Return interface name

mozilla · larseggert · Sep 4, 2024 · Sep 3, 2024 · Sep 3, 2024 · Sep 3, 2024
commit dce0de85896c9a5a629bcd013f77caf4602365e5
@@ -13,15 +13,13 @@ use std::{
 use log::trace;
 
 /// Prepare a default error result.
-fn default_result<T>() -> Result<(InterfaceId, T), Error> {
+fn default_result<T>() -> Result<(String, T), Error> {
     Err(Error::new(
         ErrorKind::NotFound,
         "Local interface MTU not found",
     ))
 }
 
-type InterfaceId = u64;
-
 /// Return a unique interface ID and the maximum transmission unit (MTU) of the local network
 /// interface towards the destination [`SocketAddr`] given in `remote`.
 ///
@@ -37,14 +35,14 @@ type InterfaceId = u64;
 ///
 /// ```
 /// let saddr = "127.0.0.1:443".parse().unwrap();
-/// let (id, mtu) = mtu::get_interface_and_mtu(&saddr).unwrap();
-/// println!("MTU towards {:?} is {}", saddr, mtu);
+/// let (name, mtu) = mtu::get_interface_and_mtu(&saddr).unwrap();
+/// println!("MTU towards {saddr:?} is {mtu} on {name}");
 /// ```
 ///
 /// # Errors
 ///
 /// This function returns an error if the local interface MTU cannot be determined.
-pub fn get_interface_and_mtu(remote: &SocketAddr) -> Result<(InterfaceId, usize), Error> {
+pub fn get_interface_and_mtu(remote: &SocketAddr) -> Result<(String, usize), Error> {
     #[cfg(any(target_os = "macos", target_os = "linux", target_os = "windows"))]
     #[allow(unused_assignments)] // Yes, res is reassigned in the platform-specific code.
     let mut res = default_result();
@@ -79,13 +77,10 @@ pub fn get_interface_and_mtu(remote: &SocketAddr) -> Result<(InterfaceId, usize)
 }
 
 #[cfg(any(target_os = "macos", target_os = "linux"))]
-fn get_interface_and_mtu_linux_macos(socket: &UdpSocket) -> Result<(InterfaceId, usize), Error> {
+fn get_interface_and_mtu_linux_macos(socket: &UdpSocket) -> Result<(String, usize), Error> {
+    use std::ffi::{c_int, CStr};
     #[cfg(target_os = "linux")]
     use std::{ffi::c_char, mem, os::fd::AsRawFd};
-    use std::{
-        ffi::{c_int, CStr},
-        hash::{DefaultHasher, Hash, Hasher},
-    };
 
     use libc::{
         freeifaddrs, getifaddrs, ifaddrs, in_addr_t, sockaddr_in, sockaddr_in6, AF_INET, AF_INET6,
@@ -95,12 +90,6 @@ fn get_interface_and_mtu_linux_macos(socket: &UdpSocket) -> Result<(InterfaceId,
     #[cfg(target_os = "linux")]
     use libc::{ifreq, ioctl};
 
-    fn hash_interface_name(name: &str) -> InterfaceId {
-        let mut hasher = DefaultHasher::new();
-        name.hash(&mut hasher);
-        hasher.finish()
-    }
-
     // Get the interface list.
     let mut ifap: *mut ifaddrs = ptr::null_mut();
     if unsafe { getifaddrs(&mut ifap) } != 0 {
@@ -163,7 +152,7 @@ fn get_interface_and_mtu_linux_macos(socket: &UdpSocket) -> Result<(InterfaceId,
                     {
                         let data = unsafe { &*(ifa.ifa_data as *const if_data) };
                         if let Ok(mtu) = usize::try_from(data.ifi_mtu) {
-                            res = Ok((hash_interface_name(iface), mtu));
+                            res = Ok((iface.to_string(), mtu));
                         }
                         break;
                     }
@@ -182,7 +171,7 @@ fn get_interface_and_mtu_linux_macos(socket: &UdpSocket) -> Result<(InterfaceId,
             if unsafe { ioctl(socket.as_raw_fd(), libc::SIOCGIFMTU, &ifr) } != 0 {
                 res = Err(Error::last_os_error());
             } else if let Ok(mtu) = usize::try_from(unsafe { ifr.ifr_ifru.ifru_mtu }) {
-                res = Ok((hash_interface_name(iface), mtu));
+                res = Ok((iface.to_string(), mtu));
             }
         }
     }
@@ -192,18 +181,15 @@ fn get_interface_and_mtu_linux_macos(socket: &UdpSocket) -> Result<(InterfaceId,
 }
 
 #[cfg(target_os = "windows")]
-fn get_interface_and_mtu_windows(socket: &UdpSocket) -> Result<(InterfaceId, usize), Error> {
-    use std::{
-        ffi::c_void,
-        hash::{DefaultHasher, Hash, Hasher},
-        slice,
-    };
+fn get_interface_and_mtu_windows(socket: &UdpSocket) -> Result<(String, usize), Error> {
+    use std::{ffi::c_void, slice};
 
     use windows::Win32::{
         Foundation::NO_ERROR,
         NetworkManagement::IpHelper::{
-            FreeMibTable, GetIpInterfaceTable, GetUnicastIpAddressTable, MIB_IPINTERFACE_ROW,
-            MIB_IPINTERFACE_TABLE, MIB_UNICASTIPADDRESS_ROW, MIB_UNICASTIPADDRESS_TABLE,
+            if_indextoname, FreeMibTable, GetIpInterfaceTable, GetUnicastIpAddressTable,
+            MIB_IPINTERFACE_ROW, MIB_IPINTERFACE_TABLE, MIB_UNICASTIPADDRESS_ROW,
+            MIB_UNICASTIPADDRESS_TABLE,
         },
         Networking::WinSock::{AF_INET, AF_INET6, AF_UNSPEC},
     };
@@ -257,10 +243,9 @@ fn get_interface_and_mtu_windows(socket: &UdpSocket) -> Result<(InterfaceId, usi
             for iface in ifaces {
                 if iface.InterfaceIndex == addr.InterfaceIndex {
                     if let Ok(mtu) = iface.NlMtu.try_into() {
-                        let mut hasher = DefaultHasher::new();
-                        iface.InterfaceIndex.hash(&mut hasher);
-                        let id = hasher.finish();
-                        res = Ok((id, mtu));
+                        if_indextoname(iface.InterfaceIndex, |name| {
+                            res = Ok((name, mtu));
+                        });
                     }
                     break 'addr_loop;
                 }
@@ -289,7 +274,7 @@ fn get_interface_and_mtu_windows(socket: &UdpSocket) -> Result<(InterfaceId, usi
 /// ```
 /// let saddr = "127.0.0.1:443".parse().unwrap();
 /// let mtu = mtu::get_interface_mtu(&saddr).unwrap();
-/// println!("MTU towards {:?} is {}", saddr, mtu);
+/// println!("MTU towards {saddr:?} is {mtu}");
 /// ```
 ///
 /// # Errors