linux下udp编程

#include<sys/types.h>#include<sys/socket.h>#include<unistd.h>#include<netinet/in.h>#include<arpa/inet.h>#include<stdio.h>#include<stdlib.h>#include<errno.h>#include<netdb.h>#include<stdarg.h>#include<string>#include<iostream>#include<cstring>   /* 创建UDP套接口 */    struct sockaddr_in server_addr;    memset(&server_addr,0, sizeof(server_addr));    server_addr.sin_family = AF_INET;    server_addr.sin_addr.s_addr = htonl(INADDR_ANY);    server_addr.sin_port = htons(port);    /* 创建socket */    int server_socket_fd = socket(AF_INET, SOCK_DGRAM, 0);    if(server_socket_fd == -1)    {        perror("Create Socket Failed:");        exit(1);    }    /* 绑定套接口 */    if(-1 == (bind(server_socket_fd,(struct sockaddr*)&server_addr,sizeof(server_addr))))    {        perror("Server Bind Failed:");        exit(1);    }    struct sockaddr_in client_addr;    socklen_t client_addr_length = sizeof(client_addr);    //设置超时    struct timeval tv_out;    tv_out.tv_sec = 3;//等待10秒    tv_out.tv_usec = 0;    setsockopt(server_socket_fd,SOL_SOCKET,SO_RCVTIMEO,&tv_out, sizeof(tv_out));    /* 接收数据 */    memset(buffer,0, lenbuff);    if(recvfrom(server_socket_fd, buffer, lenbuff,0,(struct sockaddr*)&client_addr, &client_addr_length) == -1)  //MSG_DONTWAIT  将0换为MSG_DONTWAIT就是非阻塞模式，可能会cpu占用过高问题    {        if(errno!=EAGAIN)  //阻塞不设置超时时，不用判断，直接去掉该判断，保留子语句        {            perror("Receive Data Failed:");            exit(1);        }    }    close(server_socket_fd);