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Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/j.anaszewski...
[linux-2.6-block.git] / include / net / tcp.h
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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 FASTRETRANS_DEBUG 1
22
23#include <linux/list.h>
24#include <linux/tcp.h>
25#include <linux/bug.h>
26#include <linux/slab.h>
27#include <linux/cache.h>
28#include <linux/percpu.h>
29#include <linux/skbuff.h>
30#include <linux/cryptohash.h>
31#include <linux/kref.h>
32#include <linux/ktime.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#include <linux/memcontrol.h>
48
49extern struct inet_hashinfo tcp_hashinfo;
50
51extern struct percpu_counter tcp_orphan_count;
52void 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/* Minimal accepted MSS. It is (60+60+8) - (20+20). */
64#define TCP_MIN_MSS 88U
65
66/* The least MTU to use for probing */
67#define TCP_BASE_MSS 1024
68
69/* probing interval, default to 10 minutes as per RFC4821 */
70#define TCP_PROBE_INTERVAL 600
71
72/* Specify interval when tcp mtu probing will stop */
73#define TCP_PROBE_THRESHOLD 8
74
75/* After receiving this amount of duplicate ACKs fast retransmit starts. */
76#define TCP_FASTRETRANS_THRESH 3
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 6 /* This is how many retries are done
101 * when active opening a connection.
102 * RFC1122 says the minimum retry MUST
103 * be at least 180secs. Nevertheless
104 * this value is corresponding to
105 * 63secs of retransmission with the
106 * current initial RTO.
107 */
108
109#define TCP_SYNACK_RETRIES 5 /* This is how may retries are done
110 * when passive opening a connection.
111 * This is corresponding to 31secs of
112 * retransmission with the current
113 * initial RTO.
114 */
115
116#define TCP_TIMEWAIT_LEN (60*HZ) /* how long to wait to destroy TIME-WAIT
117 * state, about 60 seconds */
118#define TCP_FIN_TIMEOUT TCP_TIMEWAIT_LEN
119 /* BSD style FIN_WAIT2 deadlock breaker.
120 * It used to be 3min, new value is 60sec,
121 * to combine FIN-WAIT-2 timeout with
122 * TIME-WAIT timer.
123 */
124
125#define TCP_DELACK_MAX ((unsigned)(HZ/5)) /* maximal time to delay before sending an ACK */
126#if HZ >= 100
127#define TCP_DELACK_MIN ((unsigned)(HZ/25)) /* minimal time to delay before sending an ACK */
128#define TCP_ATO_MIN ((unsigned)(HZ/25))
129#else
130#define TCP_DELACK_MIN 4U
131#define TCP_ATO_MIN 4U
132#endif
133#define TCP_RTO_MAX ((unsigned)(120*HZ))
134#define TCP_RTO_MIN ((unsigned)(HZ/5))
135#define TCP_TIMEOUT_INIT ((unsigned)(1*HZ)) /* RFC6298 2.1 initial RTO value */
136#define TCP_TIMEOUT_FALLBACK ((unsigned)(3*HZ)) /* RFC 1122 initial RTO value, now
137 * used as a fallback RTO for the
138 * initial data transmission if no
139 * valid RTT sample has been acquired,
140 * most likely due to retrans in 3WHS.
141 */
142
143#define TCP_RESOURCE_PROBE_INTERVAL ((unsigned)(HZ/2U)) /* Maximal interval between probes
144 * for local resources.
145 */
146
147#define TCP_KEEPALIVE_TIME (120*60*HZ) /* two hours */
148#define TCP_KEEPALIVE_PROBES 9 /* Max of 9 keepalive probes */
149#define TCP_KEEPALIVE_INTVL (75*HZ)
150
151#define MAX_TCP_KEEPIDLE 32767
152#define MAX_TCP_KEEPINTVL 32767
153#define MAX_TCP_KEEPCNT 127
154#define MAX_TCP_SYNCNT 127
155
156#define TCP_SYNQ_INTERVAL (HZ/5) /* Period of SYNACK timer */
157
158#define TCP_PAWS_24DAYS (60 * 60 * 24 * 24)
159#define TCP_PAWS_MSL 60 /* Per-host timestamps are invalidated
160 * after this time. It should be equal
161 * (or greater than) TCP_TIMEWAIT_LEN
162 * to provide reliability equal to one
163 * provided by timewait state.
164 */
165#define TCP_PAWS_WINDOW 1 /* Replay window for per-host
166 * timestamps. It must be less than
167 * minimal timewait lifetime.
168 */
169/*
170 * TCP option
171 */
172
173#define TCPOPT_NOP 1 /* Padding */
174#define TCPOPT_EOL 0 /* End of options */
175#define TCPOPT_MSS 2 /* Segment size negotiating */
176#define TCPOPT_WINDOW 3 /* Window scaling */
177#define TCPOPT_SACK_PERM 4 /* SACK Permitted */
178#define TCPOPT_SACK 5 /* SACK Block */
179#define TCPOPT_TIMESTAMP 8 /* Better RTT estimations/PAWS */
180#define TCPOPT_MD5SIG 19 /* MD5 Signature (RFC2385) */
181#define TCPOPT_FASTOPEN 34 /* Fast open (RFC7413) */
182#define TCPOPT_EXP 254 /* Experimental */
183/* Magic number to be after the option value for sharing TCP
184 * experimental options. See draft-ietf-tcpm-experimental-options-00.txt
185 */
186#define TCPOPT_FASTOPEN_MAGIC 0xF989
187
188/*
189 * TCP option lengths
190 */
191
192#define TCPOLEN_MSS 4
193#define TCPOLEN_WINDOW 3
194#define TCPOLEN_SACK_PERM 2
195#define TCPOLEN_TIMESTAMP 10
196#define TCPOLEN_MD5SIG 18
197#define TCPOLEN_FASTOPEN_BASE 2
198#define TCPOLEN_EXP_FASTOPEN_BASE 4
199
200/* But this is what stacks really send out. */
201#define TCPOLEN_TSTAMP_ALIGNED 12
202#define TCPOLEN_WSCALE_ALIGNED 4
203#define TCPOLEN_SACKPERM_ALIGNED 4
204#define TCPOLEN_SACK_BASE 2
205#define TCPOLEN_SACK_BASE_ALIGNED 4
206#define TCPOLEN_SACK_PERBLOCK 8
207#define TCPOLEN_MD5SIG_ALIGNED 20
208#define TCPOLEN_MSS_ALIGNED 4
209
210/* Flags in tp->nonagle */
211#define TCP_NAGLE_OFF 1 /* Nagle's algo is disabled */
212#define TCP_NAGLE_CORK 2 /* Socket is corked */
213#define TCP_NAGLE_PUSH 4 /* Cork is overridden for already queued data */
214
215/* TCP thin-stream limits */
216#define TCP_THIN_LINEAR_RETRIES 6 /* After 6 linear retries, do exp. backoff */
217
218/* TCP initial congestion window as per rfc6928 */
219#define TCP_INIT_CWND 10
220
221/* Bit Flags for sysctl_tcp_fastopen */
222#define TFO_CLIENT_ENABLE 1
223#define TFO_SERVER_ENABLE 2
224#define TFO_CLIENT_NO_COOKIE 4 /* Data in SYN w/o cookie option */
225
226/* Accept SYN data w/o any cookie option */
227#define TFO_SERVER_COOKIE_NOT_REQD 0x200
228
229/* Force enable TFO on all listeners, i.e., not requiring the
230 * TCP_FASTOPEN socket option. SOCKOPT1/2 determine how to set max_qlen.
231 */
232#define TFO_SERVER_WO_SOCKOPT1 0x400
233#define TFO_SERVER_WO_SOCKOPT2 0x800
234
235extern struct inet_timewait_death_row tcp_death_row;
236
237/* sysctl variables for tcp */
238extern int sysctl_tcp_timestamps;
239extern int sysctl_tcp_window_scaling;
240extern int sysctl_tcp_sack;
241extern int sysctl_tcp_fastopen;
242extern int sysctl_tcp_retrans_collapse;
243extern int sysctl_tcp_stdurg;
244extern int sysctl_tcp_rfc1337;
245extern int sysctl_tcp_abort_on_overflow;
246extern int sysctl_tcp_max_orphans;
247extern int sysctl_tcp_fack;
248extern int sysctl_tcp_reordering;
249extern int sysctl_tcp_max_reordering;
250extern int sysctl_tcp_dsack;
251extern long sysctl_tcp_mem[3];
252extern int sysctl_tcp_wmem[3];
253extern int sysctl_tcp_rmem[3];
254extern int sysctl_tcp_app_win;
255extern int sysctl_tcp_adv_win_scale;
256extern int sysctl_tcp_tw_reuse;
257extern int sysctl_tcp_frto;
258extern int sysctl_tcp_low_latency;
259extern int sysctl_tcp_nometrics_save;
260extern int sysctl_tcp_moderate_rcvbuf;
261extern int sysctl_tcp_tso_win_divisor;
262extern int sysctl_tcp_workaround_signed_windows;
263extern int sysctl_tcp_slow_start_after_idle;
264extern int sysctl_tcp_thin_linear_timeouts;
265extern int sysctl_tcp_thin_dupack;
266extern int sysctl_tcp_early_retrans;
267extern int sysctl_tcp_limit_output_bytes;
268extern int sysctl_tcp_challenge_ack_limit;
269extern int sysctl_tcp_min_tso_segs;
270extern int sysctl_tcp_min_rtt_wlen;
271extern int sysctl_tcp_autocorking;
272extern int sysctl_tcp_invalid_ratelimit;
273extern int sysctl_tcp_pacing_ss_ratio;
274extern int sysctl_tcp_pacing_ca_ratio;
275
276extern atomic_long_t tcp_memory_allocated;
277extern struct percpu_counter tcp_sockets_allocated;
278extern int tcp_memory_pressure;
279
280/* optimized version of sk_under_memory_pressure() for TCP sockets */
281static inline bool tcp_under_memory_pressure(const struct sock *sk)
282{
283 if (mem_cgroup_sockets_enabled && sk->sk_memcg &&
284 mem_cgroup_under_socket_pressure(sk->sk_memcg))
285 return true;
286
287 return tcp_memory_pressure;
288}
289/*
290 * The next routines deal with comparing 32 bit unsigned ints
291 * and worry about wraparound (automatic with unsigned arithmetic).
292 */
293
294static inline bool before(__u32 seq1, __u32 seq2)
295{
296 return (__s32)(seq1-seq2) < 0;
297}
298#define after(seq2, seq1) before(seq1, seq2)
299
300/* is s2<=s1<=s3 ? */
301static inline bool between(__u32 seq1, __u32 seq2, __u32 seq3)
302{
303 return seq3 - seq2 >= seq1 - seq2;
304}
305
306static inline bool tcp_out_of_memory(struct sock *sk)
307{
308 if (sk->sk_wmem_queued > SOCK_MIN_SNDBUF &&
309 sk_memory_allocated(sk) > sk_prot_mem_limits(sk, 2))
310 return true;
311 return false;
312}
313
314void sk_forced_mem_schedule(struct sock *sk, int size);
315
316static inline bool tcp_too_many_orphans(struct sock *sk, int shift)
317{
318 struct percpu_counter *ocp = sk->sk_prot->orphan_count;
319 int orphans = percpu_counter_read_positive(ocp);
320
321 if (orphans << shift > sysctl_tcp_max_orphans) {
322 orphans = percpu_counter_sum_positive(ocp);
323 if (orphans << shift > sysctl_tcp_max_orphans)
324 return true;
325 }
326 return false;
327}
328
329bool tcp_check_oom(struct sock *sk, int shift);
330
331
332extern struct proto tcp_prot;
333
334#define TCP_INC_STATS(net, field) SNMP_INC_STATS((net)->mib.tcp_statistics, field)
335#define TCP_INC_STATS_BH(net, field) SNMP_INC_STATS_BH((net)->mib.tcp_statistics, field)
336#define TCP_DEC_STATS(net, field) SNMP_DEC_STATS((net)->mib.tcp_statistics, field)
337#define TCP_ADD_STATS_USER(net, field, val) SNMP_ADD_STATS_USER((net)->mib.tcp_statistics, field, val)
338#define TCP_ADD_STATS(net, field, val) SNMP_ADD_STATS((net)->mib.tcp_statistics, field, val)
339
340void tcp_tasklet_init(void);
341
342void tcp_v4_err(struct sk_buff *skb, u32);
343
344void tcp_shutdown(struct sock *sk, int how);
345
346void tcp_v4_early_demux(struct sk_buff *skb);
347int tcp_v4_rcv(struct sk_buff *skb);
348
349int tcp_v4_tw_remember_stamp(struct inet_timewait_sock *tw);
350int tcp_sendmsg(struct sock *sk, struct msghdr *msg, size_t size);
351int tcp_sendpage(struct sock *sk, struct page *page, int offset, size_t size,
352 int flags);
353void tcp_release_cb(struct sock *sk);
354void tcp_wfree(struct sk_buff *skb);
355void tcp_write_timer_handler(struct sock *sk);
356void tcp_delack_timer_handler(struct sock *sk);
357int tcp_ioctl(struct sock *sk, int cmd, unsigned long arg);
358int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb);
359void tcp_rcv_established(struct sock *sk, struct sk_buff *skb,
360 const struct tcphdr *th, unsigned int len);
361void tcp_rcv_space_adjust(struct sock *sk);
362int tcp_twsk_unique(struct sock *sk, struct sock *sktw, void *twp);
363void tcp_twsk_destructor(struct sock *sk);
364ssize_t tcp_splice_read(struct socket *sk, loff_t *ppos,
365 struct pipe_inode_info *pipe, size_t len,
366 unsigned int flags);
367
368static inline void tcp_dec_quickack_mode(struct sock *sk,
369 const unsigned int pkts)
370{
371 struct inet_connection_sock *icsk = inet_csk(sk);
372
373 if (icsk->icsk_ack.quick) {
374 if (pkts >= icsk->icsk_ack.quick) {
375 icsk->icsk_ack.quick = 0;
376 /* Leaving quickack mode we deflate ATO. */
377 icsk->icsk_ack.ato = TCP_ATO_MIN;
378 } else
379 icsk->icsk_ack.quick -= pkts;
380 }
381}
382
383#define TCP_ECN_OK 1
384#define TCP_ECN_QUEUE_CWR 2
385#define TCP_ECN_DEMAND_CWR 4
386#define TCP_ECN_SEEN 8
387
388enum tcp_tw_status {
389 TCP_TW_SUCCESS = 0,
390 TCP_TW_RST = 1,
391 TCP_TW_ACK = 2,
392 TCP_TW_SYN = 3
393};
394
395
396enum tcp_tw_status tcp_timewait_state_process(struct inet_timewait_sock *tw,
397 struct sk_buff *skb,
398 const struct tcphdr *th);
399struct sock *tcp_check_req(struct sock *sk, struct sk_buff *skb,
400 struct request_sock *req, bool fastopen);
401int tcp_child_process(struct sock *parent, struct sock *child,
402 struct sk_buff *skb);
403void tcp_enter_loss(struct sock *sk);
404void tcp_clear_retrans(struct tcp_sock *tp);
405void tcp_update_metrics(struct sock *sk);
406void tcp_init_metrics(struct sock *sk);
407void tcp_metrics_init(void);
408bool tcp_peer_is_proven(struct request_sock *req, struct dst_entry *dst,
409 bool paws_check, bool timestamps);
410bool tcp_remember_stamp(struct sock *sk);
411bool tcp_tw_remember_stamp(struct inet_timewait_sock *tw);
412void tcp_fetch_timewait_stamp(struct sock *sk, struct dst_entry *dst);
413void tcp_disable_fack(struct tcp_sock *tp);
414void tcp_close(struct sock *sk, long timeout);
415void tcp_init_sock(struct sock *sk);
416unsigned int tcp_poll(struct file *file, struct socket *sock,
417 struct poll_table_struct *wait);
418int tcp_getsockopt(struct sock *sk, int level, int optname,
419 char __user *optval, int __user *optlen);
420int tcp_setsockopt(struct sock *sk, int level, int optname,
421 char __user *optval, unsigned int optlen);
422int compat_tcp_getsockopt(struct sock *sk, int level, int optname,
423 char __user *optval, int __user *optlen);
424int compat_tcp_setsockopt(struct sock *sk, int level, int optname,
425 char __user *optval, unsigned int optlen);
426void tcp_set_keepalive(struct sock *sk, int val);
427void tcp_syn_ack_timeout(const struct request_sock *req);
428int tcp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, int nonblock,
429 int flags, int *addr_len);
430void tcp_parse_options(const struct sk_buff *skb,
431 struct tcp_options_received *opt_rx,
432 int estab, struct tcp_fastopen_cookie *foc);
433const u8 *tcp_parse_md5sig_option(const struct tcphdr *th);
434
435/*
436 * TCP v4 functions exported for the inet6 API
437 */
438
439void tcp_v4_send_check(struct sock *sk, struct sk_buff *skb);
440void tcp_v4_mtu_reduced(struct sock *sk);
441void tcp_req_err(struct sock *sk, u32 seq, bool abort);
442int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb);
443struct sock *tcp_create_openreq_child(const struct sock *sk,
444 struct request_sock *req,
445 struct sk_buff *skb);
446void tcp_ca_openreq_child(struct sock *sk, const struct dst_entry *dst);
447struct sock *tcp_v4_syn_recv_sock(const struct sock *sk, struct sk_buff *skb,
448 struct request_sock *req,
449 struct dst_entry *dst,
450 struct request_sock *req_unhash,
451 bool *own_req);
452int tcp_v4_do_rcv(struct sock *sk, struct sk_buff *skb);
453int tcp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len);
454int tcp_connect(struct sock *sk);
455struct sk_buff *tcp_make_synack(const struct sock *sk, struct dst_entry *dst,
456 struct request_sock *req,
457 struct tcp_fastopen_cookie *foc,
458 bool attach_req);
459int tcp_disconnect(struct sock *sk, int flags);
460
461void tcp_finish_connect(struct sock *sk, struct sk_buff *skb);
462int tcp_send_rcvq(struct sock *sk, struct msghdr *msg, size_t size);
463void inet_sk_rx_dst_set(struct sock *sk, const struct sk_buff *skb);
464
465/* From syncookies.c */
466struct sock *tcp_get_cookie_sock(struct sock *sk, struct sk_buff *skb,
467 struct request_sock *req,
468 struct dst_entry *dst);
469int __cookie_v4_check(const struct iphdr *iph, const struct tcphdr *th,
470 u32 cookie);
471struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb);
472#ifdef CONFIG_SYN_COOKIES
473
474/* Syncookies use a monotonic timer which increments every 60 seconds.
475 * This counter is used both as a hash input and partially encoded into
476 * the cookie value. A cookie is only validated further if the delta
477 * between the current counter value and the encoded one is less than this,
478 * i.e. a sent cookie is valid only at most for 2*60 seconds (or less if
479 * the counter advances immediately after a cookie is generated).
480 */
481#define MAX_SYNCOOKIE_AGE 2
482#define TCP_SYNCOOKIE_PERIOD (60 * HZ)
483#define TCP_SYNCOOKIE_VALID (MAX_SYNCOOKIE_AGE * TCP_SYNCOOKIE_PERIOD)
484
485/* syncookies: remember time of last synqueue overflow
486 * But do not dirty this field too often (once per second is enough)
487 * It is racy as we do not hold a lock, but race is very minor.
488 */
489static inline void tcp_synq_overflow(const struct sock *sk)
490{
491 unsigned long last_overflow = tcp_sk(sk)->rx_opt.ts_recent_stamp;
492 unsigned long now = jiffies;
493
494 if (time_after(now, last_overflow + HZ))
495 tcp_sk(sk)->rx_opt.ts_recent_stamp = now;
496}
497
498/* syncookies: no recent synqueue overflow on this listening socket? */
499static inline bool tcp_synq_no_recent_overflow(const struct sock *sk)
500{
501 unsigned long last_overflow = tcp_sk(sk)->rx_opt.ts_recent_stamp;
502
503 return time_after(jiffies, last_overflow + TCP_SYNCOOKIE_VALID);
504}
505
506static inline u32 tcp_cookie_time(void)
507{
508 u64 val = get_jiffies_64();
509
510 do_div(val, TCP_SYNCOOKIE_PERIOD);
511 return val;
512}
513
514u32 __cookie_v4_init_sequence(const struct iphdr *iph, const struct tcphdr *th,
515 u16 *mssp);
516__u32 cookie_v4_init_sequence(const struct sk_buff *skb, __u16 *mss);
517__u32 cookie_init_timestamp(struct request_sock *req);
518bool cookie_timestamp_decode(struct tcp_options_received *opt);
519bool cookie_ecn_ok(const struct tcp_options_received *opt,
520 const struct net *net, const struct dst_entry *dst);
521
522/* From net/ipv6/syncookies.c */
523int __cookie_v6_check(const struct ipv6hdr *iph, const struct tcphdr *th,
524 u32 cookie);
525struct sock *cookie_v6_check(struct sock *sk, struct sk_buff *skb);
526
527u32 __cookie_v6_init_sequence(const struct ipv6hdr *iph,
528 const struct tcphdr *th, u16 *mssp);
529__u32 cookie_v6_init_sequence(const struct sk_buff *skb, __u16 *mss);
530#endif
531/* tcp_output.c */
532
533void __tcp_push_pending_frames(struct sock *sk, unsigned int cur_mss,
534 int nonagle);
535bool tcp_may_send_now(struct sock *sk);
536int __tcp_retransmit_skb(struct sock *, struct sk_buff *);
537int tcp_retransmit_skb(struct sock *, struct sk_buff *);
538void tcp_retransmit_timer(struct sock *sk);
539void tcp_xmit_retransmit_queue(struct sock *);
540void tcp_simple_retransmit(struct sock *);
541int tcp_trim_head(struct sock *, struct sk_buff *, u32);
542int tcp_fragment(struct sock *, struct sk_buff *, u32, unsigned int, gfp_t);
543
544void tcp_send_probe0(struct sock *);
545void tcp_send_partial(struct sock *);
546int tcp_write_wakeup(struct sock *, int mib);
547void tcp_send_fin(struct sock *sk);
548void tcp_send_active_reset(struct sock *sk, gfp_t priority);
549int tcp_send_synack(struct sock *);
550void tcp_push_one(struct sock *, unsigned int mss_now);
551void tcp_send_ack(struct sock *sk);
552void tcp_send_delayed_ack(struct sock *sk);
553void tcp_send_loss_probe(struct sock *sk);
554bool tcp_schedule_loss_probe(struct sock *sk);
555void tcp_skb_collapse_tstamp(struct sk_buff *skb,
556 const struct sk_buff *next_skb);
557
558/* tcp_input.c */
559void tcp_resume_early_retransmit(struct sock *sk);
560void tcp_rearm_rto(struct sock *sk);
561void tcp_synack_rtt_meas(struct sock *sk, struct request_sock *req);
562void tcp_reset(struct sock *sk);
563void tcp_skb_mark_lost_uncond_verify(struct tcp_sock *tp, struct sk_buff *skb);
564void tcp_fin(struct sock *sk);
565
566/* tcp_timer.c */
567void tcp_init_xmit_timers(struct sock *);
568static inline void tcp_clear_xmit_timers(struct sock *sk)
569{
570 inet_csk_clear_xmit_timers(sk);
571}
572
573unsigned int tcp_sync_mss(struct sock *sk, u32 pmtu);
574unsigned int tcp_current_mss(struct sock *sk);
575
576/* Bound MSS / TSO packet size with the half of the window */
577static inline int tcp_bound_to_half_wnd(struct tcp_sock *tp, int pktsize)
578{
579 int cutoff;
580
581 /* When peer uses tiny windows, there is no use in packetizing
582 * to sub-MSS pieces for the sake of SWS or making sure there
583 * are enough packets in the pipe for fast recovery.
584 *
585 * On the other hand, for extremely large MSS devices, handling
586 * smaller than MSS windows in this way does make sense.
587 */
588 if (tp->max_window >= 512)
589 cutoff = (tp->max_window >> 1);
590 else
591 cutoff = tp->max_window;
592
593 if (cutoff && pktsize > cutoff)
594 return max_t(int, cutoff, 68U - tp->tcp_header_len);
595 else
596 return pktsize;
597}
598
599/* tcp.c */
600void tcp_get_info(struct sock *, struct tcp_info *);
601
602/* Read 'sendfile()'-style from a TCP socket */
603typedef int (*sk_read_actor_t)(read_descriptor_t *, struct sk_buff *,
604 unsigned int, size_t);
605int tcp_read_sock(struct sock *sk, read_descriptor_t *desc,
606 sk_read_actor_t recv_actor);
607
608void tcp_initialize_rcv_mss(struct sock *sk);
609
610int tcp_mtu_to_mss(struct sock *sk, int pmtu);
611int tcp_mss_to_mtu(struct sock *sk, int mss);
612void tcp_mtup_init(struct sock *sk);
613void tcp_init_buffer_space(struct sock *sk);
614
615static inline void tcp_bound_rto(const struct sock *sk)
616{
617 if (inet_csk(sk)->icsk_rto > TCP_RTO_MAX)
618 inet_csk(sk)->icsk_rto = TCP_RTO_MAX;
619}
620
621static inline u32 __tcp_set_rto(const struct tcp_sock *tp)
622{
623 return usecs_to_jiffies((tp->srtt_us >> 3) + tp->rttvar_us);
624}
625
626static inline void __tcp_fast_path_on(struct tcp_sock *tp, u32 snd_wnd)
627{
628 tp->pred_flags = htonl((tp->tcp_header_len << 26) |
629 ntohl(TCP_FLAG_ACK) |
630 snd_wnd);
631}
632
633static inline void tcp_fast_path_on(struct tcp_sock *tp)
634{
635 __tcp_fast_path_on(tp, tp->snd_wnd >> tp->rx_opt.snd_wscale);
636}
637
638static inline void tcp_fast_path_check(struct sock *sk)
639{
640 struct tcp_sock *tp = tcp_sk(sk);
641
642 if (skb_queue_empty(&tp->out_of_order_queue) &&
643 tp->rcv_wnd &&
644 atomic_read(&sk->sk_rmem_alloc) < sk->sk_rcvbuf &&
645 !tp->urg_data)
646 tcp_fast_path_on(tp);
647}
648
649/* Compute the actual rto_min value */
650static inline u32 tcp_rto_min(struct sock *sk)
651{
652 const struct dst_entry *dst = __sk_dst_get(sk);
653 u32 rto_min = TCP_RTO_MIN;
654
655 if (dst && dst_metric_locked(dst, RTAX_RTO_MIN))
656 rto_min = dst_metric_rtt(dst, RTAX_RTO_MIN);
657 return rto_min;
658}
659
660static inline u32 tcp_rto_min_us(struct sock *sk)
661{
662 return jiffies_to_usecs(tcp_rto_min(sk));
663}
664
665static inline bool tcp_ca_dst_locked(const struct dst_entry *dst)
666{
667 return dst_metric_locked(dst, RTAX_CC_ALGO);
668}
669
670/* Minimum RTT in usec. ~0 means not available. */
671static inline u32 tcp_min_rtt(const struct tcp_sock *tp)
672{
673 return tp->rtt_min[0].rtt;
674}
675
676/* Compute the actual receive window we are currently advertising.
677 * Rcv_nxt can be after the window if our peer push more data
678 * than the offered window.
679 */
680static inline u32 tcp_receive_window(const struct tcp_sock *tp)
681{
682 s32 win = tp->rcv_wup + tp->rcv_wnd - tp->rcv_nxt;
683
684 if (win < 0)
685 win = 0;
686 return (u32) win;
687}
688
689/* Choose a new window, without checks for shrinking, and without
690 * scaling applied to the result. The caller does these things
691 * if necessary. This is a "raw" window selection.
692 */
693u32 __tcp_select_window(struct sock *sk);
694
695void tcp_send_window_probe(struct sock *sk);
696
697/* TCP timestamps are only 32-bits, this causes a slight
698 * complication on 64-bit systems since we store a snapshot
699 * of jiffies in the buffer control blocks below. We decided
700 * to use only the low 32-bits of jiffies and hide the ugly
701 * casts with the following macro.
702 */
703#define tcp_time_stamp ((__u32)(jiffies))
704
705static inline u32 tcp_skb_timestamp(const struct sk_buff *skb)
706{
707 return skb->skb_mstamp.stamp_jiffies;
708}
709
710
711#define tcp_flag_byte(th) (((u_int8_t *)th)[13])
712
713#define TCPHDR_FIN 0x01
714#define TCPHDR_SYN 0x02
715#define TCPHDR_RST 0x04
716#define TCPHDR_PSH 0x08
717#define TCPHDR_ACK 0x10
718#define TCPHDR_URG 0x20
719#define TCPHDR_ECE 0x40
720#define TCPHDR_CWR 0x80
721
722#define TCPHDR_SYN_ECN (TCPHDR_SYN | TCPHDR_ECE | TCPHDR_CWR)
723
724/* This is what the send packet queuing engine uses to pass
725 * TCP per-packet control information to the transmission code.
726 * We also store the host-order sequence numbers in here too.
727 * This is 44 bytes if IPV6 is enabled.
728 * If this grows please adjust skbuff.h:skbuff->cb[xxx] size appropriately.
729 */
730struct tcp_skb_cb {
731 __u32 seq; /* Starting sequence number */
732 __u32 end_seq; /* SEQ + FIN + SYN + datalen */
733 union {
734 /* Note : tcp_tw_isn is used in input path only
735 * (isn chosen by tcp_timewait_state_process())
736 *
737 * tcp_gso_segs/size are used in write queue only,
738 * cf tcp_skb_pcount()/tcp_skb_mss()
739 */
740 __u32 tcp_tw_isn;
741 struct {
742 u16 tcp_gso_segs;
743 u16 tcp_gso_size;
744 };
745 };
746 __u8 tcp_flags; /* TCP header flags. (tcp[13]) */
747
748 __u8 sacked; /* State flags for SACK/FACK. */
749#define TCPCB_SACKED_ACKED 0x01 /* SKB ACK'd by a SACK block */
750#define TCPCB_SACKED_RETRANS 0x02 /* SKB retransmitted */
751#define TCPCB_LOST 0x04 /* SKB is lost */
752#define TCPCB_TAGBITS 0x07 /* All tag bits */
753#define TCPCB_REPAIRED 0x10 /* SKB repaired (no skb_mstamp) */
754#define TCPCB_EVER_RETRANS 0x80 /* Ever retransmitted frame */
755#define TCPCB_RETRANS (TCPCB_SACKED_RETRANS|TCPCB_EVER_RETRANS| \
756 TCPCB_REPAIRED)
757
758 __u8 ip_dsfield; /* IPv4 tos or IPv6 dsfield */
759 /* 1 byte hole */
760 __u32 ack_seq; /* Sequence number ACK'd */
761 union {
762 struct inet_skb_parm h4;
763#if IS_ENABLED(CONFIG_IPV6)
764 struct inet6_skb_parm h6;
765#endif
766 } header; /* For incoming frames */
767};
768
769#define TCP_SKB_CB(__skb) ((struct tcp_skb_cb *)&((__skb)->cb[0]))
770
771
772#if IS_ENABLED(CONFIG_IPV6)
773/* This is the variant of inet6_iif() that must be used by TCP,
774 * as TCP moves IP6CB into a different location in skb->cb[]
775 */
776static inline int tcp_v6_iif(const struct sk_buff *skb)
777{
778 return TCP_SKB_CB(skb)->header.h6.iif;
779}
780#endif
781
782/* Due to TSO, an SKB can be composed of multiple actual
783 * packets. To keep these tracked properly, we use this.
784 */
785static inline int tcp_skb_pcount(const struct sk_buff *skb)
786{
787 return TCP_SKB_CB(skb)->tcp_gso_segs;
788}
789
790static inline void tcp_skb_pcount_set(struct sk_buff *skb, int segs)
791{
792 TCP_SKB_CB(skb)->tcp_gso_segs = segs;
793}
794
795static inline void tcp_skb_pcount_add(struct sk_buff *skb, int segs)
796{
797 TCP_SKB_CB(skb)->tcp_gso_segs += segs;
798}
799
800/* This is valid iff skb is in write queue and tcp_skb_pcount() > 1. */
801static inline int tcp_skb_mss(const struct sk_buff *skb)
802{
803 return TCP_SKB_CB(skb)->tcp_gso_size;
804}
805
806/* Events passed to congestion control interface */
807enum tcp_ca_event {
808 CA_EVENT_TX_START, /* first transmit when no packets in flight */
809 CA_EVENT_CWND_RESTART, /* congestion window restart */
810 CA_EVENT_COMPLETE_CWR, /* end of congestion recovery */
811 CA_EVENT_LOSS, /* loss timeout */
812 CA_EVENT_ECN_NO_CE, /* ECT set, but not CE marked */
813 CA_EVENT_ECN_IS_CE, /* received CE marked IP packet */
814 CA_EVENT_DELAYED_ACK, /* Delayed ack is sent */
815 CA_EVENT_NON_DELAYED_ACK,
816};
817
818/* Information about inbound ACK, passed to cong_ops->in_ack_event() */
819enum tcp_ca_ack_event_flags {
820 CA_ACK_SLOWPATH = (1 << 0), /* In slow path processing */
821 CA_ACK_WIN_UPDATE = (1 << 1), /* ACK updated window */
822 CA_ACK_ECE = (1 << 2), /* ECE bit is set on ack */
823};
824
825/*
826 * Interface for adding new TCP congestion control handlers
827 */
828#define TCP_CA_NAME_MAX 16
829#define TCP_CA_MAX 128
830#define TCP_CA_BUF_MAX (TCP_CA_NAME_MAX*TCP_CA_MAX)
831
832#define TCP_CA_UNSPEC 0
833
834/* Algorithm can be set on socket without CAP_NET_ADMIN privileges */
835#define TCP_CONG_NON_RESTRICTED 0x1
836/* Requires ECN/ECT set on all packets */
837#define TCP_CONG_NEEDS_ECN 0x2
838
839union tcp_cc_info;
840
841struct tcp_congestion_ops {
842 struct list_head list;
843 u32 key;
844 u32 flags;
845
846 /* initialize private data (optional) */
847 void (*init)(struct sock *sk);
848 /* cleanup private data (optional) */
849 void (*release)(struct sock *sk);
850
851 /* return slow start threshold (required) */
852 u32 (*ssthresh)(struct sock *sk);
853 /* do new cwnd calculation (required) */
854 void (*cong_avoid)(struct sock *sk, u32 ack, u32 acked);
855 /* call before changing ca_state (optional) */
856 void (*set_state)(struct sock *sk, u8 new_state);
857 /* call when cwnd event occurs (optional) */
858 void (*cwnd_event)(struct sock *sk, enum tcp_ca_event ev);
859 /* call when ack arrives (optional) */
860 void (*in_ack_event)(struct sock *sk, u32 flags);
861 /* new value of cwnd after loss (optional) */
862 u32 (*undo_cwnd)(struct sock *sk);
863 /* hook for packet ack accounting (optional) */
864 void (*pkts_acked)(struct sock *sk, u32 num_acked, s32 rtt_us);
865 /* get info for inet_diag (optional) */
866 size_t (*get_info)(struct sock *sk, u32 ext, int *attr,
867 union tcp_cc_info *info);
868
869 char name[TCP_CA_NAME_MAX];
870 struct module *owner;
871};
872
873int tcp_register_congestion_control(struct tcp_congestion_ops *type);
874void tcp_unregister_congestion_control(struct tcp_congestion_ops *type);
875
876void tcp_assign_congestion_control(struct sock *sk);
877void tcp_init_congestion_control(struct sock *sk);
878void tcp_cleanup_congestion_control(struct sock *sk);
879int tcp_set_default_congestion_control(const char *name);
880void tcp_get_default_congestion_control(char *name);
881void tcp_get_available_congestion_control(char *buf, size_t len);
882void tcp_get_allowed_congestion_control(char *buf, size_t len);
883int tcp_set_allowed_congestion_control(char *allowed);
884int tcp_set_congestion_control(struct sock *sk, const char *name);
885u32 tcp_slow_start(struct tcp_sock *tp, u32 acked);
886void tcp_cong_avoid_ai(struct tcp_sock *tp, u32 w, u32 acked);
887
888u32 tcp_reno_ssthresh(struct sock *sk);
889void tcp_reno_cong_avoid(struct sock *sk, u32 ack, u32 acked);
890extern struct tcp_congestion_ops tcp_reno;
891
892struct tcp_congestion_ops *tcp_ca_find_key(u32 key);
893u32 tcp_ca_get_key_by_name(const char *name, bool *ecn_ca);
894#ifdef CONFIG_INET
895char *tcp_ca_get_name_by_key(u32 key, char *buffer);
896#else
897static inline char *tcp_ca_get_name_by_key(u32 key, char *buffer)
898{
899 return NULL;
900}
901#endif
902
903static inline bool tcp_ca_needs_ecn(const struct sock *sk)
904{
905 const struct inet_connection_sock *icsk = inet_csk(sk);
906
907 return icsk->icsk_ca_ops->flags & TCP_CONG_NEEDS_ECN;
908}
909
910static inline void tcp_set_ca_state(struct sock *sk, const u8 ca_state)
911{
912 struct inet_connection_sock *icsk = inet_csk(sk);
913
914 if (icsk->icsk_ca_ops->set_state)
915 icsk->icsk_ca_ops->set_state(sk, ca_state);
916 icsk->icsk_ca_state = ca_state;
917}
918
919static inline void tcp_ca_event(struct sock *sk, const enum tcp_ca_event event)
920{
921 const struct inet_connection_sock *icsk = inet_csk(sk);
922
923 if (icsk->icsk_ca_ops->cwnd_event)
924 icsk->icsk_ca_ops->cwnd_event(sk, event);
925}
926
927/* These functions determine how the current flow behaves in respect of SACK
928 * handling. SACK is negotiated with the peer, and therefore it can vary
929 * between different flows.
930 *
931 * tcp_is_sack - SACK enabled
932 * tcp_is_reno - No SACK
933 * tcp_is_fack - FACK enabled, implies SACK enabled
934 */
935static inline int tcp_is_sack(const struct tcp_sock *tp)
936{
937 return tp->rx_opt.sack_ok;
938}
939
940static inline bool tcp_is_reno(const struct tcp_sock *tp)
941{
942 return !tcp_is_sack(tp);
943}
944
945static inline bool tcp_is_fack(const struct tcp_sock *tp)
946{
947 return tp->rx_opt.sack_ok & TCP_FACK_ENABLED;
948}
949
950static inline void tcp_enable_fack(struct tcp_sock *tp)
951{
952 tp->rx_opt.sack_ok |= TCP_FACK_ENABLED;
953}
954
955/* TCP early-retransmit (ER) is similar to but more conservative than
956 * the thin-dupack feature. Enable ER only if thin-dupack is disabled.
957 */
958static inline void tcp_enable_early_retrans(struct tcp_sock *tp)
959{
960 struct net *net = sock_net((struct sock *)tp);
961
962 tp->do_early_retrans = sysctl_tcp_early_retrans &&
963 sysctl_tcp_early_retrans < 4 && !sysctl_tcp_thin_dupack &&
964 net->ipv4.sysctl_tcp_reordering == 3;
965}
966
967static inline void tcp_disable_early_retrans(struct tcp_sock *tp)
968{
969 tp->do_early_retrans = 0;
970}
971
972static inline unsigned int tcp_left_out(const struct tcp_sock *tp)
973{
974 return tp->sacked_out + tp->lost_out;
975}
976
977/* This determines how many packets are "in the network" to the best
978 * of our knowledge. In many cases it is conservative, but where
979 * detailed information is available from the receiver (via SACK
980 * blocks etc.) we can make more aggressive calculations.
981 *
982 * Use this for decisions involving congestion control, use just
983 * tp->packets_out to determine if the send queue is empty or not.
984 *
985 * Read this equation as:
986 *
987 * "Packets sent once on transmission queue" MINUS
988 * "Packets left network, but not honestly ACKed yet" PLUS
989 * "Packets fast retransmitted"
990 */
991static inline unsigned int tcp_packets_in_flight(const struct tcp_sock *tp)
992{
993 return tp->packets_out - tcp_left_out(tp) + tp->retrans_out;
994}
995
996#define TCP_INFINITE_SSTHRESH 0x7fffffff
997
998static inline bool tcp_in_slow_start(const struct tcp_sock *tp)
999{
1000 return tp->snd_cwnd < tp->snd_ssthresh;
1001}
1002
1003static inline bool tcp_in_initial_slowstart(const struct tcp_sock *tp)
1004{
1005 return tp->snd_ssthresh >= TCP_INFINITE_SSTHRESH;
1006}
1007
1008static inline bool tcp_in_cwnd_reduction(const struct sock *sk)
1009{
1010 return (TCPF_CA_CWR | TCPF_CA_Recovery) &
1011 (1 << inet_csk(sk)->icsk_ca_state);
1012}
1013
1014/* If cwnd > ssthresh, we may raise ssthresh to be half-way to cwnd.
1015 * The exception is cwnd reduction phase, when cwnd is decreasing towards
1016 * ssthresh.
1017 */
1018static inline __u32 tcp_current_ssthresh(const struct sock *sk)
1019{
1020 const struct tcp_sock *tp = tcp_sk(sk);
1021
1022 if (tcp_in_cwnd_reduction(sk))
1023 return tp->snd_ssthresh;
1024 else
1025 return max(tp->snd_ssthresh,
1026 ((tp->snd_cwnd >> 1) +
1027 (tp->snd_cwnd >> 2)));
1028}
1029
1030/* Use define here intentionally to get WARN_ON location shown at the caller */
1031#define tcp_verify_left_out(tp) WARN_ON(tcp_left_out(tp) > tp->packets_out)
1032
1033void tcp_enter_cwr(struct sock *sk);
1034__u32 tcp_init_cwnd(const struct tcp_sock *tp, const struct dst_entry *dst);
1035
1036/* The maximum number of MSS of available cwnd for which TSO defers
1037 * sending if not using sysctl_tcp_tso_win_divisor.
1038 */
1039static inline __u32 tcp_max_tso_deferred_mss(const struct tcp_sock *tp)
1040{
1041 return 3;
1042}
1043
1044/* Slow start with delack produces 3 packets of burst, so that
1045 * it is safe "de facto". This will be the default - same as
1046 * the default reordering threshold - but if reordering increases,
1047 * we must be able to allow cwnd to burst at least this much in order
1048 * to not pull it back when holes are filled.
1049 */
1050static __inline__ __u32 tcp_max_burst(const struct tcp_sock *tp)
1051{
1052 return tp->reordering;
1053}
1054
1055/* Returns end sequence number of the receiver's advertised window */
1056static inline u32 tcp_wnd_end(const struct tcp_sock *tp)
1057{
1058 return tp->snd_una + tp->snd_wnd;
1059}
1060
1061/* We follow the spirit of RFC2861 to validate cwnd but implement a more
1062 * flexible approach. The RFC suggests cwnd should not be raised unless
1063 * it was fully used previously. And that's exactly what we do in
1064 * congestion avoidance mode. But in slow start we allow cwnd to grow
1065 * as long as the application has used half the cwnd.
1066 * Example :
1067 * cwnd is 10 (IW10), but application sends 9 frames.
1068 * We allow cwnd to reach 18 when all frames are ACKed.
1069 * This check is safe because it's as aggressive as slow start which already
1070 * risks 100% overshoot. The advantage is that we discourage application to
1071 * either send more filler packets or data to artificially blow up the cwnd
1072 * usage, and allow application-limited process to probe bw more aggressively.
1073 */
1074static inline bool tcp_is_cwnd_limited(const struct sock *sk)
1075{
1076 const struct tcp_sock *tp = tcp_sk(sk);
1077
1078 /* If in slow start, ensure cwnd grows to twice what was ACKed. */
1079 if (tcp_in_slow_start(tp))
1080 return tp->snd_cwnd < 2 * tp->max_packets_out;
1081
1082 return tp->is_cwnd_limited;
1083}
1084
1085/* Something is really bad, we could not queue an additional packet,
1086 * because qdisc is full or receiver sent a 0 window.
1087 * We do not want to add fuel to the fire, or abort too early,
1088 * so make sure the timer we arm now is at least 200ms in the future,
1089 * regardless of current icsk_rto value (as it could be ~2ms)
1090 */
1091static inline unsigned long tcp_probe0_base(const struct sock *sk)
1092{
1093 return max_t(unsigned long, inet_csk(sk)->icsk_rto, TCP_RTO_MIN);
1094}
1095
1096/* Variant of inet_csk_rto_backoff() used for zero window probes */
1097static inline unsigned long tcp_probe0_when(const struct sock *sk,
1098 unsigned long max_when)
1099{
1100 u64 when = (u64)tcp_probe0_base(sk) << inet_csk(sk)->icsk_backoff;
1101
1102 return (unsigned long)min_t(u64, when, max_when);
1103}
1104
1105static inline void tcp_check_probe_timer(struct sock *sk)
1106{
1107 if (!tcp_sk(sk)->packets_out && !inet_csk(sk)->icsk_pending)
1108 inet_csk_reset_xmit_timer(sk, ICSK_TIME_PROBE0,
1109 tcp_probe0_base(sk), TCP_RTO_MAX);
1110}
1111
1112static inline void tcp_init_wl(struct tcp_sock *tp, u32 seq)
1113{
1114 tp->snd_wl1 = seq;
1115}
1116
1117static inline void tcp_update_wl(struct tcp_sock *tp, u32 seq)
1118{
1119 tp->snd_wl1 = seq;
1120}
1121
1122/*
1123 * Calculate(/check) TCP checksum
1124 */
1125static inline __sum16 tcp_v4_check(int len, __be32 saddr,
1126 __be32 daddr, __wsum base)
1127{
1128 return csum_tcpudp_magic(saddr,daddr,len,IPPROTO_TCP,base);
1129}
1130
1131static inline __sum16 __tcp_checksum_complete(struct sk_buff *skb)
1132{
1133 return __skb_checksum_complete(skb);
1134}
1135
1136static inline bool tcp_checksum_complete(struct sk_buff *skb)
1137{
1138 return !skb_csum_unnecessary(skb) &&
1139 __tcp_checksum_complete(skb);
1140}
1141
1142/* Prequeue for VJ style copy to user, combined with checksumming. */
1143
1144static inline void tcp_prequeue_init(struct tcp_sock *tp)
1145{
1146 tp->ucopy.task = NULL;
1147 tp->ucopy.len = 0;
1148 tp->ucopy.memory = 0;
1149 skb_queue_head_init(&tp->ucopy.prequeue);
1150}
1151
1152bool tcp_prequeue(struct sock *sk, struct sk_buff *skb);
1153
1154#undef STATE_TRACE
1155
1156#ifdef STATE_TRACE
1157static const char *statename[]={
1158 "Unused","Established","Syn Sent","Syn Recv",
1159 "Fin Wait 1","Fin Wait 2","Time Wait", "Close",
1160 "Close Wait","Last ACK","Listen","Closing"
1161};
1162#endif
1163void tcp_set_state(struct sock *sk, int state);
1164
1165void tcp_done(struct sock *sk);
1166
1167int tcp_abort(struct sock *sk, int err);
1168
1169static inline void tcp_sack_reset(struct tcp_options_received *rx_opt)
1170{
1171 rx_opt->dsack = 0;
1172 rx_opt->num_sacks = 0;
1173}
1174
1175u32 tcp_default_init_rwnd(u32 mss);
1176void tcp_cwnd_restart(struct sock *sk, s32 delta);
1177
1178static inline void tcp_slow_start_after_idle_check(struct sock *sk)
1179{
1180 struct tcp_sock *tp = tcp_sk(sk);
1181 s32 delta;
1182
1183 if (!sysctl_tcp_slow_start_after_idle || tp->packets_out)
1184 return;
1185 delta = tcp_time_stamp - tp->lsndtime;
1186 if (delta > inet_csk(sk)->icsk_rto)
1187 tcp_cwnd_restart(sk, delta);
1188}
1189
1190/* Determine a window scaling and initial window to offer. */
1191void tcp_select_initial_window(int __space, __u32 mss, __u32 *rcv_wnd,
1192 __u32 *window_clamp, int wscale_ok,
1193 __u8 *rcv_wscale, __u32 init_rcv_wnd);
1194
1195static inline int tcp_win_from_space(int space)
1196{
1197 return sysctl_tcp_adv_win_scale<=0 ?
1198 (space>>(-sysctl_tcp_adv_win_scale)) :
1199 space - (space>>sysctl_tcp_adv_win_scale);
1200}
1201
1202/* Note: caller must be prepared to deal with negative returns */
1203static inline int tcp_space(const struct sock *sk)
1204{
1205 return tcp_win_from_space(sk->sk_rcvbuf -
1206 atomic_read(&sk->sk_rmem_alloc));
1207}
1208
1209static inline int tcp_full_space(const struct sock *sk)
1210{
1211 return tcp_win_from_space(sk->sk_rcvbuf);
1212}
1213
1214extern void tcp_openreq_init_rwin(struct request_sock *req,
1215 const struct sock *sk_listener,
1216 const struct dst_entry *dst);
1217
1218void tcp_enter_memory_pressure(struct sock *sk);
1219
1220static inline int keepalive_intvl_when(const struct tcp_sock *tp)
1221{
1222 struct net *net = sock_net((struct sock *)tp);
1223
1224 return tp->keepalive_intvl ? : net->ipv4.sysctl_tcp_keepalive_intvl;
1225}
1226
1227static inline int keepalive_time_when(const struct tcp_sock *tp)
1228{
1229 struct net *net = sock_net((struct sock *)tp);
1230
1231 return tp->keepalive_time ? : net->ipv4.sysctl_tcp_keepalive_time;
1232}
1233
1234static inline int keepalive_probes(const struct tcp_sock *tp)
1235{
1236 struct net *net = sock_net((struct sock *)tp);
1237
1238 return tp->keepalive_probes ? : net->ipv4.sysctl_tcp_keepalive_probes;
1239}
1240
1241static inline u32 keepalive_time_elapsed(const struct tcp_sock *tp)
1242{
1243 const struct inet_connection_sock *icsk = &tp->inet_conn;
1244
1245 return min_t(u32, tcp_time_stamp - icsk->icsk_ack.lrcvtime,
1246 tcp_time_stamp - tp->rcv_tstamp);
1247}
1248
1249static inline int tcp_fin_time(const struct sock *sk)
1250{
1251 int fin_timeout = tcp_sk(sk)->linger2 ? : sock_net(sk)->ipv4.sysctl_tcp_fin_timeout;
1252 const int rto = inet_csk(sk)->icsk_rto;
1253
1254 if (fin_timeout < (rto << 2) - (rto >> 1))
1255 fin_timeout = (rto << 2) - (rto >> 1);
1256
1257 return fin_timeout;
1258}
1259
1260static inline bool tcp_paws_check(const struct tcp_options_received *rx_opt,
1261 int paws_win)
1262{
1263 if ((s32)(rx_opt->ts_recent - rx_opt->rcv_tsval) <= paws_win)
1264 return true;
1265 if (unlikely(get_seconds() >= rx_opt->ts_recent_stamp + TCP_PAWS_24DAYS))
1266 return true;
1267 /*
1268 * Some OSes send SYN and SYNACK messages with tsval=0 tsecr=0,
1269 * then following tcp messages have valid values. Ignore 0 value,
1270 * or else 'negative' tsval might forbid us to accept their packets.
1271 */
1272 if (!rx_opt->ts_recent)
1273 return true;
1274 return false;
1275}
1276
1277static inline bool tcp_paws_reject(const struct tcp_options_received *rx_opt,
1278 int rst)
1279{
1280 if (tcp_paws_check(rx_opt, 0))
1281 return false;
1282
1283 /* RST segments are not recommended to carry timestamp,
1284 and, if they do, it is recommended to ignore PAWS because
1285 "their cleanup function should take precedence over timestamps."
1286 Certainly, it is mistake. It is necessary to understand the reasons
1287 of this constraint to relax it: if peer reboots, clock may go
1288 out-of-sync and half-open connections will not be reset.
1289 Actually, the problem would be not existing if all
1290 the implementations followed draft about maintaining clock
1291 via reboots. Linux-2.2 DOES NOT!
1292
1293 However, we can relax time bounds for RST segments to MSL.
1294 */
1295 if (rst && get_seconds() >= rx_opt->ts_recent_stamp + TCP_PAWS_MSL)
1296 return false;
1297 return true;
1298}
1299
1300bool tcp_oow_rate_limited(struct net *net, const struct sk_buff *skb,
1301 int mib_idx, u32 *last_oow_ack_time);
1302
1303static inline void tcp_mib_init(struct net *net)
1304{
1305 /* See RFC 2012 */
1306 TCP_ADD_STATS_USER(net, TCP_MIB_RTOALGORITHM, 1);
1307 TCP_ADD_STATS_USER(net, TCP_MIB_RTOMIN, TCP_RTO_MIN*1000/HZ);
1308 TCP_ADD_STATS_USER(net, TCP_MIB_RTOMAX, TCP_RTO_MAX*1000/HZ);
1309 TCP_ADD_STATS_USER(net, TCP_MIB_MAXCONN, -1);
1310}
1311
1312/* from STCP */
1313static inline void tcp_clear_retrans_hints_partial(struct tcp_sock *tp)
1314{
1315 tp->lost_skb_hint = NULL;
1316}
1317
1318static inline void tcp_clear_all_retrans_hints(struct tcp_sock *tp)
1319{
1320 tcp_clear_retrans_hints_partial(tp);
1321 tp->retransmit_skb_hint = NULL;
1322}
1323
1324union tcp_md5_addr {
1325 struct in_addr a4;
1326#if IS_ENABLED(CONFIG_IPV6)
1327 struct in6_addr a6;
1328#endif
1329};
1330
1331/* - key database */
1332struct tcp_md5sig_key {
1333 struct hlist_node node;
1334 u8 keylen;
1335 u8 family; /* AF_INET or AF_INET6 */
1336 union tcp_md5_addr addr;
1337 u8 key[TCP_MD5SIG_MAXKEYLEN];
1338 struct rcu_head rcu;
1339};
1340
1341/* - sock block */
1342struct tcp_md5sig_info {
1343 struct hlist_head head;
1344 struct rcu_head rcu;
1345};
1346
1347/* - pseudo header */
1348struct tcp4_pseudohdr {
1349 __be32 saddr;
1350 __be32 daddr;
1351 __u8 pad;
1352 __u8 protocol;
1353 __be16 len;
1354};
1355
1356struct tcp6_pseudohdr {
1357 struct in6_addr saddr;
1358 struct in6_addr daddr;
1359 __be32 len;
1360 __be32 protocol; /* including padding */
1361};
1362
1363union tcp_md5sum_block {
1364 struct tcp4_pseudohdr ip4;
1365#if IS_ENABLED(CONFIG_IPV6)
1366 struct tcp6_pseudohdr ip6;
1367#endif
1368};
1369
1370/* - pool: digest algorithm, hash description and scratch buffer */
1371struct tcp_md5sig_pool {
1372 struct ahash_request *md5_req;
1373 union tcp_md5sum_block md5_blk;
1374};
1375
1376/* - functions */
1377int tcp_v4_md5_hash_skb(char *md5_hash, const struct tcp_md5sig_key *key,
1378 const struct sock *sk, const struct sk_buff *skb);
1379int tcp_md5_do_add(struct sock *sk, const union tcp_md5_addr *addr,
1380 int family, const u8 *newkey, u8 newkeylen, gfp_t gfp);
1381int tcp_md5_do_del(struct sock *sk, const union tcp_md5_addr *addr,
1382 int family);
1383struct tcp_md5sig_key *tcp_v4_md5_lookup(const struct sock *sk,
1384 const struct sock *addr_sk);
1385
1386#ifdef CONFIG_TCP_MD5SIG
1387struct tcp_md5sig_key *tcp_md5_do_lookup(const struct sock *sk,
1388 const union tcp_md5_addr *addr,
1389 int family);
1390#define tcp_twsk_md5_key(twsk) ((twsk)->tw_md5_key)
1391#else
1392static inline struct tcp_md5sig_key *tcp_md5_do_lookup(const struct sock *sk,
1393 const union tcp_md5_addr *addr,
1394 int family)
1395{
1396 return NULL;
1397}
1398#define tcp_twsk_md5_key(twsk) NULL
1399#endif
1400
1401bool tcp_alloc_md5sig_pool(void);
1402
1403struct tcp_md5sig_pool *tcp_get_md5sig_pool(void);
1404static inline void tcp_put_md5sig_pool(void)
1405{
1406 local_bh_enable();
1407}
1408
1409int tcp_md5_hash_header(struct tcp_md5sig_pool *, const struct tcphdr *);
1410int tcp_md5_hash_skb_data(struct tcp_md5sig_pool *, const struct sk_buff *,
1411 unsigned int header_len);
1412int tcp_md5_hash_key(struct tcp_md5sig_pool *hp,
1413 const struct tcp_md5sig_key *key);
1414
1415/* From tcp_fastopen.c */
1416void tcp_fastopen_cache_get(struct sock *sk, u16 *mss,
1417 struct tcp_fastopen_cookie *cookie, int *syn_loss,
1418 unsigned long *last_syn_loss);
1419void tcp_fastopen_cache_set(struct sock *sk, u16 mss,
1420 struct tcp_fastopen_cookie *cookie, bool syn_lost,
1421 u16 try_exp);
1422struct tcp_fastopen_request {
1423 /* Fast Open cookie. Size 0 means a cookie request */
1424 struct tcp_fastopen_cookie cookie;
1425 struct msghdr *data; /* data in MSG_FASTOPEN */
1426 size_t size;
1427 int copied; /* queued in tcp_connect() */
1428};
1429void tcp_free_fastopen_req(struct tcp_sock *tp);
1430
1431extern struct tcp_fastopen_context __rcu *tcp_fastopen_ctx;
1432int tcp_fastopen_reset_cipher(void *key, unsigned int len);
1433void tcp_fastopen_add_skb(struct sock *sk, struct sk_buff *skb);
1434struct sock *tcp_try_fastopen(struct sock *sk, struct sk_buff *skb,
1435 struct request_sock *req,
1436 struct tcp_fastopen_cookie *foc,
1437 struct dst_entry *dst);
1438void tcp_fastopen_init_key_once(bool publish);
1439#define TCP_FASTOPEN_KEY_LENGTH 16
1440
1441/* Fastopen key context */
1442struct tcp_fastopen_context {
1443 struct crypto_cipher *tfm;
1444 __u8 key[TCP_FASTOPEN_KEY_LENGTH];
1445 struct rcu_head rcu;
1446};
1447
1448/* write queue abstraction */
1449static inline void tcp_write_queue_purge(struct sock *sk)
1450{
1451 struct sk_buff *skb;
1452
1453 while ((skb = __skb_dequeue(&sk->sk_write_queue)) != NULL)
1454 sk_wmem_free_skb(sk, skb);
1455 sk_mem_reclaim(sk);
1456 tcp_clear_all_retrans_hints(tcp_sk(sk));
1457}
1458
1459static inline struct sk_buff *tcp_write_queue_head(const struct sock *sk)
1460{
1461 return skb_peek(&sk->sk_write_queue);
1462}
1463
1464static inline struct sk_buff *tcp_write_queue_tail(const struct sock *sk)
1465{
1466 return skb_peek_tail(&sk->sk_write_queue);
1467}
1468
1469static inline struct sk_buff *tcp_write_queue_next(const struct sock *sk,
1470 const struct sk_buff *skb)
1471{
1472 return skb_queue_next(&sk->sk_write_queue, skb);
1473}
1474
1475static inline struct sk_buff *tcp_write_queue_prev(const struct sock *sk,
1476 const struct sk_buff *skb)
1477{
1478 return skb_queue_prev(&sk->sk_write_queue, skb);
1479}
1480
1481#define tcp_for_write_queue(skb, sk) \
1482 skb_queue_walk(&(sk)->sk_write_queue, skb)
1483
1484#define tcp_for_write_queue_from(skb, sk) \
1485 skb_queue_walk_from(&(sk)->sk_write_queue, skb)
1486
1487#define tcp_for_write_queue_from_safe(skb, tmp, sk) \
1488 skb_queue_walk_from_safe(&(sk)->sk_write_queue, skb, tmp)
1489
1490static inline struct sk_buff *tcp_send_head(const struct sock *sk)
1491{
1492 return sk->sk_send_head;
1493}
1494
1495static inline bool tcp_skb_is_last(const struct sock *sk,
1496 const struct sk_buff *skb)
1497{
1498 return skb_queue_is_last(&sk->sk_write_queue, skb);
1499}
1500
1501static inline void tcp_advance_send_head(struct sock *sk, const struct sk_buff *skb)
1502{
1503 if (tcp_skb_is_last(sk, skb))
1504 sk->sk_send_head = NULL;
1505 else
1506 sk->sk_send_head = tcp_write_queue_next(sk, skb);
1507}
1508
1509static inline void tcp_check_send_head(struct sock *sk, struct sk_buff *skb_unlinked)
1510{
1511 if (sk->sk_send_head == skb_unlinked)
1512 sk->sk_send_head = NULL;
1513}
1514
1515static inline void tcp_init_send_head(struct sock *sk)
1516{
1517 sk->sk_send_head = NULL;
1518}
1519
1520static inline void __tcp_add_write_queue_tail(struct sock *sk, struct sk_buff *skb)
1521{
1522 __skb_queue_tail(&sk->sk_write_queue, skb);
1523}
1524
1525static inline void tcp_add_write_queue_tail(struct sock *sk, struct sk_buff *skb)
1526{
1527 __tcp_add_write_queue_tail(sk, skb);
1528
1529 /* Queue it, remembering where we must start sending. */
1530 if (sk->sk_send_head == NULL) {
1531 sk->sk_send_head = skb;
1532
1533 if (tcp_sk(sk)->highest_sack == NULL)
1534 tcp_sk(sk)->highest_sack = skb;
1535 }
1536}
1537
1538static inline void __tcp_add_write_queue_head(struct sock *sk, struct sk_buff *skb)
1539{
1540 __skb_queue_head(&sk->sk_write_queue, skb);
1541}
1542
1543/* Insert buff after skb on the write queue of sk. */
1544static inline void tcp_insert_write_queue_after(struct sk_buff *skb,
1545 struct sk_buff *buff,
1546 struct sock *sk)
1547{
1548 __skb_queue_after(&sk->sk_write_queue, skb, buff);
1549}
1550
1551/* Insert new before skb on the write queue of sk. */
1552static inline void tcp_insert_write_queue_before(struct sk_buff *new,
1553 struct sk_buff *skb,
1554 struct sock *sk)
1555{
1556 __skb_queue_before(&sk->sk_write_queue, skb, new);
1557
1558 if (sk->sk_send_head == skb)
1559 sk->sk_send_head = new;
1560}
1561
1562static inline void tcp_unlink_write_queue(struct sk_buff *skb, struct sock *sk)
1563{
1564 __skb_unlink(skb, &sk->sk_write_queue);
1565}
1566
1567static inline bool tcp_write_queue_empty(struct sock *sk)
1568{
1569 return skb_queue_empty(&sk->sk_write_queue);
1570}
1571
1572static inline void tcp_push_pending_frames(struct sock *sk)
1573{
1574 if (tcp_send_head(sk)) {
1575 struct tcp_sock *tp = tcp_sk(sk);
1576
1577 __tcp_push_pending_frames(sk, tcp_current_mss(sk), tp->nonagle);
1578 }
1579}
1580
1581/* Start sequence of the skb just after the highest skb with SACKed
1582 * bit, valid only if sacked_out > 0 or when the caller has ensured
1583 * validity by itself.
1584 */
1585static inline u32 tcp_highest_sack_seq(struct tcp_sock *tp)
1586{
1587 if (!tp->sacked_out)
1588 return tp->snd_una;
1589
1590 if (tp->highest_sack == NULL)
1591 return tp->snd_nxt;
1592
1593 return TCP_SKB_CB(tp->highest_sack)->seq;
1594}
1595
1596static inline void tcp_advance_highest_sack(struct sock *sk, struct sk_buff *skb)
1597{
1598 tcp_sk(sk)->highest_sack = tcp_skb_is_last(sk, skb) ? NULL :
1599 tcp_write_queue_next(sk, skb);
1600}
1601
1602static inline struct sk_buff *tcp_highest_sack(struct sock *sk)
1603{
1604 return tcp_sk(sk)->highest_sack;
1605}
1606
1607static inline void tcp_highest_sack_reset(struct sock *sk)
1608{
1609 tcp_sk(sk)->highest_sack = tcp_write_queue_head(sk);
1610}
1611
1612/* Called when old skb is about to be deleted (to be combined with new skb) */
1613static inline void tcp_highest_sack_combine(struct sock *sk,
1614 struct sk_buff *old,
1615 struct sk_buff *new)
1616{
1617 if (tcp_sk(sk)->sacked_out && (old == tcp_sk(sk)->highest_sack))
1618 tcp_sk(sk)->highest_sack = new;
1619}
1620
1621/* This helper checks if socket has IP_TRANSPARENT set */
1622static inline bool inet_sk_transparent(const struct sock *sk)
1623{
1624 switch (sk->sk_state) {
1625 case TCP_TIME_WAIT:
1626 return inet_twsk(sk)->tw_transparent;
1627 case TCP_NEW_SYN_RECV:
1628 return inet_rsk(inet_reqsk(sk))->no_srccheck;
1629 }
1630 return inet_sk(sk)->transparent;
1631}
1632
1633/* Determines whether this is a thin stream (which may suffer from
1634 * increased latency). Used to trigger latency-reducing mechanisms.
1635 */
1636static inline bool tcp_stream_is_thin(struct tcp_sock *tp)
1637{
1638 return tp->packets_out < 4 && !tcp_in_initial_slowstart(tp);
1639}
1640
1641/* /proc */
1642enum tcp_seq_states {
1643 TCP_SEQ_STATE_LISTENING,
1644 TCP_SEQ_STATE_ESTABLISHED,
1645};
1646
1647int tcp_seq_open(struct inode *inode, struct file *file);
1648
1649struct tcp_seq_afinfo {
1650 char *name;
1651 sa_family_t family;
1652 const struct file_operations *seq_fops;
1653 struct seq_operations seq_ops;
1654};
1655
1656struct tcp_iter_state {
1657 struct seq_net_private p;
1658 sa_family_t family;
1659 enum tcp_seq_states state;
1660 struct sock *syn_wait_sk;
1661 int bucket, offset, sbucket, num;
1662 loff_t last_pos;
1663};
1664
1665int tcp_proc_register(struct net *net, struct tcp_seq_afinfo *afinfo);
1666void tcp_proc_unregister(struct net *net, struct tcp_seq_afinfo *afinfo);
1667
1668extern struct request_sock_ops tcp_request_sock_ops;
1669extern struct request_sock_ops tcp6_request_sock_ops;
1670
1671void tcp_v4_destroy_sock(struct sock *sk);
1672
1673struct sk_buff *tcp_gso_segment(struct sk_buff *skb,
1674 netdev_features_t features);
1675struct sk_buff **tcp_gro_receive(struct sk_buff **head, struct sk_buff *skb);
1676int tcp_gro_complete(struct sk_buff *skb);
1677
1678void __tcp_v4_send_check(struct sk_buff *skb, __be32 saddr, __be32 daddr);
1679
1680static inline u32 tcp_notsent_lowat(const struct tcp_sock *tp)
1681{
1682 struct net *net = sock_net((struct sock *)tp);
1683 return tp->notsent_lowat ?: net->ipv4.sysctl_tcp_notsent_lowat;
1684}
1685
1686static inline bool tcp_stream_memory_free(const struct sock *sk)
1687{
1688 const struct tcp_sock *tp = tcp_sk(sk);
1689 u32 notsent_bytes = tp->write_seq - tp->snd_nxt;
1690
1691 return notsent_bytes < tcp_notsent_lowat(tp);
1692}
1693
1694#ifdef CONFIG_PROC_FS
1695int tcp4_proc_init(void);
1696void tcp4_proc_exit(void);
1697#endif
1698
1699int tcp_rtx_synack(const struct sock *sk, struct request_sock *req);
1700int tcp_conn_request(struct request_sock_ops *rsk_ops,
1701 const struct tcp_request_sock_ops *af_ops,
1702 struct sock *sk, struct sk_buff *skb);
1703
1704/* TCP af-specific functions */
1705struct tcp_sock_af_ops {
1706#ifdef CONFIG_TCP_MD5SIG
1707 struct tcp_md5sig_key *(*md5_lookup) (const struct sock *sk,
1708 const struct sock *addr_sk);
1709 int (*calc_md5_hash)(char *location,
1710 const struct tcp_md5sig_key *md5,
1711 const struct sock *sk,
1712 const struct sk_buff *skb);
1713 int (*md5_parse)(struct sock *sk,
1714 char __user *optval,
1715 int optlen);
1716#endif
1717};
1718
1719struct tcp_request_sock_ops {
1720 u16 mss_clamp;
1721#ifdef CONFIG_TCP_MD5SIG
1722 struct tcp_md5sig_key *(*req_md5_lookup)(const struct sock *sk,
1723 const struct sock *addr_sk);
1724 int (*calc_md5_hash) (char *location,
1725 const struct tcp_md5sig_key *md5,
1726 const struct sock *sk,
1727 const struct sk_buff *skb);
1728#endif
1729 void (*init_req)(struct request_sock *req,
1730 const struct sock *sk_listener,
1731 struct sk_buff *skb);
1732#ifdef CONFIG_SYN_COOKIES
1733 __u32 (*cookie_init_seq)(const struct sk_buff *skb,
1734 __u16 *mss);
1735#endif
1736 struct dst_entry *(*route_req)(const struct sock *sk, struct flowi *fl,
1737 const struct request_sock *req,
1738 bool *strict);
1739 __u32 (*init_seq)(const struct sk_buff *skb);
1740 int (*send_synack)(const struct sock *sk, struct dst_entry *dst,
1741 struct flowi *fl, struct request_sock *req,
1742 struct tcp_fastopen_cookie *foc,
1743 bool attach_req);
1744};
1745
1746#ifdef CONFIG_SYN_COOKIES
1747static inline __u32 cookie_init_sequence(const struct tcp_request_sock_ops *ops,
1748 const struct sock *sk, struct sk_buff *skb,
1749 __u16 *mss)
1750{
1751 tcp_synq_overflow(sk);
1752 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_SYNCOOKIESSENT);
1753 return ops->cookie_init_seq(skb, mss);
1754}
1755#else
1756static inline __u32 cookie_init_sequence(const struct tcp_request_sock_ops *ops,
1757 const struct sock *sk, struct sk_buff *skb,
1758 __u16 *mss)
1759{
1760 return 0;
1761}
1762#endif
1763
1764int tcpv4_offload_init(void);
1765
1766void tcp_v4_init(void);
1767void tcp_init(void);
1768
1769/* tcp_recovery.c */
1770
1771/* Flags to enable various loss recovery features. See below */
1772extern int sysctl_tcp_recovery;
1773
1774/* Use TCP RACK to detect (some) tail and retransmit losses */
1775#define TCP_RACK_LOST_RETRANS 0x1
1776
1777extern int tcp_rack_mark_lost(struct sock *sk);
1778
1779extern void tcp_rack_advance(struct tcp_sock *tp,
1780 const struct skb_mstamp *xmit_time, u8 sacked);
1781
1782/*
1783 * Save and compile IPv4 options, return a pointer to it
1784 */
1785static inline struct ip_options_rcu *tcp_v4_save_options(struct sk_buff *skb)
1786{
1787 const struct ip_options *opt = &TCP_SKB_CB(skb)->header.h4.opt;
1788 struct ip_options_rcu *dopt = NULL;
1789
1790 if (opt->optlen) {
1791 int opt_size = sizeof(*dopt) + opt->optlen;
1792
1793 dopt = kmalloc(opt_size, GFP_ATOMIC);
1794 if (dopt && __ip_options_echo(&dopt->opt, skb, opt)) {
1795 kfree(dopt);
1796 dopt = NULL;
1797 }
1798 }
1799 return dopt;
1800}
1801
1802/* locally generated TCP pure ACKs have skb->truesize == 2
1803 * (check tcp_send_ack() in net/ipv4/tcp_output.c )
1804 * This is much faster than dissecting the packet to find out.
1805 * (Think of GRE encapsulations, IPv4, IPv6, ...)
1806 */
1807static inline bool skb_is_tcp_pure_ack(const struct sk_buff *skb)
1808{
1809 return skb->truesize == 2;
1810}
1811
1812static inline void skb_set_tcp_pure_ack(struct sk_buff *skb)
1813{
1814 skb->truesize = 2;
1815}
1816
1817static inline int tcp_inq(struct sock *sk)
1818{
1819 struct tcp_sock *tp = tcp_sk(sk);
1820 int answ;
1821
1822 if ((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV)) {
1823 answ = 0;
1824 } else if (sock_flag(sk, SOCK_URGINLINE) ||
1825 !tp->urg_data ||
1826 before(tp->urg_seq, tp->copied_seq) ||
1827 !before(tp->urg_seq, tp->rcv_nxt)) {
1828
1829 answ = tp->rcv_nxt - tp->copied_seq;
1830
1831 /* Subtract 1, if FIN was received */
1832 if (answ && sock_flag(sk, SOCK_DONE))
1833 answ--;
1834 } else {
1835 answ = tp->urg_seq - tp->copied_seq;
1836 }
1837
1838 return answ;
1839}
1840
1841static inline void tcp_segs_in(struct tcp_sock *tp, const struct sk_buff *skb)
1842{
1843 u16 segs_in;
1844
1845 segs_in = max_t(u16, 1, skb_shinfo(skb)->gso_segs);
1846 tp->segs_in += segs_in;
1847 if (skb->len > tcp_hdrlen(skb))
1848 tp->data_segs_in += segs_in;
1849}
1850
1851#endif /* _TCP_H */
Linux 6.x block layer and io_uring tree(s)