RPC and ZeroMQ APIs to support p2pool

Adds the following:

- "get_miner_data" to RPC API
- "json-miner-data" to ZeroMQ subscriber contexts

Both provide the necessary data to create a custom block template. They are used by p2pool.

Data provided:

- major fork version
- current height
- previous block id
- RandomX seed hash
- network difficulty
- median block weight
- coins mined by the network so far
- mineable mempool transactions

18 files changed, 393 insertions, 24 deletions

diff --git a/src/cryptonote_basic/cryptonote_basic.h b/src/cryptonote_basic/cryptonote_basic.h
index 6394a7071..d111f6f32 100644
--- a/src/cryptonote_basic/cryptonote_basic.h
+++ b/src/cryptonote_basic/cryptonote_basic.h
@@ -49,6 +49,7 @@
 #include "misc_language.h"
 #include "ringct/rctTypes.h"
 #include "device/device.hpp"
+#include "cryptonote_basic/fwd.h"
 
 namespace cryptonote
 {
diff --git a/src/cryptonote_basic/events.h b/src/cryptonote_basic/events.h
index 6c6742215..3417ece8c 100644
--- a/src/cryptonote_basic/events.h
+++ b/src/cryptonote_basic/events.h
@@ -41,6 +41,8 @@ namespace cryptonote
   {
     cryptonote::transaction tx;
     crypto::hash hash;
+    uint64_t blob_size;
+    uint64_t weight;
     bool res; //!< Listeners must ignore `tx` when this is false.
   };
 }
diff --git a/src/cryptonote_basic/fwd.h b/src/cryptonote_basic/fwd.h
index d54223461..901ad151b 100644
--- a/src/cryptonote_basic/fwd.h
+++ b/src/cryptonote_basic/fwd.h
@@ -33,4 +33,5 @@ namespace cryptonote
   struct block;
   class transaction;
   struct txpool_event;
+  struct tx_block_template_backlog_entry;
 }
diff --git a/src/cryptonote_core/blockchain.cpp b/src/cryptonote_core/blockchain.cpp
index f0e6794b9..3d0e81af1 100644
--- a/src/cryptonote_core/blockchain.cpp
+++ b/src/cryptonote_core/blockchain.cpp
@@ -1238,6 +1238,12 @@ bool Blockchain::switch_to_alternative_blockchain(std::list<block_extended_info>
     reorg_notify->notify("%s", std::to_string(split_height).c_str(), "%h", std::to_string(m_db->height()).c_str(),
         "%n", std::to_string(m_db->height() - split_height).c_str(), "%d", std::to_string(discarded_blocks).c_str(), NULL);
 
+  crypto::hash prev_id;
+  if (!get_block_hash(alt_chain.back().bl, prev_id))
+    MERROR("Failed to get block hash of an alternative chain's tip");
+  else
+    send_miner_notifications(prev_id, alt_chain.back().already_generated_coins);
+
   for (const auto& notifier : m_block_notifiers)
   {
     std::size_t notify_height = split_height;
@@ -1784,6 +1790,30 @@ bool Blockchain::create_block_template(block& b, const account_public_address& m
   return create_block_template(b, NULL, miner_address, diffic, height, expected_reward, ex_nonce, seed_height, seed_hash);
 }
 //------------------------------------------------------------------
+bool Blockchain::get_miner_data(uint8_t& major_version, uint64_t& height, crypto::hash& prev_id, crypto::hash& seed_hash, difficulty_type& difficulty, uint64_t& median_weight, uint64_t& already_generated_coins, std::vector<tx_block_template_backlog_entry>& tx_backlog)
+{
+  prev_id = m_db->top_block_hash(&height);
+  ++height;
+
+  major_version = m_hardfork->get_ideal_version(height);
+
+  seed_hash = crypto::null_hash;
+  if (m_hardfork->get_current_version() >= RX_BLOCK_VERSION)
+  {
+    uint64_t seed_height, next_height;
+    crypto::rx_seedheights(height, &seed_height, &next_height);
+    seed_hash = get_block_id_by_height(seed_height);
+  }
+
+  difficulty = get_difficulty_for_next_block();
+  median_weight = m_current_block_cumul_weight_median;
+  already_generated_coins = m_db->get_block_already_generated_coins(height - 1);
+
+  m_tx_pool.get_block_template_backlog(tx_backlog);
+
+  return true;
+}
+//------------------------------------------------------------------
 // for an alternate chain, get the timestamps from the main chain to complete
 // the needed number of timestamps for the BLOCKCHAIN_TIMESTAMP_CHECK_WINDOW.
 bool Blockchain::complete_timestamps_vector(uint64_t start_top_height, std::vector<uint64_t>& timestamps) const
@@ -4362,6 +4392,7 @@ leave:
   get_difficulty_for_next_block(); // just to cache it
   invalidate_block_template_cache();
 
+  send_miner_notifications(id, already_generated_coins);
 
   for (const auto& notifier: m_block_notifiers)
     notifier(new_height - 1, {std::addressof(bl), 1});
@@ -5270,7 +5301,7 @@ void Blockchain::set_user_options(uint64_t maxthreads, bool sync_on_blocks, uint
   m_max_prepare_blocks_threads = maxthreads;
 }
 
-void Blockchain::add_block_notify(boost::function<void(std::uint64_t, epee::span<const block>)>&& notify)
+void Blockchain::add_block_notify(BlockNotifyCallback&& notify)
 {
   if (notify)
   {
@@ -5279,6 +5310,15 @@ void Blockchain::add_block_notify(boost::function<void(std::uint64_t, epee::span
   }
 }
 
+void Blockchain::add_miner_notify(MinerNotifyCallback&& notify)
+{
+  if (notify)
+  {
+    CRITICAL_REGION_LOCAL(m_blockchain_lock);
+    m_miner_notifiers.push_back(std::move(notify));
+  }
+}
+
 void Blockchain::safesyncmode(const bool onoff)
 {
   /* all of this is no-op'd if the user set a specific
@@ -5531,6 +5571,33 @@ void Blockchain::cache_block_template(const block &b, const cryptonote::account_
   m_btc_valid = true;
 }
 
+void Blockchain::send_miner_notifications(const crypto::hash &prev_id, uint64_t already_generated_coins)
+{
+  if (m_miner_notifiers.empty())
+    return;
+
+  const uint64_t height = m_db->height();
+  const uint8_t major_version = m_hardfork->get_ideal_version(height);
+  const difficulty_type diff = get_difficulty_for_next_block();
+  const uint64_t median_weight = m_current_block_cumul_weight_median;
+
+  crypto::hash seed_hash = crypto::null_hash;
+  if (m_hardfork->get_current_version() >= RX_BLOCK_VERSION)
+  {
+    uint64_t seed_height, next_height;
+    crypto::rx_seedheights(height, &seed_height, &next_height);
+    seed_hash = get_block_id_by_height(seed_height);
+  }
+
+  std::vector<tx_block_template_backlog_entry> tx_backlog;
+  m_tx_pool.get_block_template_backlog(tx_backlog);
+
+  for (const auto& notifier : m_miner_notifiers)
+  {
+    notifier(major_version, height, prev_id, seed_hash, diff, median_weight, already_generated_coins, tx_backlog);
+  }
+}
+
 namespace cryptonote {
 template bool Blockchain::get_transactions(const std::vector<crypto::hash>&, std::vector<transaction>&, std::vector<crypto::hash>&, bool) const;
 template bool Blockchain::get_split_transactions_blobs(const std::vector<crypto::hash>&, std::vector<std::tuple<crypto::hash, cryptonote::blobdata, crypto::hash, cryptonote::blobdata>>&, std::vector<crypto::hash>&) const;
diff --git a/src/cryptonote_core/blockchain.h b/src/cryptonote_core/blockchain.h
index a0e7967de..9afbfbc2d 100644
--- a/src/cryptonote_core/blockchain.h
+++ b/src/cryptonote_core/blockchain.h
@@ -90,6 +90,9 @@ namespace cryptonote
    */
   typedef std::function<const epee::span<const unsigned char>(cryptonote::network_type network)> GetCheckpointsCallback;
 
+  typedef boost::function<void(uint64_t /* height */, epee::span<const block> /* blocks */)> BlockNotifyCallback;
+  typedef boost::function<void(uint8_t /* major_version */, uint64_t /* height */, const crypto::hash& /* prev_id */, const crypto::hash& /* seed_hash */, difficulty_type /* diff */, uint64_t /* median_weight */, uint64_t /* already_generated_coins */, const std::vector<tx_block_template_backlog_entry>& /* tx_backlog */)> MinerNotifyCallback;
+
   /************************************************************************/
   /*                                                                      */
   /************************************************************************/
@@ -371,6 +374,22 @@ namespace cryptonote
     bool create_block_template(block& b, const crypto::hash *from_block, const account_public_address& miner_address, difficulty_type& di, uint64_t& height, uint64_t& expected_reward, const blobdata& ex_nonce, uint64_t &seed_height, crypto::hash &seed_hash);
 
     /**
+     * @brief gets data required to create a block template and start mining on it
+     *
+     * @param major_version current hardfork version
+     * @param height current blockchain height
+     * @param prev_id hash of the top block
+     * @param seed_hash seed hash used for RandomX initialization
+     * @param difficulty current mining difficulty
+     * @param median_weight current median block weight
+     * @param already_generated_coins current emission
+     * @param tx_backlog transactions in mempool ready to be mined
+     *
+     * @return true if block template filled in successfully, else false
+     */
+    bool get_miner_data(uint8_t& major_version, uint64_t& height, crypto::hash& prev_id, crypto::hash& seed_hash, difficulty_type& difficulty, uint64_t& median_weight, uint64_t& already_generated_coins, std::vector<tx_block_template_backlog_entry>& tx_backlog);
+
+    /**
      * @brief checks if a block is known about with a given hash
      *
      * This function checks the main chain, alternate chains, and invalid blocks
@@ -775,7 +794,14 @@ namespace cryptonote
      *
      * @param notify the notify object to call at every new block
      */
-    void add_block_notify(boost::function<void(std::uint64_t, epee::span<const block>)> &&notify);
+    void add_block_notify(BlockNotifyCallback&& notify);
+
+    /**
+     * @brief sets a miner notify object to call for every new block
+     *
+     * @param notify the notify object to call at every new block
+     */
+    void add_miner_notify(MinerNotifyCallback&& notify);
 
     /**
      * @brief sets a reorg notify object to call for every reorg
@@ -1157,7 +1183,8 @@ namespace cryptonote
        the callable object has a single `std::shared_ptr` or `std::weap_ptr`
        internally. Whereas, the libstdc++ `std::function` will allocate. */
 
-    std::vector<boost::function<void(std::uint64_t, epee::span<const block>)>> m_block_notifiers;
+    std::vector<BlockNotifyCallback> m_block_notifiers;
+    std::vector<MinerNotifyCallback> m_miner_notifiers;
     std::shared_ptr<tools::Notify> m_reorg_notify;
 
     // for prepare_handle_incoming_blocks
@@ -1537,5 +1564,13 @@ namespace cryptonote
      * At some point, may be used to push an update to miners
      */
     void cache_block_template(const block &b, const cryptonote::account_public_address &address, const blobdata &nonce, const difficulty_type &diff, uint64_t height, uint64_t expected_reward, uint64_t seed_height, const crypto::hash &seed_hash, uint64_t pool_cookie);
+
+    /**
+     * @brief sends new block notifications to ZMQ `miner_data` subscribers
+     *
+     * @param prev_id hash of new blockchain tip
+     * @param already_generated_coins total coins mined by the network so far
+     */
+    void send_miner_notifications(const crypto::hash &prev_id, uint64_t already_generated_coins);
   };
 }  // namespace cryptonote
diff --git a/src/cryptonote_core/cryptonote_core.cpp b/src/cryptonote_core/cryptonote_core.cpp
index 1da14221a..3b7ccb157 100644
--- a/src/cryptonote_core/cryptonote_core.cpp
+++ b/src/cryptonote_core/cryptonote_core.cpp
@@ -1063,8 +1063,9 @@ namespace cryptonote
       if (already_have[i])
         continue;
 
-      const uint64_t weight = results[i].tx.pruned ? get_pruned_transaction_weight(results[i].tx) : get_transaction_weight(results[i].tx, it->blob.size());
-      ok &= add_new_tx(results[i].tx, results[i].hash, tx_blobs[i].blob, weight, tvc[i], tx_relay, relayed);
+      results[i].blob_size = it->blob.size();
+      results[i].weight = results[i].tx.pruned ? get_pruned_transaction_weight(results[i].tx) : get_transaction_weight(results[i].tx, it->blob.size());
+      ok &= add_new_tx(results[i].tx, results[i].hash, tx_blobs[i].blob, results[i].weight, tvc[i], tx_relay, relayed);
 
       if(tvc[i].m_verifivation_failed)
       {MERROR_VER("Transaction verification failed: " << results[i].hash);}
@@ -1403,6 +1404,11 @@ namespace cryptonote
     return m_blockchain_storage.create_block_template(b, prev_block, adr, diffic, height, expected_reward, ex_nonce, seed_height, seed_hash);
   }
   //-----------------------------------------------------------------------------------------------
+  bool core::get_miner_data(uint8_t& major_version, uint64_t& height, crypto::hash& prev_id, crypto::hash& seed_hash, difficulty_type& difficulty, uint64_t& median_weight, uint64_t& already_generated_coins, std::vector<tx_block_template_backlog_entry>& tx_backlog)
+  {
+    return m_blockchain_storage.get_miner_data(major_version, height, prev_id, seed_hash, difficulty, median_weight, already_generated_coins, tx_backlog);
+  }
+  //-----------------------------------------------------------------------------------------------
   bool core::find_blockchain_supplement(const std::list<crypto::hash>& qblock_ids, bool clip_pruned, NOTIFY_RESPONSE_CHAIN_ENTRY::request& resp) const
   {
     return m_blockchain_storage.find_blockchain_supplement(qblock_ids, clip_pruned, resp);
diff --git a/src/cryptonote_core/cryptonote_core.h b/src/cryptonote_core/cryptonote_core.h
index 8478049f9..dd813733f 100644
--- a/src/cryptonote_core/cryptonote_core.h
+++ b/src/cryptonote_core/cryptonote_core.h
@@ -237,6 +237,13 @@ namespace cryptonote
      virtual bool get_block_template(block& b, const crypto::hash *prev_block, const account_public_address& adr, difficulty_type& diffic, uint64_t& height, uint64_t& expected_reward, const blobdata& ex_nonce, uint64_t &seed_height, crypto::hash &seed_hash);
 
      /**
+      * @copydoc Blockchain::get_miner_data
+      *
+      * @note see Blockchain::get_miner_data
+      */
+     bool get_miner_data(uint8_t& major_version, uint64_t& height, crypto::hash& prev_id, crypto::hash& seed_hash, difficulty_type& difficulty, uint64_t& median_weight, uint64_t& already_generated_coins, std::vector<tx_block_template_backlog_entry>& tx_backlog);
+
+     /**
       * @brief called when a transaction is relayed.
       * @note Should only be invoked from `levin_notify`.
       */
diff --git a/src/cryptonote_core/cryptonote_tx_utils.h b/src/cryptonote_core/cryptonote_tx_utils.h
index 73cdd31cd..06412d6bf 100644
--- a/src/cryptonote_core/cryptonote_tx_utils.h
+++ b/src/cryptonote_core/cryptonote_tx_utils.h
@@ -108,6 +108,15 @@ namespace cryptonote
   };
 
   //---------------------------------------------------------------
+
+  struct tx_block_template_backlog_entry
+  {
+    crypto::hash id;
+    uint64_t weight;
+    uint64_t fee;
+  };
+
+  //---------------------------------------------------------------
   crypto::public_key get_destination_view_key_pub(const std::vector<tx_destination_entry> &destinations, const boost::optional<cryptonote::account_public_address>& change_addr);
   bool construct_tx(const account_keys& sender_account_keys, std::vector<tx_source_entry> &sources, const std::vector<tx_destination_entry>& destinations, const boost::optional<cryptonote::account_public_address>& change_addr, const std::vector<uint8_t> &extra, transaction& tx, uint64_t unlock_time);
   bool construct_tx_with_tx_key(const account_keys& sender_account_keys, const std::unordered_map<crypto::public_key, subaddress_index>& subaddresses, std::vector<tx_source_entry>& sources, std::vector<tx_destination_entry>& destinations, const boost::optional<cryptonote::account_public_address>& change_addr, const std::vector<uint8_t> &extra, transaction& tx, uint64_t unlock_time, const crypto::secret_key &tx_key, const std::vector<crypto::secret_key> &additional_tx_keys, bool rct = false, const rct::RCTConfig &rct_config = { rct::RangeProofBorromean, 0 }, rct::multisig_out *msout = NULL, bool shuffle_outs = true);
diff --git a/src/cryptonote_core/tx_pool.cpp b/src/cryptonote_core/tx_pool.cpp
index a7e96e23a..84605d6f5 100644
--- a/src/cryptonote_core/tx_pool.cpp
+++ b/src/cryptonote_core/tx_pool.cpp
@@ -913,6 +913,32 @@ namespace cryptonote
     }, false, category);
   }
   //------------------------------------------------------------------
+  void tx_memory_pool::get_block_template_backlog(std::vector<tx_block_template_backlog_entry>& backlog, bool include_sensitive) const
+  {
+    CRITICAL_REGION_LOCAL(m_transactions_lock);
+    CRITICAL_REGION_LOCAL1(m_blockchain);
+    const relay_category category = include_sensitive ? relay_category::all : relay_category::broadcasted;
+    backlog.reserve(m_blockchain.get_txpool_tx_count(include_sensitive));
+    txpool_tx_meta_t tmp_meta;
+    m_blockchain.for_all_txpool_txes([this, &backlog, &tmp_meta](const crypto::hash &txid, const txpool_tx_meta_t &meta, const cryptonote::blobdata_ref *bd){
+      transaction tx;
+      if (!(meta.pruned ? parse_and_validate_tx_base_from_blob(*bd, tx) : parse_and_validate_tx_from_blob(*bd, tx)))
+      {
+        MERROR("Failed to parse tx from txpool");
+        // continue
+        return true;
+      }
+      tx.set_hash(txid);
+
+      tmp_meta = meta;
+
+      if (is_transaction_ready_to_go(tmp_meta, txid, *bd, tx))
+        backlog.push_back({txid, meta.weight, meta.fee});
+
+      return true;
+    }, true, category);
+  }
+  //------------------------------------------------------------------
   void tx_memory_pool::get_transaction_stats(struct txpool_stats& stats, bool include_sensitive) const
   {
     CRITICAL_REGION_LOCAL(m_transactions_lock);
@@ -1222,11 +1248,11 @@ namespace cryptonote
     return ret;
   }
   //---------------------------------------------------------------------------------
-  bool tx_memory_pool::is_transaction_ready_to_go(txpool_tx_meta_t& txd, const crypto::hash &txid, const cryptonote::blobdata &txblob, transaction &tx) const
+  bool tx_memory_pool::is_transaction_ready_to_go(txpool_tx_meta_t& txd, const crypto::hash &txid, const cryptonote::blobdata_ref& txblob, transaction &tx) const
   {
-    struct transction_parser
+    struct transaction_parser
     {
-      transction_parser(const cryptonote::blobdata &txblob, const crypto::hash &txid, transaction &tx): txblob(txblob), txid(txid), tx(tx), parsed(false) {}
+      transaction_parser(const cryptonote::blobdata_ref &txblob, const crypto::hash &txid, transaction &tx): txblob(txblob), txid(txid), tx(tx), parsed(false) {}
       cryptonote::transaction &operator()()
       {
         if (!parsed)
@@ -1238,7 +1264,7 @@ namespace cryptonote
         }
         return tx;
       }
-      const cryptonote::blobdata &txblob;
+      const cryptonote::blobdata_ref &txblob;
       const crypto::hash &txid;
       transaction &tx;
       bool parsed;
@@ -1289,6 +1315,11 @@ namespace cryptonote
     return true;
   }
   //---------------------------------------------------------------------------------
+  bool tx_memory_pool::is_transaction_ready_to_go(txpool_tx_meta_t& txd, const crypto::hash &txid, const cryptonote::blobdata& txblob, transaction &tx) const
+  {
+    return is_transaction_ready_to_go(txd, txid, cryptonote::blobdata_ref{txblob.data(), txblob.size()}, tx);
+  }
+  //---------------------------------------------------------------------------------
   bool tx_memory_pool::have_key_images(const std::unordered_set<crypto::key_image>& k_images, const transaction_prefix& tx)
   {
     for(size_t i = 0; i!= tx.vin.size(); i++)
diff --git a/src/cryptonote_core/tx_pool.h b/src/cryptonote_core/tx_pool.h
index ab2a57ea2..80b38c51d 100644
--- a/src/cryptonote_core/tx_pool.h
+++ b/src/cryptonote_core/tx_pool.h
@@ -266,6 +266,15 @@ namespace cryptonote
     void get_transaction_backlog(std::vector<tx_backlog_entry>& backlog, bool include_sensitive = false) const;
 
     /**
+     * @brief get (hash, weight, fee) for all transactions in the pool - the minimum required information to create a block template
+     *
+     * @param backlog return-by-reference that data
+     * @param include_sensitive return stempool, anonymity-pool, and unrelayed txes
+     *
+     */
+    void get_block_template_backlog(std::vector<tx_block_template_backlog_entry>& backlog, bool include_sensitive = false) const;
+
+    /**
      * @brief get a summary statistics of all transaction hashes in the pool
      *
      * @param stats return-by-reference the pool statistics
@@ -540,6 +549,7 @@ namespace cryptonote
      *
      * @return true if the transaction is good to go, otherwise false
      */
+    bool is_transaction_ready_to_go(txpool_tx_meta_t& txd, const crypto::hash &txid, const cryptonote::blobdata_ref &txblob, transaction&tx) const;
     bool is_transaction_ready_to_go(txpool_tx_meta_t& txd, const crypto::hash &txid, const cryptonote::blobdata &txblob, transaction&tx) const;
 
     /**
diff --git a/src/daemon/daemon.cpp b/src/daemon/daemon.cpp
index 99430b2b0..3f1885423 100644
--- a/src/daemon/daemon.cpp
+++ b/src/daemon/daemon.cpp
@@ -120,6 +120,7 @@ public:
       if (shared)
       {
         core.get().get_blockchain_storage().add_block_notify(cryptonote::listener::zmq_pub::chain_main{shared});
+        core.get().get_blockchain_storage().add_miner_notify(cryptonote::listener::zmq_pub::miner_data{shared});
         core.get().set_txpool_listener(cryptonote::listener::zmq_pub::txpool_add{shared});
       }
     }
diff --git a/src/rpc/core_rpc_server.cpp b/src/rpc/core_rpc_server.cpp
index 8d8a68efb..cd0cdad92 100644
--- a/src/rpc/core_rpc_server.cpp
+++ b/src/rpc/core_rpc_server.cpp
@@ -1861,6 +1861,43 @@ namespace cryptonote
     return true;
   }
   //------------------------------------------------------------------------------------------------------------------------------
+  bool core_rpc_server::on_getminerdata(const COMMAND_RPC_GETMINERDATA::request& req, COMMAND_RPC_GETMINERDATA::response& res, epee::json_rpc::error& error_resp, const connection_context *ctx)
+  {
+    if(!check_core_ready())
+    {
+      error_resp.code = CORE_RPC_ERROR_CODE_CORE_BUSY;
+      error_resp.message = "Core is busy";
+      return false;
+    }
+
+    crypto::hash prev_id, seed_hash;
+    difficulty_type difficulty;
+
+    std::vector<tx_block_template_backlog_entry> tx_backlog;
+    if (!m_core.get_miner_data(res.major_version, res.height, prev_id, seed_hash, difficulty, res.median_weight, res.already_generated_coins, tx_backlog))
+    {
+      error_resp.code = CORE_RPC_ERROR_CODE_INTERNAL_ERROR;
+      error_resp.message = "Internal error: failed to get miner data";
+      LOG_ERROR("Failed to get miner data");
+      return false;
+    }
+
+    res.tx_backlog.clear();
+    res.tx_backlog.reserve(tx_backlog.size());
+
+    for (const auto& entry : tx_backlog)
+    {
+      res.tx_backlog.emplace_back(COMMAND_RPC_GETMINERDATA::response::tx_backlog_entry{string_tools::pod_to_hex(entry.id), entry.weight, entry.fee});
+    }
+
+    res.prev_id = string_tools::pod_to_hex(prev_id);
+    res.seed_hash = string_tools::pod_to_hex(seed_hash);
+    res.difficulty = cryptonote::hex(difficulty);
+
+    res.status = CORE_RPC_STATUS_OK;
+    return true;
+  }
+  //------------------------------------------------------------------------------------------------------------------------------
   bool core_rpc_server::on_add_aux_pow(const COMMAND_RPC_ADD_AUX_POW::request& req, COMMAND_RPC_ADD_AUX_POW::response& res, epee::json_rpc::error& error_resp, const connection_context *ctx)
   {
     RPC_TRACKER(add_aux_pow);
diff --git a/src/rpc/core_rpc_server.h b/src/rpc/core_rpc_server.h
index b21e43ab0..9bc783299 100644
--- a/src/rpc/core_rpc_server.h
+++ b/src/rpc/core_rpc_server.h
@@ -147,6 +147,7 @@ namespace cryptonote
         MAP_JON_RPC_WE("on_getblockhash",        on_getblockhash,               COMMAND_RPC_GETBLOCKHASH)
         MAP_JON_RPC_WE("get_block_template",     on_getblocktemplate,           COMMAND_RPC_GETBLOCKTEMPLATE)
         MAP_JON_RPC_WE("getblocktemplate",       on_getblocktemplate,           COMMAND_RPC_GETBLOCKTEMPLATE)
+        MAP_JON_RPC_WE("get_miner_data",         on_getminerdata,               COMMAND_RPC_GETMINERDATA)
         MAP_JON_RPC_WE("add_aux_pow",            on_add_aux_pow,                COMMAND_RPC_ADD_AUX_POW)
         MAP_JON_RPC_WE("submit_block",           on_submitblock,                COMMAND_RPC_SUBMITBLOCK)
         MAP_JON_RPC_WE("submitblock",            on_submitblock,                COMMAND_RPC_SUBMITBLOCK)
@@ -228,6 +229,7 @@ namespace cryptonote
     bool on_getblockcount(const COMMAND_RPC_GETBLOCKCOUNT::request& req, COMMAND_RPC_GETBLOCKCOUNT::response& res, const connection_context *ctx = NULL);
     bool on_getblockhash(const COMMAND_RPC_GETBLOCKHASH::request& req, COMMAND_RPC_GETBLOCKHASH::response& res, epee::json_rpc::error& error_resp, const connection_context *ctx = NULL);
     bool on_getblocktemplate(const COMMAND_RPC_GETBLOCKTEMPLATE::request& req, COMMAND_RPC_GETBLOCKTEMPLATE::response& res, epee::json_rpc::error& error_resp, const connection_context *ctx = NULL);
+    bool on_getminerdata(const COMMAND_RPC_GETMINERDATA::request& req, COMMAND_RPC_GETMINERDATA::response& res, epee::json_rpc::error& error_resp, const connection_context *ctx = NULL);
     bool on_add_aux_pow(const COMMAND_RPC_ADD_AUX_POW::request& req, COMMAND_RPC_ADD_AUX_POW::response& res, epee::json_rpc::error& error_resp, const connection_context *ctx = NULL);
     bool on_submitblock(const COMMAND_RPC_SUBMITBLOCK::request& req, COMMAND_RPC_SUBMITBLOCK::response& res, epee::json_rpc::error& error_resp, const connection_context *ctx = NULL);
     bool on_generateblocks(const COMMAND_RPC_GENERATEBLOCKS::request& req, COMMAND_RPC_GENERATEBLOCKS::response& res, epee::json_rpc::error& error_resp, const connection_context *ctx = NULL);
diff --git a/src/rpc/core_rpc_server_commands_defs.h b/src/rpc/core_rpc_server_commands_defs.h
index ff8c98b98..1dbfc83a7 100644
--- a/src/rpc/core_rpc_server_commands_defs.h
+++ b/src/rpc/core_rpc_server_commands_defs.h
@@ -88,7 +88,7 @@ namespace cryptonote
 // advance which version they will stop working with
 // Don't go over 32767 for any of these
 #define CORE_RPC_VERSION_MAJOR 3
-#define CORE_RPC_VERSION_MINOR 7
+#define CORE_RPC_VERSION_MINOR 8
 #define MAKE_CORE_RPC_VERSION(major,minor) (((major)<<16)|(minor))
 #define CORE_RPC_VERSION MAKE_CORE_RPC_VERSION(CORE_RPC_VERSION_MAJOR, CORE_RPC_VERSION_MINOR)
 
@@ -940,6 +940,56 @@ namespace cryptonote
     typedef epee::misc_utils::struct_init<response_t> response;
   };
 
+  struct COMMAND_RPC_GETMINERDATA
+  {
+    struct request_t: public rpc_request_base
+    {
+      BEGIN_KV_SERIALIZE_MAP()
+        KV_SERIALIZE_PARENT(rpc_request_base)
+      END_KV_SERIALIZE_MAP()
+    };
+    typedef epee::misc_utils::struct_init<request_t> request;
+
+    struct response_t: public rpc_response_base
+    {
+      uint8_t major_version;
+      uint64_t height;
+      std::string prev_id;
+      std::string seed_hash;
+      std::string difficulty;
+      uint64_t median_weight;
+      uint64_t already_generated_coins;
+
+      struct tx_backlog_entry
+      {
+        std::string id;
+        uint64_t weight;
+        uint64_t fee;
+
+        BEGIN_KV_SERIALIZE_MAP()
+          KV_SERIALIZE(id)
+          KV_SERIALIZE(weight)
+          KV_SERIALIZE(fee)
+        END_KV_SERIALIZE_MAP()
+      };
+
+      std::vector<tx_backlog_entry> tx_backlog;
+
+      BEGIN_KV_SERIALIZE_MAP()
+        KV_SERIALIZE_PARENT(rpc_response_base)
+        KV_SERIALIZE(major_version)
+        KV_SERIALIZE(height)
+        KV_SERIALIZE(prev_id)
+        KV_SERIALIZE(seed_hash)
+        KV_SERIALIZE(difficulty)
+        KV_SERIALIZE(median_weight)
+        KV_SERIALIZE(already_generated_coins)
+        KV_SERIALIZE(tx_backlog)
+      END_KV_SERIALIZE_MAP()
+    };
+    typedef epee::misc_utils::struct_init<response_t> response;
+  };
+
   struct COMMAND_RPC_ADD_AUX_POW
   {
     struct aux_pow_t
diff --git a/src/rpc/zmq_pub.cpp b/src/rpc/zmq_pub.cpp
index eac530968..074b55207 100644
--- a/src/rpc/zmq_pub.cpp
+++ b/src/rpc/zmq_pub.cpp
@@ -48,6 +48,8 @@
 #include "cryptonote_basic/events.h"
 #include "misc_log_ex.h"
 #include "serialization/json_object.h"
+#include "ringct/rctTypes.h"
+#include "cryptonote_core/cryptonote_tx_utils.h"
 
 #undef MONERO_DEFAULT_LOG_CATEGORY
 #define MONERO_DEFAULT_LOG_CATEGORY "net.zmq"
@@ -57,6 +59,7 @@ namespace
   constexpr const char txpool_signal[] = "tx_signal";
 
   using chain_writer =  void(epee::byte_stream&, std::uint64_t, epee::span<const cryptonote::block>);
+  using miner_writer =  void(epee::byte_stream&, uint8_t, uint64_t, const crypto::hash&, const crypto::hash&, cryptonote::difficulty_type, uint64_t, uint64_t, const std::vector<cryptonote::tx_block_template_backlog_entry>&);
   using txpool_writer = void(epee::byte_stream&, epee::span<const cryptonote::txpool_event>);
 
   template<typename F>
@@ -116,13 +119,30 @@ namespace
     const epee::span<const cryptonote::block> blocks;
   };
 
+  //! Object for miner data serialization
+  struct miner_data
+  {
+    uint8_t major_version;
+    uint64_t height;
+    const crypto::hash& prev_id;
+    const crypto::hash& seed_hash;
+    cryptonote::difficulty_type diff;
+    uint64_t median_weight;
+    uint64_t already_generated_coins;
+    const std::vector<cryptonote::tx_block_template_backlog_entry>& tx_backlog;
+  };
+
   //! Object for "minimal" tx serialization
   struct minimal_txpool
   {
     const cryptonote::transaction& tx;
+    crypto::hash hash;
+    uint64_t blob_size;
+    uint64_t weight;
+    uint64_t fee;
   };
 
-  void toJsonValue(rapidjson::Writer<epee::byte_stream>& dest, const minimal_chain self)
+  void toJsonValue(rapidjson::Writer<epee::byte_stream>& dest, const minimal_chain& self)
   {
     namespace adapt = boost::adaptors;
 
@@ -143,19 +163,27 @@ namespace
     dest.EndObject();
   }
 
-  void toJsonValue(rapidjson::Writer<epee::byte_stream>& dest, const minimal_txpool self)
+  void toJsonValue(rapidjson::Writer<epee::byte_stream>& dest, const miner_data& self)
   {
-    crypto::hash id{};
-    std::size_t blob_size = 0;
-    if (!get_transaction_hash(self.tx, id, blob_size))
-    {
-      MERROR("ZMQ/Pub failure: get_transaction_hash");
-      return;
-    }
+    dest.StartObject();
+    INSERT_INTO_JSON_OBJECT(dest, major_version, self.major_version);
+    INSERT_INTO_JSON_OBJECT(dest, height, self.height);
+    INSERT_INTO_JSON_OBJECT(dest, prev_id, self.prev_id);
+    INSERT_INTO_JSON_OBJECT(dest, seed_hash, self.seed_hash);
+    INSERT_INTO_JSON_OBJECT(dest, difficulty, cryptonote::hex(self.diff));
+    INSERT_INTO_JSON_OBJECT(dest, median_weight, self.median_weight);
+    INSERT_INTO_JSON_OBJECT(dest, already_generated_coins, self.already_generated_coins);
+    INSERT_INTO_JSON_OBJECT(dest, tx_backlog, self.tx_backlog);
+    dest.EndObject();
+  }
 
+  void toJsonValue(rapidjson::Writer<epee::byte_stream>& dest, const minimal_txpool& self)
+  {
     dest.StartObject();
-    INSERT_INTO_JSON_OBJECT(dest, id, id);
-    INSERT_INTO_JSON_OBJECT(dest, blob_size, blob_size);
+    INSERT_INTO_JSON_OBJECT(dest, id, self.hash);
+    INSERT_INTO_JSON_OBJECT(dest, blob_size, self.blob_size);
+    INSERT_INTO_JSON_OBJECT(dest, weight, self.weight);
+    INSERT_INTO_JSON_OBJECT(dest, fee, self.fee);
     dest.EndObject();
   }
 
@@ -169,6 +197,11 @@ namespace
     json_pub(buf, minimal_chain{height, blocks});
   }
 
+  void json_miner_data(epee::byte_stream& buf, uint8_t major_version, uint64_t height, const crypto::hash& prev_id, const crypto::hash& seed_hash, cryptonote::difficulty_type diff, uint64_t median_weight, uint64_t already_generated_coins, const std::vector<cryptonote::tx_block_template_backlog_entry>& tx_backlog)
+  {
+    json_pub(buf, miner_data{major_version, height, prev_id, seed_hash, diff, median_weight, already_generated_coins, tx_backlog});
+  }
+
   // boost::adaptors are in place "views" - no copy/move takes place
   // moving transactions (via sort, etc.), is expensive!
 
@@ -187,7 +220,7 @@ namespace
     namespace adapt = boost::adaptors;
     const auto to_minimal_tx = [](const cryptonote::txpool_event& event)
     {
-      return minimal_txpool{event.tx};
+      return minimal_txpool{event.tx, event.hash, event.blob_size, event.weight, cryptonote::get_tx_fee(event.tx)};
     };
     json_pub(buf, (txes | adapt::filtered(is_valid{}) | adapt::transformed(to_minimal_tx)));
   }
@@ -198,6 +231,11 @@ namespace
     {u8"json-minimal-chain_main", json_minimal_chain}
   }};
 
+  constexpr const std::array<context<miner_writer>, 1> miner_contexts =
+  {{
+    {u8"json-full-miner_data", json_miner_data},
+  }};
+
   constexpr const std::array<context<txpool_writer>, 2> txpool_contexts =
   {{
     {u8"json-full-txpool_add", json_full_txpool},
@@ -321,6 +359,7 @@ namespace cryptonote { namespace listener
 zmq_pub::zmq_pub(void* context)
   : relay_(),
     chain_subs_{{0}},
+    miner_subs_{{0}},
     txpool_subs_{{0}},
     sync_()
 {
@@ -328,6 +367,7 @@ zmq_pub::zmq_pub(void* context)
     throw std::logic_error{"ZMQ context cannot be NULL"};
 
   verify_sorted(chain_contexts, "chain_contexts");
+  verify_sorted(miner_contexts, "miner_contexts");
   verify_sorted(txpool_contexts, "txpool_contexts");
 
   relay_.reset(zmq_socket(context, ZMQ_PAIR));
@@ -348,22 +388,25 @@ bool zmq_pub::sub_request(boost::string_ref message)
     message.remove_prefix(1);
 
     const auto chain_range = get_range(chain_contexts, message);
+    const auto miner_range = get_range(miner_contexts, message);
     const auto txpool_range = get_range(txpool_contexts, message);
 
-    if (!chain_range.empty() || !txpool_range.empty())
+    if (!chain_range.empty() || !miner_range.empty() || !txpool_range.empty())
     {
       MDEBUG("Client " << (tag ? "subscribed" : "unsubscribed") << " to " <<
-             chain_range.size() << " chain topic(s) and " << txpool_range.size() << " txpool topic(s)");
+             chain_range.size() << " chain topic(s), " << miner_range.size() << " miner topic(s) and " << txpool_range.size() << " txpool topic(s)");
 
       const boost::lock_guard<boost::mutex> lock{sync_};
       switch (tag)
       {
       case 0:
         remove_subscriptions(chain_subs_, chain_range, chain_contexts.begin());
+        remove_subscriptions(miner_subs_, miner_range, miner_contexts.begin());
         remove_subscriptions(txpool_subs_, txpool_range, txpool_contexts.begin());
         return true;
       case 1:
         add_subscriptions(chain_subs_, chain_range, chain_contexts.begin());
+        add_subscriptions(miner_subs_, miner_range, miner_contexts.begin());
         add_subscriptions(txpool_subs_, txpool_range, txpool_contexts.begin());
         return true;
       default:
@@ -436,6 +479,25 @@ std::size_t zmq_pub::send_chain_main(const std::uint64_t height, const epee::spa
   return 0;
 }
 
+std::size_t zmq_pub::send_miner_data(uint8_t major_version, uint64_t height, const crypto::hash& prev_id, const crypto::hash& seed_hash, difficulty_type diff, uint64_t median_weight, uint64_t already_generated_coins, const std::vector<tx_block_template_backlog_entry>& tx_backlog)
+{
+  boost::unique_lock<boost::mutex> guard{sync_};
+
+  const auto subs_copy = miner_subs_;
+  guard.unlock();
+
+  for (const std::size_t sub : subs_copy)
+  {
+    if (sub)
+    {
+        auto messages = make_pubs(subs_copy, miner_contexts, major_version, height, prev_id, seed_hash, diff, median_weight, already_generated_coins, tx_backlog);
+        guard.lock();
+        return send_messages(relay_.get(), messages);
+    }
+  }
+  return 0;
+}
+
 std::size_t zmq_pub::send_txpool_add(std::vector<txpool_event> txes)
 {
   if (txes.empty())
@@ -466,6 +528,15 @@ void zmq_pub::chain_main::operator()(const std::uint64_t height, epee::span<cons
     MERROR("Unable to send ZMQ/Pub - ZMQ server destroyed");
 }
 
+void zmq_pub::miner_data::operator()(uint8_t major_version, uint64_t height, const crypto::hash& prev_id, const crypto::hash& seed_hash, difficulty_type diff, uint64_t median_weight, uint64_t already_generated_coins, const std::vector<tx_block_template_backlog_entry>& tx_backlog) const
+{
+  const std::shared_ptr<zmq_pub> self = self_.lock();
+  if (self)
+    self->send_miner_data(major_version, height, prev_id, seed_hash, diff, median_weight, already_generated_coins, tx_backlog);
+  else
+    MERROR("Unable to send ZMQ/Pub - ZMQ server destroyed");
+}
+
 void zmq_pub::txpool_add::operator()(std::vector<cryptonote::txpool_event> txes) const
 {
   const std::shared_ptr<zmq_pub> self = self_.lock();
diff --git a/src/rpc/zmq_pub.h b/src/rpc/zmq_pub.h
index 02e6b8103..c636e1d7b 100644
--- a/src/rpc/zmq_pub.h
+++ b/src/rpc/zmq_pub.h
@@ -39,6 +39,7 @@
 #include "cryptonote_basic/fwd.h"
 #include "net/zmq.h"
 #include "span.h"
+#include "cryptonote_basic/difficulty.h"
 
 namespace cryptonote { namespace listener
 {
@@ -59,6 +60,7 @@ class zmq_pub
     net::zmq::socket relay_;
     std::deque<std::vector<txpool_event>> txes_;
     std::array<std::size_t, 2> chain_subs_;
+    std::array<std::size_t, 1> miner_subs_;
     std::array<std::size_t, 2> txpool_subs_;
     boost::mutex sync_; //!< Synchronizes counts in `*_subs_` arrays.
 
@@ -88,6 +90,11 @@ class zmq_pub
         \return Number of ZMQ messages sent to relay. */
     std::size_t send_chain_main(std::uint64_t height, epee::span<const cryptonote::block> blocks);
 
+    /*! Send a `ZMQ_PUB` notification for a new miner data.
+        Thread-safe.
+        \return Number of ZMQ messages sent to relay. */
+    std::size_t send_miner_data(uint8_t major_version, uint64_t height, const crypto::hash& prev_id, const crypto::hash& seed_hash, difficulty_type diff, uint64_t median_weight, uint64_t already_generated_coins, const std::vector<tx_block_template_backlog_entry>& tx_backlog);
+
     /*! Send a `ZMQ_PUB` notification for new tx(es) being added to the local
         pool. Thread-safe.
         \return Number of ZMQ messages sent to relay. */
@@ -100,6 +107,13 @@ class zmq_pub
       void operator()(std::uint64_t height, epee::span<const cryptonote::block> blocks) const;
     };
 
+    //! Callable for `send_miner_data` with weak ownership to `zmq_pub` object.
+    struct miner_data
+    {
+      std::weak_ptr<zmq_pub> self_;
+      void operator()(uint8_t major_version, uint64_t height, const crypto::hash& prev_id, const crypto::hash& seed_hash, difficulty_type diff, uint64_t median_weight, uint64_t already_generated_coins, const std::vector<tx_block_template_backlog_entry>& tx_backlog) const;
+    };
+
     //! Callable for `send_txpool_add` with weak ownership to `zmq_pub` object.
     struct txpool_add
     {
diff --git a/src/serialization/json_object.cpp b/src/serialization/json_object.cpp
index 28e207ff2..b03da1edc 100644
--- a/src/serialization/json_object.cpp
+++ b/src/serialization/json_object.cpp
@@ -34,6 +34,7 @@
 #include <type_traits>
 
 #include "cryptonote_basic/cryptonote_basic_impl.h"
+#include "cryptonote_core/cryptonote_tx_utils.h"
 
 // drop macro from windows.h
 #ifdef GetObject
@@ -1411,6 +1412,27 @@ void fromJsonValue(const rapidjson::Value& val, cryptonote::rpc::output_distribu
   GET_FROM_JSON_OBJECT(val, dist.data.base, base);
 }
 
+void toJsonValue(rapidjson::Writer<epee::byte_stream>& dest, const cryptonote::tx_block_template_backlog_entry& entry)
+{
+  dest.StartObject();
+  INSERT_INTO_JSON_OBJECT(dest, id, entry.id);
+  INSERT_INTO_JSON_OBJECT(dest, weight, entry.weight);
+  INSERT_INTO_JSON_OBJECT(dest, fee, entry.fee);
+  dest.EndObject();
+}
+
+void fromJsonValue(const rapidjson::Value& val, cryptonote::tx_block_template_backlog_entry& entry)
+{
+  if (!val.IsObject())
+  {
+    throw WRONG_TYPE("json object");
+  }
+
+  GET_FROM_JSON_OBJECT(val, entry.id, id);
+  GET_FROM_JSON_OBJECT(val, entry.weight, weight);
+  GET_FROM_JSON_OBJECT(val, entry.fee, fee);
+}
+
 }  // namespace json
 
 }  // namespace cryptonote
diff --git a/src/serialization/json_object.h b/src/serialization/json_object.h
index 35ea990b3..c858faf5a 100644
--- a/src/serialization/json_object.h
+++ b/src/serialization/json_object.h
@@ -304,6 +304,9 @@ void fromJsonValue(const rapidjson::Value& val, cryptonote::rpc::DaemonInfo& inf
 void toJsonValue(rapidjson::Writer<epee::byte_stream>& dest, const cryptonote::rpc::output_distribution& dist);
 void fromJsonValue(const rapidjson::Value& val, cryptonote::rpc::output_distribution& dist);
 
+void toJsonValue(rapidjson::Writer<epee::byte_stream>& dest, const cryptonote::tx_block_template_backlog_entry& entry);
+void fromJsonValue(const rapidjson::Value& val, cryptonote::tx_block_template_backlog_entry& entry);
+
 template <typename Map>
 typename std::enable_if<sfinae::is_map_like<Map>::value, void>::type toJsonValue(rapidjson::Writer<epee::byte_stream>& dest, const Map& map);