Added discord-rpc files

CMakeLists.txt

@@ -22,7 +22,7 @@ option(OPT_BUILD_AUDIO_SINK "Build Audio Sink Module (Depedencies: rtaudio)" ON)
 option(OPT_BUILD_FALCON9_DECODER "Build the falcon9 live decoder (Dependencies: ffplay)" OFF)
 option(OPT_BUILD_METEOR_DEMODULATOR "Build the meteor demodulator module (no dependencies required)" ON)
 option(OPT_BUILD_WEATHER_SAT_DECODER "Build the HRPT decoder module (no dependencies required)" ON)
-option(OPT_BUILD_DISCORD_PRESENCE "Build the Discord Rich Presence module" ON)
+option(OPT_BUILD_DISCORD_PRESENCE "Build the Discord Rich Presence module (Dependencies: rapidjson)" ON)
 # Core of SDR++
 add_subdirectory("core")
 

discord-integration/CMakeLists.txt

@@ -9,13 +9,14 @@ else ()
     set(CMAKE_CXX_FLAGS "-O3 -std=c++17 -fPIC")
 endif ()
 
+add_subdirectory("discord-rpc")
+
 file(GLOB SRC "src/*.cpp")
+include_directories("src/" "discord-rpc/include")
 
-include_directories("src/")
-
-add_library(integration SHARED ${SRC})
-target_link_libraries(integration PUBLIC sdrpp_core discord-rpc)
-set_target_properties(integration PROPERTIES PREFIX "")
+add_library(discord-integration SHARED ${SRC})
+target_link_libraries(discord-integration PUBLIC sdrpp_core discord-rpc)
+set_target_properties(discord-integration PROPERTIES PREFIX "")
 
 # Install directives
-install(TARGETS integration DESTINATION lib/sdrpp/plugins)
+install(TARGETS discord-integration DESTINATION lib/sdrpp/plugins)

discord-integration/discord-rpc/CMakeLists.txt

@@ -0,0 +1,50 @@
+cmake_minimum_required (VERSION 3.2.0)
+project (DiscordRPC)
+
+include(GNUInstallDirs)
+
+# format
+file(GLOB_RECURSE ALL_SOURCE_FILES
+    include/*.h
+    src/*.cpp src/*.h src/*.c
+)
+
+# Set CLANG_FORMAT_SUFFIX if you are using custom clang-format, e.g. clang-format-5.0
+find_program(CLANG_FORMAT_CMD clang-format${CLANG_FORMAT_SUFFIX})
+
+if (CLANG_FORMAT_CMD)
+    add_custom_target(
+        clangformat
+        COMMAND ${CLANG_FORMAT_CMD}
+        -i -style=file -fallback-style=none
+        ${ALL_SOURCE_FILES}
+        DEPENDS
+        ${ALL_SOURCE_FILES}
+    )
+endif(CLANG_FORMAT_CMD)
+
+# thirdparty stuff
+execute_process(
+    COMMAND mkdir ${CMAKE_CURRENT_SOURCE_DIR}/thirdparty
+    ERROR_QUIET
+)
+
+find_file(RAPIDJSONTEST NAMES rapidjson rapidjson-1.1.0 PATHS ${CMAKE_CURRENT_SOURCE_DIR}/thirdparty CMAKE_FIND_ROOT_PATH_BOTH)
+if (NOT RAPIDJSONTEST)
+    message("no rapidjson, download")
+    set(RJ_TAR_FILE ${CMAKE_CURRENT_SOURCE_DIR}/thirdparty/v1.1.0.tar.gz)
+    file(DOWNLOAD https://github.com/miloyip/rapidjson/archive/v1.1.0.tar.gz ${RJ_TAR_FILE})
+    execute_process(
+        COMMAND ${CMAKE_COMMAND} -E tar xzf ${RJ_TAR_FILE}
+        WORKING_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}/thirdparty
+    )
+    file(REMOVE ${RJ_TAR_FILE})
+endif(NOT RAPIDJSONTEST)
+
+find_file(RAPIDJSON NAMES rapidjson rapidjson-1.1.0 PATHS ${CMAKE_CURRENT_SOURCE_DIR}/thirdparty CMAKE_FIND_ROOT_PATH_BOTH)
+
+add_library(rapidjson STATIC IMPORTED ${RAPIDJSON})
+
+# add subdirs
+
+add_subdirectory(src)

discord-integration/discord-rpc/LICENSE

@@ -0,0 +1,19 @@
+Copyright 2017 Discord, Inc.
+
+Permission is hereby granted, free of charge, to any person obtaining a copy of
+this software and associated documentation files (the "Software"), to deal in
+the Software without restriction, including without limitation the rights to
+use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
+of the Software, and to permit persons to whom the Software is furnished to do
+so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

discord-integration/discord-rpc/include/discord_register.h

@@ -0,0 +1,26 @@
+#pragma once
+
+#if defined(DISCORD_DYNAMIC_LIB)
+#if defined(_WIN32)
+#if defined(DISCORD_BUILDING_SDK)
+#define DISCORD_EXPORT __declspec(dllexport)
+#else
+#define DISCORD_EXPORT __declspec(dllimport)
+#endif
+#else
+#define DISCORD_EXPORT __attribute__((visibility("default")))
+#endif
+#else
+#define DISCORD_EXPORT
+#endif
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+DISCORD_EXPORT void Discord_Register(const char* applicationId, const char* command);
+DISCORD_EXPORT void Discord_RegisterSteamGame(const char* applicationId, const char* steamId);
+
+#ifdef __cplusplus
+}
+#endif

discord-integration/discord-rpc/include/discord_rpc.h

@@ -0,0 +1,90 @@
+#pragma once
+#include <stdint.h>
+
+// clang-format off
+
+#if defined(DISCORD_DYNAMIC_LIB)
+#  if defined(_WIN32)
+#    if defined(DISCORD_BUILDING_SDK)
+#      define DISCORD_EXPORT __declspec(dllexport)
+#    else
+#      define DISCORD_EXPORT __declspec(dllimport)
+#    endif
+#  else
+#    define DISCORD_EXPORT __attribute__((visibility("default")))
+#  endif
+#else
+#  define DISCORD_EXPORT
+#endif
+
+// clang-format on
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+typedef struct DiscordRichPresence {
+    const char* state;   /* max 128 bytes */
+    const char* details; /* max 128 bytes */
+    int64_t startTimestamp;
+    int64_t endTimestamp;
+    const char* largeImageKey;  /* max 32 bytes */
+    const char* largeImageText; /* max 128 bytes */
+    const char* smallImageKey;  /* max 32 bytes */
+    const char* smallImageText; /* max 128 bytes */
+    const char* partyId;        /* max 128 bytes */
+    int partySize;
+    int partyMax;
+    int partyPrivacy;
+    const char* matchSecret;    /* max 128 bytes */
+    const char* joinSecret;     /* max 128 bytes */
+    const char* spectateSecret; /* max 128 bytes */
+    int8_t instance;
+} DiscordRichPresence;
+
+typedef struct DiscordUser {
+    const char* userId;
+    const char* username;
+    const char* discriminator;
+    const char* avatar;
+} DiscordUser;
+
+typedef struct DiscordEventHandlers {
+    void (*ready)(const DiscordUser* request);
+    void (*disconnected)(int errorCode, const char* message);
+    void (*errored)(int errorCode, const char* message);
+    void (*joinGame)(const char* joinSecret);
+    void (*spectateGame)(const char* spectateSecret);
+    void (*joinRequest)(const DiscordUser* request);
+} DiscordEventHandlers;
+
+#define DISCORD_REPLY_NO 0
+#define DISCORD_REPLY_YES 1
+#define DISCORD_REPLY_IGNORE 2
+#define DISCORD_PARTY_PRIVATE 0
+#define DISCORD_PARTY_PUBLIC 1
+
+DISCORD_EXPORT void Discord_Initialize(const char* applicationId,
+                                       DiscordEventHandlers* handlers,
+                                       int autoRegister,
+                                       const char* optionalSteamId);
+DISCORD_EXPORT void Discord_Shutdown(void);
+
+/* checks for incoming messages, dispatches callbacks */
+DISCORD_EXPORT void Discord_RunCallbacks(void);
+
+/* If you disable the lib starting its own io thread, you'll need to call this from your own */
+#ifdef DISCORD_DISABLE_IO_THREAD
+DISCORD_EXPORT void Discord_UpdateConnection(void);
+#endif
+
+DISCORD_EXPORT void Discord_UpdatePresence(const DiscordRichPresence* presence);
+DISCORD_EXPORT void Discord_ClearPresence(void);
+
+DISCORD_EXPORT void Discord_Respond(const char* userid, /* DISCORD_REPLY_ */ int reply);
+
+DISCORD_EXPORT void Discord_UpdateHandlers(DiscordEventHandlers* handlers);
+
+#ifdef __cplusplus
+} /* extern "C" */
+#endif

discord-integration/discord-rpc/src/CMakeLists.txt

@@ -0,0 +1,147 @@
+include_directories(${PROJECT_SOURCE_DIR}/include)
+
+option(ENABLE_IO_THREAD "Start up a separate I/O thread, otherwise I'd need to call an update function" ON)
+option(USE_STATIC_CRT "Use /MT[d] for dynamic library" OFF)
+option(WARNINGS_AS_ERRORS "When enabled, compiles with `-Werror` (on *nix platforms)." OFF)
+
+set(CMAKE_CXX_STANDARD 14)
+
+set(BASE_RPC_SRC
+    ${PROJECT_SOURCE_DIR}/include/discord_rpc.h
+    discord_rpc.cpp
+    ${PROJECT_SOURCE_DIR}/include/discord_register.h
+    rpc_connection.h
+    rpc_connection.cpp
+    serialization.h
+    serialization.cpp
+    connection.h
+    backoff.h
+    msg_queue.h
+)
+
+if (${BUILD_SHARED_LIBS})
+    if(WIN32)
+        set(BASE_RPC_SRC ${BASE_RPC_SRC} dllmain.cpp)
+    endif(WIN32)
+endif(${BUILD_SHARED_LIBS})
+
+if(WIN32)
+    add_definitions(-DDISCORD_WINDOWS)
+    set(BASE_RPC_SRC ${BASE_RPC_SRC} connection_win.cpp discord_register_win.cpp)
+    add_library(discord-rpc ${BASE_RPC_SRC})
+    if (MSVC)
+        if(USE_STATIC_CRT)
+            foreach(CompilerFlag
+                    CMAKE_CXX_FLAGS
+                    CMAKE_CXX_FLAGS_DEBUG
+                    CMAKE_CXX_FLAGS_RELEASE
+                    CMAKE_C_FLAGS
+                    CMAKE_C_FLAGS_DEBUG
+                    CMAKE_C_FLAGS_RELEASE)
+                string(REPLACE "/MD" "/MT" ${CompilerFlag} "${${CompilerFlag}}")
+            endforeach()
+        endif(USE_STATIC_CRT)
+        target_compile_options(discord-rpc PRIVATE /EHsc
+            /Wall
+            /wd4100 # unreferenced formal parameter
+            /wd4514 # unreferenced inline
+            /wd4625 # copy constructor deleted
+            /wd5026 # move constructor deleted
+            /wd4626 # move assignment operator deleted
+            /wd4668 # not defined preprocessor macro
+            /wd4710 # function not inlined
+            /wd4711 # function was inlined
+            /wd4820 # structure padding
+            /wd4946 # reinterpret_cast used between related classes
+            /wd5027 # move assignment operator was implicitly defined as deleted
+        )
+    endif(MSVC)
+    target_link_libraries(discord-rpc PRIVATE psapi advapi32)
+endif(WIN32)
+
+if(UNIX)
+    set(BASE_RPC_SRC ${BASE_RPC_SRC} connection_unix.cpp)
+
+    if (APPLE)
+        add_definitions(-DDISCORD_OSX)
+        set(BASE_RPC_SRC ${BASE_RPC_SRC} discord_register_osx.m)
+    else (APPLE)
+        add_definitions(-DDISCORD_LINUX)
+        set(BASE_RPC_SRC ${BASE_RPC_SRC} discord_register_linux.cpp)
+    endif(APPLE)
+
+    add_library(discord-rpc ${BASE_RPC_SRC})
+    target_link_libraries(discord-rpc PUBLIC pthread)
+
+    if (APPLE)
+        target_link_libraries(discord-rpc PRIVATE "-framework AppKit, -mmacosx-version-min=10.10")
+    endif (APPLE)
+
+    target_compile_options(discord-rpc PRIVATE
+        -g
+        -Wall
+        -Wextra
+        -Wpedantic
+    )
+
+    if (${WARNINGS_AS_ERRORS})
+      target_compile_options(discord-rpc PRIVATE -Werror)
+    endif (${WARNINGS_AS_ERRORS})
+
+    target_compile_options(discord-rpc PRIVATE
+        -Wno-unknown-pragmas # pragma push thing doesn't work on clang
+        -Wno-old-style-cast # it's fine
+        -Wno-c++98-compat # that was almost 2 decades ago
+        -Wno-c++98-compat-pedantic
+        -Wno-missing-noreturn
+        -Wno-padded # structure padding
+        -Wno-covered-switch-default
+        -Wno-exit-time-destructors # not sure about these
+        -Wno-global-constructors
+    )
+
+    if (${BUILD_SHARED_LIBS})
+        target_compile_options(discord-rpc PRIVATE -fPIC)
+    endif (${BUILD_SHARED_LIBS})
+
+    if (APPLE)
+        target_link_libraries(discord-rpc PRIVATE "-framework AppKit")
+    endif (APPLE)
+endif(UNIX)
+
+target_include_directories(discord-rpc PRIVATE ${RAPIDJSON}/include)
+
+if (NOT ${ENABLE_IO_THREAD})
+    target_compile_definitions(discord-rpc PUBLIC -DDISCORD_DISABLE_IO_THREAD)
+endif (NOT ${ENABLE_IO_THREAD})
+
+if (${BUILD_SHARED_LIBS})
+    target_compile_definitions(discord-rpc PUBLIC -DDISCORD_DYNAMIC_LIB)
+    target_compile_definitions(discord-rpc PRIVATE -DDISCORD_BUILDING_SDK)
+endif(${BUILD_SHARED_LIBS})
+
+if (CLANG_FORMAT_CMD)
+    add_dependencies(discord-rpc clangformat)
+endif(CLANG_FORMAT_CMD)
+
+# install
+
+install(
+    TARGETS discord-rpc
+    EXPORT "discord-rpc"
+    RUNTIME
+        DESTINATION "${CMAKE_INSTALL_BINDIR}"
+    LIBRARY
+        DESTINATION "${CMAKE_INSTALL_LIBDIR}"
+    ARCHIVE
+        DESTINATION "${CMAKE_INSTALL_LIBDIR}"
+    INCLUDES
+        DESTINATION "${CMAKE_INSTALL_INCLUDEDIR}"
+)
+
+install(
+    FILES
+        "../include/discord_rpc.h"
+		"../include/discord_register.h"
+    DESTINATION "include"
+)

discord-integration/discord-rpc/src/backoff.h

@@ -0,0 +1,40 @@
+#pragma once
+
+#include <algorithm>
+#include <random>
+#include <stdint.h>
+#include <time.h>
+
+struct Backoff {
+    int64_t minAmount;
+    int64_t maxAmount;
+    int64_t current;
+    int fails;
+    std::mt19937_64 randGenerator;
+    std::uniform_real_distribution<> randDistribution;
+
+    double rand01() { return randDistribution(randGenerator); }
+
+    Backoff(int64_t min, int64_t max)
+      : minAmount(min)
+      , maxAmount(max)
+      , current(min)
+      , fails(0)
+      , randGenerator((uint64_t)time(0))
+    {
+    }
+
+    void reset()
+    {
+        fails = 0;
+        current = minAmount;
+    }
+
+    int64_t nextDelay()
+    {
+        ++fails;
+        int64_t delay = (int64_t)((double)current * 2.0 * rand01());
+        current = std::min(current + delay, maxAmount);
+        return current;
+    }
+};

discord-integration/discord-rpc/src/connection.h

@@ -0,0 +1,19 @@
+#pragma once
+
+// This is to wrap the platform specific kinds of connect/read/write.
+
+#include <stdint.h>
+#include <stdlib.h>
+
+// not really connectiony, but need per-platform
+int GetProcessId();
+
+struct BaseConnection {
+    static BaseConnection* Create();
+    static void Destroy(BaseConnection*&);
+    bool isOpen{false};
+    bool Open();
+    bool Close();
+    bool Write(const void* data, size_t length);
+    bool Read(void* data, size_t length);
+};

discord-integration/discord-rpc/src/connection_unix.cpp

@@ -0,0 +1,125 @@
+#include "connection.h"
+
+#include <errno.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <string.h>
+#include <sys/socket.h>
+#include <sys/types.h>
+#include <sys/un.h>
+#include <unistd.h>
+
+int GetProcessId()
+{
+    return ::getpid();
+}
+
+struct BaseConnectionUnix : public BaseConnection {
+    int sock{-1};
+};
+
+static BaseConnectionUnix Connection;
+static sockaddr_un PipeAddr{};
+#ifdef MSG_NOSIGNAL
+static int MsgFlags = MSG_NOSIGNAL;
+#else
+static int MsgFlags = 0;
+#endif
+
+static const char* GetTempPath()
+{
+    const char* temp = getenv("XDG_RUNTIME_DIR");
+    temp = temp ? temp : getenv("TMPDIR");
+    temp = temp ? temp : getenv("TMP");
+    temp = temp ? temp : getenv("TEMP");
+    temp = temp ? temp : "/tmp";
+    return temp;
+}
+
+/*static*/ BaseConnection* BaseConnection::Create()
+{
+    PipeAddr.sun_family = AF_UNIX;
+    return &Connection;
+}
+
+/*static*/ void BaseConnection::Destroy(BaseConnection*& c)
+{
+    auto self = reinterpret_cast<BaseConnectionUnix*>(c);
+    self->Close();
+    c = nullptr;
+}
+
+bool BaseConnection::Open()
+{
+    const char* tempPath = GetTempPath();
+    auto self = reinterpret_cast<BaseConnectionUnix*>(this);
+    self->sock = socket(AF_UNIX, SOCK_STREAM, 0);
+    if (self->sock == -1) {
+        return false;
+    }
+    fcntl(self->sock, F_SETFL, O_NONBLOCK);
+#ifdef SO_NOSIGPIPE
+    int optval = 1;
+    setsockopt(self->sock, SOL_SOCKET, SO_NOSIGPIPE, &optval, sizeof(optval));
+#endif
+
+    for (int pipeNum = 0; pipeNum < 10; ++pipeNum) {
+        snprintf(
+          PipeAddr.sun_path, sizeof(PipeAddr.sun_path), "%s/discord-ipc-%d", tempPath, pipeNum);
+        int err = connect(self->sock, (const sockaddr*)&PipeAddr, sizeof(PipeAddr));
+        if (err == 0) {
+            self->isOpen = true;
+            return true;
+        }
+    }
+    self->Close();
+    return false;
+}
+
+bool BaseConnection::Close()
+{
+    auto self = reinterpret_cast<BaseConnectionUnix*>(this);
+    if (self->sock == -1) {
+        return false;
+    }
+    close(self->sock);
+    self->sock = -1;
+    self->isOpen = false;
+    return true;
+}
+
+bool BaseConnection::Write(const void* data, size_t length)
+{
+    auto self = reinterpret_cast<BaseConnectionUnix*>(this);
+
+    if (self->sock == -1) {
+        return false;
+    }
+
+    ssize_t sentBytes = send(self->sock, data, length, MsgFlags);
+    if (sentBytes < 0) {
+        Close();
+    }
+    return sentBytes == (ssize_t)length;
+}
+
+bool BaseConnection::Read(void* data, size_t length)
+{
+    auto self = reinterpret_cast<BaseConnectionUnix*>(this);
+
+    if (self->sock == -1) {
+        return false;
+    }
+
+    int res = (int)recv(self->sock, data, length, MsgFlags);
+    if (res < 0) {
+        if (errno == EAGAIN) {
+            return false;
+        }
+        Close();
+    }
+    else if (res == 0) {
+        Close();
+    }
+    return res == (int)length;
+}

discord-integration/discord-rpc/src/connection_win.cpp

@@ -0,0 +1,128 @@
+#include "connection.h"
+
+#define WIN32_LEAN_AND_MEAN
+#define NOMCX
+#define NOSERVICE
+#define NOIME
+#include <assert.h>
+#include <windows.h>
+
+int GetProcessId()
+{
+    return (int)::GetCurrentProcessId();
+}
+
+struct BaseConnectionWin : public BaseConnection {
+    HANDLE pipe{INVALID_HANDLE_VALUE};
+};
+
+static BaseConnectionWin Connection;
+
+/*static*/ BaseConnection* BaseConnection::Create()
+{
+    return &Connection;
+}
+
+/*static*/ void BaseConnection::Destroy(BaseConnection*& c)
+{
+    auto self = reinterpret_cast<BaseConnectionWin*>(c);
+    self->Close();
+    c = nullptr;
+}
+
+bool BaseConnection::Open()
+{
+    wchar_t pipeName[]{L"\\\\?\\pipe\\discord-ipc-0"};
+    const size_t pipeDigit = sizeof(pipeName) / sizeof(wchar_t) - 2;
+    pipeName[pipeDigit] = L'0';
+    auto self = reinterpret_cast<BaseConnectionWin*>(this);
+    for (;;) {
+        self->pipe = ::CreateFileW(
+          pipeName, GENERIC_READ | GENERIC_WRITE, 0, nullptr, OPEN_EXISTING, 0, nullptr);
+        if (self->pipe != INVALID_HANDLE_VALUE) {
+            self->isOpen = true;
+            return true;
+        }
+
+        auto lastError = GetLastError();
+        if (lastError == ERROR_FILE_NOT_FOUND) {
+            if (pipeName[pipeDigit] < L'9') {
+                pipeName[pipeDigit]++;
+                continue;
+            }
+        }
+        else if (lastError == ERROR_PIPE_BUSY) {
+            if (!WaitNamedPipeW(pipeName, 10000)) {
+                return false;
+            }
+            continue;
+        }
+        return false;
+    }
+}
+
+bool BaseConnection::Close()
+{
+    auto self = reinterpret_cast<BaseConnectionWin*>(this);
+    ::CloseHandle(self->pipe);
+    self->pipe = INVALID_HANDLE_VALUE;
+    self->isOpen = false;
+    return true;
+}
+
+bool BaseConnection::Write(const void* data, size_t length)
+{
+    if (length == 0) {
+        return true;
+    }
+    auto self = reinterpret_cast<BaseConnectionWin*>(this);
+    assert(self);
+    if (!self) {
+        return false;
+    }
+    if (self->pipe == INVALID_HANDLE_VALUE) {
+        return false;
+    }
+    assert(data);
+    if (!data) {
+        return false;
+    }
+    const DWORD bytesLength = (DWORD)length;
+    DWORD bytesWritten = 0;
+    return ::WriteFile(self->pipe, data, bytesLength, &bytesWritten, nullptr) == TRUE &&
+      bytesWritten == bytesLength;
+}
+
+bool BaseConnection::Read(void* data, size_t length)
+{
+    assert(data);
+    if (!data) {
+        return false;
+    }
+    auto self = reinterpret_cast<BaseConnectionWin*>(this);
+    assert(self);
+    if (!self) {
+        return false;
+    }
+    if (self->pipe == INVALID_HANDLE_VALUE) {
+        return false;
+    }
+    DWORD bytesAvailable = 0;
+    if (::PeekNamedPipe(self->pipe, nullptr, 0, nullptr, &bytesAvailable, nullptr)) {
+        if (bytesAvailable >= length) {
+            DWORD bytesToRead = (DWORD)length;
+            DWORD bytesRead = 0;
+            if (::ReadFile(self->pipe, data, bytesToRead, &bytesRead, nullptr) == TRUE) {
+                assert(bytesToRead == bytesRead);
+                return true;
+            }
+            else {
+                Close();
+            }
+        }
+    }
+    else {
+        Close();
+    }
+    return false;
+}

discord-integration/discord-rpc/src/discord_register_linux.cpp

@@ -0,0 +1,102 @@
+#include "discord_rpc.h"
+#include "discord_register.h"
+#include <stdio.h>
+
+#include <errno.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+static bool Mkdir(const char* path)
+{
+    int result = mkdir(path, 0755);
+    if (result == 0) {
+        return true;
+    }
+    if (errno == EEXIST) {
+        return true;
+    }
+    return false;
+}
+
+// we want to register games so we can run them from Discord client as discord-<appid>://
+extern "C" DISCORD_EXPORT void Discord_Register(const char* applicationId, const char* command)
+{
+    // Add a desktop file and update some mime handlers so that xdg-open does the right thing.
+
+    const char* home = getenv("HOME");
+    if (!home) {
+        return;
+    }
+
+    char exePath[1024];
+    if (!command || !command[0]) {
+        ssize_t size = readlink("/proc/self/exe", exePath, sizeof(exePath));
+        if (size <= 0 || size >= (ssize_t)sizeof(exePath)) {
+            return;
+        }
+        exePath[size] = '\0';
+        command = exePath;
+    }
+
+    const char* desktopFileFormat = "[Desktop Entry]\n"
+                                   "Name=Game %s\n"
+                                   "Exec=%s %%u\n" // note: it really wants that %u in there
+                                   "Type=Application\n"
+                                   "NoDisplay=true\n"
+                                   "Categories=Discord;Games;\n"
+                                   "MimeType=x-scheme-handler/discord-%s;\n";
+    char desktopFile[2048];
+    int fileLen = snprintf(
+      desktopFile, sizeof(desktopFile), desktopFileFormat, applicationId, command, applicationId);
+    if (fileLen <= 0) {
+        return;
+    }
+
+    char desktopFilename[256];
+    snprintf(desktopFilename, sizeof(desktopFilename), "/discord-%s.desktop", applicationId);
+
+    char desktopFilePath[1024];
+    snprintf(desktopFilePath, sizeof(desktopFilePath), "%s/.local", home);
+    if (!Mkdir(desktopFilePath)) {
+        return;
+    }
+    strcat(desktopFilePath, "/share");
+    if (!Mkdir(desktopFilePath)) {
+        return;
+    }
+    strcat(desktopFilePath, "/applications");
+    if (!Mkdir(desktopFilePath)) {
+        return;
+    }
+    strcat(desktopFilePath, desktopFilename);
+
+    FILE* fp = fopen(desktopFilePath, "w");
+    if (fp) {
+        fwrite(desktopFile, 1, fileLen, fp);
+        fclose(fp);
+    }
+    else {
+        return;
+    }
+
+    char xdgMimeCommand[1024];
+    snprintf(xdgMimeCommand,
+             sizeof(xdgMimeCommand),
+             "xdg-mime default discord-%s.desktop x-scheme-handler/discord-%s",
+             applicationId,
+             applicationId);
+    if (system(xdgMimeCommand) < 0) {
+        fprintf(stderr, "Failed to register mime handler\n");
+    }
+}
+
+extern "C" DISCORD_EXPORT void Discord_RegisterSteamGame(const char* applicationId,
+                                                         const char* steamId)
+{
+    char command[256];
+    sprintf(command, "xdg-open steam://rungameid/%s", steamId);
+    Discord_Register(applicationId, command);
+}

discord-integration/discord-rpc/src/discord_register_osx.m

@@ -0,0 +1,80 @@
+#include <stdio.h>
+#include <sys/stat.h>
+
+#import <AppKit/AppKit.h>
+
+#include "discord_register.h"
+
+static void RegisterCommand(const char* applicationId, const char* command)
+{
+    // There does not appear to be a way to register arbitrary commands on OSX, so instead we'll save the command
+    // to a file in the Discord config path, and when it is needed, Discord can try to load the file there, open
+    // the command therein (will pass to js's window.open, so requires a url-like thing)
+
+    // Note: will not work for sandboxed apps
+  	NSString *home = NSHomeDirectory();
+    if (!home) {
+        return;
+    }
+
+    NSString *path = [[[[[[home stringByAppendingPathComponent:@"Library"]
+                                stringByAppendingPathComponent:@"Application Support"]
+                                stringByAppendingPathComponent:@"discord"]
+                                stringByAppendingPathComponent:@"games"]
+                                stringByAppendingPathComponent:[NSString stringWithUTF8String:applicationId]]
+                                stringByAppendingPathExtension:@"json"];
+    [[NSFileManager defaultManager] createDirectoryAtPath:[path stringByDeletingLastPathComponent] withIntermediateDirectories:YES attributes:nil error:nil];
+
+    NSString *jsonBuffer = [NSString stringWithFormat:@"{\"command\": \"%s\"}", command];
+    [jsonBuffer writeToFile:path atomically:NO encoding:NSUTF8StringEncoding error:nil];
+}
+
+static void RegisterURL(const char* applicationId)
+{
+    char url[256];
+    snprintf(url, sizeof(url), "discord-%s", applicationId);
+    CFStringRef cfURL = CFStringCreateWithCString(NULL, url, kCFStringEncodingUTF8);
+
+    NSString* myBundleId = [[NSBundle mainBundle] bundleIdentifier];
+    if (!myBundleId) {
+        fprintf(stderr, "No bundle id found\n");
+        return;
+    }
+
+    NSURL* myURL = [[NSBundle mainBundle] bundleURL];
+    if (!myURL) {
+        fprintf(stderr, "No bundle url found\n");
+        return;
+    }
+
+    OSStatus status = LSSetDefaultHandlerForURLScheme(cfURL, (__bridge CFStringRef)myBundleId);
+    if (status != noErr) {
+        fprintf(stderr, "Error in LSSetDefaultHandlerForURLScheme: %d\n", (int)status);
+        return;
+    }
+
+    status = LSRegisterURL((__bridge CFURLRef)myURL, true);
+    if (status != noErr) {
+        fprintf(stderr, "Error in LSRegisterURL: %d\n", (int)status);
+    }
+}
+
+void Discord_Register(const char* applicationId, const char* command)
+{
+    if (command) {
+        RegisterCommand(applicationId, command);
+    }
+    else {
+        // raii lite
+        @autoreleasepool {
+            RegisterURL(applicationId);
+        }
+    }
+}
+
+void Discord_RegisterSteamGame(const char* applicationId, const char* steamId)
+{
+    char command[256];
+    snprintf(command, 256, "steam://rungameid/%s", steamId);
+    Discord_Register(applicationId, command);
+}

discord-integration/discord-rpc/src/discord_register_win.cpp

@@ -0,0 +1,186 @@
+#include "discord_rpc.h"
+#include "discord_register.h"
+
+#define WIN32_LEAN_AND_MEAN
+#define NOMCX
+#define NOSERVICE
+#define NOIME
+#include <windows.h>
+#include <psapi.h>
+#include <cstdio>
+
+/**
+ * Updated fixes for MinGW and WinXP
+ * This block is written the way it does not involve changing the rest of the code
+ * Checked to be compiling
+ * 1) strsafe.h belongs to Windows SDK and cannot be added to MinGW
+ * #include guarded, functions redirected to <string.h> substitutes
+ * 2) RegSetKeyValueW and LSTATUS are not declared in <winreg.h>
+ * The entire function is rewritten
+ */
+#ifdef __MINGW32__
+#include <wchar.h>
+/// strsafe.h fixes
+static HRESULT StringCbPrintfW(LPWSTR pszDest, size_t cbDest, LPCWSTR pszFormat, ...)
+{
+    HRESULT ret;
+    va_list va;
+    va_start(va, pszFormat);
+    cbDest /= 2; // Size is divided by 2 to convert from bytes to wide characters - causes segfault
+                 // othervise
+    ret = vsnwprintf(pszDest, cbDest, pszFormat, va);
+    pszDest[cbDest - 1] = 0; // Terminate the string in case a buffer overflow; -1 will be returned
+    va_end(va);
+    return ret;
+}
+#else
+#include <cwchar>
+#include <strsafe.h>
+#endif // __MINGW32__
+
+/// winreg.h fixes
+#ifndef LSTATUS
+#define LSTATUS LONG
+#endif
+#ifdef RegSetKeyValueW
+#undefine RegSetKeyValueW
+#endif
+#define RegSetKeyValueW regset
+static LSTATUS regset(HKEY hkey,
+                      LPCWSTR subkey,
+                      LPCWSTR name,
+                      DWORD type,
+                      const void* data,
+                      DWORD len)
+{
+    HKEY htkey = hkey, hsubkey = nullptr;
+    LSTATUS ret;
+    if (subkey && subkey[0]) {
+        if ((ret = RegCreateKeyExW(hkey, subkey, 0, 0, 0, KEY_ALL_ACCESS, 0, &hsubkey, 0)) !=
+            ERROR_SUCCESS)
+            return ret;
+        htkey = hsubkey;
+    }
+    ret = RegSetValueExW(htkey, name, 0, type, (const BYTE*)data, len);
+    if (hsubkey && hsubkey != hkey)
+        RegCloseKey(hsubkey);
+    return ret;
+}
+
+static void Discord_RegisterW(const wchar_t* applicationId, const wchar_t* command)
+{
+    // https://msdn.microsoft.com/en-us/library/aa767914(v=vs.85).aspx
+    // we want to register games so we can run them as discord-<appid>://
+    // Update the HKEY_CURRENT_USER, because it doesn't seem to require special permissions.
+
+    wchar_t exeFilePath[MAX_PATH];
+    DWORD exeLen = GetModuleFileNameW(nullptr, exeFilePath, MAX_PATH);
+    wchar_t openCommand[1024];
+
+    if (command && command[0]) {
+        StringCbPrintfW(openCommand, sizeof(openCommand), L"%s", command);
+    }
+    else {
+        // StringCbCopyW(openCommand, sizeof(openCommand), exeFilePath);
+        StringCbPrintfW(openCommand, sizeof(openCommand), L"%s", exeFilePath);
+    }
+
+    wchar_t protocolName[64];
+    StringCbPrintfW(protocolName, sizeof(protocolName), L"discord-%s", applicationId);
+    wchar_t protocolDescription[128];
+    StringCbPrintfW(
+      protocolDescription, sizeof(protocolDescription), L"URL:Run game %s protocol", applicationId);
+    wchar_t urlProtocol = 0;
+
+    wchar_t keyName[256];
+    StringCbPrintfW(keyName, sizeof(keyName), L"Software\\Classes\\%s", protocolName);
+    HKEY key;
+    auto status =
+      RegCreateKeyExW(HKEY_CURRENT_USER, keyName, 0, nullptr, 0, KEY_WRITE, nullptr, &key, nullptr);
+    if (status != ERROR_SUCCESS) {
+        fprintf(stderr, "Error creating key\n");
+        return;
+    }
+    DWORD len;
+    LSTATUS result;
+    len = (DWORD)lstrlenW(protocolDescription) + 1;
+    result =
+      RegSetKeyValueW(key, nullptr, nullptr, REG_SZ, protocolDescription, len * sizeof(wchar_t));
+    if (FAILED(result)) {
+        fprintf(stderr, "Error writing description\n");
+    }
+
+    len = (DWORD)lstrlenW(protocolDescription) + 1;
+    result = RegSetKeyValueW(key, nullptr, L"URL Protocol", REG_SZ, &urlProtocol, sizeof(wchar_t));
+    if (FAILED(result)) {
+        fprintf(stderr, "Error writing description\n");
+    }
+
+    result = RegSetKeyValueW(
+      key, L"DefaultIcon", nullptr, REG_SZ, exeFilePath, (exeLen + 1) * sizeof(wchar_t));
+    if (FAILED(result)) {
+        fprintf(stderr, "Error writing icon\n");
+    }
+
+    len = (DWORD)lstrlenW(openCommand) + 1;
+    result = RegSetKeyValueW(
+      key, L"shell\\open\\command", nullptr, REG_SZ, openCommand, len * sizeof(wchar_t));
+    if (FAILED(result)) {
+        fprintf(stderr, "Error writing command\n");
+    }
+    RegCloseKey(key);
+}
+
+extern "C" DISCORD_EXPORT void Discord_Register(const char* applicationId, const char* command)
+{
+    wchar_t appId[32];
+    MultiByteToWideChar(CP_UTF8, 0, applicationId, -1, appId, 32);
+
+    wchar_t openCommand[1024];
+    const wchar_t* wcommand = nullptr;
+    if (command && command[0]) {
+        const auto commandBufferLen = sizeof(openCommand) / sizeof(*openCommand);
+        MultiByteToWideChar(CP_UTF8, 0, command, -1, openCommand, commandBufferLen);
+        wcommand = openCommand;
+    }
+
+    Discord_RegisterW(appId, wcommand);
+}
+
+extern "C" DISCORD_EXPORT void Discord_RegisterSteamGame(const char* applicationId,
+                                                         const char* steamId)
+{
+    wchar_t appId[32];
+    MultiByteToWideChar(CP_UTF8, 0, applicationId, -1, appId, 32);
+
+    wchar_t wSteamId[32];
+    MultiByteToWideChar(CP_UTF8, 0, steamId, -1, wSteamId, 32);
+
+    HKEY key;
+    auto status = RegOpenKeyExW(HKEY_CURRENT_USER, L"Software\\Valve\\Steam", 0, KEY_READ, &key);
+    if (status != ERROR_SUCCESS) {
+        fprintf(stderr, "Error opening Steam key\n");
+        return;
+    }
+
+    wchar_t steamPath[MAX_PATH];
+    DWORD pathBytes = sizeof(steamPath);
+    status = RegQueryValueExW(key, L"SteamExe", nullptr, nullptr, (BYTE*)steamPath, &pathBytes);
+    RegCloseKey(key);
+    if (status != ERROR_SUCCESS || pathBytes < 1) {
+        fprintf(stderr, "Error reading SteamExe key\n");
+        return;
+    }
+
+    DWORD pathChars = pathBytes / sizeof(wchar_t);
+    for (DWORD i = 0; i < pathChars; ++i) {
+        if (steamPath[i] == L'/') {
+            steamPath[i] = L'\\';
+        }
+    }
+
+    wchar_t command[1024];
+    StringCbPrintfW(command, sizeof(command), L"\"%s\" steam://rungameid/%s", steamPath, wSteamId);
+
+    Discord_RegisterW(appId, command);
+}

discord-integration/discord-rpc/src/discord_rpc.cpp

@@ -0,0 +1,504 @@
+#include "discord_rpc.h"
+
+#include "backoff.h"
+#include "discord_register.h"
+#include "msg_queue.h"
+#include "rpc_connection.h"
+#include "serialization.h"
+
+#include <atomic>
+#include <chrono>
+#include <mutex>
+
+#ifndef DISCORD_DISABLE_IO_THREAD
+#include <condition_variable>
+#include <thread>
+#endif
+
+constexpr size_t MaxMessageSize{16 * 1024};
+constexpr size_t MessageQueueSize{8};
+constexpr size_t JoinQueueSize{8};
+
+struct QueuedMessage {
+    size_t length;
+    char buffer[MaxMessageSize];
+
+    void Copy(const QueuedMessage& other)
+    {
+        length = other.length;
+        if (length) {
+            memcpy(buffer, other.buffer, length);
+        }
+    }
+};
+
+struct User {
+    // snowflake (64bit int), turned into a ascii decimal string, at most 20 chars +1 null
+    // terminator = 21
+    char userId[32];
+    // 32 unicode glyphs is max name size => 4 bytes per glyph in the worst case, +1 for null
+    // terminator = 129
+    char username[344];
+    // 4 decimal digits + 1 null terminator = 5
+    char discriminator[8];
+    // optional 'a_' + md5 hex digest (32 bytes) + null terminator = 35
+    char avatar[128];
+    // Rounded way up because I'm paranoid about games breaking from future changes in these sizes
+};
+
+static RpcConnection* Connection{nullptr};
+static DiscordEventHandlers QueuedHandlers{};
+static DiscordEventHandlers Handlers{};
+static std::atomic_bool WasJustConnected{false};
+static std::atomic_bool WasJustDisconnected{false};
+static std::atomic_bool GotErrorMessage{false};
+static std::atomic_bool WasJoinGame{false};
+static std::atomic_bool WasSpectateGame{false};
+static std::atomic_bool UpdatePresence{false};
+static char JoinGameSecret[256];
+static char SpectateGameSecret[256];
+static int LastErrorCode{0};
+static char LastErrorMessage[256];
+static int LastDisconnectErrorCode{0};
+static char LastDisconnectErrorMessage[256];
+static std::mutex PresenceMutex;
+static std::mutex HandlerMutex;
+static QueuedMessage QueuedPresence{};
+static MsgQueue<QueuedMessage, MessageQueueSize> SendQueue;
+static MsgQueue<User, JoinQueueSize> JoinAskQueue;
+static User connectedUser;
+
+// We want to auto connect, and retry on failure, but not as fast as possible. This does expoential
+// backoff from 0.5 seconds to 1 minute
+static Backoff ReconnectTimeMs(500, 60 * 1000);
+static auto NextConnect = std::chrono::system_clock::now();
+static int Pid{0};
+static int Nonce{1};
+
+#ifndef DISCORD_DISABLE_IO_THREAD
+static void Discord_UpdateConnection(void);
+class IoThreadHolder {
+private:
+    std::atomic_bool keepRunning{true};
+    std::mutex waitForIOMutex;
+    std::condition_variable waitForIOActivity;
+    std::thread ioThread;
+
+public:
+    void Start()
+    {
+        keepRunning.store(true);
+        ioThread = std::thread([&]() {
+            const std::chrono::duration<int64_t, std::milli> maxWait{500LL};
+            Discord_UpdateConnection();
+            while (keepRunning.load()) {
+                std::unique_lock<std::mutex> lock(waitForIOMutex);
+                waitForIOActivity.wait_for(lock, maxWait);
+                Discord_UpdateConnection();
+            }
+        });
+    }
+
+    void Notify() { waitForIOActivity.notify_all(); }
+
+    void Stop()
+    {
+        keepRunning.exchange(false);
+        Notify();
+        if (ioThread.joinable()) {
+            ioThread.join();
+        }
+    }
+
+    ~IoThreadHolder() { Stop(); }
+};
+#else
+class IoThreadHolder {
+public:
+    void Start() {}
+    void Stop() {}
+    void Notify() {}
+};
+#endif // DISCORD_DISABLE_IO_THREAD
+static IoThreadHolder* IoThread{nullptr};
+
+static void UpdateReconnectTime()
+{
+    NextConnect = std::chrono::system_clock::now() +
+      std::chrono::duration<int64_t, std::milli>{ReconnectTimeMs.nextDelay()};
+}
+
+#ifdef DISCORD_DISABLE_IO_THREAD
+extern "C" DISCORD_EXPORT void Discord_UpdateConnection(void)
+#else
+static void Discord_UpdateConnection(void)
+#endif
+{
+    if (!Connection) {
+        return;
+    }
+
+    if (!Connection->IsOpen()) {
+        if (std::chrono::system_clock::now() >= NextConnect) {
+            UpdateReconnectTime();
+            Connection->Open();
+        }
+    }
+    else {
+        // reads
+
+        for (;;) {
+            JsonDocument message;
+
+            if (!Connection->Read(message)) {
+                break;
+            }
+
+            const char* evtName = GetStrMember(&message, "evt");
+            const char* nonce = GetStrMember(&message, "nonce");
+
+            if (nonce) {
+                // in responses only -- should use to match up response when needed.
+
+                if (evtName && strcmp(evtName, "ERROR") == 0) {
+                    auto data = GetObjMember(&message, "data");
+                    LastErrorCode = GetIntMember(data, "code");
+                    StringCopy(LastErrorMessage, GetStrMember(data, "message", ""));
+                    GotErrorMessage.store(true);
+                }
+            }
+            else {
+                // should have evt == name of event, optional data
+                if (evtName == nullptr) {
+                    continue;
+                }
+
+                auto data = GetObjMember(&message, "data");
+
+                if (strcmp(evtName, "ACTIVITY_JOIN") == 0) {
+                    auto secret = GetStrMember(data, "secret");
+                    if (secret) {
+                        StringCopy(JoinGameSecret, secret);
+                        WasJoinGame.store(true);
+                    }
+                }
+                else if (strcmp(evtName, "ACTIVITY_SPECTATE") == 0) {
+                    auto secret = GetStrMember(data, "secret");
+                    if (secret) {
+                        StringCopy(SpectateGameSecret, secret);
+                        WasSpectateGame.store(true);
+                    }
+                }
+                else if (strcmp(evtName, "ACTIVITY_JOIN_REQUEST") == 0) {
+                    auto user = GetObjMember(data, "user");
+                    auto userId = GetStrMember(user, "id");
+                    auto username = GetStrMember(user, "username");
+                    auto avatar = GetStrMember(user, "avatar");
+                    auto joinReq = JoinAskQueue.GetNextAddMessage();
+                    if (userId && username && joinReq) {
+                        StringCopy(joinReq->userId, userId);
+                        StringCopy(joinReq->username, username);
+                        auto discriminator = GetStrMember(user, "discriminator");
+                        if (discriminator) {
+                            StringCopy(joinReq->discriminator, discriminator);
+                        }
+                        if (avatar) {
+                            StringCopy(joinReq->avatar, avatar);
+                        }
+                        else {
+                            joinReq->avatar[0] = 0;
+                        }
+                        JoinAskQueue.CommitAdd();
+                    }
+                }
+            }
+        }
+
+        // writes
+        if (UpdatePresence.exchange(false) && QueuedPresence.length) {
+            QueuedMessage local;
+            {
+                std::lock_guard<std::mutex> guard(PresenceMutex);
+                local.Copy(QueuedPresence);
+            }
+            if (!Connection->Write(local.buffer, local.length)) {
+                // if we fail to send, requeue
+                std::lock_guard<std::mutex> guard(PresenceMutex);
+                QueuedPresence.Copy(local);
+                UpdatePresence.exchange(true);
+            }
+        }
+
+        while (SendQueue.HavePendingSends()) {
+            auto qmessage = SendQueue.GetNextSendMessage();
+            Connection->Write(qmessage->buffer, qmessage->length);
+            SendQueue.CommitSend();
+        }
+    }
+}
+
+static void SignalIOActivity()
+{
+    if (IoThread != nullptr) {
+        IoThread->Notify();
+    }
+}
+
+static bool RegisterForEvent(const char* evtName)
+{
+    auto qmessage = SendQueue.GetNextAddMessage();
+    if (qmessage) {
+        qmessage->length =
+          JsonWriteSubscribeCommand(qmessage->buffer, sizeof(qmessage->buffer), Nonce++, evtName);
+        SendQueue.CommitAdd();
+        SignalIOActivity();
+        return true;
+    }
+    return false;
+}
+
+static bool DeregisterForEvent(const char* evtName)
+{
+    auto qmessage = SendQueue.GetNextAddMessage();
+    if (qmessage) {
+        qmessage->length =
+          JsonWriteUnsubscribeCommand(qmessage->buffer, sizeof(qmessage->buffer), Nonce++, evtName);
+        SendQueue.CommitAdd();
+        SignalIOActivity();
+        return true;
+    }
+    return false;
+}
+
+extern "C" DISCORD_EXPORT void Discord_Initialize(const char* applicationId,
+                                                  DiscordEventHandlers* handlers,
+                                                  int autoRegister,
+                                                  const char* optionalSteamId)
+{
+    IoThread = new (std::nothrow) IoThreadHolder();
+    if (IoThread == nullptr) {
+        return;
+    }
+
+    if (autoRegister) {
+        if (optionalSteamId && optionalSteamId[0]) {
+            Discord_RegisterSteamGame(applicationId, optionalSteamId);
+        }
+        else {
+            Discord_Register(applicationId, nullptr);
+        }
+    }
+
+    Pid = GetProcessId();
+
+    {
+        std::lock_guard<std::mutex> guard(HandlerMutex);
+
+        if (handlers) {
+            QueuedHandlers = *handlers;
+        }
+        else {
+            QueuedHandlers = {};
+        }
+
+        Handlers = {};
+    }
+
+    if (Connection) {
+        return;
+    }
+
+    Connection = RpcConnection::Create(applicationId);
+    Connection->onConnect = [](JsonDocument& readyMessage) {
+        Discord_UpdateHandlers(&QueuedHandlers);
+        if (QueuedPresence.length > 0) {
+            UpdatePresence.exchange(true);
+            SignalIOActivity();
+        }
+        auto data = GetObjMember(&readyMessage, "data");
+        auto user = GetObjMember(data, "user");
+        auto userId = GetStrMember(user, "id");
+        auto username = GetStrMember(user, "username");
+        auto avatar = GetStrMember(user, "avatar");
+        if (userId && username) {
+            StringCopy(connectedUser.userId, userId);
+            StringCopy(connectedUser.username, username);
+            auto discriminator = GetStrMember(user, "discriminator");
+            if (discriminator) {
+                StringCopy(connectedUser.discriminator, discriminator);
+            }
+            if (avatar) {
+                StringCopy(connectedUser.avatar, avatar);
+            }
+            else {
+                connectedUser.avatar[0] = 0;
+            }
+        }
+        WasJustConnected.exchange(true);
+        ReconnectTimeMs.reset();
+    };
+    Connection->onDisconnect = [](int err, const char* message) {
+        LastDisconnectErrorCode = err;
+        StringCopy(LastDisconnectErrorMessage, message);
+        WasJustDisconnected.exchange(true);
+        UpdateReconnectTime();
+    };
+
+    IoThread->Start();
+}
+
+extern "C" DISCORD_EXPORT void Discord_Shutdown(void)
+{
+    if (!Connection) {
+        return;
+    }
+    Connection->onConnect = nullptr;
+    Connection->onDisconnect = nullptr;
+    Handlers = {};
+    QueuedPresence.length = 0;
+    UpdatePresence.exchange(false);
+    if (IoThread != nullptr) {
+        IoThread->Stop();
+        delete IoThread;
+        IoThread = nullptr;
+    }
+
+    RpcConnection::Destroy(Connection);
+}
+
+extern "C" DISCORD_EXPORT void Discord_UpdatePresence(const DiscordRichPresence* presence)
+{
+    {
+        std::lock_guard<std::mutex> guard(PresenceMutex);
+        QueuedPresence.length = JsonWriteRichPresenceObj(
+          QueuedPresence.buffer, sizeof(QueuedPresence.buffer), Nonce++, Pid, presence);
+        UpdatePresence.exchange(true);
+    }
+    SignalIOActivity();
+}
+
+extern "C" DISCORD_EXPORT void Discord_ClearPresence(void)
+{
+    Discord_UpdatePresence(nullptr);
+}
+
+extern "C" DISCORD_EXPORT void Discord_Respond(const char* userId, /* DISCORD_REPLY_ */ int reply)
+{
+    // if we are not connected, let's not batch up stale messages for later
+    if (!Connection || !Connection->IsOpen()) {
+        return;
+    }
+    auto qmessage = SendQueue.GetNextAddMessage();
+    if (qmessage) {
+        qmessage->length =
+          JsonWriteJoinReply(qmessage->buffer, sizeof(qmessage->buffer), userId, reply, Nonce++);
+        SendQueue.CommitAdd();
+        SignalIOActivity();
+    }
+}
+
+extern "C" DISCORD_EXPORT void Discord_RunCallbacks(void)
+{
+    // Note on some weirdness: internally we might connect, get other signals, disconnect any number
+    // of times inbetween calls here. Externally, we want the sequence to seem sane, so any other
+    // signals are book-ended by calls to ready and disconnect.
+
+    if (!Connection) {
+        return;
+    }
+
+    bool wasDisconnected = WasJustDisconnected.exchange(false);
+    bool isConnected = Connection->IsOpen();
+
+    if (isConnected) {
+        // if we are connected, disconnect cb first
+        std::lock_guard<std::mutex> guard(HandlerMutex);
+        if (wasDisconnected && Handlers.disconnected) {
+            Handlers.disconnected(LastDisconnectErrorCode, LastDisconnectErrorMessage);
+        }
+    }
+
+    if (WasJustConnected.exchange(false)) {
+        std::lock_guard<std::mutex> guard(HandlerMutex);
+        if (Handlers.ready) {
+            DiscordUser du{connectedUser.userId,
+                           connectedUser.username,
+                           connectedUser.discriminator,
+                           connectedUser.avatar};
+            Handlers.ready(&du);
+        }
+    }
+
+    if (GotErrorMessage.exchange(false)) {
+        std::lock_guard<std::mutex> guard(HandlerMutex);
+        if (Handlers.errored) {
+            Handlers.errored(LastErrorCode, LastErrorMessage);
+        }
+    }
+
+    if (WasJoinGame.exchange(false)) {
+        std::lock_guard<std::mutex> guard(HandlerMutex);
+        if (Handlers.joinGame) {
+            Handlers.joinGame(JoinGameSecret);
+        }
+    }
+
+    if (WasSpectateGame.exchange(false)) {
+        std::lock_guard<std::mutex> guard(HandlerMutex);
+        if (Handlers.spectateGame) {
+            Handlers.spectateGame(SpectateGameSecret);
+        }
+    }
+
+    // Right now this batches up any requests and sends them all in a burst; I could imagine a world
+    // where the implementer would rather sequentially accept/reject each one before the next invite
+    // is sent. I left it this way because I could also imagine wanting to process these all and
+    // maybe show them in one common dialog and/or start fetching the avatars in parallel, and if
+    // not it should be trivial for the implementer to make a queue themselves.
+    while (JoinAskQueue.HavePendingSends()) {
+        auto req = JoinAskQueue.GetNextSendMessage();
+        {
+            std::lock_guard<std::mutex> guard(HandlerMutex);
+            if (Handlers.joinRequest) {
+                DiscordUser du{req->userId, req->username, req->discriminator, req->avatar};
+                Handlers.joinRequest(&du);
+            }
+        }
+        JoinAskQueue.CommitSend();
+    }
+
+    if (!isConnected) {
+        // if we are not connected, disconnect message last
+        std::lock_guard<std::mutex> guard(HandlerMutex);
+        if (wasDisconnected && Handlers.disconnected) {
+            Handlers.disconnected(LastDisconnectErrorCode, LastDisconnectErrorMessage);
+        }
+    }
+}
+
+extern "C" DISCORD_EXPORT void Discord_UpdateHandlers(DiscordEventHandlers* newHandlers)
+{
+    if (newHandlers) {
+#define HANDLE_EVENT_REGISTRATION(handler_name, event)              \
+    if (!Handlers.handler_name && newHandlers->handler_name) {      \
+        RegisterForEvent(event);                                    \
+    }                                                               \
+    else if (Handlers.handler_name && !newHandlers->handler_name) { \
+        DeregisterForEvent(event);                                  \
+    }
+
+        std::lock_guard<std::mutex> guard(HandlerMutex);
+        HANDLE_EVENT_REGISTRATION(joinGame, "ACTIVITY_JOIN")
+        HANDLE_EVENT_REGISTRATION(spectateGame, "ACTIVITY_SPECTATE")
+        HANDLE_EVENT_REGISTRATION(joinRequest, "ACTIVITY_JOIN_REQUEST")
+
+#undef HANDLE_EVENT_REGISTRATION
+
+        Handlers = *newHandlers;
+    }
+    else {
+        std::lock_guard<std::mutex> guard(HandlerMutex);
+        Handlers = {};
+    }
+    return;
+}

discord-integration/discord-rpc/src/dllmain.cpp

@@ -0,0 +1,8 @@
+#include <windows.h>
+
+// outsmart GCC's missing-declarations warning
+BOOL WINAPI DllMain(HMODULE, DWORD, LPVOID);
+BOOL WINAPI DllMain(HMODULE, DWORD, LPVOID)
+{
+    return TRUE;
+}

discord-integration/discord-rpc/src/msg_queue.h

@@ -0,0 +1,36 @@
+#pragma once
+
+#include <atomic>
+
+// A simple queue. No locks, but only works with a single thread as producer and a single thread as
+// a consumer. Mutex up as needed.
+
+template <typename ElementType, size_t QueueSize>
+class MsgQueue {
+    ElementType queue_[QueueSize];
+    std::atomic_uint nextAdd_{0};
+    std::atomic_uint nextSend_{0};
+    std::atomic_uint pendingSends_{0};
+
+public:
+    MsgQueue() {}
+
+    ElementType* GetNextAddMessage()
+    {
+        // if we are falling behind, bail
+        if (pendingSends_.load() >= QueueSize) {
+            return nullptr;
+        }
+        auto index = (nextAdd_++) % QueueSize;
+        return &queue_[index];
+    }
+    void CommitAdd() { ++pendingSends_; }
+
+    bool HavePendingSends() const { return pendingSends_.load() != 0; }
+    ElementType* GetNextSendMessage()
+    {
+        auto index = (nextSend_++) % QueueSize;
+        return &queue_[index];
+    }
+    void CommitSend() { --pendingSends_; }
+};

discord-integration/discord-rpc/src/rpc_connection.cpp

@@ -0,0 +1,137 @@
+#include "rpc_connection.h"
+#include "serialization.h"
+
+#include <atomic>
+
+static const int RpcVersion = 1;
+static RpcConnection Instance;
+
+/*static*/ RpcConnection* RpcConnection::Create(const char* applicationId)
+{
+    Instance.connection = BaseConnection::Create();
+    StringCopy(Instance.appId, applicationId);
+    return &Instance;
+}
+
+/*static*/ void RpcConnection::Destroy(RpcConnection*& c)
+{
+    c->Close();
+    BaseConnection::Destroy(c->connection);
+    c = nullptr;
+}
+
+void RpcConnection::Open()
+{
+    if (state == State::Connected) {
+        return;
+    }
+
+    if (state == State::Disconnected && !connection->Open()) {
+        return;
+    }
+
+    if (state == State::SentHandshake) {
+        JsonDocument message;
+        if (Read(message)) {
+            auto cmd = GetStrMember(&message, "cmd");
+            auto evt = GetStrMember(&message, "evt");
+            if (cmd && evt && !strcmp(cmd, "DISPATCH") && !strcmp(evt, "READY")) {
+                state = State::Connected;
+                if (onConnect) {
+                    onConnect(message);
+                }
+            }
+        }
+    }
+    else {
+        sendFrame.opcode = Opcode::Handshake;
+        sendFrame.length = (uint32_t)JsonWriteHandshakeObj(
+          sendFrame.message, sizeof(sendFrame.message), RpcVersion, appId);
+
+        if (connection->Write(&sendFrame, sizeof(MessageFrameHeader) + sendFrame.length)) {
+            state = State::SentHandshake;
+        }
+        else {
+            Close();
+        }
+    }
+}
+
+void RpcConnection::Close()
+{
+    if (onDisconnect && (state == State::Connected || state == State::SentHandshake)) {
+        onDisconnect(lastErrorCode, lastErrorMessage);
+    }
+    connection->Close();
+    state = State::Disconnected;
+}
+
+bool RpcConnection::Write(const void* data, size_t length)
+{
+    sendFrame.opcode = Opcode::Frame;
+    memcpy(sendFrame.message, data, length);
+    sendFrame.length = (uint32_t)length;
+    if (!connection->Write(&sendFrame, sizeof(MessageFrameHeader) + length)) {
+        Close();
+        return false;
+    }
+    return true;
+}
+
+bool RpcConnection::Read(JsonDocument& message)
+{
+    if (state != State::Connected && state != State::SentHandshake) {
+        return false;
+    }
+    MessageFrame readFrame;
+    for (;;) {
+        bool didRead = connection->Read(&readFrame, sizeof(MessageFrameHeader));
+        if (!didRead) {
+            if (!connection->isOpen) {
+                lastErrorCode = (int)ErrorCode::PipeClosed;
+                StringCopy(lastErrorMessage, "Pipe closed");
+                Close();
+            }
+            return false;
+        }
+
+        if (readFrame.length > 0) {
+            didRead = connection->Read(readFrame.message, readFrame.length);
+            if (!didRead) {
+                lastErrorCode = (int)ErrorCode::ReadCorrupt;
+                StringCopy(lastErrorMessage, "Partial data in frame");
+                Close();
+                return false;
+            }
+            readFrame.message[readFrame.length] = 0;
+        }
+
+        switch (readFrame.opcode) {
+        case Opcode::Close: {
+            message.ParseInsitu(readFrame.message);
+            lastErrorCode = GetIntMember(&message, "code");
+            StringCopy(lastErrorMessage, GetStrMember(&message, "message", ""));
+            Close();
+            return false;
+        }
+        case Opcode::Frame:
+            message.ParseInsitu(readFrame.message);
+            return true;
+        case Opcode::Ping:
+            readFrame.opcode = Opcode::Pong;
+            if (!connection->Write(&readFrame, sizeof(MessageFrameHeader) + readFrame.length)) {
+                Close();
+            }
+            break;
+        case Opcode::Pong:
+            break;
+        case Opcode::Handshake:
+        default:
+            // something bad happened
+            lastErrorCode = (int)ErrorCode::ReadCorrupt;
+            StringCopy(lastErrorMessage, "Bad ipc frame");
+            Close();
+            return false;
+        }
+    }
+}

discord-integration/discord-rpc/src/rpc_connection.h

@@ -0,0 +1,59 @@
+#pragma once
+
+#include "connection.h"
+#include "serialization.h"
+
+// I took this from the buffer size libuv uses for named pipes; I suspect ours would usually be much
+// smaller.
+constexpr size_t MaxRpcFrameSize = 64 * 1024;
+
+struct RpcConnection {
+    enum class ErrorCode : int {
+        Success = 0,
+        PipeClosed = 1,
+        ReadCorrupt = 2,
+    };
+
+    enum class Opcode : uint32_t {
+        Handshake = 0,
+        Frame = 1,
+        Close = 2,
+        Ping = 3,
+        Pong = 4,
+    };
+
+    struct MessageFrameHeader {
+        Opcode opcode;
+        uint32_t length;
+    };
+
+    struct MessageFrame : public MessageFrameHeader {
+        char message[MaxRpcFrameSize - sizeof(MessageFrameHeader)];
+    };
+
+    enum class State : uint32_t {
+        Disconnected,
+        SentHandshake,
+        AwaitingResponse,
+        Connected,
+    };
+
+    BaseConnection* connection{nullptr};
+    State state{State::Disconnected};
+    void (*onConnect)(JsonDocument& message){nullptr};
+    void (*onDisconnect)(int errorCode, const char* message){nullptr};
+    char appId[64]{};
+    int lastErrorCode{0};
+    char lastErrorMessage[256]{};
+    RpcConnection::MessageFrame sendFrame;
+
+    static RpcConnection* Create(const char* applicationId);
+    static void Destroy(RpcConnection*&);
+
+    inline bool IsOpen() const { return state == State::Connected; }
+
+    void Open();
+    void Close();
+    bool Write(const void* data, size_t length);
+    bool Read(JsonDocument& message);
+};

discord-integration/discord-rpc/src/serialization.cpp

@@ -0,0 +1,250 @@
+#include "serialization.h"
+#include "connection.h"
+#include "discord_rpc.h"
+
+template <typename T>
+void NumberToString(char* dest, T number)
+{
+    if (!number) {
+        *dest++ = '0';
+        *dest++ = 0;
+        return;
+    }
+    if (number < 0) {
+        *dest++ = '-';
+        number = -number;
+    }
+    char temp[32];
+    int place = 0;
+    while (number) {
+        auto digit = number % 10;
+        number = number / 10;
+        temp[place++] = '0' + (char)digit;
+    }
+    for (--place; place >= 0; --place) {
+        *dest++ = temp[place];
+    }
+    *dest = 0;
+}
+
+// it's ever so slightly faster to not have to strlen the key
+template <typename T>
+void WriteKey(JsonWriter& w, T& k)
+{
+    w.Key(k, sizeof(T) - 1);
+}
+
+struct WriteObject {
+    JsonWriter& writer;
+    WriteObject(JsonWriter& w)
+      : writer(w)
+    {
+        writer.StartObject();
+    }
+    template <typename T>
+    WriteObject(JsonWriter& w, T& name)
+      : writer(w)
+    {
+        WriteKey(writer, name);
+        writer.StartObject();
+    }
+    ~WriteObject() { writer.EndObject(); }
+};
+
+struct WriteArray {
+    JsonWriter& writer;
+    template <typename T>
+    WriteArray(JsonWriter& w, T& name)
+      : writer(w)
+    {
+        WriteKey(writer, name);
+        writer.StartArray();
+    }
+    ~WriteArray() { writer.EndArray(); }
+};
+
+template <typename T>
+void WriteOptionalString(JsonWriter& w, T& k, const char* value)
+{
+    if (value && value[0]) {
+        w.Key(k, sizeof(T) - 1);
+        w.String(value);
+    }
+}
+
+static void JsonWriteNonce(JsonWriter& writer, int nonce)
+{
+    WriteKey(writer, "nonce");
+    char nonceBuffer[32];
+    NumberToString(nonceBuffer, nonce);
+    writer.String(nonceBuffer);
+}
+
+size_t JsonWriteRichPresenceObj(char* dest,
+                                size_t maxLen,
+                                int nonce,
+                                int pid,
+                                const DiscordRichPresence* presence)
+{
+    JsonWriter writer(dest, maxLen);
+
+    {
+        WriteObject top(writer);
+
+        JsonWriteNonce(writer, nonce);
+
+        WriteKey(writer, "cmd");
+        writer.String("SET_ACTIVITY");
+
+        {
+            WriteObject args(writer, "args");
+
+            WriteKey(writer, "pid");
+            writer.Int(pid);
+
+            if (presence != nullptr) {
+                WriteObject activity(writer, "activity");
+
+                WriteOptionalString(writer, "state", presence->state);
+                WriteOptionalString(writer, "details", presence->details);
+
+                if (presence->startTimestamp || presence->endTimestamp) {
+                    WriteObject timestamps(writer, "timestamps");
+
+                    if (presence->startTimestamp) {
+                        WriteKey(writer, "start");
+                        writer.Int64(presence->startTimestamp);
+                    }
+
+                    if (presence->endTimestamp) {
+                        WriteKey(writer, "end");
+                        writer.Int64(presence->endTimestamp);
+                    }
+                }
+
+                if ((presence->largeImageKey && presence->largeImageKey[0]) ||
+                    (presence->largeImageText && presence->largeImageText[0]) ||
+                    (presence->smallImageKey && presence->smallImageKey[0]) ||
+                    (presence->smallImageText && presence->smallImageText[0])) {
+                    WriteObject assets(writer, "assets");
+                    WriteOptionalString(writer, "large_image", presence->largeImageKey);
+                    WriteOptionalString(writer, "large_text", presence->largeImageText);
+                    WriteOptionalString(writer, "small_image", presence->smallImageKey);
+                    WriteOptionalString(writer, "small_text", presence->smallImageText);
+                }
+
+                if ((presence->partyId && presence->partyId[0]) || presence->partySize ||
+                    presence->partyMax || presence->partyPrivacy) {
+                    WriteObject party(writer, "party");
+                    WriteOptionalString(writer, "id", presence->partyId);
+                    if (presence->partySize && presence->partyMax) {
+                        WriteArray size(writer, "size");
+                        writer.Int(presence->partySize);
+                        writer.Int(presence->partyMax);
+                    }
+
+                    if (presence->partyPrivacy) {
+                        WriteKey(writer, "privacy");
+                        writer.Int(presence->partyPrivacy);
+                    }
+                }
+
+                if ((presence->matchSecret && presence->matchSecret[0]) ||
+                    (presence->joinSecret && presence->joinSecret[0]) ||
+                    (presence->spectateSecret && presence->spectateSecret[0])) {
+                    WriteObject secrets(writer, "secrets");
+                    WriteOptionalString(writer, "match", presence->matchSecret);
+                    WriteOptionalString(writer, "join", presence->joinSecret);
+                    WriteOptionalString(writer, "spectate", presence->spectateSecret);
+                }
+
+                writer.Key("instance");
+                writer.Bool(presence->instance != 0);
+            }
+        }
+    }
+
+    return writer.Size();
+}
+
+size_t JsonWriteHandshakeObj(char* dest, size_t maxLen, int version, const char* applicationId)
+{
+    JsonWriter writer(dest, maxLen);
+
+    {
+        WriteObject obj(writer);
+        WriteKey(writer, "v");
+        writer.Int(version);
+        WriteKey(writer, "client_id");
+        writer.String(applicationId);
+    }
+
+    return writer.Size();
+}
+
+size_t JsonWriteSubscribeCommand(char* dest, size_t maxLen, int nonce, const char* evtName)
+{
+    JsonWriter writer(dest, maxLen);
+
+    {
+        WriteObject obj(writer);
+
+        JsonWriteNonce(writer, nonce);
+
+        WriteKey(writer, "cmd");
+        writer.String("SUBSCRIBE");
+
+        WriteKey(writer, "evt");
+        writer.String(evtName);
+    }
+
+    return writer.Size();
+}
+
+size_t JsonWriteUnsubscribeCommand(char* dest, size_t maxLen, int nonce, const char* evtName)
+{
+    JsonWriter writer(dest, maxLen);
+
+    {
+        WriteObject obj(writer);
+
+        JsonWriteNonce(writer, nonce);
+
+        WriteKey(writer, "cmd");
+        writer.String("UNSUBSCRIBE");
+
+        WriteKey(writer, "evt");
+        writer.String(evtName);
+    }
+
+    return writer.Size();
+}
+
+size_t JsonWriteJoinReply(char* dest, size_t maxLen, const char* userId, int reply, int nonce)
+{
+    JsonWriter writer(dest, maxLen);
+
+    {
+        WriteObject obj(writer);
+
+        WriteKey(writer, "cmd");
+        if (reply == DISCORD_REPLY_YES) {
+            writer.String("SEND_ACTIVITY_JOIN_INVITE");
+        }
+        else {
+            writer.String("CLOSE_ACTIVITY_JOIN_REQUEST");
+        }
+
+        WriteKey(writer, "args");
+        {
+            WriteObject args(writer);
+
+            WriteKey(writer, "user_id");
+            writer.String(userId);
+        }
+
+        JsonWriteNonce(writer, nonce);
+    }
+
+    return writer.Size();
+}

discord-integration/discord-rpc/src/serialization.h

@@ -0,0 +1,215 @@
+#pragma once
+
+#include <stdint.h>
+
+#ifndef __MINGW32__
+#pragma warning(push)
+
+#pragma warning(disable : 4061) // enum is not explicitly handled by a case label
+#pragma warning(disable : 4365) // signed/unsigned mismatch
+#pragma warning(disable : 4464) // relative include path contains
+#pragma warning(disable : 4668) // is not defined as a preprocessor macro
+#pragma warning(disable : 6313) // Incorrect operator
+#endif                          // __MINGW32__
+
+#include "rapidjson/document.h"
+#include "rapidjson/stringbuffer.h"
+#include "rapidjson/writer.h"
+
+#ifndef __MINGW32__
+#pragma warning(pop)
+#endif // __MINGW32__
+
+// if only there was a standard library function for this
+template <size_t Len>
+inline size_t StringCopy(char (&dest)[Len], const char* src)
+{
+    if (!src || !Len) {
+        return 0;
+    }
+    size_t copied;
+    char* out = dest;
+    for (copied = 1; *src && copied < Len; ++copied) {
+        *out++ = *src++;
+    }
+    *out = 0;
+    return copied - 1;
+}
+
+size_t JsonWriteHandshakeObj(char* dest, size_t maxLen, int version, const char* applicationId);
+
+// Commands
+struct DiscordRichPresence;
+size_t JsonWriteRichPresenceObj(char* dest,
+                                size_t maxLen,
+                                int nonce,
+                                int pid,
+                                const DiscordRichPresence* presence);
+size_t JsonWriteSubscribeCommand(char* dest, size_t maxLen, int nonce, const char* evtName);
+
+size_t JsonWriteUnsubscribeCommand(char* dest, size_t maxLen, int nonce, const char* evtName);
+
+size_t JsonWriteJoinReply(char* dest, size_t maxLen, const char* userId, int reply, int nonce);
+
+// I want to use as few allocations as I can get away with, and to do that with RapidJson, you need
+// to supply some of your own allocators for stuff rather than use the defaults
+
+class LinearAllocator {
+public:
+    char* buffer_;
+    char* end_;
+    LinearAllocator()
+    {
+        assert(0); // needed for some default case in rapidjson, should not use
+    }
+    LinearAllocator(char* buffer, size_t size)
+      : buffer_(buffer)
+      , end_(buffer + size)
+    {
+    }
+    static const bool kNeedFree = false;
+    void* Malloc(size_t size)
+    {
+        char* res = buffer_;
+        buffer_ += size;
+        if (buffer_ > end_) {
+            buffer_ = res;
+            return nullptr;
+        }
+        return res;
+    }
+    void* Realloc(void* originalPtr, size_t originalSize, size_t newSize)
+    {
+        if (newSize == 0) {
+            return nullptr;
+        }
+        // allocate how much you need in the first place
+        assert(!originalPtr && !originalSize);
+        // unused parameter warning
+        (void)(originalPtr);
+        (void)(originalSize);
+        return Malloc(newSize);
+    }
+    static void Free(void* ptr)
+    {
+        /* shrug */
+        (void)ptr;
+    }
+};
+
+template <size_t Size>
+class FixedLinearAllocator : public LinearAllocator {
+public:
+    char fixedBuffer_[Size];
+    FixedLinearAllocator()
+      : LinearAllocator(fixedBuffer_, Size)
+    {
+    }
+    static const bool kNeedFree = false;
+};
+
+// wonder why this isn't a thing already, maybe I missed it
+class DirectStringBuffer {
+public:
+    using Ch = char;
+    char* buffer_;
+    char* end_;
+    char* current_;
+
+    DirectStringBuffer(char* buffer, size_t maxLen)
+      : buffer_(buffer)
+      , end_(buffer + maxLen)
+      , current_(buffer)
+    {
+    }
+
+    void Put(char c)
+    {
+        if (current_ < end_) {
+            *current_++ = c;
+        }
+    }
+    void Flush() {}
+    size_t GetSize() const { return (size_t)(current_ - buffer_); }
+};
+
+using MallocAllocator = rapidjson::CrtAllocator;
+using PoolAllocator = rapidjson::MemoryPoolAllocator<MallocAllocator>;
+using UTF8 = rapidjson::UTF8<char>;
+// Writer appears to need about 16 bytes per nested object level (with 64bit size_t)
+using StackAllocator = FixedLinearAllocator<2048>;
+constexpr size_t WriterNestingLevels = 2048 / (2 * sizeof(size_t));
+using JsonWriterBase =
+  rapidjson::Writer<DirectStringBuffer, UTF8, UTF8, StackAllocator, rapidjson::kWriteNoFlags>;
+class JsonWriter : public JsonWriterBase {
+public:
+    DirectStringBuffer stringBuffer_;
+    StackAllocator stackAlloc_;
+
+    JsonWriter(char* dest, size_t maxLen)
+      : JsonWriterBase(stringBuffer_, &stackAlloc_, WriterNestingLevels)
+      , stringBuffer_(dest, maxLen)
+      , stackAlloc_()
+    {
+    }
+
+    size_t Size() const { return stringBuffer_.GetSize(); }
+};
+
+using JsonDocumentBase = rapidjson::GenericDocument<UTF8, PoolAllocator, StackAllocator>;
+class JsonDocument : public JsonDocumentBase {
+public:
+    static const int kDefaultChunkCapacity = 32 * 1024;
+    // json parser will use this buffer first, then allocate more if needed; I seriously doubt we
+    // send any messages that would use all of this, though.
+    char parseBuffer_[32 * 1024];
+    MallocAllocator mallocAllocator_;
+    PoolAllocator poolAllocator_;
+    StackAllocator stackAllocator_;
+    JsonDocument()
+      : JsonDocumentBase(rapidjson::kObjectType,
+                         &poolAllocator_,
+                         sizeof(stackAllocator_.fixedBuffer_),
+                         &stackAllocator_)
+      , poolAllocator_(parseBuffer_, sizeof(parseBuffer_), kDefaultChunkCapacity, &mallocAllocator_)
+      , stackAllocator_()
+    {
+    }
+};
+
+using JsonValue = rapidjson::GenericValue<UTF8, PoolAllocator>;
+
+inline JsonValue* GetObjMember(JsonValue* obj, const char* name)
+{
+    if (obj) {
+        auto member = obj->FindMember(name);
+        if (member != obj->MemberEnd() && member->value.IsObject()) {
+            return &member->value;
+        }
+    }
+    return nullptr;
+}
+
+inline int GetIntMember(JsonValue* obj, const char* name, int notFoundDefault = 0)
+{
+    if (obj) {
+        auto member = obj->FindMember(name);
+        if (member != obj->MemberEnd() && member->value.IsInt()) {
+            return member->value.GetInt();
+        }
+    }
+    return notFoundDefault;
+}
+
+inline const char* GetStrMember(JsonValue* obj,
+                                const char* name,
+                                const char* notFoundDefault = nullptr)
+{
+    if (obj) {
+        auto member = obj->FindMember(name);
+        if (member != obj->MemberEnd() && member->value.IsString()) {
+            return member->value.GetString();
+        }
+    }
+    return notFoundDefault;
+}