1/*
2 * libwebsockets - small server side websockets and web server implementation
3 *
4 * Copyright (C) 2010 - 2019 Andy Green <andy@warmcat.com>
5 *
6 * Permission is hereby granted, free of charge, to any person obtaining a copy
7 * of this software and associated documentation files (the "Software"), to
8 * deal in the Software without restriction, including without limitation the
9 * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
10 * sell copies of the Software, and to permit persons to whom the Software is
11 * furnished to do so, subject to the following conditions:
12 *
13 * The above copyright notice and this permission notice shall be included in
14 * all copies or substantial portions of the Software.
15 *
16 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
17 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
18 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
19 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
20 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
21 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
22 * IN THE SOFTWARE.
23 */
24
25
26#define DNS_MAX			96	/* Maximum host name		*/
27#define DNS_RECURSION_LIMIT	3
28#define DNS_PACKET_LEN		1400	/* Buffer size for DNS packet	*/
29#define MAX_CACHE_ENTRIES	10	/* Dont cache more than that	*/
30#define DNS_QUERY_TIMEOUT	30	/* Query timeout, seconds	*/
31
32/*
33 * ... when we completed a query then the query object is destroyed and a
34 * cache object below is created with the results in getaddrinfo format
35 * appended to the allocation
36 */
37
38typedef struct lws_adns_cache {
39	lws_sorted_usec_list_t	sul;	/* for cache TTL management */
40	lws_dll2_t		list;
41
42	struct lws_adns_cache	*firstcache;
43	struct lws_adns_cache	*chain;
44	struct addrinfo		*results;
45	const char		*name;
46	uint8_t			flags;	/* b0 = has ipv4, b1 = has ipv6 */
47	char			refcount;
48	char			incomplete;
49	/* addrinfo, lws_sa46, then name overallocated here */
50} lws_adns_cache_t;
51
52/*
53 * these objects are used while a query is ongoing...
54 */
55
56typedef struct {
57	lws_sorted_usec_list_t	sul;	/* per-query write retry timer */
58	lws_sorted_usec_list_t	write_sul;	/* fail if unable to write by this time */
59	lws_dll2_t		list;
60
61	lws_metrics_caliper_compose(metcal)
62
63	lws_dll2_owner_t	wsi_adns;
64	lws_async_dns_cb_t	standalone_cb;	/* if not associated to wsi */
65	struct lws_context	*context;
66	void			*opaque;
67	struct addrinfo		**last;
68	lws_async_dns_t		*dns;
69
70	lws_adns_cache_t	*firstcache;
71
72	lws_async_dns_retcode_t	ret;
73	uint16_t		tid[3]; /* last 3 sent tid */
74	uint16_t		qtype;
75	uint16_t		retry;
76	uint8_t			tsi;
77
78#if defined(LWS_WITH_IPV6)
79	uint8_t			sent[2];
80#else
81	uint8_t			sent[1];
82#endif
83	uint8_t			asked;
84	uint8_t			responded;
85
86	uint8_t			recursion;
87	uint8_t			tids;
88	uint8_t			go_nogo;
89
90	uint8_t			is_retry:1;
91
92	/* name overallocated here */
93} lws_adns_q_t;
94
95#define LADNS_MOST_RECENT_TID(_q) \
96		q->tid[(int)(_q->tids - 1) % (int)LWS_ARRAY_SIZE(q->tid)]
97
98enum {
99	DHO_TID,
100	DHO_FLAGS = 2,
101	DHO_NQUERIES = 4,
102	DHO_NANSWERS = 6,
103	DHO_NAUTH = 8,
104	DHO_NOTHER = 10,
105
106	DHO_SIZEOF = 12 /* last */
107};
108
109void
110lws_adns_q_destroy(lws_adns_q_t *q);
111
112void
113sul_cb_expire(struct lws_sorted_usec_list *sul);
114
115void
116lws_adns_cache_destroy(lws_adns_cache_t *c);
117
118int
119lws_async_dns_complete(lws_adns_q_t *q, lws_adns_cache_t *c);
120
121lws_adns_cache_t *
122lws_adns_get_cache(lws_async_dns_t *dns, const char *name);
123
124void
125lws_adns_parse_udp(lws_async_dns_t *dns, const uint8_t *pkt, size_t len);
126
127lws_adns_q_t *
128lws_adns_get_query(lws_async_dns_t *dns, adns_query_type_t qtype,
129		   lws_dll2_owner_t *owner, uint16_t tid, const char *name);
130
131void
132lws_async_dns_trim_cache(lws_async_dns_t *dns);
133
134int
135lws_async_dns_get_new_tid(struct lws_context *context, lws_adns_q_t *q);
136
137
138#if defined(_DEBUG)
139void
140lws_adns_dump(lws_async_dns_t *dns);
141#else
142#define lws_adns_dump(_d)
143#endif
144