P2P学习记录二

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

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

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

UserList ClientList;



#define COMMANDMAXC 256
#define MAXRETRY    5
/*最大尝试次数为5次*/
SOCKET PrimaryUDP;
char UserName[10];
char ServerIP[20];

bool RecvedACK;

void InitWinSock()//udp服务初始化，出书后失败时抛出异常
{
	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)//套接字创建函数，创建失败时抛出异常
{
	SOCKET sock = socket(AF_INET, type, 0);
	if (sock < 0)
	{
        printf("create socket error");
		throw Exception("");
	}
	return sock;
}

stUserListNode GetUser(char *username)//获取指定名称的用户信息，返回用户信息结构体指针，失败时抛出用户信息不存在的异常信息
{
	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)//为套接字标识绑定地址，端口。此处地址类型为IPV4，地址为本机地址，端口号由于是客户端不需要指定，在连接时会由系统随机指定
{
	sockaddr_in sin;
	sin.sin_addr.S_un.S_addr = INADDR_ANY;
	sin.sin_family = AF_INET;
	sin.sin_port = 0;
	
	if (bind(sock, (struct sockaddr*)&sin, sizeof(sin)) < 0)
		throw Exception("bind error");
}

void ConnectToServer(SOCKET sock,char *username, char *serverip)//username为自定义的用户名，serverip为服务器部署位置的本机ip
{
	sockaddr_in remote;//创建登陆地址结构体，地址为服务器ip，端口为事先定义的服务器监听端口，地址类型ipv4
	remote.sin_addr.S_un.S_addr = inet_addr(serverip);
	remote.sin_family = AF_INET;
	remote.sin_port = htons(SERVER_PORT);
	
	stMessage sendbuf;//登陆信息结构体，信息标识LOGIN，内容是用户名username
	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;//用于接收客户端返回的在线用户数目
	int fromlen = sizeof(remote);
	int iread = recvfrom(sock, (char *)&usercount, sizeof(int), 0, (sockaddr *)&remote, &fromlen);//接收登陆成功的应答信息
	if(iread<=0)
	{
		throw Exception("Login error\n");
	}

	// 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;//保存在线用户信息
		recvfrom(sock, (char*)node, sizeof(stUserListNode), 0, (sockaddr *)&remote, &fromlen);
		ClientList.push_back(node);//保存用户信息
		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;//将用户信息显示到输出屏上
	}
}

void OutputUsage()//用户提示界面
{
	cout<<"You can input you command:\n"
		<<"Command Type:\"send\",\"exit\",\"getu\"\n"
		<<"Example : send Username 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();//本地查找，确认用户存在与否
						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++)//udp打洞流程
	{
		RecvedACK = false;//应答标识

		sockaddr_in remote;//目标用户地址结构体
		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));//向目标客户端发送消息头，包含信息类型P2PMESSAGE，数据长度等信息
		isend = sendto(PrimaryUDP, (const char *)&realmessage, MessageHead.iStringLen, 0, (const sockaddr*)&remote, sizeof(remote));//数据发送，realmessage为要发送的信息
		
		// 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);
		}//阻塞等待目标用户回应，总计等待时间10*300ms=3s，3秒后如无应答，向服务器请求p2p打洞

		// 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;//目标服务器地址结构体
		server.sin_addr.S_un.S_addr = inet_addr(ServerIP);
		server.sin_family = AF_INET;
		server.sin_port = htons(SERVER_PORT);
	
		stMessage transMessage;//p2p协议里定义的p2p打洞消息类型
		transMessage.iMessageType = P2PTRANS;
		strcpy(transMessage.message.translatemessage.userName, UserName);

		sendto(PrimaryUDP, (const char*)&transMessage, sizeof(transMessage), 0, (const sockaddr*)&server, sizeof(server));//发送打洞请求到服务器
		Sleep(100);// 等待对方先发送信息。
	}
	return false;//超出预计次数判定p2p连接失败
}

// 解析命令，暂时只有exit和send命令
// 新增getu命令，获取当前服务器的所有用户
void ParseCommand(char * CommandLine)//命令相应
{
	if(strlen(CommandLine)<4)
		return;
	char Command[10];
	strncpy(Command, CommandLine, 4);//识别前四个字符
	Command[4]='\0';

	if(strcmp(Command,"exit")==0)//退出登录，关闭套接字
	{
		stMessage sendbuf;
		sendbuf.iMessageType = LOGOUT;
		strncpy(sendbuf.message.logoutmember.userName, UserName, 10);
		sockaddr_in server;
		server.sin_addr.S_un.S_addr = inet_addr(ServerIP);
		server.sin_family = AF_INET;
		server.sin_port = htons(SERVER_PORT);

		sendto(PrimaryUDP,(const char*)&sendbuf, sizeof(sendbuf), 0, (const sockaddr *)&server, sizeof(server));
		shutdown(PrimaryUDP, 2);
		closesocket(PrimaryUDP);
		exit(0);
	}
	else if(strcmp(Command,"send")==0)//向指定用户发送信息，输入格式有要求
	{
		char sendname[20];
		char message[COMMANDMAXC];
		int i;
		for(i=5;;i++)//从命令行提取发送消息的用户名，命令行格式为：命令+＇ ＇+目标用户名+＇　＇+消息，此处可以改进
		{
			if(CommandLine[i]!=' ')
				sendname[i-5]=CommandLine[i];
			else
			{
				sendname[i-5]='\0';
				break;
			}
		}
		strcpy(message, &(CommandLine[i+1]));
		if(SendMessageTo(sendname, message))
			printf("Send OK!\n");
		else 
			printf("Send Failure!\n");
	}
	else if(strcmp(Command,"getu")==0)//向服务器发送消息获得所有用户信息
	{
		int command = GETALLUSER;
		sockaddr_in server;
		server.sin_addr.S_un.S_addr = inet_addr(ServerIP);
		server.sin_family = AF_INET;
		server.sin_port = htons(SERVER_PORT);

		sendto(PrimaryUDP,(const char*)&command, sizeof(command), 0, (const sockaddr *)&server, sizeof(server));
	}
}

// 接受消息线程
DWORD WINAPI RecvThreadProc(LPVOID lpParameter)
{
	sockaddr_in remote;//获取消息发送方地址
	int sinlen = sizeof(remote);
	stP2PMessage recvbuf;//获取消息内容
	for(;;)
	{
		int iread = recvfrom(PrimaryUDP, (char *)&recvbuf, sizeof(recvbuf), 0, (sockaddr *)&remote, &sinlen);//循环监听对应端口的信息，此处为client消息头
		if(iread<=0)
		{
			printf("recv error\n");
			continue;
		}
		switch(recvbuf.iMessageType)
		{
		case P2PMESSAGE:
			{
				// 接收到P2P的消息
				char *comemessage= new char[recvbuf.iStringLen];//创建对应大小的消息缓存区域保存消息
				int iread1 = recvfrom(PrimaryUDP, comemessage, 256, 0, (sockaddr *)&remote, &sinlen);//此处接收的为消息
				comemessage[iread1-1] = '\0';
				if(iread1<=0)
					throw Exception("Recv Message Error\n");
				else
				{
					printf("Recv a Message:%s\n",comemessage);//输出接收到的消息
					
					stP2PMessage sendbuf;//P2P回复消息结构体
					sendbuf.iMessageType = P2PMESSAGEACK;//接收方接收到此标识的数据，会改变自身ACK标识
					sendto(PrimaryUDP, (const char*)&sendbuf, sizeof(sendbuf), 0, (const sockaddr*)&remote, sizeof(remote));
				}

				delete []comemessage;
				break;

			}
		case P2PSOMEONEWANTTOCALLYOU://此消息来源为服务器，同时标识A->B方向的P2P洞已经建立好
			{
				// 接收到打洞命令，向指定的IP地址打洞
				printf("Recv p2someonewanttocallyou data\n");
				sockaddr_in remote;//存放udp打洞目标地址的结构体
				remote.sin_addr.S_un.S_addr = htonl(recvbuf.iStringLen);
				remote.sin_family = AF_INET;
				remote.sin_port = htons(recvbuf.Port);

				// UDP hole punching
				stP2PMessage message;
				message.iMessageType = P2PTRASH;
				sendto(PrimaryUDP, (const char *)&message, sizeof(message), 0, (const sockaddr*)&remote, sizeof(remote));//B->A发送打洞信息，同时建立起B->A方向的P2P洞
                
				break;
			}
		case P2PMESSAGEACK:
			{
				// 发送消息的应答
				RecvedACK = true;
				break;
			}
		case P2PTRASH:
			{
				// 对方发送的打洞消息，忽略掉。
				//do nothing ...
				printf("Recv p2ptrash data\n");
				break;
			}
		case GETALLUSER://此为服务器应答1
			{
				int usercount;
				int fromlen = sizeof(remote);
				int iread = recvfrom(PrimaryUDP, (char *)&usercount, sizeof(int), 0, (sockaddr *)&remote, &fromlen);//此为服务器应答2，返回数据是用户计数
				if(iread<=0)
				{
					throw Exception("Login error\n");
				}
				
				ClientList.clear();

				cout<<"Have "<<usercount<<" users logined server:"<<endl;
				for(int i = 0;i<usercount;i++)//保存服务器返回的用户信息
				{
					stUserListNode *node = new stUserListNode;
					recvfrom(PrimaryUDP, (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;
				}
				break;
			}
		}
	}
}


int main(int argc, char* argv[])
{
	try
	{
		InitWinSock();//udp服务初始化
		
		PrimaryUDP = mksock(SOCK_DGRAM);//创建udp套接字
		BindSock(PrimaryUDP);//自定义函数为client套接字标识绑定地址

		cout<<"Please input server ip:";
		cin>>ServerIP;

		cout<<"Please input your name:";
		cin>>UserName;

		ConnectToServer(PrimaryUDP, UserName, ServerIP);

		HANDLE threadhandle = CreateThread(NULL, 0, RecvThreadProc, NULL, NULL, NULL);//创建消息接收线程
		CloseHandle(threadhandle);//销毁线程- -，上面的线程是个无限循环，只有等程序退出啦
		OutputUsage();

		for(;;)//循环等待用户操作
		{
			char Command[COMMANDMAXC];
			gets_s(Command,COMMANDMAXC);
			ParseCommand(Command);
		}
	}
	catch(Exception &e)
	{
		printf(e.GetMessage());
		return 1;
	}
	return 0;
}

转自：http://www.ppcn.net/p2ptech.htm