private async Task SynchronizeDatabaseAsync()
{
var cancellationToken = this._synchronizationTaskCancellationTokenSource.Token;
while (!cancellationToken.IsCancellationRequested)
{
var getThreatListUpdatesTask = GetThreatListUpdatesAsync(this);
var(threatListUpdateResponse, delayToDate) = await getThreatListUpdatesTask.ConfigureAwait(false);
if (threatListUpdateResponse != null)
{
foreach (var threatListUpdateResult in threatListUpdateResponse.Results)
{
var threatListWaitToDate = threatListUpdateResult.RetrievedThreatList.WaitToDate;
if (threatListWaitToDate != null && threatListWaitToDate < delayToDate)
{
delayToDate = threatListWaitToDate.Value;
}
var synchronizeThreatListTask = SynchronizeThreatListAsync(this, threatListUpdateResult);
await synchronizeThreatListTask.ConfigureAwait(false);
}
}
var delayToTask = DelayToAsync(this, delayToDate);
await delayToTask.ConfigureAwait(false);
}
// <summary>
// Delay to a Date Asynchronously.
// </summary>
async Task DelayToAsync(BrowsingDatabaseManager @this, DateTime cDate)
{
try {
var cCancellationToken = @this._synchronizationTaskCancellationTokenSource.Token;
var cDelayToTask = TaskExtension.DelayTo(cDate, cCancellationToken);
await cDelayToTask.ConfigureAwait(false);
}
catch (OperationCanceledException) {
// ...
//
// We don't care if the cancellation token is cancelled.
}
}
// <summary>
// Get Threat List Updates Asynchronously.
// </summary>
async Task <(ThreatListUpdateResponse, DateTime)> GetThreatListUpdatesAsync(BrowsingDatabaseManager @this)
{
var cDelayToDate = DateTime.UtcNow.AddMinutes(30);
try {
IEnumerable <ThreatListDescriptor> cThreatListDescriptors = @this._updateConstraints.Keys;
if (@this._updateConstraints.Count == 0)
{
// ...
//
// If the database synchronizer is not restricted to specific threat lists, we retrieve all
// available threat lists from the Google Safe Browsing API. We don't cache the result in case
// new threat lists are made available between synchronization iterations.
//
// Throws an exception if the operation fails.
var cGetThreatListDescriptorsTask = @this._client.GetThreatListDescriptorsAsync();
cThreatListDescriptors = await cGetThreatListDescriptorsTask.ConfigureAwait(false);
}
// ...
//
// Retrieve the threat lists from the database. Throws an exception if the operation fails.
var cGetThreatListsTask = @this._database.GetThreatListsAsync(cThreatListDescriptors);
var cThreatLists = await cGetThreatListsTask.ConfigureAwait(false);
ThreatListUpdateRequestBuilder cThreatListUpdateRequestBuilder = null;
foreach (var cThreatList in cThreatLists)
{
if (cThreatList.Expired)
{
cThreatListUpdateRequestBuilder = cThreatListUpdateRequestBuilder ?? ThreatListUpdateRequest.Build();
var cThreatListDescriptor = cThreatList.Descriptor;
var cThreatListState = cThreatList.State;
@this._updateConstraints.TryGetValue(cThreatListDescriptor, out var cThreatListUpdateConstraints);
cThreatListUpdateRequestBuilder.AddQuery(b => {
b.SetThreatListDescriptor(cThreatListDescriptor);
b.SetThreatListState(cThreatListState);
b.SetUpdateConstraints(cThreatListUpdateConstraints);
return(b.Build());
});
}
else
{
if (cThreatList.WaitToDate != null && cThreatList.WaitToDate < cDelayToDate)
{
// ...
//
// If the current threat list's wait to date is earlier than the previous threat
// list's wait to date, take the current the threat list's wait to date instead.
cDelayToDate = cThreatList.WaitToDate.Value;
}
}
}
ThreatListUpdateResponse cThreatListUpdateResponse = null;
if (cThreatListUpdateRequestBuilder != null)
{
// ...
//
// Throws an exception if the operation fails.
var cThreatListUpdateRequest = cThreatListUpdateRequestBuilder.Build();
var cGetThreatListUpdatesTask = @this._client.GetThreatListUpdatesAsync(cThreatListUpdateRequest);
cThreatListUpdateResponse = await cGetThreatListUpdatesTask.ConfigureAwait(false);
}
return(cThreatListUpdateResponse, cDelayToDate);
}
catch {
return(null, cDelayToDate);
}
}
// <summary>
// Synchronize Threat List Asynchronously.
// </summary>
async Task SynchronizeThreatListAsync(BrowsingDatabaseManager @this, ThreatListUpdateResult cThreatListUpdateResult)
{
var cSynchronizationStartDate = DateTime.UtcNow;
var cThreatList = cThreatListUpdateResult.RetrievedThreatList;
try {
var cSha256HashPrefixes = cThreatListUpdateResult.ThreatsToAdd;
if (cThreatListUpdateResult.IsFullUpdate)
{
// ...
//
// Throws an exception if the operation fails.
var cModifyThreatListTask = @this._database.StoreThreatListAsync(cThreatList, cSha256HashPrefixes);
await cModifyThreatListTask.ConfigureAwait(false);
}
else if (cThreatListUpdateResult.IsPartialUpdate)
{
// ...
//
// Throws an exception if the operation fails.
var cIndices = cThreatListUpdateResult.ThreatsToRemove;
var cModifyThreatListTask = @this._database.ModifyThreatListAsync(cThreatList, cSha256HashPrefixes, cIndices);
await cModifyThreatListTask.ConfigureAwait(false);
}
// ...
//
// Throws an exception if the operation fails.
var cComputeThreatListChecksumTask = @this._database.ComputeThreatListChecksumAsync(cThreatList.Descriptor);
var cThreatListChecksum = await cComputeThreatListChecksumTask.ConfigureAwait(false);
if (cThreatListChecksum != cThreatListUpdateResult.RetrievedThreatListChecksum)
{
// ...
//
// Throws an exception if the operation fails.
cThreatList = ThreatList.CreateInvalid(cThreatList.Descriptor);
var cUpdateConstraints = cThreatListUpdateResult.Query.UpdateConstraints;
var cGetThreatListUpdatesTask = @this._client.GetThreatListUpdatesAsync(cThreatList, cUpdateConstraints);
var cThreatListUpdateRequest = await cGetThreatListUpdatesTask.ConfigureAwait(false);
cThreatListUpdateResult = cThreatListUpdateRequest.Results.First();
cSha256HashPrefixes = cThreatListUpdateResult.ThreatsToAdd;
if (cThreatListUpdateResult.IsFullUpdate)
{
// ...
//
// Throws an exception if the operation fails.
cThreatList = cThreatListUpdateResult.RetrievedThreatList;
var cModifyThreatListTask = @this._database.StoreThreatListAsync(cThreatList, cSha256HashPrefixes);
await cModifyThreatListTask.ConfigureAwait(false);
}
}
// ...
//
// Invoke threat list synchronization completed event.
var cSynchronizationCompletionDate = DateTime.UtcNow;
@this.OnThreatListSynchronizationCompleted(new ThreatListSynchronizationCompletedEventArgs(
cThreatList,
cSynchronizationStartDate,
cSynchronizationCompletionDate
));
}
catch (Exception cEx) {
// ...
//
// Invoke threat list synchronization failed event.
var cSynchronizationFailureDate = DateTime.UtcNow;
@this.OnThreatListSynchronizationFailed(new ThreatListSynchronizationFailedEventArgs(
cThreatList,
cSynchronizationStartDate,
cSynchronizationFailureDate,
cEx
));
}
}
}
