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[IEEE80211] ipw2200: Simplify multicast checks.
[GitHub/mt8127/android_kernel_alcatel_ttab.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
1da177e4
LT		 24#include <linux/config.h>
25#include <linux/list.h>
26#include <linux/tcp.h>
27#include <linux/slab.h>
28#include <linux/cache.h>
29#include <linux/percpu.h>
fb286bb2 30#include <linux/skbuff.h>
3f421baa
ACM		 31
32#include <net/inet_connection_sock.h>
295ff7ed 33#include <net/inet_timewait_sock.h>
77d8bf9c 34#include <net/inet_hashtables.h>
1da177e4 35#include <net/checksum.h>
2e6599cb 36#include <net/request_sock.h>
1da177e4
LT		 37#include <net/sock.h>
38#include <net/snmp.h>
39#include <net/ip.h>
c752f073
ACM		 40#include <net/tcp_states.h>
41
1da177e4
LT		 42#include <linux/seq_file.h>
43
6e04e021 44extern struct inet_hashinfo tcp_hashinfo;
1da177e4 45
1da177e4 46extern atomic_t tcp_orphan_count;
1da177e4 47extern void tcp_time_wait(struct sock *sk, int state, int timeo);
1da177e4 48
1da177e4
LT		 49#define MAX_TCP_HEADER (128 + MAX_HEADER)
50
51/*
52 * Never offer a window over 32767 without using window scaling. Some
53 * poor stacks do signed 16bit maths!
54 */
55#define MAX_TCP_WINDOW 32767U
56
57/* Minimal accepted MSS. It is (60+60+8) - (20+20). */
58#define TCP_MIN_MSS 88U
59
60/* Minimal RCV_MSS. */
61#define TCP_MIN_RCVMSS 536U
62
63/* After receiving this amount of duplicate ACKs fast retransmit starts. */
64#define TCP_FASTRETRANS_THRESH 3
65
66/* Maximal reordering. */
67#define TCP_MAX_REORDERING 127
68
69/* Maximal number of ACKs sent quickly to accelerate slow-start. */
70#define TCP_MAX_QUICKACKS 16U
71
72/* urg_data states */
73#define TCP_URG_VALID 0x0100
74#define TCP_URG_NOTYET 0x0200
75#define TCP_URG_READ 0x0400
76
77#define TCP_RETR1 3 /*
78 * This is how many retries it does before it
79 * tries to figure out if the gateway is
80 * down. Minimal RFC value is 3; it corresponds
81 * to ~3sec-8min depending on RTO.
82 */
83
84#define TCP_RETR2 15 /*
85 * This should take at least
86 * 90 minutes to time out.
87 * RFC1122 says that the limit is 100 sec.
88 * 15 is ~13-30min depending on RTO.
89 */
90
91#define TCP_SYN_RETRIES 5 /* number of times to retry active opening a
caa20d9a 92 * connection: ~180sec is RFC minimum */
1da177e4
LT		 93
94#define TCP_SYNACK_RETRIES 5 /* number of times to retry passive opening a
caa20d9a 95 * connection: ~180sec is RFC minimum */
1da177e4
LT		 96
97
98#define TCP_ORPHAN_RETRIES 7 /* number of times to retry on an orphaned
99 * socket. 7 is ~50sec-16min.
100 */
101
102
103#define TCP_TIMEWAIT_LEN (60*HZ) /* how long to wait to destroy TIME-WAIT
104 * state, about 60 seconds */
105#define TCP_FIN_TIMEOUT TCP_TIMEWAIT_LEN
106 /* BSD style FIN_WAIT2 deadlock breaker.
107 * It used to be 3min, new value is 60sec,
108 * to combine FIN-WAIT-2 timeout with
109 * TIME-WAIT timer.
110 */
111
112#define TCP_DELACK_MAX ((unsigned)(HZ/5)) /* maximal time to delay before sending an ACK */
113#if HZ >= 100
114#define TCP_DELACK_MIN ((unsigned)(HZ/25)) /* minimal time to delay before sending an ACK */
115#define TCP_ATO_MIN ((unsigned)(HZ/25))
116#else
117#define TCP_DELACK_MIN 4U
118#define TCP_ATO_MIN 4U
119#endif
120#define TCP_RTO_MAX ((unsigned)(120*HZ))
121#define TCP_RTO_MIN ((unsigned)(HZ/5))
122#define TCP_TIMEOUT_INIT ((unsigned)(3*HZ)) /* RFC 1122 initial RTO value */
123
124#define TCP_RESOURCE_PROBE_INTERVAL ((unsigned)(HZ/2U)) /* Maximal interval between probes
125 * for local resources.
126 */
127
128#define TCP_KEEPALIVE_TIME (120*60*HZ) /* two hours */
129#define TCP_KEEPALIVE_PROBES 9 /* Max of 9 keepalive probes */
130#define TCP_KEEPALIVE_INTVL (75*HZ)
131
132#define MAX_TCP_KEEPIDLE 32767
133#define MAX_TCP_KEEPINTVL 32767
134#define MAX_TCP_KEEPCNT 127
135#define MAX_TCP_SYNCNT 127
136
137#define TCP_SYNQ_INTERVAL (HZ/5) /* Period of SYNACK timer */
138#define TCP_SYNQ_HSIZE 512 /* Size of SYNACK hash table */
139
140#define TCP_PAWS_24DAYS (60 * 60 * 24 * 24)
141#define TCP_PAWS_MSL 60 /* Per-host timestamps are invalidated
142 * after this time. It should be equal
143 * (or greater than) TCP_TIMEWAIT_LEN
144 * to provide reliability equal to one
145 * provided by timewait state.
146 */
147#define TCP_PAWS_WINDOW 1 /* Replay window for per-host
148 * timestamps. It must be less than
149 * minimal timewait lifetime.
150 */
1da177e4
LT		 151/*
152 * TCP option
153 */
154
155#define TCPOPT_NOP 1 /* Padding */
156#define TCPOPT_EOL 0 /* End of options */
157#define TCPOPT_MSS 2 /* Segment size negotiating */
158#define TCPOPT_WINDOW 3 /* Window scaling */
159#define TCPOPT_SACK_PERM 4 /* SACK Permitted */
160#define TCPOPT_SACK 5 /* SACK Block */
161#define TCPOPT_TIMESTAMP 8 /* Better RTT estimations/PAWS */
162
163/*
164 * TCP option lengths
165 */
166
167#define TCPOLEN_MSS 4
168#define TCPOLEN_WINDOW 3
169#define TCPOLEN_SACK_PERM 2
170#define TCPOLEN_TIMESTAMP 10
171
172/* But this is what stacks really send out. */
173#define TCPOLEN_TSTAMP_ALIGNED 12
174#define TCPOLEN_WSCALE_ALIGNED 4
175#define TCPOLEN_SACKPERM_ALIGNED 4
176#define TCPOLEN_SACK_BASE 2
177#define TCPOLEN_SACK_BASE_ALIGNED 4
178#define TCPOLEN_SACK_PERBLOCK 8
179
1da177e4
LT		 180/* Flags in tp->nonagle */
181#define TCP_NAGLE_OFF 1 /* Nagle's algo is disabled */
182#define TCP_NAGLE_CORK 2 /* Socket is corked */
caa20d9a 183#define TCP_NAGLE_PUSH 4 /* Cork is overridden for already queued data */
1da177e4 184
295ff7ed
ACM		 185extern struct inet_timewait_death_row tcp_death_row;
186
1da177e4 187/* sysctl variables for tcp */
1da177e4
LT		 188extern int sysctl_tcp_timestamps;
189extern int sysctl_tcp_window_scaling;
190extern int sysctl_tcp_sack;
191extern int sysctl_tcp_fin_timeout;
1da177e4
LT		 192extern int sysctl_tcp_keepalive_time;
193extern int sysctl_tcp_keepalive_probes;
194extern int sysctl_tcp_keepalive_intvl;
195extern int sysctl_tcp_syn_retries;
196extern int sysctl_tcp_synack_retries;
197extern int sysctl_tcp_retries1;
198extern int sysctl_tcp_retries2;
199extern int sysctl_tcp_orphan_retries;
200extern int sysctl_tcp_syncookies;
201extern int sysctl_tcp_retrans_collapse;
202extern int sysctl_tcp_stdurg;
203extern int sysctl_tcp_rfc1337;
204extern int sysctl_tcp_abort_on_overflow;
205extern int sysctl_tcp_max_orphans;
1da177e4
LT		 206extern int sysctl_tcp_fack;
207extern int sysctl_tcp_reordering;
208extern int sysctl_tcp_ecn;
209extern int sysctl_tcp_dsack;
210extern int sysctl_tcp_mem[3];
211extern int sysctl_tcp_wmem[3];
212extern int sysctl_tcp_rmem[3];
213extern int sysctl_tcp_app_win;
214extern int sysctl_tcp_adv_win_scale;
215extern int sysctl_tcp_tw_reuse;
216extern int sysctl_tcp_frto;
217extern int sysctl_tcp_low_latency;
1da177e4 218extern int sysctl_tcp_nometrics_save;
1da177e4
LT		 219extern int sysctl_tcp_moderate_rcvbuf;
220extern int sysctl_tcp_tso_win_divisor;
9772efb9 221extern int sysctl_tcp_abc;
1da177e4
LT		 222
223extern atomic_t tcp_memory_allocated;
224extern atomic_t tcp_sockets_allocated;
225extern int tcp_memory_pressure;
226
1da177e4
LT		 227/*
228 * The next routines deal with comparing 32 bit unsigned ints
229 * and worry about wraparound (automatic with unsigned arithmetic).
230 */
231
232static inline int before(__u32 seq1, __u32 seq2)
233{
234 return (__s32)(seq1-seq2) < 0;
235}
236
237static inline int after(__u32 seq1, __u32 seq2)
238{
239 return (__s32)(seq2-seq1) < 0;
240}
241
242
243/* is s2<=s1<=s3 ? */
244static inline int between(__u32 seq1, __u32 seq2, __u32 seq3)
245{
246 return seq3 - seq2 >= seq1 - seq2;
247}
248
249
250extern struct proto tcp_prot;
251
252DECLARE_SNMP_STAT(struct tcp_mib, tcp_statistics);
253#define TCP_INC_STATS(field) SNMP_INC_STATS(tcp_statistics, field)
254#define TCP_INC_STATS_BH(field) SNMP_INC_STATS_BH(tcp_statistics, field)
255#define TCP_INC_STATS_USER(field) SNMP_INC_STATS_USER(tcp_statistics, field)
256#define TCP_DEC_STATS(field) SNMP_DEC_STATS(tcp_statistics, field)
257#define TCP_ADD_STATS_BH(field, val) SNMP_ADD_STATS_BH(tcp_statistics, field, val)
258#define TCP_ADD_STATS_USER(field, val) SNMP_ADD_STATS_USER(tcp_statistics, field, val)
259
1da177e4
LT		 260extern void tcp_v4_err(struct sk_buff *skb, u32);
261
262extern void tcp_shutdown (struct sock *sk, int how);
263
264extern int tcp_v4_rcv(struct sk_buff *skb);
265
266extern int tcp_v4_remember_stamp(struct sock *sk);
267
8feaf0c0 268extern int tcp_v4_tw_remember_stamp(struct inet_timewait_sock *tw);
1da177e4
LT		 269
270extern int tcp_sendmsg(struct kiocb *iocb, struct sock *sk,
271 struct msghdr *msg, size_t size);
272extern ssize_t tcp_sendpage(struct socket *sock, struct page *page, int offset, size_t size, int flags);
273
274extern int tcp_ioctl(struct sock *sk,
275 int cmd,
276 unsigned long arg);
277
278extern int tcp_rcv_state_process(struct sock *sk,
279 struct sk_buff *skb,
280 struct tcphdr *th,
281 unsigned len);
282
283extern int tcp_rcv_established(struct sock *sk,
284 struct sk_buff *skb,
285 struct tcphdr *th,
286 unsigned len);
287
288extern void tcp_rcv_space_adjust(struct sock *sk);
289
6d6ee43e
ACM		 290extern int tcp_twsk_unique(struct sock *sk,
291 struct sock *sktw, void *twp);
292
463c84b9
ACM		 293static inline void tcp_dec_quickack_mode(struct sock *sk,
294 const unsigned int pkts)
1da177e4 295{
463c84b9 296 struct inet_connection_sock *icsk = inet_csk(sk);
fc6415bc 297
463c84b9
ACM		 298 if (icsk->icsk_ack.quick) {
299 if (pkts >= icsk->icsk_ack.quick) {
300 icsk->icsk_ack.quick = 0;
fc6415bc 301 /* Leaving quickack mode we deflate ATO. */
463c84b9 302 icsk->icsk_ack.ato = TCP_ATO_MIN;
fc6415bc 303 } else
463c84b9 304 icsk->icsk_ack.quick -= pkts;
1da177e4
LT		 305 }
306}
307
463c84b9 308extern void tcp_enter_quickack_mode(struct sock *sk);
1da177e4 309
1da177e4
LT		 310static inline void tcp_clear_options(struct tcp_options_received *rx_opt)
311{
312 rx_opt->tstamp_ok = rx_opt->sack_ok = rx_opt->wscale_ok = rx_opt->snd_wscale = 0;
313}
314
315enum tcp_tw_status
316{
317 TCP_TW_SUCCESS = 0,
318 TCP_TW_RST = 1,
319 TCP_TW_ACK = 2,
320 TCP_TW_SYN = 3
321};
322
323
8feaf0c0 324extern enum tcp_tw_status tcp_timewait_state_process(struct inet_timewait_sock *tw,
1da177e4 325 struct sk_buff *skb,
8feaf0c0 326 const struct tcphdr *th);
1da177e4
LT		 327
328extern struct sock * tcp_check_req(struct sock *sk,struct sk_buff *skb,
60236fdd
ACM		 329 struct request_sock *req,
330 struct request_sock **prev);
1da177e4
LT		 331extern int tcp_child_process(struct sock *parent,
332 struct sock *child,
333 struct sk_buff *skb);
334extern void tcp_enter_frto(struct sock *sk);
335extern void tcp_enter_loss(struct sock *sk, int how);
336extern void tcp_clear_retrans(struct tcp_sock *tp);
337extern void tcp_update_metrics(struct sock *sk);
338
339extern void tcp_close(struct sock *sk,
340 long timeout);
1da177e4
LT		 341extern unsigned int tcp_poll(struct file * file, struct socket *sock, struct poll_table_struct *wait);
342
343extern int tcp_getsockopt(struct sock *sk, int level,
344 int optname,
345 char __user *optval,
346 int __user *optlen);
347extern int tcp_setsockopt(struct sock *sk, int level,
348 int optname, char __user *optval,
349 int optlen);
350extern void tcp_set_keepalive(struct sock *sk, int val);
351extern int tcp_recvmsg(struct kiocb *iocb, struct sock *sk,
352 struct msghdr *msg,
353 size_t len, int nonblock,
354 int flags, int *addr_len);
355
1da177e4
LT		 356extern void tcp_parse_options(struct sk_buff *skb,
357 struct tcp_options_received *opt_rx,
358 int estab);
359
360/*
361 * TCP v4 functions exported for the inet6 API
362 */
363
8292a17a 364extern void tcp_v4_send_check(struct sock *sk, int len,
1da177e4
LT		 365 struct sk_buff *skb);
366
367extern int tcp_v4_conn_request(struct sock *sk,
368 struct sk_buff *skb);
369
370extern struct sock * tcp_create_openreq_child(struct sock *sk,
60236fdd 371 struct request_sock *req,
1da177e4
LT		 372 struct sk_buff *skb);
373
374extern struct sock * tcp_v4_syn_recv_sock(struct sock *sk,
375 struct sk_buff *skb,
60236fdd 376 struct request_sock *req,
1da177e4
LT		 377 struct dst_entry *dst);
378
379extern int tcp_v4_do_rcv(struct sock *sk,
380 struct sk_buff *skb);
381
382extern int tcp_v4_connect(struct sock *sk,
383 struct sockaddr *uaddr,
384 int addr_len);
385
386extern int tcp_connect(struct sock *sk);
387
388extern struct sk_buff * tcp_make_synack(struct sock *sk,
389 struct dst_entry *dst,
60236fdd 390 struct request_sock *req);
1da177e4
LT		 391
392extern int tcp_disconnect(struct sock *sk, int flags);
393
394extern void tcp_unhash(struct sock *sk);
395
396extern int tcp_v4_hash_connecting(struct sock *sk);
397
398
399/* From syncookies.c */
400extern struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb,
401 struct ip_options *opt);
402extern __u32 cookie_v4_init_sequence(struct sock *sk, struct sk_buff *skb,
403 __u16 *mss);
404
405/* tcp_output.c */
406
f6302d1d 407extern void __tcp_push_pending_frames(struct sock *sk, struct tcp_sock *tp,
a2e2a59c 408 unsigned int cur_mss, int nonagle);
f6302d1d 409extern int tcp_may_send_now(struct sock *sk, struct tcp_sock *tp);
1da177e4
LT		 410extern int tcp_retransmit_skb(struct sock *, struct sk_buff *);
411extern void tcp_xmit_retransmit_queue(struct sock *);
412extern void tcp_simple_retransmit(struct sock *);
413extern int tcp_trim_head(struct sock *, struct sk_buff *, u32);
6475be16 414extern int tcp_fragment(struct sock *, struct sk_buff *, u32, unsigned int);
1da177e4
LT		 415
416extern void tcp_send_probe0(struct sock *);
417extern void tcp_send_partial(struct sock *);
418extern int tcp_write_wakeup(struct sock *);
419extern void tcp_send_fin(struct sock *sk);
dd0fc66f 420extern void tcp_send_active_reset(struct sock *sk, gfp_t priority);
1da177e4 421extern int tcp_send_synack(struct sock *);
c1b4a7e6 422extern void tcp_push_one(struct sock *, unsigned int mss_now);
1da177e4
LT		 423extern void tcp_send_ack(struct sock *sk);
424extern void tcp_send_delayed_ack(struct sock *sk);
425
a762a980
DM		 426/* tcp_input.c */
427extern void tcp_cwnd_application_limited(struct sock *sk);
428
1da177e4
LT		 429/* tcp_timer.c */
430extern void tcp_init_xmit_timers(struct sock *);
463c84b9
ACM		 431static inline void tcp_clear_xmit_timers(struct sock *sk)
432{
433 inet_csk_clear_xmit_timers(sk);
434}
1da177e4 435
1da177e4
LT		 436extern unsigned int tcp_sync_mss(struct sock *sk, u32 pmtu);
437extern unsigned int tcp_current_mss(struct sock *sk, int large);
438
17b085ea 439/* tcp.c */
1da177e4
LT		 440extern void tcp_get_info(struct sock *, struct tcp_info *);
441
442/* Read 'sendfile()'-style from a TCP socket */
443typedef int (*sk_read_actor_t)(read_descriptor_t *, struct sk_buff *,
444 unsigned int, size_t);
445extern int tcp_read_sock(struct sock *sk, read_descriptor_t *desc,
446 sk_read_actor_t recv_actor);
447
1da177e4
LT		 448/* Initialize RCV_MSS value.
449 * RCV_MSS is an our guess about MSS used by the peer.
450 * We haven't any direct information about the MSS.
451 * It's better to underestimate the RCV_MSS rather than overestimate.
452 * Overestimations make us ACKing less frequently than needed.
453 * Underestimations are more easy to detect and fix by tcp_measure_rcv_mss().
454 */
455
456static inline void tcp_initialize_rcv_mss(struct sock *sk)
457{
458 struct tcp_sock *tp = tcp_sk(sk);
c1b4a7e6 459 unsigned int hint = min_t(unsigned int, tp->advmss, tp->mss_cache);
1da177e4
LT		 460
461 hint = min(hint, tp->rcv_wnd/2);
462 hint = min(hint, TCP_MIN_RCVMSS);
463 hint = max(hint, TCP_MIN_MSS);
464
463c84b9 465 inet_csk(sk)->icsk_ack.rcv_mss = hint;
1da177e4
LT		 466}
467
468static __inline__ void __tcp_fast_path_on(struct tcp_sock *tp, u32 snd_wnd)
469{
470 tp->pred_flags = htonl((tp->tcp_header_len << 26) |
471 ntohl(TCP_FLAG_ACK) |
472 snd_wnd);
473}
474
475static __inline__ void tcp_fast_path_on(struct tcp_sock *tp)
476{
477 __tcp_fast_path_on(tp, tp->snd_wnd >> tp->rx_opt.snd_wscale);
478}
479
480static inline void tcp_fast_path_check(struct sock *sk, struct tcp_sock *tp)
481{
b03efcfb 482 if (skb_queue_empty(&tp->out_of_order_queue) &&
1da177e4
LT		 483 tp->rcv_wnd &&
484 atomic_read(&sk->sk_rmem_alloc) < sk->sk_rcvbuf &&
485 !tp->urg_data)
486 tcp_fast_path_on(tp);
487}
488
489/* Compute the actual receive window we are currently advertising.
490 * Rcv_nxt can be after the window if our peer push more data
491 * than the offered window.
492 */
493static __inline__ u32 tcp_receive_window(const struct tcp_sock *tp)
494{
495 s32 win = tp->rcv_wup + tp->rcv_wnd - tp->rcv_nxt;
496
497 if (win < 0)
498 win = 0;
499 return (u32) win;
500}
501
502/* Choose a new window, without checks for shrinking, and without
503 * scaling applied to the result. The caller does these things
504 * if necessary. This is a "raw" window selection.
505 */
506extern u32 __tcp_select_window(struct sock *sk);
507
508/* TCP timestamps are only 32-bits, this causes a slight
509 * complication on 64-bit systems since we store a snapshot
31f34269
SH		 510 * of jiffies in the buffer control blocks below. We decided
511 * to use only the low 32-bits of jiffies and hide the ugly
1da177e4
LT		 512 * casts with the following macro.
513 */
514#define tcp_time_stamp ((__u32)(jiffies))
515
caa20d9a 516/* This is what the send packet queuing engine uses to pass
1da177e4
LT		 517 * TCP per-packet control information to the transmission
518 * code. We also store the host-order sequence numbers in
519 * here too. This is 36 bytes on 32-bit architectures,
520 * 40 bytes on 64-bit machines, if this grows please adjust
521 * skbuff.h:skbuff->cb[xxx] size appropriately.
522 */
523struct tcp_skb_cb {
524 union {
525 struct inet_skb_parm h4;
526#if defined(CONFIG_IPV6) || defined (CONFIG_IPV6_MODULE)
527 struct inet6_skb_parm h6;
528#endif
529 } header; /* For incoming frames */
530 __u32 seq; /* Starting sequence number */
531 __u32 end_seq; /* SEQ + FIN + SYN + datalen */
532 __u32 when; /* used to compute rtt's */
533 __u8 flags; /* TCP header flags. */
534
535 /* NOTE: These must match up to the flags byte in a
536 * real TCP header.
537 */
538#define TCPCB_FLAG_FIN 0x01
539#define TCPCB_FLAG_SYN 0x02
540#define TCPCB_FLAG_RST 0x04
541#define TCPCB_FLAG_PSH 0x08
542#define TCPCB_FLAG_ACK 0x10
543#define TCPCB_FLAG_URG 0x20
544#define TCPCB_FLAG_ECE 0x40
545#define TCPCB_FLAG_CWR 0x80
546
547 __u8 sacked; /* State flags for SACK/FACK. */
548#define TCPCB_SACKED_ACKED 0x01 /* SKB ACK'd by a SACK block */
549#define TCPCB_SACKED_RETRANS 0x02 /* SKB retransmitted */
550#define TCPCB_LOST 0x04 /* SKB is lost */
551#define TCPCB_TAGBITS 0x07 /* All tag bits */
552
553#define TCPCB_EVER_RETRANS 0x80 /* Ever retransmitted frame */
554#define TCPCB_RETRANS (TCPCB_SACKED_RETRANS|TCPCB_EVER_RETRANS)
555
caa20d9a 556#define TCPCB_URG 0x20 /* Urgent pointer advanced here */
1da177e4
LT		 557
558#define TCPCB_AT_TAIL (TCPCB_URG)
559
560 __u16 urg_ptr; /* Valid w/URG flags is set. */
561 __u32 ack_seq; /* Sequence number ACK'd */
562};
563
564#define TCP_SKB_CB(__skb) ((struct tcp_skb_cb *)&((__skb)->cb[0]))
565
566#include <net/tcp_ecn.h>
567
568/* Due to TSO, an SKB can be composed of multiple actual
569 * packets. To keep these tracked properly, we use this.
570 */
571static inline int tcp_skb_pcount(const struct sk_buff *skb)
572{
573 return skb_shinfo(skb)->tso_segs;
574}
575
576/* This is valid iff tcp_skb_pcount() > 1. */
577static inline int tcp_skb_mss(const struct sk_buff *skb)
578{
579 return skb_shinfo(skb)->tso_size;
580}
581
582static inline void tcp_dec_pcount_approx(__u32 *count,
583 const struct sk_buff *skb)
584{
585 if (*count) {
586 *count -= tcp_skb_pcount(skb);
587 if ((int)*count < 0)
588 *count = 0;
589 }
590}
591
592static inline void tcp_packets_out_inc(struct sock *sk,
593 struct tcp_sock *tp,
594 const struct sk_buff *skb)
595{
596 int orig = tp->packets_out;
597
598 tp->packets_out += tcp_skb_pcount(skb);
599 if (!orig)
3f421baa
ACM		 600 inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS,
601 inet_csk(sk)->icsk_rto, TCP_RTO_MAX);
1da177e4
LT		 602}
603
604static inline void tcp_packets_out_dec(struct tcp_sock *tp,
605 const struct sk_buff *skb)
606{
607 tp->packets_out -= tcp_skb_pcount(skb);
608}
609
317a76f9
SH		 610/* Events passed to congestion control interface */
611enum tcp_ca_event {
612 CA_EVENT_TX_START, /* first transmit when no packets in flight */
613 CA_EVENT_CWND_RESTART, /* congestion window restart */
614 CA_EVENT_COMPLETE_CWR, /* end of congestion recovery */
615 CA_EVENT_FRTO, /* fast recovery timeout */
616 CA_EVENT_LOSS, /* loss timeout */
617 CA_EVENT_FAST_ACK, /* in sequence ack */
618 CA_EVENT_SLOW_ACK, /* other ack */
619};
620
621/*
622 * Interface for adding new TCP congestion control handlers
623 */
624#define TCP_CA_NAME_MAX 16
625struct tcp_congestion_ops {
626 struct list_head list;
627
628 /* initialize private data (optional) */
6687e988 629 void (*init)(struct sock *sk);
317a76f9 630 /* cleanup private data (optional) */
6687e988 631 void (*release)(struct sock *sk);
317a76f9
SH		 632
633 /* return slow start threshold (required) */
6687e988 634 u32 (*ssthresh)(struct sock *sk);
317a76f9 635 /* lower bound for congestion window (optional) */
6687e988 636 u32 (*min_cwnd)(struct sock *sk);
317a76f9 637 /* do new cwnd calculation (required) */
6687e988 638 void (*cong_avoid)(struct sock *sk, u32 ack,
317a76f9
SH		 639 u32 rtt, u32 in_flight, int good_ack);
640 /* round trip time sample per acked packet (optional) */
6687e988 641 void (*rtt_sample)(struct sock *sk, u32 usrtt);
317a76f9 642 /* call before changing ca_state (optional) */
6687e988 643 void (*set_state)(struct sock *sk, u8 new_state);
317a76f9 644 /* call when cwnd event occurs (optional) */
6687e988 645 void (*cwnd_event)(struct sock *sk, enum tcp_ca_event ev);
317a76f9 646 /* new value of cwnd after loss (optional) */
6687e988 647 u32 (*undo_cwnd)(struct sock *sk);
317a76f9 648 /* hook for packet ack accounting (optional) */
6687e988 649 void (*pkts_acked)(struct sock *sk, u32 num_acked);
73c1f4a0 650 /* get info for inet_diag (optional) */
6687e988 651 void (*get_info)(struct sock *sk, u32 ext, struct sk_buff *skb);
317a76f9
SH		 652
653 char name[TCP_CA_NAME_MAX];
654 struct module *owner;
655};
656
657extern int tcp_register_congestion_control(struct tcp_congestion_ops *type);
658extern void tcp_unregister_congestion_control(struct tcp_congestion_ops *type);
659
6687e988
ACM		 660extern void tcp_init_congestion_control(struct sock *sk);
661extern void tcp_cleanup_congestion_control(struct sock *sk);
317a76f9
SH		 662extern int tcp_set_default_congestion_control(const char *name);
663extern void tcp_get_default_congestion_control(char *name);
6687e988 664extern int tcp_set_congestion_control(struct sock *sk, const char *name);
317a76f9 665
5f8ef48d 666extern struct tcp_congestion_ops tcp_init_congestion_ops;
6687e988
ACM		 667extern u32 tcp_reno_ssthresh(struct sock *sk);
668extern void tcp_reno_cong_avoid(struct sock *sk, u32 ack,
317a76f9 669 u32 rtt, u32 in_flight, int flag);
6687e988 670extern u32 tcp_reno_min_cwnd(struct sock *sk);
a8acfbac 671extern struct tcp_congestion_ops tcp_reno;
317a76f9 672
6687e988 673static inline void tcp_set_ca_state(struct sock *sk, const u8 ca_state)
317a76f9 674{
6687e988
ACM		 675 struct inet_connection_sock *icsk = inet_csk(sk);
676
677 if (icsk->icsk_ca_ops->set_state)
678 icsk->icsk_ca_ops->set_state(sk, ca_state);
679 icsk->icsk_ca_state = ca_state;
317a76f9
SH		 680}
681
6687e988 682static inline void tcp_ca_event(struct sock *sk, const enum tcp_ca_event event)
317a76f9 683{
6687e988
ACM		 684 const struct inet_connection_sock *icsk = inet_csk(sk);
685
686 if (icsk->icsk_ca_ops->cwnd_event)
687 icsk->icsk_ca_ops->cwnd_event(sk, event);
317a76f9
SH		 688}
689
1da177e4
LT		 690/* This determines how many packets are "in the network" to the best
691 * of our knowledge. In many cases it is conservative, but where
692 * detailed information is available from the receiver (via SACK
693 * blocks etc.) we can make more aggressive calculations.
694 *
695 * Use this for decisions involving congestion control, use just
696 * tp->packets_out to determine if the send queue is empty or not.
697 *
698 * Read this equation as:
699 *
700 * "Packets sent once on transmission queue" MINUS
701 * "Packets left network, but not honestly ACKed yet" PLUS
702 * "Packets fast retransmitted"
703 */
704static __inline__ unsigned int tcp_packets_in_flight(const struct tcp_sock *tp)
705{
706 return (tp->packets_out - tp->left_out + tp->retrans_out);
707}
708
1da177e4
LT		 709/* If cwnd > ssthresh, we may raise ssthresh to be half-way to cwnd.
710 * The exception is rate halving phase, when cwnd is decreasing towards
711 * ssthresh.
712 */
6687e988 713static inline __u32 tcp_current_ssthresh(const struct sock *sk)
1da177e4 714{
6687e988
ACM		 715 const struct tcp_sock *tp = tcp_sk(sk);
716 if ((1 << inet_csk(sk)->icsk_ca_state) & (TCPF_CA_CWR | TCPF_CA_Recovery))
1da177e4
LT		 717 return tp->snd_ssthresh;
718 else
719 return max(tp->snd_ssthresh,
720 ((tp->snd_cwnd >> 1) +
721 (tp->snd_cwnd >> 2)));
722}
723
7faffa1c
SH		 724/*
725 * Linear increase during slow start
726 */
727static inline void tcp_slow_start(struct tcp_sock *tp)
728{
9772efb9
SH		 729 if (sysctl_tcp_abc) {
730 /* RFC3465: Slow Start
731 * TCP sender SHOULD increase cwnd by the number of
732 * previously unacknowledged bytes ACKed by each incoming
733 * acknowledgment, provided the increase is not more than L
734 */
735 if (tp->bytes_acked < tp->mss_cache)
736 return;
737
738 /* We MAY increase by 2 if discovered delayed ack */
739 if (sysctl_tcp_abc > 1 && tp->bytes_acked > 2*tp->mss_cache) {
740 if (tp->snd_cwnd < tp->snd_cwnd_clamp)
741 tp->snd_cwnd++;
742 }
743 }
744 tp->bytes_acked = 0;
745
7faffa1c
SH		 746 if (tp->snd_cwnd < tp->snd_cwnd_clamp)
747 tp->snd_cwnd++;
748}
749
750
1da177e4
LT		 751static inline void tcp_sync_left_out(struct tcp_sock *tp)
752{
753 if (tp->rx_opt.sack_ok &&
754 (tp->sacked_out >= tp->packets_out - tp->lost_out))
755 tp->sacked_out = tp->packets_out - tp->lost_out;
756 tp->left_out = tp->sacked_out + tp->lost_out;
757}
758
d1b04c08 759/* Set slow start threshold and cwnd not falling to slow start */
6687e988 760static inline void __tcp_enter_cwr(struct sock *sk)
1da177e4 761{
6687e988
ACM		 762 const struct inet_connection_sock *icsk = inet_csk(sk);
763 struct tcp_sock *tp = tcp_sk(sk);
764
1da177e4 765 tp->undo_marker = 0;
6687e988 766 tp->snd_ssthresh = icsk->icsk_ca_ops->ssthresh(sk);
1da177e4
LT		 767 tp->snd_cwnd = min(tp->snd_cwnd,
768 tcp_packets_in_flight(tp) + 1U);
769 tp->snd_cwnd_cnt = 0;
770 tp->high_seq = tp->snd_nxt;
771 tp->snd_cwnd_stamp = tcp_time_stamp;
772 TCP_ECN_queue_cwr(tp);
773}
774
6687e988 775static inline void tcp_enter_cwr(struct sock *sk)
1da177e4 776{
6687e988
ACM		 777 struct tcp_sock *tp = tcp_sk(sk);
778
1da177e4 779 tp->prior_ssthresh = 0;
9772efb9 780 tp->bytes_acked = 0;
6687e988
ACM		 781 if (inet_csk(sk)->icsk_ca_state < TCP_CA_CWR) {
782 __tcp_enter_cwr(sk);
783 tcp_set_ca_state(sk, TCP_CA_CWR);
1da177e4
LT		 784 }
785}
786
787extern __u32 tcp_init_cwnd(struct tcp_sock *tp, struct dst_entry *dst);
788
789/* Slow start with delack produces 3 packets of burst, so that
790 * it is safe "de facto".
791 */
792static __inline__ __u32 tcp_max_burst(const struct tcp_sock *tp)
793{
794 return 3;
795}
796
f4805ede
SH		 797/* RFC2861 Check whether we are limited by application or congestion window
798 * This is the inverse of cwnd check in tcp_tso_should_defer
799 */
800static inline int tcp_is_cwnd_limited(const struct sock *sk, u32 in_flight)
801{
802 const struct tcp_sock *tp = tcp_sk(sk);
803 u32 left;
804
805 if (in_flight >= tp->snd_cwnd)
806 return 1;
807
808 if (!(sk->sk_route_caps & NETIF_F_TSO))
809 return 0;
810
811 left = tp->snd_cwnd - in_flight;
812 if (sysctl_tcp_tso_win_divisor)
813 return left * sysctl_tcp_tso_win_divisor < tp->snd_cwnd;
814 else
815 return left <= tcp_max_burst(tp);
816}
817
1da177e4
LT		 818static __inline__ void tcp_minshall_update(struct tcp_sock *tp, int mss,
819 const struct sk_buff *skb)
820{
821 if (skb->len < mss)
822 tp->snd_sml = TCP_SKB_CB(skb)->end_seq;
823}
824
1da177e4
LT		 825static __inline__ void tcp_check_probe_timer(struct sock *sk, struct tcp_sock *tp)
826{
463c84b9
ACM		 827 const struct inet_connection_sock *icsk = inet_csk(sk);
828 if (!tp->packets_out && !icsk->icsk_pending)
3f421baa
ACM		 829 inet_csk_reset_xmit_timer(sk, ICSK_TIME_PROBE0,
830 icsk->icsk_rto, TCP_RTO_MAX);
1da177e4
LT		 831}
832
1da177e4
LT		 833static __inline__ void tcp_push_pending_frames(struct sock *sk,
834 struct tcp_sock *tp)
835{
836 __tcp_push_pending_frames(sk, tp, tcp_current_mss(sk, 1), tp->nonagle);
837}
838
1da177e4
LT		 839static __inline__ void tcp_init_wl(struct tcp_sock *tp, u32 ack, u32 seq)
840{
841 tp->snd_wl1 = seq;
842}
843
844static __inline__ void tcp_update_wl(struct tcp_sock *tp, u32 ack, u32 seq)
845{
846 tp->snd_wl1 = seq;
847}
848
1da177e4
LT		 849/*
850 * Calculate(/check) TCP checksum
851 */
852static __inline__ u16 tcp_v4_check(struct tcphdr *th, int len,
853 unsigned long saddr, unsigned long daddr,
854 unsigned long base)
855{
856 return csum_tcpudp_magic(saddr,daddr,len,IPPROTO_TCP,base);
857}
858
859static __inline__ int __tcp_checksum_complete(struct sk_buff *skb)
860{
fb286bb2 861 return __skb_checksum_complete(skb);
1da177e4
LT		 862}
863
864static __inline__ int tcp_checksum_complete(struct sk_buff *skb)
865{
866 return skb->ip_summed != CHECKSUM_UNNECESSARY &&
867 __tcp_checksum_complete(skb);
868}
869
870/* Prequeue for VJ style copy to user, combined with checksumming. */
871
872static __inline__ void tcp_prequeue_init(struct tcp_sock *tp)
873{
874 tp->ucopy.task = NULL;
875 tp->ucopy.len = 0;
876 tp->ucopy.memory = 0;
877 skb_queue_head_init(&tp->ucopy.prequeue);
878}
879
880/* Packet is added to VJ-style prequeue for processing in process
881 * context, if a reader task is waiting. Apparently, this exciting
882 * idea (VJ's mail "Re: query about TCP header on tcp-ip" of 07 Sep 93)
883 * failed somewhere. Latency? Burstiness? Well, at least now we will
884 * see, why it failed. 8)8) --ANK
885 *
886 * NOTE: is this not too big to inline?
887 */
888static __inline__ int tcp_prequeue(struct sock *sk, struct sk_buff *skb)
889{
890 struct tcp_sock *tp = tcp_sk(sk);
891
892 if (!sysctl_tcp_low_latency && tp->ucopy.task) {
893 __skb_queue_tail(&tp->ucopy.prequeue, skb);
894 tp->ucopy.memory += skb->truesize;
895 if (tp->ucopy.memory > sk->sk_rcvbuf) {
896 struct sk_buff *skb1;
897
898 BUG_ON(sock_owned_by_user(sk));
899
900 while ((skb1 = __skb_dequeue(&tp->ucopy.prequeue)) != NULL) {
901 sk->sk_backlog_rcv(sk, skb1);
902 NET_INC_STATS_BH(LINUX_MIB_TCPPREQUEUEDROPPED);
903 }
904
905 tp->ucopy.memory = 0;
906 } else if (skb_queue_len(&tp->ucopy.prequeue) == 1) {
907 wake_up_interruptible(sk->sk_sleep);
463c84b9
ACM		 908 if (!inet_csk_ack_scheduled(sk))
909 inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK,
3f421baa
ACM		 910 (3 * TCP_RTO_MIN) / 4,
911 TCP_RTO_MAX);
1da177e4
LT		 912 }
913 return 1;
914 }
915 return 0;
916}
917
918
919#undef STATE_TRACE
920
921#ifdef STATE_TRACE
922static const char *statename[]={
923 "Unused","Established","Syn Sent","Syn Recv",
924 "Fin Wait 1","Fin Wait 2","Time Wait", "Close",
925 "Close Wait","Last ACK","Listen","Closing"
926};
927#endif
928
929static __inline__ void tcp_set_state(struct sock *sk, int state)
930{
931 int oldstate = sk->sk_state;
932
933 switch (state) {
934 case TCP_ESTABLISHED:
935 if (oldstate != TCP_ESTABLISHED)
936 TCP_INC_STATS(TCP_MIB_CURRESTAB);
937 break;
938
939 case TCP_CLOSE:
940 if (oldstate == TCP_CLOSE_WAIT || oldstate == TCP_ESTABLISHED)
941 TCP_INC_STATS(TCP_MIB_ESTABRESETS);
942
943 sk->sk_prot->unhash(sk);
463c84b9 944 if (inet_csk(sk)->icsk_bind_hash &&
1da177e4 945 !(sk->sk_userlocks & SOCK_BINDPORT_LOCK))
2d8c4ce5 946 inet_put_port(&tcp_hashinfo, sk);
1da177e4
LT		 947 /* fall through */
948 default:
949 if (oldstate==TCP_ESTABLISHED)
950 TCP_DEC_STATS(TCP_MIB_CURRESTAB);
951 }
952
953 /* Change state AFTER socket is unhashed to avoid closed
954 * socket sitting in hash tables.
955 */
956 sk->sk_state = state;
957
958#ifdef STATE_TRACE
959 SOCK_DEBUG(sk, "TCP sk=%p, State %s -> %s\n",sk, statename[oldstate],statename[state]);
960#endif
961}
962
963static __inline__ void tcp_done(struct sock *sk)
964{
965 tcp_set_state(sk, TCP_CLOSE);
966 tcp_clear_xmit_timers(sk);
967
968 sk->sk_shutdown = SHUTDOWN_MASK;
969
970 if (!sock_flag(sk, SOCK_DEAD))
971 sk->sk_state_change(sk);
972 else
0a5578cf 973 inet_csk_destroy_sock(sk);
1da177e4
LT		 974}
975
976static __inline__ void tcp_sack_reset(struct tcp_options_received *rx_opt)
977{
978 rx_opt->dsack = 0;
979 rx_opt->eff_sacks = 0;
980 rx_opt->num_sacks = 0;
981}
982
983static __inline__ void tcp_build_and_update_options(__u32 *ptr, struct tcp_sock *tp, __u32 tstamp)
984{
985 if (tp->rx_opt.tstamp_ok) {
986 *ptr++ = __constant_htonl((TCPOPT_NOP << 24) |
987 (TCPOPT_NOP << 16) |
988 (TCPOPT_TIMESTAMP << 8) |
989 TCPOLEN_TIMESTAMP);
990 *ptr++ = htonl(tstamp);
991 *ptr++ = htonl(tp->rx_opt.ts_recent);
992 }
993 if (tp->rx_opt.eff_sacks) {
994 struct tcp_sack_block *sp = tp->rx_opt.dsack ? tp->duplicate_sack : tp->selective_acks;
995 int this_sack;
996
8639a11e
ACM		 997 *ptr++ = htonl((TCPOPT_NOP << 24) |
998 (TCPOPT_NOP << 16) |
999 (TCPOPT_SACK << 8) |
1000 (TCPOLEN_SACK_BASE + (tp->rx_opt.eff_sacks *
1001 TCPOLEN_SACK_PERBLOCK)));
1da177e4
LT		 1002 for(this_sack = 0; this_sack < tp->rx_opt.eff_sacks; this_sack++) {
1003 *ptr++ = htonl(sp[this_sack].start_seq);
1004 *ptr++ = htonl(sp[this_sack].end_seq);
1005 }
1006 if (tp->rx_opt.dsack) {
1007 tp->rx_opt.dsack = 0;
1008 tp->rx_opt.eff_sacks--;
1009 }
1010 }
1011}
1012
1013/* Construct a tcp options header for a SYN or SYN_ACK packet.
1014 * If this is every changed make sure to change the definition of
1015 * MAX_SYN_SIZE to match the new maximum number of options that you
1016 * can generate.
1017 */
1018static inline void tcp_syn_build_options(__u32 *ptr, int mss, int ts, int sack,
1019 int offer_wscale, int wscale, __u32 tstamp, __u32 ts_recent)
1020{
1021 /* We always get an MSS option.
1022 * The option bytes which will be seen in normal data
1023 * packets should timestamps be used, must be in the MSS
1024 * advertised. But we subtract them from tp->mss_cache so
1025 * that calculations in tcp_sendmsg are simpler etc.
1026 * So account for this fact here if necessary. If we
1027 * don't do this correctly, as a receiver we won't
1028 * recognize data packets as being full sized when we
1029 * should, and thus we won't abide by the delayed ACK
1030 * rules correctly.
1031 * SACKs don't matter, we never delay an ACK when we
1032 * have any of those going out.
1033 */
1034 *ptr++ = htonl((TCPOPT_MSS << 24) | (TCPOLEN_MSS << 16) | mss);
1035 if (ts) {
1036 if(sack)
1037 *ptr++ = __constant_htonl((TCPOPT_SACK_PERM << 24) | (TCPOLEN_SACK_PERM << 16) |
1038 (TCPOPT_TIMESTAMP << 8) | TCPOLEN_TIMESTAMP);
1039 else
1040 *ptr++ = __constant_htonl((TCPOPT_NOP << 24) | (TCPOPT_NOP << 16) |
1041 (TCPOPT_TIMESTAMP << 8) | TCPOLEN_TIMESTAMP);
1042 *ptr++ = htonl(tstamp); /* TSVAL */
1043 *ptr++ = htonl(ts_recent); /* TSECR */
1044 } else if(sack)
1045 *ptr++ = __constant_htonl((TCPOPT_NOP << 24) | (TCPOPT_NOP << 16) |
1046 (TCPOPT_SACK_PERM << 8) | TCPOLEN_SACK_PERM);
1047 if (offer_wscale)
1048 *ptr++ = htonl((TCPOPT_NOP << 24) | (TCPOPT_WINDOW << 16) | (TCPOLEN_WINDOW << 8) | (wscale));
1049}
1050
1051/* Determine a window scaling and initial window to offer. */
1052extern void tcp_select_initial_window(int __space, __u32 mss,
1053 __u32 *rcv_wnd, __u32 *window_clamp,
1054 int wscale_ok, __u8 *rcv_wscale);
1055
1056static inline int tcp_win_from_space(int space)
1057{
1058 return sysctl_tcp_adv_win_scale<=0 ?
1059 (space>>(-sysctl_tcp_adv_win_scale)) :
1060 space - (space>>sysctl_tcp_adv_win_scale);
1061}
1062
1063/* Note: caller must be prepared to deal with negative returns */
1064static inline int tcp_space(const struct sock *sk)
1065{
1066 return tcp_win_from_space(sk->sk_rcvbuf -
1067 atomic_read(&sk->sk_rmem_alloc));
1068}
1069
1070static inline int tcp_full_space(const struct sock *sk)
1071{
1072 return tcp_win_from_space(sk->sk_rcvbuf);
1073}
1074
60236fdd 1075static __inline__ void tcp_openreq_init(struct request_sock *req,
1da177e4
LT		 1076 struct tcp_options_received *rx_opt,
1077 struct sk_buff *skb)
1078{
2e6599cb
ACM		 1079 struct inet_request_sock *ireq = inet_rsk(req);
1080
1da177e4 1081 req->rcv_wnd = 0; /* So that tcp_send_synack() knows! */
2e6599cb 1082 tcp_rsk(req)->rcv_isn = TCP_SKB_CB(skb)->seq;
1da177e4
LT		 1083 req->mss = rx_opt->mss_clamp;
1084 req->ts_recent = rx_opt->saw_tstamp ? rx_opt->rcv_tsval : 0;
2e6599cb
ACM		 1085 ireq->tstamp_ok = rx_opt->tstamp_ok;
1086 ireq->sack_ok = rx_opt->sack_ok;
1087 ireq->snd_wscale = rx_opt->snd_wscale;
1088 ireq->wscale_ok = rx_opt->wscale_ok;
1089 ireq->acked = 0;
1090 ireq->ecn_ok = 0;
1091 ireq->rmt_port = skb->h.th->source;
1da177e4
LT		 1092}
1093
1094extern void tcp_enter_memory_pressure(void);
1095
1da177e4
LT		 1096static inline int keepalive_intvl_when(const struct tcp_sock *tp)
1097{
1098 return tp->keepalive_intvl ? : sysctl_tcp_keepalive_intvl;
1099}
1100
1101static inline int keepalive_time_when(const struct tcp_sock *tp)
1102{
1103 return tp->keepalive_time ? : sysctl_tcp_keepalive_time;
1104}
1105
463c84b9 1106static inline int tcp_fin_time(const struct sock *sk)
1da177e4 1107{
463c84b9
ACM		 1108 int fin_timeout = tcp_sk(sk)->linger2 ? : sysctl_tcp_fin_timeout;
1109 const int rto = inet_csk(sk)->icsk_rto;
1da177e4 1110
463c84b9
ACM		 1111 if (fin_timeout < (rto << 2) - (rto >> 1))
1112 fin_timeout = (rto << 2) - (rto >> 1);
1da177e4
LT		 1113
1114 return fin_timeout;
1115}
1116
1117static inline int tcp_paws_check(const struct tcp_options_received *rx_opt, int rst)
1118{
1119 if ((s32)(rx_opt->rcv_tsval - rx_opt->ts_recent) >= 0)
1120 return 0;
1121 if (xtime.tv_sec >= rx_opt->ts_recent_stamp + TCP_PAWS_24DAYS)
1122 return 0;
1123
1124 /* RST segments are not recommended to carry timestamp,
1125 and, if they do, it is recommended to ignore PAWS because
1126 "their cleanup function should take precedence over timestamps."
1127 Certainly, it is mistake. It is necessary to understand the reasons
1128 of this constraint to relax it: if peer reboots, clock may go
1129 out-of-sync and half-open connections will not be reset.
1130 Actually, the problem would be not existing if all
1131 the implementations followed draft about maintaining clock
1132 via reboots. Linux-2.2 DOES NOT!
1133
1134 However, we can relax time bounds for RST segments to MSL.
1135 */
1136 if (rst && xtime.tv_sec >= rx_opt->ts_recent_stamp + TCP_PAWS_MSL)
1137 return 0;
1138 return 1;
1139}
1140
1da177e4
LT		 1141#define TCP_CHECK_TIMER(sk) do { } while (0)
1142
1143static inline int tcp_use_frto(const struct sock *sk)
1144{
1145 const struct tcp_sock *tp = tcp_sk(sk);
1146
1147 /* F-RTO must be activated in sysctl and there must be some
1148 * unsent new data, and the advertised window should allow
1149 * sending it.
1150 */
1151 return (sysctl_tcp_frto && sk->sk_send_head &&
1152 !after(TCP_SKB_CB(sk->sk_send_head)->end_seq,
1153 tp->snd_una + tp->snd_wnd));
1154}
1155
1156static inline void tcp_mib_init(void)
1157{
1158 /* See RFC 2012 */
1159 TCP_ADD_STATS_USER(TCP_MIB_RTOALGORITHM, 1);
1160 TCP_ADD_STATS_USER(TCP_MIB_RTOMIN, TCP_RTO_MIN*1000/HZ);
1161 TCP_ADD_STATS_USER(TCP_MIB_RTOMAX, TCP_RTO_MAX*1000/HZ);
1162 TCP_ADD_STATS_USER(TCP_MIB_MAXCONN, -1);
1163}
1164
6a438bbe
SH		 1165/*from STCP */
1166static inline void clear_all_retrans_hints(struct tcp_sock *tp){
1167 tp->lost_skb_hint = NULL;
1168 tp->scoreboard_skb_hint = NULL;
1169 tp->retransmit_skb_hint = NULL;
1170 tp->forward_skb_hint = NULL;
1171 tp->fastpath_skb_hint = NULL;
1172}
1173
1da177e4
LT		 1174/* /proc */
1175enum tcp_seq_states {
1176 TCP_SEQ_STATE_LISTENING,
1177 TCP_SEQ_STATE_OPENREQ,
1178 TCP_SEQ_STATE_ESTABLISHED,
1179 TCP_SEQ_STATE_TIME_WAIT,
1180};
1181
1182struct tcp_seq_afinfo {
1183 struct module *owner;
1184 char *name;
1185 sa_family_t family;
1186 int (*seq_show) (struct seq_file *m, void *v);
1187 struct file_operations *seq_fops;
1188};
1189
1190struct tcp_iter_state {
1191 sa_family_t family;
1192 enum tcp_seq_states state;
1193 struct sock *syn_wait_sk;
1194 int bucket, sbucket, num, uid;
1195 struct seq_operations seq_ops;
1196};
1197
1198extern int tcp_proc_register(struct tcp_seq_afinfo *afinfo);
1199extern void tcp_proc_unregister(struct tcp_seq_afinfo *afinfo);
1200
20380731
ACM		 1201extern struct request_sock_ops tcp_request_sock_ops;
1202
1203extern int tcp_v4_destroy_sock(struct sock *sk);
1204
1205#ifdef CONFIG_PROC_FS
1206extern int tcp4_proc_init(void);
1207extern void tcp4_proc_exit(void);
1208#endif
1209
1210extern void tcp_v4_init(struct net_proto_family *ops);
1211extern void tcp_init(void);
1212
1da177e4 1213#endif /* _TCP_H */
kernel source for telekom puls (alcatel/mediatek)