60 lines
1.3 KiB
Go
60 lines
1.3 KiB
Go
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// Copyright 2016 Mikio Hara. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// +build darwin dragonfly freebsd openbsd
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package tcp
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import (
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"net"
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"os"
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"syscall"
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"unsafe"
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)
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func (*Conn) originalDst(la, ra *net.TCPAddr) (net.Addr, error) {
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f, err := os.Open("/dev/pf")
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if err != nil {
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return nil, err
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}
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defer f.Close()
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fd := f.Fd()
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b := make([]byte, sizeofPfiocNatlook)
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nl := (*pfiocNatlook)(unsafe.Pointer(&b[0]))
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if ra.IP.To4() != nil {
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copy(nl.Saddr[:net.IPv4len], ra.IP.To4())
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copy(nl.Daddr[:net.IPv4len], la.IP.To4())
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nl.Af = sysAF_INET
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}
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if ra.IP.To16() != nil && ra.IP.To4() == nil {
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copy(nl.Saddr[:], ra.IP)
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copy(nl.Daddr[:], la.IP)
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nl.Af = sysAF_INET6
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}
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nl.setPort(ra.Port, la.Port)
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nl.Proto = ianaProtocolTCP
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ioc := uintptr(sysDIOCNATLOOK)
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for _, dir := range []byte{sysPF_OUT, sysPF_IN} {
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nl.Direction = dir
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err = ioctl(fd, int(ioc), b)
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if err == nil || err != syscall.ENOENT {
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break
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}
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}
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if err != nil {
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return nil, os.NewSyscallError("ioctl", err)
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}
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od := new(net.TCPAddr)
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od.Port = nl.rdPort()
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switch nl.Af {
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case sysAF_INET:
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od.IP = make(net.IP, net.IPv4len)
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copy(od.IP, nl.Rdaddr[:net.IPv4len])
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case sysAF_INET6:
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od.IP = make(net.IP, net.IPv6len)
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copy(od.IP, nl.Rdaddr[:])
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}
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return od, nil
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}
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