112 lines
3.1 KiB
C
112 lines
3.1 KiB
C
/* Copyright (C) CZ.NIC, z.s.p.o. <knot-resolver@labs.nic.cz>
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* SPDX-License-Identifier: GPL-3.0-or-later
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*/
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/** @file
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* Module API definition and functions for (un)loading modules.
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*/
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#pragma once
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#include "lib/defines.h"
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#include "lib/utils.h"
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#include "lib/layer.h"
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struct kr_module;
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struct kr_prop;
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/**
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* Export module API version (place this at the end of your module).
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*
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* @param module module name (e.g. policy)
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*/
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#define KR_MODULE_EXPORT(module) \
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KR_EXPORT uint32_t module ## _api(void) { return KR_MODULE_API; }
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#define KR_MODULE_API ((uint32_t) 0x20210125)
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typedef uint32_t (module_api_cb)(void);
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/**
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* Module representation.
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*
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* The five symbols (init, ...) may be defined by the module as name_init(), etc;
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* all are optional and missing symbols are represented as NULLs;
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*/
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struct kr_module {
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char *name;
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/** Constructor. Called after loading the module. @return error code.
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* Lua modules: not populated, called via lua directly. */
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int (*init)(struct kr_module *self);
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/** Destructor. Called before unloading the module. @return error code. */
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int (*deinit)(struct kr_module *self);
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/** Configure with encoded JSON (NULL if missing). @return error code.
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* Lua modules: not used and not useful from C.
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* When called from lua, input is JSON, like for kr_prop_cb. */
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int (*config)(struct kr_module *self, const char *input);
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/** Packet processing API specs. May be NULL. See docs on that type.
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* Owned by the module code. */
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const kr_layer_api_t *layer;
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/** List of properties. May be NULL. Terminated by { NULL, NULL, NULL }.
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* Lua modules: not used and not useful. */
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const struct kr_prop *props;
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/** dlopen() handle; RTLD_DEFAULT for embedded modules; NULL for lua modules. */
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void *lib;
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void *data; /**< Custom data context. */
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};
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/**
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* Module property callback. Input and output is passed via a JSON encoded in a string.
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*
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* @param env pointer to the lua engine, i.e. struct engine *env (TODO: explicit type)
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* @param input parameter (NULL if missing/nil on lua level)
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* @return a free-form JSON output (malloc-ated)
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* @note see modules_create_table_for_c() implementation for details
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* about the input/output conversion.
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*/
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typedef char *(kr_prop_cb)(void *env, struct kr_module *self, const char *input);
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/**
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* Module property (named callable).
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*/
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struct kr_prop {
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kr_prop_cb *cb;
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const char *name;
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const char *info;
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};
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/**
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* Load a C module instance into memory. And call its init().
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*
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* @param module module structure. Will be overwritten except for ->data on success.
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* @param name module name
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* @param path module search path
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* @return 0 or an error
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*/
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KR_EXPORT
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int kr_module_load(struct kr_module *module, const char *name, const char *path);
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/**
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* Unload module instance.
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*
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* @param module module structure
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* @note currently used even for lua modules
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*/
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KR_EXPORT
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void kr_module_unload(struct kr_module *module);
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typedef int (*kr_module_init_cb)(struct kr_module *);
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/**
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* Get embedded module's init function by name (or NULL).
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*/
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KR_EXPORT
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kr_module_init_cb kr_module_get_embedded(const char *name);
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