set & get MTU issues

src/adapter.rs

@@ -197,13 +197,16 @@ impl Adapter {
     /// Set `MTU` of this adapter
     pub fn set_mtu(&self, mtu: usize) -> Result<(), Error> {
         let name = self.get_name()?;
-        Ok(util::set_adapter_mtu(&name, mtu)?)
+        util::set_adapter_mtu(&name, mtu, false)?;
+        // FIXME: Here we set the IPv6 MTU as well for consistency, but for some users it may not be expected.
+        util::set_adapter_mtu(&name, mtu, true)?;
+        Ok(())
     }
 
     /// Returns `MTU` of this adapter
     pub fn get_mtu(&self) -> Result<usize, Error> {
-        let luid = self.get_luid();
-        Ok(util::get_adapter_mtu(&luid)?)
+        // FIXME: Here we get the IPv4 MTU only, but for some users it may not be expected.
+        Ok(util::get_mtu_by_index(self.index, false)? as _)
     }
 
     /// Returns the Win32 interface index of this adapter. Useful for specifying the interface

src/util.rs

@@ -9,12 +9,13 @@ use windows_sys::{
         },
         NetworkManagement::{
             IpHelper::{
-                FreeMibTable, GetAdaptersAddresses, GetIfTable2, GetInterfaceInfo, DNS_INTERFACE_SETTINGS,
+                FreeMibTable, GetAdaptersAddresses, GetInterfaceInfo, DNS_INTERFACE_SETTINGS,
                 DNS_INTERFACE_SETTINGS_VERSION1, DNS_SETTING_NAMESERVER, GAA_FLAG_INCLUDE_GATEWAYS,
                 GAA_FLAG_INCLUDE_PREFIX, IF_TYPE_ETHERNET_CSMACD, IF_TYPE_IEEE80211, IP_ADAPTER_ADDRESSES_LH,
-                IP_ADAPTER_INDEX_MAP, IP_INTERFACE_INFO, MIB_IF_ROW2, MIB_IF_TABLE2,
+                IP_ADAPTER_INDEX_MAP, IP_INTERFACE_INFO,
             },
-            Ndis::{IfOperStatusUp, NET_LUID_LH},
+            IpHelper::{GetIpInterfaceTable, MIB_IPINTERFACE_ROW, MIB_IPINTERFACE_TABLE},
+            Ndis::IfOperStatusUp,
         },
         Networking::WinSock::{AF_INET, AF_INET6, AF_UNSPEC, SOCKADDR, SOCKADDR_IN, SOCKADDR_IN6, SOCKET_ADDRESS},
         System::{
@@ -424,19 +425,20 @@ pub(crate) fn get_os_error_from_id(id: i32) -> std::io::Result<()> {
     }
 }
 
-pub fn set_adapter_mtu(name: &str, mtu: usize) -> std::io::Result<()> {
-    if let Err(e) = set_adapter_mtu_cmd(name, mtu) {
+pub fn set_adapter_mtu(name: &str, mtu: usize, is_ipv6: bool) -> std::io::Result<()> {
+    if let Err(e) = set_adapter_mtu_cmd(name, mtu, is_ipv6) {
         log::error!("Failed to set MTU for adapter: {}", e);
         set_adapter_mtu_api(name, mtu)?;
     }
     Ok(())
 }
 
-pub fn set_adapter_mtu_cmd(name: &str, mtu: usize) -> std::io::Result<()> {
+pub fn set_adapter_mtu_cmd(name: &str, mtu: usize, is_ipv6: bool) -> std::io::Result<()> {
     // command line: `netsh interface ipv4 set subinterface "MyAdapter" mtu=1500`
+    let ip_str = if is_ipv6 { "ipv6" } else { "ipv4" };
     let args = &[
         "interface",
-        "ipv4",
+        ip_str,
         "set",
         "subinterface",
         &format!("\"{}\"", name),
@@ -494,6 +496,9 @@ pub fn run_command(command: &str, args: &[&str]) -> std::io::Result<Vec<u8>> {
     Ok(out.stdout)
 }
 
+/*
+use windows_sys::Win32::NetworkManagement::IpHelper::{GetIfTable2, MIB_IF_ROW2, MIB_IF_TABLE2};
+use windows_sys::Win32::NetworkManagement::Ndis::NET_LUID_LH;
 pub(crate) fn get_adapter_mtu(luid: &NET_LUID_LH) -> std::io::Result<usize> {
     unsafe {
         let mut if_table: *mut MIB_IF_TABLE2 = std::ptr::null_mut();
@@ -524,12 +529,55 @@ pub(crate) fn get_adapter_mtu(luid: &NET_LUID_LH) -> std::io::Result<usize> {
         mtu.ok_or(std::io::Error::new(std::io::ErrorKind::NotFound, "Adapter not found"))
     }
 }
+// */
+
+pub(crate) fn get_mtu_by_index(index: u32, is_ipv6: bool) -> std::io::Result<u32> {
+    let mut mtu = None;
+    get_ip_interface_table(
+        |item| {
+            if item.InterfaceIndex == index {
+                mtu = Some(item.NlMtu);
+            }
+            Ok(())
+        },
+        is_ipv6,
+    )?;
+    let Some(mtu) = mtu else {
+        return Err(std::io::Error::from(std::io::ErrorKind::NotFound));
+    };
+    Ok(mtu)
+}
 
 pub fn decode_utf16(string: &[u16]) -> String {
     let end = string.iter().position(|b| *b == 0).unwrap_or(string.len());
     String::from_utf16_lossy(&string[..end])
 }
 
+pub fn get_ip_interface_table<F>(mut callback: F, is_ipv6: bool) -> std::io::Result<()>
+where
+    F: FnMut(&MIB_IPINTERFACE_ROW) -> std::io::Result<()>,
+{
+    let mut if_table: *mut MIB_IPINTERFACE_TABLE = std::ptr::null_mut();
+    unsafe {
+        if GetIpInterfaceTable(if is_ipv6 { AF_INET6 } else { AF_INET }, &mut if_table as _) != NO_ERROR {
+            return Err(std::io::Error::last_os_error());
+        }
+        if if_table.is_null() {
+            return Err(std::io::Error::from(std::io::ErrorKind::NotFound));
+        }
+        use std::slice::from_raw_parts;
+        let ifaces = from_raw_parts::<MIB_IPINTERFACE_ROW>(&(*if_table).Table[0], (*if_table).NumEntries as usize);
+        for item in ifaces {
+            if let Err(e) = callback(item) {
+                FreeMibTable(if_table as _);
+                return Err(e);
+            }
+        }
+        FreeMibTable(if_table as _);
+    }
+    Ok(())
+}
+
 #[repr(C, align(1))]
 #[derive(c2rust_bitfields::BitfieldStruct)]
 #[allow(non_snake_case)]