From 425c3a87ff128bc068949b86e7f764c2c3e3f904 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Jorge=20Tim=C3=B3n?= <jtimon@jtimon.cc>
Date: Mon, 30 Mar 2015 13:48:04 +0200
Subject: [PATCH] Consensus: Separate CheckIndexAgainstCheckpoint() from
 ContextualCheckBlockHeader

---
 src/main.cpp | 35 +++++++++++++++++++----------------
 1 file changed, 19 insertions(+), 16 deletions(-)

diff --git a/src/main.cpp b/src/main.cpp
index b5dd2643d3..ab5649417c 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -2719,18 +2719,23 @@ bool CheckBlock(const CBlock& block, CValidationState& state, bool fCheckPOW, bo
     return true;
 }
 
-bool ContextualCheckBlockHeader(const CBlockHeader& block, CValidationState& state, CBlockIndex * const pindexPrev)
+static bool CheckIndexAgainstCheckpoint(const CBlockIndex* pindexPrev, CValidationState& state, const CChainParams& chainparams, const uint256& hash)
 {
-    const CChainParams& chainParams = Params();
-    const Consensus::Params& consensusParams = chainParams.GetConsensus();
-    uint256 hash = block.GetHash();
-    if (hash == consensusParams.hashGenesisBlock)
+    if (*pindexPrev->phashBlock == chainparams.GetConsensus().hashGenesisBlock)
         return true;
 
-    assert(pindexPrev);
-
     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 ContextualCheckBlockHeader(const CBlockHeader& block, CValidationState& state, CBlockIndex * const pindexPrev)
+{
+    const Consensus::Params& consensusParams = Params().GetConsensus();
     // Check proof of work
     if (block.nBits != GetNextWorkRequired(pindexPrev, &block, consensusParams))
         return state.DoS(100, error("%s: incorrect proof of work", __func__),
@@ -2741,14 +2746,6 @@ bool ContextualCheckBlockHeader(const CBlockHeader& block, CValidationState& sta
         return state.Invalid(error("%s: block's timestamp is too early", __func__),
                              REJECT_INVALID, "time-too-old");
 
-    if (fCheckpointsEnabled)
-    {
-        // 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));
-    }
-
     // Reject block.nVersion=1 blocks when 95% (75% on testnet) of the network has upgraded:
     if (block.nVersion < 2 && IsSuperMajority(2, pindexPrev, consensusParams.nMajorityRejectBlockOutdated, consensusParams))
         return state.Invalid(error("%s: rejected nVersion=1 block", __func__),
@@ -2818,6 +2815,9 @@ bool AcceptBlockHeader(const CBlockHeader& block, CValidationState& state, CBloc
         if (pindexPrev->nStatus & BLOCK_FAILED_MASK)
             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))
         return false;
@@ -2933,8 +2933,11 @@ bool ProcessNewBlock(CValidationState &state, CNode* pfrom, CBlock* pblock, bool
 
 bool TestBlockValidity(CValidationState &state, const CBlock& block, CBlockIndex * const pindexPrev, bool fCheckPOW, bool fCheckMerkleRoot)
 {
+    const CChainParams& chainparams = Params();
     AssertLockHeld(cs_main);
-    assert(pindexPrev == chainActive.Tip());
+    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);