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c# - FtpWebRequest 30分钟超时

通过FTP下载大文件时，恰好30分钟后，我的代码遇到超时异常。该服务器是Windows上运行的FileZilla。我们有一个配置了Enable FTP over SSL/TLS support (FTPS)和Allow explicit FTP over TLS选项的SSL证书。我可以访问服务器和FileZilla配置，但是看不到任何可能导致此问题的内容。以下是在Windows 2012 Server计算机上的.NET 4.6.2上运行的源代码。它可以从FTP服务器下载文件，但是如果文件下载时间超过30分钟，则将在30分钟后超时(异常(exception))(以下列出)。

作为测试，我使用了从同一台客户端PC运行的FileZilla Client从同一服务器端点同时下载多个大文件，因此每个文件的下载花费了30分钟以上的时间才能完成。在这种情况下没有发生错误。

我已经搜索了StackOverflow和Google，但没有找到希望的结果。如果有人对服务器的外观(服务器端或客户端)有一些建议，我将非常感激。

申请代码

public class FtpFileDownloader
{
    // log4net
    private static readonly ILog Logger = LogManager.GetLogger(typeof(FtpFileDownloader));

    public void DownloadFile()
    {
        // setting the SecurityProtocol did not change the outcome, both were tried. Originally it was not set at all.
        // ServicePointManager.SecurityProtocol = SecurityProtocolType.Ssl3;
        ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls12;


        ServicePointManager.ServerCertificateValidationCallback = (sender, certificate, chain, sslPolicyErrors) => true;

        const int timeout = 7200000;
        const string file = "some-existing-file";
        try
        {
            var request = (FtpWebRequest) WebRequest.Create("uri-path-to-file");
            request.KeepAlive = false;
            request.Timeout = -1;
            request.ReadWriteTimeout = timeout;

            request.Credentials = new NetworkCredential("userName", "password");
            request.UsePassive = true;
            request.EnableSsl = true;
            request.Method = WebRequestMethods.Ftp.DownloadFile;

            Logger.Debug($"Downloading '{file}'");
            using (var response = (FtpWebResponse) request.GetResponse())
            using (var sourceStream = response.GetResponseStream())
            using (var targetStream = new FileStream("some-target-on-disk", FileMode.Create, FileAccess.Write))
            {
                try
                {
                    sourceStream.CopyTo(targetStream);
                    targetStream.Flush();
                    Logger.Debug($"Finished download '{file}'");
                }
                catch (Exception exInner)
                {
                    Logger.Error($"Error occurred trying to download file '{file}'.", exInner);
                }
            }
        }
        catch (Exception ex)
        {
            Logger.Error($"Error occurred trying to dispose streams when downloading file '{file}'.", ex);
        }
    }
}

应用日志
ERROR FtpFileDownloader - Error occurred trying to download file 'some-existing-file'.
System.IO.IOException: Received an unexpected EOF or 0 bytes from the transport stream.
   at System.Net.FixedSizeReader.ReadPacket(Byte[] buffer, Int32 offset, Int32 count)
   at System.Net.Security._SslStream.StartFrameBody(Int32 readBytes, Byte[] buffer, Int32 offset, Int32 count, AsyncProtocolRequest asyncRequest)
   at System.Net.Security._SslStream.StartFrameHeader(Byte[] buffer, Int32 offset, Int32 count, AsyncProtocolRequest asyncRequest)
   at System.Net.Security._SslStream.StartReading(Byte[] buffer, Int32 offset, Int32 count, AsyncProtocolRequest asyncRequest)
   at System.Net.Security._SslStream.ProcessRead(Byte[] buffer, Int32 offset, Int32 count, AsyncProtocolRequest asyncRequest)
   at System.Net.TlsStream.Read(Byte[] buffer, Int32 offset, Int32 size)
   at System.Net.FtpDataStream.Read(Byte[] buffer, Int32 offset, Int32 size)
   at System.IO.Stream.InternalCopyTo(Stream destination, Int32 bufferSize)
   at System.IO.Stream.CopyTo(Stream destination)
   at FtpFileDownloader.DownloadFile

ERROR FtpFileDownloader - Error occurred trying to dispose streams when downloading file 'some-existing-file'.
System.Net.WebException: The underlying connection was closed: An unexpected error occurred on a receive.
   at System.Net.FtpWebRequest.SyncRequestCallback(Object obj)
   at System.Net.FtpWebRequest.RequestCallback(Object obj)
   at System.Net.CommandStream.Dispose(Boolean disposing)
   at System.IO.Stream.Close()
   at System.IO.Stream.Dispose()
   at System.Net.ConnectionPool.Destroy(PooledStream pooledStream)
   at System.Net.ConnectionPool.PutConnection(PooledStream pooledStream, Object owningObject, Int32 creationTimeout, Boolean canReuse)
   at System.Net.FtpWebRequest.FinishRequestStage(RequestStage stage)
   at System.Net.FtpWebRequest.SyncRequestCallback(Object obj)
   at System.Net.FtpWebRequest.RequestCallback(Object obj)
   at System.Net.CommandStream.Abort(Exception e)
   at System.Net.CommandStream.CheckContinuePipeline()
   at System.Net.FtpWebRequest.DataStreamClosed(CloseExState closeState)
   at System.Net.FtpDataStream.System.Net.ICloseEx.CloseEx(CloseExState closeState)
   at System.Net.FtpDataStream.Dispose(Boolean disposing)
   at System.IO.Stream.Close()
   at System.IO.Stream.Dispose()
   at FtpFileDownloader.DownloadFile

FileZilla-常规设置
 Listen on these ports: 21
  Max. number of users: 0 (infinite)
     Number of threads: 2
    Connection timeout: 120 (seconds)
   No Transfer timeout: 9000 (seconds)
           Log timeout: 60 (seconds)

FileZilla服务器日志
23-2-2018 11:40:40 - (not logged in) (194.123.75.2)> Connected on port 21, sending welcome message...
23-2-2018 11:40:40 - (not logged in) (194.123.75.2)> 220 Welcome
23-2-2018 11:40:40 - (not logged in) (194.123.75.2)> AUTH TLS
23-2-2018 11:40:40 - (not logged in) (194.123.75.2)> 234 Using authentication type TLS
23-2-2018 11:40:40 - (not logged in) (194.123.75.2)> TLS connection established
23-2-2018 11:40:40 - (not logged in) (194.123.75.2)> USER  my-user-account
23-2-2018 11:40:40 - (not logged in) (194.123.75.2)> 331 Password required for my-user-account
23-2-2018 11:40:40 - (not logged in) (194.123.75.2)> PASS **************
23-2-2018 11:40:40 - my-user-account (194.123.75.2)> 230 Logged on
23-2-2018 11:40:40 - my-user-account (194.123.75.2)> PBSZ 0
23-2-2018 11:40:40 - my-user-account (194.123.75.2)> 200 PBSZ=0
23-2-2018 11:40:40 - my-user-account (194.123.75.2)> PROT P
23-2-2018 11:40:40 - my-user-account (194.123.75.2)> 200 Protection level set to P
23-2-2018 11:40:40 - my-user-account (194.123.75.2)> OPTS utf8 on
23-2-2018 11:40:40 - my-user-account (194.123.75.2)> 202 UTF8 mode is always enabled. No need to send this command.
23-2-2018 11:40:40 - my-user-account (194.123.75.2)> PWD
23-2-2018 11:40:40 - my-user-account (194.123.75.2)> 257 "/" is current directory.
23-2-2018 11:40:40 - my-user-account (194.123.75.2)> TYPE I
23-2-2018 11:40:40 - my-user-account (194.123.75.2)> 200 Type set to I
23-2-2018 11:40:40 - my-user-account (194.123.75.2)> PASV
23-2-2018 11:40:40 - my-user-account (194.123.75.2)> 227 Entering Passive Mode (IP-ADDRESS,245,222)
23-2-2018 11:40:40 - my-user-account (194.123.75.2)> RETR path-to-file
23-2-2018 11:40:40 - my-user-account (194.123.75.2)> 150 Opening data channel for file download from server of "/path-to-file"
23-2-2018 11:40:40 - my-user-account (194.123.75.2)> TLS connection for data connection established
23-2-2018 12:10:41 - my-user-account (194.123.75.2)> disconnected.

请注意，断开连接(最后一行)和它之前的那一行之间有30分钟的间隔。如果它成功完成了传输，那么在226 Successfully transferred "/path-to-file"行之前还会有一行读取disconnected的行

进度更新:
  • (2018.02.20)我要求我们的网络团队检查防火墙规则，但他们找不到任何有趣的东西。
  • (2018.02.22)我发现正在使用的FileZilla Server的版本为0.9.43 beta(根据更改日志的发布日期为2014-01-02)。尽管我在更改日志中没有发现任何暗示此行为的固定错误，但我将升级到最新版本0.9.60.2(发布日期2017-02-08)，然后再次执行测试。会在24小时内返回。
  • (2018.02.23)FileZilla已更新至最新版本。这不能解决问题，我更新了服务器日志，但它看起来与以前的日志几乎相同，除了最后一次传输是通过TLS而非SSL进行的。
  • (2018.02.23)我在FileZilla支持页面上找到以下链接Timeouts on large files。我将把它推回给托管服务提供商的网络人员，以进行另一番研究。
  • (2018.02.27)原来是公司防火墙(客户端执行网络)而不是托管防火墙(托管FileZilla的网络)。它被配置为在1800秒后删除空闲连接。已添加规则以覆盖这两个端点之间的规则。


    • 罪犯/答案

    原来，公司防火墙(客户端执行的网络)而不是托管防火墙(托管FileZilla的网络)是罪魁祸首。它被配置为在1800秒后删除空闲连接。已添加规则以覆盖这两个端点之间的规则。

    最佳答案

    可能您应该尝试另一种不在FtpWebRequest之上构建的FTP协议(protocol)客户端的实现。

    相关问题存在很长时间，没有明确的解决方案或答案。所以我会尝试类似FluentFTP的方法，它直接使用Winsock API。 XML文档注释指出DownloadFile()应该可以很好地处理大文件下载:

    /// <summary>
/// Downloads the specified file onto the local file system.
/// High-level API that takes care of various edge cases internally.
/// Supports very large files since it downloads data in chunks.
/// </summary>

    有关更多信息，请检查:
  • Downloading large files(~150MB) from FTP server hangs关于StackOverflow的讨论
    • Matt Mitchell的
  • FtpWebRequest is Broken文章
    • Microsoft TechNet上的
  • Winsock API页面
    • Elmue 在Partial FTP Downloader文章中的
  • 源代码部分

    关于c# - FtpWebRequest 30分钟超时，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/48814826/

    • 10-09 06:57
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