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.
6 * Definitions for the TCP module.
8 * Version: @(#)tcp.h 1.0.5 05/23/93
11 * Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
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.
21 #define FASTRETRANS_DEBUG 1
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/dmaengine.h>
31 #include <linux/crypto.h>
32 #include <linux/cryptohash.h>
33 #include <linux/kref.h>
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>
43 #include <net/tcp_states.h>
44 #include <net/inet_ecn.h>
47 #include <linux/seq_file.h>
48 #include <linux/memcontrol.h>
50 extern struct inet_hashinfo tcp_hashinfo;
52 extern struct percpu_counter tcp_orphan_count;
53 extern void tcp_time_wait(struct sock *sk, int state, int timeo);
55 #define MAX_TCP_HEADER (128 + MAX_HEADER)
56 #define MAX_TCP_OPTION_SPACE 40
59 * Never offer a window over 32767 without using window scaling. Some
60 * poor stacks do signed 16bit maths!
62 #define MAX_TCP_WINDOW 32767U
64 /* Minimal accepted MSS. It is (60+60+8) - (20+20). */
65 #define TCP_MIN_MSS 88U
67 /* The least MTU to use for probing */
68 #define TCP_BASE_MSS 512
70 /* After receiving this amount of duplicate ACKs fast retransmit starts. */
71 #define TCP_FASTRETRANS_THRESH 3
73 /* Maximal reordering. */
74 #define TCP_MAX_REORDERING 127
76 /* Maximal number of ACKs sent quickly to accelerate slow-start. */
77 #define TCP_MAX_QUICKACKS 16U
80 #define TCP_URG_VALID 0x0100
81 #define TCP_URG_NOTYET 0x0200
82 #define TCP_URG_READ 0x0400
84 #define TCP_RETR1 3 /*
85 * This is how many retries it does before it
86 * tries to figure out if the gateway is
87 * down. Minimal RFC value is 3; it corresponds
88 * to ~3sec-8min depending on RTO.
91 #define TCP_RETR2 15 /*
92 * This should take at least
93 * 90 minutes to time out.
94 * RFC1122 says that the limit is 100 sec.
95 * 15 is ~13-30min depending on RTO.
98 #define TCP_SYN_RETRIES 6 /* This is how many retries are done
99 * when active opening a connection.
100 * RFC1122 says the minimum retry MUST
101 * be at least 180secs. Nevertheless
102 * this value is corresponding to
103 * 63secs of retransmission with the
104 * current initial RTO.
107 #define TCP_SYNACK_RETRIES 5 /* This is how may retries are done
108 * when passive opening a connection.
109 * This is corresponding to 31secs of
110 * retransmission with the current
114 #define TCP_TIMEWAIT_LEN (60*HZ) /* how long to wait to destroy TIME-WAIT
115 * state, about 60 seconds */
116 #define TCP_FIN_TIMEOUT TCP_TIMEWAIT_LEN
117 /* BSD style FIN_WAIT2 deadlock breaker.
118 * It used to be 3min, new value is 60sec,
119 * to combine FIN-WAIT-2 timeout with
123 #define TCP_DELACK_MAX ((unsigned)(HZ/5)) /* maximal time to delay before sending an ACK */
125 #define TCP_DELACK_MIN ((unsigned)(HZ/25)) /* minimal time to delay before sending an ACK */
126 #define TCP_ATO_MIN ((unsigned)(HZ/25))
128 #define TCP_DELACK_MIN 4U
129 #define TCP_ATO_MIN 4U
131 #define TCP_RTO_MAX ((unsigned)(120*HZ))
132 #define TCP_RTO_MIN ((unsigned)(HZ/5))
133 #define TCP_TIMEOUT_INIT ((unsigned)(1*HZ)) /* RFC6298 2.1 initial RTO value */
134 #define TCP_TIMEOUT_FALLBACK ((unsigned)(3*HZ)) /* RFC 1122 initial RTO value, now
135 * used as a fallback RTO for the
136 * initial data transmission if no
137 * valid RTT sample has been acquired,
138 * most likely due to retrans in 3WHS.
141 #define TCP_RESOURCE_PROBE_INTERVAL ((unsigned)(HZ/2U)) /* Maximal interval between probes
142 * for local resources.
145 #define TCP_KEEPALIVE_TIME (120*60*HZ) /* two hours */
146 #define TCP_KEEPALIVE_PROBES 9 /* Max of 9 keepalive probes */
147 #define TCP_KEEPALIVE_INTVL (75*HZ)
149 #define MAX_TCP_KEEPIDLE 32767
150 #define MAX_TCP_KEEPINTVL 32767
151 #define MAX_TCP_KEEPCNT 127
152 #define MAX_TCP_SYNCNT 127
154 #define TCP_SYNQ_INTERVAL (HZ/5) /* Period of SYNACK timer */
156 #define TCP_PAWS_24DAYS (60 * 60 * 24 * 24)
157 #define TCP_PAWS_MSL 60 /* Per-host timestamps are invalidated
158 * after this time. It should be equal
159 * (or greater than) TCP_TIMEWAIT_LEN
160 * to provide reliability equal to one
161 * provided by timewait state.
163 #define TCP_PAWS_WINDOW 1 /* Replay window for per-host
164 * timestamps. It must be less than
165 * minimal timewait lifetime.
171 #define TCPOPT_NOP 1 /* Padding */
172 #define TCPOPT_EOL 0 /* End of options */
173 #define TCPOPT_MSS 2 /* Segment size negotiating */
174 #define TCPOPT_WINDOW 3 /* Window scaling */
175 #define TCPOPT_SACK_PERM 4 /* SACK Permitted */
176 #define TCPOPT_SACK 5 /* SACK Block */
177 #define TCPOPT_TIMESTAMP 8 /* Better RTT estimations/PAWS */
178 #define TCPOPT_MD5SIG 19 /* MD5 Signature (RFC2385) */
179 #define TCPOPT_EXP 254 /* Experimental */
180 /* Magic number to be after the option value for sharing TCP
181 * experimental options. See draft-ietf-tcpm-experimental-options-00.txt
183 #define TCPOPT_FASTOPEN_MAGIC 0xF989
189 #define TCPOLEN_MSS 4
190 #define TCPOLEN_WINDOW 3
191 #define TCPOLEN_SACK_PERM 2
192 #define TCPOLEN_TIMESTAMP 10
193 #define TCPOLEN_MD5SIG 18
194 #define TCPOLEN_EXP_FASTOPEN_BASE 4
196 /* But this is what stacks really send out. */
197 #define TCPOLEN_TSTAMP_ALIGNED 12
198 #define TCPOLEN_WSCALE_ALIGNED 4
199 #define TCPOLEN_SACKPERM_ALIGNED 4
200 #define TCPOLEN_SACK_BASE 2
201 #define TCPOLEN_SACK_BASE_ALIGNED 4
202 #define TCPOLEN_SACK_PERBLOCK 8
203 #define TCPOLEN_MD5SIG_ALIGNED 20
204 #define TCPOLEN_MSS_ALIGNED 4
206 /* Flags in tp->nonagle */
207 #define TCP_NAGLE_OFF 1 /* Nagle's algo is disabled */
208 #define TCP_NAGLE_CORK 2 /* Socket is corked */
209 #define TCP_NAGLE_PUSH 4 /* Cork is overridden for already queued data */
211 /* TCP thin-stream limits */
212 #define TCP_THIN_LINEAR_RETRIES 6 /* After 6 linear retries, do exp. backoff */
214 /* TCP initial congestion window as per draft-hkchu-tcpm-initcwnd-01 */
215 #define TCP_INIT_CWND 10
217 /* Bit Flags for sysctl_tcp_fastopen */
218 #define TFO_CLIENT_ENABLE 1
219 #define TFO_SERVER_ENABLE 2
220 #define TFO_CLIENT_NO_COOKIE 4 /* Data in SYN w/o cookie option */
222 /* Process SYN data but skip cookie validation */
223 #define TFO_SERVER_COOKIE_NOT_CHKED 0x100
224 /* Accept SYN data w/o any cookie option */
225 #define TFO_SERVER_COOKIE_NOT_REQD 0x200
227 /* Force enable TFO on all listeners, i.e., not requiring the
228 * TCP_FASTOPEN socket option. SOCKOPT1/2 determine how to set max_qlen.
230 #define TFO_SERVER_WO_SOCKOPT1 0x400
231 #define TFO_SERVER_WO_SOCKOPT2 0x800
232 /* Always create TFO child sockets on a TFO listener even when
233 * cookie/data not present. (For testing purpose!)
235 #define TFO_SERVER_ALWAYS 0x1000
237 extern struct inet_timewait_death_row tcp_death_row;
239 /* sysctl variables for tcp */
240 extern int sysctl_tcp_timestamps;
241 extern int sysctl_tcp_window_scaling;
242 extern int sysctl_tcp_sack;
243 extern int sysctl_tcp_fin_timeout;
244 extern int sysctl_tcp_keepalive_time;
245 extern int sysctl_tcp_keepalive_probes;
246 extern int sysctl_tcp_keepalive_intvl;
247 extern int sysctl_tcp_syn_retries;
248 extern int sysctl_tcp_synack_retries;
249 extern int sysctl_tcp_retries1;
250 extern int sysctl_tcp_retries2;
251 extern int sysctl_tcp_orphan_retries;
252 extern int sysctl_tcp_syncookies;
253 extern int sysctl_tcp_fastopen;
254 extern int sysctl_tcp_retrans_collapse;
255 extern int sysctl_tcp_stdurg;
256 extern int sysctl_tcp_rfc1337;
257 extern int sysctl_tcp_abort_on_overflow;
258 extern int sysctl_tcp_max_orphans;
259 extern int sysctl_tcp_fack;
260 extern int sysctl_tcp_reordering;
261 extern int sysctl_tcp_dsack;
262 extern int sysctl_tcp_wmem[3];
263 extern int sysctl_tcp_rmem[3];
264 extern int sysctl_tcp_app_win;
265 extern int sysctl_tcp_adv_win_scale;
266 extern int sysctl_tcp_tw_reuse;
267 extern int sysctl_tcp_frto;
268 extern int sysctl_tcp_low_latency;
269 extern int sysctl_tcp_dma_copybreak;
270 extern int sysctl_tcp_nometrics_save;
271 extern int sysctl_tcp_moderate_rcvbuf;
272 extern int sysctl_tcp_tso_win_divisor;
273 extern int sysctl_tcp_mtu_probing;
274 extern int sysctl_tcp_base_mss;
275 extern int sysctl_tcp_workaround_signed_windows;
276 extern int sysctl_tcp_slow_start_after_idle;
277 extern int sysctl_tcp_max_ssthresh;
278 extern int sysctl_tcp_thin_linear_timeouts;
279 extern int sysctl_tcp_thin_dupack;
280 extern int sysctl_tcp_early_retrans;
281 extern int sysctl_tcp_limit_output_bytes;
282 extern int sysctl_tcp_challenge_ack_limit;
283 extern unsigned int sysctl_tcp_notsent_lowat;
285 extern atomic_long_t tcp_memory_allocated;
286 extern struct percpu_counter tcp_sockets_allocated;
287 extern int tcp_memory_pressure;
290 * The next routines deal with comparing 32 bit unsigned ints
291 * and worry about wraparound (automatic with unsigned arithmetic).
294 static inline bool before(__u32 seq1, __u32 seq2)
296 return (__s32)(seq1-seq2) < 0;
298 #define after(seq2, seq1) before(seq1, seq2)
300 /* is s2<=s1<=s3 ? */
301 static inline bool between(__u32 seq1, __u32 seq2, __u32 seq3)
303 return seq3 - seq2 >= seq1 - seq2;
306 static inline bool tcp_out_of_memory(struct sock *sk)
308 if (sk->sk_wmem_queued > SOCK_MIN_SNDBUF &&
309 sk_memory_allocated(sk) > sk_prot_mem_limits(sk, 2))
314 static inline bool tcp_too_many_orphans(struct sock *sk, int shift)
316 struct percpu_counter *ocp = sk->sk_prot->orphan_count;
317 int orphans = percpu_counter_read_positive(ocp);
319 if (orphans << shift > sysctl_tcp_max_orphans) {
320 orphans = percpu_counter_sum_positive(ocp);
321 if (orphans << shift > sysctl_tcp_max_orphans)
327 extern bool tcp_check_oom(struct sock *sk, int shift);
329 /* syncookies: remember time of last synqueue overflow */
330 static inline void tcp_synq_overflow(struct sock *sk)
332 tcp_sk(sk)->rx_opt.ts_recent_stamp = jiffies;
335 /* syncookies: no recent synqueue overflow on this listening socket? */
336 static inline bool tcp_synq_no_recent_overflow(const struct sock *sk)
338 unsigned long last_overflow = tcp_sk(sk)->rx_opt.ts_recent_stamp;
339 return time_after(jiffies, last_overflow + TCP_TIMEOUT_FALLBACK);
342 extern struct proto tcp_prot;
344 #define TCP_INC_STATS(net, field) SNMP_INC_STATS((net)->mib.tcp_statistics, field)
345 #define TCP_INC_STATS_BH(net, field) SNMP_INC_STATS_BH((net)->mib.tcp_statistics, field)
346 #define TCP_DEC_STATS(net, field) SNMP_DEC_STATS((net)->mib.tcp_statistics, field)
347 #define TCP_ADD_STATS_USER(net, field, val) SNMP_ADD_STATS_USER((net)->mib.tcp_statistics, field, val)
348 #define TCP_ADD_STATS(net, field, val) SNMP_ADD_STATS((net)->mib.tcp_statistics, field, val)
350 extern void tcp_init_mem(struct net *net);
352 extern void tcp_tasklet_init(void);
354 extern void tcp_v4_err(struct sk_buff *skb, u32);
356 extern void tcp_shutdown (struct sock *sk, int how);
358 extern void tcp_v4_early_demux(struct sk_buff *skb);
359 extern int tcp_v4_rcv(struct sk_buff *skb);
361 extern int tcp_v4_tw_remember_stamp(struct inet_timewait_sock *tw);
362 extern int tcp_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
364 extern int tcp_sendpage(struct sock *sk, struct page *page, int offset,
365 size_t size, int flags);
366 extern void tcp_release_cb(struct sock *sk);
367 extern void tcp_wfree(struct sk_buff *skb);
368 extern void tcp_write_timer_handler(struct sock *sk);
369 extern void tcp_delack_timer_handler(struct sock *sk);
370 extern int tcp_ioctl(struct sock *sk, int cmd, unsigned long arg);
371 extern int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb,
372 const struct tcphdr *th, unsigned int len);
373 extern int tcp_rcv_established(struct sock *sk, struct sk_buff *skb,
374 const struct tcphdr *th, unsigned int len);
375 extern void tcp_rcv_space_adjust(struct sock *sk);
376 extern void tcp_cleanup_rbuf(struct sock *sk, int copied);
377 extern int tcp_twsk_unique(struct sock *sk, struct sock *sktw, void *twp);
378 extern void tcp_twsk_destructor(struct sock *sk);
379 extern ssize_t tcp_splice_read(struct socket *sk, loff_t *ppos,
380 struct pipe_inode_info *pipe, size_t len,
383 static inline void tcp_dec_quickack_mode(struct sock *sk,
384 const unsigned int pkts)
386 struct inet_connection_sock *icsk = inet_csk(sk);
388 if (icsk->icsk_ack.quick) {
389 if (pkts >= icsk->icsk_ack.quick) {
390 icsk->icsk_ack.quick = 0;
391 /* Leaving quickack mode we deflate ATO. */
392 icsk->icsk_ack.ato = TCP_ATO_MIN;
394 icsk->icsk_ack.quick -= pkts;
399 #define TCP_ECN_QUEUE_CWR 2
400 #define TCP_ECN_DEMAND_CWR 4
401 #define TCP_ECN_SEEN 8
411 extern enum tcp_tw_status tcp_timewait_state_process(struct inet_timewait_sock *tw,
413 const struct tcphdr *th);
414 extern struct sock * tcp_check_req(struct sock *sk,struct sk_buff *skb,
415 struct request_sock *req,
416 struct request_sock **prev,
418 extern int tcp_child_process(struct sock *parent, struct sock *child,
419 struct sk_buff *skb);
420 extern void tcp_enter_loss(struct sock *sk, int how);
421 extern void tcp_clear_retrans(struct tcp_sock *tp);
422 extern void tcp_update_metrics(struct sock *sk);
423 extern void tcp_init_metrics(struct sock *sk);
424 extern void tcp_metrics_init(void);
425 extern bool tcp_peer_is_proven(struct request_sock *req, struct dst_entry *dst, bool paws_check);
426 extern bool tcp_remember_stamp(struct sock *sk);
427 extern bool tcp_tw_remember_stamp(struct inet_timewait_sock *tw);
428 extern void tcp_fetch_timewait_stamp(struct sock *sk, struct dst_entry *dst);
429 extern void tcp_disable_fack(struct tcp_sock *tp);
430 extern void tcp_close(struct sock *sk, long timeout);
431 extern void tcp_init_sock(struct sock *sk);
432 extern unsigned int tcp_poll(struct file * file, struct socket *sock,
433 struct poll_table_struct *wait);
434 extern int tcp_getsockopt(struct sock *sk, int level, int optname,
435 char __user *optval, int __user *optlen);
436 extern int tcp_setsockopt(struct sock *sk, int level, int optname,
437 char __user *optval, unsigned int optlen);
438 extern int compat_tcp_getsockopt(struct sock *sk, int level, int optname,
439 char __user *optval, int __user *optlen);
440 extern int compat_tcp_setsockopt(struct sock *sk, int level, int optname,
441 char __user *optval, unsigned int optlen);
442 extern void tcp_set_keepalive(struct sock *sk, int val);
443 extern void tcp_syn_ack_timeout(struct sock *sk, struct request_sock *req);
444 extern int tcp_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
445 size_t len, int nonblock, int flags, int *addr_len);
446 extern void tcp_parse_options(const struct sk_buff *skb,
447 struct tcp_options_received *opt_rx,
448 int estab, struct tcp_fastopen_cookie *foc);
449 extern const u8 *tcp_parse_md5sig_option(const struct tcphdr *th);
452 * TCP v4 functions exported for the inet6 API
455 extern void tcp_v4_send_check(struct sock *sk, struct sk_buff *skb);
456 extern int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb);
457 extern struct sock * tcp_create_openreq_child(struct sock *sk,
458 struct request_sock *req,
459 struct sk_buff *skb);
460 extern struct sock * tcp_v4_syn_recv_sock(struct sock *sk, struct sk_buff *skb,
461 struct request_sock *req,
462 struct dst_entry *dst);
463 extern int tcp_v4_do_rcv(struct sock *sk, struct sk_buff *skb);
464 extern int tcp_v4_connect(struct sock *sk, struct sockaddr *uaddr,
466 extern int tcp_connect(struct sock *sk);
467 extern struct sk_buff * tcp_make_synack(struct sock *sk, struct dst_entry *dst,
468 struct request_sock *req,
469 struct tcp_fastopen_cookie *foc);
470 extern int tcp_disconnect(struct sock *sk, int flags);
472 void tcp_connect_init(struct sock *sk);
473 void tcp_finish_connect(struct sock *sk, struct sk_buff *skb);
474 int tcp_send_rcvq(struct sock *sk, struct msghdr *msg, size_t size);
475 void inet_sk_rx_dst_set(struct sock *sk, const struct sk_buff *skb);
477 /* From syncookies.c */
478 extern __u32 syncookie_secret[2][16-4+SHA_DIGEST_WORDS];
479 extern struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb,
480 struct ip_options *opt);
481 #ifdef CONFIG_SYN_COOKIES
482 extern __u32 cookie_v4_init_sequence(struct sock *sk, struct sk_buff *skb,
485 static inline __u32 cookie_v4_init_sequence(struct sock *sk,
493 extern __u32 cookie_init_timestamp(struct request_sock *req);
494 extern bool cookie_check_timestamp(struct tcp_options_received *opt,
495 struct net *net, bool *ecn_ok);
497 /* From net/ipv6/syncookies.c */
498 extern struct sock *cookie_v6_check(struct sock *sk, struct sk_buff *skb);
499 #ifdef CONFIG_SYN_COOKIES
500 extern __u32 cookie_v6_init_sequence(struct sock *sk, const struct sk_buff *skb,
503 static inline __u32 cookie_v6_init_sequence(struct sock *sk,
512 extern void __tcp_push_pending_frames(struct sock *sk, unsigned int cur_mss,
514 extern bool tcp_may_send_now(struct sock *sk);
515 extern int __tcp_retransmit_skb(struct sock *, struct sk_buff *);
516 extern int tcp_retransmit_skb(struct sock *, struct sk_buff *);
517 extern void tcp_retransmit_timer(struct sock *sk);
518 extern void tcp_xmit_retransmit_queue(struct sock *);
519 extern void tcp_simple_retransmit(struct sock *);
520 extern int tcp_trim_head(struct sock *, struct sk_buff *, u32);
521 extern int tcp_fragment(struct sock *, struct sk_buff *, u32, unsigned int);
523 extern void tcp_send_probe0(struct sock *);
524 extern void tcp_send_partial(struct sock *);
525 extern int tcp_write_wakeup(struct sock *);
526 extern void tcp_send_fin(struct sock *sk);
527 extern void tcp_send_active_reset(struct sock *sk, gfp_t priority);
528 extern int tcp_send_synack(struct sock *);
529 extern bool tcp_syn_flood_action(struct sock *sk,
530 const struct sk_buff *skb,
532 extern void tcp_push_one(struct sock *, unsigned int mss_now);
533 extern void tcp_send_ack(struct sock *sk);
534 extern void tcp_send_delayed_ack(struct sock *sk);
535 extern void tcp_send_loss_probe(struct sock *sk);
536 extern bool tcp_schedule_loss_probe(struct sock *sk);
539 extern void tcp_cwnd_application_limited(struct sock *sk);
540 extern void tcp_resume_early_retransmit(struct sock *sk);
541 extern void tcp_rearm_rto(struct sock *sk);
542 extern void tcp_reset(struct sock *sk);
545 extern void tcp_init_xmit_timers(struct sock *);
546 static inline void tcp_clear_xmit_timers(struct sock *sk)
548 inet_csk_clear_xmit_timers(sk);
551 extern unsigned int tcp_sync_mss(struct sock *sk, u32 pmtu);
552 extern unsigned int tcp_current_mss(struct sock *sk);
554 /* Bound MSS / TSO packet size with the half of the window */
555 static inline int tcp_bound_to_half_wnd(struct tcp_sock *tp, int pktsize)
559 /* When peer uses tiny windows, there is no use in packetizing
560 * to sub-MSS pieces for the sake of SWS or making sure there
561 * are enough packets in the pipe for fast recovery.
563 * On the other hand, for extremely large MSS devices, handling
564 * smaller than MSS windows in this way does make sense.
566 if (tp->max_window >= 512)
567 cutoff = (tp->max_window >> 1);
569 cutoff = tp->max_window;
571 if (cutoff && pktsize > cutoff)
572 return max_t(int, cutoff, 68U - tp->tcp_header_len);
578 extern void tcp_get_info(const struct sock *, struct tcp_info *);
580 /* Read 'sendfile()'-style from a TCP socket */
581 typedef int (*sk_read_actor_t)(read_descriptor_t *, struct sk_buff *,
582 unsigned int, size_t);
583 extern int tcp_read_sock(struct sock *sk, read_descriptor_t *desc,
584 sk_read_actor_t recv_actor);
586 extern void tcp_initialize_rcv_mss(struct sock *sk);
588 extern int tcp_mtu_to_mss(struct sock *sk, int pmtu);
589 extern int tcp_mss_to_mtu(struct sock *sk, int mss);
590 extern void tcp_mtup_init(struct sock *sk);
591 extern void tcp_init_buffer_space(struct sock *sk);
593 static inline void tcp_bound_rto(const struct sock *sk)
595 if (inet_csk(sk)->icsk_rto > TCP_RTO_MAX)
596 inet_csk(sk)->icsk_rto = TCP_RTO_MAX;
599 static inline u32 __tcp_set_rto(const struct tcp_sock *tp)
601 return (tp->srtt >> 3) + tp->rttvar;
604 extern void tcp_set_rto(struct sock *sk);
606 static inline void __tcp_fast_path_on(struct tcp_sock *tp, u32 snd_wnd)
608 tp->pred_flags = htonl((tp->tcp_header_len << 26) |
609 ntohl(TCP_FLAG_ACK) |
613 static inline void tcp_fast_path_on(struct tcp_sock *tp)
615 __tcp_fast_path_on(tp, tp->snd_wnd >> tp->rx_opt.snd_wscale);
618 static inline void tcp_fast_path_check(struct sock *sk)
620 struct tcp_sock *tp = tcp_sk(sk);
622 if (skb_queue_empty(&tp->out_of_order_queue) &&
624 atomic_read(&sk->sk_rmem_alloc) < sk->sk_rcvbuf &&
626 tcp_fast_path_on(tp);
629 /* Compute the actual rto_min value */
630 static inline u32 tcp_rto_min(struct sock *sk)
632 const struct dst_entry *dst = __sk_dst_get(sk);
633 u32 rto_min = TCP_RTO_MIN;
635 if (dst && dst_metric_locked(dst, RTAX_RTO_MIN))
636 rto_min = dst_metric_rtt(dst, RTAX_RTO_MIN);
640 /* Compute the actual receive window we are currently advertising.
641 * Rcv_nxt can be after the window if our peer push more data
642 * than the offered window.
644 static inline u32 tcp_receive_window(const struct tcp_sock *tp)
646 s32 win = tp->rcv_wup + tp->rcv_wnd - tp->rcv_nxt;
653 /* Choose a new window, without checks for shrinking, and without
654 * scaling applied to the result. The caller does these things
655 * if necessary. This is a "raw" window selection.
657 extern u32 __tcp_select_window(struct sock *sk);
659 void tcp_send_window_probe(struct sock *sk);
661 /* TCP timestamps are only 32-bits, this causes a slight
662 * complication on 64-bit systems since we store a snapshot
663 * of jiffies in the buffer control blocks below. We decided
664 * to use only the low 32-bits of jiffies and hide the ugly
665 * casts with the following macro.
667 #define tcp_time_stamp ((__u32)(jiffies))
669 #define tcp_flag_byte(th) (((u_int8_t *)th)[13])
671 #define TCPHDR_FIN 0x01
672 #define TCPHDR_SYN 0x02
673 #define TCPHDR_RST 0x04
674 #define TCPHDR_PSH 0x08
675 #define TCPHDR_ACK 0x10
676 #define TCPHDR_URG 0x20
677 #define TCPHDR_ECE 0x40
678 #define TCPHDR_CWR 0x80
680 /* This is what the send packet queuing engine uses to pass
681 * TCP per-packet control information to the transmission code.
682 * We also store the host-order sequence numbers in here too.
683 * This is 44 bytes if IPV6 is enabled.
684 * If this grows please adjust skbuff.h:skbuff->cb[xxx] size appropriately.
688 struct inet_skb_parm h4;
689 #if IS_ENABLED(CONFIG_IPV6)
690 struct inet6_skb_parm h6;
692 } header; /* For incoming frames */
693 __u32 seq; /* Starting sequence number */
694 __u32 end_seq; /* SEQ + FIN + SYN + datalen */
695 __u32 when; /* used to compute rtt's */
696 __u8 tcp_flags; /* TCP header flags. (tcp[13]) */
698 __u8 sacked; /* State flags for SACK/FACK. */
699 #define TCPCB_SACKED_ACKED 0x01 /* SKB ACK'd by a SACK block */
700 #define TCPCB_SACKED_RETRANS 0x02 /* SKB retransmitted */
701 #define TCPCB_LOST 0x04 /* SKB is lost */
702 #define TCPCB_TAGBITS 0x07 /* All tag bits */
703 #define TCPCB_EVER_RETRANS 0x80 /* Ever retransmitted frame */
704 #define TCPCB_RETRANS (TCPCB_SACKED_RETRANS|TCPCB_EVER_RETRANS)
706 __u8 ip_dsfield; /* IPv4 tos or IPv6 dsfield */
708 __u32 ack_seq; /* Sequence number ACK'd */
711 #define TCP_SKB_CB(__skb) ((struct tcp_skb_cb *)&((__skb)->cb[0]))
713 /* RFC3168 : 6.1.1 SYN packets must not have ECT/ECN bits set
715 * If we receive a SYN packet with these bits set, it means a network is
716 * playing bad games with TOS bits. In order to avoid possible false congestion
717 * notifications, we disable TCP ECN negociation.
720 TCP_ECN_create_request(struct request_sock *req, const struct sk_buff *skb,
723 const struct tcphdr *th = tcp_hdr(skb);
725 if (net->ipv4.sysctl_tcp_ecn && th->ece && th->cwr &&
726 INET_ECN_is_not_ect(TCP_SKB_CB(skb)->ip_dsfield))
727 inet_rsk(req)->ecn_ok = 1;
730 /* Due to TSO, an SKB can be composed of multiple actual
731 * packets. To keep these tracked properly, we use this.
733 static inline int tcp_skb_pcount(const struct sk_buff *skb)
735 return skb_shinfo(skb)->gso_segs;
738 /* This is valid iff tcp_skb_pcount() > 1. */
739 static inline int tcp_skb_mss(const struct sk_buff *skb)
741 return skb_shinfo(skb)->gso_size;
744 /* Events passed to congestion control interface */
746 CA_EVENT_TX_START, /* first transmit when no packets in flight */
747 CA_EVENT_CWND_RESTART, /* congestion window restart */
748 CA_EVENT_COMPLETE_CWR, /* end of congestion recovery */
749 CA_EVENT_LOSS, /* loss timeout */
750 CA_EVENT_FAST_ACK, /* in sequence ack */
751 CA_EVENT_SLOW_ACK, /* other ack */
755 * Interface for adding new TCP congestion control handlers
757 #define TCP_CA_NAME_MAX 16
758 #define TCP_CA_MAX 128
759 #define TCP_CA_BUF_MAX (TCP_CA_NAME_MAX*TCP_CA_MAX)
761 #define TCP_CONG_NON_RESTRICTED 0x1
762 #define TCP_CONG_RTT_STAMP 0x2
764 struct tcp_congestion_ops {
765 struct list_head list;
768 /* initialize private data (optional) */
769 void (*init)(struct sock *sk);
770 /* cleanup private data (optional) */
771 void (*release)(struct sock *sk);
773 /* return slow start threshold (required) */
774 u32 (*ssthresh)(struct sock *sk);
775 /* lower bound for congestion window (optional) */
776 u32 (*min_cwnd)(const struct sock *sk);
777 /* do new cwnd calculation (required) */
778 void (*cong_avoid)(struct sock *sk, u32 ack, u32 in_flight);
779 /* call before changing ca_state (optional) */
780 void (*set_state)(struct sock *sk, u8 new_state);
781 /* call when cwnd event occurs (optional) */
782 void (*cwnd_event)(struct sock *sk, enum tcp_ca_event ev);
783 /* new value of cwnd after loss (optional) */
784 u32 (*undo_cwnd)(struct sock *sk);
785 /* hook for packet ack accounting (optional) */
786 void (*pkts_acked)(struct sock *sk, u32 num_acked, s32 rtt_us);
787 /* get info for inet_diag (optional) */
788 void (*get_info)(struct sock *sk, u32 ext, struct sk_buff *skb);
790 char name[TCP_CA_NAME_MAX];
791 struct module *owner;
794 extern int tcp_register_congestion_control(struct tcp_congestion_ops *type);
795 extern void tcp_unregister_congestion_control(struct tcp_congestion_ops *type);
797 extern void tcp_init_congestion_control(struct sock *sk);
798 extern void tcp_cleanup_congestion_control(struct sock *sk);
799 extern int tcp_set_default_congestion_control(const char *name);
800 extern void tcp_get_default_congestion_control(char *name);
801 extern void tcp_get_available_congestion_control(char *buf, size_t len);
802 extern void tcp_get_allowed_congestion_control(char *buf, size_t len);
803 extern int tcp_set_allowed_congestion_control(char *allowed);
804 extern int tcp_set_congestion_control(struct sock *sk, const char *name);
805 extern void tcp_slow_start(struct tcp_sock *tp);
806 extern void tcp_cong_avoid_ai(struct tcp_sock *tp, u32 w);
808 extern struct tcp_congestion_ops tcp_init_congestion_ops;
809 extern u32 tcp_reno_ssthresh(struct sock *sk);
810 extern void tcp_reno_cong_avoid(struct sock *sk, u32 ack, u32 in_flight);
811 extern u32 tcp_reno_min_cwnd(const struct sock *sk);
812 extern struct tcp_congestion_ops tcp_reno;
814 static inline void tcp_set_ca_state(struct sock *sk, const u8 ca_state)
816 struct inet_connection_sock *icsk = inet_csk(sk);
818 if (icsk->icsk_ca_ops->set_state)
819 icsk->icsk_ca_ops->set_state(sk, ca_state);
820 icsk->icsk_ca_state = ca_state;
823 static inline void tcp_ca_event(struct sock *sk, const enum tcp_ca_event event)
825 const struct inet_connection_sock *icsk = inet_csk(sk);
827 if (icsk->icsk_ca_ops->cwnd_event)
828 icsk->icsk_ca_ops->cwnd_event(sk, event);
831 /* These functions determine how the current flow behaves in respect of SACK
832 * handling. SACK is negotiated with the peer, and therefore it can vary
833 * between different flows.
835 * tcp_is_sack - SACK enabled
836 * tcp_is_reno - No SACK
837 * tcp_is_fack - FACK enabled, implies SACK enabled
839 static inline int tcp_is_sack(const struct tcp_sock *tp)
841 return tp->rx_opt.sack_ok;
844 static inline bool tcp_is_reno(const struct tcp_sock *tp)
846 return !tcp_is_sack(tp);
849 static inline bool tcp_is_fack(const struct tcp_sock *tp)
851 return tp->rx_opt.sack_ok & TCP_FACK_ENABLED;
854 static inline void tcp_enable_fack(struct tcp_sock *tp)
856 tp->rx_opt.sack_ok |= TCP_FACK_ENABLED;
859 /* TCP early-retransmit (ER) is similar to but more conservative than
860 * the thin-dupack feature. Enable ER only if thin-dupack is disabled.
862 static inline void tcp_enable_early_retrans(struct tcp_sock *tp)
864 tp->do_early_retrans = sysctl_tcp_early_retrans &&
865 sysctl_tcp_early_retrans < 4 && !sysctl_tcp_thin_dupack &&
866 sysctl_tcp_reordering == 3;
869 static inline void tcp_disable_early_retrans(struct tcp_sock *tp)
871 tp->do_early_retrans = 0;
874 static inline unsigned int tcp_left_out(const struct tcp_sock *tp)
876 return tp->sacked_out + tp->lost_out;
879 /* This determines how many packets are "in the network" to the best
880 * of our knowledge. In many cases it is conservative, but where
881 * detailed information is available from the receiver (via SACK
882 * blocks etc.) we can make more aggressive calculations.
884 * Use this for decisions involving congestion control, use just
885 * tp->packets_out to determine if the send queue is empty or not.
887 * Read this equation as:
889 * "Packets sent once on transmission queue" MINUS
890 * "Packets left network, but not honestly ACKed yet" PLUS
891 * "Packets fast retransmitted"
893 static inline unsigned int tcp_packets_in_flight(const struct tcp_sock *tp)
895 return tp->packets_out - tcp_left_out(tp) + tp->retrans_out;
898 #define TCP_INFINITE_SSTHRESH 0x7fffffff
900 static inline bool tcp_in_initial_slowstart(const struct tcp_sock *tp)
902 return tp->snd_ssthresh >= TCP_INFINITE_SSTHRESH;
905 static inline bool tcp_in_cwnd_reduction(const struct sock *sk)
907 return (TCPF_CA_CWR | TCPF_CA_Recovery) &
908 (1 << inet_csk(sk)->icsk_ca_state);
911 /* If cwnd > ssthresh, we may raise ssthresh to be half-way to cwnd.
912 * The exception is cwnd reduction phase, when cwnd is decreasing towards
915 static inline __u32 tcp_current_ssthresh(const struct sock *sk)
917 const struct tcp_sock *tp = tcp_sk(sk);
919 if (tcp_in_cwnd_reduction(sk))
920 return tp->snd_ssthresh;
922 return max(tp->snd_ssthresh,
923 ((tp->snd_cwnd >> 1) +
924 (tp->snd_cwnd >> 2)));
927 /* Use define here intentionally to get WARN_ON location shown at the caller */
928 #define tcp_verify_left_out(tp) WARN_ON(tcp_left_out(tp) > tp->packets_out)
930 extern void tcp_enter_cwr(struct sock *sk, const int set_ssthresh);
931 extern __u32 tcp_init_cwnd(const struct tcp_sock *tp, const struct dst_entry *dst);
933 /* The maximum number of MSS of available cwnd for which TSO defers
934 * sending if not using sysctl_tcp_tso_win_divisor.
936 static inline __u32 tcp_max_tso_deferred_mss(const struct tcp_sock *tp)
941 /* Slow start with delack produces 3 packets of burst, so that
942 * it is safe "de facto". This will be the default - same as
943 * the default reordering threshold - but if reordering increases,
944 * we must be able to allow cwnd to burst at least this much in order
945 * to not pull it back when holes are filled.
947 static __inline__ __u32 tcp_max_burst(const struct tcp_sock *tp)
949 return tp->reordering;
952 /* Returns end sequence number of the receiver's advertised window */
953 static inline u32 tcp_wnd_end(const struct tcp_sock *tp)
955 return tp->snd_una + tp->snd_wnd;
957 extern bool tcp_is_cwnd_limited(const struct sock *sk, u32 in_flight);
959 static inline void tcp_minshall_update(struct tcp_sock *tp, unsigned int mss,
960 const struct sk_buff *skb)
963 tp->snd_sml = TCP_SKB_CB(skb)->end_seq;
966 static inline void tcp_check_probe_timer(struct sock *sk)
968 const struct tcp_sock *tp = tcp_sk(sk);
969 const struct inet_connection_sock *icsk = inet_csk(sk);
971 if (!tp->packets_out && !icsk->icsk_pending)
972 inet_csk_reset_xmit_timer(sk, ICSK_TIME_PROBE0,
973 icsk->icsk_rto, TCP_RTO_MAX);
976 static inline void tcp_init_wl(struct tcp_sock *tp, u32 seq)
981 static inline void tcp_update_wl(struct tcp_sock *tp, u32 seq)
987 * Calculate(/check) TCP checksum
989 static inline __sum16 tcp_v4_check(int len, __be32 saddr,
990 __be32 daddr, __wsum base)
992 return csum_tcpudp_magic(saddr,daddr,len,IPPROTO_TCP,base);
995 static inline __sum16 __tcp_checksum_complete(struct sk_buff *skb)
997 return __skb_checksum_complete(skb);
1000 static inline bool tcp_checksum_complete(struct sk_buff *skb)
1002 return !skb_csum_unnecessary(skb) &&
1003 __tcp_checksum_complete(skb);
1006 /* Prequeue for VJ style copy to user, combined with checksumming. */
1008 static inline void tcp_prequeue_init(struct tcp_sock *tp)
1010 tp->ucopy.task = NULL;
1012 tp->ucopy.memory = 0;
1013 skb_queue_head_init(&tp->ucopy.prequeue);
1014 #ifdef CONFIG_NET_DMA
1015 tp->ucopy.dma_chan = NULL;
1016 tp->ucopy.wakeup = 0;
1017 tp->ucopy.pinned_list = NULL;
1018 tp->ucopy.dma_cookie = 0;
1022 extern bool tcp_prequeue(struct sock *sk, struct sk_buff *skb);
1027 static const char *statename[]={
1028 "Unused","Established","Syn Sent","Syn Recv",
1029 "Fin Wait 1","Fin Wait 2","Time Wait", "Close",
1030 "Close Wait","Last ACK","Listen","Closing"
1033 extern void tcp_set_state(struct sock *sk, int state);
1035 extern void tcp_done(struct sock *sk);
1037 static inline void tcp_sack_reset(struct tcp_options_received *rx_opt)
1040 rx_opt->num_sacks = 0;
1043 extern u32 tcp_default_init_rwnd(u32 mss);
1045 /* Determine a window scaling and initial window to offer. */
1046 extern void tcp_select_initial_window(int __space, __u32 mss,
1047 __u32 *rcv_wnd, __u32 *window_clamp,
1048 int wscale_ok, __u8 *rcv_wscale,
1049 __u32 init_rcv_wnd);
1051 static inline int tcp_win_from_space(int space)
1053 return sysctl_tcp_adv_win_scale<=0 ?
1054 (space>>(-sysctl_tcp_adv_win_scale)) :
1055 space - (space>>sysctl_tcp_adv_win_scale);
1058 /* Note: caller must be prepared to deal with negative returns */
1059 static inline int tcp_space(const struct sock *sk)
1061 return tcp_win_from_space(sk->sk_rcvbuf -
1062 atomic_read(&sk->sk_rmem_alloc));
1065 static inline int tcp_full_space(const struct sock *sk)
1067 return tcp_win_from_space(sk->sk_rcvbuf);
1070 static inline void tcp_openreq_init(struct request_sock *req,
1071 struct tcp_options_received *rx_opt,
1072 struct sk_buff *skb)
1074 struct inet_request_sock *ireq = inet_rsk(req);
1076 req->rcv_wnd = 0; /* So that tcp_send_synack() knows! */
1078 tcp_rsk(req)->rcv_isn = TCP_SKB_CB(skb)->seq;
1079 tcp_rsk(req)->rcv_nxt = TCP_SKB_CB(skb)->seq + 1;
1080 tcp_rsk(req)->snt_synack = 0;
1081 req->mss = rx_opt->mss_clamp;
1082 req->ts_recent = rx_opt->saw_tstamp ? rx_opt->rcv_tsval : 0;
1083 ireq->tstamp_ok = rx_opt->tstamp_ok;
1084 ireq->sack_ok = rx_opt->sack_ok;
1085 ireq->snd_wscale = rx_opt->snd_wscale;
1086 ireq->wscale_ok = rx_opt->wscale_ok;
1089 ireq->rmt_port = tcp_hdr(skb)->source;
1090 ireq->loc_port = tcp_hdr(skb)->dest;
1093 extern void tcp_enter_memory_pressure(struct sock *sk);
1095 static inline int keepalive_intvl_when(const struct tcp_sock *tp)
1097 return tp->keepalive_intvl ? : sysctl_tcp_keepalive_intvl;
1100 static inline int keepalive_time_when(const struct tcp_sock *tp)
1102 return tp->keepalive_time ? : sysctl_tcp_keepalive_time;
1105 static inline int keepalive_probes(const struct tcp_sock *tp)
1107 return tp->keepalive_probes ? : sysctl_tcp_keepalive_probes;
1110 static inline u32 keepalive_time_elapsed(const struct tcp_sock *tp)
1112 const struct inet_connection_sock *icsk = &tp->inet_conn;
1114 return min_t(u32, tcp_time_stamp - icsk->icsk_ack.lrcvtime,
1115 tcp_time_stamp - tp->rcv_tstamp);
1118 static inline int tcp_fin_time(const struct sock *sk)
1120 int fin_timeout = tcp_sk(sk)->linger2 ? : sysctl_tcp_fin_timeout;
1121 const int rto = inet_csk(sk)->icsk_rto;
1123 if (fin_timeout < (rto << 2) - (rto >> 1))
1124 fin_timeout = (rto << 2) - (rto >> 1);
1129 static inline bool tcp_paws_check(const struct tcp_options_received *rx_opt,
1132 if ((s32)(rx_opt->ts_recent - rx_opt->rcv_tsval) <= paws_win)
1134 if (unlikely(get_seconds() >= rx_opt->ts_recent_stamp + TCP_PAWS_24DAYS))
1137 * Some OSes send SYN and SYNACK messages with tsval=0 tsecr=0,
1138 * then following tcp messages have valid values. Ignore 0 value,
1139 * or else 'negative' tsval might forbid us to accept their packets.
1141 if (!rx_opt->ts_recent)
1146 static inline bool tcp_paws_reject(const struct tcp_options_received *rx_opt,
1149 if (tcp_paws_check(rx_opt, 0))
1152 /* RST segments are not recommended to carry timestamp,
1153 and, if they do, it is recommended to ignore PAWS because
1154 "their cleanup function should take precedence over timestamps."
1155 Certainly, it is mistake. It is necessary to understand the reasons
1156 of this constraint to relax it: if peer reboots, clock may go
1157 out-of-sync and half-open connections will not be reset.
1158 Actually, the problem would be not existing if all
1159 the implementations followed draft about maintaining clock
1160 via reboots. Linux-2.2 DOES NOT!
1162 However, we can relax time bounds for RST segments to MSL.
1164 if (rst && get_seconds() >= rx_opt->ts_recent_stamp + TCP_PAWS_MSL)
1169 static inline void tcp_mib_init(struct net *net)
1172 TCP_ADD_STATS_USER(net, TCP_MIB_RTOALGORITHM, 1);
1173 TCP_ADD_STATS_USER(net, TCP_MIB_RTOMIN, TCP_RTO_MIN*1000/HZ);
1174 TCP_ADD_STATS_USER(net, TCP_MIB_RTOMAX, TCP_RTO_MAX*1000/HZ);
1175 TCP_ADD_STATS_USER(net, TCP_MIB_MAXCONN, -1);
1179 static inline void tcp_clear_retrans_hints_partial(struct tcp_sock *tp)
1181 tp->lost_skb_hint = NULL;
1184 static inline void tcp_clear_all_retrans_hints(struct tcp_sock *tp)
1186 tcp_clear_retrans_hints_partial(tp);
1187 tp->retransmit_skb_hint = NULL;
1193 union tcp_md5_addr {
1195 #if IS_ENABLED(CONFIG_IPV6)
1200 /* - key database */
1201 struct tcp_md5sig_key {
1202 struct hlist_node node;
1204 u8 family; /* AF_INET or AF_INET6 */
1205 union tcp_md5_addr addr;
1206 u8 key[TCP_MD5SIG_MAXKEYLEN];
1207 struct rcu_head rcu;
1211 struct tcp_md5sig_info {
1212 struct hlist_head head;
1213 struct rcu_head rcu;
1216 /* - pseudo header */
1217 struct tcp4_pseudohdr {
1225 struct tcp6_pseudohdr {
1226 struct in6_addr saddr;
1227 struct in6_addr daddr;
1229 __be32 protocol; /* including padding */
1232 union tcp_md5sum_block {
1233 struct tcp4_pseudohdr ip4;
1234 #if IS_ENABLED(CONFIG_IPV6)
1235 struct tcp6_pseudohdr ip6;
1239 /* - pool: digest algorithm, hash description and scratch buffer */
1240 struct tcp_md5sig_pool {
1241 struct hash_desc md5_desc;
1242 union tcp_md5sum_block md5_blk;
1246 extern int tcp_v4_md5_hash_skb(char *md5_hash, struct tcp_md5sig_key *key,
1247 const struct sock *sk,
1248 const struct request_sock *req,
1249 const struct sk_buff *skb);
1250 extern int tcp_md5_do_add(struct sock *sk, const union tcp_md5_addr *addr,
1251 int family, const u8 *newkey,
1252 u8 newkeylen, gfp_t gfp);
1253 extern int tcp_md5_do_del(struct sock *sk, const union tcp_md5_addr *addr,
1255 extern struct tcp_md5sig_key *tcp_v4_md5_lookup(struct sock *sk,
1256 struct sock *addr_sk);
1258 #ifdef CONFIG_TCP_MD5SIG
1259 extern struct tcp_md5sig_key *tcp_md5_do_lookup(struct sock *sk,
1260 const union tcp_md5_addr *addr, int family);
1261 #define tcp_twsk_md5_key(twsk) ((twsk)->tw_md5_key)
1263 static inline struct tcp_md5sig_key *tcp_md5_do_lookup(struct sock *sk,
1264 const union tcp_md5_addr *addr,
1269 #define tcp_twsk_md5_key(twsk) NULL
1272 extern bool tcp_alloc_md5sig_pool(void);
1274 extern struct tcp_md5sig_pool *tcp_get_md5sig_pool(void);
1275 static inline void tcp_put_md5sig_pool(void)
1280 extern int tcp_md5_hash_header(struct tcp_md5sig_pool *, const struct tcphdr *);
1281 extern int tcp_md5_hash_skb_data(struct tcp_md5sig_pool *, const struct sk_buff *,
1282 unsigned int header_len);
1283 extern int tcp_md5_hash_key(struct tcp_md5sig_pool *hp,
1284 const struct tcp_md5sig_key *key);
1286 /* From tcp_fastopen.c */
1287 extern void tcp_fastopen_cache_get(struct sock *sk, u16 *mss,
1288 struct tcp_fastopen_cookie *cookie,
1289 int *syn_loss, unsigned long *last_syn_loss);
1290 extern void tcp_fastopen_cache_set(struct sock *sk, u16 mss,
1291 struct tcp_fastopen_cookie *cookie,
1293 struct tcp_fastopen_request {
1294 /* Fast Open cookie. Size 0 means a cookie request */
1295 struct tcp_fastopen_cookie cookie;
1296 struct msghdr *data; /* data in MSG_FASTOPEN */
1297 u16 copied; /* queued in tcp_connect() */
1299 void tcp_free_fastopen_req(struct tcp_sock *tp);
1301 extern struct tcp_fastopen_context __rcu *tcp_fastopen_ctx;
1302 int tcp_fastopen_reset_cipher(void *key, unsigned int len);
1303 void tcp_fastopen_cookie_gen(__be32 addr, struct tcp_fastopen_cookie *foc);
1305 #define TCP_FASTOPEN_KEY_LENGTH 16
1307 /* Fastopen key context */
1308 struct tcp_fastopen_context {
1309 struct crypto_cipher *tfm;
1310 __u8 key[TCP_FASTOPEN_KEY_LENGTH];
1311 struct rcu_head rcu;
1314 /* write queue abstraction */
1315 static inline void tcp_write_queue_purge(struct sock *sk)
1317 struct sk_buff *skb;
1319 while ((skb = __skb_dequeue(&sk->sk_write_queue)) != NULL)
1320 sk_wmem_free_skb(sk, skb);
1322 tcp_clear_all_retrans_hints(tcp_sk(sk));
1325 static inline struct sk_buff *tcp_write_queue_head(const struct sock *sk)
1327 return skb_peek(&sk->sk_write_queue);
1330 static inline struct sk_buff *tcp_write_queue_tail(const struct sock *sk)
1332 return skb_peek_tail(&sk->sk_write_queue);
1335 static inline struct sk_buff *tcp_write_queue_next(const struct sock *sk,
1336 const struct sk_buff *skb)
1338 return skb_queue_next(&sk->sk_write_queue, skb);
1341 static inline struct sk_buff *tcp_write_queue_prev(const struct sock *sk,
1342 const struct sk_buff *skb)
1344 return skb_queue_prev(&sk->sk_write_queue, skb);
1347 #define tcp_for_write_queue(skb, sk) \
1348 skb_queue_walk(&(sk)->sk_write_queue, skb)
1350 #define tcp_for_write_queue_from(skb, sk) \
1351 skb_queue_walk_from(&(sk)->sk_write_queue, skb)
1353 #define tcp_for_write_queue_from_safe(skb, tmp, sk) \
1354 skb_queue_walk_from_safe(&(sk)->sk_write_queue, skb, tmp)
1356 static inline struct sk_buff *tcp_send_head(const struct sock *sk)
1358 return sk->sk_send_head;
1361 static inline bool tcp_skb_is_last(const struct sock *sk,
1362 const struct sk_buff *skb)
1364 return skb_queue_is_last(&sk->sk_write_queue, skb);
1367 static inline void tcp_advance_send_head(struct sock *sk, const struct sk_buff *skb)
1369 if (tcp_skb_is_last(sk, skb))
1370 sk->sk_send_head = NULL;
1372 sk->sk_send_head = tcp_write_queue_next(sk, skb);
1375 static inline void tcp_check_send_head(struct sock *sk, struct sk_buff *skb_unlinked)
1377 if (sk->sk_send_head == skb_unlinked)
1378 sk->sk_send_head = NULL;
1381 static inline void tcp_init_send_head(struct sock *sk)
1383 sk->sk_send_head = NULL;
1386 static inline void __tcp_add_write_queue_tail(struct sock *sk, struct sk_buff *skb)
1388 __skb_queue_tail(&sk->sk_write_queue, skb);
1391 static inline void tcp_add_write_queue_tail(struct sock *sk, struct sk_buff *skb)
1393 __tcp_add_write_queue_tail(sk, skb);
1395 /* Queue it, remembering where we must start sending. */
1396 if (sk->sk_send_head == NULL) {
1397 sk->sk_send_head = skb;
1399 if (tcp_sk(sk)->highest_sack == NULL)
1400 tcp_sk(sk)->highest_sack = skb;
1404 static inline void __tcp_add_write_queue_head(struct sock *sk, struct sk_buff *skb)
1406 __skb_queue_head(&sk->sk_write_queue, skb);
1409 /* Insert buff after skb on the write queue of sk. */
1410 static inline void tcp_insert_write_queue_after(struct sk_buff *skb,
1411 struct sk_buff *buff,
1414 __skb_queue_after(&sk->sk_write_queue, skb, buff);
1417 /* Insert new before skb on the write queue of sk. */
1418 static inline void tcp_insert_write_queue_before(struct sk_buff *new,
1419 struct sk_buff *skb,
1422 __skb_queue_before(&sk->sk_write_queue, skb, new);
1424 if (sk->sk_send_head == skb)
1425 sk->sk_send_head = new;
1428 static inline void tcp_unlink_write_queue(struct sk_buff *skb, struct sock *sk)
1430 __skb_unlink(skb, &sk->sk_write_queue);
1433 static inline bool tcp_write_queue_empty(struct sock *sk)
1435 return skb_queue_empty(&sk->sk_write_queue);
1438 static inline void tcp_push_pending_frames(struct sock *sk)
1440 if (tcp_send_head(sk)) {
1441 struct tcp_sock *tp = tcp_sk(sk);
1443 __tcp_push_pending_frames(sk, tcp_current_mss(sk), tp->nonagle);
1447 /* Start sequence of the skb just after the highest skb with SACKed
1448 * bit, valid only if sacked_out > 0 or when the caller has ensured
1449 * validity by itself.
1451 static inline u32 tcp_highest_sack_seq(struct tcp_sock *tp)
1453 if (!tp->sacked_out)
1456 if (tp->highest_sack == NULL)
1459 return TCP_SKB_CB(tp->highest_sack)->seq;
1462 static inline void tcp_advance_highest_sack(struct sock *sk, struct sk_buff *skb)
1464 tcp_sk(sk)->highest_sack = tcp_skb_is_last(sk, skb) ? NULL :
1465 tcp_write_queue_next(sk, skb);
1468 static inline struct sk_buff *tcp_highest_sack(struct sock *sk)
1470 return tcp_sk(sk)->highest_sack;
1473 static inline void tcp_highest_sack_reset(struct sock *sk)
1475 tcp_sk(sk)->highest_sack = tcp_write_queue_head(sk);
1478 /* Called when old skb is about to be deleted (to be combined with new skb) */
1479 static inline void tcp_highest_sack_combine(struct sock *sk,
1480 struct sk_buff *old,
1481 struct sk_buff *new)
1483 if (tcp_sk(sk)->sacked_out && (old == tcp_sk(sk)->highest_sack))
1484 tcp_sk(sk)->highest_sack = new;
1487 /* Determines whether this is a thin stream (which may suffer from
1488 * increased latency). Used to trigger latency-reducing mechanisms.
1490 static inline bool tcp_stream_is_thin(struct tcp_sock *tp)
1492 return tp->packets_out < 4 && !tcp_in_initial_slowstart(tp);
1496 enum tcp_seq_states {
1497 TCP_SEQ_STATE_LISTENING,
1498 TCP_SEQ_STATE_OPENREQ,
1499 TCP_SEQ_STATE_ESTABLISHED,
1500 TCP_SEQ_STATE_TIME_WAIT,
1503 int tcp_seq_open(struct inode *inode, struct file *file);
1505 struct tcp_seq_afinfo {
1508 const struct file_operations *seq_fops;
1509 struct seq_operations seq_ops;
1512 struct tcp_iter_state {
1513 struct seq_net_private p;
1515 enum tcp_seq_states state;
1516 struct sock *syn_wait_sk;
1517 int bucket, offset, sbucket, num;
1522 extern int tcp_proc_register(struct net *net, struct tcp_seq_afinfo *afinfo);
1523 extern void tcp_proc_unregister(struct net *net, struct tcp_seq_afinfo *afinfo);
1525 extern struct request_sock_ops tcp_request_sock_ops;
1526 extern struct request_sock_ops tcp6_request_sock_ops;
1528 extern void tcp_v4_destroy_sock(struct sock *sk);
1530 extern struct sk_buff *tcp_tso_segment(struct sk_buff *skb,
1531 netdev_features_t features);
1532 extern struct sk_buff **tcp_gro_receive(struct sk_buff **head,
1533 struct sk_buff *skb);
1534 extern int tcp_gro_complete(struct sk_buff *skb);
1536 extern void __tcp_v4_send_check(struct sk_buff *skb, __be32 saddr,
1539 static inline u32 tcp_notsent_lowat(const struct tcp_sock *tp)
1541 return tp->notsent_lowat ?: sysctl_tcp_notsent_lowat;
1544 static inline bool tcp_stream_memory_free(const struct sock *sk)
1546 const struct tcp_sock *tp = tcp_sk(sk);
1547 u32 notsent_bytes = tp->write_seq - tp->snd_nxt;
1549 return notsent_bytes < tcp_notsent_lowat(tp);
1552 #ifdef CONFIG_PROC_FS
1553 extern int tcp4_proc_init(void);
1554 extern void tcp4_proc_exit(void);
1557 /* TCP af-specific functions */
1558 struct tcp_sock_af_ops {
1559 #ifdef CONFIG_TCP_MD5SIG
1560 struct tcp_md5sig_key *(*md5_lookup) (struct sock *sk,
1561 struct sock *addr_sk);
1562 int (*calc_md5_hash) (char *location,
1563 struct tcp_md5sig_key *md5,
1564 const struct sock *sk,
1565 const struct request_sock *req,
1566 const struct sk_buff *skb);
1567 int (*md5_parse) (struct sock *sk,
1568 char __user *optval,
1573 struct tcp_request_sock_ops {
1574 #ifdef CONFIG_TCP_MD5SIG
1575 struct tcp_md5sig_key *(*md5_lookup) (struct sock *sk,
1576 struct request_sock *req);
1577 int (*calc_md5_hash) (char *location,
1578 struct tcp_md5sig_key *md5,
1579 const struct sock *sk,
1580 const struct request_sock *req,
1581 const struct sk_buff *skb);
1585 extern int tcpv4_offload_init(void);
1587 extern void tcp_v4_init(void);
1588 extern void tcp_init(void);