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;
256 extern atomic_long_t tcp_memory_allocated;
257 extern struct percpu_counter tcp_sockets_allocated;
258 extern int tcp_memory_pressure;
261 * The next routines deal with comparing 32 bit unsigned ints
262 * and worry about wraparound (automatic with unsigned arithmetic).
265 static inline int before(__u32 seq1, __u32 seq2)
267 return (__s32)(seq1-seq2) < 0;
269 #define after(seq2, seq1) before(seq1, seq2)
271 /* is s2<=s1<=s3 ? */
272 static inline int between(__u32 seq1, __u32 seq2, __u32 seq3)
274 return seq3 - seq2 >= seq1 - seq2;
277 static inline bool tcp_out_of_memory(struct sock *sk)
279 if (sk->sk_wmem_queued > SOCK_MIN_SNDBUF &&
280 sk_memory_allocated(sk) > sk_prot_mem_limits(sk, 2))
285 static inline bool tcp_too_many_orphans(struct sock *sk, int shift)
287 struct percpu_counter *ocp = sk->sk_prot->orphan_count;
288 int orphans = percpu_counter_read_positive(ocp);
290 if (orphans << shift > sysctl_tcp_max_orphans) {
291 orphans = percpu_counter_sum_positive(ocp);
292 if (orphans << shift > sysctl_tcp_max_orphans)
298 extern bool tcp_check_oom(struct sock *sk, int shift);
300 /* syncookies: remember time of last synqueue overflow */
301 static inline void tcp_synq_overflow(struct sock *sk)
303 tcp_sk(sk)->rx_opt.ts_recent_stamp = jiffies;
306 /* syncookies: no recent synqueue overflow on this listening socket? */
307 static inline int tcp_synq_no_recent_overflow(const struct sock *sk)
309 unsigned long last_overflow = tcp_sk(sk)->rx_opt.ts_recent_stamp;
310 return time_after(jiffies, last_overflow + TCP_TIMEOUT_FALLBACK);
313 extern struct proto tcp_prot;
315 #define TCP_INC_STATS(net, field) SNMP_INC_STATS((net)->mib.tcp_statistics, field)
316 #define TCP_INC_STATS_BH(net, field) SNMP_INC_STATS_BH((net)->mib.tcp_statistics, field)
317 #define TCP_DEC_STATS(net, field) SNMP_DEC_STATS((net)->mib.tcp_statistics, field)
318 #define TCP_ADD_STATS_USER(net, field, val) SNMP_ADD_STATS_USER((net)->mib.tcp_statistics, field, val)
319 #define TCP_ADD_STATS(net, field, val) SNMP_ADD_STATS((net)->mib.tcp_statistics, field, val)
321 extern void tcp_init_mem(struct net *net);
323 extern void tcp_v4_err(struct sk_buff *skb, u32);
325 extern void tcp_shutdown (struct sock *sk, int how);
327 extern int tcp_v4_rcv(struct sk_buff *skb);
329 extern struct inet_peer *tcp_v4_get_peer(struct sock *sk, bool *release_it);
330 extern void *tcp_v4_tw_get_peer(struct sock *sk);
331 extern int tcp_v4_tw_remember_stamp(struct inet_timewait_sock *tw);
332 extern int tcp_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
334 extern int tcp_sendpage(struct sock *sk, struct page *page, int offset,
335 size_t size, int flags);
336 extern int tcp_ioctl(struct sock *sk, int cmd, unsigned long arg);
337 extern int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb,
338 const struct tcphdr *th, unsigned int len);
339 extern int tcp_rcv_established(struct sock *sk, struct sk_buff *skb,
340 const struct tcphdr *th, unsigned int len);
341 extern void tcp_rcv_space_adjust(struct sock *sk);
342 extern void tcp_cleanup_rbuf(struct sock *sk, int copied);
343 extern int tcp_twsk_unique(struct sock *sk, struct sock *sktw, void *twp);
344 extern void tcp_twsk_destructor(struct sock *sk);
345 extern ssize_t tcp_splice_read(struct socket *sk, loff_t *ppos,
346 struct pipe_inode_info *pipe, size_t len,
349 static inline void tcp_dec_quickack_mode(struct sock *sk,
350 const unsigned int pkts)
352 struct inet_connection_sock *icsk = inet_csk(sk);
354 if (icsk->icsk_ack.quick) {
355 if (pkts >= icsk->icsk_ack.quick) {
356 icsk->icsk_ack.quick = 0;
357 /* Leaving quickack mode we deflate ATO. */
358 icsk->icsk_ack.ato = TCP_ATO_MIN;
360 icsk->icsk_ack.quick -= pkts;
365 #define TCP_ECN_QUEUE_CWR 2
366 #define TCP_ECN_DEMAND_CWR 4
367 #define TCP_ECN_SEEN 8
369 static __inline__ void
370 TCP_ECN_create_request(struct request_sock *req, struct tcphdr *th)
372 if (sysctl_tcp_ecn && th->ece && th->cwr)
373 inet_rsk(req)->ecn_ok = 1;
384 extern enum tcp_tw_status tcp_timewait_state_process(struct inet_timewait_sock *tw,
386 const struct tcphdr *th);
387 extern struct sock * tcp_check_req(struct sock *sk,struct sk_buff *skb,
388 struct request_sock *req,
389 struct request_sock **prev);
390 extern int tcp_child_process(struct sock *parent, struct sock *child,
391 struct sk_buff *skb);
392 extern int tcp_use_frto(struct sock *sk);
393 extern void tcp_enter_frto(struct sock *sk);
394 extern void tcp_enter_loss(struct sock *sk, int how);
395 extern void tcp_clear_retrans(struct tcp_sock *tp);
396 extern void tcp_update_metrics(struct sock *sk);
397 extern void tcp_close(struct sock *sk, long timeout);
398 extern void tcp_init_sock(struct sock *sk);
399 extern unsigned int tcp_poll(struct file * file, struct socket *sock,
400 struct poll_table_struct *wait);
401 extern int tcp_getsockopt(struct sock *sk, int level, int optname,
402 char __user *optval, int __user *optlen);
403 extern int tcp_setsockopt(struct sock *sk, int level, int optname,
404 char __user *optval, unsigned int optlen);
405 extern int compat_tcp_getsockopt(struct sock *sk, int level, int optname,
406 char __user *optval, int __user *optlen);
407 extern int compat_tcp_setsockopt(struct sock *sk, int level, int optname,
408 char __user *optval, unsigned int optlen);
409 extern void tcp_set_keepalive(struct sock *sk, int val);
410 extern void tcp_syn_ack_timeout(struct sock *sk, struct request_sock *req);
411 extern int tcp_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
412 size_t len, int nonblock, int flags, int *addr_len);
413 extern void tcp_parse_options(const struct sk_buff *skb,
414 struct tcp_options_received *opt_rx, const u8 **hvpp,
416 extern const u8 *tcp_parse_md5sig_option(const struct tcphdr *th);
419 * TCP v4 functions exported for the inet6 API
422 extern void tcp_v4_send_check(struct sock *sk, struct sk_buff *skb);
423 extern int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb);
424 extern struct sock * tcp_create_openreq_child(struct sock *sk,
425 struct request_sock *req,
426 struct sk_buff *skb);
427 extern struct sock * tcp_v4_syn_recv_sock(struct sock *sk, struct sk_buff *skb,
428 struct request_sock *req,
429 struct dst_entry *dst);
430 extern int tcp_v4_do_rcv(struct sock *sk, struct sk_buff *skb);
431 extern int tcp_v4_connect(struct sock *sk, struct sockaddr *uaddr,
433 extern int tcp_connect(struct sock *sk);
434 extern struct sk_buff * tcp_make_synack(struct sock *sk, struct dst_entry *dst,
435 struct request_sock *req,
436 struct request_values *rvp);
437 extern int tcp_disconnect(struct sock *sk, int flags);
439 void tcp_connect_init(struct sock *sk);
440 void tcp_finish_connect(struct sock *sk, struct sk_buff *skb);
441 void tcp_queue_rcv(struct sock *sk, struct sk_buff *skb, int hdrlen);
443 /* From syncookies.c */
444 extern __u32 syncookie_secret[2][16-4+SHA_DIGEST_WORDS];
445 extern struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb,
446 struct ip_options *opt);
447 #ifdef CONFIG_SYN_COOKIES
448 extern __u32 cookie_v4_init_sequence(struct sock *sk, struct sk_buff *skb,
451 static inline __u32 cookie_v4_init_sequence(struct sock *sk,
459 extern __u32 cookie_init_timestamp(struct request_sock *req);
460 extern bool cookie_check_timestamp(struct tcp_options_received *opt, bool *);
462 /* From net/ipv6/syncookies.c */
463 extern struct sock *cookie_v6_check(struct sock *sk, struct sk_buff *skb);
464 #ifdef CONFIG_SYN_COOKIES
465 extern __u32 cookie_v6_init_sequence(struct sock *sk, const struct sk_buff *skb,
468 static inline __u32 cookie_v6_init_sequence(struct sock *sk,
477 extern void __tcp_push_pending_frames(struct sock *sk, unsigned int cur_mss,
479 extern int tcp_may_send_now(struct sock *sk);
480 extern int tcp_retransmit_skb(struct sock *, struct sk_buff *);
481 extern void tcp_retransmit_timer(struct sock *sk);
482 extern void tcp_xmit_retransmit_queue(struct sock *);
483 extern void tcp_simple_retransmit(struct sock *);
484 extern int tcp_trim_head(struct sock *, struct sk_buff *, u32);
485 extern int tcp_fragment(struct sock *, struct sk_buff *, u32, unsigned int);
487 extern void tcp_send_probe0(struct sock *);
488 extern void tcp_send_partial(struct sock *);
489 extern int tcp_write_wakeup(struct sock *);
490 extern void tcp_send_fin(struct sock *sk);
491 extern void tcp_send_active_reset(struct sock *sk, gfp_t priority);
492 extern int tcp_send_synack(struct sock *);
493 extern int tcp_syn_flood_action(struct sock *sk,
494 const struct sk_buff *skb,
496 extern void tcp_push_one(struct sock *, unsigned int mss_now);
497 extern void tcp_send_ack(struct sock *sk);
498 extern void tcp_send_delayed_ack(struct sock *sk);
501 extern void tcp_cwnd_application_limited(struct sock *sk);
504 extern void tcp_init_xmit_timers(struct sock *);
505 static inline void tcp_clear_xmit_timers(struct sock *sk)
507 inet_csk_clear_xmit_timers(sk);
510 extern unsigned int tcp_sync_mss(struct sock *sk, u32 pmtu);
511 extern unsigned int tcp_current_mss(struct sock *sk);
513 /* Bound MSS / TSO packet size with the half of the window */
514 static inline int tcp_bound_to_half_wnd(struct tcp_sock *tp, int pktsize)
518 /* When peer uses tiny windows, there is no use in packetizing
519 * to sub-MSS pieces for the sake of SWS or making sure there
520 * are enough packets in the pipe for fast recovery.
522 * On the other hand, for extremely large MSS devices, handling
523 * smaller than MSS windows in this way does make sense.
525 if (tp->max_window >= 512)
526 cutoff = (tp->max_window >> 1);
528 cutoff = tp->max_window;
530 if (cutoff && pktsize > cutoff)
531 return max_t(int, cutoff, 68U - tp->tcp_header_len);
537 extern void tcp_get_info(const struct sock *, struct tcp_info *);
539 /* Read 'sendfile()'-style from a TCP socket */
540 typedef int (*sk_read_actor_t)(read_descriptor_t *, struct sk_buff *,
541 unsigned int, size_t);
542 extern int tcp_read_sock(struct sock *sk, read_descriptor_t *desc,
543 sk_read_actor_t recv_actor);
545 extern void tcp_initialize_rcv_mss(struct sock *sk);
547 extern int tcp_mtu_to_mss(struct sock *sk, int pmtu);
548 extern int tcp_mss_to_mtu(struct sock *sk, int mss);
549 extern void tcp_mtup_init(struct sock *sk);
550 extern void tcp_valid_rtt_meas(struct sock *sk, u32 seq_rtt);
552 static inline void tcp_bound_rto(const struct sock *sk)
554 if (inet_csk(sk)->icsk_rto > TCP_RTO_MAX)
555 inet_csk(sk)->icsk_rto = TCP_RTO_MAX;
558 static inline u32 __tcp_set_rto(const struct tcp_sock *tp)
560 return (tp->srtt >> 3) + tp->rttvar;
563 static inline void __tcp_fast_path_on(struct tcp_sock *tp, u32 snd_wnd)
565 tp->pred_flags = htonl((tp->tcp_header_len << 26) |
566 ntohl(TCP_FLAG_ACK) |
570 static inline void tcp_fast_path_on(struct tcp_sock *tp)
572 __tcp_fast_path_on(tp, tp->snd_wnd >> tp->rx_opt.snd_wscale);
575 static inline void tcp_fast_path_check(struct sock *sk)
577 struct tcp_sock *tp = tcp_sk(sk);
579 if (skb_queue_empty(&tp->out_of_order_queue) &&
581 atomic_read(&sk->sk_rmem_alloc) < sk->sk_rcvbuf &&
583 tcp_fast_path_on(tp);
586 /* Compute the actual rto_min value */
587 static inline u32 tcp_rto_min(struct sock *sk)
589 const struct dst_entry *dst = __sk_dst_get(sk);
590 u32 rto_min = TCP_RTO_MIN;
592 if (dst && dst_metric_locked(dst, RTAX_RTO_MIN))
593 rto_min = dst_metric_rtt(dst, RTAX_RTO_MIN);
597 /* Compute the actual receive window we are currently advertising.
598 * Rcv_nxt can be after the window if our peer push more data
599 * than the offered window.
601 static inline u32 tcp_receive_window(const struct tcp_sock *tp)
603 s32 win = tp->rcv_wup + tp->rcv_wnd - tp->rcv_nxt;
610 /* Choose a new window, without checks for shrinking, and without
611 * scaling applied to the result. The caller does these things
612 * if necessary. This is a "raw" window selection.
614 extern u32 __tcp_select_window(struct sock *sk);
616 void tcp_send_window_probe(struct sock *sk);
618 /* TCP timestamps are only 32-bits, this causes a slight
619 * complication on 64-bit systems since we store a snapshot
620 * of jiffies in the buffer control blocks below. We decided
621 * to use only the low 32-bits of jiffies and hide the ugly
622 * casts with the following macro.
624 #define tcp_time_stamp ((__u32)(jiffies))
626 #define tcp_flag_byte(th) (((u_int8_t *)th)[13])
628 #define TCPHDR_FIN 0x01
629 #define TCPHDR_SYN 0x02
630 #define TCPHDR_RST 0x04
631 #define TCPHDR_PSH 0x08
632 #define TCPHDR_ACK 0x10
633 #define TCPHDR_URG 0x20
634 #define TCPHDR_ECE 0x40
635 #define TCPHDR_CWR 0x80
637 /* This is what the send packet queuing engine uses to pass
638 * TCP per-packet control information to the transmission code.
639 * We also store the host-order sequence numbers in here too.
640 * This is 44 bytes if IPV6 is enabled.
641 * If this grows please adjust skbuff.h:skbuff->cb[xxx] size appropriately.
645 struct inet_skb_parm h4;
646 #if IS_ENABLED(CONFIG_IPV6)
647 struct inet6_skb_parm h6;
649 } header; /* For incoming frames */
650 __u32 seq; /* Starting sequence number */
651 __u32 end_seq; /* SEQ + FIN + SYN + datalen */
652 __u32 when; /* used to compute rtt's */
653 __u8 tcp_flags; /* TCP header flags. (tcp[13]) */
655 __u8 sacked; /* State flags for SACK/FACK. */
656 #define TCPCB_SACKED_ACKED 0x01 /* SKB ACK'd by a SACK block */
657 #define TCPCB_SACKED_RETRANS 0x02 /* SKB retransmitted */
658 #define TCPCB_LOST 0x04 /* SKB is lost */
659 #define TCPCB_TAGBITS 0x07 /* All tag bits */
660 #define TCPCB_EVER_RETRANS 0x80 /* Ever retransmitted frame */
661 #define TCPCB_RETRANS (TCPCB_SACKED_RETRANS|TCPCB_EVER_RETRANS)
663 __u8 ip_dsfield; /* IPv4 tos or IPv6 dsfield */
665 __u32 ack_seq; /* Sequence number ACK'd */
668 #define TCP_SKB_CB(__skb) ((struct tcp_skb_cb *)&((__skb)->cb[0]))
670 /* Due to TSO, an SKB can be composed of multiple actual
671 * packets. To keep these tracked properly, we use this.
673 static inline int tcp_skb_pcount(const struct sk_buff *skb)
675 return skb_shinfo(skb)->gso_segs;
678 /* This is valid iff tcp_skb_pcount() > 1. */
679 static inline int tcp_skb_mss(const struct sk_buff *skb)
681 return skb_shinfo(skb)->gso_size;
684 /* Events passed to congestion control interface */
686 CA_EVENT_TX_START, /* first transmit when no packets in flight */
687 CA_EVENT_CWND_RESTART, /* congestion window restart */
688 CA_EVENT_COMPLETE_CWR, /* end of congestion recovery */
689 CA_EVENT_FRTO, /* fast recovery timeout */
690 CA_EVENT_LOSS, /* loss timeout */
691 CA_EVENT_FAST_ACK, /* in sequence ack */
692 CA_EVENT_SLOW_ACK, /* other ack */
696 * Interface for adding new TCP congestion control handlers
698 #define TCP_CA_NAME_MAX 16
699 #define TCP_CA_MAX 128
700 #define TCP_CA_BUF_MAX (TCP_CA_NAME_MAX*TCP_CA_MAX)
702 #define TCP_CONG_NON_RESTRICTED 0x1
703 #define TCP_CONG_RTT_STAMP 0x2
705 struct tcp_congestion_ops {
706 struct list_head list;
709 /* initialize private data (optional) */
710 void (*init)(struct sock *sk);
711 /* cleanup private data (optional) */
712 void (*release)(struct sock *sk);
714 /* return slow start threshold (required) */
715 u32 (*ssthresh)(struct sock *sk);
716 /* lower bound for congestion window (optional) */
717 u32 (*min_cwnd)(const struct sock *sk);
718 /* do new cwnd calculation (required) */
719 void (*cong_avoid)(struct sock *sk, u32 ack, u32 in_flight);
720 /* call before changing ca_state (optional) */
721 void (*set_state)(struct sock *sk, u8 new_state);
722 /* call when cwnd event occurs (optional) */
723 void (*cwnd_event)(struct sock *sk, enum tcp_ca_event ev);
724 /* new value of cwnd after loss (optional) */
725 u32 (*undo_cwnd)(struct sock *sk);
726 /* hook for packet ack accounting (optional) */
727 void (*pkts_acked)(struct sock *sk, u32 num_acked, s32 rtt_us);
728 /* get info for inet_diag (optional) */
729 void (*get_info)(struct sock *sk, u32 ext, struct sk_buff *skb);
731 char name[TCP_CA_NAME_MAX];
732 struct module *owner;
735 extern int tcp_register_congestion_control(struct tcp_congestion_ops *type);
736 extern void tcp_unregister_congestion_control(struct tcp_congestion_ops *type);
738 extern void tcp_init_congestion_control(struct sock *sk);
739 extern void tcp_cleanup_congestion_control(struct sock *sk);
740 extern int tcp_set_default_congestion_control(const char *name);
741 extern void tcp_get_default_congestion_control(char *name);
742 extern void tcp_get_available_congestion_control(char *buf, size_t len);
743 extern void tcp_get_allowed_congestion_control(char *buf, size_t len);
744 extern int tcp_set_allowed_congestion_control(char *allowed);
745 extern int tcp_set_congestion_control(struct sock *sk, const char *name);
746 extern void tcp_slow_start(struct tcp_sock *tp);
747 extern void tcp_cong_avoid_ai(struct tcp_sock *tp, u32 w);
749 extern struct tcp_congestion_ops tcp_init_congestion_ops;
750 extern u32 tcp_reno_ssthresh(struct sock *sk);
751 extern void tcp_reno_cong_avoid(struct sock *sk, u32 ack, u32 in_flight);
752 extern u32 tcp_reno_min_cwnd(const struct sock *sk);
753 extern struct tcp_congestion_ops tcp_reno;
755 static inline void tcp_set_ca_state(struct sock *sk, const u8 ca_state)
757 struct inet_connection_sock *icsk = inet_csk(sk);
759 if (icsk->icsk_ca_ops->set_state)
760 icsk->icsk_ca_ops->set_state(sk, ca_state);
761 icsk->icsk_ca_state = ca_state;
764 static inline void tcp_ca_event(struct sock *sk, const enum tcp_ca_event event)
766 const struct inet_connection_sock *icsk = inet_csk(sk);
768 if (icsk->icsk_ca_ops->cwnd_event)
769 icsk->icsk_ca_ops->cwnd_event(sk, event);
772 /* These functions determine how the current flow behaves in respect of SACK
773 * handling. SACK is negotiated with the peer, and therefore it can vary
774 * between different flows.
776 * tcp_is_sack - SACK enabled
777 * tcp_is_reno - No SACK
778 * tcp_is_fack - FACK enabled, implies SACK enabled
780 static inline int tcp_is_sack(const struct tcp_sock *tp)
782 return tp->rx_opt.sack_ok;
785 static inline int tcp_is_reno(const struct tcp_sock *tp)
787 return !tcp_is_sack(tp);
790 static inline int tcp_is_fack(const struct tcp_sock *tp)
792 return tp->rx_opt.sack_ok & TCP_FACK_ENABLED;
795 static inline void tcp_enable_fack(struct tcp_sock *tp)
797 tp->rx_opt.sack_ok |= TCP_FACK_ENABLED;
800 static inline unsigned int tcp_left_out(const struct tcp_sock *tp)
802 return tp->sacked_out + tp->lost_out;
805 /* This determines how many packets are "in the network" to the best
806 * of our knowledge. In many cases it is conservative, but where
807 * detailed information is available from the receiver (via SACK
808 * blocks etc.) we can make more aggressive calculations.
810 * Use this for decisions involving congestion control, use just
811 * tp->packets_out to determine if the send queue is empty or not.
813 * Read this equation as:
815 * "Packets sent once on transmission queue" MINUS
816 * "Packets left network, but not honestly ACKed yet" PLUS
817 * "Packets fast retransmitted"
819 static inline unsigned int tcp_packets_in_flight(const struct tcp_sock *tp)
821 return tp->packets_out - tcp_left_out(tp) + tp->retrans_out;
824 #define TCP_INFINITE_SSTHRESH 0x7fffffff
826 static inline bool tcp_in_initial_slowstart(const struct tcp_sock *tp)
828 return tp->snd_ssthresh >= TCP_INFINITE_SSTHRESH;
831 /* If cwnd > ssthresh, we may raise ssthresh to be half-way to cwnd.
832 * The exception is rate halving phase, when cwnd is decreasing towards
835 static inline __u32 tcp_current_ssthresh(const struct sock *sk)
837 const struct tcp_sock *tp = tcp_sk(sk);
839 if ((1 << inet_csk(sk)->icsk_ca_state) & (TCPF_CA_CWR | TCPF_CA_Recovery))
840 return tp->snd_ssthresh;
842 return max(tp->snd_ssthresh,
843 ((tp->snd_cwnd >> 1) +
844 (tp->snd_cwnd >> 2)));
847 /* Use define here intentionally to get WARN_ON location shown at the caller */
848 #define tcp_verify_left_out(tp) WARN_ON(tcp_left_out(tp) > tp->packets_out)
850 extern void tcp_enter_cwr(struct sock *sk, const int set_ssthresh);
851 extern __u32 tcp_init_cwnd(const struct tcp_sock *tp, const struct dst_entry *dst);
853 /* The maximum number of MSS of available cwnd for which TSO defers
854 * sending if not using sysctl_tcp_tso_win_divisor.
856 static inline __u32 tcp_max_tso_deferred_mss(const struct tcp_sock *tp)
861 /* Slow start with delack produces 3 packets of burst, so that
862 * it is safe "de facto". This will be the default - same as
863 * the default reordering threshold - but if reordering increases,
864 * we must be able to allow cwnd to burst at least this much in order
865 * to not pull it back when holes are filled.
867 static __inline__ __u32 tcp_max_burst(const struct tcp_sock *tp)
869 return tp->reordering;
872 /* Returns end sequence number of the receiver's advertised window */
873 static inline u32 tcp_wnd_end(const struct tcp_sock *tp)
875 return tp->snd_una + tp->snd_wnd;
877 extern int tcp_is_cwnd_limited(const struct sock *sk, u32 in_flight);
879 static inline void tcp_minshall_update(struct tcp_sock *tp, unsigned int mss,
880 const struct sk_buff *skb)
883 tp->snd_sml = TCP_SKB_CB(skb)->end_seq;
886 static inline void tcp_check_probe_timer(struct sock *sk)
888 const struct tcp_sock *tp = tcp_sk(sk);
889 const struct inet_connection_sock *icsk = inet_csk(sk);
891 if (!tp->packets_out && !icsk->icsk_pending)
892 inet_csk_reset_xmit_timer(sk, ICSK_TIME_PROBE0,
893 icsk->icsk_rto, TCP_RTO_MAX);
896 static inline void tcp_init_wl(struct tcp_sock *tp, u32 seq)
901 static inline void tcp_update_wl(struct tcp_sock *tp, u32 seq)
907 * Calculate(/check) TCP checksum
909 static inline __sum16 tcp_v4_check(int len, __be32 saddr,
910 __be32 daddr, __wsum base)
912 return csum_tcpudp_magic(saddr,daddr,len,IPPROTO_TCP,base);
915 static inline __sum16 __tcp_checksum_complete(struct sk_buff *skb)
917 return __skb_checksum_complete(skb);
920 static inline int tcp_checksum_complete(struct sk_buff *skb)
922 return !skb_csum_unnecessary(skb) &&
923 __tcp_checksum_complete(skb);
926 /* Prequeue for VJ style copy to user, combined with checksumming. */
928 static inline void tcp_prequeue_init(struct tcp_sock *tp)
930 tp->ucopy.task = NULL;
932 tp->ucopy.memory = 0;
933 skb_queue_head_init(&tp->ucopy.prequeue);
934 #ifdef CONFIG_NET_DMA
935 tp->ucopy.dma_chan = NULL;
936 tp->ucopy.wakeup = 0;
937 tp->ucopy.pinned_list = NULL;
938 tp->ucopy.dma_cookie = 0;
942 /* Packet is added to VJ-style prequeue for processing in process
943 * context, if a reader task is waiting. Apparently, this exciting
944 * idea (VJ's mail "Re: query about TCP header on tcp-ip" of 07 Sep 93)
945 * failed somewhere. Latency? Burstiness? Well, at least now we will
946 * see, why it failed. 8)8) --ANK
948 * NOTE: is this not too big to inline?
950 static inline int tcp_prequeue(struct sock *sk, struct sk_buff *skb)
952 struct tcp_sock *tp = tcp_sk(sk);
954 if (sysctl_tcp_low_latency || !tp->ucopy.task)
957 __skb_queue_tail(&tp->ucopy.prequeue, skb);
958 tp->ucopy.memory += skb->truesize;
959 if (tp->ucopy.memory > sk->sk_rcvbuf) {
960 struct sk_buff *skb1;
962 BUG_ON(sock_owned_by_user(sk));
964 while ((skb1 = __skb_dequeue(&tp->ucopy.prequeue)) != NULL) {
965 sk_backlog_rcv(sk, skb1);
966 NET_INC_STATS_BH(sock_net(sk),
967 LINUX_MIB_TCPPREQUEUEDROPPED);
970 tp->ucopy.memory = 0;
971 } else if (skb_queue_len(&tp->ucopy.prequeue) == 1) {
972 wake_up_interruptible_sync_poll(sk_sleep(sk),
973 POLLIN | POLLRDNORM | POLLRDBAND);
974 if (!inet_csk_ack_scheduled(sk))
975 inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK,
976 (3 * tcp_rto_min(sk)) / 4,
986 static const char *statename[]={
987 "Unused","Established","Syn Sent","Syn Recv",
988 "Fin Wait 1","Fin Wait 2","Time Wait", "Close",
989 "Close Wait","Last ACK","Listen","Closing"
992 extern void tcp_set_state(struct sock *sk, int state);
994 extern void tcp_done(struct sock *sk);
996 static inline void tcp_sack_reset(struct tcp_options_received *rx_opt)
999 rx_opt->num_sacks = 0;
1002 /* Determine a window scaling and initial window to offer. */
1003 extern void tcp_select_initial_window(int __space, __u32 mss,
1004 __u32 *rcv_wnd, __u32 *window_clamp,
1005 int wscale_ok, __u8 *rcv_wscale,
1006 __u32 init_rcv_wnd);
1008 static inline int tcp_win_from_space(int space)
1010 return sysctl_tcp_adv_win_scale<=0 ?
1011 (space>>(-sysctl_tcp_adv_win_scale)) :
1012 space - (space>>sysctl_tcp_adv_win_scale);
1015 /* Note: caller must be prepared to deal with negative returns */
1016 static inline int tcp_space(const struct sock *sk)
1018 return tcp_win_from_space(sk->sk_rcvbuf -
1019 atomic_read(&sk->sk_rmem_alloc));
1022 static inline int tcp_full_space(const struct sock *sk)
1024 return tcp_win_from_space(sk->sk_rcvbuf);
1027 static inline void tcp_openreq_init(struct request_sock *req,
1028 struct tcp_options_received *rx_opt,
1029 struct sk_buff *skb)
1031 struct inet_request_sock *ireq = inet_rsk(req);
1033 req->rcv_wnd = 0; /* So that tcp_send_synack() knows! */
1035 tcp_rsk(req)->rcv_isn = TCP_SKB_CB(skb)->seq;
1036 req->mss = rx_opt->mss_clamp;
1037 req->ts_recent = rx_opt->saw_tstamp ? rx_opt->rcv_tsval : 0;
1038 ireq->tstamp_ok = rx_opt->tstamp_ok;
1039 ireq->sack_ok = rx_opt->sack_ok;
1040 ireq->snd_wscale = rx_opt->snd_wscale;
1041 ireq->wscale_ok = rx_opt->wscale_ok;
1044 ireq->rmt_port = tcp_hdr(skb)->source;
1045 ireq->loc_port = tcp_hdr(skb)->dest;
1048 extern void tcp_enter_memory_pressure(struct sock *sk);
1050 static inline int keepalive_intvl_when(const struct tcp_sock *tp)
1052 return tp->keepalive_intvl ? : sysctl_tcp_keepalive_intvl;
1055 static inline int keepalive_time_when(const struct tcp_sock *tp)
1057 return tp->keepalive_time ? : sysctl_tcp_keepalive_time;
1060 static inline int keepalive_probes(const struct tcp_sock *tp)
1062 return tp->keepalive_probes ? : sysctl_tcp_keepalive_probes;
1065 static inline u32 keepalive_time_elapsed(const struct tcp_sock *tp)
1067 const struct inet_connection_sock *icsk = &tp->inet_conn;
1069 return min_t(u32, tcp_time_stamp - icsk->icsk_ack.lrcvtime,
1070 tcp_time_stamp - tp->rcv_tstamp);
1073 static inline int tcp_fin_time(const struct sock *sk)
1075 int fin_timeout = tcp_sk(sk)->linger2 ? : sysctl_tcp_fin_timeout;
1076 const int rto = inet_csk(sk)->icsk_rto;
1078 if (fin_timeout < (rto << 2) - (rto >> 1))
1079 fin_timeout = (rto << 2) - (rto >> 1);
1084 static inline int tcp_paws_check(const struct tcp_options_received *rx_opt,
1087 if ((s32)(rx_opt->ts_recent - rx_opt->rcv_tsval) <= paws_win)
1089 if (unlikely(get_seconds() >= rx_opt->ts_recent_stamp + TCP_PAWS_24DAYS))
1092 * Some OSes send SYN and SYNACK messages with tsval=0 tsecr=0,
1093 * then following tcp messages have valid values. Ignore 0 value,
1094 * or else 'negative' tsval might forbid us to accept their packets.
1096 if (!rx_opt->ts_recent)
1101 static inline int tcp_paws_reject(const struct tcp_options_received *rx_opt,
1104 if (tcp_paws_check(rx_opt, 0))
1107 /* RST segments are not recommended to carry timestamp,
1108 and, if they do, it is recommended to ignore PAWS because
1109 "their cleanup function should take precedence over timestamps."
1110 Certainly, it is mistake. It is necessary to understand the reasons
1111 of this constraint to relax it: if peer reboots, clock may go
1112 out-of-sync and half-open connections will not be reset.
1113 Actually, the problem would be not existing if all
1114 the implementations followed draft about maintaining clock
1115 via reboots. Linux-2.2 DOES NOT!
1117 However, we can relax time bounds for RST segments to MSL.
1119 if (rst && get_seconds() >= rx_opt->ts_recent_stamp + TCP_PAWS_MSL)
1124 static inline void tcp_mib_init(struct net *net)
1127 TCP_ADD_STATS_USER(net, TCP_MIB_RTOALGORITHM, 1);
1128 TCP_ADD_STATS_USER(net, TCP_MIB_RTOMIN, TCP_RTO_MIN*1000/HZ);
1129 TCP_ADD_STATS_USER(net, TCP_MIB_RTOMAX, TCP_RTO_MAX*1000/HZ);
1130 TCP_ADD_STATS_USER(net, TCP_MIB_MAXCONN, -1);
1134 static inline void tcp_clear_retrans_hints_partial(struct tcp_sock *tp)
1136 tp->lost_skb_hint = NULL;
1137 tp->scoreboard_skb_hint = NULL;
1140 static inline void tcp_clear_all_retrans_hints(struct tcp_sock *tp)
1142 tcp_clear_retrans_hints_partial(tp);
1143 tp->retransmit_skb_hint = NULL;
1149 union tcp_md5_addr {
1151 #if IS_ENABLED(CONFIG_IPV6)
1156 /* - key database */
1157 struct tcp_md5sig_key {
1158 struct hlist_node node;
1160 u8 family; /* AF_INET or AF_INET6 */
1161 union tcp_md5_addr addr;
1162 u8 key[TCP_MD5SIG_MAXKEYLEN];
1163 struct rcu_head rcu;
1167 struct tcp_md5sig_info {
1168 struct hlist_head head;
1169 struct rcu_head rcu;
1172 /* - pseudo header */
1173 struct tcp4_pseudohdr {
1181 struct tcp6_pseudohdr {
1182 struct in6_addr saddr;
1183 struct in6_addr daddr;
1185 __be32 protocol; /* including padding */
1188 union tcp_md5sum_block {
1189 struct tcp4_pseudohdr ip4;
1190 #if IS_ENABLED(CONFIG_IPV6)
1191 struct tcp6_pseudohdr ip6;
1195 /* - pool: digest algorithm, hash description and scratch buffer */
1196 struct tcp_md5sig_pool {
1197 struct hash_desc md5_desc;
1198 union tcp_md5sum_block md5_blk;
1202 extern int tcp_v4_md5_hash_skb(char *md5_hash, struct tcp_md5sig_key *key,
1203 const struct sock *sk,
1204 const struct request_sock *req,
1205 const struct sk_buff *skb);
1206 extern int tcp_md5_do_add(struct sock *sk, const union tcp_md5_addr *addr,
1207 int family, const u8 *newkey,
1208 u8 newkeylen, gfp_t gfp);
1209 extern int tcp_md5_do_del(struct sock *sk, const union tcp_md5_addr *addr,
1211 extern struct tcp_md5sig_key *tcp_v4_md5_lookup(struct sock *sk,
1212 struct sock *addr_sk);
1214 #ifdef CONFIG_TCP_MD5SIG
1215 extern struct tcp_md5sig_key *tcp_md5_do_lookup(struct sock *sk,
1216 const union tcp_md5_addr *addr, int family);
1217 #define tcp_twsk_md5_key(twsk) ((twsk)->tw_md5_key)
1219 static inline struct tcp_md5sig_key *tcp_md5_do_lookup(struct sock *sk,
1220 const union tcp_md5_addr *addr,
1225 #define tcp_twsk_md5_key(twsk) NULL
1228 extern struct tcp_md5sig_pool __percpu *tcp_alloc_md5sig_pool(struct sock *);
1229 extern void tcp_free_md5sig_pool(void);
1231 extern struct tcp_md5sig_pool *tcp_get_md5sig_pool(void);
1232 extern void tcp_put_md5sig_pool(void);
1234 extern int tcp_md5_hash_header(struct tcp_md5sig_pool *, const struct tcphdr *);
1235 extern int tcp_md5_hash_skb_data(struct tcp_md5sig_pool *, const struct sk_buff *,
1236 unsigned int header_len);
1237 extern int tcp_md5_hash_key(struct tcp_md5sig_pool *hp,
1238 const struct tcp_md5sig_key *key);
1240 /* write queue abstraction */
1241 static inline void tcp_write_queue_purge(struct sock *sk)
1243 struct sk_buff *skb;
1245 while ((skb = __skb_dequeue(&sk->sk_write_queue)) != NULL)
1246 sk_wmem_free_skb(sk, skb);
1248 tcp_clear_all_retrans_hints(tcp_sk(sk));
1251 static inline struct sk_buff *tcp_write_queue_head(const struct sock *sk)
1253 return skb_peek(&sk->sk_write_queue);
1256 static inline struct sk_buff *tcp_write_queue_tail(const struct sock *sk)
1258 return skb_peek_tail(&sk->sk_write_queue);
1261 static inline struct sk_buff *tcp_write_queue_next(const struct sock *sk,
1262 const struct sk_buff *skb)
1264 return skb_queue_next(&sk->sk_write_queue, skb);
1267 static inline struct sk_buff *tcp_write_queue_prev(const struct sock *sk,
1268 const struct sk_buff *skb)
1270 return skb_queue_prev(&sk->sk_write_queue, skb);
1273 #define tcp_for_write_queue(skb, sk) \
1274 skb_queue_walk(&(sk)->sk_write_queue, skb)
1276 #define tcp_for_write_queue_from(skb, sk) \
1277 skb_queue_walk_from(&(sk)->sk_write_queue, skb)
1279 #define tcp_for_write_queue_from_safe(skb, tmp, sk) \
1280 skb_queue_walk_from_safe(&(sk)->sk_write_queue, skb, tmp)
1282 static inline struct sk_buff *tcp_send_head(const struct sock *sk)
1284 return sk->sk_send_head;
1287 static inline bool tcp_skb_is_last(const struct sock *sk,
1288 const struct sk_buff *skb)
1290 return skb_queue_is_last(&sk->sk_write_queue, skb);
1293 static inline void tcp_advance_send_head(struct sock *sk, const struct sk_buff *skb)
1295 if (tcp_skb_is_last(sk, skb))
1296 sk->sk_send_head = NULL;
1298 sk->sk_send_head = tcp_write_queue_next(sk, skb);
1301 static inline void tcp_check_send_head(struct sock *sk, struct sk_buff *skb_unlinked)
1303 if (sk->sk_send_head == skb_unlinked)
1304 sk->sk_send_head = NULL;
1307 static inline void tcp_init_send_head(struct sock *sk)
1309 sk->sk_send_head = NULL;
1312 static inline void __tcp_add_write_queue_tail(struct sock *sk, struct sk_buff *skb)
1314 __skb_queue_tail(&sk->sk_write_queue, skb);
1317 static inline void tcp_add_write_queue_tail(struct sock *sk, struct sk_buff *skb)
1319 __tcp_add_write_queue_tail(sk, skb);
1321 /* Queue it, remembering where we must start sending. */
1322 if (sk->sk_send_head == NULL) {
1323 sk->sk_send_head = skb;
1325 if (tcp_sk(sk)->highest_sack == NULL)
1326 tcp_sk(sk)->highest_sack = skb;
1330 static inline void __tcp_add_write_queue_head(struct sock *sk, struct sk_buff *skb)
1332 __skb_queue_head(&sk->sk_write_queue, skb);
1335 /* Insert buff after skb on the write queue of sk. */
1336 static inline void tcp_insert_write_queue_after(struct sk_buff *skb,
1337 struct sk_buff *buff,
1340 __skb_queue_after(&sk->sk_write_queue, skb, buff);
1343 /* Insert new before skb on the write queue of sk. */
1344 static inline void tcp_insert_write_queue_before(struct sk_buff *new,
1345 struct sk_buff *skb,
1348 __skb_queue_before(&sk->sk_write_queue, skb, new);
1350 if (sk->sk_send_head == skb)
1351 sk->sk_send_head = new;
1354 static inline void tcp_unlink_write_queue(struct sk_buff *skb, struct sock *sk)
1356 __skb_unlink(skb, &sk->sk_write_queue);
1359 static inline int tcp_write_queue_empty(struct sock *sk)
1361 return skb_queue_empty(&sk->sk_write_queue);
1364 static inline void tcp_push_pending_frames(struct sock *sk)
1366 if (tcp_send_head(sk)) {
1367 struct tcp_sock *tp = tcp_sk(sk);
1369 __tcp_push_pending_frames(sk, tcp_current_mss(sk), tp->nonagle);
1373 /* Start sequence of the skb just after the highest skb with SACKed
1374 * bit, valid only if sacked_out > 0 or when the caller has ensured
1375 * validity by itself.
1377 static inline u32 tcp_highest_sack_seq(struct tcp_sock *tp)
1379 if (!tp->sacked_out)
1382 if (tp->highest_sack == NULL)
1385 return TCP_SKB_CB(tp->highest_sack)->seq;
1388 static inline void tcp_advance_highest_sack(struct sock *sk, struct sk_buff *skb)
1390 tcp_sk(sk)->highest_sack = tcp_skb_is_last(sk, skb) ? NULL :
1391 tcp_write_queue_next(sk, skb);
1394 static inline struct sk_buff *tcp_highest_sack(struct sock *sk)
1396 return tcp_sk(sk)->highest_sack;
1399 static inline void tcp_highest_sack_reset(struct sock *sk)
1401 tcp_sk(sk)->highest_sack = tcp_write_queue_head(sk);
1404 /* Called when old skb is about to be deleted (to be combined with new skb) */
1405 static inline void tcp_highest_sack_combine(struct sock *sk,
1406 struct sk_buff *old,
1407 struct sk_buff *new)
1409 if (tcp_sk(sk)->sacked_out && (old == tcp_sk(sk)->highest_sack))
1410 tcp_sk(sk)->highest_sack = new;
1413 /* Determines whether this is a thin stream (which may suffer from
1414 * increased latency). Used to trigger latency-reducing mechanisms.
1416 static inline unsigned int tcp_stream_is_thin(struct tcp_sock *tp)
1418 return tp->packets_out < 4 && !tcp_in_initial_slowstart(tp);
1422 enum tcp_seq_states {
1423 TCP_SEQ_STATE_LISTENING,
1424 TCP_SEQ_STATE_OPENREQ,
1425 TCP_SEQ_STATE_ESTABLISHED,
1426 TCP_SEQ_STATE_TIME_WAIT,
1429 int tcp_seq_open(struct inode *inode, struct file *file);
1431 struct tcp_seq_afinfo {
1434 const struct file_operations *seq_fops;
1435 struct seq_operations seq_ops;
1438 struct tcp_iter_state {
1439 struct seq_net_private p;
1441 enum tcp_seq_states state;
1442 struct sock *syn_wait_sk;
1443 int bucket, offset, sbucket, num, uid;
1447 extern int tcp_proc_register(struct net *net, struct tcp_seq_afinfo *afinfo);
1448 extern void tcp_proc_unregister(struct net *net, struct tcp_seq_afinfo *afinfo);
1450 extern struct request_sock_ops tcp_request_sock_ops;
1451 extern struct request_sock_ops tcp6_request_sock_ops;
1453 extern void tcp_v4_destroy_sock(struct sock *sk);
1455 extern int tcp_v4_gso_send_check(struct sk_buff *skb);
1456 extern struct sk_buff *tcp_tso_segment(struct sk_buff *skb,
1457 netdev_features_t features);
1458 extern struct sk_buff **tcp_gro_receive(struct sk_buff **head,
1459 struct sk_buff *skb);
1460 extern struct sk_buff **tcp4_gro_receive(struct sk_buff **head,
1461 struct sk_buff *skb);
1462 extern int tcp_gro_complete(struct sk_buff *skb);
1463 extern int tcp4_gro_complete(struct sk_buff *skb);
1465 #ifdef CONFIG_PROC_FS
1466 extern int tcp4_proc_init(void);
1467 extern void tcp4_proc_exit(void);
1470 /* TCP af-specific functions */
1471 struct tcp_sock_af_ops {
1472 #ifdef CONFIG_TCP_MD5SIG
1473 struct tcp_md5sig_key *(*md5_lookup) (struct sock *sk,
1474 struct sock *addr_sk);
1475 int (*calc_md5_hash) (char *location,
1476 struct tcp_md5sig_key *md5,
1477 const struct sock *sk,
1478 const struct request_sock *req,
1479 const struct sk_buff *skb);
1480 int (*md5_parse) (struct sock *sk,
1481 char __user *optval,
1486 struct tcp_request_sock_ops {
1487 #ifdef CONFIG_TCP_MD5SIG
1488 struct tcp_md5sig_key *(*md5_lookup) (struct sock *sk,
1489 struct request_sock *req);
1490 int (*calc_md5_hash) (char *location,
1491 struct tcp_md5sig_key *md5,
1492 const struct sock *sk,
1493 const struct request_sock *req,
1494 const struct sk_buff *skb);
1498 /* Using SHA1 for now, define some constants.
1500 #define COOKIE_DIGEST_WORDS (SHA_DIGEST_WORDS)
1501 #define COOKIE_MESSAGE_WORDS (SHA_MESSAGE_BYTES / 4)
1502 #define COOKIE_WORKSPACE_WORDS (COOKIE_DIGEST_WORDS + COOKIE_MESSAGE_WORDS)
1504 extern int tcp_cookie_generator(u32 *bakery);
1507 * struct tcp_cookie_values - each socket needs extra space for the
1508 * cookies, together with (optional) space for any SYN data.
1510 * A tcp_sock contains a pointer to the current value, and this is
1511 * cloned to the tcp_timewait_sock.
1513 * @cookie_pair: variable data from the option exchange.
1515 * @cookie_desired: user specified tcpct_cookie_desired. Zero
1516 * indicates default (sysctl_tcp_cookie_size).
1517 * After cookie sent, remembers size of cookie.
1518 * Range 0, TCP_COOKIE_MIN to TCP_COOKIE_MAX.
1520 * @s_data_desired: user specified tcpct_s_data_desired. When the
1521 * constant payload is specified (@s_data_constant),
1522 * holds its length instead.
1523 * Range 0 to TCP_MSS_DESIRED.
1525 * @s_data_payload: constant data that is to be included in the
1526 * payload of SYN or SYNACK segments when the
1527 * cookie option is present.
1529 struct tcp_cookie_values {
1531 u8 cookie_pair[TCP_COOKIE_PAIR_SIZE];
1532 u8 cookie_pair_size;
1534 u16 s_data_desired:11,
1539 u8 s_data_payload[0];
1542 static inline void tcp_cookie_values_release(struct kref *kref)
1544 kfree(container_of(kref, struct tcp_cookie_values, kref));
1547 /* The length of constant payload data. Note that s_data_desired is
1548 * overloaded, depending on s_data_constant: either the length of constant
1549 * data (returned here) or the limit on variable data.
1551 static inline int tcp_s_data_size(const struct tcp_sock *tp)
1553 return (tp->cookie_values != NULL && tp->cookie_values->s_data_constant)
1554 ? tp->cookie_values->s_data_desired
1559 * struct tcp_extend_values - tcp_ipv?.c to tcp_output.c workspace.
1561 * As tcp_request_sock has already been extended in other places, the
1562 * only remaining method is to pass stack values along as function
1563 * parameters. These parameters are not needed after sending SYNACK.
1565 * @cookie_bakery: cryptographic secret and message workspace.
1567 * @cookie_plus: bytes in authenticator/cookie option, copied from
1568 * struct tcp_options_received (above).
1570 struct tcp_extend_values {
1571 struct request_values rv;
1572 u32 cookie_bakery[COOKIE_WORKSPACE_WORDS];
1578 static inline struct tcp_extend_values *tcp_xv(struct request_values *rvp)
1580 return (struct tcp_extend_values *)rvp;
1583 extern void tcp_v4_init(void);
1584 extern void tcp_init(void);