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

1 files changed, 14 insertions, 0 deletions

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
     {