protected RateLimitMiddleware(
RequestDelegate next,
RateLimitOptions options,
TProcessor processor,
IRateLimitConfiguration config)
{
_next = next;
_options = options;
_processor = processor;
_config = config;
}
protected RateLimitProcessor(
RateLimitOptions options,
IRateLimitCounterStore counterStore,
ICounterKeyBuilder counterKeyBuilder,
IRateLimitConfiguration config)
{
_options = options;
_counterStore = counterStore;
_counterKeyBuilder = counterKeyBuilder;
_config = config;
}
protected virtual string BuildCounterKey(ClientRequestIdentity requestIdentity, RateLimitRule rule, ICounterKeyBuilder counterKeyBuilder, RateLimitOptions rateLimitOptions)
{
var key = counterKeyBuilder.Build(requestIdentity, rule);
if (rateLimitOptions.EnableEndpointRateLimiting && _config.EndpointCounterKeyBuilder != null)
{
key += _config.EndpointCounterKeyBuilder.Build(requestIdentity, rule);
}
var bytes = Encoding.UTF8.GetBytes(key);
using var algorithm = new SHA1Managed();
var hash = algorithm.ComputeHash(bytes);
return(Convert.ToBase64String(hash));
}
public abstract Task <RateLimitCounter> ProcessRequestAsync(ClientRequestIdentity requestIdentity, RateLimitRule rule, ICounterKeyBuilder counterKeyBuilder, RateLimitOptions rateLimitOptions, CancellationToken cancellationToken = default);
protected RateLimitProcessor(RateLimitOptions options)
{
_options = options;
}
public override async Task <RateLimitCounter> ProcessRequestAsync(ClientRequestIdentity requestIdentity, RateLimitRule rule, ICounterKeyBuilder counterKeyBuilder, RateLimitOptions rateLimitOptions, CancellationToken cancellationToken = default)
{
var counter = new RateLimitCounter
{
Timestamp = DateTime.UtcNow,
Count = 1
};
var counterId = BuildCounterKey(requestIdentity, rule, counterKeyBuilder, rateLimitOptions);
// serial reads and writes on same key
using (await AsyncLock.WriterLockAsync(counterId).ConfigureAwait(false))
{
var entry = await _counterStore.GetAsync(counterId, cancellationToken);
if (entry.HasValue)
{
// entry has not expired
if (entry.Value.Timestamp + rule.PeriodTimespan.Value >= DateTime.UtcNow)
{
// increment request count
var totalCount = entry.Value.Count + _config.RateIncrementer?.Invoke() ?? 1;
// deep copy
counter = new RateLimitCounter
{
Timestamp = entry.Value.Timestamp,
Count = totalCount
};
}
}
// stores: id (string) - timestamp (datetime) - total_requests (long)
await _counterStore.SetAsync(counterId, counter, rule.PeriodTimespan.Value, cancellationToken);
}
return(counter);
}