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