41 lines
1.1 KiB
Go
41 lines
1.1 KiB
Go
package redir
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import (
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"encoding/binary"
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"net"
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"net/netip"
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"os"
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"syscall"
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"github.com/sagernet/sing/common"
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"github.com/sagernet/sing/common/control"
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M "github.com/sagernet/sing/common/metadata"
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)
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func GetOriginalDestination(conn net.Conn) (destination netip.AddrPort, err error) {
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syscallConn, ok := common.Cast[syscall.Conn](conn)
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if !ok {
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return netip.AddrPort{}, os.ErrInvalid
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}
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err = control.Conn(syscallConn, func(fd uintptr) error {
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const SO_ORIGINAL_DST = 80
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if conn.RemoteAddr().(*net.TCPAddr).IP.To4() != nil {
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raw, err := syscall.GetsockoptIPv6Mreq(int(fd), syscall.IPPROTO_IP, SO_ORIGINAL_DST)
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if err != nil {
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return err
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}
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destination = netip.AddrPortFrom(M.AddrFromIP(raw.Multiaddr[4:8]), uint16(raw.Multiaddr[2])<<8+uint16(raw.Multiaddr[3]))
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} else {
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raw, err := syscall.GetsockoptIPv6MTUInfo(int(fd), syscall.IPPROTO_IPV6, SO_ORIGINAL_DST)
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if err != nil {
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return err
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}
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var port [2]byte
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binary.BigEndian.PutUint16(port[:], raw.Addr.Port)
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destination = netip.AddrPortFrom(M.AddrFromIP(raw.Addr.Addr[:]), binary.LittleEndian.Uint16(port[:]))
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}
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return nil
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})
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return
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}
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