mirror of
https://github.com/luscis/openlan.git
synced 2025-10-07 01:22:51 +08:00
52 lines
1.5 KiB
Go
52 lines
1.5 KiB
Go
package pfutil
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import (
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"net"
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"syscall"
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"unsafe"
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)
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func NatLookup(c *net.TCPConn) (*net.TCPAddr, error) {
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const (
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PF_INOUT = 0
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PF_IN = 1
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PF_OUT = 2
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IOC_OUT = 0x40000000
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IOC_IN = 0x80000000
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IOC_INOUT = IOC_IN | IOC_OUT
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IOCPARM_MASK = 0x1FFF
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LEN = 4*16 + 4*4 + 4*1
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// #define _IOC(inout,group,num,len) (inout | ((len & IOCPARM_MASK) << 16) | ((group) << 8) | (num))
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// #define _IOWR(g,n,t) _IOC(IOC_INOUT, (g), (n), sizeof(t))
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// #define DIOCNATLOOK _IOWR('D', 23, struct pfioc_natlook)
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DIOCNATLOOK = IOC_INOUT | ((LEN & IOCPARM_MASK) << 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: PF_OUT,
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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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var addr net.TCPAddr
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addr.IP = nl.rdaddr[:4]
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addr.Port = int(nl.rdxport[0])<<8 | int(nl.rdxport[1])
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return &addr, nil
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}
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