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[SOCK]: Introduce sk_clone
[linux-2.6-block.git] / include / net / tcp.h
CommitLineData
1da177e4
LT		 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 *
02c30a84 10 * Authors: Ross Biro
1da177e4
LT		 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/* Cancel timers, when they are not required. */
25#undef TCP_CLEAR_TIMERS
26
27#include <linux/config.h>
28#include <linux/list.h>
29#include <linux/tcp.h>
30#include <linux/slab.h>
31#include <linux/cache.h>
32#include <linux/percpu.h>
77d8bf9c 33#include <net/inet_hashtables.h>
1da177e4 34#include <net/checksum.h>
2e6599cb 35#include <net/request_sock.h>
1da177e4
LT		 36#include <net/sock.h>
37#include <net/snmp.h>
38#include <net/ip.h>
c752f073
ACM		 39#include <net/tcp_states.h>
40
1da177e4
LT		 41#include <linux/seq_file.h>
42
6e04e021 43extern struct inet_hashinfo tcp_hashinfo;
1da177e4 44
1da177e4
LT		 45extern atomic_t tcp_orphan_count;
46extern int tcp_tw_count;
47extern void tcp_time_wait(struct sock *sk, int state, int timeo);
8feaf0c0 48extern void tcp_tw_deschedule(struct inet_timewait_sock *tw);
1da177e4 49
1da177e4
LT		 50#define MAX_TCP_HEADER (128 + MAX_HEADER)
51
52/*
53 * Never offer a window over 32767 without using window scaling. Some
54 * poor stacks do signed 16bit maths!
55 */
56#define MAX_TCP_WINDOW 32767U
57
58/* Minimal accepted MSS. It is (60+60+8) - (20+20). */
59#define TCP_MIN_MSS 88U
60
61/* Minimal RCV_MSS. */
62#define TCP_MIN_RCVMSS 536U
63
64/* After receiving this amount of duplicate ACKs fast retransmit starts. */
65#define TCP_FASTRETRANS_THRESH 3
66
67/* Maximal reordering. */
68#define TCP_MAX_REORDERING 127
69
70/* Maximal number of ACKs sent quickly to accelerate slow-start. */
71#define TCP_MAX_QUICKACKS 16U
72
73/* urg_data states */
74#define TCP_URG_VALID 0x0100
75#define TCP_URG_NOTYET 0x0200
76#define TCP_URG_READ 0x0400
77
78#define TCP_RETR1 3 /*
79 * This is how many retries it does before it
80 * tries to figure out if the gateway is
81 * down. Minimal RFC value is 3; it corresponds
82 * to ~3sec-8min depending on RTO.
83 */
84
85#define TCP_RETR2 15 /*
86 * This should take at least
87 * 90 minutes to time out.
88 * RFC1122 says that the limit is 100 sec.
89 * 15 is ~13-30min depending on RTO.
90 */
91
92#define TCP_SYN_RETRIES 5 /* number of times to retry active opening a
93 * connection: ~180sec is RFC minumum */
94
95#define TCP_SYNACK_RETRIES 5 /* number of times to retry passive opening a
96 * connection: ~180sec is RFC minumum */
97
98
99#define TCP_ORPHAN_RETRIES 7 /* number of times to retry on an orphaned
100 * socket. 7 is ~50sec-16min.
101 */
102
103
104#define TCP_TIMEWAIT_LEN (60*HZ) /* how long to wait to destroy TIME-WAIT
105 * state, about 60 seconds */
106#define TCP_FIN_TIMEOUT TCP_TIMEWAIT_LEN
107 /* BSD style FIN_WAIT2 deadlock breaker.
108 * It used to be 3min, new value is 60sec,
109 * to combine FIN-WAIT-2 timeout with
110 * TIME-WAIT timer.
111 */
112
113#define TCP_DELACK_MAX ((unsigned)(HZ/5)) /* maximal time to delay before sending an ACK */
114#if HZ >= 100
115#define TCP_DELACK_MIN ((unsigned)(HZ/25)) /* minimal time to delay before sending an ACK */
116#define TCP_ATO_MIN ((unsigned)(HZ/25))
117#else
118#define TCP_DELACK_MIN 4U
119#define TCP_ATO_MIN 4U
120#endif
121#define TCP_RTO_MAX ((unsigned)(120*HZ))
122#define TCP_RTO_MIN ((unsigned)(HZ/5))
123#define TCP_TIMEOUT_INIT ((unsigned)(3*HZ)) /* RFC 1122 initial RTO value */
124
125#define TCP_RESOURCE_PROBE_INTERVAL ((unsigned)(HZ/2U)) /* Maximal interval between probes
126 * for local resources.
127 */
128
129#define TCP_KEEPALIVE_TIME (120*60*HZ) /* two hours */
130#define TCP_KEEPALIVE_PROBES 9 /* Max of 9 keepalive probes */
131#define TCP_KEEPALIVE_INTVL (75*HZ)
132
133#define MAX_TCP_KEEPIDLE 32767
134#define MAX_TCP_KEEPINTVL 32767
135#define MAX_TCP_KEEPCNT 127
136#define MAX_TCP_SYNCNT 127
137
138#define TCP_SYNQ_INTERVAL (HZ/5) /* Period of SYNACK timer */
139#define TCP_SYNQ_HSIZE 512 /* Size of SYNACK hash table */
140
141#define TCP_PAWS_24DAYS (60 * 60 * 24 * 24)
142#define TCP_PAWS_MSL 60 /* Per-host timestamps are invalidated
143 * after this time. It should be equal
144 * (or greater than) TCP_TIMEWAIT_LEN
145 * to provide reliability equal to one
146 * provided by timewait state.
147 */
148#define TCP_PAWS_WINDOW 1 /* Replay window for per-host
149 * timestamps. It must be less than
150 * minimal timewait lifetime.
151 */
152
153#define TCP_TW_RECYCLE_SLOTS_LOG 5
154#define TCP_TW_RECYCLE_SLOTS (1<<TCP_TW_RECYCLE_SLOTS_LOG)
155
156/* If time > 4sec, it is "slow" path, no recycling is required,
157 so that we select tick to get range about 4 seconds.
158 */
159
160#if HZ <= 16 || HZ > 4096
161# error Unsupported: HZ <= 16 or HZ > 4096
162#elif HZ <= 32
163# define TCP_TW_RECYCLE_TICK (5+2-TCP_TW_RECYCLE_SLOTS_LOG)
164#elif HZ <= 64
165# define TCP_TW_RECYCLE_TICK (6+2-TCP_TW_RECYCLE_SLOTS_LOG)
166#elif HZ <= 128
167# define TCP_TW_RECYCLE_TICK (7+2-TCP_TW_RECYCLE_SLOTS_LOG)
168#elif HZ <= 256
169# define TCP_TW_RECYCLE_TICK (8+2-TCP_TW_RECYCLE_SLOTS_LOG)
170#elif HZ <= 512
171# define TCP_TW_RECYCLE_TICK (9+2-TCP_TW_RECYCLE_SLOTS_LOG)
172#elif HZ <= 1024
173# define TCP_TW_RECYCLE_TICK (10+2-TCP_TW_RECYCLE_SLOTS_LOG)
174#elif HZ <= 2048
175# define TCP_TW_RECYCLE_TICK (11+2-TCP_TW_RECYCLE_SLOTS_LOG)
176#else
177# define TCP_TW_RECYCLE_TICK (12+2-TCP_TW_RECYCLE_SLOTS_LOG)
178#endif
1da177e4
LT		 179/*
180 * TCP option
181 */
182
183#define TCPOPT_NOP 1 /* Padding */
184#define TCPOPT_EOL 0 /* End of options */
185#define TCPOPT_MSS 2 /* Segment size negotiating */
186#define TCPOPT_WINDOW 3 /* Window scaling */
187#define TCPOPT_SACK_PERM 4 /* SACK Permitted */
188#define TCPOPT_SACK 5 /* SACK Block */
189#define TCPOPT_TIMESTAMP 8 /* Better RTT estimations/PAWS */
190
191/*
192 * TCP option lengths
193 */
194
195#define TCPOLEN_MSS 4
196#define TCPOLEN_WINDOW 3
197#define TCPOLEN_SACK_PERM 2
198#define TCPOLEN_TIMESTAMP 10
199
200/* But this is what stacks really send out. */
201#define TCPOLEN_TSTAMP_ALIGNED 12
202#define TCPOLEN_WSCALE_ALIGNED 4
203#define TCPOLEN_SACKPERM_ALIGNED 4
204#define TCPOLEN_SACK_BASE 2
205#define TCPOLEN_SACK_BASE_ALIGNED 4
206#define TCPOLEN_SACK_PERBLOCK 8
207
208#define TCP_TIME_RETRANS 1 /* Retransmit timer */
209#define TCP_TIME_DACK 2 /* Delayed ack timer */
210#define TCP_TIME_PROBE0 3 /* Zero window probe timer */
211#define TCP_TIME_KEEPOPEN 4 /* Keepalive timer */
212
213/* Flags in tp->nonagle */
214#define TCP_NAGLE_OFF 1 /* Nagle's algo is disabled */
215#define TCP_NAGLE_CORK 2 /* Socket is corked */
216#define TCP_NAGLE_PUSH 4 /* Cork is overriden for already queued data */
217
218/* sysctl variables for tcp */
1da177e4
LT		 219extern int sysctl_tcp_timestamps;
220extern int sysctl_tcp_window_scaling;
221extern int sysctl_tcp_sack;
222extern int sysctl_tcp_fin_timeout;
223extern int sysctl_tcp_tw_recycle;
224extern int sysctl_tcp_keepalive_time;
225extern int sysctl_tcp_keepalive_probes;
226extern int sysctl_tcp_keepalive_intvl;
227extern int sysctl_tcp_syn_retries;
228extern int sysctl_tcp_synack_retries;
229extern int sysctl_tcp_retries1;
230extern int sysctl_tcp_retries2;
231extern int sysctl_tcp_orphan_retries;
232extern int sysctl_tcp_syncookies;
233extern int sysctl_tcp_retrans_collapse;
234extern int sysctl_tcp_stdurg;
235extern int sysctl_tcp_rfc1337;
236extern int sysctl_tcp_abort_on_overflow;
237extern int sysctl_tcp_max_orphans;
238extern int sysctl_tcp_max_tw_buckets;
239extern int sysctl_tcp_fack;
240extern int sysctl_tcp_reordering;
241extern int sysctl_tcp_ecn;
242extern int sysctl_tcp_dsack;
243extern int sysctl_tcp_mem[3];
244extern int sysctl_tcp_wmem[3];
245extern int sysctl_tcp_rmem[3];
246extern int sysctl_tcp_app_win;
247extern int sysctl_tcp_adv_win_scale;
248extern int sysctl_tcp_tw_reuse;
249extern int sysctl_tcp_frto;
250extern int sysctl_tcp_low_latency;
1da177e4 251extern int sysctl_tcp_nometrics_save;
1da177e4
LT		 252extern int sysctl_tcp_moderate_rcvbuf;
253extern int sysctl_tcp_tso_win_divisor;
254
255extern atomic_t tcp_memory_allocated;
256extern atomic_t tcp_sockets_allocated;
257extern int tcp_memory_pressure;
258
1da177e4
LT		 259#if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
260#define TCP_INET_FAMILY(fam) ((fam) == AF_INET)
261#else
262#define TCP_INET_FAMILY(fam) 1
263#endif
264
265/*
266 * Pointers to address related TCP functions
267 * (i.e. things that depend on the address family)
268 */
269
270struct tcp_func {
271 int (*queue_xmit) (struct sk_buff *skb,
272 int ipfragok);
273
274 void (*send_check) (struct sock *sk,
275 struct tcphdr *th,
276 int len,
277 struct sk_buff *skb);
278
279 int (*rebuild_header) (struct sock *sk);
280
281 int (*conn_request) (struct sock *sk,
282 struct sk_buff *skb);
283
284 struct sock * (*syn_recv_sock) (struct sock *sk,
285 struct sk_buff *skb,
60236fdd 286 struct request_sock *req,
1da177e4
LT		 287 struct dst_entry *dst);
288
289 int (*remember_stamp) (struct sock *sk);
290
291 __u16 net_header_len;
292
293 int (*setsockopt) (struct sock *sk,
294 int level,
295 int optname,
296 char __user *optval,
297 int optlen);
298
299 int (*getsockopt) (struct sock *sk,
300 int level,
301 int optname,
302 char __user *optval,
303 int __user *optlen);
304
305
306 void (*addr2sockaddr) (struct sock *sk,
307 struct sockaddr *);
308
309 int sockaddr_len;
310};
311
312/*
313 * The next routines deal with comparing 32 bit unsigned ints
314 * and worry about wraparound (automatic with unsigned arithmetic).
315 */
316
317static inline int before(__u32 seq1, __u32 seq2)
318{
319 return (__s32)(seq1-seq2) < 0;
320}
321
322static inline int after(__u32 seq1, __u32 seq2)
323{
324 return (__s32)(seq2-seq1) < 0;
325}
326
327
328/* is s2<=s1<=s3 ? */
329static inline int between(__u32 seq1, __u32 seq2, __u32 seq3)
330{
331 return seq3 - seq2 >= seq1 - seq2;
332}
333
334
335extern struct proto tcp_prot;
336
337DECLARE_SNMP_STAT(struct tcp_mib, tcp_statistics);
338#define TCP_INC_STATS(field) SNMP_INC_STATS(tcp_statistics, field)
339#define TCP_INC_STATS_BH(field) SNMP_INC_STATS_BH(tcp_statistics, field)
340#define TCP_INC_STATS_USER(field) SNMP_INC_STATS_USER(tcp_statistics, field)
341#define TCP_DEC_STATS(field) SNMP_DEC_STATS(tcp_statistics, field)
342#define TCP_ADD_STATS_BH(field, val) SNMP_ADD_STATS_BH(tcp_statistics, field, val)
343#define TCP_ADD_STATS_USER(field, val) SNMP_ADD_STATS_USER(tcp_statistics, field, val)
344
1da177e4
LT		 345extern void tcp_v4_err(struct sk_buff *skb, u32);
346
347extern void tcp_shutdown (struct sock *sk, int how);
348
349extern int tcp_v4_rcv(struct sk_buff *skb);
350
351extern int tcp_v4_remember_stamp(struct sock *sk);
352
8feaf0c0 353extern int tcp_v4_tw_remember_stamp(struct inet_timewait_sock *tw);
1da177e4
LT		 354
355extern int tcp_sendmsg(struct kiocb *iocb, struct sock *sk,
356 struct msghdr *msg, size_t size);
357extern ssize_t tcp_sendpage(struct socket *sock, struct page *page, int offset, size_t size, int flags);
358
359extern int tcp_ioctl(struct sock *sk,
360 int cmd,
361 unsigned long arg);
362
363extern int tcp_rcv_state_process(struct sock *sk,
364 struct sk_buff *skb,
365 struct tcphdr *th,
366 unsigned len);
367
368extern int tcp_rcv_established(struct sock *sk,
369 struct sk_buff *skb,
370 struct tcphdr *th,
371 unsigned len);
372
373extern void tcp_rcv_space_adjust(struct sock *sk);
374
375enum tcp_ack_state_t
376{
377 TCP_ACK_SCHED = 1,
378 TCP_ACK_TIMER = 2,
379 TCP_ACK_PUSHED= 4
380};
381
382static inline void tcp_schedule_ack(struct tcp_sock *tp)
383{
384 tp->ack.pending |= TCP_ACK_SCHED;
385}
386
387static inline int tcp_ack_scheduled(struct tcp_sock *tp)
388{
389 return tp->ack.pending&TCP_ACK_SCHED;
390}
391
fc6415bc 392static __inline__ void tcp_dec_quickack_mode(struct tcp_sock *tp, unsigned int pkts)
1da177e4 393{
fc6415bc
DM		 394 if (tp->ack.quick) {
395 if (pkts >= tp->ack.quick) {
396 tp->ack.quick = 0;
397
398 /* Leaving quickack mode we deflate ATO. */
399 tp->ack.ato = TCP_ATO_MIN;
400 } else
401 tp->ack.quick -= pkts;
1da177e4
LT		 402 }
403}
404
405extern void tcp_enter_quickack_mode(struct tcp_sock *tp);
406
407static __inline__ void tcp_delack_init(struct tcp_sock *tp)
408{
409 memset(&tp->ack, 0, sizeof(tp->ack));
410}
411
412static inline void tcp_clear_options(struct tcp_options_received *rx_opt)
413{
414 rx_opt->tstamp_ok = rx_opt->sack_ok = rx_opt->wscale_ok = rx_opt->snd_wscale = 0;
415}
416
417enum tcp_tw_status
418{
419 TCP_TW_SUCCESS = 0,
420 TCP_TW_RST = 1,
421 TCP_TW_ACK = 2,
422 TCP_TW_SYN = 3
423};
424
425
8feaf0c0 426extern enum tcp_tw_status tcp_timewait_state_process(struct inet_timewait_sock *tw,
1da177e4 427 struct sk_buff *skb,
8feaf0c0 428 const struct tcphdr *th);
1da177e4
LT		 429
430extern struct sock * tcp_check_req(struct sock *sk,struct sk_buff *skb,
60236fdd
ACM		 431 struct request_sock *req,
432 struct request_sock **prev);
1da177e4
LT		 433extern int tcp_child_process(struct sock *parent,
434 struct sock *child,
435 struct sk_buff *skb);
436extern void tcp_enter_frto(struct sock *sk);
437extern void tcp_enter_loss(struct sock *sk, int how);
438extern void tcp_clear_retrans(struct tcp_sock *tp);
439extern void tcp_update_metrics(struct sock *sk);
440
441extern void tcp_close(struct sock *sk,
442 long timeout);
443extern struct sock * tcp_accept(struct sock *sk, int flags, int *err);
444extern unsigned int tcp_poll(struct file * file, struct socket *sock, struct poll_table_struct *wait);
445
446extern int tcp_getsockopt(struct sock *sk, int level,
447 int optname,
448 char __user *optval,
449 int __user *optlen);
450extern int tcp_setsockopt(struct sock *sk, int level,
451 int optname, char __user *optval,
452 int optlen);
453extern void tcp_set_keepalive(struct sock *sk, int val);
454extern int tcp_recvmsg(struct kiocb *iocb, struct sock *sk,
455 struct msghdr *msg,
456 size_t len, int nonblock,
457 int flags, int *addr_len);
458
459extern int tcp_listen_start(struct sock *sk);
460
461extern void tcp_parse_options(struct sk_buff *skb,
462 struct tcp_options_received *opt_rx,
463 int estab);
464
465/*
466 * TCP v4 functions exported for the inet6 API
467 */
468
1da177e4
LT		 469extern void tcp_v4_send_check(struct sock *sk,
470 struct tcphdr *th, int len,
471 struct sk_buff *skb);
472
473extern int tcp_v4_conn_request(struct sock *sk,
474 struct sk_buff *skb);
475
476extern struct sock * tcp_create_openreq_child(struct sock *sk,
60236fdd 477 struct request_sock *req,
1da177e4
LT		 478 struct sk_buff *skb);
479
480extern struct sock * tcp_v4_syn_recv_sock(struct sock *sk,
481 struct sk_buff *skb,
60236fdd 482 struct request_sock *req,
1da177e4
LT		 483 struct dst_entry *dst);
484
485extern int tcp_v4_do_rcv(struct sock *sk,
486 struct sk_buff *skb);
487
488extern int tcp_v4_connect(struct sock *sk,
489 struct sockaddr *uaddr,
490 int addr_len);
491
492extern int tcp_connect(struct sock *sk);
493
494extern struct sk_buff * tcp_make_synack(struct sock *sk,
495 struct dst_entry *dst,
60236fdd 496 struct request_sock *req);
1da177e4
LT		 497
498extern int tcp_disconnect(struct sock *sk, int flags);
499
500extern void tcp_unhash(struct sock *sk);
501
502extern int tcp_v4_hash_connecting(struct sock *sk);
503
504
505/* From syncookies.c */
506extern struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb,
507 struct ip_options *opt);
508extern __u32 cookie_v4_init_sequence(struct sock *sk, struct sk_buff *skb,
509 __u16 *mss);
510
511/* tcp_output.c */
512
f6302d1d 513extern void __tcp_push_pending_frames(struct sock *sk, struct tcp_sock *tp,
a2e2a59c 514 unsigned int cur_mss, int nonagle);
f6302d1d 515extern int tcp_may_send_now(struct sock *sk, struct tcp_sock *tp);
1da177e4
LT		 516extern int tcp_retransmit_skb(struct sock *, struct sk_buff *);
517extern void tcp_xmit_retransmit_queue(struct sock *);
518extern void tcp_simple_retransmit(struct sock *);
519extern int tcp_trim_head(struct sock *, struct sk_buff *, u32);
520
521extern void tcp_send_probe0(struct sock *);
522extern void tcp_send_partial(struct sock *);
523extern int tcp_write_wakeup(struct sock *);
524extern void tcp_send_fin(struct sock *sk);
86a76caf
VF		 525extern void tcp_send_active_reset(struct sock *sk,
526 unsigned int __nocast priority);
1da177e4 527extern int tcp_send_synack(struct sock *);
c1b4a7e6 528extern void tcp_push_one(struct sock *, unsigned int mss_now);
1da177e4
LT		 529extern void tcp_send_ack(struct sock *sk);
530extern void tcp_send_delayed_ack(struct sock *sk);
531
a762a980
DM		 532/* tcp_input.c */
533extern void tcp_cwnd_application_limited(struct sock *sk);
534
1da177e4
LT		 535/* tcp_timer.c */
536extern void tcp_init_xmit_timers(struct sock *);
537extern void tcp_clear_xmit_timers(struct sock *);
538
539extern void tcp_delete_keepalive_timer(struct sock *);
540extern void tcp_reset_keepalive_timer(struct sock *, unsigned long);
541extern unsigned int tcp_sync_mss(struct sock *sk, u32 pmtu);
542extern unsigned int tcp_current_mss(struct sock *sk, int large);
543
544#ifdef TCP_DEBUG
545extern const char tcp_timer_bug_msg[];
546#endif
547
548/* tcp_diag.c */
549extern void tcp_get_info(struct sock *, struct tcp_info *);
550
551/* Read 'sendfile()'-style from a TCP socket */
552typedef int (*sk_read_actor_t)(read_descriptor_t *, struct sk_buff *,
553 unsigned int, size_t);
554extern int tcp_read_sock(struct sock *sk, read_descriptor_t *desc,
555 sk_read_actor_t recv_actor);
556
557static inline void tcp_clear_xmit_timer(struct sock *sk, int what)
558{
559 struct tcp_sock *tp = tcp_sk(sk);
560
561 switch (what) {
562 case TCP_TIME_RETRANS:
563 case TCP_TIME_PROBE0:
564 tp->pending = 0;
565
566#ifdef TCP_CLEAR_TIMERS
567 sk_stop_timer(sk, &tp->retransmit_timer);
568#endif
569 break;
570 case TCP_TIME_DACK:
571 tp->ack.blocked = 0;
572 tp->ack.pending = 0;
573
574#ifdef TCP_CLEAR_TIMERS
575 sk_stop_timer(sk, &tp->delack_timer);
576#endif
577 break;
578 default:
579#ifdef TCP_DEBUG
580 printk(tcp_timer_bug_msg);
581#endif
582 return;
583 };
584
585}
586
587/*
588 * Reset the retransmission timer
589 */
590static inline void tcp_reset_xmit_timer(struct sock *sk, int what, unsigned long when)
591{
592 struct tcp_sock *tp = tcp_sk(sk);
593
594 if (when > TCP_RTO_MAX) {
595#ifdef TCP_DEBUG
596 printk(KERN_DEBUG "reset_xmit_timer sk=%p %d when=0x%lx, caller=%p\n", sk, what, when, current_text_addr());
597#endif
598 when = TCP_RTO_MAX;
599 }
600
601 switch (what) {
602 case TCP_TIME_RETRANS:
603 case TCP_TIME_PROBE0:
604 tp->pending = what;
605 tp->timeout = jiffies+when;
606 sk_reset_timer(sk, &tp->retransmit_timer, tp->timeout);
607 break;
608
609 case TCP_TIME_DACK:
610 tp->ack.pending |= TCP_ACK_TIMER;
611 tp->ack.timeout = jiffies+when;
612 sk_reset_timer(sk, &tp->delack_timer, tp->ack.timeout);
613 break;
614
615 default:
616#ifdef TCP_DEBUG
617 printk(tcp_timer_bug_msg);
618#endif
619 return;
620 };
621}
622
623/* Initialize RCV_MSS value.
624 * RCV_MSS is an our guess about MSS used by the peer.
625 * We haven't any direct information about the MSS.
626 * It's better to underestimate the RCV_MSS rather than overestimate.
627 * Overestimations make us ACKing less frequently than needed.
628 * Underestimations are more easy to detect and fix by tcp_measure_rcv_mss().
629 */
630
631static inline void tcp_initialize_rcv_mss(struct sock *sk)
632{
633 struct tcp_sock *tp = tcp_sk(sk);
c1b4a7e6 634 unsigned int hint = min_t(unsigned int, tp->advmss, tp->mss_cache);
1da177e4
LT		 635
636 hint = min(hint, tp->rcv_wnd/2);
637 hint = min(hint, TCP_MIN_RCVMSS);
638 hint = max(hint, TCP_MIN_MSS);
639
640 tp->ack.rcv_mss = hint;
641}
642
643static __inline__ void __tcp_fast_path_on(struct tcp_sock *tp, u32 snd_wnd)
644{
645 tp->pred_flags = htonl((tp->tcp_header_len << 26) |
646 ntohl(TCP_FLAG_ACK) |
647 snd_wnd);
648}
649
650static __inline__ void tcp_fast_path_on(struct tcp_sock *tp)
651{
652 __tcp_fast_path_on(tp, tp->snd_wnd >> tp->rx_opt.snd_wscale);
653}
654
655static inline void tcp_fast_path_check(struct sock *sk, struct tcp_sock *tp)
656{
b03efcfb 657 if (skb_queue_empty(&tp->out_of_order_queue) &&
1da177e4
LT		 658 tp->rcv_wnd &&
659 atomic_read(&sk->sk_rmem_alloc) < sk->sk_rcvbuf &&
660 !tp->urg_data)
661 tcp_fast_path_on(tp);
662}
663
664/* Compute the actual receive window we are currently advertising.
665 * Rcv_nxt can be after the window if our peer push more data
666 * than the offered window.
667 */
668static __inline__ u32 tcp_receive_window(const struct tcp_sock *tp)
669{
670 s32 win = tp->rcv_wup + tp->rcv_wnd - tp->rcv_nxt;
671
672 if (win < 0)
673 win = 0;
674 return (u32) win;
675}
676
677/* Choose a new window, without checks for shrinking, and without
678 * scaling applied to the result. The caller does these things
679 * if necessary. This is a "raw" window selection.
680 */
681extern u32 __tcp_select_window(struct sock *sk);
682
683/* TCP timestamps are only 32-bits, this causes a slight
684 * complication on 64-bit systems since we store a snapshot
685 * of jiffies in the buffer control blocks below. We decidely
686 * only use of the low 32-bits of jiffies and hide the ugly
687 * casts with the following macro.
688 */
689#define tcp_time_stamp ((__u32)(jiffies))
690
691/* This is what the send packet queueing engine uses to pass
692 * TCP per-packet control information to the transmission
693 * code. We also store the host-order sequence numbers in
694 * here too. This is 36 bytes on 32-bit architectures,
695 * 40 bytes on 64-bit machines, if this grows please adjust
696 * skbuff.h:skbuff->cb[xxx] size appropriately.
697 */
698struct tcp_skb_cb {
699 union {
700 struct inet_skb_parm h4;
701#if defined(CONFIG_IPV6) || defined (CONFIG_IPV6_MODULE)
702 struct inet6_skb_parm h6;
703#endif
704 } header; /* For incoming frames */
705 __u32 seq; /* Starting sequence number */
706 __u32 end_seq; /* SEQ + FIN + SYN + datalen */
707 __u32 when; /* used to compute rtt's */
708 __u8 flags; /* TCP header flags. */
709
710 /* NOTE: These must match up to the flags byte in a
711 * real TCP header.
712 */
713#define TCPCB_FLAG_FIN 0x01
714#define TCPCB_FLAG_SYN 0x02
715#define TCPCB_FLAG_RST 0x04
716#define TCPCB_FLAG_PSH 0x08
717#define TCPCB_FLAG_ACK 0x10
718#define TCPCB_FLAG_URG 0x20
719#define TCPCB_FLAG_ECE 0x40
720#define TCPCB_FLAG_CWR 0x80
721
722 __u8 sacked; /* State flags for SACK/FACK. */
723#define TCPCB_SACKED_ACKED 0x01 /* SKB ACK'd by a SACK block */
724#define TCPCB_SACKED_RETRANS 0x02 /* SKB retransmitted */
725#define TCPCB_LOST 0x04 /* SKB is lost */
726#define TCPCB_TAGBITS 0x07 /* All tag bits */
727
728#define TCPCB_EVER_RETRANS 0x80 /* Ever retransmitted frame */
729#define TCPCB_RETRANS (TCPCB_SACKED_RETRANS|TCPCB_EVER_RETRANS)
730
731#define TCPCB_URG 0x20 /* Urgent pointer advenced here */
732
733#define TCPCB_AT_TAIL (TCPCB_URG)
734
735 __u16 urg_ptr; /* Valid w/URG flags is set. */
736 __u32 ack_seq; /* Sequence number ACK'd */
737};
738
739#define TCP_SKB_CB(__skb) ((struct tcp_skb_cb *)&((__skb)->cb[0]))
740
741#include <net/tcp_ecn.h>
742
743/* Due to TSO, an SKB can be composed of multiple actual
744 * packets. To keep these tracked properly, we use this.
745 */
746static inline int tcp_skb_pcount(const struct sk_buff *skb)
747{
748 return skb_shinfo(skb)->tso_segs;
749}
750
751/* This is valid iff tcp_skb_pcount() > 1. */
752static inline int tcp_skb_mss(const struct sk_buff *skb)
753{
754 return skb_shinfo(skb)->tso_size;
755}
756
757static inline void tcp_dec_pcount_approx(__u32 *count,
758 const struct sk_buff *skb)
759{
760 if (*count) {
761 *count -= tcp_skb_pcount(skb);
762 if ((int)*count < 0)
763 *count = 0;
764 }
765}
766
767static inline void tcp_packets_out_inc(struct sock *sk,
768 struct tcp_sock *tp,
769 const struct sk_buff *skb)
770{
771 int orig = tp->packets_out;
772
773 tp->packets_out += tcp_skb_pcount(skb);
774 if (!orig)
775 tcp_reset_xmit_timer(sk, TCP_TIME_RETRANS, tp->rto);
776}
777
778static inline void tcp_packets_out_dec(struct tcp_sock *tp,
779 const struct sk_buff *skb)
780{
781 tp->packets_out -= tcp_skb_pcount(skb);
782}
783
317a76f9
SH		 784/* Events passed to congestion control interface */
785enum tcp_ca_event {
786 CA_EVENT_TX_START, /* first transmit when no packets in flight */
787 CA_EVENT_CWND_RESTART, /* congestion window restart */
788 CA_EVENT_COMPLETE_CWR, /* end of congestion recovery */
789 CA_EVENT_FRTO, /* fast recovery timeout */
790 CA_EVENT_LOSS, /* loss timeout */
791 CA_EVENT_FAST_ACK, /* in sequence ack */
792 CA_EVENT_SLOW_ACK, /* other ack */
793};
794
795/*
796 * Interface for adding new TCP congestion control handlers
797 */
798#define TCP_CA_NAME_MAX 16
799struct tcp_congestion_ops {
800 struct list_head list;
801
802 /* initialize private data (optional) */
803 void (*init)(struct tcp_sock *tp);
804 /* cleanup private data (optional) */
805 void (*release)(struct tcp_sock *tp);
806
807 /* return slow start threshold (required) */
808 u32 (*ssthresh)(struct tcp_sock *tp);
809 /* lower bound for congestion window (optional) */
810 u32 (*min_cwnd)(struct tcp_sock *tp);
811 /* do new cwnd calculation (required) */
812 void (*cong_avoid)(struct tcp_sock *tp, u32 ack,
813 u32 rtt, u32 in_flight, int good_ack);
814 /* round trip time sample per acked packet (optional) */
815 void (*rtt_sample)(struct tcp_sock *tp, u32 usrtt);
816 /* call before changing ca_state (optional) */
817 void (*set_state)(struct tcp_sock *tp, u8 new_state);
818 /* call when cwnd event occurs (optional) */
819 void (*cwnd_event)(struct tcp_sock *tp, enum tcp_ca_event ev);
820 /* new value of cwnd after loss (optional) */
821 u32 (*undo_cwnd)(struct tcp_sock *tp);
822 /* hook for packet ack accounting (optional) */
823 void (*pkts_acked)(struct tcp_sock *tp, u32 num_acked);
824 /* get info for tcp_diag (optional) */
825 void (*get_info)(struct tcp_sock *tp, u32 ext, struct sk_buff *skb);
826
827 char name[TCP_CA_NAME_MAX];
828 struct module *owner;
829};
830
831extern int tcp_register_congestion_control(struct tcp_congestion_ops *type);
832extern void tcp_unregister_congestion_control(struct tcp_congestion_ops *type);
833
834extern void tcp_init_congestion_control(struct tcp_sock *tp);
835extern void tcp_cleanup_congestion_control(struct tcp_sock *tp);
836extern int tcp_set_default_congestion_control(const char *name);
837extern void tcp_get_default_congestion_control(char *name);
5f8ef48d 838extern int tcp_set_congestion_control(struct tcp_sock *tp, const char *name);
317a76f9 839
5f8ef48d 840extern struct tcp_congestion_ops tcp_init_congestion_ops;
317a76f9
SH		 841extern u32 tcp_reno_ssthresh(struct tcp_sock *tp);
842extern void tcp_reno_cong_avoid(struct tcp_sock *tp, u32 ack,
843 u32 rtt, u32 in_flight, int flag);
844extern u32 tcp_reno_min_cwnd(struct tcp_sock *tp);
a8acfbac 845extern struct tcp_congestion_ops tcp_reno;
317a76f9
SH		 846
847static inline void tcp_set_ca_state(struct tcp_sock *tp, u8 ca_state)
848{
849 if (tp->ca_ops->set_state)
850 tp->ca_ops->set_state(tp, ca_state);
851 tp->ca_state = ca_state;
852}
853
854static inline void tcp_ca_event(struct tcp_sock *tp, enum tcp_ca_event event)
855{
856 if (tp->ca_ops->cwnd_event)
857 tp->ca_ops->cwnd_event(tp, event);
858}
859
1da177e4
LT		 860/* This determines how many packets are "in the network" to the best
861 * of our knowledge. In many cases it is conservative, but where
862 * detailed information is available from the receiver (via SACK
863 * blocks etc.) we can make more aggressive calculations.
864 *
865 * Use this for decisions involving congestion control, use just
866 * tp->packets_out to determine if the send queue is empty or not.
867 *
868 * Read this equation as:
869 *
870 * "Packets sent once on transmission queue" MINUS
871 * "Packets left network, but not honestly ACKed yet" PLUS
872 * "Packets fast retransmitted"
873 */
874static __inline__ unsigned int tcp_packets_in_flight(const struct tcp_sock *tp)
875{
876 return (tp->packets_out - tp->left_out + tp->retrans_out);
877}
878
1da177e4
LT		 879/* If cwnd > ssthresh, we may raise ssthresh to be half-way to cwnd.
880 * The exception is rate halving phase, when cwnd is decreasing towards
881 * ssthresh.
882 */
883static inline __u32 tcp_current_ssthresh(struct tcp_sock *tp)
884{
885 if ((1<<tp->ca_state)&(TCPF_CA_CWR|TCPF_CA_Recovery))
886 return tp->snd_ssthresh;
887 else
888 return max(tp->snd_ssthresh,
889 ((tp->snd_cwnd >> 1) +
890 (tp->snd_cwnd >> 2)));
891}
892
893static inline void tcp_sync_left_out(struct tcp_sock *tp)
894{
895 if (tp->rx_opt.sack_ok &&
896 (tp->sacked_out >= tp->packets_out - tp->lost_out))
897 tp->sacked_out = tp->packets_out - tp->lost_out;
898 tp->left_out = tp->sacked_out + tp->lost_out;
899}
900
d1b04c08 901/* Set slow start threshold and cwnd not falling to slow start */
1da177e4
LT		 902static inline void __tcp_enter_cwr(struct tcp_sock *tp)
903{
904 tp->undo_marker = 0;
317a76f9 905 tp->snd_ssthresh = tp->ca_ops->ssthresh(tp);
1da177e4
LT		 906 tp->snd_cwnd = min(tp->snd_cwnd,
907 tcp_packets_in_flight(tp) + 1U);
908 tp->snd_cwnd_cnt = 0;
909 tp->high_seq = tp->snd_nxt;
910 tp->snd_cwnd_stamp = tcp_time_stamp;
911 TCP_ECN_queue_cwr(tp);
912}
913
914static inline void tcp_enter_cwr(struct tcp_sock *tp)
915{
916 tp->prior_ssthresh = 0;
917 if (tp->ca_state < TCP_CA_CWR) {
918 __tcp_enter_cwr(tp);
919 tcp_set_ca_state(tp, TCP_CA_CWR);
920 }
921}
922
923extern __u32 tcp_init_cwnd(struct tcp_sock *tp, struct dst_entry *dst);
924
925/* Slow start with delack produces 3 packets of burst, so that
926 * it is safe "de facto".
927 */
928static __inline__ __u32 tcp_max_burst(const struct tcp_sock *tp)
929{
930 return 3;
931}
932
1da177e4
LT		 933static __inline__ void tcp_minshall_update(struct tcp_sock *tp, int mss,
934 const struct sk_buff *skb)
935{
936 if (skb->len < mss)
937 tp->snd_sml = TCP_SKB_CB(skb)->end_seq;
938}
939
1da177e4
LT		 940static __inline__ void tcp_check_probe_timer(struct sock *sk, struct tcp_sock *tp)
941{
942 if (!tp->packets_out && !tp->pending)
943 tcp_reset_xmit_timer(sk, TCP_TIME_PROBE0, tp->rto);
944}
945
1da177e4
LT		 946static __inline__ void tcp_push_pending_frames(struct sock *sk,
947 struct tcp_sock *tp)
948{
949 __tcp_push_pending_frames(sk, tp, tcp_current_mss(sk, 1), tp->nonagle);
950}
951
1da177e4
LT		 952static __inline__ void tcp_init_wl(struct tcp_sock *tp, u32 ack, u32 seq)
953{
954 tp->snd_wl1 = seq;
955}
956
957static __inline__ void tcp_update_wl(struct tcp_sock *tp, u32 ack, u32 seq)
958{
959 tp->snd_wl1 = seq;
960}
961
962extern void tcp_destroy_sock(struct sock *sk);
963
964
965/*
966 * Calculate(/check) TCP checksum
967 */
968static __inline__ u16 tcp_v4_check(struct tcphdr *th, int len,
969 unsigned long saddr, unsigned long daddr,
970 unsigned long base)
971{
972 return csum_tcpudp_magic(saddr,daddr,len,IPPROTO_TCP,base);
973}
974
975static __inline__ int __tcp_checksum_complete(struct sk_buff *skb)
976{
977 return (unsigned short)csum_fold(skb_checksum(skb, 0, skb->len, skb->csum));
978}
979
980static __inline__ int tcp_checksum_complete(struct sk_buff *skb)
981{
982 return skb->ip_summed != CHECKSUM_UNNECESSARY &&
983 __tcp_checksum_complete(skb);
984}
985
986/* Prequeue for VJ style copy to user, combined with checksumming. */
987
988static __inline__ void tcp_prequeue_init(struct tcp_sock *tp)
989{
990 tp->ucopy.task = NULL;
991 tp->ucopy.len = 0;
992 tp->ucopy.memory = 0;
993 skb_queue_head_init(&tp->ucopy.prequeue);
994}
995
996/* Packet is added to VJ-style prequeue for processing in process
997 * context, if a reader task is waiting. Apparently, this exciting
998 * idea (VJ's mail "Re: query about TCP header on tcp-ip" of 07 Sep 93)
999 * failed somewhere. Latency? Burstiness? Well, at least now we will
1000 * see, why it failed. 8)8) --ANK
1001 *
1002 * NOTE: is this not too big to inline?
1003 */
1004static __inline__ int tcp_prequeue(struct sock *sk, struct sk_buff *skb)
1005{
1006 struct tcp_sock *tp = tcp_sk(sk);
1007
1008 if (!sysctl_tcp_low_latency && tp->ucopy.task) {
1009 __skb_queue_tail(&tp->ucopy.prequeue, skb);
1010 tp->ucopy.memory += skb->truesize;
1011 if (tp->ucopy.memory > sk->sk_rcvbuf) {
1012 struct sk_buff *skb1;
1013
1014 BUG_ON(sock_owned_by_user(sk));
1015
1016 while ((skb1 = __skb_dequeue(&tp->ucopy.prequeue)) != NULL) {
1017 sk->sk_backlog_rcv(sk, skb1);
1018 NET_INC_STATS_BH(LINUX_MIB_TCPPREQUEUEDROPPED);
1019 }
1020
1021 tp->ucopy.memory = 0;
1022 } else if (skb_queue_len(&tp->ucopy.prequeue) == 1) {
1023 wake_up_interruptible(sk->sk_sleep);
1024 if (!tcp_ack_scheduled(tp))
1025 tcp_reset_xmit_timer(sk, TCP_TIME_DACK, (3*TCP_RTO_MIN)/4);
1026 }
1027 return 1;
1028 }
1029 return 0;
1030}
1031
1032
1033#undef STATE_TRACE
1034
1035#ifdef STATE_TRACE
1036static const char *statename[]={
1037 "Unused","Established","Syn Sent","Syn Recv",
1038 "Fin Wait 1","Fin Wait 2","Time Wait", "Close",
1039 "Close Wait","Last ACK","Listen","Closing"
1040};
1041#endif
1042
1043static __inline__ void tcp_set_state(struct sock *sk, int state)
1044{
1045 int oldstate = sk->sk_state;
1046
1047 switch (state) {
1048 case TCP_ESTABLISHED:
1049 if (oldstate != TCP_ESTABLISHED)
1050 TCP_INC_STATS(TCP_MIB_CURRESTAB);
1051 break;
1052
1053 case TCP_CLOSE:
1054 if (oldstate == TCP_CLOSE_WAIT || oldstate == TCP_ESTABLISHED)
1055 TCP_INC_STATS(TCP_MIB_ESTABRESETS);
1056
1057 sk->sk_prot->unhash(sk);
a55ebcc4 1058 if (inet_sk(sk)->bind_hash &&
1da177e4 1059 !(sk->sk_userlocks & SOCK_BINDPORT_LOCK))
2d8c4ce5 1060 inet_put_port(&tcp_hashinfo, sk);
1da177e4
LT		 1061 /* fall through */
1062 default:
1063 if (oldstate==TCP_ESTABLISHED)
1064 TCP_DEC_STATS(TCP_MIB_CURRESTAB);
1065 }
1066
1067 /* Change state AFTER socket is unhashed to avoid closed
1068 * socket sitting in hash tables.
1069 */
1070 sk->sk_state = state;
1071
1072#ifdef STATE_TRACE
1073 SOCK_DEBUG(sk, "TCP sk=%p, State %s -> %s\n",sk, statename[oldstate],statename[state]);
1074#endif
1075}
1076
1077static __inline__ void tcp_done(struct sock *sk)
1078{
1079 tcp_set_state(sk, TCP_CLOSE);
1080 tcp_clear_xmit_timers(sk);
1081
1082 sk->sk_shutdown = SHUTDOWN_MASK;
1083
1084 if (!sock_flag(sk, SOCK_DEAD))
1085 sk->sk_state_change(sk);
1086 else
1087 tcp_destroy_sock(sk);
1088}
1089
1090static __inline__ void tcp_sack_reset(struct tcp_options_received *rx_opt)
1091{
1092 rx_opt->dsack = 0;
1093 rx_opt->eff_sacks = 0;
1094 rx_opt->num_sacks = 0;
1095}
1096
1097static __inline__ void tcp_build_and_update_options(__u32 *ptr, struct tcp_sock *tp, __u32 tstamp)
1098{
1099 if (tp->rx_opt.tstamp_ok) {
1100 *ptr++ = __constant_htonl((TCPOPT_NOP << 24) |
1101 (TCPOPT_NOP << 16) |
1102 (TCPOPT_TIMESTAMP << 8) |
1103 TCPOLEN_TIMESTAMP);
1104 *ptr++ = htonl(tstamp);
1105 *ptr++ = htonl(tp->rx_opt.ts_recent);
1106 }
1107 if (tp->rx_opt.eff_sacks) {
1108 struct tcp_sack_block *sp = tp->rx_opt.dsack ? tp->duplicate_sack : tp->selective_acks;
1109 int this_sack;
1110
1111 *ptr++ = __constant_htonl((TCPOPT_NOP << 24) |
1112 (TCPOPT_NOP << 16) |
1113 (TCPOPT_SACK << 8) |
1114 (TCPOLEN_SACK_BASE +
1115 (tp->rx_opt.eff_sacks * TCPOLEN_SACK_PERBLOCK)));
1116 for(this_sack = 0; this_sack < tp->rx_opt.eff_sacks; this_sack++) {
1117 *ptr++ = htonl(sp[this_sack].start_seq);
1118 *ptr++ = htonl(sp[this_sack].end_seq);
1119 }
1120 if (tp->rx_opt.dsack) {
1121 tp->rx_opt.dsack = 0;
1122 tp->rx_opt.eff_sacks--;
1123 }
1124 }
1125}
1126
1127/* Construct a tcp options header for a SYN or SYN_ACK packet.
1128 * If this is every changed make sure to change the definition of
1129 * MAX_SYN_SIZE to match the new maximum number of options that you
1130 * can generate.
1131 */
1132static inline void tcp_syn_build_options(__u32 *ptr, int mss, int ts, int sack,
1133 int offer_wscale, int wscale, __u32 tstamp, __u32 ts_recent)
1134{
1135 /* We always get an MSS option.
1136 * The option bytes which will be seen in normal data
1137 * packets should timestamps be used, must be in the MSS
1138 * advertised. But we subtract them from tp->mss_cache so
1139 * that calculations in tcp_sendmsg are simpler etc.
1140 * So account for this fact here if necessary. If we
1141 * don't do this correctly, as a receiver we won't
1142 * recognize data packets as being full sized when we
1143 * should, and thus we won't abide by the delayed ACK
1144 * rules correctly.
1145 * SACKs don't matter, we never delay an ACK when we
1146 * have any of those going out.
1147 */
1148 *ptr++ = htonl((TCPOPT_MSS << 24) | (TCPOLEN_MSS << 16) | mss);
1149 if (ts) {
1150 if(sack)
1151 *ptr++ = __constant_htonl((TCPOPT_SACK_PERM << 24) | (TCPOLEN_SACK_PERM << 16) |
1152 (TCPOPT_TIMESTAMP << 8) | TCPOLEN_TIMESTAMP);
1153 else
1154 *ptr++ = __constant_htonl((TCPOPT_NOP << 24) | (TCPOPT_NOP << 16) |
1155 (TCPOPT_TIMESTAMP << 8) | TCPOLEN_TIMESTAMP);
1156 *ptr++ = htonl(tstamp); /* TSVAL */
1157 *ptr++ = htonl(ts_recent); /* TSECR */
1158 } else if(sack)
1159 *ptr++ = __constant_htonl((TCPOPT_NOP << 24) | (TCPOPT_NOP << 16) |
1160 (TCPOPT_SACK_PERM << 8) | TCPOLEN_SACK_PERM);
1161 if (offer_wscale)
1162 *ptr++ = htonl((TCPOPT_NOP << 24) | (TCPOPT_WINDOW << 16) | (TCPOLEN_WINDOW << 8) | (wscale));
1163}
1164
1165/* Determine a window scaling and initial window to offer. */
1166extern void tcp_select_initial_window(int __space, __u32 mss,
1167 __u32 *rcv_wnd, __u32 *window_clamp,
1168 int wscale_ok, __u8 *rcv_wscale);
1169
1170static inline int tcp_win_from_space(int space)
1171{
1172 return sysctl_tcp_adv_win_scale<=0 ?
1173 (space>>(-sysctl_tcp_adv_win_scale)) :
1174 space - (space>>sysctl_tcp_adv_win_scale);
1175}
1176
1177/* Note: caller must be prepared to deal with negative returns */
1178static inline int tcp_space(const struct sock *sk)
1179{
1180 return tcp_win_from_space(sk->sk_rcvbuf -
1181 atomic_read(&sk->sk_rmem_alloc));
1182}
1183
1184static inline int tcp_full_space(const struct sock *sk)
1185{
1186 return tcp_win_from_space(sk->sk_rcvbuf);
1187}
1188
60236fdd 1189static inline void tcp_acceptq_queue(struct sock *sk, struct request_sock *req,
1da177e4
LT		 1190 struct sock *child)
1191{
0e87506f 1192 reqsk_queue_add(&tcp_sk(sk)->accept_queue, req, sk, child);
1da177e4
LT		 1193}
1194
1da177e4 1195static inline void
60236fdd 1196tcp_synq_removed(struct sock *sk, struct request_sock *req)
1da177e4 1197{
0e87506f 1198 if (reqsk_queue_removed(&tcp_sk(sk)->accept_queue, req) == 0)
1da177e4 1199 tcp_delete_keepalive_timer(sk);
1da177e4
LT		 1200}
1201
1202static inline void tcp_synq_added(struct sock *sk)
1203{
0e87506f 1204 if (reqsk_queue_added(&tcp_sk(sk)->accept_queue) == 0)
1da177e4 1205 tcp_reset_keepalive_timer(sk, TCP_TIMEOUT_INIT);
1da177e4
LT		 1206}
1207
1208static inline int tcp_synq_len(struct sock *sk)
1209{
0e87506f 1210 return reqsk_queue_len(&tcp_sk(sk)->accept_queue);
1da177e4
LT		 1211}
1212
1213static inline int tcp_synq_young(struct sock *sk)
1214{
0e87506f 1215 return reqsk_queue_len_young(&tcp_sk(sk)->accept_queue);
1da177e4
LT		 1216}
1217
1218static inline int tcp_synq_is_full(struct sock *sk)
1219{
0e87506f 1220 return reqsk_queue_is_full(&tcp_sk(sk)->accept_queue);
1da177e4
LT		 1221}
1222
60236fdd 1223static inline void tcp_synq_unlink(struct tcp_sock *tp, struct request_sock *req,
0e87506f 1224 struct request_sock **prev)
1da177e4 1225{
0e87506f 1226 reqsk_queue_unlink(&tp->accept_queue, req, prev);
1da177e4
LT		 1227}
1228
60236fdd
ACM		 1229static inline void tcp_synq_drop(struct sock *sk, struct request_sock *req,
1230 struct request_sock **prev)
1da177e4
LT		 1231{
1232 tcp_synq_unlink(tcp_sk(sk), req, prev);
1233 tcp_synq_removed(sk, req);
60236fdd 1234 reqsk_free(req);
1da177e4
LT		 1235}
1236
60236fdd 1237static __inline__ void tcp_openreq_init(struct request_sock *req,
1da177e4
LT		 1238 struct tcp_options_received *rx_opt,
1239 struct sk_buff *skb)
1240{
2e6599cb
ACM		 1241 struct inet_request_sock *ireq = inet_rsk(req);
1242
1da177e4 1243 req->rcv_wnd = 0; /* So that tcp_send_synack() knows! */
2e6599cb 1244 tcp_rsk(req)->rcv_isn = TCP_SKB_CB(skb)->seq;
1da177e4
LT		 1245 req->mss = rx_opt->mss_clamp;
1246 req->ts_recent = rx_opt->saw_tstamp ? rx_opt->rcv_tsval : 0;
2e6599cb
ACM		 1247 ireq->tstamp_ok = rx_opt->tstamp_ok;
1248 ireq->sack_ok = rx_opt->sack_ok;
1249 ireq->snd_wscale = rx_opt->snd_wscale;
1250 ireq->wscale_ok = rx_opt->wscale_ok;
1251 ireq->acked = 0;
1252 ireq->ecn_ok = 0;
1253 ireq->rmt_port = skb->h.th->source;
1da177e4
LT		 1254}
1255
1256extern void tcp_enter_memory_pressure(void);
1257
1da177e4
LT		 1258static inline int keepalive_intvl_when(const struct tcp_sock *tp)
1259{
1260 return tp->keepalive_intvl ? : sysctl_tcp_keepalive_intvl;
1261}
1262
1263static inline int keepalive_time_when(const struct tcp_sock *tp)
1264{
1265 return tp->keepalive_time ? : sysctl_tcp_keepalive_time;
1266}
1267
1268static inline int tcp_fin_time(const struct tcp_sock *tp)
1269{
1270 int fin_timeout = tp->linger2 ? : sysctl_tcp_fin_timeout;
1271
1272 if (fin_timeout < (tp->rto<<2) - (tp->rto>>1))
1273 fin_timeout = (tp->rto<<2) - (tp->rto>>1);
1274
1275 return fin_timeout;
1276}
1277
1278static inline int tcp_paws_check(const struct tcp_options_received *rx_opt, int rst)
1279{
1280 if ((s32)(rx_opt->rcv_tsval - rx_opt->ts_recent) >= 0)
1281 return 0;
1282 if (xtime.tv_sec >= rx_opt->ts_recent_stamp + TCP_PAWS_24DAYS)
1283 return 0;
1284
1285 /* RST segments are not recommended to carry timestamp,
1286 and, if they do, it is recommended to ignore PAWS because
1287 "their cleanup function should take precedence over timestamps."
1288 Certainly, it is mistake. It is necessary to understand the reasons
1289 of this constraint to relax it: if peer reboots, clock may go
1290 out-of-sync and half-open connections will not be reset.
1291 Actually, the problem would be not existing if all
1292 the implementations followed draft about maintaining clock
1293 via reboots. Linux-2.2 DOES NOT!
1294
1295 However, we can relax time bounds for RST segments to MSL.
1296 */
1297 if (rst && xtime.tv_sec >= rx_opt->ts_recent_stamp + TCP_PAWS_MSL)
1298 return 0;
1299 return 1;
1300}
1301
1da177e4
LT		 1302#define TCP_CHECK_TIMER(sk) do { } while (0)
1303
1304static inline int tcp_use_frto(const struct sock *sk)
1305{
1306 const struct tcp_sock *tp = tcp_sk(sk);
1307
1308 /* F-RTO must be activated in sysctl and there must be some
1309 * unsent new data, and the advertised window should allow
1310 * sending it.
1311 */
1312 return (sysctl_tcp_frto && sk->sk_send_head &&
1313 !after(TCP_SKB_CB(sk->sk_send_head)->end_seq,
1314 tp->snd_una + tp->snd_wnd));
1315}
1316
1317static inline void tcp_mib_init(void)
1318{
1319 /* See RFC 2012 */
1320 TCP_ADD_STATS_USER(TCP_MIB_RTOALGORITHM, 1);
1321 TCP_ADD_STATS_USER(TCP_MIB_RTOMIN, TCP_RTO_MIN*1000/HZ);
1322 TCP_ADD_STATS_USER(TCP_MIB_RTOMAX, TCP_RTO_MAX*1000/HZ);
1323 TCP_ADD_STATS_USER(TCP_MIB_MAXCONN, -1);
1324}
1325
1326/* /proc */
1327enum tcp_seq_states {
1328 TCP_SEQ_STATE_LISTENING,
1329 TCP_SEQ_STATE_OPENREQ,
1330 TCP_SEQ_STATE_ESTABLISHED,
1331 TCP_SEQ_STATE_TIME_WAIT,
1332};
1333
1334struct tcp_seq_afinfo {
1335 struct module *owner;
1336 char *name;
1337 sa_family_t family;
1338 int (*seq_show) (struct seq_file *m, void *v);
1339 struct file_operations *seq_fops;
1340};
1341
1342struct tcp_iter_state {
1343 sa_family_t family;
1344 enum tcp_seq_states state;
1345 struct sock *syn_wait_sk;
1346 int bucket, sbucket, num, uid;
1347 struct seq_operations seq_ops;
1348};
1349
1350extern int tcp_proc_register(struct tcp_seq_afinfo *afinfo);
1351extern void tcp_proc_unregister(struct tcp_seq_afinfo *afinfo);
1352
1da177e4 1353#endif /* _TCP_H */
Linux 6.x block layer and io_uring tree(s)