windows网络编程，udp多播例程，基于C语言

#define _WINSOCK_DEPRECATED_NO_WARNINGS #include<winsock2.h> #include<ws2ipdef.h> #include<stdio.h> #pragma comment(lib, "ws2_32.lib") int main() { WORD wVersionRequested = MAKEWORD(2, 2);//版本 WSADATA wsaDATA; //打开网络库 if (WSAStartup(wVersionRequested, &wsaDATA) != 0) { printf("打开网络库失败！\n"); return -1; } ip_mreq mreq; int TTL = 8; mreq.imr_interface.S_un.S_addr = inet_addr("127.0.0.1");//本地IP mreq.imr_multiaddr.S_un.S_addr = inet_addr("234.2.3.4");//多播组IP SOCKET sock = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);//创建Socket句柄，多播只支持UDP if (setsockopt(sock, IPPROTO_IP, IP_MULTICAST_TTL, (char*)&TTL, sizeof(TTL)) != 0)//设置TTL { printf("setsockopt设置TTL失败！\n"); closesocket(sock);//关闭Socket句柄 WSACleanup();//关闭网络库 return -1; } if (setsockopt(sock, IPPROTO_IP, IP_ADD_MEMBERSHIP, (char*)&mreq, sizeof(ip_mreq)) != 0)//加入多播组 { printf("setsockopt设置TTL失败！\n"); closesocket(sock);//关闭Socket句柄 WSACleanup();//关闭网络库 return -1; } struct sockaddr_in localif; localif.sin_family = AF_INET; localif.sin_port = htons(9527);//用htons宏将整型转为端口号的无符号整型 localif.sin_addr.S_un.S_addr = inet_addr("127.0.0.1");//使用多播IP作为目标IP if (SOCKET_ERROR == bind(sock, (const struct sockaddr*)&localif, sizeof(localif))) { int err = WSAGetLastError();//取错误码 printf("bind失败错误码为：%d\n", err); closesocket(sock);//释放 WSACleanup();//清理网络库 return 0; } char Recvbuf[0x100] = { 0 }; int Recvlen = sizeof(localif); while (1) { //用recv简单直接收取消息 if (recv(sock, Recvbuf, sizeof(Recvbuf), 0) == SOCKET_ERROR) { int err = WSAGetLastError();//取错误码 printf("recv失败错误码为：%d\n", err); continue; } //也可以用recvfrom，额外获取发送方IP地址 //struct sockaddr_in sa; //int iSaLen = sizeof(sa); //if (recvfrom(sock, Recvbuf, sizeof(Recvbuf), 0, (struct sockaddr*)&sa,&iSaLen) == SOCKET_ERROR) //{ // int err = WSAGetLastError();//取错误码 // printf("recv失败错误码为：%d\n", err); // continue; //} //printf("%s\n", inet_ntoa(sa.sin_addr)); printf("%s\n", Recvbuf); } closesocket(sock);//关闭Socket句柄 WSACleanup();//关闭网络库 return 0; }