为什么 FtpWebRequest 为这个现有目录返回一个空流

问题描述

I'm not sure why am I getting this result. I'm running this on a Linux server. (It's my small web site's shared web hosting account.)

The files are grouped as follows:

and the Another Dir has one file inside:

So I'm trying to retrieve the contents of the badname directory inside 1somelongdir1234567 directory that doesn't exist on the server, using this code:

try
{
    FtpWebRequest ftpRequest = (FtpWebRequest)WebRequest.Create(
        "ftp://server12.some-domain.com/public_html/1somelongdir1234567/badname");
    ftpRequest.EnableSsl = true;
    ftpRequest.Credentials = new NetworkCredential("user", "password");
    ftpRequest.KeepAlive = true;
    ftpRequest.Timeout = -1;

    ftpRequest.Method = WebRequestMethods.Ftp.ListDirectoryDetails;

    using (FtpWebResponse response1 = (FtpWebResponse)ftpRequest.GetResponse())
    {
        //*****BEGIN OF EDIT*****
        Console.WriteLine(response1.StatusDescription);
        Console.WriteLine(response1.StatusCode);
        //*****END OF EDIT*****

        using (StreamReader streamReader = new StreamReader(response1.GetResponseStream()))
        {
            List<string> arrList = new List<string>();

            for (; ; )
            {
                string line = streamReader.ReadLine();

                //I get to here, where `line` is null????

                if (string.IsNullOrEmpty(line))
                    break;

                arrList.Add(line);

                //*****BEGIN OF EDIT*****
                Console.WriteLine(line);
                //*****END OF EDIT*****
            }
        }
    }
}
catch (Exception ex)
{
    Console.WriteLine(ex.Message);
}

So as you see, there's no such folder badname but instead of throwing an exception, my ftpRequest.GetResponse() succeeds and then streamReader.ReadLine() returns null like I showed in the code above.

More strangely, if I provide an actual directory as such:

    FtpWebRequest ftpRequest = (FtpWebRequest)WebRequest.Create(
        "ftp://server12.some-domain.com/public_html/1somelongdir1234567/Another%20Dir");

the streamReader.ReadLine() still returns null.

Can someone explain why?

Edit: OK, guys, I updated the code above to retrieve the status code. I'm still puzzled though.

First, here's three values of connection URI and the response/output that I'm getting:

Example 1:

//Existing folder
"ftp://server12.some-domain.com/public_html/1somelongdir1234567"

Output:

150 Accepted data connection

OpeningData
drwxr-xr-x    3 username   username         4096 Sep  5 05:51 .
drwxr-x---  118 username   99               4096 Sep  5 05:54 ..
drwxr-xr-x    2 username   username         4096 Sep  5 05:52 Another Dir
-rw-r--r--    1 username   username           11 Sep  5 05:51 test123.txt

Example 2:

//Another existing folder
"ftp://server12.some-domain.com/public_html/1somelongdir1234567/Another%20Dir"

Output:

150 Accepted data connection

OpeningData

Example 3:

//Nonexistent folder
"ftp://server12.some-domain.com/public_html/1somelongdir1234567/SomeBogusName"

Output:

150 Accepted data connection

OpeningData

So why is it giving me the same result for example 2 as I'm getting for 3?

As for what ftp server it is, I wasn't able to see it in the network logs nor in FtpWebRequest itself. Here's what I was able to get from Microsoft Network Monitor:

Welcome to Pure-FTPd [privsep] [TLS] ----------..
220-You are user number 4 of 50 allowed... 220-Local time is now 13:14. Server port: 21...
220-This is a private system - No anonymous login..
220-IPv6 connections are also welcome on this server...
220 You will be disconnected after 15 minutes of inactivity...

The URL for the ListDirectory/ListDirectoryDetails method should end with a slash, in general.

Without a slash, results tend to be uncertain.

WebRequest.Create("ftp://example.com/public_html/1somelongdir1234567/Another%20Dir/");

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