cachedb.h revision 356345 
1/*
2 * cachedb/cachedb.h - cache from a database external to the program module
3 *
4 * Copyright (c) 2016, NLnet Labs. All rights reserved.
5 *
6 * This software is open source.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 *
12 * Redistributions of source code must retain the above copyright notice,
13 * this list of conditions and the following disclaimer.
14 *
15 * Redistributions in binary form must reproduce the above copyright notice,
16 * this list of conditions and the following disclaimer in the documentation
17 * and/or other materials provided with the distribution.
18 *
19 * Neither the name of the NLNET LABS nor the names of its contributors may
20 * be used to endorse or promote products derived from this software without
21 * specific prior written permission.
22 *
23 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
24 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
25 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
26 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
27 * HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
28 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
29 * TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
30 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
31 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
32 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
33 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
34 */
35
36/**
37 * \file
38 *
39 * This file contains a module that uses an external database to cache
40 * dns responses.
41 */
42#include "util/module.h"
43struct cachedb_backend;
44
45/**
46 * The global variable environment contents for the cachedb
47 * Shared between threads, this represents long term information.
48 * Like database connections.
49 */
50struct cachedb_env {
51	/** true is cachedb is enabled, the backend is turned on */
52	int enabled;
53
54	/** the backend routines */
55	struct cachedb_backend* backend;
56
57	/** backend specific data here */
58	void* backend_data;
59};
60
61/**
62 * Per query state for the cachedb module.
63 */
64struct cachedb_qstate {
65	int todo;
66};
67
68/**
69 * Backend call routines
70 */
71struct cachedb_backend {
72	/** backend name */
73	const char* name;
74
75	/** Init(env, cachedb_env): false on setup failure */
76	int (*init)(struct module_env*, struct cachedb_env*);
77
78	/** Deinit - close db for program exit */
79	void (*deinit)(struct module_env*, struct cachedb_env*);
80
81	/** Lookup (env, cachedb_env, key, result_buffer): true if found */
82	int (*lookup)(struct module_env*, struct cachedb_env*, char*,
83		struct sldns_buffer*);
84
85	/** Store (env, cachedb_env, key, data, data_len) */
86	void (*store)(struct module_env*, struct cachedb_env*, char*,
87		uint8_t*, size_t);
88};
89
90#define CACHEDB_HASHSIZE 256 /* bit hash */
91
92/** Init the cachedb module */
93int cachedb_init(struct module_env* env, int id);
94/** Deinit the cachedb module */
95void cachedb_deinit(struct module_env* env, int id);
96/** Operate on an event on a query (in qstate). */
97void cachedb_operate(struct module_qstate* qstate, enum module_ev event,
98	int id, struct outbound_entry* outbound);
99/** Subordinate query done, inform this super request of its conclusion */
100void cachedb_inform_super(struct module_qstate* qstate, int id,
101	struct module_qstate* super);
102/** clear the cachedb query-specific contents out of qstate */
103void cachedb_clear(struct module_qstate* qstate, int id);
104/** return memory estimate for cachedb module */
105size_t cachedb_get_mem(struct module_env* env, int id);
106
107/**
108 * Get the function block with pointers to the cachedb functions
109 * @return the function block for "cachedb".
110 */
111struct module_func_block* cachedb_get_funcblock(void);
112
113