p2pclient.cpp

一个UDP穿透NAT的实例程序

 /* P2P 程序客户端
 * 
 * 文件名：P2PClient.c
 *
 * 日期：2004-5-21
 *
 * 作者：shootingstars([e-mail])
 *
 */

/*  源码修改声明:
 *
 *	这个修改的代码是早期为了节省时间在原作者(shootingstars)的代码的基础上修
 *  改测试用的。原代码的版权归原作者所有。对于做的修改的部分本人不作任何担保，
 *  只是为了方便大家使用修改后的代码对于UDP穿透进行验证而已。
 *
 *  原作者的关于UDP穿透的简介是网上较早的一份对于UDP穿透内网的说明，但是并
 *  不是特别的清楚和详细。本人在从事P2P程序开发的过程中, 对于内网穿透做了很
 *  好的实现。由于经常有人问起这方面的问题，因此决定将自己对于使用UDP内网
 *  穿透的经验也写出来与大家分享， 希望对于从事这方面工作的朋友有所帮助.
 *  
 *  源码修改者简介:
 *
 *  Hwycheng Leo, like C/C++/Python/Perl, hate Java. 
 *  一直使用C/C++语言从事网络服务器和客户端方面的开发工作。近两年来主攻P2P技术方向。
 *  开发了完全免费强大的BitTorrent下载软件 - FlashBT(变态快车). 近期在公司负责开发
 *  P2P + IM 的商业化平台。
 *  
 *  邮件/MSN: [e-mail]           [欢迎热爱网络编程和P2P开发的来信交流]
 *  软件主页: http://www.hwysoft.com/chs/   [FlashBT(变态快车)的官方主页]
 *  个人Blog: http://hwycheng.blogchina.com [主要是自己写的一些技术文章和生活感受]
 */

#pragma comment(lib,"ws2_32.lib")

#include "windows.h"
#include "..\proto.h"
#include "..\Exception.h"
#include <iostream>
using namespace std;

USHORT g_nClientPort = 9896;
USHORT g_nServerPort = SERVER_PORT;

UserList ClientList;

#define COMMANDMAXC 256
#define MAXRETRY    5

SOCKET PrimaryUDP;
char UserName[10];
char ServerIP[20];

bool RecvedACK;

void InitWinSock()
{
	WSADATA wsaData;

	if (WSAStartup(MAKEWORD(2, 2), &wsaData) != 0)
	{
		printf("Windows sockets 2.2 startup");
		throw Exception("");
	}
	else{
		printf("Using %s (Status: %s)\n",
			wsaData.szDescription, wsaData.szSystemStatus);
		printf("with API versions %d.%d to %d.%d\n\n",
			LOBYTE(wsaData.wVersion), HIBYTE(wsaData.wVersion),
			LOBYTE(wsaData.wHighVersion), HIBYTE(wsaData.wHighVersion));
	}
}

SOCKET mksock(int type)
{
	SOCKET sock = socket(AF_INET, type, 0);
	if (sock < 0)
	{
        printf("create socket error");
		throw Exception("");
	}
	return sock;
}

stUserListNode GetUser(char *username)
{
	for(UserList::iterator UserIterator=ClientList.begin();
						UserIterator!=ClientList.end();
							++UserIterator)
	{
		if( strcmp( ((*UserIterator)->userName), username) == 0 )
			return *(*UserIterator);
	}
	throw Exception("not find this user");
}

void BindSock(SOCKET sock)
{
	sockaddr_in sin;
	sin.sin_addr.S_un.S_addr = INADDR_ANY;
	sin.sin_family = AF_INET;
	sin.sin_port = htons(g_nClientPort);
	
	if (bind(sock, (struct sockaddr*)&sin, sizeof(sin)) < 0)
		throw Exception("bind error");
}

void ConnectToServer(SOCKET sock,char *username, char *serverip)
{
	sockaddr_in remote;
	remote.sin_addr.S_un.S_addr = inet_addr(serverip);
	remote.sin_family = AF_INET;
	remote.sin_port = htons(g_nServerPort);
	
	stMessage sendbuf;
	sendbuf.iMessageType = LOGIN;
	strncpy(sendbuf.message.loginmember.userName, username, 10);

	sendto(sock, (const char*)&sendbuf, sizeof(sendbuf), 0, (const sockaddr*)&remote,sizeof(remote));
	int usercount;
	int fromlen = sizeof(remote);

    for ( ;; )
    {
        fd_set readfds;
        fd_set writefds;

        FD_ZERO( &readfds );
        FD_ZERO( &writefds );

        FD_SET( sock, &readfds );
        int maxfd = sock;

        timeval to;
        to.tv_sec = 2;
        to.tv_usec = 0;

        int n = select( maxfd + 1, &readfds, &writefds, NULL, &to );

        if ( n > 0 )
        {
            if ( FD_ISSET( sock, &readfds ) )
			{
				int iread = recvfrom(sock, (char *)&usercount, sizeof(int), 0, (sockaddr *)&remote, &fromlen);
				if(iread<=0)
				{
					throw Exception("Login error\n");
				}

				break;
			}
        }
        else if ( n < 0 )
        {
			throw Exception("Login error\n");
        }

		sendto(sock, (const char*)&sendbuf, sizeof(sendbuf), 0, (const sockaddr*)&remote,sizeof(remote));
    }

	// 登录到服务端后，接收服务端发来的已经登录的用户的信息
	cout<<"Have "<<usercount<<" users logined server:"<<endl;
	for(int i = 0;i<usercount;i++)
	{
		stUserListNode *node = new stUserListNode;
		recvfrom(sock, (char*)node, sizeof(stUserListNode), 0, (sockaddr *)&remote, &fromlen);
		ClientList.push_back(node);
		cout<<"Username:"<<node->userName<<endl;
		in_addr tmp;
		tmp.S_un.S_addr = htonl(node->ip);
		cout<<"UserIP:"<<inet_ntoa(tmp)<<endl;
		cout<<"UserPort:"<<node->port<<endl;
		cout<<""<<endl;
	}
}

void OutputUsage()
{
	cout<<"You can input you command:\n"
		<<"Command Type:\"send\",\"tell\", \"exit\",\"getu\"\n"
		<<"Example : send Username Message\n"
		<<"Example : tell Username ip:port Message\n"
		<<"          exit\n"
		<<"          getu\n"
		<<endl;
}

/* 这是主要的函数：发送一个消息给某个用户(C)
 *流程：直接向某个用户的外网IP发送消息，如果此前没有联系过
 *      那么此消息将无法发送，发送端等待超时。
 *      超时后，发送端将发送一个请求信息到服务端，
 *      要求服务端发送给客户C一个请求，请求C给本机发送打洞消息
 *      以上流程将重复MAXRETRY次
 */
bool SendMessageTo(char *UserName, char *Message)
{
	char realmessage[256];
	unsigned int UserIP;
	unsigned short UserPort;
	bool FindUser = false;
	for(UserList::iterator UserIterator=ClientList.begin();
						UserIterator!=ClientList.end();
						++UserIterator)
	{
		if( strcmp( ((*UserIterator)->userName), UserName) == 0 )
		{
			UserIP = (*UserIterator)->ip;
			UserPort = (*UserIterator)->port;
			FindUser = true;
		}
	}

	if(!FindUser)
		return false;

	strcpy(realmessage, Message);
	for(int i=0;i<MAXRETRY;i++)
	{
		RecvedACK = false;

		sockaddr_in remote;
		remote.sin_addr.S_un.S_addr = htonl(UserIP);
		remote.sin_family = AF_INET;
		remote.sin_port = htons(UserPort);
		stP2PMessage MessageHead;
		MessageHead.iMessageType = P2PMESSAGE;
		MessageHead.iStringLen = (int)strlen(realmessage)+1;
		int isend = sendto(PrimaryUDP, (const char *)&MessageHead, sizeof(MessageHead), 0, (const sockaddr*)&remote, sizeof(remote));
		isend = sendto(PrimaryUDP, (const char *)&realmessage, MessageHead.iStringLen, 0, (const sockaddr*)&remote, sizeof(remote));
		
		// 等待接收线程将此标记修改
		for(int j=0;j<10;j++)
		{
			if(RecvedACK)
				return true;
			else
				Sleep(300);
		}

		// 没有接收到目标主机的回应，认为目标主机的端口映射没有
		// 打开，那么发送请求信息给服务器，要服务器告诉目标主机
		// 打开映射端口（UDP打洞）
		sockaddr_in server;
		server.sin_addr.S_un.S_addr = inet_addr(ServerIP);
		server.sin_family = AF_INET;
		server.sin_port = htons(g_nServerPort);
	
		stMessage transMessage;
		transMessage.iMessageType = P2PTRANS;
		strcpy(transMessage.message.translatemessage.userName, UserName);

		sendto(PrimaryUDP, (const char*)&transMessage, sizeof(transMessage), 0, (const sockaddr*)&server, sizeof(server));
		Sleep(100);// 等待对方先发送信息。
	}
	return false;
}

bool SendMessageTo2(char *UserName, char *Message, const char *pIP, USHORT nPort )
{
	char realmessage[256];
	unsigned int UserIP = 0L;
	unsigned short UserPort = 0;

	if ( pIP != NULL )
	{
		UserIP = ntohl( inet_addr( pIP ) );
		UserPort = nPort;
	}
	else
	{
		bool FindUser = false;
		for(UserList::iterator UserIterator=ClientList.begin();
							UserIterator!=ClientList.end();
							++UserIterator)
		{
			if( strcmp( ((*UserIterator)->userName), UserName) == 0 )
			{
				UserIP = (*UserIterator)->ip;
				UserPort = (*UserIterator)->port;
				FindUser = true;
			}
		}

		if(!FindUser)
			return false;
	}

	strcpy(realmessage, Message);

	sockaddr_in remote;
	remote.sin_addr.S_un.S_addr = htonl(UserIP);
	remote.sin_family = AF_INET;
	remote.sin_port = htons(UserPort);
	stP2PMessage MessageHead;
	MessageHead.iMessageType = P2PMESSAGE;
	MessageHead.iStringLen = (int)strlen(realmessage)+1;

	printf( "Send message, %s:%ld -> %s\n", inet_ntoa( remote.sin_addr ), ntohs( remote.sin_port ), realmessage );
	
	for(int i=0;i<MAXRETRY;i++)
	{
		RecvedACK = false;
		int isend = sendto(PrimaryUDP, (const char *)&MessageHead, sizeof(MessageHead), 0, (const sockaddr*)&remote, sizeof(remote));
		isend = sendto(PrimaryUDP, (const char *)&realmessage, MessageHead.iStringLen, 0, (const sockaddr*)&remote, sizeof(remote));
		
		// 等待接收线程将此标记修改
		for(int j=0;j<10;j++)
		{
			if(RecvedACK)
				return true;
			else
				Sleep(300);
		}
	}
	return false;
}