socket编程中的超时设置示例详解之二

接前文

​二、操作(send,
recv)超时

对它们有两种方式来设置超时，

1. 将send, recv设置成非阻塞模式，然后用select来设置超时机制，就如上面的connect方式一样。

2. 使用setsockopt()函数来设置相应的超时机制。

因为前一种方式在connect中重点说明，本节来主要说明第二种方式。

示例代码如下：

对send和recv进行了超时设置，并最多做四次重试

/*

* \brief

* tcp client

*/

#include <stdio.h>

#include <stdlib.h>

#include <sys/socket.h>

#include <sys/time.h>

#include <netdb.h>

#include <string.h>

#define TIMEOUT_TIME 2

#define SERVPORT 8080

#define MAXDATASIZE 100

int main(int argc, char *argv[])

{

int sockfd, recvbytes;

char rcv_buf[MAXDATASIZE]; /*./client 127.0.0.1 hello */

char snd_buf[MAXDATASIZE];

struct hostent *host; /* struct hostent

* {

* char *h_name; // general hostname

* char **h_aliases; // hostname's alias

* int h_addrtype; // AF_INET

* int h_length;

* char **h_addr_list;

* };

*/

struct sockaddr_in server_addr;

/* Timeout */

struct timeval timeout;

socklen_t len = sizeof(timeout);

int result;

int error;

int i;

if (argc < 3)

{

printf("Usage:%s [ip address] [any string]\n", argv[0]);

return 1;

}

*snd_buf = '\0';

strcat(snd_buf, argv[2]);

if ((sockfd = socket(AF_INET, SOCK_STREAM, 0)) == -1)

{

perror("socket:");

exit(1);

}

server_addr.sin_family = AF_INET;

server_addr.sin_port = htons(SERVPORT);

inet_pton(AF_INET, argv[1], &server_addr.sin_addr);

memset(&(server_addr.sin_zero), 0, 8);

/* create the connection by socket

* means that connect "sockfd" to "server_addr"

*/

if (connect(sockfd, (struct sockaddr *)&server_addr, sizeof(struct sockaddr)) == -1)

{

perror("connect");

exit(1);

}

/* send 超时设置，并最多做四次重试 */

timeout.tv_sec = TIMEOUT_TIME;

timeout.tv_usec= 0;

result = setsockopt(sockfd, SOL_SOCKET, SO_SNDTIMEO, (char*)&timeout.tv_sec, len);

if (result < 0)

{

perror("setsockopt:");

exit(1);

}

for(i = 0; i < 4; i++)

{

if (send(sockfd, snd_buf, sizeof(snd_buf), 0) == -1)

{

getsockopt(sockfd, SOL_SOCKET, SO_ERROR, &error, &len);

if (error == 0)

{

printf("recv timeout!\n");

continue;

}

}

else

{

break;

}

}

printf("send:%s\n", snd_buf);

/* recv 超时设置，并最多做四次重试 */

timeout.tv_sec = TIMEOUT_TIME;

timeout.tv_usec= 0;

result = setsockopt(sockfd, SOL_SOCKET, SO_RCVTIMEO, (char*)&timeout.tv_sec, len);

if (result < 0)

{

perror("setsockopt:");

exit(1);

}

for(i = 0; i < 4; i++)

{

if ((recvbytes = recv(sockfd, rcv_buf, MAXDATASIZE, 0)) == -1)

{

getsockopt(sockfd, SOL_SOCKET, SO_ERROR, &error, &len);

if (error == 0)

{

printf("recv timeout!\n");

continue;

}

}

else

{

break;

}

}

rcv_buf[recvbytes] = '\0';

printf("recv:%s\n", rcv_buf);

close(sockfd);

return 0;

}

​