wallet: adds rescan_bc option with preserving key images

- enables to perform rescan_spent / ki sync with untrusted daemon. Spent check status involves RPC calls which require trusted daemon status as it leaks information. The new call performs soft reset while preserving key images thus a sequence: refresh, ki sync / import, rescan_bc keep_ki will correctly perform spent checking without need for trusted daemon.

- useful to detect spent outputs with untrusted daemon on watch_only / multisig / hw-cold wallets after expensive key image sync.

- cli: rescan_bc keep_ki

src/simplewallet/simplewallet.cpp

@@ -190,7 +190,7 @@ namespace
   const char* USAGE_CHECK_RESERVE_PROOF("check_reserve_proof <address> <signature_file> [<message>]");
   const char* USAGE_SHOW_TRANSFERS("show_transfers [in|out|pending|failed|pool|coinbase] [index=<N1>[,<N2>,...]] [<min_height> [<max_height>]]");
   const char* USAGE_UNSPENT_OUTPUTS("unspent_outputs [index=<N1>[,<N2>,...]] [<min_amount> [<max_amount>]]");
-  const char* USAGE_RESCAN_BC("rescan_bc [hard]");
+  const char* USAGE_RESCAN_BC("rescan_bc [hard|soft|keep_ki] [start_height=0]");
   const char* USAGE_SET_TX_NOTE("set_tx_note <txid> [free text note]");
   const char* USAGE_GET_TX_NOTE("get_tx_note <txid>");
   const char* USAGE_GET_DESCRIPTION("get_description");
@@ -4748,8 +4748,16 @@ bool simple_wallet::refresh_main(uint64_t start_height, enum ResetType reset, bo
 
   LOCK_IDLE_SCOPE();
 
+  crypto::hash transfer_hash_pre{};
+  uint64_t height_pre, height_post;
+
   if (reset != ResetNone)
-    m_wallet->rescan_blockchain(reset == ResetHard, false);
+  {
+    if (reset == ResetSoftKeepKI)
+      height_pre = m_wallet->hash_m_transfers(-1, transfer_hash_pre);
+
+    m_wallet->rescan_blockchain(reset == ResetHard, false, reset == ResetSoftKeepKI);
+  }
 
 #ifdef HAVE_READLINE
   rdln::suspend_readline pause_readline;
@@ -4766,6 +4774,18 @@ bool simple_wallet::refresh_main(uint64_t start_height, enum ResetType reset, bo
     m_in_manual_refresh.store(true, std::memory_order_relaxed);
     epee::misc_utils::auto_scope_leave_caller scope_exit_handler = epee::misc_utils::create_scope_leave_handler([&](){m_in_manual_refresh.store(false, std::memory_order_relaxed);});
     m_wallet->refresh(m_wallet->is_trusted_daemon(), start_height, fetched_blocks, received_money);
+
+    if (reset == ResetSoftKeepKI)
+    {
+      m_wallet->finish_rescan_bc_keep_key_images(height_pre, transfer_hash_pre);
+
+      height_post = m_wallet->get_num_transfer_details();
+      if (height_pre != height_post)
+      {
+        message_writer() << tr("New transfer received since rescan was started. Key images are incomplete.");
+      }
+    }
+
     ok = true;
     // Clear line "Height xxx of xxx"
     std::cout << "\r                                                                \r";
@@ -7773,18 +7793,43 @@ bool simple_wallet::unspent_outputs(const std::vector<std::string> &args_)
 //----------------------------------------------------------------------------------------------------
 bool simple_wallet::rescan_blockchain(const std::vector<std::string> &args_)
 {
-  bool hard = false;
+  uint64_t start_height = 0;
+  ResetType reset_type = ResetSoft;
+
   if (!args_.empty())
   {
-    if (args_[0] != "hard")
+    if (args_[0] == "hard")
+    {
+      reset_type = ResetHard;
+    }
+    else if (args_[0] == "soft")
+    {
+      reset_type = ResetSoft;
+    }
+    else if (args_[0] == "keep_ki")
+    {
+      reset_type = ResetSoftKeepKI;
+    }
+    else
     {
       PRINT_USAGE(USAGE_RESCAN_BC);
       return true;
     }
-    hard = true;
+
+    if (args_.size() > 1)
+    {
+      try
+      {
+        start_height = boost::lexical_cast<uint64_t>( args_[1] );
+      }
+      catch(const boost::bad_lexical_cast &)
+      {
+        start_height = 0;
+      }
+    }
   }
 
-  if (hard)
+  if (reset_type == ResetHard)
   {
     message_writer() << tr("Warning: this will lose any information which can not be recovered from the blockchain.");
     message_writer() << tr("This includes destination addresses, tx secret keys, tx notes, etc");
@@ -7795,7 +7840,20 @@ bool simple_wallet::rescan_blockchain(const std::vector<std::string> &args_)
         return true;
     }
   }
-  return refresh_main(0, hard ? ResetHard : ResetSoft, true);
+
+  const uint64_t wallet_from_height = m_wallet->get_refresh_from_block_height();
+  if (start_height > wallet_from_height)
+  {
+    message_writer() << tr("Warning: your restore height is higher than wallet restore height: ") << wallet_from_height;
+    std::string confirm = input_line(tr("Rescan anyway ? (Y/Yes/N/No): "));
+    if(!std::cin.eof())
+    {
+      if (!command_line::is_yes(confirm))
+        return true;
+    }
+  }
+
+  return refresh_main(start_height, reset_type, true);
 }
 //----------------------------------------------------------------------------------------------------
 void simple_wallet::check_for_messages()

src/simplewallet/simplewallet.h

@@ -84,7 +84,7 @@ namespace cryptonote
     std::string get_command_usage(const std::vector<std::string> &args);
   private:
 
-    enum ResetType { ResetNone, ResetSoft, ResetHard };
+    enum ResetType { ResetNone, ResetSoft, ResetHard, ResetSoftKeepKI };
 
     bool handle_command_line(const boost::program_options::variables_map& vm);
 

src/wallet/wallet2.cpp

@@ -3223,6 +3223,26 @@ bool wallet2::clear()
   m_device_last_key_image_sync = 0;
   return true;
 }
+//----------------------------------------------------------------------------------------------------
+void wallet2::clear_soft(bool keep_key_images)
+{
+  m_blockchain.clear();
+  m_transfers.clear();
+  if (!keep_key_images)
+    m_key_images.clear();
+  m_pub_keys.clear();
+  m_unconfirmed_txs.clear();
+  m_payments.clear();
+  m_confirmed_txs.clear();
+  m_unconfirmed_payments.clear();
+  m_scanned_pool_txs[0].clear();
+  m_scanned_pool_txs[1].clear();
+
+  cryptonote::block b;
+  generate_genesis(b);
+  m_blockchain.push_back(get_block_hash(b));
+  m_last_block_reward = cryptonote::get_outs_money_amount(b.miner_tx);
+}
 
 /*!
  * \brief Stores wallet information to wallet file.
@@ -5469,8 +5489,12 @@ void wallet2::rescan_spent()
   }
 }
 //----------------------------------------------------------------------------------------------------
-void wallet2::rescan_blockchain(bool hard, bool refresh)
+void wallet2::rescan_blockchain(bool hard, bool refresh, bool keep_key_images)
 {
+  CHECK_AND_ASSERT_THROW_MES(!hard || !keep_key_images, "Cannot preserve key images on hard rescan");
+  const size_t transfers_cnt = m_transfers.size();
+  crypto::hash transfers_hash{};
+
   if(hard)
   {
     clear();
@@ -5478,25 +5502,16 @@ void wallet2::rescan_blockchain(bool hard, bool refresh)
   }
   else
   {
-    m_blockchain.clear();
-    m_transfers.clear();
-    m_key_images.clear();
-    m_pub_keys.clear();
-    m_unconfirmed_txs.clear();
-    m_payments.clear();
-    m_confirmed_txs.clear();
-    m_unconfirmed_payments.clear();
-    m_scanned_pool_txs[0].clear();
-    m_scanned_pool_txs[1].clear();
-
-    cryptonote::block b;
-    generate_genesis(b);
-    m_blockchain.push_back(get_block_hash(b));
-    m_last_block_reward = cryptonote::get_outs_money_amount(b.miner_tx);
+    if (keep_key_images && refresh)
+      hash_m_transfers((int64_t) transfers_cnt, transfers_hash);
+    clear_soft(keep_key_images);
   }
 
   if (refresh)
     this->refresh(false);
+
+  if (refresh && keep_key_images)
+    finish_rescan_bc_keep_key_images(transfers_cnt, transfers_hash);
 }
 //----------------------------------------------------------------------------------------------------
 bool wallet2::is_transfer_unlocked(const transfer_details& td) const
@@ -11392,6 +11407,7 @@ uint64_t wallet2::import_key_images(const std::vector<std::pair<crypto::key_imag
         auto it = m_key_images.find(boost::get<cryptonote::txin_to_key>(in).k_image);
         if (it != m_key_images.end())
         {
+          THROW_WALLET_EXCEPTION_IF(it->second >= m_transfers.size(), error::wallet_internal_error, std::string("Key images cache contains illegal transfer offset: ") + std::to_string(it->second) + std::string(" m_transfers.size() = ") + std::to_string(m_transfers.size()));
           const transfer_details& td = m_transfers[it->second];
           uint64_t amount = boost::get<cryptonote::txin_to_key>(in).amount;
           if (amount > 0)
@@ -12490,5 +12506,61 @@ void wallet2::throw_on_rpc_response_error(const boost::optional<std::string> &st
   THROW_WALLET_EXCEPTION_IF(*status == CORE_RPC_STATUS_BUSY, tools::error::daemon_busy, method);
   THROW_WALLET_EXCEPTION_IF(*status != CORE_RPC_STATUS_OK, tools::error::wallet_generic_rpc_error, method, m_trusted_daemon ? *status : "daemon error");
 }
-
+//----------------------------------------------------------------------------------------------------
+void wallet2::hash_m_transfer(const transfer_details & transfer, crypto::hash &hash) const
+{
+  KECCAK_CTX state;
+  keccak_init(&state);
+  keccak_update(&state, (const uint8_t *) transfer.m_txid.data, sizeof(transfer.m_txid.data));
+  keccak_update(&state, (const uint8_t *) transfer.m_internal_output_index, sizeof(transfer.m_internal_output_index));
+  keccak_update(&state, (const uint8_t *) transfer.m_global_output_index, sizeof(transfer.m_global_output_index));
+  keccak_update(&state, (const uint8_t *) transfer.m_amount, sizeof(transfer.m_amount));
+  keccak_finish(&state, (uint8_t *) hash.data);
+}
+//----------------------------------------------------------------------------------------------------
+uint64_t wallet2::hash_m_transfers(int64_t transfer_height, crypto::hash &hash) const
+{
+  CHECK_AND_ASSERT_THROW_MES(transfer_height > (int64_t)m_transfers.size(), "Hash height is greater than number of transfers");
+
+  KECCAK_CTX state;
+  crypto::hash tmp_hash{};
+  uint64_t current_height = 0;
+
+  keccak_init(&state);
+  for(const transfer_details & transfer : m_transfers){
+    if (transfer_height >= 0 && current_height >= (uint64_t)transfer_height){
+      break;
+    }
+
+    hash_m_transfer(transfer, tmp_hash);
+    keccak_update(&state, (const uint8_t *) transfer.m_block_height, sizeof(transfer.m_block_height));
+    keccak_update(&state, (const uint8_t *) tmp_hash.data, sizeof(tmp_hash.data));
+    current_height += 1;
+  }
+
+  keccak_finish(&state, (uint8_t *) hash.data);
+  return current_height;
+}
+//----------------------------------------------------------------------------------------------------
+void wallet2::finish_rescan_bc_keep_key_images(uint64_t transfer_height, const crypto::hash &hash)
+{
+  // Compute hash of m_transfers, if differs there had to be BC reorg.
+  crypto::hash new_transfers_hash{};
+  hash_m_transfers((int64_t) transfer_height, new_transfers_hash);
+
+  if (new_transfers_hash != hash)
+  {
+    // Soft-Reset to avoid inconsistency in case of BC reorg.
+    clear_soft(false);  // keep_key_images works only with soft reset.
+    THROW_WALLET_EXCEPTION_IF(true, error::wallet_internal_error, "Transfers changed during rescan, soft or hard rescan is needed");
+  }
+
+  // Restore key images in m_transfers from m_key_images
+  for(auto it = m_key_images.begin(); it != m_key_images.end(); it++)
+  {
+    THROW_WALLET_EXCEPTION_IF(it->second >= m_transfers.size(), error::wallet_internal_error, "Key images cache contains illegal transfer offset");
+    m_transfers[it->second].m_key_image = it->first;
+    m_transfers[it->second].m_key_image_known = true;
+  }
+}
 }

src/wallet/wallet2.h

@@ -818,7 +818,7 @@ namespace tools
 
     uint64_t get_blockchain_current_height() const { return m_light_wallet_blockchain_height ? m_light_wallet_blockchain_height : m_blockchain.size(); }
     void rescan_spent();
-    void rescan_blockchain(bool hard, bool refresh = true);
+    void rescan_blockchain(bool hard, bool refresh = true, bool keep_key_images = false);
     bool is_transfer_unlocked(const transfer_details& td) const;
     bool is_transfer_unlocked(uint64_t unlock_time, uint64_t block_height) const;
 
@@ -1248,6 +1248,9 @@ namespace tools
     void set_tx_notify(const std::shared_ptr<tools::Notify> &notify) { m_tx_notify = notify; }
 
     bool is_tx_spendtime_unlocked(uint64_t unlock_time, uint64_t block_height) const;
+    void hash_m_transfer(const transfer_details & transfer, crypto::hash &hash) const;
+    uint64_t hash_m_transfers(int64_t transfer_height, crypto::hash &hash) const;
+    void finish_rescan_bc_keep_key_images(uint64_t transfer_height, const crypto::hash &hash);
 
   private:
     /*!
@@ -1269,6 +1272,7 @@ namespace tools
     void detach_blockchain(uint64_t height);
     void get_short_chain_history(std::list<crypto::hash>& ids, uint64_t granularity = 1) const;
     bool clear();
+    void clear_soft(bool keep_key_images=false);
     void pull_blocks(uint64_t start_height, uint64_t& blocks_start_height, const std::list<crypto::hash> &short_chain_history, std::vector<cryptonote::block_complete_entry> &blocks, std::vector<cryptonote::COMMAND_RPC_GET_BLOCKS_FAST::block_output_indices> &o_indices);
     void pull_hashes(uint64_t start_height, uint64_t& blocks_start_height, const std::list<crypto::hash> &short_chain_history, std::vector<crypto::hash> &hashes);
     void fast_refresh(uint64_t stop_height, uint64_t &blocks_start_height, std::list<crypto::hash> &short_chain_history, bool force = false);