Abstract context-dependent block checking from acceptance

2 files changed, 75 insertions, 53 deletions

diff --git a/src/main.cpp b/src/main.cpp
index 82d52913a0..2781c6f3fb 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -2334,6 +2334,73 @@ bool CheckBlock(const CBlock& block, CValidationState& state, bool fCheckPOW, bo
     return true;
 }
 
+bool ContextualCheckBlockHeader(const CBlockHeader& block, CValidationState& state, CBlockIndex * const pindexPrev)
+{
+    uint256 hash = block.GetHash();
+    if (hash == Params().HashGenesisBlock())
+        return true;
+
+    assert(pindexPrev);
+
+    int nHeight = pindexPrev->nHeight+1;
+
+    // Check proof of work
+    if ((!Params().SkipProofOfWorkCheck()) &&
+       (block.nBits != GetNextWorkRequired(pindexPrev, &block)))
+        return state.DoS(100, error("%s : incorrect proof of work", __func__),
+                         REJECT_INVALID, "bad-diffbits");
+
+    // Check timestamp against prev
+    if (block.GetBlockTime() <= pindexPrev->GetMedianTimePast())
+        return state.Invalid(error("%s : block's timestamp is too early", __func__),
+                             REJECT_INVALID, "time-too-old");
+
+    // Check that the block chain matches the known block chain up to a checkpoint
+    if (!Checkpoints::CheckBlock(nHeight, hash))
+        return state.DoS(100, error("%s : rejected by checkpoint lock-in at %d", __func__, nHeight),
+                         REJECT_CHECKPOINT, "checkpoint mismatch");
+
+    // Don't accept any forks from the main chain prior to last checkpoint
+    CBlockIndex* pcheckpoint = Checkpoints::GetLastCheckpoint();
+    if (pcheckpoint && nHeight < pcheckpoint->nHeight)
+        return state.DoS(100, error("%s : forked chain older than last checkpoint (height %d)", __func__, nHeight));
+
+    // Reject block.nVersion=1 blocks when 95% (75% on testnet) of the network has upgraded:
+    if (block.nVersion < 2 && 
+        CBlockIndex::IsSuperMajority(2, pindexPrev, Params().RejectBlockOutdatedMajority()))
+    {
+        return state.Invalid(error("%s : rejected nVersion=1 block", __func__),
+                             REJECT_OBSOLETE, "bad-version");
+    }
+
+    return true;
+}
+
+bool ContextualCheckBlock(const CBlock& block, CValidationState& state, CBlockIndex * const pindexPrev)
+{
+    const int nHeight = pindexPrev == NULL ? 0 : pindexPrev->nHeight + 1;
+
+    // Check that all transactions are finalized
+    BOOST_FOREACH(const CTransaction& tx, block.vtx)
+        if (!IsFinalTx(tx, nHeight, block.GetBlockTime())) {
+            return state.DoS(10, error("%s : contains a non-final transaction", __func__), REJECT_INVALID, "bad-txns-nonfinal");
+        }
+
+    // Enforce block.nVersion=2 rule that the coinbase starts with serialized block height
+    // if 750 of the last 1,000 blocks are version 2 or greater (51/100 if testnet):
+    if (block.nVersion >= 2 && 
+        CBlockIndex::IsSuperMajority(2, pindexPrev, Params().EnforceBlockUpgradeMajority()))
+    {
+        CScript expect = CScript() << nHeight;
+        if (block.vtx[0].vin[0].scriptSig.size() < expect.size() ||
+            !std::equal(expect.begin(), expect.end(), block.vtx[0].vin[0].scriptSig.begin())) {
+            return state.DoS(100, error("%s : block height mismatch in coinbase", __func__), REJECT_INVALID, "bad-cb-height");
+        }
+    }
+
+    return true;
+}
+
 bool AcceptBlockHeader(const CBlockHeader& block, CValidationState& state, CBlockIndex** ppindex)
 {
     AssertLockHeld(cs_main);
@@ -2353,44 +2420,16 @@ bool AcceptBlockHeader(const CBlockHeader& block, CValidationState& state, CBloc
 
     // Get prev block index
     CBlockIndex* pindexPrev = NULL;
-    int nHeight = 0;
     if (hash != Params().HashGenesisBlock()) {
         BlockMap::iterator mi = mapBlockIndex.find(block.hashPrevBlock);
         if (mi == mapBlockIndex.end())
             return state.DoS(10, error("%s : prev block not found", __func__), 0, "bad-prevblk");
         pindexPrev = (*mi).second;
-        nHeight = pindexPrev->nHeight+1;
-
-        // Check proof of work
-        if ((!Params().SkipProofOfWorkCheck()) &&
-           (block.nBits != GetNextWorkRequired(pindexPrev, &block)))
-            return state.DoS(100, error("%s : incorrect proof of work", __func__),
-                             REJECT_INVALID, "bad-diffbits");
-
-        // Check timestamp against prev
-        if (block.GetBlockTime() <= pindexPrev->GetMedianTimePast())
-            return state.Invalid(error("%s : block's timestamp is too early", __func__),
-                                 REJECT_INVALID, "time-too-old");
-
-        // Check that the block chain matches the known block chain up to a checkpoint
-        if (!Checkpoints::CheckBlock(nHeight, hash))
-            return state.DoS(100, error("%s : rejected by checkpoint lock-in at %d", __func__, nHeight),
-                             REJECT_CHECKPOINT, "checkpoint mismatch");
-
-        // Don't accept any forks from the main chain prior to last checkpoint
-        CBlockIndex* pcheckpoint = Checkpoints::GetLastCheckpoint();
-        if (pcheckpoint && nHeight < pcheckpoint->nHeight)
-            return state.DoS(100, error("%s : forked chain older than last checkpoint (height %d)", __func__, nHeight));
-
-        // Reject block.nVersion=1 blocks when 95% (75% on testnet) of the network has upgraded:
-        if (block.nVersion < 2 && 
-            CBlockIndex::IsSuperMajority(2, pindexPrev, Params().RejectBlockOutdatedMajority()))
-        {
-            return state.Invalid(error("%s : rejected nVersion=1 block", __func__),
-                                 REJECT_OBSOLETE, "bad-version");
-        }
     }
 
+    if (!ContextualCheckBlockHeader(block, state, pindexPrev))
+        return false;
+
     if (pindex == NULL)
         pindex = AddToBlockIndex(block);
 
@@ -2415,7 +2454,7 @@ bool AcceptBlock(CBlock& block, CValidationState& state, CBlockIndex** ppindex,
         return true;
     }
 
-    if (!CheckBlock(block, state)) {
+    if ((!CheckBlock(block, state)) || !ContextualCheckBlock(block, state, pindex->pprev)) {
         if (state.IsInvalid() && !state.CorruptionPossible()) {
             pindex->nStatus |= BLOCK_FAILED_VALID;
         }
@@ -2424,27 +2463,6 @@ bool AcceptBlock(CBlock& block, CValidationState& state, CBlockIndex** ppindex,
 
     int nHeight = pindex->nHeight;
 
-    // Check that all transactions are finalized
-    BOOST_FOREACH(const CTransaction& tx, block.vtx)
-        if (!IsFinalTx(tx, nHeight, block.GetBlockTime())) {
-            pindex->nStatus |= BLOCK_FAILED_VALID;
-            return state.DoS(10, error("AcceptBlock() : contains a non-final transaction"),
-                             REJECT_INVALID, "bad-txns-nonfinal");
-        }
-
-    // Enforce block.nVersion=2 rule that the coinbase starts with serialized block height
-    // if 750 of the last 1,000 blocks are version 2 or greater (51/100 if testnet):
-    if (block.nVersion >= 2 && 
-        CBlockIndex::IsSuperMajority(2, pindex->pprev, Params().EnforceBlockUpgradeMajority()))
-    {
-        CScript expect = CScript() << nHeight;
-        if (block.vtx[0].vin[0].scriptSig.size() < expect.size() ||
-            !std::equal(expect.begin(), expect.end(), block.vtx[0].vin[0].scriptSig.begin())) {
-            pindex->nStatus |= BLOCK_FAILED_VALID;
-            return state.DoS(100, error("AcceptBlock() : block height mismatch in coinbase"), REJECT_INVALID, "bad-cb-height");
-        }
-    }
-
     // Write block to history file
     try {
         unsigned int nBlockSize = ::GetSerializeSize(block, SER_DISK, CLIENT_VERSION);
diff --git a/src/main.h b/src/main.h
index 1bb0919817..6e684be8c0 100644
--- a/src/main.h
+++ b/src/main.h
@@ -463,6 +463,10 @@ bool ConnectBlock(CBlock& block, CValidationState& state, CBlockIndex* pindex, C
 bool CheckBlockHeader(const CBlockHeader& block, CValidationState& state, bool fCheckPOW = true);
 bool CheckBlock(const CBlock& block, CValidationState& state, bool fCheckPOW = true, bool fCheckMerkleRoot = true);
 
+// Context-dependent validity checks
+bool ContextualCheckBlockHeader(const CBlockHeader& block, CValidationState& state, CBlockIndex *pindexPrev);
+bool ContextualCheckBlock(const CBlock& block, CValidationState& state, CBlockIndex *pindexPrev);
+
 // Store block on disk
 // if dbp is provided, the file is known to already reside on disk
 bool AcceptBlock(CBlock& block, CValidationState& state, CBlockIndex **pindex, CDiskBlockPos* dbp = NULL);