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/*
* cachedb/cachedb.h - cache from a database external to the program module
*
* Copyright (c) 2016, NLnet Labs. All rights reserved.
*
* This software is open source.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
*
* Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* Neither the name of the NLNET LABS nor the names of its contributors may
* be used to endorse or promote products derived from this software without
* specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
* TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
/**
* \file
*
* This file contains a module that uses an external database to cache
* dns responses.
*/
#include "util/module.h"
struct cachedb_backend;
struct module_stack;
/**
* The global variable environment contents for the cachedb
* Shared between threads, this represents long term information.
* Like database connections.
*/
struct cachedb_env {
/** true is cachedb is enabled, the backend is turned on */
int enabled;
/** the backend routines */
struct cachedb_backend* backend;
/** backend specific data here */
void* backend_data;
};
/**
* Per query state for the cachedb module.
*/
struct cachedb_qstate {
int todo;
};
/**
* Backend call routines
*/
struct cachedb_backend {
/** backend name */
const char* name;
/** Init(env, cachedb_env): false on setup failure */
int (*init)(struct module_env*, struct cachedb_env*);
/** Deinit - close db for program exit */
void (*deinit)(struct module_env*, struct cachedb_env*);
/** Lookup (env, cachedb_env, key, result_buffer): true if found */
int (*lookup)(struct module_env*, struct cachedb_env*, char*,
struct sldns_buffer*);
/** Store (env, cachedb_env, key, data, data_len) */
void (*store)(struct module_env*, struct cachedb_env*, char*,
uint8_t*, size_t, time_t);
};
#define CACHEDB_HASHSIZE 256 /* bit hash */
/** Init the cachedb module */
int cachedb_init(struct module_env* env, int id);
/** Deinit the cachedb module */
void cachedb_deinit(struct module_env* env, int id);
/** Operate on an event on a query (in qstate). */
void cachedb_operate(struct module_qstate* qstate, enum module_ev event,
int id, struct outbound_entry* outbound);
/** Subordinate query done, inform this super request of its conclusion */
void cachedb_inform_super(struct module_qstate* qstate, int id,
struct module_qstate* super);
/** clear the cachedb query-specific contents out of qstate */
void cachedb_clear(struct module_qstate* qstate, int id);
/** return memory estimate for cachedb module */
size_t cachedb_get_mem(struct module_env* env, int id);
/**
* Get the function block with pointers to the cachedb functions
* @return the function block for "cachedb".
*/
struct module_func_block* cachedb_get_funcblock(void);
/**
* See if the cachedb is enabled.
* @param mods: module stack. It finds the cachedb module environment.
* @param env: module environment.
* @return true if exists and enabled.
*/
int cachedb_is_enabled(struct module_stack* mods, struct module_env* env);
/**
* Remove a message from the global cache. Because edns subnet has a more
* specific entry, and if not removed when everything expires, the global
* entry is used, instead of a fresh lookup of the edns subnet entry.
* @param qstate: query state.
*/
void cachedb_msg_remove(struct module_qstate* qstate);
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