59 lines
1.6 KiB
Go
59 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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"syscall"
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"unsafe"
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"github.com/riobard/go-shadowsocks2/socks"
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)
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func parserPacket(c net.Conn) (socks.Addr, error) {
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const (
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PfInout = 0
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PfIn = 1
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PfOut = 2
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IOCOut = 0x40000000
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IOCIn = 0x80000000
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IOCInOut = IOCIn | IOCOut
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IOCPARMMask = 0x1FFF
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LEN = 4*16 + 4*4 + 4*1
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// #define _IOC(inout,group,num,len) (inout | ((len & IOCPARMMask) << 16) | ((group) << 8) | (num))
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// #define _IOWR(g,n,t) _IOC(IOCInOut, (g), (n), sizeof(t))
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// #define DIOCNATLOOK _IOWR('D', 23, struct pfioc_natlook)
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DIOCNATLOOK = IOCInOut | ((LEN & IOCPARMMask) << 16) | ('D' << 8) | 23
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)
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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 nil, err
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}
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defer syscall.Close(fd)
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nl := struct { // struct pfioc_natlook
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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: PfOut,
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}
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saddr := c.RemoteAddr().(*net.TCPAddr)
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daddr := c.LocalAddr().(*net.TCPAddr)
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copy(nl.saddr[:], saddr.IP)
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copy(nl.daddr[:], daddr.IP)
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nl.sxport[0], nl.sxport[1] = byte(saddr.Port>>8), byte(saddr.Port)
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nl.dxport[0], nl.dxport[1] = byte(daddr.Port>>8), byte(daddr.Port)
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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 nil, errno
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}
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addr := make([]byte, 1+net.IPv4len+2)
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addr[0] = socks.AtypIPv4
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copy(addr[1:1+net.IPv4len], nl.rdaddr[:4])
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copy(addr[1+net.IPv4len:], nl.rdxport[:2])
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return addr, nil
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}
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