keepass2android/src/Kp2aBusinessLogic/Io/CachingFileStorage.cs

507 lines
14 KiB
C#

using System;
using System.Collections.Generic;
using System.IO;
using System.Net;
using System.Security.Cryptography;
using System.Text;
using Android.Content;
using Android.OS;
using KeePassLib.Cryptography;
using KeePassLib.Serialization;
using KeePassLib.Utility;
namespace keepass2android.Io
{
/// <summary>
/// Interface for classes which can handle certain Cache events on a higher level (e.g. by user interaction)
/// </summary>
public interface ICacheSupervisor
{
/// <summary>
/// called when a save operation only updated the cache but not the remote file
/// </summary>
/// <param name="ioc">The file which we tried to write</param>
/// <param name="ex">The exception why the remote file couldn't be updated</param>
void CouldntSaveToRemote(IOConnectionInfo ioc, Exception ex);
/// <summary>
/// Called when only the local file could be opened during an open operation.
/// </summary>
void CouldntOpenFromRemote(IOConnectionInfo ioc, Exception ex);
/// <summary>
/// Called when the local file either didn't exist or was unmodified, so the remote file
/// was loaded and the cache was updated during the load operation.
/// </summary>
void UpdatedCachedFileOnLoad(IOConnectionInfo ioc);
/// <summary>
/// Called when the remote file either didn't exist or was unmodified, so the local file
/// was loaded and the remote file was updated during the load operation.
/// </summary>
void UpdatedRemoteFileOnLoad(IOConnectionInfo ioc);
/// <summary>
/// Called to notify the supervisor that the file described by ioc is opened from the cache because there's a conflict
/// with local and remote changes
/// </summary>
/// <param name="ioc"></param>
void NotifyOpenFromLocalDueToConflict(IOConnectionInfo ioc);
/// <summary>
/// Called when the load operation was performed and the remote file was identical with the local file
/// </summary>
void LoadedFromRemoteInSync(IOConnectionInfo ioc);
}
/// <summary>
/// Implements the IFileStorage interface as a proxy: A base storage is used as a remote storage. Local files are used to cache the
/// files on remote.
/// </summary>
public class CachingFileStorage: IFileStorage
{
private readonly IFileStorage _cachedStorage;
private readonly ICacheSupervisor _cacheSupervisor;
private readonly string _streamCacheDir;
public CachingFileStorage(IFileStorage cachedStorage, string cacheDir, ICacheSupervisor cacheSupervisor)
{
_cachedStorage = cachedStorage;
_cacheSupervisor = cacheSupervisor;
_streamCacheDir = cacheDir + Java.IO.File.Separator + "OfflineCache" + Java.IO.File.Separator;
if (!Directory.Exists(_streamCacheDir))
Directory.CreateDirectory(_streamCacheDir);
}
public void ClearCache()
{
IoUtil.DeleteDir(new Java.IO.File(_streamCacheDir), true);
}
public IEnumerable<string> SupportedProtocols { get { return _cachedStorage.SupportedProtocols; } }
public void DeleteFile(IOConnectionInfo ioc)
{
if (IsCached(ioc))
{
File.Delete(CachedFilePath(ioc));
File.Delete(VersionFilePath(ioc));
File.Delete(BaseVersionFilePath(ioc));
}
_cachedStorage.Delete(ioc);
}
private string CachedFilePath(IOConnectionInfo ioc)
{
SHA256Managed sha256 = new SHA256Managed();
string iocAsHexString = MemUtil.ByteArrayToHexString(sha256.ComputeHash(Encoding.Unicode.GetBytes(ioc.Path.ToCharArray())))+".cache";
return _streamCacheDir + iocAsHexString;
}
private bool IsCached(IOConnectionInfo ioc)
{
return File.Exists(CachedFilePath(ioc))
&& File.Exists(VersionFilePath(ioc))
&& File.Exists(BaseVersionFilePath(ioc));
}
public void Delete(IOConnectionInfo ioc)
{
_cachedStorage.Delete(ioc);
}
public bool CheckForFileChangeFast(IOConnectionInfo ioc, string previousFileVersion)
{
//see comment in GetCurrentFileVersionFast
return false;
}
public string GetCurrentFileVersionFast(IOConnectionInfo ioc)
{
//fast file version checking is not supported by CachingFileStorage:
//it's hard to return good versions in cases that the base source is offline
//or after modifying the cache.
//It's probably not relevant because fast file version checking is meant for local storage
//which is not cached.
return String.Empty;
}
private string VersionFilePath(IOConnectionInfo ioc)
{
return CachedFilePath(ioc)+".version";
}
private string BaseVersionFilePath(IOConnectionInfo ioc)
{
return CachedFilePath(ioc) + ".baseversion";
}
public Stream OpenFileForRead(IOConnectionInfo ioc)
{
string cachedFilePath = CachedFilePath(ioc);
try
{
if (!IsCached(ioc)
|| GetLocalVersionHash(ioc) == GetBaseVersionHash(ioc))
{
return OpenFileForReadWhenNoLocalChanges(ioc, cachedFilePath);
}
else
{
return OpenFileForReadWhenLocalChanges(ioc, cachedFilePath);
}
}
catch (Exception ex)
{
if (!IsCached(ioc))
throw;
Kp2aLog.Log("couldn't open from remote " + ioc.Path);
Kp2aLog.Log(ex.ToString());
_cacheSupervisor.CouldntOpenFromRemote(ioc, ex);
return File.OpenRead(cachedFilePath);
}
}
private Stream OpenFileForReadWhenLocalChanges(IOConnectionInfo ioc, string cachedFilePath)
{
//file is cached but has local modifications
//try to upload the changes if remote file doesn't have changes as well:
var hash = CalculateHash(ioc);
if (File.ReadAllText(BaseVersionFilePath(ioc)) == hash)
{
//no changes in remote file -> upload
using (Stream localData = File.OpenRead(CachedFilePath(ioc)))
{
if (TryUpdateRemoteFile(localData, ioc, true, hash))
_cacheSupervisor.UpdatedRemoteFileOnLoad(ioc);
}
}
else
{
//conflict: both files changed.
//signal that we're loading from local
_cacheSupervisor.NotifyOpenFromLocalDueToConflict(ioc);
}
return File.OpenRead(cachedFilePath);
}
public MemoryStream GetRemoteDataAndHash(IOConnectionInfo ioc, out string hash)
{
MemoryStream remoteData = new MemoryStream();
using (
HashingStreamEx hashingRemoteStream = new HashingStreamEx(_cachedStorage.OpenFileForRead(ioc), false,
new SHA256Managed()))
{
hashingRemoteStream.CopyTo(remoteData);
hashingRemoteStream.Close();
hash = MemUtil.ByteArrayToHexString(hashingRemoteStream.Hash);
}
remoteData.Position = 0;
return remoteData;
}
private string CalculateHash(IOConnectionInfo ioc)
{
string hash;
GetRemoteDataAndHash(ioc, out hash);
return hash;
}
private Stream OpenFileForReadWhenNoLocalChanges(IOConnectionInfo ioc, string cachedFilePath)
{
//open stream:
using (Stream file = _cachedStorage.OpenFileForRead(ioc))
{
//copy to cache:
//note: we might use the file version to check if it's already in the cache and if copying is required.
//However, this is safer.
string fileHash;
using (HashingStreamEx cachedFile = new HashingStreamEx(File.Create(cachedFilePath), true, new SHA256Managed()))
{
file.CopyTo(cachedFile);
cachedFile.Close();
fileHash = MemUtil.ByteArrayToHexString(cachedFile.Hash);
}
//remember current hash
string previousHash = null;
string baseVersionFilePath = BaseVersionFilePath(ioc);
if (File.Exists(baseVersionFilePath))
previousHash = File.ReadAllText(baseVersionFilePath);
//save hash in cache files:
File.WriteAllText(VersionFilePath(ioc), fileHash);
File.WriteAllText(baseVersionFilePath, fileHash);
//notify supervisor what we did:
if (previousHash != fileHash)
_cacheSupervisor.UpdatedCachedFileOnLoad(ioc);
else
_cacheSupervisor.LoadedFromRemoteInSync(ioc);
return File.OpenRead(cachedFilePath);
}
}
private bool TryUpdateRemoteFile(Stream cachedData, IOConnectionInfo ioc, bool useFileTransaction, string hash)
{
try
{
UpdateRemoteFile(cachedData, ioc, useFileTransaction, hash);
return true;
}
catch (Exception e)
{
Kp2aLog.Log("couldn't save to remote " + ioc.Path);
Kp2aLog.Log(e.ToString());
//notify the supervisor so it might display a warning or schedule a retry
_cacheSupervisor.CouldntSaveToRemote(ioc, e);
return false;
}
}
private void UpdateRemoteFile(Stream cachedData, IOConnectionInfo ioc, bool useFileTransaction, string hash)
{
//try to write to remote:
using (
IWriteTransaction remoteTrans = _cachedStorage.OpenWriteTransaction(ioc, useFileTransaction))
{
Stream remoteStream = remoteTrans.OpenFile();
cachedData.CopyTo(remoteStream);
remoteStream.Close();
remoteTrans.CommitWrite();
}
//success. Update base-version of cache:
File.WriteAllText(BaseVersionFilePath(ioc), hash);
File.WriteAllText(VersionFilePath(ioc), hash);
}
public void UpdateRemoteFile(IOConnectionInfo ioc, bool useFileTransaction)
{
using (Stream cachedData = File.OpenRead(CachedFilePath(ioc)))
{
UpdateRemoteFile(cachedData, ioc, useFileTransaction, GetLocalVersionHash(ioc));
}
}
private class CachedWriteTransaction: IWriteTransaction
{
private class CachedWriteMemoryStream : MemoryStream
{
private readonly IOConnectionInfo ioc;
private readonly CachingFileStorage _cachingFileStorage;
private readonly bool _useFileTransaction;
private bool _closed;
public CachedWriteMemoryStream(IOConnectionInfo ioc, CachingFileStorage cachingFileStorage, bool useFileTransaction)
{
this.ioc = ioc;
_cachingFileStorage = cachingFileStorage;
_useFileTransaction = useFileTransaction;
}
public override void Close()
{
if (_closed) return;
//write file to cache:
//(note: this might overwrite local changes. It's assumed that a sync operation or check was performed before
string hash;
using (var hashingStream = new HashingStreamEx(File.Create(_cachingFileStorage.CachedFilePath(ioc)), true, new SHA256Managed()))
{
Position = 0;
CopyTo(hashingStream);
hashingStream.Close();
hash = MemUtil.ByteArrayToHexString(hashingStream.Hash);
}
File.WriteAllText(_cachingFileStorage.VersionFilePath(ioc), hash);
//update file on remote. This might overwrite changes there as well, see above.
Position = 0;
if (_cachingFileStorage.IsCached(ioc))
{
//if the file already is in the cache, it's ok if writing to remote fails.
_cachingFileStorage.TryUpdateRemoteFile(this, ioc, _useFileTransaction, hash);
}
else
{
//if not, we don't accept a failure (e.g. invalid credentials would always remain a problem)
_cachingFileStorage.UpdateRemoteFile(this, ioc, _useFileTransaction, hash);
}
base.Close();
_closed = true;
}
}
private readonly IOConnectionInfo _ioc;
private readonly bool _useFileTransaction;
private readonly CachingFileStorage _cachingFileStorage;
private MemoryStream _memoryStream;
private bool _committed;
public CachedWriteTransaction(IOConnectionInfo ioc, bool useFileTransaction, CachingFileStorage cachingFileStorage)
{
_ioc = ioc;
_useFileTransaction = useFileTransaction;
_cachingFileStorage = cachingFileStorage;
}
public void Dispose()
{
if (!_committed)
{
try
{
_memoryStream.Dispose();
}
catch (ObjectDisposedException e)
{
Kp2aLog.Log("Ignoring exception in Dispose: "+e);
}
}
}
public Stream OpenFile()
{
_memoryStream = new CachedWriteMemoryStream(_ioc, _cachingFileStorage, _useFileTransaction);
return _memoryStream;
}
public void CommitWrite()
{
//the transaction is committed in the stream's Close
_committed = true;
}
}
public IWriteTransaction OpenWriteTransaction(IOConnectionInfo ioc, bool useFileTransaction)
{
//create a transaction which writes to memory stream
//on close: write to cache. If possible, write to online
//update versions
return new CachedWriteTransaction(ioc, useFileTransaction, this);
}
public bool CompleteIoId()
{
throw new NotImplementedException();
}
public bool? FileExists()
{
throw new NotImplementedException();
}
public string GetFilenameWithoutPathAndExt(IOConnectionInfo ioc)
{
return UrlUtil.StripExtension(
UrlUtil.GetFileName(ioc.Path));
}
public bool RequiresCredentials(IOConnectionInfo ioc)
{
return _cachedStorage.RequiresCredentials(ioc);
}
public void CreateDirectory(IOConnectionInfo ioc, string newDirName)
{
_cachedStorage.CreateDirectory(ioc, newDirName);
}
public IEnumerable<FileDescription> ListContents(IOConnectionInfo ioc)
{
return _cachedStorage.ListContents(ioc);
}
public FileDescription GetFileDescription(IOConnectionInfo ioc)
{
return _cachedStorage.GetFileDescription(ioc);
}
public bool RequiresSetup(IOConnectionInfo ioConnection)
{
return _cachedStorage.RequiresSetup(ioConnection);
}
public string IocToPath(IOConnectionInfo ioc)
{
return _cachedStorage.IocToPath(ioc);
}
public void StartSelectFile(IFileStorageSetupInitiatorActivity activity, bool isForSave, int requestCode, string protocolId)
{
_cachedStorage.StartSelectFile(activity, isForSave, requestCode, protocolId);
}
public void PrepareFileUsage(IFileStorageSetupInitiatorActivity activity, IOConnectionInfo ioc, int requestCode)
{
_cachedStorage.PrepareFileUsage(activity, ioc, requestCode);
}
public void OnCreate(IFileStorageSetupActivity activity, Bundle savedInstanceState)
{
_cachedStorage.OnCreate(activity, savedInstanceState);
}
public void OnResume(IFileStorageSetupActivity activity)
{
_cachedStorage.OnResume(activity);
}
public void OnStart(IFileStorageSetupActivity activity)
{
_cachedStorage.OnStart(activity);
}
public void OnActivityResult(IFileStorageSetupActivity activity, int requestCode, int resultCode, Intent data)
{
_cachedStorage.OnActivityResult(activity, requestCode, resultCode, data);
}
public string GetBaseVersionHash(IOConnectionInfo ioc)
{
return File.ReadAllText(BaseVersionFilePath(ioc));
}
public string GetLocalVersionHash(IOConnectionInfo ioc)
{
return File.ReadAllText(VersionFilePath(ioc));
}
public bool HasLocalChanges(IOConnectionInfo ioc)
{
return IsCached(ioc)
&& GetLocalVersionHash(ioc) != GetBaseVersionHash(ioc);
}
public Stream OpenRemoteForReadIfAvailable(IOConnectionInfo ioc)
{
try
{
return _cachedStorage.OpenFileForRead(ioc);
}
catch (Exception)
{
return File.OpenRead(CachedFilePath(ioc));
}
}
}
}