Add random select of fee address

Sending all fees to same address will make funds on that address
unspendable - it will never be enough confirmations on top of last
transactions. Taking random address from pool will prevent this issue.

Sources/NBitcoin/Networks/DeStreamMain.cs

@@ -9,12 +9,20 @@ namespace NBitcoin
 {
     public abstract partial class Network
     {
-        // TODO: Implement custom circular collection
-        public readonly IReadOnlyCollection<string> DeStreamWallets = new ReadOnlyCollection<string>(new List<string>()
+        private readonly LinkedList<string> _deStreamWallets = new LinkedList<string>(new []
         {
             "DQAa8Fg1ytS5wiXbn1qToRpe9wYSQhCAWc",
             "DMoFqYQNfsoorMbmTbyErxk43ev9B2EuEe",
-        });
+        }.OrderBy(p => Guid.NewGuid()));
+
+        private LinkedListNode<string> DeStreamWalletsNode => this._deStreamWallets.First;
+        
+        public string DeStreamWallet => this.DeStreamWalletsNode.NextOrFirst().Value;
+
+        public bool IsDeStreamAddress(string address)
+        {
+            return this._deStreamWallets.Contains(address);
+        }
 
         /// <summary>
         /// 

Sources/NBitcoin/Utils/CircularLinkedList.cs

+using System.Collections.Generic;
+
+namespace NBitcoin
+{
+    internal static class CircularLinkedList
+    {
+        public static LinkedListNode<T> NextOrFirst<T>(this LinkedListNode<T> current)
+        {
+            if (current?.List != null) return current.Next ?? current.List.First;
+            return null;
+        }
+
+        public static LinkedListNode<T> PreviousOrLast<T>(this LinkedListNode<T> current)
+        {
+            if (current?.List != null) return current.Previous ?? current.List.Last;
+            return null;
+        }
+    }
+}
\ No newline at end of file

Sources/Stratis.Bitcoin.Features.Consensus/Rules/CommonRules/DeStreamBlockFeeRule.cs

@@ -37,9 +37,8 @@ namespace Stratis.Bitcoin.Features.Consensus.Rules.CommonRules
         private long GetActualFee(Block block)
         {
             IList<TxOut> outputsToFeeWallet = block.Transactions[BlockStake.IsProofOfStake(block) ? 1 : 0].Outputs
-                .Where(p =>
-                    this.Parent.Network.DeStreamWallets.Any(q =>
-                        q == p.ScriptPubKey.GetDestinationAddress(this.Parent.Network)?.ToString())).ToList();
+                .Where(p => this.Parent.Network.IsDeStreamAddress(p.ScriptPubKey
+                    .GetDestinationAddress(this.Parent.Network)?.ToString())).ToList();
 
             if (outputsToFeeWallet.Count() != 1)
                 throw new Exception();

Sources/Stratis.Bitcoin.Features.Miner/DeStreamPosMinting.cs

@@ -44,7 +44,7 @@ namespace Stratis.Bitcoin.Features.Miner
                 return;
 
             Script deStreamAddressKey = new KeyId(new uint160(Encoders.Base58Check
-                .DecodeData(this.network.DeStreamWallets.First())
+                .DecodeData(this.network.DeStreamWallet)
                 .Skip(this.network.Base58Prefixes[(int) Base58Type.PUBKEY_ADDRESS].Length).ToArray())).ScriptPubKey;
 
             context.CoinstakeContext.CoinstakeTx.AddOutput(new TxOut(Money.Zero, deStreamAddressKey));

Sources/Stratis.Bitcoin.Features.Miner/DeStreamPosPowBlockDefinition.cs

@@ -81,7 +81,7 @@ namespace Stratis.Bitcoin.Features.Miner
             base.CreateCoinbase();
 
             Script deStreamAddressKey = new KeyId(new uint160(Encoders.Base58Check
-                .DecodeData(this.Network.DeStreamWallets.First())
+                .DecodeData(this.Network.DeStreamWallet)
                 .Skip(this.Network.Base58Prefixes[(int) Base58Type.PUBKEY_ADDRESS].Length).ToArray())).ScriptPubKey;
             this.coinbase.AddOutput(new TxOut(Money.Zero, deStreamAddressKey));
         }

Sources/Stratis.Bitcoin.Features.Miner/DeStreamPowBlockDefinition.cs

@@ -81,7 +81,7 @@ namespace Stratis.Bitcoin.Features.Miner
             base.CreateCoinbase();
 
             Script deStreamAddressKey = new KeyId(new uint160(Encoders.Base58Check
-                .DecodeData(this.Network.DeStreamWallets.First())
+                .DecodeData(this.Network.DeStreamWallet)
                 .Skip(this.Network.Base58Prefixes[(int) Base58Type.PUBKEY_ADDRESS].Length).ToArray())).ScriptPubKey;
             this.coinbase.AddOutput(new TxOut(Money.Zero, deStreamAddressKey));
         }