track double spending in the txpool

Transactions in the txpool are marked when another transaction
is seen double spending one or more of its inputs.
This is then exposed wherever appropriate.

Note that being marked with this "double spend seen" flag does
NOT mean this transaction IS a double spend and will never be
mined: it just means that the network has seen at least another
transaction spending at least one of the same inputs, so care
should be taken to wait for a few confirmations before acting
upon that transaction (ie, mostly of use for merchants wanting
to accept unconfirmed transactions).

src/blockchain_db/blockchain_db.h

@@ -147,8 +147,9 @@ struct txpool_tx_meta_t
   uint8_t kept_by_block;
   uint8_t relayed;
   uint8_t do_not_relay;
+  uint8_t double_spend_seen: 1;
 
-  uint8_t padding[77]; // till 192 bytes
+  uint8_t padding[76]; // till 192 bytes
 };
 
 #define DBF_SAFE       1

src/cryptonote_core/blockchain.cpp

@@ -3166,9 +3166,9 @@ bool Blockchain::flush_txes_from_pool(const std::list<crypto::hash> &txids)
     cryptonote::transaction tx;
     size_t blob_size;
     uint64_t fee;
-    bool relayed, do_not_relay;
+    bool relayed, do_not_relay, double_spend_seen;
     MINFO("Removing txid " << txid << " from the pool");
-    if(m_tx_pool.have_tx(txid) && !m_tx_pool.take_tx(txid, tx, blob_size, fee, relayed, do_not_relay))
+    if(m_tx_pool.have_tx(txid) && !m_tx_pool.take_tx(txid, tx, blob_size, fee, relayed, do_not_relay, double_spend_seen))
     {
       MERROR("Failed to remove txid " << txid << " from the pool");
       res = false;
@@ -3351,7 +3351,7 @@ leave:
     transaction tx;
     size_t blob_size = 0;
     uint64_t fee = 0;
-    bool relayed = false, do_not_relay = false;
+    bool relayed = false, do_not_relay = false, double_spend_seen = false;
     TIME_MEASURE_START(aa);
 
 // XXX old code does not check whether tx exists
@@ -3368,7 +3368,7 @@ leave:
     TIME_MEASURE_START(bb);
 
     // get transaction with hash <tx_id> from tx_pool
-    if(!m_tx_pool.take_tx(tx_id, tx, blob_size, fee, relayed, do_not_relay))
+    if(!m_tx_pool.take_tx(tx_id, tx, blob_size, fee, relayed, do_not_relay, double_spend_seen))
     {
       MERROR_VER("Block with id: " << id  << " has at least one unknown transaction with id: " << tx_id);
       bvc.m_verifivation_failed = true;
@@ -4381,12 +4381,12 @@ void Blockchain::load_compiled_in_block_hashes()
 
         size_t blob_size;
         uint64_t fee;
-        bool relayed, do_not_relay;
+        bool relayed, do_not_relay, double_spend_seen;
         transaction pool_tx;
         for(const transaction &tx : txs)
         {
           crypto::hash tx_hash = get_transaction_hash(tx);
-          m_tx_pool.take_tx(tx_hash, pool_tx, blob_size, fee, relayed, do_not_relay);
+          m_tx_pool.take_tx(tx_hash, pool_tx, blob_size, fee, relayed, do_not_relay, double_spend_seen);
         }
       }
     }

src/cryptonote_core/tx_pool.cpp

@@ -187,6 +187,7 @@ namespace cryptonote
     {
       if(have_tx_keyimges_as_spent(tx))
       {
+        mark_double_spend(tx);
         LOG_PRINT_L1("Transaction with id= "<< id << " used already spent key images");
         tvc.m_verifivation_failed = true;
         tvc.m_double_spend = true;
@@ -228,6 +229,7 @@ namespace cryptonote
         meta.last_relayed_time = time(NULL);
         meta.relayed = relayed;
         meta.do_not_relay = do_not_relay;
+        meta.double_spend_seen = have_tx_keyimges_as_spent(tx);
         memset(meta.padding, 0, sizeof(meta.padding));
         try
         {
@@ -266,6 +268,7 @@ namespace cryptonote
       meta.last_relayed_time = time(NULL);
       meta.relayed = relayed;
       meta.do_not_relay = do_not_relay;
+      meta.double_spend_seen = false;
       memset(meta.padding, 0, sizeof(meta.padding));
 
       try
@@ -354,7 +357,7 @@ namespace cryptonote
     return true;
   }
   //---------------------------------------------------------------------------------
-  bool tx_memory_pool::take_tx(const crypto::hash &id, transaction &tx, size_t& blob_size, uint64_t& fee, bool &relayed, bool &do_not_relay)
+  bool tx_memory_pool::take_tx(const crypto::hash &id, transaction &tx, size_t& blob_size, uint64_t& fee, bool &relayed, bool &do_not_relay, bool &double_spend_seen)
   {
     CRITICAL_REGION_LOCAL(m_transactions_lock);
     CRITICAL_REGION_LOCAL1(m_blockchain);
@@ -377,6 +380,7 @@ namespace cryptonote
       fee = meta.fee;
       relayed = meta.relayed;
       do_not_relay = meta.do_not_relay;
+      double_spend_seen = meta.double_spend_seen;
 
       // remove first, in case this throws, so key images aren't removed
       m_blockchain.remove_txpool_tx(id);
@@ -594,6 +598,8 @@ namespace cryptonote
       uint64_t age = now - meta.receive_time + (now == meta.receive_time);
       agebytes[age].txs++;
       agebytes[age].bytes += meta.blob_size;
+      if (meta.double_spend_seen)
+        ++stats.num_double_spends;
       return true;
     });
     stats.bytes_med = epee::misc_utils::median(sizes);
@@ -649,6 +655,7 @@ namespace cryptonote
     m_blockchain.for_all_txpool_txes([&tx_infos, key_image_infos](const crypto::hash &txid, const txpool_tx_meta_t &meta, const cryptonote::blobdata *bd){
       tx_info txi;
       txi.id_hash = epee::string_tools::pod_to_hex(txid);
+      txi.tx_blob = *bd;
       transaction tx;
       if (!parse_and_validate_tx_from_blob(*bd, tx))
       {
@@ -668,6 +675,7 @@ namespace cryptonote
       txi.relayed = meta.relayed;
       txi.last_relayed_time = meta.last_relayed_time;
       txi.do_not_relay = meta.do_not_relay;
+      txi.double_spend_seen = meta.double_spend_seen;
       tx_infos.push_back(txi);
       return true;
     }, true);
@@ -712,6 +720,7 @@ namespace cryptonote
       txi.relayed = meta.relayed;
       txi.last_relayed_time = meta.last_relayed_time;
       txi.do_not_relay = meta.do_not_relay;
+      txi.double_spend_seen = meta.double_spend_seen;
       tx_infos.push_back(txi);
       return true;
     }, true);
@@ -843,7 +852,10 @@ namespace cryptonote
     }
     //if we here, transaction seems valid, but, anyway, check for key_images collisions with blockchain, just to be sure
     if(m_blockchain.have_tx_keyimges_as_spent(tx))
+    {
+      txd.double_spend_seen = true;
       return false;
+    }
 
     //transaction is ok.
     return true;
@@ -871,6 +883,39 @@ namespace cryptonote
     return true;
   }
   //---------------------------------------------------------------------------------
+  void tx_memory_pool::mark_double_spend(const transaction &tx)
+  {
+    CRITICAL_REGION_LOCAL(m_transactions_lock);
+    CRITICAL_REGION_LOCAL1(m_blockchain);
+    LockedTXN lock(m_blockchain);
+    for(size_t i = 0; i!= tx.vin.size(); i++)
+    {
+      CHECKED_GET_SPECIFIC_VARIANT(tx.vin[i], const txin_to_key, itk, void());
+      const key_images_container::const_iterator it = m_spent_key_images.find(itk.k_image);
+      if (it != m_spent_key_images.end())
+      {
+        for (const crypto::hash &txid: it->second)
+        {
+          txpool_tx_meta_t meta = m_blockchain.get_txpool_tx_meta(txid);
+          if (!meta.double_spend_seen)
+          {
+            MDEBUG("Marking " << txid << " as double spending " << itk.k_image);
+            meta.double_spend_seen = true;
+            try
+            {
+              m_blockchain.update_txpool_tx(txid, meta);
+            }
+            catch (const std::exception &e)
+            {
+              MERROR("Failed to update tx meta: " << e.what());
+              // continue, not fatal
+            }
+          }
+        }
+      }
+    }
+  }
+  //---------------------------------------------------------------------------------
   std::string tx_memory_pool::print_pool(bool short_format) const
   {
     std::stringstream ss;
@@ -890,6 +935,7 @@ namespace cryptonote
       ss << "blob_size: " << meta.blob_size << std::endl
         << "fee: " << print_money(meta.fee) << std::endl
         << "kept_by_block: " << (meta.kept_by_block ? 'T' : 'F') << std::endl
+        << "double_spend_seen: " << (meta.double_spend_seen ? 'T' : 'F') << std::endl
         << "max_used_block_height: " << meta.max_used_block_height << std::endl
         << "max_used_block_id: " << meta.max_used_block_id << std::endl
         << "last_failed_height: " << meta.last_failed_height << std::endl

src/cryptonote_core/tx_pool.h

@@ -137,10 +137,11 @@ namespace cryptonote
      * @param fee the transaction fee
      * @param relayed return-by-reference was transaction relayed to us by the network?
      * @param do_not_relay return-by-reference is transaction not to be relayed to the network?
+     * @param double_spend_seen return-by-reference was a double spend seen for that transaction?
      *
      * @return true unless the transaction cannot be found in the pool
      */
-    bool take_tx(const crypto::hash &id, transaction &tx, size_t& blob_size, uint64_t& fee, bool &relayed, bool &do_not_relay);
+    bool take_tx(const crypto::hash &id, transaction &tx, size_t& blob_size, uint64_t& fee, bool &relayed, bool &do_not_relay, bool &double_spend_seen);
 
     /**
      * @brief checks if the pool has a transaction with the given hash
@@ -391,6 +392,8 @@ namespace cryptonote
       time_t last_relayed_time;  //!< the last time the transaction was relayed to the network
       bool relayed;  //!< whether or not the transaction has been relayed to the network
       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
     };
 
   private:
@@ -478,6 +481,11 @@ namespace cryptonote
      */
     bool is_transaction_ready_to_go(txpool_tx_meta_t& txd, transaction &tx) const;
 
+    /**
+     * @brief mark all transactions double spending the one passed
+     */
+    void mark_double_spend(const transaction &tx);
+
     //TODO: confirm the below comments and investigate whether or not this
     //      is the desired behavior
     //! map key images to transactions which spent them

src/daemon/rpc_command_executor.cpp

@@ -840,6 +840,7 @@ bool t_rpc_command_executor::print_transaction_pool_long() {
                           << "relayed: " << [&](const cryptonote::tx_info &tx_info)->std::string { if (!tx_info.relayed) return "no"; return boost::lexical_cast<std::string>(tx_info.last_relayed_time) + " (" + get_human_time_ago(tx_info.last_relayed_time, now) + ")"; } (tx_info) << std::endl
                           << "do_not_relay: " << (tx_info.do_not_relay ? 'T' : 'F')  << std::endl
                           << "kept_by_block: " << (tx_info.kept_by_block ? 'T' : 'F') << std::endl
+                          << "double_spend_seen: " << (tx_info.double_spend_seen ? 'T' : 'F')  << std::endl
                           << "max_used_block_height: " << tx_info.max_used_block_height << std::endl
                           << "max_used_block_id: " << tx_info.max_used_block_id_hash << std::endl
                           << "last_failed_height: " << tx_info.last_failed_height << std::endl
@@ -922,6 +923,7 @@ bool t_rpc_command_executor::print_transaction_pool_short() {
                           << "relayed: " << [&](const cryptonote::tx_info &tx_info)->std::string { if (!tx_info.relayed) return "no"; return boost::lexical_cast<std::string>(tx_info.last_relayed_time) + " (" + get_human_time_ago(tx_info.last_relayed_time, now) + ")"; } (tx_info) << std::endl
                           << "do_not_relay: " << (tx_info.do_not_relay ? 'T' : 'F')  << std::endl
                           << "kept_by_block: " << (tx_info.kept_by_block ? 'T' : 'F') << std::endl
+                          << "double_spend_seen: " << (tx_info.double_spend_seen ? 'T' : 'F') << std::endl
                           << "max_used_block_height: " << tx_info.max_used_block_height << std::endl
                           << "max_used_block_id: " << tx_info.max_used_block_id_hash << std::endl
                           << "last_failed_height: " << tx_info.last_failed_height << std::endl
@@ -984,7 +986,7 @@ bool t_rpc_command_executor::print_transaction_pool_stats() {
 
   tools::msg_writer() << n_transactions << " tx(es), " << res.pool_stats.bytes_total << " bytes total (min " << res.pool_stats.bytes_min << ", max " << res.pool_stats.bytes_max << ", avg " << avg_bytes << ", median " << res.pool_stats.bytes_med << ")" << std::endl
       << "fees " << cryptonote::print_money(res.pool_stats.fee_total) << " (avg " << cryptonote::print_money(n_transactions ? res.pool_stats.fee_total / n_transactions : 0) << " per tx" << ", " << cryptonote::print_money(res.pool_stats.bytes_total ? res.pool_stats.fee_total / res.pool_stats.bytes_total : 0) << " per byte)" << std::endl
-      << res.pool_stats.num_not_relayed << " not relayed, " << res.pool_stats.num_failing << " failing, " << res.pool_stats.num_10m << " older than 10 minutes (oldest " << (res.pool_stats.oldest == 0 ? "-" : get_human_time_ago(res.pool_stats.oldest, now)) << "), " << backlog_message;
+      << res.pool_stats.num_double_spends << " double spends, " << res.pool_stats.num_not_relayed << " not relayed, " << res.pool_stats.num_failing << " failing, " << res.pool_stats.num_10m << " older than 10 minutes (oldest " << (res.pool_stats.oldest == 0 ? "-" : get_human_time_ago(res.pool_stats.oldest, now)) << "), " << backlog_message;
 
   if (n_transactions > 1 && res.pool_stats.histo.size())
   {

src/rpc/core_rpc_server.cpp

@@ -478,15 +478,17 @@ namespace cryptonote
     // try the pool for any missing txes
     size_t found_in_pool = 0;
     std::unordered_set<crypto::hash> pool_tx_hashes;
+    std::unordered_map<crypto::hash, bool> double_spend_seen;
     if (!missed_txs.empty())
     {
-      std::list<transaction> pool_txs;
+      std::vector<tx_info> pool_tx_info;
-      bool r = m_core.get_pool_transactions(pool_txs);
+      std::vector<spent_key_image_info> pool_key_image_info;
+      bool r = m_core.get_pool_transactions_and_spent_keys_info(pool_tx_info, pool_key_image_info);
       if(r)
       {
         // sort to match original request
         std::list<transaction> sorted_txs;
-        std::list<cryptonote::transaction>::const_iterator i;
+        std::vector<tx_info>::const_iterator i;
         for (const crypto::hash &h: vh)
         {
           if (std::find(missed_txs.begin(), missed_txs.end(), h) == missed_txs.end())
@@ -500,11 +502,26 @@ namespace cryptonote
             sorted_txs.push_back(std::move(txs.front()));
             txs.pop_front();
           }
-          else if ((i = std::find_if(pool_txs.begin(), pool_txs.end(), [h](cryptonote::transaction &tx) { return h == cryptonote::get_transaction_hash(tx); })) != pool_txs.end())
+          else if ((i = std::find_if(pool_tx_info.begin(), pool_tx_info.end(), [h](const tx_info &txi) { return epee::string_tools::pod_to_hex(h) == txi.id_hash; })) != pool_tx_info.end())
           {
-            sorted_txs.push_back(*i);
+            cryptonote::transaction tx;
+            if (!cryptonote::parse_and_validate_tx_from_blob(i->tx_blob, tx))
+            {
+              res.status = "Failed to parse and validate tx from blob";
+              return true;
+            }
+            sorted_txs.push_back(tx);
             missed_txs.remove(h);
             pool_tx_hashes.insert(h);
+            const std::string hash_string = epee::string_tools::pod_to_hex(h);
+            for (const auto &ti: pool_tx_info)
+            {
+              if (ti.id_hash == hash_string)
+              {
+                double_spend_seen.insert(std::make_pair(h, ti.double_spend_seen));
+                break;
+              }
+            }
             ++found_in_pool;
           }
         }
@@ -530,11 +547,21 @@ namespace cryptonote
       if (e.in_pool)
       {
         e.block_height = e.block_timestamp = std::numeric_limits<uint64_t>::max();
+        if (double_spend_seen.find(tx_hash) != double_spend_seen.end())
+        {
+          e.double_spend_seen = double_spend_seen[tx_hash];
+        }
+        else
+        {
+          MERROR("Failed to determine double spend status for " << tx_hash);
+          e.double_spend_seen = false;
+        }
       }
       else
       {
         e.block_height = m_core.get_blockchain_storage().get_db().get_tx_block_height(tx_hash);
         e.block_timestamp = m_core.get_blockchain_storage().get_db().get_block_timestamp(e.block_height);
+        e.double_spend_seen = false;
       }
 
       // fill up old style responses too, in case an old wallet asks

src/rpc/core_rpc_server_commands_defs.h

@@ -566,6 +566,7 @@ namespace cryptonote
       std::string as_hex;
       std::string as_json;
       bool in_pool;
+      bool double_spend_seen;
       uint64_t block_height;
       uint64_t block_timestamp;
       std::vector<uint64_t> output_indices;
@@ -575,6 +576,7 @@ namespace cryptonote
         KV_SERIALIZE(as_hex)
         KV_SERIALIZE(as_json)
         KV_SERIALIZE(in_pool)
+        KV_SERIALIZE(double_spend_seen)
         KV_SERIALIZE(block_height)
         KV_SERIALIZE(block_timestamp)
         KV_SERIALIZE(output_indices)
@@ -1357,6 +1359,8 @@ namespace cryptonote
     bool relayed;
     uint64_t last_relayed_time;
     bool do_not_relay;
+    bool double_spend_seen;
+    std::string tx_blob;
 
     BEGIN_KV_SERIALIZE_MAP()
       KV_SERIALIZE(id_hash)
@@ -1372,6 +1376,8 @@ namespace cryptonote
       KV_SERIALIZE(relayed)
       KV_SERIALIZE(last_relayed_time)
       KV_SERIALIZE(do_not_relay)
+      KV_SERIALIZE(double_spend_seen)
+      KV_SERIALIZE(tx_blob)
     END_KV_SERIALIZE_MAP()
   };
 
@@ -1480,6 +1486,7 @@ namespace cryptonote
     uint32_t num_not_relayed;
     uint64_t histo_98pc;
     std::vector<txpool_histo> histo;
+    uint32_t num_double_spends;
 
     BEGIN_KV_SERIALIZE_MAP()
       KV_SERIALIZE(bytes_total)
@@ -1494,6 +1501,7 @@ namespace cryptonote
       KV_SERIALIZE(num_not_relayed)
       KV_SERIALIZE(histo_98pc)
       KV_SERIALIZE_CONTAINER_POD_AS_BLOB(histo)
+      KV_SERIALIZE(num_double_spends)
     END_KV_SERIALIZE_MAP()
   };
 

src/rpc/message_data_structs.h

@@ -95,6 +95,7 @@ namespace rpc
     uint64_t last_relayed_time;
     bool relayed;
     bool do_not_relay;
+    bool double_spend_seen;
   };
 
   typedef std::unordered_map<crypto::key_image, std::vector<crypto::hash> > key_images_with_tx_hashes;

src/serialization/json_object.cpp

@@ -755,6 +755,7 @@ void toJsonValue(rapidjson::Document& doc, const cryptonote::rpc::tx_in_pool& tx
   INSERT_INTO_JSON_OBJECT(val, doc, last_relayed_time, tx.last_relayed_time);
   INSERT_INTO_JSON_OBJECT(val, doc, relayed, tx.relayed);
   INSERT_INTO_JSON_OBJECT(val, doc, do_not_relay, tx.do_not_relay);
+  INSERT_INTO_JSON_OBJECT(val, doc, double_spend_seen, tx.double_spend_seen);
 }
 
 
@@ -777,6 +778,7 @@ void fromJsonValue(const rapidjson::Value& val, cryptonote::rpc::tx_in_pool& tx)
   GET_FROM_JSON_OBJECT(val, tx.last_relayed_time, last_relayed_time);
   GET_FROM_JSON_OBJECT(val, tx.relayed, relayed);
   GET_FROM_JSON_OBJECT(val, tx.do_not_relay, do_not_relay);
+  GET_FROM_JSON_OBJECT(val, tx.double_spend_seen, double_spend_seen);
 }
 
 void toJsonValue(rapidjson::Document& doc, const cryptonote::rpc::hard_fork_info& info, rapidjson::Value& val)

src/simplewallet/simplewallet.cpp

@@ -4415,15 +4415,18 @@ bool simple_wallet::show_transfers(const std::vector<std::string> &args_)
     try
     {
       m_wallet->update_pool_state();
-      std::list<std::pair<crypto::hash, tools::wallet2::payment_details>> payments;
+      std::list<std::pair<crypto::hash, tools::wallet2::pool_payment_details>> payments;
       m_wallet->get_unconfirmed_payments(payments, m_current_subaddress_account, subaddr_indices);
-      for (std::list<std::pair<crypto::hash, tools::wallet2::payment_details>>::const_iterator i = payments.begin(); i != payments.end(); ++i) {
+      for (std::list<std::pair<crypto::hash, tools::wallet2::pool_payment_details>>::const_iterator i = payments.begin(); i != payments.end(); ++i) {
-        const tools::wallet2::payment_details &pd = i->second;
+        const tools::wallet2::payment_details &pd = i->second.m_pd;
         std::string payment_id = string_tools::pod_to_hex(i->first);
         if (payment_id.substr(16).find_first_not_of('0') == std::string::npos)
           payment_id = payment_id.substr(0,16);
         std::string note = m_wallet->get_tx_note(pd.m_tx_hash);
-        message_writer() << (boost::format("%8.8s %6.6s %16.16s %20.20s %s %s %d %s %s") % "pool" % "in" % get_human_readable_timestamp(pd.m_timestamp) % print_money(pd.m_amount) % string_tools::pod_to_hex(pd.m_tx_hash) % payment_id % pd.m_subaddr_index.minor % "-" % note).str();
+        std::string double_spend_note;
+        if (i->second.m_double_spend_seen)
+          double_spend_note = tr("[Double spend seen on the network: this transaction may or may not end up being mined] ");
+        message_writer() << (boost::format("%8.8s %6.6s %16.16s %20.20s %s %s %d %s %s%s") % "pool" % "in" % get_human_readable_timestamp(pd.m_timestamp) % print_money(pd.m_amount) % string_tools::pod_to_hex(pd.m_tx_hash) % payment_id % pd.m_subaddr_index.minor % "-" % note % double_spend_note).str();
       }
     }
     catch (const std::exception& e)
@@ -5439,10 +5442,10 @@ bool simple_wallet::show_transfer(const std::vector<std::string> &args)
   try
   {
     m_wallet->update_pool_state();
-    std::list<std::pair<crypto::hash, tools::wallet2::payment_details>> pool_payments;
+    std::list<std::pair<crypto::hash, tools::wallet2::pool_payment_details>> pool_payments;
     m_wallet->get_unconfirmed_payments(pool_payments);
-    for (std::list<std::pair<crypto::hash, tools::wallet2::payment_details>>::const_iterator i = pool_payments.begin(); i != pool_payments.end(); ++i) {
+    for (std::list<std::pair<crypto::hash, tools::wallet2::pool_payment_details>>::const_iterator i = pool_payments.begin(); i != pool_payments.end(); ++i) {
-      const tools::wallet2::payment_details &pd = i->second;
+      const tools::wallet2::payment_details &pd = i->second.m_pd;
       if (pd.m_tx_hash == txid)
       {
         std::string payment_id = string_tools::pod_to_hex(i->first);
@@ -5455,6 +5458,8 @@ bool simple_wallet::show_transfer(const std::vector<std::string> &args)
         success_msg_writer() << "Payment ID: " << payment_id;
         success_msg_writer() << "Address index: " << pd.m_subaddr_index.minor;
         success_msg_writer() << "Note: " << m_wallet->get_tx_note(txid);
+        if (i->second.m_double_spend_seen)
+          success_msg_writer() << tr("Double spend seen on the network: this transaction may or may not end up being mined");
         return true;
       }
     }

src/wallet/api/transaction_history.cpp

@@ -217,10 +217,10 @@ void TransactionHistoryImpl::refresh()
     
     
     // unconfirmed payments (tx pool)
-    std::list<std::pair<crypto::hash, tools::wallet2::payment_details>> upayments;
+    std::list<std::pair<crypto::hash, tools::wallet2::pool_payment_details>> upayments;
     m_wallet->m_wallet->get_unconfirmed_payments(upayments);
-    for (std::list<std::pair<crypto::hash, tools::wallet2::payment_details>>::const_iterator i = upayments.begin(); i != upayments.end(); ++i) {  
+    for (std::list<std::pair<crypto::hash, tools::wallet2::pool_payment_details>>::const_iterator i = upayments.begin(); i != upayments.end(); ++i) {
-        const tools::wallet2::payment_details &pd = i->second;
+        const tools::wallet2::payment_details &pd = i->second.m_pd;
         std::string payment_id = string_tools::pod_to_hex(i->first);
         if (payment_id.substr(16).find_first_not_of('0') == std::string::npos)
             payment_id = payment_id.substr(0,16);

src/wallet/wallet2.cpp

@@ -444,6 +444,21 @@ std::string strjoin(const std::vector<size_t> &V, const char *sep)
   return ss.str();
 }
 
+static void emplace_or_replace(std::unordered_multimap<crypto::hash, tools::wallet2::pool_payment_details> &container,
+  const crypto::hash &key, const tools::wallet2::pool_payment_details &pd)
+{
+  auto range = container.equal_range(key);
+  for (auto i = range.first; i != range.second; ++i)
+  {
+    if (i->second.m_pd.m_tx_hash == pd.m_pd.m_tx_hash)
+    {
+      i->second = pd;
+      return;
+    }
+  }
+  container.emplace(key, pd);
+}
+
 } //namespace
 
 namespace tools
@@ -793,7 +808,7 @@ void wallet2::scan_output(const cryptonote::account_keys &keys, const cryptonote
   ++num_vouts_received;
 }
 //----------------------------------------------------------------------------------------------------
-void wallet2::process_new_transaction(const crypto::hash &txid, const cryptonote::transaction& tx, const std::vector<uint64_t> &o_indices, uint64_t height, uint64_t ts, bool miner_tx, bool pool)
+void wallet2::process_new_transaction(const crypto::hash &txid, const cryptonote::transaction& tx, const std::vector<uint64_t> &o_indices, uint64_t height, uint64_t ts, bool miner_tx, bool pool, bool double_spend_seen)
 {
   // In this function, tx (probably) only contains the base information
   // (that is, the prunable stuff may or may not be included)
@@ -1163,7 +1178,7 @@ void wallet2::process_new_transaction(const crypto::hash &txid, const cryptonote
       payment.m_timestamp    = ts;
       payment.m_subaddr_index = i.first;
       if (pool) {
-        m_unconfirmed_payments.emplace(payment_id, payment);
+        emplace_or_replace(m_unconfirmed_payments, payment_id, pool_payment_details{payment, double_spend_seen});
         if (0 != m_callback)
           m_callback->on_unconfirmed_money_received(height, txid, tx, payment.m_amount, payment.m_subaddr_index);
       }
@@ -1241,7 +1256,7 @@ void wallet2::process_new_blockchain_entry(const cryptonote::block& b, const cry
   if(b.timestamp + 60*60*24 > m_account.get_createtime() && height >= m_refresh_from_block_height)
   {
     TIME_MEASURE_START(miner_tx_handle_time);
-    process_new_transaction(get_transaction_hash(b.miner_tx), b.miner_tx, o_indices.indices[txidx++].indices, height, b.timestamp, true, false);
+    process_new_transaction(get_transaction_hash(b.miner_tx), b.miner_tx, o_indices.indices[txidx++].indices, height, b.timestamp, true, false, false);
     TIME_MEASURE_FINISH(miner_tx_handle_time);
 
     TIME_MEASURE_START(txs_handle_time);
@@ -1252,7 +1267,7 @@ void wallet2::process_new_blockchain_entry(const cryptonote::block& b, const cry
       cryptonote::transaction tx;
       bool r = parse_and_validate_tx_base_from_blob(txblob, tx);
       THROW_WALLET_EXCEPTION_IF(!r, error::tx_parse_error, txblob);
-      process_new_transaction(b.tx_hashes[idx], tx, o_indices.indices[txidx++].indices, height, b.timestamp, false, false);
+      process_new_transaction(b.tx_hashes[idx], tx, o_indices.indices[txidx++].indices, height, b.timestamp, false, false, false);
       ++idx;
     }
     TIME_MEASURE_FINISH(txs_handle_time);
@@ -1520,10 +1535,10 @@ void wallet2::pull_next_blocks(uint64_t start_height, uint64_t &blocks_start_hei
 void wallet2::remove_obsolete_pool_txs(const std::vector<crypto::hash> &tx_hashes)
 {
   // remove pool txes to us that aren't in the pool anymore
-  std::unordered_multimap<crypto::hash, wallet2::payment_details>::iterator uit = m_unconfirmed_payments.begin();
+  std::unordered_multimap<crypto::hash, wallet2::pool_payment_details>::iterator uit = m_unconfirmed_payments.begin();
   while (uit != m_unconfirmed_payments.end())
   {
-    const crypto::hash &txid = uit->second.m_tx_hash;
+    const crypto::hash &txid = uit->second.m_pd.m_tx_hash;
     bool found = false;
     for (const auto &it2: tx_hashes)
     {
@@ -1626,23 +1641,27 @@ void wallet2::update_pool_state(bool refreshed)
   MDEBUG("update_pool_state done second loop");
 
   // gather txids of new pool txes to us
-  std::vector<crypto::hash> txids;
+  std::vector<std::pair<crypto::hash, bool>> txids;
   for (const auto &txid: res.tx_hashes)
   {
-    if (m_scanned_pool_txs[0].find(txid) != m_scanned_pool_txs[0].end() || m_scanned_pool_txs[1].find(txid) != m_scanned_pool_txs[1].end())
-    {
-      LOG_PRINT_L2("Already seen " << txid << ", skipped");
-      continue;
-    }
     bool txid_found_in_up = false;
     for (const auto &up: m_unconfirmed_payments)
     {
-      if (up.second.m_tx_hash == txid)
+      if (up.second.m_pd.m_tx_hash == txid)
       {
         txid_found_in_up = true;
         break;
       }
     }
+    if (m_scanned_pool_txs[0].find(txid) != m_scanned_pool_txs[0].end() || m_scanned_pool_txs[1].find(txid) != m_scanned_pool_txs[1].end())
+    {
+      // if it's for us, we want to keep track of whether we saw a double spend, so don't bail out
+      if (!txid_found_in_up)
+      {
+        LOG_PRINT_L2("Already seen " << txid << ", and not for us, skipped");
+        continue;
+      }
+    }
     if (!txid_found_in_up)
     {
       LOG_PRINT_L1("Found new pool tx: " << txid);
@@ -1670,7 +1689,7 @@ void wallet2::update_pool_state(bool refreshed)
       if (!found)
       {
         // not one of those we sent ourselves
-        txids.push_back(txid);
+        txids.push_back({txid, false});
       }
       else
       {
@@ -1680,6 +1699,7 @@ void wallet2::update_pool_state(bool refreshed)
     else
     {
       LOG_PRINT_L1("Already saw that one, it's for us");
+      txids.push_back({txid, true});
     }
   }
 
@@ -1688,8 +1708,8 @@ void wallet2::update_pool_state(bool refreshed)
   {
     cryptonote::COMMAND_RPC_GET_TRANSACTIONS::request req;
     cryptonote::COMMAND_RPC_GET_TRANSACTIONS::response res;
-    for (const auto &txid: txids)
+    for (const auto &p: txids)
-      req.txs_hashes.push_back(epee::string_tools::pod_to_hex(txid));
+      req.txs_hashes.push_back(epee::string_tools::pod_to_hex(p.first));
     MDEBUG("asking for " << txids.size() << " transactions");
     req.decode_as_json = false;
     m_daemon_rpc_mutex.lock();
@@ -1711,10 +1731,11 @@ void wallet2::update_pool_state(bool refreshed)
             {
               if (cryptonote::parse_and_validate_tx_from_blob(bd, tx, tx_hash, tx_prefix_hash))
               {
-                const std::vector<crypto::hash>::const_iterator i = std::find(txids.begin(), txids.end(), tx_hash);
+                const std::vector<std::pair<crypto::hash, bool>>::const_iterator i = std::find_if(txids.begin(), txids.end(),
+                    [tx_hash](const std::pair<crypto::hash, bool> &e) { return e.first == tx_hash; });
                 if (i != txids.end())
                 {
-                  process_new_transaction(tx_hash, tx, std::vector<uint64_t>(), 0, time(NULL), false, true);
+                  process_new_transaction(tx_hash, tx, std::vector<uint64_t>(), 0, time(NULL), false, true, tx_entry.double_spend_seen);
                   m_scanned_pool_txs[0].insert(tx_hash);
                   if (m_scanned_pool_txs[0].size() > 5000)
                   {
@@ -3073,11 +3094,11 @@ void wallet2::get_unconfirmed_payments_out(std::list<std::pair<crypto::hash,wall
   }
 }
 //----------------------------------------------------------------------------------------------------
-void wallet2::get_unconfirmed_payments(std::list<std::pair<crypto::hash,wallet2::payment_details>>& unconfirmed_payments, const boost::optional<uint32_t>& subaddr_account, const std::set<uint32_t>& subaddr_indices) const
+void wallet2::get_unconfirmed_payments(std::list<std::pair<crypto::hash,wallet2::pool_payment_details>>& unconfirmed_payments, const boost::optional<uint32_t>& subaddr_account, const std::set<uint32_t>& subaddr_indices) const
 {
   for (auto i = m_unconfirmed_payments.begin(); i != m_unconfirmed_payments.end(); ++i) {
-    if ((!subaddr_account || *subaddr_account == i->second.m_subaddr_index.major) &&
+    if ((!subaddr_account || *subaddr_account == i->second.m_pd.m_subaddr_index.major) &&
-      (subaddr_indices.empty() || subaddr_indices.count(i->second.m_subaddr_index.minor) == 1))
+      (subaddr_indices.empty() || subaddr_indices.count(i->second.m_pd.m_subaddr_index.minor) == 1))
     unconfirmed_payments.push_back(*i);
   }
 }
@@ -5129,7 +5150,7 @@ void wallet2::light_wallet_get_address_txs()
     payments_txs.push_back(p.second.m_tx_hash);
   std::vector<crypto::hash> unconfirmed_payments_txs;
   for(const auto &up: m_unconfirmed_payments)
-    unconfirmed_payments_txs.push_back(up.second.m_tx_hash);
+    unconfirmed_payments_txs.push_back(up.second.m_pd.m_tx_hash);
 
   // for balance calculation
   uint64_t wallet_total_sent = 0;
@@ -5195,7 +5216,11 @@ void wallet2::light_wallet_get_address_txs()
       if (t.mempool) {   
         if (std::find(unconfirmed_payments_txs.begin(), unconfirmed_payments_txs.end(), tx_hash) == unconfirmed_payments_txs.end()) {
           pool_txs.push_back(tx_hash);
-          m_unconfirmed_payments.emplace(tx_hash, payment);
+          // assume false as we don't get that info from the light wallet server
+          crypto::hash payment_id;
+          THROW_WALLET_EXCEPTION_IF(!epee::string_tools::hex_to_pod(t.payment_id, payment_id),
+              error::wallet_internal_error, "Failed to parse payment id");
+          emplace_or_replace(m_unconfirmed_payments, payment_id, pool_payment_details{payment, false});
           if (0 != m_callback) {
             m_callback->on_lw_unconfirmed_money_received(t.height, payment.m_tx_hash, payment.m_amount);
           }

src/wallet/wallet2.h

@@ -244,6 +244,12 @@ namespace tools
       bool m_incoming;
     };
 
+    struct pool_payment_details
+    {
+      payment_details m_pd;
+      bool m_double_spend_seen;
+    };
+
     struct unconfirmed_transfer_details
     {
       cryptonote::transaction_prefix m_tx;
@@ -530,7 +536,7 @@ namespace tools
     void get_payments_out(std::list<std::pair<crypto::hash,wallet2::confirmed_transfer_details>>& confirmed_payments,
       uint64_t min_height, uint64_t max_height = (uint64_t)-1, const boost::optional<uint32_t>& subaddr_account = boost::none, const std::set<uint32_t>& subaddr_indices = {}) const;
     void get_unconfirmed_payments_out(std::list<std::pair<crypto::hash,wallet2::unconfirmed_transfer_details>>& unconfirmed_payments, const boost::optional<uint32_t>& subaddr_account = boost::none, const std::set<uint32_t>& subaddr_indices = {}) const;
-    void get_unconfirmed_payments(std::list<std::pair<crypto::hash,wallet2::payment_details>>& unconfirmed_payments, const boost::optional<uint32_t>& subaddr_account = boost::none, const std::set<uint32_t>& subaddr_indices = {}) const;
+    void get_unconfirmed_payments(std::list<std::pair<crypto::hash,wallet2::pool_payment_details>>& unconfirmed_payments, const boost::optional<uint32_t>& subaddr_account = boost::none, const std::set<uint32_t>& subaddr_indices = {}) const;
 
     uint64_t get_blockchain_current_height() const { return m_local_bc_height; }
     void rescan_spent();
@@ -585,7 +591,7 @@ namespace tools
         std::unordered_map<crypto::hash, payment_details> m;
         a & m;
         for (std::unordered_map<crypto::hash, payment_details>::const_iterator i = m.begin(); i != m.end(); ++i)
-          m_unconfirmed_payments.insert(*i);
+          m_unconfirmed_payments.insert(std::make_pair(i->first, pool_payment_details{i->second, false}));
       }
       if(ver < 14)
         return;
@@ -607,7 +613,15 @@ namespace tools
       a & m_address_book;
       if(ver < 17)
         return;
-      a & m_unconfirmed_payments;
+      if (ver < 21)
+      {
+        // we're loading an old version, where m_unconfirmed_payments payload was payment_details
+        std::unordered_map<crypto::hash, payment_details> m;
+        a & m;
+        for (const auto &i: m)
+          m_unconfirmed_payments.insert(std::make_pair(i.first, pool_payment_details{i.second, false}));
+        return;
+      }
       if(ver < 18)
         return;
       a & m_scanned_pool_txs[0];
@@ -621,6 +635,9 @@ namespace tools
       if(ver < 21)
         return;
       a & m_attributes;
+      if(ver < 22)
+        return;
+      a & m_unconfirmed_payments;
     }
 
     /*!
@@ -797,7 +814,7 @@ namespace tools
      * \param password       Password of wallet file
      */
     bool load_keys(const std::string& keys_file_name, const std::string& password);
-    void process_new_transaction(const crypto::hash &txid, const cryptonote::transaction& tx, const std::vector<uint64_t> &o_indices, uint64_t height, uint64_t ts, bool miner_tx, bool pool);
+    void process_new_transaction(const crypto::hash &txid, const cryptonote::transaction& tx, const std::vector<uint64_t> &o_indices, uint64_t height, uint64_t ts, bool miner_tx, bool pool, bool double_spend_seen);
     void process_new_blockchain_entry(const cryptonote::block& b, const cryptonote::block_complete_entry& bche, const crypto::hash& bl_id, uint64_t height, const cryptonote::COMMAND_RPC_GET_BLOCKS_FAST::block_output_indices &o_indices);
     void detach_blockchain(uint64_t height);
     void get_short_chain_history(std::list<crypto::hash>& ids) const;
@@ -846,7 +863,7 @@ namespace tools
     std::atomic<uint64_t> m_local_bc_height; //temporary workaround
     std::unordered_map<crypto::hash, unconfirmed_transfer_details> m_unconfirmed_txs;
     std::unordered_map<crypto::hash, confirmed_transfer_details> m_confirmed_txs;
-    std::unordered_multimap<crypto::hash, payment_details> m_unconfirmed_payments;
+    std::unordered_multimap<crypto::hash, pool_payment_details> m_unconfirmed_payments;
     std::unordered_map<crypto::hash, crypto::secret_key> m_tx_keys;
     cryptonote::checkpoints m_checkpoints;
     std::unordered_map<crypto::hash, std::vector<crypto::secret_key>> m_additional_tx_keys;
@@ -908,9 +925,10 @@ namespace tools
     std::unordered_map<crypto::public_key, std::map<uint64_t, crypto::key_image> > m_key_image_cache;
   };
 }
-BOOST_CLASS_VERSION(tools::wallet2, 21)
+BOOST_CLASS_VERSION(tools::wallet2, 22)
 BOOST_CLASS_VERSION(tools::wallet2::transfer_details, 8)
 BOOST_CLASS_VERSION(tools::wallet2::payment_details, 2)
+BOOST_CLASS_VERSION(tools::wallet2::pool_payment_details, 1)
 BOOST_CLASS_VERSION(tools::wallet2::unconfirmed_transfer_details, 7)
 BOOST_CLASS_VERSION(tools::wallet2::confirmed_transfer_details, 5)
 BOOST_CLASS_VERSION(tools::wallet2::address_book_row, 17)
@@ -1138,6 +1156,13 @@ namespace boost
       a & x.m_subaddr_index;
     }
 
+    template <class Archive>
+    inline void serialize(Archive& a, tools::wallet2::pool_payment_details& x, const boost::serialization::version_type ver)
+    {
+      a & x.m_pd;
+      a & x.m_double_spend_seen;
+    }
+
     template <class Archive>
     inline void serialize(Archive& a, tools::wallet2::address_book_row& x, const boost::serialization::version_type ver)
     {

src/wallet/wallet_rpc_server.cpp

@@ -299,8 +299,9 @@ namespace tools
     entry.subaddr_index = { pd.m_subaddr_account, 0 };
   }
   //------------------------------------------------------------------------------------------------------------------------------
-  void wallet_rpc_server::fill_transfer_entry(tools::wallet_rpc::transfer_entry &entry, const crypto::hash &payment_id, const tools::wallet2::payment_details &pd)
+  void wallet_rpc_server::fill_transfer_entry(tools::wallet_rpc::transfer_entry &entry, const crypto::hash &payment_id, const tools::wallet2::pool_payment_details &ppd)
   {
+    const tools::wallet2::payment_details &pd = ppd.m_pd;
     entry.txid = string_tools::pod_to_hex(pd.m_tx_hash);
     entry.payment_id = string_tools::pod_to_hex(payment_id);
     if (entry.payment_id.substr(16).find_first_not_of('0') == std::string::npos)
@@ -311,6 +312,7 @@ namespace tools
     entry.unlock_time = pd.m_unlock_time;
     entry.fee = 0; // TODO
     entry.note = m_wallet->get_tx_note(pd.m_tx_hash);
+    entry.double_spend_seen = ppd.m_double_spend_seen;
     entry.type = "pool";
     entry.subaddr_index = pd.m_subaddr_index;
   }
@@ -1357,9 +1359,9 @@ namespace tools
     {
       m_wallet->update_pool_state();
 
-      std::list<std::pair<crypto::hash, tools::wallet2::payment_details>> payments;
+      std::list<std::pair<crypto::hash, tools::wallet2::pool_payment_details>> payments;
       m_wallet->get_unconfirmed_payments(payments, req.account_index, req.subaddr_indices);
-      for (std::list<std::pair<crypto::hash, tools::wallet2::payment_details>>::const_iterator i = payments.begin(); i != payments.end(); ++i) {
+      for (std::list<std::pair<crypto::hash, tools::wallet2::pool_payment_details>>::const_iterator i = payments.begin(); i != payments.end(); ++i) {
         res.pool.push_back(wallet_rpc::transfer_entry());
         fill_transfer_entry(res.pool.back(), i->first, i->second);
       }
@@ -1430,10 +1432,10 @@ namespace tools
 
     m_wallet->update_pool_state();
 
-    std::list<std::pair<crypto::hash, tools::wallet2::payment_details>> pool_payments;
+    std::list<std::pair<crypto::hash, tools::wallet2::pool_payment_details>> pool_payments;
     m_wallet->get_unconfirmed_payments(pool_payments);
-    for (std::list<std::pair<crypto::hash, tools::wallet2::payment_details>>::const_iterator i = pool_payments.begin(); i != pool_payments.end(); ++i) {
+    for (std::list<std::pair<crypto::hash, tools::wallet2::pool_payment_details>>::const_iterator i = pool_payments.begin(); i != pool_payments.end(); ++i) {
-      if (i->second.m_tx_hash == txid)
+      if (i->second.m_pd.m_tx_hash == txid)
       {
         fill_transfer_entry(res.transfer, i->first, i->second);
         return true;

src/wallet/wallet_rpc_server.h

@@ -163,7 +163,7 @@ namespace tools
       void fill_transfer_entry(tools::wallet_rpc::transfer_entry &entry, const crypto::hash &txid, const crypto::hash &payment_id, const tools::wallet2::payment_details &pd);
       void fill_transfer_entry(tools::wallet_rpc::transfer_entry &entry, const crypto::hash &txid, const tools::wallet2::confirmed_transfer_details &pd);
       void fill_transfer_entry(tools::wallet_rpc::transfer_entry &entry, const crypto::hash &txid, const tools::wallet2::unconfirmed_transfer_details &pd);
-      void fill_transfer_entry(tools::wallet_rpc::transfer_entry &entry, const crypto::hash &payment_id, const tools::wallet2::payment_details &pd);
+      void fill_transfer_entry(tools::wallet_rpc::transfer_entry &entry, const crypto::hash &payment_id, const tools::wallet2::pool_payment_details &pd);
       bool not_open(epee::json_rpc::error& er);
       uint64_t adjust_mixin(uint64_t mixin);
       void handle_rpc_exception(const std::exception_ptr& e, epee::json_rpc::error& er, int default_error_code);

src/wallet/wallet_rpc_server_commands_defs.h

@@ -794,6 +794,7 @@ namespace wallet_rpc
     std::string type;
     uint64_t unlock_time;
     cryptonote::subaddress_index subaddr_index;
+    bool double_spend_seen;
 
     BEGIN_KV_SERIALIZE_MAP()
       KV_SERIALIZE(txid);
@@ -807,6 +808,7 @@ namespace wallet_rpc
       KV_SERIALIZE(type);
       KV_SERIALIZE(unlock_time)
       KV_SERIALIZE(subaddr_index);
+      KV_SERIALIZE(double_spend_seen)
     END_KV_SERIALIZE_MAP()
   };