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