[tunnel] Toggle cksum recalc in dev

Author: dilyevsky

cmd/tunnelproxy/main.go

@@ -49,6 +49,7 @@ var (
 jwksURLs = flag.String("jwks_urls", "", "Comma-separated URLs of the JWKS endpoints.")
 
 extIPv6SubnetSize = flag.Int("ext_ipv6_subnet_size", 64, "IPv6 subnet size.")
+cksumRecalc = flag.Bool("cksum_recalc", false, "Recalculate checksum.")
 )
 
 func main() {
@@ -118,9 +119,11 @@ func main() {
 
 log.Infof("External IPv6 prefix: %s", extIPv6Prefix.String())
 
-r, err := router.NewNetlinkRouter(
+rOpts := []router.Option{
 router.WithExternalIPv6Prefix(extIPv6Prefix),
-)
+router.WithChecksumRecalculation(*cksumRecalc),
+}
+r, err := router.NewNetlinkRouter(rOpts...)
 if err != nil {
 log.Fatalf("Failed to create netlink router: %v", err)
 }

pkg/drivers/tunnelproxy_docker.go

@@ -117,6 +117,7 @@ func (d *TunnelProxyDockerDriver) Start(
 cmd.Args = append(cmd.Args, []string{
 "--apiserver_addr=" + apiserverAddr,
 fmt.Sprintf("--jwks_urls=http://%s:%d%s", apiserverHost, 8444, token.JWKSURI),
+"--cksum_recalc=true",
 }...)
 if build.IsDev() {
 cmd.Args = append(cmd.Args, "--dev")

pkg/tunnel/connection/splice.go

@@ -60,6 +60,7 @@ func defaultSpliceConfig() *SpliceConfig {
 }
 }
 
+// Splice starts the TUN <-> Connection splice operation.
 func Splice(tunDev tun.Device, conn Connection, opts ...SpliceOption) error {
 config := defaultSpliceConfig()
 for _, opt := range opts {

pkg/tunnel/router/netstack.go

@@ -24,13 +24,17 @@ var (
 // NetstackRouter implements Router using a userspace network stack.
 // This router can be used for both client and server sides.
 type NetstackRouter struct {
-tunDev *netstack.TunDevice
-mux *connection.MuxedConn
-proxy *socksproxy.ProxyServer
+tunDev *netstack.TunDevice
+mux *connection.MuxedConn
+
+proxy *socksproxy.ProxyServer
+
 localAddresses []netip.Prefix
 resolveConf *network.ResolveConfig
 socksListenAddr string
-closeOnce sync.Once
+cksumRecalc bool
+
+closeOnce sync.Once
 }
 
 // NewNetstackRouter creates a new netstack-based tunnel router.
@@ -52,12 +56,15 @@ func NewNetstackRouter(opts ...Option) (*NetstackRouter, error) {
 )
 
 return &NetstackRouter{
-tunDev: tunDev,
-mux: connection.NewMuxedConn(),
-proxy: proxy,
+tunDev: tunDev,
+mux: connection.NewMuxedConn(),
+
+proxy: proxy,
+
 localAddresses: options.localAddresses,
 resolveConf: options.resolveConf,
 socksListenAddr: options.socksListenAddr,
+cksumRecalc: options.cksumRecalc,
 }, nil
 }
 
@@ -75,7 +82,11 @@ func (r *NetstackRouter) Start(ctx context.Context) error {
 })
 
 g.Go(func() error {
-return connection.Splice(r.tunDev, r.mux, connection.WithChecksumRecalculation())
+var opts []connection.SpliceOption
+if r.cksumRecalc {
+opts = append(opts, connection.WithChecksumRecalculation())
+}
+return connection.Splice(r.tunDev, r.mux, opts...)
 })
 
 _, socksListenPortStr, err := net.SplitHostPort(r.socksListenAddr)

pkg/tunnel/router/options.go

@@ -17,13 +17,15 @@ type routerOptions struct {
 extIfaceName string
 tunIfaceName string
 socksListenAddr string
+cksumRecalc bool
 }
 
 func defaultOptions() *routerOptions {
 return &routerOptions{
 extIfaceName: "eth0",
 tunIfaceName: "tun0",
 socksListenAddr: "localhost:1080",
+cksumRecalc: false,
 }
 }
 
@@ -78,3 +80,11 @@ func WithSocksListenAddr(addr string) Option {
 o.socksListenAddr = addr
 }
 }
+
+// WithChecksumRecalculation enables or disables checksum recalculation for the netstack router.
+// Only valid for netstack routers.
+func WithChecksumRecalculation(enable bool) Option {
+return func(o *routerOptions) {
+o.cksumRecalc = enable
+}
+}

pkg/tunnel/router/server_netlink_linux.go

@@ -33,6 +33,8 @@ type NetlinkRouter struct {
 extLink netlink.Link
 extIPv6Prefix netip.Prefix
 
+cksumRecalc bool
+
 tunDev tun.Device
 tunLink netlink.Link
 
@@ -114,6 +116,8 @@ func NewNetlinkRouter(opts ...Option) (*NetlinkRouter, error) {
 extLink: extLink,
 extIPv6Prefix: options.extIPv6Prefix,
 
+cksumRecalc: options.cksumRecalc,
+
 tunDev: tunDev,
 tunLink: tunLink,
 
@@ -200,7 +204,11 @@ func (r *NetlinkRouter) Start(ctx context.Context) error {
 
 // Start the splicing operation
 g.Go(func() error {
-return connection.Splice(r.tunDev, r.mux)
+var opts []connection.SpliceOption
+if r.cksumRecalc {
+opts = append(opts, connection.WithChecksumRecalculation())
+}
+return connection.Splice(r.tunDev, r.mux, opts...)
 })
 
 return g.Wait()