv4Addr {
         &self.addr
     }
+
+    /// Returns the interface this address is found on.
+    pub const fn interface_id(&self) -> &InterfaceId {
+        &self.interface_id
+    }
 }
 
 /// An IPv6 address with scope_id (interface identifier).
@@ -113,12 +129,23 @@ impl ScopedIp {
             ScopedIp::V6(v6) => v6.addr.is_loopback(),
         }
     }
+
+    /// Returns the interface identifier for this address.
+    pub const fn interface_id(&self) -> &InterfaceId {
+        match self {
+            ScopedIp::V4(v4) => &v4.interface_id,
+            ScopedIp::V6(v6) => &v6.scope_id,
+        }
+    }
 }
 
 impl From<IpAddr> for ScopedIp {
     fn from(ip: IpAddr) -> Self {
         match ip {
-            IpAddr::V4(v4) => ScopedIp::V4(ScopedIpV4 { addr: v4 }),
+            IpAddr::V4(v4) => ScopedIp::V4(ScopedIpV4 {
+                addr: v4,
+                interface_id: InterfaceId::default(),
+            }),
             IpAddr::V6(v6) => ScopedIp::V6(ScopedIpV6 {
                 addr: v6,
                 scope_id: InterfaceId::default(),
@@ -130,7 +157,10 @@ impl From<IpAddr> for ScopedIp {
 impl From<&Interface> for ScopedIp {
     fn from(interface: &Interface) -> Self {
         match interface.ip() {
-            IpAddr::V4(v4) => ScopedIp::V4(ScopedIpV4 { addr: v4 }),
+            IpAddr::V4(v4) => ScopedIp::V4(ScopedIpV4 {
+                addr: v4,
+                interface_id: InterfaceId::from(interface),
+            }),
             IpAddr::V6(v6) => ScopedIp::V6(ScopedIpV6 {
                 addr: v6,
                 scope_id: InterfaceId::from(interface),
@@ -666,7 +696,10 @@ impl DnsAddress {
 
     pub fn address(&self) -> ScopedIp {
         match self.address {
-            IpAddr::V4(v4) => ScopedIp::V4(ScopedIpV4 { addr: v4 }),
+            IpAddr::V4(v4) => ScopedIp::V4(ScopedIpV4 {
+                addr: v4,
+                interface_id: self.interface_id.clone(),
+            }),
             IpAddr::V6(v6) => ScopedIp::V6(ScopedIpV6 {
                 addr: v6,
                 scope_id: self.interface_id.clone(),

src/service_daemon.rs

@@ -4966,7 +4966,7 @@ mod tests {
         let service_ip_addr: ScopedIp = my_ip_interfaces(false)
             .iter()
             .find(|iface| iface.ip().is_ipv4())
-            .map(|iface| iface.ip().into())
+            .map(|iface| iface.into())
             .unwrap();
 
         let mut my_service = ServiceInfo::new(

tests/mdns_test.rs

@@ -1,7 +1,7 @@
 use if_addrs::{IfAddr, Interface};
 use mdns_sd::{
-    DaemonEvent, DaemonStatus, HostnameResolutionEvent, IfKind, IntoTxtProperties, ScopedIp,
-    ServiceDaemon, ServiceEvent, ServiceInfo, TxtProperty, UnregisterStatus,
+    DaemonEvent, DaemonStatus, HostnameResolutionEvent, IfKind, InterfaceId, IntoTxtProperties,
+    ScopedIp, ServiceDaemon, ServiceEvent, ServiceInfo, TxtProperty, UnregisterStatus,
 };
 use std::collections::{HashMap, HashSet};
 use std::net::{IpAddr, Ipv4Addr, Ipv6Addr};
@@ -2553,6 +2553,26 @@ fn test_rfc6763_utf8_network_integration() {
     d.shutdown().unwrap();
 }
 
+#[test]
+fn test_interface_id_get_addrs() {
+    // Get actual interfaces from the OS to build a valid InterfaceId.
+    let if_addrs = if_addrs::get_if_addrs().expect("failed to get interfaces");
+    let first = if_addrs.first().expect("no interfaces found");
+    let intf_id = InterfaceId::from(first);
+
+    let addrs = intf_id.get_addrs();
+    assert!(
+        !addrs.is_empty(),
+        "interface {} should have at least one address",
+        intf_id.name
+    );
+    assert!(
+        addrs.contains(&first.ip()),
+        "get_addrs() should contain the address we constructed from: {}",
+        first.ip()
+    );
+}
+
 /// A helper function to include a timestamp for println.
 fn timed_println(msg: String) {
     let now = SystemTime::now();