ICMP handled by smoltcp stack. Disable rx checksum verification

Author: zonyitoo

crates/shadowsocks-service/src/local/tun/mod.rs

@@ -13,7 +13,7 @@ use byte_string::ByteStr;
 use ipnet::IpNet;
 use log::{debug, error, info, trace, warn};
 use shadowsocks::config::Mode;
-use smoltcp::wire::{Icmpv4Packet, Icmpv6Packet, IpProtocol, TcpPacket, UdpPacket};
+use smoltcp::wire::{IpProtocol, TcpPacket, UdpPacket};
 use tokio::io::AsyncReadExt;
 use tun::{AsyncDevice, Configuration as TunConfiguration, Device as TunDevice, Error as TunError, Layer};
 
@@ -267,7 +267,9 @@ impl Tun {
                 }
             }
             IpProtocol::Icmp | IpProtocol::Icmpv6 => {
-                self.handle_icmp_packet(&packet).await?;
+                // ICMP is handled by TCP's Interface.
+                // smoltcp's interface will always send replies to EchoRequest
+                self.tcp.drive_interface_state(frame).await;
             }
             _ => {
                 debug!("IP packet ignored (protocol: {:?})", packet.protocol());
@@ -277,25 +279,4 @@ impl Tun {
 
         Ok(())
     }
-
-    async fn handle_icmp_packet(&self, packet: &IpPacket<&[u8]>) -> smoltcp::Result<()> {
-        match *packet {
-            IpPacket::Ipv4(ref ipv4) => {
-                let icmp = Icmpv4Packet::new_checked(ipv4.payload())?;
-                trace!("[TUN] received {}", icmp);
-            }
-            IpPacket::Ipv6(ref ipv6) => {
-                let icmp = Icmpv6Packet::new_checked(ipv6.payload())?;
-                trace!(
-                    "[TUN] received ICMPv6 {:?} code={} echo_ident={} echo_seq_no={}",
-                    icmp.msg_type(),
-                    icmp.msg_code(),
-                    icmp.echo_ident(),
-                    icmp.echo_seq_no()
-                );
-            }
-        }
-
-        Ok(())
-    }
 }

crates/shadowsocks-service/src/local/tun/tcp.rs

@@ -14,7 +14,7 @@ use parking_lot::Mutex as ParkingMutex;
 use shadowsocks::{net::TcpSocketOpts, relay::socks5::Address};
 use smoltcp::{
     iface::{Interface, InterfaceBuilder, Routes, SocketHandle},
-    phy::{DeviceCapabilities, Medium},
+    phy::{Checksum, ChecksumCapabilities, DeviceCapabilities, Medium},
     socket::{TcpSocket, TcpSocketBuffer, TcpState},
     storage::RingBuffer,
     time::{Duration, Instant},
@@ -198,6 +198,14 @@ impl TcpTun {
         capabilities.medium = Medium::Ip;
         capabilities.max_transmission_unit = mtu as usize;
 
+        // Disable Checksum verification for improving performance.
+        capabilities.checksum = ChecksumCapabilities::default();
+        capabilities.checksum.ipv4 = Checksum::Tx;
+        capabilities.checksum.tcp = Checksum::Tx;
+        capabilities.checksum.udp = Checksum::Tx;
+        capabilities.checksum.icmpv4 = Checksum::Tx;
+        capabilities.checksum.icmpv6 = Checksum::Tx;
+
         let (virt, iface_rx, iface_tx) = VirtTunDevice::new(capabilities);
 
         let iface_builder = InterfaceBuilder::new(virt, vec![]);