/// <summary>
/// Downloads all new files and replaces old files in directory.
/// </summary>
/// <param name="info">Update information generated by <c>FetchUpdateInfoAsync</c></param>
/// <returns>True on success, false on failure.</returns>
/// <exception cref="KangarupException">On a file checksum error.</exception>
public async Task <bool> UpdateNewFilesAsync(UpdateInfo info)
{
if (UpdateUri == null)
{
throw new ArgumentNullException("UpdateUri cannot be null");
}
var httpClient = new HttpClient();
var tempPath = Path.GetTempPath();
var tempFolder = Directory.CreateDirectory(Path.Combine(tempPath, TempFolderName));
foreach (var infoFile in info.Files)
{
var downloadStream = await httpClient.GetStreamAsync(UpdateUri.Append(infoFile.RelativeUrl)).ConfigureAwait(false);
var fileToReplace = Path.GetFileName(infoFile.RelativeUrl);
try
{
// download file
var tmpFile = Path.GetTempFileName();
using (var fileStream = File.Create(tmpFile))
{
await downloadStream.CopyToAsync(fileStream).ConfigureAwait(false);
}
// verify file
var sha256 = SHA256.Create();
using (var inputStream = File.OpenRead(tmpFile))
{
var hash = sha256.ComputeHash(inputStream);
var hashHex = BitConverter.ToString(hash).Replace("-", string.Empty);
if (infoFile.Checksum != hashHex)
{
// checksum wrong
throw new KangarupException($"Checksum mismatch of file '{fileToReplace}'.");
}
}
// place file
File.Move(fileToReplace, Path.Combine(tempFolder.FullName, $"{fileToReplace}"));
File.Move(tmpFile, fileToReplace);
}
catch (IOException e)
{
Logger?.Error($"Unable to update file '{fileToReplace}': {e.Message}", e);
return(false);
}
//File.Delete($"{fileToReplace}.old"); // TODO not possible on running application
}
return(true);
}
/// <summary>
/// Retrieves latest update information from server and verifies cryptographic signature.
/// </summary>
/// <exception cref="KangarupException">Cryptographic signature does not match update manifest</exception>
/// <exception cref="ArgumentNullException">UpdateUri is null</exception>
/// <returns>Latest update information.</returns>
public async Task <UpdateInfo> FetchUpdateInfoAsync()
{
if (UpdateUri == null)
{
throw new ArgumentNullException("UpdateUri cannot be null");
}
if (_rsa == null)
{
LoadCertificate();
}
// download update manifest
var httpClient = new HttpClient();
try
{
var rawUpdateInfo =
await httpClient.GetByteArrayAsync(
UpdateUri.Append("update.yml"));
// download update manifest signature
var signature = await httpClient.GetByteArrayAsync(UpdateUri.Append("update.sig"));
// verify manifest
if (!_rsa.VerifyData(rawUpdateInfo, signature, HashAlgorithmName.SHA256, RSASignaturePadding.Pkcs1))
{
throw new KangarupException("Update manifest signature is wrong.");
}
// construct UpdateInfo object from data
var deserializer = new Deserializer();
return(deserializer.Deserialize <UpdateInfo>(Encoding.UTF8.GetString(rawUpdateInfo)));
}
catch (HttpRequestException e)
{
Logger?.Error("Unable to contact update server.", e);
return(null);
}
}