Add 'invalidateblock' and 'reconsiderblock' RPC commands.

These can be used for testing reorganizations or for manual intervention in case of
chain forks.

src/main.cpp

@@ -2135,6 +2135,79 @@ bool ActivateBestChain(CValidationState &state, CBlock *pblock) {
     return true;
 }
 
+bool InvalidateBlock(CValidationState& state, CBlockIndex *pindex) {
+    AssertLockHeld(cs_main);
+
+    // Mark the block itself as invalid.
+    pindex->nStatus |= BLOCK_FAILED_VALID;
+    if (!pblocktree->WriteBlockIndex(CDiskBlockIndex(pindex))) {
+        return state.Abort("Failed to update block index");
+    }
+    setBlockIndexCandidates.erase(pindex);
+
+    while (chainActive.Contains(pindex)) {
+        CBlockIndex *pindexWalk = chainActive.Tip();
+        pindexWalk->nStatus |= BLOCK_FAILED_CHILD;
+        if (!pblocktree->WriteBlockIndex(CDiskBlockIndex(pindexWalk))) {
+            return state.Abort("Failed to update block index");
+        }
+        setBlockIndexCandidates.erase(pindexWalk);
+        // ActivateBestChain considers blocks already in chainActive
+        // unconditionally valid already, so force disconnect away from it.
+        if (!DisconnectTip(state)) {
+            return false;
+        }
+    }
+
+    // The resulting new best tip may not be in setBlockIndexCandidates anymore, so
+    // add them again.
+    BlockMap::iterator it = mapBlockIndex.begin();
+    while (it != mapBlockIndex.end()) {
+        if (it->second->IsValid(BLOCK_VALID_TRANSACTIONS) && it->second->nChainTx && setBlockIndexCandidates.value_comp()(chainActive.Tip(), it->second)) {
+            setBlockIndexCandidates.insert(pindex);
+        }
+        it++;
+    }
+
+    InvalidChainFound(pindex);
+    return true;
+}
+
+bool ReconsiderBlock(CValidationState& state, CBlockIndex *pindex) {
+    AssertLockHeld(cs_main);
+
+    int nHeight = pindex->nHeight;
+
+    // Remove the invalidity flag from this block and all its descendants.
+    BlockMap::iterator it = mapBlockIndex.begin();
+    while (it != mapBlockIndex.end()) {
+        if (!it->second->IsValid() && it->second->GetAncestor(nHeight) == pindex) {
+            it->second->nStatus &= ~BLOCK_FAILED_MASK;
+            if (!pblocktree->WriteBlockIndex(CDiskBlockIndex(pindex))) {
+                return state.Abort("Failed to update block index");
+            }
+            if (it->second->IsValid(BLOCK_VALID_TRANSACTIONS) && it->second->nChainTx && setBlockIndexCandidates.value_comp()(chainActive.Tip(), it->second)) {
+                setBlockIndexCandidates.insert(it->second);
+            }
+            if (it->second == pindexBestInvalid) {
+                // Reset invalid block marker if it was pointing to one of those.
+                pindexBestInvalid = NULL;
+            }
+        }
+        it++;
+    }
+
+    // Remove the invalidity flag from all ancestors too.
+    while (pindex != NULL) {
+        pindex->nStatus &= ~BLOCK_FAILED_MASK;
+        if (!pblocktree->WriteBlockIndex(CDiskBlockIndex(pindex))) {
+            return state.Abort("Failed to update block index");
+        }
+        pindex = pindex->pprev;
+    }
+    return true;
+}
+
 CBlockIndex* AddToBlockIndex(const CBlockHeader& block)
 {
     // Check for duplicate

src/main.h

@@ -609,6 +609,12 @@ public:
 /** Find the last common block between the parameter chain and a locator. */
 CBlockIndex* FindForkInGlobalIndex(const CChain& chain, const CBlockLocator& locator);
 
+/** Mark a block as invalid. */
+bool InvalidateBlock(CValidationState& state, CBlockIndex *pindex);
+
+/** Remove invalidity status from a block and its descendants. */
+bool ReconsiderBlock(CValidationState& state, CBlockIndex *pindex);
+
 /** The currently-connected chain of blocks. */
 extern CChain chainActive;
 

src/rpcblockchain.cpp

@@ -561,3 +561,79 @@ Value getmempoolinfo(const Array& params, bool fHelp)
     return ret;
 }
 
+Value invalidateblock(const Array& params, bool fHelp)
+{
+    if (fHelp || params.size() != 1)
+        throw runtime_error(
+            "invalidateblock \"hash\"\n"
+            "\nPermanently marks a block as invalid, as if it violated a consensus rule.\n"
+            "\nArguments:\n"
+            "1. hash   (string, required) the hash of the block to mark as invalid\n"
+            "\nResult:\n"
+            "\nExamples:\n"
+            + HelpExampleCli("invalidateblock", "\"blockhash\"")
+            + HelpExampleRpc("invalidateblock", "\"blockhash\"")
+        );
+
+    std::string strHash = params[0].get_str();
+    uint256 hash(strHash);
+    CValidationState state;
+
+    {
+        LOCK(cs_main);
+        if (mapBlockIndex.count(hash) == 0)
+            throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "Block not found");
+
+        CBlockIndex* pblockindex = mapBlockIndex[hash];
+        InvalidateBlock(state, pblockindex);
+    }
+
+    if (state.IsValid()) {
+        ActivateBestChain(state);
+    }
+
+    if (!state.IsValid()) {
+        throw JSONRPCError(RPC_DATABASE_ERROR, state.GetRejectReason());
+    }
+
+    return Value::null;
+}
+
+Value reconsiderblock(const Array& params, bool fHelp)
+{
+    if (fHelp || params.size() != 1)
+        throw runtime_error(
+            "reconsiderblock \"hash\"\n"
+            "\nRemoves invalidity status of a block and its descendants, reconsider them for activation.\n"
+            "This can be used to undo the effects of invalidateblock.\n"
+            "\nArguments:\n"
+            "1. hash   (string, required) the hash of the block to reconsider\n"
+            "\nResult:\n"
+            "\nExamples:\n"
+            + HelpExampleCli("reconsiderblock", "\"blockhash\"")
+            + HelpExampleRpc("reconsiderblock", "\"blockhash\"")
+        );
+
+    std::string strHash = params[0].get_str();
+    uint256 hash(strHash);
+    CValidationState state;
+
+    {
+        LOCK(cs_main);
+        if (mapBlockIndex.count(hash) == 0)
+            throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "Block not found");
+
+        CBlockIndex* pblockindex = mapBlockIndex[hash];
+        ReconsiderBlock(state, pblockindex);
+    }
+
+    if (state.IsValid()) {
+        ActivateBestChain(state);
+    }
+
+    if (!state.IsValid()) {
+        throw JSONRPCError(RPC_DATABASE_ERROR, state.GetRejectReason());
+    }
+
+    return Value::null;
+}

src/rpcserver.cpp

@@ -270,6 +270,8 @@ static const CRPCCommand vRPCCommands[] =
     { "blockchain",         "gettxout",               &gettxout,               true,      false,      false },
     { "blockchain",         "gettxoutsetinfo",        &gettxoutsetinfo,        true,      false,      false },
     { "blockchain",         "verifychain",            &verifychain,            true,      false,      false },
+    { "blockchain",         "invalidateblock",        &invalidateblock,        true,      true,       false },
+    { "blockchain",         "reconsiderblock",        &reconsiderblock,        true,      true,       false },
 
     /* Mining */
     { "mining",             "getblocktemplate",       &getblocktemplate,       true,      false,      false },

src/rpcserver.h

@@ -222,6 +222,8 @@ extern json_spirit::Value gettxoutsetinfo(const json_spirit::Array& params, bool
 extern json_spirit::Value gettxout(const json_spirit::Array& params, bool fHelp);
 extern json_spirit::Value verifychain(const json_spirit::Array& params, bool fHelp);
 extern json_spirit::Value getchaintips(const json_spirit::Array& params, bool fHelp);
+extern json_spirit::Value invalidateblock(const json_spirit::Array& params, bool fHelp);
+extern json_spirit::Value reconsiderblock(const json_spirit::Array& params, bool fHelp);
 
 // in rest.cpp
 extern bool HTTPReq_REST(AcceptedConnection *conn,