Merge pull request dogecoin#3576 from patricklodder/bugfix/maskpow

validation: avoid masking of difficulty adjustment errors

src/validation.cpp

@@ -2998,20 +2998,6 @@ bool CheckBlock(const CBlock& block, CValidationState& state, bool fCheckPOW, bo
     return true;
 }
 
-static bool CheckIndexAgainstCheckpoint(const CBlockIndex* pindexPrev, CValidationState& state, const CChainParams& chainparams, const uint256& hash)
-{
-    if (*pindexPrev->phashBlock == chainparams.GetConsensus(0).hashGenesisBlock)
-        return true;
-
-    int nHeight = pindexPrev->nHeight+1;
-    // Don't accept any forks from the main chain prior to last checkpoint
-    CBlockIndex* pcheckpoint = Checkpoints::GetLastCheckpoint(chainparams.Checkpoints());
-    if (pcheckpoint && nHeight < pcheckpoint->nHeight)
-        return state.DoS(100, error("%s: forked chain older than last checkpoint (height %d)", __func__, nHeight));
-
-    return true;
-}
-
 bool IsWitnessEnabled(const CBlockIndex* pindexPrev, const Consensus::Params& params)
 {
     // Dogecoin: Disable SegWit
@@ -3079,7 +3065,8 @@ std::vector<unsigned char> GenerateCoinbaseCommitment(CBlock& block, const CBloc
 bool ContextualCheckBlockHeader(const CBlockHeader& block, CValidationState& state, const CBlockIndex* pindexPrev, int64_t nAdjustedTime)
 {
     const int nHeight = pindexPrev == NULL ? 0 : pindexPrev->nHeight + 1;
-    const Consensus::Params& consensusParams = Params().GetConsensus(nHeight);
+    const CChainParams& params = Params();
+    const Consensus::Params& consensusParams = params.GetConsensus(nHeight);
 
     // Disallow legacy blocks after merge-mining start.
     if (!consensusParams.fAllowLegacyBlocks
@@ -3101,6 +3088,16 @@ bool ContextualCheckBlockHeader(const CBlockHeader& block, CValidationState& sta
     if (block.nBits != GetNextWorkRequired(pindexPrev, &block, consensusParams))
         return state.DoS(100, false, REJECT_INVALID, "bad-diffbits", false, "incorrect proof of work");
 
+    // Check against checkpoints
+    if (fCheckpointsEnabled) {
+        // Don't accept any forks from the main chain prior to last checkpoint.
+        // GetLastCheckpoint finds the last checkpoint in MapCheckpoints that's in our
+        // MapBlockIndex.
+        CBlockIndex* pcheckpoint = Checkpoints::GetLastCheckpoint(params.Checkpoints());
+        if (pcheckpoint && nHeight < pcheckpoint->nHeight)
+            return state.DoS(100, error("%s: forked chain older than last checkpoint (height %d)", __func__, nHeight), REJECT_CHECKPOINT, "bad-fork-prior-to-checkpoint");
+    }
+
     // Check timestamp against prev
     if (block.GetBlockTime() <= pindexPrev->GetMedianTimePast())
         return state.Invalid(false, REJECT_INVALID, "time-too-old", "block's timestamp is too early");
@@ -3236,8 +3233,6 @@ static bool AcceptBlockHeader(const CBlockHeader& block, CValidationState& state
             return state.DoS(100, error("%s: prev block invalid", __func__), REJECT_INVALID, "bad-prevblk");
 
         assert(pindexPrev);
-        if (fCheckpointsEnabled && !CheckIndexAgainstCheckpoint(pindexPrev, state, chainparams, hash))
-            return error("%s: CheckIndexAgainstCheckpoint(): %s", __func__, state.GetRejectReason().c_str());
 
         if (!ContextualCheckBlockHeader(block, state, pindexPrev, GetAdjustedTime()))
             return error("%s: Consensus::ContextualCheckBlockHeader: %s, %s", __func__, hash.ToString(), FormatStateMessage(state));
@@ -3417,9 +3412,6 @@ bool TestBlockValidity(CValidationState& state, const CChainParams& chainparams,
 {
     AssertLockHeld(cs_main);
     assert(pindexPrev && pindexPrev == chainActive.Tip());
-    if (fCheckpointsEnabled && !CheckIndexAgainstCheckpoint(pindexPrev, state, chainparams, block.GetHash()))
-        return error("%s: CheckIndexAgainstCheckpoint(): %s", __func__, state.GetRejectReason().c_str());
-
     CCoinsViewCache viewNew(pcoinsTip);
     CBlockIndex indexDummy(block);
     indexDummy.pprev = pindexPrev;