Add a better random number generator

Geekbot.net/Commands/Games/Roll.cs

@@ -8,6 +8,7 @@ using Geekbot.net.Lib.AlmostRedis;
 using Geekbot.net.Lib.ErrorHandling;
 using Geekbot.net.Lib.Extensions;
 using Geekbot.net.Lib.Localization;
+using Geekbot.net.Lib.RandomNumberGenerator;
 using StackExchange.Redis;
 
 namespace Geekbot.net.Commands.Games
@@ -18,12 +19,14 @@ namespace Geekbot.net.Commands.Games
         private readonly IAlmostRedis _redis;
         private readonly ITranslationHandler _translation;
         private readonly DatabaseContext _database;
+        private readonly IRandomNumberGenerator _randomNumberGenerator;
 
-        public Roll(IAlmostRedis redis, IErrorHandler errorHandler, ITranslationHandler translation, DatabaseContext database)
+        public Roll(IAlmostRedis redis, IErrorHandler errorHandler, ITranslationHandler translation, DatabaseContext database, IRandomNumberGenerator randomNumberGenerator)
         {
             _redis = redis;
             _translation = translation;
             _database = database;
+            _randomNumberGenerator = randomNumberGenerator;
             _errorHandler = errorHandler;
         }
 
@@ -33,7 +36,7 @@ namespace Geekbot.net.Commands.Games
         {
             try
             {
-                var number = new Random().Next(1, 100);
+                var number = _randomNumberGenerator.Next(1, 100);
                 var guess = 1000;
                 int.TryParse(stuff, out guess);
                 var transDict = await _translation.GetDict(Context);

Geekbot.net/Commands/Randomness/Ship.cs

@@ -7,18 +7,21 @@ using Geekbot.net.Database;
 using Geekbot.net.Database.Models;
 using Geekbot.net.Lib.ErrorHandling;
 using Geekbot.net.Lib.Extensions;
+using Geekbot.net.Lib.RandomNumberGenerator;
 
 namespace Geekbot.net.Commands.Randomness
 {
     public class Ship : ModuleBase
     {
         private readonly IErrorHandler _errorHandler;
+        private readonly IRandomNumberGenerator _randomNumberGenerator;
         private readonly DatabaseContext _database;
 
-        public Ship(DatabaseContext database, IErrorHandler errorHandler)
+        public Ship(DatabaseContext database, IErrorHandler errorHandler, IRandomNumberGenerator randomNumberGenerator)
         {
             _database = database;
             _errorHandler = errorHandler;
+            _randomNumberGenerator = randomNumberGenerator;
         }
 
         [Command("Ship", RunMode = RunMode.Async)]
@@ -38,7 +41,7 @@ namespace Geekbot.net.Commands.Randomness
                 var shippingRate = 0;
                 if (dbval == null)
                 {
-                    shippingRate = new Random().Next(1, 100);
+                    shippingRate = _randomNumberGenerator.Next(1, 100);
                     _database.Ships.Add(new ShipsModel()
                     {
                         FirstUserId = userKeys.Item1,

Geekbot.net/Commands/Rpg/Cookies.cs

@@ -9,6 +9,7 @@ using Geekbot.net.Lib.CommandPreconditions;
 using Geekbot.net.Lib.ErrorHandling;
 using Geekbot.net.Lib.Extensions;
 using Geekbot.net.Lib.Localization;
+using Geekbot.net.Lib.RandomNumberGenerator;
 
 namespace Geekbot.net.Commands.Rpg
 {
@@ -19,12 +20,14 @@ namespace Geekbot.net.Commands.Rpg
         private readonly DatabaseContext _database;
         private readonly IErrorHandler _errorHandler;
         private readonly ITranslationHandler _translation;
+        private readonly IRandomNumberGenerator _randomNumberGenerator;
 
-        public Cookies(DatabaseContext database, IErrorHandler errorHandler, ITranslationHandler translation)
+        public Cookies(DatabaseContext database, IErrorHandler errorHandler, ITranslationHandler translation , IRandomNumberGenerator randomNumberGenerator)
         {
             _database = database;
             _errorHandler = errorHandler;
             _translation = translation;
+            _randomNumberGenerator = randomNumberGenerator;
         }
 
         [Command("get", RunMode = RunMode.Async)]
@@ -114,7 +117,7 @@ namespace Geekbot.net.Commands.Rpg
                     return;
                 }
 
-                var amount = new Random().Next(1, 5);
+                var amount = _randomNumberGenerator.Next(1, 5);
                 actor.Cookies -= amount;
                 
                 await SetUser(actor);

Geekbot.net/Commands/Utils/Dice/Dice.cs

@@ -4,11 +4,19 @@ using System.Linq;
 using System.Text;
 using System.Threading.Tasks;
 using Discord.Commands;
+using Geekbot.net.Lib.RandomNumberGenerator;
 
 namespace Geekbot.net.Commands.Utils.Dice
 {
     public class Dice : ModuleBase
     {
+        private readonly IRandomNumberGenerator _randomNumberGenerator;
+
+        public Dice(IRandomNumberGenerator randomNumberGenerator)
+        {
+            _randomNumberGenerator = randomNumberGenerator;
+        }
+        
         [Command("dice", RunMode = RunMode.Async)]
         [Summary("Roll a dice.")]
         public async Task RollCommand([Remainder] [Summary("diceType")] string diceType = "1d20")
@@ -66,7 +74,7 @@ namespace Geekbot.net.Commands.Utils.Dice
                 var results = new List<int>();
                 for (var i = 0; i < dice.Times; i++)
                 {
-                    var roll = new Random().Next(1, dice.Sides);
+                    var roll = _randomNumberGenerator.Next(1, dice.Sides);
                     total += roll;
                     results.Add(roll);
                     if (roll == dice.Sides) extraText = "**Critical Hit!**";

Geekbot.net/Commands/Utils/Quote/Quote.cs

@@ -9,6 +9,7 @@ using Geekbot.net.Lib.CommandPreconditions;
 using Geekbot.net.Lib.ErrorHandling;
 using Geekbot.net.Lib.Extensions;
 using Geekbot.net.Lib.Polyfills;
+using Geekbot.net.Lib.RandomNumberGenerator;
 
 namespace Geekbot.net.Commands.Utils.Quote
 {
@@ -18,11 +19,13 @@ namespace Geekbot.net.Commands.Utils.Quote
     {
         private readonly IErrorHandler _errorHandler;
         private readonly DatabaseContext _database;
+        private readonly IRandomNumberGenerator _randomNumberGenerator;
 
-        public Quote(IErrorHandler errorHandler, DatabaseContext database)
+        public Quote(IErrorHandler errorHandler, DatabaseContext database, IRandomNumberGenerator randomNumberGenerator)
         {
             _errorHandler = errorHandler;
             _database = database;
+            _randomNumberGenerator = randomNumberGenerator;
         }
 
         [Command]
@@ -39,7 +42,7 @@ namespace Geekbot.net.Commands.Utils.Quote
                     return;
                 }
 
-                var random = new Random().Next(s.Count());
+                var random = _randomNumberGenerator.Next(0, s.Count());
                 var quote = s[random];
                 
                 var embed = QuoteBuilder(quote);

Geekbot.net/Lib/RandomNumberGenerator/IRandomNumberGenerator.cs

@@ -0,0 +1,7 @@
+namespace Geekbot.net.Lib.RandomNumberGenerator
+{
+    public interface IRandomNumberGenerator
+    {
+        int Next(int minValue, int maxExclusiveValue);
+    }
+}

Geekbot.net/Lib/RandomNumberGenerator/RandomNumberGenerator.cs

@@ -0,0 +1,46 @@
+using System;
+using System.Security.Cryptography;
+
+namespace Geekbot.net.Lib.RandomNumberGenerator
+{
+    public class RandomNumberGenerator : IRandomNumberGenerator
+    {
+        readonly RNGCryptoServiceProvider csp;
+
+        public RandomNumberGenerator()
+        {
+            csp = new RNGCryptoServiceProvider();
+        }
+
+        public int Next(int minValue, int maxExclusiveValue)
+        {
+            if (minValue >= maxExclusiveValue)
+            {
+                throw new ArgumentOutOfRangeException("minValue must be lower than maxExclusiveValue");
+            }
+
+            var diff = (long)maxExclusiveValue - minValue;
+            var upperBound = uint.MaxValue / diff * diff;
+
+            uint ui;
+            do
+            {
+                ui = GetRandomUInt();
+            } while (ui >= upperBound);
+            return (int)(minValue + (ui % diff));
+        }
+
+        private uint GetRandomUInt()
+        {
+            var randomBytes = GenerateRandomBytes(sizeof(uint));
+            return BitConverter.ToUInt32(randomBytes, 0);
+        }
+
+        private byte[] GenerateRandomBytes(int bytesNumber)
+        {
+            var buffer = new byte[bytesNumber];
+            csp.GetBytes(buffer);
+            return buffer;
+        }
+    }
+}

Geekbot.net/Program.cs

@@ -19,6 +19,7 @@ using Geekbot.net.Lib.Levels;
 using Geekbot.net.Lib.Localization;
 using Geekbot.net.Lib.Logger;
 using Geekbot.net.Lib.Media;
+using Geekbot.net.Lib.RandomNumberGenerator;
 using Geekbot.net.Lib.ReactionListener;
 using Geekbot.net.Lib.UserRepository;
 using Microsoft.EntityFrameworkCore;
@@ -124,6 +125,7 @@ namespace Geekbot.net
             var mtgManaConverter = new MtgManaConverter();
             var wikipediaClient = new WikipediaClient();
             var audioUtils = new AudioUtils();
+            var randomNumberGenerator = new RandomNumberGenerator();
             _highscoreManager = new HighscoreManager(_databaseInitializer.Initialize(), _userRepository);
             
             _services.AddSingleton<IAlmostRedis>(_redis);
@@ -137,6 +139,7 @@ namespace Geekbot.net
             _services.AddSingleton<IMtgManaConverter>(mtgManaConverter);
             _services.AddSingleton<IWikipediaClient>(wikipediaClient);
             _services.AddSingleton<IAudioUtils>(audioUtils);
+            _services.AddSingleton<IRandomNumberGenerator>(randomNumberGenerator);
             _services.AddSingleton<IHighscoreManager>(_highscoreManager);
             _services.AddSingleton<IGlobalSettings>(_globalSettings);
             _services.AddTransient<DatabaseContext>((e) => _databaseInitializer.Initialize());