Vender add

vender/github.com/ccding/go-stun/stun/net.go

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+// Copyright 2016, Cong Ding. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//   http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+// Author: Cong Ding <dinggnu@gmail.com>
+
+package stun
+
+import (
+	"bytes"
+	"encoding/hex"
+	"errors"
+	"net"
+	"time"
+)
+
+const (
+	numRetransmit  = 9
+	defaultTimeout = 100
+	maxTimeout     = 1600
+	maxPacketSize  = 1024
+)
+
+func (c *Client) sendBindingReq(conn net.PacketConn, addr net.Addr, changeIP bool, changePort bool) (*response, error) {
+	// Construct packet.
+	pkt, err := newPacket()
+	if err != nil {
+		return nil, err
+	}
+	pkt.types = typeBindingRequest
+	attribute := newSoftwareAttribute(c.softwareName)
+	pkt.addAttribute(*attribute)
+	if changeIP || changePort {
+		attribute = newChangeReqAttribute(changeIP, changePort)
+		pkt.addAttribute(*attribute)
+	}
+	// length of fingerprint attribute must be included into crc,
+	// so we add it before calculating crc, then subtract it after calculating crc.
+	pkt.length += 8
+	attribute = newFingerprintAttribute(pkt)
+	pkt.length -= 8
+	pkt.addAttribute(*attribute)
+	// Send packet.
+	return c.send(pkt, conn, addr)
+}
+
+// RFC 3489: Clients SHOULD retransmit the request starting with an interval
+// of 100ms, doubling every retransmit until the interval reaches 1.6s.
+// Retransmissions continue with intervals of 1.6s until a response is
+// received, or a total of 9 requests have been sent.
+func (c *Client) send(pkt *packet, conn net.PacketConn, addr net.Addr) (*response, error) {
+	c.logger.Info("\n" + hex.Dump(pkt.bytes()))
+	timeout := defaultTimeout
+	packetBytes := make([]byte, maxPacketSize)
+	for i := 0; i < numRetransmit; i++ {
+		// Send packet to the server.
+		length, err := conn.WriteTo(pkt.bytes(), addr)
+		if err != nil {
+			return nil, err
+		}
+		if length != len(pkt.bytes()) {
+			return nil, errors.New("Error in sending data.")
+		}
+		err = conn.SetReadDeadline(time.Now().Add(time.Duration(timeout) * time.Millisecond))
+		if err != nil {
+			return nil, err
+		}
+		if timeout < maxTimeout {
+			timeout *= 2
+		}
+		for {
+			// Read from the port.
+			length, raddr, err := conn.ReadFrom(packetBytes)
+			if err != nil {
+				if nerr, ok := err.(net.Error); ok && nerr.Timeout() {
+					break
+				}
+				return nil, err
+			}
+			p, err := newPacketFromBytes(packetBytes[0:length])
+			if err != nil {
+				return nil, err
+			}
+			// If transId mismatches, keep reading until get a
+			// matched packet or timeout.
+			if !bytes.Equal(pkt.transID, p.transID) {
+				continue
+			}
+			c.logger.Info("\n" + hex.Dump(packetBytes[0:length]))
+			resp := newResponse(p, conn)
+			resp.serverAddr = newHostFromStr(raddr.String())
+			return resp, err
+		}
+	}
+	return nil, nil
+}