github.com/eagleql/xray-core@v1.4.4/proxy/dokodemo/fakeudp_linux.go (about)

     1  // +build linux
     2  
     3  package dokodemo
     4  
     5  import (
     6  	"fmt"
     7  	"net"
     8  	"os"
     9  	"syscall"
    10  
    11  	"golang.org/x/sys/unix"
    12  )
    13  
    14  func FakeUDP(addr *net.UDPAddr, mark int) (net.PacketConn, error) {
    15  	var af int
    16  	var sockaddr syscall.Sockaddr
    17  
    18  	if len(addr.IP) == 4 {
    19  		af = syscall.AF_INET
    20  		sockaddr = &syscall.SockaddrInet4{Port: addr.Port}
    21  		copy(sockaddr.(*syscall.SockaddrInet4).Addr[:], addr.IP)
    22  	} else {
    23  		af = syscall.AF_INET6
    24  		sockaddr = &syscall.SockaddrInet6{Port: addr.Port}
    25  		copy(sockaddr.(*syscall.SockaddrInet6).Addr[:], addr.IP)
    26  	}
    27  
    28  	var fd int
    29  	var err error
    30  
    31  	if fd, err = syscall.Socket(af, syscall.SOCK_DGRAM, 0); err != nil {
    32  		return nil, &net.OpError{Op: "fake", Err: fmt.Errorf("socket open: %s", err)}
    33  	}
    34  
    35  	if mark != 0 {
    36  		if err = syscall.SetsockoptInt(fd, syscall.SOL_SOCKET, syscall.SO_MARK, mark); err != nil {
    37  			syscall.Close(fd)
    38  			return nil, &net.OpError{Op: "fake", Err: fmt.Errorf("set socket option: SO_MARK: %s", err)}
    39  		}
    40  	}
    41  
    42  	if err = syscall.SetsockoptInt(fd, syscall.SOL_IP, syscall.IP_TRANSPARENT, 1); err != nil {
    43  		syscall.Close(fd)
    44  		return nil, &net.OpError{Op: "fake", Err: fmt.Errorf("set socket option: IP_TRANSPARENT: %s", err)}
    45  	}
    46  
    47  	syscall.SetsockoptInt(fd, syscall.SOL_SOCKET, syscall.SO_REUSEADDR, 1)
    48  
    49  	syscall.SetsockoptInt(fd, syscall.SOL_SOCKET, unix.SO_REUSEPORT, 1)
    50  
    51  	if err = syscall.Bind(fd, sockaddr); err != nil {
    52  		syscall.Close(fd)
    53  		return nil, &net.OpError{Op: "fake", Err: fmt.Errorf("socket bind: %s", err)}
    54  	}
    55  
    56  	fdFile := os.NewFile(uintptr(fd), fmt.Sprintf("net-udp-fake-%s", addr.String()))
    57  	defer fdFile.Close()
    58  
    59  	packetConn, err := net.FilePacketConn(fdFile)
    60  	if err != nil {
    61  		syscall.Close(fd)
    62  		return nil, &net.OpError{Op: "fake", Err: fmt.Errorf("convert file descriptor to connection: %s", err)}
    63  	}
    64  
    65  	return packetConn, nil
    66  }