unbound-event.h revision 269257 
1/*
2 * unbound-event.h - unbound validating resolver public API with events
3 *
4 * Copyright (c) 2007, 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 the unbound interface for use with libevent.
40 * You have to use the same libevent that unbound was compiled with,
41 * otherwise it wouldn't work, the event and event_base structures would
42 * be different.  If unbound is compiled without libevent support then
43 * this header file is not supposed to be installed on the system.
44 *
45 * Use ub_ctx_create_event_base() to create an unbound context that uses
46 * the event base that you have made.  Then, use the ub_resolve_event call
47 * to add DNS resolve queries to the context.  Those then run when you
48 * call event_dispatch() on your event_base, and when they are done you
49 * get a function callback.
50 *
51 * This method does not fork another process or create a thread, the effort
52 * is done by the unbound state machines that are connected to the event_base.
53 */
54#ifndef _UB_UNBOUND_EVENT_H
55#define _UB_UNBOUND_EVENT_H
56
57#ifdef __cplusplus
58extern "C" {
59#endif
60
61struct ub_ctx;
62struct ub_result;
63struct event_base;
64
65typedef void (*ub_event_callback_t)(void*, int, void*, int, int, char*);
66
67/**
68 * Create a resolving and validation context.
69 * The information from /etc/resolv.conf and /etc/hosts is not utilised by
70 * default. Use ub_ctx_resolvconf and ub_ctx_hosts to read them.
71 * @param base: the event base that the caller has created.  The unbound
72 *	context uses this event base.
73 * @return a new context. default initialisation.
74 * 	returns NULL on error.
75 * You must use ub_resolve_event with this context.
76 * Do not call ub_ctx_async, ub_poll, ub_wait, ub_process, this is all done
77 * with the event_base.  Setup the options you like with the other functions.
78 */
79struct ub_ctx* ub_ctx_create_event(struct event_base* base);
80
81/**
82 * Set a new event_base on a context created with ub_ctx_create_event.
83 * Any outbound queries will be canceled.
84 * @param ctx the ub_ctx to update.  Must have been created with ub_ctx_create_event
85 * @param base the new event_base to attach to the ctx
86 * @return 0 if OK, else error
87 */
88int ub_ctx_set_event(struct ub_ctx* ctx, struct event_base* base);
89
90/**
91 * Perform resolution and validation of the target name.
92 * Asynchronous, after a while, the callback will be called with your
93 * data and the result.  Uses the event_base user installed by creating the
94 * context with ub_ctx_create_event().
95 * @param ctx: context with event_base in it.
96 *	The context is finalized, and can no longer accept all config changes.
97 * @param name: domain name in text format (a string).
98 * @param rrtype: type of RR in host order, 1 is A.
99 * @param rrclass: class of RR in host order, 1 is IN (for internet).
100 * @param mydata: this data is your own data (you can pass NULL),
101 * 	and is passed on to the callback function.
102 * @param callback: this is called on completion of the resolution.
103 * 	It is called as:
104 * 	void callback(void* mydata, int rcode, void* packet, int packet_len,
105 * 		int sec, char* why_bogus)
106 * 	with mydata: the same as passed here, you may pass NULL,
107 * 	with rcode: 0 on no error, nonzero for mostly SERVFAIL situations,
108 *		this is a DNS rcode.
109 *	with packet: a buffer with DNS wireformat packet with the answer.
110 *		do not inspect if rcode != 0.
111 *		do not write or free the packet buffer, it is used internally
112 *		in unbound (for other callbacks that want the same data).
113 *	with packet_len: length in bytes of the packet buffer.
114 *	with sec: 0 if insecure, 1 if bogus, 2 if DNSSEC secure.
115 *	with why_bogus: text string explaining why it is bogus (or NULL).
116 *	These point to buffers inside unbound; do not deallocate the packet or
117 *	error string.
118 *
119 * 	If an error happens during processing, your callback will be called
120 * 	with error set to a nonzero value (and result==NULL).
121 * 	For localdata (etc/hosts) the callback is called immediately, before
122 * 	resolve_event returns, async_id=0 is returned.
123 * @param async_id: if you pass a non-NULL value, an identifier number is
124 *	returned for the query as it is in progress. It can be used to
125 *	cancel the query.
126 * @return 0 if OK, else error.
127 */
128int ub_resolve_event(struct ub_ctx* ctx, const char* name, int rrtype,
129	int rrclass, void* mydata, ub_event_callback_t callback, int* async_id);
130
131#ifdef __cplusplus
132}
133#endif
134
135#endif /* _UB_UNBOUND_H */
136