public void OnEvent(HttpContextBase context)
{
HttpRequestBase request = context.Request;
HttpResponseBase response = context.Response;
// get policy from repo
if (policyRepository != null)
{
policy = policyRepository.FirstOrDefault(ThrottleManager.GetPolicyKey());
}
if (policy == null || (!policy.IpThrottling && !policy.ClientThrottling && !policy.EndpointThrottling))
{
response.StatusCode = (int)HttpStatusCode.OK;
return;
}
core.Repository = Repository;
core.Policy = policy;
var identity = SetIdentity(request);
if (core.IsWhitelisted(identity))
{
response.StatusCode = (int)HttpStatusCode.OK;
return;
}
if (policy.Endpoints != null && policy.Endpoints.Count > 0)
{
if (!core.IsEndpointMonitored(identity))
{
response.StatusCode = (int)HttpStatusCode.OK;
return;
}
}
TimeSpan timeSpan = TimeSpan.FromSeconds(1);
// get default rates
var defRates = core.RatesWithDefaults(Policy.Rates.ToList());
if (Policy.StackBlockedRequests)
{
// all requests including the rejected ones will stack in this order: week, day, hour, min, sec
// if a client hits the hour limit then the minutes and seconds counters will expire and will eventually get erased from cache
defRates.Reverse();
}
// apply policy
foreach (var rate in defRates)
{
var rateLimitPeriod = rate.Key;
var rateLimit = rate.Value;
timeSpan = core.GetTimeSpanFromPeriod(rateLimitPeriod);
// apply global rules
core.ApplyRules(identity, timeSpan, rateLimitPeriod, ref rateLimit);
if (rateLimit > 0)
{
// increment counter
var requestId = ComputeThrottleKey(identity, rateLimitPeriod);
var throttleCounter = core.ProcessRequest(timeSpan, requestId);
// check if key expired
if (throttleCounter.Timestamp + timeSpan < DateTime.UtcNow)
{
continue;
}
// check if limit is reached
if (throttleCounter.TotalRequests > rateLimit)
{
// log blocked request
if (Logger != null)
{
Logger.Log(core.ComputeLogEntry(requestId, identity, throttleCounter, rateLimitPeriod.ToString(), rateLimit, request));
}
var message = !string.IsNullOrEmpty(this.QuotaExceededMessage)
? this.QuotaExceededMessage
: "API calls quota exceeded! maximum admitted {0} per {1}.";
var content = this.QuotaExceededContent != null
? this.QuotaExceededContent(rateLimit, rateLimitPeriod)
: string.Format(message, rateLimit, rateLimitPeriod);
// break execution
response.StatusCode = (int)QuotaExceededResponseCode;
response.AddHeader("Retry-After", core.RetryAfterFrom(throttleCounter.Timestamp, rateLimitPeriod));
response.Write(content);
return;
}
}
}
// no throttling required
response.StatusCode = (int)HttpStatusCode.OK;
return;
}
