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diff --git a/docs/afb-binding-references.md b/docs/afb-binding-references.md new file mode 100644 index 00000000..7d6cdd1d --- /dev/null +++ b/docs/afb-binding-references.md @@ -0,0 +1,672 @@ +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 authorisation */ + uint32_t session; /* authorisation 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 reexecuted 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 initialisation. + +```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. 'iserror' a boolean status being true (not null) 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 iserror, 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 1 in case of success or 0 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 recommanded 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 asynchrnous 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'. + * 'iserror' is a boolean that indicates if the reply is 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 iserror, 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 an error answer and returns 1 when no error was detected. + * 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. + +Some definitions can be used to + + |