Add a --restricted-rpc flag to simplewallet

It restricts RPC to a subset of "view only" commands. Kind of like
a poor man's view key replacement.

src/simplewallet/simplewallet.cpp

@@ -81,6 +81,7 @@ namespace
   const command_line::arg_descriptor<int> arg_daemon_port = {"daemon-port", "Use daemon instance at port <arg> instead of 8081", 0};
   const command_line::arg_descriptor<uint32_t> arg_log_level = {"set_log", "", 0, true};
   const command_line::arg_descriptor<bool> arg_testnet = {"testnet", "Used to deploy test nets. The daemon must be launched with --testnet flag", false};
+  const command_line::arg_descriptor<bool> arg_restricted = {"restricted-rpc", "Restricts RPC to view only commands", false};
 
   const command_line::arg_descriptor< std::vector<std::string> > arg_command = {"command", ""};
 
@@ -1336,6 +1337,7 @@ int main(int argc, char* argv[])
   command_line::add_arg(desc_params, arg_non_deterministic );
   command_line::add_arg(desc_params, arg_electrum_seed );
   command_line::add_arg(desc_params, arg_testnet);
+  command_line::add_arg(desc_params, arg_restricted);
   tools::wallet_rpc_server::init_options(desc_params);
 
   po::positional_options_description positional_options;
@@ -1406,6 +1408,7 @@ int main(int argc, char* argv[])
     }
 
     bool testnet = command_line::get_arg(vm, arg_testnet);
+    bool restricted = command_line::get_arg(vm, arg_restricted);
     std::string wallet_file     = command_line::get_arg(vm, arg_wallet_file);
     std::string wallet_password = command_line::get_arg(vm, arg_password);
     std::string daemon_address  = command_line::get_arg(vm, arg_daemon_address);
@@ -1418,7 +1421,7 @@ int main(int argc, char* argv[])
     if (daemon_address.empty())
       daemon_address = std::string("http://") + daemon_host + ":" + std::to_string(daemon_port);
 
-    tools::wallet2 wal(testnet);
+    tools::wallet2 wal(testnet,restricted);
     try
     {
       LOG_PRINT_L0("Loading wallet...");

src/wallet/wallet2.h

@@ -82,7 +82,7 @@ namespace tools
   {
     wallet2(const wallet2&) : m_run(true), m_callback(0), m_testnet(false) {};
   public:
-    wallet2(bool testnet = false) : m_run(true), m_callback(0), m_testnet(testnet), is_old_file_format(false) {};
+    wallet2(bool testnet = false, bool restricted = false) : m_run(true), m_callback(0), m_testnet(testnet), m_restricted(restricted), is_old_file_format(false) {};
     struct transfer_details
     {
       uint64_t m_block_height;
@@ -196,6 +196,7 @@ namespace tools
     bool refresh(size_t & blocks_fetched, bool& received_money, bool& ok);
 
     bool testnet() { return m_testnet; }
+    bool restricted() const { return m_restricted; }
 
     uint64_t balance();
     uint64_t unlocked_balance();
@@ -296,6 +297,7 @@ namespace tools
 
     i_wallet2_callback* m_callback;
     bool m_testnet;
+    bool m_restricted;
     std::string seed_language; /*!< Language of the mnemonics (seed). */
     bool is_old_file_format; /*!< Whether the wallet file is of an old file format */
   };

src/wallet/wallet_rpc_server.cpp

@@ -167,6 +167,13 @@ namespace tools
     std::vector<cryptonote::tx_destination_entry> dsts;
     std::vector<uint8_t> extra;
 
+    if (m_wallet.restricted())
+    {
+      er.code = WALLET_RPC_ERROR_CODE_DENIED;
+      er.message = "Command unavailable in restricted mode.";
+      return false;
+    }
+
     // validate the transfer requested and populate dsts & extra
     if (!validate_transfer(req.destinations, req.payment_id, dsts, extra, er))
     {
@@ -218,6 +225,13 @@ namespace tools
     std::vector<cryptonote::tx_destination_entry> dsts;
     std::vector<uint8_t> extra;
 
+    if (m_wallet.restricted())
+    {
+      er.code = WALLET_RPC_ERROR_CODE_DENIED;
+      er.message = "Command unavailable in restricted mode.";
+      return false;
+    }
+
     // validate the transfer requested and populate dsts & extra; RPC_TRANSFER::request and RPC_TRANSFER_SPLIT::request are identical types.
     if (!validate_transfer(req.destinations, req.payment_id, dsts, extra, er))
     {
@@ -261,6 +275,13 @@ namespace tools
   //------------------------------------------------------------------------------------------------------------------------------
   bool wallet_rpc_server::on_store(const wallet_rpc::COMMAND_RPC_STORE::request& req, wallet_rpc::COMMAND_RPC_STORE::response& res, epee::json_rpc::error& er, connection_context& cntx)
   {
+    if (m_wallet.restricted())
+    {
+      er.code = WALLET_RPC_ERROR_CODE_DENIED;
+      er.message = "Command unavailable in restricted mode.";
+      return false;
+    }
+
     try
     {
       m_wallet.store();
@@ -409,6 +430,13 @@ namespace tools
   //------------------------------------------------------------------------------------------------------------------------------
   bool wallet_rpc_server::on_query_key(const wallet_rpc::COMMAND_RPC_QUERY_KEY::request& req, wallet_rpc::COMMAND_RPC_QUERY_KEY::response& res, epee::json_rpc::error& er, connection_context& cntx)
   {
+      if (m_wallet.restricted())
+      {
+        er.code = WALLET_RPC_ERROR_CODE_DENIED;
+        er.message = "Command unavailable in restricted mode.";
+        return false;
+      }
+
       if (req.key_type.compare("mnemonic") == 0)
       {
         if (!m_wallet.get_seed(res.key))

src/wallet/wallet_rpc_server_error_codes.h

@@ -37,3 +37,4 @@
 #define WALLET_RPC_ERROR_CODE_GENERIC_TRANSFER_ERROR  -4
 #define WALLET_RPC_ERROR_CODE_WRONG_PAYMENT_ID        -5
 #define WALLET_RPC_ERROR_CODE_TRANSFER_TYPE           -6
+#define WALLET_RPC_ERROR_CODE_DENIED                  -7