/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
 * Copyright (c) 2003-2008 by AG-Software 											 *
 * All Rights Reserved.																 *
 * Contact information for AG-Software is available at http://www.ag-software.de	 *
 *																					 *
 * Licence:																			 *
 * The agsXMPP SDK is released under a dual licence									 *
 * agsXMPP can be used under either of two licences									 *
 * 																					 *
 * A commercial licence which is probably the most appropriate for commercial 		 *
 * corporate use and closed source projects. 										 *
 *																					 *
 * The GNU Public License (GPL) is probably most appropriate for inclusion in		 *
 * other open source projects.														 *
 *																					 *
 * See README.html for details.														 *
 *																					 *
 * For general enquiries visit our website at:										 *
 * http://www.ag-software.de														 *
 * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */ 

using System;

//encoded challenge to client: 
//
//<challenge xmlns='urn:ietf:params:xml:ns:xmpp-sasl'>
//cmVhbG09InNvbWVyZWFsbSIsbm9uY2U9Ik9BNk1HOXRFUUdtMmhoIixxb3A9ImF1dGgi
//LGNoYXJzZXQ9dXRmLTgsYWxnb3JpdGhtPW1kNS1zZXNzCg==
//</challenge>The decoded challenge is: 
//
//realm="somerealm",nonce="OA6MG9tEQGm2hh",qop="auth",charset=utf-8,algorithm=md5-sess


namespace agsXMPP.sasl.DigestMD5
{
	/// <summary>
	/// Summary description for Step1.
	/// </summary>
	public class Step1 : DigestMD5Mechanism // Mechanism 
	{
        /// <summary>
        /// Exception occurs when we were unable to parse the challenge
        /// </summary>
        public class ChallengeParseException : Exception
        {
            public ChallengeParseException(string message) : base(message)
            {
            }
        }

		#region << Constructors >>
		public Step1()
		{
			
		}

		public Step1(string message)
		{
			m_Message = message;
			Parse(message);
		}
		#endregion
		
		#region << Properties >>
		private string	m_Realm;		
		private string	m_Nonce;		
		private string	m_Qop;//			= "auth";		
		private string	m_Charset		= "utf-8";		
		private string	m_Algorithm;
		
		private string	m_Rspauth		= null;

		private string	m_Message;

		public string Realm
		{
			get { return m_Realm; }
			set { m_Realm = value; }
		}

		public string Nonce
		{
			get { return m_Nonce; }
			set { m_Nonce = value; }
		}

		public string Qop
		{
			get { return m_Qop; }
			set { m_Qop = value; }
		}

		public string Charset
		{
			get { return m_Charset; }
			set { m_Charset = value; }
		}

		public string Algorithm
		{
			get { return m_Algorithm; }
			set { m_Algorithm = value; }
		}
		
		public string Rspauth
		{
			get { return m_Rspauth; }
			set { m_Rspauth = value; }
		}
		#endregion

        /*
            nonce="deqOGux/N6hDPtf9vkGMU5Vzae+zfrqpBIvh6LovbBM=",
            realm="amessage.de",
            qop="auth,auth-int,auth-conf",
            cipher="rc4-40,rc4-56,rc4,des,3des",
            maxbuf=1024,
            charset=utf-8,
            algorithm=md5-sess
        */
        private void Parse(string message)
        {
            try
            {
                int start = 0;
                int end = 0;
                while (start < message.Length)
                {
                    int equalPos = message.IndexOf('=', start);
                    if (equalPos > 0)
                    {
                        // look if the next char is a quote
                        if (message.Substring(equalPos + 1, 1) == "\"")
                        {
                            // quoted value, find the end now
                            end = message.IndexOf('"', equalPos + 2);
                            ParsePair(message.Substring(start, end - start + 1));
                            start = end + 2;
                        }
                        else
                        {
                            // value is not quoted, ends at the next comma or end of string   
                            end = message.IndexOf(',', equalPos + 1);
                            if (end == -1)
                                end = message.Length;
                            
                            ParsePair(message.Substring(start, end - start));

                            start = end + 1;
                        }
                    }
                }
            }
            catch
            {
                throw new ChallengeParseException("Unable to parse challenge");
            }
        }

        private void ParsePair(string pair)
        {
            int equalPos = pair.IndexOf("=");
            if (equalPos > 0)
            {
                string key = pair.Substring(0, equalPos);
                string data;
                // is the value quoted?
                if (pair.Substring(equalPos + 1, 1) == "\"")
                    data = pair.Substring(equalPos + 2, pair.Length - equalPos - 3);
                else
                    data = pair.Substring(equalPos + 1);

                switch (key)
                {
                    case "realm":
                        m_Realm = data;
                        break;
                    case "nonce":
                        m_Nonce = data;
                        break;
                    case "qop":
                        m_Qop = data;
                        break;
                    case "charset":
                        m_Charset = data;
                        break;
                    case "algorithm":
                        m_Algorithm = data;
                        break;
                    case "rspauth":
                        m_Rspauth = data;
                        break;
                }
            }
        }
	}
}
