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TCPCT part 1b: generate Responder Cookie secret
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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
34#include <net/inet_connection_sock.h>
35#include <net/inet_timewait_sock.h>
36#include <net/inet_hashtables.h>
37#include <net/checksum.h>
38#include <net/request_sock.h>
39#include <net/sock.h>
40#include <net/snmp.h>
41#include <net/ip.h>
42#include <net/tcp_states.h>
43#include <net/inet_ecn.h>
44#include <net/dst.h>
45
46#include <linux/seq_file.h>
47
48extern struct inet_hashinfo tcp_hashinfo;
49
50extern struct percpu_counter tcp_orphan_count;
51extern void tcp_time_wait(struct sock *sk, int state, int timeo);
52
53#define MAX_TCP_HEADER (128 + MAX_HEADER)
54#define MAX_TCP_OPTION_SPACE 40
55
56/*
57 * Never offer a window over 32767 without using window scaling. Some
58 * poor stacks do signed 16bit maths!
59 */
60#define MAX_TCP_WINDOW 32767U
61
62/* Minimal accepted MSS. It is (60+60+8) - (20+20). */
63#define TCP_MIN_MSS 88U
64
65/* The least MTU to use for probing */
66#define TCP_BASE_MSS 512
67
68/* After receiving this amount of duplicate ACKs fast retransmit starts. */
69#define TCP_FASTRETRANS_THRESH 3
70
71/* Maximal reordering. */
72#define TCP_MAX_REORDERING 127
73
74/* Maximal number of ACKs sent quickly to accelerate slow-start. */
75#define TCP_MAX_QUICKACKS 16U
76
77/* urg_data states */
78#define TCP_URG_VALID 0x0100
79#define TCP_URG_NOTYET 0x0200
80#define TCP_URG_READ 0x0400
81
82#define TCP_RETR1 3 /*
83 * This is how many retries it does before it
84 * tries to figure out if the gateway is
85 * down. Minimal RFC value is 3; it corresponds
86 * to ~3sec-8min depending on RTO.
87 */
88
89#define TCP_RETR2 15 /*
90 * This should take at least
91 * 90 minutes to time out.
92 * RFC1122 says that the limit is 100 sec.
93 * 15 is ~13-30min depending on RTO.
94 */
95
96#define TCP_SYN_RETRIES 5 /* number of times to retry active opening a
97 * connection: ~180sec is RFC minimum */
98
99#define TCP_SYNACK_RETRIES 5 /* number of times to retry passive opening a
100 * connection: ~180sec is RFC minimum */
101
102
103#define TCP_ORPHAN_RETRIES 7 /* number of times to retry on an orphaned
104 * socket. 7 is ~50sec-16min.
105 */
106
107
108#define TCP_TIMEWAIT_LEN (60*HZ) /* how long to wait to destroy TIME-WAIT
109 * state, about 60 seconds */
110#define TCP_FIN_TIMEOUT TCP_TIMEWAIT_LEN
111 /* BSD style FIN_WAIT2 deadlock breaker.
112 * It used to be 3min, new value is 60sec,
113 * to combine FIN-WAIT-2 timeout with
114 * TIME-WAIT timer.
115 */
116
117#define TCP_DELACK_MAX ((unsigned)(HZ/5)) /* maximal time to delay before sending an ACK */
118#if HZ >= 100
119#define TCP_DELACK_MIN ((unsigned)(HZ/25)) /* minimal time to delay before sending an ACK */
120#define TCP_ATO_MIN ((unsigned)(HZ/25))
121#else
122#define TCP_DELACK_MIN 4U
123#define TCP_ATO_MIN 4U
124#endif
125#define TCP_RTO_MAX ((unsigned)(120*HZ))
126#define TCP_RTO_MIN ((unsigned)(HZ/5))
127#define TCP_TIMEOUT_INIT ((unsigned)(3*HZ)) /* RFC 1122 initial RTO value */
128
129#define TCP_RESOURCE_PROBE_INTERVAL ((unsigned)(HZ/2U)) /* Maximal interval between probes
130 * for local resources.
131 */
132
133#define TCP_KEEPALIVE_TIME (120*60*HZ) /* two hours */
134#define TCP_KEEPALIVE_PROBES 9 /* Max of 9 keepalive probes */
135#define TCP_KEEPALIVE_INTVL (75*HZ)
136
137#define MAX_TCP_KEEPIDLE 32767
138#define MAX_TCP_KEEPINTVL 32767
139#define MAX_TCP_KEEPCNT 127
140#define MAX_TCP_SYNCNT 127
141
142#define TCP_SYNQ_INTERVAL (HZ/5) /* Period of SYNACK timer */
143
144#define TCP_PAWS_24DAYS (60 * 60 * 24 * 24)
145#define TCP_PAWS_MSL 60 /* Per-host timestamps are invalidated
146 * after this time. It should be equal
147 * (or greater than) TCP_TIMEWAIT_LEN
148 * to provide reliability equal to one
149 * provided by timewait state.
150 */
151#define TCP_PAWS_WINDOW 1 /* Replay window for per-host
152 * timestamps. It must be less than
153 * minimal timewait lifetime.
154 */
155/*
156 * TCP option
157 */
158
159#define TCPOPT_NOP 1 /* Padding */
160#define TCPOPT_EOL 0 /* End of options */
161#define TCPOPT_MSS 2 /* Segment size negotiating */
162#define TCPOPT_WINDOW 3 /* Window scaling */
163#define TCPOPT_SACK_PERM 4 /* SACK Permitted */
164#define TCPOPT_SACK 5 /* SACK Block */
165#define TCPOPT_TIMESTAMP 8 /* Better RTT estimations/PAWS */
166#define TCPOPT_MD5SIG 19 /* MD5 Signature (RFC2385) */
167
168/*
169 * TCP option lengths
170 */
171
172#define TCPOLEN_MSS 4
173#define TCPOLEN_WINDOW 3
174#define TCPOLEN_SACK_PERM 2
175#define TCPOLEN_TIMESTAMP 10
176#define TCPOLEN_MD5SIG 18
177
178/* But this is what stacks really send out. */
179#define TCPOLEN_TSTAMP_ALIGNED 12
180#define TCPOLEN_WSCALE_ALIGNED 4
181#define TCPOLEN_SACKPERM_ALIGNED 4
182#define TCPOLEN_SACK_BASE 2
183#define TCPOLEN_SACK_BASE_ALIGNED 4
184#define TCPOLEN_SACK_PERBLOCK 8
185#define TCPOLEN_MD5SIG_ALIGNED 20
186#define TCPOLEN_MSS_ALIGNED 4
187
188/* Flags in tp->nonagle */
189#define TCP_NAGLE_OFF 1 /* Nagle's algo is disabled */
190#define TCP_NAGLE_CORK 2 /* Socket is corked */
191#define TCP_NAGLE_PUSH 4 /* Cork is overridden for already queued data */
192
193extern struct inet_timewait_death_row tcp_death_row;
194
195/* sysctl variables for tcp */
196extern int sysctl_tcp_timestamps;
197extern int sysctl_tcp_window_scaling;
198extern int sysctl_tcp_sack;
199extern int sysctl_tcp_fin_timeout;
200extern int sysctl_tcp_keepalive_time;
201extern int sysctl_tcp_keepalive_probes;
202extern int sysctl_tcp_keepalive_intvl;
203extern int sysctl_tcp_syn_retries;
204extern int sysctl_tcp_synack_retries;
205extern int sysctl_tcp_retries1;
206extern int sysctl_tcp_retries2;
207extern int sysctl_tcp_orphan_retries;
208extern int sysctl_tcp_syncookies;
209extern int sysctl_tcp_retrans_collapse;
210extern int sysctl_tcp_stdurg;
211extern int sysctl_tcp_rfc1337;
212extern int sysctl_tcp_abort_on_overflow;
213extern int sysctl_tcp_max_orphans;
214extern int sysctl_tcp_fack;
215extern int sysctl_tcp_reordering;
216extern int sysctl_tcp_ecn;
217extern int sysctl_tcp_dsack;
218extern int sysctl_tcp_mem[3];
219extern int sysctl_tcp_wmem[3];
220extern int sysctl_tcp_rmem[3];
221extern int sysctl_tcp_app_win;
222extern int sysctl_tcp_adv_win_scale;
223extern int sysctl_tcp_tw_reuse;
224extern int sysctl_tcp_frto;
225extern int sysctl_tcp_frto_response;
226extern int sysctl_tcp_low_latency;
227extern int sysctl_tcp_dma_copybreak;
228extern int sysctl_tcp_nometrics_save;
229extern int sysctl_tcp_moderate_rcvbuf;
230extern int sysctl_tcp_tso_win_divisor;
231extern int sysctl_tcp_abc;
232extern int sysctl_tcp_mtu_probing;
233extern int sysctl_tcp_base_mss;
234extern int sysctl_tcp_workaround_signed_windows;
235extern int sysctl_tcp_slow_start_after_idle;
236extern int sysctl_tcp_max_ssthresh;
237
238extern atomic_t tcp_memory_allocated;
239extern struct percpu_counter tcp_sockets_allocated;
240extern int tcp_memory_pressure;
241
242/*
243 * The next routines deal with comparing 32 bit unsigned ints
244 * and worry about wraparound (automatic with unsigned arithmetic).
245 */
246
247static inline int before(__u32 seq1, __u32 seq2)
248{
249 return (__s32)(seq1-seq2) < 0;
250}
251#define after(seq2, seq1) before(seq1, seq2)
252
253/* is s2<=s1<=s3 ? */
254static inline int between(__u32 seq1, __u32 seq2, __u32 seq3)
255{
256 return seq3 - seq2 >= seq1 - seq2;
257}
258
259static inline int tcp_too_many_orphans(struct sock *sk, int num)
260{
261 return (num > sysctl_tcp_max_orphans) ||
262 (sk->sk_wmem_queued > SOCK_MIN_SNDBUF &&
263 atomic_read(&tcp_memory_allocated) > sysctl_tcp_mem[2]);
264}
265
266/* syncookies: remember time of last synqueue overflow */
267static inline void tcp_synq_overflow(struct sock *sk)
268{
269 tcp_sk(sk)->rx_opt.ts_recent_stamp = jiffies;
270}
271
272/* syncookies: no recent synqueue overflow on this listening socket? */
273static inline int tcp_synq_no_recent_overflow(const struct sock *sk)
274{
275 unsigned long last_overflow = tcp_sk(sk)->rx_opt.ts_recent_stamp;
276 return time_after(jiffies, last_overflow + TCP_TIMEOUT_INIT);
277}
278
279extern struct proto tcp_prot;
280
281#define TCP_INC_STATS(net, field) SNMP_INC_STATS((net)->mib.tcp_statistics, field)
282#define TCP_INC_STATS_BH(net, field) SNMP_INC_STATS_BH((net)->mib.tcp_statistics, field)
283#define TCP_DEC_STATS(net, field) SNMP_DEC_STATS((net)->mib.tcp_statistics, field)
284#define TCP_ADD_STATS_USER(net, field, val) SNMP_ADD_STATS_USER((net)->mib.tcp_statistics, field, val)
285
286extern void tcp_v4_err(struct sk_buff *skb, u32);
287
288extern void tcp_shutdown (struct sock *sk, int how);
289
290extern int tcp_v4_rcv(struct sk_buff *skb);
291
292extern int tcp_v4_remember_stamp(struct sock *sk);
293
294extern int tcp_v4_tw_remember_stamp(struct inet_timewait_sock *tw);
295
296extern int tcp_sendmsg(struct kiocb *iocb, struct socket *sock,
297 struct msghdr *msg, size_t size);
298extern ssize_t tcp_sendpage(struct socket *sock, struct page *page, int offset, size_t size, int flags);
299
300extern int tcp_ioctl(struct sock *sk,
301 int cmd,
302 unsigned long arg);
303
304extern int tcp_rcv_state_process(struct sock *sk,
305 struct sk_buff *skb,
306 struct tcphdr *th,
307 unsigned len);
308
309extern int tcp_rcv_established(struct sock *sk,
310 struct sk_buff *skb,
311 struct tcphdr *th,
312 unsigned len);
313
314extern void tcp_rcv_space_adjust(struct sock *sk);
315
316extern void tcp_cleanup_rbuf(struct sock *sk, int copied);
317
318extern int tcp_twsk_unique(struct sock *sk,
319 struct sock *sktw, void *twp);
320
321extern void tcp_twsk_destructor(struct sock *sk);
322
323extern ssize_t tcp_splice_read(struct socket *sk, loff_t *ppos,
324 struct pipe_inode_info *pipe, size_t len, unsigned int flags);
325
326static inline void tcp_dec_quickack_mode(struct sock *sk,
327 const unsigned int pkts)
328{
329 struct inet_connection_sock *icsk = inet_csk(sk);
330
331 if (icsk->icsk_ack.quick) {
332 if (pkts >= icsk->icsk_ack.quick) {
333 icsk->icsk_ack.quick = 0;
334 /* Leaving quickack mode we deflate ATO. */
335 icsk->icsk_ack.ato = TCP_ATO_MIN;
336 } else
337 icsk->icsk_ack.quick -= pkts;
338 }
339}
340
341extern void tcp_enter_quickack_mode(struct sock *sk);
342
343static inline void tcp_clear_options(struct tcp_options_received *rx_opt)
344{
345 rx_opt->tstamp_ok = rx_opt->sack_ok = rx_opt->wscale_ok = rx_opt->snd_wscale = 0;
346}
347
348#define TCP_ECN_OK 1
349#define TCP_ECN_QUEUE_CWR 2
350#define TCP_ECN_DEMAND_CWR 4
351
352static __inline__ void
353TCP_ECN_create_request(struct request_sock *req, struct tcphdr *th)
354{
355 if (sysctl_tcp_ecn && th->ece && th->cwr)
356 inet_rsk(req)->ecn_ok = 1;
357}
358
359enum tcp_tw_status {
360 TCP_TW_SUCCESS = 0,
361 TCP_TW_RST = 1,
362 TCP_TW_ACK = 2,
363 TCP_TW_SYN = 3
364};
365
366
367extern enum tcp_tw_status tcp_timewait_state_process(struct inet_timewait_sock *tw,
368 struct sk_buff *skb,
369 const struct tcphdr *th);
370
371extern struct sock * tcp_check_req(struct sock *sk,struct sk_buff *skb,
372 struct request_sock *req,
373 struct request_sock **prev);
374extern int tcp_child_process(struct sock *parent,
375 struct sock *child,
376 struct sk_buff *skb);
377extern int tcp_use_frto(struct sock *sk);
378extern void tcp_enter_frto(struct sock *sk);
379extern void tcp_enter_loss(struct sock *sk, int how);
380extern void tcp_clear_retrans(struct tcp_sock *tp);
381extern void tcp_update_metrics(struct sock *sk);
382
383extern void tcp_close(struct sock *sk,
384 long timeout);
385extern unsigned int tcp_poll(struct file * file, struct socket *sock, struct poll_table_struct *wait);
386
387extern int tcp_getsockopt(struct sock *sk, int level,
388 int optname,
389 char __user *optval,
390 int __user *optlen);
391extern int tcp_setsockopt(struct sock *sk, int level,
392 int optname, char __user *optval,
393 unsigned int optlen);
394extern int compat_tcp_getsockopt(struct sock *sk,
395 int level, int optname,
396 char __user *optval, int __user *optlen);
397extern int compat_tcp_setsockopt(struct sock *sk,
398 int level, int optname,
399 char __user *optval, unsigned int optlen);
400extern void tcp_set_keepalive(struct sock *sk, int val);
401extern int tcp_recvmsg(struct kiocb *iocb, struct sock *sk,
402 struct msghdr *msg,
403 size_t len, int nonblock,
404 int flags, int *addr_len);
405
406extern void tcp_parse_options(struct sk_buff *skb,
407 struct tcp_options_received *opt_rx,
408 int estab,
409 struct dst_entry *dst);
410
411extern u8 *tcp_parse_md5sig_option(struct tcphdr *th);
412
413/*
414 * TCP v4 functions exported for the inet6 API
415 */
416
417extern void tcp_v4_send_check(struct sock *sk, int len,
418 struct sk_buff *skb);
419
420extern int tcp_v4_conn_request(struct sock *sk,
421 struct sk_buff *skb);
422
423extern struct sock * tcp_create_openreq_child(struct sock *sk,
424 struct request_sock *req,
425 struct sk_buff *skb);
426
427extern struct sock * tcp_v4_syn_recv_sock(struct sock *sk,
428 struct sk_buff *skb,
429 struct request_sock *req,
430 struct dst_entry *dst);
431
432extern int tcp_v4_do_rcv(struct sock *sk,
433 struct sk_buff *skb);
434
435extern int tcp_v4_connect(struct sock *sk,
436 struct sockaddr *uaddr,
437 int addr_len);
438
439extern int tcp_connect(struct sock *sk);
440
441extern struct sk_buff * tcp_make_synack(struct sock *sk,
442 struct dst_entry *dst,
443 struct request_sock *req,
444 struct request_values *rvp);
445
446extern int tcp_disconnect(struct sock *sk, int flags);
447
448
449/* From syncookies.c */
450extern __u32 syncookie_secret[2][16-4+SHA_DIGEST_WORDS];
451extern struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb,
452 struct ip_options *opt);
453extern __u32 cookie_v4_init_sequence(struct sock *sk, struct sk_buff *skb,
454 __u16 *mss);
455
456extern __u32 cookie_init_timestamp(struct request_sock *req);
457extern void cookie_check_timestamp(struct tcp_options_received *tcp_opt);
458
459/* From net/ipv6/syncookies.c */
460extern struct sock *cookie_v6_check(struct sock *sk, struct sk_buff *skb);
461extern __u32 cookie_v6_init_sequence(struct sock *sk, struct sk_buff *skb,
462 __u16 *mss);
463
464/* tcp_output.c */
465
466extern void __tcp_push_pending_frames(struct sock *sk, unsigned int cur_mss,
467 int nonagle);
468extern int tcp_may_send_now(struct sock *sk);
469extern int tcp_retransmit_skb(struct sock *, struct sk_buff *);
470extern void tcp_retransmit_timer(struct sock *sk);
471extern void tcp_xmit_retransmit_queue(struct sock *);
472extern void tcp_simple_retransmit(struct sock *);
473extern int tcp_trim_head(struct sock *, struct sk_buff *, u32);
474extern int tcp_fragment(struct sock *, struct sk_buff *, u32, unsigned int);
475
476extern void tcp_send_probe0(struct sock *);
477extern void tcp_send_partial(struct sock *);
478extern int tcp_write_wakeup(struct sock *);
479extern void tcp_send_fin(struct sock *sk);
480extern void tcp_send_active_reset(struct sock *sk, gfp_t priority);
481extern int tcp_send_synack(struct sock *);
482extern void tcp_push_one(struct sock *, unsigned int mss_now);
483extern void tcp_send_ack(struct sock *sk);
484extern void tcp_send_delayed_ack(struct sock *sk);
485
486/* tcp_input.c */
487extern void tcp_cwnd_application_limited(struct sock *sk);
488
489/* tcp_timer.c */
490extern void tcp_init_xmit_timers(struct sock *);
491static inline void tcp_clear_xmit_timers(struct sock *sk)
492{
493 inet_csk_clear_xmit_timers(sk);
494}
495
496extern unsigned int tcp_sync_mss(struct sock *sk, u32 pmtu);
497extern unsigned int tcp_current_mss(struct sock *sk);
498
499/* Bound MSS / TSO packet size with the half of the window */
500static inline int tcp_bound_to_half_wnd(struct tcp_sock *tp, int pktsize)
501{
502 if (tp->max_window && pktsize > (tp->max_window >> 1))
503 return max(tp->max_window >> 1, 68U - tp->tcp_header_len);
504 else
505 return pktsize;
506}
507
508/* tcp.c */
509extern void tcp_get_info(struct sock *, struct tcp_info *);
510
511/* Read 'sendfile()'-style from a TCP socket */
512typedef int (*sk_read_actor_t)(read_descriptor_t *, struct sk_buff *,
513 unsigned int, size_t);
514extern int tcp_read_sock(struct sock *sk, read_descriptor_t *desc,
515 sk_read_actor_t recv_actor);
516
517extern void tcp_initialize_rcv_mss(struct sock *sk);
518
519extern int tcp_mtu_to_mss(struct sock *sk, int pmtu);
520extern int tcp_mss_to_mtu(struct sock *sk, int mss);
521extern void tcp_mtup_init(struct sock *sk);
522
523static inline void tcp_bound_rto(const struct sock *sk)
524{
525 if (inet_csk(sk)->icsk_rto > TCP_RTO_MAX)
526 inet_csk(sk)->icsk_rto = TCP_RTO_MAX;
527}
528
529static inline u32 __tcp_set_rto(const struct tcp_sock *tp)
530{
531 return (tp->srtt >> 3) + tp->rttvar;
532}
533
534static inline void __tcp_fast_path_on(struct tcp_sock *tp, u32 snd_wnd)
535{
536 tp->pred_flags = htonl((tp->tcp_header_len << 26) |
537 ntohl(TCP_FLAG_ACK) |
538 snd_wnd);
539}
540
541static inline void tcp_fast_path_on(struct tcp_sock *tp)
542{
543 __tcp_fast_path_on(tp, tp->snd_wnd >> tp->rx_opt.snd_wscale);
544}
545
546static inline void tcp_fast_path_check(struct sock *sk)
547{
548 struct tcp_sock *tp = tcp_sk(sk);
549
550 if (skb_queue_empty(&tp->out_of_order_queue) &&
551 tp->rcv_wnd &&
552 atomic_read(&sk->sk_rmem_alloc) < sk->sk_rcvbuf &&
553 !tp->urg_data)
554 tcp_fast_path_on(tp);
555}
556
557/* Compute the actual rto_min value */
558static inline u32 tcp_rto_min(struct sock *sk)
559{
560 struct dst_entry *dst = __sk_dst_get(sk);
561 u32 rto_min = TCP_RTO_MIN;
562
563 if (dst && dst_metric_locked(dst, RTAX_RTO_MIN))
564 rto_min = dst_metric_rtt(dst, RTAX_RTO_MIN);
565 return rto_min;
566}
567
568/* Compute the actual receive window we are currently advertising.
569 * Rcv_nxt can be after the window if our peer push more data
570 * than the offered window.
571 */
572static inline u32 tcp_receive_window(const struct tcp_sock *tp)
573{
574 s32 win = tp->rcv_wup + tp->rcv_wnd - tp->rcv_nxt;
575
576 if (win < 0)
577 win = 0;
578 return (u32) win;
579}
580
581/* Choose a new window, without checks for shrinking, and without
582 * scaling applied to the result. The caller does these things
583 * if necessary. This is a "raw" window selection.
584 */
585extern u32 __tcp_select_window(struct sock *sk);
586
587/* TCP timestamps are only 32-bits, this causes a slight
588 * complication on 64-bit systems since we store a snapshot
589 * of jiffies in the buffer control blocks below. We decided
590 * to use only the low 32-bits of jiffies and hide the ugly
591 * casts with the following macro.
592 */
593#define tcp_time_stamp ((__u32)(jiffies))
594
595/* This is what the send packet queuing engine uses to pass
596 * TCP per-packet control information to the transmission
597 * code. We also store the host-order sequence numbers in
598 * here too. This is 36 bytes on 32-bit architectures,
599 * 40 bytes on 64-bit machines, if this grows please adjust
600 * skbuff.h:skbuff->cb[xxx] size appropriately.
601 */
602struct tcp_skb_cb {
603 union {
604 struct inet_skb_parm h4;
605#if defined(CONFIG_IPV6) || defined (CONFIG_IPV6_MODULE)
606 struct inet6_skb_parm h6;
607#endif
608 } header; /* For incoming frames */
609 __u32 seq; /* Starting sequence number */
610 __u32 end_seq; /* SEQ + FIN + SYN + datalen */
611 __u32 when; /* used to compute rtt's */
612 __u8 flags; /* TCP header flags. */
613
614 /* NOTE: These must match up to the flags byte in a
615 * real TCP header.
616 */
617#define TCPCB_FLAG_FIN 0x01
618#define TCPCB_FLAG_SYN 0x02
619#define TCPCB_FLAG_RST 0x04
620#define TCPCB_FLAG_PSH 0x08
621#define TCPCB_FLAG_ACK 0x10
622#define TCPCB_FLAG_URG 0x20
623#define TCPCB_FLAG_ECE 0x40
624#define TCPCB_FLAG_CWR 0x80
625
626 __u8 sacked; /* State flags for SACK/FACK. */
627#define TCPCB_SACKED_ACKED 0x01 /* SKB ACK'd by a SACK block */
628#define TCPCB_SACKED_RETRANS 0x02 /* SKB retransmitted */
629#define TCPCB_LOST 0x04 /* SKB is lost */
630#define TCPCB_TAGBITS 0x07 /* All tag bits */
631
632#define TCPCB_EVER_RETRANS 0x80 /* Ever retransmitted frame */
633#define TCPCB_RETRANS (TCPCB_SACKED_RETRANS|TCPCB_EVER_RETRANS)
634
635 __u32 ack_seq; /* Sequence number ACK'd */
636};
637
638#define TCP_SKB_CB(__skb) ((struct tcp_skb_cb *)&((__skb)->cb[0]))
639
640/* Due to TSO, an SKB can be composed of multiple actual
641 * packets. To keep these tracked properly, we use this.
642 */
643static inline int tcp_skb_pcount(const struct sk_buff *skb)
644{
645 return skb_shinfo(skb)->gso_segs;
646}
647
648/* This is valid iff tcp_skb_pcount() > 1. */
649static inline int tcp_skb_mss(const struct sk_buff *skb)
650{
651 return skb_shinfo(skb)->gso_size;
652}
653
654/* Events passed to congestion control interface */
655enum tcp_ca_event {
656 CA_EVENT_TX_START, /* first transmit when no packets in flight */
657 CA_EVENT_CWND_RESTART, /* congestion window restart */
658 CA_EVENT_COMPLETE_CWR, /* end of congestion recovery */
659 CA_EVENT_FRTO, /* fast recovery timeout */
660 CA_EVENT_LOSS, /* loss timeout */
661 CA_EVENT_FAST_ACK, /* in sequence ack */
662 CA_EVENT_SLOW_ACK, /* other ack */
663};
664
665/*
666 * Interface for adding new TCP congestion control handlers
667 */
668#define TCP_CA_NAME_MAX 16
669#define TCP_CA_MAX 128
670#define TCP_CA_BUF_MAX (TCP_CA_NAME_MAX*TCP_CA_MAX)
671
672#define TCP_CONG_NON_RESTRICTED 0x1
673#define TCP_CONG_RTT_STAMP 0x2
674
675struct tcp_congestion_ops {
676 struct list_head list;
677 unsigned long flags;
678
679 /* initialize private data (optional) */
680 void (*init)(struct sock *sk);
681 /* cleanup private data (optional) */
682 void (*release)(struct sock *sk);
683
684 /* return slow start threshold (required) */
685 u32 (*ssthresh)(struct sock *sk);
686 /* lower bound for congestion window (optional) */
687 u32 (*min_cwnd)(const struct sock *sk);
688 /* do new cwnd calculation (required) */
689 void (*cong_avoid)(struct sock *sk, u32 ack, u32 in_flight);
690 /* call before changing ca_state (optional) */
691 void (*set_state)(struct sock *sk, u8 new_state);
692 /* call when cwnd event occurs (optional) */
693 void (*cwnd_event)(struct sock *sk, enum tcp_ca_event ev);
694 /* new value of cwnd after loss (optional) */
695 u32 (*undo_cwnd)(struct sock *sk);
696 /* hook for packet ack accounting (optional) */
697 void (*pkts_acked)(struct sock *sk, u32 num_acked, s32 rtt_us);
698 /* get info for inet_diag (optional) */
699 void (*get_info)(struct sock *sk, u32 ext, struct sk_buff *skb);
700
701 char name[TCP_CA_NAME_MAX];
702 struct module *owner;
703};
704
705extern int tcp_register_congestion_control(struct tcp_congestion_ops *type);
706extern void tcp_unregister_congestion_control(struct tcp_congestion_ops *type);
707
708extern void tcp_init_congestion_control(struct sock *sk);
709extern void tcp_cleanup_congestion_control(struct sock *sk);
710extern int tcp_set_default_congestion_control(const char *name);
711extern void tcp_get_default_congestion_control(char *name);
712extern void tcp_get_available_congestion_control(char *buf, size_t len);
713extern void tcp_get_allowed_congestion_control(char *buf, size_t len);
714extern int tcp_set_allowed_congestion_control(char *allowed);
715extern int tcp_set_congestion_control(struct sock *sk, const char *name);
716extern void tcp_slow_start(struct tcp_sock *tp);
717extern void tcp_cong_avoid_ai(struct tcp_sock *tp, u32 w);
718
719extern struct tcp_congestion_ops tcp_init_congestion_ops;
720extern u32 tcp_reno_ssthresh(struct sock *sk);
721extern void tcp_reno_cong_avoid(struct sock *sk, u32 ack, u32 in_flight);
722extern u32 tcp_reno_min_cwnd(const struct sock *sk);
723extern struct tcp_congestion_ops tcp_reno;
724
725static inline void tcp_set_ca_state(struct sock *sk, const u8 ca_state)
726{
727 struct inet_connection_sock *icsk = inet_csk(sk);
728
729 if (icsk->icsk_ca_ops->set_state)
730 icsk->icsk_ca_ops->set_state(sk, ca_state);
731 icsk->icsk_ca_state = ca_state;
732}
733
734static inline void tcp_ca_event(struct sock *sk, const enum tcp_ca_event event)
735{
736 const struct inet_connection_sock *icsk = inet_csk(sk);
737
738 if (icsk->icsk_ca_ops->cwnd_event)
739 icsk->icsk_ca_ops->cwnd_event(sk, event);
740}
741
742/* These functions determine how the current flow behaves in respect of SACK
743 * handling. SACK is negotiated with the peer, and therefore it can vary
744 * between different flows.
745 *
746 * tcp_is_sack - SACK enabled
747 * tcp_is_reno - No SACK
748 * tcp_is_fack - FACK enabled, implies SACK enabled
749 */
750static inline int tcp_is_sack(const struct tcp_sock *tp)
751{
752 return tp->rx_opt.sack_ok;
753}
754
755static inline int tcp_is_reno(const struct tcp_sock *tp)
756{
757 return !tcp_is_sack(tp);
758}
759
760static inline int tcp_is_fack(const struct tcp_sock *tp)
761{
762 return tp->rx_opt.sack_ok & 2;
763}
764
765static inline void tcp_enable_fack(struct tcp_sock *tp)
766{
767 tp->rx_opt.sack_ok |= 2;
768}
769
770static inline unsigned int tcp_left_out(const struct tcp_sock *tp)
771{
772 return tp->sacked_out + tp->lost_out;
773}
774
775/* This determines how many packets are "in the network" to the best
776 * of our knowledge. In many cases it is conservative, but where
777 * detailed information is available from the receiver (via SACK
778 * blocks etc.) we can make more aggressive calculations.
779 *
780 * Use this for decisions involving congestion control, use just
781 * tp->packets_out to determine if the send queue is empty or not.
782 *
783 * Read this equation as:
784 *
785 * "Packets sent once on transmission queue" MINUS
786 * "Packets left network, but not honestly ACKed yet" PLUS
787 * "Packets fast retransmitted"
788 */
789static inline unsigned int tcp_packets_in_flight(const struct tcp_sock *tp)
790{
791 return tp->packets_out - tcp_left_out(tp) + tp->retrans_out;
792}
793
794#define TCP_INFINITE_SSTHRESH 0x7fffffff
795
796static inline bool tcp_in_initial_slowstart(const struct tcp_sock *tp)
797{
798 return tp->snd_ssthresh >= TCP_INFINITE_SSTHRESH;
799}
800
801/* If cwnd > ssthresh, we may raise ssthresh to be half-way to cwnd.
802 * The exception is rate halving phase, when cwnd is decreasing towards
803 * ssthresh.
804 */
805static inline __u32 tcp_current_ssthresh(const struct sock *sk)
806{
807 const struct tcp_sock *tp = tcp_sk(sk);
808 if ((1 << inet_csk(sk)->icsk_ca_state) & (TCPF_CA_CWR | TCPF_CA_Recovery))
809 return tp->snd_ssthresh;
810 else
811 return max(tp->snd_ssthresh,
812 ((tp->snd_cwnd >> 1) +
813 (tp->snd_cwnd >> 2)));
814}
815
816/* Use define here intentionally to get WARN_ON location shown at the caller */
817#define tcp_verify_left_out(tp) WARN_ON(tcp_left_out(tp) > tp->packets_out)
818
819extern void tcp_enter_cwr(struct sock *sk, const int set_ssthresh);
820extern __u32 tcp_init_cwnd(struct tcp_sock *tp, struct dst_entry *dst);
821
822/* Slow start with delack produces 3 packets of burst, so that
823 * it is safe "de facto". This will be the default - same as
824 * the default reordering threshold - but if reordering increases,
825 * we must be able to allow cwnd to burst at least this much in order
826 * to not pull it back when holes are filled.
827 */
828static __inline__ __u32 tcp_max_burst(const struct tcp_sock *tp)
829{
830 return tp->reordering;
831}
832
833/* Returns end sequence number of the receiver's advertised window */
834static inline u32 tcp_wnd_end(const struct tcp_sock *tp)
835{
836 return tp->snd_una + tp->snd_wnd;
837}
838extern int tcp_is_cwnd_limited(const struct sock *sk, u32 in_flight);
839
840static inline void tcp_minshall_update(struct tcp_sock *tp, unsigned int mss,
841 const struct sk_buff *skb)
842{
843 if (skb->len < mss)
844 tp->snd_sml = TCP_SKB_CB(skb)->end_seq;
845}
846
847static inline void tcp_check_probe_timer(struct sock *sk)
848{
849 struct tcp_sock *tp = tcp_sk(sk);
850 const struct inet_connection_sock *icsk = inet_csk(sk);
851
852 if (!tp->packets_out && !icsk->icsk_pending)
853 inet_csk_reset_xmit_timer(sk, ICSK_TIME_PROBE0,
854 icsk->icsk_rto, TCP_RTO_MAX);
855}
856
857static inline void tcp_push_pending_frames(struct sock *sk)
858{
859 struct tcp_sock *tp = tcp_sk(sk);
860
861 __tcp_push_pending_frames(sk, tcp_current_mss(sk), tp->nonagle);
862}
863
864static inline void tcp_init_wl(struct tcp_sock *tp, u32 seq)
865{
866 tp->snd_wl1 = seq;
867}
868
869static inline void tcp_update_wl(struct tcp_sock *tp, u32 seq)
870{
871 tp->snd_wl1 = seq;
872}
873
874/*
875 * Calculate(/check) TCP checksum
876 */
877static inline __sum16 tcp_v4_check(int len, __be32 saddr,
878 __be32 daddr, __wsum base)
879{
880 return csum_tcpudp_magic(saddr,daddr,len,IPPROTO_TCP,base);
881}
882
883static inline __sum16 __tcp_checksum_complete(struct sk_buff *skb)
884{
885 return __skb_checksum_complete(skb);
886}
887
888static inline int tcp_checksum_complete(struct sk_buff *skb)
889{
890 return !skb_csum_unnecessary(skb) &&
891 __tcp_checksum_complete(skb);
892}
893
894/* Prequeue for VJ style copy to user, combined with checksumming. */
895
896static inline void tcp_prequeue_init(struct tcp_sock *tp)
897{
898 tp->ucopy.task = NULL;
899 tp->ucopy.len = 0;
900 tp->ucopy.memory = 0;
901 skb_queue_head_init(&tp->ucopy.prequeue);
902#ifdef CONFIG_NET_DMA
903 tp->ucopy.dma_chan = NULL;
904 tp->ucopy.wakeup = 0;
905 tp->ucopy.pinned_list = NULL;
906 tp->ucopy.dma_cookie = 0;
907#endif
908}
909
910/* Packet is added to VJ-style prequeue for processing in process
911 * context, if a reader task is waiting. Apparently, this exciting
912 * idea (VJ's mail "Re: query about TCP header on tcp-ip" of 07 Sep 93)
913 * failed somewhere. Latency? Burstiness? Well, at least now we will
914 * see, why it failed. 8)8) --ANK
915 *
916 * NOTE: is this not too big to inline?
917 */
918static inline int tcp_prequeue(struct sock *sk, struct sk_buff *skb)
919{
920 struct tcp_sock *tp = tcp_sk(sk);
921
922 if (sysctl_tcp_low_latency || !tp->ucopy.task)
923 return 0;
924
925 __skb_queue_tail(&tp->ucopy.prequeue, skb);
926 tp->ucopy.memory += skb->truesize;
927 if (tp->ucopy.memory > sk->sk_rcvbuf) {
928 struct sk_buff *skb1;
929
930 BUG_ON(sock_owned_by_user(sk));
931
932 while ((skb1 = __skb_dequeue(&tp->ucopy.prequeue)) != NULL) {
933 sk_backlog_rcv(sk, skb1);
934 NET_INC_STATS_BH(sock_net(sk),
935 LINUX_MIB_TCPPREQUEUEDROPPED);
936 }
937
938 tp->ucopy.memory = 0;
939 } else if (skb_queue_len(&tp->ucopy.prequeue) == 1) {
940 wake_up_interruptible_poll(sk->sk_sleep,
941 POLLIN | POLLRDNORM | POLLRDBAND);
942 if (!inet_csk_ack_scheduled(sk))
943 inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK,
944 (3 * tcp_rto_min(sk)) / 4,
945 TCP_RTO_MAX);
946 }
947 return 1;
948}
949
950
951#undef STATE_TRACE
952
953#ifdef STATE_TRACE
954static const char *statename[]={
955 "Unused","Established","Syn Sent","Syn Recv",
956 "Fin Wait 1","Fin Wait 2","Time Wait", "Close",
957 "Close Wait","Last ACK","Listen","Closing"
958};
959#endif
960extern void tcp_set_state(struct sock *sk, int state);
961
962extern void tcp_done(struct sock *sk);
963
964static inline void tcp_sack_reset(struct tcp_options_received *rx_opt)
965{
966 rx_opt->dsack = 0;
967 rx_opt->num_sacks = 0;
968}
969
970/* Determine a window scaling and initial window to offer. */
971extern void tcp_select_initial_window(int __space, __u32 mss,
972 __u32 *rcv_wnd, __u32 *window_clamp,
973 int wscale_ok, __u8 *rcv_wscale);
974
975static inline int tcp_win_from_space(int space)
976{
977 return sysctl_tcp_adv_win_scale<=0 ?
978 (space>>(-sysctl_tcp_adv_win_scale)) :
979 space - (space>>sysctl_tcp_adv_win_scale);
980}
981
982/* Note: caller must be prepared to deal with negative returns */
983static inline int tcp_space(const struct sock *sk)
984{
985 return tcp_win_from_space(sk->sk_rcvbuf -
986 atomic_read(&sk->sk_rmem_alloc));
987}
988
989static inline int tcp_full_space(const struct sock *sk)
990{
991 return tcp_win_from_space(sk->sk_rcvbuf);
992}
993
994static inline void tcp_openreq_init(struct request_sock *req,
995 struct tcp_options_received *rx_opt,
996 struct sk_buff *skb)
997{
998 struct inet_request_sock *ireq = inet_rsk(req);
999
1000 req->rcv_wnd = 0; /* So that tcp_send_synack() knows! */
1001 req->cookie_ts = 0;
1002 tcp_rsk(req)->rcv_isn = TCP_SKB_CB(skb)->seq;
1003 req->mss = rx_opt->mss_clamp;
1004 req->ts_recent = rx_opt->saw_tstamp ? rx_opt->rcv_tsval : 0;
1005 ireq->tstamp_ok = rx_opt->tstamp_ok;
1006 ireq->sack_ok = rx_opt->sack_ok;
1007 ireq->snd_wscale = rx_opt->snd_wscale;
1008 ireq->wscale_ok = rx_opt->wscale_ok;
1009 ireq->acked = 0;
1010 ireq->ecn_ok = 0;
1011 ireq->rmt_port = tcp_hdr(skb)->source;
1012 ireq->loc_port = tcp_hdr(skb)->dest;
1013}
1014
1015extern void tcp_enter_memory_pressure(struct sock *sk);
1016
1017static inline int keepalive_intvl_when(const struct tcp_sock *tp)
1018{
1019 return tp->keepalive_intvl ? : sysctl_tcp_keepalive_intvl;
1020}
1021
1022static inline int keepalive_time_when(const struct tcp_sock *tp)
1023{
1024 return tp->keepalive_time ? : sysctl_tcp_keepalive_time;
1025}
1026
1027static inline int keepalive_probes(const struct tcp_sock *tp)
1028{
1029 return tp->keepalive_probes ? : sysctl_tcp_keepalive_probes;
1030}
1031
1032static inline int tcp_fin_time(const struct sock *sk)
1033{
1034 int fin_timeout = tcp_sk(sk)->linger2 ? : sysctl_tcp_fin_timeout;
1035 const int rto = inet_csk(sk)->icsk_rto;
1036
1037 if (fin_timeout < (rto << 2) - (rto >> 1))
1038 fin_timeout = (rto << 2) - (rto >> 1);
1039
1040 return fin_timeout;
1041}
1042
1043static inline int tcp_paws_check(const struct tcp_options_received *rx_opt,
1044 int paws_win)
1045{
1046 if ((s32)(rx_opt->ts_recent - rx_opt->rcv_tsval) <= paws_win)
1047 return 1;
1048 if (unlikely(get_seconds() >= rx_opt->ts_recent_stamp + TCP_PAWS_24DAYS))
1049 return 1;
1050
1051 return 0;
1052}
1053
1054static inline int tcp_paws_reject(const struct tcp_options_received *rx_opt,
1055 int rst)
1056{
1057 if (tcp_paws_check(rx_opt, 0))
1058 return 0;
1059
1060 /* RST segments are not recommended to carry timestamp,
1061 and, if they do, it is recommended to ignore PAWS because
1062 "their cleanup function should take precedence over timestamps."
1063 Certainly, it is mistake. It is necessary to understand the reasons
1064 of this constraint to relax it: if peer reboots, clock may go
1065 out-of-sync and half-open connections will not be reset.
1066 Actually, the problem would be not existing if all
1067 the implementations followed draft about maintaining clock
1068 via reboots. Linux-2.2 DOES NOT!
1069
1070 However, we can relax time bounds for RST segments to MSL.
1071 */
1072 if (rst && get_seconds() >= rx_opt->ts_recent_stamp + TCP_PAWS_MSL)
1073 return 0;
1074 return 1;
1075}
1076
1077#define TCP_CHECK_TIMER(sk) do { } while (0)
1078
1079static inline void tcp_mib_init(struct net *net)
1080{
1081 /* See RFC 2012 */
1082 TCP_ADD_STATS_USER(net, TCP_MIB_RTOALGORITHM, 1);
1083 TCP_ADD_STATS_USER(net, TCP_MIB_RTOMIN, TCP_RTO_MIN*1000/HZ);
1084 TCP_ADD_STATS_USER(net, TCP_MIB_RTOMAX, TCP_RTO_MAX*1000/HZ);
1085 TCP_ADD_STATS_USER(net, TCP_MIB_MAXCONN, -1);
1086}
1087
1088/* from STCP */
1089static inline void tcp_clear_retrans_hints_partial(struct tcp_sock *tp)
1090{
1091 tp->lost_skb_hint = NULL;
1092 tp->scoreboard_skb_hint = NULL;
1093}
1094
1095static inline void tcp_clear_all_retrans_hints(struct tcp_sock *tp)
1096{
1097 tcp_clear_retrans_hints_partial(tp);
1098 tp->retransmit_skb_hint = NULL;
1099}
1100
1101/* MD5 Signature */
1102struct crypto_hash;
1103
1104/* - key database */
1105struct tcp_md5sig_key {
1106 u8 *key;
1107 u8 keylen;
1108};
1109
1110struct tcp4_md5sig_key {
1111 struct tcp_md5sig_key base;
1112 __be32 addr;
1113};
1114
1115struct tcp6_md5sig_key {
1116 struct tcp_md5sig_key base;
1117#if 0
1118 u32 scope_id; /* XXX */
1119#endif
1120 struct in6_addr addr;
1121};
1122
1123/* - sock block */
1124struct tcp_md5sig_info {
1125 struct tcp4_md5sig_key *keys4;
1126#if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
1127 struct tcp6_md5sig_key *keys6;
1128 u32 entries6;
1129 u32 alloced6;
1130#endif
1131 u32 entries4;
1132 u32 alloced4;
1133};
1134
1135/* - pseudo header */
1136struct tcp4_pseudohdr {
1137 __be32 saddr;
1138 __be32 daddr;
1139 __u8 pad;
1140 __u8 protocol;
1141 __be16 len;
1142};
1143
1144struct tcp6_pseudohdr {
1145 struct in6_addr saddr;
1146 struct in6_addr daddr;
1147 __be32 len;
1148 __be32 protocol; /* including padding */
1149};
1150
1151union tcp_md5sum_block {
1152 struct tcp4_pseudohdr ip4;
1153#if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
1154 struct tcp6_pseudohdr ip6;
1155#endif
1156};
1157
1158/* - pool: digest algorithm, hash description and scratch buffer */
1159struct tcp_md5sig_pool {
1160 struct hash_desc md5_desc;
1161 union tcp_md5sum_block md5_blk;
1162};
1163
1164#define TCP_MD5SIG_MAXKEYS (~(u32)0) /* really?! */
1165
1166/* - functions */
1167extern int tcp_v4_md5_hash_skb(char *md5_hash,
1168 struct tcp_md5sig_key *key,
1169 struct sock *sk,
1170 struct request_sock *req,
1171 struct sk_buff *skb);
1172
1173extern struct tcp_md5sig_key *tcp_v4_md5_lookup(struct sock *sk,
1174 struct sock *addr_sk);
1175
1176extern int tcp_v4_md5_do_add(struct sock *sk,
1177 __be32 addr,
1178 u8 *newkey,
1179 u8 newkeylen);
1180
1181extern int tcp_v4_md5_do_del(struct sock *sk,
1182 __be32 addr);
1183
1184#ifdef CONFIG_TCP_MD5SIG
1185#define tcp_twsk_md5_key(twsk) ((twsk)->tw_md5_keylen ? \
1186 &(struct tcp_md5sig_key) { \
1187 .key = (twsk)->tw_md5_key, \
1188 .keylen = (twsk)->tw_md5_keylen, \
1189 } : NULL)
1190#else
1191#define tcp_twsk_md5_key(twsk) NULL
1192#endif
1193
1194extern struct tcp_md5sig_pool **tcp_alloc_md5sig_pool(struct sock *);
1195extern void tcp_free_md5sig_pool(void);
1196
1197extern struct tcp_md5sig_pool *__tcp_get_md5sig_pool(int cpu);
1198extern void __tcp_put_md5sig_pool(void);
1199extern int tcp_md5_hash_header(struct tcp_md5sig_pool *, struct tcphdr *);
1200extern int tcp_md5_hash_skb_data(struct tcp_md5sig_pool *, struct sk_buff *,
1201 unsigned header_len);
1202extern int tcp_md5_hash_key(struct tcp_md5sig_pool *hp,
1203 struct tcp_md5sig_key *key);
1204
1205static inline
1206struct tcp_md5sig_pool *tcp_get_md5sig_pool(void)
1207{
1208 int cpu = get_cpu();
1209 struct tcp_md5sig_pool *ret = __tcp_get_md5sig_pool(cpu);
1210 if (!ret)
1211 put_cpu();
1212 return ret;
1213}
1214
1215static inline void tcp_put_md5sig_pool(void)
1216{
1217 __tcp_put_md5sig_pool();
1218 put_cpu();
1219}
1220
1221/* write queue abstraction */
1222static inline void tcp_write_queue_purge(struct sock *sk)
1223{
1224 struct sk_buff *skb;
1225
1226 while ((skb = __skb_dequeue(&sk->sk_write_queue)) != NULL)
1227 sk_wmem_free_skb(sk, skb);
1228 sk_mem_reclaim(sk);
1229}
1230
1231static inline struct sk_buff *tcp_write_queue_head(struct sock *sk)
1232{
1233 return skb_peek(&sk->sk_write_queue);
1234}
1235
1236static inline struct sk_buff *tcp_write_queue_tail(struct sock *sk)
1237{
1238 return skb_peek_tail(&sk->sk_write_queue);
1239}
1240
1241static inline struct sk_buff *tcp_write_queue_next(struct sock *sk, struct sk_buff *skb)
1242{
1243 return skb_queue_next(&sk->sk_write_queue, skb);
1244}
1245
1246static inline struct sk_buff *tcp_write_queue_prev(struct sock *sk, struct sk_buff *skb)
1247{
1248 return skb_queue_prev(&sk->sk_write_queue, skb);
1249}
1250
1251#define tcp_for_write_queue(skb, sk) \
1252 skb_queue_walk(&(sk)->sk_write_queue, skb)
1253
1254#define tcp_for_write_queue_from(skb, sk) \
1255 skb_queue_walk_from(&(sk)->sk_write_queue, skb)
1256
1257#define tcp_for_write_queue_from_safe(skb, tmp, sk) \
1258 skb_queue_walk_from_safe(&(sk)->sk_write_queue, skb, tmp)
1259
1260/* This function calculates a "timeout" which is equivalent to the timeout of a
1261 * TCP connection after "boundary" unsucessful, exponentially backed-off
1262 * retransmissions with an initial RTO of TCP_RTO_MIN.
1263 */
1264static inline bool retransmits_timed_out(const struct sock *sk,
1265 unsigned int boundary)
1266{
1267 unsigned int timeout, linear_backoff_thresh;
1268
1269 if (!inet_csk(sk)->icsk_retransmits)
1270 return false;
1271
1272 linear_backoff_thresh = ilog2(TCP_RTO_MAX/TCP_RTO_MIN);
1273
1274 if (boundary <= linear_backoff_thresh)
1275 timeout = ((2 << boundary) - 1) * TCP_RTO_MIN;
1276 else
1277 timeout = ((2 << linear_backoff_thresh) - 1) * TCP_RTO_MIN +
1278 (boundary - linear_backoff_thresh) * TCP_RTO_MAX;
1279
1280 return (tcp_time_stamp - tcp_sk(sk)->retrans_stamp) >= timeout;
1281}
1282
1283static inline struct sk_buff *tcp_send_head(struct sock *sk)
1284{
1285 return sk->sk_send_head;
1286}
1287
1288static inline bool tcp_skb_is_last(const struct sock *sk,
1289 const struct sk_buff *skb)
1290{
1291 return skb_queue_is_last(&sk->sk_write_queue, skb);
1292}
1293
1294static inline void tcp_advance_send_head(struct sock *sk, struct sk_buff *skb)
1295{
1296 if (tcp_skb_is_last(sk, skb))
1297 sk->sk_send_head = NULL;
1298 else
1299 sk->sk_send_head = tcp_write_queue_next(sk, skb);
1300}
1301
1302static inline void tcp_check_send_head(struct sock *sk, struct sk_buff *skb_unlinked)
1303{
1304 if (sk->sk_send_head == skb_unlinked)
1305 sk->sk_send_head = NULL;
1306}
1307
1308static inline void tcp_init_send_head(struct sock *sk)
1309{
1310 sk->sk_send_head = NULL;
1311}
1312
1313static inline void __tcp_add_write_queue_tail(struct sock *sk, struct sk_buff *skb)
1314{
1315 __skb_queue_tail(&sk->sk_write_queue, skb);
1316}
1317
1318static inline void tcp_add_write_queue_tail(struct sock *sk, struct sk_buff *skb)
1319{
1320 __tcp_add_write_queue_tail(sk, skb);
1321
1322 /* Queue it, remembering where we must start sending. */
1323 if (sk->sk_send_head == NULL) {
1324 sk->sk_send_head = skb;
1325
1326 if (tcp_sk(sk)->highest_sack == NULL)
1327 tcp_sk(sk)->highest_sack = skb;
1328 }
1329}
1330
1331static inline void __tcp_add_write_queue_head(struct sock *sk, struct sk_buff *skb)
1332{
1333 __skb_queue_head(&sk->sk_write_queue, skb);
1334}
1335
1336/* Insert buff after skb on the write queue of sk. */
1337static inline void tcp_insert_write_queue_after(struct sk_buff *skb,
1338 struct sk_buff *buff,
1339 struct sock *sk)
1340{
1341 __skb_queue_after(&sk->sk_write_queue, skb, buff);
1342}
1343
1344/* Insert new before skb on the write queue of sk. */
1345static inline void tcp_insert_write_queue_before(struct sk_buff *new,
1346 struct sk_buff *skb,
1347 struct sock *sk)
1348{
1349 __skb_queue_before(&sk->sk_write_queue, skb, new);
1350
1351 if (sk->sk_send_head == skb)
1352 sk->sk_send_head = new;
1353}
1354
1355static inline void tcp_unlink_write_queue(struct sk_buff *skb, struct sock *sk)
1356{
1357 __skb_unlink(skb, &sk->sk_write_queue);
1358}
1359
1360static inline int tcp_write_queue_empty(struct sock *sk)
1361{
1362 return skb_queue_empty(&sk->sk_write_queue);
1363}
1364
1365/* Start sequence of the highest skb with SACKed bit, valid only if
1366 * sacked > 0 or when the caller has ensured validity by itself.
1367 */
1368static inline u32 tcp_highest_sack_seq(struct tcp_sock *tp)
1369{
1370 if (!tp->sacked_out)
1371 return tp->snd_una;
1372
1373 if (tp->highest_sack == NULL)
1374 return tp->snd_nxt;
1375
1376 return TCP_SKB_CB(tp->highest_sack)->seq;
1377}
1378
1379static inline void tcp_advance_highest_sack(struct sock *sk, struct sk_buff *skb)
1380{
1381 tcp_sk(sk)->highest_sack = tcp_skb_is_last(sk, skb) ? NULL :
1382 tcp_write_queue_next(sk, skb);
1383}
1384
1385static inline struct sk_buff *tcp_highest_sack(struct sock *sk)
1386{
1387 return tcp_sk(sk)->highest_sack;
1388}
1389
1390static inline void tcp_highest_sack_reset(struct sock *sk)
1391{
1392 tcp_sk(sk)->highest_sack = tcp_write_queue_head(sk);
1393}
1394
1395/* Called when old skb is about to be deleted (to be combined with new skb) */
1396static inline void tcp_highest_sack_combine(struct sock *sk,
1397 struct sk_buff *old,
1398 struct sk_buff *new)
1399{
1400 if (tcp_sk(sk)->sacked_out && (old == tcp_sk(sk)->highest_sack))
1401 tcp_sk(sk)->highest_sack = new;
1402}
1403
1404/* /proc */
1405enum tcp_seq_states {
1406 TCP_SEQ_STATE_LISTENING,
1407 TCP_SEQ_STATE_OPENREQ,
1408 TCP_SEQ_STATE_ESTABLISHED,
1409 TCP_SEQ_STATE_TIME_WAIT,
1410};
1411
1412struct tcp_seq_afinfo {
1413 char *name;
1414 sa_family_t family;
1415 struct file_operations seq_fops;
1416 struct seq_operations seq_ops;
1417};
1418
1419struct tcp_iter_state {
1420 struct seq_net_private p;
1421 sa_family_t family;
1422 enum tcp_seq_states state;
1423 struct sock *syn_wait_sk;
1424 int bucket, sbucket, num, uid;
1425};
1426
1427extern int tcp_proc_register(struct net *net, struct tcp_seq_afinfo *afinfo);
1428extern void tcp_proc_unregister(struct net *net, struct tcp_seq_afinfo *afinfo);
1429
1430extern struct request_sock_ops tcp_request_sock_ops;
1431extern struct request_sock_ops tcp6_request_sock_ops;
1432
1433extern void tcp_v4_destroy_sock(struct sock *sk);
1434
1435extern int tcp_v4_gso_send_check(struct sk_buff *skb);
1436extern struct sk_buff *tcp_tso_segment(struct sk_buff *skb, int features);
1437extern struct sk_buff **tcp_gro_receive(struct sk_buff **head,
1438 struct sk_buff *skb);
1439extern struct sk_buff **tcp4_gro_receive(struct sk_buff **head,
1440 struct sk_buff *skb);
1441extern int tcp_gro_complete(struct sk_buff *skb);
1442extern int tcp4_gro_complete(struct sk_buff *skb);
1443
1444#ifdef CONFIG_PROC_FS
1445extern int tcp4_proc_init(void);
1446extern void tcp4_proc_exit(void);
1447#endif
1448
1449/* TCP af-specific functions */
1450struct tcp_sock_af_ops {
1451#ifdef CONFIG_TCP_MD5SIG
1452 struct tcp_md5sig_key *(*md5_lookup) (struct sock *sk,
1453 struct sock *addr_sk);
1454 int (*calc_md5_hash) (char *location,
1455 struct tcp_md5sig_key *md5,
1456 struct sock *sk,
1457 struct request_sock *req,
1458 struct sk_buff *skb);
1459 int (*md5_add) (struct sock *sk,
1460 struct sock *addr_sk,
1461 u8 *newkey,
1462 u8 len);
1463 int (*md5_parse) (struct sock *sk,
1464 char __user *optval,
1465 int optlen);
1466#endif
1467};
1468
1469struct tcp_request_sock_ops {
1470#ifdef CONFIG_TCP_MD5SIG
1471 struct tcp_md5sig_key *(*md5_lookup) (struct sock *sk,
1472 struct request_sock *req);
1473 int (*calc_md5_hash) (char *location,
1474 struct tcp_md5sig_key *md5,
1475 struct sock *sk,
1476 struct request_sock *req,
1477 struct sk_buff *skb);
1478#endif
1479};
1480
1481/* Using SHA1 for now, define some constants.
1482 */
1483#define COOKIE_DIGEST_WORDS (SHA_DIGEST_WORDS)
1484#define COOKIE_MESSAGE_WORDS (SHA_MESSAGE_BYTES / 4)
1485#define COOKIE_WORKSPACE_WORDS (COOKIE_DIGEST_WORDS + COOKIE_MESSAGE_WORDS)
1486
1487extern int tcp_cookie_generator(u32 *bakery);
1488
1489extern void tcp_v4_init(void);
1490extern void tcp_init(void);
1491
1492#endif /* _TCP_H */
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