1 files changed, 140 insertions, 0 deletions
diff --git a/src/validation.h b/src/validation.h
index 3cd64bc391..8114d42d37 100644
--- a/src/validation.h
+++ b/src/validation.h
@@ -44,6 +44,7 @@ class CTxMemPool;
 class CValidationState;
 struct ChainTxData;
 
+struct DisconnectedBlockTransactions;
 struct PrecomputedTransactionData;
 struct LockPoints;
 
@@ -422,6 +423,145 @@ inline CBlockIndex* LookupBlockIndex(const uint256& hash)
 /** Find the last common block between the parameter chain and a locator. */
 CBlockIndex* FindForkInGlobalIndex(const CChain& chain, const CBlockLocator& locator) EXCLUSIVE_LOCKS_REQUIRED(cs_main);
 
+enum DisconnectResult
+{
+    DISCONNECT_OK,      // All good.
+    DISCONNECT_UNCLEAN, // Rolled back, but UTXO set was inconsistent with block.
+    DISCONNECT_FAILED   // Something else went wrong.
+};
+
+class ConnectTrace;
+
+struct CBlockIndexWorkComparator
+{
+    bool operator()(const CBlockIndex *pa, const CBlockIndex *pb) const;
+};
+
+/**
+ * CChainState stores and provides an API to update our local knowledge of the
+ * current best chain and header tree.
+ *
+ * It generally provides access to the current block tree, as well as functions
+ * to provide new data, which it will appropriately validate and incorporate in
+ * its state as necessary.
+ *
+ * Eventually, the API here is targeted at being exposed externally as a
+ * consumable libconsensus library, so any functions added must only call
+ * other class member functions, pure functions in other parts of the consensus
+ * library, callbacks via the validation interface, or read/write-to-disk
+ * functions (eventually this will also be via callbacks).
+ */
+class CChainState {
+private:
+    /**
+     * The set of all CBlockIndex entries with BLOCK_VALID_TRANSACTIONS (for itself and all ancestors) and
+     * as good as our current tip or better. Entries may be failed, though, and pruning nodes may be
+     * missing the data for the block.
+     */
+    std::set<CBlockIndex*, CBlockIndexWorkComparator> setBlockIndexCandidates;
+
+    /**
+     * Every received block is assigned a unique and increasing identifier, so we
+     * know which one to give priority in case of a fork.
+     */
+    CCriticalSection cs_nBlockSequenceId;
+    /** Blocks loaded from disk are assigned id 0, so start the counter at 1. */
+    int32_t nBlockSequenceId = 1;
+    /** Decreasing counter (used by subsequent preciousblock calls). */
+    int32_t nBlockReverseSequenceId = -1;
+    /** chainwork for the last block that preciousblock has been applied to. */
+    arith_uint256 nLastPreciousChainwork = 0;
+
+    /** In order to efficiently track invalidity of headers, we keep the set of
+      * blocks which we tried to connect and found to be invalid here (ie which
+      * were set to BLOCK_FAILED_VALID since the last restart). We can then
+      * walk this set and check if a new header is a descendant of something in
+      * this set, preventing us from having to walk mapBlockIndex when we try
+      * to connect a bad block and fail.
+      *
+      * While this is more complicated than marking everything which descends
+      * from an invalid block as invalid at the time we discover it to be
+      * invalid, doing so would require walking all of mapBlockIndex to find all
+      * descendants. Since this case should be very rare, keeping track of all
+      * BLOCK_FAILED_VALID blocks in a set should be just fine and work just as
+      * well.
+      *
+      * Because we already walk mapBlockIndex in height-order at startup, we go
+      * ahead and mark descendants of invalid blocks as FAILED_CHILD at that time,
+      * instead of putting things in this set.
+      */
+    std::set<CBlockIndex*> m_failed_blocks;
+
+    /**
+     * the ChainState CriticalSection
+     * A lock that must be held when modifying this ChainState - held in ActivateBestChain()
+     */
+    CCriticalSection m_cs_chainstate;
+
+public:
+    //! The current chain of blockheaders we consult and build on.
+    //! @see CChain, CBlockIndex.
+    CChain m_chain;
+    BlockMap mapBlockIndex GUARDED_BY(cs_main);
+    std::multimap<CBlockIndex*, CBlockIndex*> mapBlocksUnlinked;
+    CBlockIndex *pindexBestInvalid = nullptr;
+
+    bool LoadBlockIndex(const Consensus::Params& consensus_params, CBlockTreeDB& blocktree) EXCLUSIVE_LOCKS_REQUIRED(cs_main);
+
+    bool ActivateBestChain(CValidationState &state, const CChainParams& chainparams, std::shared_ptr<const CBlock> pblock) LOCKS_EXCLUDED(cs_main);
+
+    /**
+     * If a block header hasn't already been seen, call CheckBlockHeader on it, ensure
+     * that it doesn't descend from an invalid block, and then add it to mapBlockIndex.
+     */
+    bool AcceptBlockHeader(const CBlockHeader& block, CValidationState& state, const CChainParams& chainparams, CBlockIndex** ppindex) EXCLUSIVE_LOCKS_REQUIRED(cs_main);
+    bool AcceptBlock(const std::shared_ptr<const CBlock>& pblock, CValidationState& state, const CChainParams& chainparams, CBlockIndex** ppindex, bool fRequested, const FlatFilePos* dbp, bool* fNewBlock) EXCLUSIVE_LOCKS_REQUIRED(cs_main);
+
+    // Block (dis)connection on a given view:
+    DisconnectResult DisconnectBlock(const CBlock& block, const CBlockIndex* pindex, CCoinsViewCache& view);
+    bool ConnectBlock(const CBlock& block, CValidationState& state, CBlockIndex* pindex,
+                      CCoinsViewCache& view, const CChainParams& chainparams, bool fJustCheck = false) EXCLUSIVE_LOCKS_REQUIRED(cs_main);
+
+    // Block disconnection on our pcoinsTip:
+    bool DisconnectTip(CValidationState& state, const CChainParams& chainparams, DisconnectedBlockTransactions* disconnectpool) EXCLUSIVE_LOCKS_REQUIRED(cs_main);
+
+    // Manual block validity manipulation:
+    bool PreciousBlock(CValidationState& state, const CChainParams& params, CBlockIndex* pindex) LOCKS_EXCLUDED(cs_main);
+    bool InvalidateBlock(CValidationState& state, const CChainParams& chainparams, CBlockIndex* pindex) LOCKS_EXCLUDED(cs_main);
+    void ResetBlockFailureFlags(CBlockIndex* pindex) EXCLUSIVE_LOCKS_REQUIRED(cs_main);
+
+    bool ReplayBlocks(const CChainParams& params, CCoinsView* view);
+    bool RewindBlockIndex(const CChainParams& params) LOCKS_EXCLUDED(cs_main);
+    bool LoadGenesisBlock(const CChainParams& chainparams);
+
+    void PruneBlockIndexCandidates();
+
+    void UnloadBlockIndex();
+
+private:
+    bool ActivateBestChainStep(CValidationState& state, const CChainParams& chainparams, CBlockIndex* pindexMostWork, const std::shared_ptr<const CBlock>& pblock, bool& fInvalidFound, ConnectTrace& connectTrace) EXCLUSIVE_LOCKS_REQUIRED(cs_main);
+    bool ConnectTip(CValidationState& state, const CChainParams& chainparams, CBlockIndex* pindexNew, const std::shared_ptr<const CBlock>& pblock, ConnectTrace& connectTrace, DisconnectedBlockTransactions &disconnectpool) EXCLUSIVE_LOCKS_REQUIRED(cs_main);
+
+    CBlockIndex* AddToBlockIndex(const CBlockHeader& block) EXCLUSIVE_LOCKS_REQUIRED(cs_main);
+    /** Create a new block index entry for a given block hash */
+    CBlockIndex* InsertBlockIndex(const uint256& hash) EXCLUSIVE_LOCKS_REQUIRED(cs_main);
+    /**
+     * Make various assertions about the state of the block index.
+     *
+     * By default this only executes fully when using the Regtest chain; see: fCheckBlockIndex.
+     */
+    void CheckBlockIndex(const Consensus::Params& consensusParams);
+
+    void InvalidBlockFound(CBlockIndex *pindex, const CValidationState &state) EXCLUSIVE_LOCKS_REQUIRED(cs_main);
+    CBlockIndex* FindMostWorkChain() EXCLUSIVE_LOCKS_REQUIRED(cs_main);
+    void ReceivedBlockTransactions(const CBlock& block, CBlockIndex* pindexNew, const FlatFilePos& pos, const Consensus::Params& consensusParams) EXCLUSIVE_LOCKS_REQUIRED(cs_main);
+
+    bool RollforwardBlock(const CBlockIndex* pindex, CCoinsViewCache& inputs, const CChainParams& params) EXCLUSIVE_LOCKS_REQUIRED(cs_main);
+
+    //! Mark a block as not having block data
+    void EraseBlockData(CBlockIndex* index) EXCLUSIVE_LOCKS_REQUIRED(cs_main);
+};
+
 /** Mark a block as precious and reorganize.
  *
  * May not be called in a