private Stream ReadFileImpl(string virtualFilePath)
{
//get a token - this creates a new transfer and validates the request
DownloadToken token = RequestDownloadToken(virtualFilePath, false);
//forward the token
return(DownloadFileImpl(token.TransferId));
}
/// <summary>
/// Requests a download token based on an older one. This allows to resume a paused
/// or expired download if the service already discarded the token.
/// </summary>
/// <param name="oldToken">The previously used token.</param>
/// <param name="includeFileHash">Whether a file hash for the
/// requested resource should be calculated and assigned to the
/// <see cref="DownloadToken.Md5FileHash"/> property of the returned
/// <see cref="DownloadToken"/>. Can be used to verify file integrity, and also
/// indicates whether the file was changed if the old token contained a file hash.</param>
/// <returns>An updated token with a new expiration time, which reflects the
/// status updates of the submitted token, including the <see cref="TransferToken.LastTransmittedBlockInfo"/></returns>
public DownloadToken RenewToken(DownloadToken oldToken, bool includeFileHash)
{
//just create a new token - no adjustments needed with this service implementation
var token = RequestDownloadToken(oldToken.ResourceIdentifier, includeFileHash);
token.LastTransmittedBlockInfo = oldToken.LastTransmittedBlockInfo;
token.LastBlockTransmissionTime = oldToken.LastBlockTransmissionTime;
return(token);
}
public void Init()
{
store = new InMemoryTransferStore<DownloadTransfer<FileItem>>();
transfers = new List<DownloadTransfer<FileItem>>();
for (int i = 0; i < 10; i++)
{
FileItem item = new FileItem {LocalFile = new FileInfo(i.ToString())};
var token = new DownloadToken {TransferId = i.ToString()};
transfers.Add(new DownloadTransfer<FileItem>(token, item));
}
}
/// <summary>
/// Requests a download token for a given resource.
/// </summary>
/// <param name="resourceIdentifier"></param>
/// <param name="includeFileHash">Whether a file hash for the
/// requested resource should be calculated and assigned to the
/// <see cref="DownloadToken.Md5FileHash"/> property of the returned
/// <see cref="DownloadToken"/>.</param>
/// <returns></returns>
public DownloadToken RequestDownloadToken(string resourceIdentifier, bool includeFileHash)
{
FileInfo fileInfo = FileResolveFunc(resourceIdentifier);
if (!fileInfo.Exists)
{
string msg = String.Format("Resource [{0}] not found.", resourceIdentifier);
throw new VirtualResourceNotFoundException(msg);
}
string transferId = Guid.NewGuid().ToString();
DownloadToken dt = new DownloadToken
{
TransferId = transferId,
ResourceIdentifier = resourceIdentifier,
CreationTime = SystemTime.Now(),
ContentType = ContentUtil.ResolveContentType(fileInfo.Extension),
DownloadBlockSize = 512 * 1024, //TODO configure block size and expiration
ResourceName = fileInfo.Name,
ResourceLength = fileInfo.Length,
ExpirationTime = SystemTime.Now().AddHours(24),
Status = TransferStatus.Starting
};
//calculate number of blocks
long count = dt.ResourceLength / dt.DownloadBlockSize.Value;
if (dt.ResourceLength % dt.DownloadBlockSize != null)
{
count++;
}
dt.TotalBlockCount = count;
if (includeFileHash)
{
dt.Md5FileHash = fileInfo.CalculateMd5Hash();
}
var transfer = new DownloadTransfer(dt)
{
File = fileInfo
};
Transfers.Add(transferId, transfer);
return(dt);
}
/// <summary>
/// Initializes a new instance of the <see cref="T:System.Object"/> class.
/// </summary>
public DownloadManager(IDownloadTransferService transferService, string resourceId, DownloadToken token)
{
TransferService = transferService;
ResourceId = resourceId;
Token = token;
}
/// <summary>
/// Initializes a new instance of the <see cref="T:System.Object"/> class.
/// </summary>
protected OutboundTransferManager(DownloadToken token)
{
Token = token;
}
/// <summary>
/// Initializes a new instance of the <see cref="T:System.Object"/> class.
/// </summary>
protected OutboundTransferManager(DownloadToken token)
{
Token = token;
}
/// <summary>
/// Creates a transfer object for a given requested resource.
/// </summary>
/// <param name="submittedResourceFilePath">The resource identifier as submitted.</param>
/// <param name="fileItem">Represents the requested file resource.</param>
/// <param name="token">The token that is being issued for the transfer.</param>
/// <param name="claims">The access rights for the resource.</param>
/// <param name="lockGuard">File locks, if necessary. Can be a null reference
/// if no locking takes place.</param>
/// <param name="expirationJob">A scheduled job that invokes the
/// <see cref="TransferHandlerBase{TFile,TToken,TTransfer}.OnTransferExpiration"/>
/// method once the transfer expires. May be null if the token does not expire.</param>
/// <returns>A transfer object which encapsulates the information required to perform
/// the transfer.</returns>
protected abstract TTransfer CreateTransfer(string submittedResourceFilePath, TFile fileItem, DownloadToken token,
FileClaims claims, ResourceLockGuard lockGuard,
Job <DownloadToken> expirationJob);
private TTransfer InitTransferImpl(string submittedResourceFilePath, int?clientMaxBlockSize, bool includeFileHash)
{
const FileSystemTask context = FileSystemTask.DownloadTokenRequest;
TFile fileItem = CreateFileItemImpl(submittedResourceFilePath, false, context);
if (!fileItem.Exists)
{
Auditor.AuditRequestedFileNotFound(fileItem, context);
string msg = String.Format("Resource [{0}] not found.", submittedResourceFilePath);
throw new VirtualResourceNotFoundException(msg)
{
IsAudited = true
};
}
//get authorization
FileClaims claims = GetFileClaims(fileItem);
if (!claims.AllowReadData)
{
Auditor.AuditDeniedOperation(context, AuditEvent.FileDataDownloadDenied, fileItem);
string msg = "Read request for file [{0}] was denied - you are not authorized to read the resource.";
msg = String.Format(msg, submittedResourceFilePath);
throw new ResourceAccessException(msg)
{
IsAudited = true
};
}
//try to get lock
ResourceLockGuard readLock = LockResourceForDownload(fileItem, claims);
if (readLock != null && !readLock.IsLockEnabled)
{
Auditor.AuditDeniedOperation(context, AuditEvent.FileReadLockDenied, fileItem);
string msg = "The requested file [{0}] is currently locked and thus cannot be accessed.";
msg = String.Format(msg, submittedResourceFilePath);
throw new ResourceLockedException(msg)
{
IsAudited = true
};
}
//create download token
DownloadToken token = CreateDownloadToken(submittedResourceFilePath, fileItem, clientMaxBlockSize, includeFileHash);
//create expiration job if we have an expiration time
Job <DownloadToken> job = null;
if (token.ExpirationTime.HasValue)
{
job = ScheduleExpiration(token);
}
//create transfer instance
TTransfer transfer = CreateTransfer(submittedResourceFilePath, fileItem, token, claims, readLock, job);
//cache transfer
TransferStore.AddTransfer(transfer);
//audit issued token
Auditor.AuditResourceOperation(context, AuditEvent.DownloadTokenIssued, fileItem);
return(transfer);
}
/// <summary>
/// Handles locking, validation and stream preparation of a given transfer in order to read
/// a given block of data. The actual reading (either into a buffer, or a returned
/// stream) is being delegated via the <paramref name="dataReaderFunc"/>.
/// </summary>
/// <typeparam name="T">The type of <see cref="IDataBlockInfo"/> that is being returned.</typeparam>
/// <param name="transferId">The transfer token ID.</param>
/// <param name="blockNumber">The block number to be read.</param>
/// <param name="dataReaderFunc">A function that receives the <see cref="DownloadTransfer"/> and
/// the designated stream offset, and returns the required <see cref="IDataBlockInfo"/> that
/// provides the block's data.</param>
/// <returns>The <see cref="IDataBlockInfo"/> that is being created by the <paramref name="dataReaderFunc"/>.</returns>
private T PrepareBlockReading <T>(string transferId, long blockNumber, Func <DownloadTransfer, long, T> dataReaderFunc) where T : IDataBlockInfo
{
DownloadTransfer transfer = GetCachedTransfer(transferId, true);
DownloadToken token = transfer.Token;
if (!File.Exists(transfer.File.FullName))
{
string msg = "Resource [{0}] of transfer [{1}] was not found.";
msg = String.Format(msg, transfer.Token.ResourceName, transferId);
throw new VirtualResourceNotFoundException(msg);
}
lock (transfer.SyncRoot)
{
//make sure the transfer is active
if (!transfer.Status.Is(TransferStatus.Starting, TransferStatus.Running, TransferStatus.Paused))
{
string msg = String.Format("Transfer is not active anymore - status is [{0}].", transfer.Status);
throw new TransferStatusException(msg);
}
long position = blockNumber * token.DownloadBlockSize.Value;
//in case of an invalid position, throw error
if (position > token.ResourceLength)
{
string msg = "Cannot deliver block {0} - invalid block number.";
msg = String.Format(msg, blockNumber);
throw new DataBlockException(msg);
}
if (transfer.Stream == null)
{
//open stream, share read access
transfer.Stream = transfer.File.Open(FileMode.Open, FileAccess.Read, FileShare.Read);
}
//reposition stream if necessary
if (position != transfer.Stream.Position)
{
transfer.Stream.Seek(position, SeekOrigin.Begin);
}
T dataBlock = dataReaderFunc(transfer, position);
if (dataBlock.IsLastBlock)
{
//assume the last block will be processed successfully and
//already close the stream (don't wait for the transfer to be
//close by client)
transfer.Stream.Close();
transfer.Stream.Dispose();
transfer.Stream = null;
}
//update status
transfer.Token.Status = TransferStatus.Running;
//maintain local (unshared) copy of the block info without the data
transfer.Token.LastTransmittedBlockInfo = DataBlockInfo.FromDataBlock(dataBlock);
return(dataBlock);
}
}
/// <summary>
/// Initializes a new instance of the <see cref="T:System.Object"/> class.
/// </summary>
public DownloadTransfer(DownloadToken token)
{
Token = token;
SyncRoot = new object();
}
/// <summary>
/// Initializes a new instance of the <see cref="T:System.Object"/> class.
/// </summary>
public DownloadTransfer(DownloadToken token)
{
Token = token;
SyncRoot = new object();
}
/// <summary>
/// Initializes a new instance of the <see cref="T:System.Object"/> class.
/// </summary>
public DownloadManager(IDownloadTransferService transferService, string resourceId, DownloadToken token)
{
TransferService = transferService;
ResourceId = resourceId;
Token = token;
}