网络超时 -- 采取 SO_RCVTIMEO套接字选项设置 （ recv / recvfrom）

#include <sys/types.h>  
#include <sys/socket.h>  
#include <stdio.h>  
#include <netinet/in.h>  
#include <arpa/inet.h>  
#include <unistd.h>  
#include <string.h>  
#include <stdlib.h>  
#include <fcntl.h>  
#include <sys/shm.h>  
#include <error.h>
#include <errno.h>


#define MYPORT  8887  
#define QUEUE   20  
#define BUFFER_SIZE 1024  
  
int main()  
{  
    ///定义sockfd  
    int server_sockfd = socket(AF_INET,SOCK_STREAM, 0);  
     
    struct timeval  tv; 
    tv.tv_sec = 5;
    tv.tv_usec = 0;
    
    setsockopt(server_sockfd, SOL_SOCKET, SO_RCVTIMEO, &tv, sizeof(tv));


    ///定义sockaddr_in  
    struct sockaddr_in server_sockaddr;  
    server_sockaddr.sin_family = AF_INET;  
    server_sockaddr.sin_port = htons(MYPORT);  
    server_sockaddr.sin_addr.s_addr = htonl(INADDR_ANY);  
     
    ///bind，成功返回0，出错返回-1  
    if(bind(server_sockfd,(struct sockaddr *)&server_sockaddr,sizeof(server_sockaddr))==-1)  
    {   
        perror("bind");  
        exit(1);  
    }   
     
    printf("监听%d端口\n",MYPORT);  
    ///listen，成功返回0，出错返回-1  
    if(listen(server_sockfd,QUEUE) == -1)  
    {   
        perror("listen");  
        exit(1);  
    }   
     
    ///客户端套接字  
    char buffer[BUFFER_SIZE];  
    struct sockaddr_in client_addr;  
    socklen_t length = sizeof(client_addr);  
     
    printf("等待客户端连接\n");  
    ///成功返回非负描述字，出错返回-1  
    int conn = accept(server_sockfd, (struct sockaddr*)&client_addr, &length);  
    if(conn<0)  
    {
        perror("connect");
        exit(1);
    }
    printf("客户端成功连接\n");

    while(1)
    {
        memset(buffer,0,sizeof(buffer));
        int len = recv(conn, buffer, sizeof(buffer),0);
        if (len < 0)
        {
            if (errno == EWOULDBLOCK)
            {
                printf("socket timeout.\n");
                continue;
            }
            else
            {
                printf("recv error.\n");
            }
        }
        //客户端发送exit或者异常结束时，退出  
        if(strcmp(buffer,"exit\n")==0 || len<=0)
            break;
        printf("来自客户端数据：%s\n",buffer);
        send(conn, buffer, len, 0);
        printf("发送给客户端数据：%s\n",buffer);
    }
    close(conn);
    close(server_sockfd);
    return 0;
}