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1/*
2 * INET An implementation of the TCP/IP protocol suite for the LINUX
3 * operating system. INET is implemented using the BSD Socket
4 * interface as the means of communication with the user level.
5 *
6 * Definitions for the TCP module.
7 *
8 * Version: @(#)tcp.h 1.0.5 05/23/93
9 *
10 * Authors: Ross Biro
11 * Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
12 *
13 * This program is free software; you can redistribute it and/or
14 * modify it under the terms of the GNU General Public License
15 * as published by the Free Software Foundation; either version
16 * 2 of the License, or (at your option) any later version.
17 */
18#ifndef _TCP_H
19#define _TCP_H
20
21#define TCP_DEBUG 1
22#define FASTRETRANS_DEBUG 1
23
24#include <linux/list.h>
25#include <linux/tcp.h>
26#include <linux/slab.h>
27#include <linux/cache.h>
28#include <linux/percpu.h>
29#include <linux/skbuff.h>
30#include <linux/dmaengine.h>
31#include <linux/crypto.h>
32#include <linux/cryptohash.h>
33#include <linux/kref.h>
34
35#include <net/inet_connection_sock.h>
36#include <net/inet_timewait_sock.h>
37#include <net/inet_hashtables.h>
38#include <net/checksum.h>
39#include <net/request_sock.h>
40#include <net/sock.h>
41#include <net/snmp.h>
42#include <net/ip.h>
43#include <net/tcp_states.h>
44#include <net/inet_ecn.h>
45#include <net/dst.h>
46
47#include <linux/seq_file.h>
48
49extern struct inet_hashinfo tcp_hashinfo;
50
51extern struct percpu_counter tcp_orphan_count;
52extern void tcp_time_wait(struct sock *sk, int state, int timeo);
53
54#define MAX_TCP_HEADER (128 + MAX_HEADER)
55#define MAX_TCP_OPTION_SPACE 40
56
57/*
58 * Never offer a window over 32767 without using window scaling. Some
59 * poor stacks do signed 16bit maths!
60 */
61#define MAX_TCP_WINDOW 32767U
62
63/* Offer an initial receive window of 10 mss. */
64#define TCP_DEFAULT_INIT_RCVWND 10
65
66/* Minimal accepted MSS. It is (60+60+8) - (20+20). */
67#define TCP_MIN_MSS 88U
68
69/* The least MTU to use for probing */
70#define TCP_BASE_MSS 512
71
72/* After receiving this amount of duplicate ACKs fast retransmit starts. */
73#define TCP_FASTRETRANS_THRESH 3
74
75/* Maximal reordering. */
76#define TCP_MAX_REORDERING 127
77
78/* Maximal number of ACKs sent quickly to accelerate slow-start. */
79#define TCP_MAX_QUICKACKS 16U
80
81/* urg_data states */
82#define TCP_URG_VALID 0x0100
83#define TCP_URG_NOTYET 0x0200
84#define TCP_URG_READ 0x0400
85
86#define TCP_RETR1 3 /*
87 * This is how many retries it does before it
88 * tries to figure out if the gateway is
89 * down. Minimal RFC value is 3; it corresponds
90 * to ~3sec-8min depending on RTO.
91 */
92
93#define TCP_RETR2 15 /*
94 * This should take at least
95 * 90 minutes to time out.
96 * RFC1122 says that the limit is 100 sec.
97 * 15 is ~13-30min depending on RTO.
98 */
99
100#define TCP_SYN_RETRIES 5 /* number of times to retry active opening a
101 * connection: ~180sec is RFC minimum */
102
103#define TCP_SYNACK_RETRIES 5 /* number of times to retry passive opening a
104 * connection: ~180sec is RFC minimum */
105
106#define TCP_TIMEWAIT_LEN (60*HZ) /* how long to wait to destroy TIME-WAIT
107 * state, about 60 seconds */
108#define TCP_FIN_TIMEOUT TCP_TIMEWAIT_LEN
109 /* BSD style FIN_WAIT2 deadlock breaker.
110 * It used to be 3min, new value is 60sec,
111 * to combine FIN-WAIT-2 timeout with
112 * TIME-WAIT timer.
113 */
114
115#define TCP_DELACK_MAX ((unsigned)(HZ/5)) /* maximal time to delay before sending an ACK */
116#if HZ >= 100
117#define TCP_DELACK_MIN ((unsigned)(HZ/25)) /* minimal time to delay before sending an ACK */
118#define TCP_ATO_MIN ((unsigned)(HZ/25))
119#else
120#define TCP_DELACK_MIN 4U
121#define TCP_ATO_MIN 4U
122#endif
123#define TCP_RTO_MAX ((unsigned)(120*HZ))
124#define TCP_RTO_MIN ((unsigned)(HZ/5))
125#define TCP_TIMEOUT_INIT ((unsigned)(1*HZ)) /* RFC2988bis initial RTO value */
126#define TCP_TIMEOUT_FALLBACK ((unsigned)(3*HZ)) /* RFC 1122 initial RTO value, now
127 * used as a fallback RTO for the
128 * initial data transmission if no
129 * valid RTT sample has been acquired,
130 * most likely due to retrans in 3WHS.
131 */
132
133#define TCP_RESOURCE_PROBE_INTERVAL ((unsigned)(HZ/2U)) /* Maximal interval between probes
134 * for local resources.
135 */
136
137#define TCP_KEEPALIVE_TIME (120*60*HZ) /* two hours */
138#define TCP_KEEPALIVE_PROBES 9 /* Max of 9 keepalive probes */
139#define TCP_KEEPALIVE_INTVL (75*HZ)
140
141#define MAX_TCP_KEEPIDLE 32767
142#define MAX_TCP_KEEPINTVL 32767
143#define MAX_TCP_KEEPCNT 127
144#define MAX_TCP_SYNCNT 127
145
146#define TCP_SYNQ_INTERVAL (HZ/5) /* Period of SYNACK timer */
147
148#define TCP_PAWS_24DAYS (60 * 60 * 24 * 24)
149#define TCP_PAWS_MSL 60 /* Per-host timestamps are invalidated
150 * after this time. It should be equal
151 * (or greater than) TCP_TIMEWAIT_LEN
152 * to provide reliability equal to one
153 * provided by timewait state.
154 */
155#define TCP_PAWS_WINDOW 1 /* Replay window for per-host
156 * timestamps. It must be less than
157 * minimal timewait lifetime.
158 */
159/*
160 * TCP option
161 */
162
163#define TCPOPT_NOP 1 /* Padding */
164#define TCPOPT_EOL 0 /* End of options */
165#define TCPOPT_MSS 2 /* Segment size negotiating */
166#define TCPOPT_WINDOW 3 /* Window scaling */
167#define TCPOPT_SACK_PERM 4 /* SACK Permitted */
168#define TCPOPT_SACK 5 /* SACK Block */
169#define TCPOPT_TIMESTAMP 8 /* Better RTT estimations/PAWS */
170#define TCPOPT_MD5SIG 19 /* MD5 Signature (RFC2385) */
171#define TCPOPT_COOKIE 253 /* Cookie extension (experimental) */
172
173/*
174 * TCP option lengths
175 */
176
177#define TCPOLEN_MSS 4
178#define TCPOLEN_WINDOW 3
179#define TCPOLEN_SACK_PERM 2
180#define TCPOLEN_TIMESTAMP 10
181#define TCPOLEN_MD5SIG 18
182#define TCPOLEN_COOKIE_BASE 2 /* Cookie-less header extension */
183#define TCPOLEN_COOKIE_PAIR 3 /* Cookie pair header extension */
184#define TCPOLEN_COOKIE_MIN (TCPOLEN_COOKIE_BASE+TCP_COOKIE_MIN)
185#define TCPOLEN_COOKIE_MAX (TCPOLEN_COOKIE_BASE+TCP_COOKIE_MAX)
186
187/* But this is what stacks really send out. */
188#define TCPOLEN_TSTAMP_ALIGNED 12
189#define TCPOLEN_WSCALE_ALIGNED 4
190#define TCPOLEN_SACKPERM_ALIGNED 4
191#define TCPOLEN_SACK_BASE 2
192#define TCPOLEN_SACK_BASE_ALIGNED 4
193#define TCPOLEN_SACK_PERBLOCK 8
194#define TCPOLEN_MD5SIG_ALIGNED 20
195#define TCPOLEN_MSS_ALIGNED 4
196
197/* Flags in tp->nonagle */
198#define TCP_NAGLE_OFF 1 /* Nagle's algo is disabled */
199#define TCP_NAGLE_CORK 2 /* Socket is corked */
200#define TCP_NAGLE_PUSH 4 /* Cork is overridden for already queued data */
201
202/* TCP thin-stream limits */
203#define TCP_THIN_LINEAR_RETRIES 6 /* After 6 linear retries, do exp. backoff */
204
205/* TCP initial congestion window as per draft-hkchu-tcpm-initcwnd-01 */
206#define TCP_INIT_CWND 10
207
208extern struct inet_timewait_death_row tcp_death_row;
209
210/* sysctl variables for tcp */
211extern int sysctl_tcp_timestamps;
212extern int sysctl_tcp_window_scaling;
213extern int sysctl_tcp_sack;
214extern int sysctl_tcp_fin_timeout;
215extern int sysctl_tcp_keepalive_time;
216extern int sysctl_tcp_keepalive_probes;
217extern int sysctl_tcp_keepalive_intvl;
218extern int sysctl_tcp_syn_retries;
219extern int sysctl_tcp_synack_retries;
220extern int sysctl_tcp_retries1;
221extern int sysctl_tcp_retries2;
222extern int sysctl_tcp_orphan_retries;
223extern int sysctl_tcp_syncookies;
224extern int sysctl_tcp_retrans_collapse;
225extern int sysctl_tcp_stdurg;
226extern int sysctl_tcp_rfc1337;
227extern int sysctl_tcp_abort_on_overflow;
228extern int sysctl_tcp_max_orphans;
229extern int sysctl_tcp_fack;
230extern int sysctl_tcp_reordering;
231extern int sysctl_tcp_ecn;
232extern int sysctl_tcp_dsack;
233extern long sysctl_tcp_mem[3];
234extern int sysctl_tcp_wmem[3];
235extern int sysctl_tcp_rmem[3];
236extern int sysctl_tcp_app_win;
237extern int sysctl_tcp_adv_win_scale;
238extern int sysctl_tcp_tw_reuse;
239extern int sysctl_tcp_frto;
240extern int sysctl_tcp_frto_response;
241extern int sysctl_tcp_low_latency;
242extern int sysctl_tcp_dma_copybreak;
243extern int sysctl_tcp_nometrics_save;
244extern int sysctl_tcp_moderate_rcvbuf;
245extern int sysctl_tcp_tso_win_divisor;
246extern int sysctl_tcp_abc;
247extern int sysctl_tcp_mtu_probing;
248extern int sysctl_tcp_base_mss;
249extern int sysctl_tcp_workaround_signed_windows;
250extern int sysctl_tcp_slow_start_after_idle;
251extern int sysctl_tcp_max_ssthresh;
252extern int sysctl_tcp_cookie_size;
253extern int sysctl_tcp_thin_linear_timeouts;
254extern int sysctl_tcp_thin_dupack;
255
256extern atomic_long_t tcp_memory_allocated;
257extern struct percpu_counter tcp_sockets_allocated;
258extern int tcp_memory_pressure;
259
260/*
261 * The next routines deal with comparing 32 bit unsigned ints
262 * and worry about wraparound (automatic with unsigned arithmetic).
263 */
264
265static inline int before(__u32 seq1, __u32 seq2)
266{
267 return (__s32)(seq1-seq2) < 0;
268}
269#define after(seq2, seq1) before(seq1, seq2)
270
271/* is s2<=s1<=s3 ? */
272static inline int between(__u32 seq1, __u32 seq2, __u32 seq3)
273{
274 return seq3 - seq2 >= seq1 - seq2;
275}
276
277static inline bool tcp_too_many_orphans(struct sock *sk, int shift)
278{
279 struct percpu_counter *ocp = sk->sk_prot->orphan_count;
280 int orphans = percpu_counter_read_positive(ocp);
281
282 if (orphans << shift > sysctl_tcp_max_orphans) {
283 orphans = percpu_counter_sum_positive(ocp);
284 if (orphans << shift > sysctl_tcp_max_orphans)
285 return true;
286 }
287
288 if (sk->sk_wmem_queued > SOCK_MIN_SNDBUF &&
289 atomic_long_read(&tcp_memory_allocated) > sysctl_tcp_mem[2])
290 return true;
291 return false;
292}
293
294/* syncookies: remember time of last synqueue overflow */
295static inline void tcp_synq_overflow(struct sock *sk)
296{
297 tcp_sk(sk)->rx_opt.ts_recent_stamp = jiffies;
298}
299
300/* syncookies: no recent synqueue overflow on this listening socket? */
301static inline int tcp_synq_no_recent_overflow(const struct sock *sk)
302{
303 unsigned long last_overflow = tcp_sk(sk)->rx_opt.ts_recent_stamp;
304 return time_after(jiffies, last_overflow + TCP_TIMEOUT_FALLBACK);
305}
306
307extern struct proto tcp_prot;
308
309#define TCP_INC_STATS(net, field) SNMP_INC_STATS((net)->mib.tcp_statistics, field)
310#define TCP_INC_STATS_BH(net, field) SNMP_INC_STATS_BH((net)->mib.tcp_statistics, field)
311#define TCP_DEC_STATS(net, field) SNMP_DEC_STATS((net)->mib.tcp_statistics, field)
312#define TCP_ADD_STATS_USER(net, field, val) SNMP_ADD_STATS_USER((net)->mib.tcp_statistics, field, val)
313#define TCP_ADD_STATS(net, field, val) SNMP_ADD_STATS((net)->mib.tcp_statistics, field, val)
314
315extern void tcp_v4_err(struct sk_buff *skb, u32);
316
317extern void tcp_shutdown (struct sock *sk, int how);
318
319extern int tcp_v4_rcv(struct sk_buff *skb);
320
321extern struct inet_peer *tcp_v4_get_peer(struct sock *sk, bool *release_it);
322extern void *tcp_v4_tw_get_peer(struct sock *sk);
323extern int tcp_v4_tw_remember_stamp(struct inet_timewait_sock *tw);
324extern int tcp_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
325 size_t size);
326extern int tcp_sendpage(struct sock *sk, struct page *page, int offset,
327 size_t size, int flags);
328extern int tcp_ioctl(struct sock *sk, int cmd, unsigned long arg);
329extern int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb,
330 struct tcphdr *th, unsigned len);
331extern int tcp_rcv_established(struct sock *sk, struct sk_buff *skb,
332 struct tcphdr *th, unsigned len);
333extern void tcp_rcv_space_adjust(struct sock *sk);
334extern void tcp_cleanup_rbuf(struct sock *sk, int copied);
335extern int tcp_twsk_unique(struct sock *sk, struct sock *sktw, void *twp);
336extern void tcp_twsk_destructor(struct sock *sk);
337extern ssize_t tcp_splice_read(struct socket *sk, loff_t *ppos,
338 struct pipe_inode_info *pipe, size_t len,
339 unsigned int flags);
340
341static inline void tcp_dec_quickack_mode(struct sock *sk,
342 const unsigned int pkts)
343{
344 struct inet_connection_sock *icsk = inet_csk(sk);
345
346 if (icsk->icsk_ack.quick) {
347 if (pkts >= icsk->icsk_ack.quick) {
348 icsk->icsk_ack.quick = 0;
349 /* Leaving quickack mode we deflate ATO. */
350 icsk->icsk_ack.ato = TCP_ATO_MIN;
351 } else
352 icsk->icsk_ack.quick -= pkts;
353 }
354}
355
356#define TCP_ECN_OK 1
357#define TCP_ECN_QUEUE_CWR 2
358#define TCP_ECN_DEMAND_CWR 4
359
360static __inline__ void
361TCP_ECN_create_request(struct request_sock *req, struct tcphdr *th)
362{
363 if (sysctl_tcp_ecn && th->ece && th->cwr)
364 inet_rsk(req)->ecn_ok = 1;
365}
366
367enum tcp_tw_status {
368 TCP_TW_SUCCESS = 0,
369 TCP_TW_RST = 1,
370 TCP_TW_ACK = 2,
371 TCP_TW_SYN = 3
372};
373
374
375extern enum tcp_tw_status tcp_timewait_state_process(struct inet_timewait_sock *tw,
376 struct sk_buff *skb,
377 const struct tcphdr *th);
378extern struct sock * tcp_check_req(struct sock *sk,struct sk_buff *skb,
379 struct request_sock *req,
380 struct request_sock **prev);
381extern int tcp_child_process(struct sock *parent, struct sock *child,
382 struct sk_buff *skb);
383extern int tcp_use_frto(struct sock *sk);
384extern void tcp_enter_frto(struct sock *sk);
385extern void tcp_enter_loss(struct sock *sk, int how);
386extern void tcp_clear_retrans(struct tcp_sock *tp);
387extern void tcp_update_metrics(struct sock *sk);
388extern void tcp_close(struct sock *sk, long timeout);
389extern unsigned int tcp_poll(struct file * file, struct socket *sock,
390 struct poll_table_struct *wait);
391extern int tcp_getsockopt(struct sock *sk, int level, int optname,
392 char __user *optval, int __user *optlen);
393extern int tcp_setsockopt(struct sock *sk, int level, int optname,
394 char __user *optval, unsigned int optlen);
395extern int compat_tcp_getsockopt(struct sock *sk, int level, int optname,
396 char __user *optval, int __user *optlen);
397extern int compat_tcp_setsockopt(struct sock *sk, int level, int optname,
398 char __user *optval, unsigned int optlen);
399extern void tcp_set_keepalive(struct sock *sk, int val);
400extern void tcp_syn_ack_timeout(struct sock *sk, struct request_sock *req);
401extern int tcp_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
402 size_t len, int nonblock, int flags, int *addr_len);
403extern void tcp_parse_options(struct sk_buff *skb,
404 struct tcp_options_received *opt_rx, u8 **hvpp,
405 int estab);
406extern u8 *tcp_parse_md5sig_option(struct tcphdr *th);
407
408/*
409 * TCP v4 functions exported for the inet6 API
410 */
411
412extern void tcp_v4_send_check(struct sock *sk, struct sk_buff *skb);
413extern int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb);
414extern struct sock * tcp_create_openreq_child(struct sock *sk,
415 struct request_sock *req,
416 struct sk_buff *skb);
417extern struct sock * tcp_v4_syn_recv_sock(struct sock *sk, struct sk_buff *skb,
418 struct request_sock *req,
419 struct dst_entry *dst);
420extern int tcp_v4_do_rcv(struct sock *sk, struct sk_buff *skb);
421extern int tcp_v4_connect(struct sock *sk, struct sockaddr *uaddr,
422 int addr_len);
423extern int tcp_connect(struct sock *sk);
424extern struct sk_buff * tcp_make_synack(struct sock *sk, struct dst_entry *dst,
425 struct request_sock *req,
426 struct request_values *rvp);
427extern int tcp_disconnect(struct sock *sk, int flags);
428
429
430/* From syncookies.c */
431extern __u32 syncookie_secret[2][16-4+SHA_DIGEST_WORDS];
432extern struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb,
433 struct ip_options *opt);
434#ifdef CONFIG_SYN_COOKIES
435extern __u32 cookie_v4_init_sequence(struct sock *sk, struct sk_buff *skb,
436 __u16 *mss);
437#else
438static inline __u32 cookie_v4_init_sequence(struct sock *sk,
439 struct sk_buff *skb,
440 __u16 *mss)
441{
442 return 0;
443}
444#endif
445
446extern __u32 cookie_init_timestamp(struct request_sock *req);
447extern bool cookie_check_timestamp(struct tcp_options_received *opt, bool *);
448
449/* From net/ipv6/syncookies.c */
450extern struct sock *cookie_v6_check(struct sock *sk, struct sk_buff *skb);
451#ifdef CONFIG_SYN_COOKIES
452extern __u32 cookie_v6_init_sequence(struct sock *sk, struct sk_buff *skb,
453 __u16 *mss);
454#else
455static inline __u32 cookie_v6_init_sequence(struct sock *sk,
456 struct sk_buff *skb,
457 __u16 *mss)
458{
459 return 0;
460}
461#endif
462/* tcp_output.c */
463
464extern void __tcp_push_pending_frames(struct sock *sk, unsigned int cur_mss,
465 int nonagle);
466extern int tcp_may_send_now(struct sock *sk);
467extern int tcp_retransmit_skb(struct sock *, struct sk_buff *);
468extern void tcp_retransmit_timer(struct sock *sk);
469extern void tcp_xmit_retransmit_queue(struct sock *);
470extern void tcp_simple_retransmit(struct sock *);
471extern int tcp_trim_head(struct sock *, struct sk_buff *, u32);
472extern int tcp_fragment(struct sock *, struct sk_buff *, u32, unsigned int);
473
474extern void tcp_send_probe0(struct sock *);
475extern void tcp_send_partial(struct sock *);
476extern int tcp_write_wakeup(struct sock *);
477extern void tcp_send_fin(struct sock *sk);
478extern void tcp_send_active_reset(struct sock *sk, gfp_t priority);
479extern int tcp_send_synack(struct sock *);
480extern int tcp_syn_flood_action(struct sock *sk,
481 const struct sk_buff *skb,
482 const char *proto);
483extern void tcp_push_one(struct sock *, unsigned int mss_now);
484extern void tcp_send_ack(struct sock *sk);
485extern void tcp_send_delayed_ack(struct sock *sk);
486
487/* tcp_input.c */
488extern void tcp_cwnd_application_limited(struct sock *sk);
489
490/* tcp_timer.c */
491extern void tcp_init_xmit_timers(struct sock *);
492static inline void tcp_clear_xmit_timers(struct sock *sk)
493{
494 inet_csk_clear_xmit_timers(sk);
495}
496
497extern unsigned int tcp_sync_mss(struct sock *sk, u32 pmtu);
498extern unsigned int tcp_current_mss(struct sock *sk);
499
500/* Bound MSS / TSO packet size with the half of the window */
501static inline int tcp_bound_to_half_wnd(struct tcp_sock *tp, int pktsize)
502{
503 int cutoff;
504
505 /* When peer uses tiny windows, there is no use in packetizing
506 * to sub-MSS pieces for the sake of SWS or making sure there
507 * are enough packets in the pipe for fast recovery.
508 *
509 * On the other hand, for extremely large MSS devices, handling
510 * smaller than MSS windows in this way does make sense.
511 */
512 if (tp->max_window >= 512)
513 cutoff = (tp->max_window >> 1);
514 else
515 cutoff = tp->max_window;
516
517 if (cutoff && pktsize > cutoff)
518 return max_t(int, cutoff, 68U - tp->tcp_header_len);
519 else
520 return pktsize;
521}
522
523/* tcp.c */
524extern void tcp_get_info(struct sock *, struct tcp_info *);
525
526/* Read 'sendfile()'-style from a TCP socket */
527typedef int (*sk_read_actor_t)(read_descriptor_t *, struct sk_buff *,
528 unsigned int, size_t);
529extern int tcp_read_sock(struct sock *sk, read_descriptor_t *desc,
530 sk_read_actor_t recv_actor);
531
532extern void tcp_initialize_rcv_mss(struct sock *sk);
533
534extern int tcp_mtu_to_mss(struct sock *sk, int pmtu);
535extern int tcp_mss_to_mtu(struct sock *sk, int mss);
536extern void tcp_mtup_init(struct sock *sk);
537extern void tcp_valid_rtt_meas(struct sock *sk, u32 seq_rtt);
538
539static inline void tcp_bound_rto(const struct sock *sk)
540{
541 if (inet_csk(sk)->icsk_rto > TCP_RTO_MAX)
542 inet_csk(sk)->icsk_rto = TCP_RTO_MAX;
543}
544
545static inline u32 __tcp_set_rto(const struct tcp_sock *tp)
546{
547 return (tp->srtt >> 3) + tp->rttvar;
548}
549
550static inline void __tcp_fast_path_on(struct tcp_sock *tp, u32 snd_wnd)
551{
552 tp->pred_flags = htonl((tp->tcp_header_len << 26) |
553 ntohl(TCP_FLAG_ACK) |
554 snd_wnd);
555}
556
557static inline void tcp_fast_path_on(struct tcp_sock *tp)
558{
559 __tcp_fast_path_on(tp, tp->snd_wnd >> tp->rx_opt.snd_wscale);
560}
561
562static inline void tcp_fast_path_check(struct sock *sk)
563{
564 struct tcp_sock *tp = tcp_sk(sk);
565
566 if (skb_queue_empty(&tp->out_of_order_queue) &&
567 tp->rcv_wnd &&
568 atomic_read(&sk->sk_rmem_alloc) < sk->sk_rcvbuf &&
569 !tp->urg_data)
570 tcp_fast_path_on(tp);
571}
572
573/* Compute the actual rto_min value */
574static inline u32 tcp_rto_min(struct sock *sk)
575{
576 struct dst_entry *dst = __sk_dst_get(sk);
577 u32 rto_min = TCP_RTO_MIN;
578
579 if (dst && dst_metric_locked(dst, RTAX_RTO_MIN))
580 rto_min = dst_metric_rtt(dst, RTAX_RTO_MIN);
581 return rto_min;
582}
583
584/* Compute the actual receive window we are currently advertising.
585 * Rcv_nxt can be after the window if our peer push more data
586 * than the offered window.
587 */
588static inline u32 tcp_receive_window(const struct tcp_sock *tp)
589{
590 s32 win = tp->rcv_wup + tp->rcv_wnd - tp->rcv_nxt;
591
592 if (win < 0)
593 win = 0;
594 return (u32) win;
595}
596
597/* Choose a new window, without checks for shrinking, and without
598 * scaling applied to the result. The caller does these things
599 * if necessary. This is a "raw" window selection.
600 */
601extern u32 __tcp_select_window(struct sock *sk);
602
603/* TCP timestamps are only 32-bits, this causes a slight
604 * complication on 64-bit systems since we store a snapshot
605 * of jiffies in the buffer control blocks below. We decided
606 * to use only the low 32-bits of jiffies and hide the ugly
607 * casts with the following macro.
608 */
609#define tcp_time_stamp ((__u32)(jiffies))
610
611#define tcp_flag_byte(th) (((u_int8_t *)th)[13])
612
613#define TCPHDR_FIN 0x01
614#define TCPHDR_SYN 0x02
615#define TCPHDR_RST 0x04
616#define TCPHDR_PSH 0x08
617#define TCPHDR_ACK 0x10
618#define TCPHDR_URG 0x20
619#define TCPHDR_ECE 0x40
620#define TCPHDR_CWR 0x80
621
622/* This is what the send packet queuing engine uses to pass
623 * TCP per-packet control information to the transmission code.
624 * We also store the host-order sequence numbers in here too.
625 * This is 44 bytes if IPV6 is enabled.
626 * If this grows please adjust skbuff.h:skbuff->cb[xxx] size appropriately.
627 */
628struct tcp_skb_cb {
629 union {
630 struct inet_skb_parm h4;
631#if defined(CONFIG_IPV6) || defined (CONFIG_IPV6_MODULE)
632 struct inet6_skb_parm h6;
633#endif
634 } header; /* For incoming frames */
635 __u32 seq; /* Starting sequence number */
636 __u32 end_seq; /* SEQ + FIN + SYN + datalen */
637 __u32 when; /* used to compute rtt's */
638 __u8 flags; /* TCP header flags. */
639 __u8 sacked; /* State flags for SACK/FACK. */
640#define TCPCB_SACKED_ACKED 0x01 /* SKB ACK'd by a SACK block */
641#define TCPCB_SACKED_RETRANS 0x02 /* SKB retransmitted */
642#define TCPCB_LOST 0x04 /* SKB is lost */
643#define TCPCB_TAGBITS 0x07 /* All tag bits */
644
645#define TCPCB_EVER_RETRANS 0x80 /* Ever retransmitted frame */
646#define TCPCB_RETRANS (TCPCB_SACKED_RETRANS|TCPCB_EVER_RETRANS)
647
648 __u32 ack_seq; /* Sequence number ACK'd */
649};
650
651#define TCP_SKB_CB(__skb) ((struct tcp_skb_cb *)&((__skb)->cb[0]))
652
653/* Due to TSO, an SKB can be composed of multiple actual
654 * packets. To keep these tracked properly, we use this.
655 */
656static inline int tcp_skb_pcount(const struct sk_buff *skb)
657{
658 return skb_shinfo(skb)->gso_segs;
659}
660
661/* This is valid iff tcp_skb_pcount() > 1. */
662static inline int tcp_skb_mss(const struct sk_buff *skb)
663{
664 return skb_shinfo(skb)->gso_size;
665}
666
667/* Events passed to congestion control interface */
668enum tcp_ca_event {
669 CA_EVENT_TX_START, /* first transmit when no packets in flight */
670 CA_EVENT_CWND_RESTART, /* congestion window restart */
671 CA_EVENT_COMPLETE_CWR, /* end of congestion recovery */
672 CA_EVENT_FRTO, /* fast recovery timeout */
673 CA_EVENT_LOSS, /* loss timeout */
674 CA_EVENT_FAST_ACK, /* in sequence ack */
675 CA_EVENT_SLOW_ACK, /* other ack */
676};
677
678/*
679 * Interface for adding new TCP congestion control handlers
680 */
681#define TCP_CA_NAME_MAX 16
682#define TCP_CA_MAX 128
683#define TCP_CA_BUF_MAX (TCP_CA_NAME_MAX*TCP_CA_MAX)
684
685#define TCP_CONG_NON_RESTRICTED 0x1
686#define TCP_CONG_RTT_STAMP 0x2
687
688struct tcp_congestion_ops {
689 struct list_head list;
690 unsigned long flags;
691
692 /* initialize private data (optional) */
693 void (*init)(struct sock *sk);
694 /* cleanup private data (optional) */
695 void (*release)(struct sock *sk);
696
697 /* return slow start threshold (required) */
698 u32 (*ssthresh)(struct sock *sk);
699 /* lower bound for congestion window (optional) */
700 u32 (*min_cwnd)(const struct sock *sk);
701 /* do new cwnd calculation (required) */
702 void (*cong_avoid)(struct sock *sk, u32 ack, u32 in_flight);
703 /* call before changing ca_state (optional) */
704 void (*set_state)(struct sock *sk, u8 new_state);
705 /* call when cwnd event occurs (optional) */
706 void (*cwnd_event)(struct sock *sk, enum tcp_ca_event ev);
707 /* new value of cwnd after loss (optional) */
708 u32 (*undo_cwnd)(struct sock *sk);
709 /* hook for packet ack accounting (optional) */
710 void (*pkts_acked)(struct sock *sk, u32 num_acked, s32 rtt_us);
711 /* get info for inet_diag (optional) */
712 void (*get_info)(struct sock *sk, u32 ext, struct sk_buff *skb);
713
714 char name[TCP_CA_NAME_MAX];
715 struct module *owner;
716};
717
718extern int tcp_register_congestion_control(struct tcp_congestion_ops *type);
719extern void tcp_unregister_congestion_control(struct tcp_congestion_ops *type);
720
721extern void tcp_init_congestion_control(struct sock *sk);
722extern void tcp_cleanup_congestion_control(struct sock *sk);
723extern int tcp_set_default_congestion_control(const char *name);
724extern void tcp_get_default_congestion_control(char *name);
725extern void tcp_get_available_congestion_control(char *buf, size_t len);
726extern void tcp_get_allowed_congestion_control(char *buf, size_t len);
727extern int tcp_set_allowed_congestion_control(char *allowed);
728extern int tcp_set_congestion_control(struct sock *sk, const char *name);
729extern void tcp_slow_start(struct tcp_sock *tp);
730extern void tcp_cong_avoid_ai(struct tcp_sock *tp, u32 w);
731
732extern struct tcp_congestion_ops tcp_init_congestion_ops;
733extern u32 tcp_reno_ssthresh(struct sock *sk);
734extern void tcp_reno_cong_avoid(struct sock *sk, u32 ack, u32 in_flight);
735extern u32 tcp_reno_min_cwnd(const struct sock *sk);
736extern struct tcp_congestion_ops tcp_reno;
737
738static inline void tcp_set_ca_state(struct sock *sk, const u8 ca_state)
739{
740 struct inet_connection_sock *icsk = inet_csk(sk);
741
742 if (icsk->icsk_ca_ops->set_state)
743 icsk->icsk_ca_ops->set_state(sk, ca_state);
744 icsk->icsk_ca_state = ca_state;
745}
746
747static inline void tcp_ca_event(struct sock *sk, const enum tcp_ca_event event)
748{
749 const struct inet_connection_sock *icsk = inet_csk(sk);
750
751 if (icsk->icsk_ca_ops->cwnd_event)
752 icsk->icsk_ca_ops->cwnd_event(sk, event);
753}
754
755/* These functions determine how the current flow behaves in respect of SACK
756 * handling. SACK is negotiated with the peer, and therefore it can vary
757 * between different flows.
758 *
759 * tcp_is_sack - SACK enabled
760 * tcp_is_reno - No SACK
761 * tcp_is_fack - FACK enabled, implies SACK enabled
762 */
763static inline int tcp_is_sack(const struct tcp_sock *tp)
764{
765 return tp->rx_opt.sack_ok;
766}
767
768static inline int tcp_is_reno(const struct tcp_sock *tp)
769{
770 return !tcp_is_sack(tp);
771}
772
773static inline int tcp_is_fack(const struct tcp_sock *tp)
774{
775 return tp->rx_opt.sack_ok & 2;
776}
777
778static inline void tcp_enable_fack(struct tcp_sock *tp)
779{
780 tp->rx_opt.sack_ok |= 2;
781}
782
783static inline unsigned int tcp_left_out(const struct tcp_sock *tp)
784{
785 return tp->sacked_out + tp->lost_out;
786}
787
788/* This determines how many packets are "in the network" to the best
789 * of our knowledge. In many cases it is conservative, but where
790 * detailed information is available from the receiver (via SACK
791 * blocks etc.) we can make more aggressive calculations.
792 *
793 * Use this for decisions involving congestion control, use just
794 * tp->packets_out to determine if the send queue is empty or not.
795 *
796 * Read this equation as:
797 *
798 * "Packets sent once on transmission queue" MINUS
799 * "Packets left network, but not honestly ACKed yet" PLUS
800 * "Packets fast retransmitted"
801 */
802static inline unsigned int tcp_packets_in_flight(const struct tcp_sock *tp)
803{
804 return tp->packets_out - tcp_left_out(tp) + tp->retrans_out;
805}
806
807#define TCP_INFINITE_SSTHRESH 0x7fffffff
808
809static inline bool tcp_in_initial_slowstart(const struct tcp_sock *tp)
810{
811 return tp->snd_ssthresh >= TCP_INFINITE_SSTHRESH;
812}
813
814/* If cwnd > ssthresh, we may raise ssthresh to be half-way to cwnd.
815 * The exception is rate halving phase, when cwnd is decreasing towards
816 * ssthresh.
817 */
818static inline __u32 tcp_current_ssthresh(const struct sock *sk)
819{
820 const struct tcp_sock *tp = tcp_sk(sk);
821 if ((1 << inet_csk(sk)->icsk_ca_state) & (TCPF_CA_CWR | TCPF_CA_Recovery))
822 return tp->snd_ssthresh;
823 else
824 return max(tp->snd_ssthresh,
825 ((tp->snd_cwnd >> 1) +
826 (tp->snd_cwnd >> 2)));
827}
828
829/* Use define here intentionally to get WARN_ON location shown at the caller */
830#define tcp_verify_left_out(tp) WARN_ON(tcp_left_out(tp) > tp->packets_out)
831
832extern void tcp_enter_cwr(struct sock *sk, const int set_ssthresh);
833extern __u32 tcp_init_cwnd(struct tcp_sock *tp, struct dst_entry *dst);
834
835/* Slow start with delack produces 3 packets of burst, so that
836 * it is safe "de facto". This will be the default - same as
837 * the default reordering threshold - but if reordering increases,
838 * we must be able to allow cwnd to burst at least this much in order
839 * to not pull it back when holes are filled.
840 */
841static __inline__ __u32 tcp_max_burst(const struct tcp_sock *tp)
842{
843 return tp->reordering;
844}
845
846/* Returns end sequence number of the receiver's advertised window */
847static inline u32 tcp_wnd_end(const struct tcp_sock *tp)
848{
849 return tp->snd_una + tp->snd_wnd;
850}
851extern int tcp_is_cwnd_limited(const struct sock *sk, u32 in_flight);
852
853static inline void tcp_minshall_update(struct tcp_sock *tp, unsigned int mss,
854 const struct sk_buff *skb)
855{
856 if (skb->len < mss)
857 tp->snd_sml = TCP_SKB_CB(skb)->end_seq;
858}
859
860static inline void tcp_check_probe_timer(struct sock *sk)
861{
862 struct tcp_sock *tp = tcp_sk(sk);
863 const struct inet_connection_sock *icsk = inet_csk(sk);
864
865 if (!tp->packets_out && !icsk->icsk_pending)
866 inet_csk_reset_xmit_timer(sk, ICSK_TIME_PROBE0,
867 icsk->icsk_rto, TCP_RTO_MAX);
868}
869
870static inline void tcp_init_wl(struct tcp_sock *tp, u32 seq)
871{
872 tp->snd_wl1 = seq;
873}
874
875static inline void tcp_update_wl(struct tcp_sock *tp, u32 seq)
876{
877 tp->snd_wl1 = seq;
878}
879
880/*
881 * Calculate(/check) TCP checksum
882 */
883static inline __sum16 tcp_v4_check(int len, __be32 saddr,
884 __be32 daddr, __wsum base)
885{
886 return csum_tcpudp_magic(saddr,daddr,len,IPPROTO_TCP,base);
887}
888
889static inline __sum16 __tcp_checksum_complete(struct sk_buff *skb)
890{
891 return __skb_checksum_complete(skb);
892}
893
894static inline int tcp_checksum_complete(struct sk_buff *skb)
895{
896 return !skb_csum_unnecessary(skb) &&
897 __tcp_checksum_complete(skb);
898}
899
900/* Prequeue for VJ style copy to user, combined with checksumming. */
901
902static inline void tcp_prequeue_init(struct tcp_sock *tp)
903{
904 tp->ucopy.task = NULL;
905 tp->ucopy.len = 0;
906 tp->ucopy.memory = 0;
907 skb_queue_head_init(&tp->ucopy.prequeue);
908#ifdef CONFIG_NET_DMA
909 tp->ucopy.dma_chan = NULL;
910 tp->ucopy.wakeup = 0;
911 tp->ucopy.pinned_list = NULL;
912 tp->ucopy.dma_cookie = 0;
913#endif
914}
915
916/* Packet is added to VJ-style prequeue for processing in process
917 * context, if a reader task is waiting. Apparently, this exciting
918 * idea (VJ's mail "Re: query about TCP header on tcp-ip" of 07 Sep 93)
919 * failed somewhere. Latency? Burstiness? Well, at least now we will
920 * see, why it failed. 8)8) --ANK
921 *
922 * NOTE: is this not too big to inline?
923 */
924static inline int tcp_prequeue(struct sock *sk, struct sk_buff *skb)
925{
926 struct tcp_sock *tp = tcp_sk(sk);
927
928 if (sysctl_tcp_low_latency || !tp->ucopy.task)
929 return 0;
930
931 __skb_queue_tail(&tp->ucopy.prequeue, skb);
932 tp->ucopy.memory += skb->truesize;
933 if (tp->ucopy.memory > sk->sk_rcvbuf) {
934 struct sk_buff *skb1;
935
936 BUG_ON(sock_owned_by_user(sk));
937
938 while ((skb1 = __skb_dequeue(&tp->ucopy.prequeue)) != NULL) {
939 sk_backlog_rcv(sk, skb1);
940 NET_INC_STATS_BH(sock_net(sk),
941 LINUX_MIB_TCPPREQUEUEDROPPED);
942 }
943
944 tp->ucopy.memory = 0;
945 } else if (skb_queue_len(&tp->ucopy.prequeue) == 1) {
946 wake_up_interruptible_sync_poll(sk_sleep(sk),
947 POLLIN | POLLRDNORM | POLLRDBAND);
948 if (!inet_csk_ack_scheduled(sk))
949 inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK,
950 (3 * tcp_rto_min(sk)) / 4,
951 TCP_RTO_MAX);
952 }
953 return 1;
954}
955
956
957#undef STATE_TRACE
958
959#ifdef STATE_TRACE
960static const char *statename[]={
961 "Unused","Established","Syn Sent","Syn Recv",
962 "Fin Wait 1","Fin Wait 2","Time Wait", "Close",
963 "Close Wait","Last ACK","Listen","Closing"
964};
965#endif
966extern void tcp_set_state(struct sock *sk, int state);
967
968extern void tcp_done(struct sock *sk);
969
970static inline void tcp_sack_reset(struct tcp_options_received *rx_opt)
971{
972 rx_opt->dsack = 0;
973 rx_opt->num_sacks = 0;
974}
975
976/* Determine a window scaling and initial window to offer. */
977extern void tcp_select_initial_window(int __space, __u32 mss,
978 __u32 *rcv_wnd, __u32 *window_clamp,
979 int wscale_ok, __u8 *rcv_wscale,
980 __u32 init_rcv_wnd);
981
982static inline int tcp_win_from_space(int space)
983{
984 return sysctl_tcp_adv_win_scale<=0 ?
985 (space>>(-sysctl_tcp_adv_win_scale)) :
986 space - (space>>sysctl_tcp_adv_win_scale);
987}
988
989/* Note: caller must be prepared to deal with negative returns */
990static inline int tcp_space(const struct sock *sk)
991{
992 return tcp_win_from_space(sk->sk_rcvbuf -
993 atomic_read(&sk->sk_rmem_alloc));
994}
995
996static inline int tcp_full_space(const struct sock *sk)
997{
998 return tcp_win_from_space(sk->sk_rcvbuf);
999}
1000
1001static inline void tcp_openreq_init(struct request_sock *req,
1002 struct tcp_options_received *rx_opt,
1003 struct sk_buff *skb)
1004{
1005 struct inet_request_sock *ireq = inet_rsk(req);
1006
1007 req->rcv_wnd = 0; /* So that tcp_send_synack() knows! */
1008 req->cookie_ts = 0;
1009 tcp_rsk(req)->rcv_isn = TCP_SKB_CB(skb)->seq;
1010 req->mss = rx_opt->mss_clamp;
1011 req->ts_recent = rx_opt->saw_tstamp ? rx_opt->rcv_tsval : 0;
1012 ireq->tstamp_ok = rx_opt->tstamp_ok;
1013 ireq->sack_ok = rx_opt->sack_ok;
1014 ireq->snd_wscale = rx_opt->snd_wscale;
1015 ireq->wscale_ok = rx_opt->wscale_ok;
1016 ireq->acked = 0;
1017 ireq->ecn_ok = 0;
1018 ireq->rmt_port = tcp_hdr(skb)->source;
1019 ireq->loc_port = tcp_hdr(skb)->dest;
1020}
1021
1022extern void tcp_enter_memory_pressure(struct sock *sk);
1023
1024static inline int keepalive_intvl_when(const struct tcp_sock *tp)
1025{
1026 return tp->keepalive_intvl ? : sysctl_tcp_keepalive_intvl;
1027}
1028
1029static inline int keepalive_time_when(const struct tcp_sock *tp)
1030{
1031 return tp->keepalive_time ? : sysctl_tcp_keepalive_time;
1032}
1033
1034static inline int keepalive_probes(const struct tcp_sock *tp)
1035{
1036 return tp->keepalive_probes ? : sysctl_tcp_keepalive_probes;
1037}
1038
1039static inline u32 keepalive_time_elapsed(const struct tcp_sock *tp)
1040{
1041 const struct inet_connection_sock *icsk = &tp->inet_conn;
1042
1043 return min_t(u32, tcp_time_stamp - icsk->icsk_ack.lrcvtime,
1044 tcp_time_stamp - tp->rcv_tstamp);
1045}
1046
1047static inline int tcp_fin_time(const struct sock *sk)
1048{
1049 int fin_timeout = tcp_sk(sk)->linger2 ? : sysctl_tcp_fin_timeout;
1050 const int rto = inet_csk(sk)->icsk_rto;
1051
1052 if (fin_timeout < (rto << 2) - (rto >> 1))
1053 fin_timeout = (rto << 2) - (rto >> 1);
1054
1055 return fin_timeout;
1056}
1057
1058static inline int tcp_paws_check(const struct tcp_options_received *rx_opt,
1059 int paws_win)
1060{
1061 if ((s32)(rx_opt->ts_recent - rx_opt->rcv_tsval) <= paws_win)
1062 return 1;
1063 if (unlikely(get_seconds() >= rx_opt->ts_recent_stamp + TCP_PAWS_24DAYS))
1064 return 1;
1065 /*
1066 * Some OSes send SYN and SYNACK messages with tsval=0 tsecr=0,
1067 * then following tcp messages have valid values. Ignore 0 value,
1068 * or else 'negative' tsval might forbid us to accept their packets.
1069 */
1070 if (!rx_opt->ts_recent)
1071 return 1;
1072 return 0;
1073}
1074
1075static inline int tcp_paws_reject(const struct tcp_options_received *rx_opt,
1076 int rst)
1077{
1078 if (tcp_paws_check(rx_opt, 0))
1079 return 0;
1080
1081 /* RST segments are not recommended to carry timestamp,
1082 and, if they do, it is recommended to ignore PAWS because
1083 "their cleanup function should take precedence over timestamps."
1084 Certainly, it is mistake. It is necessary to understand the reasons
1085 of this constraint to relax it: if peer reboots, clock may go
1086 out-of-sync and half-open connections will not be reset.
1087 Actually, the problem would be not existing if all
1088 the implementations followed draft about maintaining clock
1089 via reboots. Linux-2.2 DOES NOT!
1090
1091 However, we can relax time bounds for RST segments to MSL.
1092 */
1093 if (rst && get_seconds() >= rx_opt->ts_recent_stamp + TCP_PAWS_MSL)
1094 return 0;
1095 return 1;
1096}
1097
1098static inline void tcp_mib_init(struct net *net)
1099{
1100 /* See RFC 2012 */
1101 TCP_ADD_STATS_USER(net, TCP_MIB_RTOALGORITHM, 1);
1102 TCP_ADD_STATS_USER(net, TCP_MIB_RTOMIN, TCP_RTO_MIN*1000/HZ);
1103 TCP_ADD_STATS_USER(net, TCP_MIB_RTOMAX, TCP_RTO_MAX*1000/HZ);
1104 TCP_ADD_STATS_USER(net, TCP_MIB_MAXCONN, -1);
1105}
1106
1107/* from STCP */
1108static inline void tcp_clear_retrans_hints_partial(struct tcp_sock *tp)
1109{
1110 tp->lost_skb_hint = NULL;
1111 tp->scoreboard_skb_hint = NULL;
1112}
1113
1114static inline void tcp_clear_all_retrans_hints(struct tcp_sock *tp)
1115{
1116 tcp_clear_retrans_hints_partial(tp);
1117 tp->retransmit_skb_hint = NULL;
1118}
1119
1120/* MD5 Signature */
1121struct crypto_hash;
1122
1123/* - key database */
1124struct tcp_md5sig_key {
1125 u8 *key;
1126 u8 keylen;
1127};
1128
1129struct tcp4_md5sig_key {
1130 struct tcp_md5sig_key base;
1131 __be32 addr;
1132};
1133
1134struct tcp6_md5sig_key {
1135 struct tcp_md5sig_key base;
1136#if 0
1137 u32 scope_id; /* XXX */
1138#endif
1139 struct in6_addr addr;
1140};
1141
1142/* - sock block */
1143struct tcp_md5sig_info {
1144 struct tcp4_md5sig_key *keys4;
1145#if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
1146 struct tcp6_md5sig_key *keys6;
1147 u32 entries6;
1148 u32 alloced6;
1149#endif
1150 u32 entries4;
1151 u32 alloced4;
1152};
1153
1154/* - pseudo header */
1155struct tcp4_pseudohdr {
1156 __be32 saddr;
1157 __be32 daddr;
1158 __u8 pad;
1159 __u8 protocol;
1160 __be16 len;
1161};
1162
1163struct tcp6_pseudohdr {
1164 struct in6_addr saddr;
1165 struct in6_addr daddr;
1166 __be32 len;
1167 __be32 protocol; /* including padding */
1168};
1169
1170union tcp_md5sum_block {
1171 struct tcp4_pseudohdr ip4;
1172#if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
1173 struct tcp6_pseudohdr ip6;
1174#endif
1175};
1176
1177/* - pool: digest algorithm, hash description and scratch buffer */
1178struct tcp_md5sig_pool {
1179 struct hash_desc md5_desc;
1180 union tcp_md5sum_block md5_blk;
1181};
1182
1183/* - functions */
1184extern int tcp_v4_md5_hash_skb(char *md5_hash, struct tcp_md5sig_key *key,
1185 struct sock *sk, struct request_sock *req,
1186 struct sk_buff *skb);
1187extern struct tcp_md5sig_key * tcp_v4_md5_lookup(struct sock *sk,
1188 struct sock *addr_sk);
1189extern int tcp_v4_md5_do_add(struct sock *sk, __be32 addr, u8 *newkey,
1190 u8 newkeylen);
1191extern int tcp_v4_md5_do_del(struct sock *sk, __be32 addr);
1192
1193#ifdef CONFIG_TCP_MD5SIG
1194#define tcp_twsk_md5_key(twsk) ((twsk)->tw_md5_keylen ? \
1195 &(struct tcp_md5sig_key) { \
1196 .key = (twsk)->tw_md5_key, \
1197 .keylen = (twsk)->tw_md5_keylen, \
1198 } : NULL)
1199#else
1200#define tcp_twsk_md5_key(twsk) NULL
1201#endif
1202
1203extern struct tcp_md5sig_pool * __percpu *tcp_alloc_md5sig_pool(struct sock *);
1204extern void tcp_free_md5sig_pool(void);
1205
1206extern struct tcp_md5sig_pool *tcp_get_md5sig_pool(void);
1207extern void tcp_put_md5sig_pool(void);
1208
1209extern int tcp_md5_hash_header(struct tcp_md5sig_pool *, struct tcphdr *);
1210extern int tcp_md5_hash_skb_data(struct tcp_md5sig_pool *, struct sk_buff *,
1211 unsigned header_len);
1212extern int tcp_md5_hash_key(struct tcp_md5sig_pool *hp,
1213 struct tcp_md5sig_key *key);
1214
1215/* write queue abstraction */
1216static inline void tcp_write_queue_purge(struct sock *sk)
1217{
1218 struct sk_buff *skb;
1219
1220 while ((skb = __skb_dequeue(&sk->sk_write_queue)) != NULL)
1221 sk_wmem_free_skb(sk, skb);
1222 sk_mem_reclaim(sk);
1223 tcp_clear_all_retrans_hints(tcp_sk(sk));
1224}
1225
1226static inline struct sk_buff *tcp_write_queue_head(struct sock *sk)
1227{
1228 return skb_peek(&sk->sk_write_queue);
1229}
1230
1231static inline struct sk_buff *tcp_write_queue_tail(struct sock *sk)
1232{
1233 return skb_peek_tail(&sk->sk_write_queue);
1234}
1235
1236static inline struct sk_buff *tcp_write_queue_next(struct sock *sk, struct sk_buff *skb)
1237{
1238 return skb_queue_next(&sk->sk_write_queue, skb);
1239}
1240
1241static inline struct sk_buff *tcp_write_queue_prev(struct sock *sk, struct sk_buff *skb)
1242{
1243 return skb_queue_prev(&sk->sk_write_queue, skb);
1244}
1245
1246#define tcp_for_write_queue(skb, sk) \
1247 skb_queue_walk(&(sk)->sk_write_queue, skb)
1248
1249#define tcp_for_write_queue_from(skb, sk) \
1250 skb_queue_walk_from(&(sk)->sk_write_queue, skb)
1251
1252#define tcp_for_write_queue_from_safe(skb, tmp, sk) \
1253 skb_queue_walk_from_safe(&(sk)->sk_write_queue, skb, tmp)
1254
1255static inline struct sk_buff *tcp_send_head(struct sock *sk)
1256{
1257 return sk->sk_send_head;
1258}
1259
1260static inline bool tcp_skb_is_last(const struct sock *sk,
1261 const struct sk_buff *skb)
1262{
1263 return skb_queue_is_last(&sk->sk_write_queue, skb);
1264}
1265
1266static inline void tcp_advance_send_head(struct sock *sk, struct sk_buff *skb)
1267{
1268 if (tcp_skb_is_last(sk, skb))
1269 sk->sk_send_head = NULL;
1270 else
1271 sk->sk_send_head = tcp_write_queue_next(sk, skb);
1272}
1273
1274static inline void tcp_check_send_head(struct sock *sk, struct sk_buff *skb_unlinked)
1275{
1276 if (sk->sk_send_head == skb_unlinked)
1277 sk->sk_send_head = NULL;
1278}
1279
1280static inline void tcp_init_send_head(struct sock *sk)
1281{
1282 sk->sk_send_head = NULL;
1283}
1284
1285static inline void __tcp_add_write_queue_tail(struct sock *sk, struct sk_buff *skb)
1286{
1287 __skb_queue_tail(&sk->sk_write_queue, skb);
1288}
1289
1290static inline void tcp_add_write_queue_tail(struct sock *sk, struct sk_buff *skb)
1291{
1292 __tcp_add_write_queue_tail(sk, skb);
1293
1294 /* Queue it, remembering where we must start sending. */
1295 if (sk->sk_send_head == NULL) {
1296 sk->sk_send_head = skb;
1297
1298 if (tcp_sk(sk)->highest_sack == NULL)
1299 tcp_sk(sk)->highest_sack = skb;
1300 }
1301}
1302
1303static inline void __tcp_add_write_queue_head(struct sock *sk, struct sk_buff *skb)
1304{
1305 __skb_queue_head(&sk->sk_write_queue, skb);
1306}
1307
1308/* Insert buff after skb on the write queue of sk. */
1309static inline void tcp_insert_write_queue_after(struct sk_buff *skb,
1310 struct sk_buff *buff,
1311 struct sock *sk)
1312{
1313 __skb_queue_after(&sk->sk_write_queue, skb, buff);
1314}
1315
1316/* Insert new before skb on the write queue of sk. */
1317static inline void tcp_insert_write_queue_before(struct sk_buff *new,
1318 struct sk_buff *skb,
1319 struct sock *sk)
1320{
1321 __skb_queue_before(&sk->sk_write_queue, skb, new);
1322
1323 if (sk->sk_send_head == skb)
1324 sk->sk_send_head = new;
1325}
1326
1327static inline void tcp_unlink_write_queue(struct sk_buff *skb, struct sock *sk)
1328{
1329 __skb_unlink(skb, &sk->sk_write_queue);
1330}
1331
1332static inline int tcp_write_queue_empty(struct sock *sk)
1333{
1334 return skb_queue_empty(&sk->sk_write_queue);
1335}
1336
1337static inline void tcp_push_pending_frames(struct sock *sk)
1338{
1339 if (tcp_send_head(sk)) {
1340 struct tcp_sock *tp = tcp_sk(sk);
1341
1342 __tcp_push_pending_frames(sk, tcp_current_mss(sk), tp->nonagle);
1343 }
1344}
1345
1346/* Start sequence of the highest skb with SACKed bit, valid only if
1347 * sacked > 0 or when the caller has ensured validity by itself.
1348 */
1349static inline u32 tcp_highest_sack_seq(struct tcp_sock *tp)
1350{
1351 if (!tp->sacked_out)
1352 return tp->snd_una;
1353
1354 if (tp->highest_sack == NULL)
1355 return tp->snd_nxt;
1356
1357 return TCP_SKB_CB(tp->highest_sack)->seq;
1358}
1359
1360static inline void tcp_advance_highest_sack(struct sock *sk, struct sk_buff *skb)
1361{
1362 tcp_sk(sk)->highest_sack = tcp_skb_is_last(sk, skb) ? NULL :
1363 tcp_write_queue_next(sk, skb);
1364}
1365
1366static inline struct sk_buff *tcp_highest_sack(struct sock *sk)
1367{
1368 return tcp_sk(sk)->highest_sack;
1369}
1370
1371static inline void tcp_highest_sack_reset(struct sock *sk)
1372{
1373 tcp_sk(sk)->highest_sack = tcp_write_queue_head(sk);
1374}
1375
1376/* Called when old skb is about to be deleted (to be combined with new skb) */
1377static inline void tcp_highest_sack_combine(struct sock *sk,
1378 struct sk_buff *old,
1379 struct sk_buff *new)
1380{
1381 if (tcp_sk(sk)->sacked_out && (old == tcp_sk(sk)->highest_sack))
1382 tcp_sk(sk)->highest_sack = new;
1383}
1384
1385/* Determines whether this is a thin stream (which may suffer from
1386 * increased latency). Used to trigger latency-reducing mechanisms.
1387 */
1388static inline unsigned int tcp_stream_is_thin(struct tcp_sock *tp)
1389{
1390 return tp->packets_out < 4 && !tcp_in_initial_slowstart(tp);
1391}
1392
1393/* /proc */
1394enum tcp_seq_states {
1395 TCP_SEQ_STATE_LISTENING,
1396 TCP_SEQ_STATE_OPENREQ,
1397 TCP_SEQ_STATE_ESTABLISHED,
1398 TCP_SEQ_STATE_TIME_WAIT,
1399};
1400
1401struct tcp_seq_afinfo {
1402 char *name;
1403 sa_family_t family;
1404 struct file_operations seq_fops;
1405 struct seq_operations seq_ops;
1406};
1407
1408struct tcp_iter_state {
1409 struct seq_net_private p;
1410 sa_family_t family;
1411 enum tcp_seq_states state;
1412 struct sock *syn_wait_sk;
1413 int bucket, offset, sbucket, num, uid;
1414 loff_t last_pos;
1415};
1416
1417extern int tcp_proc_register(struct net *net, struct tcp_seq_afinfo *afinfo);
1418extern void tcp_proc_unregister(struct net *net, struct tcp_seq_afinfo *afinfo);
1419
1420extern struct request_sock_ops tcp_request_sock_ops;
1421extern struct request_sock_ops tcp6_request_sock_ops;
1422
1423extern void tcp_v4_destroy_sock(struct sock *sk);
1424
1425extern int tcp_v4_gso_send_check(struct sk_buff *skb);
1426extern struct sk_buff *tcp_tso_segment(struct sk_buff *skb, u32 features);
1427extern struct sk_buff **tcp_gro_receive(struct sk_buff **head,
1428 struct sk_buff *skb);
1429extern struct sk_buff **tcp4_gro_receive(struct sk_buff **head,
1430 struct sk_buff *skb);
1431extern int tcp_gro_complete(struct sk_buff *skb);
1432extern int tcp4_gro_complete(struct sk_buff *skb);
1433
1434#ifdef CONFIG_PROC_FS
1435extern int tcp4_proc_init(void);
1436extern void tcp4_proc_exit(void);
1437#endif
1438
1439/* TCP af-specific functions */
1440struct tcp_sock_af_ops {
1441#ifdef CONFIG_TCP_MD5SIG
1442 struct tcp_md5sig_key *(*md5_lookup) (struct sock *sk,
1443 struct sock *addr_sk);
1444 int (*calc_md5_hash) (char *location,
1445 struct tcp_md5sig_key *md5,
1446 struct sock *sk,
1447 struct request_sock *req,
1448 struct sk_buff *skb);
1449 int (*md5_add) (struct sock *sk,
1450 struct sock *addr_sk,
1451 u8 *newkey,
1452 u8 len);
1453 int (*md5_parse) (struct sock *sk,
1454 char __user *optval,
1455 int optlen);
1456#endif
1457};
1458
1459struct tcp_request_sock_ops {
1460#ifdef CONFIG_TCP_MD5SIG
1461 struct tcp_md5sig_key *(*md5_lookup) (struct sock *sk,
1462 struct request_sock *req);
1463 int (*calc_md5_hash) (char *location,
1464 struct tcp_md5sig_key *md5,
1465 struct sock *sk,
1466 struct request_sock *req,
1467 struct sk_buff *skb);
1468#endif
1469};
1470
1471/* Using SHA1 for now, define some constants.
1472 */
1473#define COOKIE_DIGEST_WORDS (SHA_DIGEST_WORDS)
1474#define COOKIE_MESSAGE_WORDS (SHA_MESSAGE_BYTES / 4)
1475#define COOKIE_WORKSPACE_WORDS (COOKIE_DIGEST_WORDS + COOKIE_MESSAGE_WORDS)
1476
1477extern int tcp_cookie_generator(u32 *bakery);
1478
1479/**
1480 * struct tcp_cookie_values - each socket needs extra space for the
1481 * cookies, together with (optional) space for any SYN data.
1482 *
1483 * A tcp_sock contains a pointer to the current value, and this is
1484 * cloned to the tcp_timewait_sock.
1485 *
1486 * @cookie_pair: variable data from the option exchange.
1487 *
1488 * @cookie_desired: user specified tcpct_cookie_desired. Zero
1489 * indicates default (sysctl_tcp_cookie_size).
1490 * After cookie sent, remembers size of cookie.
1491 * Range 0, TCP_COOKIE_MIN to TCP_COOKIE_MAX.
1492 *
1493 * @s_data_desired: user specified tcpct_s_data_desired. When the
1494 * constant payload is specified (@s_data_constant),
1495 * holds its length instead.
1496 * Range 0 to TCP_MSS_DESIRED.
1497 *
1498 * @s_data_payload: constant data that is to be included in the
1499 * payload of SYN or SYNACK segments when the
1500 * cookie option is present.
1501 */
1502struct tcp_cookie_values {
1503 struct kref kref;
1504 u8 cookie_pair[TCP_COOKIE_PAIR_SIZE];
1505 u8 cookie_pair_size;
1506 u8 cookie_desired;
1507 u16 s_data_desired:11,
1508 s_data_constant:1,
1509 s_data_in:1,
1510 s_data_out:1,
1511 s_data_unused:2;
1512 u8 s_data_payload[0];
1513};
1514
1515static inline void tcp_cookie_values_release(struct kref *kref)
1516{
1517 kfree(container_of(kref, struct tcp_cookie_values, kref));
1518}
1519
1520/* The length of constant payload data. Note that s_data_desired is
1521 * overloaded, depending on s_data_constant: either the length of constant
1522 * data (returned here) or the limit on variable data.
1523 */
1524static inline int tcp_s_data_size(const struct tcp_sock *tp)
1525{
1526 return (tp->cookie_values != NULL && tp->cookie_values->s_data_constant)
1527 ? tp->cookie_values->s_data_desired
1528 : 0;
1529}
1530
1531/**
1532 * struct tcp_extend_values - tcp_ipv?.c to tcp_output.c workspace.
1533 *
1534 * As tcp_request_sock has already been extended in other places, the
1535 * only remaining method is to pass stack values along as function
1536 * parameters. These parameters are not needed after sending SYNACK.
1537 *
1538 * @cookie_bakery: cryptographic secret and message workspace.
1539 *
1540 * @cookie_plus: bytes in authenticator/cookie option, copied from
1541 * struct tcp_options_received (above).
1542 */
1543struct tcp_extend_values {
1544 struct request_values rv;
1545 u32 cookie_bakery[COOKIE_WORKSPACE_WORDS];
1546 u8 cookie_plus:6,
1547 cookie_out_never:1,
1548 cookie_in_always:1;
1549};
1550
1551static inline struct tcp_extend_values *tcp_xv(struct request_values *rvp)
1552{
1553 return (struct tcp_extend_values *)rvp;
1554}
1555
1556extern void tcp_v4_init(void);
1557extern void tcp_init(void);
1558
1559#endif /* _TCP_H */
1/*
2 * INET An implementation of the TCP/IP protocol suite for the LINUX
3 * operating system. INET is implemented using the BSD Socket
4 * interface as the means of communication with the user level.
5 *
6 * Definitions for the TCP module.
7 *
8 * Version: @(#)tcp.h 1.0.5 05/23/93
9 *
10 * Authors: Ross Biro
11 * Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
12 *
13 * This program is free software; you can redistribute it and/or
14 * modify it under the terms of the GNU General Public License
15 * as published by the Free Software Foundation; either version
16 * 2 of the License, or (at your option) any later version.
17 */
18#ifndef _TCP_H
19#define _TCP_H
20
21#define FASTRETRANS_DEBUG 1
22
23#include <linux/list.h>
24#include <linux/tcp.h>
25#include <linux/bug.h>
26#include <linux/slab.h>
27#include <linux/cache.h>
28#include <linux/percpu.h>
29#include <linux/skbuff.h>
30#include <linux/dmaengine.h>
31#include <linux/crypto.h>
32#include <linux/cryptohash.h>
33#include <linux/kref.h>
34#include <linux/ktime.h>
35
36#include <net/inet_connection_sock.h>
37#include <net/inet_timewait_sock.h>
38#include <net/inet_hashtables.h>
39#include <net/checksum.h>
40#include <net/request_sock.h>
41#include <net/sock.h>
42#include <net/snmp.h>
43#include <net/ip.h>
44#include <net/tcp_states.h>
45#include <net/inet_ecn.h>
46#include <net/dst.h>
47
48#include <linux/seq_file.h>
49#include <linux/memcontrol.h>
50
51extern struct inet_hashinfo tcp_hashinfo;
52
53extern struct percpu_counter tcp_orphan_count;
54void tcp_time_wait(struct sock *sk, int state, int timeo);
55
56#define MAX_TCP_HEADER (128 + MAX_HEADER)
57#define MAX_TCP_OPTION_SPACE 40
58
59/*
60 * Never offer a window over 32767 without using window scaling. Some
61 * poor stacks do signed 16bit maths!
62 */
63#define MAX_TCP_WINDOW 32767U
64
65/* Minimal accepted MSS. It is (60+60+8) - (20+20). */
66#define TCP_MIN_MSS 88U
67
68/* The least MTU to use for probing */
69#define TCP_BASE_MSS 512
70
71/* After receiving this amount of duplicate ACKs fast retransmit starts. */
72#define TCP_FASTRETRANS_THRESH 3
73
74/* Maximal reordering. */
75#define TCP_MAX_REORDERING 127
76
77/* Maximal number of ACKs sent quickly to accelerate slow-start. */
78#define TCP_MAX_QUICKACKS 16U
79
80/* urg_data states */
81#define TCP_URG_VALID 0x0100
82#define TCP_URG_NOTYET 0x0200
83#define TCP_URG_READ 0x0400
84
85#define TCP_RETR1 3 /*
86 * This is how many retries it does before it
87 * tries to figure out if the gateway is
88 * down. Minimal RFC value is 3; it corresponds
89 * to ~3sec-8min depending on RTO.
90 */
91
92#define TCP_RETR2 15 /*
93 * This should take at least
94 * 90 minutes to time out.
95 * RFC1122 says that the limit is 100 sec.
96 * 15 is ~13-30min depending on RTO.
97 */
98
99#define TCP_SYN_RETRIES 6 /* This is how many retries are done
100 * when active opening a connection.
101 * RFC1122 says the minimum retry MUST
102 * be at least 180secs. Nevertheless
103 * this value is corresponding to
104 * 63secs of retransmission with the
105 * current initial RTO.
106 */
107
108#define TCP_SYNACK_RETRIES 5 /* This is how may retries are done
109 * when passive opening a connection.
110 * This is corresponding to 31secs of
111 * retransmission with the current
112 * initial RTO.
113 */
114
115#define TCP_TIMEWAIT_LEN (60*HZ) /* how long to wait to destroy TIME-WAIT
116 * state, about 60 seconds */
117#define TCP_FIN_TIMEOUT TCP_TIMEWAIT_LEN
118 /* BSD style FIN_WAIT2 deadlock breaker.
119 * It used to be 3min, new value is 60sec,
120 * to combine FIN-WAIT-2 timeout with
121 * TIME-WAIT timer.
122 */
123
124#define TCP_DELACK_MAX ((unsigned)(HZ/5)) /* maximal time to delay before sending an ACK */
125#if HZ >= 100
126#define TCP_DELACK_MIN ((unsigned)(HZ/25)) /* minimal time to delay before sending an ACK */
127#define TCP_ATO_MIN ((unsigned)(HZ/25))
128#else
129#define TCP_DELACK_MIN 4U
130#define TCP_ATO_MIN 4U
131#endif
132#define TCP_RTO_MAX ((unsigned)(120*HZ))
133#define TCP_RTO_MIN ((unsigned)(HZ/5))
134#define TCP_TIMEOUT_INIT ((unsigned)(1*HZ)) /* RFC6298 2.1 initial RTO value */
135#define TCP_TIMEOUT_FALLBACK ((unsigned)(3*HZ)) /* RFC 1122 initial RTO value, now
136 * used as a fallback RTO for the
137 * initial data transmission if no
138 * valid RTT sample has been acquired,
139 * most likely due to retrans in 3WHS.
140 */
141
142#define TCP_RESOURCE_PROBE_INTERVAL ((unsigned)(HZ/2U)) /* Maximal interval between probes
143 * for local resources.
144 */
145
146#define TCP_KEEPALIVE_TIME (120*60*HZ) /* two hours */
147#define TCP_KEEPALIVE_PROBES 9 /* Max of 9 keepalive probes */
148#define TCP_KEEPALIVE_INTVL (75*HZ)
149
150#define MAX_TCP_KEEPIDLE 32767
151#define MAX_TCP_KEEPINTVL 32767
152#define MAX_TCP_KEEPCNT 127
153#define MAX_TCP_SYNCNT 127
154
155#define TCP_SYNQ_INTERVAL (HZ/5) /* Period of SYNACK timer */
156
157#define TCP_PAWS_24DAYS (60 * 60 * 24 * 24)
158#define TCP_PAWS_MSL 60 /* Per-host timestamps are invalidated
159 * after this time. It should be equal
160 * (or greater than) TCP_TIMEWAIT_LEN
161 * to provide reliability equal to one
162 * provided by timewait state.
163 */
164#define TCP_PAWS_WINDOW 1 /* Replay window for per-host
165 * timestamps. It must be less than
166 * minimal timewait lifetime.
167 */
168/*
169 * TCP option
170 */
171
172#define TCPOPT_NOP 1 /* Padding */
173#define TCPOPT_EOL 0 /* End of options */
174#define TCPOPT_MSS 2 /* Segment size negotiating */
175#define TCPOPT_WINDOW 3 /* Window scaling */
176#define TCPOPT_SACK_PERM 4 /* SACK Permitted */
177#define TCPOPT_SACK 5 /* SACK Block */
178#define TCPOPT_TIMESTAMP 8 /* Better RTT estimations/PAWS */
179#define TCPOPT_MD5SIG 19 /* MD5 Signature (RFC2385) */
180#define TCPOPT_EXP 254 /* Experimental */
181/* Magic number to be after the option value for sharing TCP
182 * experimental options. See draft-ietf-tcpm-experimental-options-00.txt
183 */
184#define TCPOPT_FASTOPEN_MAGIC 0xF989
185
186/*
187 * TCP option lengths
188 */
189
190#define TCPOLEN_MSS 4
191#define TCPOLEN_WINDOW 3
192#define TCPOLEN_SACK_PERM 2
193#define TCPOLEN_TIMESTAMP 10
194#define TCPOLEN_MD5SIG 18
195#define TCPOLEN_EXP_FASTOPEN_BASE 4
196
197/* But this is what stacks really send out. */
198#define TCPOLEN_TSTAMP_ALIGNED 12
199#define TCPOLEN_WSCALE_ALIGNED 4
200#define TCPOLEN_SACKPERM_ALIGNED 4
201#define TCPOLEN_SACK_BASE 2
202#define TCPOLEN_SACK_BASE_ALIGNED 4
203#define TCPOLEN_SACK_PERBLOCK 8
204#define TCPOLEN_MD5SIG_ALIGNED 20
205#define TCPOLEN_MSS_ALIGNED 4
206
207/* Flags in tp->nonagle */
208#define TCP_NAGLE_OFF 1 /* Nagle's algo is disabled */
209#define TCP_NAGLE_CORK 2 /* Socket is corked */
210#define TCP_NAGLE_PUSH 4 /* Cork is overridden for already queued data */
211
212/* TCP thin-stream limits */
213#define TCP_THIN_LINEAR_RETRIES 6 /* After 6 linear retries, do exp. backoff */
214
215/* TCP initial congestion window as per draft-hkchu-tcpm-initcwnd-01 */
216#define TCP_INIT_CWND 10
217
218/* Bit Flags for sysctl_tcp_fastopen */
219#define TFO_CLIENT_ENABLE 1
220#define TFO_SERVER_ENABLE 2
221#define TFO_CLIENT_NO_COOKIE 4 /* Data in SYN w/o cookie option */
222
223/* Process SYN data but skip cookie validation */
224#define TFO_SERVER_COOKIE_NOT_CHKED 0x100
225/* Accept SYN data w/o any cookie option */
226#define TFO_SERVER_COOKIE_NOT_REQD 0x200
227
228/* Force enable TFO on all listeners, i.e., not requiring the
229 * TCP_FASTOPEN socket option. SOCKOPT1/2 determine how to set max_qlen.
230 */
231#define TFO_SERVER_WO_SOCKOPT1 0x400
232#define TFO_SERVER_WO_SOCKOPT2 0x800
233/* Always create TFO child sockets on a TFO listener even when
234 * cookie/data not present. (For testing purpose!)
235 */
236#define TFO_SERVER_ALWAYS 0x1000
237
238extern struct inet_timewait_death_row tcp_death_row;
239
240/* sysctl variables for tcp */
241extern int sysctl_tcp_timestamps;
242extern int sysctl_tcp_window_scaling;
243extern int sysctl_tcp_sack;
244extern int sysctl_tcp_fin_timeout;
245extern int sysctl_tcp_keepalive_time;
246extern int sysctl_tcp_keepalive_probes;
247extern int sysctl_tcp_keepalive_intvl;
248extern int sysctl_tcp_syn_retries;
249extern int sysctl_tcp_synack_retries;
250extern int sysctl_tcp_retries1;
251extern int sysctl_tcp_retries2;
252extern int sysctl_tcp_orphan_retries;
253extern int sysctl_tcp_syncookies;
254extern int sysctl_tcp_fastopen;
255extern int sysctl_tcp_retrans_collapse;
256extern int sysctl_tcp_stdurg;
257extern int sysctl_tcp_rfc1337;
258extern int sysctl_tcp_abort_on_overflow;
259extern int sysctl_tcp_max_orphans;
260extern int sysctl_tcp_fack;
261extern int sysctl_tcp_reordering;
262extern int sysctl_tcp_dsack;
263extern long sysctl_tcp_mem[3];
264extern int sysctl_tcp_wmem[3];
265extern int sysctl_tcp_rmem[3];
266extern int sysctl_tcp_app_win;
267extern int sysctl_tcp_adv_win_scale;
268extern int sysctl_tcp_tw_reuse;
269extern int sysctl_tcp_frto;
270extern int sysctl_tcp_low_latency;
271extern int sysctl_tcp_dma_copybreak;
272extern int sysctl_tcp_nometrics_save;
273extern int sysctl_tcp_moderate_rcvbuf;
274extern int sysctl_tcp_tso_win_divisor;
275extern int sysctl_tcp_mtu_probing;
276extern int sysctl_tcp_base_mss;
277extern int sysctl_tcp_workaround_signed_windows;
278extern int sysctl_tcp_slow_start_after_idle;
279extern int sysctl_tcp_thin_linear_timeouts;
280extern int sysctl_tcp_thin_dupack;
281extern int sysctl_tcp_early_retrans;
282extern int sysctl_tcp_limit_output_bytes;
283extern int sysctl_tcp_challenge_ack_limit;
284extern unsigned int sysctl_tcp_notsent_lowat;
285extern int sysctl_tcp_min_tso_segs;
286extern int sysctl_tcp_autocorking;
287
288extern atomic_long_t tcp_memory_allocated;
289extern struct percpu_counter tcp_sockets_allocated;
290extern int tcp_memory_pressure;
291
292/*
293 * The next routines deal with comparing 32 bit unsigned ints
294 * and worry about wraparound (automatic with unsigned arithmetic).
295 */
296
297static inline bool before(__u32 seq1, __u32 seq2)
298{
299 return (__s32)(seq1-seq2) < 0;
300}
301#define after(seq2, seq1) before(seq1, seq2)
302
303/* is s2<=s1<=s3 ? */
304static inline bool between(__u32 seq1, __u32 seq2, __u32 seq3)
305{
306 return seq3 - seq2 >= seq1 - seq2;
307}
308
309static inline bool tcp_out_of_memory(struct sock *sk)
310{
311 if (sk->sk_wmem_queued > SOCK_MIN_SNDBUF &&
312 sk_memory_allocated(sk) > sk_prot_mem_limits(sk, 2))
313 return true;
314 return false;
315}
316
317static inline bool tcp_too_many_orphans(struct sock *sk, int shift)
318{
319 struct percpu_counter *ocp = sk->sk_prot->orphan_count;
320 int orphans = percpu_counter_read_positive(ocp);
321
322 if (orphans << shift > sysctl_tcp_max_orphans) {
323 orphans = percpu_counter_sum_positive(ocp);
324 if (orphans << shift > sysctl_tcp_max_orphans)
325 return true;
326 }
327 return false;
328}
329
330bool tcp_check_oom(struct sock *sk, int shift);
331
332/* syncookies: remember time of last synqueue overflow */
333static inline void tcp_synq_overflow(struct sock *sk)
334{
335 tcp_sk(sk)->rx_opt.ts_recent_stamp = jiffies;
336}
337
338/* syncookies: no recent synqueue overflow on this listening socket? */
339static inline bool tcp_synq_no_recent_overflow(const struct sock *sk)
340{
341 unsigned long last_overflow = tcp_sk(sk)->rx_opt.ts_recent_stamp;
342 return time_after(jiffies, last_overflow + TCP_TIMEOUT_FALLBACK);
343}
344
345extern struct proto tcp_prot;
346
347#define TCP_INC_STATS(net, field) SNMP_INC_STATS((net)->mib.tcp_statistics, field)
348#define TCP_INC_STATS_BH(net, field) SNMP_INC_STATS_BH((net)->mib.tcp_statistics, field)
349#define TCP_DEC_STATS(net, field) SNMP_DEC_STATS((net)->mib.tcp_statistics, field)
350#define TCP_ADD_STATS_USER(net, field, val) SNMP_ADD_STATS_USER((net)->mib.tcp_statistics, field, val)
351#define TCP_ADD_STATS(net, field, val) SNMP_ADD_STATS((net)->mib.tcp_statistics, field, val)
352
353void tcp_tasklet_init(void);
354
355void tcp_v4_err(struct sk_buff *skb, u32);
356
357void tcp_shutdown(struct sock *sk, int how);
358
359void tcp_v4_early_demux(struct sk_buff *skb);
360int tcp_v4_rcv(struct sk_buff *skb);
361
362int tcp_v4_tw_remember_stamp(struct inet_timewait_sock *tw);
363int tcp_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
364 size_t size);
365int tcp_sendpage(struct sock *sk, struct page *page, int offset, size_t size,
366 int flags);
367void tcp_release_cb(struct sock *sk);
368void tcp_wfree(struct sk_buff *skb);
369void tcp_write_timer_handler(struct sock *sk);
370void tcp_delack_timer_handler(struct sock *sk);
371int tcp_ioctl(struct sock *sk, int cmd, unsigned long arg);
372int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb,
373 const struct tcphdr *th, unsigned int len);
374void tcp_rcv_established(struct sock *sk, struct sk_buff *skb,
375 const struct tcphdr *th, unsigned int len);
376void tcp_rcv_space_adjust(struct sock *sk);
377void tcp_cleanup_rbuf(struct sock *sk, int copied);
378int tcp_twsk_unique(struct sock *sk, struct sock *sktw, void *twp);
379void tcp_twsk_destructor(struct sock *sk);
380ssize_t tcp_splice_read(struct socket *sk, loff_t *ppos,
381 struct pipe_inode_info *pipe, size_t len,
382 unsigned int flags);
383
384static inline void tcp_dec_quickack_mode(struct sock *sk,
385 const unsigned int pkts)
386{
387 struct inet_connection_sock *icsk = inet_csk(sk);
388
389 if (icsk->icsk_ack.quick) {
390 if (pkts >= icsk->icsk_ack.quick) {
391 icsk->icsk_ack.quick = 0;
392 /* Leaving quickack mode we deflate ATO. */
393 icsk->icsk_ack.ato = TCP_ATO_MIN;
394 } else
395 icsk->icsk_ack.quick -= pkts;
396 }
397}
398
399#define TCP_ECN_OK 1
400#define TCP_ECN_QUEUE_CWR 2
401#define TCP_ECN_DEMAND_CWR 4
402#define TCP_ECN_SEEN 8
403
404enum tcp_tw_status {
405 TCP_TW_SUCCESS = 0,
406 TCP_TW_RST = 1,
407 TCP_TW_ACK = 2,
408 TCP_TW_SYN = 3
409};
410
411
412enum tcp_tw_status tcp_timewait_state_process(struct inet_timewait_sock *tw,
413 struct sk_buff *skb,
414 const struct tcphdr *th);
415struct sock *tcp_check_req(struct sock *sk, struct sk_buff *skb,
416 struct request_sock *req, struct request_sock **prev,
417 bool fastopen);
418int tcp_child_process(struct sock *parent, struct sock *child,
419 struct sk_buff *skb);
420void tcp_enter_loss(struct sock *sk, int how);
421void tcp_clear_retrans(struct tcp_sock *tp);
422void tcp_update_metrics(struct sock *sk);
423void tcp_init_metrics(struct sock *sk);
424void tcp_metrics_init(void);
425bool tcp_peer_is_proven(struct request_sock *req, struct dst_entry *dst,
426 bool paws_check);
427bool tcp_remember_stamp(struct sock *sk);
428bool tcp_tw_remember_stamp(struct inet_timewait_sock *tw);
429void tcp_fetch_timewait_stamp(struct sock *sk, struct dst_entry *dst);
430void tcp_disable_fack(struct tcp_sock *tp);
431void tcp_close(struct sock *sk, long timeout);
432void tcp_init_sock(struct sock *sk);
433unsigned int tcp_poll(struct file *file, struct socket *sock,
434 struct poll_table_struct *wait);
435int tcp_getsockopt(struct sock *sk, int level, int optname,
436 char __user *optval, int __user *optlen);
437int tcp_setsockopt(struct sock *sk, int level, int optname,
438 char __user *optval, unsigned int optlen);
439int compat_tcp_getsockopt(struct sock *sk, int level, int optname,
440 char __user *optval, int __user *optlen);
441int compat_tcp_setsockopt(struct sock *sk, int level, int optname,
442 char __user *optval, unsigned int optlen);
443void tcp_set_keepalive(struct sock *sk, int val);
444void tcp_syn_ack_timeout(struct sock *sk, struct request_sock *req);
445int tcp_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
446 size_t len, int nonblock, int flags, int *addr_len);
447void tcp_parse_options(const struct sk_buff *skb,
448 struct tcp_options_received *opt_rx,
449 int estab, struct tcp_fastopen_cookie *foc);
450const u8 *tcp_parse_md5sig_option(const struct tcphdr *th);
451
452/*
453 * TCP v4 functions exported for the inet6 API
454 */
455
456void tcp_v4_send_check(struct sock *sk, struct sk_buff *skb);
457int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb);
458struct sock *tcp_create_openreq_child(struct sock *sk,
459 struct request_sock *req,
460 struct sk_buff *skb);
461struct sock *tcp_v4_syn_recv_sock(struct sock *sk, struct sk_buff *skb,
462 struct request_sock *req,
463 struct dst_entry *dst);
464int tcp_v4_do_rcv(struct sock *sk, struct sk_buff *skb);
465int tcp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len);
466int tcp_connect(struct sock *sk);
467struct sk_buff *tcp_make_synack(struct sock *sk, struct dst_entry *dst,
468 struct request_sock *req,
469 struct tcp_fastopen_cookie *foc);
470int tcp_disconnect(struct sock *sk, int flags);
471
472void tcp_finish_connect(struct sock *sk, struct sk_buff *skb);
473int tcp_send_rcvq(struct sock *sk, struct msghdr *msg, size_t size);
474void inet_sk_rx_dst_set(struct sock *sk, const struct sk_buff *skb);
475
476/* From syncookies.c */
477int __cookie_v4_check(const struct iphdr *iph, const struct tcphdr *th,
478 u32 cookie);
479struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb,
480 struct ip_options *opt);
481#ifdef CONFIG_SYN_COOKIES
482
483/* Syncookies use a monotonic timer which increments every 60 seconds.
484 * This counter is used both as a hash input and partially encoded into
485 * the cookie value. A cookie is only validated further if the delta
486 * between the current counter value and the encoded one is less than this,
487 * i.e. a sent cookie is valid only at most for 2*60 seconds (or less if
488 * the counter advances immediately after a cookie is generated).
489 */
490#define MAX_SYNCOOKIE_AGE 2
491
492static inline u32 tcp_cookie_time(void)
493{
494 u64 val = get_jiffies_64();
495
496 do_div(val, 60 * HZ);
497 return val;
498}
499
500u32 __cookie_v4_init_sequence(const struct iphdr *iph, const struct tcphdr *th,
501 u16 *mssp);
502__u32 cookie_v4_init_sequence(struct sock *sk, struct sk_buff *skb, __u16 *mss);
503#else
504static inline __u32 cookie_v4_init_sequence(struct sock *sk,
505 struct sk_buff *skb,
506 __u16 *mss)
507{
508 return 0;
509}
510#endif
511
512__u32 cookie_init_timestamp(struct request_sock *req);
513bool cookie_check_timestamp(struct tcp_options_received *opt, struct net *net,
514 bool *ecn_ok);
515
516/* From net/ipv6/syncookies.c */
517int __cookie_v6_check(const struct ipv6hdr *iph, const struct tcphdr *th,
518 u32 cookie);
519struct sock *cookie_v6_check(struct sock *sk, struct sk_buff *skb);
520#ifdef CONFIG_SYN_COOKIES
521u32 __cookie_v6_init_sequence(const struct ipv6hdr *iph,
522 const struct tcphdr *th, u16 *mssp);
523__u32 cookie_v6_init_sequence(struct sock *sk, const struct sk_buff *skb,
524 __u16 *mss);
525#else
526static inline __u32 cookie_v6_init_sequence(struct sock *sk,
527 struct sk_buff *skb,
528 __u16 *mss)
529{
530 return 0;
531}
532#endif
533/* tcp_output.c */
534
535void __tcp_push_pending_frames(struct sock *sk, unsigned int cur_mss,
536 int nonagle);
537bool tcp_may_send_now(struct sock *sk);
538int __tcp_retransmit_skb(struct sock *, struct sk_buff *);
539int tcp_retransmit_skb(struct sock *, struct sk_buff *);
540void tcp_retransmit_timer(struct sock *sk);
541void tcp_xmit_retransmit_queue(struct sock *);
542void tcp_simple_retransmit(struct sock *);
543int tcp_trim_head(struct sock *, struct sk_buff *, u32);
544int tcp_fragment(struct sock *, struct sk_buff *, u32, unsigned int);
545
546void tcp_send_probe0(struct sock *);
547void tcp_send_partial(struct sock *);
548int tcp_write_wakeup(struct sock *);
549void tcp_send_fin(struct sock *sk);
550void tcp_send_active_reset(struct sock *sk, gfp_t priority);
551int tcp_send_synack(struct sock *);
552bool tcp_syn_flood_action(struct sock *sk, const struct sk_buff *skb,
553 const char *proto);
554void tcp_push_one(struct sock *, unsigned int mss_now);
555void tcp_send_ack(struct sock *sk);
556void tcp_send_delayed_ack(struct sock *sk);
557void tcp_send_loss_probe(struct sock *sk);
558bool tcp_schedule_loss_probe(struct sock *sk);
559
560/* tcp_input.c */
561void tcp_cwnd_application_limited(struct sock *sk);
562void tcp_resume_early_retransmit(struct sock *sk);
563void tcp_rearm_rto(struct sock *sk);
564void tcp_reset(struct sock *sk);
565
566/* tcp_timer.c */
567void tcp_init_xmit_timers(struct sock *);
568static inline void tcp_clear_xmit_timers(struct sock *sk)
569{
570 inet_csk_clear_xmit_timers(sk);
571}
572
573unsigned int tcp_sync_mss(struct sock *sk, u32 pmtu);
574unsigned int tcp_current_mss(struct sock *sk);
575
576/* Bound MSS / TSO packet size with the half of the window */
577static inline int tcp_bound_to_half_wnd(struct tcp_sock *tp, int pktsize)
578{
579 int cutoff;
580
581 /* When peer uses tiny windows, there is no use in packetizing
582 * to sub-MSS pieces for the sake of SWS or making sure there
583 * are enough packets in the pipe for fast recovery.
584 *
585 * On the other hand, for extremely large MSS devices, handling
586 * smaller than MSS windows in this way does make sense.
587 */
588 if (tp->max_window >= 512)
589 cutoff = (tp->max_window >> 1);
590 else
591 cutoff = tp->max_window;
592
593 if (cutoff && pktsize > cutoff)
594 return max_t(int, cutoff, 68U - tp->tcp_header_len);
595 else
596 return pktsize;
597}
598
599/* tcp.c */
600void tcp_get_info(const struct sock *, struct tcp_info *);
601
602/* Read 'sendfile()'-style from a TCP socket */
603typedef int (*sk_read_actor_t)(read_descriptor_t *, struct sk_buff *,
604 unsigned int, size_t);
605int tcp_read_sock(struct sock *sk, read_descriptor_t *desc,
606 sk_read_actor_t recv_actor);
607
608void tcp_initialize_rcv_mss(struct sock *sk);
609
610int tcp_mtu_to_mss(struct sock *sk, int pmtu);
611int tcp_mss_to_mtu(struct sock *sk, int mss);
612void tcp_mtup_init(struct sock *sk);
613void tcp_init_buffer_space(struct sock *sk);
614
615static inline void tcp_bound_rto(const struct sock *sk)
616{
617 if (inet_csk(sk)->icsk_rto > TCP_RTO_MAX)
618 inet_csk(sk)->icsk_rto = TCP_RTO_MAX;
619}
620
621static inline u32 __tcp_set_rto(const struct tcp_sock *tp)
622{
623 return usecs_to_jiffies((tp->srtt_us >> 3) + tp->rttvar_us);
624}
625
626static inline void __tcp_fast_path_on(struct tcp_sock *tp, u32 snd_wnd)
627{
628 tp->pred_flags = htonl((tp->tcp_header_len << 26) |
629 ntohl(TCP_FLAG_ACK) |
630 snd_wnd);
631}
632
633static inline void tcp_fast_path_on(struct tcp_sock *tp)
634{
635 __tcp_fast_path_on(tp, tp->snd_wnd >> tp->rx_opt.snd_wscale);
636}
637
638static inline void tcp_fast_path_check(struct sock *sk)
639{
640 struct tcp_sock *tp = tcp_sk(sk);
641
642 if (skb_queue_empty(&tp->out_of_order_queue) &&
643 tp->rcv_wnd &&
644 atomic_read(&sk->sk_rmem_alloc) < sk->sk_rcvbuf &&
645 !tp->urg_data)
646 tcp_fast_path_on(tp);
647}
648
649/* Compute the actual rto_min value */
650static inline u32 tcp_rto_min(struct sock *sk)
651{
652 const struct dst_entry *dst = __sk_dst_get(sk);
653 u32 rto_min = TCP_RTO_MIN;
654
655 if (dst && dst_metric_locked(dst, RTAX_RTO_MIN))
656 rto_min = dst_metric_rtt(dst, RTAX_RTO_MIN);
657 return rto_min;
658}
659
660static inline u32 tcp_rto_min_us(struct sock *sk)
661{
662 return jiffies_to_usecs(tcp_rto_min(sk));
663}
664
665/* Compute the actual receive window we are currently advertising.
666 * Rcv_nxt can be after the window if our peer push more data
667 * than the offered window.
668 */
669static inline u32 tcp_receive_window(const struct tcp_sock *tp)
670{
671 s32 win = tp->rcv_wup + tp->rcv_wnd - tp->rcv_nxt;
672
673 if (win < 0)
674 win = 0;
675 return (u32) win;
676}
677
678/* Choose a new window, without checks for shrinking, and without
679 * scaling applied to the result. The caller does these things
680 * if necessary. This is a "raw" window selection.
681 */
682u32 __tcp_select_window(struct sock *sk);
683
684void tcp_send_window_probe(struct sock *sk);
685
686/* TCP timestamps are only 32-bits, this causes a slight
687 * complication on 64-bit systems since we store a snapshot
688 * of jiffies in the buffer control blocks below. We decided
689 * to use only the low 32-bits of jiffies and hide the ugly
690 * casts with the following macro.
691 */
692#define tcp_time_stamp ((__u32)(jiffies))
693
694#define tcp_flag_byte(th) (((u_int8_t *)th)[13])
695
696#define TCPHDR_FIN 0x01
697#define TCPHDR_SYN 0x02
698#define TCPHDR_RST 0x04
699#define TCPHDR_PSH 0x08
700#define TCPHDR_ACK 0x10
701#define TCPHDR_URG 0x20
702#define TCPHDR_ECE 0x40
703#define TCPHDR_CWR 0x80
704
705/* This is what the send packet queuing engine uses to pass
706 * TCP per-packet control information to the transmission code.
707 * We also store the host-order sequence numbers in here too.
708 * This is 44 bytes if IPV6 is enabled.
709 * If this grows please adjust skbuff.h:skbuff->cb[xxx] size appropriately.
710 */
711struct tcp_skb_cb {
712 union {
713 struct inet_skb_parm h4;
714#if IS_ENABLED(CONFIG_IPV6)
715 struct inet6_skb_parm h6;
716#endif
717 } header; /* For incoming frames */
718 __u32 seq; /* Starting sequence number */
719 __u32 end_seq; /* SEQ + FIN + SYN + datalen */
720 __u32 when; /* used to compute rtt's */
721 __u8 tcp_flags; /* TCP header flags. (tcp[13]) */
722
723 __u8 sacked; /* State flags for SACK/FACK. */
724#define TCPCB_SACKED_ACKED 0x01 /* SKB ACK'd by a SACK block */
725#define TCPCB_SACKED_RETRANS 0x02 /* SKB retransmitted */
726#define TCPCB_LOST 0x04 /* SKB is lost */
727#define TCPCB_TAGBITS 0x07 /* All tag bits */
728#define TCPCB_EVER_RETRANS 0x80 /* Ever retransmitted frame */
729#define TCPCB_RETRANS (TCPCB_SACKED_RETRANS|TCPCB_EVER_RETRANS)
730
731 __u8 ip_dsfield; /* IPv4 tos or IPv6 dsfield */
732 /* 1 byte hole */
733 __u32 ack_seq; /* Sequence number ACK'd */
734};
735
736#define TCP_SKB_CB(__skb) ((struct tcp_skb_cb *)&((__skb)->cb[0]))
737
738/* RFC3168 : 6.1.1 SYN packets must not have ECT/ECN bits set
739 *
740 * If we receive a SYN packet with these bits set, it means a network is
741 * playing bad games with TOS bits. In order to avoid possible false congestion
742 * notifications, we disable TCP ECN negociation.
743 */
744static inline void
745TCP_ECN_create_request(struct request_sock *req, const struct sk_buff *skb,
746 struct net *net)
747{
748 const struct tcphdr *th = tcp_hdr(skb);
749
750 if (net->ipv4.sysctl_tcp_ecn && th->ece && th->cwr &&
751 INET_ECN_is_not_ect(TCP_SKB_CB(skb)->ip_dsfield))
752 inet_rsk(req)->ecn_ok = 1;
753}
754
755/* Due to TSO, an SKB can be composed of multiple actual
756 * packets. To keep these tracked properly, we use this.
757 */
758static inline int tcp_skb_pcount(const struct sk_buff *skb)
759{
760 return skb_shinfo(skb)->gso_segs;
761}
762
763/* This is valid iff tcp_skb_pcount() > 1. */
764static inline int tcp_skb_mss(const struct sk_buff *skb)
765{
766 return skb_shinfo(skb)->gso_size;
767}
768
769/* Events passed to congestion control interface */
770enum tcp_ca_event {
771 CA_EVENT_TX_START, /* first transmit when no packets in flight */
772 CA_EVENT_CWND_RESTART, /* congestion window restart */
773 CA_EVENT_COMPLETE_CWR, /* end of congestion recovery */
774 CA_EVENT_LOSS, /* loss timeout */
775 CA_EVENT_FAST_ACK, /* in sequence ack */
776 CA_EVENT_SLOW_ACK, /* other ack */
777};
778
779/*
780 * Interface for adding new TCP congestion control handlers
781 */
782#define TCP_CA_NAME_MAX 16
783#define TCP_CA_MAX 128
784#define TCP_CA_BUF_MAX (TCP_CA_NAME_MAX*TCP_CA_MAX)
785
786#define TCP_CONG_NON_RESTRICTED 0x1
787
788struct tcp_congestion_ops {
789 struct list_head list;
790 unsigned long flags;
791
792 /* initialize private data (optional) */
793 void (*init)(struct sock *sk);
794 /* cleanup private data (optional) */
795 void (*release)(struct sock *sk);
796
797 /* return slow start threshold (required) */
798 u32 (*ssthresh)(struct sock *sk);
799 /* do new cwnd calculation (required) */
800 void (*cong_avoid)(struct sock *sk, u32 ack, u32 acked, u32 in_flight);
801 /* call before changing ca_state (optional) */
802 void (*set_state)(struct sock *sk, u8 new_state);
803 /* call when cwnd event occurs (optional) */
804 void (*cwnd_event)(struct sock *sk, enum tcp_ca_event ev);
805 /* new value of cwnd after loss (optional) */
806 u32 (*undo_cwnd)(struct sock *sk);
807 /* hook for packet ack accounting (optional) */
808 void (*pkts_acked)(struct sock *sk, u32 num_acked, s32 rtt_us);
809 /* get info for inet_diag (optional) */
810 void (*get_info)(struct sock *sk, u32 ext, struct sk_buff *skb);
811
812 char name[TCP_CA_NAME_MAX];
813 struct module *owner;
814};
815
816int tcp_register_congestion_control(struct tcp_congestion_ops *type);
817void tcp_unregister_congestion_control(struct tcp_congestion_ops *type);
818
819void tcp_init_congestion_control(struct sock *sk);
820void tcp_cleanup_congestion_control(struct sock *sk);
821int tcp_set_default_congestion_control(const char *name);
822void tcp_get_default_congestion_control(char *name);
823void tcp_get_available_congestion_control(char *buf, size_t len);
824void tcp_get_allowed_congestion_control(char *buf, size_t len);
825int tcp_set_allowed_congestion_control(char *allowed);
826int tcp_set_congestion_control(struct sock *sk, const char *name);
827int tcp_slow_start(struct tcp_sock *tp, u32 acked);
828void tcp_cong_avoid_ai(struct tcp_sock *tp, u32 w);
829
830extern struct tcp_congestion_ops tcp_init_congestion_ops;
831u32 tcp_reno_ssthresh(struct sock *sk);
832void tcp_reno_cong_avoid(struct sock *sk, u32 ack, u32 acked, u32 in_flight);
833extern struct tcp_congestion_ops tcp_reno;
834
835static inline void tcp_set_ca_state(struct sock *sk, const u8 ca_state)
836{
837 struct inet_connection_sock *icsk = inet_csk(sk);
838
839 if (icsk->icsk_ca_ops->set_state)
840 icsk->icsk_ca_ops->set_state(sk, ca_state);
841 icsk->icsk_ca_state = ca_state;
842}
843
844static inline void tcp_ca_event(struct sock *sk, const enum tcp_ca_event event)
845{
846 const struct inet_connection_sock *icsk = inet_csk(sk);
847
848 if (icsk->icsk_ca_ops->cwnd_event)
849 icsk->icsk_ca_ops->cwnd_event(sk, event);
850}
851
852/* These functions determine how the current flow behaves in respect of SACK
853 * handling. SACK is negotiated with the peer, and therefore it can vary
854 * between different flows.
855 *
856 * tcp_is_sack - SACK enabled
857 * tcp_is_reno - No SACK
858 * tcp_is_fack - FACK enabled, implies SACK enabled
859 */
860static inline int tcp_is_sack(const struct tcp_sock *tp)
861{
862 return tp->rx_opt.sack_ok;
863}
864
865static inline bool tcp_is_reno(const struct tcp_sock *tp)
866{
867 return !tcp_is_sack(tp);
868}
869
870static inline bool tcp_is_fack(const struct tcp_sock *tp)
871{
872 return tp->rx_opt.sack_ok & TCP_FACK_ENABLED;
873}
874
875static inline void tcp_enable_fack(struct tcp_sock *tp)
876{
877 tp->rx_opt.sack_ok |= TCP_FACK_ENABLED;
878}
879
880/* TCP early-retransmit (ER) is similar to but more conservative than
881 * the thin-dupack feature. Enable ER only if thin-dupack is disabled.
882 */
883static inline void tcp_enable_early_retrans(struct tcp_sock *tp)
884{
885 tp->do_early_retrans = sysctl_tcp_early_retrans &&
886 sysctl_tcp_early_retrans < 4 && !sysctl_tcp_thin_dupack &&
887 sysctl_tcp_reordering == 3;
888}
889
890static inline void tcp_disable_early_retrans(struct tcp_sock *tp)
891{
892 tp->do_early_retrans = 0;
893}
894
895static inline unsigned int tcp_left_out(const struct tcp_sock *tp)
896{
897 return tp->sacked_out + tp->lost_out;
898}
899
900/* This determines how many packets are "in the network" to the best
901 * of our knowledge. In many cases it is conservative, but where
902 * detailed information is available from the receiver (via SACK
903 * blocks etc.) we can make more aggressive calculations.
904 *
905 * Use this for decisions involving congestion control, use just
906 * tp->packets_out to determine if the send queue is empty or not.
907 *
908 * Read this equation as:
909 *
910 * "Packets sent once on transmission queue" MINUS
911 * "Packets left network, but not honestly ACKed yet" PLUS
912 * "Packets fast retransmitted"
913 */
914static inline unsigned int tcp_packets_in_flight(const struct tcp_sock *tp)
915{
916 return tp->packets_out - tcp_left_out(tp) + tp->retrans_out;
917}
918
919#define TCP_INFINITE_SSTHRESH 0x7fffffff
920
921static inline bool tcp_in_initial_slowstart(const struct tcp_sock *tp)
922{
923 return tp->snd_ssthresh >= TCP_INFINITE_SSTHRESH;
924}
925
926static inline bool tcp_in_cwnd_reduction(const struct sock *sk)
927{
928 return (TCPF_CA_CWR | TCPF_CA_Recovery) &
929 (1 << inet_csk(sk)->icsk_ca_state);
930}
931
932/* If cwnd > ssthresh, we may raise ssthresh to be half-way to cwnd.
933 * The exception is cwnd reduction phase, when cwnd is decreasing towards
934 * ssthresh.
935 */
936static inline __u32 tcp_current_ssthresh(const struct sock *sk)
937{
938 const struct tcp_sock *tp = tcp_sk(sk);
939
940 if (tcp_in_cwnd_reduction(sk))
941 return tp->snd_ssthresh;
942 else
943 return max(tp->snd_ssthresh,
944 ((tp->snd_cwnd >> 1) +
945 (tp->snd_cwnd >> 2)));
946}
947
948/* Use define here intentionally to get WARN_ON location shown at the caller */
949#define tcp_verify_left_out(tp) WARN_ON(tcp_left_out(tp) > tp->packets_out)
950
951void tcp_enter_cwr(struct sock *sk, const int set_ssthresh);
952__u32 tcp_init_cwnd(const struct tcp_sock *tp, const struct dst_entry *dst);
953
954/* The maximum number of MSS of available cwnd for which TSO defers
955 * sending if not using sysctl_tcp_tso_win_divisor.
956 */
957static inline __u32 tcp_max_tso_deferred_mss(const struct tcp_sock *tp)
958{
959 return 3;
960}
961
962/* Slow start with delack produces 3 packets of burst, so that
963 * it is safe "de facto". This will be the default - same as
964 * the default reordering threshold - but if reordering increases,
965 * we must be able to allow cwnd to burst at least this much in order
966 * to not pull it back when holes are filled.
967 */
968static __inline__ __u32 tcp_max_burst(const struct tcp_sock *tp)
969{
970 return tp->reordering;
971}
972
973/* Returns end sequence number of the receiver's advertised window */
974static inline u32 tcp_wnd_end(const struct tcp_sock *tp)
975{
976 return tp->snd_una + tp->snd_wnd;
977}
978bool tcp_is_cwnd_limited(const struct sock *sk, u32 in_flight);
979
980static inline void tcp_check_probe_timer(struct sock *sk)
981{
982 const struct tcp_sock *tp = tcp_sk(sk);
983 const struct inet_connection_sock *icsk = inet_csk(sk);
984
985 if (!tp->packets_out && !icsk->icsk_pending)
986 inet_csk_reset_xmit_timer(sk, ICSK_TIME_PROBE0,
987 icsk->icsk_rto, TCP_RTO_MAX);
988}
989
990static inline void tcp_init_wl(struct tcp_sock *tp, u32 seq)
991{
992 tp->snd_wl1 = seq;
993}
994
995static inline void tcp_update_wl(struct tcp_sock *tp, u32 seq)
996{
997 tp->snd_wl1 = seq;
998}
999
1000/*
1001 * Calculate(/check) TCP checksum
1002 */
1003static inline __sum16 tcp_v4_check(int len, __be32 saddr,
1004 __be32 daddr, __wsum base)
1005{
1006 return csum_tcpudp_magic(saddr,daddr,len,IPPROTO_TCP,base);
1007}
1008
1009static inline __sum16 __tcp_checksum_complete(struct sk_buff *skb)
1010{
1011 return __skb_checksum_complete(skb);
1012}
1013
1014static inline bool tcp_checksum_complete(struct sk_buff *skb)
1015{
1016 return !skb_csum_unnecessary(skb) &&
1017 __tcp_checksum_complete(skb);
1018}
1019
1020/* Prequeue for VJ style copy to user, combined with checksumming. */
1021
1022static inline void tcp_prequeue_init(struct tcp_sock *tp)
1023{
1024 tp->ucopy.task = NULL;
1025 tp->ucopy.len = 0;
1026 tp->ucopy.memory = 0;
1027 skb_queue_head_init(&tp->ucopy.prequeue);
1028#ifdef CONFIG_NET_DMA
1029 tp->ucopy.dma_chan = NULL;
1030 tp->ucopy.wakeup = 0;
1031 tp->ucopy.pinned_list = NULL;
1032 tp->ucopy.dma_cookie = 0;
1033#endif
1034}
1035
1036bool tcp_prequeue(struct sock *sk, struct sk_buff *skb);
1037
1038#undef STATE_TRACE
1039
1040#ifdef STATE_TRACE
1041static const char *statename[]={
1042 "Unused","Established","Syn Sent","Syn Recv",
1043 "Fin Wait 1","Fin Wait 2","Time Wait", "Close",
1044 "Close Wait","Last ACK","Listen","Closing"
1045};
1046#endif
1047void tcp_set_state(struct sock *sk, int state);
1048
1049void tcp_done(struct sock *sk);
1050
1051static inline void tcp_sack_reset(struct tcp_options_received *rx_opt)
1052{
1053 rx_opt->dsack = 0;
1054 rx_opt->num_sacks = 0;
1055}
1056
1057u32 tcp_default_init_rwnd(u32 mss);
1058
1059/* Determine a window scaling and initial window to offer. */
1060void tcp_select_initial_window(int __space, __u32 mss, __u32 *rcv_wnd,
1061 __u32 *window_clamp, int wscale_ok,
1062 __u8 *rcv_wscale, __u32 init_rcv_wnd);
1063
1064static inline int tcp_win_from_space(int space)
1065{
1066 return sysctl_tcp_adv_win_scale<=0 ?
1067 (space>>(-sysctl_tcp_adv_win_scale)) :
1068 space - (space>>sysctl_tcp_adv_win_scale);
1069}
1070
1071/* Note: caller must be prepared to deal with negative returns */
1072static inline int tcp_space(const struct sock *sk)
1073{
1074 return tcp_win_from_space(sk->sk_rcvbuf -
1075 atomic_read(&sk->sk_rmem_alloc));
1076}
1077
1078static inline int tcp_full_space(const struct sock *sk)
1079{
1080 return tcp_win_from_space(sk->sk_rcvbuf);
1081}
1082
1083static inline void tcp_openreq_init(struct request_sock *req,
1084 struct tcp_options_received *rx_opt,
1085 struct sk_buff *skb)
1086{
1087 struct inet_request_sock *ireq = inet_rsk(req);
1088
1089 req->rcv_wnd = 0; /* So that tcp_send_synack() knows! */
1090 req->cookie_ts = 0;
1091 tcp_rsk(req)->rcv_isn = TCP_SKB_CB(skb)->seq;
1092 tcp_rsk(req)->rcv_nxt = TCP_SKB_CB(skb)->seq + 1;
1093 tcp_rsk(req)->snt_synack = 0;
1094 req->mss = rx_opt->mss_clamp;
1095 req->ts_recent = rx_opt->saw_tstamp ? rx_opt->rcv_tsval : 0;
1096 ireq->tstamp_ok = rx_opt->tstamp_ok;
1097 ireq->sack_ok = rx_opt->sack_ok;
1098 ireq->snd_wscale = rx_opt->snd_wscale;
1099 ireq->wscale_ok = rx_opt->wscale_ok;
1100 ireq->acked = 0;
1101 ireq->ecn_ok = 0;
1102 ireq->ir_rmt_port = tcp_hdr(skb)->source;
1103 ireq->ir_num = ntohs(tcp_hdr(skb)->dest);
1104}
1105
1106void tcp_enter_memory_pressure(struct sock *sk);
1107
1108static inline int keepalive_intvl_when(const struct tcp_sock *tp)
1109{
1110 return tp->keepalive_intvl ? : sysctl_tcp_keepalive_intvl;
1111}
1112
1113static inline int keepalive_time_when(const struct tcp_sock *tp)
1114{
1115 return tp->keepalive_time ? : sysctl_tcp_keepalive_time;
1116}
1117
1118static inline int keepalive_probes(const struct tcp_sock *tp)
1119{
1120 return tp->keepalive_probes ? : sysctl_tcp_keepalive_probes;
1121}
1122
1123static inline u32 keepalive_time_elapsed(const struct tcp_sock *tp)
1124{
1125 const struct inet_connection_sock *icsk = &tp->inet_conn;
1126
1127 return min_t(u32, tcp_time_stamp - icsk->icsk_ack.lrcvtime,
1128 tcp_time_stamp - tp->rcv_tstamp);
1129}
1130
1131static inline int tcp_fin_time(const struct sock *sk)
1132{
1133 int fin_timeout = tcp_sk(sk)->linger2 ? : sysctl_tcp_fin_timeout;
1134 const int rto = inet_csk(sk)->icsk_rto;
1135
1136 if (fin_timeout < (rto << 2) - (rto >> 1))
1137 fin_timeout = (rto << 2) - (rto >> 1);
1138
1139 return fin_timeout;
1140}
1141
1142static inline bool tcp_paws_check(const struct tcp_options_received *rx_opt,
1143 int paws_win)
1144{
1145 if ((s32)(rx_opt->ts_recent - rx_opt->rcv_tsval) <= paws_win)
1146 return true;
1147 if (unlikely(get_seconds() >= rx_opt->ts_recent_stamp + TCP_PAWS_24DAYS))
1148 return true;
1149 /*
1150 * Some OSes send SYN and SYNACK messages with tsval=0 tsecr=0,
1151 * then following tcp messages have valid values. Ignore 0 value,
1152 * or else 'negative' tsval might forbid us to accept their packets.
1153 */
1154 if (!rx_opt->ts_recent)
1155 return true;
1156 return false;
1157}
1158
1159static inline bool tcp_paws_reject(const struct tcp_options_received *rx_opt,
1160 int rst)
1161{
1162 if (tcp_paws_check(rx_opt, 0))
1163 return false;
1164
1165 /* RST segments are not recommended to carry timestamp,
1166 and, if they do, it is recommended to ignore PAWS because
1167 "their cleanup function should take precedence over timestamps."
1168 Certainly, it is mistake. It is necessary to understand the reasons
1169 of this constraint to relax it: if peer reboots, clock may go
1170 out-of-sync and half-open connections will not be reset.
1171 Actually, the problem would be not existing if all
1172 the implementations followed draft about maintaining clock
1173 via reboots. Linux-2.2 DOES NOT!
1174
1175 However, we can relax time bounds for RST segments to MSL.
1176 */
1177 if (rst && get_seconds() >= rx_opt->ts_recent_stamp + TCP_PAWS_MSL)
1178 return false;
1179 return true;
1180}
1181
1182static inline void tcp_mib_init(struct net *net)
1183{
1184 /* See RFC 2012 */
1185 TCP_ADD_STATS_USER(net, TCP_MIB_RTOALGORITHM, 1);
1186 TCP_ADD_STATS_USER(net, TCP_MIB_RTOMIN, TCP_RTO_MIN*1000/HZ);
1187 TCP_ADD_STATS_USER(net, TCP_MIB_RTOMAX, TCP_RTO_MAX*1000/HZ);
1188 TCP_ADD_STATS_USER(net, TCP_MIB_MAXCONN, -1);
1189}
1190
1191/* from STCP */
1192static inline void tcp_clear_retrans_hints_partial(struct tcp_sock *tp)
1193{
1194 tp->lost_skb_hint = NULL;
1195}
1196
1197static inline void tcp_clear_all_retrans_hints(struct tcp_sock *tp)
1198{
1199 tcp_clear_retrans_hints_partial(tp);
1200 tp->retransmit_skb_hint = NULL;
1201}
1202
1203/* MD5 Signature */
1204struct crypto_hash;
1205
1206union tcp_md5_addr {
1207 struct in_addr a4;
1208#if IS_ENABLED(CONFIG_IPV6)
1209 struct in6_addr a6;
1210#endif
1211};
1212
1213/* - key database */
1214struct tcp_md5sig_key {
1215 struct hlist_node node;
1216 u8 keylen;
1217 u8 family; /* AF_INET or AF_INET6 */
1218 union tcp_md5_addr addr;
1219 u8 key[TCP_MD5SIG_MAXKEYLEN];
1220 struct rcu_head rcu;
1221};
1222
1223/* - sock block */
1224struct tcp_md5sig_info {
1225 struct hlist_head head;
1226 struct rcu_head rcu;
1227};
1228
1229/* - pseudo header */
1230struct tcp4_pseudohdr {
1231 __be32 saddr;
1232 __be32 daddr;
1233 __u8 pad;
1234 __u8 protocol;
1235 __be16 len;
1236};
1237
1238struct tcp6_pseudohdr {
1239 struct in6_addr saddr;
1240 struct in6_addr daddr;
1241 __be32 len;
1242 __be32 protocol; /* including padding */
1243};
1244
1245union tcp_md5sum_block {
1246 struct tcp4_pseudohdr ip4;
1247#if IS_ENABLED(CONFIG_IPV6)
1248 struct tcp6_pseudohdr ip6;
1249#endif
1250};
1251
1252/* - pool: digest algorithm, hash description and scratch buffer */
1253struct tcp_md5sig_pool {
1254 struct hash_desc md5_desc;
1255 union tcp_md5sum_block md5_blk;
1256};
1257
1258/* - functions */
1259int tcp_v4_md5_hash_skb(char *md5_hash, struct tcp_md5sig_key *key,
1260 const struct sock *sk, const struct request_sock *req,
1261 const struct sk_buff *skb);
1262int tcp_md5_do_add(struct sock *sk, const union tcp_md5_addr *addr,
1263 int family, const u8 *newkey, u8 newkeylen, gfp_t gfp);
1264int tcp_md5_do_del(struct sock *sk, const union tcp_md5_addr *addr,
1265 int family);
1266struct tcp_md5sig_key *tcp_v4_md5_lookup(struct sock *sk,
1267 struct sock *addr_sk);
1268
1269#ifdef CONFIG_TCP_MD5SIG
1270struct tcp_md5sig_key *tcp_md5_do_lookup(struct sock *sk,
1271 const union tcp_md5_addr *addr,
1272 int family);
1273#define tcp_twsk_md5_key(twsk) ((twsk)->tw_md5_key)
1274#else
1275static inline struct tcp_md5sig_key *tcp_md5_do_lookup(struct sock *sk,
1276 const union tcp_md5_addr *addr,
1277 int family)
1278{
1279 return NULL;
1280}
1281#define tcp_twsk_md5_key(twsk) NULL
1282#endif
1283
1284bool tcp_alloc_md5sig_pool(void);
1285
1286struct tcp_md5sig_pool *tcp_get_md5sig_pool(void);
1287static inline void tcp_put_md5sig_pool(void)
1288{
1289 local_bh_enable();
1290}
1291
1292int tcp_md5_hash_header(struct tcp_md5sig_pool *, const struct tcphdr *);
1293int tcp_md5_hash_skb_data(struct tcp_md5sig_pool *, const struct sk_buff *,
1294 unsigned int header_len);
1295int tcp_md5_hash_key(struct tcp_md5sig_pool *hp,
1296 const struct tcp_md5sig_key *key);
1297
1298/* From tcp_fastopen.c */
1299void tcp_fastopen_cache_get(struct sock *sk, u16 *mss,
1300 struct tcp_fastopen_cookie *cookie, int *syn_loss,
1301 unsigned long *last_syn_loss);
1302void tcp_fastopen_cache_set(struct sock *sk, u16 mss,
1303 struct tcp_fastopen_cookie *cookie, bool syn_lost);
1304struct tcp_fastopen_request {
1305 /* Fast Open cookie. Size 0 means a cookie request */
1306 struct tcp_fastopen_cookie cookie;
1307 struct msghdr *data; /* data in MSG_FASTOPEN */
1308 size_t size;
1309 int copied; /* queued in tcp_connect() */
1310};
1311void tcp_free_fastopen_req(struct tcp_sock *tp);
1312
1313extern struct tcp_fastopen_context __rcu *tcp_fastopen_ctx;
1314int tcp_fastopen_reset_cipher(void *key, unsigned int len);
1315void tcp_fastopen_cookie_gen(__be32 src, __be32 dst,
1316 struct tcp_fastopen_cookie *foc);
1317void tcp_fastopen_init_key_once(bool publish);
1318#define TCP_FASTOPEN_KEY_LENGTH 16
1319
1320/* Fastopen key context */
1321struct tcp_fastopen_context {
1322 struct crypto_cipher *tfm;
1323 __u8 key[TCP_FASTOPEN_KEY_LENGTH];
1324 struct rcu_head rcu;
1325};
1326
1327/* write queue abstraction */
1328static inline void tcp_write_queue_purge(struct sock *sk)
1329{
1330 struct sk_buff *skb;
1331
1332 while ((skb = __skb_dequeue(&sk->sk_write_queue)) != NULL)
1333 sk_wmem_free_skb(sk, skb);
1334 sk_mem_reclaim(sk);
1335 tcp_clear_all_retrans_hints(tcp_sk(sk));
1336}
1337
1338static inline struct sk_buff *tcp_write_queue_head(const struct sock *sk)
1339{
1340 return skb_peek(&sk->sk_write_queue);
1341}
1342
1343static inline struct sk_buff *tcp_write_queue_tail(const struct sock *sk)
1344{
1345 return skb_peek_tail(&sk->sk_write_queue);
1346}
1347
1348static inline struct sk_buff *tcp_write_queue_next(const struct sock *sk,
1349 const struct sk_buff *skb)
1350{
1351 return skb_queue_next(&sk->sk_write_queue, skb);
1352}
1353
1354static inline struct sk_buff *tcp_write_queue_prev(const struct sock *sk,
1355 const struct sk_buff *skb)
1356{
1357 return skb_queue_prev(&sk->sk_write_queue, skb);
1358}
1359
1360#define tcp_for_write_queue(skb, sk) \
1361 skb_queue_walk(&(sk)->sk_write_queue, skb)
1362
1363#define tcp_for_write_queue_from(skb, sk) \
1364 skb_queue_walk_from(&(sk)->sk_write_queue, skb)
1365
1366#define tcp_for_write_queue_from_safe(skb, tmp, sk) \
1367 skb_queue_walk_from_safe(&(sk)->sk_write_queue, skb, tmp)
1368
1369static inline struct sk_buff *tcp_send_head(const struct sock *sk)
1370{
1371 return sk->sk_send_head;
1372}
1373
1374static inline bool tcp_skb_is_last(const struct sock *sk,
1375 const struct sk_buff *skb)
1376{
1377 return skb_queue_is_last(&sk->sk_write_queue, skb);
1378}
1379
1380static inline void tcp_advance_send_head(struct sock *sk, const struct sk_buff *skb)
1381{
1382 if (tcp_skb_is_last(sk, skb))
1383 sk->sk_send_head = NULL;
1384 else
1385 sk->sk_send_head = tcp_write_queue_next(sk, skb);
1386}
1387
1388static inline void tcp_check_send_head(struct sock *sk, struct sk_buff *skb_unlinked)
1389{
1390 if (sk->sk_send_head == skb_unlinked)
1391 sk->sk_send_head = NULL;
1392}
1393
1394static inline void tcp_init_send_head(struct sock *sk)
1395{
1396 sk->sk_send_head = NULL;
1397}
1398
1399static inline void __tcp_add_write_queue_tail(struct sock *sk, struct sk_buff *skb)
1400{
1401 __skb_queue_tail(&sk->sk_write_queue, skb);
1402}
1403
1404static inline void tcp_add_write_queue_tail(struct sock *sk, struct sk_buff *skb)
1405{
1406 __tcp_add_write_queue_tail(sk, skb);
1407
1408 /* Queue it, remembering where we must start sending. */
1409 if (sk->sk_send_head == NULL) {
1410 sk->sk_send_head = skb;
1411
1412 if (tcp_sk(sk)->highest_sack == NULL)
1413 tcp_sk(sk)->highest_sack = skb;
1414 }
1415}
1416
1417static inline void __tcp_add_write_queue_head(struct sock *sk, struct sk_buff *skb)
1418{
1419 __skb_queue_head(&sk->sk_write_queue, skb);
1420}
1421
1422/* Insert buff after skb on the write queue of sk. */
1423static inline void tcp_insert_write_queue_after(struct sk_buff *skb,
1424 struct sk_buff *buff,
1425 struct sock *sk)
1426{
1427 __skb_queue_after(&sk->sk_write_queue, skb, buff);
1428}
1429
1430/* Insert new before skb on the write queue of sk. */
1431static inline void tcp_insert_write_queue_before(struct sk_buff *new,
1432 struct sk_buff *skb,
1433 struct sock *sk)
1434{
1435 __skb_queue_before(&sk->sk_write_queue, skb, new);
1436
1437 if (sk->sk_send_head == skb)
1438 sk->sk_send_head = new;
1439}
1440
1441static inline void tcp_unlink_write_queue(struct sk_buff *skb, struct sock *sk)
1442{
1443 __skb_unlink(skb, &sk->sk_write_queue);
1444}
1445
1446static inline bool tcp_write_queue_empty(struct sock *sk)
1447{
1448 return skb_queue_empty(&sk->sk_write_queue);
1449}
1450
1451static inline void tcp_push_pending_frames(struct sock *sk)
1452{
1453 if (tcp_send_head(sk)) {
1454 struct tcp_sock *tp = tcp_sk(sk);
1455
1456 __tcp_push_pending_frames(sk, tcp_current_mss(sk), tp->nonagle);
1457 }
1458}
1459
1460/* Start sequence of the skb just after the highest skb with SACKed
1461 * bit, valid only if sacked_out > 0 or when the caller has ensured
1462 * validity by itself.
1463 */
1464static inline u32 tcp_highest_sack_seq(struct tcp_sock *tp)
1465{
1466 if (!tp->sacked_out)
1467 return tp->snd_una;
1468
1469 if (tp->highest_sack == NULL)
1470 return tp->snd_nxt;
1471
1472 return TCP_SKB_CB(tp->highest_sack)->seq;
1473}
1474
1475static inline void tcp_advance_highest_sack(struct sock *sk, struct sk_buff *skb)
1476{
1477 tcp_sk(sk)->highest_sack = tcp_skb_is_last(sk, skb) ? NULL :
1478 tcp_write_queue_next(sk, skb);
1479}
1480
1481static inline struct sk_buff *tcp_highest_sack(struct sock *sk)
1482{
1483 return tcp_sk(sk)->highest_sack;
1484}
1485
1486static inline void tcp_highest_sack_reset(struct sock *sk)
1487{
1488 tcp_sk(sk)->highest_sack = tcp_write_queue_head(sk);
1489}
1490
1491/* Called when old skb is about to be deleted (to be combined with new skb) */
1492static inline void tcp_highest_sack_combine(struct sock *sk,
1493 struct sk_buff *old,
1494 struct sk_buff *new)
1495{
1496 if (tcp_sk(sk)->sacked_out && (old == tcp_sk(sk)->highest_sack))
1497 tcp_sk(sk)->highest_sack = new;
1498}
1499
1500/* Determines whether this is a thin stream (which may suffer from
1501 * increased latency). Used to trigger latency-reducing mechanisms.
1502 */
1503static inline bool tcp_stream_is_thin(struct tcp_sock *tp)
1504{
1505 return tp->packets_out < 4 && !tcp_in_initial_slowstart(tp);
1506}
1507
1508/* /proc */
1509enum tcp_seq_states {
1510 TCP_SEQ_STATE_LISTENING,
1511 TCP_SEQ_STATE_OPENREQ,
1512 TCP_SEQ_STATE_ESTABLISHED,
1513};
1514
1515int tcp_seq_open(struct inode *inode, struct file *file);
1516
1517struct tcp_seq_afinfo {
1518 char *name;
1519 sa_family_t family;
1520 const struct file_operations *seq_fops;
1521 struct seq_operations seq_ops;
1522};
1523
1524struct tcp_iter_state {
1525 struct seq_net_private p;
1526 sa_family_t family;
1527 enum tcp_seq_states state;
1528 struct sock *syn_wait_sk;
1529 int bucket, offset, sbucket, num;
1530 kuid_t uid;
1531 loff_t last_pos;
1532};
1533
1534int tcp_proc_register(struct net *net, struct tcp_seq_afinfo *afinfo);
1535void tcp_proc_unregister(struct net *net, struct tcp_seq_afinfo *afinfo);
1536
1537extern struct request_sock_ops tcp_request_sock_ops;
1538extern struct request_sock_ops tcp6_request_sock_ops;
1539
1540void tcp_v4_destroy_sock(struct sock *sk);
1541
1542struct sk_buff *tcp_gso_segment(struct sk_buff *skb,
1543 netdev_features_t features);
1544struct sk_buff **tcp_gro_receive(struct sk_buff **head, struct sk_buff *skb);
1545int tcp_gro_complete(struct sk_buff *skb);
1546
1547void __tcp_v4_send_check(struct sk_buff *skb, __be32 saddr, __be32 daddr);
1548
1549static inline u32 tcp_notsent_lowat(const struct tcp_sock *tp)
1550{
1551 return tp->notsent_lowat ?: sysctl_tcp_notsent_lowat;
1552}
1553
1554static inline bool tcp_stream_memory_free(const struct sock *sk)
1555{
1556 const struct tcp_sock *tp = tcp_sk(sk);
1557 u32 notsent_bytes = tp->write_seq - tp->snd_nxt;
1558
1559 return notsent_bytes < tcp_notsent_lowat(tp);
1560}
1561
1562#ifdef CONFIG_PROC_FS
1563int tcp4_proc_init(void);
1564void tcp4_proc_exit(void);
1565#endif
1566
1567/* TCP af-specific functions */
1568struct tcp_sock_af_ops {
1569#ifdef CONFIG_TCP_MD5SIG
1570 struct tcp_md5sig_key *(*md5_lookup) (struct sock *sk,
1571 struct sock *addr_sk);
1572 int (*calc_md5_hash) (char *location,
1573 struct tcp_md5sig_key *md5,
1574 const struct sock *sk,
1575 const struct request_sock *req,
1576 const struct sk_buff *skb);
1577 int (*md5_parse) (struct sock *sk,
1578 char __user *optval,
1579 int optlen);
1580#endif
1581};
1582
1583struct tcp_request_sock_ops {
1584#ifdef CONFIG_TCP_MD5SIG
1585 struct tcp_md5sig_key *(*md5_lookup) (struct sock *sk,
1586 struct request_sock *req);
1587 int (*calc_md5_hash) (char *location,
1588 struct tcp_md5sig_key *md5,
1589 const struct sock *sk,
1590 const struct request_sock *req,
1591 const struct sk_buff *skb);
1592#endif
1593};
1594
1595int tcpv4_offload_init(void);
1596
1597void tcp_v4_init(void);
1598void tcp_init(void);
1599
1600#endif /* _TCP_H */