/// <summary>
/// Download content
/// </summary>
/// <param name="files">The files to download</param>
public void Add(IEnumerable <UpdateFile> files)
{
var contentDownloader = new ContentDownloader();
contentDownloader.OnDownloadProgress += ContentDownloader_OnDownloadProgress;
var hashChecker = new ContentHash();
hashChecker.OnHashingProgress += HashChecker_OnHashingProgress;
var cancellationSource = new CancellationTokenSource();
var progressData = new ContentOperationProgress();
foreach (var file in files)
{
progressData.CurrentOperation = OperationType.DownloadFileStart;
progressData.File = file;
Progress?.Invoke(this, progressData);
if (Contains(file))
{
progressData.CurrentOperation = OperationType.DownloadFileEnd;
Progress?.Invoke(this, progressData);
}
else
{
// Create the directory structure where the file will be downloaded
var contentFilePath = GetUpdateFilePath(file);
var contentFileDirectory = Path.GetDirectoryName(contentFilePath);
if (!Directory.Exists(contentFileDirectory))
{
Directory.CreateDirectory(contentFileDirectory);
}
// Download the file (or resume and interrupted download)
contentDownloader.DownloadToFile(GetUpdateFilePath(file), file, cancellationSource.Token);
progressData.CurrentOperation = OperationType.DownloadFileEnd;
Progress?.Invoke(this, progressData);
progressData.CurrentOperation = OperationType.HashFileStart;
Progress?.Invoke(this, progressData);
// Check the hash; must match the strongest hash specified in the update metadata
if (hashChecker.Check(file, contentFilePath))
{
var markerFile = File.Create(GetUpdateFileMarkerPath(file));
markerFile.Dispose();
}
progressData.CurrentOperation = OperationType.HashFileEnd;
Progress?.Invoke(this, progressData);
}
}
}
/// <summary>
/// Downloads the specified URL to the destination file stream
/// </summary>
/// <param name="destination">The file stream to write content to</param>
/// <param name="updateFile">The update to download</param>
/// <param name="startOffset">Offset to resume download at</param>
/// <param name="cancellationToken">Cancellation token</param>
public void DownloadToStream(
Stream destination,
UpdateFile updateFile,
long startOffset,
CancellationToken cancellationToken)
{
var progress = new ContentOperationProgress()
{
File = updateFile,
Current = startOffset,
Maximum = (long)updateFile.Size,
CurrentOperation = OperationType.DownloadFileProgress
};
// Validate starting offset
if (startOffset >= (long)updateFile.Size)
{
throw new Exception($"Start offset {startOffset} cannot be greater than expected file size {updateFile.Size}");
}
var url = updateFile.DownloadUrl;
using (var client = new HttpClient())
{
var fileSizeOnServer = GetFileSizeOnServer(client, url, cancellationToken);
// Make sure our size matches the server's size
if (fileSizeOnServer != (long)updateFile.Size)
{
throw new Exception($"File size mismatch. Expected {updateFile.Size}, server advertised {fileSizeOnServer}");
}
// Build the range request for the download
using (var updateRequest = new HttpRequestMessage {
RequestUri = new Uri(url), Method = HttpMethod.Get
})
{
updateRequest.Headers.Range = new RangeHeaderValue((long)startOffset, (long)fileSizeOnServer - 1);
// Stream the file to disk
using (HttpResponseMessage response = client
.SendAsync(updateRequest, HttpCompletionOption.ResponseHeadersRead, cancellationToken)
.GetAwaiter()
.GetResult())
{
if (response.IsSuccessStatusCode)
{
using (Stream streamToReadFrom = response.Content.ReadAsStreamAsync().GetAwaiter().GetResult())
{
// Read in chunks while not at the end and cancellation was not requested
byte[] readBuffer = new byte[2097152 * 5];
var readBytesCount = streamToReadFrom.Read(readBuffer, 0, readBuffer.Length);
while (!cancellationToken.IsCancellationRequested && readBytesCount > 0)
{
destination.Write(readBuffer, 0, readBytesCount);
progress.Current += readBytesCount;
OnDownloadProgress?.Invoke(this, progress);
readBytesCount = streamToReadFrom.Read(readBuffer, 0, readBuffer.Length);
}
}
}
else
{
throw new Exception($"Failed to get content of update from {url}: {response.ReasonPhrase}");
}
}
}
}
}
/// <summary>
/// Checks that the hash of a file matches the value specified in the update file metadata
/// </summary>
/// <param name="updateFile">The update file object that contains the expected checksums</param>
/// <param name="filePath">The path to the file to checksum</param>
/// <returns>The string representatin of the hash</returns>
public bool Check(UpdateFile updateFile, string filePath)
{
byte[] readAheadBuffer, buffer;
int readAheadBytesRead, bytesRead;
int bufferSize = 512 * 1024;
// Pick the stronges hash algorithm available
HashAlgorithm hashAlgorithm;
UpdateFileDigest targetDigest;
if ((targetDigest = updateFile.Digests.Find(d => d.Algorithm.Equals("SHA512"))) != null)
{
hashAlgorithm = new SHA512Managed();
}
else if ((targetDigest = updateFile.Digests.Find(d => d.Algorithm.Equals("SHA256"))) != null)
{
hashAlgorithm = new SHA256Managed();
}
else if ((targetDigest = updateFile.Digests.Find(d => d.Algorithm.Equals("SHA1"))) != null)
{
hashAlgorithm = new SHA1Managed();
}
else
{
throw new Exception($"No supported hashing algorithms found for update file {updateFile.FileName}");
}
readAheadBuffer = new byte[bufferSize];
buffer = new byte[bufferSize];
// Hash the file contents
using (var fileStream = File.Open(filePath, FileMode.Open, FileAccess.Read))
{
var progress = new ContentOperationProgress()
{
File = updateFile,
Current = 0,
Maximum = (long)updateFile.Size,
CurrentOperation = OperationType.HashFileProgress
};
readAheadBytesRead = fileStream.Read(readAheadBuffer, 0, readAheadBuffer.Length);
do
{
byte[] tempBuffer;
bytesRead = readAheadBytesRead;
tempBuffer = buffer;
buffer = readAheadBuffer;
readAheadBuffer = tempBuffer;
readAheadBytesRead = fileStream.Read(readAheadBuffer, 0, readAheadBuffer.Length);
if (readAheadBytesRead == 0)
{
hashAlgorithm.TransformFinalBlock(buffer, 0, bytesRead);
progress.Current += bytesRead;
}
else
{
hashAlgorithm.TransformBlock(buffer, 0, bytesRead, buffer, 0);
progress.Current += bytesRead;
}
OnHashingProgress?.Invoke(this, progress);
} while (readAheadBytesRead != 0);
// Check that actual hash matches the expected value
var actualHash = hashAlgorithm.Hash;
var expectedHash = Convert.FromBase64String(targetDigest.DigestBase64);
return(actualHash.SequenceEqual(expectedHash));
}
}
