CreateNewBlock: Check that the produced CBlock is acceptable (except for proof-of-work and merkletree, since those need to be provided later)

This throws an exception from CreateNewBlock otherwise, which is not safe without #1245!

src/main.cpp

@@ -1252,10 +1252,10 @@ bool CBlock::DisconnectBlock(CTxDB& txdb, CBlockIndex* pindex)
     return true;
 }
 
-bool CBlock::ConnectBlock(CTxDB& txdb, CBlockIndex* pindex)
+bool CBlock::ConnectBlock(CTxDB& txdb, CBlockIndex* pindex, bool fJustCheck)
 {
     // Check it again in case a previous version let a bad block in
-    if (!CheckBlock())
+    if (!CheckBlock(!fJustCheck, !fJustCheck))
         return false;
 
     // Do not allow blocks that contain transactions which 'overwrite' older transactions,
@@ -1283,7 +1283,13 @@ bool CBlock::ConnectBlock(CTxDB& txdb, CBlockIndex* pindex)
     bool fStrictPayToScriptHash = (pindex->nTime >= nBIP16SwitchTime);
 
     //// issue here: it doesn't know the version
-    unsigned int nTxPos = pindex->nBlockPos + ::GetSerializeSize(CBlock(), SER_DISK) - 1 + GetSizeOfCompactSize(vtx.size());
+    unsigned int nTxPos;
+    if (fJustCheck)
+        // FetchInputs treats CDiskTxPos(1,1,1) as a special "refer to memorypool" indicator
+        // Since we're just checking the block and not actually connecting it, it might not (and probably shouldn't) be on the disk to get the transaction from
+        nTxPos = 1;
+    else
+        nTxPos = pindex->nBlockPos + ::GetSerializeSize(CBlock(), SER_DISK) - 1 + GetSizeOfCompactSize(vtx.size());
 
     map<uint256, CTxIndex> mapQueuedChanges;
     int64 nFees = 0;
@@ -1295,6 +1301,7 @@ bool CBlock::ConnectBlock(CTxDB& txdb, CBlockIndex* pindex)
             return DoS(100, error("ConnectBlock() : too many sigops"));
 
         CDiskTxPos posThisTx(pindex->nFile, pindex->nBlockPos, nTxPos);
+        if (!fJustCheck)
             nTxPos += ::GetSerializeSize(tx, SER_DISK);
 
         MapPrevTx mapInputs;
@@ -1323,6 +1330,12 @@ bool CBlock::ConnectBlock(CTxDB& txdb, CBlockIndex* pindex)
         mapQueuedChanges[tx.GetHash()] = CTxIndex(posThisTx, tx.vout.size());
     }
 
+    if (vtx[0].GetValueOut() > GetBlockValue(pindex->nHeight, nFees))
+        return false;
+
+    if (fJustCheck)
+        return true;
+
     // Write queued txindex changes
     for (map<uint256, CTxIndex>::iterator mi = mapQueuedChanges.begin(); mi != mapQueuedChanges.end(); ++mi)
     {
@@ -1330,9 +1343,6 @@ bool CBlock::ConnectBlock(CTxDB& txdb, CBlockIndex* pindex)
             return error("ConnectBlock() : UpdateTxIndex failed");
     }
 
-    if (vtx[0].GetValueOut() > GetBlockValue(pindex->nHeight, nFees))
-        return false;
-
     // Update block index on disk without changing it in memory.
     // The memory index structure will be changed after the db commits.
     if (pindex->pprev)
@@ -1619,7 +1629,7 @@ bool CBlock::AddToBlockIndex(unsigned int nFile, unsigned int nBlockPos)
 
 
 
-bool CBlock::CheckBlock() const
+bool CBlock::CheckBlock(bool fCheckPOW, bool fCheckMerkleRoot) const
 {
     // These are checks that are independent of context
     // that can be verified before saving an orphan block.
@@ -1629,7 +1639,7 @@ bool CBlock::CheckBlock() const
         return DoS(100, error("CheckBlock() : size limits failed"));
 
     // Check proof of work matches claimed amount
-    if (!CheckProofOfWork(GetHash(), nBits))
+    if (fCheckPOW && !CheckProofOfWork(GetHash(), nBits))
         return DoS(50, error("CheckBlock() : proof of work failed"));
 
     // Check timestamp
@@ -1657,7 +1667,7 @@ bool CBlock::CheckBlock() const
         return DoS(100, error("CheckBlock() : out-of-bounds SigOpCount"));
 
     // Check merkleroot
-    if (hashMerkleRoot != BuildMerkleTree())
+    if (fCheckMerkleRoot && hashMerkleRoot != BuildMerkleTree())
         return DoS(100, error("CheckBlock() : hashMerkleRoot mismatch"));
 
     return true;
@@ -3066,6 +3076,9 @@ public:
 uint64 nLastBlockTx = 0;
 uint64 nLastBlockSize = 0;
 
+const char* pszDummy = "\0\0";
+CScript scriptDummy(std::vector<unsigned char>(pszDummy, pszDummy + sizeof(pszDummy)));
+
 CBlock* CreateNewBlock(CReserveKey& reservekey)
 {
     CBlockIndex* pindexPrev = pindexBest;
@@ -3224,16 +3237,22 @@ CBlock* CreateNewBlock(CReserveKey& reservekey)
         nLastBlockSize = nBlockSize;
         printf("CreateNewBlock(): total size %lu\n", nBlockSize);
 
-    }
     pblock->vtx[0].vout[0].nValue = GetBlockValue(pindexPrev->nHeight+1, nFees);
 
     // Fill in header
     pblock->hashPrevBlock  = pindexPrev->GetBlockHash();
-    pblock->hashMerkleRoot = pblock->BuildMerkleTree();
     pblock->UpdateTime(pindexPrev);
     pblock->nBits          = GetNextWorkRequired(pindexPrev, pblock.get());
     pblock->nNonce         = 0;
 
+        pblock->vtx[0].vin[0].scriptSig = scriptDummy;
+        CBlockIndex indexDummy(1, 1, *pblock);
+        indexDummy.pprev = pindexPrev;
+        indexDummy.nHeight = pindexPrev->nHeight + 1;
+        if (!pblock->ConnectBlock(txdb, &indexDummy, true))
+            throw std::runtime_error("CreateNewBlock() : ConnectBlock failed");
+    }
+
     return pblock.release();
 }
 

src/main.h

@@ -1017,11 +1017,11 @@ public:
 
 
     bool DisconnectBlock(CTxDB& txdb, CBlockIndex* pindex);
-    bool ConnectBlock(CTxDB& txdb, CBlockIndex* pindex);
+    bool ConnectBlock(CTxDB& txdb, CBlockIndex* pindex, bool fJustCheck=false);
     bool ReadFromDisk(const CBlockIndex* pindex, bool fReadTransactions=true);
     bool SetBestChain(CTxDB& txdb, CBlockIndex* pindexNew);
     bool AddToBlockIndex(unsigned int nFile, unsigned int nBlockPos);
-    bool CheckBlock() const;
+    bool CheckBlock(bool fCheckPOW=true, bool fCheckMerkleRoot=true) const;
     bool AcceptBlock();
 
 private: