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 /* Process SYN data but skip cookie validation */
224 #define TFO_SERVER_COOKIE_NOT_CHKED 0x100
225 /* Accept SYN data w/o any cookie option */
226 #define TFO_SERVER_COOKIE_NOT_REQD 0x200
228 /* Force enable TFO on all listeners, i.e., not requiring the
229 * TCP_FASTOPEN socket option. SOCKOPT1/2 determine how to set max_qlen.
231 #define TFO_SERVER_WO_SOCKOPT1 0x400
232 #define TFO_SERVER_WO_SOCKOPT2 0x800
233 /* Always create TFO child sockets on a TFO listener even when
234 * cookie/data not present. (For testing purpose!)
236 #define TFO_SERVER_ALWAYS 0x1000
238 extern struct inet_timewait_death_row tcp_death_row;
240 /* sysctl variables for tcp */
241 extern int sysctl_tcp_timestamps;
242 extern int sysctl_tcp_window_scaling;
243 extern int sysctl_tcp_sack;
244 extern int sysctl_tcp_fin_timeout;
245 extern int sysctl_tcp_keepalive_time;
246 extern int sysctl_tcp_keepalive_probes;
247 extern int sysctl_tcp_keepalive_intvl;
248 extern int sysctl_tcp_syn_retries;
249 extern int sysctl_tcp_synack_retries;
250 extern int sysctl_tcp_retries1;
251 extern int sysctl_tcp_retries2;
252 extern int sysctl_tcp_orphan_retries;
253 extern int sysctl_tcp_syncookies;
254 extern int sysctl_tcp_fastopen;
255 extern int sysctl_tcp_retrans_collapse;
256 extern int sysctl_tcp_stdurg;
257 extern int sysctl_tcp_rfc1337;
258 extern int sysctl_tcp_abort_on_overflow;
259 extern int sysctl_tcp_max_orphans;
260 extern int sysctl_tcp_fack;
261 extern int sysctl_tcp_reordering;
262 extern int sysctl_tcp_dsack;
263 extern long sysctl_tcp_mem[3];
264 extern int sysctl_tcp_wmem[3];
265 extern int sysctl_tcp_rmem[3];
266 extern int sysctl_tcp_app_win;
267 extern int sysctl_tcp_adv_win_scale;
268 extern int sysctl_tcp_tw_reuse;
269 extern int sysctl_tcp_frto;
270 extern int sysctl_tcp_low_latency;
271 extern int sysctl_tcp_dma_copybreak;
272 extern int sysctl_tcp_nometrics_save;
273 extern int sysctl_tcp_moderate_rcvbuf;
274 extern int sysctl_tcp_tso_win_divisor;
275 extern int sysctl_tcp_mtu_probing;
276 extern int sysctl_tcp_base_mss;
277 extern int sysctl_tcp_workaround_signed_windows;
278 extern int sysctl_tcp_slow_start_after_idle;
279 extern int sysctl_tcp_thin_linear_timeouts;
280 extern int sysctl_tcp_thin_dupack;
281 extern int sysctl_tcp_early_retrans;
282 extern int sysctl_tcp_limit_output_bytes;
283 extern int sysctl_tcp_challenge_ack_limit;
284 extern unsigned int sysctl_tcp_notsent_lowat;
285 extern int sysctl_tcp_min_tso_segs;
286 extern int sysctl_tcp_autocorking;
288 extern atomic_long_t tcp_memory_allocated;
289 extern struct percpu_counter tcp_sockets_allocated;
290 extern int tcp_memory_pressure;
293 * The next routines deal with comparing 32 bit unsigned ints
294 * and worry about wraparound (automatic with unsigned arithmetic).
297 static inline bool before(__u32 seq1, __u32 seq2)
299 return (__s32)(seq1-seq2) < 0;
301 #define after(seq2, seq1) before(seq1, seq2)
303 /* is s2<=s1<=s3 ? */
304 static inline bool between(__u32 seq1, __u32 seq2, __u32 seq3)
306 return seq3 - seq2 >= seq1 - seq2;
309 static inline bool tcp_out_of_memory(struct sock *sk)
311 if (sk->sk_wmem_queued > SOCK_MIN_SNDBUF &&
312 sk_memory_allocated(sk) > sk_prot_mem_limits(sk, 2))
317 static inline bool tcp_too_many_orphans(struct sock *sk, int shift)
319 struct percpu_counter *ocp = sk->sk_prot->orphan_count;
320 int orphans = percpu_counter_read_positive(ocp);
322 if (orphans << shift > sysctl_tcp_max_orphans) {
323 orphans = percpu_counter_sum_positive(ocp);
324 if (orphans << shift > sysctl_tcp_max_orphans)
330 bool tcp_check_oom(struct sock *sk, int shift);
332 /* syncookies: remember time of last synqueue overflow */
333 static inline void tcp_synq_overflow(struct sock *sk)
335 tcp_sk(sk)->rx_opt.ts_recent_stamp = jiffies;
338 /* syncookies: no recent synqueue overflow on this listening socket? */
339 static inline bool tcp_synq_no_recent_overflow(const struct sock *sk)
341 unsigned long last_overflow = tcp_sk(sk)->rx_opt.ts_recent_stamp;
342 return time_after(jiffies, last_overflow + TCP_TIMEOUT_FALLBACK);
345 extern struct proto tcp_prot;
347 #define TCP_INC_STATS(net, field) SNMP_INC_STATS((net)->mib.tcp_statistics, field)
348 #define TCP_INC_STATS_BH(net, field) SNMP_INC_STATS_BH((net)->mib.tcp_statistics, field)
349 #define TCP_DEC_STATS(net, field) SNMP_DEC_STATS((net)->mib.tcp_statistics, field)
350 #define TCP_ADD_STATS_USER(net, field, val) SNMP_ADD_STATS_USER((net)->mib.tcp_statistics, field, val)
351 #define TCP_ADD_STATS(net, field, val) SNMP_ADD_STATS((net)->mib.tcp_statistics, field, val)
353 void tcp_tasklet_init(void);
355 void tcp_v4_err(struct sk_buff *skb, u32);
357 void tcp_shutdown(struct sock *sk, int how);
359 void tcp_v4_early_demux(struct sk_buff *skb);
360 int tcp_v4_rcv(struct sk_buff *skb);
362 int tcp_v4_tw_remember_stamp(struct inet_timewait_sock *tw);
363 int tcp_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
365 int tcp_sendpage(struct sock *sk, struct page *page, int offset, size_t size,
367 void tcp_release_cb(struct sock *sk);
368 void tcp_wfree(struct sk_buff *skb);
369 void tcp_write_timer_handler(struct sock *sk);
370 void tcp_delack_timer_handler(struct sock *sk);
371 int tcp_ioctl(struct sock *sk, int cmd, unsigned long arg);
372 int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb,
373 const struct tcphdr *th, unsigned int len);
374 void tcp_rcv_established(struct sock *sk, struct sk_buff *skb,
375 const struct tcphdr *th, unsigned int len);
376 void tcp_rcv_space_adjust(struct sock *sk);
377 void tcp_cleanup_rbuf(struct sock *sk, int copied);
378 int tcp_twsk_unique(struct sock *sk, struct sock *sktw, void *twp);
379 void tcp_twsk_destructor(struct sock *sk);
380 ssize_t tcp_splice_read(struct socket *sk, loff_t *ppos,
381 struct pipe_inode_info *pipe, size_t len,
384 static inline void tcp_dec_quickack_mode(struct sock *sk,
385 const unsigned int pkts)
387 struct inet_connection_sock *icsk = inet_csk(sk);
389 if (icsk->icsk_ack.quick) {
390 if (pkts >= icsk->icsk_ack.quick) {
391 icsk->icsk_ack.quick = 0;
392 /* Leaving quickack mode we deflate ATO. */
393 icsk->icsk_ack.ato = TCP_ATO_MIN;
395 icsk->icsk_ack.quick -= pkts;
400 #define TCP_ECN_QUEUE_CWR 2
401 #define TCP_ECN_DEMAND_CWR 4
402 #define TCP_ECN_SEEN 8
412 enum tcp_tw_status tcp_timewait_state_process(struct inet_timewait_sock *tw,
414 const struct tcphdr *th);
415 struct sock *tcp_check_req(struct sock *sk, struct sk_buff *skb,
416 struct request_sock *req, struct request_sock **prev,
418 int tcp_child_process(struct sock *parent, struct sock *child,
419 struct sk_buff *skb);
420 void tcp_enter_loss(struct sock *sk, int how);
421 void tcp_clear_retrans(struct tcp_sock *tp);
422 void tcp_update_metrics(struct sock *sk);
423 void tcp_init_metrics(struct sock *sk);
424 void tcp_metrics_init(void);
425 bool tcp_peer_is_proven(struct request_sock *req, struct dst_entry *dst,
427 bool tcp_remember_stamp(struct sock *sk);
428 bool tcp_tw_remember_stamp(struct inet_timewait_sock *tw);
429 void tcp_fetch_timewait_stamp(struct sock *sk, struct dst_entry *dst);
430 void tcp_disable_fack(struct tcp_sock *tp);
431 void tcp_close(struct sock *sk, long timeout);
432 void tcp_init_sock(struct sock *sk);
433 unsigned int tcp_poll(struct file *file, struct socket *sock,
434 struct poll_table_struct *wait);
435 int tcp_getsockopt(struct sock *sk, int level, int optname,
436 char __user *optval, int __user *optlen);
437 int tcp_setsockopt(struct sock *sk, int level, int optname,
438 char __user *optval, unsigned int optlen);
439 int compat_tcp_getsockopt(struct sock *sk, int level, int optname,
440 char __user *optval, int __user *optlen);
441 int compat_tcp_setsockopt(struct sock *sk, int level, int optname,
442 char __user *optval, unsigned int optlen);
443 void tcp_set_keepalive(struct sock *sk, int val);
444 void tcp_syn_ack_timeout(struct sock *sk, struct request_sock *req);
445 int tcp_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
446 size_t len, int nonblock, int flags, int *addr_len);
447 void tcp_parse_options(const struct sk_buff *skb,
448 struct tcp_options_received *opt_rx,
449 int estab, struct tcp_fastopen_cookie *foc);
450 const u8 *tcp_parse_md5sig_option(const struct tcphdr *th);
453 * TCP v4 functions exported for the inet6 API
456 void tcp_v4_send_check(struct sock *sk, struct sk_buff *skb);
457 int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb);
458 struct sock *tcp_create_openreq_child(struct sock *sk,
459 struct request_sock *req,
460 struct sk_buff *skb);
461 struct sock *tcp_v4_syn_recv_sock(struct sock *sk, struct sk_buff *skb,
462 struct request_sock *req,
463 struct dst_entry *dst);
464 int tcp_v4_do_rcv(struct sock *sk, struct sk_buff *skb);
465 int tcp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len);
466 int tcp_connect(struct sock *sk);
467 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 int tcp_disconnect(struct sock *sk, int flags);
472 void tcp_finish_connect(struct sock *sk, struct sk_buff *skb);
473 int tcp_send_rcvq(struct sock *sk, struct msghdr *msg, size_t size);
474 void inet_sk_rx_dst_set(struct sock *sk, const struct sk_buff *skb);
476 /* From syncookies.c */
477 int __cookie_v4_check(const struct iphdr *iph, const struct tcphdr *th,
479 struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb,
480 struct ip_options *opt);
481 #ifdef CONFIG_SYN_COOKIES
483 /* Syncookies use a monotonic timer which increments every 64 seconds.
484 * This counter is used both as a hash input and partially encoded into
485 * the cookie value. A cookie is only validated further if the delta
486 * between the current counter value and the encoded one is less than this,
487 * i.e. a sent cookie is valid only at most for 128 seconds (or less if
488 * the counter advances immediately after a cookie is generated).
490 #define MAX_SYNCOOKIE_AGE 2
492 static inline u32 tcp_cookie_time(void)
495 getnstimeofday(&now);
496 return now.tv_sec >> 6; /* 64 seconds granularity */
499 u32 __cookie_v4_init_sequence(const struct iphdr *iph, const struct tcphdr *th,
501 __u32 cookie_v4_init_sequence(struct sock *sk, struct sk_buff *skb, __u16 *mss);
503 static inline __u32 cookie_v4_init_sequence(struct sock *sk,
511 __u32 cookie_init_timestamp(struct request_sock *req);
512 bool cookie_check_timestamp(struct tcp_options_received *opt, struct net *net,
515 /* From net/ipv6/syncookies.c */
516 int __cookie_v6_check(const struct ipv6hdr *iph, const struct tcphdr *th,
518 struct sock *cookie_v6_check(struct sock *sk, struct sk_buff *skb);
519 #ifdef CONFIG_SYN_COOKIES
520 u32 __cookie_v6_init_sequence(const struct ipv6hdr *iph,
521 const struct tcphdr *th, u16 *mssp);
522 __u32 cookie_v6_init_sequence(struct sock *sk, const struct sk_buff *skb,
525 static inline __u32 cookie_v6_init_sequence(struct sock *sk,
534 void __tcp_push_pending_frames(struct sock *sk, unsigned int cur_mss,
536 bool tcp_may_send_now(struct sock *sk);
537 int __tcp_retransmit_skb(struct sock *, struct sk_buff *);
538 int tcp_retransmit_skb(struct sock *, struct sk_buff *);
539 void tcp_retransmit_timer(struct sock *sk);
540 void tcp_xmit_retransmit_queue(struct sock *);
541 void tcp_simple_retransmit(struct sock *);
542 int tcp_trim_head(struct sock *, struct sk_buff *, u32);
543 int tcp_fragment(struct sock *, struct sk_buff *, u32, unsigned int);
545 void tcp_send_probe0(struct sock *);
546 void tcp_send_partial(struct sock *);
547 int tcp_write_wakeup(struct sock *);
548 void tcp_send_fin(struct sock *sk);
549 void tcp_send_active_reset(struct sock *sk, gfp_t priority);
550 int tcp_send_synack(struct sock *);
551 bool tcp_syn_flood_action(struct sock *sk, const struct sk_buff *skb,
553 void tcp_push_one(struct sock *, unsigned int mss_now);
554 void tcp_send_ack(struct sock *sk);
555 void tcp_send_delayed_ack(struct sock *sk);
556 void tcp_send_loss_probe(struct sock *sk);
557 bool tcp_schedule_loss_probe(struct sock *sk);
560 void tcp_cwnd_application_limited(struct sock *sk);
561 void tcp_resume_early_retransmit(struct sock *sk);
562 void tcp_rearm_rto(struct sock *sk);
563 void tcp_reset(struct sock *sk);
566 void tcp_init_xmit_timers(struct sock *);
567 static inline void tcp_clear_xmit_timers(struct sock *sk)
569 inet_csk_clear_xmit_timers(sk);
572 unsigned int tcp_sync_mss(struct sock *sk, u32 pmtu);
573 unsigned int tcp_current_mss(struct sock *sk);
575 /* Bound MSS / TSO packet size with the half of the window */
576 static inline int tcp_bound_to_half_wnd(struct tcp_sock *tp, int pktsize)
580 /* When peer uses tiny windows, there is no use in packetizing
581 * to sub-MSS pieces for the sake of SWS or making sure there
582 * are enough packets in the pipe for fast recovery.
584 * On the other hand, for extremely large MSS devices, handling
585 * smaller than MSS windows in this way does make sense.
587 if (tp->max_window >= 512)
588 cutoff = (tp->max_window >> 1);
590 cutoff = tp->max_window;
592 if (cutoff && pktsize > cutoff)
593 return max_t(int, cutoff, 68U - tp->tcp_header_len);
599 void tcp_get_info(const struct sock *, struct tcp_info *);
601 /* Read 'sendfile()'-style from a TCP socket */
602 typedef int (*sk_read_actor_t)(read_descriptor_t *, struct sk_buff *,
603 unsigned int, size_t);
604 int tcp_read_sock(struct sock *sk, read_descriptor_t *desc,
605 sk_read_actor_t recv_actor);
607 void tcp_initialize_rcv_mss(struct sock *sk);
609 int tcp_mtu_to_mss(struct sock *sk, int pmtu);
610 int tcp_mss_to_mtu(struct sock *sk, int mss);
611 void tcp_mtup_init(struct sock *sk);
612 void tcp_init_buffer_space(struct sock *sk);
614 static inline void tcp_bound_rto(const struct sock *sk)
616 if (inet_csk(sk)->icsk_rto > TCP_RTO_MAX)
617 inet_csk(sk)->icsk_rto = TCP_RTO_MAX;
620 static inline u32 __tcp_set_rto(const struct tcp_sock *tp)
622 return usecs_to_jiffies((tp->srtt_us >> 3) + tp->rttvar_us);
625 static inline void __tcp_fast_path_on(struct tcp_sock *tp, u32 snd_wnd)
627 tp->pred_flags = htonl((tp->tcp_header_len << 26) |
628 ntohl(TCP_FLAG_ACK) |
632 static inline void tcp_fast_path_on(struct tcp_sock *tp)
634 __tcp_fast_path_on(tp, tp->snd_wnd >> tp->rx_opt.snd_wscale);
637 static inline void tcp_fast_path_check(struct sock *sk)
639 struct tcp_sock *tp = tcp_sk(sk);
641 if (skb_queue_empty(&tp->out_of_order_queue) &&
643 atomic_read(&sk->sk_rmem_alloc) < sk->sk_rcvbuf &&
645 tcp_fast_path_on(tp);
648 /* Compute the actual rto_min value */
649 static inline u32 tcp_rto_min(struct sock *sk)
651 const struct dst_entry *dst = __sk_dst_get(sk);
652 u32 rto_min = TCP_RTO_MIN;
654 if (dst && dst_metric_locked(dst, RTAX_RTO_MIN))
655 rto_min = dst_metric_rtt(dst, RTAX_RTO_MIN);
659 static inline u32 tcp_rto_min_us(struct sock *sk)
661 return jiffies_to_usecs(tcp_rto_min(sk));
664 /* Compute the actual receive window we are currently advertising.
665 * Rcv_nxt can be after the window if our peer push more data
666 * than the offered window.
668 static inline u32 tcp_receive_window(const struct tcp_sock *tp)
670 s32 win = tp->rcv_wup + tp->rcv_wnd - tp->rcv_nxt;
677 /* Choose a new window, without checks for shrinking, and without
678 * scaling applied to the result. The caller does these things
679 * if necessary. This is a "raw" window selection.
681 u32 __tcp_select_window(struct sock *sk);
683 void tcp_send_window_probe(struct sock *sk);
685 /* TCP timestamps are only 32-bits, this causes a slight
686 * complication on 64-bit systems since we store a snapshot
687 * of jiffies in the buffer control blocks below. We decided
688 * to use only the low 32-bits of jiffies and hide the ugly
689 * casts with the following macro.
691 #define tcp_time_stamp ((__u32)(jiffies))
693 #define tcp_flag_byte(th) (((u_int8_t *)th)[13])
695 #define TCPHDR_FIN 0x01
696 #define TCPHDR_SYN 0x02
697 #define TCPHDR_RST 0x04
698 #define TCPHDR_PSH 0x08
699 #define TCPHDR_ACK 0x10
700 #define TCPHDR_URG 0x20
701 #define TCPHDR_ECE 0x40
702 #define TCPHDR_CWR 0x80
704 /* This is what the send packet queuing engine uses to pass
705 * TCP per-packet control information to the transmission code.
706 * We also store the host-order sequence numbers in here too.
707 * This is 44 bytes if IPV6 is enabled.
708 * If this grows please adjust skbuff.h:skbuff->cb[xxx] size appropriately.
712 struct inet_skb_parm h4;
713 #if IS_ENABLED(CONFIG_IPV6)
714 struct inet6_skb_parm h6;
716 } header; /* For incoming frames */
717 __u32 seq; /* Starting sequence number */
718 __u32 end_seq; /* SEQ + FIN + SYN + datalen */
719 __u32 when; /* used to compute rtt's */
720 __u8 tcp_flags; /* TCP header flags. (tcp[13]) */
722 __u8 sacked; /* State flags for SACK/FACK. */
723 #define TCPCB_SACKED_ACKED 0x01 /* SKB ACK'd by a SACK block */
724 #define TCPCB_SACKED_RETRANS 0x02 /* SKB retransmitted */
725 #define TCPCB_LOST 0x04 /* SKB is lost */
726 #define TCPCB_TAGBITS 0x07 /* All tag bits */
727 #define TCPCB_EVER_RETRANS 0x80 /* Ever retransmitted frame */
728 #define TCPCB_RETRANS (TCPCB_SACKED_RETRANS|TCPCB_EVER_RETRANS)
730 __u8 ip_dsfield; /* IPv4 tos or IPv6 dsfield */
732 __u32 ack_seq; /* Sequence number ACK'd */
735 #define TCP_SKB_CB(__skb) ((struct tcp_skb_cb *)&((__skb)->cb[0]))
737 /* RFC3168 : 6.1.1 SYN packets must not have ECT/ECN bits set
739 * If we receive a SYN packet with these bits set, it means a network is
740 * playing bad games with TOS bits. In order to avoid possible false congestion
741 * notifications, we disable TCP ECN negociation.
744 TCP_ECN_create_request(struct request_sock *req, const struct sk_buff *skb,
747 const struct tcphdr *th = tcp_hdr(skb);
749 if (net->ipv4.sysctl_tcp_ecn && th->ece && th->cwr &&
750 INET_ECN_is_not_ect(TCP_SKB_CB(skb)->ip_dsfield))
751 inet_rsk(req)->ecn_ok = 1;
754 /* Due to TSO, an SKB can be composed of multiple actual
755 * packets. To keep these tracked properly, we use this.
757 static inline int tcp_skb_pcount(const struct sk_buff *skb)
759 return skb_shinfo(skb)->gso_segs;
762 /* This is valid iff tcp_skb_pcount() > 1. */
763 static inline int tcp_skb_mss(const struct sk_buff *skb)
765 return skb_shinfo(skb)->gso_size;
768 /* Events passed to congestion control interface */
770 CA_EVENT_TX_START, /* first transmit when no packets in flight */
771 CA_EVENT_CWND_RESTART, /* congestion window restart */
772 CA_EVENT_COMPLETE_CWR, /* end of congestion recovery */
773 CA_EVENT_LOSS, /* loss timeout */
774 CA_EVENT_FAST_ACK, /* in sequence ack */
775 CA_EVENT_SLOW_ACK, /* other ack */
779 * Interface for adding new TCP congestion control handlers
781 #define TCP_CA_NAME_MAX 16
782 #define TCP_CA_MAX 128
783 #define TCP_CA_BUF_MAX (TCP_CA_NAME_MAX*TCP_CA_MAX)
785 #define TCP_CONG_NON_RESTRICTED 0x1
787 struct tcp_congestion_ops {
788 struct list_head list;
791 /* initialize private data (optional) */
792 void (*init)(struct sock *sk);
793 /* cleanup private data (optional) */
794 void (*release)(struct sock *sk);
796 /* return slow start threshold (required) */
797 u32 (*ssthresh)(struct sock *sk);
798 /* do new cwnd calculation (required) */
799 void (*cong_avoid)(struct sock *sk, u32 ack, u32 acked, u32 in_flight);
800 /* call before changing ca_state (optional) */
801 void (*set_state)(struct sock *sk, u8 new_state);
802 /* call when cwnd event occurs (optional) */
803 void (*cwnd_event)(struct sock *sk, enum tcp_ca_event ev);
804 /* new value of cwnd after loss (optional) */
805 u32 (*undo_cwnd)(struct sock *sk);
806 /* hook for packet ack accounting (optional) */
807 void (*pkts_acked)(struct sock *sk, u32 num_acked, s32 rtt_us);
808 /* get info for inet_diag (optional) */
809 void (*get_info)(struct sock *sk, u32 ext, struct sk_buff *skb);
811 char name[TCP_CA_NAME_MAX];
812 struct module *owner;
815 int tcp_register_congestion_control(struct tcp_congestion_ops *type);
816 void tcp_unregister_congestion_control(struct tcp_congestion_ops *type);
818 void tcp_init_congestion_control(struct sock *sk);
819 void tcp_cleanup_congestion_control(struct sock *sk);
820 int tcp_set_default_congestion_control(const char *name);
821 void tcp_get_default_congestion_control(char *name);
822 void tcp_get_available_congestion_control(char *buf, size_t len);
823 void tcp_get_allowed_congestion_control(char *buf, size_t len);
824 int tcp_set_allowed_congestion_control(char *allowed);
825 int tcp_set_congestion_control(struct sock *sk, const char *name);
826 int tcp_slow_start(struct tcp_sock *tp, u32 acked);
827 void tcp_cong_avoid_ai(struct tcp_sock *tp, u32 w);
829 extern struct tcp_congestion_ops tcp_init_congestion_ops;
830 u32 tcp_reno_ssthresh(struct sock *sk);
831 void tcp_reno_cong_avoid(struct sock *sk, u32 ack, u32 acked, u32 in_flight);
832 extern struct tcp_congestion_ops tcp_reno;
834 static inline void tcp_set_ca_state(struct sock *sk, const u8 ca_state)
836 struct inet_connection_sock *icsk = inet_csk(sk);
838 if (icsk->icsk_ca_ops->set_state)
839 icsk->icsk_ca_ops->set_state(sk, ca_state);
840 icsk->icsk_ca_state = ca_state;
843 static inline void tcp_ca_event(struct sock *sk, const enum tcp_ca_event event)
845 const struct inet_connection_sock *icsk = inet_csk(sk);
847 if (icsk->icsk_ca_ops->cwnd_event)
848 icsk->icsk_ca_ops->cwnd_event(sk, event);
851 /* These functions determine how the current flow behaves in respect of SACK
852 * handling. SACK is negotiated with the peer, and therefore it can vary
853 * between different flows.
855 * tcp_is_sack - SACK enabled
856 * tcp_is_reno - No SACK
857 * tcp_is_fack - FACK enabled, implies SACK enabled
859 static inline int tcp_is_sack(const struct tcp_sock *tp)
861 return tp->rx_opt.sack_ok;
864 static inline bool tcp_is_reno(const struct tcp_sock *tp)
866 return !tcp_is_sack(tp);
869 static inline bool tcp_is_fack(const struct tcp_sock *tp)
871 return tp->rx_opt.sack_ok & TCP_FACK_ENABLED;
874 static inline void tcp_enable_fack(struct tcp_sock *tp)
876 tp->rx_opt.sack_ok |= TCP_FACK_ENABLED;
879 /* TCP early-retransmit (ER) is similar to but more conservative than
880 * the thin-dupack feature. Enable ER only if thin-dupack is disabled.
882 static inline void tcp_enable_early_retrans(struct tcp_sock *tp)
884 tp->do_early_retrans = sysctl_tcp_early_retrans &&
885 sysctl_tcp_early_retrans < 4 && !sysctl_tcp_thin_dupack &&
886 sysctl_tcp_reordering == 3;
889 static inline void tcp_disable_early_retrans(struct tcp_sock *tp)
891 tp->do_early_retrans = 0;
894 static inline unsigned int tcp_left_out(const struct tcp_sock *tp)
896 return tp->sacked_out + tp->lost_out;
899 /* This determines how many packets are "in the network" to the best
900 * of our knowledge. In many cases it is conservative, but where
901 * detailed information is available from the receiver (via SACK
902 * blocks etc.) we can make more aggressive calculations.
904 * Use this for decisions involving congestion control, use just
905 * tp->packets_out to determine if the send queue is empty or not.
907 * Read this equation as:
909 * "Packets sent once on transmission queue" MINUS
910 * "Packets left network, but not honestly ACKed yet" PLUS
911 * "Packets fast retransmitted"
913 static inline unsigned int tcp_packets_in_flight(const struct tcp_sock *tp)
915 return tp->packets_out - tcp_left_out(tp) + tp->retrans_out;
918 #define TCP_INFINITE_SSTHRESH 0x7fffffff
920 static inline bool tcp_in_initial_slowstart(const struct tcp_sock *tp)
922 return tp->snd_ssthresh >= TCP_INFINITE_SSTHRESH;
925 static inline bool tcp_in_cwnd_reduction(const struct sock *sk)
927 return (TCPF_CA_CWR | TCPF_CA_Recovery) &
928 (1 << inet_csk(sk)->icsk_ca_state);
931 /* If cwnd > ssthresh, we may raise ssthresh to be half-way to cwnd.
932 * The exception is cwnd reduction phase, when cwnd is decreasing towards
935 static inline __u32 tcp_current_ssthresh(const struct sock *sk)
937 const struct tcp_sock *tp = tcp_sk(sk);
939 if (tcp_in_cwnd_reduction(sk))
940 return tp->snd_ssthresh;
942 return max(tp->snd_ssthresh,
943 ((tp->snd_cwnd >> 1) +
944 (tp->snd_cwnd >> 2)));
947 /* Use define here intentionally to get WARN_ON location shown at the caller */
948 #define tcp_verify_left_out(tp) WARN_ON(tcp_left_out(tp) > tp->packets_out)
950 void tcp_enter_cwr(struct sock *sk, const int set_ssthresh);
951 __u32 tcp_init_cwnd(const struct tcp_sock *tp, const struct dst_entry *dst);
953 /* The maximum number of MSS of available cwnd for which TSO defers
954 * sending if not using sysctl_tcp_tso_win_divisor.
956 static inline __u32 tcp_max_tso_deferred_mss(const struct tcp_sock *tp)
961 /* Slow start with delack produces 3 packets of burst, so that
962 * it is safe "de facto". This will be the default - same as
963 * the default reordering threshold - but if reordering increases,
964 * we must be able to allow cwnd to burst at least this much in order
965 * to not pull it back when holes are filled.
967 static __inline__ __u32 tcp_max_burst(const struct tcp_sock *tp)
969 return tp->reordering;
972 /* Returns end sequence number of the receiver's advertised window */
973 static inline u32 tcp_wnd_end(const struct tcp_sock *tp)
975 return tp->snd_una + tp->snd_wnd;
977 bool tcp_is_cwnd_limited(const struct sock *sk, u32 in_flight);
979 static inline void tcp_check_probe_timer(struct sock *sk)
981 const struct tcp_sock *tp = tcp_sk(sk);
982 const struct inet_connection_sock *icsk = inet_csk(sk);
984 if (!tp->packets_out && !icsk->icsk_pending)
985 inet_csk_reset_xmit_timer(sk, ICSK_TIME_PROBE0,
986 icsk->icsk_rto, TCP_RTO_MAX);
989 static inline void tcp_init_wl(struct tcp_sock *tp, u32 seq)
994 static inline void tcp_update_wl(struct tcp_sock *tp, u32 seq)
1000 * Calculate(/check) TCP checksum
1002 static inline __sum16 tcp_v4_check(int len, __be32 saddr,
1003 __be32 daddr, __wsum base)
1005 return csum_tcpudp_magic(saddr,daddr,len,IPPROTO_TCP,base);
1008 static inline __sum16 __tcp_checksum_complete(struct sk_buff *skb)
1010 return __skb_checksum_complete(skb);
1013 static inline bool tcp_checksum_complete(struct sk_buff *skb)
1015 return !skb_csum_unnecessary(skb) &&
1016 __tcp_checksum_complete(skb);
1019 /* Prequeue for VJ style copy to user, combined with checksumming. */
1021 static inline void tcp_prequeue_init(struct tcp_sock *tp)
1023 tp->ucopy.task = NULL;
1025 tp->ucopy.memory = 0;
1026 skb_queue_head_init(&tp->ucopy.prequeue);
1027 #ifdef CONFIG_NET_DMA
1028 tp->ucopy.dma_chan = NULL;
1029 tp->ucopy.wakeup = 0;
1030 tp->ucopy.pinned_list = NULL;
1031 tp->ucopy.dma_cookie = 0;
1035 bool tcp_prequeue(struct sock *sk, struct sk_buff *skb);
1040 static const char *statename[]={
1041 "Unused","Established","Syn Sent","Syn Recv",
1042 "Fin Wait 1","Fin Wait 2","Time Wait", "Close",
1043 "Close Wait","Last ACK","Listen","Closing"
1046 void tcp_set_state(struct sock *sk, int state);
1048 void tcp_done(struct sock *sk);
1050 static inline void tcp_sack_reset(struct tcp_options_received *rx_opt)
1053 rx_opt->num_sacks = 0;
1056 u32 tcp_default_init_rwnd(u32 mss);
1058 /* Determine a window scaling and initial window to offer. */
1059 void tcp_select_initial_window(int __space, __u32 mss, __u32 *rcv_wnd,
1060 __u32 *window_clamp, int wscale_ok,
1061 __u8 *rcv_wscale, __u32 init_rcv_wnd);
1063 static inline int tcp_win_from_space(int space)
1065 return sysctl_tcp_adv_win_scale<=0 ?
1066 (space>>(-sysctl_tcp_adv_win_scale)) :
1067 space - (space>>sysctl_tcp_adv_win_scale);
1070 /* Note: caller must be prepared to deal with negative returns */
1071 static inline int tcp_space(const struct sock *sk)
1073 return tcp_win_from_space(sk->sk_rcvbuf -
1074 atomic_read(&sk->sk_rmem_alloc));
1077 static inline int tcp_full_space(const struct sock *sk)
1079 return tcp_win_from_space(sk->sk_rcvbuf);
1082 static inline void tcp_openreq_init(struct request_sock *req,
1083 struct tcp_options_received *rx_opt,
1084 struct sk_buff *skb)
1086 struct inet_request_sock *ireq = inet_rsk(req);
1088 req->rcv_wnd = 0; /* So that tcp_send_synack() knows! */
1090 tcp_rsk(req)->rcv_isn = TCP_SKB_CB(skb)->seq;
1091 tcp_rsk(req)->rcv_nxt = TCP_SKB_CB(skb)->seq + 1;
1092 tcp_rsk(req)->snt_synack = 0;
1093 req->mss = rx_opt->mss_clamp;
1094 req->ts_recent = rx_opt->saw_tstamp ? rx_opt->rcv_tsval : 0;
1095 ireq->tstamp_ok = rx_opt->tstamp_ok;
1096 ireq->sack_ok = rx_opt->sack_ok;
1097 ireq->snd_wscale = rx_opt->snd_wscale;
1098 ireq->wscale_ok = rx_opt->wscale_ok;
1101 ireq->ir_rmt_port = tcp_hdr(skb)->source;
1102 ireq->ir_num = ntohs(tcp_hdr(skb)->dest);
1105 void tcp_enter_memory_pressure(struct sock *sk);
1107 static inline int keepalive_intvl_when(const struct tcp_sock *tp)
1109 return tp->keepalive_intvl ? : sysctl_tcp_keepalive_intvl;
1112 static inline int keepalive_time_when(const struct tcp_sock *tp)
1114 return tp->keepalive_time ? : sysctl_tcp_keepalive_time;
1117 static inline int keepalive_probes(const struct tcp_sock *tp)
1119 return tp->keepalive_probes ? : sysctl_tcp_keepalive_probes;
1122 static inline u32 keepalive_time_elapsed(const struct tcp_sock *tp)
1124 const struct inet_connection_sock *icsk = &tp->inet_conn;
1126 return min_t(u32, tcp_time_stamp - icsk->icsk_ack.lrcvtime,
1127 tcp_time_stamp - tp->rcv_tstamp);
1130 static inline int tcp_fin_time(const struct sock *sk)
1132 int fin_timeout = tcp_sk(sk)->linger2 ? : sysctl_tcp_fin_timeout;
1133 const int rto = inet_csk(sk)->icsk_rto;
1135 if (fin_timeout < (rto << 2) - (rto >> 1))
1136 fin_timeout = (rto << 2) - (rto >> 1);
1141 static inline bool tcp_paws_check(const struct tcp_options_received *rx_opt,
1144 if ((s32)(rx_opt->ts_recent - rx_opt->rcv_tsval) <= paws_win)
1146 if (unlikely(get_seconds() >= rx_opt->ts_recent_stamp + TCP_PAWS_24DAYS))
1149 * Some OSes send SYN and SYNACK messages with tsval=0 tsecr=0,
1150 * then following tcp messages have valid values. Ignore 0 value,
1151 * or else 'negative' tsval might forbid us to accept their packets.
1153 if (!rx_opt->ts_recent)
1158 static inline bool tcp_paws_reject(const struct tcp_options_received *rx_opt,
1161 if (tcp_paws_check(rx_opt, 0))
1164 /* RST segments are not recommended to carry timestamp,
1165 and, if they do, it is recommended to ignore PAWS because
1166 "their cleanup function should take precedence over timestamps."
1167 Certainly, it is mistake. It is necessary to understand the reasons
1168 of this constraint to relax it: if peer reboots, clock may go
1169 out-of-sync and half-open connections will not be reset.
1170 Actually, the problem would be not existing if all
1171 the implementations followed draft about maintaining clock
1172 via reboots. Linux-2.2 DOES NOT!
1174 However, we can relax time bounds for RST segments to MSL.
1176 if (rst && get_seconds() >= rx_opt->ts_recent_stamp + TCP_PAWS_MSL)
1181 static inline void tcp_mib_init(struct net *net)
1184 TCP_ADD_STATS_USER(net, TCP_MIB_RTOALGORITHM, 1);
1185 TCP_ADD_STATS_USER(net, TCP_MIB_RTOMIN, TCP_RTO_MIN*1000/HZ);
1186 TCP_ADD_STATS_USER(net, TCP_MIB_RTOMAX, TCP_RTO_MAX*1000/HZ);
1187 TCP_ADD_STATS_USER(net, TCP_MIB_MAXCONN, -1);
1191 static inline void tcp_clear_retrans_hints_partial(struct tcp_sock *tp)
1193 tp->lost_skb_hint = NULL;
1196 static inline void tcp_clear_all_retrans_hints(struct tcp_sock *tp)
1198 tcp_clear_retrans_hints_partial(tp);
1199 tp->retransmit_skb_hint = NULL;
1205 union tcp_md5_addr {
1207 #if IS_ENABLED(CONFIG_IPV6)
1212 /* - key database */
1213 struct tcp_md5sig_key {
1214 struct hlist_node node;
1216 u8 family; /* AF_INET or AF_INET6 */
1217 union tcp_md5_addr addr;
1218 u8 key[TCP_MD5SIG_MAXKEYLEN];
1219 struct rcu_head rcu;
1223 struct tcp_md5sig_info {
1224 struct hlist_head head;
1225 struct rcu_head rcu;
1228 /* - pseudo header */
1229 struct tcp4_pseudohdr {
1237 struct tcp6_pseudohdr {
1238 struct in6_addr saddr;
1239 struct in6_addr daddr;
1241 __be32 protocol; /* including padding */
1244 union tcp_md5sum_block {
1245 struct tcp4_pseudohdr ip4;
1246 #if IS_ENABLED(CONFIG_IPV6)
1247 struct tcp6_pseudohdr ip6;
1251 /* - pool: digest algorithm, hash description and scratch buffer */
1252 struct tcp_md5sig_pool {
1253 struct hash_desc md5_desc;
1254 union tcp_md5sum_block md5_blk;
1258 int tcp_v4_md5_hash_skb(char *md5_hash, struct tcp_md5sig_key *key,
1259 const struct sock *sk, const struct request_sock *req,
1260 const struct sk_buff *skb);
1261 int tcp_md5_do_add(struct sock *sk, const union tcp_md5_addr *addr,
1262 int family, const u8 *newkey, u8 newkeylen, gfp_t gfp);
1263 int tcp_md5_do_del(struct sock *sk, const union tcp_md5_addr *addr,
1265 struct tcp_md5sig_key *tcp_v4_md5_lookup(struct sock *sk,
1266 struct sock *addr_sk);
1268 #ifdef CONFIG_TCP_MD5SIG
1269 struct tcp_md5sig_key *tcp_md5_do_lookup(struct sock *sk,
1270 const union tcp_md5_addr *addr,
1272 #define tcp_twsk_md5_key(twsk) ((twsk)->tw_md5_key)
1274 static inline struct tcp_md5sig_key *tcp_md5_do_lookup(struct sock *sk,
1275 const union tcp_md5_addr *addr,
1280 #define tcp_twsk_md5_key(twsk) NULL
1283 bool tcp_alloc_md5sig_pool(void);
1285 struct tcp_md5sig_pool *tcp_get_md5sig_pool(void);
1286 static inline void tcp_put_md5sig_pool(void)
1291 int tcp_md5_hash_header(struct tcp_md5sig_pool *, const struct tcphdr *);
1292 int tcp_md5_hash_skb_data(struct tcp_md5sig_pool *, const struct sk_buff *,
1293 unsigned int header_len);
1294 int tcp_md5_hash_key(struct tcp_md5sig_pool *hp,
1295 const struct tcp_md5sig_key *key);
1297 /* From tcp_fastopen.c */
1298 void tcp_fastopen_cache_get(struct sock *sk, u16 *mss,
1299 struct tcp_fastopen_cookie *cookie, int *syn_loss,
1300 unsigned long *last_syn_loss);
1301 void tcp_fastopen_cache_set(struct sock *sk, u16 mss,
1302 struct tcp_fastopen_cookie *cookie, bool syn_lost);
1303 struct tcp_fastopen_request {
1304 /* Fast Open cookie. Size 0 means a cookie request */
1305 struct tcp_fastopen_cookie cookie;
1306 struct msghdr *data; /* data in MSG_FASTOPEN */
1308 int copied; /* queued in tcp_connect() */
1310 void tcp_free_fastopen_req(struct tcp_sock *tp);
1312 extern struct tcp_fastopen_context __rcu *tcp_fastopen_ctx;
1313 int tcp_fastopen_reset_cipher(void *key, unsigned int len);
1314 void tcp_fastopen_cookie_gen(__be32 src, __be32 dst,
1315 struct tcp_fastopen_cookie *foc);
1316 void tcp_fastopen_init_key_once(bool publish);
1317 #define TCP_FASTOPEN_KEY_LENGTH 16
1319 /* Fastopen key context */
1320 struct tcp_fastopen_context {
1321 struct crypto_cipher *tfm;
1322 __u8 key[TCP_FASTOPEN_KEY_LENGTH];
1323 struct rcu_head rcu;
1326 /* write queue abstraction */
1327 static inline void tcp_write_queue_purge(struct sock *sk)
1329 struct sk_buff *skb;
1331 while ((skb = __skb_dequeue(&sk->sk_write_queue)) != NULL)
1332 sk_wmem_free_skb(sk, skb);
1334 tcp_clear_all_retrans_hints(tcp_sk(sk));
1337 static inline struct sk_buff *tcp_write_queue_head(const struct sock *sk)
1339 return skb_peek(&sk->sk_write_queue);
1342 static inline struct sk_buff *tcp_write_queue_tail(const struct sock *sk)
1344 return skb_peek_tail(&sk->sk_write_queue);
1347 static inline struct sk_buff *tcp_write_queue_next(const struct sock *sk,
1348 const struct sk_buff *skb)
1350 return skb_queue_next(&sk->sk_write_queue, skb);
1353 static inline struct sk_buff *tcp_write_queue_prev(const struct sock *sk,
1354 const struct sk_buff *skb)
1356 return skb_queue_prev(&sk->sk_write_queue, skb);
1359 #define tcp_for_write_queue(skb, sk) \
1360 skb_queue_walk(&(sk)->sk_write_queue, skb)
1362 #define tcp_for_write_queue_from(skb, sk) \
1363 skb_queue_walk_from(&(sk)->sk_write_queue, skb)
1365 #define tcp_for_write_queue_from_safe(skb, tmp, sk) \
1366 skb_queue_walk_from_safe(&(sk)->sk_write_queue, skb, tmp)
1368 static inline struct sk_buff *tcp_send_head(const struct sock *sk)
1370 return sk->sk_send_head;
1373 static inline bool tcp_skb_is_last(const struct sock *sk,
1374 const struct sk_buff *skb)
1376 return skb_queue_is_last(&sk->sk_write_queue, skb);
1379 static inline void tcp_advance_send_head(struct sock *sk, const struct sk_buff *skb)
1381 if (tcp_skb_is_last(sk, skb))
1382 sk->sk_send_head = NULL;
1384 sk->sk_send_head = tcp_write_queue_next(sk, skb);
1387 static inline void tcp_check_send_head(struct sock *sk, struct sk_buff *skb_unlinked)
1389 if (sk->sk_send_head == skb_unlinked)
1390 sk->sk_send_head = NULL;
1393 static inline void tcp_init_send_head(struct sock *sk)
1395 sk->sk_send_head = NULL;
1398 static inline void __tcp_add_write_queue_tail(struct sock *sk, struct sk_buff *skb)
1400 __skb_queue_tail(&sk->sk_write_queue, skb);
1403 static inline void tcp_add_write_queue_tail(struct sock *sk, struct sk_buff *skb)
1405 __tcp_add_write_queue_tail(sk, skb);
1407 /* Queue it, remembering where we must start sending. */
1408 if (sk->sk_send_head == NULL) {
1409 sk->sk_send_head = skb;
1411 if (tcp_sk(sk)->highest_sack == NULL)
1412 tcp_sk(sk)->highest_sack = skb;
1416 static inline void __tcp_add_write_queue_head(struct sock *sk, struct sk_buff *skb)
1418 __skb_queue_head(&sk->sk_write_queue, skb);
1421 /* Insert buff after skb on the write queue of sk. */
1422 static inline void tcp_insert_write_queue_after(struct sk_buff *skb,
1423 struct sk_buff *buff,
1426 __skb_queue_after(&sk->sk_write_queue, skb, buff);
1429 /* Insert new before skb on the write queue of sk. */
1430 static inline void tcp_insert_write_queue_before(struct sk_buff *new,
1431 struct sk_buff *skb,
1434 __skb_queue_before(&sk->sk_write_queue, skb, new);
1436 if (sk->sk_send_head == skb)
1437 sk->sk_send_head = new;
1440 static inline void tcp_unlink_write_queue(struct sk_buff *skb, struct sock *sk)
1442 __skb_unlink(skb, &sk->sk_write_queue);
1445 static inline bool tcp_write_queue_empty(struct sock *sk)
1447 return skb_queue_empty(&sk->sk_write_queue);
1450 static inline void tcp_push_pending_frames(struct sock *sk)
1452 if (tcp_send_head(sk)) {
1453 struct tcp_sock *tp = tcp_sk(sk);
1455 __tcp_push_pending_frames(sk, tcp_current_mss(sk), tp->nonagle);
1459 /* Start sequence of the skb just after the highest skb with SACKed
1460 * bit, valid only if sacked_out > 0 or when the caller has ensured
1461 * validity by itself.
1463 static inline u32 tcp_highest_sack_seq(struct tcp_sock *tp)
1465 if (!tp->sacked_out)
1468 if (tp->highest_sack == NULL)
1471 return TCP_SKB_CB(tp->highest_sack)->seq;
1474 static inline void tcp_advance_highest_sack(struct sock *sk, struct sk_buff *skb)
1476 tcp_sk(sk)->highest_sack = tcp_skb_is_last(sk, skb) ? NULL :
1477 tcp_write_queue_next(sk, skb);
1480 static inline struct sk_buff *tcp_highest_sack(struct sock *sk)
1482 return tcp_sk(sk)->highest_sack;
1485 static inline void tcp_highest_sack_reset(struct sock *sk)
1487 tcp_sk(sk)->highest_sack = tcp_write_queue_head(sk);
1490 /* Called when old skb is about to be deleted (to be combined with new skb) */
1491 static inline void tcp_highest_sack_combine(struct sock *sk,
1492 struct sk_buff *old,
1493 struct sk_buff *new)
1495 if (tcp_sk(sk)->sacked_out && (old == tcp_sk(sk)->highest_sack))
1496 tcp_sk(sk)->highest_sack = new;
1499 /* Determines whether this is a thin stream (which may suffer from
1500 * increased latency). Used to trigger latency-reducing mechanisms.
1502 static inline bool tcp_stream_is_thin(struct tcp_sock *tp)
1504 return tp->packets_out < 4 && !tcp_in_initial_slowstart(tp);
1508 enum tcp_seq_states {
1509 TCP_SEQ_STATE_LISTENING,
1510 TCP_SEQ_STATE_OPENREQ,
1511 TCP_SEQ_STATE_ESTABLISHED,
1514 int tcp_seq_open(struct inode *inode, struct file *file);
1516 struct tcp_seq_afinfo {
1519 const struct file_operations *seq_fops;
1520 struct seq_operations seq_ops;
1523 struct tcp_iter_state {
1524 struct seq_net_private p;
1526 enum tcp_seq_states state;
1527 struct sock *syn_wait_sk;
1528 int bucket, offset, sbucket, num;
1533 int tcp_proc_register(struct net *net, struct tcp_seq_afinfo *afinfo);
1534 void tcp_proc_unregister(struct net *net, struct tcp_seq_afinfo *afinfo);
1536 extern struct request_sock_ops tcp_request_sock_ops;
1537 extern struct request_sock_ops tcp6_request_sock_ops;
1539 void tcp_v4_destroy_sock(struct sock *sk);
1541 struct sk_buff *tcp_gso_segment(struct sk_buff *skb,
1542 netdev_features_t features);
1543 struct sk_buff **tcp_gro_receive(struct sk_buff **head, struct sk_buff *skb);
1544 int tcp_gro_complete(struct sk_buff *skb);
1546 void __tcp_v4_send_check(struct sk_buff *skb, __be32 saddr, __be32 daddr);
1548 static inline u32 tcp_notsent_lowat(const struct tcp_sock *tp)
1550 return tp->notsent_lowat ?: sysctl_tcp_notsent_lowat;
1553 static inline bool tcp_stream_memory_free(const struct sock *sk)
1555 const struct tcp_sock *tp = tcp_sk(sk);
1556 u32 notsent_bytes = tp->write_seq - tp->snd_nxt;
1558 return notsent_bytes < tcp_notsent_lowat(tp);
1561 #ifdef CONFIG_PROC_FS
1562 int tcp4_proc_init(void);
1563 void tcp4_proc_exit(void);
1566 /* TCP af-specific functions */
1567 struct tcp_sock_af_ops {
1568 #ifdef CONFIG_TCP_MD5SIG
1569 struct tcp_md5sig_key *(*md5_lookup) (struct sock *sk,
1570 struct sock *addr_sk);
1571 int (*calc_md5_hash) (char *location,
1572 struct tcp_md5sig_key *md5,
1573 const struct sock *sk,
1574 const struct request_sock *req,
1575 const struct sk_buff *skb);
1576 int (*md5_parse) (struct sock *sk,
1577 char __user *optval,
1582 struct tcp_request_sock_ops {
1583 #ifdef CONFIG_TCP_MD5SIG
1584 struct tcp_md5sig_key *(*md5_lookup) (struct sock *sk,
1585 struct request_sock *req);
1586 int (*calc_md5_hash) (char *location,
1587 struct tcp_md5sig_key *md5,
1588 const struct sock *sk,
1589 const struct request_sock *req,
1590 const struct sk_buff *skb);
1594 int tcpv4_offload_init(void);
1596 void tcp_v4_init(void);
1597 void tcp_init(void);