mirror of https://github.com/XTLS/Xray-core
53 lines
1.4 KiB
Go
53 lines
1.4 KiB
Go
//go:build linux
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// +build linux
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package tcp
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import (
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"context"
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"syscall"
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"unsafe"
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"github.com/xtls/xray-core/common/errors"
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"github.com/xtls/xray-core/common/net"
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"github.com/xtls/xray-core/transport/internet/stat"
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)
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const SO_ORIGINAL_DST = 80
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func GetOriginalDestination(conn stat.Connection) (net.Destination, error) {
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sysrawconn, f := conn.(syscall.Conn)
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if !f {
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return net.Destination{}, errors.New("unable to get syscall.Conn")
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}
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rawConn, err := sysrawconn.SyscallConn()
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if err != nil {
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return net.Destination{}, errors.New("failed to get sys fd").Base(err)
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}
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var dest net.Destination
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err = rawConn.Control(func(fd uintptr) {
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level := syscall.IPPROTO_IP
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if conn.RemoteAddr().String()[0] == '[' {
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level = syscall.IPPROTO_IPV6
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}
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addr, err := syscall.GetsockoptIPv6MTUInfo(int(fd), level, SO_ORIGINAL_DST)
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if err != nil {
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errors.LogInfoInner(context.Background(), err, "failed to call getsockopt")
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return
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}
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ip := (*[4]byte)(unsafe.Pointer(&addr.Addr.Flowinfo))[:4]
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if level == syscall.IPPROTO_IPV6 {
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ip = addr.Addr.Addr[:]
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}
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port := (*[2]byte)(unsafe.Pointer(&addr.Addr.Port))[:2]
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dest = net.TCPDestination(net.IPAddress(ip), net.PortFromBytes(port))
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})
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if err != nil {
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return net.Destination{}, errors.New("failed to control connection").Base(err)
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}
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if !dest.IsValid() {
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return net.Destination{}, errors.New("failed to call getsockopt")
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}
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return dest, nil
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}
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