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 int __cookie_v4_check(const struct iphdr *iph, const struct tcphdr *th,
481 extern struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb,
482 struct ip_options *opt);
483 #ifdef CONFIG_SYN_COOKIES
484 extern u32 __cookie_v4_init_sequence(const struct iphdr *iph,
485 const struct tcphdr *th, u16 *mssp);
486 extern __u32 cookie_v4_init_sequence(struct sock *sk, struct sk_buff *skb,
489 static inline __u32 cookie_v4_init_sequence(struct sock *sk,
497 extern __u32 cookie_init_timestamp(struct request_sock *req);
498 extern bool cookie_check_timestamp(struct tcp_options_received *opt,
499 struct net *net, bool *ecn_ok);
501 /* From net/ipv6/syncookies.c */
502 extern struct sock *cookie_v6_check(struct sock *sk, struct sk_buff *skb);
503 #ifdef CONFIG_SYN_COOKIES
504 extern __u32 cookie_v6_init_sequence(struct sock *sk, const struct sk_buff *skb,
507 static inline __u32 cookie_v6_init_sequence(struct sock *sk,
516 extern void __tcp_push_pending_frames(struct sock *sk, unsigned int cur_mss,
518 extern bool tcp_may_send_now(struct sock *sk);
519 extern int __tcp_retransmit_skb(struct sock *, struct sk_buff *);
520 extern int tcp_retransmit_skb(struct sock *, struct sk_buff *);
521 extern void tcp_retransmit_timer(struct sock *sk);
522 extern void tcp_xmit_retransmit_queue(struct sock *);
523 extern void tcp_simple_retransmit(struct sock *);
524 extern int tcp_trim_head(struct sock *, struct sk_buff *, u32);
525 extern int tcp_fragment(struct sock *, struct sk_buff *, u32, unsigned int);
527 extern void tcp_send_probe0(struct sock *);
528 extern void tcp_send_partial(struct sock *);
529 extern int tcp_write_wakeup(struct sock *);
530 extern void tcp_send_fin(struct sock *sk);
531 extern void tcp_send_active_reset(struct sock *sk, gfp_t priority);
532 extern int tcp_send_synack(struct sock *);
533 extern bool tcp_syn_flood_action(struct sock *sk,
534 const struct sk_buff *skb,
536 extern void tcp_push_one(struct sock *, unsigned int mss_now);
537 extern void tcp_send_ack(struct sock *sk);
538 extern void tcp_send_delayed_ack(struct sock *sk);
539 extern void tcp_send_loss_probe(struct sock *sk);
540 extern bool tcp_schedule_loss_probe(struct sock *sk);
543 extern void tcp_cwnd_application_limited(struct sock *sk);
544 extern void tcp_resume_early_retransmit(struct sock *sk);
545 extern void tcp_rearm_rto(struct sock *sk);
546 extern void tcp_reset(struct sock *sk);
549 extern void tcp_init_xmit_timers(struct sock *);
550 static inline void tcp_clear_xmit_timers(struct sock *sk)
552 inet_csk_clear_xmit_timers(sk);
555 extern unsigned int tcp_sync_mss(struct sock *sk, u32 pmtu);
556 extern unsigned int tcp_current_mss(struct sock *sk);
558 /* Bound MSS / TSO packet size with the half of the window */
559 static inline int tcp_bound_to_half_wnd(struct tcp_sock *tp, int pktsize)
563 /* When peer uses tiny windows, there is no use in packetizing
564 * to sub-MSS pieces for the sake of SWS or making sure there
565 * are enough packets in the pipe for fast recovery.
567 * On the other hand, for extremely large MSS devices, handling
568 * smaller than MSS windows in this way does make sense.
570 if (tp->max_window >= 512)
571 cutoff = (tp->max_window >> 1);
573 cutoff = tp->max_window;
575 if (cutoff && pktsize > cutoff)
576 return max_t(int, cutoff, 68U - tp->tcp_header_len);
582 extern void tcp_get_info(const struct sock *, struct tcp_info *);
584 /* Read 'sendfile()'-style from a TCP socket */
585 typedef int (*sk_read_actor_t)(read_descriptor_t *, struct sk_buff *,
586 unsigned int, size_t);
587 extern int tcp_read_sock(struct sock *sk, read_descriptor_t *desc,
588 sk_read_actor_t recv_actor);
590 extern void tcp_initialize_rcv_mss(struct sock *sk);
592 extern int tcp_mtu_to_mss(struct sock *sk, int pmtu);
593 extern int tcp_mss_to_mtu(struct sock *sk, int mss);
594 extern void tcp_mtup_init(struct sock *sk);
595 extern void tcp_init_buffer_space(struct sock *sk);
597 static inline void tcp_bound_rto(const struct sock *sk)
599 if (inet_csk(sk)->icsk_rto > TCP_RTO_MAX)
600 inet_csk(sk)->icsk_rto = TCP_RTO_MAX;
603 static inline u32 __tcp_set_rto(const struct tcp_sock *tp)
605 return (tp->srtt >> 3) + tp->rttvar;
608 extern void tcp_set_rto(struct sock *sk);
610 static inline void __tcp_fast_path_on(struct tcp_sock *tp, u32 snd_wnd)
612 tp->pred_flags = htonl((tp->tcp_header_len << 26) |
613 ntohl(TCP_FLAG_ACK) |
617 static inline void tcp_fast_path_on(struct tcp_sock *tp)
619 __tcp_fast_path_on(tp, tp->snd_wnd >> tp->rx_opt.snd_wscale);
622 static inline void tcp_fast_path_check(struct sock *sk)
624 struct tcp_sock *tp = tcp_sk(sk);
626 if (skb_queue_empty(&tp->out_of_order_queue) &&
628 atomic_read(&sk->sk_rmem_alloc) < sk->sk_rcvbuf &&
630 tcp_fast_path_on(tp);
633 /* Compute the actual rto_min value */
634 static inline u32 tcp_rto_min(struct sock *sk)
636 const struct dst_entry *dst = __sk_dst_get(sk);
637 u32 rto_min = TCP_RTO_MIN;
639 if (dst && dst_metric_locked(dst, RTAX_RTO_MIN))
640 rto_min = dst_metric_rtt(dst, RTAX_RTO_MIN);
644 /* Compute the actual receive window we are currently advertising.
645 * Rcv_nxt can be after the window if our peer push more data
646 * than the offered window.
648 static inline u32 tcp_receive_window(const struct tcp_sock *tp)
650 s32 win = tp->rcv_wup + tp->rcv_wnd - tp->rcv_nxt;
657 /* Choose a new window, without checks for shrinking, and without
658 * scaling applied to the result. The caller does these things
659 * if necessary. This is a "raw" window selection.
661 extern u32 __tcp_select_window(struct sock *sk);
663 void tcp_send_window_probe(struct sock *sk);
665 /* TCP timestamps are only 32-bits, this causes a slight
666 * complication on 64-bit systems since we store a snapshot
667 * of jiffies in the buffer control blocks below. We decided
668 * to use only the low 32-bits of jiffies and hide the ugly
669 * casts with the following macro.
671 #define tcp_time_stamp ((__u32)(jiffies))
673 #define tcp_flag_byte(th) (((u_int8_t *)th)[13])
675 #define TCPHDR_FIN 0x01
676 #define TCPHDR_SYN 0x02
677 #define TCPHDR_RST 0x04
678 #define TCPHDR_PSH 0x08
679 #define TCPHDR_ACK 0x10
680 #define TCPHDR_URG 0x20
681 #define TCPHDR_ECE 0x40
682 #define TCPHDR_CWR 0x80
684 /* This is what the send packet queuing engine uses to pass
685 * TCP per-packet control information to the transmission code.
686 * We also store the host-order sequence numbers in here too.
687 * This is 44 bytes if IPV6 is enabled.
688 * If this grows please adjust skbuff.h:skbuff->cb[xxx] size appropriately.
692 struct inet_skb_parm h4;
693 #if IS_ENABLED(CONFIG_IPV6)
694 struct inet6_skb_parm h6;
696 } header; /* For incoming frames */
697 __u32 seq; /* Starting sequence number */
698 __u32 end_seq; /* SEQ + FIN + SYN + datalen */
699 __u32 when; /* used to compute rtt's */
700 __u8 tcp_flags; /* TCP header flags. (tcp[13]) */
702 __u8 sacked; /* State flags for SACK/FACK. */
703 #define TCPCB_SACKED_ACKED 0x01 /* SKB ACK'd by a SACK block */
704 #define TCPCB_SACKED_RETRANS 0x02 /* SKB retransmitted */
705 #define TCPCB_LOST 0x04 /* SKB is lost */
706 #define TCPCB_TAGBITS 0x07 /* All tag bits */
707 #define TCPCB_EVER_RETRANS 0x80 /* Ever retransmitted frame */
708 #define TCPCB_RETRANS (TCPCB_SACKED_RETRANS|TCPCB_EVER_RETRANS)
710 __u8 ip_dsfield; /* IPv4 tos or IPv6 dsfield */
712 __u32 ack_seq; /* Sequence number ACK'd */
715 #define TCP_SKB_CB(__skb) ((struct tcp_skb_cb *)&((__skb)->cb[0]))
717 /* RFC3168 : 6.1.1 SYN packets must not have ECT/ECN bits set
719 * If we receive a SYN packet with these bits set, it means a network is
720 * playing bad games with TOS bits. In order to avoid possible false congestion
721 * notifications, we disable TCP ECN negociation.
724 TCP_ECN_create_request(struct request_sock *req, const struct sk_buff *skb,
727 const struct tcphdr *th = tcp_hdr(skb);
729 if (net->ipv4.sysctl_tcp_ecn && th->ece && th->cwr &&
730 INET_ECN_is_not_ect(TCP_SKB_CB(skb)->ip_dsfield))
731 inet_rsk(req)->ecn_ok = 1;
734 /* Due to TSO, an SKB can be composed of multiple actual
735 * packets. To keep these tracked properly, we use this.
737 static inline int tcp_skb_pcount(const struct sk_buff *skb)
739 return skb_shinfo(skb)->gso_segs;
742 /* This is valid iff tcp_skb_pcount() > 1. */
743 static inline int tcp_skb_mss(const struct sk_buff *skb)
745 return skb_shinfo(skb)->gso_size;
748 /* Events passed to congestion control interface */
750 CA_EVENT_TX_START, /* first transmit when no packets in flight */
751 CA_EVENT_CWND_RESTART, /* congestion window restart */
752 CA_EVENT_COMPLETE_CWR, /* end of congestion recovery */
753 CA_EVENT_LOSS, /* loss timeout */
754 CA_EVENT_FAST_ACK, /* in sequence ack */
755 CA_EVENT_SLOW_ACK, /* other ack */
759 * Interface for adding new TCP congestion control handlers
761 #define TCP_CA_NAME_MAX 16
762 #define TCP_CA_MAX 128
763 #define TCP_CA_BUF_MAX (TCP_CA_NAME_MAX*TCP_CA_MAX)
765 #define TCP_CONG_NON_RESTRICTED 0x1
766 #define TCP_CONG_RTT_STAMP 0x2
768 struct tcp_congestion_ops {
769 struct list_head list;
772 /* initialize private data (optional) */
773 void (*init)(struct sock *sk);
774 /* cleanup private data (optional) */
775 void (*release)(struct sock *sk);
777 /* return slow start threshold (required) */
778 u32 (*ssthresh)(struct sock *sk);
779 /* lower bound for congestion window (optional) */
780 u32 (*min_cwnd)(const struct sock *sk);
781 /* do new cwnd calculation (required) */
782 void (*cong_avoid)(struct sock *sk, u32 ack, u32 in_flight);
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 extern int tcp_register_congestion_control(struct tcp_congestion_ops *type);
799 extern void tcp_unregister_congestion_control(struct tcp_congestion_ops *type);
801 extern void tcp_init_congestion_control(struct sock *sk);
802 extern void tcp_cleanup_congestion_control(struct sock *sk);
803 extern int tcp_set_default_congestion_control(const char *name);
804 extern void tcp_get_default_congestion_control(char *name);
805 extern void tcp_get_available_congestion_control(char *buf, size_t len);
806 extern void tcp_get_allowed_congestion_control(char *buf, size_t len);
807 extern int tcp_set_allowed_congestion_control(char *allowed);
808 extern int tcp_set_congestion_control(struct sock *sk, const char *name);
809 extern void tcp_slow_start(struct tcp_sock *tp);
810 extern void tcp_cong_avoid_ai(struct tcp_sock *tp, u32 w);
812 extern struct tcp_congestion_ops tcp_init_congestion_ops;
813 extern u32 tcp_reno_ssthresh(struct sock *sk);
814 extern void tcp_reno_cong_avoid(struct sock *sk, u32 ack, u32 in_flight);
815 extern u32 tcp_reno_min_cwnd(const struct sock *sk);
816 extern struct tcp_congestion_ops tcp_reno;
818 static inline void tcp_set_ca_state(struct sock *sk, const u8 ca_state)
820 struct inet_connection_sock *icsk = inet_csk(sk);
822 if (icsk->icsk_ca_ops->set_state)
823 icsk->icsk_ca_ops->set_state(sk, ca_state);
824 icsk->icsk_ca_state = ca_state;
827 static inline void tcp_ca_event(struct sock *sk, const enum tcp_ca_event event)
829 const struct inet_connection_sock *icsk = inet_csk(sk);
831 if (icsk->icsk_ca_ops->cwnd_event)
832 icsk->icsk_ca_ops->cwnd_event(sk, event);
835 /* These functions determine how the current flow behaves in respect of SACK
836 * handling. SACK is negotiated with the peer, and therefore it can vary
837 * between different flows.
839 * tcp_is_sack - SACK enabled
840 * tcp_is_reno - No SACK
841 * tcp_is_fack - FACK enabled, implies SACK enabled
843 static inline int tcp_is_sack(const struct tcp_sock *tp)
845 return tp->rx_opt.sack_ok;
848 static inline bool tcp_is_reno(const struct tcp_sock *tp)
850 return !tcp_is_sack(tp);
853 static inline bool tcp_is_fack(const struct tcp_sock *tp)
855 return tp->rx_opt.sack_ok & TCP_FACK_ENABLED;
858 static inline void tcp_enable_fack(struct tcp_sock *tp)
860 tp->rx_opt.sack_ok |= TCP_FACK_ENABLED;
863 /* TCP early-retransmit (ER) is similar to but more conservative than
864 * the thin-dupack feature. Enable ER only if thin-dupack is disabled.
866 static inline void tcp_enable_early_retrans(struct tcp_sock *tp)
868 tp->do_early_retrans = sysctl_tcp_early_retrans &&
869 sysctl_tcp_early_retrans < 4 && !sysctl_tcp_thin_dupack &&
870 sysctl_tcp_reordering == 3;
873 static inline void tcp_disable_early_retrans(struct tcp_sock *tp)
875 tp->do_early_retrans = 0;
878 static inline unsigned int tcp_left_out(const struct tcp_sock *tp)
880 return tp->sacked_out + tp->lost_out;
883 /* This determines how many packets are "in the network" to the best
884 * of our knowledge. In many cases it is conservative, but where
885 * detailed information is available from the receiver (via SACK
886 * blocks etc.) we can make more aggressive calculations.
888 * Use this for decisions involving congestion control, use just
889 * tp->packets_out to determine if the send queue is empty or not.
891 * Read this equation as:
893 * "Packets sent once on transmission queue" MINUS
894 * "Packets left network, but not honestly ACKed yet" PLUS
895 * "Packets fast retransmitted"
897 static inline unsigned int tcp_packets_in_flight(const struct tcp_sock *tp)
899 return tp->packets_out - tcp_left_out(tp) + tp->retrans_out;
902 #define TCP_INFINITE_SSTHRESH 0x7fffffff
904 static inline bool tcp_in_initial_slowstart(const struct tcp_sock *tp)
906 return tp->snd_ssthresh >= TCP_INFINITE_SSTHRESH;
909 static inline bool tcp_in_cwnd_reduction(const struct sock *sk)
911 return (TCPF_CA_CWR | TCPF_CA_Recovery) &
912 (1 << inet_csk(sk)->icsk_ca_state);
915 /* If cwnd > ssthresh, we may raise ssthresh to be half-way to cwnd.
916 * The exception is cwnd reduction phase, when cwnd is decreasing towards
919 static inline __u32 tcp_current_ssthresh(const struct sock *sk)
921 const struct tcp_sock *tp = tcp_sk(sk);
923 if (tcp_in_cwnd_reduction(sk))
924 return tp->snd_ssthresh;
926 return max(tp->snd_ssthresh,
927 ((tp->snd_cwnd >> 1) +
928 (tp->snd_cwnd >> 2)));
931 /* Use define here intentionally to get WARN_ON location shown at the caller */
932 #define tcp_verify_left_out(tp) WARN_ON(tcp_left_out(tp) > tp->packets_out)
934 extern void tcp_enter_cwr(struct sock *sk, const int set_ssthresh);
935 extern __u32 tcp_init_cwnd(const struct tcp_sock *tp, const struct dst_entry *dst);
937 /* The maximum number of MSS of available cwnd for which TSO defers
938 * sending if not using sysctl_tcp_tso_win_divisor.
940 static inline __u32 tcp_max_tso_deferred_mss(const struct tcp_sock *tp)
945 /* Slow start with delack produces 3 packets of burst, so that
946 * it is safe "de facto". This will be the default - same as
947 * the default reordering threshold - but if reordering increases,
948 * we must be able to allow cwnd to burst at least this much in order
949 * to not pull it back when holes are filled.
951 static __inline__ __u32 tcp_max_burst(const struct tcp_sock *tp)
953 return tp->reordering;
956 /* Returns end sequence number of the receiver's advertised window */
957 static inline u32 tcp_wnd_end(const struct tcp_sock *tp)
959 return tp->snd_una + tp->snd_wnd;
961 extern bool tcp_is_cwnd_limited(const struct sock *sk, u32 in_flight);
963 static inline void tcp_minshall_update(struct tcp_sock *tp, unsigned int mss,
964 const struct sk_buff *skb)
967 tp->snd_sml = TCP_SKB_CB(skb)->end_seq;
970 static inline void tcp_check_probe_timer(struct sock *sk)
972 const struct tcp_sock *tp = tcp_sk(sk);
973 const struct inet_connection_sock *icsk = inet_csk(sk);
975 if (!tp->packets_out && !icsk->icsk_pending)
976 inet_csk_reset_xmit_timer(sk, ICSK_TIME_PROBE0,
977 icsk->icsk_rto, TCP_RTO_MAX);
980 static inline void tcp_init_wl(struct tcp_sock *tp, u32 seq)
985 static inline void tcp_update_wl(struct tcp_sock *tp, u32 seq)
991 * Calculate(/check) TCP checksum
993 static inline __sum16 tcp_v4_check(int len, __be32 saddr,
994 __be32 daddr, __wsum base)
996 return csum_tcpudp_magic(saddr,daddr,len,IPPROTO_TCP,base);
999 static inline __sum16 __tcp_checksum_complete(struct sk_buff *skb)
1001 return __skb_checksum_complete(skb);
1004 static inline bool tcp_checksum_complete(struct sk_buff *skb)
1006 return !skb_csum_unnecessary(skb) &&
1007 __tcp_checksum_complete(skb);
1010 /* Prequeue for VJ style copy to user, combined with checksumming. */
1012 static inline void tcp_prequeue_init(struct tcp_sock *tp)
1014 tp->ucopy.task = NULL;
1016 tp->ucopy.memory = 0;
1017 skb_queue_head_init(&tp->ucopy.prequeue);
1018 #ifdef CONFIG_NET_DMA
1019 tp->ucopy.dma_chan = NULL;
1020 tp->ucopy.wakeup = 0;
1021 tp->ucopy.pinned_list = NULL;
1022 tp->ucopy.dma_cookie = 0;
1026 extern bool tcp_prequeue(struct sock *sk, struct sk_buff *skb);
1031 static const char *statename[]={
1032 "Unused","Established","Syn Sent","Syn Recv",
1033 "Fin Wait 1","Fin Wait 2","Time Wait", "Close",
1034 "Close Wait","Last ACK","Listen","Closing"
1037 extern void tcp_set_state(struct sock *sk, int state);
1039 extern void tcp_done(struct sock *sk);
1041 static inline void tcp_sack_reset(struct tcp_options_received *rx_opt)
1044 rx_opt->num_sacks = 0;
1047 extern u32 tcp_default_init_rwnd(u32 mss);
1049 /* Determine a window scaling and initial window to offer. */
1050 extern void tcp_select_initial_window(int __space, __u32 mss,
1051 __u32 *rcv_wnd, __u32 *window_clamp,
1052 int wscale_ok, __u8 *rcv_wscale,
1053 __u32 init_rcv_wnd);
1055 static inline int tcp_win_from_space(int space)
1057 return sysctl_tcp_adv_win_scale<=0 ?
1058 (space>>(-sysctl_tcp_adv_win_scale)) :
1059 space - (space>>sysctl_tcp_adv_win_scale);
1062 /* Note: caller must be prepared to deal with negative returns */
1063 static inline int tcp_space(const struct sock *sk)
1065 return tcp_win_from_space(sk->sk_rcvbuf -
1066 atomic_read(&sk->sk_rmem_alloc));
1069 static inline int tcp_full_space(const struct sock *sk)
1071 return tcp_win_from_space(sk->sk_rcvbuf);
1074 static inline void tcp_openreq_init(struct request_sock *req,
1075 struct tcp_options_received *rx_opt,
1076 struct sk_buff *skb)
1078 struct inet_request_sock *ireq = inet_rsk(req);
1080 req->rcv_wnd = 0; /* So that tcp_send_synack() knows! */
1082 tcp_rsk(req)->rcv_isn = TCP_SKB_CB(skb)->seq;
1083 tcp_rsk(req)->rcv_nxt = TCP_SKB_CB(skb)->seq + 1;
1084 tcp_rsk(req)->snt_synack = 0;
1085 req->mss = rx_opt->mss_clamp;
1086 req->ts_recent = rx_opt->saw_tstamp ? rx_opt->rcv_tsval : 0;
1087 ireq->tstamp_ok = rx_opt->tstamp_ok;
1088 ireq->sack_ok = rx_opt->sack_ok;
1089 ireq->snd_wscale = rx_opt->snd_wscale;
1090 ireq->wscale_ok = rx_opt->wscale_ok;
1093 ireq->rmt_port = tcp_hdr(skb)->source;
1094 ireq->loc_port = tcp_hdr(skb)->dest;
1097 extern void tcp_enter_memory_pressure(struct sock *sk);
1099 static inline int keepalive_intvl_when(const struct tcp_sock *tp)
1101 return tp->keepalive_intvl ? : sysctl_tcp_keepalive_intvl;
1104 static inline int keepalive_time_when(const struct tcp_sock *tp)
1106 return tp->keepalive_time ? : sysctl_tcp_keepalive_time;
1109 static inline int keepalive_probes(const struct tcp_sock *tp)
1111 return tp->keepalive_probes ? : sysctl_tcp_keepalive_probes;
1114 static inline u32 keepalive_time_elapsed(const struct tcp_sock *tp)
1116 const struct inet_connection_sock *icsk = &tp->inet_conn;
1118 return min_t(u32, tcp_time_stamp - icsk->icsk_ack.lrcvtime,
1119 tcp_time_stamp - tp->rcv_tstamp);
1122 static inline int tcp_fin_time(const struct sock *sk)
1124 int fin_timeout = tcp_sk(sk)->linger2 ? : sysctl_tcp_fin_timeout;
1125 const int rto = inet_csk(sk)->icsk_rto;
1127 if (fin_timeout < (rto << 2) - (rto >> 1))
1128 fin_timeout = (rto << 2) - (rto >> 1);
1133 static inline bool tcp_paws_check(const struct tcp_options_received *rx_opt,
1136 if ((s32)(rx_opt->ts_recent - rx_opt->rcv_tsval) <= paws_win)
1138 if (unlikely(get_seconds() >= rx_opt->ts_recent_stamp + TCP_PAWS_24DAYS))
1141 * Some OSes send SYN and SYNACK messages with tsval=0 tsecr=0,
1142 * then following tcp messages have valid values. Ignore 0 value,
1143 * or else 'negative' tsval might forbid us to accept their packets.
1145 if (!rx_opt->ts_recent)
1150 static inline bool tcp_paws_reject(const struct tcp_options_received *rx_opt,
1153 if (tcp_paws_check(rx_opt, 0))
1156 /* RST segments are not recommended to carry timestamp,
1157 and, if they do, it is recommended to ignore PAWS because
1158 "their cleanup function should take precedence over timestamps."
1159 Certainly, it is mistake. It is necessary to understand the reasons
1160 of this constraint to relax it: if peer reboots, clock may go
1161 out-of-sync and half-open connections will not be reset.
1162 Actually, the problem would be not existing if all
1163 the implementations followed draft about maintaining clock
1164 via reboots. Linux-2.2 DOES NOT!
1166 However, we can relax time bounds for RST segments to MSL.
1168 if (rst && get_seconds() >= rx_opt->ts_recent_stamp + TCP_PAWS_MSL)
1173 static inline void tcp_mib_init(struct net *net)
1176 TCP_ADD_STATS_USER(net, TCP_MIB_RTOALGORITHM, 1);
1177 TCP_ADD_STATS_USER(net, TCP_MIB_RTOMIN, TCP_RTO_MIN*1000/HZ);
1178 TCP_ADD_STATS_USER(net, TCP_MIB_RTOMAX, TCP_RTO_MAX*1000/HZ);
1179 TCP_ADD_STATS_USER(net, TCP_MIB_MAXCONN, -1);
1183 static inline void tcp_clear_retrans_hints_partial(struct tcp_sock *tp)
1185 tp->lost_skb_hint = NULL;
1188 static inline void tcp_clear_all_retrans_hints(struct tcp_sock *tp)
1190 tcp_clear_retrans_hints_partial(tp);
1191 tp->retransmit_skb_hint = NULL;
1197 union tcp_md5_addr {
1199 #if IS_ENABLED(CONFIG_IPV6)
1204 /* - key database */
1205 struct tcp_md5sig_key {
1206 struct hlist_node node;
1208 u8 family; /* AF_INET or AF_INET6 */
1209 union tcp_md5_addr addr;
1210 u8 key[TCP_MD5SIG_MAXKEYLEN];
1211 struct rcu_head rcu;
1215 struct tcp_md5sig_info {
1216 struct hlist_head head;
1217 struct rcu_head rcu;
1220 /* - pseudo header */
1221 struct tcp4_pseudohdr {
1229 struct tcp6_pseudohdr {
1230 struct in6_addr saddr;
1231 struct in6_addr daddr;
1233 __be32 protocol; /* including padding */
1236 union tcp_md5sum_block {
1237 struct tcp4_pseudohdr ip4;
1238 #if IS_ENABLED(CONFIG_IPV6)
1239 struct tcp6_pseudohdr ip6;
1243 /* - pool: digest algorithm, hash description and scratch buffer */
1244 struct tcp_md5sig_pool {
1245 struct hash_desc md5_desc;
1246 union tcp_md5sum_block md5_blk;
1250 extern int tcp_v4_md5_hash_skb(char *md5_hash, struct tcp_md5sig_key *key,
1251 const struct sock *sk,
1252 const struct request_sock *req,
1253 const struct sk_buff *skb);
1254 extern int tcp_md5_do_add(struct sock *sk, const union tcp_md5_addr *addr,
1255 int family, const u8 *newkey,
1256 u8 newkeylen, gfp_t gfp);
1257 extern int tcp_md5_do_del(struct sock *sk, const union tcp_md5_addr *addr,
1259 extern struct tcp_md5sig_key *tcp_v4_md5_lookup(struct sock *sk,
1260 struct sock *addr_sk);
1262 #ifdef CONFIG_TCP_MD5SIG
1263 extern struct tcp_md5sig_key *tcp_md5_do_lookup(struct sock *sk,
1264 const union tcp_md5_addr *addr, int family);
1265 #define tcp_twsk_md5_key(twsk) ((twsk)->tw_md5_key)
1267 static inline struct tcp_md5sig_key *tcp_md5_do_lookup(struct sock *sk,
1268 const union tcp_md5_addr *addr,
1273 #define tcp_twsk_md5_key(twsk) NULL
1276 extern bool tcp_alloc_md5sig_pool(void);
1278 extern struct tcp_md5sig_pool *tcp_get_md5sig_pool(void);
1279 static inline void tcp_put_md5sig_pool(void)
1284 extern int tcp_md5_hash_header(struct tcp_md5sig_pool *, const struct tcphdr *);
1285 extern int tcp_md5_hash_skb_data(struct tcp_md5sig_pool *, const struct sk_buff *,
1286 unsigned int header_len);
1287 extern int tcp_md5_hash_key(struct tcp_md5sig_pool *hp,
1288 const struct tcp_md5sig_key *key);
1290 /* From tcp_fastopen.c */
1291 extern void tcp_fastopen_cache_get(struct sock *sk, u16 *mss,
1292 struct tcp_fastopen_cookie *cookie,
1293 int *syn_loss, unsigned long *last_syn_loss);
1294 extern void tcp_fastopen_cache_set(struct sock *sk, u16 mss,
1295 struct tcp_fastopen_cookie *cookie,
1297 struct tcp_fastopen_request {
1298 /* Fast Open cookie. Size 0 means a cookie request */
1299 struct tcp_fastopen_cookie cookie;
1300 struct msghdr *data; /* data in MSG_FASTOPEN */
1301 u16 copied; /* queued in tcp_connect() */
1303 void tcp_free_fastopen_req(struct tcp_sock *tp);
1305 extern struct tcp_fastopen_context __rcu *tcp_fastopen_ctx;
1306 int tcp_fastopen_reset_cipher(void *key, unsigned int len);
1307 extern void tcp_fastopen_cookie_gen(__be32 src, __be32 dst,
1308 struct tcp_fastopen_cookie *foc);
1310 #define TCP_FASTOPEN_KEY_LENGTH 16
1312 /* Fastopen key context */
1313 struct tcp_fastopen_context {
1314 struct crypto_cipher *tfm;
1315 __u8 key[TCP_FASTOPEN_KEY_LENGTH];
1316 struct rcu_head rcu;
1319 /* write queue abstraction */
1320 static inline void tcp_write_queue_purge(struct sock *sk)
1322 struct sk_buff *skb;
1324 while ((skb = __skb_dequeue(&sk->sk_write_queue)) != NULL)
1325 sk_wmem_free_skb(sk, skb);
1327 tcp_clear_all_retrans_hints(tcp_sk(sk));
1330 static inline struct sk_buff *tcp_write_queue_head(const struct sock *sk)
1332 return skb_peek(&sk->sk_write_queue);
1335 static inline struct sk_buff *tcp_write_queue_tail(const struct sock *sk)
1337 return skb_peek_tail(&sk->sk_write_queue);
1340 static inline struct sk_buff *tcp_write_queue_next(const struct sock *sk,
1341 const struct sk_buff *skb)
1343 return skb_queue_next(&sk->sk_write_queue, skb);
1346 static inline struct sk_buff *tcp_write_queue_prev(const struct sock *sk,
1347 const struct sk_buff *skb)
1349 return skb_queue_prev(&sk->sk_write_queue, skb);
1352 #define tcp_for_write_queue(skb, sk) \
1353 skb_queue_walk(&(sk)->sk_write_queue, skb)
1355 #define tcp_for_write_queue_from(skb, sk) \
1356 skb_queue_walk_from(&(sk)->sk_write_queue, skb)
1358 #define tcp_for_write_queue_from_safe(skb, tmp, sk) \
1359 skb_queue_walk_from_safe(&(sk)->sk_write_queue, skb, tmp)
1361 static inline struct sk_buff *tcp_send_head(const struct sock *sk)
1363 return sk->sk_send_head;
1366 static inline bool tcp_skb_is_last(const struct sock *sk,
1367 const struct sk_buff *skb)
1369 return skb_queue_is_last(&sk->sk_write_queue, skb);
1372 static inline void tcp_advance_send_head(struct sock *sk, const struct sk_buff *skb)
1374 if (tcp_skb_is_last(sk, skb))
1375 sk->sk_send_head = NULL;
1377 sk->sk_send_head = tcp_write_queue_next(sk, skb);
1380 static inline void tcp_check_send_head(struct sock *sk, struct sk_buff *skb_unlinked)
1382 if (sk->sk_send_head == skb_unlinked)
1383 sk->sk_send_head = NULL;
1386 static inline void tcp_init_send_head(struct sock *sk)
1388 sk->sk_send_head = NULL;
1391 static inline void __tcp_add_write_queue_tail(struct sock *sk, struct sk_buff *skb)
1393 __skb_queue_tail(&sk->sk_write_queue, skb);
1396 static inline void tcp_add_write_queue_tail(struct sock *sk, struct sk_buff *skb)
1398 __tcp_add_write_queue_tail(sk, skb);
1400 /* Queue it, remembering where we must start sending. */
1401 if (sk->sk_send_head == NULL) {
1402 sk->sk_send_head = skb;
1404 if (tcp_sk(sk)->highest_sack == NULL)
1405 tcp_sk(sk)->highest_sack = skb;
1409 static inline void __tcp_add_write_queue_head(struct sock *sk, struct sk_buff *skb)
1411 __skb_queue_head(&sk->sk_write_queue, skb);
1414 /* Insert buff after skb on the write queue of sk. */
1415 static inline void tcp_insert_write_queue_after(struct sk_buff *skb,
1416 struct sk_buff *buff,
1419 __skb_queue_after(&sk->sk_write_queue, skb, buff);
1422 /* Insert new before skb on the write queue of sk. */
1423 static inline void tcp_insert_write_queue_before(struct sk_buff *new,
1424 struct sk_buff *skb,
1427 __skb_queue_before(&sk->sk_write_queue, skb, new);
1429 if (sk->sk_send_head == skb)
1430 sk->sk_send_head = new;
1433 static inline void tcp_unlink_write_queue(struct sk_buff *skb, struct sock *sk)
1435 __skb_unlink(skb, &sk->sk_write_queue);
1438 static inline bool tcp_write_queue_empty(struct sock *sk)
1440 return skb_queue_empty(&sk->sk_write_queue);
1443 static inline void tcp_push_pending_frames(struct sock *sk)
1445 if (tcp_send_head(sk)) {
1446 struct tcp_sock *tp = tcp_sk(sk);
1448 __tcp_push_pending_frames(sk, tcp_current_mss(sk), tp->nonagle);
1452 /* Start sequence of the skb just after the highest skb with SACKed
1453 * bit, valid only if sacked_out > 0 or when the caller has ensured
1454 * validity by itself.
1456 static inline u32 tcp_highest_sack_seq(struct tcp_sock *tp)
1458 if (!tp->sacked_out)
1461 if (tp->highest_sack == NULL)
1464 return TCP_SKB_CB(tp->highest_sack)->seq;
1467 static inline void tcp_advance_highest_sack(struct sock *sk, struct sk_buff *skb)
1469 tcp_sk(sk)->highest_sack = tcp_skb_is_last(sk, skb) ? NULL :
1470 tcp_write_queue_next(sk, skb);
1473 static inline struct sk_buff *tcp_highest_sack(struct sock *sk)
1475 return tcp_sk(sk)->highest_sack;
1478 static inline void tcp_highest_sack_reset(struct sock *sk)
1480 tcp_sk(sk)->highest_sack = tcp_write_queue_head(sk);
1483 /* Called when old skb is about to be deleted (to be combined with new skb) */
1484 static inline void tcp_highest_sack_combine(struct sock *sk,
1485 struct sk_buff *old,
1486 struct sk_buff *new)
1488 if (tcp_sk(sk)->sacked_out && (old == tcp_sk(sk)->highest_sack))
1489 tcp_sk(sk)->highest_sack = new;
1492 /* Determines whether this is a thin stream (which may suffer from
1493 * increased latency). Used to trigger latency-reducing mechanisms.
1495 static inline bool tcp_stream_is_thin(struct tcp_sock *tp)
1497 return tp->packets_out < 4 && !tcp_in_initial_slowstart(tp);
1501 enum tcp_seq_states {
1502 TCP_SEQ_STATE_LISTENING,
1503 TCP_SEQ_STATE_OPENREQ,
1504 TCP_SEQ_STATE_ESTABLISHED,
1505 TCP_SEQ_STATE_TIME_WAIT,
1508 int tcp_seq_open(struct inode *inode, struct file *file);
1510 struct tcp_seq_afinfo {
1513 const struct file_operations *seq_fops;
1514 struct seq_operations seq_ops;
1517 struct tcp_iter_state {
1518 struct seq_net_private p;
1520 enum tcp_seq_states state;
1521 struct sock *syn_wait_sk;
1522 int bucket, offset, sbucket, num;
1527 extern int tcp_proc_register(struct net *net, struct tcp_seq_afinfo *afinfo);
1528 extern void tcp_proc_unregister(struct net *net, struct tcp_seq_afinfo *afinfo);
1530 extern struct request_sock_ops tcp_request_sock_ops;
1531 extern struct request_sock_ops tcp6_request_sock_ops;
1533 extern void tcp_v4_destroy_sock(struct sock *sk);
1535 extern struct sk_buff *tcp_tso_segment(struct sk_buff *skb,
1536 netdev_features_t features);
1537 extern struct sk_buff **tcp_gro_receive(struct sk_buff **head,
1538 struct sk_buff *skb);
1539 extern int tcp_gro_complete(struct sk_buff *skb);
1541 extern void __tcp_v4_send_check(struct sk_buff *skb, __be32 saddr,
1544 static inline u32 tcp_notsent_lowat(const struct tcp_sock *tp)
1546 return tp->notsent_lowat ?: sysctl_tcp_notsent_lowat;
1549 static inline bool tcp_stream_memory_free(const struct sock *sk)
1551 const struct tcp_sock *tp = tcp_sk(sk);
1552 u32 notsent_bytes = tp->write_seq - tp->snd_nxt;
1554 return notsent_bytes < tcp_notsent_lowat(tp);
1557 #ifdef CONFIG_PROC_FS
1558 extern int tcp4_proc_init(void);
1559 extern void tcp4_proc_exit(void);
1562 /* TCP af-specific functions */
1563 struct tcp_sock_af_ops {
1564 #ifdef CONFIG_TCP_MD5SIG
1565 struct tcp_md5sig_key *(*md5_lookup) (struct sock *sk,
1566 struct sock *addr_sk);
1567 int (*calc_md5_hash) (char *location,
1568 struct tcp_md5sig_key *md5,
1569 const struct sock *sk,
1570 const struct request_sock *req,
1571 const struct sk_buff *skb);
1572 int (*md5_parse) (struct sock *sk,
1573 char __user *optval,
1578 struct tcp_request_sock_ops {
1579 #ifdef CONFIG_TCP_MD5SIG
1580 struct tcp_md5sig_key *(*md5_lookup) (struct sock *sk,
1581 struct request_sock *req);
1582 int (*calc_md5_hash) (char *location,
1583 struct tcp_md5sig_key *md5,
1584 const struct sock *sk,
1585 const struct request_sock *req,
1586 const struct sk_buff *skb);
1590 extern int tcpv4_offload_init(void);
1592 extern void tcp_v4_init(void);
1593 extern void tcp_init(void);