#region License

// The PostgreSQL License

//

// Copyright (C) 2017 The Npgsql Development Team

//

// Permission to use, copy, modify, and distribute this software and its

// documentation for any purpose, without fee, and without a written

// agreement is hereby granted, provided that the above copyright notice

// and this paragraph and the following two paragraphs appear in all copies.

//

// IN NO EVENT SHALL THE NPGSQL DEVELOPMENT TEAM BE LIABLE TO ANY PARTY

// FOR DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES,

// INCLUDING LOST PROFITS, ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS

// DOCUMENTATION, EVEN IF THE NPGSQL DEVELOPMENT TEAM HAS BEEN ADVISED OF

// THE POSSIBILITY OF SUCH DAMAGE.

//

// THE NPGSQL DEVELOPMENT TEAM SPECIFICALLY DISCLAIMS ANY WARRANTIES,

// INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY

// AND FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS

// ON AN "AS IS" BASIS, AND THE NPGSQL DEVELOPMENT TEAM HAS NO OBLIGATIONS

// TO PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.

#endregion

using System;

using System.Diagnostics;

using System.IO;

using System.Linq;

using JetBrains.Annotations;

using Microsoft.Extensions.Logging;

using Npgsql.Logging;

namespace Npgsql

{

/// <summary>

/// Launches MIT Kerberos klist and parses out the default principal from it.

/// Caches the result.

/// </summary>

class KerberosUsernameProvider

{

static bool _performedDetection;

static string _principalWithRealm;

static string _principalWithoutRealm;

[CanBeNull]

internal static string GetUsername(bool includeRealm)

{

if (!_performedDetection)

{

DetectUsername();

_performedDetection = true;

}

return includeRealm ? _principalWithRealm : _principalWithoutRealm;

}

static void DetectUsername()

{

var klistPath = FindInPath("klist");

if (klistPath == null)

{

Log.Logger.LogDebug("klist not found in PATH, skipping Kerberos username detection");

return;

}

var processStartInfo = new ProcessStartInfo

{

FileName = klistPath,

RedirectStandardOutput = true,

RedirectStandardError = true,

UseShellExecute = false

};

var process = Process.Start(processStartInfo);

process.WaitForExit();

if (process.ExitCode != 0)

{

Log.Logger.LogDebug($"klist exited with code {process.ExitCode}: {process.StandardError.ReadToEnd()}");

return;

}

var line = "";

for (var i = 0; i < 2; i++)

if ((line = process.StandardOutput.ReadLine()) == null)

{

Log.Logger.LogDebug("Unexpected output from klist, aborting Kerberos username detection");

return;

}

var components = line.Split(':');

if (components.Length != 2)

{

Log.Logger.LogDebug("Unexpected output from klist, aborting Kerberos username detection");

return;

}

var principalWithRealm = components[1].Trim();

components = principalWithRealm.Split('@');

if (components.Length != 2)

{

Log.Logger.LogDebug($"Badly-formed default principal {principalWithRealm} from klist, aborting Kerberos username detection");

return;

}

_principalWithRealm = principalWithRealm;

_principalWithoutRealm = components[0];

}

static string FindInPath(string name) => Environment.GetEnvironmentVariable("PATH")

.Split(Path.PathSeparator)

.Select(p => Path.Combine(p, name))

.FirstOrDefault(File.Exists);

}

}