/*
  KeePass Password Safe - The Open-Source Password Manager
  Copyright (C) 2003-2020 Dominik Reichl <dominik.reichl@t-online.de>

  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., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
*/

// #define KDBX_BENCHMARK

using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.IO;
using System.Security;
using System.Text;
using System.Xml;
#if !ModernKeePassLib && !KeePassUAP
using System.Security.Cryptography;
#endif

#if !KeePassLibSD
using System.IO.Compression;
#else
using KeePassLibSD;
#endif

using ModernKeePassLib.Collections;
using ModernKeePassLib.Cryptography;
using ModernKeePassLib.Cryptography.Cipher;
using ModernKeePassLib.Cryptography.KeyDerivation;
using ModernKeePassLib.Interfaces;
using ModernKeePassLib.Keys;
using ModernKeePassLib.Resources;
using ModernKeePassLib.Security;
using ModernKeePassLib.Utility;

namespace ModernKeePassLib.Serialization
{
	/// <summary>
	/// Serialization to KeePass KDBX files.
	/// </summary>
	public sealed partial class KdbxFile
	{
		/// <summary>
		/// Load a KDBX file.
		/// </summary>
		/// <param name="strFilePath">File to load.</param>
		/// <param name="fmt">Format.</param>
		/// <param name="slLogger">Status logger (optional).</param>
#if ModernKeePassLib
        public void Load(byte[] fileContents, KdbxFormat fmt, IStatusLogger slLogger)
		{
			IOConnectionInfo ioc = IOConnectionInfo.FromByteArray(fileContents);
#else
		public void Load(string strFilePath, KdbxFormat fmt, IStatusLogger slLogger)
		{
			IOConnectionInfo ioc = IOConnectionInfo.FromPath(strFilePath);
#endif
			Load(IOConnection.OpenRead(ioc), fmt, slLogger);
		}

		/// <summary>
		/// Load a KDBX file from a stream.
		/// </summary>
		/// <param name="sSource">Stream to read the data from. Must contain
		/// a KDBX stream.</param>
		/// <param name="fmt">Format.</param>
		/// <param name="slLogger">Status logger (optional).</param>
		public void Load(Stream sSource, KdbxFormat fmt, IStatusLogger slLogger)
		{
			Debug.Assert(sSource != null);
			if(sSource == null) throw new ArgumentNullException("sSource");

			if(m_bUsedOnce)
				throw new InvalidOperationException("Do not reuse KdbxFile objects!");
			m_bUsedOnce = true;

#if KDBX_BENCHMARK
			Stopwatch swTime = Stopwatch.StartNew();
#endif

			m_format = fmt;
			m_slLogger = slLogger;

			m_pbsBinaries.Clear();

			UTF8Encoding encNoBom = StrUtil.Utf8;
			byte[] pbCipherKey = null;
			byte[] pbHmacKey64 = null;

			List<Stream> lStreams = new List<Stream>();
			lStreams.Add(sSource);

			HashingStreamEx sHashing = new HashingStreamEx(sSource, false, null);
			lStreams.Add(sHashing);

			try
			{
				Stream sXml;
				if(fmt == KdbxFormat.Default)
				{
					BinaryReaderEx br = new BinaryReaderEx(sHashing,
						encNoBom, KLRes.FileCorrupted);
					byte[] pbHeader = LoadHeader(br);
					m_pbHashOfHeader = CryptoUtil.HashSha256(pbHeader);

					int cbEncKey, cbEncIV;
					ICipherEngine iCipher = GetCipher(out cbEncKey, out cbEncIV);

					ComputeKeys(out pbCipherKey, cbEncKey, out pbHmacKey64);

					string strIncomplete = KLRes.FileHeaderCorrupted + " " +
						KLRes.FileIncomplete;

					Stream sPlain;
					if(m_uFileVersion < FileVersion32_4)
					{
						Stream sDecrypted = EncryptStream(sHashing, iCipher,
							pbCipherKey, cbEncIV, false);
						if((sDecrypted == null) || (sDecrypted == sHashing))
							throw new SecurityException(KLRes.CryptoStreamFailed);
						lStreams.Add(sDecrypted);

						BinaryReaderEx brDecrypted = new BinaryReaderEx(sDecrypted,
							encNoBom, strIncomplete);
						byte[] pbStoredStartBytes = brDecrypted.ReadBytes(32);

						if((m_pbStreamStartBytes == null) || (m_pbStreamStartBytes.Length != 32))
							throw new EndOfStreamException(strIncomplete);
						if(!MemUtil.ArraysEqual(pbStoredStartBytes, m_pbStreamStartBytes))
							throw new InvalidCompositeKeyException();

						sPlain = new HashedBlockStream(sDecrypted, false, 0, !m_bRepairMode);
					}
					else // KDBX >= 4
					{
						byte[] pbStoredHash = MemUtil.Read(sHashing, 32);
						if((pbStoredHash == null) || (pbStoredHash.Length != 32))
							throw new EndOfStreamException(strIncomplete);
						if(!MemUtil.ArraysEqual(m_pbHashOfHeader, pbStoredHash))
							throw new InvalidDataException(KLRes.FileHeaderCorrupted);

						byte[] pbHeaderHmac = ComputeHeaderHmac(pbHeader, pbHmacKey64);
						byte[] pbStoredHmac = MemUtil.Read(sHashing, 32);
						if((pbStoredHmac == null) || (pbStoredHmac.Length != 32))
							throw new EndOfStreamException(strIncomplete);
						if(!MemUtil.ArraysEqual(pbHeaderHmac, pbStoredHmac))
							throw new InvalidCompositeKeyException();

						HmacBlockStream sBlocks = new HmacBlockStream(sHashing,
							false, !m_bRepairMode, pbHmacKey64);
						lStreams.Add(sBlocks);

						sPlain = EncryptStream(sBlocks, iCipher, pbCipherKey,
							cbEncIV, false);
						if((sPlain == null) || (sPlain == sBlocks))
							throw new SecurityException(KLRes.CryptoStreamFailed);
					}
					lStreams.Add(sPlain);

					if(m_pwDatabase.Compression == PwCompressionAlgorithm.GZip)
					{
						sXml = new GZipStream(sPlain, CompressionMode.Decompress);
						lStreams.Add(sXml);
					}
					else sXml = sPlain;

					if(m_uFileVersion >= FileVersion32_4)
						LoadInnerHeader(sXml); // Binary header before XML
				}
				else if(fmt == KdbxFormat.PlainXml)
					sXml = sHashing;
				else { Debug.Assert(false); throw new ArgumentOutOfRangeException("fmt"); }

				if(fmt == KdbxFormat.Default)
				{
					if(m_pbInnerRandomStreamKey == null)
					{
						Debug.Assert(false);
						throw new SecurityException("Invalid inner random stream key!");
					}

					m_randomStream = new CryptoRandomStream(m_craInnerRandomStream,
						m_pbInnerRandomStreamKey);
				}

#if KeePassDebug_WriteXml
#warning XML output is enabled!
				/* using(FileStream fsOut = new FileStream("Raw.xml", FileMode.Create,
					FileAccess.Write, FileShare.None))
				{
					while(true)
					{
						int b = sXml.ReadByte();
						if(b == -1) throw new EndOfStreamException();
						fsOut.WriteByte((byte)b);
					}
				} */
#endif

				ReadXmlStreamed(sXml, sHashing);
				// ReadXmlDom(sXml);
			}
#if !ModernKeePassLib
			catch(CryptographicException) // Thrown on invalid padding
			{
				throw new CryptographicException(KLRes.FileCorrupted);
			}
#endif
			finally
			{
				if(pbCipherKey != null) MemUtil.ZeroByteArray(pbCipherKey);
				if(pbHmacKey64 != null) MemUtil.ZeroByteArray(pbHmacKey64);

				CommonCleanUpRead(lStreams, sHashing);
			}

#if KDBX_BENCHMARK
			swTime.Stop();
			MessageService.ShowInfo("Loading KDBX took " +
				swTime.ElapsedMilliseconds.ToString() + " ms.");
#endif
		}

		private void CommonCleanUpRead(List<Stream> lStreams, HashingStreamEx sHashing)
		{
			CloseStreams(lStreams);

			Debug.Assert(lStreams.Contains(sHashing)); // sHashing must be closed
			m_pbHashOfFileOnDisk = sHashing.Hash;
			Debug.Assert(m_pbHashOfFileOnDisk != null);

			CleanUpInnerRandomStream();

			// Reset memory protection settings (to always use reasonable
			// defaults)
			m_pwDatabase.MemoryProtection = new MemoryProtectionConfig();

			// Remove old backups (this call is required here in order to apply
			// the default history maintenance settings for people upgrading from
			// KeePass <= 2.14 to >= 2.15; also it ensures history integrity in
			// case a different application has created the KDBX file and ignored
			// the history maintenance settings)
			m_pwDatabase.MaintainBackups(); // Don't mark database as modified

			// Expand the root group, such that in case the user accidently
			// collapses the root group he can simply reopen the database
			PwGroup pgRoot = m_pwDatabase.RootGroup;
			if(pgRoot != null) pgRoot.IsExpanded = true;
			else { Debug.Assert(false); }

			m_pbHashOfHeader = null;
		}

		private byte[] LoadHeader(BinaryReaderEx br)
		{
			string strPrevExcpText = br.ReadExceptionText;
			br.ReadExceptionText = KLRes.FileHeaderCorrupted + " " +
				KLRes.FileIncompleteExpc;

			MemoryStream msHeader = new MemoryStream();
			Debug.Assert(br.CopyDataTo == null);
			br.CopyDataTo = msHeader;

			byte[] pbSig1 = br.ReadBytes(4);
			uint uSig1 = MemUtil.BytesToUInt32(pbSig1);
			byte[] pbSig2 = br.ReadBytes(4);
			uint uSig2 = MemUtil.BytesToUInt32(pbSig2);

			if((uSig1 == FileSignatureOld1) && (uSig2 == FileSignatureOld2))
				throw new OldFormatException(PwDefs.ShortProductName + @" 1.x",
					OldFormatException.OldFormatType.KeePass1x);

			if((uSig1 == FileSignature1) && (uSig2 == FileSignature2)) { }
			else if((uSig1 == FileSignaturePreRelease1) && (uSig2 ==
				FileSignaturePreRelease2)) { }
			else throw new FormatException(KLRes.FileSigInvalid);

			byte[] pb = br.ReadBytes(4);
			uint uVersion = MemUtil.BytesToUInt32(pb);
			if((uVersion & FileVersionCriticalMask) > (FileVersion32 & FileVersionCriticalMask))
				throw new FormatException(KLRes.FileVersionUnsupported +
					MessageService.NewParagraph + KLRes.FileNewVerReq);
			m_uFileVersion = uVersion;

			while(true)
			{
				if(!ReadHeaderField(br)) break;
			}

			br.CopyDataTo = null;
			byte[] pbHeader = msHeader.ToArray();
			msHeader.Dispose();

			br.ReadExceptionText = strPrevExcpText;
			return pbHeader;
		}

		private bool ReadHeaderField(BinaryReaderEx brSource)
		{
			Debug.Assert(brSource != null);
			if(brSource == null) throw new ArgumentNullException("brSource");

			byte btFieldID = brSource.ReadByte();

			int cbSize;
			Debug.Assert(m_uFileVersion > 0);
			if(m_uFileVersion < FileVersion32_4)
				cbSize = (int)MemUtil.BytesToUInt16(brSource.ReadBytes(2));
			else cbSize = MemUtil.BytesToInt32(brSource.ReadBytes(4));
			if(cbSize < 0) throw new FormatException(KLRes.FileCorrupted);

			byte[] pbData = MemUtil.EmptyByteArray;
			if(cbSize > 0) pbData = brSource.ReadBytes(cbSize);

			bool bResult = true;
			KdbxHeaderFieldID kdbID = (KdbxHeaderFieldID)btFieldID;
			switch(kdbID)
			{
				case KdbxHeaderFieldID.EndOfHeader:
					bResult = false; // Returning false indicates end of header
					break;

				case KdbxHeaderFieldID.CipherID:
					SetCipher(pbData);
					break;

				case KdbxHeaderFieldID.CompressionFlags:
					SetCompressionFlags(pbData);
					break;

				case KdbxHeaderFieldID.MasterSeed:
					m_pbMasterSeed = pbData;
					CryptoRandom.Instance.AddEntropy(pbData);
					break;

				// Obsolete; for backward compatibility only
				case KdbxHeaderFieldID.TransformSeed:
					Debug.Assert(m_uFileVersion < FileVersion32_4);

					AesKdf kdfS = new AesKdf();
					if(!m_pwDatabase.KdfParameters.KdfUuid.Equals(kdfS.Uuid))
						m_pwDatabase.KdfParameters = kdfS.GetDefaultParameters();

					// m_pbTransformSeed = pbData;
					m_pwDatabase.KdfParameters.SetByteArray(AesKdf.ParamSeed, pbData);

					CryptoRandom.Instance.AddEntropy(pbData);
					break;

				// Obsolete; for backward compatibility only
				case KdbxHeaderFieldID.TransformRounds:
					Debug.Assert(m_uFileVersion < FileVersion32_4);

					AesKdf kdfR = new AesKdf();
					if(!m_pwDatabase.KdfParameters.KdfUuid.Equals(kdfR.Uuid))
						m_pwDatabase.KdfParameters = kdfR.GetDefaultParameters();

					// m_pwDatabase.KeyEncryptionRounds = MemUtil.BytesToUInt64(pbData);
					m_pwDatabase.KdfParameters.SetUInt64(AesKdf.ParamRounds,
						MemUtil.BytesToUInt64(pbData));
					break;

				case KdbxHeaderFieldID.EncryptionIV:
					m_pbEncryptionIV = pbData;
					break;

				case KdbxHeaderFieldID.InnerRandomStreamKey:
					Debug.Assert(m_uFileVersion < FileVersion32_4);
					Debug.Assert(m_pbInnerRandomStreamKey == null);
					m_pbInnerRandomStreamKey = pbData;
					CryptoRandom.Instance.AddEntropy(pbData);
					break;

				case KdbxHeaderFieldID.StreamStartBytes:
					Debug.Assert(m_uFileVersion < FileVersion32_4);
					m_pbStreamStartBytes = pbData;
					break;

				case KdbxHeaderFieldID.InnerRandomStreamID:
					Debug.Assert(m_uFileVersion < FileVersion32_4);
					SetInnerRandomStreamID(pbData);
					break;

				case KdbxHeaderFieldID.KdfParameters:
					m_pwDatabase.KdfParameters = KdfParameters.DeserializeExt(pbData);
					break;

				case KdbxHeaderFieldID.PublicCustomData:
					Debug.Assert(m_pwDatabase.PublicCustomData.Count == 0);
					m_pwDatabase.PublicCustomData = VariantDictionary.Deserialize(pbData);
					break;

				default:
					Debug.Assert(false);
					if(m_slLogger != null)
						m_slLogger.SetText(KLRes.UnknownHeaderId + ": " +
							kdbID.ToString() + "!", LogStatusType.Warning);
					break;
			}

			return bResult;
		}

		private void LoadInnerHeader(Stream s)
		{
			BinaryReaderEx br = new BinaryReaderEx(s, StrUtil.Utf8,
				KLRes.FileCorrupted + " " + KLRes.FileIncompleteExpc);

			while(true)
			{
				if(!ReadInnerHeaderField(br)) break;
			}
		}

		private bool ReadInnerHeaderField(BinaryReaderEx br)
		{
			Debug.Assert(br != null);
			if(br == null) throw new ArgumentNullException("br");

			byte btFieldID = br.ReadByte();

			int cbSize = MemUtil.BytesToInt32(br.ReadBytes(4));
			if(cbSize < 0) throw new FormatException(KLRes.FileCorrupted);

			byte[] pbData = MemUtil.EmptyByteArray;
			if(cbSize > 0) pbData = br.ReadBytes(cbSize);

			bool bResult = true;
			KdbxInnerHeaderFieldID kdbID = (KdbxInnerHeaderFieldID)btFieldID;
			switch(kdbID)
			{
				case KdbxInnerHeaderFieldID.EndOfHeader:
					bResult = false; // Returning false indicates end of header
					break;

				case KdbxInnerHeaderFieldID.InnerRandomStreamID:
					SetInnerRandomStreamID(pbData);
					break;

				case KdbxInnerHeaderFieldID.InnerRandomStreamKey:
					Debug.Assert(m_pbInnerRandomStreamKey == null);
					m_pbInnerRandomStreamKey = pbData;
					CryptoRandom.Instance.AddEntropy(pbData);
					break;

				case KdbxInnerHeaderFieldID.Binary:
					if(pbData.Length < 1) throw new FormatException();
					KdbxBinaryFlags f = (KdbxBinaryFlags)pbData[0];
					bool bProt = ((f & KdbxBinaryFlags.Protected) != KdbxBinaryFlags.None);

					ProtectedBinary pb = new ProtectedBinary(bProt, pbData,
						1, pbData.Length - 1);
					m_pbsBinaries.Add(pb);

					if(bProt) MemUtil.ZeroByteArray(pbData);
					break;

				default:
					Debug.Assert(false);
					break;
			}

			return bResult;
		}

		private void SetCipher(byte[] pbID)
		{
			if((pbID == null) || (pbID.Length != (int)PwUuid.UuidSize))
				throw new FormatException(KLRes.FileUnknownCipher);

			m_pwDatabase.DataCipherUuid = new PwUuid(pbID);
		}

		private void SetCompressionFlags(byte[] pbFlags)
		{
			int nID = (int)MemUtil.BytesToUInt32(pbFlags);
			if((nID < 0) || (nID >= (int)PwCompressionAlgorithm.Count))
				throw new FormatException(KLRes.FileUnknownCompression);

			m_pwDatabase.Compression = (PwCompressionAlgorithm)nID;
		}

		private void SetInnerRandomStreamID(byte[] pbID)
		{
			uint uID = MemUtil.BytesToUInt32(pbID);
			if(uID >= (uint)CrsAlgorithm.Count)
				throw new FormatException(KLRes.FileUnknownCipher);

			m_craInnerRandomStream = (CrsAlgorithm)uID;
		}

		[Obsolete]
		public static List<PwEntry> ReadEntries(Stream msData)
		{
			return ReadEntries(msData, null, false);
		}

		[Obsolete]
		public static List<PwEntry> ReadEntries(PwDatabase pdContext, Stream msData)
		{
			return ReadEntries(msData, pdContext, true);
		}

		/// <summary>
		/// Read entries from a stream.
		/// </summary>
		/// <param name="msData">Input stream to read the entries from.</param>
		/// <param name="pdContext">Context database (e.g. for storing icons).</param>
		/// <param name="bCopyIcons">If <c>true</c>, custom icons required by
		/// the loaded entries are copied to the context database.</param>
		/// <returns>Loaded entries.</returns>
		public static List<PwEntry> ReadEntries(Stream msData, PwDatabase pdContext,
			bool bCopyIcons)
		{
			List<PwEntry> lEntries = new List<PwEntry>();

			if(msData == null) { Debug.Assert(false); return lEntries; }
			// pdContext may be null

			/* KdbxFile f = new KdbxFile(pwDatabase);
			f.m_format = KdbxFormat.PlainXml;

			XmlDocument doc = XmlUtilEx.CreateXmlDocument();
			doc.Load(msData);

			XmlElement el = doc.DocumentElement;
			if(el.Name != ElemRoot) throw new FormatException();

			List<PwEntry> vEntries = new List<PwEntry>();

			foreach(XmlNode xmlChild in el.ChildNodes)
			{
				if(xmlChild.Name == ElemEntry)
				{
					PwEntry pe = f.ReadEntry(xmlChild);
					pe.Uuid = new PwUuid(true);

					foreach(PwEntry peHistory in pe.History)
						peHistory.Uuid = pe.Uuid;

					vEntries.Add(pe);
				}
				else { Debug.Assert(false); }
			}

			return vEntries; */

			PwDatabase pd = new PwDatabase();
			pd.New(new IOConnectionInfo(), new CompositeKey());

			KdbxFile f = new KdbxFile(pd);
			f.Load(msData, KdbxFormat.PlainXml, null);

			foreach(PwEntry pe in pd.RootGroup.Entries)
			{
				pe.SetUuid(new PwUuid(true), true);
				lEntries.Add(pe);

				if(bCopyIcons && (pdContext != null))
				{
					PwUuid pu = pe.CustomIconUuid;
					if(!pu.Equals(PwUuid.Zero))
					{
						int iSrc = pd.GetCustomIconIndex(pu);
						int iDst = pdContext.GetCustomIconIndex(pu);

						if(iSrc < 0) { Debug.Assert(false); }
						else if(iDst < 0)
						{
							pdContext.CustomIcons.Add(pd.CustomIcons[iSrc]);

							pdContext.Modified = true;
							pdContext.UINeedsIconUpdate = true;
						}
					}
				}
			}

			return lEntries;
		}
	}
}