src/parser_data.h

/**
 * @file parser_data.h
 * @author Radek Krejci <rkrejci@cesnet.cz>
 * @brief Data parsers for libyang
 *
 * Copyright (c) 2015-2020 CESNET, z.s.p.o.
 *
 * This source code is licensed under BSD 3-Clause License (the "License").
 * You may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     https://opensource.org/licenses/BSD-3-Clause
 */

#ifndef LY_PARSER_DATA_H_
#define LY_PARSER_DATA_H_

#include "tree_data.h"

#ifdef __cplusplus
extern "C" {
#endif

struct ly_in;

/**
 * @page howtoDataParsers Parsing Data
 *
 * Data parser allows to read instances from a specific format. libyang supports the following data formats:
 *
 * - XML
 *
 *   Original data format used in NETCONF protocol. XML mapping is part of the YANG specification
 *   ([RFC 6020](http://tools.ietf.org/html/rfc6020)).
 *
 * - JSON
 *
 *   The alternative data format available in RESTCONF protocol. Specification of JSON encoding of data modeled by YANG
 *   can be found in [RFC 7951](http://tools.ietf.org/html/rfc7951). The specification does not cover RPCs, actions and
 *   Notifications, so the representation of these data trees is proprietary and corresponds to the representation of these
 *   trees in XML.
 *
 * While the parsers themselves process the input data only syntactically, all the parser functions actually incorporate
 * the [common validator](@ref howtoDataValidation) checking the input data semantically. Therefore, the parser functions
 * accepts two groups of options - @ref dataparseroptions and @ref datavalidationoptions.
 *
 * In contrast to the schema parser, data parser also accepts empty input data if such an empty data tree is valid
 * according to the schemas in the libyang context (i.e. there are no top level mandatory nodes).
 *
 * There are individual functions to process different types of the data instances trees:
 * - ::lyd_parse_data() is intended for standard configuration data trees. According to the given
 *   [parser options](@ref dataparseroptions), the caller can further specify which kind of data tree is expected:
 *   - *complete :running datastore*: this is the default case, possibly with the use of (some of) the
 *     ::LYD_PARSE_STRICT, ::LYD_PARSE_OPAQ or ::LYD_VALIDATE_PRESENT options.
 *   - *complete configuration-only datastore* (such as :startup): in this case it is necessary to except all state data
 *     using ::LYD_PARSE_NO_STATE option.
 *   - *incomplete datastore*: there are situation when the data tree is incomplete or invalid by specification. For
 *     example the *:operational* datastore is not necessarily valid and results of the NETCONF's \<get\> or \<get-config\>
 *     oprations used with filters will be incomplete (and thus invalid). This can be allowed using ::LYD_PARSE_ONLY,
 *     the ::LYD_PARSE_NO_STATE should be used for the data returned by \<get-config\> operation.
 * - ::lyd_parse_rpc() is used for parsing RPCs/Actions, optionally including the RPC envelopes known from the NETCONF
 *   protocol.
 * - ::lyd_parse_reply() processes reply to a previous RPC/Action, which must be provided.
 * - ::lyd_parse_notif() is able to process complete Notification message.
 *
 * Further information regarding the processing input instance data can be found on the following pages.
 * - @subpage howtoDataValidation
 * - @subpage howtoDataWD
 *
 * Functions List
 * --------------
 * - ::lyd_parse_data()
 * - ::lyd_parse_data_mem()
 * - ::lyd_parse_data_fd()
 * - ::lyd_parse_data_path()
 * - ::lyd_parse_rpc()
 * - ::lyd_parse_reply()
 * - ::lyd_parse_notif()
 */

/**
 * @page howtoDataValidation Validating Data
 *
 * Data validation is performed implicitly to the input data processed by the [parser](@ref howtoDataParsers) and
 * on demand via the lyd_validate_*() functions. The explicit validation process is supposed to be used when a (complex or
 * simple) change is done on the data tree (via [data manipulation](@ref howtoDataManipulation) functions) and the data
 * tree is expected to be valid (it doesn't make sense to validate modified result of filtered \<get\> operation).
 *
 * Similarly to the [data parser](@ref howtoDataParsers), there are individual functions to validate standard data tree
 * (::lyd_validate_all()) and RPC, Action and Notification (::lyd_validate_op()). For the standard data trees, it is possible
 * to modify the validation process by @ref datavalidationoptions. This way the state data can be prohibited
 * (::LYD_VALIDATE_NO_STATE) and checking for mandatory nodes can be limited to the YANG modules with already present data
 * instances (::LYD_VALIDATE_PRESENT). Validation of the standard data tree can be also limited with ::lyd_validate_module()
 * function, which scopes only to a specified single YANG module.
 *
 * Since the operation data trees (RPCs, Actions or Notifications) can reference (leafref, instance-identifier, when/must
 * expressions) data from a datastore tree, ::lyd_validate_op() may require additional data tree to be provided. This is a
 * difference in contrast to the parsing process, when the data are loaded from an external source and invalid reference
 * outside the operation tree is acceptable.
 *
 * Functions List
 * --------------
 * - ::lyd_validate_all()
 * - ::lyd_validate_module()
 * - ::lyd_validate_op()
 */

/**
 * @addtogroup datatree
 * @{
 */

/**
 * @ingroup datatree
 * @defgroup dataparseroptions Data parser options
 *
 * Various options to change the data tree parsers behavior.
 *
 * Default parser behavior:
 * - complete input file is always parsed. In case of XML, even not well-formed XML document (multiple top-level
 * elements) is parsed in its entirety,
 * - parser silently ignores data without matching schema node definition,
 * - list instances are checked whether they have all the keys, error is raised if not.
 *
 * Default parser validation behavior:
 * - the provided data are expected to provide complete datastore content (both the configuration and state data)
 * and performs data validation according to all YANG rules, specifics follow,
 * - list instances are expected to have all the keys (it is not checked),
 * - instantiated (status) obsolete data print a warning,
 * - all types are fully resolved (leafref/instance-identifier targets, unions) and must be valid (lists have
 * all the keys, leaf(-lists) correct values),
 * - when statements on existing nodes are evaluated, if not satisfied, a validation error is raised,
 * - if-feature statements are evaluated,
 * - invalid multiple data instances/data from several cases cause a validation error,
 * - implicit nodes (NP containers and default values) are added.
 * @{
 */
/* note: keep the lower 16bits free for use by LYD_VALIDATE_ flags. They are not supposed to be combined together,
 * but since they are used (as a separate parameter) together in some functions, we want to keep them in a separated
 * range to be able detect that the caller put wrong flags into the parser/validate options parameter. */
#define LYD_PARSE_ONLY      0x010000        /**< Data will be only parsed and no validation will be performed. When statements
                                                 are kept unevaluated, union types may not be fully resolved, if-feature
                                                 statements are not checked, and default values are not added (only the ones
                                                 parsed are present). */
#define LYD_PARSE_STRICT    0x020000        /**< Instead of silently ignoring data without schema definition raise an error.
                                                 Do not combine with ::LYD_PARSE_OPAQ (except for ::LYD_LYB). */
#define LYD_PARSE_OPAQ      0x040000        /**< Instead of silently ignoring data without definition, parse them into
                                                 an opaq node. Do not combine with ::LYD_PARSE_STRICT (except for ::LYD_LYB). */
#define LYD_PARSE_NO_STATE  0x080000        /**< Forbid state data in the parsed data. Usually used with ::LYD_VALIDATE_NO_STATE. */

#define LYD_PARSE_LYB_MOD_UPDATE  0x100000  /**< Only for LYB format, allow parsing data printed using a specific module
                                                 revision to be loaded even with a module with the same name but newer
                                                 revision. */

#define LYD_PARSE_OPTS_MASK 0xFFFF0000      /**< Mask for all the LYD_PARSE_ options. */

/** @} dataparseroptions */

/**
 * @ingroup datatree
 * @defgroup datavalidationoptions Data validation options
 *
 * Various options to change data validation behaviour, both for the parser and separate validation.
 *
 * Default separate validation behavior:
 * - the provided data are expected to provide complete datastore content (both the configuration and state data)
 * and performs data validation according to all YANG rules, specifics follow,
 * - instantiated (status) obsolete data print a warning,
 * - all types are fully resolved (leafref/instance-identifier targets, unions) and must be valid (lists have
 * all the keys, leaf(-lists) correct values),
 * - when statements on existing nodes are evaluated. Depending on the previous when state (from previous validation
 * or parsing), the node is silently auto-deleted if the state changed from true to false, otherwise a validation error
 * is raised if it evaluates to false,
 * - if-feature statements are evaluated,
 * - data from several cases behave based on their previous state (from previous validation or parsing). If there existed
 * already a case and another one was added, the previous one is silently auto-deleted. Otherwise (if data from 2 or
 * more cases were created) a validation error is raised,
 * - default values are added.
 *
 * @{
 */
#define LYD_VALIDATE_NO_STATE   0x0001      /**< Consider state data not allowed and raise an error if they are found.
                                                 Also, no implicit state data are added. */
#define LYD_VALIDATE_PRESENT    0x0002      /**< Validate only modules whose data actually exist. */

#define LYD_VALIDATE_OPTS_MASK  0x0000FFFF  /**< Mask for all the LYD_VALIDATE_* options. */

/** @} datavalidationoptions */

/**
 * @ingroup datatree
 * @defgroup datavalidateop Operation to validate
 *
 * Operation provided to ::lyd_validate_op() to validate.
 *
 * The operation cannot be determined automatically since RPC/action and a reply to it share the common top level node
 * referencing the RPC/action schema node and may not have any input/output children to use for distinction.
 *
 * @{
 */
typedef enum {
    LYD_VALIDATE_OP_RPC = 1,   /**< Validate RPC/action request (input parameters). */
    LYD_VALIDATE_OP_REPLY,     /**< Validate RPC/action reply (output parameters). */
    LYD_VALIDATE_OP_NOTIF      /**< Validate Notification operation. */
} LYD_VALIDATE_OP;

/** @} datavalidateop */

/**
 * @brief Parse (and validate) data from the input handler as a YANG data tree.
 *
 * @param[in] ctx Context to connect with the tree being built here.
 * @param[in] in The input handle to provide the dumped data in the specified @p format to parse (and validate).
 * @param[in] format Format of the input data to be parsed. Can be 0 to try to detect format from the input handler.
 * @param[in] parse_options Options for parser, see @ref dataparseroptions.
 * @param[in] validate_options Options for the validation phase, see @ref datavalidationoptions.
 * @param[out] tree Resulting data tree built from the input data. Note that NULL can be a valid result as a representation of an empty YANG data tree.
 * The returned data are expected to be freed using ::lyd_free_all().
 * @return LY_SUCCESS in case of successful parsing (and validation).
 * @return LY_ERR value in case of error. Additional error information can be obtained from the context using ly_err* functions.
 */
LY_ERR lyd_parse_data(const struct ly_ctx *ctx, struct ly_in *in, LYD_FORMAT format, uint32_t parse_options,
        uint32_t validate_options, struct lyd_node **tree);

/**
 * @brief Parse (and validate) input data as a YANG data tree.
 *
 * Wrapper around ::lyd_parse_data() hiding work with the input handler.
 *
 * @param[in] ctx Context to connect with the tree being built here.
 * @param[in] data The input data in the specified @p format to parse (and validate).
 * @param[in] format Format of the input data to be parsed. Can be 0 to try to detect format from the input handler.
 * @param[in] parse_options Options for parser, see @ref dataparseroptions.
 * @param[in] validate_options Options for the validation phase, see @ref datavalidationoptions.
 * @param[out] tree Resulting data tree built from the input data. Note that NULL can be a valid result as a representation of an empty YANG data tree.
 * The returned data are expected to be freed using ::lyd_free_all().
 * @return LY_SUCCESS in case of successful parsing (and validation).
 * @return LY_ERR value in case of error. Additional error information can be obtained from the context using ly_err* functions.
 */
LY_ERR lyd_parse_data_mem(const struct ly_ctx *ctx, const char *data, LYD_FORMAT format, uint32_t parse_options,
        uint32_t validate_options, struct lyd_node **tree);

/**
 * @brief Parse (and validate) input data as a YANG data tree.
 *
 * Wrapper around ::lyd_parse_data() hiding work with the input handler.
 *
 * @param[in] ctx Context to connect with the tree being built here.
 * @param[in] fd File descriptor of a regular file (e.g. sockets are not supported) containing the input data in the specified @p format to parse (and validate).
 * @param[in] format Format of the input data to be parsed. Can be 0 to try to detect format from the input handler.
 * @param[in] parse_options Options for parser, see @ref dataparseroptions.
 * @param[in] validate_options Options for the validation phase, see @ref datavalidationoptions.
 * @param[out] tree Resulting data tree built from the input data. Note that NULL can be a valid result as a representation of an empty YANG data tree.
 * The returned data are expected to be freed using ::lyd_free_all().
 * @return LY_SUCCESS in case of successful parsing (and validation).
 * @return LY_ERR value in case of error. Additional error information can be obtained from the context using ly_err* functions.
 */
LY_ERR lyd_parse_data_fd(const struct ly_ctx *ctx, int fd, LYD_FORMAT format, uint32_t parse_options, uint32_t validate_options,
        struct lyd_node **tree);

/**
 * @brief Parse (and validate) input data as a YANG data tree.
 *
 * Wrapper around ::lyd_parse_data() hiding work with the input handler.
 *
 * @param[in] ctx Context to connect with the tree being built here.
 * @param[in] path Path to the file with the input data in the specified @p format to parse (and validate).
 * @param[in] format Format of the input data to be parsed. Can be 0 to try to detect format from the input handler.
 * @param[in] parse_options Options for parser, see @ref dataparseroptions.
 * @param[in] validate_options Options for the validation phase, see @ref datavalidationoptions.
 * @param[out] tree Resulting data tree built from the input data. Note that NULL can be a valid result as a representation of an empty YANG data tree.
 * The returned data are expected to be freed using ::lyd_free_all().
 * @return LY_SUCCESS in case of successful parsing (and validation).
 * @return LY_ERR value in case of error. Additional error information can be obtained from the context using ly_err* functions.
 */
LY_ERR lyd_parse_data_path(const struct ly_ctx *ctx, const char *path, LYD_FORMAT format, uint32_t parse_options,
        uint32_t validate_options, struct lyd_node **tree);

/**
 * @brief Parse (no validation) data from the input handler as a YANG RPC/action request.
 *
 * @param[in] ctx Context to connect with the tree being parsed.
 * @param[in] in Input handle to provide the dumped data in the specified @p format to parse.
 * @param[in] format Format of the input data to be parsed.
 * @param[out] tree Resulting full RPC/action request tree built from the input data. The returned data are expected to be freed using ::lyd_free_all().
 * In contrast to YANG data tree, result of parsing RPC/action cannot be NULL until an error occurs.
 * @param[out] op Optional pointer to the actual operation node inside the full action @p tree, useful only for action.
 * @return LY_SUCCESS in case of successful parsing.
 * @return LY_ERR value in case of error. Additional error information can be obtained from the context using ly_err* functions.
 */
LY_ERR lyd_parse_rpc(const struct ly_ctx *ctx, struct ly_in *in, LYD_FORMAT format, struct lyd_node **tree,
        struct lyd_node **op);

/**
 * @brief Parse (no validation) data from the input handler as a YANG RPC/action reply.
 *
 * @param[in] ctx Context to connect with the tree being parsed.
 * @param[in] in Input handle to provide the dumped data in the specified @p format to parse (and validate).
 * @param[in] format Format of the input data to be parsed.
 * @param[out] tree Resulting full RPC/action reply tree built from the input data. The returned data are expected to be freed using ::lyd_free_all().
 * In contrast to YANG data tree, result of parsing RPC/action cannot be NULL until an error occurs.
 * At least one of the @p tree and @p op output variables must be provided.
 * @param[out] op Pointer to the actual operation node inside the full action reply @p tree, useful only for action. At least one of the @p op
 * and @p tree output variables must be provided.
 * @return LY_SUCCESS in case of successful parsing.
 * @return LY_ERR value in case of error. Additional error information can be obtained from the request's context using ly_err* functions.
 */
LY_ERR lyd_parse_reply(const struct ly_ctx *ctx, struct ly_in *in, LYD_FORMAT format, struct lyd_node **tree,
        struct lyd_node **op);

/**
 * @brief Parse (no validation) data from the input handler as a YANG notification.
 *
 * @param[in] ctx Context to connect with the tree being parsed.
 * @param[in] in Input handle to provide the dumped data in the specified @p format to parse (and validate).
 * @param[in] format Format of the input data to be parsed.
 * @param[out] tree Resulting full notification tree built from the input data. The returned data are expected to be freed using ::lyd_free_all().
 * In contrast to YANG data tree, result of parsing notification cannot be NULL until an error occurs.
 * @param[out] ntf Optional pointer to the actual notification node inside the full notification @p tree, useful for nested notifications.
 * @return LY_SUCCESS in case of successful parsing.
 * @return LY_ERR value in case of error. Additional error information can be obtained from the context using ly_err* functions.
 */
LY_ERR lyd_parse_notif(const struct ly_ctx *ctx, struct ly_in *in, LYD_FORMAT format, struct lyd_node **tree,
        struct lyd_node **ntf);

/**
 * @brief Fully validate a data tree.
 *
 * @param[in,out] tree Data tree to recursively validate. May be changed by validation.
 * @param[in] ctx libyang context. Can be NULL if @p tree is set.
 * @param[in] val_opts Validation options (@ref datavalidationoptions).
 * @param[out] diff Optional diff with any changes made by the validation.
 * @return LY_SUCCESS on success.
 * @return LY_ERR error on error.
 */
LY_ERR lyd_validate_all(struct lyd_node **tree, const struct ly_ctx *ctx, uint32_t val_opts, struct lyd_node **diff);

/**
 * @brief Fully validate a data tree of a module.
 *
 * @param[in,out] tree Data tree to recursively validate. May be changed by validation.
 * @param[in] module Module whose data (and schema restrictions) to validate.
 * @param[in] val_opts Validation options (@ref datavalidationoptions).
 * @param[out] diff Optional diff with any changes made by the validation.
 * @return LY_SUCCESS on success.
 * @return LY_ERR error on error.
 */
LY_ERR lyd_validate_module(struct lyd_node **tree, const struct lys_module *module, uint32_t val_opts, struct lyd_node **diff);

/**
 * @brief Validate an RPC/action, notification, or RPC/action reply.
 *
 * @param[in,out] op_tree Operation tree with any parents. It can point to the operation itself or any of
 * its parents, only the operation subtree is actually validated.
 * @param[in] tree Tree to be used for validating references from the operation subtree.
 * @param[in] op Operation to validate (@ref datavalidateop), the given @p op_tree must correspond to this value. Note that
 * it isn't possible to detect the operation simply from the @p op_tree since RPC/action and their reply share the same
 * RPC/action data node and in case one of the input and output do not define any data node children, it is not possible
 * to get know what is here given for validation and if it is really valid.
 * @param[out] diff Optional diff with any changes made by the validation.
 * @return LY_SUCCESS on success.
 * @return LY_ERR error on error.
 */
LY_ERR lyd_validate_op(struct lyd_node *op_tree, const struct lyd_node *tree, LYD_VALIDATE_OP op, struct lyd_node **diff);

/** @} datatree */

#ifdef __cplusplus
}
#endif

#endif /* LY_PARSER_DATA_H_ */