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1/*
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.
5 *
6 * Definitions for the TCP module.
7 *
8 * Version: @(#)tcp.h 1.0.5 05/23/93
9 *
10 * Authors: Ross Biro, <bir7@leland.Stanford.Edu>
11 * Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
12 *
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.
17 */
18#ifndef _TCP_H
19#define _TCP_H
20
21#define TCP_DEBUG 1
22#define FASTRETRANS_DEBUG 1
23
24/* Cancel timers, when they are not required. */
25#undef TCP_CLEAR_TIMERS
26
27#include <linux/config.h>
28#include <linux/list.h>
29#include <linux/tcp.h>
30#include <linux/slab.h>
31#include <linux/cache.h>
32#include <linux/percpu.h>
33#include <net/checksum.h>
34#include <net/sock.h>
35#include <net/snmp.h>
36#include <net/ip.h>
37#if defined(CONFIG_IPV6) || defined (CONFIG_IPV6_MODULE)
38#include <linux/ipv6.h>
39#endif
40#include <linux/seq_file.h>
41
42/* This is for all connections with a full identity, no wildcards.
43 * New scheme, half the table is for TIME_WAIT, the other half is
44 * for the rest. I'll experiment with dynamic table growth later.
45 */
46struct tcp_ehash_bucket {
47 rwlock_t lock;
48 struct hlist_head chain;
49} __attribute__((__aligned__(8)));
50
51/* This is for listening sockets, thus all sockets which possess wildcards. */
52#define TCP_LHTABLE_SIZE 32 /* Yes, really, this is all you need. */
53
54/* There are a few simple rules, which allow for local port reuse by
55 * an application. In essence:
56 *
57 * 1) Sockets bound to different interfaces may share a local port.
58 * Failing that, goto test 2.
59 * 2) If all sockets have sk->sk_reuse set, and none of them are in
60 * TCP_LISTEN state, the port may be shared.
61 * Failing that, goto test 3.
62 * 3) If all sockets are bound to a specific inet_sk(sk)->rcv_saddr local
63 * address, and none of them are the same, the port may be
64 * shared.
65 * Failing this, the port cannot be shared.
66 *
67 * The interesting point, is test #2. This is what an FTP server does
68 * all day. To optimize this case we use a specific flag bit defined
69 * below. As we add sockets to a bind bucket list, we perform a
70 * check of: (newsk->sk_reuse && (newsk->sk_state != TCP_LISTEN))
71 * As long as all sockets added to a bind bucket pass this test,
72 * the flag bit will be set.
73 * The resulting situation is that tcp_v[46]_verify_bind() can just check
74 * for this flag bit, if it is set and the socket trying to bind has
75 * sk->sk_reuse set, we don't even have to walk the owners list at all,
76 * we return that it is ok to bind this socket to the requested local port.
77 *
78 * Sounds like a lot of work, but it is worth it. In a more naive
79 * implementation (ie. current FreeBSD etc.) the entire list of ports
80 * must be walked for each data port opened by an ftp server. Needless
81 * to say, this does not scale at all. With a couple thousand FTP
82 * users logged onto your box, isn't it nice to know that new data
83 * ports are created in O(1) time? I thought so. ;-) -DaveM
84 */
85struct tcp_bind_bucket {
86 unsigned short port;
87 signed short fastreuse;
88 struct hlist_node node;
89 struct hlist_head owners;
90};
91
92#define tb_for_each(tb, node, head) hlist_for_each_entry(tb, node, head, node)
93
94struct tcp_bind_hashbucket {
95 spinlock_t lock;
96 struct hlist_head chain;
97};
98
99static inline struct tcp_bind_bucket *__tb_head(struct tcp_bind_hashbucket *head)
100{
101 return hlist_entry(head->chain.first, struct tcp_bind_bucket, node);
102}
103
104static inline struct tcp_bind_bucket *tb_head(struct tcp_bind_hashbucket *head)
105{
106 return hlist_empty(&head->chain) ? NULL : __tb_head(head);
107}
108
109extern struct tcp_hashinfo {
110 /* This is for sockets with full identity only. Sockets here will
111 * always be without wildcards and will have the following invariant:
112 *
113 * TCP_ESTABLISHED <= sk->sk_state < TCP_CLOSE
114 *
115 * First half of the table is for sockets not in TIME_WAIT, second half
116 * is for TIME_WAIT sockets only.
117 */
118 struct tcp_ehash_bucket *__tcp_ehash;
119
120 /* Ok, let's try this, I give up, we do need a local binding
121 * TCP hash as well as the others for fast bind/connect.
122 */
123 struct tcp_bind_hashbucket *__tcp_bhash;
124
125 int __tcp_bhash_size;
126 int __tcp_ehash_size;
127
128 /* All sockets in TCP_LISTEN state will be in here. This is the only
129 * table where wildcard'd TCP sockets can exist. Hash function here
130 * is just local port number.
131 */
132 struct hlist_head __tcp_listening_hash[TCP_LHTABLE_SIZE];
133
134 /* All the above members are written once at bootup and
135 * never written again _or_ are predominantly read-access.
136 *
137 * Now align to a new cache line as all the following members
138 * are often dirty.
139 */
140 rwlock_t __tcp_lhash_lock ____cacheline_aligned;
141 atomic_t __tcp_lhash_users;
142 wait_queue_head_t __tcp_lhash_wait;
143 spinlock_t __tcp_portalloc_lock;
144} tcp_hashinfo;
145
146#define tcp_ehash (tcp_hashinfo.__tcp_ehash)
147#define tcp_bhash (tcp_hashinfo.__tcp_bhash)
148#define tcp_ehash_size (tcp_hashinfo.__tcp_ehash_size)
149#define tcp_bhash_size (tcp_hashinfo.__tcp_bhash_size)
150#define tcp_listening_hash (tcp_hashinfo.__tcp_listening_hash)
151#define tcp_lhash_lock (tcp_hashinfo.__tcp_lhash_lock)
152#define tcp_lhash_users (tcp_hashinfo.__tcp_lhash_users)
153#define tcp_lhash_wait (tcp_hashinfo.__tcp_lhash_wait)
154#define tcp_portalloc_lock (tcp_hashinfo.__tcp_portalloc_lock)
155
156extern kmem_cache_t *tcp_bucket_cachep;
157extern struct tcp_bind_bucket *tcp_bucket_create(struct tcp_bind_hashbucket *head,
158 unsigned short snum);
159extern void tcp_bucket_destroy(struct tcp_bind_bucket *tb);
160extern void tcp_bucket_unlock(struct sock *sk);
161extern int tcp_port_rover;
162
163/* These are AF independent. */
164static __inline__ int tcp_bhashfn(__u16 lport)
165{
166 return (lport & (tcp_bhash_size - 1));
167}
168
169extern void tcp_bind_hash(struct sock *sk, struct tcp_bind_bucket *tb,
170 unsigned short snum);
171
172#if (BITS_PER_LONG == 64)
173#define TCP_ADDRCMP_ALIGN_BYTES 8
174#else
175#define TCP_ADDRCMP_ALIGN_BYTES 4
176#endif
177
178/* This is a TIME_WAIT bucket. It works around the memory consumption
179 * problems of sockets in such a state on heavily loaded servers, but
180 * without violating the protocol specification.
181 */
182struct tcp_tw_bucket {
183 /*
184 * Now struct sock also uses sock_common, so please just
185 * don't add nothing before this first member (__tw_common) --acme
186 */
187 struct sock_common __tw_common;
188#define tw_family __tw_common.skc_family
189#define tw_state __tw_common.skc_state
190#define tw_reuse __tw_common.skc_reuse
191#define tw_bound_dev_if __tw_common.skc_bound_dev_if
192#define tw_node __tw_common.skc_node
193#define tw_bind_node __tw_common.skc_bind_node
194#define tw_refcnt __tw_common.skc_refcnt
195 volatile unsigned char tw_substate;
196 unsigned char tw_rcv_wscale;
197 __u16 tw_sport;
198 /* Socket demultiplex comparisons on incoming packets. */
199 /* these five are in inet_sock */
200 __u32 tw_daddr
201 __attribute__((aligned(TCP_ADDRCMP_ALIGN_BYTES)));
202 __u32 tw_rcv_saddr;
203 __u16 tw_dport;
204 __u16 tw_num;
205 /* And these are ours. */
206 int tw_hashent;
207 int tw_timeout;
208 __u32 tw_rcv_nxt;
209 __u32 tw_snd_nxt;
210 __u32 tw_rcv_wnd;
211 __u32 tw_ts_recent;
212 long tw_ts_recent_stamp;
213 unsigned long tw_ttd;
214 struct tcp_bind_bucket *tw_tb;
215 struct hlist_node tw_death_node;
216#if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
217 struct in6_addr tw_v6_daddr;
218 struct in6_addr tw_v6_rcv_saddr;
219 int tw_v6_ipv6only;
220#endif
221};
222
223static __inline__ void tw_add_node(struct tcp_tw_bucket *tw,
224 struct hlist_head *list)
225{
226 hlist_add_head(&tw->tw_node, list);
227}
228
229static __inline__ void tw_add_bind_node(struct tcp_tw_bucket *tw,
230 struct hlist_head *list)
231{
232 hlist_add_head(&tw->tw_bind_node, list);
233}
234
235static inline int tw_dead_hashed(struct tcp_tw_bucket *tw)
236{
237 return tw->tw_death_node.pprev != NULL;
238}
239
240static __inline__ void tw_dead_node_init(struct tcp_tw_bucket *tw)
241{
242 tw->tw_death_node.pprev = NULL;
243}
244
245static __inline__ void __tw_del_dead_node(struct tcp_tw_bucket *tw)
246{
247 __hlist_del(&tw->tw_death_node);
248 tw_dead_node_init(tw);
249}
250
251static __inline__ int tw_del_dead_node(struct tcp_tw_bucket *tw)
252{
253 if (tw_dead_hashed(tw)) {
254 __tw_del_dead_node(tw);
255 return 1;
256 }
257 return 0;
258}
259
260#define tw_for_each(tw, node, head) \
261 hlist_for_each_entry(tw, node, head, tw_node)
262
263#define tw_for_each_inmate(tw, node, jail) \
264 hlist_for_each_entry(tw, node, jail, tw_death_node)
265
266#define tw_for_each_inmate_safe(tw, node, safe, jail) \
267 hlist_for_each_entry_safe(tw, node, safe, jail, tw_death_node)
268
269#define tcptw_sk(__sk) ((struct tcp_tw_bucket *)(__sk))
270
271static inline u32 tcp_v4_rcv_saddr(const struct sock *sk)
272{
273 return likely(sk->sk_state != TCP_TIME_WAIT) ?
274 inet_sk(sk)->rcv_saddr : tcptw_sk(sk)->tw_rcv_saddr;
275}
276
277#if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
278static inline struct in6_addr *__tcp_v6_rcv_saddr(const struct sock *sk)
279{
280 return likely(sk->sk_state != TCP_TIME_WAIT) ?
281 &inet6_sk(sk)->rcv_saddr : &tcptw_sk(sk)->tw_v6_rcv_saddr;
282}
283
284static inline struct in6_addr *tcp_v6_rcv_saddr(const struct sock *sk)
285{
286 return sk->sk_family == AF_INET6 ? __tcp_v6_rcv_saddr(sk) : NULL;
287}
288
289#define tcptw_sk_ipv6only(__sk) (tcptw_sk(__sk)->tw_v6_ipv6only)
290
291static inline int tcp_v6_ipv6only(const struct sock *sk)
292{
293 return likely(sk->sk_state != TCP_TIME_WAIT) ?
294 ipv6_only_sock(sk) : tcptw_sk_ipv6only(sk);
295}
296#else
297# define __tcp_v6_rcv_saddr(__sk) NULL
298# define tcp_v6_rcv_saddr(__sk) NULL
299# define tcptw_sk_ipv6only(__sk) 0
300# define tcp_v6_ipv6only(__sk) 0
301#endif
302
303extern kmem_cache_t *tcp_timewait_cachep;
304
305static inline void tcp_tw_put(struct tcp_tw_bucket *tw)
306{
307 if (atomic_dec_and_test(&tw->tw_refcnt)) {
308#ifdef INET_REFCNT_DEBUG
309 printk(KERN_DEBUG "tw_bucket %p released\n", tw);
310#endif
311 kmem_cache_free(tcp_timewait_cachep, tw);
312 }
313}
314
315extern atomic_t tcp_orphan_count;
316extern int tcp_tw_count;
317extern void tcp_time_wait(struct sock *sk, int state, int timeo);
318extern void tcp_tw_deschedule(struct tcp_tw_bucket *tw);
319
320
321/* Socket demux engine toys. */
322#ifdef __BIG_ENDIAN
323#define TCP_COMBINED_PORTS(__sport, __dport) \
324 (((__u32)(__sport)<<16) | (__u32)(__dport))
325#else /* __LITTLE_ENDIAN */
326#define TCP_COMBINED_PORTS(__sport, __dport) \
327 (((__u32)(__dport)<<16) | (__u32)(__sport))
328#endif
329
330#if (BITS_PER_LONG == 64)
331#ifdef __BIG_ENDIAN
332#define TCP_V4_ADDR_COOKIE(__name, __saddr, __daddr) \
333 __u64 __name = (((__u64)(__saddr))<<32)|((__u64)(__daddr));
334#else /* __LITTLE_ENDIAN */
335#define TCP_V4_ADDR_COOKIE(__name, __saddr, __daddr) \
336 __u64 __name = (((__u64)(__daddr))<<32)|((__u64)(__saddr));
337#endif /* __BIG_ENDIAN */
338#define TCP_IPV4_MATCH(__sk, __cookie, __saddr, __daddr, __ports, __dif)\
339 (((*((__u64 *)&(inet_sk(__sk)->daddr)))== (__cookie)) && \
340 ((*((__u32 *)&(inet_sk(__sk)->dport)))== (__ports)) && \
341 (!((__sk)->sk_bound_dev_if) || ((__sk)->sk_bound_dev_if == (__dif))))
342#define TCP_IPV4_TW_MATCH(__sk, __cookie, __saddr, __daddr, __ports, __dif)\
343 (((*((__u64 *)&(tcptw_sk(__sk)->tw_daddr))) == (__cookie)) && \
344 ((*((__u32 *)&(tcptw_sk(__sk)->tw_dport))) == (__ports)) && \
345 (!((__sk)->sk_bound_dev_if) || ((__sk)->sk_bound_dev_if == (__dif))))
346#else /* 32-bit arch */
347#define TCP_V4_ADDR_COOKIE(__name, __saddr, __daddr)
348#define TCP_IPV4_MATCH(__sk, __cookie, __saddr, __daddr, __ports, __dif)\
349 ((inet_sk(__sk)->daddr == (__saddr)) && \
350 (inet_sk(__sk)->rcv_saddr == (__daddr)) && \
351 ((*((__u32 *)&(inet_sk(__sk)->dport)))== (__ports)) && \
352 (!((__sk)->sk_bound_dev_if) || ((__sk)->sk_bound_dev_if == (__dif))))
353#define TCP_IPV4_TW_MATCH(__sk, __cookie, __saddr, __daddr, __ports, __dif)\
354 ((tcptw_sk(__sk)->tw_daddr == (__saddr)) && \
355 (tcptw_sk(__sk)->tw_rcv_saddr == (__daddr)) && \
356 ((*((__u32 *)&(tcptw_sk(__sk)->tw_dport))) == (__ports)) && \
357 (!((__sk)->sk_bound_dev_if) || ((__sk)->sk_bound_dev_if == (__dif))))
358#endif /* 64-bit arch */
359
360#define TCP_IPV6_MATCH(__sk, __saddr, __daddr, __ports, __dif) \
361 (((*((__u32 *)&(inet_sk(__sk)->dport)))== (__ports)) && \
362 ((__sk)->sk_family == AF_INET6) && \
363 ipv6_addr_equal(&inet6_sk(__sk)->daddr, (__saddr)) && \
364 ipv6_addr_equal(&inet6_sk(__sk)->rcv_saddr, (__daddr)) && \
365 (!((__sk)->sk_bound_dev_if) || ((__sk)->sk_bound_dev_if == (__dif))))
366
367/* These can have wildcards, don't try too hard. */
368static __inline__ int tcp_lhashfn(unsigned short num)
369{
370 return num & (TCP_LHTABLE_SIZE - 1);
371}
372
373static __inline__ int tcp_sk_listen_hashfn(struct sock *sk)
374{
375 return tcp_lhashfn(inet_sk(sk)->num);
376}
377
378#define MAX_TCP_HEADER (128 + MAX_HEADER)
379
380/*
381 * Never offer a window over 32767 without using window scaling. Some
382 * poor stacks do signed 16bit maths!
383 */
384#define MAX_TCP_WINDOW 32767U
385
386/* Minimal accepted MSS. It is (60+60+8) - (20+20). */
387#define TCP_MIN_MSS 88U
388
389/* Minimal RCV_MSS. */
390#define TCP_MIN_RCVMSS 536U
391
392/* After receiving this amount of duplicate ACKs fast retransmit starts. */
393#define TCP_FASTRETRANS_THRESH 3
394
395/* Maximal reordering. */
396#define TCP_MAX_REORDERING 127
397
398/* Maximal number of ACKs sent quickly to accelerate slow-start. */
399#define TCP_MAX_QUICKACKS 16U
400
401/* urg_data states */
402#define TCP_URG_VALID 0x0100
403#define TCP_URG_NOTYET 0x0200
404#define TCP_URG_READ 0x0400
405
406#define TCP_RETR1 3 /*
407 * This is how many retries it does before it
408 * tries to figure out if the gateway is
409 * down. Minimal RFC value is 3; it corresponds
410 * to ~3sec-8min depending on RTO.
411 */
412
413#define TCP_RETR2 15 /*
414 * This should take at least
415 * 90 minutes to time out.
416 * RFC1122 says that the limit is 100 sec.
417 * 15 is ~13-30min depending on RTO.
418 */
419
420#define TCP_SYN_RETRIES 5 /* number of times to retry active opening a
421 * connection: ~180sec is RFC minumum */
422
423#define TCP_SYNACK_RETRIES 5 /* number of times to retry passive opening a
424 * connection: ~180sec is RFC minumum */
425
426
427#define TCP_ORPHAN_RETRIES 7 /* number of times to retry on an orphaned
428 * socket. 7 is ~50sec-16min.
429 */
430
431
432#define TCP_TIMEWAIT_LEN (60*HZ) /* how long to wait to destroy TIME-WAIT
433 * state, about 60 seconds */
434#define TCP_FIN_TIMEOUT TCP_TIMEWAIT_LEN
435 /* BSD style FIN_WAIT2 deadlock breaker.
436 * It used to be 3min, new value is 60sec,
437 * to combine FIN-WAIT-2 timeout with
438 * TIME-WAIT timer.
439 */
440
441#define TCP_DELACK_MAX ((unsigned)(HZ/5)) /* maximal time to delay before sending an ACK */
442#if HZ >= 100
443#define TCP_DELACK_MIN ((unsigned)(HZ/25)) /* minimal time to delay before sending an ACK */
444#define TCP_ATO_MIN ((unsigned)(HZ/25))
445#else
446#define TCP_DELACK_MIN 4U
447#define TCP_ATO_MIN 4U
448#endif
449#define TCP_RTO_MAX ((unsigned)(120*HZ))
450#define TCP_RTO_MIN ((unsigned)(HZ/5))
451#define TCP_TIMEOUT_INIT ((unsigned)(3*HZ)) /* RFC 1122 initial RTO value */
452
453#define TCP_RESOURCE_PROBE_INTERVAL ((unsigned)(HZ/2U)) /* Maximal interval between probes
454 * for local resources.
455 */
456
457#define TCP_KEEPALIVE_TIME (120*60*HZ) /* two hours */
458#define TCP_KEEPALIVE_PROBES 9 /* Max of 9 keepalive probes */
459#define TCP_KEEPALIVE_INTVL (75*HZ)
460
461#define MAX_TCP_KEEPIDLE 32767
462#define MAX_TCP_KEEPINTVL 32767
463#define MAX_TCP_KEEPCNT 127
464#define MAX_TCP_SYNCNT 127
465
466#define TCP_SYNQ_INTERVAL (HZ/5) /* Period of SYNACK timer */
467#define TCP_SYNQ_HSIZE 512 /* Size of SYNACK hash table */
468
469#define TCP_PAWS_24DAYS (60 * 60 * 24 * 24)
470#define TCP_PAWS_MSL 60 /* Per-host timestamps are invalidated
471 * after this time. It should be equal
472 * (or greater than) TCP_TIMEWAIT_LEN
473 * to provide reliability equal to one
474 * provided by timewait state.
475 */
476#define TCP_PAWS_WINDOW 1 /* Replay window for per-host
477 * timestamps. It must be less than
478 * minimal timewait lifetime.
479 */
480
481#define TCP_TW_RECYCLE_SLOTS_LOG 5
482#define TCP_TW_RECYCLE_SLOTS (1<<TCP_TW_RECYCLE_SLOTS_LOG)
483
484/* If time > 4sec, it is "slow" path, no recycling is required,
485 so that we select tick to get range about 4 seconds.
486 */
487
488#if HZ <= 16 || HZ > 4096
489# error Unsupported: HZ <= 16 or HZ > 4096
490#elif HZ <= 32
491# define TCP_TW_RECYCLE_TICK (5+2-TCP_TW_RECYCLE_SLOTS_LOG)
492#elif HZ <= 64
493# define TCP_TW_RECYCLE_TICK (6+2-TCP_TW_RECYCLE_SLOTS_LOG)
494#elif HZ <= 128
495# define TCP_TW_RECYCLE_TICK (7+2-TCP_TW_RECYCLE_SLOTS_LOG)
496#elif HZ <= 256
497# define TCP_TW_RECYCLE_TICK (8+2-TCP_TW_RECYCLE_SLOTS_LOG)
498#elif HZ <= 512
499# define TCP_TW_RECYCLE_TICK (9+2-TCP_TW_RECYCLE_SLOTS_LOG)
500#elif HZ <= 1024
501# define TCP_TW_RECYCLE_TICK (10+2-TCP_TW_RECYCLE_SLOTS_LOG)
502#elif HZ <= 2048
503# define TCP_TW_RECYCLE_TICK (11+2-TCP_TW_RECYCLE_SLOTS_LOG)
504#else
505# define TCP_TW_RECYCLE_TICK (12+2-TCP_TW_RECYCLE_SLOTS_LOG)
506#endif
507
508#define BICTCP_BETA_SCALE 1024 /* Scale factor beta calculation
509 * max_cwnd = snd_cwnd * beta
510 */
511#define BICTCP_MAX_INCREMENT 32 /*
512 * Limit on the amount of
513 * increment allowed during
514 * binary search.
515 */
516#define BICTCP_FUNC_OF_MIN_INCR 11 /*
517 * log(B/Smin)/log(B/(B-1))+1,
518 * Smin:min increment
519 * B:log factor
520 */
521#define BICTCP_B 4 /*
522 * In binary search,
523 * go to point (max+min)/N
524 */
525
526/*
527 * TCP option
528 */
529
530#define TCPOPT_NOP 1 /* Padding */
531#define TCPOPT_EOL 0 /* End of options */
532#define TCPOPT_MSS 2 /* Segment size negotiating */
533#define TCPOPT_WINDOW 3 /* Window scaling */
534#define TCPOPT_SACK_PERM 4 /* SACK Permitted */
535#define TCPOPT_SACK 5 /* SACK Block */
536#define TCPOPT_TIMESTAMP 8 /* Better RTT estimations/PAWS */
537
538/*
539 * TCP option lengths
540 */
541
542#define TCPOLEN_MSS 4
543#define TCPOLEN_WINDOW 3
544#define TCPOLEN_SACK_PERM 2
545#define TCPOLEN_TIMESTAMP 10
546
547/* But this is what stacks really send out. */
548#define TCPOLEN_TSTAMP_ALIGNED 12
549#define TCPOLEN_WSCALE_ALIGNED 4
550#define TCPOLEN_SACKPERM_ALIGNED 4
551#define TCPOLEN_SACK_BASE 2
552#define TCPOLEN_SACK_BASE_ALIGNED 4
553#define TCPOLEN_SACK_PERBLOCK 8
554
555#define TCP_TIME_RETRANS 1 /* Retransmit timer */
556#define TCP_TIME_DACK 2 /* Delayed ack timer */
557#define TCP_TIME_PROBE0 3 /* Zero window probe timer */
558#define TCP_TIME_KEEPOPEN 4 /* Keepalive timer */
559
560/* Flags in tp->nonagle */
561#define TCP_NAGLE_OFF 1 /* Nagle's algo is disabled */
562#define TCP_NAGLE_CORK 2 /* Socket is corked */
563#define TCP_NAGLE_PUSH 4 /* Cork is overriden for already queued data */
564
565/* sysctl variables for tcp */
566extern int sysctl_max_syn_backlog;
567extern int sysctl_tcp_timestamps;
568extern int sysctl_tcp_window_scaling;
569extern int sysctl_tcp_sack;
570extern int sysctl_tcp_fin_timeout;
571extern int sysctl_tcp_tw_recycle;
572extern int sysctl_tcp_keepalive_time;
573extern int sysctl_tcp_keepalive_probes;
574extern int sysctl_tcp_keepalive_intvl;
575extern int sysctl_tcp_syn_retries;
576extern int sysctl_tcp_synack_retries;
577extern int sysctl_tcp_retries1;
578extern int sysctl_tcp_retries2;
579extern int sysctl_tcp_orphan_retries;
580extern int sysctl_tcp_syncookies;
581extern int sysctl_tcp_retrans_collapse;
582extern int sysctl_tcp_stdurg;
583extern int sysctl_tcp_rfc1337;
584extern int sysctl_tcp_abort_on_overflow;
585extern int sysctl_tcp_max_orphans;
586extern int sysctl_tcp_max_tw_buckets;
587extern int sysctl_tcp_fack;
588extern int sysctl_tcp_reordering;
589extern int sysctl_tcp_ecn;
590extern int sysctl_tcp_dsack;
591extern int sysctl_tcp_mem[3];
592extern int sysctl_tcp_wmem[3];
593extern int sysctl_tcp_rmem[3];
594extern int sysctl_tcp_app_win;
595extern int sysctl_tcp_adv_win_scale;
596extern int sysctl_tcp_tw_reuse;
597extern int sysctl_tcp_frto;
598extern int sysctl_tcp_low_latency;
599extern int sysctl_tcp_westwood;
600extern int sysctl_tcp_vegas_cong_avoid;
601extern int sysctl_tcp_vegas_alpha;
602extern int sysctl_tcp_vegas_beta;
603extern int sysctl_tcp_vegas_gamma;
604extern int sysctl_tcp_nometrics_save;
605extern int sysctl_tcp_bic;
606extern int sysctl_tcp_bic_fast_convergence;
607extern int sysctl_tcp_bic_low_window;
608extern int sysctl_tcp_bic_beta;
609extern int sysctl_tcp_moderate_rcvbuf;
610extern int sysctl_tcp_tso_win_divisor;
611
612extern atomic_t tcp_memory_allocated;
613extern atomic_t tcp_sockets_allocated;
614extern int tcp_memory_pressure;
615
616struct open_request;
617
618struct or_calltable {
619 int family;
620 int (*rtx_syn_ack) (struct sock *sk, struct open_request *req, struct dst_entry*);
621 void (*send_ack) (struct sk_buff *skb, struct open_request *req);
622 void (*destructor) (struct open_request *req);
623 void (*send_reset) (struct sk_buff *skb);
624};
625
626struct tcp_v4_open_req {
627 __u32 loc_addr;
628 __u32 rmt_addr;
629 struct ip_options *opt;
630};
631
632#if defined(CONFIG_IPV6) || defined (CONFIG_IPV6_MODULE)
633struct tcp_v6_open_req {
634 struct in6_addr loc_addr;
635 struct in6_addr rmt_addr;
636 struct sk_buff *pktopts;
637 int iif;
638};
639#endif
640
641/* this structure is too big */
642struct open_request {
643 struct open_request *dl_next; /* Must be first member! */
644 __u32 rcv_isn;
645 __u32 snt_isn;
646 __u16 rmt_port;
647 __u16 mss;
648 __u8 retrans;
649 __u8 __pad;
650 __u16 snd_wscale : 4,
651 rcv_wscale : 4,
652 tstamp_ok : 1,
653 sack_ok : 1,
654 wscale_ok : 1,
655 ecn_ok : 1,
656 acked : 1;
657 /* The following two fields can be easily recomputed I think -AK */
658 __u32 window_clamp; /* window clamp at creation time */
659 __u32 rcv_wnd; /* rcv_wnd offered first time */
660 __u32 ts_recent;
661 unsigned long expires;
662 struct or_calltable *class;
663 struct sock *sk;
664 union {
665 struct tcp_v4_open_req v4_req;
666#if defined(CONFIG_IPV6) || defined (CONFIG_IPV6_MODULE)
667 struct tcp_v6_open_req v6_req;
668#endif
669 } af;
670};
671
672/* SLAB cache for open requests. */
673extern kmem_cache_t *tcp_openreq_cachep;
674
675#define tcp_openreq_alloc() kmem_cache_alloc(tcp_openreq_cachep, SLAB_ATOMIC)
676#define tcp_openreq_fastfree(req) kmem_cache_free(tcp_openreq_cachep, req)
677
678static inline void tcp_openreq_free(struct open_request *req)
679{
680 req->class->destructor(req);
681 tcp_openreq_fastfree(req);
682}
683
684#if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
685#define TCP_INET_FAMILY(fam) ((fam) == AF_INET)
686#else
687#define TCP_INET_FAMILY(fam) 1
688#endif
689
690/*
691 * Pointers to address related TCP functions
692 * (i.e. things that depend on the address family)
693 */
694
695struct tcp_func {
696 int (*queue_xmit) (struct sk_buff *skb,
697 int ipfragok);
698
699 void (*send_check) (struct sock *sk,
700 struct tcphdr *th,
701 int len,
702 struct sk_buff *skb);
703
704 int (*rebuild_header) (struct sock *sk);
705
706 int (*conn_request) (struct sock *sk,
707 struct sk_buff *skb);
708
709 struct sock * (*syn_recv_sock) (struct sock *sk,
710 struct sk_buff *skb,
711 struct open_request *req,
712 struct dst_entry *dst);
713
714 int (*remember_stamp) (struct sock *sk);
715
716 __u16 net_header_len;
717
718 int (*setsockopt) (struct sock *sk,
719 int level,
720 int optname,
721 char __user *optval,
722 int optlen);
723
724 int (*getsockopt) (struct sock *sk,
725 int level,
726 int optname,
727 char __user *optval,
728 int __user *optlen);
729
730
731 void (*addr2sockaddr) (struct sock *sk,
732 struct sockaddr *);
733
734 int sockaddr_len;
735};
736
737/*
738 * The next routines deal with comparing 32 bit unsigned ints
739 * and worry about wraparound (automatic with unsigned arithmetic).
740 */
741
742static inline int before(__u32 seq1, __u32 seq2)
743{
744 return (__s32)(seq1-seq2) < 0;
745}
746
747static inline int after(__u32 seq1, __u32 seq2)
748{
749 return (__s32)(seq2-seq1) < 0;
750}
751
752
753/* is s2<=s1<=s3 ? */
754static inline int between(__u32 seq1, __u32 seq2, __u32 seq3)
755{
756 return seq3 - seq2 >= seq1 - seq2;
757}
758
759
760extern struct proto tcp_prot;
761
762DECLARE_SNMP_STAT(struct tcp_mib, tcp_statistics);
763#define TCP_INC_STATS(field) SNMP_INC_STATS(tcp_statistics, field)
764#define TCP_INC_STATS_BH(field) SNMP_INC_STATS_BH(tcp_statistics, field)
765#define TCP_INC_STATS_USER(field) SNMP_INC_STATS_USER(tcp_statistics, field)
766#define TCP_DEC_STATS(field) SNMP_DEC_STATS(tcp_statistics, field)
767#define TCP_ADD_STATS_BH(field, val) SNMP_ADD_STATS_BH(tcp_statistics, field, val)
768#define TCP_ADD_STATS_USER(field, val) SNMP_ADD_STATS_USER(tcp_statistics, field, val)
769
770extern void tcp_put_port(struct sock *sk);
771extern void tcp_inherit_port(struct sock *sk, struct sock *child);
772
773extern void tcp_v4_err(struct sk_buff *skb, u32);
774
775extern void tcp_shutdown (struct sock *sk, int how);
776
777extern int tcp_v4_rcv(struct sk_buff *skb);
778
779extern int tcp_v4_remember_stamp(struct sock *sk);
780
781extern int tcp_v4_tw_remember_stamp(struct tcp_tw_bucket *tw);
782
783extern int tcp_sendmsg(struct kiocb *iocb, struct sock *sk,
784 struct msghdr *msg, size_t size);
785extern ssize_t tcp_sendpage(struct socket *sock, struct page *page, int offset, size_t size, int flags);
786
787extern int tcp_ioctl(struct sock *sk,
788 int cmd,
789 unsigned long arg);
790
791extern int tcp_rcv_state_process(struct sock *sk,
792 struct sk_buff *skb,
793 struct tcphdr *th,
794 unsigned len);
795
796extern int tcp_rcv_established(struct sock *sk,
797 struct sk_buff *skb,
798 struct tcphdr *th,
799 unsigned len);
800
801extern void tcp_rcv_space_adjust(struct sock *sk);
802
803enum tcp_ack_state_t
804{
805 TCP_ACK_SCHED = 1,
806 TCP_ACK_TIMER = 2,
807 TCP_ACK_PUSHED= 4
808};
809
810static inline void tcp_schedule_ack(struct tcp_sock *tp)
811{
812 tp->ack.pending |= TCP_ACK_SCHED;
813}
814
815static inline int tcp_ack_scheduled(struct tcp_sock *tp)
816{
817 return tp->ack.pending&TCP_ACK_SCHED;
818}
819
820static __inline__ void tcp_dec_quickack_mode(struct tcp_sock *tp)
821{
822 if (tp->ack.quick && --tp->ack.quick == 0) {
823 /* Leaving quickack mode we deflate ATO. */
824 tp->ack.ato = TCP_ATO_MIN;
825 }
826}
827
828extern void tcp_enter_quickack_mode(struct tcp_sock *tp);
829
830static __inline__ void tcp_delack_init(struct tcp_sock *tp)
831{
832 memset(&tp->ack, 0, sizeof(tp->ack));
833}
834
835static inline void tcp_clear_options(struct tcp_options_received *rx_opt)
836{
837 rx_opt->tstamp_ok = rx_opt->sack_ok = rx_opt->wscale_ok = rx_opt->snd_wscale = 0;
838}
839
840enum tcp_tw_status
841{
842 TCP_TW_SUCCESS = 0,
843 TCP_TW_RST = 1,
844 TCP_TW_ACK = 2,
845 TCP_TW_SYN = 3
846};
847
848
849extern enum tcp_tw_status tcp_timewait_state_process(struct tcp_tw_bucket *tw,
850 struct sk_buff *skb,
851 struct tcphdr *th,
852 unsigned len);
853
854extern struct sock * tcp_check_req(struct sock *sk,struct sk_buff *skb,
855 struct open_request *req,
856 struct open_request **prev);
857extern int tcp_child_process(struct sock *parent,
858 struct sock *child,
859 struct sk_buff *skb);
860extern void tcp_enter_frto(struct sock *sk);
861extern void tcp_enter_loss(struct sock *sk, int how);
862extern void tcp_clear_retrans(struct tcp_sock *tp);
863extern void tcp_update_metrics(struct sock *sk);
864
865extern void tcp_close(struct sock *sk,
866 long timeout);
867extern struct sock * tcp_accept(struct sock *sk, int flags, int *err);
868extern unsigned int tcp_poll(struct file * file, struct socket *sock, struct poll_table_struct *wait);
869
870extern int tcp_getsockopt(struct sock *sk, int level,
871 int optname,
872 char __user *optval,
873 int __user *optlen);
874extern int tcp_setsockopt(struct sock *sk, int level,
875 int optname, char __user *optval,
876 int optlen);
877extern void tcp_set_keepalive(struct sock *sk, int val);
878extern int tcp_recvmsg(struct kiocb *iocb, struct sock *sk,
879 struct msghdr *msg,
880 size_t len, int nonblock,
881 int flags, int *addr_len);
882
883extern int tcp_listen_start(struct sock *sk);
884
885extern void tcp_parse_options(struct sk_buff *skb,
886 struct tcp_options_received *opt_rx,
887 int estab);
888
889/*
890 * TCP v4 functions exported for the inet6 API
891 */
892
893extern int tcp_v4_rebuild_header(struct sock *sk);
894
895extern int tcp_v4_build_header(struct sock *sk,
896 struct sk_buff *skb);
897
898extern void tcp_v4_send_check(struct sock *sk,
899 struct tcphdr *th, int len,
900 struct sk_buff *skb);
901
902extern int tcp_v4_conn_request(struct sock *sk,
903 struct sk_buff *skb);
904
905extern struct sock * tcp_create_openreq_child(struct sock *sk,
906 struct open_request *req,
907 struct sk_buff *skb);
908
909extern struct sock * tcp_v4_syn_recv_sock(struct sock *sk,
910 struct sk_buff *skb,
911 struct open_request *req,
912 struct dst_entry *dst);
913
914extern int tcp_v4_do_rcv(struct sock *sk,
915 struct sk_buff *skb);
916
917extern int tcp_v4_connect(struct sock *sk,
918 struct sockaddr *uaddr,
919 int addr_len);
920
921extern int tcp_connect(struct sock *sk);
922
923extern struct sk_buff * tcp_make_synack(struct sock *sk,
924 struct dst_entry *dst,
925 struct open_request *req);
926
927extern int tcp_disconnect(struct sock *sk, int flags);
928
929extern void tcp_unhash(struct sock *sk);
930
931extern int tcp_v4_hash_connecting(struct sock *sk);
932
933
934/* From syncookies.c */
935extern struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb,
936 struct ip_options *opt);
937extern __u32 cookie_v4_init_sequence(struct sock *sk, struct sk_buff *skb,
938 __u16 *mss);
939
940/* tcp_output.c */
941
942extern int tcp_write_xmit(struct sock *, int nonagle);
943extern int tcp_retransmit_skb(struct sock *, struct sk_buff *);
944extern void tcp_xmit_retransmit_queue(struct sock *);
945extern void tcp_simple_retransmit(struct sock *);
946extern int tcp_trim_head(struct sock *, struct sk_buff *, u32);
947
948extern void tcp_send_probe0(struct sock *);
949extern void tcp_send_partial(struct sock *);
950extern int tcp_write_wakeup(struct sock *);
951extern void tcp_send_fin(struct sock *sk);
952extern void tcp_send_active_reset(struct sock *sk, int priority);
953extern int tcp_send_synack(struct sock *);
954extern void tcp_push_one(struct sock *, unsigned mss_now);
955extern void tcp_send_ack(struct sock *sk);
956extern void tcp_send_delayed_ack(struct sock *sk);
957
958/* tcp_timer.c */
959extern void tcp_init_xmit_timers(struct sock *);
960extern void tcp_clear_xmit_timers(struct sock *);
961
962extern void tcp_delete_keepalive_timer(struct sock *);
963extern void tcp_reset_keepalive_timer(struct sock *, unsigned long);
964extern unsigned int tcp_sync_mss(struct sock *sk, u32 pmtu);
965extern unsigned int tcp_current_mss(struct sock *sk, int large);
966
967#ifdef TCP_DEBUG
968extern const char tcp_timer_bug_msg[];
969#endif
970
971/* tcp_diag.c */
972extern void tcp_get_info(struct sock *, struct tcp_info *);
973
974/* Read 'sendfile()'-style from a TCP socket */
975typedef int (*sk_read_actor_t)(read_descriptor_t *, struct sk_buff *,
976 unsigned int, size_t);
977extern int tcp_read_sock(struct sock *sk, read_descriptor_t *desc,
978 sk_read_actor_t recv_actor);
979
980static inline void tcp_clear_xmit_timer(struct sock *sk, int what)
981{
982 struct tcp_sock *tp = tcp_sk(sk);
983
984 switch (what) {
985 case TCP_TIME_RETRANS:
986 case TCP_TIME_PROBE0:
987 tp->pending = 0;
988
989#ifdef TCP_CLEAR_TIMERS
990 sk_stop_timer(sk, &tp->retransmit_timer);
991#endif
992 break;
993 case TCP_TIME_DACK:
994 tp->ack.blocked = 0;
995 tp->ack.pending = 0;
996
997#ifdef TCP_CLEAR_TIMERS
998 sk_stop_timer(sk, &tp->delack_timer);
999#endif
1000 break;
1001 default:
1002#ifdef TCP_DEBUG
1003 printk(tcp_timer_bug_msg);
1004#endif
1005 return;
1006 };
1007
1008}
1009
1010/*
1011 * Reset the retransmission timer
1012 */
1013static inline void tcp_reset_xmit_timer(struct sock *sk, int what, unsigned long when)
1014{
1015 struct tcp_sock *tp = tcp_sk(sk);
1016
1017 if (when > TCP_RTO_MAX) {
1018#ifdef TCP_DEBUG
1019 printk(KERN_DEBUG "reset_xmit_timer sk=%p %d when=0x%lx, caller=%p\n", sk, what, when, current_text_addr());
1020#endif
1021 when = TCP_RTO_MAX;
1022 }
1023
1024 switch (what) {
1025 case TCP_TIME_RETRANS:
1026 case TCP_TIME_PROBE0:
1027 tp->pending = what;
1028 tp->timeout = jiffies+when;
1029 sk_reset_timer(sk, &tp->retransmit_timer, tp->timeout);
1030 break;
1031
1032 case TCP_TIME_DACK:
1033 tp->ack.pending |= TCP_ACK_TIMER;
1034 tp->ack.timeout = jiffies+when;
1035 sk_reset_timer(sk, &tp->delack_timer, tp->ack.timeout);
1036 break;
1037
1038 default:
1039#ifdef TCP_DEBUG
1040 printk(tcp_timer_bug_msg);
1041#endif
1042 return;
1043 };
1044}
1045
1046/* Initialize RCV_MSS value.
1047 * RCV_MSS is an our guess about MSS used by the peer.
1048 * We haven't any direct information about the MSS.
1049 * It's better to underestimate the RCV_MSS rather than overestimate.
1050 * Overestimations make us ACKing less frequently than needed.
1051 * Underestimations are more easy to detect and fix by tcp_measure_rcv_mss().
1052 */
1053
1054static inline void tcp_initialize_rcv_mss(struct sock *sk)
1055{
1056 struct tcp_sock *tp = tcp_sk(sk);
1057 unsigned int hint = min(tp->advmss, tp->mss_cache_std);
1058
1059 hint = min(hint, tp->rcv_wnd/2);
1060 hint = min(hint, TCP_MIN_RCVMSS);
1061 hint = max(hint, TCP_MIN_MSS);
1062
1063 tp->ack.rcv_mss = hint;
1064}
1065
1066static __inline__ void __tcp_fast_path_on(struct tcp_sock *tp, u32 snd_wnd)
1067{
1068 tp->pred_flags = htonl((tp->tcp_header_len << 26) |
1069 ntohl(TCP_FLAG_ACK) |
1070 snd_wnd);
1071}
1072
1073static __inline__ void tcp_fast_path_on(struct tcp_sock *tp)
1074{
1075 __tcp_fast_path_on(tp, tp->snd_wnd >> tp->rx_opt.snd_wscale);
1076}
1077
1078static inline void tcp_fast_path_check(struct sock *sk, struct tcp_sock *tp)
1079{
1080 if (skb_queue_len(&tp->out_of_order_queue) == 0 &&
1081 tp->rcv_wnd &&
1082 atomic_read(&sk->sk_rmem_alloc) < sk->sk_rcvbuf &&
1083 !tp->urg_data)
1084 tcp_fast_path_on(tp);
1085}
1086
1087/* Compute the actual receive window we are currently advertising.
1088 * Rcv_nxt can be after the window if our peer push more data
1089 * than the offered window.
1090 */
1091static __inline__ u32 tcp_receive_window(const struct tcp_sock *tp)
1092{
1093 s32 win = tp->rcv_wup + tp->rcv_wnd - tp->rcv_nxt;
1094
1095 if (win < 0)
1096 win = 0;
1097 return (u32) win;
1098}
1099
1100/* Choose a new window, without checks for shrinking, and without
1101 * scaling applied to the result. The caller does these things
1102 * if necessary. This is a "raw" window selection.
1103 */
1104extern u32 __tcp_select_window(struct sock *sk);
1105
1106/* TCP timestamps are only 32-bits, this causes a slight
1107 * complication on 64-bit systems since we store a snapshot
1108 * of jiffies in the buffer control blocks below. We decidely
1109 * only use of the low 32-bits of jiffies and hide the ugly
1110 * casts with the following macro.
1111 */
1112#define tcp_time_stamp ((__u32)(jiffies))
1113
1114/* This is what the send packet queueing engine uses to pass
1115 * TCP per-packet control information to the transmission
1116 * code. We also store the host-order sequence numbers in
1117 * here too. This is 36 bytes on 32-bit architectures,
1118 * 40 bytes on 64-bit machines, if this grows please adjust
1119 * skbuff.h:skbuff->cb[xxx] size appropriately.
1120 */
1121struct tcp_skb_cb {
1122 union {
1123 struct inet_skb_parm h4;
1124#if defined(CONFIG_IPV6) || defined (CONFIG_IPV6_MODULE)
1125 struct inet6_skb_parm h6;
1126#endif
1127 } header; /* For incoming frames */
1128 __u32 seq; /* Starting sequence number */
1129 __u32 end_seq; /* SEQ + FIN + SYN + datalen */
1130 __u32 when; /* used to compute rtt's */
1131 __u8 flags; /* TCP header flags. */
1132
1133 /* NOTE: These must match up to the flags byte in a
1134 * real TCP header.
1135 */
1136#define TCPCB_FLAG_FIN 0x01
1137#define TCPCB_FLAG_SYN 0x02
1138#define TCPCB_FLAG_RST 0x04
1139#define TCPCB_FLAG_PSH 0x08
1140#define TCPCB_FLAG_ACK 0x10
1141#define TCPCB_FLAG_URG 0x20
1142#define TCPCB_FLAG_ECE 0x40
1143#define TCPCB_FLAG_CWR 0x80
1144
1145 __u8 sacked; /* State flags for SACK/FACK. */
1146#define TCPCB_SACKED_ACKED 0x01 /* SKB ACK'd by a SACK block */
1147#define TCPCB_SACKED_RETRANS 0x02 /* SKB retransmitted */
1148#define TCPCB_LOST 0x04 /* SKB is lost */
1149#define TCPCB_TAGBITS 0x07 /* All tag bits */
1150
1151#define TCPCB_EVER_RETRANS 0x80 /* Ever retransmitted frame */
1152#define TCPCB_RETRANS (TCPCB_SACKED_RETRANS|TCPCB_EVER_RETRANS)
1153
1154#define TCPCB_URG 0x20 /* Urgent pointer advenced here */
1155
1156#define TCPCB_AT_TAIL (TCPCB_URG)
1157
1158 __u16 urg_ptr; /* Valid w/URG flags is set. */
1159 __u32 ack_seq; /* Sequence number ACK'd */
1160};
1161
1162#define TCP_SKB_CB(__skb) ((struct tcp_skb_cb *)&((__skb)->cb[0]))
1163
1164#include <net/tcp_ecn.h>
1165
1166/* Due to TSO, an SKB can be composed of multiple actual
1167 * packets. To keep these tracked properly, we use this.
1168 */
1169static inline int tcp_skb_pcount(const struct sk_buff *skb)
1170{
1171 return skb_shinfo(skb)->tso_segs;
1172}
1173
1174/* This is valid iff tcp_skb_pcount() > 1. */
1175static inline int tcp_skb_mss(const struct sk_buff *skb)
1176{
1177 return skb_shinfo(skb)->tso_size;
1178}
1179
1180static inline void tcp_dec_pcount_approx(__u32 *count,
1181 const struct sk_buff *skb)
1182{
1183 if (*count) {
1184 *count -= tcp_skb_pcount(skb);
1185 if ((int)*count < 0)
1186 *count = 0;
1187 }
1188}
1189
1190static inline void tcp_packets_out_inc(struct sock *sk,
1191 struct tcp_sock *tp,
1192 const struct sk_buff *skb)
1193{
1194 int orig = tp->packets_out;
1195
1196 tp->packets_out += tcp_skb_pcount(skb);
1197 if (!orig)
1198 tcp_reset_xmit_timer(sk, TCP_TIME_RETRANS, tp->rto);
1199}
1200
1201static inline void tcp_packets_out_dec(struct tcp_sock *tp,
1202 const struct sk_buff *skb)
1203{
1204 tp->packets_out -= tcp_skb_pcount(skb);
1205}
1206
1207/* This determines how many packets are "in the network" to the best
1208 * of our knowledge. In many cases it is conservative, but where
1209 * detailed information is available from the receiver (via SACK
1210 * blocks etc.) we can make more aggressive calculations.
1211 *
1212 * Use this for decisions involving congestion control, use just
1213 * tp->packets_out to determine if the send queue is empty or not.
1214 *
1215 * Read this equation as:
1216 *
1217 * "Packets sent once on transmission queue" MINUS
1218 * "Packets left network, but not honestly ACKed yet" PLUS
1219 * "Packets fast retransmitted"
1220 */
1221static __inline__ unsigned int tcp_packets_in_flight(const struct tcp_sock *tp)
1222{
1223 return (tp->packets_out - tp->left_out + tp->retrans_out);
1224}
1225
1226/*
1227 * Which congestion algorithim is in use on the connection.
1228 */
1229#define tcp_is_vegas(__tp) ((__tp)->adv_cong == TCP_VEGAS)
1230#define tcp_is_westwood(__tp) ((__tp)->adv_cong == TCP_WESTWOOD)
1231#define tcp_is_bic(__tp) ((__tp)->adv_cong == TCP_BIC)
1232
1233/* Recalculate snd_ssthresh, we want to set it to:
1234 *
1235 * Reno:
1236 * one half the current congestion window, but no
1237 * less than two segments
1238 *
1239 * BIC:
1240 * behave like Reno until low_window is reached,
1241 * then increase congestion window slowly
1242 */
1243static inline __u32 tcp_recalc_ssthresh(struct tcp_sock *tp)
1244{
1245 if (tcp_is_bic(tp)) {
1246 if (sysctl_tcp_bic_fast_convergence &&
1247 tp->snd_cwnd < tp->bictcp.last_max_cwnd)
1248 tp->bictcp.last_max_cwnd = (tp->snd_cwnd *
1249 (BICTCP_BETA_SCALE
1250 + sysctl_tcp_bic_beta))
1251 / (2 * BICTCP_BETA_SCALE);
1252 else
1253 tp->bictcp.last_max_cwnd = tp->snd_cwnd;
1254
1255 if (tp->snd_cwnd > sysctl_tcp_bic_low_window)
1256 return max((tp->snd_cwnd * sysctl_tcp_bic_beta)
1257 / BICTCP_BETA_SCALE, 2U);
1258 }
1259
1260 return max(tp->snd_cwnd >> 1U, 2U);
1261}
1262
1263/* Stop taking Vegas samples for now. */
1264#define tcp_vegas_disable(__tp) ((__tp)->vegas.doing_vegas_now = 0)
1265
1266static inline void tcp_vegas_enable(struct tcp_sock *tp)
1267{
1268 /* There are several situations when we must "re-start" Vegas:
1269 *
1270 * o when a connection is established
1271 * o after an RTO
1272 * o after fast recovery
1273 * o when we send a packet and there is no outstanding
1274 * unacknowledged data (restarting an idle connection)
1275 *
1276 * In these circumstances we cannot do a Vegas calculation at the
1277 * end of the first RTT, because any calculation we do is using
1278 * stale info -- both the saved cwnd and congestion feedback are
1279 * stale.
1280 *
1281 * Instead we must wait until the completion of an RTT during
1282 * which we actually receive ACKs.
1283 */
1284
1285 /* Begin taking Vegas samples next time we send something. */
1286 tp->vegas.doing_vegas_now = 1;
1287
1288 /* Set the beginning of the next send window. */
1289 tp->vegas.beg_snd_nxt = tp->snd_nxt;
1290
1291 tp->vegas.cntRTT = 0;
1292 tp->vegas.minRTT = 0x7fffffff;
1293}
1294
1295/* Should we be taking Vegas samples right now? */
1296#define tcp_vegas_enabled(__tp) ((__tp)->vegas.doing_vegas_now)
1297
1298extern void tcp_ca_init(struct tcp_sock *tp);
1299
1300static inline void tcp_set_ca_state(struct tcp_sock *tp, u8 ca_state)
1301{
1302 if (tcp_is_vegas(tp)) {
1303 if (ca_state == TCP_CA_Open)
1304 tcp_vegas_enable(tp);
1305 else
1306 tcp_vegas_disable(tp);
1307 }
1308 tp->ca_state = ca_state;
1309}
1310
1311/* If cwnd > ssthresh, we may raise ssthresh to be half-way to cwnd.
1312 * The exception is rate halving phase, when cwnd is decreasing towards
1313 * ssthresh.
1314 */
1315static inline __u32 tcp_current_ssthresh(struct tcp_sock *tp)
1316{
1317 if ((1<<tp->ca_state)&(TCPF_CA_CWR|TCPF_CA_Recovery))
1318 return tp->snd_ssthresh;
1319 else
1320 return max(tp->snd_ssthresh,
1321 ((tp->snd_cwnd >> 1) +
1322 (tp->snd_cwnd >> 2)));
1323}
1324
1325static inline void tcp_sync_left_out(struct tcp_sock *tp)
1326{
1327 if (tp->rx_opt.sack_ok &&
1328 (tp->sacked_out >= tp->packets_out - tp->lost_out))
1329 tp->sacked_out = tp->packets_out - tp->lost_out;
1330 tp->left_out = tp->sacked_out + tp->lost_out;
1331}
1332
1333extern void tcp_cwnd_application_limited(struct sock *sk);
1334
1335/* Congestion window validation. (RFC2861) */
1336
1337static inline void tcp_cwnd_validate(struct sock *sk, struct tcp_sock *tp)
1338{
1339 __u32 packets_out = tp->packets_out;
1340
1341 if (packets_out >= tp->snd_cwnd) {
1342 /* Network is feed fully. */
1343 tp->snd_cwnd_used = 0;
1344 tp->snd_cwnd_stamp = tcp_time_stamp;
1345 } else {
1346 /* Network starves. */
1347 if (tp->packets_out > tp->snd_cwnd_used)
1348 tp->snd_cwnd_used = tp->packets_out;
1349
1350 if ((s32)(tcp_time_stamp - tp->snd_cwnd_stamp) >= tp->rto)
1351 tcp_cwnd_application_limited(sk);
1352 }
1353}
1354
1355/* Set slow start threshould and cwnd not falling to slow start */
1356static inline void __tcp_enter_cwr(struct tcp_sock *tp)
1357{
1358 tp->undo_marker = 0;
1359 tp->snd_ssthresh = tcp_recalc_ssthresh(tp);
1360 tp->snd_cwnd = min(tp->snd_cwnd,
1361 tcp_packets_in_flight(tp) + 1U);
1362 tp->snd_cwnd_cnt = 0;
1363 tp->high_seq = tp->snd_nxt;
1364 tp->snd_cwnd_stamp = tcp_time_stamp;
1365 TCP_ECN_queue_cwr(tp);
1366}
1367
1368static inline void tcp_enter_cwr(struct tcp_sock *tp)
1369{
1370 tp->prior_ssthresh = 0;
1371 if (tp->ca_state < TCP_CA_CWR) {
1372 __tcp_enter_cwr(tp);
1373 tcp_set_ca_state(tp, TCP_CA_CWR);
1374 }
1375}
1376
1377extern __u32 tcp_init_cwnd(struct tcp_sock *tp, struct dst_entry *dst);
1378
1379/* Slow start with delack produces 3 packets of burst, so that
1380 * it is safe "de facto".
1381 */
1382static __inline__ __u32 tcp_max_burst(const struct tcp_sock *tp)
1383{
1384 return 3;
1385}
1386
1387static __inline__ int tcp_minshall_check(const struct tcp_sock *tp)
1388{
1389 return after(tp->snd_sml,tp->snd_una) &&
1390 !after(tp->snd_sml, tp->snd_nxt);
1391}
1392
1393static __inline__ void tcp_minshall_update(struct tcp_sock *tp, int mss,
1394 const struct sk_buff *skb)
1395{
1396 if (skb->len < mss)
1397 tp->snd_sml = TCP_SKB_CB(skb)->end_seq;
1398}
1399
1400/* Return 0, if packet can be sent now without violation Nagle's rules:
1401 1. It is full sized.
1402 2. Or it contains FIN.
1403 3. Or TCP_NODELAY was set.
1404 4. Or TCP_CORK is not set, and all sent packets are ACKed.
1405 With Minshall's modification: all sent small packets are ACKed.
1406 */
1407
1408static __inline__ int
1409tcp_nagle_check(const struct tcp_sock *tp, const struct sk_buff *skb,
1410 unsigned mss_now, int nonagle)
1411{
1412 return (skb->len < mss_now &&
1413 !(TCP_SKB_CB(skb)->flags & TCPCB_FLAG_FIN) &&
1414 ((nonagle&TCP_NAGLE_CORK) ||
1415 (!nonagle &&
1416 tp->packets_out &&
1417 tcp_minshall_check(tp))));
1418}
1419
1420extern void tcp_set_skb_tso_segs(struct sk_buff *, unsigned int);
1421
1422/* This checks if the data bearing packet SKB (usually sk->sk_send_head)
1423 * should be put on the wire right now.
1424 */
1425static __inline__ int tcp_snd_test(const struct tcp_sock *tp,
1426 struct sk_buff *skb,
1427 unsigned cur_mss, int nonagle)
1428{
1429 int pkts = tcp_skb_pcount(skb);
1430
1431 if (!pkts) {
1432 tcp_set_skb_tso_segs(skb, tp->mss_cache_std);
1433 pkts = tcp_skb_pcount(skb);
1434 }
1435
1436 /* RFC 1122 - section 4.2.3.4
1437 *
1438 * We must queue if
1439 *
1440 * a) The right edge of this frame exceeds the window
1441 * b) There are packets in flight and we have a small segment
1442 * [SWS avoidance and Nagle algorithm]
1443 * (part of SWS is done on packetization)
1444 * Minshall version sounds: there are no _small_
1445 * segments in flight. (tcp_nagle_check)
1446 * c) We have too many packets 'in flight'
1447 *
1448 * Don't use the nagle rule for urgent data (or
1449 * for the final FIN -DaveM).
1450 *
1451 * Also, Nagle rule does not apply to frames, which
1452 * sit in the middle of queue (they have no chances
1453 * to get new data) and if room at tail of skb is
1454 * not enough to save something seriously (<32 for now).
1455 */
1456
1457 /* Don't be strict about the congestion window for the
1458 * final FIN frame. -DaveM
1459 */
1460 return (((nonagle&TCP_NAGLE_PUSH) || tp->urg_mode
1461 || !tcp_nagle_check(tp, skb, cur_mss, nonagle)) &&
1462 (((tcp_packets_in_flight(tp) + (pkts-1)) < tp->snd_cwnd) ||
1463 (TCP_SKB_CB(skb)->flags & TCPCB_FLAG_FIN)) &&
1464 !after(TCP_SKB_CB(skb)->end_seq, tp->snd_una + tp->snd_wnd));
1465}
1466
1467static __inline__ void tcp_check_probe_timer(struct sock *sk, struct tcp_sock *tp)
1468{
1469 if (!tp->packets_out && !tp->pending)
1470 tcp_reset_xmit_timer(sk, TCP_TIME_PROBE0, tp->rto);
1471}
1472
1473static __inline__ int tcp_skb_is_last(const struct sock *sk,
1474 const struct sk_buff *skb)
1475{
1476 return skb->next == (struct sk_buff *)&sk->sk_write_queue;
1477}
1478
1479/* Push out any pending frames which were held back due to
1480 * TCP_CORK or attempt at coalescing tiny packets.
1481 * The socket must be locked by the caller.
1482 */
1483static __inline__ void __tcp_push_pending_frames(struct sock *sk,
1484 struct tcp_sock *tp,
1485 unsigned cur_mss,
1486 int nonagle)
1487{
1488 struct sk_buff *skb = sk->sk_send_head;
1489
1490 if (skb) {
1491 if (!tcp_skb_is_last(sk, skb))
1492 nonagle = TCP_NAGLE_PUSH;
1493 if (!tcp_snd_test(tp, skb, cur_mss, nonagle) ||
1494 tcp_write_xmit(sk, nonagle))
1495 tcp_check_probe_timer(sk, tp);
1496 }
1497 tcp_cwnd_validate(sk, tp);
1498}
1499
1500static __inline__ void tcp_push_pending_frames(struct sock *sk,
1501 struct tcp_sock *tp)
1502{
1503 __tcp_push_pending_frames(sk, tp, tcp_current_mss(sk, 1), tp->nonagle);
1504}
1505
1506static __inline__ int tcp_may_send_now(struct sock *sk, struct tcp_sock *tp)
1507{
1508 struct sk_buff *skb = sk->sk_send_head;
1509
1510 return (skb &&
1511 tcp_snd_test(tp, skb, tcp_current_mss(sk, 1),
1512 tcp_skb_is_last(sk, skb) ? TCP_NAGLE_PUSH : tp->nonagle));
1513}
1514
1515static __inline__ void tcp_init_wl(struct tcp_sock *tp, u32 ack, u32 seq)
1516{
1517 tp->snd_wl1 = seq;
1518}
1519
1520static __inline__ void tcp_update_wl(struct tcp_sock *tp, u32 ack, u32 seq)
1521{
1522 tp->snd_wl1 = seq;
1523}
1524
1525extern void tcp_destroy_sock(struct sock *sk);
1526
1527
1528/*
1529 * Calculate(/check) TCP checksum
1530 */
1531static __inline__ u16 tcp_v4_check(struct tcphdr *th, int len,
1532 unsigned long saddr, unsigned long daddr,
1533 unsigned long base)
1534{
1535 return csum_tcpudp_magic(saddr,daddr,len,IPPROTO_TCP,base);
1536}
1537
1538static __inline__ int __tcp_checksum_complete(struct sk_buff *skb)
1539{
1540 return (unsigned short)csum_fold(skb_checksum(skb, 0, skb->len, skb->csum));
1541}
1542
1543static __inline__ int tcp_checksum_complete(struct sk_buff *skb)
1544{
1545 return skb->ip_summed != CHECKSUM_UNNECESSARY &&
1546 __tcp_checksum_complete(skb);
1547}
1548
1549/* Prequeue for VJ style copy to user, combined with checksumming. */
1550
1551static __inline__ void tcp_prequeue_init(struct tcp_sock *tp)
1552{
1553 tp->ucopy.task = NULL;
1554 tp->ucopy.len = 0;
1555 tp->ucopy.memory = 0;
1556 skb_queue_head_init(&tp->ucopy.prequeue);
1557}
1558
1559/* Packet is added to VJ-style prequeue for processing in process
1560 * context, if a reader task is waiting. Apparently, this exciting
1561 * idea (VJ's mail "Re: query about TCP header on tcp-ip" of 07 Sep 93)
1562 * failed somewhere. Latency? Burstiness? Well, at least now we will
1563 * see, why it failed. 8)8) --ANK
1564 *
1565 * NOTE: is this not too big to inline?
1566 */
1567static __inline__ int tcp_prequeue(struct sock *sk, struct sk_buff *skb)
1568{
1569 struct tcp_sock *tp = tcp_sk(sk);
1570
1571 if (!sysctl_tcp_low_latency && tp->ucopy.task) {
1572 __skb_queue_tail(&tp->ucopy.prequeue, skb);
1573 tp->ucopy.memory += skb->truesize;
1574 if (tp->ucopy.memory > sk->sk_rcvbuf) {
1575 struct sk_buff *skb1;
1576
1577 BUG_ON(sock_owned_by_user(sk));
1578
1579 while ((skb1 = __skb_dequeue(&tp->ucopy.prequeue)) != NULL) {
1580 sk->sk_backlog_rcv(sk, skb1);
1581 NET_INC_STATS_BH(LINUX_MIB_TCPPREQUEUEDROPPED);
1582 }
1583
1584 tp->ucopy.memory = 0;
1585 } else if (skb_queue_len(&tp->ucopy.prequeue) == 1) {
1586 wake_up_interruptible(sk->sk_sleep);
1587 if (!tcp_ack_scheduled(tp))
1588 tcp_reset_xmit_timer(sk, TCP_TIME_DACK, (3*TCP_RTO_MIN)/4);
1589 }
1590 return 1;
1591 }
1592 return 0;
1593}
1594
1595
1596#undef STATE_TRACE
1597
1598#ifdef STATE_TRACE
1599static const char *statename[]={
1600 "Unused","Established","Syn Sent","Syn Recv",
1601 "Fin Wait 1","Fin Wait 2","Time Wait", "Close",
1602 "Close Wait","Last ACK","Listen","Closing"
1603};
1604#endif
1605
1606static __inline__ void tcp_set_state(struct sock *sk, int state)
1607{
1608 int oldstate = sk->sk_state;
1609
1610 switch (state) {
1611 case TCP_ESTABLISHED:
1612 if (oldstate != TCP_ESTABLISHED)
1613 TCP_INC_STATS(TCP_MIB_CURRESTAB);
1614 break;
1615
1616 case TCP_CLOSE:
1617 if (oldstate == TCP_CLOSE_WAIT || oldstate == TCP_ESTABLISHED)
1618 TCP_INC_STATS(TCP_MIB_ESTABRESETS);
1619
1620 sk->sk_prot->unhash(sk);
1621 if (tcp_sk(sk)->bind_hash &&
1622 !(sk->sk_userlocks & SOCK_BINDPORT_LOCK))
1623 tcp_put_port(sk);
1624 /* fall through */
1625 default:
1626 if (oldstate==TCP_ESTABLISHED)
1627 TCP_DEC_STATS(TCP_MIB_CURRESTAB);
1628 }
1629
1630 /* Change state AFTER socket is unhashed to avoid closed
1631 * socket sitting in hash tables.
1632 */
1633 sk->sk_state = state;
1634
1635#ifdef STATE_TRACE
1636 SOCK_DEBUG(sk, "TCP sk=%p, State %s -> %s\n",sk, statename[oldstate],statename[state]);
1637#endif
1638}
1639
1640static __inline__ void tcp_done(struct sock *sk)
1641{
1642 tcp_set_state(sk, TCP_CLOSE);
1643 tcp_clear_xmit_timers(sk);
1644
1645 sk->sk_shutdown = SHUTDOWN_MASK;
1646
1647 if (!sock_flag(sk, SOCK_DEAD))
1648 sk->sk_state_change(sk);
1649 else
1650 tcp_destroy_sock(sk);
1651}
1652
1653static __inline__ void tcp_sack_reset(struct tcp_options_received *rx_opt)
1654{
1655 rx_opt->dsack = 0;
1656 rx_opt->eff_sacks = 0;
1657 rx_opt->num_sacks = 0;
1658}
1659
1660static __inline__ void tcp_build_and_update_options(__u32 *ptr, struct tcp_sock *tp, __u32 tstamp)
1661{
1662 if (tp->rx_opt.tstamp_ok) {
1663 *ptr++ = __constant_htonl((TCPOPT_NOP << 24) |
1664 (TCPOPT_NOP << 16) |
1665 (TCPOPT_TIMESTAMP << 8) |
1666 TCPOLEN_TIMESTAMP);
1667 *ptr++ = htonl(tstamp);
1668 *ptr++ = htonl(tp->rx_opt.ts_recent);
1669 }
1670 if (tp->rx_opt.eff_sacks) {
1671 struct tcp_sack_block *sp = tp->rx_opt.dsack ? tp->duplicate_sack : tp->selective_acks;
1672 int this_sack;
1673
1674 *ptr++ = __constant_htonl((TCPOPT_NOP << 24) |
1675 (TCPOPT_NOP << 16) |
1676 (TCPOPT_SACK << 8) |
1677 (TCPOLEN_SACK_BASE +
1678 (tp->rx_opt.eff_sacks * TCPOLEN_SACK_PERBLOCK)));
1679 for(this_sack = 0; this_sack < tp->rx_opt.eff_sacks; this_sack++) {
1680 *ptr++ = htonl(sp[this_sack].start_seq);
1681 *ptr++ = htonl(sp[this_sack].end_seq);
1682 }
1683 if (tp->rx_opt.dsack) {
1684 tp->rx_opt.dsack = 0;
1685 tp->rx_opt.eff_sacks--;
1686 }
1687 }
1688}
1689
1690/* Construct a tcp options header for a SYN or SYN_ACK packet.
1691 * If this is every changed make sure to change the definition of
1692 * MAX_SYN_SIZE to match the new maximum number of options that you
1693 * can generate.
1694 */
1695static inline void tcp_syn_build_options(__u32 *ptr, int mss, int ts, int sack,
1696 int offer_wscale, int wscale, __u32 tstamp, __u32 ts_recent)
1697{
1698 /* We always get an MSS option.
1699 * The option bytes which will be seen in normal data
1700 * packets should timestamps be used, must be in the MSS
1701 * advertised. But we subtract them from tp->mss_cache so
1702 * that calculations in tcp_sendmsg are simpler etc.
1703 * So account for this fact here if necessary. If we
1704 * don't do this correctly, as a receiver we won't
1705 * recognize data packets as being full sized when we
1706 * should, and thus we won't abide by the delayed ACK
1707 * rules correctly.
1708 * SACKs don't matter, we never delay an ACK when we
1709 * have any of those going out.
1710 */
1711 *ptr++ = htonl((TCPOPT_MSS << 24) | (TCPOLEN_MSS << 16) | mss);
1712 if (ts) {
1713 if(sack)
1714 *ptr++ = __constant_htonl((TCPOPT_SACK_PERM << 24) | (TCPOLEN_SACK_PERM << 16) |
1715 (TCPOPT_TIMESTAMP << 8) | TCPOLEN_TIMESTAMP);
1716 else
1717 *ptr++ = __constant_htonl((TCPOPT_NOP << 24) | (TCPOPT_NOP << 16) |
1718 (TCPOPT_TIMESTAMP << 8) | TCPOLEN_TIMESTAMP);
1719 *ptr++ = htonl(tstamp); /* TSVAL */
1720 *ptr++ = htonl(ts_recent); /* TSECR */
1721 } else if(sack)
1722 *ptr++ = __constant_htonl((TCPOPT_NOP << 24) | (TCPOPT_NOP << 16) |
1723 (TCPOPT_SACK_PERM << 8) | TCPOLEN_SACK_PERM);
1724 if (offer_wscale)
1725 *ptr++ = htonl((TCPOPT_NOP << 24) | (TCPOPT_WINDOW << 16) | (TCPOLEN_WINDOW << 8) | (wscale));
1726}
1727
1728/* Determine a window scaling and initial window to offer. */
1729extern void tcp_select_initial_window(int __space, __u32 mss,
1730 __u32 *rcv_wnd, __u32 *window_clamp,
1731 int wscale_ok, __u8 *rcv_wscale);
1732
1733static inline int tcp_win_from_space(int space)
1734{
1735 return sysctl_tcp_adv_win_scale<=0 ?
1736 (space>>(-sysctl_tcp_adv_win_scale)) :
1737 space - (space>>sysctl_tcp_adv_win_scale);
1738}
1739
1740/* Note: caller must be prepared to deal with negative returns */
1741static inline int tcp_space(const struct sock *sk)
1742{
1743 return tcp_win_from_space(sk->sk_rcvbuf -
1744 atomic_read(&sk->sk_rmem_alloc));
1745}
1746
1747static inline int tcp_full_space(const struct sock *sk)
1748{
1749 return tcp_win_from_space(sk->sk_rcvbuf);
1750}
1751
1752static inline void tcp_acceptq_queue(struct sock *sk, struct open_request *req,
1753 struct sock *child)
1754{
1755 struct tcp_sock *tp = tcp_sk(sk);
1756
1757 req->sk = child;
1758 sk_acceptq_added(sk);
1759
1760 if (!tp->accept_queue_tail) {
1761 tp->accept_queue = req;
1762 } else {
1763 tp->accept_queue_tail->dl_next = req;
1764 }
1765 tp->accept_queue_tail = req;
1766 req->dl_next = NULL;
1767}
1768
1769struct tcp_listen_opt
1770{
1771 u8 max_qlen_log; /* log_2 of maximal queued SYNs */
1772 int qlen;
1773 int qlen_young;
1774 int clock_hand;
1775 u32 hash_rnd;
1776 struct open_request *syn_table[TCP_SYNQ_HSIZE];
1777};
1778
1779static inline void
1780tcp_synq_removed(struct sock *sk, struct open_request *req)
1781{
1782 struct tcp_listen_opt *lopt = tcp_sk(sk)->listen_opt;
1783
1784 if (--lopt->qlen == 0)
1785 tcp_delete_keepalive_timer(sk);
1786 if (req->retrans == 0)
1787 lopt->qlen_young--;
1788}
1789
1790static inline void tcp_synq_added(struct sock *sk)
1791{
1792 struct tcp_listen_opt *lopt = tcp_sk(sk)->listen_opt;
1793
1794 if (lopt->qlen++ == 0)
1795 tcp_reset_keepalive_timer(sk, TCP_TIMEOUT_INIT);
1796 lopt->qlen_young++;
1797}
1798
1799static inline int tcp_synq_len(struct sock *sk)
1800{
1801 return tcp_sk(sk)->listen_opt->qlen;
1802}
1803
1804static inline int tcp_synq_young(struct sock *sk)
1805{
1806 return tcp_sk(sk)->listen_opt->qlen_young;
1807}
1808
1809static inline int tcp_synq_is_full(struct sock *sk)
1810{
1811 return tcp_synq_len(sk) >> tcp_sk(sk)->listen_opt->max_qlen_log;
1812}
1813
1814static inline void tcp_synq_unlink(struct tcp_sock *tp, struct open_request *req,
1815 struct open_request **prev)
1816{
1817 write_lock(&tp->syn_wait_lock);
1818 *prev = req->dl_next;
1819 write_unlock(&tp->syn_wait_lock);
1820}
1821
1822static inline void tcp_synq_drop(struct sock *sk, struct open_request *req,
1823 struct open_request **prev)
1824{
1825 tcp_synq_unlink(tcp_sk(sk), req, prev);
1826 tcp_synq_removed(sk, req);
1827 tcp_openreq_free(req);
1828}
1829
1830static __inline__ void tcp_openreq_init(struct open_request *req,
1831 struct tcp_options_received *rx_opt,
1832 struct sk_buff *skb)
1833{
1834 req->rcv_wnd = 0; /* So that tcp_send_synack() knows! */
1835 req->rcv_isn = TCP_SKB_CB(skb)->seq;
1836 req->mss = rx_opt->mss_clamp;
1837 req->ts_recent = rx_opt->saw_tstamp ? rx_opt->rcv_tsval : 0;
1838 req->tstamp_ok = rx_opt->tstamp_ok;
1839 req->sack_ok = rx_opt->sack_ok;
1840 req->snd_wscale = rx_opt->snd_wscale;
1841 req->wscale_ok = rx_opt->wscale_ok;
1842 req->acked = 0;
1843 req->ecn_ok = 0;
1844 req->rmt_port = skb->h.th->source;
1845}
1846
1847extern void tcp_enter_memory_pressure(void);
1848
1849extern void tcp_listen_wlock(void);
1850
1851/* - We may sleep inside this lock.
1852 * - If sleeping is not required (or called from BH),
1853 * use plain read_(un)lock(&tcp_lhash_lock).
1854 */
1855
1856static inline void tcp_listen_lock(void)
1857{
1858 /* read_lock synchronizes to candidates to writers */
1859 read_lock(&tcp_lhash_lock);
1860 atomic_inc(&tcp_lhash_users);
1861 read_unlock(&tcp_lhash_lock);
1862}
1863
1864static inline void tcp_listen_unlock(void)
1865{
1866 if (atomic_dec_and_test(&tcp_lhash_users))
1867 wake_up(&tcp_lhash_wait);
1868}
1869
1870static inline int keepalive_intvl_when(const struct tcp_sock *tp)
1871{
1872 return tp->keepalive_intvl ? : sysctl_tcp_keepalive_intvl;
1873}
1874
1875static inline int keepalive_time_when(const struct tcp_sock *tp)
1876{
1877 return tp->keepalive_time ? : sysctl_tcp_keepalive_time;
1878}
1879
1880static inline int tcp_fin_time(const struct tcp_sock *tp)
1881{
1882 int fin_timeout = tp->linger2 ? : sysctl_tcp_fin_timeout;
1883
1884 if (fin_timeout < (tp->rto<<2) - (tp->rto>>1))
1885 fin_timeout = (tp->rto<<2) - (tp->rto>>1);
1886
1887 return fin_timeout;
1888}
1889
1890static inline int tcp_paws_check(const struct tcp_options_received *rx_opt, int rst)
1891{
1892 if ((s32)(rx_opt->rcv_tsval - rx_opt->ts_recent) >= 0)
1893 return 0;
1894 if (xtime.tv_sec >= rx_opt->ts_recent_stamp + TCP_PAWS_24DAYS)
1895 return 0;
1896
1897 /* RST segments are not recommended to carry timestamp,
1898 and, if they do, it is recommended to ignore PAWS because
1899 "their cleanup function should take precedence over timestamps."
1900 Certainly, it is mistake. It is necessary to understand the reasons
1901 of this constraint to relax it: if peer reboots, clock may go
1902 out-of-sync and half-open connections will not be reset.
1903 Actually, the problem would be not existing if all
1904 the implementations followed draft about maintaining clock
1905 via reboots. Linux-2.2 DOES NOT!
1906
1907 However, we can relax time bounds for RST segments to MSL.
1908 */
1909 if (rst && xtime.tv_sec >= rx_opt->ts_recent_stamp + TCP_PAWS_MSL)
1910 return 0;
1911 return 1;
1912}
1913
1914static inline void tcp_v4_setup_caps(struct sock *sk, struct dst_entry *dst)
1915{
1916 sk->sk_route_caps = dst->dev->features;
1917 if (sk->sk_route_caps & NETIF_F_TSO) {
1918 if (sock_flag(sk, SOCK_NO_LARGESEND) || dst->header_len)
1919 sk->sk_route_caps &= ~NETIF_F_TSO;
1920 }
1921}
1922
1923#define TCP_CHECK_TIMER(sk) do { } while (0)
1924
1925static inline int tcp_use_frto(const struct sock *sk)
1926{
1927 const struct tcp_sock *tp = tcp_sk(sk);
1928
1929 /* F-RTO must be activated in sysctl and there must be some
1930 * unsent new data, and the advertised window should allow
1931 * sending it.
1932 */
1933 return (sysctl_tcp_frto && sk->sk_send_head &&
1934 !after(TCP_SKB_CB(sk->sk_send_head)->end_seq,
1935 tp->snd_una + tp->snd_wnd));
1936}
1937
1938static inline void tcp_mib_init(void)
1939{
1940 /* See RFC 2012 */
1941 TCP_ADD_STATS_USER(TCP_MIB_RTOALGORITHM, 1);
1942 TCP_ADD_STATS_USER(TCP_MIB_RTOMIN, TCP_RTO_MIN*1000/HZ);
1943 TCP_ADD_STATS_USER(TCP_MIB_RTOMAX, TCP_RTO_MAX*1000/HZ);
1944 TCP_ADD_STATS_USER(TCP_MIB_MAXCONN, -1);
1945}
1946
1947/* /proc */
1948enum tcp_seq_states {
1949 TCP_SEQ_STATE_LISTENING,
1950 TCP_SEQ_STATE_OPENREQ,
1951 TCP_SEQ_STATE_ESTABLISHED,
1952 TCP_SEQ_STATE_TIME_WAIT,
1953};
1954
1955struct tcp_seq_afinfo {
1956 struct module *owner;
1957 char *name;
1958 sa_family_t family;
1959 int (*seq_show) (struct seq_file *m, void *v);
1960 struct file_operations *seq_fops;
1961};
1962
1963struct tcp_iter_state {
1964 sa_family_t family;
1965 enum tcp_seq_states state;
1966 struct sock *syn_wait_sk;
1967 int bucket, sbucket, num, uid;
1968 struct seq_operations seq_ops;
1969};
1970
1971extern int tcp_proc_register(struct tcp_seq_afinfo *afinfo);
1972extern void tcp_proc_unregister(struct tcp_seq_afinfo *afinfo);
1973
1974/* TCP Westwood functions and constants */
1975
1976#define TCP_WESTWOOD_INIT_RTT (20*HZ) /* maybe too conservative?! */
1977#define TCP_WESTWOOD_RTT_MIN (HZ/20) /* 50ms */
1978
1979static inline void tcp_westwood_update_rtt(struct tcp_sock *tp, __u32 rtt_seq)
1980{
1981 if (tcp_is_westwood(tp))
1982 tp->westwood.rtt = rtt_seq;
1983}
1984
1985static inline __u32 __tcp_westwood_bw_rttmin(const struct tcp_sock *tp)
1986{
1987 return max((tp->westwood.bw_est) * (tp->westwood.rtt_min) /
1988 (__u32) (tp->mss_cache_std),
1989 2U);
1990}
1991
1992static inline __u32 tcp_westwood_bw_rttmin(const struct tcp_sock *tp)
1993{
1994 return tcp_is_westwood(tp) ? __tcp_westwood_bw_rttmin(tp) : 0;
1995}
1996
1997static inline int tcp_westwood_ssthresh(struct tcp_sock *tp)
1998{
1999 __u32 ssthresh = 0;
2000
2001 if (tcp_is_westwood(tp)) {
2002 ssthresh = __tcp_westwood_bw_rttmin(tp);
2003 if (ssthresh)
2004 tp->snd_ssthresh = ssthresh;
2005 }
2006
2007 return (ssthresh != 0);
2008}
2009
2010static inline int tcp_westwood_cwnd(struct tcp_sock *tp)
2011{
2012 __u32 cwnd = 0;
2013
2014 if (tcp_is_westwood(tp)) {
2015 cwnd = __tcp_westwood_bw_rttmin(tp);
2016 if (cwnd)
2017 tp->snd_cwnd = cwnd;
2018 }
2019
2020 return (cwnd != 0);
2021}
2022#endif /* _TCP_H */
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