private bool RateLimit(string hostname, string channel)
{
if (string.IsNullOrEmpty(hostname) || string.IsNullOrEmpty(channel))
{
// sanity check - this probably chanserv.
this.logger.Error("JoinMessage ratelimiting called with null channel or null hostname!");
return(true);
}
try
{
// TODO: rate limiting needs to be tidyed up a bit
lock (this.rateLimitCache)
{
if (!this.rateLimitCache.ContainsKey(channel))
{
this.rateLimitCache.Add(channel, new Cache());
}
var channelCache = this.rateLimitCache[channel];
if (channelCache.ContainsKey(hostname))
{
this.logger.Debug("Rate limit key found.");
var cacheEntry = channelCache[hostname];
if (cacheEntry.Expiry.AddMinutes(this.configuration.RateLimitDuration) >= DateTime.Now)
{
this.logger.Debug("Rate limit key NOT expired.");
if (cacheEntry.Counter >= this.configuration.RateLimitMax)
{
this.logger.Debug("Rate limit HIT");
// RATE LIMITED!
return(true);
}
this.logger.Debug("Rate limit incremented.");
// increment counter
cacheEntry.Counter++;
}
else
{
this.logger.Debug("Rate limit key is expired, resetting to new value.");
// Cache expired
cacheEntry.Expiry = DateTime.Now;
cacheEntry.Counter = 1;
}
}
else
{
this.logger.Debug("Rate limit not found, creating key.");
// Not in cache.
var cacheEntry = new RateLimitCacheEntry {
Expiry = DateTime.Now, Counter = 1
};
channelCache.Add(hostname, cacheEntry);
}
// Clean up the channel's cache.
foreach (var key in channelCache.Keys.ToList())
{
if (channelCache[key].Expiry.AddMinutes(this.configuration.RateLimitDuration) < DateTime.Now)
{
// Expired.
channelCache.Remove(key);
}
}
}
}
catch (Exception ex)
{
// ooh dear. Something went wrong with rate limiting.
this.logger.Error("Unknown error during rate limit processing.", ex);
return(false);
}
return(false);
}
private void CreateOrUpdateCacheEntry(string key, RateLimitCacheEntry entry, TimeSpan span)
{
var cacheOpts = new MemoryCacheEntryOptions().SetPriority(CacheItemPriority.High).SetAbsoluteExpiration(span).RegisterPostEvictionCallback(EvictionNotice);
memoryCache.Set <RateLimitCacheEntry>(key, entry, cacheOpts);
}
public async Task OnPageHandlerExecutionAsync(PageHandlerExecutingContext context, PageHandlerExecutionDelegate next)
{
RateLimitCacheEntry cacheRec = null;
string path = context.ActionDescriptor.ViewEnginePath;
string method = context.HttpContext.Request.Method;
// string method = context.HandlerMethod.HttpMethod;
string key = RateLimitRule.MakeRuleKey(path, method);
if (rateLimits.RateLimitRuleMatches(key))
{
logger?.LogDebug($"Limit rule for page: {path} and method: {method} matched");
string filterKey = rateLimits.FilterKey.BuildKey(context);
string filterKeyName = rateLimits.FilterKey.GetFilterKeyName();
if (rateLimits.IsWhitelisted(filterKey))
{
logger?.LogDebug($"Rate ignored for whitelisted {filterKeyName}: {filterKey}");
}
else
{
var rule = rateLimits.GetRateLimitByKey(key);
var ruleLimits = rule.RequestLimits;
var cacheKeys = GetTimeUnitCacheKeys(path, method, filterKey, filterKeyName).ToArray();
DateTime now = DateTime.UtcNow;
// limit for this page and method is in effect, check cache entries for each time unit (minute, hour, day)
for (int z = 0; z < 3; z++)
{
if (ruleLimits[z] == 0)
{
// zero means don't do limiting for this time unit
logger?.LogDebug($"Rate-limiting disabled for per-{rule.GetTimeUnitName(z)}");
}
else
{
bool exists = memoryCache.TryGetValue <RateLimitCacheEntry>(cacheKeys[z], out cacheRec);
if (exists)
{
if (cacheRec.IsExpired(now))
{
// there's no guarantee the system will auto-expire entries on time, so we have to manually check them
logger?.LogDebug($"Manual delete of expired cache key for {rule.GetRuleDesc(z)} for {filterKeyName} {filterKey}");
memoryCache.Remove(cacheKeys[z]); // dump the old cache entry
// create a new cache entry
cacheRec = new RateLimitCacheEntry(spans[z]);
CreateOrUpdateCacheEntry(cacheKeys[z], cacheRec, spans[z]);
}
else
{
TimeSpan timeRemaining = cacheRec.CalcRemainingTime(now);
int totSecs = Convert.ToInt32(timeRemaining.TotalSeconds) + 1;
string timeRemainingStr = cacheRec.BuildTimeCountdownStringFromSpan(timeRemaining);
if (cacheRec.ReqCnt + 1 > ruleLimits[z])
{
// cache limit has been exceeded - return 429
logger?.LogDebug($"Rule limit ({cacheRec.ReqCnt}) exceeded for {rule.GetRuleDesc(z)} for Filter: {filterKeyName}, Key: {filterKey}");
context.HttpContext.Response.Headers.Add("Retry-After", totSecs.ToString());
context.Result = new ContentResult {
// StatusCode = (int) HttpStatusCode.TooManyRequests,
StatusCode = 429,
ContentType = "text/html",
Content = $"Request quota ({rule.GetRuleDesc(z)}) exceeded. Try again in {timeRemainingStr}."
};
return;
}
else
{
logger?.LogDebug($"Time remaining on cache entry per {rule.GetTimeUnitName(z)}: {timeRemainingStr} for Filter: {filterKeyName}, Key: {filterKey}");
logger?.LogDebug($"Adding 1 to count ({cacheRec.ReqCnt}) per {rule.GetTimeUnitName(z)} for Filter: {filterKeyName}, Key: {filterKey}");
cacheRec.ReqCnt += 1;
// pass in new time left based on original starting time and span
CreateOrUpdateCacheEntry(cacheKeys[z], cacheRec, cacheRec.CalcRemainingTime(now));
}
}
}
else
{
// doesn't exist in cache, so we'll create it fresh
cacheRec = new RateLimitCacheEntry(spans[z]);
CreateOrUpdateCacheEntry(cacheKeys[z], cacheRec, spans[z]);
}
}
}
}
}
else
{
logger?.LogDebug($"No limit rule for page: {path} and method: {method}");
}
await next.Invoke();
}
private bool RateLimit(IUser source, int id)
{
if (source == null || source.Hostname == null)
{
this.Logger.Error("Rate limiting called with no source or no source hostname!");
return(true);
}
var cacheKey = string.Format("{1}|{0}", source.Hostname, id);
lock (RateLimitCache)
{
if (RateLimitCache.ContainsKey(cacheKey))
{
this.Logger.Debug("Rate limit key found.");
var cacheEntry = RateLimitCache[cacheKey];
if (cacheEntry.Expiry.AddMinutes(this.config.RateLimitDuration) >= DateTime.Now)
{
this.Logger.Debug("Rate limit key NOT expired.");
if (cacheEntry.Counter >= this.config.RateLimitMax)
{
this.Logger.Debug("Rate limit HIT");
// RATE LIMITED!
return(true);
}
this.Logger.Debug("Rate limit incremented.");
// increment counter
cacheEntry.Counter++;
}
else
{
this.Logger.Debug("Rate limit key is expired, resetting to new value.");
// Cache expired
cacheEntry.Expiry = DateTime.Now;
cacheEntry.Counter = 1;
}
}
else
{
this.Logger.Debug("Rate limit not found, creating key.");
// Not in cache.
var cacheEntry = new RateLimitCacheEntry {
Expiry = DateTime.Now, Counter = 1
};
RateLimitCache.Add(cacheKey, cacheEntry);
}
// Clean up the cache
foreach (var key in RateLimitCache.Keys.ToList())
{
if (RateLimitCache[key].Expiry.AddMinutes(this.config.RateLimitDuration) < DateTime.Now)
{
// Expired.
RateLimitCache.Remove(key);
}
}
}
return(false);
}
