linux基础之 创建一个UDP socket

UDP socket

int bind_server_udp1(int server_s){struct sockaddr_in local_addr;memset(&local_addr,0,sizeof(local_addr));//set 0 for everythinglocal_addr.sin_family = AF_INET;//AF_INET（又称 PF_INET）是 IPv4 网络协议的套接字类型，AF_INET6 则是 IPv6 的；而 AF_UNIX 则是 Unix 系统本地通信local_addr.sin_addr.s_addr = htonl(INADDR_ANY);//INADDR_ANY就是指定地址为0.0.0.0的地址,这个地址事实上表示不确定地址,或“所有地址”、“任意地址”local_addr.sin_port = htons(3702);/* Give the socket FD the local address ADDR (which is LEN bytes long).将一本地地址与一套接口捆绑  int bind (int __fd, __CONST_SOCKADDR_ARG __addr, socklen_t __len);*/return bind(server_s,(struct sockaddr*)&local_addr,sizeof(local_addr));}static int create_server_socket_udp(void){int server_udp;unsigned char one = 1;int sock_opt = 1;//server_udp = socket(PF_INET, SOCK_DGRAM, 0);server_udp = socket(PF_INET, SOCK_DGRAM, IPPROTO_UDP);if (server_udp == -1) {printf("unable to create socket\n");}/* reuse socket addr, SO_REUSERADDR 允许重用本地地址和端口 int充许绑定已被使用的地址（或端口号）*/if ((setsockopt(server_udp, SOL_SOCKET, SO_REUSEADDR, (void *) &sock_opt,sizeof (sock_opt))) == -1) {printf("setsockopt\n");    }/*IP_MULTICAST_LOOP组播组中的成员自己也会收到它向本组发送的报文。这个选项用于选择是否激活这种状态。*/if ((setsockopt(server_udp, IPPROTO_IP, IP_MULTICAST_LOOP,&one, sizeof (unsigned char))) == -1) {printf("setsockopt\n");    }/* IPv4 multicast request. IP_ADD_MEMBERSHIP struct ip_mreq 加入到组播组中 */struct ip_mreq mreq;mreq.imr_multiaddr.s_addr = inet_addr("239.255.255.250");mreq.imr_interface.s_addr = htonl(INADDR_ANY);if(setsockopt(server_udp,IPPROTO_IP,IP_ADD_MEMBERSHIP,&mreq,sizeof(mreq))==-1){perror("memberchip error\n");}return server_udp;}