linux网络编程二十：socket选项：SO_RCVTIMEO和SO_SNDTIMEO

SO_RCVTIMEO和SO_SNDTIMEO ，它们分别用来设置socket接收数据超时时间和发送数据超时时间。

因此，这两个选项仅对与数据收发相关的系统调用有效，这些系统调用包括：send, sendmsg, recv, recvmsg, accept, connect 。

这两个选项设置后，若超时，返回-1，并设置errno为EAGAIN或EWOULDBLOCK.

其中connect超时的话，也是返回-1, 但errno设置为EINPROGRESS

1. 代码：设置connect超时时间

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

//超时连接
int timeout_connect(const char *ip, int port, int time);

int main(int argc, char **argv)
{
   if (argc != 3) {
       fprintf(stderr, "Usage: %s ip port\n", argv[0]);
       return 1;
   }

   const char *ip = argv[1];
   int port = atoi(argv[2]);

   int sockfd = timeout_connect(ip, port, 10);
   if (sockfd < 0)
       return 1;


   return 0;
}

int timeout_connect(const char *ip, int port, int time)
{
   int ret = 0;
   int error;

   struct sockaddr_in address;
   bzero(&address, sizeof(address));
   address.sin_family = AF_INET;
   address.sin_port = htons(port);
   inet_pton(AF_INET, ip, &address.sin_addr);

   int sockfd = socket(PF_INET, SOCK_STREAM, 0);
   if (sockfd == -1)
       return -1;

   //超时时间
   struct timeval timeout;
   timeout.tv_sec = time;
   timeout.tv_usec = 0;

   socklen_t len = sizeof(timeout);
   ret = setsockopt(sockfd, SOL_SOCKET, SO_SNDTIMEO, &timeout, len);
   if (ret == -1) {
       error = errno;
       while ((close(sockfd) == -1) && (errno == EINTR));
       errno = error;
       return -1;
   }

   ret = connect(sockfd, (struct sockaddr*)&address, sizeof(address));
   if (ret == -1) {
       if (errno == EINPROGRESS) {
           printf("connecting timeout\n");
           return -1;
       }

       printf("error occur when connecting to server\n");
       return -1;
   }

   char buffer[1024];
   memset(buffer, '\0', 1024);
   ret = recv(sockfd, buffer, 1024, 0);

   printf("recv %d bytes, buf: %s\n", ret, buffer);

   return sockfd;
}

参考：《linux高性能服务器编程》

---------------------
作者：jasonliuvip
来源：CSDN
原文：https://blog.csdn.net/jasonliuvip/article/details/23567843
版权声明：本文为博主原创文章，转载请附上博文链接！

来源：oschina

链接：https://my.oschina.net/u/4000302/blog/3044293

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