edns.c revision 356345 
1/*
2 * util/edns.c - handle base EDNS options.
3 *
4 * Copyright (c) 2018, 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 functions for base EDNS options.
40 */
41
42#include "config.h"
43#include "util/edns.h"
44#include "util/config_file.h"
45#include "util/netevent.h"
46#include "util/regional.h"
47#include "util/data/msgparse.h"
48#include "util/data/msgreply.h"
49
50#include "edns.h"
51
52static int edns_keepalive(struct edns_data* edns_out, struct edns_data* edns_in,
53		struct comm_point* c, struct regional* region)
54{
55	if(c->type == comm_udp)
56		return 1;
57
58	/* To respond with a Keepalive option, the client connection
59	 * must have received one message with a TCP Keepalive EDNS option,
60	 * and that option must have 0 length data. Subsequent messages
61	 * sent on that connection will have a TCP Keepalive option.
62	 */
63	if(c->tcp_keepalive ||
64		edns_opt_list_find(edns_in->opt_list, LDNS_EDNS_KEEPALIVE)) {
65		int keepalive = c->tcp_timeout_msec / 100;
66		uint8_t data[2];
67		data[0] = (uint8_t)((keepalive >> 8) & 0xff);
68		data[1] = (uint8_t)(keepalive & 0xff);
69		if(!edns_opt_list_append(&edns_out->opt_list, LDNS_EDNS_KEEPALIVE,
70			sizeof(data), data, region))
71			return 0;
72		c->tcp_keepalive = 1;
73	}
74	return 1;
75}
76
77int apply_edns_options(struct edns_data* edns_out, struct edns_data* edns_in,
78	struct config_file* cfg, struct comm_point* c, struct regional* region)
79{
80	if(cfg->do_tcp_keepalive &&
81		!edns_keepalive(edns_out, edns_in, c, region))
82		return 0;
83
84	return 1;
85}
86