vc++实现组播传输

- 日理万妓 2022-02-19 21:15 324阅读 0赞

组播传输比起普通udp传输主要多了加入组以及设置本地回环是否接收等设定。需要注意的是，如果本地有多个IP，绑定local address的时候建议不要使用INADDR\_ANY。源码如下

#include <iostream>
    #include <winsock2.h> 
    #include <Ws2tcpip.h>
    #include <process.h> 
    
    #pragma comment(lib, "ws2_32.lib")
    
    using namespace std;
    
    //const char* MULTICAST_IP = "224.0.0.99"; 
    const char* MULTICAST_IP = "239.192.152.143"; 
    const int MULTICAST_PORT = 6771; 
    
    const int BUFFER_SIZE = 1024;
    
    void do_send(void* arg); 
    void do_read(void* arg); 
    int main()
    { 
    	WSAData wsaData;
    
    	if (WSAStartup(MAKEWORD(2, 2), &wsaData) != 0)
    	{ 
    		cout << "Error in WSAStartup" << endl;
    		return 0;
    	}
    
    	SOCKET server;
    	server = socket(AF_INET, SOCK_DGRAM, 0); 
    	cout << "create socket: " << server << endl;
    
    	int ret;
    
    	const int on = 1; 
    	ret = setsockopt(server, SOL_SOCKET, SO_REUSEADDR, (char *)&on, sizeof(on));
    	if (ret == SOCKET_ERROR)
    	{ 
    		WSACleanup();
    
    		cout << "Error in setsockopt(SO_REUSEADDR): " << WSAGetLastError() << endl;
    		return 0;
    	}
    
    	const int routenum = 10;
    	ret = setsockopt(server, IPPROTO_IP, IP_MULTICAST_TTL, \
    		(char*)&routenum, sizeof(routenum));
    	if (ret == SOCKET_ERROR)
    	{ 
    		WSACleanup();
    
    		cout << "Error in setsockopt(IP_MULTICAST_TTL): " << WSAGetLastError() << endl;
    		return 0;
    	}
    
    	const int loopback = 1; 
    	ret = setsockopt(server, IPPROTO_IP, IP_MULTICAST_LOOP, \
    		(char*)&loopback, sizeof(loopback));
    	if (ret == SOCKET_ERROR)
    	{ 
    		WSACleanup();
    
    		cout << "Error in setsockopt(IP_MULTICAST_LOOP): " << WSAGetLastError() << endl;
    		return 0;
    	}
    
    	sockaddr_in local;
    	memset(&local, 0, sizeof(local));
    	local.sin_family = AF_INET;
    	local.sin_port = htons(MULTICAST_PORT);
    	local.sin_addr.S_un.S_addr = INADDR_ANY;
    
    	ret = bind(server, (sockaddr*)(&local), sizeof(local));
    	if (ret == SOCKET_ERROR)
    	{ 
    		WSACleanup();
    
    		cout << "Error in bind: " << WSAGetLastError() << endl;
    		return 0;
    	}
    
    	ip_mreq mreq;
    	memset(&mreq, 0, sizeof(mreq));
    	mreq.imr_interface.S_un.S_addr = INADDR_ANY;
    	mreq.imr_multiaddr.S_un.S_addr = inet_addr(MULTICAST_IP);
    
    	ret = setsockopt(server, IPPROTO_IP, IP_ADD_MEMBERSHIP, \
    		(char*)&mreq, sizeof(mreq));
    	if (ret == SOCKET_ERROR)
    	{ 
    		WSACleanup();
    
    		cout << "Error in setsockopt(IP_ADD_MEMBERSHIP): " << WSAGetLastError() << endl;
    		return 0;
    	}
    
    	HANDLE hHandle[2];
    	hHandle[0] = (HANDLE)_beginthread(do_send, 0, (void*)server);
    	hHandle[1] = (HANDLE)_beginthread(do_read, 0, (void*)server);
    
    	
    	WaitForSingleObject(hHandle[0], INFINITE);
    
    	WSACleanup();
    
    	return 0;
    }
    
    void do_send(void* arg)
    { 
    	SOCKET server = (SOCKET)arg;
    
    	char sendline[BUFFER_SIZE + 1];
    
    	sockaddr_in remote;
    	memset(&remote, 0, sizeof(remote));
    	remote.sin_addr.s_addr = inet_addr(MULTICAST_IP);
    	remote.sin_family = AF_INET;
    	remote.sin_port = htons(MULTICAST_PORT);
    
    	for (;;) 
    	{ 
    		std::cout << "Send: ";
    		std::cin >> sendline;
    		//cin.getline(sendline, BUFFER_SIZE);
    
    		if (strncmp(sendline, "end", 3) == 0)
    			break;
    
    		
    		sendto(server, sendline, strlen(sendline), 0, (sockaddr*)(&remote), sizeof(remote));
    	}
    
    	cout << "do_send end..." << endl;
    }
    
    void do_read(void* arg)
    { 
    	SOCKET server = (SOCKET)arg;
    
    	char buf[BUFFER_SIZE + 1];
    	int ret;
    
    	sockaddr_in client;
    	int clientLen;
    
    	for (;;) 
    	{ 
    		clientLen = sizeof(client);
    		memset(&client, 0, clientLen);
    
    		ret = recvfrom(server, buf, BUFFER_SIZE, 0, (sockaddr*)(&clientLen), &clientLen);
    		if (ret == 0) 
    		{ 
    			continue;
    		}
    		else if (ret == SOCKET_ERROR)
    		{ 
    			if (WSAGetLastError() == WSAEINTR) 
    				break;
    
    			cout << "Error in recvfrom: " << WSAGetLastError() << endl;
    			break;
    		}
    		buf[ret] = '\0';
    		cout << std::endl << "received: " << buf << endl;
    		std::cout << "Send: ";
    	}
    
    	cout << "do_read end..." << endl;
    }

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