sing-box/common/redir/redir_darwin.go
2022-08-31 14:21:37 +08:00

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
}