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
/** @file
 @brief TCP data handler

 This is not to be included by the application.
 */

/*
 * Copyright (c) 2016 Intel Corporation
 *
 * SPDX-License-Identifier: Apache-2.0
 */

#ifndef __TCP_H
#define __TCP_H

#include <zephyr/types.h>

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

#include "connection.h"

#ifdef __cplusplus
extern "C" {
#endif

/** Is this TCP context/socket used or not */
#define NET_TCP_IN_USE BIT(0)

/** Is the final segment sent */
#define NET_TCP_FINAL_SENT BIT(1)

/** Is the final segment received */
#define NET_TCP_FINAL_RECV BIT(2)

/** Is the socket shutdown for read/write */
#define NET_TCP_IS_SHUTDOWN BIT(3)

/** A retransmitted packet has been sent and not yet ack'd */
#define NET_TCP_RETRYING BIT(4)

/** MSS option has been set already */
#define NET_TCP_RECV_MSS_SET BIT(5)

/*
 * TCP connection states
 */
enum net_tcp_state {
	NET_TCP_CLOSED = 0,
	NET_TCP_LISTEN,
	NET_TCP_SYN_SENT,
	NET_TCP_SYN_RCVD,
	NET_TCP_ESTABLISHED,
	NET_TCP_CLOSE_WAIT,
	NET_TCP_LAST_ACK,
	NET_TCP_FIN_WAIT_1,
	NET_TCP_FIN_WAIT_2,
	NET_TCP_TIME_WAIT,
	NET_TCP_CLOSING,
};

/* TCP packet types */
#define NET_TCP_FIN 0x01
#define NET_TCP_SYN 0x02
#define NET_TCP_RST 0x04
#define NET_TCP_PSH 0x08
#define NET_TCP_ACK 0x10
#define NET_TCP_URG 0x20
#define NET_TCP_CTL 0x3f

#define NET_TCP_FLAGS(hdr) (hdr->flags & NET_TCP_CTL)

/* TCP max window size */
#define NET_TCP_MAX_WIN   (4 * 1024)

/* Maximal value of the sequence number */
#define NET_TCP_MAX_SEQ   0xffffffff

#define NET_TCP_MAX_OPT_SIZE  8

#define NET_TCP_MSS_HEADER    0x02040000 /* MSS option */
#define NET_TCP_WINDOW_HEADER 0x30300    /* Window scale option */

#define NET_TCP_MSS_SIZE      4          /* MSS option size */
#define NET_TCP_WINDOW_SIZE   3          /* Window scale option size */

/* Max received bytes to buffer internally */
#define NET_TCP_BUF_MAX_LEN 1280

/* Max segment lifetime, in seconds */
#define NET_TCP_MAX_SEG_LIFETIME 60

struct net_context;

struct net_tcp {
	/** Network context back pointer. */
	struct net_context *context;

	/** Cookie pointer passed to net_context_recv() */
	void *recv_user_data;

	/** ACK message timer */
	struct k_delayed_work ack_timer;

	/** Timer for doing active close in case the peer FIN is lost. */
	struct k_delayed_work fin_timer;

	/** Retransmit timer */
	struct k_timer retry_timer;

	/** List pointer used for TCP retransmit buffering */
	sys_slist_t sent_list;

	/** Max acknowledgment. */
	u32_t recv_max_ack;

	/** Current sequence number. */
	u32_t send_seq;

	/** Acknowledgment number to send in next packet. */
	u32_t send_ack;

	/** Last ACK value sent */
	u32_t sent_ack;

	/** Current retransmit period */
	u32_t retry_timeout_shift : 5;
	/** Flags for the TCP */
	u32_t flags : 8;
	/** Current TCP state */
	u32_t state : 4;
	/* An outbound FIN packet has been sent */
	u32_t fin_sent : 1;
	/* An inbound FIN packet has been received */
	u32_t fin_rcvd : 1;
	/** Remaining bits in this u32_t */
	u32_t _padding : 13;

	/** Accept callback to be called when the connection has been
	 * established.
	 */
	net_tcp_accept_cb_t accept_cb;

	/**
	 * Semaphore to signal TCP connection completion
	 */
	struct k_sem connect_wait;

	u16_t recv_wnd;
};

static inline bool net_tcp_is_used(struct net_tcp *tcp)
{
	NET_ASSERT(tcp);

	return tcp->flags & NET_TCP_IN_USE;
}

/**
 * @brief Register a callback to be called when TCP packet
 * is received corresponding to received packet.
 *
 * @param remote_addr Remote address of the connection end point.
 * @param local_addr Local address of the connection end point.
 * @param remote_port Remote port of the connection end point.
 * @param local_port Local port of the connection end point.
 * @param cb Callback to be called
 * @param user_data User data supplied by caller.
 * @param handle TCP handle that can be used when unregistering
 *
 * @return Return 0 if the registration succeed, <0 otherwise.
 */
static inline int net_tcp_register(const struct sockaddr *remote_addr,
				   const struct sockaddr *local_addr,
				   u16_t remote_port,
				   u16_t local_port,
				   net_conn_cb_t cb,
				   void *user_data,
				   struct net_conn_handle **handle)
{
	return net_conn_register(IPPROTO_TCP, remote_addr, local_addr,
				 remote_port, local_port, cb, user_data,
				 handle);
}

/**
 * @brief Unregister TCP handler.
 *
 * @param handle Handle from registering.
 *
 * @return Return 0 if the unregistration succeed, <0 otherwise.
 */
static inline int net_tcp_unregister(struct net_conn_handle *handle)
{
	return net_conn_unregister(handle);
}

/*
 * @brief Generate initial TCP sequence number
 *
 * @return Return a random TCP sequence number
 */
static inline u32_t tcp_init_isn(void)
{
	/* Randomise initial seq number */
	return sys_rand32_get();
}

const char *net_tcp_state_str(enum net_tcp_state state);

#if defined(CONFIG_NET_TCP)
void net_tcp_change_state(struct net_tcp *tcp, enum net_tcp_state new_state);
#else
#define net_tcp_change_state(...)
#endif

/**
 * @brief Allocate TCP connection context.
 *
 * @param context Pointer to net_context that is tied to this TCP
 * context.
 *
 * @return Pointer TCP connection context. NULL if no available
 * context can be found.
 */
struct net_tcp *net_tcp_alloc(struct net_context *context);

/**
 * @brief Release TCP connection context.
 *
 * @param tcp Pointer to net_tcp context.
 *
 * @return 0 if ok, < 0 if error
 */
int net_tcp_release(struct net_tcp *tcp);

/**
 * @brief Send a TCP segment without any data. The returned buffer
 * is a ready made packet that can be sent via net_send_data()
 * function.
 *
 * @param tcp TCP context
 * @param flags TCP flags
 * @param options Pointer TCP options, NULL if no options.
 * @param optlen Length of the options.
 * @param local Source address, or NULL to use the local address of
 *        the TCP context
 * @param remote Peer address
 * @param send_pkt Full IP + TCP header that is to be sent.
 *
 * @return 0 if ok, < 0 if error
 */
int net_tcp_prepare_segment(struct net_tcp *tcp, u8_t flags,
			    void *options, size_t optlen,
			    const struct sockaddr_ptr *local,
			    const struct sockaddr *remote,
			    struct net_pkt **send_pkt);

/**
 * @brief Prepare a TCP ACK message that can be send to peer.
 *
 * @param tcp TCP context
 * @param remote Peer address
 * @param pkt Network buffer
 *
 * @return 0 if ok, < 0 if error
 */
int net_tcp_prepare_ack(struct net_tcp *tcp, const struct sockaddr *remote,
			struct net_pkt **pkt);

/**
 * @brief Prepare a TCP RST message that can be send to peer.
 *
 * @param tcp TCP context
 * @param remote Peer address
 * @param pkt Network buffer
 *
 * @return 0 if ok, < 0 if error
 */
int net_tcp_prepare_reset(struct net_tcp *tcp, const struct sockaddr *remote,
			  struct net_pkt **pkt);

typedef void (*net_tcp_cb_t)(struct net_tcp *tcp, void *user_data);

/**
 * @brief Go through all the TCP connections and call callback
 * for each of them.
 *
 * @param cb User supplied callback function to call.
 * @param user_data User specified data.
 */
void net_tcp_foreach(net_tcp_cb_t cb, void *user_data);

/**
 * @brief Send available queued data over TCP connection
 *
 * @param context TCP context
 *
 * @return 0 if ok, < 0 if error
 */
int net_tcp_send_data(struct net_context *context);

/**
 * @brief Enqueue a single packet for transmission
 *
 * @param context TCP context
 * @param pkt Packet
 *
 * @return 0 if ok, < 0 if error
 */
int net_tcp_queue_data(struct net_context *context, struct net_pkt *pkt);

/**
 * @brief Sends one TCP packet initialized with the _prepare_*()
 *        family of functions.
 *
 * @param pkt Packet
 */
int net_tcp_send_pkt(struct net_pkt *pkt);

/**
 * @brief Handle a received TCP ACK
 *
 * @param cts Context
 * @param seq Received ACK sequence number
 */
void net_tcp_ack_received(struct net_context *ctx, u32_t ack);

/**
 * @brief Calculates and returns the MSS for a given TCP context
 *
 * @param tcp TCP context
 *
 * @return Maximum Segment Size
 */
u16_t net_tcp_get_recv_mss(const struct net_tcp *tcp);

/**
 * @brief Returns the receive window for a given TCP context
 *
 * @param tcp TCP context
 *
 * @return Current TCP receive window
 */
u32_t net_tcp_get_recv_wnd(const struct net_tcp *tcp);

/**
 * @brief Obtains the state for a TCP context
 *
 * @param tcp TCP context
 */
static inline enum net_tcp_state net_tcp_get_state(const struct net_tcp *tcp)
{
	return (enum net_tcp_state)tcp->state;
}

/**
 * @brief Check if the sequence number is valid i.e., it is inside the window.
 *
 * @param tcp TCP context
 * @param pkt Network packet
 *
 * @return true if network packet sequence number is valid, false otherwise
 */
bool net_tcp_validate_seq(struct net_tcp *tcp, struct net_pkt *pkt);

#if defined(CONFIG_NET_TCP)
/**
 * @brief Get TCP packet header data from net_pkt. The array values are in
 * network byte order and other values are in host byte order.
 *
 * @param pkt Network packet
 * @param hdr Where to place the header.
 *
 * @return Return pointer to header or NULL if something went wrong.
 */
struct net_tcp_hdr *net_tcp_get_hdr(struct net_pkt *pkt,
				    struct net_tcp_hdr *hdr);

/**
 * @brief Set TCP packet header data in net_pkt. The array values are in
 * network byte order and other values are in host byte order.
 *
 * @param pkt Network packet
 * @param hdr Header to be written
 *
 * @return Return hdr or NULL if error
 */
struct net_tcp_hdr *net_tcp_set_hdr(struct net_pkt *pkt,
				    struct net_tcp_hdr *hdr);

/**
 * @brief Set TCP checksum in network packet.
 *
 * @param pkt Network packet
 * @param frag Fragment where to start calculating the offset.
 * Typically this is set to pkt->frags by the caller.
 *
 * @return Return the actual fragment where the checksum was written.
 */
struct net_buf *net_tcp_set_chksum(struct net_pkt *pkt, struct net_buf *frag);

/**
 * @brief Get TCP checksum from network packet.
 *
 * @param pkt Network packet
 * @param frag Fragment where to start calculating the offset.
 * Typically this is set to pkt->frags by the caller.
 *
 * @return Return the checksum in host byte order.
 */
u16_t net_tcp_get_chksum(struct net_pkt *pkt, struct net_buf *frag);

#else

static inline u16_t net_tcp_get_chksum(struct net_pkt *pkt,
				       struct net_buf *frag)
{
	ARG_UNUSED(pkt);
	ARG_UNUSED(frag);
	return 0;
}

static inline struct net_buf *net_tcp_set_chksum(struct net_pkt *pkt,
						 struct net_buf *frag)
{
	ARG_UNUSED(pkt);
	ARG_UNUSED(frag);
	return NULL;
}

static inline struct net_tcp_hdr *net_tcp_get_hdr(struct net_pkt *pkt,
						  struct net_tcp_hdr *hdr)
{
	ARG_UNUSED(pkt);
	ARG_UNUSED(hdr);
	return NULL;
}

static inline struct net_tcp_hdr *net_tcp_set_hdr(struct net_pkt *pkt,
						  struct net_tcp_hdr *hdr)
{
	ARG_UNUSED(pkt);
	ARG_UNUSED(hdr);
	return NULL;
}
#endif

#if defined(CONFIG_NET_TCP)
void net_tcp_init(void);
#else
#define net_tcp_init(...)
#endif

#ifdef __cplusplus
}
#endif

#endif /* __TCP_H */