socket重启端口被占用

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我是靠谱客的博主个性吐司，这篇文章主要介绍socket重启端口被占用，现在分享给大家，希望可以做个参考。

问题描述：

代码是linux上一个socket服务器端，客户端与其建立连接；Ctrl+c 结束socket服务器。再次重启服务器后，端口被占用，bind失败（Address already in use）；需经过大约2分钟后，重启服务器方能再次使用。

问题分析：

因为socket结束后，linux会保留此端口一定时间，据说是1~4分钟；过后才能再次被使用。

处理方法：

设置SO_REUSEADDR选项可以解决此问题，关闭socket后可立即再使用端口。代码如下：

复制代码

int Socket_base::SocketInit(void)
{
	int 				serverSocketFd = -1;
	int 				serverLen = 0; 
	struct sockaddr_in 	serverAddress;	// sockaddr_in for AF_INET

/* Create and name a socket for the server. */
	m_serverSocketFd = socket(AF_INET, SOCK_STREAM, 0);

// use SO_REUSEADDR, so may use the port again immediately after restarting the socket
	int optval = 1;
	if (setsockopt(m_serverSocketFd, SOL_SOCKET, SO_REUSEADDR, &optval, sizeof(optval)) < 0) 
	{
		perror("setsockopt error");
	}
	
	int flags = fcntl(m_serverSocketFd, F_GETFL, 0);		// get file flag
	fcntl(m_serverSocketFd, F_SETFL, flags | O_NONBLOCK);	// set file Non-blocking, for "accept" use in while

serverAddress.sin_family 		= AF_INET;
	serverAddress.sin_addr.s_addr 	= htonl(INADDR_ANY);
	serverAddress.sin_port 			= htons(SOCKET_PORT);
	serverLen = sizeof(serverAddress);

if((bind(m_serverSocketFd, (struct sockaddr *)&serverAddress, serverLen)) < 0)
	{
		perror("bind error");
	}
	/* Create a connection queue and initialize readFds to handle input from serverSocketFd. */
	listen(m_serverSocketFd, 0);	
}

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int Socket_base::SocketInit(void)
{
	int 				serverSocketFd = -1;
	int 				serverLen = 0; 
	struct sockaddr_in 	serverAddress;	// sockaddr_in for AF_INET

	/* Create and name a socket for the server. */
	m_serverSocketFd = socket(AF_INET, SOCK_STREAM, 0);

	// use SO_REUSEADDR, so may use the port again immediately after restarting the socket
	int optval = 1;
	if (setsockopt(m_serverSocketFd, SOL_SOCKET, SO_REUSEADDR, &optval, sizeof(optval)) < 0) 
	{
		perror("setsockopt error");
	}
	
	int flags = fcntl(m_serverSocketFd, F_GETFL, 0);		// get file flag
	fcntl(m_serverSocketFd, F_SETFL, flags | O_NONBLOCK);	// set file Non-blocking, for "accept" use in while

	serverAddress.sin_family 		= AF_INET;
	serverAddress.sin_addr.s_addr 	= htonl(INADDR_ANY);
	serverAddress.sin_port 			= htons(SOCKET_PORT);
	serverLen = sizeof(serverAddress);

	if((bind(m_serverSocketFd, (struct sockaddr *)&serverAddress, serverLen)) < 0)
	{
		perror("bind error");
	}
	/* Create a connection queue and initialize readFds to handle input from serverSocketFd. */
	listen(m_serverSocketFd, 0);	
}