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>
34 #include <linux/ktime.h>
36 #include <net/inet_connection_sock.h>
37 #include <net/inet_timewait_sock.h>
38 #include <net/inet_hashtables.h>
39 #include <net/checksum.h>
40 #include <net/request_sock.h>
44 #include <net/tcp_states.h>
45 #include <net/inet_ecn.h>
48 #include <linux/seq_file.h>
49 #include <linux/memcontrol.h>
51 extern struct inet_hashinfo tcp_hashinfo;
53 extern struct percpu_counter tcp_orphan_count;
54 void tcp_time_wait(struct sock *sk, int state, int timeo);
56 #define MAX_TCP_HEADER (128 + MAX_HEADER)
57 #define MAX_TCP_OPTION_SPACE 40
60 * Never offer a window over 32767 without using window scaling. Some
61 * poor stacks do signed 16bit maths!
63 #define MAX_TCP_WINDOW 32767U
65 /* Minimal accepted MSS. It is (60+60+8) - (20+20). */
66 #define TCP_MIN_MSS 88U
68 /* The least MTU to use for probing */
69 #define TCP_BASE_MSS 512
71 /* After receiving this amount of duplicate ACKs fast retransmit starts. */
72 #define TCP_FASTRETRANS_THRESH 3
74 /* Maximal reordering. */
75 #define TCP_MAX_REORDERING 127
77 /* Maximal number of ACKs sent quickly to accelerate slow-start. */
78 #define TCP_MAX_QUICKACKS 16U
81 #define TCP_URG_VALID 0x0100
82 #define TCP_URG_NOTYET 0x0200
83 #define TCP_URG_READ 0x0400
85 #define TCP_RETR1 3 /*
86 * This is how many retries it does before it
87 * tries to figure out if the gateway is
88 * down. Minimal RFC value is 3; it corresponds
89 * to ~3sec-8min depending on RTO.
92 #define TCP_RETR2 15 /*
93 * This should take at least
94 * 90 minutes to time out.
95 * RFC1122 says that the limit is 100 sec.
96 * 15 is ~13-30min depending on RTO.
99 #define TCP_SYN_RETRIES 6 /* This is how many retries are done
100 * when active opening a connection.
101 * RFC1122 says the minimum retry MUST
102 * be at least 180secs. Nevertheless
103 * this value is corresponding to
104 * 63secs of retransmission with the
105 * current initial RTO.
108 #define TCP_SYNACK_RETRIES 5 /* This is how may retries are done
109 * when passive opening a connection.
110 * This is corresponding to 31secs of
111 * retransmission with the current
115 #define TCP_TIMEWAIT_LEN (60*HZ) /* how long to wait to destroy TIME-WAIT
116 * state, about 60 seconds */
117 #define TCP_FIN_TIMEOUT TCP_TIMEWAIT_LEN
118 /* BSD style FIN_WAIT2 deadlock breaker.
119 * It used to be 3min, new value is 60sec,
120 * to combine FIN-WAIT-2 timeout with
124 #define TCP_DELACK_MAX ((unsigned)(HZ/5)) /* maximal time to delay before sending an ACK */
126 #define TCP_DELACK_MIN ((unsigned)(HZ/25)) /* minimal time to delay before sending an ACK */
127 #define TCP_ATO_MIN ((unsigned)(HZ/25))
129 #define TCP_DELACK_MIN 4U
130 #define TCP_ATO_MIN 4U
132 #define TCP_RTO_MAX ((unsigned)(120*HZ))
133 #define TCP_RTO_MIN ((unsigned)(HZ/5))
134 #define TCP_TIMEOUT_INIT ((unsigned)(1*HZ)) /* RFC6298 2.1 initial RTO value */
135 #define TCP_TIMEOUT_FALLBACK ((unsigned)(3*HZ)) /* RFC 1122 initial RTO value, now
136 * used as a fallback RTO for the
137 * initial data transmission if no
138 * valid RTT sample has been acquired,
139 * most likely due to retrans in 3WHS.
142 #define TCP_RESOURCE_PROBE_INTERVAL ((unsigned)(HZ/2U)) /* Maximal interval between probes
143 * for local resources.
146 #define TCP_KEEPALIVE_TIME (120*60*HZ) /* two hours */
147 #define TCP_KEEPALIVE_PROBES 9 /* Max of 9 keepalive probes */
148 #define TCP_KEEPALIVE_INTVL (75*HZ)
150 #define MAX_TCP_KEEPIDLE 32767
151 #define MAX_TCP_KEEPINTVL 32767
152 #define MAX_TCP_KEEPCNT 127
153 #define MAX_TCP_SYNCNT 127
155 #define TCP_SYNQ_INTERVAL (HZ/5) /* Period of SYNACK timer */
157 #define TCP_PAWS_24DAYS (60 * 60 * 24 * 24)
158 #define TCP_PAWS_MSL 60 /* Per-host timestamps are invalidated
159 * after this time. It should be equal
160 * (or greater than) TCP_TIMEWAIT_LEN
161 * to provide reliability equal to one
162 * provided by timewait state.
164 #define TCP_PAWS_WINDOW 1 /* Replay window for per-host
165 * timestamps. It must be less than
166 * minimal timewait lifetime.
172 #define TCPOPT_NOP 1 /* Padding */
173 #define TCPOPT_EOL 0 /* End of options */
174 #define TCPOPT_MSS 2 /* Segment size negotiating */
175 #define TCPOPT_WINDOW 3 /* Window scaling */
176 #define TCPOPT_SACK_PERM 4 /* SACK Permitted */
177 #define TCPOPT_SACK 5 /* SACK Block */
178 #define TCPOPT_TIMESTAMP 8 /* Better RTT estimations/PAWS */
179 #define TCPOPT_MD5SIG 19 /* MD5 Signature (RFC2385) */
180 #define TCPOPT_EXP 254 /* Experimental */
181 /* Magic number to be after the option value for sharing TCP
182 * experimental options. See draft-ietf-tcpm-experimental-options-00.txt
184 #define TCPOPT_FASTOPEN_MAGIC 0xF989
190 #define TCPOLEN_MSS 4
191 #define TCPOLEN_WINDOW 3
192 #define TCPOLEN_SACK_PERM 2
193 #define TCPOLEN_TIMESTAMP 10
194 #define TCPOLEN_MD5SIG 18
195 #define TCPOLEN_EXP_FASTOPEN_BASE 4
197 /* But this is what stacks really send out. */
198 #define TCPOLEN_TSTAMP_ALIGNED 12
199 #define TCPOLEN_WSCALE_ALIGNED 4
200 #define TCPOLEN_SACKPERM_ALIGNED 4
201 #define TCPOLEN_SACK_BASE 2
202 #define TCPOLEN_SACK_BASE_ALIGNED 4
203 #define TCPOLEN_SACK_PERBLOCK 8
204 #define TCPOLEN_MD5SIG_ALIGNED 20
205 #define TCPOLEN_MSS_ALIGNED 4
207 /* Flags in tp->nonagle */
208 #define TCP_NAGLE_OFF 1 /* Nagle's algo is disabled */
209 #define TCP_NAGLE_CORK 2 /* Socket is corked */
210 #define TCP_NAGLE_PUSH 4 /* Cork is overridden for already queued data */
212 /* TCP thin-stream limits */
213 #define TCP_THIN_LINEAR_RETRIES 6 /* After 6 linear retries, do exp. backoff */
215 /* TCP initial congestion window as per draft-hkchu-tcpm-initcwnd-01 */
216 #define TCP_INIT_CWND 10
218 /* Bit Flags for sysctl_tcp_fastopen */
219 #define TFO_CLIENT_ENABLE 1
220 #define TFO_SERVER_ENABLE 2
221 #define TFO_CLIENT_NO_COOKIE 4 /* Data in SYN w/o cookie option */
223 /* Accept SYN data w/o any cookie option */
224 #define TFO_SERVER_COOKIE_NOT_REQD 0x200
226 /* Force enable TFO on all listeners, i.e., not requiring the
227 * TCP_FASTOPEN socket option. SOCKOPT1/2 determine how to set max_qlen.
229 #define TFO_SERVER_WO_SOCKOPT1 0x400
230 #define TFO_SERVER_WO_SOCKOPT2 0x800
232 extern struct inet_timewait_death_row tcp_death_row;
234 /* sysctl variables for tcp */
235 extern int sysctl_tcp_timestamps;
236 extern int sysctl_tcp_window_scaling;
237 extern int sysctl_tcp_sack;
238 extern int sysctl_tcp_fin_timeout;
239 extern int sysctl_tcp_keepalive_time;
240 extern int sysctl_tcp_keepalive_probes;
241 extern int sysctl_tcp_keepalive_intvl;
242 extern int sysctl_tcp_syn_retries;
243 extern int sysctl_tcp_synack_retries;
244 extern int sysctl_tcp_retries1;
245 extern int sysctl_tcp_retries2;
246 extern int sysctl_tcp_orphan_retries;
247 extern int sysctl_tcp_syncookies;
248 extern int sysctl_tcp_fastopen;
249 extern int sysctl_tcp_retrans_collapse;
250 extern int sysctl_tcp_stdurg;
251 extern int sysctl_tcp_rfc1337;
252 extern int sysctl_tcp_abort_on_overflow;
253 extern int sysctl_tcp_max_orphans;
254 extern int sysctl_tcp_fack;
255 extern int sysctl_tcp_reordering;
256 extern int sysctl_tcp_dsack;
257 extern long sysctl_tcp_mem[3];
258 extern int sysctl_tcp_wmem[3];
259 extern int sysctl_tcp_rmem[3];
260 extern int sysctl_tcp_app_win;
261 extern int sysctl_tcp_adv_win_scale;
262 extern int sysctl_tcp_tw_reuse;
263 extern int sysctl_tcp_frto;
264 extern int sysctl_tcp_low_latency;
265 extern int sysctl_tcp_dma_copybreak;
266 extern int sysctl_tcp_nometrics_save;
267 extern int sysctl_tcp_moderate_rcvbuf;
268 extern int sysctl_tcp_tso_win_divisor;
269 extern int sysctl_tcp_mtu_probing;
270 extern int sysctl_tcp_base_mss;
271 extern int sysctl_tcp_workaround_signed_windows;
272 extern int sysctl_tcp_slow_start_after_idle;
273 extern int sysctl_tcp_thin_linear_timeouts;
274 extern int sysctl_tcp_thin_dupack;
275 extern int sysctl_tcp_early_retrans;
276 extern int sysctl_tcp_limit_output_bytes;
277 extern int sysctl_tcp_challenge_ack_limit;
278 extern unsigned int sysctl_tcp_notsent_lowat;
279 extern int sysctl_tcp_min_tso_segs;
280 extern int sysctl_tcp_autocorking;
282 extern atomic_long_t tcp_memory_allocated;
283 extern struct percpu_counter tcp_sockets_allocated;
284 extern int tcp_memory_pressure;
287 * The next routines deal with comparing 32 bit unsigned ints
288 * and worry about wraparound (automatic with unsigned arithmetic).
291 static inline bool before(__u32 seq1, __u32 seq2)
293 return (__s32)(seq1-seq2) < 0;
295 #define after(seq2, seq1) before(seq1, seq2)
297 /* is s2<=s1<=s3 ? */
298 static inline bool between(__u32 seq1, __u32 seq2, __u32 seq3)
300 return seq3 - seq2 >= seq1 - seq2;
303 static inline bool tcp_out_of_memory(struct sock *sk)
305 if (sk->sk_wmem_queued > SOCK_MIN_SNDBUF &&
306 sk_memory_allocated(sk) > sk_prot_mem_limits(sk, 2))
311 static inline bool tcp_too_many_orphans(struct sock *sk, int shift)
313 struct percpu_counter *ocp = sk->sk_prot->orphan_count;
314 int orphans = percpu_counter_read_positive(ocp);
316 if (orphans << shift > sysctl_tcp_max_orphans) {
317 orphans = percpu_counter_sum_positive(ocp);
318 if (orphans << shift > sysctl_tcp_max_orphans)
324 bool tcp_check_oom(struct sock *sk, int shift);
326 /* syncookies: remember time of last synqueue overflow */
327 static inline void tcp_synq_overflow(struct sock *sk)
329 tcp_sk(sk)->rx_opt.ts_recent_stamp = jiffies;
332 /* syncookies: no recent synqueue overflow on this listening socket? */
333 static inline bool tcp_synq_no_recent_overflow(const struct sock *sk)
335 unsigned long last_overflow = tcp_sk(sk)->rx_opt.ts_recent_stamp;
336 return time_after(jiffies, last_overflow + TCP_TIMEOUT_FALLBACK);
339 extern struct proto tcp_prot;
341 #define TCP_INC_STATS(net, field) SNMP_INC_STATS((net)->mib.tcp_statistics, field)
342 #define TCP_INC_STATS_BH(net, field) SNMP_INC_STATS_BH((net)->mib.tcp_statistics, field)
343 #define TCP_DEC_STATS(net, field) SNMP_DEC_STATS((net)->mib.tcp_statistics, field)
344 #define TCP_ADD_STATS_USER(net, field, val) SNMP_ADD_STATS_USER((net)->mib.tcp_statistics, field, val)
345 #define TCP_ADD_STATS(net, field, val) SNMP_ADD_STATS((net)->mib.tcp_statistics, field, val)
347 void tcp_tasklet_init(void);
349 void tcp_v4_err(struct sk_buff *skb, u32);
351 void tcp_shutdown(struct sock *sk, int how);
353 void tcp_v4_early_demux(struct sk_buff *skb);
354 int tcp_v4_rcv(struct sk_buff *skb);
356 int tcp_v4_tw_remember_stamp(struct inet_timewait_sock *tw);
357 int tcp_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
359 int tcp_sendpage(struct sock *sk, struct page *page, int offset, size_t size,
361 void tcp_release_cb(struct sock *sk);
362 void tcp_wfree(struct sk_buff *skb);
363 void tcp_write_timer_handler(struct sock *sk);
364 void tcp_delack_timer_handler(struct sock *sk);
365 int tcp_ioctl(struct sock *sk, int cmd, unsigned long arg);
366 int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb,
367 const struct tcphdr *th, unsigned int len);
368 void tcp_rcv_established(struct sock *sk, struct sk_buff *skb,
369 const struct tcphdr *th, unsigned int len);
370 void tcp_rcv_space_adjust(struct sock *sk);
371 void tcp_cleanup_rbuf(struct sock *sk, int copied);
372 int tcp_twsk_unique(struct sock *sk, struct sock *sktw, void *twp);
373 void tcp_twsk_destructor(struct sock *sk);
374 ssize_t tcp_splice_read(struct socket *sk, loff_t *ppos,
375 struct pipe_inode_info *pipe, size_t len,
378 static inline void tcp_dec_quickack_mode(struct sock *sk,
379 const unsigned int pkts)
381 struct inet_connection_sock *icsk = inet_csk(sk);
383 if (icsk->icsk_ack.quick) {
384 if (pkts >= icsk->icsk_ack.quick) {
385 icsk->icsk_ack.quick = 0;
386 /* Leaving quickack mode we deflate ATO. */
387 icsk->icsk_ack.ato = TCP_ATO_MIN;
389 icsk->icsk_ack.quick -= pkts;
394 #define TCP_ECN_QUEUE_CWR 2
395 #define TCP_ECN_DEMAND_CWR 4
396 #define TCP_ECN_SEEN 8
406 enum tcp_tw_status tcp_timewait_state_process(struct inet_timewait_sock *tw,
408 const struct tcphdr *th);
409 struct sock *tcp_check_req(struct sock *sk, struct sk_buff *skb,
410 struct request_sock *req, struct request_sock **prev,
412 int tcp_child_process(struct sock *parent, struct sock *child,
413 struct sk_buff *skb);
414 void tcp_enter_loss(struct sock *sk);
415 void tcp_clear_retrans(struct tcp_sock *tp);
416 void tcp_update_metrics(struct sock *sk);
417 void tcp_init_metrics(struct sock *sk);
418 void tcp_metrics_init(void);
419 bool tcp_peer_is_proven(struct request_sock *req, struct dst_entry *dst,
421 bool tcp_remember_stamp(struct sock *sk);
422 bool tcp_tw_remember_stamp(struct inet_timewait_sock *tw);
423 void tcp_fetch_timewait_stamp(struct sock *sk, struct dst_entry *dst);
424 void tcp_disable_fack(struct tcp_sock *tp);
425 void tcp_close(struct sock *sk, long timeout);
426 void tcp_init_sock(struct sock *sk);
427 unsigned int tcp_poll(struct file *file, struct socket *sock,
428 struct poll_table_struct *wait);
429 int tcp_getsockopt(struct sock *sk, int level, int optname,
430 char __user *optval, int __user *optlen);
431 int tcp_setsockopt(struct sock *sk, int level, int optname,
432 char __user *optval, unsigned int optlen);
433 int compat_tcp_getsockopt(struct sock *sk, int level, int optname,
434 char __user *optval, int __user *optlen);
435 int compat_tcp_setsockopt(struct sock *sk, int level, int optname,
436 char __user *optval, unsigned int optlen);
437 void tcp_set_keepalive(struct sock *sk, int val);
438 void tcp_syn_ack_timeout(struct sock *sk, struct request_sock *req);
439 int tcp_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
440 size_t len, int nonblock, int flags, int *addr_len);
441 void tcp_parse_options(const struct sk_buff *skb,
442 struct tcp_options_received *opt_rx,
443 int estab, struct tcp_fastopen_cookie *foc);
444 const u8 *tcp_parse_md5sig_option(const struct tcphdr *th);
447 * TCP v4 functions exported for the inet6 API
450 void tcp_v4_send_check(struct sock *sk, struct sk_buff *skb);
451 int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb);
452 struct sock *tcp_create_openreq_child(struct sock *sk,
453 struct request_sock *req,
454 struct sk_buff *skb);
455 struct sock *tcp_v4_syn_recv_sock(struct sock *sk, struct sk_buff *skb,
456 struct request_sock *req,
457 struct dst_entry *dst);
458 int tcp_v4_do_rcv(struct sock *sk, struct sk_buff *skb);
459 int tcp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len);
460 int tcp_connect(struct sock *sk);
461 struct sk_buff *tcp_make_synack(struct sock *sk, struct dst_entry *dst,
462 struct request_sock *req,
463 struct tcp_fastopen_cookie *foc);
464 int tcp_disconnect(struct sock *sk, int flags);
466 void tcp_finish_connect(struct sock *sk, struct sk_buff *skb);
467 int tcp_send_rcvq(struct sock *sk, struct msghdr *msg, size_t size);
468 void inet_sk_rx_dst_set(struct sock *sk, const struct sk_buff *skb);
470 /* From syncookies.c */
471 int __cookie_v4_check(const struct iphdr *iph, const struct tcphdr *th,
473 struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb,
474 struct ip_options *opt);
475 #ifdef CONFIG_SYN_COOKIES
477 /* Syncookies use a monotonic timer which increments every 60 seconds.
478 * This counter is used both as a hash input and partially encoded into
479 * the cookie value. A cookie is only validated further if the delta
480 * between the current counter value and the encoded one is less than this,
481 * i.e. a sent cookie is valid only at most for 2*60 seconds (or less if
482 * the counter advances immediately after a cookie is generated).
484 #define MAX_SYNCOOKIE_AGE 2
486 static inline u32 tcp_cookie_time(void)
488 u64 val = get_jiffies_64();
490 do_div(val, 60 * HZ);
494 u32 __cookie_v4_init_sequence(const struct iphdr *iph, const struct tcphdr *th,
496 __u32 cookie_v4_init_sequence(struct sock *sk, const struct sk_buff *skb,
500 __u32 cookie_init_timestamp(struct request_sock *req);
501 bool cookie_check_timestamp(struct tcp_options_received *opt, struct net *net,
504 /* From net/ipv6/syncookies.c */
505 int __cookie_v6_check(const struct ipv6hdr *iph, const struct tcphdr *th,
507 struct sock *cookie_v6_check(struct sock *sk, struct sk_buff *skb);
508 #ifdef CONFIG_SYN_COOKIES
509 u32 __cookie_v6_init_sequence(const struct ipv6hdr *iph,
510 const struct tcphdr *th, u16 *mssp);
511 __u32 cookie_v6_init_sequence(struct sock *sk, const struct sk_buff *skb,
516 void __tcp_push_pending_frames(struct sock *sk, unsigned int cur_mss,
518 bool tcp_may_send_now(struct sock *sk);
519 int __tcp_retransmit_skb(struct sock *, struct sk_buff *);
520 int tcp_retransmit_skb(struct sock *, struct sk_buff *);
521 void tcp_retransmit_timer(struct sock *sk);
522 void tcp_xmit_retransmit_queue(struct sock *);
523 void tcp_simple_retransmit(struct sock *);
524 int tcp_trim_head(struct sock *, struct sk_buff *, u32);
525 int tcp_fragment(struct sock *, struct sk_buff *, u32, unsigned int, gfp_t);
527 void tcp_send_probe0(struct sock *);
528 void tcp_send_partial(struct sock *);
529 int tcp_write_wakeup(struct sock *);
530 void tcp_send_fin(struct sock *sk);
531 void tcp_send_active_reset(struct sock *sk, gfp_t priority);
532 int tcp_send_synack(struct sock *);
533 bool tcp_syn_flood_action(struct sock *sk, const struct sk_buff *skb,
535 void tcp_push_one(struct sock *, unsigned int mss_now);
536 void tcp_send_ack(struct sock *sk);
537 void tcp_send_delayed_ack(struct sock *sk);
538 void tcp_send_loss_probe(struct sock *sk);
539 bool tcp_schedule_loss_probe(struct sock *sk);
542 void tcp_resume_early_retransmit(struct sock *sk);
543 void tcp_rearm_rto(struct sock *sk);
544 void tcp_reset(struct sock *sk);
547 void tcp_init_xmit_timers(struct sock *);
548 static inline void tcp_clear_xmit_timers(struct sock *sk)
550 inet_csk_clear_xmit_timers(sk);
553 unsigned int tcp_sync_mss(struct sock *sk, u32 pmtu);
554 unsigned int tcp_current_mss(struct sock *sk);
556 /* Bound MSS / TSO packet size with the half of the window */
557 static inline int tcp_bound_to_half_wnd(struct tcp_sock *tp, int pktsize)
561 /* When peer uses tiny windows, there is no use in packetizing
562 * to sub-MSS pieces for the sake of SWS or making sure there
563 * are enough packets in the pipe for fast recovery.
565 * On the other hand, for extremely large MSS devices, handling
566 * smaller than MSS windows in this way does make sense.
568 if (tp->max_window >= 512)
569 cutoff = (tp->max_window >> 1);
571 cutoff = tp->max_window;
573 if (cutoff && pktsize > cutoff)
574 return max_t(int, cutoff, 68U - tp->tcp_header_len);
580 void tcp_get_info(const struct sock *, struct tcp_info *);
582 /* Read 'sendfile()'-style from a TCP socket */
583 typedef int (*sk_read_actor_t)(read_descriptor_t *, struct sk_buff *,
584 unsigned int, size_t);
585 int tcp_read_sock(struct sock *sk, read_descriptor_t *desc,
586 sk_read_actor_t recv_actor);
588 void tcp_initialize_rcv_mss(struct sock *sk);
590 int tcp_mtu_to_mss(struct sock *sk, int pmtu);
591 int tcp_mss_to_mtu(struct sock *sk, int mss);
592 void tcp_mtup_init(struct sock *sk);
593 void tcp_init_buffer_space(struct sock *sk);
595 static inline void tcp_bound_rto(const struct sock *sk)
597 if (inet_csk(sk)->icsk_rto > TCP_RTO_MAX)
598 inet_csk(sk)->icsk_rto = TCP_RTO_MAX;
601 static inline u32 __tcp_set_rto(const struct tcp_sock *tp)
603 return usecs_to_jiffies((tp->srtt_us >> 3) + tp->rttvar_us);
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 static inline u32 tcp_rto_min_us(struct sock *sk)
642 return jiffies_to_usecs(tcp_rto_min(sk));
645 /* Compute the actual receive window we are currently advertising.
646 * Rcv_nxt can be after the window if our peer push more data
647 * than the offered window.
649 static inline u32 tcp_receive_window(const struct tcp_sock *tp)
651 s32 win = tp->rcv_wup + tp->rcv_wnd - tp->rcv_nxt;
658 /* Choose a new window, without checks for shrinking, and without
659 * scaling applied to the result. The caller does these things
660 * if necessary. This is a "raw" window selection.
662 u32 __tcp_select_window(struct sock *sk);
664 void tcp_send_window_probe(struct sock *sk);
666 /* TCP timestamps are only 32-bits, this causes a slight
667 * complication on 64-bit systems since we store a snapshot
668 * of jiffies in the buffer control blocks below. We decided
669 * to use only the low 32-bits of jiffies and hide the ugly
670 * casts with the following macro.
672 #define tcp_time_stamp ((__u32)(jiffies))
674 #define tcp_flag_byte(th) (((u_int8_t *)th)[13])
676 #define TCPHDR_FIN 0x01
677 #define TCPHDR_SYN 0x02
678 #define TCPHDR_RST 0x04
679 #define TCPHDR_PSH 0x08
680 #define TCPHDR_ACK 0x10
681 #define TCPHDR_URG 0x20
682 #define TCPHDR_ECE 0x40
683 #define TCPHDR_CWR 0x80
685 /* This is what the send packet queuing engine uses to pass
686 * TCP per-packet control information to the transmission code.
687 * We also store the host-order sequence numbers in here too.
688 * This is 44 bytes if IPV6 is enabled.
689 * If this grows please adjust skbuff.h:skbuff->cb[xxx] size appropriately.
693 struct inet_skb_parm h4;
694 #if IS_ENABLED(CONFIG_IPV6)
695 struct inet6_skb_parm h6;
697 } header; /* For incoming frames */
698 __u32 seq; /* Starting sequence number */
699 __u32 end_seq; /* SEQ + FIN + SYN + datalen */
700 __u32 when; /* used to compute rtt's */
701 __u8 tcp_flags; /* TCP header flags. (tcp[13]) */
703 __u8 sacked; /* State flags for SACK/FACK. */
704 #define TCPCB_SACKED_ACKED 0x01 /* SKB ACK'd by a SACK block */
705 #define TCPCB_SACKED_RETRANS 0x02 /* SKB retransmitted */
706 #define TCPCB_LOST 0x04 /* SKB is lost */
707 #define TCPCB_TAGBITS 0x07 /* All tag bits */
708 #define TCPCB_REPAIRED 0x10 /* SKB repaired (no skb_mstamp) */
709 #define TCPCB_EVER_RETRANS 0x80 /* Ever retransmitted frame */
710 #define TCPCB_RETRANS (TCPCB_SACKED_RETRANS|TCPCB_EVER_RETRANS| \
713 __u8 ip_dsfield; /* IPv4 tos or IPv6 dsfield */
715 __u32 ack_seq; /* Sequence number ACK'd */
718 #define TCP_SKB_CB(__skb) ((struct tcp_skb_cb *)&((__skb)->cb[0]))
720 /* RFC3168 : 6.1.1 SYN packets must not have ECT/ECN bits set
722 * If we receive a SYN packet with these bits set, it means a network is
723 * playing bad games with TOS bits. In order to avoid possible false congestion
724 * notifications, we disable TCP ECN negociation.
727 TCP_ECN_create_request(struct request_sock *req, const struct sk_buff *skb,
730 const struct tcphdr *th = tcp_hdr(skb);
732 if (net->ipv4.sysctl_tcp_ecn && th->ece && th->cwr &&
733 INET_ECN_is_not_ect(TCP_SKB_CB(skb)->ip_dsfield))
734 inet_rsk(req)->ecn_ok = 1;
737 /* Due to TSO, an SKB can be composed of multiple actual
738 * packets. To keep these tracked properly, we use this.
740 static inline int tcp_skb_pcount(const struct sk_buff *skb)
742 return skb_shinfo(skb)->gso_segs;
745 /* This is valid iff tcp_skb_pcount() > 1. */
746 static inline int tcp_skb_mss(const struct sk_buff *skb)
748 return skb_shinfo(skb)->gso_size;
751 /* Events passed to congestion control interface */
753 CA_EVENT_TX_START, /* first transmit when no packets in flight */
754 CA_EVENT_CWND_RESTART, /* congestion window restart */
755 CA_EVENT_COMPLETE_CWR, /* end of congestion recovery */
756 CA_EVENT_LOSS, /* loss timeout */
757 CA_EVENT_FAST_ACK, /* in sequence ack */
758 CA_EVENT_SLOW_ACK, /* other ack */
762 * Interface for adding new TCP congestion control handlers
764 #define TCP_CA_NAME_MAX 16
765 #define TCP_CA_MAX 128
766 #define TCP_CA_BUF_MAX (TCP_CA_NAME_MAX*TCP_CA_MAX)
768 #define TCP_CONG_NON_RESTRICTED 0x1
770 struct tcp_congestion_ops {
771 struct list_head list;
774 /* initialize private data (optional) */
775 void (*init)(struct sock *sk);
776 /* cleanup private data (optional) */
777 void (*release)(struct sock *sk);
779 /* return slow start threshold (required) */
780 u32 (*ssthresh)(struct sock *sk);
781 /* do new cwnd calculation (required) */
782 void (*cong_avoid)(struct sock *sk, u32 ack, u32 acked);
783 /* call before changing ca_state (optional) */
784 void (*set_state)(struct sock *sk, u8 new_state);
785 /* call when cwnd event occurs (optional) */
786 void (*cwnd_event)(struct sock *sk, enum tcp_ca_event ev);
787 /* new value of cwnd after loss (optional) */
788 u32 (*undo_cwnd)(struct sock *sk);
789 /* hook for packet ack accounting (optional) */
790 void (*pkts_acked)(struct sock *sk, u32 num_acked, s32 rtt_us);
791 /* get info for inet_diag (optional) */
792 void (*get_info)(struct sock *sk, u32 ext, struct sk_buff *skb);
794 char name[TCP_CA_NAME_MAX];
795 struct module *owner;
798 int tcp_register_congestion_control(struct tcp_congestion_ops *type);
799 void tcp_unregister_congestion_control(struct tcp_congestion_ops *type);
801 void tcp_init_congestion_control(struct sock *sk);
802 void tcp_cleanup_congestion_control(struct sock *sk);
803 int tcp_set_default_congestion_control(const char *name);
804 void tcp_get_default_congestion_control(char *name);
805 void tcp_get_available_congestion_control(char *buf, size_t len);
806 void tcp_get_allowed_congestion_control(char *buf, size_t len);
807 int tcp_set_allowed_congestion_control(char *allowed);
808 int tcp_set_congestion_control(struct sock *sk, const char *name);
809 int tcp_slow_start(struct tcp_sock *tp, u32 acked);
810 void tcp_cong_avoid_ai(struct tcp_sock *tp, u32 w);
812 extern struct tcp_congestion_ops tcp_init_congestion_ops;
813 u32 tcp_reno_ssthresh(struct sock *sk);
814 void tcp_reno_cong_avoid(struct sock *sk, u32 ack, u32 acked);
815 extern struct tcp_congestion_ops tcp_reno;
817 static inline void tcp_set_ca_state(struct sock *sk, const u8 ca_state)
819 struct inet_connection_sock *icsk = inet_csk(sk);
821 if (icsk->icsk_ca_ops->set_state)
822 icsk->icsk_ca_ops->set_state(sk, ca_state);
823 icsk->icsk_ca_state = ca_state;
826 static inline void tcp_ca_event(struct sock *sk, const enum tcp_ca_event event)
828 const struct inet_connection_sock *icsk = inet_csk(sk);
830 if (icsk->icsk_ca_ops->cwnd_event)
831 icsk->icsk_ca_ops->cwnd_event(sk, event);
834 /* These functions determine how the current flow behaves in respect of SACK
835 * handling. SACK is negotiated with the peer, and therefore it can vary
836 * between different flows.
838 * tcp_is_sack - SACK enabled
839 * tcp_is_reno - No SACK
840 * tcp_is_fack - FACK enabled, implies SACK enabled
842 static inline int tcp_is_sack(const struct tcp_sock *tp)
844 return tp->rx_opt.sack_ok;
847 static inline bool tcp_is_reno(const struct tcp_sock *tp)
849 return !tcp_is_sack(tp);
852 static inline bool tcp_is_fack(const struct tcp_sock *tp)
854 return tp->rx_opt.sack_ok & TCP_FACK_ENABLED;
857 static inline void tcp_enable_fack(struct tcp_sock *tp)
859 tp->rx_opt.sack_ok |= TCP_FACK_ENABLED;
862 /* TCP early-retransmit (ER) is similar to but more conservative than
863 * the thin-dupack feature. Enable ER only if thin-dupack is disabled.
865 static inline void tcp_enable_early_retrans(struct tcp_sock *tp)
867 tp->do_early_retrans = sysctl_tcp_early_retrans &&
868 sysctl_tcp_early_retrans < 4 && !sysctl_tcp_thin_dupack &&
869 sysctl_tcp_reordering == 3;
872 static inline void tcp_disable_early_retrans(struct tcp_sock *tp)
874 tp->do_early_retrans = 0;
877 static inline unsigned int tcp_left_out(const struct tcp_sock *tp)
879 return tp->sacked_out + tp->lost_out;
882 /* This determines how many packets are "in the network" to the best
883 * of our knowledge. In many cases it is conservative, but where
884 * detailed information is available from the receiver (via SACK
885 * blocks etc.) we can make more aggressive calculations.
887 * Use this for decisions involving congestion control, use just
888 * tp->packets_out to determine if the send queue is empty or not.
890 * Read this equation as:
892 * "Packets sent once on transmission queue" MINUS
893 * "Packets left network, but not honestly ACKed yet" PLUS
894 * "Packets fast retransmitted"
896 static inline unsigned int tcp_packets_in_flight(const struct tcp_sock *tp)
898 return tp->packets_out - tcp_left_out(tp) + tp->retrans_out;
901 #define TCP_INFINITE_SSTHRESH 0x7fffffff
903 static inline bool tcp_in_initial_slowstart(const struct tcp_sock *tp)
905 return tp->snd_ssthresh >= TCP_INFINITE_SSTHRESH;
908 static inline bool tcp_in_cwnd_reduction(const struct sock *sk)
910 return (TCPF_CA_CWR | TCPF_CA_Recovery) &
911 (1 << inet_csk(sk)->icsk_ca_state);
914 /* If cwnd > ssthresh, we may raise ssthresh to be half-way to cwnd.
915 * The exception is cwnd reduction phase, when cwnd is decreasing towards
918 static inline __u32 tcp_current_ssthresh(const struct sock *sk)
920 const struct tcp_sock *tp = tcp_sk(sk);
922 if (tcp_in_cwnd_reduction(sk))
923 return tp->snd_ssthresh;
925 return max(tp->snd_ssthresh,
926 ((tp->snd_cwnd >> 1) +
927 (tp->snd_cwnd >> 2)));
930 /* Use define here intentionally to get WARN_ON location shown at the caller */
931 #define tcp_verify_left_out(tp) WARN_ON(tcp_left_out(tp) > tp->packets_out)
933 void tcp_enter_cwr(struct sock *sk);
934 __u32 tcp_init_cwnd(const struct tcp_sock *tp, const struct dst_entry *dst);
936 /* The maximum number of MSS of available cwnd for which TSO defers
937 * sending if not using sysctl_tcp_tso_win_divisor.
939 static inline __u32 tcp_max_tso_deferred_mss(const struct tcp_sock *tp)
944 /* Slow start with delack produces 3 packets of burst, so that
945 * it is safe "de facto". This will be the default - same as
946 * the default reordering threshold - but if reordering increases,
947 * we must be able to allow cwnd to burst at least this much in order
948 * to not pull it back when holes are filled.
950 static __inline__ __u32 tcp_max_burst(const struct tcp_sock *tp)
952 return tp->reordering;
955 /* Returns end sequence number of the receiver's advertised window */
956 static inline u32 tcp_wnd_end(const struct tcp_sock *tp)
958 return tp->snd_una + tp->snd_wnd;
961 /* We follow the spirit of RFC2861 to validate cwnd but implement a more
962 * flexible approach. The RFC suggests cwnd should not be raised unless
963 * it was fully used previously. And that's exactly what we do in
964 * congestion avoidance mode. But in slow start we allow cwnd to grow
965 * as long as the application has used half the cwnd.
967 * cwnd is 10 (IW10), but application sends 9 frames.
968 * We allow cwnd to reach 18 when all frames are ACKed.
969 * This check is safe because it's as aggressive as slow start which already
970 * risks 100% overshoot. The advantage is that we discourage application to
971 * either send more filler packets or data to artificially blow up the cwnd
972 * usage, and allow application-limited process to probe bw more aggressively.
974 static inline bool tcp_is_cwnd_limited(const struct sock *sk)
976 const struct tcp_sock *tp = tcp_sk(sk);
978 /* If in slow start, ensure cwnd grows to twice what was ACKed. */
979 if (tp->snd_cwnd <= tp->snd_ssthresh)
980 return tp->snd_cwnd < 2 * tp->max_packets_out;
982 return tp->is_cwnd_limited;
985 static inline void tcp_check_probe_timer(struct sock *sk)
987 const struct tcp_sock *tp = tcp_sk(sk);
988 const struct inet_connection_sock *icsk = inet_csk(sk);
990 if (!tp->packets_out && !icsk->icsk_pending)
991 inet_csk_reset_xmit_timer(sk, ICSK_TIME_PROBE0,
992 icsk->icsk_rto, TCP_RTO_MAX);
995 static inline void tcp_init_wl(struct tcp_sock *tp, u32 seq)
1000 static inline void tcp_update_wl(struct tcp_sock *tp, u32 seq)
1006 * Calculate(/check) TCP checksum
1008 static inline __sum16 tcp_v4_check(int len, __be32 saddr,
1009 __be32 daddr, __wsum base)
1011 return csum_tcpudp_magic(saddr,daddr,len,IPPROTO_TCP,base);
1014 static inline __sum16 __tcp_checksum_complete(struct sk_buff *skb)
1016 return __skb_checksum_complete(skb);
1019 static inline bool tcp_checksum_complete(struct sk_buff *skb)
1021 return !skb_csum_unnecessary(skb) &&
1022 __tcp_checksum_complete(skb);
1025 /* Prequeue for VJ style copy to user, combined with checksumming. */
1027 static inline void tcp_prequeue_init(struct tcp_sock *tp)
1029 tp->ucopy.task = NULL;
1031 tp->ucopy.memory = 0;
1032 skb_queue_head_init(&tp->ucopy.prequeue);
1033 #ifdef CONFIG_NET_DMA
1034 tp->ucopy.dma_chan = NULL;
1035 tp->ucopy.wakeup = 0;
1036 tp->ucopy.pinned_list = NULL;
1037 tp->ucopy.dma_cookie = 0;
1041 bool tcp_prequeue(struct sock *sk, struct sk_buff *skb);
1046 static const char *statename[]={
1047 "Unused","Established","Syn Sent","Syn Recv",
1048 "Fin Wait 1","Fin Wait 2","Time Wait", "Close",
1049 "Close Wait","Last ACK","Listen","Closing"
1052 void tcp_set_state(struct sock *sk, int state);
1054 void tcp_done(struct sock *sk);
1056 static inline void tcp_sack_reset(struct tcp_options_received *rx_opt)
1059 rx_opt->num_sacks = 0;
1062 u32 tcp_default_init_rwnd(u32 mss);
1064 /* Determine a window scaling and initial window to offer. */
1065 void tcp_select_initial_window(int __space, __u32 mss, __u32 *rcv_wnd,
1066 __u32 *window_clamp, int wscale_ok,
1067 __u8 *rcv_wscale, __u32 init_rcv_wnd);
1069 static inline int tcp_win_from_space(int space)
1071 return sysctl_tcp_adv_win_scale<=0 ?
1072 (space>>(-sysctl_tcp_adv_win_scale)) :
1073 space - (space>>sysctl_tcp_adv_win_scale);
1076 /* Note: caller must be prepared to deal with negative returns */
1077 static inline int tcp_space(const struct sock *sk)
1079 return tcp_win_from_space(sk->sk_rcvbuf -
1080 atomic_read(&sk->sk_rmem_alloc));
1083 static inline int tcp_full_space(const struct sock *sk)
1085 return tcp_win_from_space(sk->sk_rcvbuf);
1088 static inline void tcp_openreq_init(struct request_sock *req,
1089 struct tcp_options_received *rx_opt,
1090 struct sk_buff *skb, struct sock *sk)
1092 struct inet_request_sock *ireq = inet_rsk(req);
1094 req->rcv_wnd = 0; /* So that tcp_send_synack() knows! */
1096 tcp_rsk(req)->rcv_isn = TCP_SKB_CB(skb)->seq;
1097 tcp_rsk(req)->rcv_nxt = TCP_SKB_CB(skb)->seq + 1;
1098 tcp_rsk(req)->snt_synack = tcp_time_stamp;
1099 req->mss = rx_opt->mss_clamp;
1100 req->ts_recent = rx_opt->saw_tstamp ? rx_opt->rcv_tsval : 0;
1101 ireq->tstamp_ok = rx_opt->tstamp_ok;
1102 ireq->sack_ok = rx_opt->sack_ok;
1103 ireq->snd_wscale = rx_opt->snd_wscale;
1104 ireq->wscale_ok = rx_opt->wscale_ok;
1107 ireq->ir_rmt_port = tcp_hdr(skb)->source;
1108 ireq->ir_num = ntohs(tcp_hdr(skb)->dest);
1109 ireq->ir_mark = inet_request_mark(sk, skb);
1112 extern void tcp_openreq_init_rwin(struct request_sock *req,
1113 struct sock *sk, struct dst_entry *dst);
1115 void tcp_enter_memory_pressure(struct sock *sk);
1117 static inline int keepalive_intvl_when(const struct tcp_sock *tp)
1119 return tp->keepalive_intvl ? : sysctl_tcp_keepalive_intvl;
1122 static inline int keepalive_time_when(const struct tcp_sock *tp)
1124 return tp->keepalive_time ? : sysctl_tcp_keepalive_time;
1127 static inline int keepalive_probes(const struct tcp_sock *tp)
1129 return tp->keepalive_probes ? : sysctl_tcp_keepalive_probes;
1132 static inline u32 keepalive_time_elapsed(const struct tcp_sock *tp)
1134 const struct inet_connection_sock *icsk = &tp->inet_conn;
1136 return min_t(u32, tcp_time_stamp - icsk->icsk_ack.lrcvtime,
1137 tcp_time_stamp - tp->rcv_tstamp);
1140 static inline int tcp_fin_time(const struct sock *sk)
1142 int fin_timeout = tcp_sk(sk)->linger2 ? : sysctl_tcp_fin_timeout;
1143 const int rto = inet_csk(sk)->icsk_rto;
1145 if (fin_timeout < (rto << 2) - (rto >> 1))
1146 fin_timeout = (rto << 2) - (rto >> 1);
1151 static inline bool tcp_paws_check(const struct tcp_options_received *rx_opt,
1154 if ((s32)(rx_opt->ts_recent - rx_opt->rcv_tsval) <= paws_win)
1156 if (unlikely(get_seconds() >= rx_opt->ts_recent_stamp + TCP_PAWS_24DAYS))
1159 * Some OSes send SYN and SYNACK messages with tsval=0 tsecr=0,
1160 * then following tcp messages have valid values. Ignore 0 value,
1161 * or else 'negative' tsval might forbid us to accept their packets.
1163 if (!rx_opt->ts_recent)
1168 static inline bool tcp_paws_reject(const struct tcp_options_received *rx_opt,
1171 if (tcp_paws_check(rx_opt, 0))
1174 /* RST segments are not recommended to carry timestamp,
1175 and, if they do, it is recommended to ignore PAWS because
1176 "their cleanup function should take precedence over timestamps."
1177 Certainly, it is mistake. It is necessary to understand the reasons
1178 of this constraint to relax it: if peer reboots, clock may go
1179 out-of-sync and half-open connections will not be reset.
1180 Actually, the problem would be not existing if all
1181 the implementations followed draft about maintaining clock
1182 via reboots. Linux-2.2 DOES NOT!
1184 However, we can relax time bounds for RST segments to MSL.
1186 if (rst && get_seconds() >= rx_opt->ts_recent_stamp + TCP_PAWS_MSL)
1191 static inline void tcp_mib_init(struct net *net)
1194 TCP_ADD_STATS_USER(net, TCP_MIB_RTOALGORITHM, 1);
1195 TCP_ADD_STATS_USER(net, TCP_MIB_RTOMIN, TCP_RTO_MIN*1000/HZ);
1196 TCP_ADD_STATS_USER(net, TCP_MIB_RTOMAX, TCP_RTO_MAX*1000/HZ);
1197 TCP_ADD_STATS_USER(net, TCP_MIB_MAXCONN, -1);
1201 static inline void tcp_clear_retrans_hints_partial(struct tcp_sock *tp)
1203 tp->lost_skb_hint = NULL;
1206 static inline void tcp_clear_all_retrans_hints(struct tcp_sock *tp)
1208 tcp_clear_retrans_hints_partial(tp);
1209 tp->retransmit_skb_hint = NULL;
1215 union tcp_md5_addr {
1217 #if IS_ENABLED(CONFIG_IPV6)
1222 /* - key database */
1223 struct tcp_md5sig_key {
1224 struct hlist_node node;
1226 u8 family; /* AF_INET or AF_INET6 */
1227 union tcp_md5_addr addr;
1228 u8 key[TCP_MD5SIG_MAXKEYLEN];
1229 struct rcu_head rcu;
1233 struct tcp_md5sig_info {
1234 struct hlist_head head;
1235 struct rcu_head rcu;
1238 /* - pseudo header */
1239 struct tcp4_pseudohdr {
1247 struct tcp6_pseudohdr {
1248 struct in6_addr saddr;
1249 struct in6_addr daddr;
1251 __be32 protocol; /* including padding */
1254 union tcp_md5sum_block {
1255 struct tcp4_pseudohdr ip4;
1256 #if IS_ENABLED(CONFIG_IPV6)
1257 struct tcp6_pseudohdr ip6;
1261 /* - pool: digest algorithm, hash description and scratch buffer */
1262 struct tcp_md5sig_pool {
1263 struct hash_desc md5_desc;
1264 union tcp_md5sum_block md5_blk;
1268 int tcp_v4_md5_hash_skb(char *md5_hash, struct tcp_md5sig_key *key,
1269 const struct sock *sk, const struct request_sock *req,
1270 const struct sk_buff *skb);
1271 int tcp_md5_do_add(struct sock *sk, const union tcp_md5_addr *addr,
1272 int family, const u8 *newkey, u8 newkeylen, gfp_t gfp);
1273 int tcp_md5_do_del(struct sock *sk, const union tcp_md5_addr *addr,
1275 struct tcp_md5sig_key *tcp_v4_md5_lookup(struct sock *sk,
1276 struct sock *addr_sk);
1278 #ifdef CONFIG_TCP_MD5SIG
1279 struct tcp_md5sig_key *tcp_md5_do_lookup(struct sock *sk,
1280 const union tcp_md5_addr *addr,
1282 #define tcp_twsk_md5_key(twsk) ((twsk)->tw_md5_key)
1284 static inline struct tcp_md5sig_key *tcp_md5_do_lookup(struct sock *sk,
1285 const union tcp_md5_addr *addr,
1290 #define tcp_twsk_md5_key(twsk) NULL
1293 bool tcp_alloc_md5sig_pool(void);
1295 struct tcp_md5sig_pool *tcp_get_md5sig_pool(void);
1296 static inline void tcp_put_md5sig_pool(void)
1301 int tcp_md5_hash_header(struct tcp_md5sig_pool *, const struct tcphdr *);
1302 int tcp_md5_hash_skb_data(struct tcp_md5sig_pool *, const struct sk_buff *,
1303 unsigned int header_len);
1304 int tcp_md5_hash_key(struct tcp_md5sig_pool *hp,
1305 const struct tcp_md5sig_key *key);
1307 /* From tcp_fastopen.c */
1308 void tcp_fastopen_cache_get(struct sock *sk, u16 *mss,
1309 struct tcp_fastopen_cookie *cookie, int *syn_loss,
1310 unsigned long *last_syn_loss);
1311 void tcp_fastopen_cache_set(struct sock *sk, u16 mss,
1312 struct tcp_fastopen_cookie *cookie, bool syn_lost);
1313 struct tcp_fastopen_request {
1314 /* Fast Open cookie. Size 0 means a cookie request */
1315 struct tcp_fastopen_cookie cookie;
1316 struct msghdr *data; /* data in MSG_FASTOPEN */
1318 int copied; /* queued in tcp_connect() */
1320 void tcp_free_fastopen_req(struct tcp_sock *tp);
1322 extern struct tcp_fastopen_context __rcu *tcp_fastopen_ctx;
1323 int tcp_fastopen_reset_cipher(void *key, unsigned int len);
1324 bool tcp_try_fastopen(struct sock *sk, struct sk_buff *skb,
1325 struct request_sock *req,
1326 struct tcp_fastopen_cookie *foc,
1327 struct dst_entry *dst);
1328 void tcp_fastopen_init_key_once(bool publish);
1329 #define TCP_FASTOPEN_KEY_LENGTH 16
1331 /* Fastopen key context */
1332 struct tcp_fastopen_context {
1333 struct crypto_cipher *tfm;
1334 __u8 key[TCP_FASTOPEN_KEY_LENGTH];
1335 struct rcu_head rcu;
1338 /* write queue abstraction */
1339 static inline void tcp_write_queue_purge(struct sock *sk)
1341 struct sk_buff *skb;
1343 while ((skb = __skb_dequeue(&sk->sk_write_queue)) != NULL)
1344 sk_wmem_free_skb(sk, skb);
1346 tcp_clear_all_retrans_hints(tcp_sk(sk));
1349 static inline struct sk_buff *tcp_write_queue_head(const struct sock *sk)
1351 return skb_peek(&sk->sk_write_queue);
1354 static inline struct sk_buff *tcp_write_queue_tail(const struct sock *sk)
1356 return skb_peek_tail(&sk->sk_write_queue);
1359 static inline struct sk_buff *tcp_write_queue_next(const struct sock *sk,
1360 const struct sk_buff *skb)
1362 return skb_queue_next(&sk->sk_write_queue, skb);
1365 static inline struct sk_buff *tcp_write_queue_prev(const struct sock *sk,
1366 const struct sk_buff *skb)
1368 return skb_queue_prev(&sk->sk_write_queue, skb);
1371 #define tcp_for_write_queue(skb, sk) \
1372 skb_queue_walk(&(sk)->sk_write_queue, skb)
1374 #define tcp_for_write_queue_from(skb, sk) \
1375 skb_queue_walk_from(&(sk)->sk_write_queue, skb)
1377 #define tcp_for_write_queue_from_safe(skb, tmp, sk) \
1378 skb_queue_walk_from_safe(&(sk)->sk_write_queue, skb, tmp)
1380 static inline struct sk_buff *tcp_send_head(const struct sock *sk)
1382 return sk->sk_send_head;
1385 static inline bool tcp_skb_is_last(const struct sock *sk,
1386 const struct sk_buff *skb)
1388 return skb_queue_is_last(&sk->sk_write_queue, skb);
1391 static inline void tcp_advance_send_head(struct sock *sk, const struct sk_buff *skb)
1393 if (tcp_skb_is_last(sk, skb))
1394 sk->sk_send_head = NULL;
1396 sk->sk_send_head = tcp_write_queue_next(sk, skb);
1399 static inline void tcp_check_send_head(struct sock *sk, struct sk_buff *skb_unlinked)
1401 if (sk->sk_send_head == skb_unlinked)
1402 sk->sk_send_head = NULL;
1405 static inline void tcp_init_send_head(struct sock *sk)
1407 sk->sk_send_head = NULL;
1410 static inline void __tcp_add_write_queue_tail(struct sock *sk, struct sk_buff *skb)
1412 __skb_queue_tail(&sk->sk_write_queue, skb);
1415 static inline void tcp_add_write_queue_tail(struct sock *sk, struct sk_buff *skb)
1417 __tcp_add_write_queue_tail(sk, skb);
1419 /* Queue it, remembering where we must start sending. */
1420 if (sk->sk_send_head == NULL) {
1421 sk->sk_send_head = skb;
1423 if (tcp_sk(sk)->highest_sack == NULL)
1424 tcp_sk(sk)->highest_sack = skb;
1428 static inline void __tcp_add_write_queue_head(struct sock *sk, struct sk_buff *skb)
1430 __skb_queue_head(&sk->sk_write_queue, skb);
1433 /* Insert buff after skb on the write queue of sk. */
1434 static inline void tcp_insert_write_queue_after(struct sk_buff *skb,
1435 struct sk_buff *buff,
1438 __skb_queue_after(&sk->sk_write_queue, skb, buff);
1441 /* Insert new before skb on the write queue of sk. */
1442 static inline void tcp_insert_write_queue_before(struct sk_buff *new,
1443 struct sk_buff *skb,
1446 __skb_queue_before(&sk->sk_write_queue, skb, new);
1448 if (sk->sk_send_head == skb)
1449 sk->sk_send_head = new;
1452 static inline void tcp_unlink_write_queue(struct sk_buff *skb, struct sock *sk)
1454 __skb_unlink(skb, &sk->sk_write_queue);
1457 static inline bool tcp_write_queue_empty(struct sock *sk)
1459 return skb_queue_empty(&sk->sk_write_queue);
1462 static inline void tcp_push_pending_frames(struct sock *sk)
1464 if (tcp_send_head(sk)) {
1465 struct tcp_sock *tp = tcp_sk(sk);
1467 __tcp_push_pending_frames(sk, tcp_current_mss(sk), tp->nonagle);
1471 /* Start sequence of the skb just after the highest skb with SACKed
1472 * bit, valid only if sacked_out > 0 or when the caller has ensured
1473 * validity by itself.
1475 static inline u32 tcp_highest_sack_seq(struct tcp_sock *tp)
1477 if (!tp->sacked_out)
1480 if (tp->highest_sack == NULL)
1483 return TCP_SKB_CB(tp->highest_sack)->seq;
1486 static inline void tcp_advance_highest_sack(struct sock *sk, struct sk_buff *skb)
1488 tcp_sk(sk)->highest_sack = tcp_skb_is_last(sk, skb) ? NULL :
1489 tcp_write_queue_next(sk, skb);
1492 static inline struct sk_buff *tcp_highest_sack(struct sock *sk)
1494 return tcp_sk(sk)->highest_sack;
1497 static inline void tcp_highest_sack_reset(struct sock *sk)
1499 tcp_sk(sk)->highest_sack = tcp_write_queue_head(sk);
1502 /* Called when old skb is about to be deleted (to be combined with new skb) */
1503 static inline void tcp_highest_sack_combine(struct sock *sk,
1504 struct sk_buff *old,
1505 struct sk_buff *new)
1507 if (tcp_sk(sk)->sacked_out && (old == tcp_sk(sk)->highest_sack))
1508 tcp_sk(sk)->highest_sack = new;
1511 /* Determines whether this is a thin stream (which may suffer from
1512 * increased latency). Used to trigger latency-reducing mechanisms.
1514 static inline bool tcp_stream_is_thin(struct tcp_sock *tp)
1516 return tp->packets_out < 4 && !tcp_in_initial_slowstart(tp);
1520 enum tcp_seq_states {
1521 TCP_SEQ_STATE_LISTENING,
1522 TCP_SEQ_STATE_OPENREQ,
1523 TCP_SEQ_STATE_ESTABLISHED,
1526 int tcp_seq_open(struct inode *inode, struct file *file);
1528 struct tcp_seq_afinfo {
1531 const struct file_operations *seq_fops;
1532 struct seq_operations seq_ops;
1535 struct tcp_iter_state {
1536 struct seq_net_private p;
1538 enum tcp_seq_states state;
1539 struct sock *syn_wait_sk;
1540 int bucket, offset, sbucket, num;
1545 int tcp_proc_register(struct net *net, struct tcp_seq_afinfo *afinfo);
1546 void tcp_proc_unregister(struct net *net, struct tcp_seq_afinfo *afinfo);
1548 extern struct request_sock_ops tcp_request_sock_ops;
1549 extern struct request_sock_ops tcp6_request_sock_ops;
1551 void tcp_v4_destroy_sock(struct sock *sk);
1553 struct sk_buff *tcp_gso_segment(struct sk_buff *skb,
1554 netdev_features_t features);
1555 struct sk_buff **tcp_gro_receive(struct sk_buff **head, struct sk_buff *skb);
1556 int tcp_gro_complete(struct sk_buff *skb);
1558 void __tcp_v4_send_check(struct sk_buff *skb, __be32 saddr, __be32 daddr);
1560 static inline u32 tcp_notsent_lowat(const struct tcp_sock *tp)
1562 return tp->notsent_lowat ?: sysctl_tcp_notsent_lowat;
1565 static inline bool tcp_stream_memory_free(const struct sock *sk)
1567 const struct tcp_sock *tp = tcp_sk(sk);
1568 u32 notsent_bytes = tp->write_seq - tp->snd_nxt;
1570 return notsent_bytes < tcp_notsent_lowat(tp);
1573 #ifdef CONFIG_PROC_FS
1574 int tcp4_proc_init(void);
1575 void tcp4_proc_exit(void);
1578 int tcp_rtx_synack(struct sock *sk, struct request_sock *req);
1579 int tcp_conn_request(struct request_sock_ops *rsk_ops,
1580 const struct tcp_request_sock_ops *af_ops,
1581 struct sock *sk, struct sk_buff *skb);
1583 /* TCP af-specific functions */
1584 struct tcp_sock_af_ops {
1585 #ifdef CONFIG_TCP_MD5SIG
1586 struct tcp_md5sig_key *(*md5_lookup) (struct sock *sk,
1587 struct sock *addr_sk);
1588 int (*calc_md5_hash) (char *location,
1589 struct tcp_md5sig_key *md5,
1590 const struct sock *sk,
1591 const struct request_sock *req,
1592 const struct sk_buff *skb);
1593 int (*md5_parse) (struct sock *sk,
1594 char __user *optval,
1599 struct tcp_request_sock_ops {
1601 #ifdef CONFIG_TCP_MD5SIG
1602 struct tcp_md5sig_key *(*md5_lookup) (struct sock *sk,
1603 struct request_sock *req);
1604 int (*calc_md5_hash) (char *location,
1605 struct tcp_md5sig_key *md5,
1606 const struct sock *sk,
1607 const struct request_sock *req,
1608 const struct sk_buff *skb);
1610 void (*init_req)(struct request_sock *req, struct sock *sk,
1611 struct sk_buff *skb);
1612 #ifdef CONFIG_SYN_COOKIES
1613 __u32 (*cookie_init_seq)(struct sock *sk, const struct sk_buff *skb,
1616 struct dst_entry *(*route_req)(struct sock *sk, struct flowi *fl,
1617 const struct request_sock *req,
1619 __u32 (*init_seq)(const struct sk_buff *skb);
1620 int (*send_synack)(struct sock *sk, struct dst_entry *dst,
1621 struct flowi *fl, struct request_sock *req,
1622 u16 queue_mapping, struct tcp_fastopen_cookie *foc);
1623 void (*queue_hash_add)(struct sock *sk, struct request_sock *req,
1624 const unsigned long timeout);
1627 #ifdef CONFIG_SYN_COOKIES
1628 static inline __u32 cookie_init_sequence(const struct tcp_request_sock_ops *ops,
1629 struct sock *sk, struct sk_buff *skb,
1632 return ops->cookie_init_seq(sk, skb, mss);
1635 static inline __u32 cookie_init_sequence(const struct tcp_request_sock_ops *ops,
1636 struct sock *sk, struct sk_buff *skb,
1643 int tcpv4_offload_init(void);
1645 void tcp_v4_init(void);
1646 void tcp_init(void);