Exemplo n.º 1
0
static UniValue getblocktemplate(const JSONRPCRequest& request)
{
    if (request.fHelp || request.params.size() > 1)
        throw std::runtime_error(
            "getblocktemplate ( TemplateRequest )\n"
            "\nIf the request parameters include a 'mode' key, that is used to explicitly select between the default 'template' request or a 'proposal'.\n"
            "It returns data needed to construct a block to work on.\n"
            "For full specification, see BIPs 22, 23, 9, and 145:\n"
            "    https://github.com/bitcoin/bips/blob/master/bip-0022.mediawiki\n"
            "    https://github.com/bitcoin/bips/blob/master/bip-0023.mediawiki\n"
            "    https://github.com/bitcoin/bips/blob/master/bip-0009.mediawiki#getblocktemplate_changes\n"
            "    https://github.com/bitcoin/bips/blob/master/bip-0145.mediawiki\n"

            "\nArguments:\n"
            "1. template_request         (json object, optional) A json object in the following spec\n"
            "     {\n"
            "       \"mode\":\"template\"    (string, optional) This must be set to \"template\", \"proposal\" (see BIP 23), or omitted\n"
            "       \"capabilities\":[     (array, optional) A list of strings\n"
            "           \"support\"          (string) client side supported feature, 'longpoll', 'coinbasetxn', 'coinbasevalue', 'proposal', 'serverlist', 'workid'\n"
            "           ,...\n"
            "       ],\n"
            "       \"rules\":[            (array, optional) A list of strings\n"
            "           \"support\"          (string) client side supported softfork deployment\n"
            "           ,...\n"
            "       ]\n"
            "     }\n"
            "\n"

            "\nResult:\n"
            "{\n"
            "  \"version\" : n,                    (numeric) The preferred block version\n"
            "  \"rules\" : [ \"rulename\", ... ],    (array of strings) specific block rules that are to be enforced\n"
            "  \"vbavailable\" : {                 (json object) set of pending, supported versionbit (BIP 9) softfork deployments\n"
            "      \"rulename\" : bitnumber          (numeric) identifies the bit number as indicating acceptance and readiness for the named softfork rule\n"
            "      ,...\n"
            "  },\n"
            "  \"vbrequired\" : n,                 (numeric) bit mask of versionbits the server requires set in submissions\n"
            "  \"previousblockhash\" : \"xxxx\",     (string) The hash of current highest block\n"
            "  \"transactions\" : [                (array) contents of non-coinbase transactions that should be included in the next block\n"
            "      {\n"
            "         \"data\" : \"xxxx\",             (string) transaction data encoded in hexadecimal (byte-for-byte)\n"
            "         \"txid\" : \"xxxx\",             (string) transaction id encoded in little-endian hexadecimal\n"
            "         \"hash\" : \"xxxx\",             (string) hash encoded in little-endian hexadecimal (including witness data)\n"
            "         \"depends\" : [                (array) array of numbers \n"
            "             n                          (numeric) transactions before this one (by 1-based index in 'transactions' list) that must be present in the final block if this one is\n"
            "             ,...\n"
            "         ],\n"
            "         \"fee\": n,                    (numeric) difference in value between transaction inputs and outputs (in satoshis); for coinbase transactions, this is a negative Number of the total collected block fees (ie, not including the block subsidy); if key is not present, fee is unknown and clients MUST NOT assume there isn't one\n"
            "         \"sigops\" : n,                (numeric) total SigOps cost, as counted for purposes of block limits; if key is not present, sigop cost is unknown and clients MUST NOT assume it is zero\n"
            "         \"weight\" : n,                (numeric) total transaction weight, as counted for purposes of block limits\n"
            "      }\n"
            "      ,...\n"
            "  ],\n"
            "  \"coinbaseaux\" : {                 (json object) data that should be included in the coinbase's scriptSig content\n"
            "      \"flags\" : \"xx\"                  (string) key name is to be ignored, and value included in scriptSig\n"
            "  },\n"
            "  \"coinbasevalue\" : n,              (numeric) maximum allowable input to coinbase transaction, including the generation award and transaction fees (in satoshis)\n"
            "  \"coinbasetxn\" : { ... },          (json object) information for coinbase transaction\n"
            "  \"target\" : \"xxxx\",                (string) The hash target\n"
            "  \"mintime\" : xxx,                  (numeric) The minimum timestamp appropriate for next block time in seconds since epoch (Jan 1 1970 GMT)\n"
            "  \"mutable\" : [                     (array of string) list of ways the block template may be changed \n"
            "     \"value\"                          (string) A way the block template may be changed, e.g. 'time', 'transactions', 'prevblock'\n"
            "     ,...\n"
            "  ],\n"
            "  \"noncerange\" : \"00000000ffffffff\",(string) A range of valid nonces\n"
            "  \"sigoplimit\" : n,                 (numeric) limit of sigops in blocks\n"
            "  \"sizelimit\" : n,                  (numeric) limit of block size\n"
            "  \"weightlimit\" : n,                (numeric) limit of block weight\n"
            "  \"curtime\" : ttt,                  (numeric) current timestamp in seconds since epoch (Jan 1 1970 GMT)\n"
            "  \"bits\" : \"xxxxxxxx\",              (string) compressed target of next block\n"
            "  \"height\" : n                      (numeric) The height of the next block\n"
            "}\n"

            "\nExamples:\n"
            + HelpExampleCli("getblocktemplate", "{\"rules\": [\"segwit\"]}")
            + HelpExampleRpc("getblocktemplate", "{\"rules\": [\"segwit\"]}")
         );

    LOCK(cs_main);

    std::string strMode = "template";
    UniValue lpval = NullUniValue;
    std::set<std::string> setClientRules;
    int64_t nMaxVersionPreVB = -1;
    if (!request.params[0].isNull())
    {
        const UniValue& oparam = request.params[0].get_obj();
        const UniValue& modeval = find_value(oparam, "mode");
        if (modeval.isStr())
            strMode = modeval.get_str();
        else if (modeval.isNull())
        {
            /* Do nothing */
        }
        else
            throw JSONRPCError(RPC_INVALID_PARAMETER, "Invalid mode");
        lpval = find_value(oparam, "longpollid");

        if (strMode == "proposal")
        {
            const UniValue& dataval = find_value(oparam, "data");
            if (!dataval.isStr())
                throw JSONRPCError(RPC_TYPE_ERROR, "Missing data String key for proposal");

            CBlock block;
            if (!DecodeHexBlk(block, dataval.get_str()))
                throw JSONRPCError(RPC_DESERIALIZATION_ERROR, "Block decode failed");

            uint256 hash = block.GetHash();
            const CBlockIndex* pindex = LookupBlockIndex(hash);
            if (pindex) {
                if (pindex->IsValid(BLOCK_VALID_SCRIPTS))
                    return "duplicate";
                if (pindex->nStatus & BLOCK_FAILED_MASK)
                    return "duplicate-invalid";
                return "duplicate-inconclusive";
            }

            CBlockIndex* const pindexPrev = chainActive.Tip();
            // TestBlockValidity only supports blocks built on the current Tip
            if (block.hashPrevBlock != pindexPrev->GetBlockHash())
                return "inconclusive-not-best-prevblk";
            CValidationState state;
            TestBlockValidity(state, Params(), block, pindexPrev, false, true);
            return BIP22ValidationResult(state);
        }

        const UniValue& aClientRules = find_value(oparam, "rules");
        if (aClientRules.isArray()) {
            for (unsigned int i = 0; i < aClientRules.size(); ++i) {
                const UniValue& v = aClientRules[i];
                setClientRules.insert(v.get_str());
            }
        } else {
            // NOTE: It is important that this NOT be read if versionbits is supported
            const UniValue& uvMaxVersion = find_value(oparam, "maxversion");
            if (uvMaxVersion.isNum()) {
                nMaxVersionPreVB = uvMaxVersion.get_int64();
            }
        }
    }

    if (strMode != "template")
        throw JSONRPCError(RPC_INVALID_PARAMETER, "Invalid mode");

    if(!g_connman)
        throw JSONRPCError(RPC_CLIENT_P2P_DISABLED, "Error: Peer-to-peer functionality missing or disabled");

    if (g_connman->GetNodeCount(CConnman::CONNECTIONS_ALL) == 0)
        throw JSONRPCError(RPC_CLIENT_NOT_CONNECTED, "Bitcoin is not connected!");

    if (IsInitialBlockDownload())
        throw JSONRPCError(RPC_CLIENT_IN_INITIAL_DOWNLOAD, "Bitcoin is downloading blocks...");

    static unsigned int nTransactionsUpdatedLast;

    if (!lpval.isNull())
    {
        // Wait to respond until either the best block changes, OR a minute has passed and there are more transactions
        uint256 hashWatchedChain;
        std::chrono::steady_clock::time_point checktxtime;
        unsigned int nTransactionsUpdatedLastLP;

        if (lpval.isStr())
        {
            // Format: <hashBestChain><nTransactionsUpdatedLast>
            std::string lpstr = lpval.get_str();

            hashWatchedChain = ParseHashV(lpstr.substr(0, 64), "longpollid");
            nTransactionsUpdatedLastLP = atoi64(lpstr.substr(64));
        }
        else
        {
            // NOTE: Spec does not specify behaviour for non-string longpollid, but this makes testing easier
            hashWatchedChain = chainActive.Tip()->GetBlockHash();
            nTransactionsUpdatedLastLP = nTransactionsUpdatedLast;
        }

        // Release the wallet and main lock while waiting
        LEAVE_CRITICAL_SECTION(cs_main);
        {
            checktxtime = std::chrono::steady_clock::now() + std::chrono::minutes(1);

            WAIT_LOCK(g_best_block_mutex, lock);
            while (g_best_block == hashWatchedChain && IsRPCRunning())
            {
                if (g_best_block_cv.wait_until(lock, checktxtime) == std::cv_status::timeout)
                {
                    // Timeout: Check transactions for update
                    if (mempool.GetTransactionsUpdated() != nTransactionsUpdatedLastLP)
                        break;
                    checktxtime += std::chrono::seconds(10);
                }
            }
        }
        ENTER_CRITICAL_SECTION(cs_main);

        if (!IsRPCRunning())
            throw JSONRPCError(RPC_CLIENT_NOT_CONNECTED, "Shutting down");
        // TODO: Maybe recheck connections/IBD and (if something wrong) send an expires-immediately template to stop miners?
    }

    const struct VBDeploymentInfo& segwit_info = VersionBitsDeploymentInfo[Consensus::DEPLOYMENT_SEGWIT];
    // If the caller is indicating segwit support, then allow CreateNewBlock()
    // to select witness transactions, after segwit activates (otherwise
    // don't).
    bool fSupportsSegwit = setClientRules.find(segwit_info.name) != setClientRules.end();

    // Update block
    static CBlockIndex* pindexPrev;
    static int64_t nStart;
    static std::unique_ptr<CBlockTemplate> pblocktemplate;
    // Cache whether the last invocation was with segwit support, to avoid returning
    // a segwit-block to a non-segwit caller.
    static bool fLastTemplateSupportsSegwit = true;
    if (pindexPrev != chainActive.Tip() ||
        (mempool.GetTransactionsUpdated() != nTransactionsUpdatedLast && GetTime() - nStart > 5) ||
        fLastTemplateSupportsSegwit != fSupportsSegwit)
    {
        // Clear pindexPrev so future calls make a new block, despite any failures from here on
        pindexPrev = nullptr;

        // Store the pindexBest used before CreateNewBlock, to avoid races
        nTransactionsUpdatedLast = mempool.GetTransactionsUpdated();
        CBlockIndex* pindexPrevNew = chainActive.Tip();
        nStart = GetTime();
        fLastTemplateSupportsSegwit = fSupportsSegwit;

        // Create new block
        CScript scriptDummy = CScript() << OP_TRUE;
        pblocktemplate = BlockAssembler(Params()).CreateNewBlock(scriptDummy, fSupportsSegwit);
        if (!pblocktemplate)
            throw JSONRPCError(RPC_OUT_OF_MEMORY, "Out of memory");

        // Need to update only after we know CreateNewBlock succeeded
        pindexPrev = pindexPrevNew;
    }
    assert(pindexPrev);
    CBlock* pblock = &pblocktemplate->block; // pointer for convenience
    const Consensus::Params& consensusParams = Params().GetConsensus();

    // Update nTime
    UpdateTime(pblock, consensusParams, pindexPrev);
    pblock->nNonce = 0;

    // NOTE: If at some point we support pre-segwit miners post-segwit-activation, this needs to take segwit support into consideration
    const bool fPreSegWit = (ThresholdState::ACTIVE != VersionBitsState(pindexPrev, consensusParams, Consensus::DEPLOYMENT_SEGWIT, versionbitscache));

    UniValue aCaps(UniValue::VARR); aCaps.push_back("proposal");

    UniValue transactions(UniValue::VARR);
    std::map<uint256, int64_t> setTxIndex;
    int i = 0;
    for (const auto& it : pblock->vtx) {
        const CTransaction& tx = *it;
        uint256 txHash = tx.GetHash();
        setTxIndex[txHash] = i++;

        if (tx.IsCoinBase())
            continue;

        UniValue entry(UniValue::VOBJ);

        entry.pushKV("data", EncodeHexTx(tx));
        entry.pushKV("txid", txHash.GetHex());
        entry.pushKV("hash", tx.GetWitnessHash().GetHex());

        UniValue deps(UniValue::VARR);
        for (const CTxIn &in : tx.vin)
        {
            if (setTxIndex.count(in.prevout.hash))
                deps.push_back(setTxIndex[in.prevout.hash]);
        }
        entry.pushKV("depends", deps);

        int index_in_template = i - 1;
        entry.pushKV("fee", pblocktemplate->vTxFees[index_in_template]);
        int64_t nTxSigOps = pblocktemplate->vTxSigOpsCost[index_in_template];
        if (fPreSegWit) {
            assert(nTxSigOps % WITNESS_SCALE_FACTOR == 0);
            nTxSigOps /= WITNESS_SCALE_FACTOR;
        }
        entry.pushKV("sigops", nTxSigOps);
        entry.pushKV("weight", GetTransactionWeight(tx));

        transactions.push_back(entry);
    }

    UniValue aux(UniValue::VOBJ);
    aux.pushKV("flags", HexStr(COINBASE_FLAGS.begin(), COINBASE_FLAGS.end()));

    arith_uint256 hashTarget = arith_uint256().SetCompact(pblock->nBits);

    UniValue aMutable(UniValue::VARR);
    aMutable.push_back("time");
    aMutable.push_back("transactions");
    aMutable.push_back("prevblock");

    UniValue result(UniValue::VOBJ);
    result.pushKV("capabilities", aCaps);

    UniValue aRules(UniValue::VARR);
    UniValue vbavailable(UniValue::VOBJ);
    for (int j = 0; j < (int)Consensus::MAX_VERSION_BITS_DEPLOYMENTS; ++j) {
        Consensus::DeploymentPos pos = Consensus::DeploymentPos(j);
        ThresholdState state = VersionBitsState(pindexPrev, consensusParams, pos, versionbitscache);
        switch (state) {
            case ThresholdState::DEFINED:
            case ThresholdState::FAILED:
                // Not exposed to GBT at all
                break;
            case ThresholdState::LOCKED_IN:
                // Ensure bit is set in block version
                pblock->nVersion |= VersionBitsMask(consensusParams, pos);
                // FALL THROUGH to get vbavailable set...
            case ThresholdState::STARTED:
            {
                const struct VBDeploymentInfo& vbinfo = VersionBitsDeploymentInfo[pos];
                vbavailable.pushKV(gbt_vb_name(pos), consensusParams.vDeployments[pos].bit);
                if (setClientRules.find(vbinfo.name) == setClientRules.end()) {
                    if (!vbinfo.gbt_force) {
                        // If the client doesn't support this, don't indicate it in the [default] version
                        pblock->nVersion &= ~VersionBitsMask(consensusParams, pos);
                    }
                }
                break;
            }
            case ThresholdState::ACTIVE:
            {
                // Add to rules only
                const struct VBDeploymentInfo& vbinfo = VersionBitsDeploymentInfo[pos];
                aRules.push_back(gbt_vb_name(pos));
                if (setClientRules.find(vbinfo.name) == setClientRules.end()) {
                    // Not supported by the client; make sure it's safe to proceed
                    if (!vbinfo.gbt_force) {
                        // If we do anything other than throw an exception here, be sure version/force isn't sent to old clients
                        throw JSONRPCError(RPC_INVALID_PARAMETER, strprintf("Support for '%s' rule requires explicit client support", vbinfo.name));
                    }
                }
                break;
            }
        }
    }
    result.pushKV("version", pblock->nVersion);
    result.pushKV("rules", aRules);
    result.pushKV("vbavailable", vbavailable);
    result.pushKV("vbrequired", int(0));

    if (nMaxVersionPreVB >= 2) {
        // If VB is supported by the client, nMaxVersionPreVB is -1, so we won't get here
        // Because BIP 34 changed how the generation transaction is serialized, we can only use version/force back to v2 blocks
        // This is safe to do [otherwise-]unconditionally only because we are throwing an exception above if a non-force deployment gets activated
        // Note that this can probably also be removed entirely after the first BIP9 non-force deployment (ie, probably segwit) gets activated
        aMutable.push_back("version/force");
    }

    result.pushKV("previousblockhash", pblock->hashPrevBlock.GetHex());
    result.pushKV("transactions", transactions);
    result.pushKV("coinbaseaux", aux);
    result.pushKV("coinbasevalue", (int64_t)pblock->vtx[0]->vout[0].nValue);
    result.pushKV("longpollid", chainActive.Tip()->GetBlockHash().GetHex() + i64tostr(nTransactionsUpdatedLast));
    result.pushKV("target", hashTarget.GetHex());
    result.pushKV("mintime", (int64_t)pindexPrev->GetMedianTimePast()+1);
    result.pushKV("mutable", aMutable);
    result.pushKV("noncerange", "00000000ffffffff");
    int64_t nSigOpLimit = MAX_BLOCK_SIGOPS_COST;
    int64_t nSizeLimit = MAX_BLOCK_SERIALIZED_SIZE;
    if (fPreSegWit) {
        assert(nSigOpLimit % WITNESS_SCALE_FACTOR == 0);
        nSigOpLimit /= WITNESS_SCALE_FACTOR;
        assert(nSizeLimit % WITNESS_SCALE_FACTOR == 0);
        nSizeLimit /= WITNESS_SCALE_FACTOR;
    }
    result.pushKV("sigoplimit", nSigOpLimit);
    result.pushKV("sizelimit", nSizeLimit);
    if (!fPreSegWit) {
        result.pushKV("weightlimit", (int64_t)MAX_BLOCK_WEIGHT);
    }
    result.pushKV("curtime", pblock->GetBlockTime());
    result.pushKV("bits", strprintf("%08x", pblock->nBits));
    result.pushKV("height", (int64_t)(pindexPrev->nHeight+1));

    if (!pblocktemplate->vchCoinbaseCommitment.empty() && fSupportsSegwit) {
        result.pushKV("default_witness_commitment", HexStr(pblocktemplate->vchCoinbaseCommitment.begin(), pblocktemplate->vchCoinbaseCommitment.end()));
    }

    return result;
}
Exemplo n.º 2
0
UniValue getblocktemplate(const JSONRPCRequest& request)
{
    if (request.fHelp || request.params.size() > 1)
        throw std::runtime_error(
            "getblocktemplate ( TemplateRequest )\n"
            "\nIf the request parameters include a 'mode' key, that is used to explicitly select between the default 'template' request or a 'proposal'.\n"
            "It returns data needed to construct a block to work on.\n"
            "For full specification, see BIPs 22, 23, and 9:\n"
            "    https://github.com/bitcoin/bips/blob/master/bip-0022.mediawiki\n"
            "    https://github.com/bitcoin/bips/blob/master/bip-0023.mediawiki\n"
            "    https://github.com/bitcoin/bips/blob/master/bip-0009.mediawiki#getblocktemplate_changes\n"

            "\nArguments:\n"
            "1. template_request         (json object, optional) A json object in the following spec\n"
            "     {\n"
            "       \"mode\":\"template\"    (string, optional) This must be set to \"template\", \"proposal\" (see BIP 23), or omitted\n"
            "       \"capabilities\":[     (array, optional) A list of strings\n"
            "           \"support\"          (string) client side supported feature, 'longpoll', 'coinbasetxn', 'coinbasevalue', 'proposal', 'serverlist', 'workid'\n"
            "           ,...\n"
            "       ],\n"
            "       \"rules\":[            (array, optional) A list of strings\n"
            "           \"support\"          (string) client side supported softfork deployment\n"
            "           ,...\n"
            "       ]\n"
            "     }\n"
            "\n"

            "\nResult:\n"
            "{\n"
            "  \"capabilities\" : [ \"capability\", ... ],    (array of strings) specific client side supported features\n"
            "  \"version\" : n,                    (numeric) The preferred block version\n"
            "  \"rules\" : [ \"rulename\", ... ],    (array of strings) specific block rules that are to be enforced\n"
            "  \"vbavailable\" : {                 (json object) set of pending, supported versionbit (BIP 9) softfork deployments\n"
            "      \"rulename\" : bitnumber          (numeric) identifies the bit number as indicating acceptance and readiness for the named softfork rule\n"
            "      ,...\n"
            "  },\n"
            "  \"vbrequired\" : n,                 (numeric) bit mask of versionbits the server requires set in submissions\n"
            "  \"previousblockhash\" : \"xxxx\",     (string) The hash of current highest block\n"
            "  \"transactions\" : [                (array) contents of non-coinbase transactions that should be included in the next block\n"
            "      {\n"
            "         \"data\" : \"xxxx\",             (string) transaction data encoded in hexadecimal (byte-for-byte)\n"
            "         \"hash\" : \"xxxx\",             (string) hash/id encoded in little-endian hexadecimal\n"
            "         \"depends\" : [                (array) array of numbers \n"
            "             n                          (numeric) transactions before this one (by 1-based index in 'transactions' list) that must be present in the final block if this one is\n"
            "             ,...\n"
            "         ],\n"
            "         \"fee\": n,                    (numeric) difference in value between transaction inputs and outputs (in duffs); for coinbase transactions, this is a negative Number of the total collected block fees (ie, not including the block subsidy); if key is not present, fee is unknown and clients MUST NOT assume there isn't one\n"
            "         \"sigops\" : n,                (numeric) total number of SigOps, as counted for purposes of block limits; if key is not present, sigop count is unknown and clients MUST NOT assume there aren't any\n"
            "         \"required\" : true|false      (boolean) if provided and true, this transaction must be in the final block\n"
            "      }\n"
            "      ,...\n"
            "  ],\n"
            "  \"coinbaseaux\" : {                 (json object) data that should be included in the coinbase's scriptSig content\n"
            "      \"flags\" : \"xx\"                  (string) key name is to be ignored, and value included in scriptSig\n"
            "  },\n"
            "  \"coinbasevalue\" : n,              (numeric) maximum allowable input to coinbase transaction, including the generation award and transaction fees (in duffs)\n"
            "  \"coinbasetxn\" : { ... },          (json object) information for coinbase transaction\n"
            "  \"target\" : \"xxxx\",                (string) The hash target\n"
            "  \"mintime\" : xxx,                  (numeric) The minimum timestamp appropriate for next block time in seconds since epoch (Jan 1 1970 GMT)\n"
            "  \"mutable\" : [                     (array of string) list of ways the block template may be changed \n"
            "     \"value\"                          (string) A way the block template may be changed, e.g. 'time', 'transactions', 'prevblock'\n"
            "     ,...\n"
            "  ],\n"
            "  \"noncerange\" : \"00000000ffffffff\",(string) A range of valid nonces\n"
            "  \"sigoplimit\" : n,                 (numeric) limit of sigops in blocks\n"
            "  \"sizelimit\" : n,                  (numeric) limit of block size\n"
            "  \"curtime\" : ttt,                  (numeric) current timestamp in seconds since epoch (Jan 1 1970 GMT)\n"
            "  \"bits\" : \"xxxxxxxx\",              (string) compressed target of next block\n"
            "  \"previousbits\" : \"xxxxxxxx\",      (string) compressed target of current highest block\n"
            "  \"height\" : n                      (numeric) The height of the next block\n"
            "  \"masternode\" : [                  (array) required masternode payments that must be included in the next block\n"
            "      {\n"
            "         \"payee\" : \"xxxx\",          (string) payee address\n"
            "         \"script\" : \"xxxx\",         (string) payee scriptPubKey\n"
            "         \"amount\": n                (numeric) required amount to pay\n"
            "      }\n"
            "  },\n"
            "  \"masternode_payments_started\" :  true|false, (boolean) true, if masternode payments started\n"
            "  \"masternode_payments_enforced\" : true|false, (boolean) true, if masternode payments are enforced\n"
            "  \"superblock\" : [                  (array) required superblock payees that must be included in the next block\n"
            "      {\n"
            "         \"payee\" : \"xxxx\",          (string) payee address\n"
            "         \"script\" : \"xxxx\",         (string) payee scriptPubKey\n"
            "         \"amount\": n                (numeric) required amount to pay\n"
            "      }\n"
            "      ,...\n"
            "  ],\n"
            "  \"superblocks_started\" : true|false, (boolean) true, if superblock payments started\n"
            "  \"superblocks_enabled\" : true|false, (boolean) true, if superblock payments are enabled\n"
            "  \"coinbase_payload\" : \"xxxxxxxx\"    (string) coinbase transaction payload data encoded in hexadecimal\n"
            "}\n"

            "\nExamples:\n"
            + HelpExampleCli("getblocktemplate", "")
            + HelpExampleRpc("getblocktemplate", "")
         );

    LOCK(cs_main);

    std::string strMode = "template";
    UniValue lpval = NullUniValue;
    std::set<std::string> setClientRules;
    int64_t nMaxVersionPreVB = -1;
    if (request.params.size() > 0)
    {
        const UniValue& oparam = request.params[0].get_obj();
        const UniValue& modeval = find_value(oparam, "mode");
        if (modeval.isStr())
            strMode = modeval.get_str();
        else if (modeval.isNull())
        {
            /* Do nothing */
        }
        else
            throw JSONRPCError(RPC_INVALID_PARAMETER, "Invalid mode");
        lpval = find_value(oparam, "longpollid");

        if (strMode == "proposal")
        {
            const UniValue& dataval = find_value(oparam, "data");
            if (!dataval.isStr())
                throw JSONRPCError(RPC_TYPE_ERROR, "Missing data String key for proposal");

            CBlock block;
            if (!DecodeHexBlk(block, dataval.get_str()))
                throw JSONRPCError(RPC_DESERIALIZATION_ERROR, "Block decode failed");

            uint256 hash = block.GetHash();
            BlockMap::iterator mi = mapBlockIndex.find(hash);
            if (mi != mapBlockIndex.end()) {
                CBlockIndex *pindex = mi->second;
                if (pindex->IsValid(BLOCK_VALID_SCRIPTS))
                    return "duplicate";
                if (pindex->nStatus & BLOCK_FAILED_MASK)
                    return "duplicate-invalid";
                return "duplicate-inconclusive";
            }

            CBlockIndex* const pindexPrev = chainActive.Tip();
            // TestBlockValidity only supports blocks built on the current Tip
            if (block.hashPrevBlock != pindexPrev->GetBlockHash())
                return "inconclusive-not-best-prevblk";
            CValidationState state;
            TestBlockValidity(state, Params(), block, pindexPrev, false, true);
            return BIP22ValidationResult(state);
        }

        const UniValue& aClientRules = find_value(oparam, "rules");
        if (aClientRules.isArray()) {
            for (unsigned int i = 0; i < aClientRules.size(); ++i) {
                const UniValue& v = aClientRules[i];
                setClientRules.insert(v.get_str());
            }
        } else {
            // NOTE: It is important that this NOT be read if versionbits is supported
            const UniValue& uvMaxVersion = find_value(oparam, "maxversion");
            if (uvMaxVersion.isNum()) {
                nMaxVersionPreVB = uvMaxVersion.get_int64();
            }
        }
    }

    if (strMode != "template")
        throw JSONRPCError(RPC_INVALID_PARAMETER, "Invalid mode");

    if(!g_connman)
        throw JSONRPCError(RPC_CLIENT_P2P_DISABLED, "Error: Peer-to-peer functionality missing or disabled");

    if (Params().MiningRequiresPeers()) {
        if (g_connman->GetNodeCount(CConnman::CONNECTIONS_ALL) == 0)
            throw JSONRPCError(RPC_CLIENT_NOT_CONNECTED, "Dash Core is not connected!");

        if (IsInitialBlockDownload())
            throw JSONRPCError(RPC_CLIENT_IN_INITIAL_DOWNLOAD, "Dash Core is downloading blocks...");
    }

    // when enforcement is on we need information about a masternode payee or otherwise our block is going to be orphaned by the network
    std::vector<CTxOut> voutMasternodePayments;
    if (sporkManager.IsSporkActive(SPORK_8_MASTERNODE_PAYMENT_ENFORCEMENT)
        && !masternodeSync.IsWinnersListSynced()
        && !mnpayments.GetBlockTxOuts(chainActive.Height() + 1, 0, voutMasternodePayments))
            throw JSONRPCError(RPC_CLIENT_IN_INITIAL_DOWNLOAD, "Dash Core is downloading masternode winners...");

    // next bock is a superblock and we need governance info to correctly construct it
    if (sporkManager.IsSporkActive(SPORK_9_SUPERBLOCKS_ENABLED)
        && !masternodeSync.IsSynced()
        && CSuperblock::IsValidBlockHeight(chainActive.Height() + 1))
            throw JSONRPCError(RPC_CLIENT_IN_INITIAL_DOWNLOAD, "Dash Core is syncing with network...");

    static unsigned int nTransactionsUpdatedLast;

    if (!lpval.isNull())
    {
        // Wait to respond until either the best block changes, OR a minute has passed and there are more transactions
        uint256 hashWatchedChain;
        boost::system_time checktxtime;
        unsigned int nTransactionsUpdatedLastLP;

        if (lpval.isStr())
        {
            // Format: <hashBestChain><nTransactionsUpdatedLast>
            std::string lpstr = lpval.get_str();

            hashWatchedChain.SetHex(lpstr.substr(0, 64));
            nTransactionsUpdatedLastLP = atoi64(lpstr.substr(64));
        }
        else
        {
            // NOTE: Spec does not specify behaviour for non-string longpollid, but this makes testing easier
            hashWatchedChain = chainActive.Tip()->GetBlockHash();
            nTransactionsUpdatedLastLP = nTransactionsUpdatedLast;
        }

        // Release the wallet and main lock while waiting
        LEAVE_CRITICAL_SECTION(cs_main);
        {
            checktxtime = boost::get_system_time() + boost::posix_time::minutes(1);

            boost::unique_lock<boost::mutex> lock(csBestBlock);
            while (chainActive.Tip()->GetBlockHash() == hashWatchedChain && IsRPCRunning())
            {
                if (!cvBlockChange.timed_wait(lock, checktxtime))
                {
                    // Timeout: Check transactions for update
                    if (mempool.GetTransactionsUpdated() != nTransactionsUpdatedLastLP)
                        break;
                    checktxtime += boost::posix_time::seconds(10);
                }
            }
        }
        ENTER_CRITICAL_SECTION(cs_main);

        if (!IsRPCRunning())
            throw JSONRPCError(RPC_CLIENT_NOT_CONNECTED, "Shutting down");
        // TODO: Maybe recheck connections/IBD and (if something wrong) send an expires-immediately template to stop miners?
    }

    // Update block
    static CBlockIndex* pindexPrev;
    static int64_t nStart;
    static std::unique_ptr<CBlockTemplate> pblocktemplate;
    if (pindexPrev != chainActive.Tip() ||
        (mempool.GetTransactionsUpdated() != nTransactionsUpdatedLast && GetTime() - nStart > 5))
    {
        // Clear pindexPrev so future calls make a new block, despite any failures from here on
        pindexPrev = nullptr;

        // Store the chainActive.Tip() used before CreateNewBlock, to avoid races
        nTransactionsUpdatedLast = mempool.GetTransactionsUpdated();
        CBlockIndex* pindexPrevNew = chainActive.Tip();
        nStart = GetTime();

        // Create new block
        CScript scriptDummy = CScript() << OP_TRUE;
        pblocktemplate = BlockAssembler(Params()).CreateNewBlock(scriptDummy);
        if (!pblocktemplate)
            throw JSONRPCError(RPC_OUT_OF_MEMORY, "Out of memory");

        // Need to update only after we know CreateNewBlock succeeded
        pindexPrev = pindexPrevNew;
    }
    CBlock* pblock = &pblocktemplate->block; // pointer for convenience
    const Consensus::Params& consensusParams = Params().GetConsensus();

    // Update nTime
    UpdateTime(pblock, consensusParams, pindexPrev);
    pblock->nNonce = 0;

    UniValue aCaps(UniValue::VARR); aCaps.push_back("proposal");

    UniValue transactions(UniValue::VARR);
    std::map<uint256, int64_t> setTxIndex;
    int i = 0;
    for (const auto& it : pblock->vtx) {
        const CTransaction& tx = *it;
        uint256 txHash = tx.GetHash();
        setTxIndex[txHash] = i++;

        if (tx.IsCoinBase())
            continue;

        UniValue entry(UniValue::VOBJ);

        entry.push_back(Pair("data", EncodeHexTx(tx)));

        entry.push_back(Pair("hash", txHash.GetHex()));

        UniValue deps(UniValue::VARR);
        BOOST_FOREACH (const CTxIn &in, tx.vin)
        {
            if (setTxIndex.count(in.prevout.hash))
                deps.push_back(setTxIndex[in.prevout.hash]);
        }
        entry.push_back(Pair("depends", deps));

        int index_in_template = i - 1;
        entry.push_back(Pair("fee", pblocktemplate->vTxFees[index_in_template]));
        entry.push_back(Pair("sigops", pblocktemplate->vTxSigOps[index_in_template]));

        transactions.push_back(entry);
    }

    UniValue aux(UniValue::VOBJ);
    aux.push_back(Pair("flags", HexStr(COINBASE_FLAGS.begin(), COINBASE_FLAGS.end())));

    arith_uint256 hashTarget = arith_uint256().SetCompact(pblock->nBits);

    UniValue aMutable(UniValue::VARR);
    aMutable.push_back("time");
    aMutable.push_back("transactions");
    aMutable.push_back("prevblock");

    UniValue result(UniValue::VOBJ);
    result.push_back(Pair("capabilities", aCaps));

    UniValue aRules(UniValue::VARR);
    UniValue vbavailable(UniValue::VOBJ);
    for (int j = 0; j < (int)Consensus::MAX_VERSION_BITS_DEPLOYMENTS; ++j) {
        Consensus::DeploymentPos pos = Consensus::DeploymentPos(j);
        ThresholdState state = VersionBitsState(pindexPrev, consensusParams, pos, versionbitscache);
        switch (state) {
            case THRESHOLD_DEFINED:
            case THRESHOLD_FAILED:
                // Not exposed to GBT at all
                break;
            case THRESHOLD_LOCKED_IN:
                // Ensure bit is set in block version
                pblock->nVersion |= VersionBitsMask(consensusParams, pos);
                // FALL THROUGH to get vbavailable set...
            case THRESHOLD_STARTED:
            {
                const struct BIP9DeploymentInfo& vbinfo = VersionBitsDeploymentInfo[pos];
                vbavailable.push_back(Pair(gbt_vb_name(pos), consensusParams.vDeployments[pos].bit));
                if (setClientRules.find(vbinfo.name) == setClientRules.end()) {
                    if (!vbinfo.gbt_force) {
                        // If the client doesn't support this, don't indicate it in the [default] version
                        pblock->nVersion &= ~VersionBitsMask(consensusParams, pos);
                    }
                }
                break;
            }
            case THRESHOLD_ACTIVE:
            {
                // Add to rules only
                const struct BIP9DeploymentInfo& vbinfo = VersionBitsDeploymentInfo[pos];
                aRules.push_back(gbt_vb_name(pos));
                if (setClientRules.find(vbinfo.name) == setClientRules.end()) {
                    // Not supported by the client; make sure it's safe to proceed
                    if (!vbinfo.gbt_force) {
                        // If we do anything other than throw an exception here, be sure version/force isn't sent to old clients
                        throw JSONRPCError(RPC_INVALID_PARAMETER, strprintf("Support for '%s' rule requires explicit client support", vbinfo.name));
                    }
                }
                break;
            }
        }
    }
    result.push_back(Pair("version", pblock->nVersion));
    result.push_back(Pair("rules", aRules));
    result.push_back(Pair("vbavailable", vbavailable));
    result.push_back(Pair("vbrequired", int(0)));

    if (nMaxVersionPreVB >= 2) {
        // If VB is supported by the client, nMaxVersionPreVB is -1, so we won't get here
        // Because BIP 34 changed how the generation transaction is serialized, we can only use version/force back to v2 blocks
        // This is safe to do [otherwise-]unconditionally only because we are throwing an exception above if a non-force deployment gets activated
        // Note that this can probably also be removed entirely after the first BIP9 non-force deployment (ie, probably segwit) gets activated
        aMutable.push_back("version/force");
    }

    result.push_back(Pair("previousblockhash", pblock->hashPrevBlock.GetHex()));
    result.push_back(Pair("transactions", transactions));
    result.push_back(Pair("coinbaseaux", aux));
    result.push_back(Pair("coinbasevalue", (int64_t)pblock->vtx[0]->GetValueOut()));
    result.push_back(Pair("longpollid", chainActive.Tip()->GetBlockHash().GetHex() + i64tostr(nTransactionsUpdatedLast)));
    result.push_back(Pair("target", hashTarget.GetHex()));
    result.push_back(Pair("mintime", (int64_t)pindexPrev->GetMedianTimePast()+1));
    result.push_back(Pair("mutable", aMutable));
    result.push_back(Pair("noncerange", "00000000ffffffff"));
    result.push_back(Pair("sigoplimit", (int64_t)MaxBlockSigOps(fDIP0001ActiveAtTip)));
    result.push_back(Pair("sizelimit", (int64_t)MaxBlockSize(fDIP0001ActiveAtTip)));
    result.push_back(Pair("curtime", pblock->GetBlockTime()));
    result.push_back(Pair("bits", strprintf("%08x", pblock->nBits)));
    result.push_back(Pair("previousbits", strprintf("%08x", pblocktemplate->nPrevBits)));
    result.push_back(Pair("height", (int64_t)(pindexPrev->nHeight+1)));

    UniValue masternodeObj(UniValue::VARR);
    for (const auto& txout : pblocktemplate->voutMasternodePayments) {
        CTxDestination address1;
        ExtractDestination(txout.scriptPubKey, address1);
        CBitcoinAddress address2(address1);

        UniValue obj(UniValue::VOBJ);
        obj.push_back(Pair("payee", address2.ToString().c_str()));
        obj.push_back(Pair("script", HexStr(txout.scriptPubKey)));
        obj.push_back(Pair("amount", txout.nValue));
        masternodeObj.push_back(obj);
    }

    result.push_back(Pair("masternode", masternodeObj));
    result.push_back(Pair("masternode_payments_started", pindexPrev->nHeight + 1 > consensusParams.nMasternodePaymentsStartBlock));
    result.push_back(Pair("masternode_payments_enforced", deterministicMNManager->IsDeterministicMNsSporkActive() || sporkManager.IsSporkActive(SPORK_8_MASTERNODE_PAYMENT_ENFORCEMENT)));

    UniValue superblockObjArray(UniValue::VARR);
    if(pblocktemplate->voutSuperblockPayments.size()) {
        for (const auto& txout : pblocktemplate->voutSuperblockPayments) {
            UniValue entry(UniValue::VOBJ);
            CTxDestination address1;
            ExtractDestination(txout.scriptPubKey, address1);
            CBitcoinAddress address2(address1);
            entry.push_back(Pair("payee", address2.ToString().c_str()));
            entry.push_back(Pair("script", HexStr(txout.scriptPubKey)));
            entry.push_back(Pair("amount", txout.nValue));
            superblockObjArray.push_back(entry);
        }
    }
    result.push_back(Pair("superblock", superblockObjArray));
    result.push_back(Pair("superblocks_started", pindexPrev->nHeight + 1 > consensusParams.nSuperblockStartBlock));
    result.push_back(Pair("superblocks_enabled", sporkManager.IsSporkActive(SPORK_9_SUPERBLOCKS_ENABLED)));

    result.push_back(Pair("coinbase_payload", HexStr(pblock->vtx[0]->vExtraPayload)));

    return result;
}