Fake outs set is now decided by the wallet

This plugs a privacy leak from the wallet to the daemon,
as the daemon could previously see what input is included
as a transaction input, which the daemon hadn't previously
supplied. Now, the wallet requests a particular set of
outputs, including the real one.

This can result in transactions that can't be accepted if
the wallet happens to select too many outputs with non standard
unlock times. The daemon could know this and select another
output, but the wallet is blind to it. It's currently very
unlikely since I don't think anything uses non default
unlock times. The wallet requests more outputs than necessary
so it can use spares if any of the returns outputs are still
locked. If there are not enough spares to reach the desired
mixin, the transaction will fail.

src/cryptonote_core/blockchain.cpp

@@ -1597,6 +1597,25 @@ bool Blockchain::get_random_outs_for_amounts(const COMMAND_RPC_GET_RANDOM_OUTPUT
   return true;
 }
 //------------------------------------------------------------------
+bool Blockchain::get_outs(const COMMAND_RPC_GET_OUTPUTS::request& req, COMMAND_RPC_GET_OUTPUTS::response& res) const
+{
+  LOG_PRINT_L3("Blockchain::" << __func__);
+  CRITICAL_REGION_LOCAL(m_blockchain_lock);
+
+  res.outs.clear();
+  res.outs.reserve(req.outputs.size());
+  for (const auto &i: req.outputs)
+  {
+    // get tx_hash, tx_out_index from DB
+    crypto::public_key key = m_db->get_output_key(i.amount, i.index).pubkey;
+    tx_out_index toi = m_db->get_output_tx_and_index(i.amount, i.index);
+    bool unlocked = is_tx_spendtime_unlocked(m_db->get_tx_unlock_time(toi.first));
+
+    res.outs.push_back({key, unlocked});
+  }
+  return true;
+}
+//------------------------------------------------------------------
 // This function takes a list of block hashes from another node
 // on the network to find where the split point is between us and them.
 // This is used to see what to send another node that needs to sync.

src/cryptonote_core/blockchain.h

@@ -439,6 +439,21 @@ namespace cryptonote
      */
     bool get_random_outs_for_amounts(const COMMAND_RPC_GET_RANDOM_OUTPUTS_FOR_AMOUNTS::request& req, COMMAND_RPC_GET_RANDOM_OUTPUTS_FOR_AMOUNTS::response& res) const;
 
+    /**
+     * @brief gets specific outputs to mix with
+     *
+     * This function takes an RPC request for outputs to mix with
+     * and creates an RPC response with the resultant output indices.
+     *
+     * Outputs to mix with are specified in the request.
+     *
+     * @param req the outputs to return
+     * @param res return-by-reference the resultant output indices and keys
+     *
+     * @return true
+     */
+    bool get_outs(const COMMAND_RPC_GET_OUTPUTS::request& req, COMMAND_RPC_GET_OUTPUTS::response& res) const;
+
     /**
      * @brief gets the global indices for outputs from a given transaction
      *

src/cryptonote_core/cryptonote_core.cpp

@@ -709,6 +709,11 @@ namespace cryptonote
     return m_blockchain_storage.get_random_outs_for_amounts(req, res);
   }
   //-----------------------------------------------------------------------------------------------
+  bool core::get_outs(const COMMAND_RPC_GET_OUTPUTS::request& req, COMMAND_RPC_GET_OUTPUTS::response& res) const
+  {
+    return m_blockchain_storage.get_outs(req, res);
+  }
+  //-----------------------------------------------------------------------------------------------
   bool core::get_tx_outputs_gindexs(const crypto::hash& tx_id, std::vector<uint64_t>& indexs) const
   {
     return m_blockchain_storage.get_tx_outputs_gindexs(tx_id, indexs);

src/cryptonote_core/cryptonote_core.h

@@ -476,6 +476,13 @@ namespace cryptonote
       */
      bool get_random_outs_for_amounts(const COMMAND_RPC_GET_RANDOM_OUTPUTS_FOR_AMOUNTS::request& req, COMMAND_RPC_GET_RANDOM_OUTPUTS_FOR_AMOUNTS::response& res) const;
 
+     /**
+      * @copydoc Blockchain::get_outs
+      *
+      * @note see Blockchain::get_outs
+      */
+     bool get_outs(const COMMAND_RPC_GET_OUTPUTS::request& req, COMMAND_RPC_GET_OUTPUTS::response& res) const;
+
 
      /**
       * @copydoc miner::pause