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 /* Minimal accepted MSS. It is (60+60+8) - (20+20). */
64 #define TCP_MIN_MSS 88U
66 /* The least MTU to use for probing */
67 #define TCP_BASE_MSS 512
69 /* After receiving this amount of duplicate ACKs fast retransmit starts. */
70 #define TCP_FASTRETRANS_THRESH 3
72 /* Maximal reordering. */
73 #define TCP_MAX_REORDERING 127
75 /* Maximal number of ACKs sent quickly to accelerate slow-start. */
76 #define TCP_MAX_QUICKACKS 16U
79 #define TCP_URG_VALID 0x0100
80 #define TCP_URG_NOTYET 0x0200
81 #define TCP_URG_READ 0x0400
83 #define TCP_RETR1 3 /*
84 * This is how many retries it does before it
85 * tries to figure out if the gateway is
86 * down. Minimal RFC value is 3; it corresponds
87 * to ~3sec-8min depending on RTO.
90 #define TCP_RETR2 15 /*
91 * This should take at least
92 * 90 minutes to time out.
93 * RFC1122 says that the limit is 100 sec.
94 * 15 is ~13-30min depending on RTO.
97 #define TCP_SYN_RETRIES 5 /* number of times to retry active opening a
98 * connection: ~180sec is RFC minimum */
100 #define TCP_SYNACK_RETRIES 5 /* number of times to retry passive opening a
101 * connection: ~180sec is RFC minimum */
104 #define TCP_ORPHAN_RETRIES 7 /* number of times to retry on an orphaned
105 * socket. 7 is ~50sec-16min.
109 #define TCP_TIMEWAIT_LEN (60*HZ) /* how long to wait to destroy TIME-WAIT
110 * state, about 60 seconds */
111 #define TCP_FIN_TIMEOUT TCP_TIMEWAIT_LEN
112 /* BSD style FIN_WAIT2 deadlock breaker.
113 * It used to be 3min, new value is 60sec,
114 * to combine FIN-WAIT-2 timeout with
118 #define TCP_DELACK_MAX ((unsigned)(HZ/5)) /* maximal time to delay before sending an ACK */
120 #define TCP_DELACK_MIN ((unsigned)(HZ/25)) /* minimal time to delay before sending an ACK */
121 #define TCP_ATO_MIN ((unsigned)(HZ/25))
123 #define TCP_DELACK_MIN 4U
124 #define TCP_ATO_MIN 4U
126 #define TCP_RTO_MAX ((unsigned)(120*HZ))
127 #define TCP_RTO_MIN ((unsigned)(HZ/5))
128 #define TCP_TIMEOUT_INIT ((unsigned)(3*HZ)) /* RFC 1122 initial RTO value */
130 #define TCP_RESOURCE_PROBE_INTERVAL ((unsigned)(HZ/2U)) /* Maximal interval between probes
131 * for local resources.
134 #define TCP_KEEPALIVE_TIME (120*60*HZ) /* two hours */
135 #define TCP_KEEPALIVE_PROBES 9 /* Max of 9 keepalive probes */
136 #define TCP_KEEPALIVE_INTVL (75*HZ)
138 #define MAX_TCP_KEEPIDLE 32767
139 #define MAX_TCP_KEEPINTVL 32767
140 #define MAX_TCP_KEEPCNT 127
141 #define MAX_TCP_SYNCNT 127
143 #define TCP_SYNQ_INTERVAL (HZ/5) /* Period of SYNACK timer */
145 #define TCP_PAWS_24DAYS (60 * 60 * 24 * 24)
146 #define TCP_PAWS_MSL 60 /* Per-host timestamps are invalidated
147 * after this time. It should be equal
148 * (or greater than) TCP_TIMEWAIT_LEN
149 * to provide reliability equal to one
150 * provided by timewait state.
152 #define TCP_PAWS_WINDOW 1 /* Replay window for per-host
153 * timestamps. It must be less than
154 * minimal timewait lifetime.
160 #define TCPOPT_NOP 1 /* Padding */
161 #define TCPOPT_EOL 0 /* End of options */
162 #define TCPOPT_MSS 2 /* Segment size negotiating */
163 #define TCPOPT_WINDOW 3 /* Window scaling */
164 #define TCPOPT_SACK_PERM 4 /* SACK Permitted */
165 #define TCPOPT_SACK 5 /* SACK Block */
166 #define TCPOPT_TIMESTAMP 8 /* Better RTT estimations/PAWS */
167 #define TCPOPT_MD5SIG 19 /* MD5 Signature (RFC2385) */
168 #define TCPOPT_COOKIE 253 /* Cookie extension (experimental) */
174 #define TCPOLEN_MSS 4
175 #define TCPOLEN_WINDOW 3
176 #define TCPOLEN_SACK_PERM 2
177 #define TCPOLEN_TIMESTAMP 10
178 #define TCPOLEN_MD5SIG 18
179 #define TCPOLEN_COOKIE_BASE 2 /* Cookie-less header extension */
180 #define TCPOLEN_COOKIE_PAIR 3 /* Cookie pair header extension */
181 #define TCPOLEN_COOKIE_MIN (TCPOLEN_COOKIE_BASE+TCP_COOKIE_MIN)
182 #define TCPOLEN_COOKIE_MAX (TCPOLEN_COOKIE_BASE+TCP_COOKIE_MAX)
184 /* But this is what stacks really send out. */
185 #define TCPOLEN_TSTAMP_ALIGNED 12
186 #define TCPOLEN_WSCALE_ALIGNED 4
187 #define TCPOLEN_SACKPERM_ALIGNED 4
188 #define TCPOLEN_SACK_BASE 2
189 #define TCPOLEN_SACK_BASE_ALIGNED 4
190 #define TCPOLEN_SACK_PERBLOCK 8
191 #define TCPOLEN_MD5SIG_ALIGNED 20
192 #define TCPOLEN_MSS_ALIGNED 4
194 /* Flags in tp->nonagle */
195 #define TCP_NAGLE_OFF 1 /* Nagle's algo is disabled */
196 #define TCP_NAGLE_CORK 2 /* Socket is corked */
197 #define TCP_NAGLE_PUSH 4 /* Cork is overridden for already queued data */
199 /* TCP thin-stream limits */
200 #define TCP_THIN_LINEAR_RETRIES 6 /* After 6 linear retries, do exp. backoff */
202 extern struct inet_timewait_death_row tcp_death_row;
204 /* sysctl variables for tcp */
205 extern int sysctl_tcp_timestamps;
206 extern int sysctl_tcp_window_scaling;
207 extern int sysctl_tcp_sack;
208 extern int sysctl_tcp_fin_timeout;
209 extern int sysctl_tcp_keepalive_time;
210 extern int sysctl_tcp_keepalive_probes;
211 extern int sysctl_tcp_keepalive_intvl;
212 extern int sysctl_tcp_syn_retries;
213 extern int sysctl_tcp_synack_retries;
214 extern int sysctl_tcp_retries1;
215 extern int sysctl_tcp_retries2;
216 extern int sysctl_tcp_orphan_retries;
217 extern int sysctl_tcp_syncookies;
218 extern int sysctl_tcp_retrans_collapse;
219 extern int sysctl_tcp_stdurg;
220 extern int sysctl_tcp_rfc1337;
221 extern int sysctl_tcp_abort_on_overflow;
222 extern int sysctl_tcp_max_orphans;
223 extern int sysctl_tcp_fack;
224 extern int sysctl_tcp_reordering;
225 extern int sysctl_tcp_ecn;
226 extern int sysctl_tcp_dsack;
227 extern int sysctl_tcp_mem[3];
228 extern int sysctl_tcp_wmem[3];
229 extern int sysctl_tcp_rmem[3];
230 extern int sysctl_tcp_app_win;
231 extern int sysctl_tcp_adv_win_scale;
232 extern int sysctl_tcp_tw_reuse;
233 extern int sysctl_tcp_frto;
234 extern int sysctl_tcp_frto_response;
235 extern int sysctl_tcp_low_latency;
236 extern int sysctl_tcp_dma_copybreak;
237 extern int sysctl_tcp_nometrics_save;
238 extern int sysctl_tcp_moderate_rcvbuf;
239 extern int sysctl_tcp_tso_win_divisor;
240 extern int sysctl_tcp_abc;
241 extern int sysctl_tcp_mtu_probing;
242 extern int sysctl_tcp_base_mss;
243 extern int sysctl_tcp_workaround_signed_windows;
244 extern int sysctl_tcp_slow_start_after_idle;
245 extern int sysctl_tcp_max_ssthresh;
246 extern int sysctl_tcp_cookie_size;
247 extern int sysctl_tcp_thin_linear_timeouts;
248 extern int sysctl_tcp_thin_dupack;
250 extern atomic_t tcp_memory_allocated;
251 extern struct percpu_counter tcp_sockets_allocated;
252 extern int tcp_memory_pressure;
255 * The next routines deal with comparing 32 bit unsigned ints
256 * and worry about wraparound (automatic with unsigned arithmetic).
259 static inline int before(__u32 seq1, __u32 seq2)
261 return (__s32)(seq1-seq2) < 0;
263 #define after(seq2, seq1) before(seq1, seq2)
265 /* is s2<=s1<=s3 ? */
266 static inline int between(__u32 seq1, __u32 seq2, __u32 seq3)
268 return seq3 - seq2 >= seq1 - seq2;
271 static inline int tcp_too_many_orphans(struct sock *sk, int num)
273 return (num > sysctl_tcp_max_orphans) ||
274 (sk->sk_wmem_queued > SOCK_MIN_SNDBUF &&
275 atomic_read(&tcp_memory_allocated) > sysctl_tcp_mem[2]);
278 /* syncookies: remember time of last synqueue overflow */
279 static inline void tcp_synq_overflow(struct sock *sk)
281 tcp_sk(sk)->rx_opt.ts_recent_stamp = jiffies;
284 /* syncookies: no recent synqueue overflow on this listening socket? */
285 static inline int tcp_synq_no_recent_overflow(const struct sock *sk)
287 unsigned long last_overflow = tcp_sk(sk)->rx_opt.ts_recent_stamp;
288 return time_after(jiffies, last_overflow + TCP_TIMEOUT_INIT);
291 extern struct proto tcp_prot;
293 #define TCP_INC_STATS(net, field) SNMP_INC_STATS((net)->mib.tcp_statistics, field)
294 #define TCP_INC_STATS_BH(net, field) SNMP_INC_STATS_BH((net)->mib.tcp_statistics, field)
295 #define TCP_DEC_STATS(net, field) SNMP_DEC_STATS((net)->mib.tcp_statistics, field)
296 #define TCP_ADD_STATS_USER(net, field, val) SNMP_ADD_STATS_USER((net)->mib.tcp_statistics, field, val)
297 #define TCP_ADD_STATS(net, field, val) SNMP_ADD_STATS((net)->mib.tcp_statistics, field, val)
299 extern void tcp_v4_err(struct sk_buff *skb, u32);
301 extern void tcp_shutdown (struct sock *sk, int how);
303 extern int tcp_v4_rcv(struct sk_buff *skb);
305 extern int tcp_v4_remember_stamp(struct sock *sk);
306 extern int tcp_v4_tw_remember_stamp(struct inet_timewait_sock *tw);
307 extern int tcp_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
309 extern int tcp_sendpage(struct sock *sk, struct page *page, int offset,
310 size_t size, int flags);
311 extern int tcp_ioctl(struct sock *sk, int cmd, unsigned long arg);
312 extern int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb,
313 struct tcphdr *th, unsigned len);
314 extern int tcp_rcv_established(struct sock *sk, struct sk_buff *skb,
315 struct tcphdr *th, unsigned len);
316 extern void tcp_rcv_space_adjust(struct sock *sk);
317 extern void tcp_cleanup_rbuf(struct sock *sk, int copied);
318 extern int tcp_twsk_unique(struct sock *sk, struct sock *sktw, void *twp);
319 extern void tcp_twsk_destructor(struct sock *sk);
320 extern ssize_t tcp_splice_read(struct socket *sk, loff_t *ppos,
321 struct pipe_inode_info *pipe, size_t len,
324 static inline void tcp_dec_quickack_mode(struct sock *sk,
325 const unsigned int pkts)
327 struct inet_connection_sock *icsk = inet_csk(sk);
329 if (icsk->icsk_ack.quick) {
330 if (pkts >= icsk->icsk_ack.quick) {
331 icsk->icsk_ack.quick = 0;
332 /* Leaving quickack mode we deflate ATO. */
333 icsk->icsk_ack.ato = TCP_ATO_MIN;
335 icsk->icsk_ack.quick -= pkts;
339 extern void tcp_enter_quickack_mode(struct sock *sk);
342 #define TCP_ECN_QUEUE_CWR 2
343 #define TCP_ECN_DEMAND_CWR 4
345 static __inline__ void
346 TCP_ECN_create_request(struct request_sock *req, struct tcphdr *th)
348 if (sysctl_tcp_ecn && th->ece && th->cwr)
349 inet_rsk(req)->ecn_ok = 1;
360 extern enum tcp_tw_status tcp_timewait_state_process(struct inet_timewait_sock *tw,
362 const struct tcphdr *th);
363 extern struct sock * tcp_check_req(struct sock *sk,struct sk_buff *skb,
364 struct request_sock *req,
365 struct request_sock **prev);
366 extern int tcp_child_process(struct sock *parent, struct sock *child,
367 struct sk_buff *skb);
368 extern int tcp_use_frto(struct sock *sk);
369 extern void tcp_enter_frto(struct sock *sk);
370 extern void tcp_enter_loss(struct sock *sk, int how);
371 extern void tcp_clear_retrans(struct tcp_sock *tp);
372 extern void tcp_update_metrics(struct sock *sk);
373 extern void tcp_close(struct sock *sk, long timeout);
374 extern unsigned int tcp_poll(struct file * file, struct socket *sock,
375 struct poll_table_struct *wait);
376 extern int tcp_getsockopt(struct sock *sk, int level, int optname,
377 char __user *optval, int __user *optlen);
378 extern int tcp_setsockopt(struct sock *sk, int level, int optname,
379 char __user *optval, unsigned int optlen);
380 extern int compat_tcp_getsockopt(struct sock *sk, int level, int optname,
381 char __user *optval, int __user *optlen);
382 extern int compat_tcp_setsockopt(struct sock *sk, int level, int optname,
383 char __user *optval, unsigned int optlen);
384 extern void tcp_set_keepalive(struct sock *sk, int val);
385 extern void tcp_syn_ack_timeout(struct sock *sk, struct request_sock *req);
386 extern int tcp_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
387 size_t len, int nonblock, int flags, int *addr_len);
388 extern void tcp_parse_options(struct sk_buff *skb,
389 struct tcp_options_received *opt_rx, u8 **hvpp,
391 extern u8 *tcp_parse_md5sig_option(struct tcphdr *th);
394 * TCP v4 functions exported for the inet6 API
397 extern void tcp_v4_send_check(struct sock *sk, struct sk_buff *skb);
398 extern int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb);
399 extern struct sock * tcp_create_openreq_child(struct sock *sk,
400 struct request_sock *req,
401 struct sk_buff *skb);
402 extern struct sock * tcp_v4_syn_recv_sock(struct sock *sk, struct sk_buff *skb,
403 struct request_sock *req,
404 struct dst_entry *dst);
405 extern int tcp_v4_do_rcv(struct sock *sk, struct sk_buff *skb);
406 extern int tcp_v4_connect(struct sock *sk, struct sockaddr *uaddr,
408 extern int tcp_connect(struct sock *sk);
409 extern struct sk_buff * tcp_make_synack(struct sock *sk, struct dst_entry *dst,
410 struct request_sock *req,
411 struct request_values *rvp);
412 extern int tcp_disconnect(struct sock *sk, int flags);
415 /* From syncookies.c */
416 extern __u32 syncookie_secret[2][16-4+SHA_DIGEST_WORDS];
417 extern struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb,
418 struct ip_options *opt);
419 extern __u32 cookie_v4_init_sequence(struct sock *sk, struct sk_buff *skb,
422 extern __u32 cookie_init_timestamp(struct request_sock *req);
423 extern bool cookie_check_timestamp(struct tcp_options_received *opt, bool *);
425 /* From net/ipv6/syncookies.c */
426 extern struct sock *cookie_v6_check(struct sock *sk, struct sk_buff *skb);
427 extern __u32 cookie_v6_init_sequence(struct sock *sk, struct sk_buff *skb,
432 extern void __tcp_push_pending_frames(struct sock *sk, unsigned int cur_mss,
434 extern int tcp_may_send_now(struct sock *sk);
435 extern int tcp_retransmit_skb(struct sock *, struct sk_buff *);
436 extern void tcp_retransmit_timer(struct sock *sk);
437 extern void tcp_xmit_retransmit_queue(struct sock *);
438 extern void tcp_simple_retransmit(struct sock *);
439 extern int tcp_trim_head(struct sock *, struct sk_buff *, u32);
440 extern int tcp_fragment(struct sock *, struct sk_buff *, u32, unsigned int);
442 extern void tcp_send_probe0(struct sock *);
443 extern void tcp_send_partial(struct sock *);
444 extern int tcp_write_wakeup(struct sock *);
445 extern void tcp_send_fin(struct sock *sk);
446 extern void tcp_send_active_reset(struct sock *sk, gfp_t priority);
447 extern int tcp_send_synack(struct sock *);
448 extern void tcp_push_one(struct sock *, unsigned int mss_now);
449 extern void tcp_send_ack(struct sock *sk);
450 extern void tcp_send_delayed_ack(struct sock *sk);
453 extern void tcp_cwnd_application_limited(struct sock *sk);
456 extern void tcp_init_xmit_timers(struct sock *);
457 static inline void tcp_clear_xmit_timers(struct sock *sk)
459 inet_csk_clear_xmit_timers(sk);
462 extern unsigned int tcp_sync_mss(struct sock *sk, u32 pmtu);
463 extern unsigned int tcp_current_mss(struct sock *sk);
465 /* Bound MSS / TSO packet size with the half of the window */
466 static inline int tcp_bound_to_half_wnd(struct tcp_sock *tp, int pktsize)
468 if (tp->max_window && pktsize > (tp->max_window >> 1))
469 return max(tp->max_window >> 1, 68U - tp->tcp_header_len);
475 extern void tcp_get_info(struct sock *, struct tcp_info *);
477 /* Read 'sendfile()'-style from a TCP socket */
478 typedef int (*sk_read_actor_t)(read_descriptor_t *, struct sk_buff *,
479 unsigned int, size_t);
480 extern int tcp_read_sock(struct sock *sk, read_descriptor_t *desc,
481 sk_read_actor_t recv_actor);
483 extern void tcp_initialize_rcv_mss(struct sock *sk);
485 extern int tcp_mtu_to_mss(struct sock *sk, int pmtu);
486 extern int tcp_mss_to_mtu(struct sock *sk, int mss);
487 extern void tcp_mtup_init(struct sock *sk);
489 static inline void tcp_bound_rto(const struct sock *sk)
491 if (inet_csk(sk)->icsk_rto > TCP_RTO_MAX)
492 inet_csk(sk)->icsk_rto = TCP_RTO_MAX;
495 static inline u32 __tcp_set_rto(const struct tcp_sock *tp)
497 return (tp->srtt >> 3) + tp->rttvar;
500 static inline void __tcp_fast_path_on(struct tcp_sock *tp, u32 snd_wnd)
502 tp->pred_flags = htonl((tp->tcp_header_len << 26) |
503 ntohl(TCP_FLAG_ACK) |
507 static inline void tcp_fast_path_on(struct tcp_sock *tp)
509 __tcp_fast_path_on(tp, tp->snd_wnd >> tp->rx_opt.snd_wscale);
512 static inline void tcp_fast_path_check(struct sock *sk)
514 struct tcp_sock *tp = tcp_sk(sk);
516 if (skb_queue_empty(&tp->out_of_order_queue) &&
518 atomic_read(&sk->sk_rmem_alloc) < sk->sk_rcvbuf &&
520 tcp_fast_path_on(tp);
523 /* Compute the actual rto_min value */
524 static inline u32 tcp_rto_min(struct sock *sk)
526 struct dst_entry *dst = __sk_dst_get(sk);
527 u32 rto_min = TCP_RTO_MIN;
529 if (dst && dst_metric_locked(dst, RTAX_RTO_MIN))
530 rto_min = dst_metric_rtt(dst, RTAX_RTO_MIN);
534 /* Compute the actual receive window we are currently advertising.
535 * Rcv_nxt can be after the window if our peer push more data
536 * than the offered window.
538 static inline u32 tcp_receive_window(const struct tcp_sock *tp)
540 s32 win = tp->rcv_wup + tp->rcv_wnd - tp->rcv_nxt;
547 /* Choose a new window, without checks for shrinking, and without
548 * scaling applied to the result. The caller does these things
549 * if necessary. This is a "raw" window selection.
551 extern u32 __tcp_select_window(struct sock *sk);
553 /* TCP timestamps are only 32-bits, this causes a slight
554 * complication on 64-bit systems since we store a snapshot
555 * of jiffies in the buffer control blocks below. We decided
556 * to use only the low 32-bits of jiffies and hide the ugly
557 * casts with the following macro.
559 #define tcp_time_stamp ((__u32)(jiffies))
561 #define tcp_flag_byte(th) (((u_int8_t *)th)[13])
563 #define TCPHDR_FIN 0x01
564 #define TCPHDR_SYN 0x02
565 #define TCPHDR_RST 0x04
566 #define TCPHDR_PSH 0x08
567 #define TCPHDR_ACK 0x10
568 #define TCPHDR_URG 0x20
569 #define TCPHDR_ECE 0x40
570 #define TCPHDR_CWR 0x80
572 /* This is what the send packet queuing engine uses to pass
573 * TCP per-packet control information to the transmission code.
574 * We also store the host-order sequence numbers in here too.
575 * This is 44 bytes if IPV6 is enabled.
576 * If this grows please adjust skbuff.h:skbuff->cb[xxx] size appropriately.
580 struct inet_skb_parm h4;
581 #if defined(CONFIG_IPV6) || defined (CONFIG_IPV6_MODULE)
582 struct inet6_skb_parm h6;
584 } header; /* For incoming frames */
585 __u32 seq; /* Starting sequence number */
586 __u32 end_seq; /* SEQ + FIN + SYN + datalen */
587 __u32 when; /* used to compute rtt's */
588 __u8 flags; /* TCP header flags. */
589 __u8 sacked; /* State flags for SACK/FACK. */
590 #define TCPCB_SACKED_ACKED 0x01 /* SKB ACK'd by a SACK block */
591 #define TCPCB_SACKED_RETRANS 0x02 /* SKB retransmitted */
592 #define TCPCB_LOST 0x04 /* SKB is lost */
593 #define TCPCB_TAGBITS 0x07 /* All tag bits */
595 #define TCPCB_EVER_RETRANS 0x80 /* Ever retransmitted frame */
596 #define TCPCB_RETRANS (TCPCB_SACKED_RETRANS|TCPCB_EVER_RETRANS)
598 __u32 ack_seq; /* Sequence number ACK'd */
601 #define TCP_SKB_CB(__skb) ((struct tcp_skb_cb *)&((__skb)->cb[0]))
603 /* Due to TSO, an SKB can be composed of multiple actual
604 * packets. To keep these tracked properly, we use this.
606 static inline int tcp_skb_pcount(const struct sk_buff *skb)
608 return skb_shinfo(skb)->gso_segs;
611 /* This is valid iff tcp_skb_pcount() > 1. */
612 static inline int tcp_skb_mss(const struct sk_buff *skb)
614 return skb_shinfo(skb)->gso_size;
617 /* Events passed to congestion control interface */
619 CA_EVENT_TX_START, /* first transmit when no packets in flight */
620 CA_EVENT_CWND_RESTART, /* congestion window restart */
621 CA_EVENT_COMPLETE_CWR, /* end of congestion recovery */
622 CA_EVENT_FRTO, /* fast recovery timeout */
623 CA_EVENT_LOSS, /* loss timeout */
624 CA_EVENT_FAST_ACK, /* in sequence ack */
625 CA_EVENT_SLOW_ACK, /* other ack */
629 * Interface for adding new TCP congestion control handlers
631 #define TCP_CA_NAME_MAX 16
632 #define TCP_CA_MAX 128
633 #define TCP_CA_BUF_MAX (TCP_CA_NAME_MAX*TCP_CA_MAX)
635 #define TCP_CONG_NON_RESTRICTED 0x1
636 #define TCP_CONG_RTT_STAMP 0x2
638 struct tcp_congestion_ops {
639 struct list_head list;
642 /* initialize private data (optional) */
643 void (*init)(struct sock *sk);
644 /* cleanup private data (optional) */
645 void (*release)(struct sock *sk);
647 /* return slow start threshold (required) */
648 u32 (*ssthresh)(struct sock *sk);
649 /* lower bound for congestion window (optional) */
650 u32 (*min_cwnd)(const struct sock *sk);
651 /* do new cwnd calculation (required) */
652 void (*cong_avoid)(struct sock *sk, u32 ack, u32 in_flight);
653 /* call before changing ca_state (optional) */
654 void (*set_state)(struct sock *sk, u8 new_state);
655 /* call when cwnd event occurs (optional) */
656 void (*cwnd_event)(struct sock *sk, enum tcp_ca_event ev);
657 /* new value of cwnd after loss (optional) */
658 u32 (*undo_cwnd)(struct sock *sk);
659 /* hook for packet ack accounting (optional) */
660 void (*pkts_acked)(struct sock *sk, u32 num_acked, s32 rtt_us);
661 /* get info for inet_diag (optional) */
662 void (*get_info)(struct sock *sk, u32 ext, struct sk_buff *skb);
664 char name[TCP_CA_NAME_MAX];
665 struct module *owner;
668 extern int tcp_register_congestion_control(struct tcp_congestion_ops *type);
669 extern void tcp_unregister_congestion_control(struct tcp_congestion_ops *type);
671 extern void tcp_init_congestion_control(struct sock *sk);
672 extern void tcp_cleanup_congestion_control(struct sock *sk);
673 extern int tcp_set_default_congestion_control(const char *name);
674 extern void tcp_get_default_congestion_control(char *name);
675 extern void tcp_get_available_congestion_control(char *buf, size_t len);
676 extern void tcp_get_allowed_congestion_control(char *buf, size_t len);
677 extern int tcp_set_allowed_congestion_control(char *allowed);
678 extern int tcp_set_congestion_control(struct sock *sk, const char *name);
679 extern void tcp_slow_start(struct tcp_sock *tp);
680 extern void tcp_cong_avoid_ai(struct tcp_sock *tp, u32 w);
682 extern struct tcp_congestion_ops tcp_init_congestion_ops;
683 extern u32 tcp_reno_ssthresh(struct sock *sk);
684 extern void tcp_reno_cong_avoid(struct sock *sk, u32 ack, u32 in_flight);
685 extern u32 tcp_reno_min_cwnd(const struct sock *sk);
686 extern struct tcp_congestion_ops tcp_reno;
688 static inline void tcp_set_ca_state(struct sock *sk, const u8 ca_state)
690 struct inet_connection_sock *icsk = inet_csk(sk);
692 if (icsk->icsk_ca_ops->set_state)
693 icsk->icsk_ca_ops->set_state(sk, ca_state);
694 icsk->icsk_ca_state = ca_state;
697 static inline void tcp_ca_event(struct sock *sk, const enum tcp_ca_event event)
699 const struct inet_connection_sock *icsk = inet_csk(sk);
701 if (icsk->icsk_ca_ops->cwnd_event)
702 icsk->icsk_ca_ops->cwnd_event(sk, event);
705 /* These functions determine how the current flow behaves in respect of SACK
706 * handling. SACK is negotiated with the peer, and therefore it can vary
707 * between different flows.
709 * tcp_is_sack - SACK enabled
710 * tcp_is_reno - No SACK
711 * tcp_is_fack - FACK enabled, implies SACK enabled
713 static inline int tcp_is_sack(const struct tcp_sock *tp)
715 return tp->rx_opt.sack_ok;
718 static inline int tcp_is_reno(const struct tcp_sock *tp)
720 return !tcp_is_sack(tp);
723 static inline int tcp_is_fack(const struct tcp_sock *tp)
725 return tp->rx_opt.sack_ok & 2;
728 static inline void tcp_enable_fack(struct tcp_sock *tp)
730 tp->rx_opt.sack_ok |= 2;
733 static inline unsigned int tcp_left_out(const struct tcp_sock *tp)
735 return tp->sacked_out + tp->lost_out;
738 /* This determines how many packets are "in the network" to the best
739 * of our knowledge. In many cases it is conservative, but where
740 * detailed information is available from the receiver (via SACK
741 * blocks etc.) we can make more aggressive calculations.
743 * Use this for decisions involving congestion control, use just
744 * tp->packets_out to determine if the send queue is empty or not.
746 * Read this equation as:
748 * "Packets sent once on transmission queue" MINUS
749 * "Packets left network, but not honestly ACKed yet" PLUS
750 * "Packets fast retransmitted"
752 static inline unsigned int tcp_packets_in_flight(const struct tcp_sock *tp)
754 return tp->packets_out - tcp_left_out(tp) + tp->retrans_out;
757 #define TCP_INFINITE_SSTHRESH 0x7fffffff
759 static inline bool tcp_in_initial_slowstart(const struct tcp_sock *tp)
761 return tp->snd_ssthresh >= TCP_INFINITE_SSTHRESH;
764 /* If cwnd > ssthresh, we may raise ssthresh to be half-way to cwnd.
765 * The exception is rate halving phase, when cwnd is decreasing towards
768 static inline __u32 tcp_current_ssthresh(const struct sock *sk)
770 const struct tcp_sock *tp = tcp_sk(sk);
771 if ((1 << inet_csk(sk)->icsk_ca_state) & (TCPF_CA_CWR | TCPF_CA_Recovery))
772 return tp->snd_ssthresh;
774 return max(tp->snd_ssthresh,
775 ((tp->snd_cwnd >> 1) +
776 (tp->snd_cwnd >> 2)));
779 /* Use define here intentionally to get WARN_ON location shown at the caller */
780 #define tcp_verify_left_out(tp) WARN_ON(tcp_left_out(tp) > tp->packets_out)
783 * Convert RFC 3390 larger initial window into an equivalent number of packets.
784 * This is based on the numbers specified in RFC 5681, 3.1.
786 static inline u32 rfc3390_bytes_to_packets(const u32 smss)
788 return smss <= 1095 ? 4 : (smss > 2190 ? 2 : 3);
791 extern void tcp_enter_cwr(struct sock *sk, const int set_ssthresh);
792 extern __u32 tcp_init_cwnd(struct tcp_sock *tp, struct dst_entry *dst);
794 /* Slow start with delack produces 3 packets of burst, so that
795 * it is safe "de facto". This will be the default - same as
796 * the default reordering threshold - but if reordering increases,
797 * we must be able to allow cwnd to burst at least this much in order
798 * to not pull it back when holes are filled.
800 static __inline__ __u32 tcp_max_burst(const struct tcp_sock *tp)
802 return tp->reordering;
805 /* Returns end sequence number of the receiver's advertised window */
806 static inline u32 tcp_wnd_end(const struct tcp_sock *tp)
808 return tp->snd_una + tp->snd_wnd;
810 extern int tcp_is_cwnd_limited(const struct sock *sk, u32 in_flight);
812 static inline void tcp_minshall_update(struct tcp_sock *tp, unsigned int mss,
813 const struct sk_buff *skb)
816 tp->snd_sml = TCP_SKB_CB(skb)->end_seq;
819 static inline void tcp_check_probe_timer(struct sock *sk)
821 struct tcp_sock *tp = tcp_sk(sk);
822 const struct inet_connection_sock *icsk = inet_csk(sk);
824 if (!tp->packets_out && !icsk->icsk_pending)
825 inet_csk_reset_xmit_timer(sk, ICSK_TIME_PROBE0,
826 icsk->icsk_rto, TCP_RTO_MAX);
829 static inline void tcp_init_wl(struct tcp_sock *tp, u32 seq)
834 static inline void tcp_update_wl(struct tcp_sock *tp, u32 seq)
840 * Calculate(/check) TCP checksum
842 static inline __sum16 tcp_v4_check(int len, __be32 saddr,
843 __be32 daddr, __wsum base)
845 return csum_tcpudp_magic(saddr,daddr,len,IPPROTO_TCP,base);
848 static inline __sum16 __tcp_checksum_complete(struct sk_buff *skb)
850 return __skb_checksum_complete(skb);
853 static inline int tcp_checksum_complete(struct sk_buff *skb)
855 return !skb_csum_unnecessary(skb) &&
856 __tcp_checksum_complete(skb);
859 /* Prequeue for VJ style copy to user, combined with checksumming. */
861 static inline void tcp_prequeue_init(struct tcp_sock *tp)
863 tp->ucopy.task = NULL;
865 tp->ucopy.memory = 0;
866 skb_queue_head_init(&tp->ucopy.prequeue);
867 #ifdef CONFIG_NET_DMA
868 tp->ucopy.dma_chan = NULL;
869 tp->ucopy.wakeup = 0;
870 tp->ucopy.pinned_list = NULL;
871 tp->ucopy.dma_cookie = 0;
875 /* Packet is added to VJ-style prequeue for processing in process
876 * context, if a reader task is waiting. Apparently, this exciting
877 * idea (VJ's mail "Re: query about TCP header on tcp-ip" of 07 Sep 93)
878 * failed somewhere. Latency? Burstiness? Well, at least now we will
879 * see, why it failed. 8)8) --ANK
881 * NOTE: is this not too big to inline?
883 static inline int tcp_prequeue(struct sock *sk, struct sk_buff *skb)
885 struct tcp_sock *tp = tcp_sk(sk);
887 if (sysctl_tcp_low_latency || !tp->ucopy.task)
890 __skb_queue_tail(&tp->ucopy.prequeue, skb);
891 tp->ucopy.memory += skb->truesize;
892 if (tp->ucopy.memory > sk->sk_rcvbuf) {
893 struct sk_buff *skb1;
895 BUG_ON(sock_owned_by_user(sk));
897 while ((skb1 = __skb_dequeue(&tp->ucopy.prequeue)) != NULL) {
898 sk_backlog_rcv(sk, skb1);
899 NET_INC_STATS_BH(sock_net(sk),
900 LINUX_MIB_TCPPREQUEUEDROPPED);
903 tp->ucopy.memory = 0;
904 } else if (skb_queue_len(&tp->ucopy.prequeue) == 1) {
905 wake_up_interruptible_sync_poll(sk_sleep(sk),
906 POLLIN | POLLRDNORM | POLLRDBAND);
907 if (!inet_csk_ack_scheduled(sk))
908 inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK,
909 (3 * tcp_rto_min(sk)) / 4,
919 static const char *statename[]={
920 "Unused","Established","Syn Sent","Syn Recv",
921 "Fin Wait 1","Fin Wait 2","Time Wait", "Close",
922 "Close Wait","Last ACK","Listen","Closing"
925 extern void tcp_set_state(struct sock *sk, int state);
927 extern void tcp_done(struct sock *sk);
929 static inline void tcp_sack_reset(struct tcp_options_received *rx_opt)
932 rx_opt->num_sacks = 0;
935 /* Determine a window scaling and initial window to offer. */
936 extern void tcp_select_initial_window(int __space, __u32 mss,
937 __u32 *rcv_wnd, __u32 *window_clamp,
938 int wscale_ok, __u8 *rcv_wscale,
941 static inline int tcp_win_from_space(int space)
943 return sysctl_tcp_adv_win_scale<=0 ?
944 (space>>(-sysctl_tcp_adv_win_scale)) :
945 space - (space>>sysctl_tcp_adv_win_scale);
948 /* Note: caller must be prepared to deal with negative returns */
949 static inline int tcp_space(const struct sock *sk)
951 return tcp_win_from_space(sk->sk_rcvbuf -
952 atomic_read(&sk->sk_rmem_alloc));
955 static inline int tcp_full_space(const struct sock *sk)
957 return tcp_win_from_space(sk->sk_rcvbuf);
960 static inline void tcp_openreq_init(struct request_sock *req,
961 struct tcp_options_received *rx_opt,
964 struct inet_request_sock *ireq = inet_rsk(req);
966 req->rcv_wnd = 0; /* So that tcp_send_synack() knows! */
968 tcp_rsk(req)->rcv_isn = TCP_SKB_CB(skb)->seq;
969 req->mss = rx_opt->mss_clamp;
970 req->ts_recent = rx_opt->saw_tstamp ? rx_opt->rcv_tsval : 0;
971 ireq->tstamp_ok = rx_opt->tstamp_ok;
972 ireq->sack_ok = rx_opt->sack_ok;
973 ireq->snd_wscale = rx_opt->snd_wscale;
974 ireq->wscale_ok = rx_opt->wscale_ok;
977 ireq->rmt_port = tcp_hdr(skb)->source;
978 ireq->loc_port = tcp_hdr(skb)->dest;
981 extern void tcp_enter_memory_pressure(struct sock *sk);
983 static inline int keepalive_intvl_when(const struct tcp_sock *tp)
985 return tp->keepalive_intvl ? : sysctl_tcp_keepalive_intvl;
988 static inline int keepalive_time_when(const struct tcp_sock *tp)
990 return tp->keepalive_time ? : sysctl_tcp_keepalive_time;
993 static inline int keepalive_probes(const struct tcp_sock *tp)
995 return tp->keepalive_probes ? : sysctl_tcp_keepalive_probes;
998 static inline u32 keepalive_time_elapsed(const struct tcp_sock *tp)
1000 const struct inet_connection_sock *icsk = &tp->inet_conn;
1002 return min_t(u32, tcp_time_stamp - icsk->icsk_ack.lrcvtime,
1003 tcp_time_stamp - tp->rcv_tstamp);
1006 static inline int tcp_fin_time(const struct sock *sk)
1008 int fin_timeout = tcp_sk(sk)->linger2 ? : sysctl_tcp_fin_timeout;
1009 const int rto = inet_csk(sk)->icsk_rto;
1011 if (fin_timeout < (rto << 2) - (rto >> 1))
1012 fin_timeout = (rto << 2) - (rto >> 1);
1017 static inline int tcp_paws_check(const struct tcp_options_received *rx_opt,
1020 if ((s32)(rx_opt->ts_recent - rx_opt->rcv_tsval) <= paws_win)
1022 if (unlikely(get_seconds() >= rx_opt->ts_recent_stamp + TCP_PAWS_24DAYS))
1028 static inline int tcp_paws_reject(const struct tcp_options_received *rx_opt,
1031 if (tcp_paws_check(rx_opt, 0))
1034 /* RST segments are not recommended to carry timestamp,
1035 and, if they do, it is recommended to ignore PAWS because
1036 "their cleanup function should take precedence over timestamps."
1037 Certainly, it is mistake. It is necessary to understand the reasons
1038 of this constraint to relax it: if peer reboots, clock may go
1039 out-of-sync and half-open connections will not be reset.
1040 Actually, the problem would be not existing if all
1041 the implementations followed draft about maintaining clock
1042 via reboots. Linux-2.2 DOES NOT!
1044 However, we can relax time bounds for RST segments to MSL.
1046 if (rst && get_seconds() >= rx_opt->ts_recent_stamp + TCP_PAWS_MSL)
1051 #define TCP_CHECK_TIMER(sk) do { } while (0)
1053 static inline void tcp_mib_init(struct net *net)
1056 TCP_ADD_STATS_USER(net, TCP_MIB_RTOALGORITHM, 1);
1057 TCP_ADD_STATS_USER(net, TCP_MIB_RTOMIN, TCP_RTO_MIN*1000/HZ);
1058 TCP_ADD_STATS_USER(net, TCP_MIB_RTOMAX, TCP_RTO_MAX*1000/HZ);
1059 TCP_ADD_STATS_USER(net, TCP_MIB_MAXCONN, -1);
1063 static inline void tcp_clear_retrans_hints_partial(struct tcp_sock *tp)
1065 tp->lost_skb_hint = NULL;
1066 tp->scoreboard_skb_hint = NULL;
1069 static inline void tcp_clear_all_retrans_hints(struct tcp_sock *tp)
1071 tcp_clear_retrans_hints_partial(tp);
1072 tp->retransmit_skb_hint = NULL;
1078 /* - key database */
1079 struct tcp_md5sig_key {
1084 struct tcp4_md5sig_key {
1085 struct tcp_md5sig_key base;
1089 struct tcp6_md5sig_key {
1090 struct tcp_md5sig_key base;
1092 u32 scope_id; /* XXX */
1094 struct in6_addr addr;
1098 struct tcp_md5sig_info {
1099 struct tcp4_md5sig_key *keys4;
1100 #if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
1101 struct tcp6_md5sig_key *keys6;
1109 /* - pseudo header */
1110 struct tcp4_pseudohdr {
1118 struct tcp6_pseudohdr {
1119 struct in6_addr saddr;
1120 struct in6_addr daddr;
1122 __be32 protocol; /* including padding */
1125 union tcp_md5sum_block {
1126 struct tcp4_pseudohdr ip4;
1127 #if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
1128 struct tcp6_pseudohdr ip6;
1132 /* - pool: digest algorithm, hash description and scratch buffer */
1133 struct tcp_md5sig_pool {
1134 struct hash_desc md5_desc;
1135 union tcp_md5sum_block md5_blk;
1138 #define TCP_MD5SIG_MAXKEYS (~(u32)0) /* really?! */
1141 extern int tcp_v4_md5_hash_skb(char *md5_hash, struct tcp_md5sig_key *key,
1142 struct sock *sk, struct request_sock *req,
1143 struct sk_buff *skb);
1144 extern struct tcp_md5sig_key * tcp_v4_md5_lookup(struct sock *sk,
1145 struct sock *addr_sk);
1146 extern int tcp_v4_md5_do_add(struct sock *sk, __be32 addr, u8 *newkey,
1148 extern int tcp_v4_md5_do_del(struct sock *sk, __be32 addr);
1150 #ifdef CONFIG_TCP_MD5SIG
1151 #define tcp_twsk_md5_key(twsk) ((twsk)->tw_md5_keylen ? \
1152 &(struct tcp_md5sig_key) { \
1153 .key = (twsk)->tw_md5_key, \
1154 .keylen = (twsk)->tw_md5_keylen, \
1157 #define tcp_twsk_md5_key(twsk) NULL
1160 extern struct tcp_md5sig_pool * __percpu *tcp_alloc_md5sig_pool(struct sock *);
1161 extern void tcp_free_md5sig_pool(void);
1163 extern struct tcp_md5sig_pool *tcp_get_md5sig_pool(void);
1164 extern void tcp_put_md5sig_pool(void);
1166 extern int tcp_md5_hash_header(struct tcp_md5sig_pool *, struct tcphdr *);
1167 extern int tcp_md5_hash_skb_data(struct tcp_md5sig_pool *, struct sk_buff *,
1168 unsigned header_len);
1169 extern int tcp_md5_hash_key(struct tcp_md5sig_pool *hp,
1170 struct tcp_md5sig_key *key);
1172 /* write queue abstraction */
1173 static inline void tcp_write_queue_purge(struct sock *sk)
1175 struct sk_buff *skb;
1177 while ((skb = __skb_dequeue(&sk->sk_write_queue)) != NULL)
1178 sk_wmem_free_skb(sk, skb);
1180 tcp_clear_all_retrans_hints(tcp_sk(sk));
1183 static inline struct sk_buff *tcp_write_queue_head(struct sock *sk)
1185 return skb_peek(&sk->sk_write_queue);
1188 static inline struct sk_buff *tcp_write_queue_tail(struct sock *sk)
1190 return skb_peek_tail(&sk->sk_write_queue);
1193 static inline struct sk_buff *tcp_write_queue_next(struct sock *sk, struct sk_buff *skb)
1195 return skb_queue_next(&sk->sk_write_queue, skb);
1198 static inline struct sk_buff *tcp_write_queue_prev(struct sock *sk, struct sk_buff *skb)
1200 return skb_queue_prev(&sk->sk_write_queue, skb);
1203 #define tcp_for_write_queue(skb, sk) \
1204 skb_queue_walk(&(sk)->sk_write_queue, skb)
1206 #define tcp_for_write_queue_from(skb, sk) \
1207 skb_queue_walk_from(&(sk)->sk_write_queue, skb)
1209 #define tcp_for_write_queue_from_safe(skb, tmp, sk) \
1210 skb_queue_walk_from_safe(&(sk)->sk_write_queue, skb, tmp)
1212 static inline struct sk_buff *tcp_send_head(struct sock *sk)
1214 return sk->sk_send_head;
1217 static inline bool tcp_skb_is_last(const struct sock *sk,
1218 const struct sk_buff *skb)
1220 return skb_queue_is_last(&sk->sk_write_queue, skb);
1223 static inline void tcp_advance_send_head(struct sock *sk, struct sk_buff *skb)
1225 if (tcp_skb_is_last(sk, skb))
1226 sk->sk_send_head = NULL;
1228 sk->sk_send_head = tcp_write_queue_next(sk, skb);
1231 static inline void tcp_check_send_head(struct sock *sk, struct sk_buff *skb_unlinked)
1233 if (sk->sk_send_head == skb_unlinked)
1234 sk->sk_send_head = NULL;
1237 static inline void tcp_init_send_head(struct sock *sk)
1239 sk->sk_send_head = NULL;
1242 static inline void __tcp_add_write_queue_tail(struct sock *sk, struct sk_buff *skb)
1244 __skb_queue_tail(&sk->sk_write_queue, skb);
1247 static inline void tcp_add_write_queue_tail(struct sock *sk, struct sk_buff *skb)
1249 __tcp_add_write_queue_tail(sk, skb);
1251 /* Queue it, remembering where we must start sending. */
1252 if (sk->sk_send_head == NULL) {
1253 sk->sk_send_head = skb;
1255 if (tcp_sk(sk)->highest_sack == NULL)
1256 tcp_sk(sk)->highest_sack = skb;
1260 static inline void __tcp_add_write_queue_head(struct sock *sk, struct sk_buff *skb)
1262 __skb_queue_head(&sk->sk_write_queue, skb);
1265 /* Insert buff after skb on the write queue of sk. */
1266 static inline void tcp_insert_write_queue_after(struct sk_buff *skb,
1267 struct sk_buff *buff,
1270 __skb_queue_after(&sk->sk_write_queue, skb, buff);
1273 /* Insert new before skb on the write queue of sk. */
1274 static inline void tcp_insert_write_queue_before(struct sk_buff *new,
1275 struct sk_buff *skb,
1278 __skb_queue_before(&sk->sk_write_queue, skb, new);
1280 if (sk->sk_send_head == skb)
1281 sk->sk_send_head = new;
1284 static inline void tcp_unlink_write_queue(struct sk_buff *skb, struct sock *sk)
1286 __skb_unlink(skb, &sk->sk_write_queue);
1289 static inline int tcp_write_queue_empty(struct sock *sk)
1291 return skb_queue_empty(&sk->sk_write_queue);
1294 static inline void tcp_push_pending_frames(struct sock *sk)
1296 if (tcp_send_head(sk)) {
1297 struct tcp_sock *tp = tcp_sk(sk);
1299 __tcp_push_pending_frames(sk, tcp_current_mss(sk), tp->nonagle);
1303 /* Start sequence of the highest skb with SACKed bit, valid only if
1304 * sacked > 0 or when the caller has ensured validity by itself.
1306 static inline u32 tcp_highest_sack_seq(struct tcp_sock *tp)
1308 if (!tp->sacked_out)
1311 if (tp->highest_sack == NULL)
1314 return TCP_SKB_CB(tp->highest_sack)->seq;
1317 static inline void tcp_advance_highest_sack(struct sock *sk, struct sk_buff *skb)
1319 tcp_sk(sk)->highest_sack = tcp_skb_is_last(sk, skb) ? NULL :
1320 tcp_write_queue_next(sk, skb);
1323 static inline struct sk_buff *tcp_highest_sack(struct sock *sk)
1325 return tcp_sk(sk)->highest_sack;
1328 static inline void tcp_highest_sack_reset(struct sock *sk)
1330 tcp_sk(sk)->highest_sack = tcp_write_queue_head(sk);
1333 /* Called when old skb is about to be deleted (to be combined with new skb) */
1334 static inline void tcp_highest_sack_combine(struct sock *sk,
1335 struct sk_buff *old,
1336 struct sk_buff *new)
1338 if (tcp_sk(sk)->sacked_out && (old == tcp_sk(sk)->highest_sack))
1339 tcp_sk(sk)->highest_sack = new;
1342 /* Determines whether this is a thin stream (which may suffer from
1343 * increased latency). Used to trigger latency-reducing mechanisms.
1345 static inline unsigned int tcp_stream_is_thin(struct tcp_sock *tp)
1347 return tp->packets_out < 4 && !tcp_in_initial_slowstart(tp);
1351 enum tcp_seq_states {
1352 TCP_SEQ_STATE_LISTENING,
1353 TCP_SEQ_STATE_OPENREQ,
1354 TCP_SEQ_STATE_ESTABLISHED,
1355 TCP_SEQ_STATE_TIME_WAIT,
1358 struct tcp_seq_afinfo {
1361 struct file_operations seq_fops;
1362 struct seq_operations seq_ops;
1365 struct tcp_iter_state {
1366 struct seq_net_private p;
1368 enum tcp_seq_states state;
1369 struct sock *syn_wait_sk;
1370 int bucket, offset, sbucket, num, uid;
1374 extern int tcp_proc_register(struct net *net, struct tcp_seq_afinfo *afinfo);
1375 extern void tcp_proc_unregister(struct net *net, struct tcp_seq_afinfo *afinfo);
1377 extern struct request_sock_ops tcp_request_sock_ops;
1378 extern struct request_sock_ops tcp6_request_sock_ops;
1380 extern void tcp_v4_destroy_sock(struct sock *sk);
1382 extern int tcp_v4_gso_send_check(struct sk_buff *skb);
1383 extern struct sk_buff *tcp_tso_segment(struct sk_buff *skb, int features);
1384 extern struct sk_buff **tcp_gro_receive(struct sk_buff **head,
1385 struct sk_buff *skb);
1386 extern struct sk_buff **tcp4_gro_receive(struct sk_buff **head,
1387 struct sk_buff *skb);
1388 extern int tcp_gro_complete(struct sk_buff *skb);
1389 extern int tcp4_gro_complete(struct sk_buff *skb);
1391 #ifdef CONFIG_PROC_FS
1392 extern int tcp4_proc_init(void);
1393 extern void tcp4_proc_exit(void);
1396 /* TCP af-specific functions */
1397 struct tcp_sock_af_ops {
1398 #ifdef CONFIG_TCP_MD5SIG
1399 struct tcp_md5sig_key *(*md5_lookup) (struct sock *sk,
1400 struct sock *addr_sk);
1401 int (*calc_md5_hash) (char *location,
1402 struct tcp_md5sig_key *md5,
1404 struct request_sock *req,
1405 struct sk_buff *skb);
1406 int (*md5_add) (struct sock *sk,
1407 struct sock *addr_sk,
1410 int (*md5_parse) (struct sock *sk,
1411 char __user *optval,
1416 struct tcp_request_sock_ops {
1417 #ifdef CONFIG_TCP_MD5SIG
1418 struct tcp_md5sig_key *(*md5_lookup) (struct sock *sk,
1419 struct request_sock *req);
1420 int (*calc_md5_hash) (char *location,
1421 struct tcp_md5sig_key *md5,
1423 struct request_sock *req,
1424 struct sk_buff *skb);
1428 /* Using SHA1 for now, define some constants.
1430 #define COOKIE_DIGEST_WORDS (SHA_DIGEST_WORDS)
1431 #define COOKIE_MESSAGE_WORDS (SHA_MESSAGE_BYTES / 4)
1432 #define COOKIE_WORKSPACE_WORDS (COOKIE_DIGEST_WORDS + COOKIE_MESSAGE_WORDS)
1434 extern int tcp_cookie_generator(u32 *bakery);
1437 * struct tcp_cookie_values - each socket needs extra space for the
1438 * cookies, together with (optional) space for any SYN data.
1440 * A tcp_sock contains a pointer to the current value, and this is
1441 * cloned to the tcp_timewait_sock.
1443 * @cookie_pair: variable data from the option exchange.
1445 * @cookie_desired: user specified tcpct_cookie_desired. Zero
1446 * indicates default (sysctl_tcp_cookie_size).
1447 * After cookie sent, remembers size of cookie.
1448 * Range 0, TCP_COOKIE_MIN to TCP_COOKIE_MAX.
1450 * @s_data_desired: user specified tcpct_s_data_desired. When the
1451 * constant payload is specified (@s_data_constant),
1452 * holds its length instead.
1453 * Range 0 to TCP_MSS_DESIRED.
1455 * @s_data_payload: constant data that is to be included in the
1456 * payload of SYN or SYNACK segments when the
1457 * cookie option is present.
1459 struct tcp_cookie_values {
1461 u8 cookie_pair[TCP_COOKIE_PAIR_SIZE];
1462 u8 cookie_pair_size;
1464 u16 s_data_desired:11,
1469 u8 s_data_payload[0];
1472 static inline void tcp_cookie_values_release(struct kref *kref)
1474 kfree(container_of(kref, struct tcp_cookie_values, kref));
1477 /* The length of constant payload data. Note that s_data_desired is
1478 * overloaded, depending on s_data_constant: either the length of constant
1479 * data (returned here) or the limit on variable data.
1481 static inline int tcp_s_data_size(const struct tcp_sock *tp)
1483 return (tp->cookie_values != NULL && tp->cookie_values->s_data_constant)
1484 ? tp->cookie_values->s_data_desired
1489 * struct tcp_extend_values - tcp_ipv?.c to tcp_output.c workspace.
1491 * As tcp_request_sock has already been extended in other places, the
1492 * only remaining method is to pass stack values along as function
1493 * parameters. These parameters are not needed after sending SYNACK.
1495 * @cookie_bakery: cryptographic secret and message workspace.
1497 * @cookie_plus: bytes in authenticator/cookie option, copied from
1498 * struct tcp_options_received (above).
1500 struct tcp_extend_values {
1501 struct request_values rv;
1502 u32 cookie_bakery[COOKIE_WORKSPACE_WORDS];
1508 static inline struct tcp_extend_values *tcp_xv(struct request_values *rvp)
1510 return (struct tcp_extend_values *)rvp;
1513 extern void tcp_v4_init(void);
1514 extern void tcp_init(void);