diff options
| -rw-r--r-- | talpid-core/src/tunnel/mod.rs | 14 |
1 files changed, 12 insertions, 2 deletions
diff --git a/talpid-core/src/tunnel/mod.rs b/talpid-core/src/tunnel/mod.rs index a0fda069f5..302c8003c9 100644 --- a/talpid-core/src/tunnel/mod.rs +++ b/talpid-core/src/tunnel/mod.rs @@ -223,8 +223,16 @@ impl TunnelMonitor { }) } + /// Set the MTU in the tunnel parameters based on the inputted device MTU and some + /// calculations. `peer_mtu` is the detected device MTU. #[cfg(any(target_os = "linux", target_os = "windows"))] fn set_mtu(params: &mut wireguard_types::TunnelParameters, peer_mtu: u16) { + // Some users experience fragmentation issues even when we take the interface MTU and + // subtract the header sizes. This is likely due to some program that they use which does + // not change the interface MTU but adds its own header onto the outgoing packets. For this + // reason we subtract some extra bytes from our MTU in order to give other programs some + // safety margin. + const MTU_SAFETY_MARGIN: u16 = 60; const IPV4_HEADER_SIZE: u16 = 20; const IPV6_HEADER_SIZE: u16 = 40; const WIREGUARD_HEADER_SIZE: u16 = 40; @@ -234,8 +242,8 @@ impl TunnelMonitor { true => IPV6_HEADER_SIZE, }; // The largest peer MTU that we allow - const MAX_PEER_MTU: u16 = 1500; - // The minimum allowed MTU size for our tunnel in IPv6 is 1280 + const MAX_PEER_MTU: u16 = 1500 - MTU_SAFETY_MARGIN; + // The minimum allowed MTU size for our tunnel in IPv6 is 1280 and 576 for IPv4 const MIN_IPV4_MTU: u16 = 576; const MIN_IPV6_MTU: u16 = 1280; let min_mtu = match params.generic_options.enable_ipv6 { @@ -248,6 +256,8 @@ impl TunnelMonitor { params.options.mtu = Some(tunnel_mtu); } + /// Detects the MTU of the device, calculates what the virtual device MTU should be and sets + /// that in the tunnel parameters. #[cfg(any(target_os = "linux", target_os = "windows"))] async fn assign_mtu( route_manager: &RouteManagerHandle, |