P2P网络通讯程序(c#)

http://www.cnblogs.com/windsea123/archive/2009/03/26/1422677.html

在网上看了很多程序（QQ、Azureus、Ants、PPStream）都实现了p2p，以前觉得技术很高深。通过这段时间的学习才发现，单纯的实现p2p在局域网通讯很容易，但是要实现外网穿透(NAT)感觉很困难。最近看了Azureus和emule源码，分别是JAVA和C++版，本人对这两门语言都不熟悉，看起来很吃力。最后只好根据VC++实现的P2PDemo程序进行了改版，根据设计思路用c#写了一个Demo出来。通过测试，多个客户端在局域网能脱离服务端实现端到端工作。外网的情况要通过路由器，看了Azureus要实现uPnp进行端口映射，在CodeProject上下载了一个uPnp源码看，测试结果没有启用uPnp路由器。结果现在郁闷了，不知道下一步怎么测试，是不是用upnp实现了端口自动映射成功就能实现象QQ那样通讯。

下面是程序说明：

1、公共类

公共类主要定义一些包结构



a、Packet.cs 



[Serializable()]

    public abstract class Packet

    {

        /// <summary>

        /// 命令类型

        /// </summary>

        /// <returns></returns>
        public virtual int GetCommandType()

        {

            return -1;

        }

        /// <summary>

        /// 用户名

        /// </summary>
        public string UserName

        {

            get;

            set;

        }

        public Packet()

        { }

        public Packet(string username)

        {

            this.UserName = username;

        }

    }

b、MassTextPacket.cs  --分片传输类



 [Serializable()]

    public class MassTextPacket:TextPacket

    {

        private int seqID;

        /// <summary>

        /// 包序列

        /// </summary>
        public int SeqID

        {

            get { return seqID; }

            set { seqID = value; }

        }

        private int seqCount;

        /// <summary>

        /// 包数量

        /// </summary>
        public int SeqCount

        {

            get { return seqCount; }

            set { seqCount = value; }

        }

        private int _CLSD;

        public int CLSD

        {

            get { return _CLSD; }

            set { _CLSD = value; }

        }

    }

 

2、客户端

a、消息传送时进行p2p通讯



        private bool SendMessageTo(string toUserName, Packet packet)

        {

            PeerEntity toUser = userList.Single(c => c.UserName == toUserName);

            if (toUser == null)

            {

                return false;

            }

            ReceivedACK = false;

            for (int i=0; i<MAXRETRY; i++)            

            {      

                // 如果对方P2P地址不为0，就试图以它为目的地址发送数据，

                // 如果发送失败，则认为此P2P地址无效
                if (toUser.P2PAddress != null && toUser.P2PAddress.Port != 0)

                {

                    if (packet.GetType() == typeof(TextPacket))

                    {

                        TextPacket msgPacket = new TextPacket(toUserName, (packet as TextPacket).Message);

                        byte[] buffer = UtilityHelper.Serialize(msgPacket);

                        if (buffer.Length > MAXBUFFERSIZE)

                        {

                         

                            MassTextPacket mtp = new MassTextPacket();

                            mtp.SeqID = 0;

                            mtp.SeqCount = (int)System.Math.Ceiling(buffer.Length / (decimal)MAXBUFFERSIZE);

                            mtp.CLSD = mtp.GetHashCode();

                            

                            long pos = 0;

                            long count = buffer.Length < MAXBUFFERSIZE ? buffer.Length : MAXBUFFERSIZE;

                            while (pos < buffer.Length && pos > 0)

                            {

                                byte[] bytes = new byte[count];                          ;

                                for (int k = 0; k < count; k++)

                                    bytes[k] = buffer[pos + k];

                                //数据组包
                                mtp.SeqID = mtp.SeqID + 1;

                                mtp.Message = Convert.ToBase64String(bytes);

                                //发送数据
                                byte[] buf = UtilityHelper.Serialize(mtp);

                                client.Send(buf, buf.Length, toUser.P2PAddress);

                                Thread.Sleep(100);

                            }

                        }

                        else

                            client.Send(buffer, buffer.Length, toUser.P2PAddress);

                    }

                    else if (packet.GetType() == typeof(FileStreamPacket))

                    {

                        FileStreamPacket fsp = packet as FileStreamPacket;

                        System.IO.FileStream fs = new System.IO.FileStream(fsp.FileName, System.IO.FileMode.Open, System.IO.FileAccess.Read, FileShare.Read);

                       handle1.Reset();

                        fsp.SeqID = 0;

                        fsp.SeqCount = (int)System.Math.Ceiling(fs.Length / (decimal)MAXBUFFERSIZE);

                        fsp.CLSD = fsp.GetHashCode();

                        long pos = 0;

                        long count = fs.Length < MAXBUFFERSIZE ? fs.Length : MAXBUFFERSIZE;

                        while (pos < fs.Length && count > 0)

                        {

                            byte[] buffer = new byte[count];

                            fs.Seek(pos, SeekOrigin.Begin);

                            fs.Read(buffer, 0, (int)count);

                            pos += count;

                            count = pos + MAXBUFFERSIZE < fs.Length ? MAXBUFFERSIZE : fs.Length - pos;

                            //数据组包
                            fsp.SeqID = fsp.SeqID + 1;

                            fsp.Message = Convert.ToBase64String(buffer);

                            //发送数据
                            byte[] buf = UtilityHelper.Serialize(fsp);

                            client.Send(buf, buf.Length, toUser.P2PAddress);

                            Thread.Sleep(300);

                        }

                        handle1.Set();

                    }

                    // 等待接收线程将标记修改
                    for (int j = 0; j < 10; j++)

                    {

                        if (this.ReceivedACK)

                        {

                            this.ReceivedACK = false;

                            return true;

                        }

                        else

                        {

                            Thread.Sleep(300);

                        }

                    }

                }

                // 构建P2P打洞封包

                // 然后通过服务器转发，请求对方向自己打洞
                P2PConnectionPacket transMsg = new P2PConnectionPacket(UserName, toUserName);

                byte[] msgBuffer = UtilityHelper.Serialize(transMsg);

                client.Send(msgBuffer, msgBuffer.Length, hostPoint);

                // 等待对方的P2PCONNECTACK消息
                for(int j = 0; j < 10; ++j)

                {

                    toUser = userList.Single(c => c.UserName == toUserName);

                    if ( toUser.P2PAddress != null && toUser.P2PAddress.Port != 0)

                        break;

                    Thread.Sleep(300);

                }

                

            }

            return false;

        }

b、消息接受线程


Code

c.建立p2p会话


Code

3、服务端

a、消息处理线程 


Code

b、服务端请求客户端建立p2p连接


Code
    
4、测试
a、服务端



b、客户端




 

困惑:

1、能不能实现外网通讯,要实现像QQ那样通讯要做哪些改进。

2、文件续传如何实现。

3、c#封装的网络操作类(像QQ.NET源码的Net实现)

4、远程协助的实现。

最后，希望大家共同讨论、共同进步！！！

P2PDemo.RAR可执行文件。