feat: validate random number count and prevent duplicate generation

Author: jason-aelf

src/RandomContract.cs

@@ -59,10 +59,14 @@ public override Empty SetMaxRandomNumberCount(Int32Value input)
 
     public override Empty GenerateRandomNumber(GenerateRandomNumberInput input)
     {
+        // Check if the random number is already generated
+        Assert(State.RandomNumbers[input.Hash] == null, "Random number already generated.");
         // Check if the maxValue is valid
         Assert(input.MaxValue > 0 && input.MaxValue <= State.MaxValueLimit.Value, "Invalid max value.");
         // Check if the random number count is valid
-        Assert(input.RandomNumberCount > 0 && input.RandomNumberCount <= State.MaxRandomNumberCount.Value, "Invalid random number count.");
+        Assert(
+            input.RandomNumberCount > 0 && input.RandomNumberCount <= State.MaxRandomNumberCount.Value &&
+            input.RandomNumberCount <= input.MaxValue, "Invalid random number count.");
         // Get a random hash and check if it is available
         var randomHash = State.ConsensusContract.GetRandomHash.Call(new Int64Value
         {

src/RandomContract.csproj

@@ -4,7 +4,6 @@
         <RootNamespace>AElf.Contracts.RandomContract</RootNamespace>
         <IsContract>true</IsContract>
         <CheckForOverflowUnderflow>true</CheckForOverflowUnderflow>
-        <AssemblyVersion>1.0.0.0</AssemblyVersion>
     </PropertyGroup>
     <PropertyGroup>
         <ObjPath>$(MSBuildProjectDirectory)/$(BaseIntermediateOutputPath)$(Configuration)/$(TargetFramework)/</ObjPath>

test/RandomContractTests.cs

@@ -186,6 +186,7 @@ public async Task GenerateRandomNumberTest()
         // Generate 100 random number
         randomNumberCount = 10;
         maxValue = 100;
+        hash = "Test";
         result = await RandomContractStub.GenerateRandomNumber.SendAsync(new GenerateRandomNumberInput
         {
             Hash = hash,
@@ -213,6 +214,17 @@ public async Task GenerateRandomNumberTest()
             randomSet.Add(randomNumber);
         }
 
+        // Generate random number with same hash and expect an exception
+        result = await RandomContractStub.GenerateRandomNumber.SendWithExceptionAsync(new GenerateRandomNumberInput
+        {
+            Hash = hash,
+            RandomNumberCount = randomNumberCount,
+            MaxValue = maxValue
+        });
+        result.TransactionResult.Status.ShouldBe(TransactionResultStatus.Failed);
+        result.TransactionResult.Error.ShouldContain("Random number already generated");
+        
+        hash = "OtherHash";
         // Generate random number with invalid max value and expect an exception
         result = await RandomContractStub.GenerateRandomNumber.SendWithExceptionAsync(new GenerateRandomNumberInput
         {
@@ -246,6 +258,15 @@ public async Task GenerateRandomNumberTest()
         {
             Hash = hash,
             RandomNumberCount = maxRandomNumberCount + 1,
+            MaxValue = maxValueLimit
+        });
+        result.TransactionResult.Status.ShouldBe(TransactionResultStatus.Failed);
+        result.TransactionResult.Error.ShouldContain("Invalid random number count");
+        
+        result = await RandomContractStub.GenerateRandomNumber.SendWithExceptionAsync(new GenerateRandomNumberInput
+        {
+            Hash = hash,
+            RandomNumberCount = maxValue + 1,
             MaxValue = maxValue
         });
         result.TransactionResult.Status.ShouldBe(TransactionResultStatus.Failed);