Make loading modules considerably more robust and user friendly.

8 files changed, 147 insertions, 95 deletions

diff --git a/include/dynamic.h b/include/dynamic.h
index 703120fc0..3a312a382 100644
--- a/include/dynamic.h
+++ b/include/dynamic.h
@@ -30,35 +30,34 @@
  */
 class CoreExport DLLManager : public classbase
 {
- protected:
-	/** The last error string
-	 */
+ private:
+	/** The last error string. */
 	std::string err;
 
-	/** Sets the last error string
-	*/
+	/** The module library handle. */
+#ifdef _WIN32
+	HMODULE lib;
+#else
+	void* lib;
+#endif
+
+	/** The filename of the module library. */
+	const std::string libname;
+
+	/** Sets the last error string. */
 	void RetrieveLastError();
 
  public:
-	/** This constructor loads the module using dlopen()
-	 * @param fname The filename to load. This should be within
-	 * the modules dir.
-	 */
-	DLLManager(const char *fname);
-	virtual ~DLLManager();
-
-	/** Get the last error from dlopen() or dlsym().
+	/** Attempts to load the specified module.
+	 * @param name The name of the library to load.
 	 */
-	const std::string& LastError()
-	{
-		 return err;
-	}
+	DLLManager(const std::string& name);
 
-	/** The module library handle.
-	 */
-	void *h;
+	/** Unloads the module if one was loaded. */
+	~DLLManager();
 
-	/** Return a module by calling the init function
+	/** Attempts to create a new module instance from this shared library.
+	 * @return Either a new instance of the Module class or NULL on error.
 	 */
 	Module* CallInit();
 
@@ -66,8 +65,24 @@ class CoreExport DLLManager : public classbase
 	 * @param name The name of the symbol to retrieve.
 	 * @return Either the value of the specified symbol or or NULL if it does not exist.
 	 */
-	void* GetSymbol(const char* name);
+	void* GetSymbol(const char* name) const;
+
+	/** Retrieves the value of the specified symbol and casts it to the requested type.
+	 * @param name The name of the symbol to retrieve.
+	 * @return Either the value of the specified symbol or or NULL if it does not exist.
+	 */
+	template <typename TReturn>
+	TReturn* GetSymbol(const char* name) const
+	{
+		return static_cast<TReturn*>(GetSymbol(name));
+	}
+
+	/** Retrieves the module version from the dynamic library. */
+	const char* GetVersion() const { return GetSymbol<const char>(MODULE_STR_VERSION); }
+
+	/** Retrieves the last error which occurred or an empty string if no errors have occurred. */
+	const std::string& LastError() const { return err; }
 
-	/** Get detailed version information from the module file */
-	std::string GetVersion();
+	/** Retrieves the filename of the underlying shared library. */
+	const std::string& LibraryName() const { return libname; }
 };
diff --git a/include/moduledefs.h b/include/moduledefs.h
new file mode 100644
index 000000000..a2bac63cb
--- /dev/null
+++ b/include/moduledefs.h
@@ -0,0 +1,47 @@
+/*
+ * InspIRCd -- Internet Relay Chat Daemon
+ *
+ *   Copyright (C) 2020 Sadie Powell <sadie@witchery.services>
+ *
+ * This file is part of InspIRCd.  InspIRCd is free software: you can
+ * redistribute it and/or modify it under the terms of the GNU General Public
+ * License as published by the Free Software Foundation, version 2.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+ * FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more
+ * details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+
+#pragma once
+
+class Module;
+
+/** The version of the InspIRCd ABI which is presently in use. */
+#define MODULE_ABI 3010
+
+/** Stringifies the value of a symbol. */
+#define MODULE_STRINGIFY_SYM1(DEF) MODULE_STRINGIFY_SYM2(DEF)
+#define MODULE_STRINGIFY_SYM2(DEF) #DEF
+
+/** The name of the symbol which contains the ABI that a module was compiled against. */
+#define MODULE_SYM_ABI inspircd_module_abi
+#define MODULE_STR_ABI MODULE_STRINGIFY_SYM1(MODULE_SYM_ABI)
+
+/** The name of the symbol which creates a new Module instance. */
+#define MODULE_SYM_INIT inspircd_module_init
+#define MODULE_STR_INIT MODULE_STRINGIFY_SYM1(MODULE_SYM_INIT)
+
+/** The name of the symbol which contains the version that a module was compiled against. */
+#define MODULE_SYM_VERSION inspircd_module_version
+#define MODULE_STR_VERSION MODULE_STRINGIFY_SYM1(MODULE_SYM_VERSION)
+
+/** Defines the interface that a shared library must expose in order to be a module. */
+#define MODULE_INIT(klass) \
+	extern "C" DllExport const uint32_t MODULE_SYM_ABI = MODULE_ABI; \
+	extern "C" DllExport const char MODULE_SYM_VERSION[] = INSPIRCD_VERSION; \
+	extern "C" DllExport Module* MODULE_SYM_INIT() { return new klass; }
diff --git a/include/modules.h b/include/modules.h
index 1c1f4a3ae..5e0c9ab07 100644
--- a/include/modules.h
+++ b/include/modules.h
@@ -30,13 +30,11 @@
 
 #pragma once
 
+#include "moduledefs.h"
 #include "dynamic.h"
 #include "base.h"
 #include "ctables.h"
 #include "inspsocket.h"
-#include <string>
-#include <deque>
-#include <sstream>
 #include "timer.h"
 #include "mode.h"
 
@@ -101,19 +99,6 @@ struct ModResult {
 	}
 };
 
-/** InspIRCd major version.
- * 1.2 -> 102; 2.1 -> 201; 2.12 -> 212
- */
-#define INSPIRCD_VERSION_MAJ 300
-
-/** InspIRCd API version.
- * If you change any API elements, increment this value. This counter should be
- * reset whenever the major version is changed. Modules can use these two values
- * and numerical comparisons in preprocessor macros if they wish to support
- * multiple versions of InspIRCd in one file.
- */
-#define INSPIRCD_VERSION_API 9
-
 /**
  * This #define allows us to call a method in all
  * loaded modules in a readable simple way, e.g.:
@@ -1190,24 +1175,3 @@ class CoreExport ModuleManager : public fakederef<ModuleManager>
 	 */
 	void DelReferent(ServiceProvider* service);
 };
-
-/** Do not mess with these functions unless you know the C preprocessor
- * well enough to explain why they are needed. The order is important.
- */
-#define MODULE_INIT_STR MODULE_INIT_STR_FN_2(MODULE_INIT_SYM)
-#define MODULE_INIT_STR_FN_2(x) MODULE_INIT_STR_FN_1(x)
-#define MODULE_INIT_STR_FN_1(x) #x
-#define MODULE_INIT_SYM MODULE_INIT_SYM_FN_2(INSPIRCD_VERSION_MAJ, INSPIRCD_VERSION_API)
-#define MODULE_INIT_SYM_FN_2(x,y) MODULE_INIT_SYM_FN_1(x,y)
-#define MODULE_INIT_SYM_FN_1(x,y) inspircd_module_ ## x ## _ ## y
-
-/** This definition is used as shorthand for the various classes
- * and functions needed to make a module loadable by the OS.
- * It defines the class factory and external init_module function.
- */
-#define MODULE_INIT(y) \
-	extern "C" DllExport Module * MODULE_INIT_SYM() \
-	{ \
-		return new y; \
-	} \
-	extern "C" DllExport const char inspircd_src_version[] = INSPIRCD_VERSION;
diff --git a/src/coremods/core_info/cmd_modules.cpp b/src/coremods/core_info/cmd_modules.cpp
index 7c9e49550..7936a34d7 100644
--- a/src/coremods/core_info/cmd_modules.cpp
+++ b/src/coremods/core_info/cmd_modules.cpp
@@ -76,8 +76,8 @@ CmdResult CommandModules::Handle(User* user, const Params& parameters)
 				if (!(V.Flags & mult))
 					flags[pos] = '-';
 
-			std::string srcrev = m->ModuleDLLManager->GetVersion();
-			user->WriteRemoteNumeric(RPL_MODLIST, m->ModuleSourceFile, srcrev.empty() ? "*" : srcrev, flags, V.description);
+			const char* srcrev = m->ModuleDLLManager->GetVersion();
+			user->WriteRemoteNumeric(RPL_MODLIST, m->ModuleSourceFile, srcrev ? "*" : srcrev, flags, V.description);
 		}
 		else
 		{
diff --git a/src/dynamic.cpp b/src/dynamic.cpp
index a6f758d33..a3ba43ff2 100644
--- a/src/dynamic.cpp
+++ b/src/dynamic.cpp
@@ -26,62 +26,89 @@
 
 
 #include "inspircd.h"
-
 #ifndef _WIN32
-#include <dlfcn.h>
-#else
-#define dlopen(path, state) (void*)LoadLibraryA(path)
-#define dlsym(handle, export) (void*)GetProcAddress((HMODULE)handle, export)
-#define dlclose(handle) FreeLibrary((HMODULE)handle)
+# include <dlfcn.h>
 #endif
 
-DLLManager::DLLManager(const char *fname)
+/** The extension that dynamic libraries end with. */
+#define DLL_EXTENSION ".so"
+
+DLLManager::DLLManager(const std::string& name)
+	: lib(NULL)
+	, libname(name)
 {
-	if (!strstr(fname,".so"))
+	static size_t extlen = strlen(DLL_EXTENSION);
+	if (name.length() <= extlen || name.compare(name.length() - extlen, name.length(), DLL_EXTENSION))
 	{
-		err = "This doesn't look like a module file to me...";
-		h = NULL;
+		err.assign(name + " is not a module (no " DLL_EXTENSION " extension)");
 		return;
 	}
 
-	h = dlopen(fname, RTLD_NOW|RTLD_LOCAL);
-	if (!h)
-	{
+#ifdef _WIN32
+	lib = LoadLibraryA(name.c_str());
+#else
+	lib = dlopen(name.c_str(), RTLD_NOW|RTLD_LOCAL);
+#endif
+
+	if (!lib)
 		RetrieveLastError();
-	}
 }
 
 DLLManager::~DLLManager()
 {
-	/* close the library */
-	if (h)
-		dlclose(h);
+	if (!lib)
+		return;
+
+#ifdef _WIN32
+	FreeLibrary(lib)
+#else
+	dlclose(lib);
+#endif
 }
 
 Module* DLLManager::CallInit()
 {
+	const uint32_t* abi = GetSymbol<const uint32_t>(MODULE_STR_ABI);
+	if (!abi)
+	{
+		err.assign(libname + " is not a module (no ABI symbol)");
+		return NULL;
+	}
+	else if (*abi != MODULE_ABI)
+	{
+		const char* version = GetVersion();
+		err.assign(InspIRCd::Format("%s was built against %s which is too %s to use with %s",
+			libname.c_str(), version ? version : "an unknown version",
+			*abi < MODULE_ABI ? "old" : "new", INSPIRCD_VERSION));
+		return NULL;
+	}
+
 	union
 	{
 		void* vptr;
 		Module* (*fptr)();
 	};
 
-	vptr = GetSymbol(MODULE_INIT_STR);
+	vptr = GetSymbol(MODULE_STR_INIT);
 	if (!vptr)
+	{
+		err.assign(libname + " is not a module (no init symbol)");
 		return NULL;
+	}
 
 	return (*fptr)();
 }
 
-void* DLLManager::GetSymbol(const char* name)
+void* DLLManager::GetSymbol(const char* name) const
 {
-	return h ? dlsym(h, name) : NULL;
-}
+	if (!lib)
+		return NULL;
 
-std::string DLLManager::GetVersion()
-{
-	const char* srcver = static_cast<const char*>(GetSymbol("inspircd_src_version"));
-	return srcver ? srcver : "";
+#if defined _WIN32
+	return GetProcAddress(lib, name);
+#else
+	return dlsym(lib, name);
+#endif
 }
 
 void DLLManager::RetrieveLastError()
diff --git a/src/inspircd.cpp b/src/inspircd.cpp
index dea4b4575..e2d3f8dff 100644
--- a/src/inspircd.cpp
+++ b/src/inspircd.cpp
@@ -36,7 +36,6 @@
 #ifndef _WIN32
 	#include <unistd.h>
 	#include <sys/resource.h>
-	#include <dlfcn.h>
 	#include <getopt.h>
 	#include <pwd.h> // setuid
 	#include <grp.h> // setgid
diff --git a/src/logger.cpp b/src/logger.cpp
index a05edc55f..8aad5e8f1 100644
--- a/src/logger.cpp
+++ b/src/logger.cpp
@@ -56,7 +56,7 @@
  */
 
 const char LogStream::LogHeader[] =
-	"Log started for " INSPIRCD_VERSION " (" MODULE_INIT_STR ")";
+	"Log started for " INSPIRCD_VERSION;
 
 LogManager::LogManager()
 	: Logging(false)
diff --git a/src/modulemanager.cpp b/src/modulemanager.cpp
index 218b9aa5a..e5309af57 100644
--- a/src/modulemanager.cpp
+++ b/src/modulemanager.cpp
@@ -69,13 +69,13 @@ bool ModuleManager::Load(const std::string& modname, bool defer)
 			newmod->ModuleSourceFile = filename;
 			newmod->ModuleDLLManager = newhandle;
 			Modules[filename] = newmod;
-			std::string version = newhandle->GetVersion();
-			if (version.empty())
-				version.assign("unknown");
+			const char* version = newhandle->GetVersion();
+			if (!version)
+				version = "unknown";
 			if (defer)
 			{
 				ServerInstance->Logs->Log("MODULE", LOG_DEFAULT, "New module introduced: %s (Module version %s)",
-					filename.c_str(), version.c_str());
+					filename.c_str(), version);
 			}
 			else
 			{
@@ -88,7 +88,7 @@ bool ModuleManager::Load(const std::string& modname, bool defer)
 
 				Version v = newmod->GetVersion();
 				ServerInstance->Logs->Log("MODULE", LOG_DEFAULT, "New module introduced: %s (Module version %s)%s",
-					filename.c_str(), version.c_str(), (!(v.Flags & VF_VENDOR) ? " [3rd Party]" : " [Vendor]"));
+					filename.c_str(), version, (!(v.Flags & VF_VENDOR) ? " [3rd Party]" : " [Vendor]"));
 			}
 		}
 		else