windows socket 设置connect的超时（附Linux平台connect超时设置)

linux平台下的socket 通过设置超时时间可以在connect的时候进行超时判断，而windows设置超时对connect不起作用，默认大概是16s。

以下是windows平台下connect超时的示例代码。可以直接编译运行。

 

#include <Winsock2.h>
#include <iostream>

#pragma comment(lib,"ws2_32.lib")


bool connect(char *host, int port, int timeout=3)
{
	TIMEVAL Timeout;
	Timeout.tv_sec = timeout;
	Timeout.tv_usec = 0;
	struct sockaddr_in address;  /* the libc network address data structure */

	SOCKET sock = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);

	address.sin_addr.s_addr = inet_addr(host); /* assign the address */
	address.sin_port = htons(port);            /* translate int2port num */
	address.sin_family = AF_INET;

	//set the socket in non-blocking
	unsigned long iMode = 1;
	int iResult = ioctlsocket(sock, FIONBIO, &iMode);
	if (iResult != NO_ERROR)
	{
		printf("ioctlsocket failed with error: %ld\n", iResult);
	}

	if (connect(sock, (struct sockaddr *)&address, sizeof(address)) == false)
	{
		return false;
	}

	// restart the socket mode
	iMode = 0;
	iResult = ioctlsocket(sock, FIONBIO, &iMode);
	if (iResult != NO_ERROR)
	{
		printf("ioctlsocket failed with error: %ld\n", iResult);
	}

	fd_set Write, Err;
	FD_ZERO(&Write);
	FD_ZERO(&Err);
	FD_SET(sock, &Write);
	FD_SET(sock, &Err);

	// check if the socket is ready
	select(0, NULL, &Write, &Err, &Timeout);
	if (FD_ISSET(sock, &Write))
	{
		return true;
	}

	return false;
}

using namespace std;

int main()
{
	while (1)
	{
		bool ret = false;
		ret = connect("www.baidu.com", 800);
		if(ret )
		{
			printf("sucess\n");
		}
		else printf("failed\n");
		ret = connect("192.168.1.200", 80);
		if (ret)
		{
			printf("sucess\n");
		}
		else printf("failed\n");
	}
	return 0;
}



#ifdef WIN32
class WSInit
{
public:
	WSInit()
	{
		WSADATA wsadata;
		WSAStartup(MAKEWORD(2, 2), &wsadata);
	}

	~WSInit() { WSACleanup(); }
};

static WSInit wsinit_;
#endif

linux平台connect超时设置的示例：

参考http://ju.outofmemory.cn/entry/136595

经测试可以正常使用。简洁明了。

int connect_timeout_v3(int sock, struct sockaddr *addr, int timeout) {
        int ret;
        struct timeval timeo = {3, 0};
        socklen_t len = sizeof(timeo);
        ret = setsockopt(sock, SOL_SOCKET, SO_SNDTIMEO, &timeo, len);
        if (ret) {
                printf("set socket opt failed!\n");
        }
        ret = connect(sock, addr, sizeof(struct sockaddr_in));
        return ret;
}

 引用：

https://www.codeproject.com/tips/168704/how-to-set-a-socket-connection-timeout

 

不得不说国内有些人真的是水平太差，错误代码也往网上放，https://blog.youkuaiyun.com/cupidove/article/details/43953603/

下面这个是有问题的：https://blog.youkuaiyun.com/cupidove/article/details/43953603/