Improve WebDAV/S3 data sync request timeout settings

[FreeBoy-V-V]

使用IPV6的DNS解析慢导致云端同步失败

Is there an existing issue for this?

• I have searched the existing issues

Can the issue be reproduced with the default theme (daylight/midnight)?

• I was able to reproduce the issue with the default theme

Could the issue be due to extensions?

• I've ruled out the possibility that the extension is causing the problem.

Describe the problem

1、在“设置”->“云端”配置页面，将“云端存储服务提供商”设置为S3，将“Endpoint”设置为内网IPv4地址，“Timeout (s)”配置为30s，在设置“云端同步目录”时，可以在1秒内获取到存储目录并配置，手工点击“同步”时，可以正常同步。
2、流程同上，其他配置不变，将“Endpoint”设置为IPv6地址对应的DNS域名，可以在30秒内获取到存储目录并配置，手工点击“同步”时，提示“云端存储服务提供商网络连通性校验异常，请检查网络配置 (Provider: S3) v3.1.8”。
3、查看日志，见日志文件，错误位置是：kernel\util\net.go 136行，错误信息是：context deadline exceeded
4、通过错误查找，需要优化的是：kernel\util\net.go 108行，c := req.C().SetTimeout(3 * time.Second)，默认的超时时间只有3秒，导致IPv6的DNS域名无法解析完成。

Expected result

kernel\util\net.go的isOnline方法检测云端存储服务是否在线时，使用配置的“Timeout (s)”时间或默认30s，可以正常同步数据。

Screenshot or screen recording presentation

No response

Version environment

- Version: 3.1.8
- Operating System: Windows 11, Microsoft Windows [版本 10.0.22631.4037]
- Browser (if used):

Log file

W 2024/10/08 14:54:08 net.go:136: check url [https://x.x.x:1234/] is online failed: Get "https://x.x.x:1234/": context deadline exceeded
W 2024/10/08 14:54:12 net.go:136: check url [https://x.x.x:1234/] is online failed: Get "https://x.x.x:1234/": context deadline exceeded (Client.Timeout exceeded while awaiting headers)
W 2024/10/08 14:54:12 net.go:90: network is offline [checkURL=https://x.x.x:1234/]

More information

kernel\util\net.go的isOnline方法如下：

func isOnline(checkURL string, skipTlsVerify bool) (ret bool) {
	c := req.C().SetTimeout(3 * time.Second)
	if skipTlsVerify {
		c.EnableInsecureSkipVerify()
	}
	c.SetUserAgent(UserAgent)

	for i := 0; i < 2; i++ {
		resp, err := c.R().Get(checkURL)

		if resp.GetHeader("Location") != "" {
			return true
		}

		switch err.(type) {
		case *url.Error:
			if err.(*url.Error).URL != checkURL {
				// DNS 重定向
				logging.LogWarnf("network is online [DNS redirect, checkURL=%s, retURL=%s]", checkURL, err.(*url.Error).URL)
				return true
			}
		}

		ret = err == nil
		if ret {
			break
		}

		time.Sleep(1 * time.Second)
		logging.LogWarnf("check url [%s] is online failed: %s", checkURL, err)
	}
	return
}

[Topikc1]

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