/// <summary>
/// Downloads the file specified in the given update and verifies the hash sum if available.
/// </summary>
/// <param name="update">The update to be downloaded.</param>
/// <param name="downloadProgress">A download progress provider.</param>
/// <param name="ct">A CancellationToken used to cancel the download.</param>
/// <returns>The full path to the downloaded file if the download was successful; null if the download was canceled.</returns>
/// <exception cref="UpdateFailedException">If downloading the download failed.</exception>
public async Task <string> DownloadUpdate(AppUpdate update, IProgress <int> downloadProgress = null,
CancellationToken ct = default(CancellationToken))
{
DownloadEntry entry = ResolveDownloadEntry(update);
Uri uri = new Uri(entry.Link, UriKind.RelativeOrAbsolute);
string filePath = Path.Combine(Path.GetTempPath(), entry.FileName);
try
{
if (uri.IsAbsoluteUri)
{
WebClient client = new WebClient();
ct.Register(client.CancelAsync);
await client.DownloadFileTaskAsync(new Uri(entry.Link, UriKind.RelativeOrAbsolute), filePath, downloadProgress);
}
else
{
File.Copy(uri.ToString(), filePath, true);
}
Debug.WriteLine(String.Format("Downloaded update to {0}", filePath));
}
catch (WebException ex) when(ex.Message == "The request was aborted: The request was canceled.")
{
// The download was cancelled by the user. Don't throw an exception.
return(null);
}
catch (Exception e)
{
throw new UpdateFailedException("Downloading the update failed.", e);
}
if (entry.FileHash != null)
{
if (VerifyHash(entry.FileHash, filePath))
{
return(filePath);
}
else
{
File.Delete(filePath);
throw new UpdateFailedException("File verification failed.");
}
}
else
{
return(filePath);
}
}
/// <summary>
/// Resolves the correct download information based on the DownloadIdentifier of the update checker.
/// </summary>
public DownloadEntry ResolveDownloadEntry(AppUpdate update)
{
DownloadEntry entry = null;
if (DownloadIdentifier != null)
{
entry = update.Downloads?.FirstOrDefault(de => de.Key == DownloadIdentifier);
}
// construct a download entry from default values if key was not found.
if (entry == null)
{
entry = new DownloadEntry()
{
Link = update.DownloadLink,
FileName = update.DownloadFileName,
FileHash = null
};
}
if (entry.FileName == null)
{
entry.FileName = getFileName(entry.Link);
}
return(entry);
}