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/* Copyright (C) CZ.NIC, z.s.p.o. <knot-resolver@labs.nic.cz>
* SPDX-License-Identifier: GPL-3.0-or-later
*/
/** @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 (e.g. policy)
*/
#define KR_MODULE_EXPORT(module) \
KR_EXPORT uint32_t module ## _api() { return KR_MODULE_API; }
#define KR_MODULE_API ((uint32_t) 0x20210125)
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.
* Lua modules: not populated, called via lua directly. */
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.
* Lua modules: not used and not useful from C.
* When called from lua, input is JSON, like for kr_prop_cb. */
int (*config)(struct kr_module *self, const char *input);
/** Packet processing API specs. May be NULL. See docs on that type.
* Owned by the module code. */
const kr_layer_api_t *layer;
/** List of properties. May be NULL. Terminated by { NULL, NULL, NULL }.
* Lua modules: not used and not useful. */
const struct kr_prop *props;
/** dlopen() handle; RTLD_DEFAULT for embedded modules; NULL for lua modules. */
void *lib;
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 modules_create_table_for_c() 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. And call its init().
*
* @param module module structure. Will be overwritten except for ->data on success.
* @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
* @note currently used even for lua modules
*/
KR_EXPORT
void kr_module_unload(struct kr_module *module);
typedef int (*kr_module_init_cb)(struct kr_module *);
/**
* Get embedded module's init function by name (or NULL).
*/
KR_EXPORT
kr_module_init_cb kr_module_get_embedded(const char *name);
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