1 files changed, 111 insertions, 0 deletions
diff --git a/lib/module.h b/lib/module.h
new file mode 100644
index 0000000..295c1f9
--- /dev/null
+++ b/lib/module.h
@@ -0,0 +1,111 @@
+/*  Copyright (C) 2015-2017 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+
+    This program 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, either version 3 of the License, or
+    (at your option) any later version.
+
+    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 <https://www.gnu.org/licenses/>.
+ */
+
+/** @file
+ * Module API definition and functions for (un)loading modules.
+ */
+
+#pragma once
+
+#include "lib/defines.h"
+#include "lib/utils.h"
+#include "lib/layer.h"
+
+struct kr_module;
+struct kr_prop;
+
+
+/**
+ * Export module API version (place this at the end of your module).
+ *
+ * @param module module name (f.e. hints)
+ */
+#define KR_MODULE_EXPORT(module) \
+    KR_EXPORT uint32_t module ## _api() { return KR_MODULE_API; }
+#define KR_MODULE_API ((uint32_t) 0x20180401)
+
+typedef uint32_t (module_api_cb)(void);
+
+
+/**
+ * Module representation.
+ *
+ * The five symbols (init, ...) may be defined by the module as name_init(), etc;
+ * all are optional and missing symbols are represented as NULLs;
+ */
+struct kr_module {
+	char *name;
+
+	/** Constructor.  Called after loading the module.  @return error code. */
+	int (*init)(struct kr_module *self);
+	/** Destructor.  Called before unloading the module.  @return error code. */
+	int (*deinit)(struct kr_module *self);
+	/** Configure with encoded JSON (NULL if missing).  @return error code. */
+	int (*config)(struct kr_module *self, const char *input);
+	/** Get a pointer to packet processing API specs.  See docs on that type. */
+	const kr_layer_api_t * (*layer)(struct kr_module *self);
+	/** Get a pointer to list of properties, terminated by { NULL, NULL, NULL }. */
+	const struct kr_prop * (*props)(void);
+
+	void *lib;      /**< Shared library handle or RTLD_DEFAULT */
+	void *data;     /**< Custom data context. */
+};
+
+/**
+ * Module property callback.  Input and output is passed via a JSON encoded in a string.
+ *
+ * @param env pointer to the lua engine, i.e. struct engine *env (TODO: explicit type)
+ * @param input parameter (NULL if missing/nil on lua level)
+ * @return a free-form JSON output (malloc-ated)
+ * @note see l_trampoline() implementation for details about the input/output conversion.
+ */
+typedef char *(kr_prop_cb)(void *env, struct kr_module *self, const char *input);
+
+/**
+ * Module property (named callable).
+ */
+struct kr_prop {
+	kr_prop_cb *cb;
+	const char *name;
+	const char *info;
+};
+
+
+/**
+ * Load a C module instance into memory.
+ *
+ * @param module module structure
+ * @param name module name
+ * @param path module search path
+ * @return 0 or an error
+ */
+KR_EXPORT
+int kr_module_load(struct kr_module *module, const char *name, const char *path);
+
+/**
+ * Unload module instance.
+ *
+ * @param module module structure
+ */
+KR_EXPORT
+void kr_module_unload(struct kr_module *module);
+
+/**
+ * Get embedded module prototype by name (or NULL).
+ */
+KR_EXPORT
+const struct kr_module * kr_module_embedded(const char *name);
+