module.h

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#pragma once
/*
 *  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 2 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, write to the Free Software
 *  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
 */
 
/**
 * $Id: e734bce8ab9d0a13fd5a24165aa89fe16b450308 $
 *
 * @file lib/server/module.h
 * @brief Interface to the FreeRADIUS module system.
 *
 * @copyright 2022 Arran Cudbard-Bell <a.cudbardb@freeradius.org>
 * @copyright 2013 The FreeRADIUS server project
 */
RCSIDH(modules_h, "$Id: e734bce8ab9d0a13fd5a24165aa89fe16b450308 $")
 
#ifdef __cplusplus
extern "C" {
#endif
 
typedef struct module_s                         module_t;
typedef struct module_state_func_table_s        module_state_func_table_t;
typedef struct module_method_group_s            module_method_group_t;
typedef struct module_method_binding_s          module_method_binding_t;
typedef struct module_instance_s                module_instance_t;
typedef struct module_thread_instance_s         module_thread_instance_t;
typedef struct module_list_type_s               module_list_type_t;
typedef struct module_list_s                    module_list_t;
 
#include <freeradius-devel/server/module_ctx.h>
#include <freeradius-devel/server/rcode.h>
#include <freeradius-devel/server/request.h>
 
DIAG_OFF(attributes)
typedef enum CC_HINT(flag_enum) {
        MODULE_TYPE_THREAD_UNSAFE       = (1 << 0),     //!< Module is not threadsafe.
                                                        //!< Server will protect calls with mutex.
        MODULE_TYPE_RETRY               = (1 << 2),     //!< can handle retries
 
        MODULE_TYPE_DYNAMIC_UNSAFE      = (1 << 3)      //!< Instances of this module cannot be
                                                        ///< created at runtime.
} module_flags_t;
DIAG_ON(attributes)
 
/** Module section callback
 *
 * Is called when the module is listed in a particular section of a virtual
 * server, and the request has reached the module call.
 *
 * @param[out] p_result         Result code of the module method.
 * @param[in] mctx              Holds global instance data, thread instance
 *                              data and call specific instance data.
 * @param[in] request           to process.
 * @return the appropriate rcode.
 */
typedef unlang_action_t (*module_method_t)(rlm_rcode_t *p_result, module_ctx_t const *mctx, request_t *request);
 
/** Module instantiation callback
 *
 * Is called once per module instance. Is not called when new threads are
 * spawned. See module_thread_instantiate_t for that.
 *
 * @param[in] mctx              Holds global instance data.
 * @return
 *      - 0 on success.
 *      - -1 if instantiation failed.
 */
typedef int (*module_instantiate_t)(module_inst_ctx_t const *mctx);
 
/** Module detach callback
 *
 * Is called just before the server exits, and after re-instantiation on HUP,
 * to free the old module instance.
 *
 * Detach should close all handles associated with the module instance, and
 * free any memory allocated during instantiate.
 *
 * @param[in] inst to free.
 * @return
 *      - 0 on success.
 *      - -1 if detach failed.
 */
typedef int (*module_detach_t)(module_detach_ctx_t const *inst);
 
/** Module thread creation callback
 *
 * Called whenever a new thread is created.
 *
 * @param[in] mctx              Holds global instance data, thread instance
 *                              data, and the thread-specific event list.
 * @return
 *      - 0 on success.
 *      - -1 if instantiation failed.
 */
typedef int (*module_thread_instantiate_t)(module_thread_inst_ctx_t const *mctx);
 
/** Module thread destruction callback
 *
 * Destroy a module/thread instance.
 *
 * @param[in] mctx              Holds global instance data, thread instance
 *                              data, and the thread-specific event list.
 * @return
 *      - 0 on success.
 *      - -1 if instantiation failed.
 */
typedef int (*module_thread_detach_t)(module_thread_inst_ctx_t const *mctx);
 
#ifdef __cplusplus
}
#endif
 
#include <freeradius-devel/features.h>
#include <freeradius-devel/io/schedule.h>
 
#include <freeradius-devel/server/cf_util.h>
#include <freeradius-devel/server/dl_module.h>
#include <freeradius-devel/server/exfile.h>
#include <freeradius-devel/server/pool.h>
#include <freeradius-devel/server/request.h>
#include <freeradius-devel/server/section.h>
 
#include <freeradius-devel/unlang/action.h>
#include <freeradius-devel/unlang/call_env.h>
#include <freeradius-devel/unlang/mod_action.h>
 
#include <freeradius-devel/util/event.h>
 
#ifdef __cplusplus
extern "C" {
#endif
 
/** The maximum size of a module instance
 */
#define MODULE_INSTANCE_LEN_MAX 256
 
/** Terminate a module binding list
 */
#define MODULE_BINDING_TERMINATOR { .section = NULL }
 
/** A group of methods exported by a module or added as an overlay
 *
 * Module method groups are organised into a linked list, with each group
 * containing a list of named methods.  This allows common collections of
 * methods to be added to a module.
 *
 * One common use case is adding the `instantiate`, `exists`, and `detach`
 * methods which are added to dynamic modules, and allow dynamic module
 * instances to be created and destroyed at runtime.
 */
struct module_method_group_s {
        module_method_binding_t                 *bindings;              //!< named methods
 
        bool                                    validated;              //!< Set to true by #module_method_group_validate.
        module_method_group_t                   *next;                  //!< Next group in the list.
};
 
/** Named methods exported by a module
 *
 */
struct module_method_binding_s {
        section_name_t const                    *section;               //!< Identifier for a section.
 
        module_method_t                         method;                 //!< Module method to call
        call_env_method_t const                 *method_env;            //!< Method specific call_env.
 
        fr_dlist_head_t                         same_name1;             //!< List of bindings with the same name1.  Only initialised
                                                                        ///< for the the first name1 binding.
                                                                        ///< DO NOT INITIALISE IN THE MODULE.
        fr_dlist_t                              entry;                  //!< Linked list of bindings with the same name1.
                                                                        ///< Allows us to more quickly iterate over all
                                                                        ///< name2 entries after finding a matching name1.
                                                                        ///< This is also temporarily used to verify the ordering
                                                                        ///< of name bindings.
                                                                        ///< DO NOT INITIALISE IN THE MODULE.
};
 
/** Struct exported by a rlm_* module
 *
 * Determines the capabilities of the module, and maps internal functions
 * within the module to different sections.
 */
struct module_s {
        DL_MODULE_COMMON;                                       //!< Common fields for all loadable modules.
 
        conf_parser_t const             *config;                //!< How to convert a CONF_SECTION to a module instance.
 
        size_t                          boot_size;              //!< Size of the module's bootstrap data.
        char const                      *boot_type;             //!< talloc type to assign to bootstrap data.
 
        size_t                          inst_size;              //!< Size of the module's instance data.
        char const                      *inst_type;             //!< talloc type to assign to instance data.
 
        module_instantiate_t            bootstrap;              //!< Callback to allow the module to register any global
                                                                ///< resources like xlat functions and attributes.
                                                                ///< Instance data is read only during the bootstrap phase
                                                                ///< and MUST NOT be modified.
                                                                ///< Any attributes added during this phase that the module
                                                                ///< need to be re-resolved during the instantiation phase
                                                                ///< so that dynamic modules (which don't run bootstrap)
                                                                ///< work correctly.
                                                                ///< @note Not modifying the instance data is not just a
                                                                ///< suggestion, if you try, you'll generate a SIGBUS
                                                                ///< or SIGSEGV and it won't be obvious why.
 
        module_instantiate_t            instantiate;            //!< Callback to allow the module to register any
                                                                ///< per-instance resources like sockets and file handles.
                                                                ///< After instantiate completes the module instance data
                                                                ///< is mprotected to prevent modification.
 
        module_detach_t                 detach;                 //!< Clean up module resources from the instantiation pahses.
 
        module_detach_t                 unstrap;                //!< Clean up module resources from both the bootstrap phase.
 
        module_flags_t                  flags;                  //!< Flags that control how a module starts up and how
                                                                ///< a module is called.
 
        module_thread_instantiate_t     thread_instantiate;     //!< Callback to populate a new module thread instance data.
                                                                ///< Called once per thread.
        module_thread_detach_t          thread_detach;          //!< Callback to free thread-specific resources associated
                                                                ///!< with a module.
 
        size_t                          thread_inst_size;       //!< Size of the module's thread-specific instance data.
        char const                      *thread_inst_type;      //!< talloc type to assign to thread instance data.
};
 
/** What state the module instance is currently in
 *
 */
DIAG_OFF(attributes)
typedef enum CC_HINT(flag_enum) {
        MODULE_INSTANCE_BOOTSTRAPPED            = (1 << 1),     //!< Module instance has been bootstrapped, but not
                                                                ///< yet instantiated.
        MODULE_INSTANCE_INSTANTIATED            = (1 << 2),     //!< Module instance has been bootstrapped and
                                                                ///< instantiated.
        MODULE_INSTANCE_NO_THREAD_INSTANTIATE   = (1 << 3)      //!< Not set internally, but can be used to prevent
                                                                ///< thread instantiation for certain modules.
} module_instance_state_t;
DIAG_ON(attributes)
 
typedef struct {
        TALLOC_CTX                      *ctx;           //!< ctx data is allocated in.
        void                            *start;         //!< Start address which may be passed to mprotect.
        size_t                          len;            //!< How much data we need mprotect to protect.
} module_data_pool_t;
 
/** Module instance data
 *
 * Per-module-instance data structure to correlate the modules with the
 * instance names (may NOT be the module names!), and the per-instance
 * data structures.
 */
struct module_instance_s {
       /** @name Fields that are most frequently accessed at runtime
        *
        * Putting them first gives us the greatest chance of the pointers being prefetched.
        * @{
        */
        void                            *data;          //!< Module's instance data.  This is most
                                                        ///< frequently accessed, so comes first.
 
        void                            *boot;          //!< Data allocated during the boostrap phase
 
        module_t                        *exported;      //!< Public module structure.  Cached for convenience.
                                                        ///< This exports module methods, i.e. the functions
                                                        ///< which allow the module to perform actions.
                                                        ///< This is an identical address to module->common,
                                                        ///< but with a different type, containing additional
                                                        ///< instance callbacks to make it easier to use.
 
        pthread_mutex_t                 mutex;          //!< Used prevent multiple threads entering a thread
                                                        ///< unsafe module simultaneously.
 
        dl_module_t                     *module;        //!< Dynamic loader handle.  Contains the module's
                                                        ///< dlhandle, and the functions it exports.
                                                        ///< The dl_module is reference counted so that it
                                                        ///< can be freed automatically when the last instance
                                                        ///< is freed.  This will also (usually) unload the
                                                        ///< .so or .dylib.
        /** @} */
 
        /** @name Return code overrides
         * @{
         */
        bool                            force;          //!< Force the module to return a specific code.
                                                        //!< Usually set via an administrative interface.
 
        rlm_rcode_t                     code;           //!< Code module will return when 'force' has
                                                        //!< has been set to true.
 
        unlang_mod_actions_t            actions;        //!< default actions and retries.
        /** @} */
 
       /** @name Allow module instance data to be resolved by name or data, and to get back to the module list
        * @{
        */
        module_list_t                   *ml;            //!< Module list this instance belongs to.
        fr_rb_node_t                    name_node;      //!< Entry in the name tree.
        fr_rb_node_t                    data_node;      //!< Entry in the data tree.
        uint32_t                        number;         //!< Unique module number.  Used to assign a stable
                                                        ///< number to each module instance.
        /** @} */
 
       /** @name These structures allow mprotect to protect/unprotest bootstrap and instance data
        * @{
        */
        module_data_pool_t              inst_pool;      //!< Data to allow mprotect state toggling
                                                        ///< for instance data.
        module_data_pool_t              boot_pool;      //!< Data to allow mprotect state toggling
                                                        ///< for bootstrap data.
        /** @} */
 
       /** @name Module instance state
        * @{
        */
        module_instance_state_t         state;          //!< What's been done with this module so far.
        CONF_SECTION                    *conf;          //!< Module's instance configuration.
        /** @} */
 
       /** @name Misc fields
        * @{
        */
        char const                      *name;          //!< Instance name e.g. user_database.
 
        module_instance_t const         *parent;        //!< Parent module's instance (if any).
 
        void                            *uctx;          //!< Extra data passed to module_instance_alloc.
        /** @} */
};
 
/** Per thread per instance data
 *
 * Stores module and thread specific data.
 */
struct module_thread_instance_s {
        fr_heap_index_t                 inst_idx;       //!< Entry in the thread-specific bootstrap heap.
                                                        ///< Should be an identical value to the global
                                                        ///< instance data for the same module.
 
        void                            *data;          //!< Thread specific instance data.
 
        fr_event_list_t                 *el;            //!< Event list associated with this thread.
 
        module_instance_t               *mi;            //!< As opposed to the thread local inst.
 
        uint64_t                        total_calls;    //! total number of times we've been called
        uint64_t                        active_callers; //! number of active callers.  i.e. number of current yields
};
 
/** Callback to retrieve thread-local data for a module
 *
 * This is public for performance reasons, and should be called through
 * #module_thread.
 *
 * @param[in] mi        to add data to (use mi->ml for the module list).
 * @return
 *      - NULL if no data exists.
 *      - Pointer to the data on success.
 */
typedef module_thread_instance_t *(*module_list_thread_data_get_t)(module_instance_t const *mi);
 
/** A list of modules
 *
 * This used to be a global structure, but was move to a struct.
 *
 * Module lists allow collections of modules to be created.  The module lists themselves can be configured
 * to be thread-local or global, with optional runtime write protection.
 *
 * Thread-local module lists are used for dynamic modules, i.e. those created at runtime, where as the
 * global module lists are used for backend modules, listeners, and process state machines.
 */
struct module_list_s
{
        char const                      *name;                  //!< Friendly list identifier.
        module_instance_state_t         mask;                   //!< Prevent phases from being executed.
 
        uint32_t                        last_number;            //!< Last identifier assigned to a module instance.
        fr_rb_tree_t                    *name_tree;             //!< Modules indexed by name.
        fr_rb_tree_t                    *data_tree;             //!< Modules indexed by data.
        fr_heap_t                       *inst_heap;             //!< Heap of module instances.
 
        bool                            write_protect;          //!< If true, pages containing module boot or
                                                                ///< instance data will be write protected after
                                                                ///< bootstrapping and instantiation is complete,
                                                                ///< to prevent accidental modification.
 
        /** @name Callbacks to manage thread-specific data
         *
         * In "child" lists, which are only operating in a single thread, we don't need
         * to use true thread-local data, because the module list itself is thread-local.
         *
         * In that case these callbacks hang memory off of the list itself.
         *
         * In the main module list, which is shared between threads, these callbacks
         * do use true thread-local data, to manage the module_thread_instance_t
         * on a per thread-basis.
         *
         * @{
         */
        module_list_type_t const        *type;                  //!< Type of module list.
        module_list_thread_data_get_t   thread_data_get;        //!< Callback to get thread-specific data.
                                                                ///< Copy of type->thread_data_get.
        /** @} */
};
 
/** Map string values to module state method
 *
 */
struct module_state_func_table_s {
        char const                      *name;                  //!< String identifier for state.
        module_method_t                 func;                   //!< State function.
};
 
/** @name Callbacks for the conf_parser_t
 *
 * @{
 */
int                     module_submodule_parse(UNUSED TALLOC_CTX *ctx, void *out, void *parent,
                                               CONF_ITEM *ci, UNUSED conf_parser_t const *rule) CC_HINT(warn_unused_result);
/** @} */
 
/** @name Debugging functions
 *
 * @{
 */
void module_instance_debug(module_instance_t const *mi) CC_HINT(nonnull);
 
void module_list_debug(module_list_t const *ml) CC_HINT(nonnull);
 /** @} */
 
/** @name Toggle protection on module instance data
 *
 * This is used for module lists which implement additional instantiation phases
 * (like li->open).  It should NOT be used by modules to hack around instance
 * data being read-only after instantiation completes.
 *
 * @{
 */
int                     module_instance_data_protect(module_instance_t const *mi);
 
int                     module_instance_data_unprotect(module_instance_t const *mi);
 /** @} */
 
/** @name Module and module thread lookup
 *
 * @{
 */
fr_slen_t               module_instance_name_from_conf(char const **name, CONF_SECTION *conf);
 
int                     module_instance_conf_parse(module_instance_t *mi, CONF_SECTION *conf);
 
char const              *module_instance_root_prefix_str(module_instance_t const *mi) CC_HINT(nonnull) CC_HINT(warn_unused_result);
 
module_instance_t       *module_instance_root(module_instance_t const *child); CC_HINT(warn_unused_result)
 
module_instance_t       *module_instance_by_name(module_list_t const *ml, module_instance_t const *parent, char const *asked_name)
                        CC_HINT(nonnull(1,3)) CC_HINT(warn_unused_result);
 
module_instance_t       *module_instance_by_data(module_list_t const *ml, void const *data) CC_HINT(warn_unused_result);
 
/** Retrieve module/thread specific instance for a module
 *
 * @param[in] mi        to find thread specific data for.
 * @return
 *      - Thread specific instance data on success.
 *      - NULL if module has no thread instance data.
 */
static inline CC_HINT(warn_unused_result) CC_HINT(always_inline)
module_thread_instance_t *module_thread(module_instance_t const *mi)
{
        return mi->ml->thread_data_get(mi);
}
 
module_thread_instance_t *module_thread_by_data(module_list_t const *ml, void const *data) CC_HINT(warn_unused_result);
/** @} */
 
/** @name Module and module thread initialisation and instantiation
 *
 * @{
 */
void                    modules_thread_detach(module_list_t *ml);
 
int                     module_thread_instantiate(TALLOC_CTX *ctx, module_instance_t *mi, fr_event_list_t *el)
                        CC_HINT(nonnull) CC_HINT(warn_unused_result);
 
int                     modules_thread_instantiate(TALLOC_CTX *ctx, module_list_t const *ml, fr_event_list_t *el)
                        CC_HINT(nonnull) CC_HINT(warn_unused_result);
 
int                     module_instantiate(module_instance_t *mi) CC_HINT(nonnull) CC_HINT(warn_unused_result);
 
int                     modules_instantiate(module_list_t const *ml) CC_HINT(nonnull) CC_HINT(warn_unused_result);
 
int                     module_bootstrap(module_instance_t *mi) CC_HINT(nonnull) CC_HINT(warn_unused_result);
 
int                     modules_bootstrap(module_list_t const *ml) CC_HINT(nonnull) CC_HINT(warn_unused_result);
 
extern bool const module_instance_allowed_chars[UINT8_MAX + 1];
 
fr_slen_t               module_instance_name_valid(char const *inst_name) CC_HINT(nonnull);
 
module_instance_t       *module_instance_copy(module_list_t *dst, module_instance_t const *src, char const *inst_name)
                        CC_HINT(nonnull(1,2)) CC_HINT(warn_unused_result);
 
module_instance_t       *module_instance_alloc(module_list_t *ml,
                                               module_instance_t const *parent,
                                               dl_module_type_t type, char const *mod_name, char const *inst_name,
                                               module_instance_state_t init_state)
                                               CC_HINT(nonnull(1)) CC_HINT(warn_unused_result);
 
void                    module_instance_uctx_set(module_instance_t *mi, void *uctx);
 
/** @name Module list variants
 *
 * These are passed to the module_list_alloc function to allocate lists of different types
 *
 * Global module lists are used for backend modules, listeners, and process state machines.
 *
 * Thread-local lists are usually runtime instantiated variants of modules, or modules that represent client connections.
 *
 * One major difference (from the module's perspective) is that bootstrap is not called for thread-local modules.
 *
 * @{
 */
extern module_list_type_t const module_list_type_global;        //!< Initialise a global module, with thread-specific data.
extern module_list_type_t const module_list_type_thread_local;  //!< Initialise a thread-local module, which is only used in a single thread.
/** @} */
 
/** @name Control which phases are skipped (if any)
 * @{
 */
bool                    module_instance_skip_bootstrap(module_instance_t *mi);
 
bool                    module_instance_skip_instantiate(module_instance_t *mi);
 
bool                    module_instance_skip_thread_instantiate(module_instance_t *mi);
 
void                    module_list_mask_set(module_list_t *ml, module_instance_state_t mask);
/** @} */
 
module_list_t           *module_list_alloc(TALLOC_CTX *ctx, module_list_type_t const *type,
                                           char const *name, bool write_protect)
                                           CC_HINT(nonnull(2,3)) CC_HINT(warn_unused_result);
 
void                    modules_init(char const *lib_dir);
/** @} */
 
#ifdef __cplusplus
}
#endif