269 lines
8.3 KiB
C
269 lines
8.3 KiB
C
/*
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* Copyright (c) 2018 MariaDB Corporation Ab
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*
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* Use of this software is governed by the Business Source License included
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* in the LICENSE.TXT file and at www.mariadb.com/bsl11.
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*
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* Change Date: 2022-01-01
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*
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* On the date above, in accordance with the Business Source License, use
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* of this software will be governed by version 2 or later of the General
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* Public License.
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*/
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#pragma once
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/**
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* @file include/maxscale/filter.h - The public filter interface
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*/
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#include <maxscale/cdefs.h>
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#include <stdint.h>
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#include <maxbase/jansson.h>
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#include <maxscale/buffer.h>
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#include <maxscale/config.h>
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#include <maxscale/dcb.h>
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#include <maxscale/routing.h>
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#include <maxscale/session.h>
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MXS_BEGIN_DECLS
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/**
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* MXS_FILTER is an opaque type representing a particular filter instance.
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*
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* MaxScale itself does not do anything with it, except for receiving it
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* from the @c createInstance function of a filter module and subsequently
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* passing it back to the API functions of the filter.
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*/
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typedef struct mxs_filter
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{
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} MXS_FILTER;
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/**
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* MXS_FILTER_SESSION is an opaque type representing the session related
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* data of a particular filter instance.
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*
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* MaxScale itself does not do anything with it, except for receiving it
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* from the @c newSession function of a filter module and subsequently
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* passing it back to the API functions of the filter.
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*/
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typedef struct mxs_filter_session
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{
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} MXS_FILTER_SESSION;
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/**
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* @verbatim
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* The "module object" structure for a filter module. All entry points
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* marked with `(optional)` are optional entry points which can be set to NULL
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* if no implementation is required.
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*
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* The entry points are:
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* createInstance Called by the service to create a new instance of the filter
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* newSession Called to create a new user session within the filter
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* closeSession Called when a session is closed
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* freeSession Called when a session is freed
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* setDownstream Sets the downstream component of the filter pipline
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* setUpstream Sets the upstream component of the filter pipline
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* routeQuery Called on each query that requires routing
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* clientReply Called for each reply packet (optional)
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* diagnostics Called for diagnostic output
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* getCapabilities Called to obtain the capabilities of the filter (optional)
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* destroyInstance Called for destroying a filter instance (optional)
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*
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* @endverbatim
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*
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* @see load_module
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*/
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typedef struct mxs_filter_object
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{
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/**
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* @brief Create a new instance of the filter
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*
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* This function is called when a new filter instance is created. The return
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* value of this function will be passed as the first parameter to the
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* other API functions.
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*
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* @param name Name of the filter instance
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* @param params Filter parameters
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*
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* @return New filter instance on NULL on error
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*/
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MXS_FILTER*(*createInstance)(const char* name, MXS_CONFIG_PARAMETER* params);
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/**
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* Called to create a new user session within the filter
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*
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* This function is called when a new filter session is created for a client.
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* The return value of this function will be passed as the second parameter
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* to the @c routeQuery, @c clientReply, @c closeSession, @c freeSession,
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* @c setDownstream and @c setUpstream functions.
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*
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* @param instance Filter instance
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* @param session Client MXS_SESSION object
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*
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* @return New filter session or NULL on error
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*/
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MXS_FILTER_SESSION*(*newSession)(MXS_FILTER * instance, MXS_SESSION* session);
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/**
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* @brief Called when a session is closed
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*
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* The filter should close all objects but not free any memory.
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*
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* @param instance Filter instance
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* @param fsession Filter session
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*/
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void (* closeSession)(MXS_FILTER* instance, MXS_FILTER_SESSION* fsession);
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/**
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* @brief Called when a session is freed
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*
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* The session should free all allocated memory in this function.
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*
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* @param instance Filter instance
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* @param fsession Filter session
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*/
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void (* freeSession)(MXS_FILTER* instance, MXS_FILTER_SESSION* fsession);
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/**
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* @brief Sets the downstream component of the filter pipeline
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*
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* @param instance Filter instance
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* @param fsession Filter session
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*/
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void (* setDownstream)(MXS_FILTER* instance, MXS_FILTER_SESSION* fsession, MXS_DOWNSTREAM* downstream);
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/**
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* @brief Sets the upstream component of the filter pipeline
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*
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* @param instance Filter instance
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* @param fsession Filter session
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*/
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void (* setUpstream)(MXS_FILTER* instance, MXS_FILTER_SESSION* fsession, MXS_UPSTREAM* downstream);
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/**
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* @brief Called on each query that requires routing
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*
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* TODO: Document how routeQuery should be used
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*
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* @param instance Filter instance
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* @param fsession Filter session
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* @param queue Request from the client
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*
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* @return If successful, the function returns 1. If an error occurs
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* and the session should be closed, the function returns 0.
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*/
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int32_t (* routeQuery)(MXS_FILTER* instance, MXS_FILTER_SESSION* fsession, GWBUF* queue);
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/**
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* @brief Called for each reply packet
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*
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* TODO: Document how clientReply should be used
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*
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* @param instance Filter instance
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* @param fsession Filter session
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* @param queue Response from the server
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*
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* @return If successful, the function returns 1. If an error occurs
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* and the session should be closed, the function returns 0.
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*/
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int32_t (* clientReply)(MXS_FILTER* instance, MXS_FILTER_SESSION* fsession, GWBUF* queue);
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/**
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* @brief Called for diagnostic output
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*
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* @param instance Filter instance
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* @param fsession Filter session, NULL if general information about the filter is queried
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* @param dcb DCB where the diagnostic information should be written
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*/
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void (* diagnostics)(MXS_FILTER* instance, MXS_FILTER_SESSION* fsession, DCB* dcb);
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/**
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* @brief Called for diagnostic output
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*
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* @param instance Filter instance
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* @param fsession Filter session, NULL if general information about the filter is queried
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*
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* @return JSON formatted information about the filter
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*
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* @see jansson.h
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*/
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json_t* (*diagnostics_json)(const MXS_FILTER * instance, const MXS_FILTER_SESSION* fsession);
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/**
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* @brief Called to obtain the capabilities of the filter
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*
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* @return Zero or more bitwise-or'd values from the mxs_routing_capability_t enum
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*
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* @see routing.h
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*/
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uint64_t (* getCapabilities)(MXS_FILTER* instance);
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/**
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* @brief Called for destroying a filter instance
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*
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* @param instance Filter instance
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*/
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void (* destroyInstance)(MXS_FILTER* instance);
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} MXS_FILTER_OBJECT;
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/**
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* The filter API version. If the MXS_FILTER_OBJECT structure or the filter API
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* is changed these values must be updated in line with the rules in the
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* file modinfo.h.
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*/
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#define MXS_FILTER_VERSION {4, 0, 0}
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/**
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* MXS_FILTER_DEF represents a filter definition from the configuration file.
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* Its exact definition is private to MaxScale.
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*/
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struct mxs_filter_def;
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typedef struct mxs_filter_def
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{
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} MXS_FILTER_DEF;
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/**
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* Get the name of a filter definition. This corresponds to
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* to a filter section in the configuration file.
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*
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* @param filter_def A filter definition.
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*
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* @return The filter name.
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*/
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const char* filter_def_get_name(const MXS_FILTER_DEF* filter_def);
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/**
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* Get module name of a filter definition.
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*
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* @param filter_def A filter definition.
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*
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* @return The module name.
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*/
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const char* filter_def_get_module_name(const MXS_FILTER_DEF* filter_def);
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/**
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* Get the filter instance of a particular filter definition.
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*
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* @return A filter instance.
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*/
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MXS_FILTER* filter_def_get_instance(const MXS_FILTER_DEF* filter_def);
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/**
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* Specifies capabilities specific for filters. Common capabilities
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* are defined by @c routing_capability_t.
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*
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* @see enum routing_capability
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*
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* @note The values of the capabilities here *must* be between 0x80000000
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* and 0x01000000, that is, bits 24 to 31.
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*/
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typedef enum filter_capability
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{
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FCAP_TYPE_NONE = 0x0 // TODO: remove once filter capabilities are defined
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} filter_capability_t;
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MXS_END_DECLS
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