Enforce restricted # pool txs served via RPC + optimize chunked reqs

- `/getblocks.bin` respects the `RESTRICTED_TX_COUNT` (=100) when
returning pool txs via a restricted RPC daemon.
- A restricted RPC daemon includes a max of `RESTRICTED_TX_COUNT` txs
in the `added_pool_txs` field, and returns any remaining pool hashes
in the `remaining_added_pool_txids` field. The client then requests
the remaining txs via `/gettransactions` in chunks.
- `/gettransactions` no longer does expensive no-ops for ALL pool txs
if the client requests a subset of pool txs. Instead it searches for
the txs the client explicitly requests.
- Reset `m_pool_info_query_time` when a user:
  (1) rescans the chain (so the wallet re-requests the whole pool)
  (2) changes the daemon their wallets points to (a new daemon would
      have a different view of the pool)
- `/getblocks.bin` respects the `req.prune` field when returning
pool txs.
- Pool extension fields in response to `/getblocks.bin` are optional
with default 0'd values.

5 files changed, 74 insertions, 37 deletions

diff --git a/src/cryptonote_core/blockchain.cpp b/src/cryptonote_core/blockchain.cpp
index 135dd3df0..07ff5f068 100644
--- a/src/cryptonote_core/blockchain.cpp
+++ b/src/cryptonote_core/blockchain.cpp
@@ -2044,7 +2044,7 @@ bool Blockchain::handle_alternative_block(const block& b, const crypto::hash& id
       cryptonote::blobdata blob;
       if (m_tx_pool.have_tx(txid, relay_category::legacy))
       {
-        if (m_tx_pool.get_transaction_info(txid, td))
+        if (m_tx_pool.get_transaction_info(txid, td, true/*include_sensitive_data*/))
         {
           bei.block_cumulative_weight += td.weight;
         }
diff --git a/src/cryptonote_core/cryptonote_core.cpp b/src/cryptonote_core/cryptonote_core.cpp
index 0773dec7a..70431d23a 100644
--- a/src/cryptonote_core/cryptonote_core.cpp
+++ b/src/cryptonote_core/cryptonote_core.cpp
@@ -1727,6 +1727,11 @@ namespace cryptonote
     return true;
   }
   //-----------------------------------------------------------------------------------------------
+  bool core::get_pool_transactions_info(const std::vector<crypto::hash>& txids, std::vector<std::pair<crypto::hash, tx_memory_pool::tx_details>>& txs, bool include_sensitive_txes) const
+  {
+    return m_mempool.get_transactions_info(txids, txs, include_sensitive_txes);
+  }
+  //-----------------------------------------------------------------------------------------------
   bool core::get_pool_transactions(std::vector<transaction>& txs, bool include_sensitive_data) const
   {
     m_mempool.get_transactions(txs, include_sensitive_data);
@@ -1739,9 +1744,9 @@ namespace cryptonote
     return true;
   }
   //-----------------------------------------------------------------------------------------------
-  bool core::get_pool_info(time_t start_time, bool include_sensitive_txes, std::vector<tx_memory_pool::tx_details>& added_txs, std::vector<crypto::hash>& removed_txs, bool& incremental) const
+  bool core::get_pool_info(time_t start_time, bool include_sensitive_txes, size_t max_tx_count, std::vector<std::pair<crypto::hash, tx_memory_pool::tx_details>>& added_txs, std::vector<crypto::hash>& remaining_added_txids, std::vector<crypto::hash>& removed_txs, bool& incremental) const
   {
-    return m_mempool.get_pool_info(start_time, include_sensitive_txes, added_txs, removed_txs, incremental);
+    return m_mempool.get_pool_info(start_time, include_sensitive_txes, max_tx_count, added_txs, remaining_added_txids, removed_txs, incremental);
   }
   //-----------------------------------------------------------------------------------------------
   bool core::get_pool_transaction_stats(struct txpool_stats& stats, bool include_sensitive_data) const
diff --git a/src/cryptonote_core/cryptonote_core.h b/src/cryptonote_core/cryptonote_core.h
index b0d99e1ce..efab56405 100644
--- a/src/cryptonote_core/cryptonote_core.h
+++ b/src/cryptonote_core/cryptonote_core.h
@@ -510,12 +510,21 @@ namespace cryptonote
      bool get_pool_transaction_hashes(std::vector<crypto::hash>& txs, bool include_sensitive_txes = false) const;
 
      /**
+      * @copydoc tx_memory_pool::get_pool_transactions_info
+      * @param include_sensitive_txes include private transactions
+      *
+      * @note see tx_memory_pool::get_pool_transactions_info
+      */
+     bool get_pool_transactions_info(const std::vector<crypto::hash>& txids, std::vector<std::pair<crypto::hash, tx_memory_pool::tx_details>>& txs, bool include_sensitive_txes = false) const;
+
+     /**
       * @copydoc tx_memory_pool::get_pool_info
       * @param include_sensitive_txes include private transactions
+      * @param max_tx_count max allowed added_txs in response
       *
       * @note see tx_memory_pool::get_pool_info
       */
-     bool get_pool_info(time_t start_time, bool include_sensitive_txes, std::vector<tx_memory_pool::tx_details>& added_txs, std::vector<crypto::hash>& removed_txs, bool& incremental) const;
+     bool get_pool_info(time_t start_time, bool include_sensitive_txes, size_t max_tx_count, std::vector<std::pair<crypto::hash, tx_memory_pool::tx_details>>& added_txs, std::vector<crypto::hash>& remaining_added_txids, std::vector<crypto::hash>& removed_txs, bool& incremental) const;
 
     /**
       * @copydoc tx_memory_pool::get_transactions
diff --git a/src/cryptonote_core/tx_pool.cpp b/src/cryptonote_core/tx_pool.cpp
index 243912768..b2a800e2b 100644
--- a/src/cryptonote_core/tx_pool.cpp
+++ b/src/cryptonote_core/tx_pool.cpp
@@ -603,7 +603,7 @@ namespace cryptonote
     return true;
   }
   //---------------------------------------------------------------------------------
-  bool tx_memory_pool::get_transaction_info(const crypto::hash &txid, tx_details &td) const
+  bool tx_memory_pool::get_transaction_info(const crypto::hash &txid, tx_details &td, bool include_sensitive_data, bool include_blob) const
   {
     PERF_TIMER(get_transaction_info);
     CRITICAL_REGION_LOCAL(m_transactions_lock);
@@ -615,7 +615,12 @@ namespace cryptonote
       txpool_tx_meta_t meta;
       if (!m_blockchain.get_txpool_tx_meta(txid, meta))
       {
-        MERROR("Failed to find tx in txpool");
+        LOG_PRINT_L2("Failed to find tx in txpool: " << txid);
+        return false;
+      }
+      if (!include_sensitive_data && !meta.matches(relay_category::broadcasted))
+      {
+        // We don't want sensitive data && the tx is sensitive, so no need to return it
         return false;
       }
       cryptonote::blobdata txblob = m_blockchain.get_txpool_tx_blob(txid, relay_category::all);
@@ -641,12 +646,13 @@ namespace cryptonote
       td.kept_by_block = meta.kept_by_block;
       td.last_failed_height = meta.last_failed_height;
       td.last_failed_id = meta.last_failed_id;
-      td.receive_time = meta.receive_time;
-      td.last_relayed_time = meta.dandelionpp_stem ? 0 : meta.last_relayed_time;
+      td.receive_time = include_sensitive_data ? meta.receive_time : 0;
+      td.last_relayed_time = (include_sensitive_data && !meta.dandelionpp_stem) ? meta.last_relayed_time : 0;
       td.relayed = meta.relayed;
       td.do_not_relay = meta.do_not_relay;
       td.double_spend_seen = meta.double_spend_seen;
-      td.sensitive = !meta.matches(relay_category::broadcasted);
+      if (include_blob)
+        td.tx_blob = std::move(txblob);
     }
     catch (const std::exception &e)
     {
@@ -656,6 +662,25 @@ namespace cryptonote
 
     return true;
   }
+  //------------------------------------------------------------------
+  bool tx_memory_pool::get_transactions_info(const std::vector<crypto::hash>& txids, std::vector<std::pair<crypto::hash, tx_details>>& txs, bool include_sensitive) const
+  {
+    CRITICAL_REGION_LOCAL(m_transactions_lock);
+    CRITICAL_REGION_LOCAL1(m_blockchain);
+
+    txs.clear();
+
+    for (const auto &it: txids)
+    {
+      tx_details details;
+      bool success = get_transaction_info(it, details, include_sensitive, true/*include_blob*/);
+      if (success)
+      {
+        txs.push_back(std::make_pair(it, std::move(details)));
+      }
+    }
+    return true;
+  }
   //---------------------------------------------------------------------------------
   bool tx_memory_pool::get_complement(const std::vector<crypto::hash> &hashes, std::vector<cryptonote::blobdata> &txes) const
   {
@@ -929,7 +954,7 @@ namespace cryptonote
     }, false, category);
   }
   //------------------------------------------------------------------
-  bool tx_memory_pool::get_pool_info(time_t start_time, bool include_sensitive, std::vector<tx_details>& added_txs, std::vector<crypto::hash>& removed_txs, bool& incremental) const
+  bool tx_memory_pool::get_pool_info(time_t start_time, bool include_sensitive, size_t max_tx_count, std::vector<std::pair<crypto::hash, tx_details>>& added_txs, std::vector<crypto::hash>& remaining_added_txids, std::vector<crypto::hash>& removed_txs, bool& incremental) const
   {
     CRITICAL_REGION_LOCAL(m_transactions_lock);
     CRITICAL_REGION_LOCAL1(m_blockchain);
@@ -957,46 +982,39 @@ namespace cryptonote
     }
 
     added_txs.clear();
+    remaining_added_txids.clear();
     removed_txs.clear();
 
+    std::vector<crypto::hash> txids;
     if (!incremental)
     {
+      LOG_PRINT_L2("Giving back the whole pool");
       // Give back the whole pool in 'added_txs'; because calling 'get_transaction_info' right inside the
       // anonymous method somehow results in an LMDB error with transactions we have to build a list of
       // ids first and get the full info afterwards
-      std::vector<crypto::hash> txids;
-      const relay_category category = include_sensitive ? relay_category::all : relay_category::broadcasted;
-      m_blockchain.for_all_txpool_txes([&txids](const crypto::hash &txid, const txpool_tx_meta_t &meta, const cryptonote::blobdata_ref *bd){
-        txids.push_back(txid);
-        return true;
-      }, false, category);
-      tx_details details;
-      for (const auto &it: txids)
+      get_transaction_hashes(txids, include_sensitive);
+      if (txids.size() > max_tx_count)
       {
-        bool success = get_transaction_info(it, details);
-        if (success)
-        {
-          added_txs.push_back(std::move(details));
-        }
+        remaining_added_txids = std::vector<crypto::hash>(txids.begin() + max_tx_count, txids.end());
+        txids.erase(txids.begin() + max_tx_count, txids.end());
       }
+      get_transactions_info(txids, added_txs, include_sensitive);
       return true;
     }
 
     // Give back incrementally, based on time of entry into the map
-    tx_details details;
     for (const auto &pit : m_added_txs_by_id)
     {
       if (pit.second >= start_time)
-      {
-        bool success = get_transaction_info(pit.first, details);
-        if (success)
-        {
-          if (include_sensitive || !details.sensitive)
-          {
-            added_txs.push_back(std::move(details));
-          }
-        }
-      }
+        txids.push_back(pit.first);
+    }
+    get_transactions_info(txids, added_txs, include_sensitive);
+    if (added_txs.size() > max_tx_count)
+    {
+      remaining_added_txids.reserve(added_txs.size() - max_tx_count);
+      for (size_t i = max_tx_count; i < added_txs.size(); ++i)
+        remaining_added_txids.push_back(added_txs[i].first);
+      added_txs.erase(added_txs.begin() + max_tx_count, added_txs.end());
     }
 
     std::multimap<time_t, removed_tx_info>::const_iterator rit = m_removed_txs_by_time.lower_bound(start_time);
diff --git a/src/cryptonote_core/tx_pool.h b/src/cryptonote_core/tx_pool.h
index 3e099cf2d..23135ead1 100644
--- a/src/cryptonote_core/tx_pool.h
+++ b/src/cryptonote_core/tx_pool.h
@@ -428,6 +428,7 @@ namespace cryptonote
     struct tx_details
     {
       transaction tx;  //!< the transaction
+      cryptonote::blobdata tx_blob; //!< the transaction's binary blob
       size_t blob_size;  //!< the transaction's size
       size_t weight;  //!< the transaction's weight
       uint64_t fee;  //!< the transaction's fee amount
@@ -461,13 +462,17 @@ namespace cryptonote
       bool do_not_relay; //!< to avoid relay this transaction to the network
 
       bool double_spend_seen; //!< true iff another tx was seen double spending this one
-      bool sensitive;
     };
 
     /**
      * @brief get infornation about a single transaction
      */
-    bool get_transaction_info(const crypto::hash &txid, tx_details &td) const;
+    bool get_transaction_info(const crypto::hash &txid, tx_details &td, bool include_sensitive_data, bool include_blob = false) const;
+
+    /**
+     * @brief get information about multiple transactions
+     */
+    bool get_transactions_info(const std::vector<crypto::hash>& txids, std::vector<std::pair<crypto::hash, tx_details>>& txs, bool include_sensitive_data = false) const;
 
     /**
      * @brief get transactions not in the passed set
@@ -479,7 +484,7 @@ namespace cryptonote
      *
      * @return true on success, false on error
      */
-    bool get_pool_info(time_t start_time, bool include_sensitive, std::vector<tx_details>& added_txs, std::vector<crypto::hash>& removed_txs, bool& incremental) const;
+    bool get_pool_info(time_t start_time, bool include_sensitive, size_t max_tx_count, std::vector<std::pair<crypto::hash, tx_details>>& added_txs, std::vector<crypto::hash>& remaining_added_txids, std::vector<crypto::hash>& removed_txs, bool& incremental) const;
 
   private: