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 #include <linux/config.h> 25 #include <linux/list.h> 26 #include <linux/tcp.h> 27 #include <linux/slab.h> 28 #include <linux/cache.h> 29 #include <linux/percpu.h> 30 31 #include <net/inet_connection_sock.h> 32 #include <net/inet_timewait_sock.h> 33 #include <net/inet_hashtables.h> 34 #include <net/checksum.h> 35 #include <net/request_sock.h> 36 #include <net/sock.h> 37 #include <net/snmp.h> 38 #include <net/ip.h> 39 #include <net/tcp_states.h> 40 41 #include <linux/seq_file.h> 42 43 extern struct inet_hashinfo tcp_hashinfo; 44 45 extern atomic_t tcp_orphan_count; 46 extern void tcp_time_wait(struct sock *sk, int state, int timeo); 47 48 #define MAX_TCP_HEADER (128 + MAX_HEADER) 49 50 /* 51 * Never offer a window over 32767 without using window scaling. Some 52 * poor stacks do signed 16bit maths! 53 */ 54 #define MAX_TCP_WINDOW 32767U 55 56 /* Minimal accepted MSS. It is (60+60+8) - (20+20). */ 57 #define TCP_MIN_MSS 88U 58 59 /* Minimal RCV_MSS. */ 60 #define TCP_MIN_RCVMSS 536U 61 62 /* After receiving this amount of duplicate ACKs fast retransmit starts. */ 63 #define TCP_FASTRETRANS_THRESH 3 64 65 /* Maximal reordering. */ 66 #define TCP_MAX_REORDERING 127 67 68 /* Maximal number of ACKs sent quickly to accelerate slow-start. */ 69 #define TCP_MAX_QUICKACKS 16U 70 71 /* urg_data states */ 72 #define TCP_URG_VALID 0x0100 73 #define TCP_URG_NOTYET 0x0200 74 #define TCP_URG_READ 0x0400 75 76 #define TCP_RETR1 3 /* 77 * This is how many retries it does before it 78 * tries to figure out if the gateway is 79 * down. Minimal RFC value is 3; it corresponds 80 * to ~3sec-8min depending on RTO. 81 */ 82 83 #define TCP_RETR2 15 /* 84 * This should take at least 85 * 90 minutes to time out. 86 * RFC1122 says that the limit is 100 sec. 87 * 15 is ~13-30min depending on RTO. 88 */ 89 90 #define TCP_SYN_RETRIES 5 /* number of times to retry active opening a 91 * connection: ~180sec is RFC minumum */ 92 93 #define TCP_SYNACK_RETRIES 5 /* number of times to retry passive opening a 94 * connection: ~180sec is RFC minumum */ 95 96 97 #define TCP_ORPHAN_RETRIES 7 /* number of times to retry on an orphaned 98 * socket. 7 is ~50sec-16min. 99 */ 100 101 102 #define TCP_TIMEWAIT_LEN (60*HZ) /* how long to wait to destroy TIME-WAIT 103 * state, about 60 seconds */ 104 #define TCP_FIN_TIMEOUT TCP_TIMEWAIT_LEN 105 /* BSD style FIN_WAIT2 deadlock breaker. 106 * It used to be 3min, new value is 60sec, 107 * to combine FIN-WAIT-2 timeout with 108 * TIME-WAIT timer. 109 */ 110 111 #define TCP_DELACK_MAX ((unsigned)(HZ/5)) /* maximal time to delay before sending an ACK */ 112 #if HZ >= 100 113 #define TCP_DELACK_MIN ((unsigned)(HZ/25)) /* minimal time to delay before sending an ACK */ 114 #define TCP_ATO_MIN ((unsigned)(HZ/25)) 115 #else 116 #define TCP_DELACK_MIN 4U 117 #define TCP_ATO_MIN 4U 118 #endif 119 #define TCP_RTO_MAX ((unsigned)(120*HZ)) 120 #define TCP_RTO_MIN ((unsigned)(HZ/5)) 121 #define TCP_TIMEOUT_INIT ((unsigned)(3*HZ)) /* RFC 1122 initial RTO value */ 122 123 #define TCP_RESOURCE_PROBE_INTERVAL ((unsigned)(HZ/2U)) /* Maximal interval between probes 124 * for local resources. 125 */ 126 127 #define TCP_KEEPALIVE_TIME (120*60*HZ) /* two hours */ 128 #define TCP_KEEPALIVE_PROBES 9 /* Max of 9 keepalive probes */ 129 #define TCP_KEEPALIVE_INTVL (75*HZ) 130 131 #define MAX_TCP_KEEPIDLE 32767 132 #define MAX_TCP_KEEPINTVL 32767 133 #define MAX_TCP_KEEPCNT 127 134 #define MAX_TCP_SYNCNT 127 135 136 #define TCP_SYNQ_INTERVAL (HZ/5) /* Period of SYNACK timer */ 137 #define TCP_SYNQ_HSIZE 512 /* Size of SYNACK hash table */ 138 139 #define TCP_PAWS_24DAYS (60 * 60 * 24 * 24) 140 #define TCP_PAWS_MSL 60 /* Per-host timestamps are invalidated 141 * after this time. It should be equal 142 * (or greater than) TCP_TIMEWAIT_LEN 143 * to provide reliability equal to one 144 * provided by timewait state. 145 */ 146 #define TCP_PAWS_WINDOW 1 /* Replay window for per-host 147 * timestamps. It must be less than 148 * minimal timewait lifetime. 149 */ 150 /* 151 * TCP option 152 */ 153 154 #define TCPOPT_NOP 1 /* Padding */ 155 #define TCPOPT_EOL 0 /* End of options */ 156 #define TCPOPT_MSS 2 /* Segment size negotiating */ 157 #define TCPOPT_WINDOW 3 /* Window scaling */ 158 #define TCPOPT_SACK_PERM 4 /* SACK Permitted */ 159 #define TCPOPT_SACK 5 /* SACK Block */ 160 #define TCPOPT_TIMESTAMP 8 /* Better RTT estimations/PAWS */ 161 162 /* 163 * TCP option lengths 164 */ 165 166 #define TCPOLEN_MSS 4 167 #define TCPOLEN_WINDOW 3 168 #define TCPOLEN_SACK_PERM 2 169 #define TCPOLEN_TIMESTAMP 10 170 171 /* But this is what stacks really send out. */ 172 #define TCPOLEN_TSTAMP_ALIGNED 12 173 #define TCPOLEN_WSCALE_ALIGNED 4 174 #define TCPOLEN_SACKPERM_ALIGNED 4 175 #define TCPOLEN_SACK_BASE 2 176 #define TCPOLEN_SACK_BASE_ALIGNED 4 177 #define TCPOLEN_SACK_PERBLOCK 8 178 179 /* Flags in tp->nonagle */ 180 #define TCP_NAGLE_OFF 1 /* Nagle's algo is disabled */ 181 #define TCP_NAGLE_CORK 2 /* Socket is corked */ 182 #define TCP_NAGLE_PUSH 4 /* Cork is overriden for already queued data */ 183 184 extern struct inet_timewait_death_row tcp_death_row; 185 186 /* sysctl variables for tcp */ 187 extern int sysctl_tcp_timestamps; 188 extern int sysctl_tcp_window_scaling; 189 extern int sysctl_tcp_sack; 190 extern int sysctl_tcp_fin_timeout; 191 extern int sysctl_tcp_keepalive_time; 192 extern int sysctl_tcp_keepalive_probes; 193 extern int sysctl_tcp_keepalive_intvl; 194 extern int sysctl_tcp_syn_retries; 195 extern int sysctl_tcp_synack_retries; 196 extern int sysctl_tcp_retries1; 197 extern int sysctl_tcp_retries2; 198 extern int sysctl_tcp_orphan_retries; 199 extern int sysctl_tcp_syncookies; 200 extern int sysctl_tcp_retrans_collapse; 201 extern int sysctl_tcp_stdurg; 202 extern int sysctl_tcp_rfc1337; 203 extern int sysctl_tcp_abort_on_overflow; 204 extern int sysctl_tcp_max_orphans; 205 extern int sysctl_tcp_fack; 206 extern int sysctl_tcp_reordering; 207 extern int sysctl_tcp_ecn; 208 extern int sysctl_tcp_dsack; 209 extern int sysctl_tcp_mem[3]; 210 extern int sysctl_tcp_wmem[3]; 211 extern int sysctl_tcp_rmem[3]; 212 extern int sysctl_tcp_app_win; 213 extern int sysctl_tcp_adv_win_scale; 214 extern int sysctl_tcp_tw_reuse; 215 extern int sysctl_tcp_frto; 216 extern int sysctl_tcp_low_latency; 217 extern int sysctl_tcp_nometrics_save; 218 extern int sysctl_tcp_moderate_rcvbuf; 219 extern int sysctl_tcp_tso_win_divisor; 220 221 extern atomic_t tcp_memory_allocated; 222 extern atomic_t tcp_sockets_allocated; 223 extern int tcp_memory_pressure; 224 225 /* 226 * Pointers to address related TCP functions 227 * (i.e. things that depend on the address family) 228 */ 229 230 struct tcp_func { 231 int (*queue_xmit) (struct sk_buff *skb, 232 int ipfragok); 233 234 void (*send_check) (struct sock *sk, 235 struct tcphdr *th, 236 int len, 237 struct sk_buff *skb); 238 239 int (*rebuild_header) (struct sock *sk); 240 241 int (*conn_request) (struct sock *sk, 242 struct sk_buff *skb); 243 244 struct sock * (*syn_recv_sock) (struct sock *sk, 245 struct sk_buff *skb, 246 struct request_sock *req, 247 struct dst_entry *dst); 248 249 int (*remember_stamp) (struct sock *sk); 250 251 __u16 net_header_len; 252 253 int (*setsockopt) (struct sock *sk, 254 int level, 255 int optname, 256 char __user *optval, 257 int optlen); 258 259 int (*getsockopt) (struct sock *sk, 260 int level, 261 int optname, 262 char __user *optval, 263 int __user *optlen); 264 265 266 void (*addr2sockaddr) (struct sock *sk, 267 struct sockaddr *); 268 269 int sockaddr_len; 270 }; 271 272 /* 273 * The next routines deal with comparing 32 bit unsigned ints 274 * and worry about wraparound (automatic with unsigned arithmetic). 275 */ 276 277 static inline int before(__u32 seq1, __u32 seq2) 278 { 279 return (__s32)(seq1-seq2) < 0; 280 } 281 282 static inline int after(__u32 seq1, __u32 seq2) 283 { 284 return (__s32)(seq2-seq1) < 0; 285 } 286 287 288 /* is s2<=s1<=s3 ? */ 289 static inline int between(__u32 seq1, __u32 seq2, __u32 seq3) 290 { 291 return seq3 - seq2 >= seq1 - seq2; 292 } 293 294 295 extern struct proto tcp_prot; 296 297 DECLARE_SNMP_STAT(struct tcp_mib, tcp_statistics); 298 #define TCP_INC_STATS(field) SNMP_INC_STATS(tcp_statistics, field) 299 #define TCP_INC_STATS_BH(field) SNMP_INC_STATS_BH(tcp_statistics, field) 300 #define TCP_INC_STATS_USER(field) SNMP_INC_STATS_USER(tcp_statistics, field) 301 #define TCP_DEC_STATS(field) SNMP_DEC_STATS(tcp_statistics, field) 302 #define TCP_ADD_STATS_BH(field, val) SNMP_ADD_STATS_BH(tcp_statistics, field, val) 303 #define TCP_ADD_STATS_USER(field, val) SNMP_ADD_STATS_USER(tcp_statistics, field, val) 304 305 extern void tcp_v4_err(struct sk_buff *skb, u32); 306 307 extern void tcp_shutdown (struct sock *sk, int how); 308 309 extern int tcp_v4_rcv(struct sk_buff *skb); 310 311 extern int tcp_v4_remember_stamp(struct sock *sk); 312 313 extern int tcp_v4_tw_remember_stamp(struct inet_timewait_sock *tw); 314 315 extern int tcp_sendmsg(struct kiocb *iocb, struct sock *sk, 316 struct msghdr *msg, size_t size); 317 extern ssize_t tcp_sendpage(struct socket *sock, struct page *page, int offset, size_t size, int flags); 318 319 extern int tcp_ioctl(struct sock *sk, 320 int cmd, 321 unsigned long arg); 322 323 extern int tcp_rcv_state_process(struct sock *sk, 324 struct sk_buff *skb, 325 struct tcphdr *th, 326 unsigned len); 327 328 extern int tcp_rcv_established(struct sock *sk, 329 struct sk_buff *skb, 330 struct tcphdr *th, 331 unsigned len); 332 333 extern void tcp_rcv_space_adjust(struct sock *sk); 334 335 static inline void tcp_dec_quickack_mode(struct sock *sk, 336 const unsigned int pkts) 337 { 338 struct inet_connection_sock *icsk = inet_csk(sk); 339 340 if (icsk->icsk_ack.quick) { 341 if (pkts >= icsk->icsk_ack.quick) { 342 icsk->icsk_ack.quick = 0; 343 /* Leaving quickack mode we deflate ATO. */ 344 icsk->icsk_ack.ato = TCP_ATO_MIN; 345 } else 346 icsk->icsk_ack.quick -= pkts; 347 } 348 } 349 350 extern void tcp_enter_quickack_mode(struct sock *sk); 351 352 static inline void tcp_clear_options(struct tcp_options_received *rx_opt) 353 { 354 rx_opt->tstamp_ok = rx_opt->sack_ok = rx_opt->wscale_ok = rx_opt->snd_wscale = 0; 355 } 356 357 enum tcp_tw_status 358 { 359 TCP_TW_SUCCESS = 0, 360 TCP_TW_RST = 1, 361 TCP_TW_ACK = 2, 362 TCP_TW_SYN = 3 363 }; 364 365 366 extern enum tcp_tw_status tcp_timewait_state_process(struct inet_timewait_sock *tw, 367 struct sk_buff *skb, 368 const struct tcphdr *th); 369 370 extern struct sock * tcp_check_req(struct sock *sk,struct sk_buff *skb, 371 struct request_sock *req, 372 struct request_sock **prev); 373 extern int tcp_child_process(struct sock *parent, 374 struct sock *child, 375 struct sk_buff *skb); 376 extern void tcp_enter_frto(struct sock *sk); 377 extern void tcp_enter_loss(struct sock *sk, int how); 378 extern void tcp_clear_retrans(struct tcp_sock *tp); 379 extern void tcp_update_metrics(struct sock *sk); 380 381 extern void tcp_close(struct sock *sk, 382 long timeout); 383 extern unsigned int tcp_poll(struct file * file, struct socket *sock, struct poll_table_struct *wait); 384 385 extern int tcp_getsockopt(struct sock *sk, int level, 386 int optname, 387 char __user *optval, 388 int __user *optlen); 389 extern int tcp_setsockopt(struct sock *sk, int level, 390 int optname, char __user *optval, 391 int optlen); 392 extern void tcp_set_keepalive(struct sock *sk, int val); 393 extern int tcp_recvmsg(struct kiocb *iocb, struct sock *sk, 394 struct msghdr *msg, 395 size_t len, int nonblock, 396 int flags, int *addr_len); 397 398 extern void tcp_parse_options(struct sk_buff *skb, 399 struct tcp_options_received *opt_rx, 400 int estab); 401 402 /* 403 * TCP v4 functions exported for the inet6 API 404 */ 405 406 extern void tcp_v4_send_check(struct sock *sk, 407 struct tcphdr *th, int len, 408 struct sk_buff *skb); 409 410 extern int tcp_v4_conn_request(struct sock *sk, 411 struct sk_buff *skb); 412 413 extern struct sock * tcp_create_openreq_child(struct sock *sk, 414 struct request_sock *req, 415 struct sk_buff *skb); 416 417 extern struct sock * tcp_v4_syn_recv_sock(struct sock *sk, 418 struct sk_buff *skb, 419 struct request_sock *req, 420 struct dst_entry *dst); 421 422 extern int tcp_v4_do_rcv(struct sock *sk, 423 struct sk_buff *skb); 424 425 extern int tcp_v4_connect(struct sock *sk, 426 struct sockaddr *uaddr, 427 int addr_len); 428 429 extern int tcp_connect(struct sock *sk); 430 431 extern struct sk_buff * tcp_make_synack(struct sock *sk, 432 struct dst_entry *dst, 433 struct request_sock *req); 434 435 extern int tcp_disconnect(struct sock *sk, int flags); 436 437 extern void tcp_unhash(struct sock *sk); 438 439 extern int tcp_v4_hash_connecting(struct sock *sk); 440 441 442 /* From syncookies.c */ 443 extern struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb, 444 struct ip_options *opt); 445 extern __u32 cookie_v4_init_sequence(struct sock *sk, struct sk_buff *skb, 446 __u16 *mss); 447 448 /* tcp_output.c */ 449 450 extern void __tcp_push_pending_frames(struct sock *sk, struct tcp_sock *tp, 451 unsigned int cur_mss, int nonagle); 452 extern int tcp_may_send_now(struct sock *sk, struct tcp_sock *tp); 453 extern int tcp_retransmit_skb(struct sock *, struct sk_buff *); 454 extern void tcp_xmit_retransmit_queue(struct sock *); 455 extern void tcp_simple_retransmit(struct sock *); 456 extern int tcp_trim_head(struct sock *, struct sk_buff *, u32); 457 extern int tcp_fragment(struct sock *, struct sk_buff *, u32, unsigned int); 458 459 extern void tcp_send_probe0(struct sock *); 460 extern void tcp_send_partial(struct sock *); 461 extern int tcp_write_wakeup(struct sock *); 462 extern void tcp_send_fin(struct sock *sk); 463 extern void tcp_send_active_reset(struct sock *sk, 464 unsigned int __nocast priority); 465 extern int tcp_send_synack(struct sock *); 466 extern void tcp_push_one(struct sock *, unsigned int mss_now); 467 extern void tcp_send_ack(struct sock *sk); 468 extern void tcp_send_delayed_ack(struct sock *sk); 469 470 /* tcp_input.c */ 471 extern void tcp_cwnd_application_limited(struct sock *sk); 472 473 /* tcp_timer.c */ 474 extern void tcp_init_xmit_timers(struct sock *); 475 static inline void tcp_clear_xmit_timers(struct sock *sk) 476 { 477 inet_csk_clear_xmit_timers(sk); 478 } 479 480 extern unsigned int tcp_sync_mss(struct sock *sk, u32 pmtu); 481 extern unsigned int tcp_current_mss(struct sock *sk, int large); 482 483 /* tcp.c */ 484 extern void tcp_get_info(struct sock *, struct tcp_info *); 485 486 /* Read 'sendfile()'-style from a TCP socket */ 487 typedef int (*sk_read_actor_t)(read_descriptor_t *, struct sk_buff *, 488 unsigned int, size_t); 489 extern int tcp_read_sock(struct sock *sk, read_descriptor_t *desc, 490 sk_read_actor_t recv_actor); 491 492 /* Initialize RCV_MSS value. 493 * RCV_MSS is an our guess about MSS used by the peer. 494 * We haven't any direct information about the MSS. 495 * It's better to underestimate the RCV_MSS rather than overestimate. 496 * Overestimations make us ACKing less frequently than needed. 497 * Underestimations are more easy to detect and fix by tcp_measure_rcv_mss(). 498 */ 499 500 static inline void tcp_initialize_rcv_mss(struct sock *sk) 501 { 502 struct tcp_sock *tp = tcp_sk(sk); 503 unsigned int hint = min_t(unsigned int, tp->advmss, tp->mss_cache); 504 505 hint = min(hint, tp->rcv_wnd/2); 506 hint = min(hint, TCP_MIN_RCVMSS); 507 hint = max(hint, TCP_MIN_MSS); 508 509 inet_csk(sk)->icsk_ack.rcv_mss = hint; 510 } 511 512 static __inline__ void __tcp_fast_path_on(struct tcp_sock *tp, u32 snd_wnd) 513 { 514 tp->pred_flags = htonl((tp->tcp_header_len << 26) | 515 ntohl(TCP_FLAG_ACK) | 516 snd_wnd); 517 } 518 519 static __inline__ void tcp_fast_path_on(struct tcp_sock *tp) 520 { 521 __tcp_fast_path_on(tp, tp->snd_wnd >> tp->rx_opt.snd_wscale); 522 } 523 524 static inline void tcp_fast_path_check(struct sock *sk, struct tcp_sock *tp) 525 { 526 if (skb_queue_empty(&tp->out_of_order_queue) && 527 tp->rcv_wnd && 528 atomic_read(&sk->sk_rmem_alloc) < sk->sk_rcvbuf && 529 !tp->urg_data) 530 tcp_fast_path_on(tp); 531 } 532 533 /* Compute the actual receive window we are currently advertising. 534 * Rcv_nxt can be after the window if our peer push more data 535 * than the offered window. 536 */ 537 static __inline__ u32 tcp_receive_window(const struct tcp_sock *tp) 538 { 539 s32 win = tp->rcv_wup + tp->rcv_wnd - tp->rcv_nxt; 540 541 if (win < 0) 542 win = 0; 543 return (u32) win; 544 } 545 546 /* Choose a new window, without checks for shrinking, and without 547 * scaling applied to the result. The caller does these things 548 * if necessary. This is a "raw" window selection. 549 */ 550 extern u32 __tcp_select_window(struct sock *sk); 551 552 /* TCP timestamps are only 32-bits, this causes a slight 553 * complication on 64-bit systems since we store a snapshot 554 * of jiffies in the buffer control blocks below. We decidely 555 * only use of the low 32-bits of jiffies and hide the ugly 556 * casts with the following macro. 557 */ 558 #define tcp_time_stamp ((__u32)(jiffies)) 559 560 /* This is what the send packet queueing engine uses to pass 561 * TCP per-packet control information to the transmission 562 * code. We also store the host-order sequence numbers in 563 * here too. This is 36 bytes on 32-bit architectures, 564 * 40 bytes on 64-bit machines, if this grows please adjust 565 * skbuff.h:skbuff->cb[xxx] size appropriately. 566 */ 567 struct tcp_skb_cb { 568 union { 569 struct inet_skb_parm h4; 570 #if defined(CONFIG_IPV6) || defined (CONFIG_IPV6_MODULE) 571 struct inet6_skb_parm h6; 572 #endif 573 } header; /* For incoming frames */ 574 __u32 seq; /* Starting sequence number */ 575 __u32 end_seq; /* SEQ + FIN + SYN + datalen */ 576 __u32 when; /* used to compute rtt's */ 577 __u8 flags; /* TCP header flags. */ 578 579 /* NOTE: These must match up to the flags byte in a 580 * real TCP header. 581 */ 582 #define TCPCB_FLAG_FIN 0x01 583 #define TCPCB_FLAG_SYN 0x02 584 #define TCPCB_FLAG_RST 0x04 585 #define TCPCB_FLAG_PSH 0x08 586 #define TCPCB_FLAG_ACK 0x10 587 #define TCPCB_FLAG_URG 0x20 588 #define TCPCB_FLAG_ECE 0x40 589 #define TCPCB_FLAG_CWR 0x80 590 591 __u8 sacked; /* State flags for SACK/FACK. */ 592 #define TCPCB_SACKED_ACKED 0x01 /* SKB ACK'd by a SACK block */ 593 #define TCPCB_SACKED_RETRANS 0x02 /* SKB retransmitted */ 594 #define TCPCB_LOST 0x04 /* SKB is lost */ 595 #define TCPCB_TAGBITS 0x07 /* All tag bits */ 596 597 #define TCPCB_EVER_RETRANS 0x80 /* Ever retransmitted frame */ 598 #define TCPCB_RETRANS (TCPCB_SACKED_RETRANS|TCPCB_EVER_RETRANS) 599 600 #define TCPCB_URG 0x20 /* Urgent pointer advenced here */ 601 602 #define TCPCB_AT_TAIL (TCPCB_URG) 603 604 __u16 urg_ptr; /* Valid w/URG flags is set. */ 605 __u32 ack_seq; /* Sequence number ACK'd */ 606 }; 607 608 #define TCP_SKB_CB(__skb) ((struct tcp_skb_cb *)&((__skb)->cb[0])) 609 610 #include <net/tcp_ecn.h> 611 612 /* Due to TSO, an SKB can be composed of multiple actual 613 * packets. To keep these tracked properly, we use this. 614 */ 615 static inline int tcp_skb_pcount(const struct sk_buff *skb) 616 { 617 return skb_shinfo(skb)->tso_segs; 618 } 619 620 /* This is valid iff tcp_skb_pcount() > 1. */ 621 static inline int tcp_skb_mss(const struct sk_buff *skb) 622 { 623 return skb_shinfo(skb)->tso_size; 624 } 625 626 static inline void tcp_dec_pcount_approx(__u32 *count, 627 const struct sk_buff *skb) 628 { 629 if (*count) { 630 *count -= tcp_skb_pcount(skb); 631 if ((int)*count < 0) 632 *count = 0; 633 } 634 } 635 636 static inline void tcp_packets_out_inc(struct sock *sk, 637 struct tcp_sock *tp, 638 const struct sk_buff *skb) 639 { 640 int orig = tp->packets_out; 641 642 tp->packets_out += tcp_skb_pcount(skb); 643 if (!orig) 644 inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, 645 inet_csk(sk)->icsk_rto, TCP_RTO_MAX); 646 } 647 648 static inline void tcp_packets_out_dec(struct tcp_sock *tp, 649 const struct sk_buff *skb) 650 { 651 tp->packets_out -= tcp_skb_pcount(skb); 652 } 653 654 /* Events passed to congestion control interface */ 655 enum tcp_ca_event { 656 CA_EVENT_TX_START, /* first transmit when no packets in flight */ 657 CA_EVENT_CWND_RESTART, /* congestion window restart */ 658 CA_EVENT_COMPLETE_CWR, /* end of congestion recovery */ 659 CA_EVENT_FRTO, /* fast recovery timeout */ 660 CA_EVENT_LOSS, /* loss timeout */ 661 CA_EVENT_FAST_ACK, /* in sequence ack */ 662 CA_EVENT_SLOW_ACK, /* other ack */ 663 }; 664 665 /* 666 * Interface for adding new TCP congestion control handlers 667 */ 668 #define TCP_CA_NAME_MAX 16 669 struct tcp_congestion_ops { 670 struct list_head list; 671 672 /* initialize private data (optional) */ 673 void (*init)(struct sock *sk); 674 /* cleanup private data (optional) */ 675 void (*release)(struct sock *sk); 676 677 /* return slow start threshold (required) */ 678 u32 (*ssthresh)(struct sock *sk); 679 /* lower bound for congestion window (optional) */ 680 u32 (*min_cwnd)(struct sock *sk); 681 /* do new cwnd calculation (required) */ 682 void (*cong_avoid)(struct sock *sk, u32 ack, 683 u32 rtt, u32 in_flight, int good_ack); 684 /* round trip time sample per acked packet (optional) */ 685 void (*rtt_sample)(struct sock *sk, u32 usrtt); 686 /* call before changing ca_state (optional) */ 687 void (*set_state)(struct sock *sk, u8 new_state); 688 /* call when cwnd event occurs (optional) */ 689 void (*cwnd_event)(struct sock *sk, enum tcp_ca_event ev); 690 /* new value of cwnd after loss (optional) */ 691 u32 (*undo_cwnd)(struct sock *sk); 692 /* hook for packet ack accounting (optional) */ 693 void (*pkts_acked)(struct sock *sk, u32 num_acked); 694 /* get info for inet_diag (optional) */ 695 void (*get_info)(struct sock *sk, u32 ext, struct sk_buff *skb); 696 697 char name[TCP_CA_NAME_MAX]; 698 struct module *owner; 699 }; 700 701 extern int tcp_register_congestion_control(struct tcp_congestion_ops *type); 702 extern void tcp_unregister_congestion_control(struct tcp_congestion_ops *type); 703 704 extern void tcp_init_congestion_control(struct sock *sk); 705 extern void tcp_cleanup_congestion_control(struct sock *sk); 706 extern int tcp_set_default_congestion_control(const char *name); 707 extern void tcp_get_default_congestion_control(char *name); 708 extern int tcp_set_congestion_control(struct sock *sk, const char *name); 709 710 extern struct tcp_congestion_ops tcp_init_congestion_ops; 711 extern u32 tcp_reno_ssthresh(struct sock *sk); 712 extern void tcp_reno_cong_avoid(struct sock *sk, u32 ack, 713 u32 rtt, u32 in_flight, int flag); 714 extern u32 tcp_reno_min_cwnd(struct sock *sk); 715 extern struct tcp_congestion_ops tcp_reno; 716 717 static inline void tcp_set_ca_state(struct sock *sk, const u8 ca_state) 718 { 719 struct inet_connection_sock *icsk = inet_csk(sk); 720 721 if (icsk->icsk_ca_ops->set_state) 722 icsk->icsk_ca_ops->set_state(sk, ca_state); 723 icsk->icsk_ca_state = ca_state; 724 } 725 726 static inline void tcp_ca_event(struct sock *sk, const enum tcp_ca_event event) 727 { 728 const struct inet_connection_sock *icsk = inet_csk(sk); 729 730 if (icsk->icsk_ca_ops->cwnd_event) 731 icsk->icsk_ca_ops->cwnd_event(sk, event); 732 } 733 734 /* This determines how many packets are "in the network" to the best 735 * of our knowledge. In many cases it is conservative, but where 736 * detailed information is available from the receiver (via SACK 737 * blocks etc.) we can make more aggressive calculations. 738 * 739 * Use this for decisions involving congestion control, use just 740 * tp->packets_out to determine if the send queue is empty or not. 741 * 742 * Read this equation as: 743 * 744 * "Packets sent once on transmission queue" MINUS 745 * "Packets left network, but not honestly ACKed yet" PLUS 746 * "Packets fast retransmitted" 747 */ 748 static __inline__ unsigned int tcp_packets_in_flight(const struct tcp_sock *tp) 749 { 750 return (tp->packets_out - tp->left_out + tp->retrans_out); 751 } 752 753 /* If cwnd > ssthresh, we may raise ssthresh to be half-way to cwnd. 754 * The exception is rate halving phase, when cwnd is decreasing towards 755 * ssthresh. 756 */ 757 static inline __u32 tcp_current_ssthresh(const struct sock *sk) 758 { 759 const struct tcp_sock *tp = tcp_sk(sk); 760 if ((1 << inet_csk(sk)->icsk_ca_state) & (TCPF_CA_CWR | TCPF_CA_Recovery)) 761 return tp->snd_ssthresh; 762 else 763 return max(tp->snd_ssthresh, 764 ((tp->snd_cwnd >> 1) + 765 (tp->snd_cwnd >> 2))); 766 } 767 768 static inline void tcp_sync_left_out(struct tcp_sock *tp) 769 { 770 if (tp->rx_opt.sack_ok && 771 (tp->sacked_out >= tp->packets_out - tp->lost_out)) 772 tp->sacked_out = tp->packets_out - tp->lost_out; 773 tp->left_out = tp->sacked_out + tp->lost_out; 774 } 775 776 /* Set slow start threshold and cwnd not falling to slow start */ 777 static inline void __tcp_enter_cwr(struct sock *sk) 778 { 779 const struct inet_connection_sock *icsk = inet_csk(sk); 780 struct tcp_sock *tp = tcp_sk(sk); 781 782 tp->undo_marker = 0; 783 tp->snd_ssthresh = icsk->icsk_ca_ops->ssthresh(sk); 784 tp->snd_cwnd = min(tp->snd_cwnd, 785 tcp_packets_in_flight(tp) + 1U); 786 tp->snd_cwnd_cnt = 0; 787 tp->high_seq = tp->snd_nxt; 788 tp->snd_cwnd_stamp = tcp_time_stamp; 789 TCP_ECN_queue_cwr(tp); 790 } 791 792 static inline void tcp_enter_cwr(struct sock *sk) 793 { 794 struct tcp_sock *tp = tcp_sk(sk); 795 796 tp->prior_ssthresh = 0; 797 if (inet_csk(sk)->icsk_ca_state < TCP_CA_CWR) { 798 __tcp_enter_cwr(sk); 799 tcp_set_ca_state(sk, TCP_CA_CWR); 800 } 801 } 802 803 extern __u32 tcp_init_cwnd(struct tcp_sock *tp, struct dst_entry *dst); 804 805 /* Slow start with delack produces 3 packets of burst, so that 806 * it is safe "de facto". 807 */ 808 static __inline__ __u32 tcp_max_burst(const struct tcp_sock *tp) 809 { 810 return 3; 811 } 812 813 static __inline__ void tcp_minshall_update(struct tcp_sock *tp, int mss, 814 const struct sk_buff *skb) 815 { 816 if (skb->len < mss) 817 tp->snd_sml = TCP_SKB_CB(skb)->end_seq; 818 } 819 820 static __inline__ void tcp_check_probe_timer(struct sock *sk, struct tcp_sock *tp) 821 { 822 const struct inet_connection_sock *icsk = inet_csk(sk); 823 if (!tp->packets_out && !icsk->icsk_pending) 824 inet_csk_reset_xmit_timer(sk, ICSK_TIME_PROBE0, 825 icsk->icsk_rto, TCP_RTO_MAX); 826 } 827 828 static __inline__ void tcp_push_pending_frames(struct sock *sk, 829 struct tcp_sock *tp) 830 { 831 __tcp_push_pending_frames(sk, tp, tcp_current_mss(sk, 1), tp->nonagle); 832 } 833 834 static __inline__ void tcp_init_wl(struct tcp_sock *tp, u32 ack, u32 seq) 835 { 836 tp->snd_wl1 = seq; 837 } 838 839 static __inline__ void tcp_update_wl(struct tcp_sock *tp, u32 ack, u32 seq) 840 { 841 tp->snd_wl1 = seq; 842 } 843 844 /* 845 * Calculate(/check) TCP checksum 846 */ 847 static __inline__ u16 tcp_v4_check(struct tcphdr *th, int len, 848 unsigned long saddr, unsigned long daddr, 849 unsigned long base) 850 { 851 return csum_tcpudp_magic(saddr,daddr,len,IPPROTO_TCP,base); 852 } 853 854 static __inline__ int __tcp_checksum_complete(struct sk_buff *skb) 855 { 856 return (unsigned short)csum_fold(skb_checksum(skb, 0, skb->len, skb->csum)); 857 } 858 859 static __inline__ int tcp_checksum_complete(struct sk_buff *skb) 860 { 861 return skb->ip_summed != CHECKSUM_UNNECESSARY && 862 __tcp_checksum_complete(skb); 863 } 864 865 /* Prequeue for VJ style copy to user, combined with checksumming. */ 866 867 static __inline__ void tcp_prequeue_init(struct tcp_sock *tp) 868 { 869 tp->ucopy.task = NULL; 870 tp->ucopy.len = 0; 871 tp->ucopy.memory = 0; 872 skb_queue_head_init(&tp->ucopy.prequeue); 873 } 874 875 /* Packet is added to VJ-style prequeue for processing in process 876 * context, if a reader task is waiting. Apparently, this exciting 877 * idea (VJ's mail "Re: query about TCP header on tcp-ip" of 07 Sep 93) 878 * failed somewhere. Latency? Burstiness? Well, at least now we will 879 * see, why it failed. 8)8) --ANK 880 * 881 * NOTE: is this not too big to inline? 882 */ 883 static __inline__ int tcp_prequeue(struct sock *sk, struct sk_buff *skb) 884 { 885 struct tcp_sock *tp = tcp_sk(sk); 886 887 if (!sysctl_tcp_low_latency && tp->ucopy.task) { 888 __skb_queue_tail(&tp->ucopy.prequeue, skb); 889 tp->ucopy.memory += skb->truesize; 890 if (tp->ucopy.memory > sk->sk_rcvbuf) { 891 struct sk_buff *skb1; 892 893 BUG_ON(sock_owned_by_user(sk)); 894 895 while ((skb1 = __skb_dequeue(&tp->ucopy.prequeue)) != NULL) { 896 sk->sk_backlog_rcv(sk, skb1); 897 NET_INC_STATS_BH(LINUX_MIB_TCPPREQUEUEDROPPED); 898 } 899 900 tp->ucopy.memory = 0; 901 } else if (skb_queue_len(&tp->ucopy.prequeue) == 1) { 902 wake_up_interruptible(sk->sk_sleep); 903 if (!inet_csk_ack_scheduled(sk)) 904 inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK, 905 (3 * TCP_RTO_MIN) / 4, 906 TCP_RTO_MAX); 907 } 908 return 1; 909 } 910 return 0; 911 } 912 913 914 #undef STATE_TRACE 915 916 #ifdef STATE_TRACE 917 static const char *statename[]={ 918 "Unused","Established","Syn Sent","Syn Recv", 919 "Fin Wait 1","Fin Wait 2","Time Wait", "Close", 920 "Close Wait","Last ACK","Listen","Closing" 921 }; 922 #endif 923 924 static __inline__ void tcp_set_state(struct sock *sk, int state) 925 { 926 int oldstate = sk->sk_state; 927 928 switch (state) { 929 case TCP_ESTABLISHED: 930 if (oldstate != TCP_ESTABLISHED) 931 TCP_INC_STATS(TCP_MIB_CURRESTAB); 932 break; 933 934 case TCP_CLOSE: 935 if (oldstate == TCP_CLOSE_WAIT || oldstate == TCP_ESTABLISHED) 936 TCP_INC_STATS(TCP_MIB_ESTABRESETS); 937 938 sk->sk_prot->unhash(sk); 939 if (inet_csk(sk)->icsk_bind_hash && 940 !(sk->sk_userlocks & SOCK_BINDPORT_LOCK)) 941 inet_put_port(&tcp_hashinfo, sk); 942 /* fall through */ 943 default: 944 if (oldstate==TCP_ESTABLISHED) 945 TCP_DEC_STATS(TCP_MIB_CURRESTAB); 946 } 947 948 /* Change state AFTER socket is unhashed to avoid closed 949 * socket sitting in hash tables. 950 */ 951 sk->sk_state = state; 952 953 #ifdef STATE_TRACE 954 SOCK_DEBUG(sk, "TCP sk=%p, State %s -> %s\n",sk, statename[oldstate],statename[state]); 955 #endif 956 } 957 958 static __inline__ void tcp_done(struct sock *sk) 959 { 960 tcp_set_state(sk, TCP_CLOSE); 961 tcp_clear_xmit_timers(sk); 962 963 sk->sk_shutdown = SHUTDOWN_MASK; 964 965 if (!sock_flag(sk, SOCK_DEAD)) 966 sk->sk_state_change(sk); 967 else 968 inet_csk_destroy_sock(sk); 969 } 970 971 static __inline__ void tcp_sack_reset(struct tcp_options_received *rx_opt) 972 { 973 rx_opt->dsack = 0; 974 rx_opt->eff_sacks = 0; 975 rx_opt->num_sacks = 0; 976 } 977 978 static __inline__ void tcp_build_and_update_options(__u32 *ptr, struct tcp_sock *tp, __u32 tstamp) 979 { 980 if (tp->rx_opt.tstamp_ok) { 981 *ptr++ = __constant_htonl((TCPOPT_NOP << 24) | 982 (TCPOPT_NOP << 16) | 983 (TCPOPT_TIMESTAMP << 8) | 984 TCPOLEN_TIMESTAMP); 985 *ptr++ = htonl(tstamp); 986 *ptr++ = htonl(tp->rx_opt.ts_recent); 987 } 988 if (tp->rx_opt.eff_sacks) { 989 struct tcp_sack_block *sp = tp->rx_opt.dsack ? tp->duplicate_sack : tp->selective_acks; 990 int this_sack; 991 992 *ptr++ = __constant_htonl((TCPOPT_NOP << 24) | 993 (TCPOPT_NOP << 16) | 994 (TCPOPT_SACK << 8) | 995 (TCPOLEN_SACK_BASE + 996 (tp->rx_opt.eff_sacks * TCPOLEN_SACK_PERBLOCK))); 997 for(this_sack = 0; this_sack < tp->rx_opt.eff_sacks; this_sack++) { 998 *ptr++ = htonl(sp[this_sack].start_seq); 999 *ptr++ = htonl(sp[this_sack].end_seq); 1000 } 1001 if (tp->rx_opt.dsack) { 1002 tp->rx_opt.dsack = 0; 1003 tp->rx_opt.eff_sacks--; 1004 } 1005 } 1006 } 1007 1008 /* Construct a tcp options header for a SYN or SYN_ACK packet. 1009 * If this is every changed make sure to change the definition of 1010 * MAX_SYN_SIZE to match the new maximum number of options that you 1011 * can generate. 1012 */ 1013 static inline void tcp_syn_build_options(__u32 *ptr, int mss, int ts, int sack, 1014 int offer_wscale, int wscale, __u32 tstamp, __u32 ts_recent) 1015 { 1016 /* We always get an MSS option. 1017 * The option bytes which will be seen in normal data 1018 * packets should timestamps be used, must be in the MSS 1019 * advertised. But we subtract them from tp->mss_cache so 1020 * that calculations in tcp_sendmsg are simpler etc. 1021 * So account for this fact here if necessary. If we 1022 * don't do this correctly, as a receiver we won't 1023 * recognize data packets as being full sized when we 1024 * should, and thus we won't abide by the delayed ACK 1025 * rules correctly. 1026 * SACKs don't matter, we never delay an ACK when we 1027 * have any of those going out. 1028 */ 1029 *ptr++ = htonl((TCPOPT_MSS << 24) | (TCPOLEN_MSS << 16) | mss); 1030 if (ts) { 1031 if(sack) 1032 *ptr++ = __constant_htonl((TCPOPT_SACK_PERM << 24) | (TCPOLEN_SACK_PERM << 16) | 1033 (TCPOPT_TIMESTAMP << 8) | TCPOLEN_TIMESTAMP); 1034 else 1035 *ptr++ = __constant_htonl((TCPOPT_NOP << 24) | (TCPOPT_NOP << 16) | 1036 (TCPOPT_TIMESTAMP << 8) | TCPOLEN_TIMESTAMP); 1037 *ptr++ = htonl(tstamp); /* TSVAL */ 1038 *ptr++ = htonl(ts_recent); /* TSECR */ 1039 } else if(sack) 1040 *ptr++ = __constant_htonl((TCPOPT_NOP << 24) | (TCPOPT_NOP << 16) | 1041 (TCPOPT_SACK_PERM << 8) | TCPOLEN_SACK_PERM); 1042 if (offer_wscale) 1043 *ptr++ = htonl((TCPOPT_NOP << 24) | (TCPOPT_WINDOW << 16) | (TCPOLEN_WINDOW << 8) | (wscale)); 1044 } 1045 1046 /* Determine a window scaling and initial window to offer. */ 1047 extern void tcp_select_initial_window(int __space, __u32 mss, 1048 __u32 *rcv_wnd, __u32 *window_clamp, 1049 int wscale_ok, __u8 *rcv_wscale); 1050 1051 static inline int tcp_win_from_space(int space) 1052 { 1053 return sysctl_tcp_adv_win_scale<=0 ? 1054 (space>>(-sysctl_tcp_adv_win_scale)) : 1055 space - (space>>sysctl_tcp_adv_win_scale); 1056 } 1057 1058 /* Note: caller must be prepared to deal with negative returns */ 1059 static inline int tcp_space(const struct sock *sk) 1060 { 1061 return tcp_win_from_space(sk->sk_rcvbuf - 1062 atomic_read(&sk->sk_rmem_alloc)); 1063 } 1064 1065 static inline int tcp_full_space(const struct sock *sk) 1066 { 1067 return tcp_win_from_space(sk->sk_rcvbuf); 1068 } 1069 1070 static __inline__ void tcp_openreq_init(struct request_sock *req, 1071 struct tcp_options_received *rx_opt, 1072 struct sk_buff *skb) 1073 { 1074 struct inet_request_sock *ireq = inet_rsk(req); 1075 1076 req->rcv_wnd = 0; /* So that tcp_send_synack() knows! */ 1077 tcp_rsk(req)->rcv_isn = TCP_SKB_CB(skb)->seq; 1078 req->mss = rx_opt->mss_clamp; 1079 req->ts_recent = rx_opt->saw_tstamp ? rx_opt->rcv_tsval : 0; 1080 ireq->tstamp_ok = rx_opt->tstamp_ok; 1081 ireq->sack_ok = rx_opt->sack_ok; 1082 ireq->snd_wscale = rx_opt->snd_wscale; 1083 ireq->wscale_ok = rx_opt->wscale_ok; 1084 ireq->acked = 0; 1085 ireq->ecn_ok = 0; 1086 ireq->rmt_port = skb->h.th->source; 1087 } 1088 1089 extern void tcp_enter_memory_pressure(void); 1090 1091 static inline int keepalive_intvl_when(const struct tcp_sock *tp) 1092 { 1093 return tp->keepalive_intvl ? : sysctl_tcp_keepalive_intvl; 1094 } 1095 1096 static inline int keepalive_time_when(const struct tcp_sock *tp) 1097 { 1098 return tp->keepalive_time ? : sysctl_tcp_keepalive_time; 1099 } 1100 1101 static inline int tcp_fin_time(const struct sock *sk) 1102 { 1103 int fin_timeout = tcp_sk(sk)->linger2 ? : sysctl_tcp_fin_timeout; 1104 const int rto = inet_csk(sk)->icsk_rto; 1105 1106 if (fin_timeout < (rto << 2) - (rto >> 1)) 1107 fin_timeout = (rto << 2) - (rto >> 1); 1108 1109 return fin_timeout; 1110 } 1111 1112 static inline int tcp_paws_check(const struct tcp_options_received *rx_opt, int rst) 1113 { 1114 if ((s32)(rx_opt->rcv_tsval - rx_opt->ts_recent) >= 0) 1115 return 0; 1116 if (xtime.tv_sec >= rx_opt->ts_recent_stamp + TCP_PAWS_24DAYS) 1117 return 0; 1118 1119 /* RST segments are not recommended to carry timestamp, 1120 and, if they do, it is recommended to ignore PAWS because 1121 "their cleanup function should take precedence over timestamps." 1122 Certainly, it is mistake. It is necessary to understand the reasons 1123 of this constraint to relax it: if peer reboots, clock may go 1124 out-of-sync and half-open connections will not be reset. 1125 Actually, the problem would be not existing if all 1126 the implementations followed draft about maintaining clock 1127 via reboots. Linux-2.2 DOES NOT! 1128 1129 However, we can relax time bounds for RST segments to MSL. 1130 */ 1131 if (rst && xtime.tv_sec >= rx_opt->ts_recent_stamp + TCP_PAWS_MSL) 1132 return 0; 1133 return 1; 1134 } 1135 1136 #define TCP_CHECK_TIMER(sk) do { } while (0) 1137 1138 static inline int tcp_use_frto(const struct sock *sk) 1139 { 1140 const struct tcp_sock *tp = tcp_sk(sk); 1141 1142 /* F-RTO must be activated in sysctl and there must be some 1143 * unsent new data, and the advertised window should allow 1144 * sending it. 1145 */ 1146 return (sysctl_tcp_frto && sk->sk_send_head && 1147 !after(TCP_SKB_CB(sk->sk_send_head)->end_seq, 1148 tp->snd_una + tp->snd_wnd)); 1149 } 1150 1151 static inline void tcp_mib_init(void) 1152 { 1153 /* See RFC 2012 */ 1154 TCP_ADD_STATS_USER(TCP_MIB_RTOALGORITHM, 1); 1155 TCP_ADD_STATS_USER(TCP_MIB_RTOMIN, TCP_RTO_MIN*1000/HZ); 1156 TCP_ADD_STATS_USER(TCP_MIB_RTOMAX, TCP_RTO_MAX*1000/HZ); 1157 TCP_ADD_STATS_USER(TCP_MIB_MAXCONN, -1); 1158 } 1159 1160 /* /proc */ 1161 enum tcp_seq_states { 1162 TCP_SEQ_STATE_LISTENING, 1163 TCP_SEQ_STATE_OPENREQ, 1164 TCP_SEQ_STATE_ESTABLISHED, 1165 TCP_SEQ_STATE_TIME_WAIT, 1166 }; 1167 1168 struct tcp_seq_afinfo { 1169 struct module *owner; 1170 char *name; 1171 sa_family_t family; 1172 int (*seq_show) (struct seq_file *m, void *v); 1173 struct file_operations *seq_fops; 1174 }; 1175 1176 struct tcp_iter_state { 1177 sa_family_t family; 1178 enum tcp_seq_states state; 1179 struct sock *syn_wait_sk; 1180 int bucket, sbucket, num, uid; 1181 struct seq_operations seq_ops; 1182 }; 1183 1184 extern int tcp_proc_register(struct tcp_seq_afinfo *afinfo); 1185 extern void tcp_proc_unregister(struct tcp_seq_afinfo *afinfo); 1186 1187 extern struct request_sock_ops tcp_request_sock_ops; 1188 1189 extern int tcp_v4_destroy_sock(struct sock *sk); 1190 1191 #ifdef CONFIG_PROC_FS 1192 extern int tcp4_proc_init(void); 1193 extern void tcp4_proc_exit(void); 1194 #endif 1195 1196 extern void tcp_v4_init(struct net_proto_family *ops); 1197 extern void tcp_init(void); 1198 1199 #endif /* _TCP_H */ 1200