/// <summary>
/// Is this a dos attack?
/// </summary>
public (bool ShouldBlockClient, ThrottleInfo?ThrottleInfo) IsDosAttack(AntiDosFirewallRequestInfo requestInfo)
{
var key = GetCacheKey(requestInfo);
var expiresAt = GetCacheExpiresAt();
if (!_cacheService.TryGetValue <ThrottleInfo>(key, out var clientThrottleInfo))
{
clientThrottleInfo = new ThrottleInfo {
RequestsCount = 1, ExpiresAt = expiresAt
};
_cacheService.Add(key, clientThrottleInfo, expiresAt, size: 1);
return(false, clientThrottleInfo);
}
if (clientThrottleInfo.RequestsCount > _antiDosConfig.Value.AllowedRequests)
{
clientThrottleInfo.BanReason = "IsDosAttack";
_cacheService.Add(key, clientThrottleInfo, expiresAt, size: 1);
return(true, clientThrottleInfo);
}
clientThrottleInfo.RequestsCount++;
_cacheService.Add(key, clientThrottleInfo, expiresAt, size: 1);
return(false, clientThrottleInfo);
}
private void addResetHeaders(HttpContext context, ThrottleInfo throttleInfo)
{
if (throttleInfo == null)
{
return;
}
context.Response.Headers["X-RateLimit-Limit"] = _antiDosConfig.Value.AllowedRequests.ToString();
var requestsRemaining = Math.Max(_antiDosConfig.Value.AllowedRequests - throttleInfo.RequestsCount, 0);
context.Response.Headers["X-RateLimit-Remaining"] = requestsRemaining.ToString();
context.Response.Headers["X-RateLimit-Reset"] = throttleInfo.ExpiresAt.ToUnixTimeSeconds().ToString();
context.Response.Headers["Retry-After"] = context.Response.Headers["X-RateLimit-Reset"];
}