65 lines
1.6 KiB
Go
65 lines
1.6 KiB
Go
package redir
|
|
|
|
import (
|
|
"net"
|
|
"net/netip"
|
|
"syscall"
|
|
"unsafe"
|
|
|
|
M "github.com/sagernet/sing/common/metadata"
|
|
)
|
|
|
|
const (
|
|
PF_OUT = 0x2
|
|
DIOCNATLOOK = 0xc0544417
|
|
)
|
|
|
|
func GetOriginalDestination(conn net.Conn) (destination netip.AddrPort, err error) {
|
|
fd, err := syscall.Open("/dev/pf", 0, syscall.O_RDONLY)
|
|
if err != nil {
|
|
return netip.AddrPort{}, err
|
|
}
|
|
defer syscall.Close(fd)
|
|
nl := struct {
|
|
saddr, daddr, rsaddr, rdaddr [16]byte
|
|
sxport, dxport, rsxport, rdxport [4]byte
|
|
af, proto, protoVariant, direction uint8
|
|
}{
|
|
af: syscall.AF_INET,
|
|
proto: syscall.IPPROTO_TCP,
|
|
direction: PF_OUT,
|
|
}
|
|
la := conn.LocalAddr().(*net.TCPAddr)
|
|
ra := conn.RemoteAddr().(*net.TCPAddr)
|
|
raIP, laIP := ra.IP, la.IP
|
|
raPort, laPort := ra.Port, la.Port
|
|
switch {
|
|
case raIP.To4() != nil:
|
|
copy(nl.saddr[:net.IPv4len], raIP.To4())
|
|
copy(nl.daddr[:net.IPv4len], laIP.To4())
|
|
nl.af = syscall.AF_INET
|
|
default:
|
|
copy(nl.saddr[:], raIP.To16())
|
|
copy(nl.daddr[:], laIP.To16())
|
|
nl.af = syscall.AF_INET6
|
|
}
|
|
nl.sxport[0], nl.sxport[1] = byte(raPort>>8), byte(raPort)
|
|
nl.dxport[0], nl.dxport[1] = byte(laPort>>8), byte(laPort)
|
|
if _, _, errno := syscall.Syscall(syscall.SYS_IOCTL, uintptr(fd), DIOCNATLOOK, uintptr(unsafe.Pointer(&nl))); errno != 0 {
|
|
return netip.AddrPort{}, errno
|
|
}
|
|
|
|
var ip net.IP
|
|
switch nl.af {
|
|
case syscall.AF_INET:
|
|
ip = make(net.IP, net.IPv4len)
|
|
copy(ip, nl.rdaddr[:net.IPv4len])
|
|
case syscall.AF_INET6:
|
|
ip = make(net.IP, net.IPv6len)
|
|
copy(ip, nl.rdaddr[:])
|
|
}
|
|
port := uint16(nl.rdxport[0])<<8 | uint16(nl.rdxport[1])
|
|
destination = netip.AddrPortFrom(M.AddrFromIP(ip), port)
|
|
return
|
|
}
|