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#if defined(LWS_WITH_UDP) && defined(LWS_WITH_NETWORK)
26
27typedef enum dns_query_type {
28 LWS_ADNS_RECORD_A = 0x01,
29 LWS_ADNS_RECORD_CNAME = 0x05,
30 LWS_ADNS_RECORD_MX = 0x0f,
31 LWS_ADNS_RECORD_AAAA = 0x1c,
32} adns_query_type_t;
33
34typedef enum {
35 LADNS_RET_FAILED_WSI_CLOSED = -4,
36 LADNS_RET_NXDOMAIN = -3,
37 LADNS_RET_TIMEDOUT = -2,
38 LADNS_RET_FAILED = -1,
39 LADNS_RET_FOUND,
40 LADNS_RET_CONTINUING
41} lws_async_dns_retcode_t;
42
43#define LWS_ADNS_SYNTHETIC 0x10000 /* don't send, synthetic response will
44 * be injected for testing */
45
46struct addrinfo;
47
48typedef struct lws * (*lws_async_dns_cb_t)(struct lws *wsi, const char *ads,
49 const struct addrinfo *result, int n, void *opaque);
50
51struct lws_adns_q;
52struct lws_async_dns;
53
54/**
55 * lws_async_dns_query() - perform a dns lookup using async dns
56 *
57 * \param context: the lws_context
58 * \param tsi: thread service index (usually 0)
59 * \param name: DNS name to look up
60 * \param qtype: type of query (A, AAAA etc)
61 * \param cb: query completion callback
62 * \param wsi: wsi if the query is related to one
63 * \param pq: NULL, or pointer to lws_adns_q query (used for testing)
64 *
65 * Starts an asynchronous DNS lookup, on completion the \p cb callback will
66 * be called.
67 *
68 * The reference count on the cached object is incremented for every callback
69 * that was called with the cached addrinfo results.
70 *
71 * The cached object can't be evicted until the reference count reaches zero...
72 * use lws_async_dns_freeaddrinfo() to indicate you're finsihed with the
73 * results for each callback that happened with them.
74 */
75LWS_VISIBLE LWS_EXTERN lws_async_dns_retcode_t
76lws_async_dns_query(struct lws_context *context, int tsi, const char *name,
77 adns_query_type_t qtype, lws_async_dns_cb_t cb,
78 struct lws *wsi, void *opaque, struct lws_adns_q **pq);
79
80/**
81 * lws_async_dns_freeaddrinfo() - decrement refcount on cached addrinfo results
82 *
83 * \param pai: a pointert to a pointer to first addrinfo returned as result in the callback
84 *
85 * Decrements the cache object's reference count. When it reaches zero, the
86 * cached object may be reaped subject to LRU rules.
87 *
88 * The pointer to the first addrinfo give in the argument is set to NULL.
89 */
90LWS_VISIBLE LWS_EXTERN void
91lws_async_dns_freeaddrinfo(const struct addrinfo **ai);
92
93/**
94 * lws_async_dns_server_add() - add a DNS server to the lws async DNS list
95 *
96 * \param cx: the lws_context
97 * \param sa46: the ipv4 or ipv6 DNS server address to add
98 *
99 * Adds the given DNS server to the lws list of async DNS servers to query.
100 * If the address is already listed, its refcount is increased, otherwise a new
101 * entry is made.
102 */
103LWS_VISIBLE LWS_EXTERN int
104lws_async_dns_server_add(struct lws_context *cx, const lws_sockaddr46 *sa46);
105
106/**
107 * lws_async_dns_server_remove() - remove a DNS server from the lws async DNS list
108 *
109 * \param cx: the lws_context
110 * \param sa46: the ipv4 or ipv6 DNS server address to add
111 *
112 * Removes the given DNS server from the lws list of async DNS servers to query.
113 * If the address does not correspond to an existing entry, no action is taken.
114 * If it does, the refcount on it is decremented, and if it reaches zero, the
115 * entry is detached from the list and destroyed.
116 */
117LWS_VISIBLE LWS_EXTERN void
118lws_async_dns_server_remove(struct lws_context *cx, const lws_sockaddr46 *sa46);
119
120/* only needed for testing */
121
122LWS_VISIBLE LWS_EXTERN uint16_t
123lws_adns_get_tid(struct lws_adns_q *q);
124LWS_VISIBLE LWS_EXTERN struct lws_async_dns *
125lws_adns_get_async_dns(struct lws_adns_q *q);
126
127LWS_VISIBLE LWS_EXTERN void
128lws_adns_parse_udp(struct lws_async_dns *dns, const uint8_t *pkt, size_t len);
129
130#endif
131