53 lines
1.8 KiB
C#
53 lines
1.8 KiB
C#
// Copyright (C) 2023-present sam/u1f320 (vulpine.solutions)
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//
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// This program is free software: you can redistribute it and/or modify
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// it under the terms of the GNU Affero General Public License as published
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// by the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// This program is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU Affero General Public License for more details.
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//
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// You should have received a copy of the GNU Affero General Public License
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// along with this program. If not, see <https://www.gnu.org/licenses/>.
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using System.Collections.Concurrent;
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using System.Threading.RateLimiting;
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using NodaTime;
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using NodaTime.Extensions;
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namespace Foxnouns.Backend.Services;
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public class EmailRateLimiter
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{
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private readonly ConcurrentDictionary<string, RateLimiter> _limiters = new();
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private readonly FixedWindowRateLimiterOptions _limiterOptions = new()
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{
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Window = TimeSpan.FromHours(2),
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PermitLimit = 3,
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};
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private RateLimiter GetLimiter(string bucket) =>
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_limiters.GetOrAdd(bucket, _ => new FixedWindowRateLimiter(_limiterOptions));
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public bool IsLimited(string bucket, out Duration retryAfter)
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{
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RateLimiter limiter = GetLimiter(bucket);
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RateLimitLease lease = limiter.AttemptAcquire();
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if (!lease.IsAcquired)
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{
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retryAfter = lease.TryGetMetadata(MetadataName.RetryAfter, out TimeSpan timeSpan)
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? timeSpan.ToDuration()
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: default;
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}
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else
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{
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retryAfter = Duration.Zero;
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}
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return !lease.IsAcquired;
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}
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}
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