Read Windows user name & password from plain text file and execute command with those credentials

RunAsFromFile.cs

// .\CompileSimply-CSharp.ps1 . RunAsFromFile.cs "64" "System.Diagnostics.Process.dll"
//
// From https://social.technet.microsoft.com/Forums/lync/en-US/132e170f-e3e8-4178-9454-e37bfccd39ea/startprocess-verb-runas-amp-credential
// $pw= convertto-securestring "PASSWORD" -asplaintext –force
// $pp = new-object -typename System.Management.Automation.PSCredential -argumentlist "DOMAIN\user",$pw
// $script = "c:\pathtoscript.ps1"
// Start-Process powershell -Credential $pp -ArgumentList '-noprofile -command &{Start-Process $script -verb runas}'
// $pw= convertto-securestring "PASSWORD" -asplaintext –force
// $pp = new-object -typename System.Management.Automation.PSCredential -argumentlist "DOMAIN\user",$pw
// $script = "c:\pathtoscript.ps1"
// Start-Process powershell -Credential $pp -ArgumentList '-noprofile -command &{Start-Process $script -verb runas}'
using System;
using System.Collections.Generic;
using System.Diagnostics; // System.Diagnostics.Process.dll
using System.Security;

namespace runasfromfile
{
    class Program
    {
        static void Main(string[] args)
        {
            if (args.Length > 1) {
                var commandLine = new ArraySegment<string>(args, 1, args.Length - 1);
                cat(args[0],
                    (u, p) => { StartProcessAs(commandLine, u, p); });
            } else {
                Console.WriteLine("Please give a file name and a command as arguments");
            }
        }

        static void SplitUserAndDomain(string fullUserName, out string domain, out string user)
        {
            var defaultDomain = System.Environment.MachineName;
            var parts = fullUserName.Split('\\');
            if (1 == parts.Length)
            {
                domain = defaultDomain;
                user = fullUserName;
            }
            else if ("." == parts[0])
            {
                domain = defaultDomain;
                user = parts[1];
            }
            else
            {
                domain = parts[0];
                user = parts[1];
            }
        }

        static void StartProcessAs(ArraySegment<string> cmdLine, string fullUserName, string password)
        {
            var startInfo = new ProcessStartInfo();
            startInfo.UseShellExecute = false;
            startInfo.FileName = cmdLine.Array[cmdLine.Offset];
            startInfo.Arguments = String.Join(" ", cmdLine.Array, cmdLine.Offset + 1, cmdLine.Count - 1);
            string domain, user;
            SplitUserAndDomain(fullUserName, out domain, out user);
            startInfo.Domain = domain;
            startInfo.UserName = user;
            startInfo.PasswordInClearText = password;
            startInfo.WorkingDirectory = System.IO.Path.GetPathRoot(System.IO.Directory.GetCurrentDirectory());
            var proc = Process.Start(startInfo);
        }

        static bool MatchHeaderAndNotSet(string line, string header, SetOnce<string> value)
        {
            return (value.NotSet
                    && line.StartsWith(header,
                                       StringComparison.CurrentCultureIgnoreCase));
        }

        static string ButFirst(string x)
        {
            var parts = x.Split(" \t".ToCharArray(), 2);
            return parts[1].Trim();
        }

        static void cat(string arg, Action<string, string> callWithCredentials)
        {
            const string USERNAME = "username";
            const string PASSWORD = "password";
            var data = new Dictionary<string, SetOnce<string>>();
            data.Add(USERNAME, new SetOnce<string>());
            data.Add(PASSWORD, new SetOnce<string>());

            using(var file =
                  new System.IO.StreamReader(arg)) {
                string line;
                while((line = file.ReadLine()) != null)
                {
                    foreach (var item in data)
                    {
                        if (MatchHeaderAndNotSet(line, item.Key, item.Value)) {
                            item.Value.Set(ButFirst(line));
                            break;
                        }
                    }
                }
                var username = data[USERNAME];
                var password = data[PASSWORD];
                if (username.IsSet && password.IsSet) {
                    callWithCredentials(username.Value, password.Value);
                } else if (username.NotSet && password.NotSet) {
                    Console.WriteLine("Neither username nor password found in " + arg);
                } else if (password.IsSet) {
                    Console.WriteLine("Password found: " + new String('*', password.Value.Length));
                } else if (username.IsSet) {
                    Console.WriteLine("Username found: " + username.Value);
                } else {
                    Console.WriteLine("This case should not occur");
                }
            }
        }
    }

    class SetOnce<T> {
        public bool NotSet {
            get { return !IsSet; }
            private set { IsSet = !value; }
        }
        public bool IsSet { get; private set; }
        public T Value { get; private set; }
        public SetOnce()
        {
            IsSet = false;
            Value = default(T);
        }

        public SetOnce(T v)
        {
            IsSet = true;
            Value = v;
        }

        public SetOnce<T> Set(T v)
        {
            if (NotSet)
            {
                IsSet = true;
                Value = v;
            }
            return this;
        }
    }
}

// Local Variables:
// compile-command: "PowerShell.exe -File CompileSimply-CSharp.ps1 . RunAsFromFile.cs 64 mscorlib.dll"
// End: