mirror of
https://github.com/SagerNet/sing-box.git
synced 2024-11-30 04:21:29 +00:00
65 lines
1.6 KiB
Go
65 lines
1.6 KiB
Go
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package redir
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import (
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"net"
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"net/netip"
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"syscall"
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"unsafe"
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M "github.com/sagernet/sing/common/metadata"
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)
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const (
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PF_OUT = 0x2
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DIOCNATLOOK = 0xc0544417
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)
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func GetOriginalDestination(conn net.Conn) (destination netip.AddrPort, err error) {
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fd, err := syscall.Open("/dev/pf", 0, syscall.O_RDONLY)
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if err != nil {
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return netip.AddrPort{}, err
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}
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defer syscall.Close(fd)
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nl := struct {
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saddr, daddr, rsaddr, rdaddr [16]byte
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sxport, dxport, rsxport, rdxport [4]byte
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af, proto, protoVariant, direction uint8
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}{
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af: syscall.AF_INET,
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proto: syscall.IPPROTO_TCP,
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direction: PF_OUT,
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}
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la := conn.LocalAddr().(*net.TCPAddr)
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ra := conn.RemoteAddr().(*net.TCPAddr)
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raIP, laIP := ra.IP, la.IP
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raPort, laPort := ra.Port, la.Port
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switch {
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case raIP.To4() != nil:
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copy(nl.saddr[:net.IPv4len], raIP.To4())
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copy(nl.daddr[:net.IPv4len], laIP.To4())
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nl.af = syscall.AF_INET
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default:
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copy(nl.saddr[:], raIP.To16())
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copy(nl.daddr[:], laIP.To16())
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nl.af = syscall.AF_INET6
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}
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nl.sxport[0], nl.sxport[1] = byte(raPort>>8), byte(raPort)
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nl.dxport[0], nl.dxport[1] = byte(laPort>>8), byte(laPort)
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if _, _, errno := syscall.Syscall(syscall.SYS_IOCTL, uintptr(fd), DIOCNATLOOK, uintptr(unsafe.Pointer(&nl))); errno != 0 {
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return netip.AddrPort{}, errno
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}
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var ip net.IP
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switch nl.af {
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case syscall.AF_INET:
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ip = make(net.IP, net.IPv4len)
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copy(ip, nl.rdaddr[:net.IPv4len])
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case syscall.AF_INET6:
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ip = make(net.IP, net.IPv6len)
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copy(ip, nl.rdaddr[:])
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}
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port := uint16(nl.rdxport[0])<<8 | uint16(nl.rdxport[1])
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destination = netip.AddrPortFrom(M.AddrFromIP(ip), port)
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return
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}
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