Adding "light wallet server" that is mymonero compatible:

      - An epee-based HTTP server that polls in the background for new txes
      - Admin utility for inspecting state, manipulating some account info,
        and approving account creation/imports
      - Optional (off by default) exchange rate retrieval from
        cryptocompare.com

contrib/epee/include/net/http_protocol_handler.h

@@ -57,6 +57,7 @@ namespace net_utils
 			std::vector<std::string> m_access_control_origins;
 			boost::optional<login> m_user;
 			critical_section m_lock;
+			bool m_access_control_credentials;
 		};
 
 		/************************************************************************/

contrib/epee/include/net/http_protocol_handler.inl

@@ -678,6 +678,9 @@ namespace net_utils
 					buf += "Access-Control-Allow-Headers: Content-Type, Authorization, X-Requested-With\r\n";
 				buf += "Access-Control-Allow-Methods: POST, PUT, GET, OPTIONS\r\n";
 			}
+
+			if (m_config.m_access_control_credentials)
+				buf += "Access-Control-Allow-Credentials: true\r\n";
 		}
 
 		//add additional fields, if it is

contrib/epee/include/net/http_server_impl_base.h

@@ -48,13 +48,19 @@ namespace epee
   {
 
   public:
-    http_server_impl_base()
+    //! allow_credentials => adds HTTP Cors header `Access-Control-Allow-Credentials: true`, use carefully
+    http_server_impl_base(bool allow_credentials = false)
         : m_net_server(epee::net_utils::e_connection_type_RPC)
-    {}
+    {
+        m_net_server.get_config_object().m_access_control_credentials = allow_credentials;
+    }
 
-    explicit http_server_impl_base(boost::asio::io_service& external_io_service)
-        : m_net_server(external_io_service)
-    {}
+    //! allow_credentials => adds HTTP Cors header `Access-Control-Allow-Credentials: true`, use carefully
+    explicit http_server_impl_base(boost::asio::io_service& external_io_service, bool allow_credentials = false)
+        : m_net_server(external_io_service, net_utils::e_connection_type_RPC)
+    {
+      m_net_server.get_config_object().m_access_control_credentials = allow_credentials;
+    }
 
     bool init(std::function<void(size_t, uint8_t*)> rng, const std::string& bind_port = "0", const std::string& bind_ip = "0.0.0.0",
       const std::string& bind_ipv6_address = "::", bool use_ipv6 = false, bool require_ipv4 = true,

contrib/epee/include/net/net_helper.h

@@ -33,6 +33,7 @@
 //#include <Ws2tcpip.h>
 #include <atomic>
 #include <string>
+#include <atomic>
 #include <boost/version.hpp>
 #include <boost/asio/io_service.hpp>
 #include <boost/asio/ip/tcp.hpp>

src/CMakeLists.txt

@@ -122,6 +122,7 @@ if(NOT IOS)
   add_subdirectory(serialization)
 endif()
 add_subdirectory(wallet)
+add_subdirectory(light_wallet_server)
 if(NOT IOS)
   add_subdirectory(p2p)
 endif()

src/common/download.cpp

@@ -101,7 +101,7 @@ namespace tools
         {
           for (const auto &kv: headers.m_header_info.m_etc_fields)
             MDEBUG("Header: " << kv.first << ": " << kv.second);
-          ssize_t length;
+          ssize_t length = 0;
           if (epee::string_tools::get_xtype_from_string(length, headers.m_header_info.m_content_length) && length >= 0)
           {
             MINFO("Content-Length: " << length);

src/common/error.cpp

@@ -41,6 +41,10 @@ namespace
         {
             switch (common_error(value))
             {
+                case common_error::configuration:
+                    return "Invalid process configuration";
+                case common_error::crypto_failure:
+                    return "A cryptographic function failed";
                 case common_error::kInvalidArgument:
                     return make_error_code(std::errc::invalid_argument).message();
                 case common_error::kInvalidErrorCode:

src/common/error.h

@@ -32,8 +32,10 @@
 enum class common_error : int
 {
     // 0 is reserved for no error, as per expect<T>
-    kInvalidArgument = 1, //!< A function argument is invalid
-    kInvalidErrorCode     //!< Default `std::error_code` given to `expect<T>`
+    configuration = 1, //!< Process configuration failure
+    crypto_failure,    //<! A `crypto::` function failed.
+    kInvalidArgument,  //!< A function argument is invalid
+    kInvalidErrorCode, //!< Default `std::error_code` given to `expect<T>`
 };
 
 std::error_category const& common_category() noexcept;

src/crypto/crypto.cpp

@@ -69,9 +69,6 @@ namespace crypto {
 #include "random.h"
   }
 
-  const crypto::public_key null_pkey = crypto::public_key{};
-  const crypto::secret_key null_skey = crypto::secret_key{};
-
   static inline unsigned char *operator &(ec_point &point) {
     return &reinterpret_cast<unsigned char &>(point);
   }

src/crypto/crypto.h

@@ -96,6 +96,12 @@ namespace crypto {
   };
 #pragma pack(pop)
 
+  template<typename T>
+  struct null_key
+  {
+    operator T() const { return T{}; }
+  };
+
   void hash_to_scalar(const void *data, size_t length, ec_scalar &res);
   void random32_unbiased(unsigned char *bytes);
 
@@ -303,8 +309,8 @@ namespace crypto {
     epee::to_hex::formatted(o, epee::as_byte_span(v)); return o;
   }
 
-  const extern crypto::public_key null_pkey;
-  const extern crypto::secret_key null_skey;
+  constexpr const null_key<public_key> null_pkey{};
+  constexpr const null_key<secret_key> null_skey{};
 }
 
 CRYPTO_MAKE_HASHABLE(public_key)

src/cryptonote_core/cryptonote_tx_utils.cpp

@@ -177,6 +177,21 @@ namespace cryptonote
     return true;
   }
   //---------------------------------------------------------------
+  boost::optional<std::pair<uint64_t, rct::key>> decode_amount(const rct::key& commitment, const rct::ecdhTuple& info, const crypto::key_derivation& sk, std::size_t index, const bool bulletproof2)
+  {
+    crypto::secret_key scalar{};
+    crypto::derivation_to_scalar(sk, index, scalar);
+
+    rct::ecdhTuple copy{info};
+    rct::ecdhDecode(copy, rct::sk2rct(scalar), bulletproof2);
+
+    rct::key Ctmp;
+    rct::addKeys2(Ctmp, copy.mask, copy.amount, rct::H);
+    if (rct::equalKeys(commitment, Ctmp))
+      return {{rct::h2d(copy.amount), copy.mask}};
+    return boost::none;
+  }
+  //---------------------------------------------------------------
   crypto::public_key get_destination_view_key_pub(const std::vector<tx_destination_entry> &destinations, const boost::optional<cryptonote::account_public_address>& change_addr)
   {
     account_public_address addr = {null_pkey, null_pkey};

src/cryptonote_core/cryptonote_tx_utils.h

@@ -29,10 +29,13 @@
 // Parts of this file are originally copyright (c) 2012-2013 The Cryptonote developers
 
 #pragma once
+#include "crypto/hash.h"
 #include "cryptonote_basic/cryptonote_format_utils.h"
+#include <boost/optional/optional.hpp>
 #include <boost/serialization/vector.hpp>
 #include <boost/serialization/utility.hpp>
 #include "ringct/rctOps.h"
+#include "ringct/rctTypes.h"
 
 namespace cryptonote
 {
@@ -108,6 +111,7 @@ namespace cryptonote
   };
 
   //---------------------------------------------------------------
+  boost::optional<std::pair<uint64_t, rct::key>> decode_amount(const rct::key &commitment, const rct::ecdhTuple &info, const crypto::key_derivation &sk, size_t index, bool bulletproof2);
   crypto::public_key get_destination_view_key_pub(const std::vector<tx_destination_entry> &destinations, const boost::optional<cryptonote::account_public_address>& change_addr);
   bool construct_tx(const account_keys& sender_account_keys, std::vector<tx_source_entry> &sources, const std::vector<tx_destination_entry>& destinations, const boost::optional<cryptonote::account_public_address>& change_addr, const std::vector<uint8_t> &extra, transaction& tx, uint64_t unlock_time);
   bool construct_tx_with_tx_key(const account_keys& sender_account_keys, const std::unordered_map<crypto::public_key, subaddress_index>& subaddresses, std::vector<tx_source_entry>& sources, std::vector<tx_destination_entry>& destinations, const boost::optional<cryptonote::account_public_address>& change_addr, const std::vector<uint8_t> &extra, transaction& tx, uint64_t unlock_time, const crypto::secret_key &tx_key, const std::vector<crypto::secret_key> &additional_tx_keys, bool rct = false, const rct::RCTConfig &rct_config = { rct::RangeProofBorromean, 0 }, rct::multisig_out *msout = NULL, bool shuffle_outs = true);

src/device/device_default.cpp

@@ -43,6 +43,18 @@
 namespace hw {
 
     namespace core {
+        void device_default::do_encrypt_payment_id(crypto::hash8& out, const crypto::key_derivation& key)
+        {
+            crypto::hash hash;
+            char data[33]; /* A hash, and an extra byte */
+
+            memcpy(data, &key, 32);
+            data[32] = ENCRYPTED_PAYMENT_ID_TAIL;
+            cn_fast_hash(data, 33, hash);
+
+            for (size_t b = 0; b < 8; ++b)
+                out.data[b] ^= hash.data[b];
+        }
 
         device_default::device_default() { }
 
@@ -337,19 +349,10 @@ namespace hw {
 
         bool  device_default::encrypt_payment_id(crypto::hash8 &payment_id, const crypto::public_key &public_key, const crypto::secret_key &secret_key) {
             crypto::key_derivation derivation;
-            crypto::hash hash;
-            char data[33]; /* A hash, and an extra byte */
-
             if (!generate_key_derivation(public_key, secret_key, derivation))
                 return false;
 
-            memcpy(data, &derivation, 32);
-            data[32] = ENCRYPTED_PAYMENT_ID_TAIL;
-            cn_fast_hash(data, 33, hash);
-
-            for (size_t b = 0; b < 8; ++b)
-                payment_id.data[b] ^= hash.data[b];
-
+            do_encrypt_payment_id(payment_id, derivation);
             return true;
         }
 

src/device/device_default.hpp

@@ -39,6 +39,18 @@ namespace hw {
 
         class device_default : public hw::device {
         public:
+            /*! \TODO These 2 functions, and a few others should be elsewhere.
+                Unfortunately, "cryptonote_core", "ringct", and "wallet"
+                libraries all depend on the device library creating a cyclic
+                dependency. None of those libraries should be dependent on
+                the hardware abstraction, it should only be dependent on them.
+            */
+            static void do_encrypt_payment_id(crypto::hash8& out, crypto::key_derivation const& key);
+            static void do_decrypt_payment_id(crypto::hash8& out, crypto::key_derivation const& key)
+            {
+                do_encrypt_payment_id(out, key);
+            }
+
             device_default();
             ~device_default();
 

src/light_wallet_server/CMakeLists.txt

@@ -0,0 +1,58 @@
+
+add_subdirectory(db)
+
+# For both the server and admin utility.
+set(lws_common_sources config.cpp error.cpp json.cpp)
+set(lws_common_headers config.h error.h fwd.h json.h)
+
+monero_add_library(light_wallet_server-common ${lws_common_sources} ${lws_common_headers})
+target_link_libraries(light_wallet_server-common common serialization-new)
+
+# Only used by server (not admin). For utilities that are unit tested
+set(lws_lib_sources random_outputs.cpp)
+set(lws_lib_headers random_outputs.h)
+
+monero_add_library(light_wallet_server-lib ${lws_lib_sources} ${lws_lib_headers})
+target_link_libraries(light_wallet_server-lib light_wallet_server-common wallet)
+
+monero_add_executable(light_wallet_server server_main.cpp rates.cpp rest_server.cpp rpc.cpp scanner.cpp)
+target_include_directories(light_wallet_server PUBLIC ${ZMQ_INCLUDE_PATH})
+target_link_libraries(light_wallet_server
+  PRIVATE
+    cryptonote_core
+    cncrypto
+    common
+    daemon_messages
+    device
+    epee
+    light_wallet_server-common
+    light_wallet_server-db
+    light_wallet_server-lib
+    lmdb_lib
+    daemon_messages
+    ${Boost_CHRONO_LIBRARY}
+    ${Boost_FILESYSTEM_LIBRARY}
+    ${Boost_PROGRAM_OPTIONS_LIBRARY}
+    ${Boost_THREAD_LIBRARY}
+    ${CMAKE_THREAD_LIBS_INIT}
+    ${EXTRA_LIBRARIES}
+    ${ZMQ_LIB}
+)
+set_property(TARGET light_wallet_server PROPERTY OUTPUT_NAME "monero-light-wallet-server")
+
+monero_add_executable(light_wallet_server_admin admin_main.cpp)
+target_link_libraries(light_wallet_server_admin
+  PRIVATE
+    cryptonote_core
+    cncrypto
+    common
+    light_wallet_server-common
+    light_wallet_server-db
+    serialization-new
+    ${Boost_PROGRAM_OPTIONS_LIBRARY}
+    ${EXTRA_LIBRARIES}
+)
+set_property(TARGET light_wallet_server_admin PROPERTY OUTPUT_NAME "monero-light-wallet-server-admin")
+
+install(TARGETS light_wallet_server DESTINATION bin)
+install(TARGETS light_wallet_server_admin DESTINATION bin)