aboutsummaryrefslogtreecommitdiffstats
path: root/src/vnet/tcp/tcp.h
blob: 52610dddaea45dfb4c9e4981e3dc64009f364513 (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
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
/*
 * Copyright (c) 2016 Cisco and/or its affiliates.
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at:
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#ifndef _vnet_tcp_h_
#define _vnet_tcp_h_

#include <vnet/vnet.h>
#include <vnet/ip/ip.h>
#include <vnet/tcp/tcp_packet.h>
#include <vnet/tcp/tcp_timer.h>
#include <vnet/session/transport.h>
#include <vnet/session/session.h>
#include <vnet/tcp/tcp_debug.h>

#define TCP_TICK 0.001			/**< TCP tick period (s) */
#define THZ (u32) (1/TCP_TICK)		/**< TCP tick frequency */
#define TCP_TSTAMP_RESOLUTION TCP_TICK	/**< Time stamp resolution */
#define TCP_PAWS_IDLE 24 * 24 * 60 * 60 * THZ /**< 24 days */
#define TCP_FIB_RECHECK_PERIOD	1 * THZ	/**< Recheck every 1s */
#define TCP_MAX_OPTION_SPACE 40

#define TCP_DUPACK_THRESHOLD 	3
#define TCP_MAX_RX_FIFO_SIZE 	4 << 20
#define TCP_MIN_RX_FIFO_SIZE	4 << 10
#define TCP_IW_N_SEGMENTS 	10
#define TCP_ALWAYS_ACK		1	/**< On/off delayed acks */
#define TCP_USE_SACKS		1	/**< Disable only for testing */

/** TCP FSM state definitions as per RFC793. */
#define foreach_tcp_fsm_state   \
  _(CLOSED, "CLOSED")           \
  _(LISTEN, "LISTEN")           \
  _(SYN_SENT, "SYN_SENT")       \
  _(SYN_RCVD, "SYN_RCVD")       \
  _(ESTABLISHED, "ESTABLISHED") \
  _(CLOSE_WAIT, "CLOSE_WAIT")   \
  _(FIN_WAIT_1, "FIN_WAIT_1")   \
  _(LAST_ACK, "LAST_ACK")       \
  _(CLOSING, "CLOSING")         \
  _(FIN_WAIT_2, "FIN_WAIT_2")   \
  _(TIME_WAIT, "TIME_WAIT")

typedef enum _tcp_state
{
#define _(sym, str) TCP_STATE_##sym,
  foreach_tcp_fsm_state
#undef _
  TCP_N_STATES
} tcp_state_t;

format_function_t format_tcp_state;
format_function_t format_tcp_flags;
format_function_t format_tcp_sacks;
format_function_t format_tcp_rcv_sacks;

/** TCP timers */
#define foreach_tcp_timer               \
  _(RETRANSMIT, "RETRANSMIT")           \
  _(DELACK, "DELAYED ACK")              \
  _(PERSIST, "PERSIST")                 \
  _(KEEP, "KEEP")                       \
  _(WAITCLOSE, "WAIT CLOSE")            \
  _(RETRANSMIT_SYN, "RETRANSMIT SYN")   \
  _(ESTABLISH, "ESTABLISH")

typedef enum _tcp_timers
{
#define _(sym, str) TCP_TIMER_##sym,
  foreach_tcp_timer
#undef _
  TCP_N_TIMERS
} tcp_timers_e;

typedef void (timer_expiration_handler) (u32 index);

extern timer_expiration_handler tcp_timer_delack_handler;
extern timer_expiration_handler tcp_timer_retransmit_handler;
extern timer_expiration_handler tcp_timer_persist_handler;
extern timer_expiration_handler tcp_timer_retransmit_syn_handler;

#define TCP_TIMER_HANDLE_INVALID ((u32) ~0)

/* Timer delays as multiples of 100ms */
#define TCP_TO_TIMER_TICK       TCP_TICK*10	/* Period for converting from TCP
						 * ticks to timer units */
#define TCP_DELACK_TIME         1	/* 0.1s */
#define TCP_ESTABLISH_TIME      750	/* 75s */
#define TCP_2MSL_TIME           300	/* 30s */
#define TCP_CLOSEWAIT_TIME	20	/* 0.1s */
#define TCP_CLEANUP_TIME	5	/* 0.5s Time to wait before cleanup */
#define TCP_TIMER_PERSIST_MIN	2	/* 0.2s */

#define TCP_RTO_MAX 60 * THZ	/* Min max RTO (60s) as per RFC6298 */
#define TCP_RTO_MIN 0.2 * THZ	/* Min RTO (200ms) - lower than standard */
#define TCP_RTT_MAX 30 * THZ	/* 30s (probably too much) */
#define TCP_RTO_SYN_RETRIES 3	/* SYN retries without doubling RTO */
#define TCP_RTO_INIT 1 * THZ	/* Initial retransmit timer */

/** TCP connection flags */
#define foreach_tcp_connection_flag             \
  _(SNDACK, "Send ACK")                         \
  _(FINSNT, "FIN sent")				\
  _(SENT_RCV_WND0, "Sent 0 receive window")     \
  _(RECOVERY, "Recovery on")                    \
  _(FAST_RECOVERY, "Fast Recovery on")		\
  _(FR_1_SMSS, "Sent 1 SMSS")			\
  _(HALF_OPEN_DONE, "Half-open completed")	\
  _(FINPNDG, "FIN pending")

typedef enum _tcp_connection_flag_bits
{
#define _(sym, str) TCP_CONN_##sym##_BIT,
  foreach_tcp_connection_flag
#undef _
  TCP_CONN_N_FLAG_BITS
} tcp_connection_flag_bits_e;

typedef enum _tcp_connection_flag
{
#define _(sym, str) TCP_CONN_##sym = 1 << TCP_CONN_##sym##_BIT,
  foreach_tcp_connection_flag
#undef _
  TCP_CONN_N_FLAGS
} tcp_connection_flags_e;

/** TCP buffer flags */
#define foreach_tcp_buf_flag                            \
  _ (ACK)       /**< Sending ACK. */                    \
  _ (DUPACK)    /**< Sending DUPACK. */                 \

enum
{
#define _(f) TCP_BUF_BIT_##f,
  foreach_tcp_buf_flag
#undef _
    TCP_N_BUF_BITS,
};

enum
{
#define _(f) TCP_BUF_FLAG_##f = 1 << TCP_BUF_BIT_##f,
  foreach_tcp_buf_flag
#undef _
};

#define TCP_SCOREBOARD_TRACE (0)
#define TCP_MAX_SACK_BLOCKS 15	/**< Max number of SACK blocks stored */
#define TCP_INVALID_SACK_HOLE_INDEX ((u32)~0)

typedef struct _scoreboard_trace_elt
{
  u32 start;
  u32 end;
  u32 ack;
  u32 snd_una_max;
  u32 group;
} scoreboard_trace_elt_t;

typedef struct _sack_scoreboard_hole
{
  u32 next;		/**< Index for next entry in linked list */
  u32 prev;		/**< Index for previous entry in linked list */
  u32 start;		/**< Start sequence number */
  u32 end;		/**< End sequence number */
  u8 is_lost;		/**< Mark hole as lost */
} sack_scoreboard_hole_t;

typedef struct _sack_scoreboard
{
  sack_scoreboard_hole_t *holes;	/**< Pool of holes */
  u32 head;				/**< Index of first entry */
  u32 tail;				/**< Index of last entry */
  u32 sacked_bytes;			/**< Number of bytes sacked in sb */
  u32 last_sacked_bytes;		/**< Number of bytes last sacked */
  u32 last_bytes_delivered;		/**< Number of sack bytes delivered */
  u32 snd_una_adv;			/**< Bytes to add to snd_una */
  u32 high_sacked;			/**< Highest byte sacked (fack) */
  u32 high_rxt;				/**< Highest retransmitted sequence */
  u32 rescue_rxt;			/**< Rescue sequence number */
  u32 lost_bytes;			/**< Bytes lost as per RFC6675 */
  u32 cur_rxt_hole;			/**< Retransmitting from this hole */

#if TCP_SCOREBOARD_TRACE
  scoreboard_trace_elt_t *trace;
#endif

} sack_scoreboard_t;

#if TCP_SCOREBOARD_TRACE
#define tcp_scoreboard_trace_add(_tc, _ack) 				\
{									\
    static u64 _group = 0;						\
    sack_scoreboard_t *_sb = &_tc->sack_sb;				\
    sack_block_t *_sack, *_sacks;					\
    scoreboard_trace_elt_t *_elt;					\
    int i;								\
    _group++;								\
    _sacks = _tc->rcv_opts.sacks;					\
    for (i = 0; i < vec_len (_sacks); i++) 				\
      {									\
	_sack = &_sacks[i];						\
	vec_add2 (_sb->trace, _elt, 1);					\
	_elt->start = _sack->start;					\
	_elt->end = _sack->end;						\
	_elt->ack = _elt->end == _ack ? _ack : 0;			\
	_elt->snd_una_max = _elt->end == _ack ? _tc->snd_una_max : 0;	\
	_elt->group = _group;						\
      }									\
}
#else
#define tcp_scoreboard_trace_add(_tc, _ack)
#endif

typedef enum _tcp_cc_algorithm_type
{
  TCP_CC_NEWRENO,
} tcp_cc_algorithm_type_e;

typedef struct _tcp_cc_algorithm tcp_cc_algorithm_t;

typedef enum _tcp_cc_ack_t
{
  TCP_CC_ACK,
  TCP_CC_DUPACK,
  TCP_CC_PARTIALACK
} tcp_cc_ack_t;

typedef struct _tcp_connection
{
  transport_connection_t connection;  /**< Common transport data. First! */

  u8 state;			/**< TCP state as per tcp_state_t */
  u16 flags;			/**< Connection flags (see tcp_conn_flags_e) */
  u32 timers[TCP_N_TIMERS];	/**< Timer handles into timer wheel */

  /* TODO RFC4898 */

  /** Send sequence variables RFC793 */
  u32 snd_una;		/**< oldest unacknowledged sequence number */
  u32 snd_una_max;	/**< newest unacknowledged sequence number + 1*/
  u32 snd_wnd;		/**< send window */
  u32 snd_wl1;		/**< seq number used for last snd.wnd update */
  u32 snd_wl2;		/**< ack number used for last snd.wnd update */
  u32 snd_nxt;		/**< next seq number to be sent */
  u16 snd_mss;		/**< Effective send max seg (data) size */

  /** Receive sequence variables RFC793 */
  u32 rcv_nxt;		/**< next sequence number expected */
  u32 rcv_wnd;		/**< receive window we expect */

  u32 rcv_las;		/**< rcv_nxt at last ack sent/rcv_wnd update */
  u32 iss;		/**< initial sent sequence */
  u32 irs;		/**< initial remote sequence */

  /* Options */
  tcp_options_t rcv_opts;	/**< Rx options for connection */
  tcp_options_t snd_opts;	/**< Tx options for connection */
  u8 snd_opts_len;		/**< Tx options len */
  u8 rcv_wscale;	/**< Window scale to advertise to peer */
  u8 snd_wscale;	/**< Window scale to use when sending */
  u32 tsval_recent;	/**< Last timestamp received */
  u32 tsval_recent_age;	/**< When last updated tstamp_recent*/

  sack_block_t *snd_sacks;	/**< Vector of SACKs to send. XXX Fixed size? */
  sack_scoreboard_t sack_sb;	/**< SACK "scoreboard" that tracks holes */

  u16 rcv_dupacks;	/**< Number of DUPACKs received */
  u8 snt_dupacks;	/**< Number of DUPACKs sent in a burst */

  /* Congestion control */
  u32 cwnd;		/**< Congestion window */
  u32 ssthresh;		/**< Slow-start threshold */
  u32 prev_ssthresh;	/**< ssthresh before congestion */
  u32 prev_cwnd;	/**< ssthresh before congestion */
  u32 bytes_acked;	/**< Bytes acknowledged by current segment */
  u32 snd_rxt_bytes;	/**< Retransmitted bytes */
  u32 snd_rxt_ts;	/**< Timestamp when first packet is retransmitted */
  u32 tsecr_last_ack;	/**< Timestamp echoed to us in last healthy ACK */
  u32 snd_congestion;	/**< snd_una_max when congestion is detected */
  tcp_cc_algorithm_t *cc_algo;	/**< Congestion control algorithm */

  /* RTT and RTO */
  u32 rto;		/**< Retransmission timeout */
  u32 rto_boff;		/**< Index for RTO backoff */
  u32 srtt;		/**< Smoothed RTT */
  u32 rttvar;		/**< Smoothed mean RTT difference. Approximates variance */
  u32 rtt_ts;		/**< Timestamp for tracked ACK */
  u32 rtt_seq;		/**< Sequence number for tracked ACK */

  u16 mss;		/**< Our max seg size that includes options */
  u32 limited_transmit;	/**< snd_nxt when limited transmit starts */
  u32 last_fib_check;	/**< Last time we checked fib route for peer */
} tcp_connection_t;

struct _tcp_cc_algorithm
{
  void (*rcv_ack) (tcp_connection_t * tc);
  void (*rcv_cong_ack) (tcp_connection_t * tc, tcp_cc_ack_t ack);
  void (*congestion) (tcp_connection_t * tc);
  void (*recovered) (tcp_connection_t * tc);
  void (*init) (tcp_connection_t * tc);
};

#define tcp_fastrecovery_on(tc) (tc)->flags |= TCP_CONN_FAST_RECOVERY
#define tcp_fastrecovery_off(tc) (tc)->flags &= ~TCP_CONN_FAST_RECOVERY
#define tcp_recovery_on(tc) (tc)->flags |= TCP_CONN_RECOVERY
#define tcp_recovery_off(tc) (tc)->flags &= ~TCP_CONN_RECOVERY
#define tcp_in_fastrecovery(tc) ((tc)->flags & TCP_CONN_FAST_RECOVERY)
#define tcp_in_recovery(tc) ((tc)->flags & (TCP_CONN_RECOVERY))
#define tcp_in_slowstart(tc) (tc->cwnd < tc->ssthresh)
#define tcp_fastrecovery_sent_1_smss(tc) ((tc)->flags & TCP_CONN_FR_1_SMSS)
#define tcp_fastrecovery_1_smss_on(tc) ((tc)->flags |= TCP_CONN_FR_1_SMSS)
#define tcp_fastrecovery_1_smss_off(tc) ((tc)->flags &= ~TCP_CONN_FR_1_SMSS)

#define tcp_in_cong_recovery(tc) ((tc)->flags & 		\
	  (TCP_CONN_FAST_RECOVERY | TCP_CONN_RECOVERY))

always_inline void
tcp_cong_recovery_off (tcp_connection_t * tc)
{
  tc->flags &= ~(TCP_CONN_FAST_RECOVERY | TCP_CONN_RECOVERY);
  tcp_fastrecovery_1_smss_off (tc);
}

typedef enum
{
  TCP_IP4,
  TCP_IP6,
  TCP_N_AF,
} tcp_af_t;

typedef enum _tcp_error
{
#define tcp_error(n,s) TCP_ERROR_##n,
#include <vnet/tcp/tcp_error.def>
#undef tcp_error
  TCP_N_ERROR,
} tcp_error_t;

typedef struct _tcp_lookup_dispatch
{
  u8 next, error;
} tcp_lookup_dispatch_t;

typedef struct _tcp_main
{
  /* Per-worker thread tcp connection pools */
  tcp_connection_t **connections;

  /* Pool of listeners. */
  tcp_connection_t *listener_pool;

  /** Dispatch table by state and flags */
  tcp_lookup_dispatch_t dispatch_table[TCP_N_STATES][64];

  u8 log2_tstamp_clocks_per_tick;
  f64 tstamp_ticks_per_clock;
  u32 *time_now;

  /** per-worker tx buffer free lists */
  u32 **tx_buffers;
  /** per-worker tx frames to 4/6 output nodes */
  vlib_frame_t **tx_frames[2];

  /* Per worker-thread timer wheel for connections timers */
  tw_timer_wheel_16t_2w_512sl_t *timer_wheels;

  /* Pool of half-open connections on which we've sent a SYN */
  tcp_connection_t *half_open_connections;
  clib_spinlock_t half_open_lock;

  /* Pool of local TCP endpoints */
  transport_endpoint_t *local_endpoints;

  /* Local endpoints lookup table */
  transport_endpoint_table_t local_endpoints_table;
  clib_spinlock_t local_endpoints_lock;

  /* Congestion control algorithms registered */
  tcp_cc_algorithm_t *cc_algos;

  /* Flag that indicates if stack is on or off */
  u8 is_enabled;

  /** Number of preallocated connections */
  u32 preallocated_connections;
  u32 preallocated_half_open_connections;

  /** Vectors of src addresses. Optional unless one needs > 63K active-opens */
  ip4_address_t *ip4_src_addresses;
  u32 last_v4_address_rotor;
  u32 last_v6_address_rotor;
  ip6_address_t *ip6_src_addresses;

  /** Port allocator random number generator seed */
  u32 port_allocator_seed;

  /** vlib buffer size */
  u32 bytes_per_buffer;
} tcp_main_t;

extern tcp_main_t tcp_main;
extern vlib_node_registration_t tcp4_input_node;
extern vlib_node_registration_t tcp6_input_node;
extern vlib_node_registration_t tcp4_output_node;
extern vlib_node_registration_t tcp6_output_node;

always_inline tcp_main_t *
vnet_get_tcp_main ()
{
  return &tcp_main;
}

always_inline tcp_header_t *
tcp_buffer_hdr (vlib_buffer_t * b)
{
  ASSERT ((signed) b->current_data >= (signed) -VLIB_BUFFER_PRE_DATA_SIZE);
  return (tcp_header_t *) (b->data + b->current_data
			   + vnet_buffer (b)->tcp.hdr_offset);
}

clib_error_t *vnet_tcp_enable_disable (vlib_main_t * vm, u8 is_en);

always_inline tcp_connection_t *
tcp_connection_get (u32 conn_index, u32 thread_index)
{
  if (PREDICT_FALSE
      (pool_is_free_index (tcp_main.connections[thread_index], conn_index)))
    return 0;
  return pool_elt_at_index (tcp_main.connections[thread_index], conn_index);
}

always_inline tcp_connection_t *
tcp_connection_get_if_valid (u32 conn_index, u32 thread_index)
{
  if (tcp_main.connections[thread_index] == 0)
    return 0;
  if (pool_is_free_index (tcp_main.connections[thread_index], conn_index))
    return 0;
  return pool_elt_at_index (tcp_main.connections[thread_index], conn_index);
}

always_inline tcp_connection_t *
tcp_get_connection_from_transport (transport_connection_t * tconn)
{
  return (tcp_connection_t *) tconn;
}

void tcp_connection_close (tcp_connection_t * tc);
void tcp_connection_cleanup (tcp_connection_t * tc);
void tcp_connection_del (tcp_connection_t * tc);
int tcp_half_open_connection_cleanup (tcp_connection_t * tc);
tcp_connection_t *tcp_connection_new (u8 thread_index);
void tcp_connection_reset (tcp_connection_t * tc);

u8 *format_tcp_connection_id (u8 * s, va_list * args);
u8 *format_tcp_connection (u8 * s, va_list * args);
u8 *format_tcp_scoreboard (u8 * s, va_list * args);

u8 *tcp_scoreboard_replay (u8 * s, tcp_connection_t * tc, u8 verbose);

always_inline tcp_connection_t *
tcp_listener_get (u32 tli)
{
  return pool_elt_at_index (tcp_main.listener_pool, tli);
}

always_inline tcp_connection_t *
tcp_half_open_connection_get (u32 conn_index)
{
  tcp_connection_t *tc = 0;
  clib_spinlock_lock_if_init (&tcp_main.half_open_lock);
  if (!pool_is_free_index (tcp_main.half_open_connections, conn_index))
    tc = pool_elt_at_index (tcp_main.half_open_connections, conn_index);
  clib_spinlock_unlock_if_init (&tcp_main.half_open_lock);
  return tc;
}

void tcp_make_ack (tcp_connection_t * ts, vlib_buffer_t * b);
void tcp_make_fin (tcp_connection_t * tc, vlib_buffer_t * b);
void tcp_make_synack (tcp_connection_t * ts, vlib_buffer_t * b);
void tcp_send_reset (tcp_connection_t * tc, vlib_buffer_t * pkt, u8 is_ip4);
void tcp_send_syn (tcp_connection_t * tc);
void tcp_send_fin (tcp_connection_t * tc);
void tcp_init_mss (tcp_connection_t * tc);
void tcp_update_snd_mss (tcp_connection_t * tc);
void tcp_update_rto (tcp_connection_t * tc);
void tcp_flush_frame_to_output (vlib_main_t * vm, u8 thread_index, u8 is_ip4);
void tcp_flush_frames_to_output (u8 thread_index);

always_inline u32
tcp_end_seq (tcp_header_t * th, u32 len)
{
  return th->seq_number + tcp_is_syn (th) + tcp_is_fin (th) + len;
}

/* Modulo arithmetic for TCP sequence numbers */
#define seq_lt(_s1, _s2) ((i32)((_s1)-(_s2)) < 0)
#define seq_leq(_s1, _s2) ((i32)((_s1)-(_s2)) <= 0)
#define seq_gt(_s1, _s2) ((i32)((_s1)-(_s2)) > 0)
#define seq_geq(_s1, _s2) ((i32)((_s1)-(_s2)) >= 0)
#define seq_max(_s1, _s2) (seq_gt((_s1), (_s2)) ? (_s1) : (_s2))

/* Modulo arithmetic for timestamps */
#define timestamp_lt(_t1, _t2) ((i32)((_t1)-(_t2)) < 0)
#define timestamp_leq(_t1, _t2) ((i32)((_t1)-(_t2)) <= 0)

/**
 * Our estimate of the number of bytes that have left the network
 */
always_inline u32
tcp_bytes_out (const tcp_connection_t * tc)
{
  if (tcp_opts_sack_permitted (&tc->rcv_opts))
    return tc->sack_sb.sacked_bytes + tc->sack_sb.lost_bytes;
  else
    return tc->rcv_dupacks * tc->snd_mss;
}

/**
 * Our estimate of the number of bytes in flight (pipe size)
 */
always_inline u32
tcp_flight_size (const tcp_connection_t * tc)
{
  int flight_size;

  flight_size = (int) (tc->snd_una_max - tc->snd_una) - tcp_bytes_out (tc)
    + tc->snd_rxt_bytes;

  if (flight_size < 0)
    {
      if (0)
	clib_warning
	  ("Negative: %u %u %u dupacks %u sacked bytes %u flags %d",
	   tc->snd_una_max - tc->snd_una, tcp_bytes_out (tc),
	   tc->snd_rxt_bytes, tc->rcv_dupacks, tc->sack_sb.sacked_bytes,
	   tc->rcv_opts.flags);
      return 0;
    }

  return flight_size;
}

/**
 * Initial cwnd as per RFC5681
 */
always_inline u32
tcp_initial_cwnd (const tcp_connection_t * tc)
{
  if (tc->snd_mss > 2190)
    return 2 * tc->snd_mss;
  else if (tc->snd_mss > 1095)
    return 3 * tc->snd_mss;
  else
    return 4 * tc->snd_mss;
}

always_inline u32
tcp_loss_wnd (const tcp_connection_t * tc)
{
  return tc->snd_mss;
}

always_inline u32
tcp_available_wnd (const tcp_connection_t * tc)
{
  return clib_min (tc->cwnd, tc->snd_wnd);
}

always_inline u32
tcp_available_snd_space (const tcp_connection_t * tc)
{
  u32 available_wnd = tcp_available_wnd (tc);
  u32 flight_size = tcp_flight_size (tc);

  if (available_wnd <= flight_size)
    return 0;

  return available_wnd - flight_size;
}

always_inline u8
tcp_is_lost_fin (tcp_connection_t * tc)
{
  if ((tc->flags & TCP_CONN_FINSNT) && tc->snd_una_max - tc->snd_una == 1)
    return 1;
  return 0;
}

i32 tcp_rcv_wnd_available (tcp_connection_t * tc);
u32 tcp_snd_space (tcp_connection_t * tc);
void tcp_update_rcv_wnd (tcp_connection_t * tc);

void tcp_retransmit_first_unacked (tcp_connection_t * tc);
void tcp_fast_retransmit_no_sack (tcp_connection_t * tc);
void tcp_fast_retransmit_sack (tcp_connection_t * tc);
void tcp_fast_retransmit (tcp_connection_t * tc);
void tcp_cc_init_congestion (tcp_connection_t * tc);
int tcp_cc_recover (tcp_connection_t * tc);
void tcp_cc_fastrecovery_exit (tcp_connection_t * tc);

fib_node_index_t tcp_lookup_rmt_in_fib (tcp_connection_t * tc);

/* Made public for unit testing only */
void tcp_update_sack_list (tcp_connection_t * tc, u32 start, u32 end);

always_inline u32
tcp_time_now (void)
{
  return tcp_main.time_now[vlib_get_thread_index ()];
}

always_inline u32
tcp_set_time_now (u32 thread_index)
{
  tcp_main.time_now[thread_index] = clib_cpu_time_now ()
    * tcp_main.tstamp_ticks_per_clock;
  return tcp_main.time_now[thread_index];
}

always_inline void
tcp_update_time (f64 now, u32 thread_index)
{
  tcp_set_time_now (thread_index);
  tw_timer_expire_timers_16t_2w_512sl (&tcp_main.timer_wheels[thread_index],
				       now);
  tcp_flush_frames_to_output (thread_index);
}

u32 tcp_push_header (transport_connection_t * tconn, vlib_buffer_t * b);

u32
tcp_prepare_retransmit_segment (tcp_connection_t * tc, u32 offset,
				u32 max_bytes, vlib_buffer_t ** b);

void tcp_connection_timers_init (tcp_connection_t * tc);
void tcp_connection_timers_reset (tcp_connection_t * tc);
void tcp_connection_init_vars (tcp_connection_t * tc);

always_inline void
tcp_connection_force_ack (tcp_connection_t * tc, vlib_buffer_t * b)
{
  /* Reset flags, make sure ack is sent */
  tc->flags = TCP_CONN_SNDACK;
  vnet_buffer (b)->tcp.flags &= ~TCP_BUF_FLAG_DUPACK;
}

always_inline void
tcp_timer_set (tcp_connection_t * tc, u8 timer_id, u32 interval)
{
  ASSERT (tc->c_thread_index == vlib_get_thread_index ());
  tc->timers[timer_id]
    = tw_timer_start_16t_2w_512sl (&tcp_main.timer_wheels[tc->c_thread_index],
				   tc->c_c_index, timer_id, interval);
}

always_inline void
tcp_timer_reset (tcp_connection_t * tc, u8 timer_id)
{
  ASSERT (tc->c_thread_index == vlib_get_thread_index ());
  if (tc->timers[timer_id] == TCP_TIMER_HANDLE_INVALID)
    return;

  tw_timer_stop_16t_2w_512sl (&tcp_main.timer_wheels[tc->c_thread_index],
			      tc->timers[timer_id]);
  tc->timers[timer_id] = TCP_TIMER_HANDLE_INVALID;
}

always_inline void
tcp_timer_update (tcp_connection_t * tc, u8 timer_id, u32 interval)
{
  ASSERT (tc->c_thread_index == vlib_get_thread_index ());
  if (tc->timers[timer_id] != TCP_TIMER_HANDLE_INVALID)
    tw_timer_stop_16t_2w_512sl (&tcp_main.timer_wheels[tc->c_thread_index],
				tc->timers[timer_id]);
  tc->timers[timer_id] =
    tw_timer_start_16t_2w_512sl (&tcp_main.timer_wheels[tc->c_thread_index],
				 tc->c_c_index, timer_id, interval);
}

always_inline void
tcp_retransmit_timer_set (tcp_connection_t * tc)
{
  tcp_timer_set (tc, TCP_TIMER_RETRANSMIT,
		 clib_max (tc->rto * TCP_TO_TIMER_TICK, 1));
}

always_inline void
tcp_retransmit_timer_reset (tcp_connection_t * tc)
{
  tcp_timer_reset (tc, TCP_TIMER_RETRANSMIT);
}

always_inline void
tcp_retransmit_timer_force_update (tcp_connection_t * tc)
{
  tcp_timer_update (tc, TCP_TIMER_RETRANSMIT,
		    clib_max (tc->rto * TCP_TO_TIMER_TICK, 1));
}

always_inline void
tcp_persist_timer_set (tcp_connection_t * tc)
{
  /* Reuse RTO. It's backed off in handler */
  tcp_timer_set (tc, TCP_TIMER_PERSIST,
		 clib_max (tc->rto * TCP_TO_TIMER_TICK,
			   TCP_TIMER_PERSIST_MIN));
}

always_inline void
tcp_persist_timer_update (tcp_connection_t * tc)
{
  tcp_timer_update (tc, TCP_TIMER_PERSIST,
		    clib_max (tc->rto * TCP_TO_TIMER_TICK,
			      TCP_TIMER_PERSIST_MIN));
}

always_inline void
tcp_persist_timer_reset (tcp_connection_t * tc)
{
  tcp_timer_reset (tc, TCP_TIMER_PERSIST);
}

always_inline void
tcp_retransmit_timer_update (tcp_connection_t * tc)
{
  if (tc->snd_una == tc->snd_una_max)
    {
      tcp_retransmit_timer_reset (tc);
      if (tc->snd_wnd < tc->snd_mss)
	tcp_persist_timer_set (tc);
    }
  else
    tcp_timer_update (tc, TCP_TIMER_RETRANSMIT,
		      clib_max (tc->rto * TCP_TO_TIMER_TICK, 1));
}

always_inline u8
tcp_timer_is_active (tcp_connection_t * tc, tcp_timers_e timer)
{
  return tc->timers[timer] != TCP_TIMER_HANDLE_INVALID;
}

#define tcp_validate_txf_size(_tc, _a) 					\
  ASSERT(_tc->state != TCP_STATE_ESTABLISHED 				\
	 || stream_session_tx_fifo_max_dequeue (&_tc->connection) >= _a)

void
scoreboard_remove_hole (sack_scoreboard_t * sb,
			sack_scoreboard_hole_t * hole);
void scoreboard_update_lost (tcp_connection_t * tc, sack_scoreboard_t * sb);
sack_scoreboard_hole_t *scoreboard_insert_hole (sack_scoreboard_t * sb,
						u32 prev_index, u32 start,
						u32 end);
sack_scoreboard_hole_t *scoreboard_next_rxt_hole (sack_scoreboard_t * sb,
						  sack_scoreboard_hole_t *
						  start, u8 have_sent_1_smss,
						  u8 * can_rescue,
						  u8 * snd_limited);
void scoreboard_init_high_rxt (sack_scoreboard_t * sb, u32 seq);

always_inline sack_scoreboard_hole_t *
scoreboard_get_hole (sack_scoreboard_t * sb, u32 index)
{
  if (index != TCP_INVALID_SACK_HOLE_INDEX)
    return pool_elt_at_index (sb->holes, index);
  return 0;
}

always_inline sack_scoreboard_hole_t *
scoreboard_next_hole (sack_scoreboard_t * sb, sack_scoreboard_hole_t * hole)
{
  if (hole->next != TCP_INVALID_SACK_HOLE_INDEX)
    return pool_elt_at_index (sb->holes, hole->next);
  return 0;
}

always_inline sack_scoreboard_hole_t *
scoreboard_prev_hole (sack_scoreboard_t * sb, sack_scoreboard_hole_t * hole)
{
  if (hole->prev != TCP_INVALID_SACK_HOLE_INDEX)
    return pool_elt_at_index (sb->holes, hole->prev);
  return 0;
}

always_inline sack_scoreboard_hole_t *
scoreboard_first_hole (sack_scoreboard_t * sb)
{
  if (sb->head != TCP_INVALID_SACK_HOLE_INDEX)
    return pool_elt_at_index (sb->holes, sb->head);
  return 0;
}

always_inline sack_scoreboard_hole_t *
scoreboard_last_hole (sack_scoreboard_t * sb)
{
  if (sb->tail != TCP_INVALID_SACK_HOLE_INDEX)
    return pool_elt_at_index (sb->holes, sb->tail);
  return 0;
}

always_inline void
scoreboard_clear (sack_scoreboard_t * sb)
{
  sack_scoreboard_hole_t *hole;
  while ((hole = scoreboard_first_hole (sb)))
    {
      scoreboard_remove_hole (sb, hole);
    }
  ASSERT (sb->head == sb->tail && sb->head == TCP_INVALID_SACK_HOLE_INDEX);
  ASSERT (pool_elts (sb->holes) == 0);
  sb->sacked_bytes = 0;
  sb->last_sacked_bytes = 0;
  sb->last_bytes_delivered = 0;
  sb->snd_una_adv = 0;
  sb->high_sacked = 0;
  sb->high_rxt = 0;
  sb->lost_bytes = 0;
  sb->cur_rxt_hole = TCP_INVALID_SACK_HOLE_INDEX;
}

always_inline u32
scoreboard_hole_bytes (sack_scoreboard_hole_t * hole)
{
  return hole->end - hole->start;
}

always_inline u32
scoreboard_hole_index (sack_scoreboard_t * sb, sack_scoreboard_hole_t * hole)
{
  ASSERT (!pool_is_free_index (sb->holes, hole - sb->holes));
  return hole - sb->holes;
}

always_inline void
scoreboard_init (sack_scoreboard_t * sb)
{
  sb->head = TCP_INVALID_SACK_HOLE_INDEX;
  sb->tail = TCP_INVALID_SACK_HOLE_INDEX;
  sb->cur_rxt_hole = TCP_INVALID_SACK_HOLE_INDEX;
}

void tcp_rcv_sacks (tcp_connection_t * tc, u32 ack);

always_inline void
tcp_cc_algo_register (tcp_cc_algorithm_type_e type,
		      const tcp_cc_algorithm_t * vft)
{
  tcp_main_t *tm = vnet_get_tcp_main ();
  vec_validate (tm->cc_algos, type);

  tm->cc_algos[type] = *vft;
}

always_inline tcp_cc_algorithm_t *
tcp_cc_algo_get (tcp_cc_algorithm_type_e type)
{
  tcp_main_t *tm = vnet_get_tcp_main ();
  return &tm->cc_algos[type];
}

void tcp_cc_init (tcp_connection_t * tc);

/**
 * Push TCP header to buffer
 *
 * @param vm - vlib_main
 * @param b - buffer to write the header to
 * @param sp_net - source port net order
 * @param dp_net - destination port net order
 * @param seq - sequence number net order
 * @param ack - ack number net order
 * @param tcp_hdr_opts_len - header and options length in bytes
 * @param flags - header flags
 * @param wnd - window size
 *
 * @return - pointer to start of TCP header
 */
always_inline void *
vlib_buffer_push_tcp_net_order (vlib_buffer_t * b, u16 sp, u16 dp, u32 seq,
				u32 ack, u8 tcp_hdr_opts_len, u8 flags,
				u16 wnd)
{
  tcp_header_t *th;

  th = vlib_buffer_push_uninit (b, tcp_hdr_opts_len);

  th->src_port = sp;
  th->dst_port = dp;
  th->seq_number = seq;
  th->ack_number = ack;
  th->data_offset_and_reserved = (tcp_hdr_opts_len >> 2) << 4;
  th->flags = flags;
  th->window = wnd;
  th->checksum = 0;
  th->urgent_pointer = 0;
  return th;
}

/**
 * Push TCP header to buffer
 *
 * @param b - buffer to write the header to
 * @param sp_net - source port net order
 * @param dp_net - destination port net order
 * @param seq - sequence number host order
 * @param ack - ack number host order
 * @param tcp_hdr_opts_len - header and options length in bytes
 * @param flags - header flags
 * @param wnd - window size
 *
 * @return - pointer to start of TCP header
 */
always_inline void *
vlib_buffer_push_tcp (vlib_buffer_t * b, u16 sp_net, u16 dp_net, u32 seq,
		      u32 ack, u8 tcp_hdr_opts_len, u8 flags, u16 wnd)
{
  return vlib_buffer_push_tcp_net_order (b, sp_net, dp_net,
					 clib_host_to_net_u32 (seq),
					 clib_host_to_net_u32 (ack),
					 tcp_hdr_opts_len, flags,
					 clib_host_to_net_u16 (wnd));
}

#endif /* _vnet_tcp_h_ */

/*
 * fd.io coding-style-patch-verification: ON
 *
 * Local Variables:
 * eval: (c-set-style "gnu")
 * End:
 */