Add handshake interface support for gVisor UDP

stack_gvisor_err.go

@@ -0,0 +1,50 @@
+//go:build with_gvisor
+
+package tun
+
+import (
+	"net"
+
+	"github.com/sagernet/gvisor/pkg/tcpip"
+	"github.com/sagernet/gvisor/pkg/tcpip/adapters/gonet"
+	E "github.com/sagernet/sing/common/exceptions"
+)
+
+type gTCPConn struct {
+	*gonet.TCPConn
+}
+
+func (c *gTCPConn) Upstream() any {
+	return c.TCPConn
+}
+
+func (c *gTCPConn) Write(b []byte) (n int, err error) {
+	n, err = c.TCPConn.Write(b)
+	if err == nil {
+		return
+	}
+	err = wrapError(err)
+	return
+}
+
+func wrapStackError(err tcpip.Error) error {
+	switch err.(type) {
+	case *tcpip.ErrClosedForSend,
+		*tcpip.ErrClosedForReceive,
+		*tcpip.ErrAborted:
+		return net.ErrClosed
+	}
+	return E.New(err.String())
+}
+
+func wrapError(err error) error {
+	if opErr, isOpErr := err.(*net.OpError); isOpErr {
+		switch opErr.Err.Error() {
+		case "endpoint is closed for send",
+			"endpoint is closed for receive",
+			"operation aborted":
+			return net.ErrClosed
+		}
+	}
+	return err
+}