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How to Use Managed Code (C#) to Create an FTP Home Directory Provider for the Days of the Week

How to Use Managed Code (C#) to Create an FTP Home Directory Provider for the Days of the Week

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I had a question from someone that had an interesting scenario: they had a series of reports that their manufacturing company generates on a daily basis, and they wanted to automate uploading those files over FTP from their factory to their headquarters. Their existing automation created report files with names like Widgets.log, Sprockets.log, Gadgets.log, etc.

But they had an additional request: they wanted the reports dropped into folders based on the day of the week. People in their headquarters could retrieve the reports from a share on their headquarters network where the FTP server would drop the files, and anyone could look at data from anytime within the past seven days.

This seemed like an extremely trivial script for me to write, so I threw together the following example batch file for them:

@echo off
pushd "C:\Reports"
for /f "usebackq delims= " %%a in (`date /t`) do (
  echo open MyServerName>ftpscript.txt
  echo MyUsername>>ftpscript.txt
  echo MyPassword>>ftpscript.txt
  echo mkdir %%a>>ftpscript.txt
  echo cd %%a>>ftpscript.txt
  echo asc>>ftpscript.txt
  echo prompt>>ftpscript.txt
  echo mput *.log>>ftpscript.txt
  echo bye>>ftpscript.txt
)
ftp.exe -s:ftpscript.txt
del ftpscript.txt
popd

This would have worked great for most scenarios, but they pointed out a few problems in their specific environment: manufacturing and headquarters were in different geographical regions of the world, therefore in different time zones, and they wanted the day of the week to be based on the day of the week where their headquarters was located. They also wanted to make sure that if anyone logged in over FTP, they would only see the reports for the current day, and they didn't want to take a chance that something might go wrong with the batch file and they might overwrite the logs from the wrong day.

With all of those requirements in mind, this was beginning to look like a problem for a custom home directory provider to tackle. Fortunately, this was a really easy home directory provider to write, and I thought that it might make a good blog.

Note: I wrote and tested the steps in this blog using both Visual Studio 2010 and Visual Studio 2008; if you use an different version of Visual Studio, some of the version-specific steps may need to be changed.

In This Blog

Prerequisites

The following items are required to complete the procedures in this blog:

  1. The following version of IIS must be installed on your Windows computer, and the Internet Information Services (IIS) Manager must also be installed:
    • IIS 7.0 must be installed on Windows Server 2008
    • IIS 7.5 must be installed on Windows Server 2008 R2 or Windows 7
  2. The new FTP 7.5 service must be installed. To install FTP 7.5, follow the instructions in the following topic:
  3. You must have FTP publishing enabled for a site. To create a new FTP site, follow the instructions in the following topic:
  4. You need to create the folders for the days of the week under your FTP root directory; for example, Sunday, Monday, Tuesday, etc.

Step 1: Set up the Project Environment

In this step, you will create a project in Microsoft Visual Studio for the demo provider.

  1. Open Visual Studio 2008 or Visual Studio 2010.
  2. Click the File menu, then New, then Project.
  3. In the New Projectdialog box:
    • Choose Visual C# as the project type.
    • Choose Class Library as the template.
    • Type FtpDayOfWeekHomeDirectory as the name of the project.
    • Click OK.
  4. When the project opens, add a reference path to the FTP extensibility library:
    • Click Project, and then click FtpDayOfWeekHomeDirectory Properties.
    • Click the Reference Paths tab.
    • Enter the path to the FTP extensibility assembly for your version of Windows, where C: is your operating system drive.
      • For Windows Server 2008 and Windows Vista:
        • C:\Windows\assembly\GAC_MSIL\Microsoft.Web.FtpServer\7.5.0.0__31bf3856ad364e35
      • For 32-bit Windows 7 and Windows Server 2008 R2:
        • C:\Program Files\Reference Assemblies\Microsoft\IIS
      • For 64-bit Windows 7 and Windows Server 2008 R2:
        • C:\Program Files (x86)\Reference Assemblies\Microsoft\IIS
    • Click Add Folder.
  5. Add a strong name key to the project:
    • Click Project, and then click FtpDayOfWeekHomeDirectory Properties.
    • Click the Signing tab.
    • Check the Sign the assembly check box.
    • Choose <New...> from the strong key name drop-down box.
    • Enter FtpDayOfWeekHomeDirectoryKey for the key file name.
    • If desired, enter a password for the key file; otherwise, clear the Protect my key file with a password check box.
    • Click OK.
  6. Note: FTP 7.5 Extensibility does not support the .NET Framework 4.0; if you are using Visual Studio 2010, or you have changed your default framework version, you may need to change the framework version for this project. To do so, use the following steps:
    • Click Project, and then click FtpDayOfWeekHomeDirectory Properties.
    • Click the Application tab.
    • Choose .NET Framework 3.5 in the Target framework drop-down menu.
    • Save, close, and re-open the project.
  7. Optional: You can add a custom build event to add the DLL automatically to the Global Assembly Cache (GAC) on your development computer:
    • Click Project, and then click FtpDayOfWeekHomeDirectory Properties.
    • Click the Build Events tab.
    • Enter the appropriate commands in the Post-build event command linedialog box, depending on your version of Visual Studio:
      • If you are using Visual Studio 2010:
        net stop ftpsvc
        call "%VS100COMNTOOLS%\vsvars32.bat">null
        gacutil.exe /if "$(TargetPath)"
        net start ftpsvc
      • If you are using Visual Studio 2008:
        net stop ftpsvc
        call "%VS90COMNTOOLS%\vsvars32.bat">null
        gacutil.exe /if "$(TargetPath)"
        net start ftpsvc
      Note: You need to be logged in as an administrator in order to restart the FTP service and add the dll to the Global Assembly Cache.
  8. Save the project.

Step 2: Create the Extensibility Class

In this step, you will implement the extensibility interfaces for the demo provider.

  1. Add the necessary references to the project:
    • Click Project, and then click Add Reference...
    • On the .NET tab, click Microsoft.Web.FtpServer.
    • Click OK.
  2. Add the code for the authentication class:
    • In Solution Explorer, double-click the Class1.cs file.
    • Remove the existing code.
    • Paste the following code into the editor:
      using System;
      using System.Collections.Generic;
      using System.Collections.Specialized;
      using Microsoft.Web.FtpServer;
      
      public class FtpDayOfWeekHomeDirectory :
          BaseProvider,
          IFtpHomeDirectoryProvider
      {
          // Store the path to the default FTP folder.
          private static string _defaultDirectory = string.Empty;
      
          // Override the default initialization method.
          protected override void Initialize(StringDictionary config)
          {
              // Retrieve the default directory path from configuration.
              _defaultDirectory = config["defaultDirectory"];
              // Test for the default home directory (Required).
              if (string.IsNullOrEmpty(_defaultDirectory))
              {
                  throw new ArgumentException(
                    "Missing default directory path in configuration.");
              }
          }
      
          // Define the home directory provider method.
          string IFtpHomeDirectoryProvider.GetUserHomeDirectoryData(
              string sessionId,
              string siteName,
              string userName)
          {
              // Return the path to the folder for the day of the week.
              return String.Format(
                  @"{0}\{1}",
                  _defaultDirectory,
                  DateTime.Today.DayOfWeek);
          }
      }
  3. Save and compile the project.

Note: If you did not use the optional steps to register the assemblies in the GAC, you will need to manually copy the assemblies to your IIS 7 computer and add the assemblies to the GAC using the Gacutil.exe tool. For more information, see the following topic on the Microsoft MSDN Web site:

Global Assembly Cache Tool (Gacutil.exe)

Step 3: Add the Demo Provider to FTP

In this step, you will add your provider to the global list of custom providers for your FTP service, configure your provider's settings, and enable your provider for an FTP site.

Adding your Provider to FTP

  1. Determine the assembly information for your extensibility provider:
    • In Windows Explorer, open your "C:\Windows\assembly" path, where C: is your operating system drive.
    • Locate the FtpDayOfWeekHomeDirectory assembly.
    • Right-click the assembly, and then click Properties.
    • Copy the Culture value; for example: Neutral.
    • Copy the Version number; for example: 1.0.0.0.
    • Copy the Public Key Token value; for example: 426f62526f636b73.
    • Click Cancel.
  2. Add the extensibility provider to the global list of FTP authentication providers:
    • Open the Internet Information Services (IIS) Manager.
    • Click your computer name in the Connections pane.
    • Double-click FTP Authentication in the main window.
    • Click Custom Providers... in the Actions pane.
    • Click Register.
    • Enter FtpDayOfWeekHomeDirectory for the provider Name.
    • Click Managed Provider (.NET).
    • Enter the assembly information for the extensibility provider using the information that you copied earlier. For example:
      FtpDayOfWeekHomeDirectory,FtpDayOfWeekHomeDirectory,version=1.0.0.0,Culture=neutral,PublicKeyToken=426f62526f636b73
    • Click OK.
    • Clear the FtpDayOfWeekHomeDirectory check box in the providers list.
    • Click OK.

Note: If you prefer, you could use the command line to add the provider to FTP by using syntax like the following example:

cd %SystemRoot%\System32\Inetsrv

appcmd.exe set config -section:system.ftpServer/providerDefinitions /+"[name='FtpDayOfWeekHomeDirectory',type='FtpDayOfWeekHomeDirectory,FtpDayOfWeekHomeDirectory,version=1.0.0.0,Culture=neutral,PublicKeyToken=426f62526f636b73']" /commit:apphost

Configuring your Provider's Settings

At the moment there is no user interface that allows you to configure properties for a custom home directory provider, so you will have to use the following command line:

cd %SystemRoot%\System32\Inetsrv

appcmd.exe set config -section:system.ftpServer/providerDefinitions /+"activation.[name='FtpDayOfWeekHomeDirectory']" /commit:apphost

appcmd.exe set config -section:system.ftpServer/providerDefinitions /+"activation.[name='FtpDayOfWeekHomeDirectory'].[key='defaultDirectory',value='C:\Inetpub\ftproot']" /commit:apphost

Note: The highlighted area contains the value that you need to update with the root directory of your FTP site.

Enabling your Provider for an FTP site

At the moment there is no user interface that allows you to enable a custom home directory provider for an FTP site, so you will have to use the following command line:

cd %SystemRoot%\System32\Inetsrv

appcmd.exe set config -section:system.applicationHost/sites /+"[name='My FTP Site'].ftpServer.customFeatures.providers.[name='FtpDayOfWeekHomeDirectory']" /commit:apphost

appcmd.exe set config -section:system.applicationHost/sites /"[name='My FTP Site'].ftpServer.userIsolation.mode:Custom" /commit:apphost

Note: The highlighted areas contain the name of the FTP site where you want to enable the custom home directory provider.

Summary

In this blog I showed you how to:

  • Create a project in Visual Studio 2010 or Visual Studio 2008 for a custom FTP home directory provider.
  • Implement the extensibility interface for custom FTP home directories.
  • Add a custom home directory provider to your FTP service.

When users connect to your FTP site, the FTP service will drop their session in the corresponding folder for the day of the week under the home directory for your FTP site, and they will not be able to change to the root directory or a directory for a different day of the week.

Comments
  • Can you explain when IFtpHomeDirectoryProvider.GetUserHomeDirectoryData is called?

    It is called when start a new session (called one time in one session) or when FTP client

    upload a file to FTP server in session (called many times in one session).

  • @DangNguyen - GetUserHomeDirectoryData is called only at the beginning of a session to establish the home directory for the current session; all operations for that session will use that home directory. If a client disconnects and reconnects, GetUserHomeDirectoryData will be called when the new sessions is established, which might get a different home directory (depending on what your implementation is trying to do).

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