summaryrefslogtreecommitdiffstats
path: root/include/linux/tcp.h
blob: 6a5e08b937b3156ff876eec85d153b975bf217ef (plain)
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
/* SPDX-License-Identifier: GPL-2.0-or-later */
/*
 * INET		An implementation of the TCP/IP protocol suite for the LINUX
 *		operating system.  INET is implemented using the  BSD Socket
 *		interface as the means of communication with the user level.
 *
 *		Definitions for the TCP protocol.
 *
 * Version:	@(#)tcp.h	1.0.2	04/28/93
 *
 * Author:	Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
 */
#ifndef _LINUX_TCP_H
#define _LINUX_TCP_H


#include <linux/skbuff.h>
#include <linux/win_minmax.h>
#include <net/sock.h>
#include <net/inet_connection_sock.h>
#include <net/inet_timewait_sock.h>
#include <uapi/linux/tcp.h>

static inline struct tcphdr *tcp_hdr(const struct sk_buff *skb)
{
	return (struct tcphdr *)skb_transport_header(skb);
}

static inline unsigned int __tcp_hdrlen(const struct tcphdr *th)
{
	return th->doff * 4;
}

static inline unsigned int tcp_hdrlen(const struct sk_buff *skb)
{
	return __tcp_hdrlen(tcp_hdr(skb));
}

static inline struct tcphdr *inner_tcp_hdr(const struct sk_buff *skb)
{
	return (struct tcphdr *)skb_inner_transport_header(skb);
}

static inline unsigned int inner_tcp_hdrlen(const struct sk_buff *skb)
{
	return inner_tcp_hdr(skb)->doff * 4;
}

/**
 * skb_tcp_all_headers - Returns size of all headers for a TCP packet
 * @skb: buffer
 *
 * Used in TX path, for a packet known to be a TCP one.
 *
 * if (skb_is_gso(skb)) {
 *         int hlen = skb_tcp_all_headers(skb);
 *         ...
 */
static inline int skb_tcp_all_headers(const struct sk_buff *skb)
{
	return skb_transport_offset(skb) + tcp_hdrlen(skb);
}

/**
 * skb_inner_tcp_all_headers - Returns size of all headers for an encap TCP packet
 * @skb: buffer
 *
 * Used in TX path, for a packet known to be a TCP one.
 *
 * if (skb_is_gso(skb) && skb->encapsulation) {
 *         int hlen = skb_inner_tcp_all_headers(skb);
 *         ...
 */
static inline int skb_inner_tcp_all_headers(const struct sk_buff *skb)
{
	return skb_inner_transport_offset(skb) + inner_tcp_hdrlen(skb);
}

static inline unsigned int tcp_optlen(const struct sk_buff *skb)
{
	return (tcp_hdr(skb)->doff - 5) * 4;
}

/* TCP Fast Open */
#define TCP_FASTOPEN_COOKIE_MIN	4	/* Min Fast Open Cookie size in bytes */
#define TCP_FASTOPEN_COOKIE_MAX	16	/* Max Fast Open Cookie size in bytes */
#define TCP_FASTOPEN_COOKIE_SIZE 8	/* the size employed by this impl. */

/* TCP Fast Open Cookie as stored in memory */
struct tcp_fastopen_cookie {
	__le64	val[DIV_ROUND_UP(TCP_FASTOPEN_COOKIE_MAX, sizeof(u64))];
	s8	len;
	bool	exp;	/* In RFC6994 experimental option format */
};

/* This defines a selective acknowledgement block. */
struct tcp_sack_block_wire {
	__be32	start_seq;
	__be32	end_seq;
};

struct tcp_sack_block {
	u32	start_seq;
	u32	end_seq;
};

/*These are used to set the sack_ok field in struct tcp_options_received */
#define TCP_SACK_SEEN     (1 << 0)   /*1 = peer is SACK capable, */
#define TCP_DSACK_SEEN    (1 << 2)   /*1 = DSACK was received from peer*/

struct tcp_options_received {
/*	PAWS/RTTM data	*/
	int	ts_recent_stamp;/* Time we stored ts_recent (for aging) */
	u32	ts_recent;	/* Time stamp to echo next		*/
	u32	rcv_tsval;	/* Time stamp value             	*/
	u32	rcv_tsecr;	/* Time stamp echo reply        	*/
	u16 	saw_tstamp : 1,	/* Saw TIMESTAMP on last packet		*/
		tstamp_ok : 1,	/* TIMESTAMP seen on SYN packet		*/
		dsack : 1,	/* D-SACK is scheduled			*/
		wscale_ok : 1,	/* Wscale seen on SYN packet		*/
		sack_ok : 3,	/* SACK seen on SYN packet		*/
		smc_ok : 1,	/* SMC seen on SYN packet		*/
		snd_wscale : 4,	/* Window scaling received from sender	*/
		rcv_wscale : 4;	/* Window scaling to send to receiver	*/
	u8	saw_unknown:1,	/* Received unknown option		*/
		unused:7;
	u8	num_sacks;	/* Number of SACK blocks		*/
	u16	user_mss;	/* mss requested by user in ioctl	*/
	u16	mss_clamp;	/* Maximal mss, negotiated at connection setup */
};

static inline void tcp_clear_options(struct tcp_options_received *rx_opt)
{
	rx_opt->tstamp_ok = rx_opt->sack_ok = 0;
	rx_opt->wscale_ok = rx_opt->snd_wscale = 0;
#if IS_ENABLED(CONFIG_SMC)
	rx_opt->smc_ok = 0;
#endif
}

/* This is the max number of SACKS that we'll generate and process. It's safe
 * to increase this, although since:
 *   size = TCPOLEN_SACK_BASE_ALIGNED (4) + n * TCPOLEN_SACK_PERBLOCK (8)
 * only four options will fit in a standard TCP header */
#define TCP_NUM_SACKS 4

struct tcp_request_sock_ops;

struct tcp_request_sock {
	struct inet_request_sock 	req;
	const struct tcp_request_sock_ops *af_specific;
	u64				snt_synack; /* first SYNACK sent time */
	bool				tfo_listener;
	bool				is_mptcp;
	bool				req_usec_ts;
#if IS_ENABLED(CONFIG_MPTCP)
	bool				drop_req;
#endif
	u32				txhash;
	u32				rcv_isn;
	u32				snt_isn;
	u32				ts_off;
	u32				last_oow_ack_time; /* last SYNACK */
	u32				rcv_nxt; /* the ack # by SYNACK. For
						  * FastOpen it's the seq#
						  * after data-in-SYN.
						  */
	u8				syn_tos;
#ifdef CONFIG_TCP_AO
	u8				ao_keyid;
	u8				ao_rcv_next;
	bool				used_tcp_ao;
#endif
};

static inline struct tcp_request_sock *tcp_rsk(const struct request_sock *req)
{
	return (struct tcp_request_sock *)req;
}

static inline bool tcp_rsk_used_ao(const struct request_sock *req)
{
#ifndef CONFIG_TCP_AO
	return false;
#else
	return tcp_rsk(req)->used_tcp_ao;
#endif
}

#define TCP_RMEM_TO_WIN_SCALE 8

struct tcp_sock {
	/* Cacheline organization can be found documented in
	 * Documentation/networking/net_cachelines/tcp_sock.rst.
	 * Please update the document when adding new fields.
	 */

	/* inet_connection_sock has to be the first member of tcp_sock */
	struct inet_connection_sock	inet_conn;

	/* TX read-mostly hotpath cache lines */
	__cacheline_group_begin(tcp_sock_read_tx);
	/* timestamp of last sent data packet (for restart window) */
	u32	max_window;	/* Maximal window ever seen from peer	*/
	u32	rcv_ssthresh;	/* Current window clamp			*/
	u32	reordering;	/* Packet reordering metric.		*/
	u32	notsent_lowat;	/* TCP_NOTSENT_LOWAT */
	u16	gso_segs;	/* Max number of segs per GSO packet	*/
	/* from STCP, retrans queue hinting */
	struct sk_buff *lost_skb_hint;
	struct sk_buff *retransmit_skb_hint;
	__cacheline_group_end(tcp_sock_read_tx);

	/* TXRX read-mostly hotpath cache lines */
	__cacheline_group_begin(tcp_sock_read_txrx);
	u32	tsoffset;	/* timestamp offset */
	u32	snd_wnd;	/* The window we expect to receive	*/
	u32	mss_cache;	/* Cached effective mss, not including SACKS */
	u32	snd_cwnd;	/* Sending congestion window		*/
	u32	prr_out;	/* Total number of pkts sent during Recovery. */
	u32	lost_out;	/* Lost packets			*/
	u32	sacked_out;	/* SACK'd packets			*/
	u16	tcp_header_len;	/* Bytes of tcp header to send		*/
	u8	scaling_ratio;	/* see tcp_win_from_space() */
	u8	chrono_type : 2,	/* current chronograph type */
		repair      : 1,
		tcp_usec_ts : 1, /* TSval values in usec */
		is_sack_reneg:1,    /* in recovery from loss with SACK reneg? */
		is_cwnd_limited:1;/* forward progress limited by snd_cwnd? */
	__cacheline_group_end(tcp_sock_read_txrx);

	/* RX read-mostly hotpath cache lines */
	__cacheline_group_begin(tcp_sock_read_rx);
	u32	copied_seq;	/* Head of yet unread data */
	u32	rcv_tstamp;	/* timestamp of last received ACK (for keepalives) */
	u32	snd_wl1;	/* Sequence for window update		*/
	u32	tlp_high_seq;	/* snd_nxt at the time of TLP */
	u32	rttvar_us;	/* smoothed mdev_max			*/
	u32	retrans_out;	/* Retransmitted packets out		*/
	u16	advmss;		/* Advertised MSS			*/
	u16	urg_data;	/* Saved octet of OOB data and control flags */
	u32	lost;		/* Total data packets lost incl. rexmits */
	struct  minmax rtt_min;
	/* OOO segments go in this rbtree. Socket lock must be held. */
	struct rb_root	out_of_order_queue;
	u32	snd_ssthresh;	/* Slow start size threshold		*/
	u8	recvmsg_inq : 1;/* Indicate # of bytes in queue upon recvmsg */
	__cacheline_group_end(tcp_sock_read_rx);

	/* TX read-write hotpath cache lines */
	__cacheline_group_begin(tcp_sock_write_tx) ____cacheline_aligned;
	u32	segs_out;	/* RFC4898 tcpEStatsPerfSegsOut
				 * The total number of segments sent.
				 */
	u32	data_segs_out;	/* RFC4898 tcpEStatsPerfDataSegsOut
				 * total number of data segments sent.
				 */
	u64	bytes_sent;	/* RFC4898 tcpEStatsPerfHCDataOctetsOut
				 * total number of data bytes sent.
				 */
	u32	snd_sml;	/* Last byte of the most recently transmitted small packet */
	u32	chrono_start;	/* Start time in jiffies of a TCP chrono */
	u32	chrono_stat[3];	/* Time in jiffies for chrono_stat stats */
	u32	write_seq;	/* Tail(+1) of data held in tcp send buffer */
	u32	pushed_seq;	/* Last pushed seq, required to talk to windows */
	u32	lsndtime;
	u32	mdev_us;	/* medium deviation			*/
	u32	rtt_seq;	/* sequence number to update rttvar	*/
	u64	tcp_wstamp_ns;	/* departure time for next sent data packet */
	struct list_head tsorted_sent_queue; /* time-sorted sent but un-SACKed skbs */
	struct sk_buff *highest_sack;   /* skb just after the highest
					 * skb with SACKed bit set
					 * (validity guaranteed only if
					 * sacked_out > 0)
					 */
	u8	ecn_flags;	/* ECN status bits.			*/
	__cacheline_group_end(tcp_sock_write_tx);

	/* TXRX read-write hotpath cache lines */
	__cacheline_group_begin(tcp_sock_write_txrx);
/*
 *	Header prediction flags
 *	0x5?10 << 16 + snd_wnd in net byte order
 */
	__be32	pred_flags;
	u64	tcp_clock_cache; /* cache last tcp_clock_ns() (see tcp_mstamp_refresh()) */
	u64	tcp_mstamp;	/* most recent packet received/sent */
	u32	rcv_nxt;	/* What we want to receive next		*/
	u32	snd_nxt;	/* Next sequence we send		*/
	u32	snd_una;	/* First byte we want an ack for	*/
	u32	window_clamp;	/* Maximal window to advertise		*/
	u32	srtt_us;	/* smoothed round trip time << 3 in usecs */
	u32	packets_out;	/* Packets which are "in flight"	*/
	u32	snd_up;		/* Urgent pointer		*/
	u32	delivered;	/* Total data packets delivered incl. rexmits */
	u32	delivered_ce;	/* Like the above but only ECE marked packets */
	u32	app_limited;	/* limited until "delivered" reaches this val */
	u32	rcv_wnd;	/* Current receiver window		*/
/*
 *      Options received (usually on last packet, some only on SYN packets).
 */
	struct tcp_options_received rx_opt;
	u8	nonagle     : 4,/* Disable Nagle algorithm?             */
		rate_app_limited:1;  /* rate_{delivered,interval_us} limited? */
	__cacheline_group_end(tcp_sock_write_txrx);

	/* RX read-write hotpath cache lines */
	__cacheline_group_begin(tcp_sock_write_rx) __aligned(8);
	u64	bytes_received;
				/* RFC4898 tcpEStatsAppHCThruOctetsReceived
				 * sum(delta(rcv_nxt)), or how many bytes
				 * were acked.
				 */
	u32	segs_in;	/* RFC4898 tcpEStatsPerfSegsIn
				 * total number of segments in.
				 */
	u32	data_segs_in;	/* RFC4898 tcpEStatsPerfDataSegsIn
				 * total number of data segments in.
				 */
	u32	rcv_wup;	/* rcv_nxt on last window update sent	*/
	u32	max_packets_out;  /* max packets_out in last window */
	u32	cwnd_usage_seq;  /* right edge of cwnd usage tracking flight */
	u32	rate_delivered;    /* saved rate sample: packets delivered */
	u32	rate_interval_us;  /* saved rate sample: time elapsed */
	u32	rcv_rtt_last_tsecr;
	u64	first_tx_mstamp;  /* start of window send phase */
	u64	delivered_mstamp; /* time we reached "delivered" */
	u64	bytes_acked;	/* RFC4898 tcpEStatsAppHCThruOctetsAcked
				 * sum(delta(snd_una)), or how many bytes
				 * were acked.
				 */
	struct {
		u32	rtt_us;
		u32	seq;
		u64	time;
	} rcv_rtt_est;
/* Receiver queue space */
	struct {
		u32	space;
		u32	seq;
		u64	time;
	} rcvq_space;
	__cacheline_group_end(tcp_sock_write_rx);
	/* End of Hot Path */

/*
 *	RFC793 variables by their proper names. This means you can
 *	read the code and the spec side by side (and laugh ...)
 *	See RFC793 and RFC1122. The RFC writes these in capitals.
 */
	u32	dsack_dups;	/* RFC4898 tcpEStatsStackDSACKDups
				 * total number of DSACK blocks received
				 */
	u32	compressed_ack_rcv_nxt;
	struct list_head tsq_node; /* anchor in tsq_tasklet.head list */

	/* Information of the most recently (s)acked skb */
	struct tcp_rack {
		u64 mstamp; /* (Re)sent time of the skb */
		u32 rtt_us;  /* Associated RTT */
		u32 end_seq; /* Ending TCP sequence of the skb */
		u32 last_delivered; /* tp->delivered at last reo_wnd adj */
		u8 reo_wnd_steps;   /* Allowed reordering window */
#define TCP_RACK_RECOVERY_THRESH 16
		u8 reo_wnd_persist:5, /* No. of recovery since last adj */
		   dsack_seen:1, /* Whether DSACK seen after last adj */
		   advanced:1;	 /* mstamp advanced since last lost marking */
	} rack;
	u8	compressed_ack;
	u8	dup_ack_counter:2,
		tlp_retrans:1,	/* TLP is a retransmission */
		unused:5;
	u8	thin_lto    : 1,/* Use linear timeouts for thin streams */
		fastopen_connect:1, /* FASTOPEN_CONNECT sockopt */
		fastopen_no_cookie:1, /* Allow send/recv SYN+data without a cookie */
		fastopen_client_fail:2, /* reason why fastopen failed */
		frto        : 1;/* F-RTO (RFC5682) activated in CA_Loss */
	u8	repair_queue;
	u8	save_syn:2,	/* Save headers of SYN packet */
		syn_data:1,	/* SYN includes data */
		syn_fastopen:1,	/* SYN includes Fast Open option */
		syn_fastopen_exp:1,/* SYN includes Fast Open exp. option */
		syn_fastopen_ch:1, /* Active TFO re-enabling probe */
		syn_data_acked:1;/* data in SYN is acked by SYN-ACK */

	u8	keepalive_probes; /* num of allowed keep alive probes	*/
	u32	tcp_tx_delay;	/* delay (in usec) added to TX packets */

/* RTT measurement */
	u32	mdev_max_us;	/* maximal mdev for the last rtt period	*/

	u32	reord_seen;	/* number of data packet reordering events */

/*
 *	Slow start and congestion control (see also Nagle, and Karn & Partridge)
 */
	u32	snd_cwnd_cnt;	/* Linear increase counter		*/
	u32	snd_cwnd_clamp; /* Do not allow snd_cwnd to grow above this */
	u32	snd_cwnd_used;
	u32	snd_cwnd_stamp;
	u32	prior_cwnd;	/* cwnd right before starting loss recovery */
	u32	prr_delivered;	/* Number of newly delivered packets to
				 * receiver in Recovery. */
	u32	last_oow_ack_time;  /* timestamp of last out-of-window ACK */

	struct hrtimer	pacing_timer;
	struct hrtimer	compressed_ack_timer;

	struct sk_buff	*ooo_last_skb; /* cache rb_last(out_of_order_queue) */

	/* SACKs data, these 2 need to be together (see tcp_options_write) */
	struct tcp_sack_block duplicate_sack[1]; /* D-SACK block */
	struct tcp_sack_block selective_acks[4]; /* The SACKS themselves*/

	struct tcp_sack_block recv_sack_cache[4];

	int     lost_cnt_hint;

	u32	prior_ssthresh; /* ssthresh saved at recovery start	*/
	u32	high_seq;	/* snd_nxt at onset of congestion	*/

	u32	retrans_stamp;	/* Timestamp of the last retransmit,
				 * also used in SYN-SENT to remember stamp of
				 * the first SYN. */
	u32	undo_marker;	/* snd_una upon a new recovery episode. */
	int	undo_retrans;	/* number of undoable retransmissions. */
	u64	bytes_retrans;	/* RFC4898 tcpEStatsPerfOctetsRetrans
				 * Total data bytes retransmitted
				 */
	u32	total_retrans;	/* Total retransmits for entire connection */
	u32	rto_stamp;	/* Start time (ms) of last CA_Loss recovery */
	u16	total_rto;	/* Total number of RTO timeouts, including
				 * SYN/SYN-ACK and recurring timeouts.
				 */
	u16	total_rto_recoveries;	/* Total number of RTO recoveries,
					 * including any unfinished recovery.
					 */
	u32	total_rto_time;	/* ms spent in (completed) RTO recoveries. */

	u32	urg_seq;	/* Seq of received urgent pointer */
	unsigned int		keepalive_time;	  /* time before keep alive takes place */
	unsigned int		keepalive_intvl;  /* time interval between keep alive probes */

	int			linger2;


/* Sock_ops bpf program related variables */
#ifdef CONFIG_BPF
	u8	bpf_sock_ops_cb_flags;  /* Control calling BPF programs
					 * values defined in uapi/linux/tcp.h
					 */
	u8	bpf_chg_cc_inprogress:1; /* In the middle of
					  * bpf_setsockopt(TCP_CONGESTION),
					  * it is to avoid the bpf_tcp_cc->init()
					  * to recur itself by calling
					  * bpf_setsockopt(TCP_CONGESTION, "itself").
					  */
#define BPF_SOCK_OPS_TEST_FLAG(TP, ARG) (TP->bpf_sock_ops_cb_flags & ARG)
#else
#define BPF_SOCK_OPS_TEST_FLAG(TP, ARG) 0
#endif

	u16 timeout_rehash;	/* Timeout-triggered rehash attempts */

	u32 rcv_ooopack; /* Received out-of-order packets, for tcpinfo */

/* TCP-specific MTU probe information. */
	struct {
		u32		  probe_seq_start;
		u32		  probe_seq_end;
	} mtu_probe;
	u32     plb_rehash;     /* PLB-triggered rehash attempts */
	u32	mtu_info; /* We received an ICMP_FRAG_NEEDED / ICMPV6_PKT_TOOBIG
			   * while socket was owned by user.
			   */
#if IS_ENABLED(CONFIG_MPTCP)
	bool	is_mptcp;
#endif
#if IS_ENABLED(CONFIG_SMC)
	bool	syn_smc;	/* SYN includes SMC */
	bool	(*smc_hs_congested)(const struct sock *sk);
#endif

#if defined(CONFIG_TCP_MD5SIG) || defined(CONFIG_TCP_AO)
/* TCP AF-Specific parts; only used by TCP-AO/MD5 Signature support so far */
	const struct tcp_sock_af_ops	*af_specific;

#ifdef CONFIG_TCP_MD5SIG
/* TCP MD5 Signature Option information */
	struct tcp_md5sig_info	__rcu *md5sig_info;
#endif
#ifdef CONFIG_TCP_AO
	struct tcp_ao_info	__rcu *ao_info;
#endif
#endif

/* TCP fastopen related information */
	struct tcp_fastopen_request *fastopen_req;
	/* fastopen_rsk points to request_sock that resulted in this big
	 * socket. Used to retransmit SYNACKs etc.
	 */
	struct request_sock __rcu *fastopen_rsk;
	struct saved_syn *saved_syn;
};

enum tsq_enum {
	TSQ_THROTTLED,
	TSQ_QUEUED,
	TCP_TSQ_DEFERRED,	   /* tcp_tasklet_func() found socket was owned */
	TCP_WRITE_TIMER_DEFERRED,  /* tcp_write_timer() found socket was owned */
	TCP_DELACK_TIMER_DEFERRED, /* tcp_delack_timer() found socket was owned */
	TCP_MTU_REDUCED_DEFERRED,  /* tcp_v{4|6}_err() could not call
				    * tcp_v{4|6}_mtu_reduced()
				    */
	TCP_ACK_DEFERRED,	   /* TX pure ack is deferred */
};

enum tsq_flags {
	TSQF_THROTTLED			= BIT(TSQ_THROTTLED),
	TSQF_QUEUED			= BIT(TSQ_QUEUED),
	TCPF_TSQ_DEFERRED		= BIT(TCP_TSQ_DEFERRED),
	TCPF_WRITE_TIMER_DEFERRED	= BIT(TCP_WRITE_TIMER_DEFERRED),
	TCPF_DELACK_TIMER_DEFERRED	= BIT(TCP_DELACK_TIMER_DEFERRED),
	TCPF_MTU_REDUCED_DEFERRED	= BIT(TCP_MTU_REDUCED_DEFERRED),
	TCPF_ACK_DEFERRED		= BIT(TCP_ACK_DEFERRED),
};

#define tcp_sk(ptr) container_of_const(ptr, struct tcp_sock, inet_conn.icsk_inet.sk)

/* Variant of tcp_sk() upgrading a const sock to a read/write tcp socket.
 * Used in context of (lockless) tcp listeners.
 */
#define tcp_sk_rw(ptr) container_of(ptr, struct tcp_sock, inet_conn.icsk_inet.sk)

struct tcp_timewait_sock {
	struct inet_timewait_sock tw_sk;
#define tw_rcv_nxt tw_sk.__tw_common.skc_tw_rcv_nxt
#define tw_snd_nxt tw_sk.__tw_common.skc_tw_snd_nxt
	u32			  tw_rcv_wnd;
	u32			  tw_ts_offset;
	u32			  tw_ts_recent;

	/* The time we sent the last out-of-window ACK: */
	u32			  tw_last_oow_ack_time;

	int			  tw_ts_recent_stamp;
	u32			  tw_tx_delay;
#ifdef CONFIG_TCP_MD5SIG
	struct tcp_md5sig_key	  *tw_md5_key;
#endif
#ifdef CONFIG_TCP_AO
	struct tcp_ao_info	__rcu *ao_info;
#endif
};

static inline struct tcp_timewait_sock *tcp_twsk(const struct sock *sk)
{
	return (struct tcp_timewait_sock *)sk;
}

static inline bool tcp_passive_fastopen(const struct sock *sk)
{
	return sk->sk_state == TCP_SYN_RECV &&
	       rcu_access_pointer(tcp_sk(sk)->fastopen_rsk) != NULL;
}

static inline void fastopen_queue_tune(struct sock *sk, int backlog)
{
	struct request_sock_queue *queue = &inet_csk(sk)->icsk_accept_queue;
	int somaxconn = READ_ONCE(sock_net(sk)->core.sysctl_somaxconn);

	WRITE_ONCE(queue->fastopenq.max_qlen, min_t(unsigned int, backlog, somaxconn));
}

static inline void tcp_move_syn(struct tcp_sock *tp,
				struct request_sock *req)
{
	tp->saved_syn = req->saved_syn;
	req->saved_syn = NULL;
}

static inline void tcp_saved_syn_free(struct tcp_sock *tp)
{
	kfree(tp->saved_syn);
	tp->saved_syn = NULL;
}

static inline u32 tcp_saved_syn_len(const struct saved_syn *saved_syn)
{
	return saved_syn->mac_hdrlen + saved_syn->network_hdrlen +
		saved_syn->tcp_hdrlen;
}

struct sk_buff *tcp_get_timestamping_opt_stats(const struct sock *sk,
					       const struct sk_buff *orig_skb,
					       const struct sk_buff *ack_skb);

static inline u16 tcp_mss_clamp(const struct tcp_sock *tp, u16 mss)
{
	/* We use READ_ONCE() here because socket might not be locked.
	 * This happens for listeners.
	 */
	u16 user_mss = READ_ONCE(tp->rx_opt.user_mss);

	return (user_mss && user_mss < mss) ? user_mss : mss;
}

int tcp_skb_shift(struct sk_buff *to, struct sk_buff *from, int pcount,
		  int shiftlen);

void __tcp_sock_set_cork(struct sock *sk, bool on);
void tcp_sock_set_cork(struct sock *sk, bool on);
int tcp_sock_set_keepcnt(struct sock *sk, int val);
int tcp_sock_set_keepidle_locked(struct sock *sk, int val);
int tcp_sock_set_keepidle(struct sock *sk, int val);
int tcp_sock_set_keepintvl(struct sock *sk, int val);
void __tcp_sock_set_nodelay(struct sock *sk, bool on);
void tcp_sock_set_nodelay(struct sock *sk);
void tcp_sock_set_quickack(struct sock *sk, int val);
int tcp_sock_set_syncnt(struct sock *sk, int val);
int tcp_sock_set_user_timeout(struct sock *sk, int val);

static inline bool dst_tcp_usec_ts(const struct dst_entry *dst)
{
	return dst_feature(dst, RTAX_FEATURE_TCP_USEC_TS);
}

#endif	/* _LINUX_TCP_H */