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sockopt_linux.go
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sockopt_linux.go
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//go:build linux
// +build linux
package tcp
import (
"syscall"
"github.com/v2fly/v2ray-core/v5/common/net"
"github.com/v2fly/v2ray-core/v5/transport/internet"
)
const SO_ORIGINAL_DST = 80 // nolint: revive,stylecheck
func GetOriginalDestination(conn internet.Connection) (net.Destination, error) {
sysrawconn, f := conn.(syscall.Conn)
if !f {
return net.Destination{}, newError("unable to get syscall.Conn")
}
rawConn, err := sysrawconn.SyscallConn()
if err != nil {
return net.Destination{}, newError("failed to get sys fd").Base(err)
}
var dest net.Destination
err = rawConn.Control(func(fd uintptr) {
var remoteIP net.IP
switch addr := conn.RemoteAddr().(type) {
case *net.TCPAddr:
remoteIP = addr.IP
case *net.UDPAddr:
remoteIP = addr.IP
default:
newError("failed to call getsockopt").WriteToLog()
return
}
if remoteIP.To4() != nil {
// ipv4
addr, err := syscall.GetsockoptIPv6Mreq(int(fd), syscall.IPPROTO_IP, SO_ORIGINAL_DST)
if err != nil {
newError("failed to call getsockopt").Base(err).WriteToLog()
return
}
ip := net.IPAddress(addr.Multiaddr[4:8])
port := uint16(addr.Multiaddr[2])<<8 + uint16(addr.Multiaddr[3])
dest = net.TCPDestination(ip, net.Port(port))
} else {
// ipv6
addr, err := syscall.GetsockoptIPv6MTUInfo(int(fd), syscall.IPPROTO_IPV6, SO_ORIGINAL_DST)
if err != nil {
newError("failed to call getsockopt").Base(err).WriteToLog()
return
}
ip := net.IPAddress(addr.Addr.Addr[:])
port := net.PortFromBytes([]byte{byte(addr.Addr.Port), byte(addr.Addr.Port >> 8)})
dest = net.TCPDestination(ip, port)
}
})
if err != nil {
return net.Destination{}, newError("failed to control connection").Base(err)
}
if !dest.IsValid() {
return net.Destination{}, newError("failed to call getsockopt")
}
return dest, nil
}