插座，检测连接丢失 [英] socket, detect connection is lost

问题描述

我连接一个服务器进程和一个TCP连接的客户端的过程，我必须检测结果
两台机器之间的物理连接已断开。我试图做到这一点使用的存活时间，结果
降低默认的系统范围内的值：

I'm connecting a server process and a client process with a TCP connection, and I have to detect
that physical connection between the two machines is down. I'm trying to do this using the keepalive,
decreasing the default system wide values to:

TCP_KEEPIDLE = 5结果
TCP_KEEPCNT = 5结果
TCP_KEEPINTVL = 1

TCP_KEEPIDLE=5
TCP_KEEPCNT = 5
TCP_KEEPINTVL = 1

当连接出现故障（我断开连接线）仅在10秒内服务器检测到连接已丢失，客户端只是挂起的发送。

When the connection goes down ( I disconnect the cable ) only the server in 10 seconds detect that the connection has been lost, the client just hangs on the send.

这是客户端code：

#include <iostream>
#include <string.h>
#include <sys/socket.h>
#include <stdlib.h>
#include <arpa/inet.h>
#include <errno.h>
#include <netinet/tcp.h>

int main(int argc, char** argv) {
  char myVector[1600];

  int mySocket = socket(AF_INET, SOCK_STREAM, IPPROTO_IP);
  if (mySocket < 0 ) {
    std::cout << "error creating the socket" << strerror(errno) << std::endl;
    ::exit(-1);
 }

 struct sockaddr_in sin;
 memset( (char *)&sin, 0, sizeof( sin ) );
 sin.sin_addr.s_addr = inet_addr("192.168.21.27");
 sin.sin_port   = htons(7788);
 sin.sin_family = AF_INET;

 if ( connect( mySocket, (struct sockaddr *)&sin, sizeof( sin )) < 0 ) {
   std::cout << "Error on connection: " << strerror(errno) << std::endl;
   ::exit(-1);
 }

 int optval = 1;
 socklen_t optlen = sizeof(optval);

 /*Enabling keep alive*/
 if(setsockopt(mySocket, SOL_SOCKET, SO_KEEPALIVE, &optval, optlen) < 0) {
   std::cout << "Error setting SO_KEEPALIVE: " << strerror(errno) << std::endl;
 }

 optval = 5;
 optlen = sizeof(optval);
 if(setsockopt(mySocket, SOL_TCP, TCP_KEEPIDLE, &optval, optlen) < 0) {
    std::cout << "Error setting TCP_KEEPIDLE: " << strerror(errno) << std::endl;
 }

 optval = 5;
 optlen = sizeof(optval);
 if(setsockopt(mySocket, SOL_TCP, TCP_KEEPCNT, &optval, optlen) < 0) {
   std::cout << "Error setting TCP_KEEPCNT: " << strerror(errno) << std::endl;
 }

 optval = 1;
 optlen = sizeof(optval);
 if(setsockopt(mySocket, SOL_TCP, TCP_KEEPINTVL, &optval, optlen) < 0) {
   std::cout << "Error setting TCP_KEEPINTVL: " << strerror(errno) << std::endl;
 }

 for (;;) {
   ssize_t myRet= ::send(mySocket,
                                      myVector,
                                      sizeof(myVector),
                                     0);
   if (myRet < 0) {
     std::cout << "Error: " << strerror(errno) << std::endl;
     break;
   }
   std::cout << myRet << "."; std::cout.flush();
   sleep(1);
 }
}

我敢肯定，我失去了一些东西，但什么？

I'm sure I'm missing something, but what ?

推荐答案

TCP保持不用于这种用途。

TCP Keepalive isn't intended for this use.

如果要检测应用层中断，做什么样的SSH，IMAP和IRC协议做 - 实现在应用层回声/平类型的消息。给他们定期，如果没有得到及时回复，连接可以被认为是了。

If you want to detect outages at the application layer, do what protocols like SSH, IMAP and IRC do - implement an echo/ping type message at the application layer. Send them on a regular basis, and if you don't get a timely reply, the connection can be assumed to be down.

这篇关于插座，检测连接丢失的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！