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
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
/** @file
 * @brief Common routines needed in various network applications.
 */

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

#ifndef __NET_APP_H
#define __NET_APP_H

#if defined(CONFIG_NET_APP_TLS) || defined(CONFIG_NET_APP_DTLS)
#if defined(CONFIG_MBEDTLS)
#if !defined(CONFIG_MBEDTLS_CFG_FILE)
#include "mbedtls/config.h"
#else
#include CONFIG_MBEDTLS_CFG_FILE
#endif /* CONFIG_MBEDTLS_CFG_FILE */

#if defined(MBEDTLS_PLATFORM_C)
#include "mbedtls/platform.h"
#else
#include <stdlib.h>
#define mbedtls_time_t       time_t
#define MBEDTLS_EXIT_SUCCESS EXIT_SUCCESS
#define MBEDTLS_EXIT_FAILURE EXIT_FAILURE
#endif /* MBEDTLS_PLATFORM_C */

#include <mbedtls/ssl_cookie.h>
#include <mbedtls/entropy.h>
#include <mbedtls/ctr_drbg.h>
#include <mbedtls/net_sockets.h>
#include <mbedtls/x509.h>
#include <mbedtls/x509_crt.h>
#include <mbedtls/ssl.h>
#include <mbedtls/error.h>
#include <mbedtls/debug.h>
#endif /* CONFIG_MBEDTLS */
#endif /* CONFIG_NET_APP_TLS || CONFIG_NET_APP_DTLS */

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

#ifdef __cplusplus
extern "C" {
#endif

/**
 * @brief Network application library
 * @defgroup net_app Network Application Library
 * @{
 */

/** Flags that tell what kind of functionality is needed by the application. */
#define NET_APP_NEED_ROUTER 0x00000001
#define NET_APP_NEED_IPV6   0x00000002
#define NET_APP_NEED_IPV4   0x00000004

enum net_app_type {
	NET_APP_UNSPEC = 0,
	NET_APP_SERVER,
	NET_APP_CLIENT,
};

struct net_app_ctx;

/**
 * @typedef net_app_recv_cb_t
 * @brief Network data receive callback.
 *
 * @details The recv callback is called after a network data is
 * received.
 *
 * @param ctx The context to use.
 * @param pkt Network buffer that is received. If the pkt is not NULL,
 * then the callback will own the buffer and it needs to to unref the pkt
 * as soon as it has finished working with it.  On EOF, pkt will be NULL.
 * @param status Value is set to 0 if some data or the connection is
 * at EOF, <0 if there was an error receiving data, in this case the
 * pkt parameter is set to NULL.
 * @param user_data The user data given in init call.
 */
typedef void (*net_app_recv_cb_t)(struct net_app_ctx *ctx,
				  struct net_pkt *pkt,
				  int status,
				  void *user_data);

/**
 * @typedef net_app_connect_cb_t
 * @brief Connection callback.
 *
 * @details The connect callback is called after a connection is being
 * established.
 *
 * @param ctx The context to use.
 * @param status Status of the connection establishment. This is 0
 * if the connection was established successfully, <0 if there was an
 * error.
 * @param user_data The user data given in init call.
 */
typedef void (*net_app_connect_cb_t)(struct net_app_ctx *ctx,
				     int status,
				     void *user_data);

/**
 * @typedef net_app_send_cb_t
 * @brief Network data send callback.
 *
 * @details The send callback is called after a network data is
 * sent.
 *
 * @param ctx The context to use.
 * @param status Value is set to 0 if all data was sent ok, <0 if
 * there was an error sending data. >0 amount of data that was
 * sent when not all data was sent ok.
 * @param user_data_send The user data given in net_app_send() call.
 * @param user_data The user data given in init call.
 */
typedef void (*net_app_send_cb_t)(struct net_app_ctx *ctx,
				  int status,
				  void *user_data_send,
				  void *user_data);

/**
 * @typedef net_app_close_cb_t
 * @brief Close callback.
 *
 * @details The close callback is called after a connection is being
 * shutdown.
 *
 * @param ctx The context to use.
 * @param status Error code for the closing.
 * @param user_data The user data given in init call.
 */
typedef void (*net_app_close_cb_t)(struct net_app_ctx *ctx,
				   int status,
				   void *user_data);

/** Network application callbacks */
struct net_app_cb {
	/** Function that is called when a connection is established.
	 */
	net_app_connect_cb_t connect;

	/** Function that is called when data is received from network.
	 */
	net_app_recv_cb_t recv;

	/** Function that is called when net_pkt is sent.
	 */
	net_app_send_cb_t send;

	/** Function that is called when connection is shutdown.
	 */
	net_app_close_cb_t close;
};

/* This is the same prototype as what net_context_sendto() has
 * so that we can override the sending of the data for TLS traffic.
 */
typedef int (*net_app_send_data_t)(struct net_pkt *pkt,
				   const struct sockaddr *dst_addr,
				   socklen_t addrlen,
				   net_context_send_cb_t cb,
				   s32_t timeout,
				   void *token,
				   void *user_data);

#if defined(CONFIG_NET_APP_TLS) || defined(CONFIG_NET_APP_DTLS)
/* Internal information for managing TLS data */
struct tls_context {
	struct net_pkt *rx_pkt;
	struct net_buf *hdr; /* IP + UDP/TCP header */
	struct net_buf *frag;
	struct k_sem tx_sem;
	struct k_fifo tx_rx_fifo;
	int remaining;
#if defined(CONFIG_NET_APP_DTLS) && defined(CONFIG_NET_APP_SERVER)
	char client_id;
#endif
};

/* This struct is used to pass data to TLS thread when reading or sending
 * data.
 */
struct net_app_fifo_block {
	struct k_mem_block block;
	struct net_pkt *pkt;
	void *token; /* Used when sending data */
	net_context_send_cb_t cb;
	u8_t dir;
};

#define NET_APP_TLS_POOL_DEFINE(name, count)				\
	K_MEM_POOL_DEFINE(name, sizeof(struct net_app_fifo_block),	\
			  sizeof(struct net_app_fifo_block), count, sizeof(int))

#if defined(CONFIG_NET_APP_SERVER)
/**
 * @typedef net_app_cert_cb_t
 * @brief Callback used when the API user needs to setup the certs.
 *
 * @param ctx Net app context.
 * @param cert MBEDTLS certificate
 * @param pkey MBEDTLS private key
 *
 * @return 0 if ok, <0 if there is an error
 */
typedef int (*net_app_cert_cb_t)(struct net_app_ctx *ctx,
				 mbedtls_x509_crt *cert,
				 mbedtls_pk_context *pkey);
#endif /* CONFIG_NET_APP_SERVER */

#if defined(CONFIG_NET_APP_CLIENT)
/**
 * @typedef net_app_ca_cert_cb_t
 * @brief Callback used when the API user needs to setup certs.
 *
 * @param ctx Net app client context.
 * @param ca_cert MBEDTLS certificate. This is of type mbedtls_x509_crt
 * if MBEDTLS_X509_CRT_PARSE_C is defined.
 *
 * @return 0 if ok, <0 if there is an error
 */
typedef int (*net_app_ca_cert_cb_t)(struct net_app_ctx *ctx,
				    void *ca_cert);
#endif /* CONFIG_NET_APP_CLIENT */

/**
 * @typedef net_app_entropy_src_cb_t
 * @brief Callback used when the API user needs to setup the entropy source.
 * @details This is the same as mbedtls_entropy_f_source_ptr callback.
 *
 * @param data Callback-specific data pointer
 * @param output Data to fill
 * @param len Maximum size to provide
 * @param olen The actual amount of bytes put into the buffer (Can be 0)
 */
typedef int (*net_app_entropy_src_cb_t)(void *data, unsigned char *output,
					size_t len, size_t *olen);
#endif /* CONFIG_NET_APP_TLS || CONFIG_NET_APP_DTLS */

#if defined(CONFIG_NET_APP_DTLS)
struct dtls_timing_context {
	u32_t snapshot;
	u32_t int_ms;
	u32_t fin_ms;
};
#endif /* CONFIG_NET_APP_DTLS */

/* Information for the context and local/remote addresses used. */
struct net_app_endpoint {
	/** Network context. */
	struct net_context *ctx;

	/** Local address */
	struct sockaddr local;

	/** Remote address */
	struct sockaddr remote;
};

/** Network application context. */
struct net_app_ctx {
#if defined(CONFIG_NET_IPV6)
	struct net_app_endpoint ipv6;
#endif
#if defined(CONFIG_NET_IPV4)
	struct net_app_endpoint ipv4;
#endif

	/** What is the default endpoint for this context. */
	struct net_app_endpoint *default_ctx;

	/** Internal function that is called when user data is sent to
	 * network. By default this is set to net_context_sendto() but
	 * is overridden for TLS as it requires special handling.
	 */
	net_app_send_data_t send_data;

	/** Connection callbacks */
	struct net_app_cb cb;

	/** Internal function that is called when data is received from
	 * network. This will do what ever needed and then pass data to
	 * application.
	 */
	net_context_recv_cb_t recv_cb;

#if defined(CONFIG_NET_APP_DTLS)
	struct {
		/** Currently active network context. This will contain the
		 * new context that is created after connection is established
		 * when UDP and DTLS is used.
		 */
		struct net_context *ctx;

		/** DTLS final timer. Connection is terminated if this expires.
		 */
		struct k_delayed_work fin_timer;
	} dtls;
#endif

#if defined(CONFIG_NET_APP_SERVER)
	struct {
#if defined(CONFIG_NET_TCP)
		/** Currently active network context. This will contain the
		 * new context that is created after connection is accepted
		 * when TCP is enabled.
		 */
		struct net_context *net_ctx;
#endif
	} server;
#endif /* CONFIG_NET_APP_SERVER */

#if defined(CONFIG_NET_APP_CLIENT)
	struct {
		/** Connect waiter */
		struct k_sem connect_wait;

#if defined(CONFIG_DNS_RESOLVER)
		/** DNS resolver waiter */
		struct k_sem dns_wait;

		/** DNS query id. This is needed if the query needs to be
		 * cancelled.
		 */
		u16_t dns_id;
#endif
	} client;
#endif /* CONFIG_NET_APP_CLIENT */

#if defined(CONFIG_NET_APP_TLS) || defined(CONFIG_NET_APP_DTLS)
	struct {
		/** TLS stack for mbedtls library. */
		k_thread_stack_t stack;

		/** TLS stack size. */
		int stack_size;

		/** TLS thread id */
		k_tid_t tid;

		/** TLS thread */
		struct k_thread thread;

		/** Memory pool for RX data */
		struct k_mem_pool *pool;

		/** Where the encrypted request is stored, this is to be
		 * provided by the user.
		 */
		u8_t *request_buf;

		/** Hostname to be used in the certificate verification */
		const char *cert_host;

		/** Request buffer maximum length */
		size_t request_buf_len;

		/** mbedtls related configuration. */
		struct {
#if defined(CONFIG_NET_APP_SERVER)
			net_app_cert_cb_t cert_cb;
			mbedtls_x509_crt srvcert;
			mbedtls_pk_context pkey;
#endif
#if defined(CONFIG_NET_APP_CLIENT)
			net_app_ca_cert_cb_t ca_cert_cb;
			mbedtls_x509_crt ca_cert;
#endif
			struct tls_context ssl_ctx;
			net_app_entropy_src_cb_t entropy_src_cb;
			mbedtls_entropy_context entropy;
			mbedtls_ctr_drbg_context ctr_drbg;
			mbedtls_ssl_context ssl;
			mbedtls_ssl_config conf;
#if defined(CONFIG_NET_APP_DTLS)
			mbedtls_ssl_cookie_ctx cookie_ctx;
			struct dtls_timing_context timing_ctx;
#endif
			u8_t *personalization_data;
			size_t personalization_data_len;
		} mbedtls;

		/** Have we called connect cb yet? */
		bool connect_cb_called;
	} tls;
#endif /* CONFIG_NET_APP_TLS || CONFIG_NET_APP_DTLS */

#if defined(CONFIG_NET_CONTEXT_NET_PKT_POOL)
	/** Network packet (net_pkt) memory pool for network contexts attached
	 * to this network app context.
	 */
	net_pkt_get_slab_func_t tx_slab;

	/** Network data net_buf pool for network contexts attached to this
	 * network app context.
	 */
	net_pkt_get_pool_func_t data_pool;
#endif

	/** User data pointer */
	void *user_data;

#if defined(CONFIG_NET_DEBUG_APP)
	/** Used when debugging with net-shell */
	sys_snode_t node;
#endif

	/** Type of the connection (stream or datagram) */
	enum net_sock_type sock_type;

	/** IP protocol type (UDP or TCP) */
	enum net_ip_protocol proto;

	/** Application type (client or server) of this instance */
	enum net_app_type app_type;

	/** Is this context setup or not */
	u8_t is_init : 1;

	/** Is this instance supporting TLS or not.
	 */
	u8_t is_tls : 1;

	/** Running status of the server. If true, then the server is enabled.
	 * If false then it is disabled and will not serve clients.
	 * The server is disabled by default after initialization and needs to
	 * be manually enabled in order to serve any requests.
	 */
	u8_t is_enabled : 1;

	/** Unused bits */
	u8_t _padding : 5;
};

/**
 * @brief Initialize this network application.
 *
 * @param app_info String describing this application.
 * @param flags Flags related to this application startup.
 * @param timeout How long to wait the network setup before continuing
 * the startup.
 *
 * @return 0 if ok, <0 if error.
 */
int net_app_init(const char *app_info, u32_t flags, s32_t timeout);

#if defined(CONFIG_NET_CONTEXT_NET_PKT_POOL)
/**
 * @brief Configure the net_pkt pool for this context.
 *
 * @details Use of this function is optional and if the pools are not set,
 * then the default TX and DATA pools are used.
 *
 * @param tx_slab Function which is used when allocating TX network packet.
 * This can be NULL in which case default TX memory pool is used.
 * @param data_pool Function which is used when allocating data network buffer.
 * This can be NULL in which case default DATA net_buf pool is used.
 */
int net_app_set_net_pkt_pool(struct net_app_ctx *ctx,
			     net_pkt_get_slab_func_t tx_slab,
			     net_pkt_get_pool_func_t data_pool);
#else
#define net_app_set_net_pkt_pool(...)
#endif /* CONFIG_NET_CONTEXT_NET_PKT_POOL */

#if defined(CONFIG_NET_APP_SERVER)
/**
 * @brief Create a network server application.
 *
 * @details Note that caller must create the context and initialize it to 0
 * before calling this function. The context must be valid for the whole
 * duration of the application life cycle. This usually means that it
 * cannot be allocated from stack.
 *
 * @param ctx Network application context.
 * @param sock_type Connection type (stream or datagram).
 * @param proto IP protocol (UDP or TCP)
 * @param server_addr Local address of the server. If set to NULL, then the
 * API will figure out a proper address where to bind the context.
 * @param port UDP or TCP port number where the service is located. This is
 * only used if server_addr parameter is NULL.
 * @param timeout Timeout for this function call. This timeout tells how
 * long to wait while accepting the data from network.
 * @param user_data User specific data.
 *
 * @return 0 if ok, <0 if error.
 */
int net_app_init_server(struct net_app_ctx *ctx,
			enum net_sock_type sock_type,
			enum net_ip_protocol proto,
			struct sockaddr *server_addr,
			u16_t port,
			void *user_data);

/**
 * @brief Create a TCP server application.
 *
 * @details Note that caller must create the context and initialize it to 0
 * before calling this function. The context must be valid for the whole
 * duration of the application life cycle. This usually means that it
 * cannot be allocated from stack.
 *
 * @param ctx Network application context.
 * @param server_addr Local address of the server. If set to NULL, then the
 * API will figure out a proper address where to bind the context.
 * @param port UDP or TCP port number where the service is located. This is
 * only used if server_addr parameter is NULL.
 * @param timeout Timeout for this function call. This timeout tells how
 * long to wait while accepting the data from network.
 * @param user_data User specific data.
 *
 * @return 0 if ok, <0 if error.
 */
static inline int net_app_init_tcp_server(struct net_app_ctx *ctx,
					  struct sockaddr *server_addr,
					  u16_t port,
					  void *user_data)
{
	return net_app_init_server(ctx,
				   SOCK_STREAM,
				   IPPROTO_TCP,
				   server_addr,
				   port,
				   user_data);
}

/**
 * @brief Create a UDP server application.
 *
 * @details Note that caller must create the context and initialize it to 0
 * before calling this function. The context must be valid for the whole
 * duration of the application life cycle. This usually means that it
 * cannot be allocated from stack.
 *
 * @param ctx Network application context.
 * @param server_addr Local address of the server. If set to NULL, then the
 * API will figure out a proper address where to bind the context.
 * @param port UDP or TCP port number where the service is located. This is
 * only used if server_addr parameter is NULL.
 * @param timeout Timeout for this function call. This timeout tells how
 * long to wait while accepting the data from network.
 * @param user_data User specific data.
 *
 * @return 0 if ok, <0 if error.
 */
static inline int net_app_init_udp_server(struct net_app_ctx *ctx,
					  struct sockaddr *server_addr,
					  u16_t port,
					  void *user_data)
{
	return net_app_init_server(ctx,
				   SOCK_DGRAM,
				   IPPROTO_UDP,
				   server_addr,
				   port,
				   user_data);
}

/**
 * @brief Wait for an incoming connection.
 *
 * @details Note that caller must have called net_app_init_server() before
 * calling this function. This functionality is separated from init function
 * so that user can setup the callbacks after calling init. Only after calling
 * this function the server starts to listen connection attempts. This function
 * will not block but will initialize the local end point address so that
 * receive callback will be called for incoming connection.
 *
 * @param ctx Network application context.
 *
 * @return 0 if ok, <0 if error.
 */
int net_app_listen(struct net_app_ctx *ctx);

/**
 * @brief Enable server to serve connections.
 *
 * @details By default the server status is disabled.
 *
 * @param ctx Network application context.
 *
 * @return 0 if ok, <0 if error.
 */
bool net_app_server_enable(struct net_app_ctx *ctx);

/**
 * @brief Disable server so that it will not serve any clients.
 *
 * @param ctx Network application context.
 *
 * @return 0 if ok, <0 if error.
 */
bool net_app_server_disable(struct net_app_ctx *ctx);

#endif /* CONFIG_NET_APP_SERVER */

#if defined(CONFIG_NET_APP_CLIENT)
/**
 * @brief Create a network client application.
 *
 * @details Note that caller must create the context and initialize it to 0
 * before calling this function. The context must be valid for the whole
 * duration of the application life cycle. This usually means that it
 * cannot be allocated from stack.
 *
 * @param ctx Network application context.
 * @param sock_type Connection type (stream or datagram).
 * @param proto IP protocol (UDP or TCP)
 * @param client_addr Local address of the client. If set to NULL, then the
 * API will figure out a proper address where to bind the context.
 * @param peer_addr Peer (target) address. If this is NULL, then the
 * peer_add_str string and peer_port are used when connecting to peer.
 * @param peer_addr_str Peer (target) address as a string. If this is NULL,
 * then the peer_addr sockaddr is used to set the peer address. If DNS is
 * configured in the system, then the hostname is automatically resolved if
 * given here. Note that the port number is optional in the string. If the
 * port number is not given in the string, then peer_port variable is used
 * instead.
 * Following syntax is supported for the address:
 *      192.0.2.1
 *      192.0.2.1:5353
 *      2001:db8::1
 *      [2001:db8::1]:5353
 *      peer.example.com
 *      peer.example.com:1234
 * @param peer_port Port number where to connect to. Ignored if port number is
 * found in the peer_addr_str.
 * @param timeout Timeout for this function call. This is used if the API
 * needs to do some time consuming operation, like resolving DNS address.
 * @param user_data User specific data.
 *
 * @return 0 if ok, <0 if error.
 */
int net_app_init_client(struct net_app_ctx *ctx,
			enum net_sock_type sock_type,
			enum net_ip_protocol proto,
			struct sockaddr *client_addr,
			struct sockaddr *peer_addr,
			const char *peer_addr_str,
			u16_t peer_port,
			s32_t timeout,
			void *user_data);

/**
 * @brief Create a TCP client application.
 *
 * @details Note that caller must create the context and initialize it to 0
 * before calling this function. The context must be valid for the whole
 * duration of the application life cycle. This usually means that it
 * cannot be allocated from stack.
 *
 * @param ctx Network application context.
 * @param client_addr Local address of the client. If set to NULL, then the
 * API will figure out a proper address where to bind the context.
 * @param peer_addr Peer (target) address. If this is NULL, then the
 * peer_add_str string and peer_port are used when connecting to peer.
 * @param peer_addr_str Peer (target) address as a string. If this is NULL,
 * then the peer_addr sockaddr is used to set the peer address. If DNS is
 * configured in the system, then the hostname is automatically resolved if
 * given here. Note that the port number is optional in the string. If the
 * port number is not given in the string, then peer_port variable is used
 * instead.
 * Following syntax is supported for the address:
 *      192.0.2.1
 *      192.0.2.1:5353
 *      2001:db8::1
 *      [2001:db8::1]:5353
 *      peer.example.com
 *      peer.example.com:1234
 * @param peer_port Port number where to connect to. Ignored if port number is
 * found in the peer_addr_str.
 * @param timeout Timeout for this function call. This is used if the API
 * needs to do some time consuming operation, like resolving DNS address.
 * @param user_data User specific data.
 *
 * @return 0 if ok, <0 if error.
 */
static inline int net_app_init_tcp_client(struct net_app_ctx *ctx,
					  struct sockaddr *client_addr,
					  struct sockaddr *peer_addr,
					  const char *peer_addr_str,
					  u16_t peer_port,
					  s32_t timeout,
					  void *user_data)
{
	return net_app_init_client(ctx,
				   SOCK_STREAM,
				   IPPROTO_TCP,
				   client_addr,
				   peer_addr,
				   peer_addr_str,
				   peer_port,
				   timeout,
				   user_data);
}

/**
 * @brief Create a UDP client application.
 *
 * @details Note that caller must create the context and initialize it to 0
 * before calling this function. The context must be valid for the whole
 * duration of the application life cycle. This usually means that it
 * cannot be allocated from stack.
 *
 * @param ctx Network application context.
 * @param client_addr Local address of the client. If set to NULL, then the
 * API will figure out a proper address where to bind the context.
 * @param peer_addr Peer (target) address. If this is NULL, then the
 * peer_add_str string and peer_port are used when connecting to peer.
 * @param peer_addr_str Peer (target) address as a string. If this is NULL,
 * then the peer_addr sockaddr is used to set the peer address. If DNS is
 * configured in the system, then the hostname is automatically resolved if
 * given here. Note that the port number is optional in the string. If the
 * port number is not given in the string, then peer_port variable is used
 * instead.
 * Following syntax is supported for the address:
 *      192.0.2.1
 *      192.0.2.1:5353
 *      2001:db8::1
 *      [2001:db8::1]:5353
 *      peer.example.com
 *      peer.example.com:1234
 * @param peer_port Port number where to connect to. Ignored if port number is
 * found in the peer_addr_str.
 * @param timeout Timeout for this function call. This is used if the API
 * needs to do some time consuming operation, like resolving DNS address.
 * @param user_data User specific data.
 *
 * @return 0 if ok, <0 if error.
 */
static inline int net_app_init_udp_client(struct net_app_ctx *ctx,
					  struct sockaddr *client_addr,
					  struct sockaddr *peer_addr,
					  const char *peer_addr_str,
					  u16_t peer_port,
					  s32_t timeout,
					  void *user_data)
{
	return net_app_init_client(ctx,
				   SOCK_DGRAM,
				   IPPROTO_UDP,
				   client_addr,
				   peer_addr,
				   peer_addr_str,
				   peer_port,
				   timeout,
				   user_data);
}

/**
 * @brief Establish a network connection to peer.
 *
 * @param ctx Network application context.
 * @param timeout How long to wait the network connection before giving up.
 *
 * @return 0 if ok, <0 if error.
 */
int net_app_connect(struct net_app_ctx *ctx, s32_t timeout);
#endif /* CONFIG_NET_APP_CLIENT */

/**
 * @brief Set various network application callbacks.
 *
 * @param ctx Network app context.
 * @param connect_cb Connect callback.
 * @param recv_cb Data receive callback.
 * @param send_cb Data sent callback.
 * @param close_cb Close callback.
 *
 * @return 0 if ok, <0 if error.
 */
int net_app_set_cb(struct net_app_ctx *ctx,
		   net_app_connect_cb_t connect_cb,
		   net_app_recv_cb_t recv_cb,
		   net_app_send_cb_t send_cb,
		   net_app_close_cb_t close_cb);

/**
 * @brief Send data that is found in net_pkt to peer.
 *
 * @details If the function return < 0, then it is caller responsibility
 * to unref the pkt. If the packet was sent successfully, then the lower
 * IP stack will release the network pkt.
 *
 * @param ctx Network application context.
 * @param pkt Network packet to send.
 * @param dst Destination address where to send packet. This is
 * ignored for TCP data.
 * @param dst_len Destination address structure size
 * @param timeout How long to wait the send before giving up.
 * @param user_data_send User data specific to this send call.
 *
 * @return 0 if ok, <0 if error.
 */
int net_app_send_pkt(struct net_app_ctx *ctx,
		     struct net_pkt *pkt,
		     const struct sockaddr *dst,
		     socklen_t dst_len,
		     s32_t timeout,
		     void *user_data_send);

/**
 * @brief Send data that is found in user specified buffer to peer.
 *
 * @param ctx Network application context.
 * @param buf Buffer to send.
 * @param buf_len Amount of data to send.
 * @param dst Destination address where to send packet. This is
 * ignored for TCP data.
 * @param dst_len Destination address structure size
 * @param timeout How long to wait the send before giving up.
 * @param user_data_send User data specific to this send call.
 *
 * @return 0 if ok, <0 if error.
 */
int net_app_send_buf(struct net_app_ctx *ctx,
		     u8_t *buf,
		     size_t buf_len,
		     const struct sockaddr *dst,
		     socklen_t dst_len,
		     s32_t timeout,
		     void *user_data_send);

/**
 * @brief Create network packet.
 *
 * @param ctx Network application context.
 * @param family What kind of network packet to get (AF_INET or AF_INET6)
 * @param timeout How long to wait the send before giving up.
 *
 * @return valid net_pkt if ok, NULL if error.
 */
struct net_pkt *net_app_get_net_pkt(struct net_app_ctx *ctx,
				    sa_family_t family,
				    s32_t timeout);

/**
 * @brief Create network buffer that will hold network data.
 *
 * @details The returned net_buf is automatically appended to the
 * end of network packet fragment chain.
 *
 * @param ctx Network application context.
 * @param pkt Network packet to where the data buf is appended.
 * @param timeout How long to wait the send before giving up.
 *
 * @return valid net_pkt if ok, NULL if error.
 */
struct net_buf *net_app_get_net_buf(struct net_app_ctx *ctx,
				    struct net_pkt *pkt,
				    s32_t timeout);

/**
 * @brief Close a network connection to peer.
 *
 * @param ctx Network application context.
 *
 * @return 0 if ok, <0 if error.
 */
int net_app_close(struct net_app_ctx *ctx);

/**
 * @brief Release this network application context.
 *
 * @details No network data will be received via this context after this
 * call.
 *
 * @param ctx Network application context.
 *
 * @return 0 if ok, <0 if error.
 */
int net_app_release(struct net_app_ctx *ctx);

#if defined(CONFIG_NET_APP_TLS) || defined(CONFIG_NET_APP_DTLS)
#if defined(CONFIG_NET_APP_CLIENT)
/**
 * @brief Initialize TLS support for this net_app client context.
 *
 * @param ctx net_app context.
 * @param request_buf Caller-supplied buffer where the TLS request will be
 * stored
 * @param request_buf_len Length of the caller-supplied buffer.
 * @param personalization_data Personalization data (Device specific
 * identifiers) for random number generator. (Can be NULL).
 * @param personalization_data_len Length of the personalization data.
 * @param cert_cb User-supplied callback that setups the certificates.
 * @param cert_host Hostname that is used to verify the server certificate.
 * This value is used when net_api API calls mbedtls_ssl_set_hostname()
 * which sets the hostname to check against the received server certificate.
 * See https://tls.mbed.org/kb/how-to/use-sni for more details.
 * This can be left NULL in which case mbedtls will silently skip certificate
 * verification entirely. This option is only used if MBEDTLS_X509_CRT_PARSE_C
 * is enabled in mbedtls config file.
 * @param entropy_src_cb User-supplied callback that setup the entropy. This
 * can be set to NULL, in which case default entropy source is used.
 * @param pool Memory pool for RX data reads.
 * @param stack TLS thread stack.
 * @param stack_len TLS thread stack size.
 *
 * @return Return 0 if ok, <0 if error.
 */
int net_app_client_tls(struct net_app_ctx *ctx,
		       u8_t *request_buf,
		       size_t request_buf_len,
		       u8_t *personalization_data,
		       size_t personalization_data_len,
		       net_app_ca_cert_cb_t cert_cb,
		       const char *cert_host,
		       net_app_entropy_src_cb_t entropy_src_cb,
		       struct k_mem_pool *pool,
		       k_thread_stack_t stack,
		       size_t stack_size);
#endif /* CONFIG_NET_APP_CLIENT */

#if defined(CONFIG_NET_APP_SERVER)
/**
 * @brief Initialize TLS support for this net_app server context.
 *
 * @param ctx net_app context.
 * @param request_buf Caller-supplied buffer where the TLS request will be
 * stored
 * @param request_buf_len Length of the caller-supplied buffer.
 * @param server_banner Print information about started service. This is only
 * printed if net_app debugging is activated. The parameter can be set to NULL
 * if no extra prints are needed.
 * @param personalization_data Personalization data (Device specific
 * identifiers) for random number generator. (Can be NULL).
 * @param personalization_data_len Length of the personalization data.
 * @param cert_cb User-supplied callback that setups the certificates.
 * @param entropy_src_cb User-supplied callback that setup the entropy. This
 * can be set to NULL, in which case default entropy source is used.
 * @param pool Memory pool for RX data reads.
 * @param stack TLS thread stack.
 * @param stack_len TLS thread stack size.
 *
 * @return Return 0 if ok, <0 if error.
 */
int net_app_server_tls(struct net_app_ctx *ctx,
		       u8_t *request_buf,
		       size_t request_buf_len,
		       const char *server_banner,
		       u8_t *personalization_data,
		       size_t personalization_data_len,
		       net_app_cert_cb_t cert_cb,
		       net_app_entropy_src_cb_t entropy_src_cb,
		       struct k_mem_pool *pool,
		       k_thread_stack_t stack,
		       size_t stack_len);

#endif /* CONFIG_NET_APP_SERVER */

#endif /* CONFIG_NET_APP_TLS || CONFIG_NET_APP_DTLS */

/**
 * @}
 */

#if defined(CONFIG_NET_DEBUG_APP)
typedef void (*net_app_ctx_cb_t)(struct net_app_ctx *ctx, void *user_data);
void net_app_server_foreach(net_app_ctx_cb_t cb, void *user_data);
void net_app_client_foreach(net_app_ctx_cb_t cb, void *user_data);
#endif /* CONFIG_NET_DEBUG_APP */

#ifdef __cplusplus
}
#endif

#endif /* __NET_APP_H */