C# class to parse WebRequestMethods.Ftp.ListDirectoryDetails FTP response

For the first (DOS/Windows) listing this code will do:

FtpWebRequest request = (FtpWebRequest)WebRequest.Create("ftp://ftp.example.com/");
request.Credentials = new NetworkCredential("user", "password");
request.Method = WebRequestMethods.Ftp.ListDirectoryDetails;
StreamReader reader = new StreamReader(request.GetResponse().GetResponseStream());

string pattern = @"^(\d+-\d+-\d+\s+\d+:\d+(?:AM|PM))\s+(<DIR>|\d+)\s+(.+)$";
Regex regex = new Regex(pattern);
IFormatProvider culture = CultureInfo.GetCultureInfo("en-us");
while (!reader.EndOfStream)
{
    string line = reader.ReadLine();
    Match match = regex.Match(line);
    string s = match.Groups[1].Value;
    DateTime modified =
        DateTime.ParseExact(s, "MM-dd-yy  hh:mmtt", culture, DateTimeStyles.None);
    s = match.Groups[2].Value;
    long size = (s != "<DIR>") ? long.Parse(s) : 0;
    string name = match.Groups[3].Value;

    Console.WriteLine(
        "{0,-16} size = {1,9}  modified = {2}",
        name, size, modified.ToString("yyyy-MM-dd HH:mm"));
}

You will get:

Version2         size =         0  modified = 2011-08-10 12:02
image34.gif      size = 144700153  modified = 2009-06-25 14:41
updates.txt      size = 144700153  modified = 2009-06-25 14:51
digger.tif       size = 144700214  modified = 2010-11-04 14:45

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For the other (*nix) listing, see my answer to Parsing FtpWebRequest ListDirectoryDetails line.

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But, actually trying to parse the listing returned by the ListDirectoryDetails is not the right way to go.

You want to use an FTP client that supports the modern MLSD command that returns a directory listing in a machine-readable format specified in the RFC 3659. Parsing the human-readable format returned by the ancient LIST command (used internally by the FtpWebRequest for its ListDirectoryDetails method) should be used as the last resort option, when talking to obsolete FTP servers, that do not support the MLSD command (like the Microsoft IIS FTP server).

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For example with WinSCP .NET assembly, you can use its Session.ListDirectory or Session.EnumerateRemoteFiles methods.

They internally use the MLSD command, but can fall back to the LIST command and support dozens of different human-readable listing formats.

The returned listing is presented as collection of RemoteFileInfo instances with properties like:

• Name
• LastWriteTime (with correct timezone)
• Length
• FilePermissions (parsed into individual rights)
• Group
• Owner
• IsDirectory
• IsParentDirectory
• IsThisDirectory

(I’m the author of WinSCP)

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Most other 3rd party libraries will do the same. Using the FtpWebRequest class is not reliable for this purpose. Unfortunately, there’s no other built-in FTP client in the .NET framework.