Binding Reference ================= Structure for declaring binding ------------------------------- ### struct afb_binding_v2 The main structure, of type **afb_binding_v2**, for describing the binding must be exported under the name **afbBindingV2**. This structure is defined as below. ```C /* * Description of the bindings of type version 2 */ struct afb_binding_v2 { const char *api; /* api name for the binding */ const char *specification; /* textual openAPIv3 specification of the binding */ const struct afb_verb_v2 *verbs; /* array of descriptions of verbs terminated by a NULL name */ int (*preinit)(); /* callback at load of the binding */ int (*init)(); /* callback for starting the service */ void (*onevent)(const char *event, struct json_object *object); /* callback for handling events */ unsigned noconcurrency: 1; /* avoids concurrent requests to verbs */ }; ``` ### struct afb_verb_v2 Each verb is described with a structure of type **afb_verb_v2** defined below: ```C /* * Description of one verb of the API provided by the binding * This enumeration is valid for bindings of type version 2 */ struct afb_verb_v2 { const char *verb; /* name of the verb */ void (*callback)(struct afb_req req); /* callback function implementing the verb */ const struct afb_auth *auth; /* required authorization */ uint32_t session; /* authorization and session requirements of the verb */ }; ``` The session flags is an or of the constant defined below: - AFB_SESSION_NONE : no flag, synonym to 0 - AFB_SESSION_LOA_0 : Requires the LOA to be 0 or more, synonym to 0 or AFB_SESSION_NONE - AFB_SESSION_LOA_1 : Requires the LOA to be 1 or more - AFB_SESSION_LOA_2 : Requires the LOA to be 2 or more - AFB_SESSION_LOA_3 : Requires the LOA to be 3 or more - AFB_SESSION_CHECK : Requires the token to be set and valid - AFB_SESSION_REFRESH : Implies a token refresh - AFB_SESSION_CLOSE : Implies cloing the session The LOA is set binding by binding using the function **afb_req_session_set_LOA**. ### struct afb_auth and enum afb_auth_type The structure **afb_auth** is used within verb description to set security requirements. The interpretation of the structure depends on the value of the field **type**. ```C struct afb_auth { const enum afb_auth_type type; union { const char *text; const unsigned loa; const struct afb_auth *first; }; const struct afb_auth *next; }; ``` The possible values for **type** is defined here: ```C /* * Enum for Session/Token/Assurance middleware. */ enum afb_auth_type { afb_auth_No = 0, /** never authorized, no data */ afb_auth_Token, /** authorized if token valid, no data */ afb_auth_LOA, /** authorized if LOA greater than data 'loa' */ afb_auth_Permission, /** authorized if permission 'text' is granted */ afb_auth_Or, /** authorized if 'first' or 'next' is authorized */ afb_auth_And, /** authorized if 'first' and 'next' are authorized */ afb_auth_Not, /** authorized if 'first' is not authorized */ afb_auth_Yes /** always authorized, no data */ }; ``` Example: ```C static const struct afb_auth _afb_auths_v2_monitor[] = { { .type = afb_auth_Permission, .text = "urn:AGL:permission:monitor:public:set" }, { .type = afb_auth_Permission, .text = "urn:AGL:permission:monitor:public:get" }, { .type = afb_auth_Or, .first = &_afb_auths_v2_monitor[1], .next = &_afb_auths_v2_monitor[0] } }; ``` Functions of class afb_daemon... ------------------------- The 3 following functions are linked to libsystemd. They allow use of **sd_event** features and access to **sd_bus** features. ```C /* * Retrieves the common systemd's event loop of AFB */ struct sd_event *afb_daemon_get_event_loop(); /* * Retrieves the common systemd's user/session d-bus of AFB */ struct sd_bus *afb_daemon_get_user_bus(); /* * Retrieves the common systemd's system d-bus of AFB */ struct sd_bus *afb_daemon_get_system_bus(); ``` The 2 following functions are linked to event management. Broadcasting an event send it to any possible listener. ```C /* * Broadcasts widely the event of 'name' with the data 'object'. * 'object' can be NULL. * * For convenience, the function calls 'json_object_put' for 'object'. * Thus, in the case where 'object' should remain available after * the function returns, the function 'json_object_get' shall be used. * * Returns the count of clients that received the event. */ int afb_daemon_broadcast_event(const char *name, struct json_object *object); /* * Creates an event of 'name' and returns it. * * See afb_event_is_valid to check if there is an error. */ struct afb_event afb_daemon_make_event(const char *name); ``` The following function is used by logging macros and should normally not be used. Instead, you should use the macros **AFB\_ERROR**, **AFB\_WARNING**, **AFB\_NOTICE**, **AFB\_INFO**, **AFB\_DEBUG** ```C /* * Send a message described by 'fmt' and following parameters * to the journal for the verbosity 'level'. * * 'file', 'line' and 'func' are indicators of position of the code in source files * (see macros __FILE__, __LINE__ and __func__). * * 'level' is defined by syslog standard: * EMERGENCY 0 System is unusable * ALERT 1 Action must be taken immediately * CRITICAL 2 Critical conditions * ERROR 3 Error conditions * WARNING 4 Warning conditions * NOTICE 5 Normal but significant condition * INFO 6 Informational * DEBUG 7 Debug-level messages */ void afb_daemon_verbose(int level, const char *file, int line, const char * func, const char *fmt, ...); ``` The 2 following functions MUST be used to access data of the bindings. ```C /* * Get the root directory file descriptor. This file descriptor can * be used with functions 'openat', 'fstatat', ... */ int afb_daemon_rootdir_get_fd(); /* * Opens 'filename' within the root directory with 'flags' (see function openat) * using the 'locale' definition (example: "jp,en-US") that can be NULL. * Returns the file descriptor or -1 in case of error. */ int afb_daemon_rootdir_open_locale(const char *filename, int flags, const char *locale); ``` The following function is used to queue jobs. ```C /* * Queue the job defined by 'callback' and 'argument' for being executed asynchronously * in this thread (later) or in an other thread. * If 'group' is not NUL, the jobs queued with a same value (as the pointer value 'group') * are executed in sequence in the order of there submission. * If 'timeout' is not 0, it represent the maximum execution time for the job in seconds. * At first, the job is called with 0 as signum and the given argument. * The job is executed with the monitoring of its time and some signals like SIGSEGV and * SIGFPE. When a such signal is catched, the job is terminated and re-executed but with * signum being the signal number (SIGALRM when timeout expired). * * Returns 0 in case of success or -1 in case of error. */ int afb_daemon_queue_job(void (*callback)(int signum, void *arg), void *argument, void *group, int timeout) ``` The following function must be used when a binding depends on other bindings at its initialization. ```C /* * Tells that it requires the API of "name" to exist * and if 'initialized' is not null to be initialized. * Returns 0 in case of success or -1 in case of error. */ int afb_daemon_require_api(const char *name, int initialized) ``` Functions of class afb_service... ------------------------- The following functions allow services to call verbs of other bindings for themselves. ```C /** * Calls the 'verb' of the 'api' with the arguments 'args' and 'verb' in the name of the binding. * The result of the call is delivered to the 'callback' function with the 'callback_closure'. * * For convenience, the function calls 'json_object_put' for 'args'. * Thus, in the case where 'args' should remain available after * the function returns, the function 'json_object_get' shall be used. * * The 'callback' receives 3 arguments: * 1. 'closure' the user defined closure pointer 'callback_closure', * 2. 'status' a status being 0 on success or negative when an error occured, * 2. 'result' the resulting data as a JSON object. * * @param api The api name of the method to call * @param verb The verb name of the method to call * @param args The arguments to pass to the method * @param callback The to call on completion * @param callback_closure The closure to pass to the callback * * @see also 'afb_req_subcall' */ void afb_service_call( const char *api, const char *verb, struct json_object *args, void (*callback)(void*closure, int status, struct json_object *result), void *callback_closure); /** * Calls the 'verb' of the 'api' with the arguments 'args' and 'verb' in the name of the binding. * 'result' will receive the response. * * For convenience, the function calls 'json_object_put' for 'args'. * Thus, in the case where 'args' should remain available after * the function returns, the function 'json_object_get' shall be used. * * @param api The api name of the method to call * @param verb The verb name of the method to call * @param args The arguments to pass to the method * @param result Where to store the result - should call json_object_put on it - * * @returns 0 in case of success or a negative value in case of error. * * @see also 'afb_req_subcall' */ int afb_service_call_sync( const char *api, const char *verb, struct json_object *args, struct json_object **result); ``` Functions of class afb_event... ------------------------- This function checks whether the event is valid. It must be used when creating events. ```C /* * Checks wether the 'event' is valid or not. * * Returns 0 if not valid or 1 if valid. */ int afb_event_is_valid(struct afb_event event); ``` The two following functions are used to broadcast or push event with its data. ```C /* * Broadcasts widely the 'event' with the data 'object'. * 'object' can be NULL. * * For convenience, the function calls 'json_object_put' for 'object'. * Thus, in the case where 'object' should remain available after * the function returns, the function 'json_object_get' shall be used. * * Returns the count of clients that received the event. */ int afb_event_broadcast(struct afb_event event, struct json_object *object); /* * Pushes the 'event' with the data 'object' to its observers. * 'object' can be NULL. * * For convenience, the function calls 'json_object_put' for 'object'. * Thus, in the case where 'object' should remain available after * the function returns, the function 'json_object_get' shall be used. * * Returns the count of clients that received the event. */ int afb_event_push(struct afb_event event, struct json_object *object); ``` The following function destiys the event. ```C /* * Drops the data associated to the 'event' * After calling this function, the event * MUST NOT BE USED ANYMORE. */ void afb_event_drop(struct afb_event event); ``` This function allows to retrieve the exact name of the event. ```C /* * Gets the name associated to the 'event'. */ const char *afb_event_name(struct afb_event event); ``` Functions of class afb_req... ------------------------- This function checks the validity of the **req**. ```C /* * Checks wether the request 'req' is valid or not. * * Returns 0 if not valid or 1 if valid. */ int afb_req_is_valid(struct afb_req req); ``` The following functions retrieves parameters of the request. ```C /* * Gets from the request 'req' the argument of 'name'. * Returns a PLAIN structure of type 'struct afb_arg'. * When the argument of 'name' is not found, all fields of result are set to NULL. * When the argument of 'name' is found, the fields are filled, * in particular, the field 'result.name' is set to 'name'. * * There is a special name value: the empty string. * The argument of name "" is defined only if the request was made using * an HTTP POST of Content-Type "application/json". In that case, the * argument of name "" receives the value of the body of the HTTP request. */ struct afb_arg afb_req_get(struct afb_req req, const char *name); /* * Gets from the request 'req' the string value of the argument of 'name'. * Returns NULL if when there is no argument of 'name'. * Returns the value of the argument of 'name' otherwise. * * Shortcut for: afb_req_get(req, name).value */ const char *afb_req_value(struct afb_req req, const char *name); /* * Gets from the request 'req' the path for file attached to the argument of 'name'. * Returns NULL if when there is no argument of 'name' or when there is no file. * Returns the path of the argument of 'name' otherwise. * * Shortcut for: afb_req_get(req, name).path */ const char *afb_req_path(struct afb_req req, const char *name); /* * Gets from the request 'req' the json object hashing the arguments. * The returned object must not be released using 'json_object_put'. */ struct json_object *afb_req_json(struct afb_req req); ``` The following functions emit the reply to the request. ```C /* * Sends a reply of kind success to the request 'req'. * The status of the reply is automatically set to "success". * Its send the object 'obj' (can be NULL) with an * informationnal comment 'info (can also be NULL). * * For convenience, the function calls 'json_object_put' for 'obj'. * Thus, in the case where 'obj' should remain available after * the function returns, the function 'json_object_get' shall be used. */ void afb_req_success(struct afb_req req, struct json_object *obj, const char *info); /* * Same as 'afb_req_success' but the 'info' is a formatting * string followed by arguments. * * For convenience, the function calls 'json_object_put' for 'obj'. * Thus, in the case where 'obj' should remain available after * the function returns, the function 'json_object_get' shall be used. */ void afb_req_success_f(struct afb_req req, struct json_object *obj, const char *info, ...); /* * Same as 'afb_req_success_f' but the arguments to the format 'info' * are given as a variable argument list instance. * * For convenience, the function calls 'json_object_put' for 'obj'. * Thus, in the case where 'obj' should remain available after * the function returns, the function 'json_object_get' shall be used. */ void afb_req_success_v(struct afb_req req, struct json_object *obj, const char *info, va_list args); /* * Sends a reply of kind failure to the request 'req'. * The status of the reply is set to 'status' and an * informationnal comment 'info' (can also be NULL) can be added. * * Note that calling afb_req_fail("success", info) is equivalent * to call afb_req_success(NULL, info). Thus even if possible it * is strongly recommended to NEVER use "success" for status. */ void afb_req_fail(struct afb_req req, const char *status, const char *info); /* * Same as 'afb_req_fail' but the 'info' is a formatting * string followed by arguments. */ void afb_req_fail_f(struct afb_req req, const char *status, const char *info, ...); /* * Same as 'afb_req_fail_f' but the arguments to the format 'info' * are given as a variable argument list instance. */ void afb_req_fail_v(struct afb_req req, const char *status, const char *info, va_list args); ``` The following functions handle the session data. ```C /* * Gets the pointer stored by the binding for the session of 'req'. * When the binding has not yet recorded a pointer, NULL is returned. */ void *afb_req_context_get(struct afb_req req); /* * Stores for the binding the pointer 'context' to the session of 'req'. * The function 'free_context' will be called when the session is closed * or if binding stores an other pointer. */ void afb_req_context_set(struct afb_req req, void *context, void (*free_context)(void*)); /* * Gets the pointer stored by the binding for the session of 'req'. * If the stored pointer is NULL, indicating that no pointer was * already stored, afb_req_context creates a new context by calling * the function 'create_context' and stores it with the freeing function * 'free_context'. */ void *afb_req_context(struct afb_req req, void *(*create_context)(), void (*free_context)(void*)); /* * Frees the pointer stored by the binding for the session of 'req' * and sets it to NULL. * * Shortcut for: afb_req_context_set(req, NULL, NULL) */ void afb_req_context_clear(struct afb_req req); /* * Closes the session associated with 'req' * and delete all associated contexts. */ void afb_req_session_close(struct afb_req req); /* * Sets the level of assurance of the session of 'req' * to 'level'. The effect of this function is subject of * security policies. * Returns 1 on success or 0 if failed. */ int afb_req_session_set_LOA(struct afb_req req, unsigned level); ``` The 4 following functions must be used for asynchronous handling requests. ```C /* * Adds one to the count of references of 'req'. * This function MUST be called by asynchronous implementations * of verbs if no reply was sent before returning. */ void afb_req_addref(struct afb_req req); /* * Substracts one to the count of references of 'req'. * This function MUST be called by asynchronous implementations * of verbs after sending the asynchronous reply. */ void afb_req_unref(struct afb_req req); /* * Stores 'req' on heap for asynchronous use. * Returns a handler to the stored 'req' or NULL on memory depletion. * The count of reference to 'req' is incremented on success * (see afb_req_addref). */ struct afb_stored_req *afb_req_store(struct afb_req req); /* * Retrieves the afb_req stored at 'sreq'. * Returns the stored request. * The count of reference is UNCHANGED, thus, the * function 'afb_req_unref' should be called on the result * after that the asynchronous reply if sent. */ struct afb_req afb_req_unstore(struct afb_stored_req *sreq); ``` The two following functions are used to associate client with events (subscription). ```C /* * Establishes for the client link identified by 'req' a subscription * to the 'event'. * Returns 0 in case of successful subscription or -1 in case of error. */ int afb_req_subscribe(struct afb_req req, struct afb_event event); /* * Revokes the subscription established to the 'event' for the client * link identified by 'req'. * Returns 0 in case of successful subscription or -1 in case of error. */ int afb_req_unsubscribe(struct afb_req req, struct afb_event event); ``` The following functions must be used to make request in the name of the client (with its permissions). ```C /* * Makes a call to the method of name 'api' / 'verb' with the object 'args'. * This call is made in the context of the request 'req'. * On completion, the function 'callback' is invoked with the * 'closure' given at call and two other parameters: 'iserror' and 'result'. * 'status' is 0 on success or negative when on an error reply. * 'result' is the json object of the reply, you must not call json_object_put * on the result. * * For convenience, the function calls 'json_object_put' for 'args'. * Thus, in the case where 'args' should remain available after * the function returns, the function 'json_object_get' shall be used. */ void afb_req_subcall( struct afb_req req, const char *api, const char *verb, struct json_object *args, void (*callback)(void *closure, int status, struct json_object *result), void *closure); /* * Makes a call to the method of name 'api' / 'verb' with the object 'args'. * This call is made in the context of the request 'req'. * This call is synchronous, it waits untill completion of the request. * It returns 0 on success or a negative value on error answer. * The object pointed by 'result' is filled and must be released by the caller * after its use by calling 'json_object_put'. * * For convenience, the function calls 'json_object_put' for 'args'. * Thus, in the case where 'args' should remain available after * the function returns, the function 'json_object_get' shall be used. */ int afb_req_subcall_sync( struct afb_req req, const char *api, const char *verb, struct json_object *args, struct json_object **result); ``` The following function is used by logging macros and should normally not be used. Instead, you should use the macros **AFB_REQ_ERROR**, **AFB_REQ_WARNING**, **AFB_REQ_NOTICE**, **AFB_REQ_INFO**, **AFB_REQ_DEBUG** ```C /* * Send associated to 'req' a message described by 'fmt' and following parameters * to the journal for the verbosity 'level'. * * 'file', 'line' and 'func' are indicators of position of the code in source files * (see macros __FILE__, __LINE__ and __func__). * * 'level' is defined by syslog standard: * EMERGENCY 0 System is unusable * ALERT 1 Action must be taken immediately * CRITICAL 2 Critical conditions * ERROR 3 Error conditions * WARNING 4 Warning conditions * NOTICE 5 Normal but significant condition * INFO 6 Informational * DEBUG 7 Debug-level messages */ void afb_req_verbose(struct afb_req req, int level, const char *file, int line, const char * func, const char *fmt, ...); ``` Logging macros -------------- The following macros must be used for logging: ```C AFB_ERROR(fmt,...) AFB_WARNING(fmt,...) AFB_NOTICE(fmt,...) AFB_INFO(fmt,...) AFB_DEBUG(fmt,...) ``` The following macros can be used for logging in the context of a request **req** of type **afb_req**: ```C AFB_REQ_ERROR(req,fmt,...) AFB_REQ_WARNING(req,fmt,...) AFB_REQ_NOTICE(req,fmt,...) AFB_REQ_INFO(req,fmt,...) AFB_REQ_DEBUG(req,fmt,...) ``` By default, the logging macros add file, line and function indication.