59 lines
978 B
Go
59 lines
978 B
Go
package relay
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import (
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"encoding/binary"
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"errors"
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"io"
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"math"
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"net"
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)
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type packetConn struct {
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net.Conn
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}
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func UDPTunConn(conn net.Conn) net.Conn {
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return &packetConn{
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Conn: conn,
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}
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}
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func (c *packetConn) Read(b []byte) (n int, err error) {
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var bb [2]byte
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_, err = io.ReadFull(c.Conn, bb[:])
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if err != nil {
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return
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}
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dlen := int(binary.BigEndian.Uint16(bb[:]))
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if len(b) >= dlen {
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return io.ReadFull(c.Conn, b[:dlen])
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}
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buf := make([]byte, dlen)
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_, err = io.ReadFull(c.Conn, buf)
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n = copy(b, buf)
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return
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}
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func (c *packetConn) ReadFrom(b []byte) (n int, addr net.Addr, err error) {
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n, err = c.Read(b)
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addr = c.Conn.RemoteAddr()
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return
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}
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func (c *packetConn) Write(b []byte) (n int, err error) {
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if len(b) > math.MaxUint16 {
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err = errors.New("write: data maximum exceeded")
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return
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}
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var bb [2]byte
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binary.BigEndian.PutUint16(bb[:2], uint16(len(b)))
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_, err = c.Conn.Write(bb[:])
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if err != nil {
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return
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}
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return c.Conn.Write(b)
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}
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