int val = 1;
setsockopt(socket, SOL_SOCKET, SO_KEEPALIVE, &val, sizeof val)
仅启用保活。您将获得保活探测的默认计时器,可以使用以下命令查看:
sysctl net.ipv4.tcp_keepalive_time
通常默认为几个小时。
如果您想更改默认计时器,可以使用以下命令:
struct KeepConfig cfg = { 60, 5, 5};
set_tcp_keepalive_cfg(fd, &cfg);
使用此处的辅助函数:
struct KeepConfig {
/** The time (in seconds) the connection needs to remain
* idle before TCP starts sending keepalive probes (TCP_KEEPIDLE socket option)
*/
int keepidle;
/** The maximum number of keepalive probes TCP should
* send before dropping the connection. (TCP_KEEPCNT socket option)
*/
int keepcnt;
/** The time (in seconds) between individual keepalive probes.
* (TCP_KEEPINTVL socket option)
*/
int keepintvl;
};
/**
* enable TCP keepalive on the socket
* @param fd file descriptor
* @return 0 on success -1 on failure
*/
int set_tcp_keepalive(int sockfd)
{
int optval = 1;
return setsockopt(sockfd, SOL_SOCKET, SO_KEEPALIVE, &optval, sizeof(optval));
}
/** Set the keepalive options on the socket
* This also enables TCP keepalive on the socket
*
* @param fd file descriptor
* @param fd file descriptor
* @return 0 on success -1 on failure
*/
int set_tcp_keepalive_cfg(int sockfd, const struct KeepConfig *cfg)
{
int rc;
//first turn on keepalive
rc = set_tcp_keepalive(sockfd);
if (rc != 0) {
return rc;
}
//set the keepalive options
rc = setsockopt(sockfd, IPPROTO_TCP, TCP_KEEPCNT, &cfg->keepcnt, sizeof cfg->keepcnt);
if (rc != 0) {
return rc;
}
rc = setsockopt(sockfd, IPPROTO_TCP, TCP_KEEPIDLE, &cfg->keepidle, sizeof cfg->keepidle);
if (rc != 0) {
return rc;
}
rc = setsockopt(sockfd, IPPROTO_TCP, TCP_KEEPINTVL, &cfg->keepintvl, sizeof cfg->keepintvl);
if (rc != 0) {
return rc;
}
return 0;
}