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/net_help.h"
47#include "util/regional.h"
48#include "util/rfc_1982.h"
49#include "util/siphash.h"
50#include "util/data/msgparse.h"
51#include "util/data/msgreply.h"
52#include "sldns/sbuffer.h"
53
54#if 0
55/* XXX: remove me */
56#include "edns.h"
57#endif
58
59struct edns_strings* edns_strings_create(void)
60{
61	struct edns_strings* edns_strings = calloc(1,
62		sizeof(struct edns_strings));
63	if(!edns_strings)
64		return NULL;
65	if(!(edns_strings->region = regional_create())) {
66		edns_strings_delete(edns_strings);
67		return NULL;
68	}
69	return edns_strings;
70}
71
72void edns_strings_delete(struct edns_strings* edns_strings)
73{
74	if(!edns_strings)
75		return;
76	regional_destroy(edns_strings->region);
77	free(edns_strings);
78}
79
80static int
81edns_strings_client_insert(struct edns_strings* edns_strings,
82	struct sockaddr_storage* addr, socklen_t addrlen, int net,
83	const char* string)
84{
85	struct edns_string_addr* esa = regional_alloc_zero(edns_strings->region,
86		sizeof(struct edns_string_addr));
87	if(!esa)
88		return 0;
89	esa->string_len = strlen(string);
90	esa->string = regional_alloc_init(edns_strings->region, string,
91		esa->string_len);
92	if(!esa->string)
93		return 0;
94	if(!addr_tree_insert(&edns_strings->client_strings, &esa->node, addr,
95		addrlen, net)) {
96		verbose(VERB_QUERY, "duplicate EDNS client string ignored.");
97	}
98	return 1;
99}
100
101int edns_strings_apply_cfg(struct edns_strings* edns_strings,
102	struct config_file* config)
103{
104	struct config_str2list* c;
105	regional_free_all(edns_strings->region);
106	addr_tree_init(&edns_strings->client_strings);
107
108	for(c=config->edns_client_strings; c; c=c->next) {
109		struct sockaddr_storage addr;
110		socklen_t addrlen;
111		int net;
112		log_assert(c->str && c->str2);
113
114		if(!netblockstrtoaddr(c->str, UNBOUND_DNS_PORT, &addr, &addrlen,
115			&net)) {
116			log_err("cannot parse EDNS client string IP netblock: "
117				"%s", c->str);
118			return 0;
119		}
120		if(!edns_strings_client_insert(edns_strings, &addr, addrlen,
121			net, c->str2)) {
122			log_err("out of memory while adding EDNS strings");
123			return 0;
124		}
125	}
126	edns_strings->client_string_opcode = config->edns_client_string_opcode;
127
128	addr_tree_init_parents(&edns_strings->client_strings);
129	return 1;
130}
131
132struct edns_string_addr*
133edns_string_addr_lookup(rbtree_type* tree, struct sockaddr_storage* addr,
134	socklen_t addrlen)
135{
136	return (struct edns_string_addr*)addr_tree_lookup(tree, addr, addrlen);
137}
138
139uint8_t*
140edns_cookie_server_hash(const uint8_t* in, const uint8_t* secret, int v4,
141	uint8_t* hash)
142{
143	v4?siphash(in, 20, secret, hash, 8):siphash(in, 32, secret, hash, 8);
144	return hash;
145}
146
147void
148edns_cookie_server_write(uint8_t* buf, const uint8_t* secret, int v4,
149	uint32_t timestamp)
150{
151	uint8_t hash[8];
152	buf[ 8] = 1;   /* Version */
153	buf[ 9] = 0;   /* Reserved */
154	buf[10] = 0;   /* Reserved */
155	buf[11] = 0;   /* Reserved */
156	sldns_write_uint32(buf + 12, timestamp);
157	(void)edns_cookie_server_hash(buf, secret, v4, hash);
158	memcpy(buf + 16, hash, 8);
159}
160
161enum edns_cookie_val_status
162edns_cookie_server_validate(const uint8_t* cookie, size_t cookie_len,
163	const uint8_t* secret, size_t secret_len, int v4,
164	const uint8_t* hash_input, uint32_t now)
165{
166	uint8_t hash[8];
167	uint32_t timestamp;
168	uint32_t subt_1982 = 0; /* Initialize for the compiler; unused value */
169	int comp_1982;
170	if(cookie_len != 24)
171		/* RFC9018 cookies are 24 bytes long */
172		return COOKIE_STATUS_CLIENT_ONLY;
173	if(secret_len != 16 ||  /* RFC9018 cookies have 16 byte secrets */
174		cookie[8] != 1) /* RFC9018 cookies are cookie version 1 */
175		return COOKIE_STATUS_INVALID;
176	timestamp = sldns_read_uint32(cookie + 12);
177	if((comp_1982 = compare_1982(now, timestamp)) > 0
178		&& (subt_1982 = subtract_1982(timestamp, now)) > 3600)
179		/* Cookie is older than 1 hour (see RFC9018 Section 4.3.) */
180		return COOKIE_STATUS_EXPIRED;
181	if(comp_1982 <= 0 && subtract_1982(now, timestamp) > 300)
182		/* Cookie time is more than 5 minutes in the future.
183		 * (see RFC9018 Section 4.3.) */
184		return COOKIE_STATUS_FUTURE;
185	if(memcmp(edns_cookie_server_hash(hash_input, secret, v4, hash),
186		cookie + 16, 8) != 0)
187		/* Hashes do not match */
188		return COOKIE_STATUS_INVALID;
189	if(comp_1982 > 0 && subt_1982 > 1800)
190		/* Valid cookie but older than 30 minutes, so create a new one
191		 * anyway */
192		return COOKIE_STATUS_VALID_RENEW;
193	return COOKIE_STATUS_VALID;
194}
195