Allow external native plug-ins to interact wit the script.

Very primitive mechanism but better than nothing.

module/CMakeLists.txt

@@ -1,5 +1,7 @@
 # Create the Squirrel module
 add_library(SqModule MODULE SqBase.hpp Main.cpp
+    # SDK
+    SDK/sqmod.h
     # VCMP
     VCMP/vcmp.h
     VCMP/vcmp20.h
@@ -114,6 +116,7 @@ add_library(SqModule MODULE SqBase.hpp Main.cpp
     Core.cpp Core.hpp
     Logger.cpp Logger.hpp
     Register.cpp
+    Exports.cpp
 )
 # Various definitions required by the plug-in
 target_compile_definitions(SqModule PRIVATE SCRAT_USE_EXCEPTIONS=1)
@@ -201,6 +204,7 @@ else(WIN32)
 endif(WIN32)
 # Include current directory in the search path
 target_include_directories(SqModule PRIVATE ${CMAKE_CURRENT_LIST_DIR})
+target_include_directories(SqModule PRIVATE ${CMAKE_CURRENT_LIST_DIR}/SDK)
 target_include_directories(SqModule PRIVATE ${CMAKE_CURRENT_LIST_DIR}/VCMP)
 target_include_directories(SqModule PRIVATE ${CMAKE_CURRENT_LIST_DIR}/Sqrat)
 # Include PCRE directory in the header search path
@@ -222,7 +226,7 @@ if(WIN32 AND MINGW AND COPY_DEPENDENCIES)
     endif()
     # Make sure the deps folder exists
     file(MAKE_DIRECTORY "${PROJECT_SOURCE_DIR}/bin/deps")
-    # Copy dependencies into the plug-ins folder (only so it can be distributed with the DLL)
+    # Copy dependencies into the deps folder (only so it can be distributed with the DLL)
     file(COPY "${MINGW_BIN_PATH}/zlib1.dll" DESTINATION "${PROJECT_SOURCE_DIR}/bin/deps")
     file(COPY "${MINGW_BIN_PATH}/libpq.dll" DESTINATION "${PROJECT_SOURCE_DIR}/bin/deps")
     file(COPY "${MINGW_BIN_PATH}/libzstd.dll" DESTINATION "${PROJECT_SOURCE_DIR}/bin/deps")
@@ -245,17 +249,17 @@ if(WIN32 AND MINGW AND COPY_DEPENDENCIES)
     file(COPY "${MINGW_BIN_PATH}/libp11-kit-0.dll" DESTINATION "${PROJECT_SOURCE_DIR}/bin/deps")
     file(COPY "${MINGW_BIN_PATH}/libbrotlidec.dll" DESTINATION "${PROJECT_SOURCE_DIR}/bin/deps")
     file(COPY "${MINGW_BIN_PATH}/libbrotlicommon.dll" DESTINATION "${PROJECT_SOURCE_DIR}/bin/deps")
-    file(COPY "${MINGW_BIN_PATH}/libunistring-2.dll" DESTINATION "${PROJECT_SOURCE_DIR}/bin/deps")
+    file(COPY "${MINGW_BIN_PATH}/libunistring-5.dll" DESTINATION "${PROJECT_SOURCE_DIR}/bin/deps")
     file(COPY "${MINGW_BIN_PATH}/libnghttp2-14.dll" DESTINATION "${PROJECT_SOURCE_DIR}/bin/deps")
     file(COPY "${MINGW_BIN_PATH}/libwinpthread-1.dll" DESTINATION "${PROJECT_SOURCE_DIR}/bin/deps")
     file(COPY "${MINGW_BIN_PATH}/libstdc++-6.dll" DESTINATION "${PROJECT_SOURCE_DIR}/bin/deps")
     if(CMAKE_SIZEOF_VOID_P EQUAL 8 AND NOT FORCE_32BIT_BIN)
         file(COPY "${MINGW_BIN_PATH}/libgcc_s_seh-1.dll" DESTINATION "${PROJECT_SOURCE_DIR}/bin/deps")
-        file(COPY "${MINGW_BIN_PATH}/libssl-1_1-x64.dll" DESTINATION "${PROJECT_SOURCE_DIR}/bin/deps")
+        file(COPY "${MINGW_BIN_PATH}/libssl-3-x64.dll" DESTINATION "${PROJECT_SOURCE_DIR}/bin/deps")
-        file(COPY "${MINGW_BIN_PATH}/libcrypto-1_1-x64.dll" DESTINATION "${PROJECT_SOURCE_DIR}/bin/deps")
+        file(COPY "${MINGW_BIN_PATH}/libcrypto-3-x64.dll" DESTINATION "${PROJECT_SOURCE_DIR}/bin/deps")
     else()
-        file(COPY "${MINGW_BIN_PATH}/libssl-1_1.dll" DESTINATION "${PROJECT_SOURCE_DIR}/bin/deps")
+        file(COPY "${MINGW_BIN_PATH}/libssl-3.dll" DESTINATION "${PROJECT_SOURCE_DIR}/bin/deps")
-        file(COPY "${MINGW_BIN_PATH}/libcrypto-1_1.dll" DESTINATION "${PROJECT_SOURCE_DIR}/bin/deps")
+        file(COPY "${MINGW_BIN_PATH}/libcrypto-3.dll" DESTINATION "${PROJECT_SOURCE_DIR}/bin/deps")
     endif()
     if(POCO_UNBUNDLED)
         file(COPY "${MINGW_BIN_PATH}/libexpat-1.dll" DESTINATION "${PROJECT_SOURCE_DIR}/bin/deps")

module/Core.cpp

@@ -161,6 +161,7 @@ Core::Core() noexcept
     , m_Scripts()
     , m_PendingScripts()
     , m_Options()
+    , m_ExtCommands{nullptr, nullptr, nullptr, nullptr}
     , m_Blips()
     , m_Checkpoints()
     , m_KeyBinds()
@@ -441,9 +442,9 @@ bool Core::Execute()
     m_LockPostLoadSignal = false;
     m_LockUnloadSignal = false;
 
-    //cLogDbg(m_Verbosity >= 1, "Signaling outside plug-ins to register their API");
+    cLogDbg(m_Verbosity >= 1, "Signaling outside plug-ins that the API is being registered");
     // Tell modules to do their monkey business
-    //_Func->SendPluginCommand(0xDEADBABE, "");
+    _Func->SendPluginCommand(0xDEADBABE, "");
 
     // Load pending scripts while we're in the bounds of the allowed recursiveness
     for (unsigned levels = 0; !m_PendingScripts.empty() && (levels < 8); ++levels)
@@ -511,9 +512,9 @@ void Core::Terminate(bool shutdown)
         // Clear the callbacks
         ResetSignalPair(mOnUnload);
 
-        //cLogDbg(m_Verbosity >= 1, "Signaling outside plug-ins to release their resources");
+        cLogDbg(m_Verbosity >= 1, "Signaling outside plug-ins to release their resources");
         // Tell modules to do their monkey business
-        //_Func->SendPluginCommand(0xDEADC0DE, "");
+        _Func->SendPluginCommand(0xDEADC0DE, "");
     }
 
     cLogDbg(m_Verbosity >= 1, "Clearing the entity containers");
@@ -596,9 +597,9 @@ void Core::Terminate(bool shutdown)
         HSQUIRRELVM sq_vm = m_VM;
         m_VM = nullptr;
 
-        //cLogDbg(m_Verbosity >= 1, "Signaling outside plug-ins the virtual machine is closing");
+        cLogDbg(m_Verbosity >= 1, "Signaling outside plug-ins the virtual machine is closing");
         // Tell modules to do their monkey business
-        //_Func->SendPluginCommand(0xBAAAAAAD, "");
+        _Func->SendPluginCommand(0xBAAAAAAD, "");
         // Release any callbacks from the logger
         Logger::Get().Release();
         cLogDbg(m_Verbosity >= 2, "Closing Virtual Machine");
@@ -629,9 +630,9 @@ void Core::Terminate(bool shutdown)
         // Destroy the VM context, if any
         delete ctx;
 
-        //cLogDbg(m_Verbosity >= 1, "Signaling outside plug-ins to release the virtual machine");
+        cLogDbg(m_Verbosity >= 1, "Signaling outside plug-ins the virtual machine was closed");
         // Tell modules to do their monkey business
-        //_Func->SendPluginCommand(0xDEADBEAF, "");
+        _Func->SendPluginCommand(0xDEADBEAF, "");
     }
 
     OutputMessage("Squirrel plug-in was successfully terminated");
@@ -904,6 +905,81 @@ String Core::FetchCodeLine(const SQChar * src, SQInteger line, bool trim)
     return script->FetchLine(line, trim);
 }
 
+// ------------------------------------------------------------------------------------------------
+int32_t Core::RegisterExtCommand(ExtPluginCommand_t fn)
+{
+    ExtPluginCommand_t * slot = nullptr;
+    // Find a free slot or matching function pointer in the pool
+    for (size_t i = 0; i < m_ExtCommands.max_size(); ++i)
+    {
+        // Is this slot available and are we still looking for a slot?
+        if (m_ExtCommands[i] == nullptr && slot == nullptr)
+        {
+            slot = &m_ExtCommands[i]; // Found a slot
+        }
+        // We keep looking for duplicates even if we found the slot
+        else if (m_ExtCommands[i] == fn)
+        {
+            return 0; // Already registered
+        }
+    }
+    // Do we have a free slot?
+    if (slot != nullptr)
+    {
+        *slot = fn; // Use this slot
+        return 1; // Successfully registered
+    }
+    // No space in the pool
+    return -1;
+}
+
+// ------------------------------------------------------------------------------------------------
+int32_t Core::UnregisterExtCommand(ExtPluginCommand_t fn)
+{
+    // Find the matching function pointer
+    for (size_t i = 0; i < m_ExtCommands.max_size(); ++i)
+    {
+        // Is this the same pointer?
+        if (m_ExtCommands[i] != nullptr && m_ExtCommands[i] == fn)
+        {
+            // Forget about it
+            m_ExtCommands[i] = nullptr;
+            return 1; // Successfully unregistered
+        }
+    }
+    // No space
+    return -1;
+}
+
+// ------------------------------------------------------------------------------------------------
+int32_t Core::SendExtCommand(int32_t target, int32_t req, int32_t tag, const uint8_t * data, size_t size)
+{
+    int32_t count = 0;
+    // Send the command to all registered function pointers
+    for (size_t i = 0; i < m_ExtCommands.max_size(); ++i)
+    {
+        if (m_ExtCommands[i] != nullptr)
+        {
+            const int32_t r = m_ExtCommands[i](target, req, tag, data, size);
+            // Command processed
+            ++count;
+            // Command failed?
+            if (r < 0)
+            {
+                LogErr("External command failed (%i): target(%i), req(%i), tag(%i), data(%p), size (%zu)",
+                        r, target, req, tag, data, size);
+            }
+            // Command consumed?
+            else if (r > 0)
+            {
+                break; // This function pointer requested exclusive access over this command
+            }
+        }
+    }
+    // Return how many function pointers received this command
+    return count;
+}
+
 // ------------------------------------------------------------------------------------------------
 bool Core::DoScripts(Scripts::iterator itr, Scripts::iterator end)
 {
@@ -2371,6 +2447,8 @@ void Core::InitEvents()
     InitSignalPair(mOnServerOption, m_Events, "ServerOption");
     InitSignalPair(mOnScriptReload, m_Events, "ScriptReload");
     InitSignalPair(mOnScriptLoaded, m_Events, "ScriptLoaded");
+    InitSignalPair(mOnExtCommandReply, m_Events, "ExtCommandReply");
+    InitSignalPair(mOnExtCommandEvent, m_Events, "ExtCommandEvent");
 }
 // ------------------------------------------------------------------------------------------------
 void Core::DropEvents()
@@ -2516,6 +2594,8 @@ void Core::DropEvents()
     ResetSignalPair(mOnServerOption);
     ResetSignalPair(mOnScriptReload);
     ResetSignalPair(mOnScriptLoaded);
+    ResetSignalPair(mOnExtCommandReply);
+    ResetSignalPair(mOnExtCommandEvent);
     m_Events.Release();
 }
 
@@ -2861,6 +2941,31 @@ static LightObj & SqGetClientDataBuffer()
     return Core::Get().GetClientDataBuffer();
 }
 
+// ------------------------------------------------------------------------------------------------
+static SQInteger SqSendExtCommand(int32_t target, int32_t req, int32_t tag, SqBuffer & buffer)
+{
+    // Default to an empty/null buffer
+    const uint8_t * data = nullptr;
+    size_t size = 0;
+    // Does the buffer actually point to anything?
+    if (buffer.GetRef())
+    {
+        data = buffer.GetRef()->Begin< uint8_t >();
+        size = buffer.GetRef()->PositionAs< size_t >();
+    }
+    // Forward the request
+    return Core::Get().SendExtCommand(target, req, tag, data, size);
+}
+
+// ------------------------------------------------------------------------------------------------
+static SQInteger SqSendExtCommandStr(int32_t target, int32_t req, int32_t tag, StackStrF & str)
+{
+    // Forward the request
+    return Core::Get().SendExtCommand(target, req, tag,
+                                        reinterpret_cast< const uint8_t * >(str.mPtr),
+                                        str.mLen <= 0 ? 0 : static_cast< size_t >(str.mLen));
+}
+
 // ================================================================================================
 void Register_Core(HSQUIRRELVM vm)
 {
@@ -2910,6 +3015,8 @@ void Register_Core(HSQUIRRELVM vm)
         .Func(_SC("DestroyPickup"), &SqDelPickup)
         .Func(_SC("DestroyVehicle"), &SqDelVehicle)
         .Func(_SC("ClientDataBuffer"), &SqGetClientDataBuffer)
+        .Func(_SC("SendExtCommand"), &SqSendExtCommand)
+        .FmtFunc(_SC("SendExtCommandStr"), &SqSendExtCommandStr)
         .Func(_SC("OnPreLoad"), &SqGetPreLoadEvent)
         .Func(_SC("OnPostLoad"), &SqGetPostLoadEvent)
         .Func(_SC("OnUnload"), &SqGetUnloadEvent)

module/Core.hpp

@@ -9,6 +9,9 @@
 // ------------------------------------------------------------------------------------------------
 #include <unordered_map>
 
+// ------------------------------------------------------------------------------------------------
+#include "SDK/sqmod.h"
+
 // ------------------------------------------------------------------------------------------------
 namespace SqMod {
 
@@ -56,6 +59,8 @@ public:
     typedef std::vector< ScriptSrc >                Scripts; // List of loaded scripts.
     // --------------------------------------------------------------------------------------------
     typedef std::unordered_map< String, String >    Options; // List of custom options.
+    // --------------------------------------------------------------------------------------------
+    typedef std::array< ExtPluginCommand_t, 4 > ExtCommands; // 4 external command parsers should be enough.
 
 private:
 
@@ -68,6 +73,7 @@ private:
     Scripts                         m_Scripts; // Loaded scripts objects.
     Scripts                         m_PendingScripts; // Pending scripts objects.
     Options                         m_Options; // Custom configuration options.
+    ExtCommands                     m_ExtCommands; // External command parsers pointers.
 
     // --------------------------------------------------------------------------------------------
     Blips                           m_Blips; // Blips pool.
@@ -399,6 +405,23 @@ public:
     */
     SQMOD_NODISCARD String FetchCodeLine(const SQChar * src, SQInteger line, bool trim = true);
 
+    /* --------------------------------------------------------------------------------------------
+     * Register a pointer to a function used to processes commands from script.
+     * Returns -1 it failed (no free slot), 0 if it was already registered and 1 if it succeeded.
+    */
+    int32_t RegisterExtCommand(ExtPluginCommand_t fn);
+
+    /* --------------------------------------------------------------------------------------------
+     * Remove a pointer to a function used to processes commands from script.
+     * Returns -1 it failed (no free slot) and 1 if it succeeded.
+    */
+    int32_t UnregisterExtCommand(ExtPluginCommand_t fn);
+
+    /* --------------------------------------------------------------------------------------------
+     * Send a command to all functions currently registered to receive them.
+    */
+    int32_t SendExtCommand(int32_t target, int32_t req, int32_t tag, const uint8_t * data, size_t size);
+
 protected:
 
     /* --------------------------------------------------------------------------------------------
@@ -710,6 +733,16 @@ public:
     */
     void EmitClientScriptData(int32_t player_id, const uint8_t * data, size_t size);
 
+    /* --------------------------------------------------------------------------------------------
+     * Send a response to the script that may have resulted from a previous command.
+    */
+    void EmitExtCommandReply(int32_t sender, int32_t tag, const uint8_t * data, size_t size);
+
+    /* --------------------------------------------------------------------------------------------
+     * Forward an event to the script from an external plug-in.
+    */
+    void EmitExtCommandEvent(int32_t sender, int32_t tag, const uint8_t * data, size_t size);
+
 public:
 
     /* --------------------------------------------------------------------------------------------
@@ -864,6 +897,8 @@ public:
     SignalPair  mOnServerOption{};
     SignalPair  mOnScriptReload{};
     SignalPair  mOnScriptLoaded{};
+    SignalPair  mOnExtCommandReply{};
+    SignalPair  mOnExtCommandEvent{};
 };
 
 /* ------------------------------------------------------------------------------------------------

module/Core/Events.inc

@@ -347,7 +347,7 @@ void Core::EmitIncomingConnection(char * player_name, size_t name_buffer_size, c
         // Release any stored buffer information
         m_IncomingNameBuffer = nullptr;
         m_IncomingNameCapacity = 0;
-        // We catched the exception so we can release the assigned buffer
+        // We caught the exception so we can release the assigned buffer
         throw; // re-throw it
     }
     // Release any stored buffer information
@@ -2246,6 +2246,44 @@ void Core::EmitClientScriptData(int32_t player_id, const uint8_t * data, size_t
     m_ClientData.Release();
 }
 
+// ------------------------------------------------------------------------------------------------
+void Core::EmitExtCommandReply(int32_t sender, int32_t tag, const uint8_t * data, size_t size)
+{
+    SQMOD_CO_EV_TRACEBACK("[TRACE<] Core::ExtCommandReply(%i, %i, %p, %zu)", sender, tag, data, size)
+    // Don't even bother if there's no one listening
+    if (!(mOnExtCommandReply.first->IsEmpty()))
+    {
+        // Allocate a buffer with the received size
+        Buffer b(static_cast< Buffer::SzType >(size));
+        // Replicate the data to the allocated buffer
+        b.Write(0, reinterpret_cast< Buffer::ConstPtr >(data), static_cast< Buffer::SzType >(size));
+        // Prepare an object for the obtained buffer
+        LightObj obj(SqTypeIdentity< SqBuffer >{}, m_VM, std::move(b));
+        // Forward the event call
+        (*mOnExtCommandReply.first)(sender, tag, obj, size);
+    }
+    SQMOD_CO_EV_TRACEBACK("[TRACE>] Core::ExtCommandReply")
+}
+
+// ------------------------------------------------------------------------------------------------
+void Core::EmitExtCommandEvent(int32_t sender, int32_t tag, const uint8_t * data, size_t size)
+{
+    SQMOD_CO_EV_TRACEBACK("[TRACE<] Core::ExtCommandEvent(%i, %i, %p, %zu)", sender, tag, data, size)
+    // Don't even bother if there's no one listening
+    if (!(mOnExtCommandEvent.first->IsEmpty()))
+    {
+        // Allocate a buffer with the received size
+        Buffer b(static_cast< Buffer::SzType >(size));
+        // Replicate the data to the allocated buffer
+        b.Write(0, reinterpret_cast< Buffer::ConstPtr >(data), static_cast< Buffer::SzType >(size));
+        // Prepare an object for the obtained buffer
+        LightObj obj(SqTypeIdentity< SqBuffer >{}, m_VM, std::move(b));
+        // Forward the event call
+        (*mOnExtCommandEvent.first)(sender, tag, obj, size);
+    }
+    SQMOD_CO_EV_TRACEBACK("[TRACE>] Core::ExtCommandEvent")
+}
+
 #undef NULL_SQOBJ_ // don't need this anymore
 
 } // Namespace:: SqMod

module/Exports.cpp

@@ -0,0 +1,73 @@
+// ------------------------------------------------------------------------------------------------
+#include "Core.hpp"
+
+// ------------------------------------------------------------------------------------------------
+#include <cstring>
+
+// ------------------------------------------------------------------------------------------------
+#include <sqmod.h>
+
+// ------------------------------------------------------------------------------------------------
+namespace SqMod {
+
+// ------------------------------------------------------------------------------------------------
+static int32_t RegisterCommandFn(ExtPluginCommand_t fn)
+{
+    return Core::Get().RegisterExtCommand(fn);
+}
+
+// ------------------------------------------------------------------------------------------------
+static int32_t UnregisterCommandFn(ExtPluginCommand_t fn)
+{
+    return Core::Get().UnregisterExtCommand(fn);
+}
+
+// ------------------------------------------------------------------------------------------------
+static int32_t SendCommandFn(int32_t target, int32_t req, int32_t tag, const uint8_t * data, size_t size)
+{
+    return Core::Get().SendExtCommand(target, req, tag, data, size);
+}
+
+// ------------------------------------------------------------------------------------------------
+static int32_t SendCommandReplyFn(int32_t sender, int32_t tag, const uint8_t * data, size_t size)
+{
+    // Mark the initialization as successful by default
+    const CoreState cs(SQMOD_SUCCESS);
+    // Forward the call to the script callbacks
+    Core::Get().EmitExtCommandReply(sender, tag, data, size);
+    // Return the last known plug-in state
+    return Core::Get().GetState();
+}
+
+// ------------------------------------------------------------------------------------------------
+static int32_t SendCommandEventFn(int32_t sender, int32_t tag, const uint8_t * data, size_t size)
+{
+    // Mark the initialization as successful by default
+    const CoreState cs(SQMOD_SUCCESS);
+    // Forward the call to the script callbacks
+    Core::Get().EmitExtCommandEvent(sender, tag, data, size);
+    // Return the last known plug-in state
+    return Core::Get().GetState();
+}
+
+// ------------------------------------------------------------------------------------------------
+static const SQ_MOD_EXPORTS g_SqModExports{
+    sizeof(SQ_MOD_EXPORTS),
+    &RegisterCommandFn,
+    &UnregisterCommandFn,
+    &SendCommandFn,
+    &SendCommandReplyFn,
+    &SendCommandEventFn
+};
+
+// The server needs a pointer to a pointer, and a persistent one
+static const SQ_MOD_EXPORTS * g_SqModExportsPtr = &g_SqModExports;
+
+// ------------------------------------------------------------------------------------------------
+void InitExports()
+{
+    // Tell the server about the pointer to the exports structure
+    _Func->ExportFunctions(_Info->pluginId, reinterpret_cast< const void ** >(&g_SqModExportsPtr), sizeof(HSQ_MOD_EXPORTS));
+}
+
+} // Namespace:: SqMod

module/Main.cpp

@@ -17,7 +17,7 @@ namespace SqMod {
 static bool g_Reload = false;
 
 // ------------------------------------------------------------------------------------------------
-//extern void InitExports();
+extern void InitExports();
 extern void InitializeNet();
 extern void InitializePocoDataConnectors();
 extern void ProcessRoutines();
@@ -1083,7 +1083,7 @@ SQMOD_API_EXPORT unsigned int VcmpPluginInit(PluginFuncs * funcs, PluginCallback
     _Clbk->OnEntityStreamingChange      = OnEntityStreamingChange;
 #endif
     // Attempt to initialize the plug-in exports
-    //InitExports();
+    InitExports();
     // Dummy spacing
     puts("");
     // Initialization was successful

module/Register.cpp

@@ -1,6 +1,3 @@
-#ifndef _REGISTER_HPP_
-#define _REGISTER_HPP_
-
 // ------------------------------------------------------------------------------------------------
 #include <squirrelex.h>
 
@@ -144,5 +141,3 @@ bool RegisterAPI(HSQUIRRELVM vm)
 }
 
 } // Namespace:: SqMod
-
-#endif // _REGISTER_HPP_

module/SDK/sqmod.h

@@ -0,0 +1,75 @@
+#if !defined(_SQ_MOD_API_H_)
+#define _SQ_MOD_API_H_
+
+#include <stdint.h>
+#include <stdlib.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif // __cplusplus
+
+    #ifndef SQMOD_API_EXPORT
+        #if defined(_MSC_VER)
+            #define SQMOD_API_EXPORT    extern "C" __declspec(dllexport)
+        #elif defined(__GNUC__)
+            #define SQMOD_API_EXPORT    extern "C"
+        #else
+            #define SQMOD_API_EXPORT    extern "C"
+        #endif
+    #endif
+
+    #define SQMOD_HOST_NAME         "SqModHost"
+    #define SQMOD_INITIALIZE_CMD    0xDABBAD00
+    #define SQMOD_LOAD_CMD          0xDEADBABE // API is being registered
+    #define SQMOD_TERMINATE_CMD     0xDEADC0DE // release your resources
+    #define SQMOD_CLOSING_CMD       0xBAAAAAAD // virtual machine is closing
+    #define SQMOD_RELEASED_CMD      0xDEADBEAF // virtual machine was closed
+    #define SQMOD_API_VER           1
+
+    // --------------------------------------------------------------------------------------------
+    typedef int32_t(*ExtPluginCommand_t)(int32_t, int32_t,  int32_t, const uint8_t *, size_t);
+
+    /* --------------------------------------------------------------------------------------------
+     * The structure exported by the host plug-in to import the module and squirrel API.
+    */
+    typedef struct
+    {
+        uint32_t StructSize;
+        /* Register a pointer to a function used to processes commands from script.
+            This is like the functionality offered by SendPluginCommand but offers interaction from
+            script side without interfering with other native plugins. And also offers a few extra
+            methods of identification to provide back and forth communication.
+            It offers a bare minimum, primitive way of interacting with the script from native plug-ins.
+            return : -1 it failed (no free slot), 0 if it was already registered and 1 if it succeeded.
+        */
+        int32_t (*RegisterCommand) (ExtPluginCommand_t fn);
+        /* Remove a pointer to a function used to processes commands from script.
+            return : -1 it failed (no free slot) and 1 if it succeeded.
+        */
+        int32_t (*UnregisterCommand) (ExtPluginCommand_t fn);
+        /* Send a command to all functions currently registered to receive them. This is mostly used by the script.
+            target - ideally a unique value that can be used to identify the intended audience for the command.
+            req : ideally a unique value that can be used to identify the requested information from the command.
+            tag : ideally a unique value that can be used to identify a later response if one is generated.
+            data : binary data that represents the command payload. the command is free to interpret it however it wants.
+            size :  size of the binary data. most likely in bytes but the command is free to interpret it however it wants.
+        */
+        int32_t (*SendCommand) (int32_t target, int32_t req, int32_t tag, const uint8_t * data, size_t size);
+        /* Send a response to the script that may have resulted from a previous command. This is mostly by the native plug-ins.
+            sender : ideally a unique value that can be used to identify the intended who generated the response.
+            tag : ideally a unique value that can be used to identify what the generated response might contain/provide.
+            data : binary data that represents the command payload. the command is free to interpret it however it wants.
+            size :  size of the binary data. most likely in bytes but the command is free to interpret it however it wants.
+        */
+        int32_t (*SendCommandReply) (int32_t sender, int32_t tag, const uint8_t * data, size_t size);
+        /* Forward an event to the script from an external plug-in. This is mostly by the native plug-ins.
+            Similar to SendCommandReply but may not have been the result of a previous command.
+        */
+        int32_t (*SendCommandEvent) (int32_t sender, int32_t tag, const uint8_t * data, size_t size);
+    } sq_mod_exports, SQ_MOD_EXPORTS, *HSQ_MOD_EXPORTS;
+
+#ifdef __cplusplus
+} /*extern "C"*/
+#endif // __cplusplus
+
+#endif /*_SQ_MOD_API_H_*/