Boot Linux faster!

Check our new training course

Boot Linux faster!

Check our new training course
and Creative Commons CC-BY-SA
lecture and lab materials

Bootlin logo

Elixir Cross Referencer

  1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
/** @file
 * @brief DNS resolving library
 *
 * An API for applications to resolve a DNS name.
 */

/*
 * Copyright (c) 2017 Intel Corporation
 *
 * SPDX-License-Identifier: Apache-2.0
 */

#ifndef ZEPHYR_INCLUDE_NET_DNS_RESOLVE_H_
#define ZEPHYR_INCLUDE_NET_DNS_RESOLVE_H_

#include <net/net_ip.h>
#include <net/net_context.h>

#ifdef __cplusplus
extern "C" {
#endif

/**
 * @brief DNS resolving library
 * @defgroup dns_resolve DNS Resolve Library
 * @ingroup networking
 * @{
 */

/**
 * DNS query type enum
 */
enum dns_query_type {
	/** IPv4 query */
	DNS_QUERY_TYPE_A = 1,
	/** IPv6 query */
	DNS_QUERY_TYPE_AAAA = 28
};

/** Max size of the resolved name. */
#ifndef DNS_MAX_NAME_SIZE
#define DNS_MAX_NAME_SIZE 20
#endif

/** @cond INTERNAL_HIDDEN */

/* Make sure that we can compile things even if CONFIG_DNS_RESOLVER
 * is not enabled.
 */
#if !defined(CONFIG_DNS_RESOLVER_MAX_SERVERS)
#define CONFIG_DNS_RESOLVER_MAX_SERVERS 1
#endif
#if !defined(CONFIG_DNS_NUM_CONCUR_QUERIES)
#define CONFIG_DNS_NUM_CONCUR_QUERIES 1
#endif

/* If mDNS is enabled, then add some extra well known multicast servers to the
 * server list.
 */
#if defined(CONFIG_MDNS_RESOLVER)
#if defined(CONFIG_NET_IPV6) && defined(CONFIG_NET_IPV4)
#define MDNS_SERVER_COUNT 2
#else
#define MDNS_SERVER_COUNT 1
#endif /* CONFIG_NET_IPV6 && CONFIG_NET_IPV4 */
#else
#define MDNS_SERVER_COUNT 0
#endif /* CONFIG_MDNS_RESOLVER */

/* If LLMNR is enabled, then add some extra well known multicast servers to the
 * server list.
 */
#if defined(CONFIG_LLMNR_RESOLVER)
#if defined(CONFIG_NET_IPV6) && defined(CONFIG_NET_IPV4)
#define LLMNR_SERVER_COUNT 2
#else
#define LLMNR_SERVER_COUNT 1
#endif /* CONFIG_NET_IPV6 && CONFIG_NET_IPV4 */
#else
#define LLMNR_SERVER_COUNT 0
#endif /* CONFIG_MDNS_RESOLVER */

#define DNS_MAX_MCAST_SERVERS (MDNS_SERVER_COUNT + LLMNR_SERVER_COUNT)

/** @endcond */

/**
 * Address info struct is passed to callback that gets all the results.
 */
struct dns_addrinfo {
	struct sockaddr ai_addr;
	socklen_t       ai_addrlen;
	u8_t            ai_family;
	char            ai_canonname[DNS_MAX_NAME_SIZE + 1];
};

/**
 * Status values for the callback.
 */
enum dns_resolve_status {
	/** Invalid value for `ai_flags' field */
	DNS_EAI_BADFLAGS    = -1,
	/** NAME or SERVICE is unknown */
	DNS_EAI_NONAME      = -2,
	/** Temporary failure in name resolution */
	DNS_EAI_AGAIN       = -3,
	/** Non-recoverable failure in name res */
	DNS_EAI_FAIL        = -4,
	/** No address associated with NAME */
	DNS_EAI_NODATA      = -5,
	/** `ai_family' not supported */
	DNS_EAI_FAMILY      = -6,
	/** `ai_socktype' not supported */
	DNS_EAI_SOCKTYPE    = -7,
	/** SRV not supported for `ai_socktype' */
	DNS_EAI_SERVICE     = -8,
	/** Address family for NAME not supported */
	DNS_EAI_ADDRFAMILY  = -9,
	/** Memory allocation failure */
	DNS_EAI_MEMORY      = -10,
	/** System error returned in `errno' */
	DNS_EAI_SYSTEM      = -11,
	/** Argument buffer overflow */
	DNS_EAI_OVERFLOW    = -12,
	/** Processing request in progress */
	DNS_EAI_INPROGRESS  = -100,
	/** Request canceled */
	DNS_EAI_CANCELED    = -101,
	/** Request not canceled */
	DNS_EAI_NOTCANCELED = -102,
	/** All requests done */
	DNS_EAI_ALLDONE     = -103,
	/** IDN encoding failed */
	DNS_EAI_IDN_ENCODE  = -105,
};

/**
 * @typedef dns_resolve_cb_t
 * @brief DNS resolve callback
 *
 * @details The DNS resolve callback is called after a successful
 * DNS resolving. The resolver can call this callback multiple times, one
 * for each resolved address.
 *
 * @param status The status of the query:
 *  DNS_EAI_INPROGRESS returned for each resolved address
 *  DNS_EAI_ALLDONE    mark end of the resolving, info is set to NULL in
 *                     this case
 *  DNS_EAI_CANCELED   if the query was canceled manually or timeout happened
 *  DNS_EAI_FAIL       if the name cannot be resolved by the server
 *  DNS_EAI_NODATA     if there is no such name
 *  other values means that an error happened.
 * @param info Query results are stored here.
 * @param user_data The user data given in dns_resolve_name() call.
 */
typedef void (*dns_resolve_cb_t)(enum dns_resolve_status status,
				 struct dns_addrinfo *info,
				 void *user_data);

/**
 * DNS resolve context structure.
 */
struct dns_resolve_context {
	struct {
		/** DNS server information */
		struct sockaddr dns_server;

		/** Connection to the DNS server */
		struct net_context *net_ctx;

		/** Is this server mDNS one */
		u8_t is_mdns : 1;

		/** Is this server LLMNR one */
		u8_t is_llmnr : 1;
	} servers[CONFIG_DNS_RESOLVER_MAX_SERVERS + DNS_MAX_MCAST_SERVERS];

	/** This timeout is also used when a buffer is required from the
	 * buffer pools.
	 */
	k_timeout_t buf_timeout;

	/** Result callbacks. We have multiple callbacks here so that it is
	 * possible to do multiple queries at the same time.
	 */
	struct dns_pending_query {
		/** Timeout timer */
		struct k_delayed_work timer;

		/** Back pointer to ctx, needed in timeout handler */
		struct dns_resolve_context *ctx;

		/** Result callback */
		dns_resolve_cb_t cb;

		/** User data */
		void *user_data;

		/** TX timeout */
		k_timeout_t timeout;

		/** String containing the thing to resolve like www.example.com
		 */
		const char *query;

		/** Query type */
		enum dns_query_type query_type;

		/** DNS id of this query */
		u16_t id;

		/** Hash of the DNS name + query type we are querying.
		 * This hash is calculated so we can match the response that
		 * we are receiving. This is needed mainly for mDNS which is
		 * setting the DNS id to 0, which means that the id alone
		 * cannot be used to find correct pending query.
		 */
		u16_t query_hash;
	} queries[CONFIG_DNS_NUM_CONCUR_QUERIES];

	/** Is this context in use */
	bool is_used;
};

/**
 * @brief Init DNS resolving context.
 *
 * @details This function sets the DNS server address and initializes the
 * DNS context that is used by the actual resolver. DNS server addresses
 * can be specified either in textual form, or as struct sockaddr (or both).
 * Note that the recommended way to resolve DNS names is to use
 * the dns_get_addr_info() API. In that case user does not need to
 * call dns_resolve_init() as the DNS servers are already setup by the system.
 *
 * @param ctx DNS context. If the context variable is allocated from
 * the stack, then the variable needs to be valid for the whole duration of
 * the resolving. Caller does not need to fill the variable beforehand or
 * edit the context afterwards.
 * @param dns_servers_str DNS server addresses using textual strings. The
 * array is NULL terminated. The port number can be given in the string.
 * Syntax for the server addresses with or without port numbers:
 *    IPv4        : 10.0.9.1
 *    IPv4 + port : 10.0.9.1:5353
 *    IPv6        : 2001:db8::22:42
 *    IPv6 + port : [2001:db8::22:42]:5353
 * @param dns_servers_sa DNS server addresses as struct sockaddr. The array
 * is NULL terminated. Port numbers are optional in struct sockaddr, the
 * default will be used if set to 0.
 *
 * @return 0 if ok, <0 if error.
 */
int dns_resolve_init(struct dns_resolve_context *ctx,
		     const char *dns_servers_str[],
		     const struct sockaddr *dns_servers_sa[]);

/**
 * @brief Close DNS resolving context.
 *
 * @details This releases DNS resolving context and marks the context unusable.
 * Caller must call the dns_resolve_init() again to make context usable.
 *
 * @param ctx DNS context
 *
 * @return 0 if ok, <0 if error.
 */
int dns_resolve_close(struct dns_resolve_context *ctx);

/**
 * @brief Cancel a pending DNS query.
 *
 * @details This releases DNS resources used by a pending query.
 *
 * @param ctx DNS context
 * @param dns_id DNS id of the pending query
 *
 * @return 0 if ok, <0 if error.
 */
int dns_resolve_cancel(struct dns_resolve_context *ctx,
		       u16_t dns_id);

/**
 * @brief Cancel a pending DNS query using id, name and type.
 *
 * @details This releases DNS resources used by a pending query.
 *
 * @param ctx DNS context
 * @param dns_id DNS id of the pending query
 * @param query_name Name of the resource we are trying to query (hostname)
 * @param query_type Type of the query (A or AAAA)
 *
 * @return 0 if ok, <0 if error.
 */
int dns_resolve_cancel_with_name(struct dns_resolve_context *ctx,
				 u16_t dns_id,
				 const char *query_name,
				 enum dns_query_type query_type);

/**
 * @brief Resolve DNS name.
 *
 * @details This function can be used to resolve e.g., IPv4 or IPv6 address.
 * Note that this is asynchronous call, the function will return immediately
 * and system will call the callback after resolving has finished or timeout
 * has occurred.
 * We might send the query to multiple servers (if there are more than one
 * server configured), but we only use the result of the first received
 * response.
 *
 * @param ctx DNS context
 * @param query What the caller wants to resolve.
 * @param type What kind of data the caller wants to get.
 * @param dns_id DNS id is returned to the caller. This is needed if one
 * wishes to cancel the query. This can be set to NULL if there is no need
 * to cancel the query.
 * @param cb Callback to call after the resolving has finished or timeout
 * has happened.
 * @param user_data The user data.
 * @param timeout The timeout value for the query. Possible values:
 * SYS_FOREVER_MS: the query is tried forever, user needs to cancel it
 *            manually if it takes too long time to finish
 * >0: start the query and let the system timeout it after specified ms
 *
 * @return 0 if resolving was started ok, < 0 otherwise
 */
int dns_resolve_name(struct dns_resolve_context *ctx,
		     const char *query,
		     enum dns_query_type type,
		     u16_t *dns_id,
		     dns_resolve_cb_t cb,
		     void *user_data,
		     s32_t timeout);

/**
 * @brief Get default DNS context.
 *
 * @details The system level DNS context uses DNS servers that are
 * defined in project config file. If no DNS servers are defined by the
 * user, then resolving DNS names using default DNS context will do nothing.
 * The configuration options are described in subsys/net/lib/dns/Kconfig file.
 *
 * @return Default DNS context.
 */
struct dns_resolve_context *dns_resolve_get_default(void);

/**
 * @brief Get IP address info from DNS.
 *
 * @details This function can be used to resolve e.g., IPv4 or IPv6 address.
 * Note that this is asynchronous call, the function will return immediately
 * and system will call the callback after resolving has finished or timeout
 * has occurred.
 * We might send the query to multiple servers (if there are more than one
 * server configured), but we only use the result of the first received
 * response.
 * This variant uses system wide DNS servers.
 *
 * @param query What the caller wants to resolve.
 * @param type What kind of data the caller wants to get.
 * @param dns_id DNS id is returned to the caller. This is needed if one
 * wishes to cancel the query. This can be set to NULL if there is no need
 * to cancel the query.
 * @param cb Callback to call after the resolving has finished or timeout
 * has happened.
 * @param user_data The user data.
 * @param timeout The timeout value for the connection. Possible values:
 * SYS_FOREVER_MS: the query is tried forever, user needs to cancel it
 *            manually if it takes too long time to finish
 * >0: start the query and let the system timeout it after specified ms
 *
 * @return 0 if resolving was started ok, < 0 otherwise
 */
static inline int dns_get_addr_info(const char *query,
				    enum dns_query_type type,
				    u16_t *dns_id,
				    dns_resolve_cb_t cb,
				    void *user_data,
				    s32_t timeout)
{
	return dns_resolve_name(dns_resolve_get_default(),
				query,
				type,
				dns_id,
				cb,
				user_data,
				timeout);
}

/**
 * @brief Cancel a pending DNS query.
 *
 * @details This releases DNS resources used by a pending query.
 *
 * @param dns_id DNS id of the pending query
 *
 * @return 0 if ok, <0 if error.
 */
static inline int dns_cancel_addr_info(u16_t dns_id)
{
	return dns_resolve_cancel(dns_resolve_get_default(), dns_id);
}

/**
 * @}
 */

/** @cond INTERNAL_HIDDEN */

/**
 * @brief Initialize DNS subsystem.
 */
#if defined(CONFIG_DNS_RESOLVER)
void dns_init_resolver(void);

#else
#define dns_init_resolver(...)
#endif /* CONFIG_DNS_RESOLVER */

/** @endcond */

#ifdef __cplusplus
}
#endif

#endif /* ZEPHYR_INCLUDE_NET_DNS_RESOLVE_H_ */