X-Git-Url: https://git.novaco.in/?a=blobdiff_plain;f=Novacoin%2FCBlock.cs;h=e8f220799ab111a28ca5a76f5137046dc0cb9a92;hb=624ac1021490395614a0cbee619c79860c22061a;hp=6ff2da3ffdf4c95c45ab3f2e960dac1218607d7f;hpb=f1d2e217ae6e24a84edfa98ca3471a8a836ecaa7;p=NovacoinLibrary.git

diff --git a/Novacoin/CBlock.cs b/Novacoin/CBlock.cs
index 6ff2da3..e8f2207 100644
--- a/Novacoin/CBlock.cs
+++ b/Novacoin/CBlock.cs
@@ -20,22 +20,24 @@ using System;
 using System.Text;
 using System.Collections.Generic;
 using System.Diagnostics.Contracts;
+using System.IO;
+using System.Numerics;
 
 namespace Novacoin
 {
     [Serializable]
-    public class BlockConstructorException : Exception
+    public class BlockException : Exception
     {
-        public BlockConstructorException()
+        public BlockException()
         {
         }
 
-        public BlockConstructorException(string message)
+        public BlockException(string message)
                 : base(message)
         {
         }
 
-        public BlockConstructorException(string message, Exception inner)
+        public BlockException(string message, Exception inner)
                 : base(message, inner)
         {
         }
@@ -46,6 +48,16 @@ namespace Novacoin
     /// </summary>
     public class CBlock
 	{
+        /// <summary>
+        /// Maximum block size is 1Mb.
+        /// </summary>
+        public const uint nMaxBlockSize = 1000000;
+
+        /// <summary>
+        /// Sanity threshold for amount of sigops.
+        /// </summary>
+        public const uint nMaxSigOps = 20000;
+
 		/// <summary>
 		/// Block header.
 		/// </summary>
@@ -75,6 +87,7 @@ namespace Novacoin
                 vtx[i] = new CTransaction(b.vtx[i]);
             }
 
+            signature = new byte[b.signature.Length];
             b.signature.CopyTo(signature, 0);
         }
 
@@ -86,20 +99,23 @@ namespace Novacoin
 		{
             try
             {
-                ByteQueue wBytes = new ByteQueue(blockBytes);
+                var stream = new MemoryStream(blockBytes);
+                var reader = new BinaryReader(stream);
 
                 // Fill the block header fields
-                header = new CBlockHeader(wBytes.Get(80));
+                header = new CBlockHeader(ref reader);               
 
                 // Parse transactions list
-                vtx = CTransaction.ReadTransactionsList(ref wBytes);
+                vtx = CTransaction.ReadTransactionsList(ref reader);
 
                 // Read block signature
-                signature = wBytes.Get((int)wBytes.GetVarInt());
+                signature = reader.ReadBytes((int)VarInt.ReadVarInt(ref reader));
+
+                reader.Close();
             }
             catch (Exception e)
             {
-                throw new BlockConstructorException("Deserialization failed", e);
+                throw new BlockException("Deserialization failed", e);
             }
 		}
 
@@ -111,6 +127,171 @@ namespace Novacoin
             vtx = new CTransaction[0];
         }
 
+        public bool CheckBlock(bool fCheckPOW = true, bool fCheckMerkleRoot = true, bool fCheckSig = true)
+        {
+            var uniqueTX = new List<uint256>(); // tx hashes
+            uint nSigOps = 0; // total sigops
+
+            // Basic sanity checkings
+            if (vtx.Length == 0 || Size > nMaxBlockSize)
+            {
+                return false;
+            }
+
+            bool fProofOfStake = IsProofOfStake;
+
+            // First transaction must be coinbase, the rest must not be
+            if (!vtx[0].IsCoinBase)
+            {
+                return false;
+            }
+
+            if (!vtx[0].CheckTransaction())
+            {
+                return false;
+            }
+
+            uniqueTX.Add(vtx[0].Hash);
+            nSigOps += vtx[0].LegacySigOpCount;
+
+            if (fProofOfStake)
+            {
+                // Proof-of-STake related checkings. Note that we know here that 1st transactions is coinstake. We don't need 
+                //   check the type of 1st transaction because it's performed earlier by IsProofOfStake()
+
+                // nNonce must be zero for proof-of-stake blocks
+                if (header.nNonce != 0)
+                {
+                    return false;
+                }
+
+                // Coinbase output should be empty if proof-of-stake block
+                if (vtx[0].vout.Length != 1 || !vtx[0].vout[0].IsEmpty)
+                {
+                    return false;
+                }
+
+                // Check coinstake timestamp
+                if (header.nTime != vtx[1].nTime)
+                {
+                    return false;
+                }
+
+                // Check proof-of-stake block signature
+                if (fCheckSig && !SignatureOK)
+                {
+                    return false;
+                }
+
+                if (!vtx[1].CheckTransaction())
+                {
+                    return false;
+                }
+
+                uniqueTX.Add(vtx[1].Hash);
+                nSigOps += vtx[1].LegacySigOpCount;
+            }
+            else
+            {
+                // Check proof of work matches claimed amount
+                if (fCheckPOW && !CheckProofOfWork(header.Hash, header.nBits))
+                {
+                    return false;
+                }
+
+                // Check timestamp
+                if (header.nTime > NetInfo.FutureDrift(NetInfo.GetAdjustedTime()))
+                {
+                    return false;
+                }
+
+                // Check coinbase timestamp
+                if (header.nTime < NetInfo.PastDrift(vtx[0].nTime))
+                {
+                    return false;
+                }
+            }
+
+            // Iterate all transactions starting from second for proof-of-stake block 
+            //    or first for proof-of-work block
+            for (int i = fProofOfStake ? 2 : 1; i < vtx.Length; i++)
+            {
+                var tx = vtx[i];
+
+                // Reject coinbase transactions at non-zero index
+                if (tx.IsCoinBase)
+                {
+                    return false;
+                }
+
+                // Reject coinstake transactions at index != 1
+                if (tx.IsCoinStake)
+                {
+                    return false;
+                }
+
+                // Check transaction timestamp
+                if (header.nTime < tx.nTime)
+                {
+                    return false;
+                }
+
+                // Check transaction consistency
+                if (!tx.CheckTransaction())
+                {
+                    return false;
+                }
+
+                // Add transaction hash into list of unique transaction IDs
+                uniqueTX.Add(tx.Hash);
+
+                // Calculate sigops count
+                nSigOps += tx.LegacySigOpCount;
+            }
+
+            // Check for duplicate txids. 
+            if (uniqueTX.Count != vtx.Length)
+            {
+                return false;
+            }
+
+            // Reject block if validation would consume too much resources.
+            if (nSigOps > nMaxSigOps)
+            {
+                return false;
+            }
+
+            // Check merkle root
+            if (fCheckMerkleRoot && hashMerkleRoot != header.merkleRoot)
+            {
+                return false;
+            }
+
+            return true;
+        }
+
+        private bool CheckProofOfWork(uint256 hash, uint nBits)
+        {
+            uint256 nTarget = new uint256();
+            nTarget.Compact = nBits;
+
+            // Check range
+            if (nTarget > NetInfo.nProofOfWorkLimit)
+            {
+                // nBits below minimum work
+                return false; 
+            }
+
+            // Check proof of work matches claimed amount
+            if (hash > nTarget)
+            {
+                //  hash doesn't match nBits
+                return false;
+            }
+
+            return true;
+        }
+
         /// <summary>
         /// Is this a Proof-of-Stake block?
         /// </summary>
@@ -177,20 +358,25 @@ namespace Novacoin
         /// <returns>Byte sequence</returns>
         public static implicit operator byte[] (CBlock b)
         {
-            var r = new List<byte>();
+            var stream = new MemoryStream();
+            var writer = new BinaryWriter(stream);
 
-            r.AddRange((byte[])b.header);
-            r.AddRange(VarInt.EncodeVarInt(b.vtx.LongLength)); // transactions count
+            writer.Write(b.header);
+            writer.Write(VarInt.EncodeVarInt(b.vtx.LongLength));
 
             foreach (var tx in b.vtx)
             {
-                r.AddRange((byte[])tx);
+                writer.Write(tx);
             }
 
-            r.AddRange(VarInt.EncodeVarInt(b.signature.LongLength));
-            r.AddRange(b.signature);
+            writer.Write(VarInt.EncodeVarInt(b.signature.LongLength));
+            writer.Write(b.signature);
+
+            var resultBytes = stream.ToArray();
+
+            writer.Close();
 
-            return r.ToArray();
+            return resultBytes;
         }
 
         /// <summary>
@@ -235,7 +421,7 @@ namespace Novacoin
         /// <summary>
         /// Merkle root
         /// </summary>
-        public Hash256 hashMerkleRoot
+        public uint256 hashMerkleRoot
         {
             get {
                 
@@ -243,7 +429,7 @@ namespace Novacoin
 
                 foreach (var tx in vtx)
                 {
-                    merkleTree.AddRange(Hash256.ComputeRaw256(tx));
+                    merkleTree.AddRange(CryptoUtils.ComputeHash256(tx));
                 }
 
                 int levelOffset = 0;
@@ -256,12 +442,12 @@ namespace Novacoin
                         var left = merkleTree.GetRange((levelOffset + nLeft) * 32, 32).ToArray();
                         var right = merkleTree.GetRange((levelOffset + nRight) * 32, 32).ToArray();
 
-                        merkleTree.AddRange(Hash256.ComputeRaw256(ref left, ref right));
+                        merkleTree.AddRange(CryptoUtils.ComputeHash256(ref left, ref right));
                     }
                     levelOffset += nLevelSize;
                 }
 
-                return (merkleTree.Count == 0) ? new Hash256() : new Hash256(merkleTree.GetRange(merkleTree.Count-32, 32).ToArray());
+                return (merkleTree.Count == 0) ? 0 : (uint256)merkleTree.GetRange(merkleTree.Count-32, 32).ToArray();
             }
         }
 
@@ -285,6 +471,51 @@ namespace Novacoin
             
             return sb.ToString();
         }
-	}
+
+        /// <summary>
+        /// Calculate proof-of-work reward.
+        /// </summary>
+        /// <param name="nBits">Packed difficulty representation.</param>
+        /// <param name="nFees">Amount of fees.</param>
+        /// <returns>Reward value.</returns>
+        public static ulong GetProofOfWorkReward(uint nBits, ulong nFees)
+        {
+            // NovaCoin: subsidy is cut in half every 64x multiply of PoW difficulty
+            // A reasonably continuous curve is used to avoid shock to market
+            // (nSubsidyLimit / nSubsidy) ** 6 == bnProofOfWorkLimit / bnTarget
+            //
+            // Human readable form:
+            //
+            // nSubsidy = 100 / (diff ^ 1/6)
+            //
+            // Please note that we're using bisection to find an approximate solutuion
+
+            BigInteger bnSubsidyLimit = NetInfo.nMaxMintProofOfWork;
+
+            uint256 nTarget = 0;
+            nTarget.Compact = nBits;
+
+            BigInteger bnTarget = new BigInteger(nTarget);
+            BigInteger bnTargetLimit = new BigInteger(NetInfo.nProofOfWorkLimit);
+
+            BigInteger bnLowerBound = CTransaction.nCent;
+            BigInteger bnUpperBound = bnSubsidyLimit;
+
+            while (bnLowerBound + CTransaction.nCent <= bnUpperBound)
+            {
+                BigInteger bnMidValue = (bnLowerBound + bnUpperBound) / 2;
+                if (bnMidValue * bnMidValue * bnMidValue * bnMidValue * bnMidValue * bnMidValue * bnTargetLimit > bnSubsidyLimit * bnSubsidyLimit * bnSubsidyLimit * bnSubsidyLimit * bnSubsidyLimit * bnSubsidyLimit * bnTarget)
+                    bnUpperBound = bnMidValue;
+                else
+                    bnLowerBound = bnMidValue;
+            }
+
+            ulong nSubsidy = (ulong)bnUpperBound;
+            nSubsidy = (nSubsidy / CTransaction.nCent) * CTransaction.nCent;
+
+
+            return Math.Min(nSubsidy, NetInfo.nMaxMintProofOfWork) + nFees;
+        }
+    }
 }