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 /* Offer an initial receive window of 10 mss. */
65 #define TCP_DEFAULT_INIT_RCVWND 10
67 /* Minimal accepted MSS. It is (60+60+8) - (20+20). */
68 #define TCP_MIN_MSS 88U
70 /* The least MTU to use for probing */
71 #define TCP_BASE_MSS 512
73 /* After receiving this amount of duplicate ACKs fast retransmit starts. */
74 #define TCP_FASTRETRANS_THRESH 3
76 /* Maximal reordering. */
77 #define TCP_MAX_REORDERING 127
79 /* Maximal number of ACKs sent quickly to accelerate slow-start. */
80 #define TCP_MAX_QUICKACKS 16U
83 #define TCP_URG_VALID 0x0100
84 #define TCP_URG_NOTYET 0x0200
85 #define TCP_URG_READ 0x0400
87 #define TCP_RETR1 3 /*
88 * This is how many retries it does before it
89 * tries to figure out if the gateway is
90 * down. Minimal RFC value is 3; it corresponds
91 * to ~3sec-8min depending on RTO.
94 #define TCP_RETR2 15 /*
95 * This should take at least
96 * 90 minutes to time out.
97 * RFC1122 says that the limit is 100 sec.
98 * 15 is ~13-30min depending on RTO.
101 #define TCP_SYN_RETRIES 5 /* number of times to retry active opening a
102 * connection: ~180sec is RFC minimum */
104 #define TCP_SYNACK_RETRIES 5 /* number of times to retry passive opening a
105 * connection: ~180sec is RFC minimum */
107 #define TCP_TIMEWAIT_LEN (60*HZ) /* how long to wait to destroy TIME-WAIT
108 * state, about 60 seconds */
109 #define TCP_FIN_TIMEOUT TCP_TIMEWAIT_LEN
110 /* BSD style FIN_WAIT2 deadlock breaker.
111 * It used to be 3min, new value is 60sec,
112 * to combine FIN-WAIT-2 timeout with
116 #define TCP_DELACK_MAX ((unsigned)(HZ/5)) /* maximal time to delay before sending an ACK */
118 #define TCP_DELACK_MIN ((unsigned)(HZ/25)) /* minimal time to delay before sending an ACK */
119 #define TCP_ATO_MIN ((unsigned)(HZ/25))
121 #define TCP_DELACK_MIN 4U
122 #define TCP_ATO_MIN 4U
124 #define TCP_RTO_MAX ((unsigned)(120*HZ))
125 #define TCP_RTO_MIN ((unsigned)(HZ/5))
126 #define TCP_TIMEOUT_INIT ((unsigned)(1*HZ)) /* RFC6298 2.1 initial RTO value */
127 #define TCP_TIMEOUT_FALLBACK ((unsigned)(3*HZ)) /* RFC 1122 initial RTO value, now
128 * used as a fallback RTO for the
129 * initial data transmission if no
130 * valid RTT sample has been acquired,
131 * most likely due to retrans in 3WHS.
134 #define TCP_RESOURCE_PROBE_INTERVAL ((unsigned)(HZ/2U)) /* Maximal interval between probes
135 * for local resources.
138 #define TCP_KEEPALIVE_TIME (120*60*HZ) /* two hours */
139 #define TCP_KEEPALIVE_PROBES 9 /* Max of 9 keepalive probes */
140 #define TCP_KEEPALIVE_INTVL (75*HZ)
142 #define MAX_TCP_KEEPIDLE 32767
143 #define MAX_TCP_KEEPINTVL 32767
144 #define MAX_TCP_KEEPCNT 127
145 #define MAX_TCP_SYNCNT 127
147 #define TCP_SYNQ_INTERVAL (HZ/5) /* Period of SYNACK timer */
149 #define TCP_PAWS_24DAYS (60 * 60 * 24 * 24)
150 #define TCP_PAWS_MSL 60 /* Per-host timestamps are invalidated
151 * after this time. It should be equal
152 * (or greater than) TCP_TIMEWAIT_LEN
153 * to provide reliability equal to one
154 * provided by timewait state.
156 #define TCP_PAWS_WINDOW 1 /* Replay window for per-host
157 * timestamps. It must be less than
158 * minimal timewait lifetime.
164 #define TCPOPT_NOP 1 /* Padding */
165 #define TCPOPT_EOL 0 /* End of options */
166 #define TCPOPT_MSS 2 /* Segment size negotiating */
167 #define TCPOPT_WINDOW 3 /* Window scaling */
168 #define TCPOPT_SACK_PERM 4 /* SACK Permitted */
169 #define TCPOPT_SACK 5 /* SACK Block */
170 #define TCPOPT_TIMESTAMP 8 /* Better RTT estimations/PAWS */
171 #define TCPOPT_MD5SIG 19 /* MD5 Signature (RFC2385) */
172 #define TCPOPT_COOKIE 253 /* Cookie extension (experimental) */
178 #define TCPOLEN_MSS 4
179 #define TCPOLEN_WINDOW 3
180 #define TCPOLEN_SACK_PERM 2
181 #define TCPOLEN_TIMESTAMP 10
182 #define TCPOLEN_MD5SIG 18
183 #define TCPOLEN_COOKIE_BASE 2 /* Cookie-less header extension */
184 #define TCPOLEN_COOKIE_PAIR 3 /* Cookie pair header extension */
185 #define TCPOLEN_COOKIE_MIN (TCPOLEN_COOKIE_BASE+TCP_COOKIE_MIN)
186 #define TCPOLEN_COOKIE_MAX (TCPOLEN_COOKIE_BASE+TCP_COOKIE_MAX)
188 /* But this is what stacks really send out. */
189 #define TCPOLEN_TSTAMP_ALIGNED 12
190 #define TCPOLEN_WSCALE_ALIGNED 4
191 #define TCPOLEN_SACKPERM_ALIGNED 4
192 #define TCPOLEN_SACK_BASE 2
193 #define TCPOLEN_SACK_BASE_ALIGNED 4
194 #define TCPOLEN_SACK_PERBLOCK 8
195 #define TCPOLEN_MD5SIG_ALIGNED 20
196 #define TCPOLEN_MSS_ALIGNED 4
198 /* Flags in tp->nonagle */
199 #define TCP_NAGLE_OFF 1 /* Nagle's algo is disabled */
200 #define TCP_NAGLE_CORK 2 /* Socket is corked */
201 #define TCP_NAGLE_PUSH 4 /* Cork is overridden for already queued data */
203 /* TCP thin-stream limits */
204 #define TCP_THIN_LINEAR_RETRIES 6 /* After 6 linear retries, do exp. backoff */
206 /* TCP initial congestion window as per draft-hkchu-tcpm-initcwnd-01 */
207 #define TCP_INIT_CWND 10
209 extern struct inet_timewait_death_row tcp_death_row;
211 /* sysctl variables for tcp */
212 extern int sysctl_tcp_timestamps;
213 extern int sysctl_tcp_window_scaling;
214 extern int sysctl_tcp_sack;
215 extern int sysctl_tcp_fin_timeout;
216 extern int sysctl_tcp_keepalive_time;
217 extern int sysctl_tcp_keepalive_probes;
218 extern int sysctl_tcp_keepalive_intvl;
219 extern int sysctl_tcp_syn_retries;
220 extern int sysctl_tcp_synack_retries;
221 extern int sysctl_tcp_retries1;
222 extern int sysctl_tcp_retries2;
223 extern int sysctl_tcp_orphan_retries;
224 extern int sysctl_tcp_syncookies;
225 extern int sysctl_tcp_retrans_collapse;
226 extern int sysctl_tcp_stdurg;
227 extern int sysctl_tcp_rfc1337;
228 extern int sysctl_tcp_abort_on_overflow;
229 extern int sysctl_tcp_max_orphans;
230 extern int sysctl_tcp_fack;
231 extern int sysctl_tcp_reordering;
232 extern int sysctl_tcp_ecn;
233 extern int sysctl_tcp_dsack;
234 extern int sysctl_tcp_wmem[3];
235 extern int sysctl_tcp_rmem[3];
236 extern int sysctl_tcp_app_win;
237 extern int sysctl_tcp_adv_win_scale;
238 extern int sysctl_tcp_tw_reuse;
239 extern int sysctl_tcp_frto;
240 extern int sysctl_tcp_frto_response;
241 extern int sysctl_tcp_low_latency;
242 extern int sysctl_tcp_dma_copybreak;
243 extern int sysctl_tcp_nometrics_save;
244 extern int sysctl_tcp_moderate_rcvbuf;
245 extern int sysctl_tcp_tso_win_divisor;
246 extern int sysctl_tcp_abc;
247 extern int sysctl_tcp_mtu_probing;
248 extern int sysctl_tcp_base_mss;
249 extern int sysctl_tcp_workaround_signed_windows;
250 extern int sysctl_tcp_slow_start_after_idle;
251 extern int sysctl_tcp_max_ssthresh;
252 extern int sysctl_tcp_cookie_size;
253 extern int sysctl_tcp_thin_linear_timeouts;
254 extern int sysctl_tcp_thin_dupack;
255 extern int sysctl_tcp_early_retrans;
257 extern atomic_long_t tcp_memory_allocated;
258 extern struct percpu_counter tcp_sockets_allocated;
259 extern int tcp_memory_pressure;
262 * The next routines deal with comparing 32 bit unsigned ints
263 * and worry about wraparound (automatic with unsigned arithmetic).
266 static inline bool before(__u32 seq1, __u32 seq2)
268 return (__s32)(seq1-seq2) < 0;
270 #define after(seq2, seq1) before(seq1, seq2)
272 /* is s2<=s1<=s3 ? */
273 static inline bool between(__u32 seq1, __u32 seq2, __u32 seq3)
275 return seq3 - seq2 >= seq1 - seq2;
278 static inline bool tcp_out_of_memory(struct sock *sk)
280 if (sk->sk_wmem_queued > SOCK_MIN_SNDBUF &&
281 sk_memory_allocated(sk) > sk_prot_mem_limits(sk, 2))
286 static inline bool tcp_too_many_orphans(struct sock *sk, int shift)
288 struct percpu_counter *ocp = sk->sk_prot->orphan_count;
289 int orphans = percpu_counter_read_positive(ocp);
291 if (orphans << shift > sysctl_tcp_max_orphans) {
292 orphans = percpu_counter_sum_positive(ocp);
293 if (orphans << shift > sysctl_tcp_max_orphans)
299 extern bool tcp_check_oom(struct sock *sk, int shift);
301 /* syncookies: remember time of last synqueue overflow */
302 static inline void tcp_synq_overflow(struct sock *sk)
304 tcp_sk(sk)->rx_opt.ts_recent_stamp = jiffies;
307 /* syncookies: no recent synqueue overflow on this listening socket? */
308 static inline bool tcp_synq_no_recent_overflow(const struct sock *sk)
310 unsigned long last_overflow = tcp_sk(sk)->rx_opt.ts_recent_stamp;
311 return time_after(jiffies, last_overflow + TCP_TIMEOUT_FALLBACK);
314 extern struct proto tcp_prot;
316 #define TCP_INC_STATS(net, field) SNMP_INC_STATS((net)->mib.tcp_statistics, field)
317 #define TCP_INC_STATS_BH(net, field) SNMP_INC_STATS_BH((net)->mib.tcp_statistics, field)
318 #define TCP_DEC_STATS(net, field) SNMP_DEC_STATS((net)->mib.tcp_statistics, field)
319 #define TCP_ADD_STATS_USER(net, field, val) SNMP_ADD_STATS_USER((net)->mib.tcp_statistics, field, val)
320 #define TCP_ADD_STATS(net, field, val) SNMP_ADD_STATS((net)->mib.tcp_statistics, field, val)
322 extern void tcp_init_mem(struct net *net);
324 extern void tcp_v4_err(struct sk_buff *skb, u32);
326 extern void tcp_shutdown (struct sock *sk, int how);
328 extern void tcp_v4_early_demux(struct sk_buff *skb);
329 extern int tcp_v4_rcv(struct sk_buff *skb);
331 extern struct inet_peer *tcp_v4_get_peer(struct sock *sk);
332 extern int tcp_v4_tw_remember_stamp(struct inet_timewait_sock *tw);
333 extern int tcp_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
335 extern int tcp_sendpage(struct sock *sk, struct page *page, int offset,
336 size_t size, int flags);
337 extern int tcp_ioctl(struct sock *sk, int cmd, unsigned long arg);
338 extern int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb,
339 const struct tcphdr *th, unsigned int len);
340 extern int tcp_rcv_established(struct sock *sk, struct sk_buff *skb,
341 const struct tcphdr *th, unsigned int len);
342 extern void tcp_rcv_space_adjust(struct sock *sk);
343 extern void tcp_cleanup_rbuf(struct sock *sk, int copied);
344 extern int tcp_twsk_unique(struct sock *sk, struct sock *sktw, void *twp);
345 extern void tcp_twsk_destructor(struct sock *sk);
346 extern ssize_t tcp_splice_read(struct socket *sk, loff_t *ppos,
347 struct pipe_inode_info *pipe, size_t len,
350 static inline void tcp_dec_quickack_mode(struct sock *sk,
351 const unsigned int pkts)
353 struct inet_connection_sock *icsk = inet_csk(sk);
355 if (icsk->icsk_ack.quick) {
356 if (pkts >= icsk->icsk_ack.quick) {
357 icsk->icsk_ack.quick = 0;
358 /* Leaving quickack mode we deflate ATO. */
359 icsk->icsk_ack.ato = TCP_ATO_MIN;
361 icsk->icsk_ack.quick -= pkts;
366 #define TCP_ECN_QUEUE_CWR 2
367 #define TCP_ECN_DEMAND_CWR 4
368 #define TCP_ECN_SEEN 8
378 extern enum tcp_tw_status tcp_timewait_state_process(struct inet_timewait_sock *tw,
380 const struct tcphdr *th);
381 extern struct sock * tcp_check_req(struct sock *sk,struct sk_buff *skb,
382 struct request_sock *req,
383 struct request_sock **prev);
384 extern int tcp_child_process(struct sock *parent, struct sock *child,
385 struct sk_buff *skb);
386 extern bool tcp_use_frto(struct sock *sk);
387 extern void tcp_enter_frto(struct sock *sk);
388 extern void tcp_enter_loss(struct sock *sk, int how);
389 extern void tcp_clear_retrans(struct tcp_sock *tp);
390 extern void tcp_update_metrics(struct sock *sk);
391 extern void tcp_init_metrics(struct sock *sk);
392 extern void tcp_metrics_init(void);
393 extern bool tcp_peer_is_proven(struct request_sock *req, struct dst_entry *dst, bool paws_check);
394 extern bool tcp_remember_stamp(struct sock *sk);
395 extern bool tcp_tw_remember_stamp(struct inet_timewait_sock *tw);
396 extern void tcp_fetch_timewait_stamp(struct sock *sk, struct dst_entry *dst);
397 extern void tcp_disable_fack(struct tcp_sock *tp);
398 extern void tcp_close(struct sock *sk, long timeout);
399 extern void tcp_init_sock(struct sock *sk);
400 extern unsigned int tcp_poll(struct file * file, struct socket *sock,
401 struct poll_table_struct *wait);
402 extern int tcp_getsockopt(struct sock *sk, int level, int optname,
403 char __user *optval, int __user *optlen);
404 extern int tcp_setsockopt(struct sock *sk, int level, int optname,
405 char __user *optval, unsigned int optlen);
406 extern int compat_tcp_getsockopt(struct sock *sk, int level, int optname,
407 char __user *optval, int __user *optlen);
408 extern int compat_tcp_setsockopt(struct sock *sk, int level, int optname,
409 char __user *optval, unsigned int optlen);
410 extern void tcp_set_keepalive(struct sock *sk, int val);
411 extern void tcp_syn_ack_timeout(struct sock *sk, struct request_sock *req);
412 extern int tcp_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
413 size_t len, int nonblock, int flags, int *addr_len);
414 extern void tcp_parse_options(const struct sk_buff *skb,
415 struct tcp_options_received *opt_rx, const u8 **hvpp,
417 extern const u8 *tcp_parse_md5sig_option(const struct tcphdr *th);
420 * TCP v4 functions exported for the inet6 API
423 extern void tcp_v4_send_check(struct sock *sk, struct sk_buff *skb);
424 extern int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb);
425 extern struct sock * tcp_create_openreq_child(struct sock *sk,
426 struct request_sock *req,
427 struct sk_buff *skb);
428 extern struct sock * tcp_v4_syn_recv_sock(struct sock *sk, struct sk_buff *skb,
429 struct request_sock *req,
430 struct dst_entry *dst);
431 extern int tcp_v4_do_rcv(struct sock *sk, struct sk_buff *skb);
432 extern int tcp_v4_connect(struct sock *sk, struct sockaddr *uaddr,
434 extern int tcp_connect(struct sock *sk);
435 extern struct sk_buff * tcp_make_synack(struct sock *sk, struct dst_entry *dst,
436 struct request_sock *req,
437 struct request_values *rvp);
438 extern int tcp_disconnect(struct sock *sk, int flags);
440 void tcp_connect_init(struct sock *sk);
441 void tcp_finish_connect(struct sock *sk, struct sk_buff *skb);
442 int tcp_send_rcvq(struct sock *sk, struct msghdr *msg, size_t size);
444 /* From syncookies.c */
445 extern __u32 syncookie_secret[2][16-4+SHA_DIGEST_WORDS];
446 extern struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb,
447 struct ip_options *opt);
448 #ifdef CONFIG_SYN_COOKIES
449 extern __u32 cookie_v4_init_sequence(struct sock *sk, struct sk_buff *skb,
452 static inline __u32 cookie_v4_init_sequence(struct sock *sk,
460 extern __u32 cookie_init_timestamp(struct request_sock *req);
461 extern bool cookie_check_timestamp(struct tcp_options_received *opt, bool *);
463 /* From net/ipv6/syncookies.c */
464 extern struct sock *cookie_v6_check(struct sock *sk, struct sk_buff *skb);
465 #ifdef CONFIG_SYN_COOKIES
466 extern __u32 cookie_v6_init_sequence(struct sock *sk, const struct sk_buff *skb,
469 static inline __u32 cookie_v6_init_sequence(struct sock *sk,
478 extern void __tcp_push_pending_frames(struct sock *sk, unsigned int cur_mss,
480 extern bool tcp_may_send_now(struct sock *sk);
481 extern int tcp_retransmit_skb(struct sock *, struct sk_buff *);
482 extern void tcp_retransmit_timer(struct sock *sk);
483 extern void tcp_xmit_retransmit_queue(struct sock *);
484 extern void tcp_simple_retransmit(struct sock *);
485 extern int tcp_trim_head(struct sock *, struct sk_buff *, u32);
486 extern int tcp_fragment(struct sock *, struct sk_buff *, u32, unsigned int);
488 extern void tcp_send_probe0(struct sock *);
489 extern void tcp_send_partial(struct sock *);
490 extern int tcp_write_wakeup(struct sock *);
491 extern void tcp_send_fin(struct sock *sk);
492 extern void tcp_send_active_reset(struct sock *sk, gfp_t priority);
493 extern int tcp_send_synack(struct sock *);
494 extern bool tcp_syn_flood_action(struct sock *sk,
495 const struct sk_buff *skb,
497 extern void tcp_push_one(struct sock *, unsigned int mss_now);
498 extern void tcp_send_ack(struct sock *sk);
499 extern void tcp_send_delayed_ack(struct sock *sk);
502 extern void tcp_cwnd_application_limited(struct sock *sk);
503 extern void tcp_resume_early_retransmit(struct sock *sk);
504 extern void tcp_rearm_rto(struct sock *sk);
507 extern void tcp_init_xmit_timers(struct sock *);
508 static inline void tcp_clear_xmit_timers(struct sock *sk)
510 inet_csk_clear_xmit_timers(sk);
513 extern unsigned int tcp_sync_mss(struct sock *sk, u32 pmtu);
514 extern unsigned int tcp_current_mss(struct sock *sk);
516 /* Bound MSS / TSO packet size with the half of the window */
517 static inline int tcp_bound_to_half_wnd(struct tcp_sock *tp, int pktsize)
521 /* When peer uses tiny windows, there is no use in packetizing
522 * to sub-MSS pieces for the sake of SWS or making sure there
523 * are enough packets in the pipe for fast recovery.
525 * On the other hand, for extremely large MSS devices, handling
526 * smaller than MSS windows in this way does make sense.
528 if (tp->max_window >= 512)
529 cutoff = (tp->max_window >> 1);
531 cutoff = tp->max_window;
533 if (cutoff && pktsize > cutoff)
534 return max_t(int, cutoff, 68U - tp->tcp_header_len);
540 extern void tcp_get_info(const struct sock *, struct tcp_info *);
542 /* Read 'sendfile()'-style from a TCP socket */
543 typedef int (*sk_read_actor_t)(read_descriptor_t *, struct sk_buff *,
544 unsigned int, size_t);
545 extern int tcp_read_sock(struct sock *sk, read_descriptor_t *desc,
546 sk_read_actor_t recv_actor);
548 extern void tcp_initialize_rcv_mss(struct sock *sk);
550 extern int tcp_mtu_to_mss(struct sock *sk, int pmtu);
551 extern int tcp_mss_to_mtu(struct sock *sk, int mss);
552 extern void tcp_mtup_init(struct sock *sk);
553 extern void tcp_valid_rtt_meas(struct sock *sk, u32 seq_rtt);
555 static inline void tcp_bound_rto(const struct sock *sk)
557 if (inet_csk(sk)->icsk_rto > TCP_RTO_MAX)
558 inet_csk(sk)->icsk_rto = TCP_RTO_MAX;
561 static inline u32 __tcp_set_rto(const struct tcp_sock *tp)
563 return (tp->srtt >> 3) + tp->rttvar;
566 extern void tcp_set_rto(struct sock *sk);
568 static inline void __tcp_fast_path_on(struct tcp_sock *tp, u32 snd_wnd)
570 tp->pred_flags = htonl((tp->tcp_header_len << 26) |
571 ntohl(TCP_FLAG_ACK) |
575 static inline void tcp_fast_path_on(struct tcp_sock *tp)
577 __tcp_fast_path_on(tp, tp->snd_wnd >> tp->rx_opt.snd_wscale);
580 static inline void tcp_fast_path_check(struct sock *sk)
582 struct tcp_sock *tp = tcp_sk(sk);
584 if (skb_queue_empty(&tp->out_of_order_queue) &&
586 atomic_read(&sk->sk_rmem_alloc) < sk->sk_rcvbuf &&
588 tcp_fast_path_on(tp);
591 /* Compute the actual rto_min value */
592 static inline u32 tcp_rto_min(struct sock *sk)
594 const struct dst_entry *dst = __sk_dst_get(sk);
595 u32 rto_min = TCP_RTO_MIN;
597 if (dst && dst_metric_locked(dst, RTAX_RTO_MIN))
598 rto_min = dst_metric_rtt(dst, RTAX_RTO_MIN);
602 /* Compute the actual receive window we are currently advertising.
603 * Rcv_nxt can be after the window if our peer push more data
604 * than the offered window.
606 static inline u32 tcp_receive_window(const struct tcp_sock *tp)
608 s32 win = tp->rcv_wup + tp->rcv_wnd - tp->rcv_nxt;
615 /* Choose a new window, without checks for shrinking, and without
616 * scaling applied to the result. The caller does these things
617 * if necessary. This is a "raw" window selection.
619 extern u32 __tcp_select_window(struct sock *sk);
621 void tcp_send_window_probe(struct sock *sk);
623 /* TCP timestamps are only 32-bits, this causes a slight
624 * complication on 64-bit systems since we store a snapshot
625 * of jiffies in the buffer control blocks below. We decided
626 * to use only the low 32-bits of jiffies and hide the ugly
627 * casts with the following macro.
629 #define tcp_time_stamp ((__u32)(jiffies))
631 #define tcp_flag_byte(th) (((u_int8_t *)th)[13])
633 #define TCPHDR_FIN 0x01
634 #define TCPHDR_SYN 0x02
635 #define TCPHDR_RST 0x04
636 #define TCPHDR_PSH 0x08
637 #define TCPHDR_ACK 0x10
638 #define TCPHDR_URG 0x20
639 #define TCPHDR_ECE 0x40
640 #define TCPHDR_CWR 0x80
642 /* This is what the send packet queuing engine uses to pass
643 * TCP per-packet control information to the transmission code.
644 * We also store the host-order sequence numbers in here too.
645 * This is 44 bytes if IPV6 is enabled.
646 * If this grows please adjust skbuff.h:skbuff->cb[xxx] size appropriately.
650 struct inet_skb_parm h4;
651 #if IS_ENABLED(CONFIG_IPV6)
652 struct inet6_skb_parm h6;
654 } header; /* For incoming frames */
655 __u32 seq; /* Starting sequence number */
656 __u32 end_seq; /* SEQ + FIN + SYN + datalen */
657 __u32 when; /* used to compute rtt's */
658 __u8 tcp_flags; /* TCP header flags. (tcp[13]) */
660 __u8 sacked; /* State flags for SACK/FACK. */
661 #define TCPCB_SACKED_ACKED 0x01 /* SKB ACK'd by a SACK block */
662 #define TCPCB_SACKED_RETRANS 0x02 /* SKB retransmitted */
663 #define TCPCB_LOST 0x04 /* SKB is lost */
664 #define TCPCB_TAGBITS 0x07 /* All tag bits */
665 #define TCPCB_EVER_RETRANS 0x80 /* Ever retransmitted frame */
666 #define TCPCB_RETRANS (TCPCB_SACKED_RETRANS|TCPCB_EVER_RETRANS)
668 __u8 ip_dsfield; /* IPv4 tos or IPv6 dsfield */
670 __u32 ack_seq; /* Sequence number ACK'd */
673 #define TCP_SKB_CB(__skb) ((struct tcp_skb_cb *)&((__skb)->cb[0]))
675 /* RFC3168 : 6.1.1 SYN packets must not have ECT/ECN bits set
677 * If we receive a SYN packet with these bits set, it means a network is
678 * playing bad games with TOS bits. In order to avoid possible false congestion
679 * notifications, we disable TCP ECN negociation.
682 TCP_ECN_create_request(struct request_sock *req, const struct sk_buff *skb)
684 const struct tcphdr *th = tcp_hdr(skb);
686 if (sysctl_tcp_ecn && th->ece && th->cwr &&
687 INET_ECN_is_not_ect(TCP_SKB_CB(skb)->ip_dsfield))
688 inet_rsk(req)->ecn_ok = 1;
691 /* Due to TSO, an SKB can be composed of multiple actual
692 * packets. To keep these tracked properly, we use this.
694 static inline int tcp_skb_pcount(const struct sk_buff *skb)
696 return skb_shinfo(skb)->gso_segs;
699 /* This is valid iff tcp_skb_pcount() > 1. */
700 static inline int tcp_skb_mss(const struct sk_buff *skb)
702 return skb_shinfo(skb)->gso_size;
705 /* Events passed to congestion control interface */
707 CA_EVENT_TX_START, /* first transmit when no packets in flight */
708 CA_EVENT_CWND_RESTART, /* congestion window restart */
709 CA_EVENT_COMPLETE_CWR, /* end of congestion recovery */
710 CA_EVENT_FRTO, /* fast recovery timeout */
711 CA_EVENT_LOSS, /* loss timeout */
712 CA_EVENT_FAST_ACK, /* in sequence ack */
713 CA_EVENT_SLOW_ACK, /* other ack */
717 * Interface for adding new TCP congestion control handlers
719 #define TCP_CA_NAME_MAX 16
720 #define TCP_CA_MAX 128
721 #define TCP_CA_BUF_MAX (TCP_CA_NAME_MAX*TCP_CA_MAX)
723 #define TCP_CONG_NON_RESTRICTED 0x1
724 #define TCP_CONG_RTT_STAMP 0x2
726 struct tcp_congestion_ops {
727 struct list_head list;
730 /* initialize private data (optional) */
731 void (*init)(struct sock *sk);
732 /* cleanup private data (optional) */
733 void (*release)(struct sock *sk);
735 /* return slow start threshold (required) */
736 u32 (*ssthresh)(struct sock *sk);
737 /* lower bound for congestion window (optional) */
738 u32 (*min_cwnd)(const struct sock *sk);
739 /* do new cwnd calculation (required) */
740 void (*cong_avoid)(struct sock *sk, u32 ack, u32 in_flight);
741 /* call before changing ca_state (optional) */
742 void (*set_state)(struct sock *sk, u8 new_state);
743 /* call when cwnd event occurs (optional) */
744 void (*cwnd_event)(struct sock *sk, enum tcp_ca_event ev);
745 /* new value of cwnd after loss (optional) */
746 u32 (*undo_cwnd)(struct sock *sk);
747 /* hook for packet ack accounting (optional) */
748 void (*pkts_acked)(struct sock *sk, u32 num_acked, s32 rtt_us);
749 /* get info for inet_diag (optional) */
750 void (*get_info)(struct sock *sk, u32 ext, struct sk_buff *skb);
752 char name[TCP_CA_NAME_MAX];
753 struct module *owner;
756 extern int tcp_register_congestion_control(struct tcp_congestion_ops *type);
757 extern void tcp_unregister_congestion_control(struct tcp_congestion_ops *type);
759 extern void tcp_init_congestion_control(struct sock *sk);
760 extern void tcp_cleanup_congestion_control(struct sock *sk);
761 extern int tcp_set_default_congestion_control(const char *name);
762 extern void tcp_get_default_congestion_control(char *name);
763 extern void tcp_get_available_congestion_control(char *buf, size_t len);
764 extern void tcp_get_allowed_congestion_control(char *buf, size_t len);
765 extern int tcp_set_allowed_congestion_control(char *allowed);
766 extern int tcp_set_congestion_control(struct sock *sk, const char *name);
767 extern void tcp_slow_start(struct tcp_sock *tp);
768 extern void tcp_cong_avoid_ai(struct tcp_sock *tp, u32 w);
770 extern struct tcp_congestion_ops tcp_init_congestion_ops;
771 extern u32 tcp_reno_ssthresh(struct sock *sk);
772 extern void tcp_reno_cong_avoid(struct sock *sk, u32 ack, u32 in_flight);
773 extern u32 tcp_reno_min_cwnd(const struct sock *sk);
774 extern struct tcp_congestion_ops tcp_reno;
776 static inline void tcp_set_ca_state(struct sock *sk, const u8 ca_state)
778 struct inet_connection_sock *icsk = inet_csk(sk);
780 if (icsk->icsk_ca_ops->set_state)
781 icsk->icsk_ca_ops->set_state(sk, ca_state);
782 icsk->icsk_ca_state = ca_state;
785 static inline void tcp_ca_event(struct sock *sk, const enum tcp_ca_event event)
787 const struct inet_connection_sock *icsk = inet_csk(sk);
789 if (icsk->icsk_ca_ops->cwnd_event)
790 icsk->icsk_ca_ops->cwnd_event(sk, event);
793 /* These functions determine how the current flow behaves in respect of SACK
794 * handling. SACK is negotiated with the peer, and therefore it can vary
795 * between different flows.
797 * tcp_is_sack - SACK enabled
798 * tcp_is_reno - No SACK
799 * tcp_is_fack - FACK enabled, implies SACK enabled
801 static inline int tcp_is_sack(const struct tcp_sock *tp)
803 return tp->rx_opt.sack_ok;
806 static inline bool tcp_is_reno(const struct tcp_sock *tp)
808 return !tcp_is_sack(tp);
811 static inline bool tcp_is_fack(const struct tcp_sock *tp)
813 return tp->rx_opt.sack_ok & TCP_FACK_ENABLED;
816 static inline void tcp_enable_fack(struct tcp_sock *tp)
818 tp->rx_opt.sack_ok |= TCP_FACK_ENABLED;
821 /* TCP early-retransmit (ER) is similar to but more conservative than
822 * the thin-dupack feature. Enable ER only if thin-dupack is disabled.
824 static inline void tcp_enable_early_retrans(struct tcp_sock *tp)
826 tp->do_early_retrans = sysctl_tcp_early_retrans &&
827 !sysctl_tcp_thin_dupack && sysctl_tcp_reordering == 3;
828 tp->early_retrans_delayed = 0;
831 static inline void tcp_disable_early_retrans(struct tcp_sock *tp)
833 tp->do_early_retrans = 0;
836 static inline unsigned int tcp_left_out(const struct tcp_sock *tp)
838 return tp->sacked_out + tp->lost_out;
841 /* This determines how many packets are "in the network" to the best
842 * of our knowledge. In many cases it is conservative, but where
843 * detailed information is available from the receiver (via SACK
844 * blocks etc.) we can make more aggressive calculations.
846 * Use this for decisions involving congestion control, use just
847 * tp->packets_out to determine if the send queue is empty or not.
849 * Read this equation as:
851 * "Packets sent once on transmission queue" MINUS
852 * "Packets left network, but not honestly ACKed yet" PLUS
853 * "Packets fast retransmitted"
855 static inline unsigned int tcp_packets_in_flight(const struct tcp_sock *tp)
857 return tp->packets_out - tcp_left_out(tp) + tp->retrans_out;
860 #define TCP_INFINITE_SSTHRESH 0x7fffffff
862 static inline bool tcp_in_initial_slowstart(const struct tcp_sock *tp)
864 return tp->snd_ssthresh >= TCP_INFINITE_SSTHRESH;
867 /* If cwnd > ssthresh, we may raise ssthresh to be half-way to cwnd.
868 * The exception is rate halving phase, when cwnd is decreasing towards
871 static inline __u32 tcp_current_ssthresh(const struct sock *sk)
873 const struct tcp_sock *tp = tcp_sk(sk);
875 if ((1 << inet_csk(sk)->icsk_ca_state) & (TCPF_CA_CWR | TCPF_CA_Recovery))
876 return tp->snd_ssthresh;
878 return max(tp->snd_ssthresh,
879 ((tp->snd_cwnd >> 1) +
880 (tp->snd_cwnd >> 2)));
883 /* Use define here intentionally to get WARN_ON location shown at the caller */
884 #define tcp_verify_left_out(tp) WARN_ON(tcp_left_out(tp) > tp->packets_out)
886 extern void tcp_enter_cwr(struct sock *sk, const int set_ssthresh);
887 extern __u32 tcp_init_cwnd(const struct tcp_sock *tp, const struct dst_entry *dst);
889 /* The maximum number of MSS of available cwnd for which TSO defers
890 * sending if not using sysctl_tcp_tso_win_divisor.
892 static inline __u32 tcp_max_tso_deferred_mss(const struct tcp_sock *tp)
897 /* Slow start with delack produces 3 packets of burst, so that
898 * it is safe "de facto". This will be the default - same as
899 * the default reordering threshold - but if reordering increases,
900 * we must be able to allow cwnd to burst at least this much in order
901 * to not pull it back when holes are filled.
903 static __inline__ __u32 tcp_max_burst(const struct tcp_sock *tp)
905 return tp->reordering;
908 /* Returns end sequence number of the receiver's advertised window */
909 static inline u32 tcp_wnd_end(const struct tcp_sock *tp)
911 return tp->snd_una + tp->snd_wnd;
913 extern bool tcp_is_cwnd_limited(const struct sock *sk, u32 in_flight);
915 static inline void tcp_minshall_update(struct tcp_sock *tp, unsigned int mss,
916 const struct sk_buff *skb)
919 tp->snd_sml = TCP_SKB_CB(skb)->end_seq;
922 static inline void tcp_check_probe_timer(struct sock *sk)
924 const struct tcp_sock *tp = tcp_sk(sk);
925 const struct inet_connection_sock *icsk = inet_csk(sk);
927 if (!tp->packets_out && !icsk->icsk_pending)
928 inet_csk_reset_xmit_timer(sk, ICSK_TIME_PROBE0,
929 icsk->icsk_rto, TCP_RTO_MAX);
932 static inline void tcp_init_wl(struct tcp_sock *tp, u32 seq)
937 static inline void tcp_update_wl(struct tcp_sock *tp, u32 seq)
943 * Calculate(/check) TCP checksum
945 static inline __sum16 tcp_v4_check(int len, __be32 saddr,
946 __be32 daddr, __wsum base)
948 return csum_tcpudp_magic(saddr,daddr,len,IPPROTO_TCP,base);
951 static inline __sum16 __tcp_checksum_complete(struct sk_buff *skb)
953 return __skb_checksum_complete(skb);
956 static inline bool tcp_checksum_complete(struct sk_buff *skb)
958 return !skb_csum_unnecessary(skb) &&
959 __tcp_checksum_complete(skb);
962 /* Prequeue for VJ style copy to user, combined with checksumming. */
964 static inline void tcp_prequeue_init(struct tcp_sock *tp)
966 tp->ucopy.task = NULL;
968 tp->ucopy.memory = 0;
969 skb_queue_head_init(&tp->ucopy.prequeue);
970 #ifdef CONFIG_NET_DMA
971 tp->ucopy.dma_chan = NULL;
972 tp->ucopy.wakeup = 0;
973 tp->ucopy.pinned_list = NULL;
974 tp->ucopy.dma_cookie = 0;
978 /* Packet is added to VJ-style prequeue for processing in process
979 * context, if a reader task is waiting. Apparently, this exciting
980 * idea (VJ's mail "Re: query about TCP header on tcp-ip" of 07 Sep 93)
981 * failed somewhere. Latency? Burstiness? Well, at least now we will
982 * see, why it failed. 8)8) --ANK
984 * NOTE: is this not too big to inline?
986 static inline bool tcp_prequeue(struct sock *sk, struct sk_buff *skb)
988 struct tcp_sock *tp = tcp_sk(sk);
990 if (sysctl_tcp_low_latency || !tp->ucopy.task)
993 __skb_queue_tail(&tp->ucopy.prequeue, skb);
994 tp->ucopy.memory += skb->truesize;
995 if (tp->ucopy.memory > sk->sk_rcvbuf) {
996 struct sk_buff *skb1;
998 BUG_ON(sock_owned_by_user(sk));
1000 while ((skb1 = __skb_dequeue(&tp->ucopy.prequeue)) != NULL) {
1001 sk_backlog_rcv(sk, skb1);
1002 NET_INC_STATS_BH(sock_net(sk),
1003 LINUX_MIB_TCPPREQUEUEDROPPED);
1006 tp->ucopy.memory = 0;
1007 } else if (skb_queue_len(&tp->ucopy.prequeue) == 1) {
1008 wake_up_interruptible_sync_poll(sk_sleep(sk),
1009 POLLIN | POLLRDNORM | POLLRDBAND);
1010 if (!inet_csk_ack_scheduled(sk))
1011 inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK,
1012 (3 * tcp_rto_min(sk)) / 4,
1022 static const char *statename[]={
1023 "Unused","Established","Syn Sent","Syn Recv",
1024 "Fin Wait 1","Fin Wait 2","Time Wait", "Close",
1025 "Close Wait","Last ACK","Listen","Closing"
1028 extern void tcp_set_state(struct sock *sk, int state);
1030 extern void tcp_done(struct sock *sk);
1032 static inline void tcp_sack_reset(struct tcp_options_received *rx_opt)
1035 rx_opt->num_sacks = 0;
1038 /* Determine a window scaling and initial window to offer. */
1039 extern void tcp_select_initial_window(int __space, __u32 mss,
1040 __u32 *rcv_wnd, __u32 *window_clamp,
1041 int wscale_ok, __u8 *rcv_wscale,
1042 __u32 init_rcv_wnd);
1044 static inline int tcp_win_from_space(int space)
1046 return sysctl_tcp_adv_win_scale<=0 ?
1047 (space>>(-sysctl_tcp_adv_win_scale)) :
1048 space - (space>>sysctl_tcp_adv_win_scale);
1051 /* Note: caller must be prepared to deal with negative returns */
1052 static inline int tcp_space(const struct sock *sk)
1054 return tcp_win_from_space(sk->sk_rcvbuf -
1055 atomic_read(&sk->sk_rmem_alloc));
1058 static inline int tcp_full_space(const struct sock *sk)
1060 return tcp_win_from_space(sk->sk_rcvbuf);
1063 static inline void tcp_openreq_init(struct request_sock *req,
1064 struct tcp_options_received *rx_opt,
1065 struct sk_buff *skb)
1067 struct inet_request_sock *ireq = inet_rsk(req);
1069 req->rcv_wnd = 0; /* So that tcp_send_synack() knows! */
1071 tcp_rsk(req)->rcv_isn = TCP_SKB_CB(skb)->seq;
1072 req->mss = rx_opt->mss_clamp;
1073 req->ts_recent = rx_opt->saw_tstamp ? rx_opt->rcv_tsval : 0;
1074 ireq->tstamp_ok = rx_opt->tstamp_ok;
1075 ireq->sack_ok = rx_opt->sack_ok;
1076 ireq->snd_wscale = rx_opt->snd_wscale;
1077 ireq->wscale_ok = rx_opt->wscale_ok;
1080 ireq->rmt_port = tcp_hdr(skb)->source;
1081 ireq->loc_port = tcp_hdr(skb)->dest;
1084 extern void tcp_enter_memory_pressure(struct sock *sk);
1086 static inline int keepalive_intvl_when(const struct tcp_sock *tp)
1088 return tp->keepalive_intvl ? : sysctl_tcp_keepalive_intvl;
1091 static inline int keepalive_time_when(const struct tcp_sock *tp)
1093 return tp->keepalive_time ? : sysctl_tcp_keepalive_time;
1096 static inline int keepalive_probes(const struct tcp_sock *tp)
1098 return tp->keepalive_probes ? : sysctl_tcp_keepalive_probes;
1101 static inline u32 keepalive_time_elapsed(const struct tcp_sock *tp)
1103 const struct inet_connection_sock *icsk = &tp->inet_conn;
1105 return min_t(u32, tcp_time_stamp - icsk->icsk_ack.lrcvtime,
1106 tcp_time_stamp - tp->rcv_tstamp);
1109 static inline int tcp_fin_time(const struct sock *sk)
1111 int fin_timeout = tcp_sk(sk)->linger2 ? : sysctl_tcp_fin_timeout;
1112 const int rto = inet_csk(sk)->icsk_rto;
1114 if (fin_timeout < (rto << 2) - (rto >> 1))
1115 fin_timeout = (rto << 2) - (rto >> 1);
1120 static inline bool tcp_paws_check(const struct tcp_options_received *rx_opt,
1123 if ((s32)(rx_opt->ts_recent - rx_opt->rcv_tsval) <= paws_win)
1125 if (unlikely(get_seconds() >= rx_opt->ts_recent_stamp + TCP_PAWS_24DAYS))
1128 * Some OSes send SYN and SYNACK messages with tsval=0 tsecr=0,
1129 * then following tcp messages have valid values. Ignore 0 value,
1130 * or else 'negative' tsval might forbid us to accept their packets.
1132 if (!rx_opt->ts_recent)
1137 static inline bool tcp_paws_reject(const struct tcp_options_received *rx_opt,
1140 if (tcp_paws_check(rx_opt, 0))
1143 /* RST segments are not recommended to carry timestamp,
1144 and, if they do, it is recommended to ignore PAWS because
1145 "their cleanup function should take precedence over timestamps."
1146 Certainly, it is mistake. It is necessary to understand the reasons
1147 of this constraint to relax it: if peer reboots, clock may go
1148 out-of-sync and half-open connections will not be reset.
1149 Actually, the problem would be not existing if all
1150 the implementations followed draft about maintaining clock
1151 via reboots. Linux-2.2 DOES NOT!
1153 However, we can relax time bounds for RST segments to MSL.
1155 if (rst && get_seconds() >= rx_opt->ts_recent_stamp + TCP_PAWS_MSL)
1160 static inline void tcp_mib_init(struct net *net)
1163 TCP_ADD_STATS_USER(net, TCP_MIB_RTOALGORITHM, 1);
1164 TCP_ADD_STATS_USER(net, TCP_MIB_RTOMIN, TCP_RTO_MIN*1000/HZ);
1165 TCP_ADD_STATS_USER(net, TCP_MIB_RTOMAX, TCP_RTO_MAX*1000/HZ);
1166 TCP_ADD_STATS_USER(net, TCP_MIB_MAXCONN, -1);
1170 static inline void tcp_clear_retrans_hints_partial(struct tcp_sock *tp)
1172 tp->lost_skb_hint = NULL;
1173 tp->scoreboard_skb_hint = NULL;
1176 static inline void tcp_clear_all_retrans_hints(struct tcp_sock *tp)
1178 tcp_clear_retrans_hints_partial(tp);
1179 tp->retransmit_skb_hint = NULL;
1185 union tcp_md5_addr {
1187 #if IS_ENABLED(CONFIG_IPV6)
1192 /* - key database */
1193 struct tcp_md5sig_key {
1194 struct hlist_node node;
1196 u8 family; /* AF_INET or AF_INET6 */
1197 union tcp_md5_addr addr;
1198 u8 key[TCP_MD5SIG_MAXKEYLEN];
1199 struct rcu_head rcu;
1203 struct tcp_md5sig_info {
1204 struct hlist_head head;
1205 struct rcu_head rcu;
1208 /* - pseudo header */
1209 struct tcp4_pseudohdr {
1217 struct tcp6_pseudohdr {
1218 struct in6_addr saddr;
1219 struct in6_addr daddr;
1221 __be32 protocol; /* including padding */
1224 union tcp_md5sum_block {
1225 struct tcp4_pseudohdr ip4;
1226 #if IS_ENABLED(CONFIG_IPV6)
1227 struct tcp6_pseudohdr ip6;
1231 /* - pool: digest algorithm, hash description and scratch buffer */
1232 struct tcp_md5sig_pool {
1233 struct hash_desc md5_desc;
1234 union tcp_md5sum_block md5_blk;
1238 extern int tcp_v4_md5_hash_skb(char *md5_hash, struct tcp_md5sig_key *key,
1239 const struct sock *sk,
1240 const struct request_sock *req,
1241 const struct sk_buff *skb);
1242 extern int tcp_md5_do_add(struct sock *sk, const union tcp_md5_addr *addr,
1243 int family, const u8 *newkey,
1244 u8 newkeylen, gfp_t gfp);
1245 extern int tcp_md5_do_del(struct sock *sk, const union tcp_md5_addr *addr,
1247 extern struct tcp_md5sig_key *tcp_v4_md5_lookup(struct sock *sk,
1248 struct sock *addr_sk);
1250 #ifdef CONFIG_TCP_MD5SIG
1251 extern struct tcp_md5sig_key *tcp_md5_do_lookup(struct sock *sk,
1252 const union tcp_md5_addr *addr, int family);
1253 #define tcp_twsk_md5_key(twsk) ((twsk)->tw_md5_key)
1255 static inline struct tcp_md5sig_key *tcp_md5_do_lookup(struct sock *sk,
1256 const union tcp_md5_addr *addr,
1261 #define tcp_twsk_md5_key(twsk) NULL
1264 extern struct tcp_md5sig_pool __percpu *tcp_alloc_md5sig_pool(struct sock *);
1265 extern void tcp_free_md5sig_pool(void);
1267 extern struct tcp_md5sig_pool *tcp_get_md5sig_pool(void);
1268 extern void tcp_put_md5sig_pool(void);
1270 extern int tcp_md5_hash_header(struct tcp_md5sig_pool *, const struct tcphdr *);
1271 extern int tcp_md5_hash_skb_data(struct tcp_md5sig_pool *, const struct sk_buff *,
1272 unsigned int header_len);
1273 extern int tcp_md5_hash_key(struct tcp_md5sig_pool *hp,
1274 const struct tcp_md5sig_key *key);
1276 /* write queue abstraction */
1277 static inline void tcp_write_queue_purge(struct sock *sk)
1279 struct sk_buff *skb;
1281 while ((skb = __skb_dequeue(&sk->sk_write_queue)) != NULL)
1282 sk_wmem_free_skb(sk, skb);
1284 tcp_clear_all_retrans_hints(tcp_sk(sk));
1287 static inline struct sk_buff *tcp_write_queue_head(const struct sock *sk)
1289 return skb_peek(&sk->sk_write_queue);
1292 static inline struct sk_buff *tcp_write_queue_tail(const struct sock *sk)
1294 return skb_peek_tail(&sk->sk_write_queue);
1297 static inline struct sk_buff *tcp_write_queue_next(const struct sock *sk,
1298 const struct sk_buff *skb)
1300 return skb_queue_next(&sk->sk_write_queue, skb);
1303 static inline struct sk_buff *tcp_write_queue_prev(const struct sock *sk,
1304 const struct sk_buff *skb)
1306 return skb_queue_prev(&sk->sk_write_queue, skb);
1309 #define tcp_for_write_queue(skb, sk) \
1310 skb_queue_walk(&(sk)->sk_write_queue, skb)
1312 #define tcp_for_write_queue_from(skb, sk) \
1313 skb_queue_walk_from(&(sk)->sk_write_queue, skb)
1315 #define tcp_for_write_queue_from_safe(skb, tmp, sk) \
1316 skb_queue_walk_from_safe(&(sk)->sk_write_queue, skb, tmp)
1318 static inline struct sk_buff *tcp_send_head(const struct sock *sk)
1320 return sk->sk_send_head;
1323 static inline bool tcp_skb_is_last(const struct sock *sk,
1324 const struct sk_buff *skb)
1326 return skb_queue_is_last(&sk->sk_write_queue, skb);
1329 static inline void tcp_advance_send_head(struct sock *sk, const struct sk_buff *skb)
1331 if (tcp_skb_is_last(sk, skb))
1332 sk->sk_send_head = NULL;
1334 sk->sk_send_head = tcp_write_queue_next(sk, skb);
1337 static inline void tcp_check_send_head(struct sock *sk, struct sk_buff *skb_unlinked)
1339 if (sk->sk_send_head == skb_unlinked)
1340 sk->sk_send_head = NULL;
1343 static inline void tcp_init_send_head(struct sock *sk)
1345 sk->sk_send_head = NULL;
1348 static inline void __tcp_add_write_queue_tail(struct sock *sk, struct sk_buff *skb)
1350 __skb_queue_tail(&sk->sk_write_queue, skb);
1353 static inline void tcp_add_write_queue_tail(struct sock *sk, struct sk_buff *skb)
1355 __tcp_add_write_queue_tail(sk, skb);
1357 /* Queue it, remembering where we must start sending. */
1358 if (sk->sk_send_head == NULL) {
1359 sk->sk_send_head = skb;
1361 if (tcp_sk(sk)->highest_sack == NULL)
1362 tcp_sk(sk)->highest_sack = skb;
1366 static inline void __tcp_add_write_queue_head(struct sock *sk, struct sk_buff *skb)
1368 __skb_queue_head(&sk->sk_write_queue, skb);
1371 /* Insert buff after skb on the write queue of sk. */
1372 static inline void tcp_insert_write_queue_after(struct sk_buff *skb,
1373 struct sk_buff *buff,
1376 __skb_queue_after(&sk->sk_write_queue, skb, buff);
1379 /* Insert new before skb on the write queue of sk. */
1380 static inline void tcp_insert_write_queue_before(struct sk_buff *new,
1381 struct sk_buff *skb,
1384 __skb_queue_before(&sk->sk_write_queue, skb, new);
1386 if (sk->sk_send_head == skb)
1387 sk->sk_send_head = new;
1390 static inline void tcp_unlink_write_queue(struct sk_buff *skb, struct sock *sk)
1392 __skb_unlink(skb, &sk->sk_write_queue);
1395 static inline bool tcp_write_queue_empty(struct sock *sk)
1397 return skb_queue_empty(&sk->sk_write_queue);
1400 static inline void tcp_push_pending_frames(struct sock *sk)
1402 if (tcp_send_head(sk)) {
1403 struct tcp_sock *tp = tcp_sk(sk);
1405 __tcp_push_pending_frames(sk, tcp_current_mss(sk), tp->nonagle);
1409 /* Start sequence of the skb just after the highest skb with SACKed
1410 * bit, valid only if sacked_out > 0 or when the caller has ensured
1411 * validity by itself.
1413 static inline u32 tcp_highest_sack_seq(struct tcp_sock *tp)
1415 if (!tp->sacked_out)
1418 if (tp->highest_sack == NULL)
1421 return TCP_SKB_CB(tp->highest_sack)->seq;
1424 static inline void tcp_advance_highest_sack(struct sock *sk, struct sk_buff *skb)
1426 tcp_sk(sk)->highest_sack = tcp_skb_is_last(sk, skb) ? NULL :
1427 tcp_write_queue_next(sk, skb);
1430 static inline struct sk_buff *tcp_highest_sack(struct sock *sk)
1432 return tcp_sk(sk)->highest_sack;
1435 static inline void tcp_highest_sack_reset(struct sock *sk)
1437 tcp_sk(sk)->highest_sack = tcp_write_queue_head(sk);
1440 /* Called when old skb is about to be deleted (to be combined with new skb) */
1441 static inline void tcp_highest_sack_combine(struct sock *sk,
1442 struct sk_buff *old,
1443 struct sk_buff *new)
1445 if (tcp_sk(sk)->sacked_out && (old == tcp_sk(sk)->highest_sack))
1446 tcp_sk(sk)->highest_sack = new;
1449 /* Determines whether this is a thin stream (which may suffer from
1450 * increased latency). Used to trigger latency-reducing mechanisms.
1452 static inline bool tcp_stream_is_thin(struct tcp_sock *tp)
1454 return tp->packets_out < 4 && !tcp_in_initial_slowstart(tp);
1458 enum tcp_seq_states {
1459 TCP_SEQ_STATE_LISTENING,
1460 TCP_SEQ_STATE_OPENREQ,
1461 TCP_SEQ_STATE_ESTABLISHED,
1462 TCP_SEQ_STATE_TIME_WAIT,
1465 int tcp_seq_open(struct inode *inode, struct file *file);
1467 struct tcp_seq_afinfo {
1470 const struct file_operations *seq_fops;
1471 struct seq_operations seq_ops;
1474 struct tcp_iter_state {
1475 struct seq_net_private p;
1477 enum tcp_seq_states state;
1478 struct sock *syn_wait_sk;
1479 int bucket, offset, sbucket, num, uid;
1483 extern int tcp_proc_register(struct net *net, struct tcp_seq_afinfo *afinfo);
1484 extern void tcp_proc_unregister(struct net *net, struct tcp_seq_afinfo *afinfo);
1486 extern struct request_sock_ops tcp_request_sock_ops;
1487 extern struct request_sock_ops tcp6_request_sock_ops;
1489 extern void tcp_v4_destroy_sock(struct sock *sk);
1491 extern int tcp_v4_gso_send_check(struct sk_buff *skb);
1492 extern struct sk_buff *tcp_tso_segment(struct sk_buff *skb,
1493 netdev_features_t features);
1494 extern struct sk_buff **tcp_gro_receive(struct sk_buff **head,
1495 struct sk_buff *skb);
1496 extern struct sk_buff **tcp4_gro_receive(struct sk_buff **head,
1497 struct sk_buff *skb);
1498 extern int tcp_gro_complete(struct sk_buff *skb);
1499 extern int tcp4_gro_complete(struct sk_buff *skb);
1501 #ifdef CONFIG_PROC_FS
1502 extern int tcp4_proc_init(void);
1503 extern void tcp4_proc_exit(void);
1506 /* TCP af-specific functions */
1507 struct tcp_sock_af_ops {
1508 #ifdef CONFIG_TCP_MD5SIG
1509 struct tcp_md5sig_key *(*md5_lookup) (struct sock *sk,
1510 struct sock *addr_sk);
1511 int (*calc_md5_hash) (char *location,
1512 struct tcp_md5sig_key *md5,
1513 const struct sock *sk,
1514 const struct request_sock *req,
1515 const struct sk_buff *skb);
1516 int (*md5_parse) (struct sock *sk,
1517 char __user *optval,
1522 struct tcp_request_sock_ops {
1523 #ifdef CONFIG_TCP_MD5SIG
1524 struct tcp_md5sig_key *(*md5_lookup) (struct sock *sk,
1525 struct request_sock *req);
1526 int (*calc_md5_hash) (char *location,
1527 struct tcp_md5sig_key *md5,
1528 const struct sock *sk,
1529 const struct request_sock *req,
1530 const struct sk_buff *skb);
1534 /* Using SHA1 for now, define some constants.
1536 #define COOKIE_DIGEST_WORDS (SHA_DIGEST_WORDS)
1537 #define COOKIE_MESSAGE_WORDS (SHA_MESSAGE_BYTES / 4)
1538 #define COOKIE_WORKSPACE_WORDS (COOKIE_DIGEST_WORDS + COOKIE_MESSAGE_WORDS)
1540 extern int tcp_cookie_generator(u32 *bakery);
1543 * struct tcp_cookie_values - each socket needs extra space for the
1544 * cookies, together with (optional) space for any SYN data.
1546 * A tcp_sock contains a pointer to the current value, and this is
1547 * cloned to the tcp_timewait_sock.
1549 * @cookie_pair: variable data from the option exchange.
1551 * @cookie_desired: user specified tcpct_cookie_desired. Zero
1552 * indicates default (sysctl_tcp_cookie_size).
1553 * After cookie sent, remembers size of cookie.
1554 * Range 0, TCP_COOKIE_MIN to TCP_COOKIE_MAX.
1556 * @s_data_desired: user specified tcpct_s_data_desired. When the
1557 * constant payload is specified (@s_data_constant),
1558 * holds its length instead.
1559 * Range 0 to TCP_MSS_DESIRED.
1561 * @s_data_payload: constant data that is to be included in the
1562 * payload of SYN or SYNACK segments when the
1563 * cookie option is present.
1565 struct tcp_cookie_values {
1567 u8 cookie_pair[TCP_COOKIE_PAIR_SIZE];
1568 u8 cookie_pair_size;
1570 u16 s_data_desired:11,
1575 u8 s_data_payload[0];
1578 static inline void tcp_cookie_values_release(struct kref *kref)
1580 kfree(container_of(kref, struct tcp_cookie_values, kref));
1583 /* The length of constant payload data. Note that s_data_desired is
1584 * overloaded, depending on s_data_constant: either the length of constant
1585 * data (returned here) or the limit on variable data.
1587 static inline int tcp_s_data_size(const struct tcp_sock *tp)
1589 return (tp->cookie_values != NULL && tp->cookie_values->s_data_constant)
1590 ? tp->cookie_values->s_data_desired
1595 * struct tcp_extend_values - tcp_ipv?.c to tcp_output.c workspace.
1597 * As tcp_request_sock has already been extended in other places, the
1598 * only remaining method is to pass stack values along as function
1599 * parameters. These parameters are not needed after sending SYNACK.
1601 * @cookie_bakery: cryptographic secret and message workspace.
1603 * @cookie_plus: bytes in authenticator/cookie option, copied from
1604 * struct tcp_options_received (above).
1606 struct tcp_extend_values {
1607 struct request_values rv;
1608 u32 cookie_bakery[COOKIE_WORKSPACE_WORDS];
1614 static inline struct tcp_extend_values *tcp_xv(struct request_values *rvp)
1616 return (struct tcp_extend_values *)rvp;
1619 extern void tcp_v4_init(void);
1620 extern void tcp_init(void);