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.
22 #define FASTRETRANS_DEBUG 1
24 #include <linux/list.h>
25 #include <linux/tcp.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>
49 extern struct inet_hashinfo tcp_hashinfo;
51 extern struct percpu_counter tcp_orphan_count;
52 extern void tcp_time_wait(struct sock *sk, int state, int timeo);
54 #define MAX_TCP_HEADER (128 + MAX_HEADER)
55 #define MAX_TCP_OPTION_SPACE 40
58 * Never offer a window over 32767 without using window scaling. Some
59 * poor stacks do signed 16bit maths!
61 #define MAX_TCP_WINDOW 32767U
63 /* Offer an initial receive window of 10 mss. */
64 #define TCP_DEFAULT_INIT_RCVWND 10
66 /* Minimal accepted MSS. It is (60+60+8) - (20+20). */
67 #define TCP_MIN_MSS 88U
69 /* The least MTU to use for probing */
70 #define TCP_BASE_MSS 512
72 /* After receiving this amount of duplicate ACKs fast retransmit starts. */
73 #define TCP_FASTRETRANS_THRESH 3
75 /* Maximal reordering. */
76 #define TCP_MAX_REORDERING 127
78 /* Maximal number of ACKs sent quickly to accelerate slow-start. */
79 #define TCP_MAX_QUICKACKS 16U
82 #define TCP_URG_VALID 0x0100
83 #define TCP_URG_NOTYET 0x0200
84 #define TCP_URG_READ 0x0400
86 #define TCP_RETR1 3 /*
87 * This is how many retries it does before it
88 * tries to figure out if the gateway is
89 * down. Minimal RFC value is 3; it corresponds
90 * to ~3sec-8min depending on RTO.
93 #define TCP_RETR2 15 /*
94 * This should take at least
95 * 90 minutes to time out.
96 * RFC1122 says that the limit is 100 sec.
97 * 15 is ~13-30min depending on RTO.
100 #define TCP_SYN_RETRIES 5 /* number of times to retry active opening a
101 * connection: ~180sec is RFC minimum */
103 #define TCP_SYNACK_RETRIES 5 /* number of times to retry passive opening a
104 * connection: ~180sec is RFC minimum */
106 #define TCP_TIMEWAIT_LEN (60*HZ) /* how long to wait to destroy TIME-WAIT
107 * state, about 60 seconds */
108 #define TCP_FIN_TIMEOUT TCP_TIMEWAIT_LEN
109 /* BSD style FIN_WAIT2 deadlock breaker.
110 * It used to be 3min, new value is 60sec,
111 * to combine FIN-WAIT-2 timeout with
115 #define TCP_DELACK_MAX ((unsigned)(HZ/5)) /* maximal time to delay before sending an ACK */
117 #define TCP_DELACK_MIN ((unsigned)(HZ/25)) /* minimal time to delay before sending an ACK */
118 #define TCP_ATO_MIN ((unsigned)(HZ/25))
120 #define TCP_DELACK_MIN 4U
121 #define TCP_ATO_MIN 4U
123 #define TCP_RTO_MAX ((unsigned)(120*HZ))
124 #define TCP_RTO_MIN ((unsigned)(HZ/5))
125 #define TCP_TIMEOUT_INIT ((unsigned)(1*HZ)) /* RFC2988bis initial RTO value */
126 #define TCP_TIMEOUT_FALLBACK ((unsigned)(3*HZ)) /* RFC 1122 initial RTO value, now
127 * used as a fallback RTO for the
128 * initial data transmission if no
129 * valid RTT sample has been acquired,
130 * most likely due to retrans in 3WHS.
133 #define TCP_RESOURCE_PROBE_INTERVAL ((unsigned)(HZ/2U)) /* Maximal interval between probes
134 * for local resources.
137 #define TCP_KEEPALIVE_TIME (120*60*HZ) /* two hours */
138 #define TCP_KEEPALIVE_PROBES 9 /* Max of 9 keepalive probes */
139 #define TCP_KEEPALIVE_INTVL (75*HZ)
141 #define MAX_TCP_KEEPIDLE 32767
142 #define MAX_TCP_KEEPINTVL 32767
143 #define MAX_TCP_KEEPCNT 127
144 #define MAX_TCP_SYNCNT 127
146 #define TCP_SYNQ_INTERVAL (HZ/5) /* Period of SYNACK timer */
148 #define TCP_PAWS_24DAYS (60 * 60 * 24 * 24)
149 #define TCP_PAWS_MSL 60 /* Per-host timestamps are invalidated
150 * after this time. It should be equal
151 * (or greater than) TCP_TIMEWAIT_LEN
152 * to provide reliability equal to one
153 * provided by timewait state.
155 #define TCP_PAWS_WINDOW 1 /* Replay window for per-host
156 * timestamps. It must be less than
157 * minimal timewait lifetime.
163 #define TCPOPT_NOP 1 /* Padding */
164 #define TCPOPT_EOL 0 /* End of options */
165 #define TCPOPT_MSS 2 /* Segment size negotiating */
166 #define TCPOPT_WINDOW 3 /* Window scaling */
167 #define TCPOPT_SACK_PERM 4 /* SACK Permitted */
168 #define TCPOPT_SACK 5 /* SACK Block */
169 #define TCPOPT_TIMESTAMP 8 /* Better RTT estimations/PAWS */
170 #define TCPOPT_MD5SIG 19 /* MD5 Signature (RFC2385) */
171 #define TCPOPT_COOKIE 253 /* Cookie extension (experimental) */
177 #define TCPOLEN_MSS 4
178 #define TCPOLEN_WINDOW 3
179 #define TCPOLEN_SACK_PERM 2
180 #define TCPOLEN_TIMESTAMP 10
181 #define TCPOLEN_MD5SIG 18
182 #define TCPOLEN_COOKIE_BASE 2 /* Cookie-less header extension */
183 #define TCPOLEN_COOKIE_PAIR 3 /* Cookie pair header extension */
184 #define TCPOLEN_COOKIE_MIN (TCPOLEN_COOKIE_BASE+TCP_COOKIE_MIN)
185 #define TCPOLEN_COOKIE_MAX (TCPOLEN_COOKIE_BASE+TCP_COOKIE_MAX)
187 /* But this is what stacks really send out. */
188 #define TCPOLEN_TSTAMP_ALIGNED 12
189 #define TCPOLEN_WSCALE_ALIGNED 4
190 #define TCPOLEN_SACKPERM_ALIGNED 4
191 #define TCPOLEN_SACK_BASE 2
192 #define TCPOLEN_SACK_BASE_ALIGNED 4
193 #define TCPOLEN_SACK_PERBLOCK 8
194 #define TCPOLEN_MD5SIG_ALIGNED 20
195 #define TCPOLEN_MSS_ALIGNED 4
197 /* Flags in tp->nonagle */
198 #define TCP_NAGLE_OFF 1 /* Nagle's algo is disabled */
199 #define TCP_NAGLE_CORK 2 /* Socket is corked */
200 #define TCP_NAGLE_PUSH 4 /* Cork is overridden for already queued data */
202 /* TCP thin-stream limits */
203 #define TCP_THIN_LINEAR_RETRIES 6 /* After 6 linear retries, do exp. backoff */
205 /* TCP initial congestion window as per draft-hkchu-tcpm-initcwnd-01 */
206 #define TCP_INIT_CWND 10
208 extern struct inet_timewait_death_row tcp_death_row;
210 /* sysctl variables for tcp */
211 extern int sysctl_tcp_timestamps;
212 extern int sysctl_tcp_window_scaling;
213 extern int sysctl_tcp_sack;
214 extern int sysctl_tcp_fin_timeout;
215 extern int sysctl_tcp_keepalive_time;
216 extern int sysctl_tcp_keepalive_probes;
217 extern int sysctl_tcp_keepalive_intvl;
218 extern int sysctl_tcp_syn_retries;
219 extern int sysctl_tcp_synack_retries;
220 extern int sysctl_tcp_retries1;
221 extern int sysctl_tcp_retries2;
222 extern int sysctl_tcp_orphan_retries;
223 extern int sysctl_tcp_syncookies;
224 extern int sysctl_tcp_retrans_collapse;
225 extern int sysctl_tcp_stdurg;
226 extern int sysctl_tcp_rfc1337;
227 extern int sysctl_tcp_abort_on_overflow;
228 extern int sysctl_tcp_max_orphans;
229 extern int sysctl_tcp_fack;
230 extern int sysctl_tcp_reordering;
231 extern int sysctl_tcp_ecn;
232 extern int sysctl_tcp_dsack;
233 extern long sysctl_tcp_mem[3];
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_too_many_orphans(struct sock *sk, int shift)
279 struct percpu_counter *ocp = sk->sk_prot->orphan_count;
280 int orphans = percpu_counter_read_positive(ocp);
282 if (orphans << shift > sysctl_tcp_max_orphans) {
283 orphans = percpu_counter_sum_positive(ocp);
284 if (orphans << shift > sysctl_tcp_max_orphans)
288 if (sk->sk_wmem_queued > SOCK_MIN_SNDBUF &&
289 atomic_long_read(&tcp_memory_allocated) > sysctl_tcp_mem[2])
294 /* syncookies: remember time of last synqueue overflow */
295 static inline void tcp_synq_overflow(struct sock *sk)
297 tcp_sk(sk)->rx_opt.ts_recent_stamp = jiffies;
300 /* syncookies: no recent synqueue overflow on this listening socket? */
301 static inline int tcp_synq_no_recent_overflow(const struct sock *sk)
303 unsigned long last_overflow = tcp_sk(sk)->rx_opt.ts_recent_stamp;
304 return time_after(jiffies, last_overflow + TCP_TIMEOUT_FALLBACK);
307 extern struct proto tcp_prot;
309 #define TCP_INC_STATS(net, field) SNMP_INC_STATS((net)->mib.tcp_statistics, field)
310 #define TCP_INC_STATS_BH(net, field) SNMP_INC_STATS_BH((net)->mib.tcp_statistics, field)
311 #define TCP_DEC_STATS(net, field) SNMP_DEC_STATS((net)->mib.tcp_statistics, field)
312 #define TCP_ADD_STATS_USER(net, field, val) SNMP_ADD_STATS_USER((net)->mib.tcp_statistics, field, val)
313 #define TCP_ADD_STATS(net, field, val) SNMP_ADD_STATS((net)->mib.tcp_statistics, field, val)
315 extern void tcp_v4_err(struct sk_buff *skb, u32);
317 extern void tcp_shutdown (struct sock *sk, int how);
319 extern int tcp_v4_rcv(struct sk_buff *skb);
321 extern struct inet_peer *tcp_v4_get_peer(struct sock *sk, bool *release_it);
322 extern void *tcp_v4_tw_get_peer(struct sock *sk);
323 extern int tcp_v4_tw_remember_stamp(struct inet_timewait_sock *tw);
324 extern int tcp_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
326 extern int tcp_sendpage(struct sock *sk, struct page *page, int offset,
327 size_t size, int flags);
328 extern int tcp_ioctl(struct sock *sk, int cmd, unsigned long arg);
329 extern int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb,
330 struct tcphdr *th, unsigned len);
331 extern int tcp_rcv_established(struct sock *sk, struct sk_buff *skb,
332 struct tcphdr *th, unsigned len);
333 extern void tcp_rcv_space_adjust(struct sock *sk);
334 extern void tcp_cleanup_rbuf(struct sock *sk, int copied);
335 extern int tcp_twsk_unique(struct sock *sk, struct sock *sktw, void *twp);
336 extern void tcp_twsk_destructor(struct sock *sk);
337 extern ssize_t tcp_splice_read(struct socket *sk, loff_t *ppos,
338 struct pipe_inode_info *pipe, size_t len,
341 static inline void tcp_dec_quickack_mode(struct sock *sk,
342 const unsigned int pkts)
344 struct inet_connection_sock *icsk = inet_csk(sk);
346 if (icsk->icsk_ack.quick) {
347 if (pkts >= icsk->icsk_ack.quick) {
348 icsk->icsk_ack.quick = 0;
349 /* Leaving quickack mode we deflate ATO. */
350 icsk->icsk_ack.ato = TCP_ATO_MIN;
352 icsk->icsk_ack.quick -= pkts;
357 #define TCP_ECN_QUEUE_CWR 2
358 #define TCP_ECN_DEMAND_CWR 4
360 static __inline__ void
361 TCP_ECN_create_request(struct request_sock *req, struct tcphdr *th)
363 if (sysctl_tcp_ecn && th->ece && th->cwr)
364 inet_rsk(req)->ecn_ok = 1;
375 extern enum tcp_tw_status tcp_timewait_state_process(struct inet_timewait_sock *tw,
377 const struct tcphdr *th);
378 extern struct sock * tcp_check_req(struct sock *sk,struct sk_buff *skb,
379 struct request_sock *req,
380 struct request_sock **prev);
381 extern int tcp_child_process(struct sock *parent, struct sock *child,
382 struct sk_buff *skb);
383 extern int tcp_use_frto(struct sock *sk);
384 extern void tcp_enter_frto(struct sock *sk);
385 extern void tcp_enter_loss(struct sock *sk, int how);
386 extern void tcp_clear_retrans(struct tcp_sock *tp);
387 extern void tcp_update_metrics(struct sock *sk);
388 extern void tcp_close(struct sock *sk, long timeout);
389 extern unsigned int tcp_poll(struct file * file, struct socket *sock,
390 struct poll_table_struct *wait);
391 extern int tcp_getsockopt(struct sock *sk, int level, int optname,
392 char __user *optval, int __user *optlen);
393 extern int tcp_setsockopt(struct sock *sk, int level, int optname,
394 char __user *optval, unsigned int optlen);
395 extern int compat_tcp_getsockopt(struct sock *sk, int level, int optname,
396 char __user *optval, int __user *optlen);
397 extern int compat_tcp_setsockopt(struct sock *sk, int level, int optname,
398 char __user *optval, unsigned int optlen);
399 extern void tcp_set_keepalive(struct sock *sk, int val);
400 extern void tcp_syn_ack_timeout(struct sock *sk, struct request_sock *req);
401 extern int tcp_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
402 size_t len, int nonblock, int flags, int *addr_len);
403 extern void tcp_parse_options(struct sk_buff *skb,
404 struct tcp_options_received *opt_rx, u8 **hvpp,
406 extern u8 *tcp_parse_md5sig_option(struct tcphdr *th);
409 * TCP v4 functions exported for the inet6 API
412 extern void tcp_v4_send_check(struct sock *sk, struct sk_buff *skb);
413 extern int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb);
414 extern struct sock * tcp_create_openreq_child(struct sock *sk,
415 struct request_sock *req,
416 struct sk_buff *skb);
417 extern struct sock * tcp_v4_syn_recv_sock(struct sock *sk, struct sk_buff *skb,
418 struct request_sock *req,
419 struct dst_entry *dst);
420 extern int tcp_v4_do_rcv(struct sock *sk, struct sk_buff *skb);
421 extern int tcp_v4_connect(struct sock *sk, struct sockaddr *uaddr,
423 extern int tcp_connect(struct sock *sk);
424 extern struct sk_buff * tcp_make_synack(struct sock *sk, struct dst_entry *dst,
425 struct request_sock *req,
426 struct request_values *rvp);
427 extern int tcp_disconnect(struct sock *sk, int flags);
430 /* From syncookies.c */
431 extern __u32 syncookie_secret[2][16-4+SHA_DIGEST_WORDS];
432 extern struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb,
433 struct ip_options *opt);
434 extern __u32 cookie_v4_init_sequence(struct sock *sk, struct sk_buff *skb,
437 extern __u32 cookie_init_timestamp(struct request_sock *req);
438 extern bool cookie_check_timestamp(struct tcp_options_received *opt, bool *);
440 /* From net/ipv6/syncookies.c */
441 extern struct sock *cookie_v6_check(struct sock *sk, struct sk_buff *skb);
442 extern __u32 cookie_v6_init_sequence(struct sock *sk, struct sk_buff *skb,
447 extern void __tcp_push_pending_frames(struct sock *sk, unsigned int cur_mss,
449 extern int tcp_may_send_now(struct sock *sk);
450 extern int tcp_retransmit_skb(struct sock *, struct sk_buff *);
451 extern void tcp_retransmit_timer(struct sock *sk);
452 extern void tcp_xmit_retransmit_queue(struct sock *);
453 extern void tcp_simple_retransmit(struct sock *);
454 extern int tcp_trim_head(struct sock *, struct sk_buff *, u32);
455 extern int tcp_fragment(struct sock *, struct sk_buff *, u32, unsigned int);
457 extern void tcp_send_probe0(struct sock *);
458 extern void tcp_send_partial(struct sock *);
459 extern int tcp_write_wakeup(struct sock *);
460 extern void tcp_send_fin(struct sock *sk);
461 extern void tcp_send_active_reset(struct sock *sk, gfp_t priority);
462 extern int tcp_send_synack(struct sock *);
463 extern int tcp_syn_flood_action(struct sock *sk,
464 const struct sk_buff *skb,
466 extern void tcp_push_one(struct sock *, unsigned int mss_now);
467 extern void tcp_send_ack(struct sock *sk);
468 extern void tcp_send_delayed_ack(struct sock *sk);
471 extern void tcp_cwnd_application_limited(struct sock *sk);
474 extern void tcp_init_xmit_timers(struct sock *);
475 static inline void tcp_clear_xmit_timers(struct sock *sk)
477 inet_csk_clear_xmit_timers(sk);
480 extern unsigned int tcp_sync_mss(struct sock *sk, u32 pmtu);
481 extern unsigned int tcp_current_mss(struct sock *sk);
483 /* Bound MSS / TSO packet size with the half of the window */
484 static inline int tcp_bound_to_half_wnd(struct tcp_sock *tp, int pktsize)
488 /* When peer uses tiny windows, there is no use in packetizing
489 * to sub-MSS pieces for the sake of SWS or making sure there
490 * are enough packets in the pipe for fast recovery.
492 * On the other hand, for extremely large MSS devices, handling
493 * smaller than MSS windows in this way does make sense.
495 if (tp->max_window >= 512)
496 cutoff = (tp->max_window >> 1);
498 cutoff = tp->max_window;
500 if (cutoff && pktsize > cutoff)
501 return max_t(int, cutoff, 68U - tp->tcp_header_len);
507 extern void tcp_get_info(struct sock *, struct tcp_info *);
509 /* Read 'sendfile()'-style from a TCP socket */
510 typedef int (*sk_read_actor_t)(read_descriptor_t *, struct sk_buff *,
511 unsigned int, size_t);
512 extern int tcp_read_sock(struct sock *sk, read_descriptor_t *desc,
513 sk_read_actor_t recv_actor);
515 extern void tcp_initialize_rcv_mss(struct sock *sk);
517 extern int tcp_mtu_to_mss(struct sock *sk, int pmtu);
518 extern int tcp_mss_to_mtu(struct sock *sk, int mss);
519 extern void tcp_mtup_init(struct sock *sk);
520 extern void tcp_valid_rtt_meas(struct sock *sk, u32 seq_rtt);
522 static inline void tcp_bound_rto(const struct sock *sk)
524 if (inet_csk(sk)->icsk_rto > TCP_RTO_MAX)
525 inet_csk(sk)->icsk_rto = TCP_RTO_MAX;
528 static inline u32 __tcp_set_rto(const struct tcp_sock *tp)
530 return (tp->srtt >> 3) + tp->rttvar;
533 static inline void __tcp_fast_path_on(struct tcp_sock *tp, u32 snd_wnd)
535 tp->pred_flags = htonl((tp->tcp_header_len << 26) |
536 ntohl(TCP_FLAG_ACK) |
540 static inline void tcp_fast_path_on(struct tcp_sock *tp)
542 __tcp_fast_path_on(tp, tp->snd_wnd >> tp->rx_opt.snd_wscale);
545 static inline void tcp_fast_path_check(struct sock *sk)
547 struct tcp_sock *tp = tcp_sk(sk);
549 if (skb_queue_empty(&tp->out_of_order_queue) &&
551 atomic_read(&sk->sk_rmem_alloc) < sk->sk_rcvbuf &&
553 tcp_fast_path_on(tp);
556 /* Compute the actual rto_min value */
557 static inline u32 tcp_rto_min(struct sock *sk)
559 struct dst_entry *dst = __sk_dst_get(sk);
560 u32 rto_min = TCP_RTO_MIN;
562 if (dst && dst_metric_locked(dst, RTAX_RTO_MIN))
563 rto_min = dst_metric_rtt(dst, RTAX_RTO_MIN);
567 /* Compute the actual receive window we are currently advertising.
568 * Rcv_nxt can be after the window if our peer push more data
569 * than the offered window.
571 static inline u32 tcp_receive_window(const struct tcp_sock *tp)
573 s32 win = tp->rcv_wup + tp->rcv_wnd - tp->rcv_nxt;
580 /* Choose a new window, without checks for shrinking, and without
581 * scaling applied to the result. The caller does these things
582 * if necessary. This is a "raw" window selection.
584 extern u32 __tcp_select_window(struct sock *sk);
586 /* TCP timestamps are only 32-bits, this causes a slight
587 * complication on 64-bit systems since we store a snapshot
588 * of jiffies in the buffer control blocks below. We decided
589 * to use only the low 32-bits of jiffies and hide the ugly
590 * casts with the following macro.
592 #define tcp_time_stamp ((__u32)(jiffies))
594 #define tcp_flag_byte(th) (((u_int8_t *)th)[13])
596 #define TCPHDR_FIN 0x01
597 #define TCPHDR_SYN 0x02
598 #define TCPHDR_RST 0x04
599 #define TCPHDR_PSH 0x08
600 #define TCPHDR_ACK 0x10
601 #define TCPHDR_URG 0x20
602 #define TCPHDR_ECE 0x40
603 #define TCPHDR_CWR 0x80
605 /* This is what the send packet queuing engine uses to pass
606 * TCP per-packet control information to the transmission code.
607 * We also store the host-order sequence numbers in here too.
608 * This is 44 bytes if IPV6 is enabled.
609 * If this grows please adjust skbuff.h:skbuff->cb[xxx] size appropriately.
613 struct inet_skb_parm h4;
614 #if defined(CONFIG_IPV6) || defined (CONFIG_IPV6_MODULE)
615 struct inet6_skb_parm h6;
617 } header; /* For incoming frames */
618 __u32 seq; /* Starting sequence number */
619 __u32 end_seq; /* SEQ + FIN + SYN + datalen */
620 __u32 when; /* used to compute rtt's */
621 __u8 flags; /* TCP header flags. */
622 __u8 sacked; /* State flags for SACK/FACK. */
623 #define TCPCB_SACKED_ACKED 0x01 /* SKB ACK'd by a SACK block */
624 #define TCPCB_SACKED_RETRANS 0x02 /* SKB retransmitted */
625 #define TCPCB_LOST 0x04 /* SKB is lost */
626 #define TCPCB_TAGBITS 0x07 /* All tag bits */
628 #define TCPCB_EVER_RETRANS 0x80 /* Ever retransmitted frame */
629 #define TCPCB_RETRANS (TCPCB_SACKED_RETRANS|TCPCB_EVER_RETRANS)
631 __u32 ack_seq; /* Sequence number ACK'd */
634 #define TCP_SKB_CB(__skb) ((struct tcp_skb_cb *)&((__skb)->cb[0]))
636 /* Due to TSO, an SKB can be composed of multiple actual
637 * packets. To keep these tracked properly, we use this.
639 static inline int tcp_skb_pcount(const struct sk_buff *skb)
641 return skb_shinfo(skb)->gso_segs;
644 /* This is valid iff tcp_skb_pcount() > 1. */
645 static inline int tcp_skb_mss(const struct sk_buff *skb)
647 return skb_shinfo(skb)->gso_size;
650 /* Events passed to congestion control interface */
652 CA_EVENT_TX_START, /* first transmit when no packets in flight */
653 CA_EVENT_CWND_RESTART, /* congestion window restart */
654 CA_EVENT_COMPLETE_CWR, /* end of congestion recovery */
655 CA_EVENT_FRTO, /* fast recovery timeout */
656 CA_EVENT_LOSS, /* loss timeout */
657 CA_EVENT_FAST_ACK, /* in sequence ack */
658 CA_EVENT_SLOW_ACK, /* other ack */
662 * Interface for adding new TCP congestion control handlers
664 #define TCP_CA_NAME_MAX 16
665 #define TCP_CA_MAX 128
666 #define TCP_CA_BUF_MAX (TCP_CA_NAME_MAX*TCP_CA_MAX)
668 #define TCP_CONG_NON_RESTRICTED 0x1
669 #define TCP_CONG_RTT_STAMP 0x2
671 struct tcp_congestion_ops {
672 struct list_head list;
675 /* initialize private data (optional) */
676 void (*init)(struct sock *sk);
677 /* cleanup private data (optional) */
678 void (*release)(struct sock *sk);
680 /* return slow start threshold (required) */
681 u32 (*ssthresh)(struct sock *sk);
682 /* lower bound for congestion window (optional) */
683 u32 (*min_cwnd)(const struct sock *sk);
684 /* do new cwnd calculation (required) */
685 void (*cong_avoid)(struct sock *sk, u32 ack, u32 in_flight);
686 /* call before changing ca_state (optional) */
687 void (*set_state)(struct sock *sk, u8 new_state);
688 /* call when cwnd event occurs (optional) */
689 void (*cwnd_event)(struct sock *sk, enum tcp_ca_event ev);
690 /* new value of cwnd after loss (optional) */
691 u32 (*undo_cwnd)(struct sock *sk);
692 /* hook for packet ack accounting (optional) */
693 void (*pkts_acked)(struct sock *sk, u32 num_acked, s32 rtt_us);
694 /* get info for inet_diag (optional) */
695 void (*get_info)(struct sock *sk, u32 ext, struct sk_buff *skb);
697 char name[TCP_CA_NAME_MAX];
698 struct module *owner;
701 extern int tcp_register_congestion_control(struct tcp_congestion_ops *type);
702 extern void tcp_unregister_congestion_control(struct tcp_congestion_ops *type);
704 extern void tcp_init_congestion_control(struct sock *sk);
705 extern void tcp_cleanup_congestion_control(struct sock *sk);
706 extern int tcp_set_default_congestion_control(const char *name);
707 extern void tcp_get_default_congestion_control(char *name);
708 extern void tcp_get_available_congestion_control(char *buf, size_t len);
709 extern void tcp_get_allowed_congestion_control(char *buf, size_t len);
710 extern int tcp_set_allowed_congestion_control(char *allowed);
711 extern int tcp_set_congestion_control(struct sock *sk, const char *name);
712 extern void tcp_slow_start(struct tcp_sock *tp);
713 extern void tcp_cong_avoid_ai(struct tcp_sock *tp, u32 w);
715 extern struct tcp_congestion_ops tcp_init_congestion_ops;
716 extern u32 tcp_reno_ssthresh(struct sock *sk);
717 extern void tcp_reno_cong_avoid(struct sock *sk, u32 ack, u32 in_flight);
718 extern u32 tcp_reno_min_cwnd(const struct sock *sk);
719 extern struct tcp_congestion_ops tcp_reno;
721 static inline void tcp_set_ca_state(struct sock *sk, const u8 ca_state)
723 struct inet_connection_sock *icsk = inet_csk(sk);
725 if (icsk->icsk_ca_ops->set_state)
726 icsk->icsk_ca_ops->set_state(sk, ca_state);
727 icsk->icsk_ca_state = ca_state;
730 static inline void tcp_ca_event(struct sock *sk, const enum tcp_ca_event event)
732 const struct inet_connection_sock *icsk = inet_csk(sk);
734 if (icsk->icsk_ca_ops->cwnd_event)
735 icsk->icsk_ca_ops->cwnd_event(sk, event);
738 /* These functions determine how the current flow behaves in respect of SACK
739 * handling. SACK is negotiated with the peer, and therefore it can vary
740 * between different flows.
742 * tcp_is_sack - SACK enabled
743 * tcp_is_reno - No SACK
744 * tcp_is_fack - FACK enabled, implies SACK enabled
746 static inline int tcp_is_sack(const struct tcp_sock *tp)
748 return tp->rx_opt.sack_ok;
751 static inline int tcp_is_reno(const struct tcp_sock *tp)
753 return !tcp_is_sack(tp);
756 static inline int tcp_is_fack(const struct tcp_sock *tp)
758 return tp->rx_opt.sack_ok & 2;
761 static inline void tcp_enable_fack(struct tcp_sock *tp)
763 tp->rx_opt.sack_ok |= 2;
766 static inline unsigned int tcp_left_out(const struct tcp_sock *tp)
768 return tp->sacked_out + tp->lost_out;
771 /* This determines how many packets are "in the network" to the best
772 * of our knowledge. In many cases it is conservative, but where
773 * detailed information is available from the receiver (via SACK
774 * blocks etc.) we can make more aggressive calculations.
776 * Use this for decisions involving congestion control, use just
777 * tp->packets_out to determine if the send queue is empty or not.
779 * Read this equation as:
781 * "Packets sent once on transmission queue" MINUS
782 * "Packets left network, but not honestly ACKed yet" PLUS
783 * "Packets fast retransmitted"
785 static inline unsigned int tcp_packets_in_flight(const struct tcp_sock *tp)
787 return tp->packets_out - tcp_left_out(tp) + tp->retrans_out;
790 #define TCP_INFINITE_SSTHRESH 0x7fffffff
792 static inline bool tcp_in_initial_slowstart(const struct tcp_sock *tp)
794 return tp->snd_ssthresh >= TCP_INFINITE_SSTHRESH;
797 /* If cwnd > ssthresh, we may raise ssthresh to be half-way to cwnd.
798 * The exception is rate halving phase, when cwnd is decreasing towards
801 static inline __u32 tcp_current_ssthresh(const struct sock *sk)
803 const struct tcp_sock *tp = tcp_sk(sk);
804 if ((1 << inet_csk(sk)->icsk_ca_state) & (TCPF_CA_CWR | TCPF_CA_Recovery))
805 return tp->snd_ssthresh;
807 return max(tp->snd_ssthresh,
808 ((tp->snd_cwnd >> 1) +
809 (tp->snd_cwnd >> 2)));
812 /* Use define here intentionally to get WARN_ON location shown at the caller */
813 #define tcp_verify_left_out(tp) WARN_ON(tcp_left_out(tp) > tp->packets_out)
815 extern void tcp_enter_cwr(struct sock *sk, const int set_ssthresh);
816 extern __u32 tcp_init_cwnd(struct tcp_sock *tp, struct dst_entry *dst);
818 /* Slow start with delack produces 3 packets of burst, so that
819 * it is safe "de facto". This will be the default - same as
820 * the default reordering threshold - but if reordering increases,
821 * we must be able to allow cwnd to burst at least this much in order
822 * to not pull it back when holes are filled.
824 static __inline__ __u32 tcp_max_burst(const struct tcp_sock *tp)
826 return tp->reordering;
829 /* Returns end sequence number of the receiver's advertised window */
830 static inline u32 tcp_wnd_end(const struct tcp_sock *tp)
832 return tp->snd_una + tp->snd_wnd;
834 extern int tcp_is_cwnd_limited(const struct sock *sk, u32 in_flight);
836 static inline void tcp_minshall_update(struct tcp_sock *tp, unsigned int mss,
837 const struct sk_buff *skb)
840 tp->snd_sml = TCP_SKB_CB(skb)->end_seq;
843 static inline void tcp_check_probe_timer(struct sock *sk)
845 struct tcp_sock *tp = tcp_sk(sk);
846 const struct inet_connection_sock *icsk = inet_csk(sk);
848 if (!tp->packets_out && !icsk->icsk_pending)
849 inet_csk_reset_xmit_timer(sk, ICSK_TIME_PROBE0,
850 icsk->icsk_rto, TCP_RTO_MAX);
853 static inline void tcp_init_wl(struct tcp_sock *tp, u32 seq)
858 static inline void tcp_update_wl(struct tcp_sock *tp, u32 seq)
864 * Calculate(/check) TCP checksum
866 static inline __sum16 tcp_v4_check(int len, __be32 saddr,
867 __be32 daddr, __wsum base)
869 return csum_tcpudp_magic(saddr,daddr,len,IPPROTO_TCP,base);
872 static inline __sum16 __tcp_checksum_complete(struct sk_buff *skb)
874 return __skb_checksum_complete(skb);
877 static inline int tcp_checksum_complete(struct sk_buff *skb)
879 return !skb_csum_unnecessary(skb) &&
880 __tcp_checksum_complete(skb);
883 /* Prequeue for VJ style copy to user, combined with checksumming. */
885 static inline void tcp_prequeue_init(struct tcp_sock *tp)
887 tp->ucopy.task = NULL;
889 tp->ucopy.memory = 0;
890 skb_queue_head_init(&tp->ucopy.prequeue);
891 #ifdef CONFIG_NET_DMA
892 tp->ucopy.dma_chan = NULL;
893 tp->ucopy.wakeup = 0;
894 tp->ucopy.pinned_list = NULL;
895 tp->ucopy.dma_cookie = 0;
899 /* Packet is added to VJ-style prequeue for processing in process
900 * context, if a reader task is waiting. Apparently, this exciting
901 * idea (VJ's mail "Re: query about TCP header on tcp-ip" of 07 Sep 93)
902 * failed somewhere. Latency? Burstiness? Well, at least now we will
903 * see, why it failed. 8)8) --ANK
905 * NOTE: is this not too big to inline?
907 static inline int tcp_prequeue(struct sock *sk, struct sk_buff *skb)
909 struct tcp_sock *tp = tcp_sk(sk);
911 if (sysctl_tcp_low_latency || !tp->ucopy.task)
914 __skb_queue_tail(&tp->ucopy.prequeue, skb);
915 tp->ucopy.memory += skb->truesize;
916 if (tp->ucopy.memory > sk->sk_rcvbuf) {
917 struct sk_buff *skb1;
919 BUG_ON(sock_owned_by_user(sk));
921 while ((skb1 = __skb_dequeue(&tp->ucopy.prequeue)) != NULL) {
922 sk_backlog_rcv(sk, skb1);
923 NET_INC_STATS_BH(sock_net(sk),
924 LINUX_MIB_TCPPREQUEUEDROPPED);
927 tp->ucopy.memory = 0;
928 } else if (skb_queue_len(&tp->ucopy.prequeue) == 1) {
929 wake_up_interruptible_sync_poll(sk_sleep(sk),
930 POLLIN | POLLRDNORM | POLLRDBAND);
931 if (!inet_csk_ack_scheduled(sk))
932 inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK,
933 (3 * tcp_rto_min(sk)) / 4,
943 static const char *statename[]={
944 "Unused","Established","Syn Sent","Syn Recv",
945 "Fin Wait 1","Fin Wait 2","Time Wait", "Close",
946 "Close Wait","Last ACK","Listen","Closing"
949 extern void tcp_set_state(struct sock *sk, int state);
951 extern void tcp_done(struct sock *sk);
953 static inline void tcp_sack_reset(struct tcp_options_received *rx_opt)
956 rx_opt->num_sacks = 0;
959 /* Determine a window scaling and initial window to offer. */
960 extern void tcp_select_initial_window(int __space, __u32 mss,
961 __u32 *rcv_wnd, __u32 *window_clamp,
962 int wscale_ok, __u8 *rcv_wscale,
965 static inline int tcp_win_from_space(int space)
967 return sysctl_tcp_adv_win_scale<=0 ?
968 (space>>(-sysctl_tcp_adv_win_scale)) :
969 space - (space>>sysctl_tcp_adv_win_scale);
972 /* Note: caller must be prepared to deal with negative returns */
973 static inline int tcp_space(const struct sock *sk)
975 return tcp_win_from_space(sk->sk_rcvbuf -
976 atomic_read(&sk->sk_rmem_alloc));
979 static inline int tcp_full_space(const struct sock *sk)
981 return tcp_win_from_space(sk->sk_rcvbuf);
984 static inline void tcp_openreq_init(struct request_sock *req,
985 struct tcp_options_received *rx_opt,
988 struct inet_request_sock *ireq = inet_rsk(req);
990 req->rcv_wnd = 0; /* So that tcp_send_synack() knows! */
992 tcp_rsk(req)->rcv_isn = TCP_SKB_CB(skb)->seq;
993 req->mss = rx_opt->mss_clamp;
994 req->ts_recent = rx_opt->saw_tstamp ? rx_opt->rcv_tsval : 0;
995 ireq->tstamp_ok = rx_opt->tstamp_ok;
996 ireq->sack_ok = rx_opt->sack_ok;
997 ireq->snd_wscale = rx_opt->snd_wscale;
998 ireq->wscale_ok = rx_opt->wscale_ok;
1001 ireq->rmt_port = tcp_hdr(skb)->source;
1002 ireq->loc_port = tcp_hdr(skb)->dest;
1005 extern void tcp_enter_memory_pressure(struct sock *sk);
1007 static inline int keepalive_intvl_when(const struct tcp_sock *tp)
1009 return tp->keepalive_intvl ? : sysctl_tcp_keepalive_intvl;
1012 static inline int keepalive_time_when(const struct tcp_sock *tp)
1014 return tp->keepalive_time ? : sysctl_tcp_keepalive_time;
1017 static inline int keepalive_probes(const struct tcp_sock *tp)
1019 return tp->keepalive_probes ? : sysctl_tcp_keepalive_probes;
1022 static inline u32 keepalive_time_elapsed(const struct tcp_sock *tp)
1024 const struct inet_connection_sock *icsk = &tp->inet_conn;
1026 return min_t(u32, tcp_time_stamp - icsk->icsk_ack.lrcvtime,
1027 tcp_time_stamp - tp->rcv_tstamp);
1030 static inline int tcp_fin_time(const struct sock *sk)
1032 int fin_timeout = tcp_sk(sk)->linger2 ? : sysctl_tcp_fin_timeout;
1033 const int rto = inet_csk(sk)->icsk_rto;
1035 if (fin_timeout < (rto << 2) - (rto >> 1))
1036 fin_timeout = (rto << 2) - (rto >> 1);
1041 static inline int tcp_paws_check(const struct tcp_options_received *rx_opt,
1044 if ((s32)(rx_opt->ts_recent - rx_opt->rcv_tsval) <= paws_win)
1046 if (unlikely(get_seconds() >= rx_opt->ts_recent_stamp + TCP_PAWS_24DAYS))
1049 * Some OSes send SYN and SYNACK messages with tsval=0 tsecr=0,
1050 * then following tcp messages have valid values. Ignore 0 value,
1051 * or else 'negative' tsval might forbid us to accept their packets.
1053 if (!rx_opt->ts_recent)
1058 static inline int tcp_paws_reject(const struct tcp_options_received *rx_opt,
1061 if (tcp_paws_check(rx_opt, 0))
1064 /* RST segments are not recommended to carry timestamp,
1065 and, if they do, it is recommended to ignore PAWS because
1066 "their cleanup function should take precedence over timestamps."
1067 Certainly, it is mistake. It is necessary to understand the reasons
1068 of this constraint to relax it: if peer reboots, clock may go
1069 out-of-sync and half-open connections will not be reset.
1070 Actually, the problem would be not existing if all
1071 the implementations followed draft about maintaining clock
1072 via reboots. Linux-2.2 DOES NOT!
1074 However, we can relax time bounds for RST segments to MSL.
1076 if (rst && get_seconds() >= rx_opt->ts_recent_stamp + TCP_PAWS_MSL)
1081 static inline void tcp_mib_init(struct net *net)
1084 TCP_ADD_STATS_USER(net, TCP_MIB_RTOALGORITHM, 1);
1085 TCP_ADD_STATS_USER(net, TCP_MIB_RTOMIN, TCP_RTO_MIN*1000/HZ);
1086 TCP_ADD_STATS_USER(net, TCP_MIB_RTOMAX, TCP_RTO_MAX*1000/HZ);
1087 TCP_ADD_STATS_USER(net, TCP_MIB_MAXCONN, -1);
1091 static inline void tcp_clear_retrans_hints_partial(struct tcp_sock *tp)
1093 tp->lost_skb_hint = NULL;
1094 tp->scoreboard_skb_hint = NULL;
1097 static inline void tcp_clear_all_retrans_hints(struct tcp_sock *tp)
1099 tcp_clear_retrans_hints_partial(tp);
1100 tp->retransmit_skb_hint = NULL;
1106 /* - key database */
1107 struct tcp_md5sig_key {
1112 struct tcp4_md5sig_key {
1113 struct tcp_md5sig_key base;
1117 struct tcp6_md5sig_key {
1118 struct tcp_md5sig_key base;
1120 u32 scope_id; /* XXX */
1122 struct in6_addr addr;
1126 struct tcp_md5sig_info {
1127 struct tcp4_md5sig_key *keys4;
1128 #if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
1129 struct tcp6_md5sig_key *keys6;
1137 /* - pseudo header */
1138 struct tcp4_pseudohdr {
1146 struct tcp6_pseudohdr {
1147 struct in6_addr saddr;
1148 struct in6_addr daddr;
1150 __be32 protocol; /* including padding */
1153 union tcp_md5sum_block {
1154 struct tcp4_pseudohdr ip4;
1155 #if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
1156 struct tcp6_pseudohdr ip6;
1160 /* - pool: digest algorithm, hash description and scratch buffer */
1161 struct tcp_md5sig_pool {
1162 struct hash_desc md5_desc;
1163 union tcp_md5sum_block md5_blk;
1167 extern int tcp_v4_md5_hash_skb(char *md5_hash, struct tcp_md5sig_key *key,
1168 struct sock *sk, struct request_sock *req,
1169 struct sk_buff *skb);
1170 extern struct tcp_md5sig_key * tcp_v4_md5_lookup(struct sock *sk,
1171 struct sock *addr_sk);
1172 extern int tcp_v4_md5_do_add(struct sock *sk, __be32 addr, u8 *newkey,
1174 extern int tcp_v4_md5_do_del(struct sock *sk, __be32 addr);
1176 #ifdef CONFIG_TCP_MD5SIG
1177 #define tcp_twsk_md5_key(twsk) ((twsk)->tw_md5_keylen ? \
1178 &(struct tcp_md5sig_key) { \
1179 .key = (twsk)->tw_md5_key, \
1180 .keylen = (twsk)->tw_md5_keylen, \
1183 #define tcp_twsk_md5_key(twsk) NULL
1186 extern struct tcp_md5sig_pool * __percpu *tcp_alloc_md5sig_pool(struct sock *);
1187 extern void tcp_free_md5sig_pool(void);
1189 extern struct tcp_md5sig_pool *tcp_get_md5sig_pool(void);
1190 extern void tcp_put_md5sig_pool(void);
1192 extern int tcp_md5_hash_header(struct tcp_md5sig_pool *, struct tcphdr *);
1193 extern int tcp_md5_hash_skb_data(struct tcp_md5sig_pool *, struct sk_buff *,
1194 unsigned header_len);
1195 extern int tcp_md5_hash_key(struct tcp_md5sig_pool *hp,
1196 struct tcp_md5sig_key *key);
1198 /* write queue abstraction */
1199 static inline void tcp_write_queue_purge(struct sock *sk)
1201 struct sk_buff *skb;
1203 while ((skb = __skb_dequeue(&sk->sk_write_queue)) != NULL)
1204 sk_wmem_free_skb(sk, skb);
1206 tcp_clear_all_retrans_hints(tcp_sk(sk));
1209 static inline struct sk_buff *tcp_write_queue_head(struct sock *sk)
1211 return skb_peek(&sk->sk_write_queue);
1214 static inline struct sk_buff *tcp_write_queue_tail(struct sock *sk)
1216 return skb_peek_tail(&sk->sk_write_queue);
1219 static inline struct sk_buff *tcp_write_queue_next(struct sock *sk, struct sk_buff *skb)
1221 return skb_queue_next(&sk->sk_write_queue, skb);
1224 static inline struct sk_buff *tcp_write_queue_prev(struct sock *sk, struct sk_buff *skb)
1226 return skb_queue_prev(&sk->sk_write_queue, skb);
1229 #define tcp_for_write_queue(skb, sk) \
1230 skb_queue_walk(&(sk)->sk_write_queue, skb)
1232 #define tcp_for_write_queue_from(skb, sk) \
1233 skb_queue_walk_from(&(sk)->sk_write_queue, skb)
1235 #define tcp_for_write_queue_from_safe(skb, tmp, sk) \
1236 skb_queue_walk_from_safe(&(sk)->sk_write_queue, skb, tmp)
1238 static inline struct sk_buff *tcp_send_head(struct sock *sk)
1240 return sk->sk_send_head;
1243 static inline bool tcp_skb_is_last(const struct sock *sk,
1244 const struct sk_buff *skb)
1246 return skb_queue_is_last(&sk->sk_write_queue, skb);
1249 static inline void tcp_advance_send_head(struct sock *sk, struct sk_buff *skb)
1251 if (tcp_skb_is_last(sk, skb))
1252 sk->sk_send_head = NULL;
1254 sk->sk_send_head = tcp_write_queue_next(sk, skb);
1257 static inline void tcp_check_send_head(struct sock *sk, struct sk_buff *skb_unlinked)
1259 if (sk->sk_send_head == skb_unlinked)
1260 sk->sk_send_head = NULL;
1263 static inline void tcp_init_send_head(struct sock *sk)
1265 sk->sk_send_head = NULL;
1268 static inline void __tcp_add_write_queue_tail(struct sock *sk, struct sk_buff *skb)
1270 __skb_queue_tail(&sk->sk_write_queue, skb);
1273 static inline void tcp_add_write_queue_tail(struct sock *sk, struct sk_buff *skb)
1275 __tcp_add_write_queue_tail(sk, skb);
1277 /* Queue it, remembering where we must start sending. */
1278 if (sk->sk_send_head == NULL) {
1279 sk->sk_send_head = skb;
1281 if (tcp_sk(sk)->highest_sack == NULL)
1282 tcp_sk(sk)->highest_sack = skb;
1286 static inline void __tcp_add_write_queue_head(struct sock *sk, struct sk_buff *skb)
1288 __skb_queue_head(&sk->sk_write_queue, skb);
1291 /* Insert buff after skb on the write queue of sk. */
1292 static inline void tcp_insert_write_queue_after(struct sk_buff *skb,
1293 struct sk_buff *buff,
1296 __skb_queue_after(&sk->sk_write_queue, skb, buff);
1299 /* Insert new before skb on the write queue of sk. */
1300 static inline void tcp_insert_write_queue_before(struct sk_buff *new,
1301 struct sk_buff *skb,
1304 __skb_queue_before(&sk->sk_write_queue, skb, new);
1306 if (sk->sk_send_head == skb)
1307 sk->sk_send_head = new;
1310 static inline void tcp_unlink_write_queue(struct sk_buff *skb, struct sock *sk)
1312 __skb_unlink(skb, &sk->sk_write_queue);
1315 static inline int tcp_write_queue_empty(struct sock *sk)
1317 return skb_queue_empty(&sk->sk_write_queue);
1320 static inline void tcp_push_pending_frames(struct sock *sk)
1322 if (tcp_send_head(sk)) {
1323 struct tcp_sock *tp = tcp_sk(sk);
1325 __tcp_push_pending_frames(sk, tcp_current_mss(sk), tp->nonagle);
1329 /* Start sequence of the highest skb with SACKed bit, valid only if
1330 * sacked > 0 or when the caller has ensured validity by itself.
1332 static inline u32 tcp_highest_sack_seq(struct tcp_sock *tp)
1334 if (!tp->sacked_out)
1337 if (tp->highest_sack == NULL)
1340 return TCP_SKB_CB(tp->highest_sack)->seq;
1343 static inline void tcp_advance_highest_sack(struct sock *sk, struct sk_buff *skb)
1345 tcp_sk(sk)->highest_sack = tcp_skb_is_last(sk, skb) ? NULL :
1346 tcp_write_queue_next(sk, skb);
1349 static inline struct sk_buff *tcp_highest_sack(struct sock *sk)
1351 return tcp_sk(sk)->highest_sack;
1354 static inline void tcp_highest_sack_reset(struct sock *sk)
1356 tcp_sk(sk)->highest_sack = tcp_write_queue_head(sk);
1359 /* Called when old skb is about to be deleted (to be combined with new skb) */
1360 static inline void tcp_highest_sack_combine(struct sock *sk,
1361 struct sk_buff *old,
1362 struct sk_buff *new)
1364 if (tcp_sk(sk)->sacked_out && (old == tcp_sk(sk)->highest_sack))
1365 tcp_sk(sk)->highest_sack = new;
1368 /* Determines whether this is a thin stream (which may suffer from
1369 * increased latency). Used to trigger latency-reducing mechanisms.
1371 static inline unsigned int tcp_stream_is_thin(struct tcp_sock *tp)
1373 return tp->packets_out < 4 && !tcp_in_initial_slowstart(tp);
1377 enum tcp_seq_states {
1378 TCP_SEQ_STATE_LISTENING,
1379 TCP_SEQ_STATE_OPENREQ,
1380 TCP_SEQ_STATE_ESTABLISHED,
1381 TCP_SEQ_STATE_TIME_WAIT,
1384 struct tcp_seq_afinfo {
1387 struct file_operations seq_fops;
1388 struct seq_operations seq_ops;
1391 struct tcp_iter_state {
1392 struct seq_net_private p;
1394 enum tcp_seq_states state;
1395 struct sock *syn_wait_sk;
1396 int bucket, offset, sbucket, num, uid;
1400 extern int tcp_proc_register(struct net *net, struct tcp_seq_afinfo *afinfo);
1401 extern void tcp_proc_unregister(struct net *net, struct tcp_seq_afinfo *afinfo);
1403 extern struct request_sock_ops tcp_request_sock_ops;
1404 extern struct request_sock_ops tcp6_request_sock_ops;
1406 extern void tcp_v4_destroy_sock(struct sock *sk);
1408 extern int tcp_v4_gso_send_check(struct sk_buff *skb);
1409 extern struct sk_buff *tcp_tso_segment(struct sk_buff *skb, u32 features);
1410 extern struct sk_buff **tcp_gro_receive(struct sk_buff **head,
1411 struct sk_buff *skb);
1412 extern struct sk_buff **tcp4_gro_receive(struct sk_buff **head,
1413 struct sk_buff *skb);
1414 extern int tcp_gro_complete(struct sk_buff *skb);
1415 extern int tcp4_gro_complete(struct sk_buff *skb);
1417 #ifdef CONFIG_PROC_FS
1418 extern int tcp4_proc_init(void);
1419 extern void tcp4_proc_exit(void);
1422 /* TCP af-specific functions */
1423 struct tcp_sock_af_ops {
1424 #ifdef CONFIG_TCP_MD5SIG
1425 struct tcp_md5sig_key *(*md5_lookup) (struct sock *sk,
1426 struct sock *addr_sk);
1427 int (*calc_md5_hash) (char *location,
1428 struct tcp_md5sig_key *md5,
1430 struct request_sock *req,
1431 struct sk_buff *skb);
1432 int (*md5_add) (struct sock *sk,
1433 struct sock *addr_sk,
1436 int (*md5_parse) (struct sock *sk,
1437 char __user *optval,
1442 struct tcp_request_sock_ops {
1443 #ifdef CONFIG_TCP_MD5SIG
1444 struct tcp_md5sig_key *(*md5_lookup) (struct sock *sk,
1445 struct request_sock *req);
1446 int (*calc_md5_hash) (char *location,
1447 struct tcp_md5sig_key *md5,
1449 struct request_sock *req,
1450 struct sk_buff *skb);
1454 /* Using SHA1 for now, define some constants.
1456 #define COOKIE_DIGEST_WORDS (SHA_DIGEST_WORDS)
1457 #define COOKIE_MESSAGE_WORDS (SHA_MESSAGE_BYTES / 4)
1458 #define COOKIE_WORKSPACE_WORDS (COOKIE_DIGEST_WORDS + COOKIE_MESSAGE_WORDS)
1460 extern int tcp_cookie_generator(u32 *bakery);
1463 * struct tcp_cookie_values - each socket needs extra space for the
1464 * cookies, together with (optional) space for any SYN data.
1466 * A tcp_sock contains a pointer to the current value, and this is
1467 * cloned to the tcp_timewait_sock.
1469 * @cookie_pair: variable data from the option exchange.
1471 * @cookie_desired: user specified tcpct_cookie_desired. Zero
1472 * indicates default (sysctl_tcp_cookie_size).
1473 * After cookie sent, remembers size of cookie.
1474 * Range 0, TCP_COOKIE_MIN to TCP_COOKIE_MAX.
1476 * @s_data_desired: user specified tcpct_s_data_desired. When the
1477 * constant payload is specified (@s_data_constant),
1478 * holds its length instead.
1479 * Range 0 to TCP_MSS_DESIRED.
1481 * @s_data_payload: constant data that is to be included in the
1482 * payload of SYN or SYNACK segments when the
1483 * cookie option is present.
1485 struct tcp_cookie_values {
1487 u8 cookie_pair[TCP_COOKIE_PAIR_SIZE];
1488 u8 cookie_pair_size;
1490 u16 s_data_desired:11,
1495 u8 s_data_payload[0];
1498 static inline void tcp_cookie_values_release(struct kref *kref)
1500 kfree(container_of(kref, struct tcp_cookie_values, kref));
1503 /* The length of constant payload data. Note that s_data_desired is
1504 * overloaded, depending on s_data_constant: either the length of constant
1505 * data (returned here) or the limit on variable data.
1507 static inline int tcp_s_data_size(const struct tcp_sock *tp)
1509 return (tp->cookie_values != NULL && tp->cookie_values->s_data_constant)
1510 ? tp->cookie_values->s_data_desired
1515 * struct tcp_extend_values - tcp_ipv?.c to tcp_output.c workspace.
1517 * As tcp_request_sock has already been extended in other places, the
1518 * only remaining method is to pass stack values along as function
1519 * parameters. These parameters are not needed after sending SYNACK.
1521 * @cookie_bakery: cryptographic secret and message workspace.
1523 * @cookie_plus: bytes in authenticator/cookie option, copied from
1524 * struct tcp_options_received (above).
1526 struct tcp_extend_values {
1527 struct request_values rv;
1528 u32 cookie_bakery[COOKIE_WORKSPACE_WORDS];
1534 static inline struct tcp_extend_values *tcp_xv(struct request_values *rvp)
1536 return (struct tcp_extend_values *)rvp;
1539 extern void tcp_v4_init(void);
1540 extern void tcp_init(void);