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P2PObjectTransfer.cs

/*
 * Galaxium Messenger
 * 
 * Copyright (C) 2008 Paul Burton <paulburton89@gmail.com>
 * 
 * License: GNU General Public License (GPL)
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the Free
 * Software Foundation; either version 2 of the License, or (at your option)
 * any later version.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
 * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write to the Free Software Foundation, Inc.,
 * 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

using System;
using System.IO;
using System.Security.Cryptography;

using Anculus.Core;

using Galaxium.Core;
using Galaxium.Client;

namespace Galaxium.Protocol.Msn
{
      [MsnP2PApplication (1, "A4268EEC-FEC5-49E5-95C3-F126696BDBF6")]
      public class P2PObjectTransfer : AbstractMsnP2PSessionApplication
      {
            MsnObject _object;
            bool _sending;
            MemoryStream _inStream;
            
            public override bool AutoAccept
            {
                  get { return true; }
            }
            
            public MsnObject Object
            {
                  get { return _object; }
            }
            
            public bool Sending
            {
                  get { return _sending; }
            }
            
            public P2PObjectTransfer (MsnP2PSession p2pSession)
                  : base (p2pSession)
            {
                  _object = MsnObject.Load (Session, EncodingUtility.Base64DecodeSafe (P2PSession.Invite.MIMEBody["Context"].Value));
                  
                  if (_object == null)
                  {
                        // Sometimes (especially with bots) the invite doesn't give us the object in the context
                        // so we accept that and send them the account display pic if we have one
                        
                        _object = Local.DisplayImage as MsnDisplayImage;
                  }
                  
                  _sending = true;
                  
                  // For some reason object transfers use BaseID-3, BaseID-2 etc after the invite
                  // We subtract 4 because the ID is incremented after sending the invite
                  P2PSession.LocalID -= 4;
            }
            
            public P2PObjectTransfer (MsnObject obj)
                  : base (obj.Session.Account, obj.Creator as MsnContact)
            {
                  _object = obj;
                  _sending = false;
            }
            
            public override bool CheckInvite (SLPRequestMessage invite)
            {
                  bool ret = base.CheckInvite (invite);
                  MsnObject obj = MsnObject.Load (invite.Session, EncodingUtility.Base64DecodeSafe (invite.MIMEBody["Context"].Value));
                  
                  if (obj != null)
                  {
                        // Invite is valid if the objects creator is the local account & the object has data
                        ret &= (obj.Creator == invite.Session.Account) && (obj.Data != null) && (obj.Data.Length > 0);
                  }
                  else
                  {
                        // Sometimes (especially with bots) the invite doesn't give us the object in the context
                        // so we accept that and send them the account display pic if we have one
                        
                        ret &= invite.Session.Account.DisplayImage is MsnDisplayImage;
                  }
                  
                  return ret;
            }
            
            public override string CreateInviteContext ()
            {
                  return EncodingUtility.Base64Encode (_object.Context);
            }
            
            public override void Begin ()
            {
                  base.Begin ();
                  
                  if (Sending)
                  {
                        P2PMessage msg = new P2PMessage (Session);
                        msg.Payload = new byte[] { 0, 0, 0, 0 };
                        
                        Send (msg, delegate
                        {
                              msg = new P2PMessage (Session);
                              msg.Header.Flags = P2PHeaderFlag.Data;
                              msg.Payload = _object.Data;
                              
                              Send (msg, delegate
                              {
                                    OnComplete ();
                              });
                        });
                  }
            }
            
            public override bool ProcessMessage (IMsnP2PBridge bridge, P2PMessage msg)
            {
                  if ((_inStream == null) && (msg.Payload.Length == 4) && (BitUtility.ToInt32 (msg.Payload, 0, true) == 0))
                  {
                        // Data prep
                        
                        _inStream = new MemoryStream ();
                        
                        Send (msg.CreateAck ());
                        
                        return true;
                  }
                  else if (((msg.Header.Flags & P2PHeaderFlag.Data) == P2PHeaderFlag.Data) ||
                           (msg.Header.Flags == P2PHeaderFlag.Normal)) // Some screwy bots do this... Virtual Secretary for example
                  {
                        _inStream.Write (msg.Payload, 0, msg.Payload.Length);
                        
                        //Log.Debug ("Received {0} of {1} bytes", _inStream.Length, _object.Size);
                        
                        if (_inStream.Length == _object.Size)
                        {
                              // Finished transfer
                              
                              byte[] data = new byte[_object.Size];
                              
                              _inStream.Seek (0, SeekOrigin.Begin);
                              _inStream.Read (data, 0, data.Length);
                              
                              string dataSha = Convert.ToBase64String (new SHA1Managed ().ComputeHash (data));
                              
                              if (dataSha != _object.Sha)
                              {
                                    Log.Warn ("Object hash doesn't match data hash, data invalid");
                                    return false;
                              }
                              
                              // Data is ok, update MsnObject
                              _object.Data = data;
                              
                              Send (msg.CreateAck ());
                              
                              OnComplete ();
                              P2PSession.Close ();
                              
                              if (_object is MsnDisplayImage && Sending == false)
                              {
                                    MsnDisplayImage image = _object as MsnDisplayImage;
                                    
                                    Local.Session.EmitContactDisplayImageChanged (new EntityChangeEventArgs<IDisplayImage> (image.Creator, image, null));
                                    
                                    ActivityUtility.EmitActivity (this, new EntityImageChangeActivity (this.Remote, image));
                              }
                        }
                        
                        return true;
                  }
                  
#if debug
                  return false;
#else
                  // If we're not debugging then we should try to continue even if we don't understand this message
                  return true;
#endif
            }
      }
}

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