diff options
Diffstat (limited to 'src/include/taler_extensions.h')
| -rw-r--r-- | src/include/taler_extensions.h | 386 |
1 files changed, 386 insertions, 0 deletions
diff --git a/src/include/taler_extensions.h b/src/include/taler_extensions.h new file mode 100644 index 000000000..1eb567f72 --- /dev/null +++ b/src/include/taler_extensions.h @@ -0,0 +1,386 @@ +/* + This file is part of TALER + Copyright (C) 2022 Taler Systems SA + + TALER 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 3, or (at your option) any later version. + + TALER 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 + TALER; see the file COPYING. If not, see <http://www.gnu.org/licenses/> + */ +/** + * @file include/taler_extensions.h + * @brief Interface for extensions + * @author Özgür Kesim + */ +#ifndef TALER_EXTENSIONS_H +#define TALER_EXTENSIONS_H + +#include <gnunet/gnunet_util_lib.h> +#include "taler_util.h" +#include "taler_json_lib.h" +#include "taler_mhd_lib.h" +#include "taler_extensions_policy.h" + + +#define TALER_EXTENSION_SECTION_PREFIX "exchange-extension-" + +enum TALER_Extension_Type +{ + TALER_Extension_PolicyNull = 0, + + TALER_Extension_AgeRestriction = 1, + TALER_Extension_PolicyMerchantRefund = 2, + TALER_Extension_PolicyBrandtVickeryAuction = 3, + TALER_Extension_PolicyEscrowedPayment = 4, + + TALER_Extension_MaxPredefined = 5 // Must be last of the predefined +}; + + +/* Forward declarations */ +enum TALER_PolicyFulfillmentState; +struct TALER_PolicyFulfillmentOutcome; + +/* + * @brief Represents the implementation of an extension. + * + * An "Extension" is an optional feature for the Exchange. + * There are only two types of extensions: + * + * a) Age restriction: This is a special feature that directly interacts with + * denominations and coins, but is not define policies during deposits, see b). + * The implementation of this extension doesn't have to implement any of the + * http- or depost-handlers in the struct. + * + * b) Policies for deposits: These are extensions that define policies (such + * as refund, escrow or auctions) for deposit requests. These extensions have + * to implement at least the deposit- and post-http-handler in the struct to be + * functional. + * + * In addition to the handlers defined in this struct, an extension must also + * be a plugin in the GNUNET_Plugin sense. That is, it must implement the + * functions + * 1: (void *ext)libtaler_extension_<name>_init(void *cfg) + * and + * 2: (void *)libtaler_extension_<name>_done(void *) + * + * In 1:, the input will be the GNUNET_CONFIGURATION_Handle to the TALER + * configuration and the output must be the struct TALER_Extension * on + * success, NULL otherwise. + * + * In 2:, no arguments are passed and NULL is expected to be returned. + */ +struct TALER_Extension +{ + /** + * Type of the extension. Only one extension of a type can be loaded + * at any time. + */ + enum TALER_Extension_Type type; + + /** + * The name of the extension, must be unique among all loaded extensions. It + * is used in URLs for /extension/$NAME as well. + */ + char *name; + + /** + * Criticality of the extension. It has the same semantics as "critical" has + * for extensions in X.509: + * - if "true", the client must "understand" the extension before proceeding, + * - if "false", clients can safely skip extensions they do not understand. + * (see https://datatracker.ietf.org/doc/html/rfc5280#section-4.2) + */ + bool critical; + + /** + * Version of the extension must be provided in Taler's protocol version ranges notation, see + * https://docs.taler.net/core/api-common.html#protocol-version-ranges + */ + char *version; + + /** + * If the extension is marked as enabled, it will be listed in the + * "extensions" field in the "/keys" response. + */ + bool enabled; + + /** + * Opaque (public) configuration object, set by the extension. + */ + void *config; + + + /** + * @brief Handler to to disable the extension. + * + * @param ext The current extension object + */ + void (*disable)(struct TALER_Extension *ext); + + /** + * @brief Handler to read an extension-specific configuration in JSON + * encoding and enable the extension. Must be implemented by the extension. + * + * @param[in] ext The extension object. If NULL, the configuration will only be checked. + * @param[in,out] config A JSON blob + * @return GNUNET_OK if the json was a valid configuration for the extension. + */ + enum GNUNET_GenericReturnValue (*load_config)( + const json_t *config, + struct TALER_Extension *ext); + + /** + * @brief Handler to return the manifest of the extension in JSON encoding. + * + * See + * https://docs.taler.net/design-documents/006-extensions.html#tsref-type-Extension + * for the definition. + * + * @param ext The extension object + * @return The JSON encoding of the extension, if enabled, NULL otherwise. + */ + json_t *(*manifest)( + const struct TALER_Extension *ext); + + /* ========================= + * Policy related handlers + * ========================= + */ + + /** + * @brief Handler to check an incoming policy and create a + * TALER_PolicyDetails. Can be NULL; + * + * When a deposit request refers to this extension in its policy + * (see https://docs.taler.net/core/api-exchange.html#deposit), this handler + * will be called before the deposit transaction. + * + * @param[in] currency Currency used in the exchange + * @param[in] policy_json Details about the policy, provided by the client + * during a deposit request. + * @param[out] details On success, will contain the details to the policy, + * evaluated by the corresponding policy handler. + * @param[out] error_hint On error, will contain a hint + * @return GNUNET_OK if the data was accepted by the extension. + */ + enum GNUNET_GenericReturnValue (*create_policy_details)( + const char *currency, + const json_t *policy_json, + struct TALER_PolicyDetails *details, + const char **error_hint); + + /** + * @brief Handler for POST-requests to the /extensions/$name endpoint. Can be NULL. + * + * @param[in] root The JSON body from the request + * @param[in] args Additional query parameters of the request. + * @param[in,out] details List of policy details related to the incoming fulfillment proof + * @param[in] details_len Size of the list @e details + * @param[out] output JSON output to return to the client + * @return GNUNET_OK on success. + */ + enum GNUNET_GenericReturnValue (*policy_post_handler)( + const json_t *root, + const char *const args[], + struct TALER_PolicyDetails *details, + size_t details_len, + json_t **output); + + /** + * @brief Handler for GET-requests to the /extensions/$name endpoint. Can be NULL. + * + * @param connection The current connection + * @param root The JSON body from the request + * @param args Additional query parameters of the request. + * @return MDH result + */ + MHD_RESULT (*policy_get_handler)( + struct MHD_Connection *connection, + const char *const args[]); +}; + + +/* + * @brief simply linked list of extensions + */ + +struct TALER_Extensions +{ + struct TALER_Extensions *next; + const struct TALER_Extension *extension; +}; + +/** + * Generic functions for extensions + */ + +/** + * @brief Loads the extensions as shared libraries, as specified in the given + * TALER configuration. + * + * @param cfg Handle to the TALER configuration + * @return #GNUNET_OK on success, #GNUNET_SYSERR if unknown extensions were found + * or any particular configuration couldn't be parsed. + */ +enum GNUNET_GenericReturnValue +TALER_extensions_init ( + const struct GNUNET_CONFIGURATION_Handle *cfg); + +/* + * @brief Parses a given JSON object as an extension manifest. + * + * @param[in] obj JSON object to parse as an extension manifest + * @param{out] critical will be set to 1 if the extension is critical according to obj + * @param[out] version will be set to the version of the extension according to obj + * @param[out] config will be set to the configuration of the extension according to obj + * @return OK on success, Error otherwise + */ +enum GNUNET_GenericReturnValue +TALER_extensions_parse_manifest ( + json_t *obj, + int *critical, + const char **version, + json_t **config); + +/* + * @brief Loads extensions according to the manifests. + * + * The JSON object must be of type ExtensionsManifestsResponse as described + * in https://docs.taler.net/design-documents/006-extensions.html#exchange + * + * @param cfg JSON object containing the manifests for all extensions + * @return #GNUNET_OK on success, #GNUNET_SYSERR if unknown extensions were + * found or any particular configuration couldn't be parsed. + */ +enum GNUNET_GenericReturnValue +TALER_extensions_load_manifests ( + const json_t *manifests); + +/* + * @brief Returns the head of the linked list of extensions. + */ +const struct TALER_Extensions * +TALER_extensions_get_head (void); + +/** + * @brief Finds and returns a supported extension by a given type. + * + * @param type of the extension to lookup + * @return extension found, or NULL (should not happen!) + */ +const struct TALER_Extension * +TALER_extensions_get_by_type ( + enum TALER_Extension_Type type); + + +/** + * @brief Finds and returns a supported extension by a given name. + * + * @param name name of the extension to lookup + * @return the extension, if found, NULL otherwise + */ +const struct TALER_Extension * +TALER_extensions_get_by_name ( + const char *name); + +/** + * @brief Check if a given type of an extension is enabled + * + * @param type type of to check + * @return true enabled, false if not enabled, will assert if type is not found. + */ +bool +TALER_extensions_is_enabled_type ( + enum TALER_Extension_Type type); + +/** + * @brief Check if an extension is enabled + * + * @param extension The extension handler. + * @return true enabled, false if not enabled, will assert if type is not found. + */ +bool +TALER_extensions_is_enabled ( + const struct TALER_Extension *extension); + +/* + * Verify the signature of a given JSON object for extensions with the master + * key of the exchange. + * + * The JSON object must be of type ExtensionsManifestsResponse as described in + * https://docs.taler.net/design-documents/006-extensions.html#exchange + * + * @param extensions JSON object with the extension configuration + * @param extensions_sig signature of the hash of the JSON object + * @param master_pub public key to verify the signature + * @return GNUNET_OK on success, GNUNET_SYSERR when hashing of the JSON fails + * and GNUNET_NO if the signature couldn't be verified. + */ +enum GNUNET_GenericReturnValue +TALER_extensions_verify_manifests_signature ( + const json_t *manifests, + struct TALER_MasterSignatureP *extensions_sig, + struct TALER_MasterPublicKeyP *master_pub); + + +/* + * TALER Age Restriction Extension + * + * This extension is special insofar as it directly interacts with coins and + * denominations. + * + * At the same time, it doesn't implement and http- or deposit-handlers. + */ + +#define TALER_EXTENSION_SECTION_AGE_RESTRICTION (TALER_EXTENSION_SECTION_PREFIX \ + "age_restriction") + +/** + * The default age mask represents the age groups + * 0-7, 8-9, 10-11, 12-13, 14-15, 16-17, 18-20, 21-... + */ +#define TALER_EXTENSION_AGE_RESTRICTION_DEFAULT_AGE_GROUPS "8:10:12:14:16:18:21" + + +/* + * @brief Configuration for Age Restriction + */ +struct TALER_AgeRestrictionConfig +{ + struct TALER_AgeMask mask; + uint8_t num_groups; +}; + + +/** + * @brief Retrieve the age restriction configuration + * + * @return age restriction configuration if present, otherwise NULL. + */ +const struct TALER_AgeRestrictionConfig * +TALER_extensions_get_age_restriction_config (void); + +/** + * @brief Check if age restriction is enabled + * + * @return true, if age restriction is loaded, configured and enabled; otherwise false. + */ +bool +TALER_extensions_is_age_restriction_enabled (void); + +/** + * @brief Return the age mask for age restriction + * + * @return configured age mask, if age restriction is loaded, configured and enabled; otherwise zero mask. + */ +struct TALER_AgeMask +TALER_extensions_get_age_restriction_mask (void); + +#endif |