44 lines
1.4 KiB
C#
44 lines
1.4 KiB
C#
 
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using MongoDB.Entities;
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using PrivaPub.Models.Statistics;
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using System.Collections.Concurrent;
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using System.Security.Cryptography;
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using System.Text;
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namespace PrivaPub.Infrastructure.Statistics
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{
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public class InteractionSalts
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{
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readonly ConcurrentDictionary<DateTime, byte[]> _known = new();
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public async Task<byte[]> For(DateTime day, CancellationToken token)
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{
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day = day.Date;
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if (_known.TryGetValue(day, out var cached))
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return cached;
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InteractionSalt salt;
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if (day == DateTime.UtcNow.Date)
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salt = await DB.Default.UpdateAndGet<InteractionSalt>()
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.Match(s => s.Day == day)
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.Modify(b => b.SetOnInsert(s => s.Key, Convert.ToBase64String(RandomNumberGenerator.GetBytes(32))))
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.Modify(b => b.SetOnInsert(s => s.ExpiresAt, day.AddHours(30)))
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.Option(o => o.IsUpsert = true)
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.ExecuteAsync(token);
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else
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salt = await DB.Default.Find<InteractionSalt>().Match(s => s.Day == day).ExecuteFirstAsync(token);
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if (salt?.Key == default)
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return default;
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var key = Convert.FromBase64String(salt.Key);
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foreach (var old in _known.Keys.Where(k => k < day.AddDays(-1)))
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_known.TryRemove(old, out _);
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_known[day] = key;
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return key;
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}
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public static string Hash(byte[] salt, string actorUri) =>
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salt == default || string.IsNullOrEmpty(actorUri)
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? default
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: Convert.ToBase64String(HMACSHA256.HashData(salt, Encoding.UTF8.GetBytes(actorUri))[..12]).TrimEnd('=').Replace('+', '-').Replace('/', '_');
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}
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}
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