103 lines
2.9 KiB
Go
103 lines
2.9 KiB
Go
// Copyright 2016, Cong Ding. All rights reserved.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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//
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// Author: Cong Ding <dinggnu@gmail.com>
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package stun
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import (
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"bytes"
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"encoding/hex"
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"errors"
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"net"
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"time"
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)
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const (
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numRetransmit = 9
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defaultTimeout = 100
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maxTimeout = 1600
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maxPacketSize = 1024
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)
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func (c *Client) sendBindingReq(conn net.PacketConn, addr net.Addr, changeIP bool, changePort bool) (*response, error) {
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// Construct packet.
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pkt, err := newPacket()
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if err != nil {
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return nil, err
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}
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pkt.types = typeBindingRequest
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attribute := newSoftwareAttribute(c.softwareName)
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pkt.addAttribute(*attribute)
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if changeIP || changePort {
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attribute = newChangeReqAttribute(changeIP, changePort)
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pkt.addAttribute(*attribute)
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}
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attribute = newFingerprintAttribute(pkt)
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pkt.addAttribute(*attribute)
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// Send packet.
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return c.send(pkt, conn, addr)
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}
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// RFC 3489: Clients SHOULD retransmit the request starting with an interval
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// of 100ms, doubling every retransmit until the interval reaches 1.6s.
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// Retransmissions continue with intervals of 1.6s until a response is
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// received, or a total of 9 requests have been sent.
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func (c *Client) send(pkt *packet, conn net.PacketConn, addr net.Addr) (*response, error) {
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c.logger.Info("\n" + hex.Dump(pkt.bytes()))
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timeout := defaultTimeout
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packetBytes := make([]byte, maxPacketSize)
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for i := 0; i < numRetransmit; i++ {
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// Send packet to the server.
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length, err := conn.WriteTo(pkt.bytes(), addr)
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if err != nil {
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return nil, err
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}
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if length != len(pkt.bytes()) {
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return nil, errors.New("Error in sending data.")
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}
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err = conn.SetReadDeadline(time.Now().Add(time.Duration(timeout) * time.Millisecond))
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if err != nil {
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return nil, err
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}
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if timeout < maxTimeout {
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timeout *= 2
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}
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for {
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// Read from the port.
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length, raddr, err := conn.ReadFrom(packetBytes)
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if err != nil {
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if nerr, ok := err.(net.Error); ok && nerr.Timeout() {
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break
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}
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return nil, err
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}
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p, err := newPacketFromBytes(packetBytes[0:length])
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if err != nil {
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return nil, err
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}
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// If transId mismatches, keep reading until get a
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// matched packet or timeout.
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if !bytes.Equal(pkt.transID, p.transID) {
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continue
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}
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c.logger.Info("\n" + hex.Dump(packetBytes[0:length]))
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resp := newResponse(p, conn)
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resp.serverAddr = newHostFromStr(raddr.String())
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return resp, err
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}
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}
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return nil, nil
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}
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