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 #include <linux/skbuff.h> 31 32 #include <net/inet_connection_sock.h> 33 #include <net/inet_timewait_sock.h> 34 #include <net/inet_hashtables.h> 35 #include <net/checksum.h> 36 #include <net/request_sock.h> 37 #include <net/sock.h> 38 #include <net/snmp.h> 39 #include <net/ip.h> 40 #include <net/tcp_states.h> 41 42 #include <linux/seq_file.h> 43 44 extern struct inet_hashinfo tcp_hashinfo; 45 46 extern atomic_t tcp_orphan_count; 47 extern void tcp_time_wait(struct sock *sk, int state, int timeo); 48 49 #define MAX_TCP_HEADER (128 + MAX_HEADER) 50 51 /* 52 * Never offer a window over 32767 without using window scaling. Some 53 * poor stacks do signed 16bit maths! 54 */ 55 #define MAX_TCP_WINDOW 32767U 56 57 /* Minimal accepted MSS. It is (60+60+8) - (20+20). */ 58 #define TCP_MIN_MSS 88U 59 60 /* Minimal RCV_MSS. */ 61 #define TCP_MIN_RCVMSS 536U 62 63 /* After receiving this amount of duplicate ACKs fast retransmit starts. */ 64 #define TCP_FASTRETRANS_THRESH 3 65 66 /* Maximal reordering. */ 67 #define TCP_MAX_REORDERING 127 68 69 /* Maximal number of ACKs sent quickly to accelerate slow-start. */ 70 #define TCP_MAX_QUICKACKS 16U 71 72 /* urg_data states */ 73 #define TCP_URG_VALID 0x0100 74 #define TCP_URG_NOTYET 0x0200 75 #define TCP_URG_READ 0x0400 76 77 #define TCP_RETR1 3 /* 78 * This is how many retries it does before it 79 * tries to figure out if the gateway is 80 * down. Minimal RFC value is 3; it corresponds 81 * to ~3sec-8min depending on RTO. 82 */ 83 84 #define TCP_RETR2 15 /* 85 * This should take at least 86 * 90 minutes to time out. 87 * RFC1122 says that the limit is 100 sec. 88 * 15 is ~13-30min depending on RTO. 89 */ 90 91 #define TCP_SYN_RETRIES 5 /* number of times to retry active opening a 92 * connection: ~180sec is RFC minimum */ 93 94 #define TCP_SYNACK_RETRIES 5 /* number of times to retry passive opening a 95 * connection: ~180sec is RFC minimum */ 96 97 98 #define TCP_ORPHAN_RETRIES 7 /* number of times to retry on an orphaned 99 * socket. 7 is ~50sec-16min. 100 */ 101 102 103 #define TCP_TIMEWAIT_LEN (60*HZ) /* how long to wait to destroy TIME-WAIT 104 * state, about 60 seconds */ 105 #define TCP_FIN_TIMEOUT TCP_TIMEWAIT_LEN 106 /* BSD style FIN_WAIT2 deadlock breaker. 107 * It used to be 3min, new value is 60sec, 108 * to combine FIN-WAIT-2 timeout with 109 * TIME-WAIT timer. 110 */ 111 112 #define TCP_DELACK_MAX ((unsigned)(HZ/5)) /* maximal time to delay before sending an ACK */ 113 #if HZ >= 100 114 #define TCP_DELACK_MIN ((unsigned)(HZ/25)) /* minimal time to delay before sending an ACK */ 115 #define TCP_ATO_MIN ((unsigned)(HZ/25)) 116 #else 117 #define TCP_DELACK_MIN 4U 118 #define TCP_ATO_MIN 4U 119 #endif 120 #define TCP_RTO_MAX ((unsigned)(120*HZ)) 121 #define TCP_RTO_MIN ((unsigned)(HZ/5)) 122 #define TCP_TIMEOUT_INIT ((unsigned)(3*HZ)) /* RFC 1122 initial RTO value */ 123 124 #define TCP_RESOURCE_PROBE_INTERVAL ((unsigned)(HZ/2U)) /* Maximal interval between probes 125 * for local resources. 126 */ 127 128 #define TCP_KEEPALIVE_TIME (120*60*HZ) /* two hours */ 129 #define TCP_KEEPALIVE_PROBES 9 /* Max of 9 keepalive probes */ 130 #define TCP_KEEPALIVE_INTVL (75*HZ) 131 132 #define MAX_TCP_KEEPIDLE 32767 133 #define MAX_TCP_KEEPINTVL 32767 134 #define MAX_TCP_KEEPCNT 127 135 #define MAX_TCP_SYNCNT 127 136 137 #define TCP_SYNQ_INTERVAL (HZ/5) /* Period of SYNACK timer */ 138 #define TCP_SYNQ_HSIZE 512 /* Size of SYNACK hash table */ 139 140 #define TCP_PAWS_24DAYS (60 * 60 * 24 * 24) 141 #define TCP_PAWS_MSL 60 /* Per-host timestamps are invalidated 142 * after this time. It should be equal 143 * (or greater than) TCP_TIMEWAIT_LEN 144 * to provide reliability equal to one 145 * provided by timewait state. 146 */ 147 #define TCP_PAWS_WINDOW 1 /* Replay window for per-host 148 * timestamps. It must be less than 149 * minimal timewait lifetime. 150 */ 151 /* 152 * TCP option 153 */ 154 155 #define TCPOPT_NOP 1 /* Padding */ 156 #define TCPOPT_EOL 0 /* End of options */ 157 #define TCPOPT_MSS 2 /* Segment size negotiating */ 158 #define TCPOPT_WINDOW 3 /* Window scaling */ 159 #define TCPOPT_SACK_PERM 4 /* SACK Permitted */ 160 #define TCPOPT_SACK 5 /* SACK Block */ 161 #define TCPOPT_TIMESTAMP 8 /* Better RTT estimations/PAWS */ 162 163 /* 164 * TCP option lengths 165 */ 166 167 #define TCPOLEN_MSS 4 168 #define TCPOLEN_WINDOW 3 169 #define TCPOLEN_SACK_PERM 2 170 #define TCPOLEN_TIMESTAMP 10 171 172 /* But this is what stacks really send out. */ 173 #define TCPOLEN_TSTAMP_ALIGNED 12 174 #define TCPOLEN_WSCALE_ALIGNED 4 175 #define TCPOLEN_SACKPERM_ALIGNED 4 176 #define TCPOLEN_SACK_BASE 2 177 #define TCPOLEN_SACK_BASE_ALIGNED 4 178 #define TCPOLEN_SACK_PERBLOCK 8 179 180 /* Flags in tp->nonagle */ 181 #define TCP_NAGLE_OFF 1 /* Nagle's algo is disabled */ 182 #define TCP_NAGLE_CORK 2 /* Socket is corked */ 183 #define TCP_NAGLE_PUSH 4 /* Cork is overridden for already queued data */ 184 185 extern struct inet_timewait_death_row tcp_death_row; 186 187 /* sysctl variables for tcp */ 188 extern int sysctl_tcp_timestamps; 189 extern int sysctl_tcp_window_scaling; 190 extern int sysctl_tcp_sack; 191 extern int sysctl_tcp_fin_timeout; 192 extern int sysctl_tcp_keepalive_time; 193 extern int sysctl_tcp_keepalive_probes; 194 extern int sysctl_tcp_keepalive_intvl; 195 extern int sysctl_tcp_syn_retries; 196 extern int sysctl_tcp_synack_retries; 197 extern int sysctl_tcp_retries1; 198 extern int sysctl_tcp_retries2; 199 extern int sysctl_tcp_orphan_retries; 200 extern int sysctl_tcp_syncookies; 201 extern int sysctl_tcp_retrans_collapse; 202 extern int sysctl_tcp_stdurg; 203 extern int sysctl_tcp_rfc1337; 204 extern int sysctl_tcp_abort_on_overflow; 205 extern int sysctl_tcp_max_orphans; 206 extern int sysctl_tcp_fack; 207 extern int sysctl_tcp_reordering; 208 extern int sysctl_tcp_ecn; 209 extern int sysctl_tcp_dsack; 210 extern int sysctl_tcp_mem[3]; 211 extern int sysctl_tcp_wmem[3]; 212 extern int sysctl_tcp_rmem[3]; 213 extern int sysctl_tcp_app_win; 214 extern int sysctl_tcp_adv_win_scale; 215 extern int sysctl_tcp_tw_reuse; 216 extern int sysctl_tcp_frto; 217 extern int sysctl_tcp_low_latency; 218 extern int sysctl_tcp_nometrics_save; 219 extern int sysctl_tcp_moderate_rcvbuf; 220 extern int sysctl_tcp_tso_win_divisor; 221 extern int sysctl_tcp_abc; 222 223 extern atomic_t tcp_memory_allocated; 224 extern atomic_t tcp_sockets_allocated; 225 extern int tcp_memory_pressure; 226 227 /* 228 * Pointers to address related TCP functions 229 * (i.e. things that depend on the address family) 230 */ 231 232 struct tcp_func { 233 int (*queue_xmit) (struct sk_buff *skb, 234 int ipfragok); 235 236 void (*send_check) (struct sock *sk, 237 struct tcphdr *th, 238 int len, 239 struct sk_buff *skb); 240 241 int (*rebuild_header) (struct sock *sk); 242 243 int (*conn_request) (struct sock *sk, 244 struct sk_buff *skb); 245 246 struct sock * (*syn_recv_sock) (struct sock *sk, 247 struct sk_buff *skb, 248 struct request_sock *req, 249 struct dst_entry *dst); 250 251 int (*remember_stamp) (struct sock *sk); 252 253 __u16 net_header_len; 254 255 int (*setsockopt) (struct sock *sk, 256 int level, 257 int optname, 258 char __user *optval, 259 int optlen); 260 261 int (*getsockopt) (struct sock *sk, 262 int level, 263 int optname, 264 char __user *optval, 265 int __user *optlen); 266 267 268 void (*addr2sockaddr) (struct sock *sk, 269 struct sockaddr *); 270 271 int sockaddr_len; 272 }; 273 274 /* 275 * The next routines deal with comparing 32 bit unsigned ints 276 * and worry about wraparound (automatic with unsigned arithmetic). 277 */ 278 279 static inline int before(__u32 seq1, __u32 seq2) 280 { 281 return (__s32)(seq1-seq2) < 0; 282 } 283 284 static inline int after(__u32 seq1, __u32 seq2) 285 { 286 return (__s32)(seq2-seq1) < 0; 287 } 288 289 290 /* is s2<=s1<=s3 ? */ 291 static inline int between(__u32 seq1, __u32 seq2, __u32 seq3) 292 { 293 return seq3 - seq2 >= seq1 - seq2; 294 } 295 296 297 extern struct proto tcp_prot; 298 299 DECLARE_SNMP_STAT(struct tcp_mib, tcp_statistics); 300 #define TCP_INC_STATS(field) SNMP_INC_STATS(tcp_statistics, field) 301 #define TCP_INC_STATS_BH(field) SNMP_INC_STATS_BH(tcp_statistics, field) 302 #define TCP_INC_STATS_USER(field) SNMP_INC_STATS_USER(tcp_statistics, field) 303 #define TCP_DEC_STATS(field) SNMP_DEC_STATS(tcp_statistics, field) 304 #define TCP_ADD_STATS_BH(field, val) SNMP_ADD_STATS_BH(tcp_statistics, field, val) 305 #define TCP_ADD_STATS_USER(field, val) SNMP_ADD_STATS_USER(tcp_statistics, field, val) 306 307 extern void tcp_v4_err(struct sk_buff *skb, u32); 308 309 extern void tcp_shutdown (struct sock *sk, int how); 310 311 extern int tcp_v4_rcv(struct sk_buff *skb); 312 313 extern int tcp_v4_remember_stamp(struct sock *sk); 314 315 extern int tcp_v4_tw_remember_stamp(struct inet_timewait_sock *tw); 316 317 extern int tcp_sendmsg(struct kiocb *iocb, struct sock *sk, 318 struct msghdr *msg, size_t size); 319 extern ssize_t tcp_sendpage(struct socket *sock, struct page *page, int offset, size_t size, int flags); 320 321 extern int tcp_ioctl(struct sock *sk, 322 int cmd, 323 unsigned long arg); 324 325 extern int tcp_rcv_state_process(struct sock *sk, 326 struct sk_buff *skb, 327 struct tcphdr *th, 328 unsigned len); 329 330 extern int tcp_rcv_established(struct sock *sk, 331 struct sk_buff *skb, 332 struct tcphdr *th, 333 unsigned len); 334 335 extern void tcp_rcv_space_adjust(struct sock *sk); 336 337 static inline void tcp_dec_quickack_mode(struct sock *sk, 338 const unsigned int pkts) 339 { 340 struct inet_connection_sock *icsk = inet_csk(sk); 341 342 if (icsk->icsk_ack.quick) { 343 if (pkts >= icsk->icsk_ack.quick) { 344 icsk->icsk_ack.quick = 0; 345 /* Leaving quickack mode we deflate ATO. */ 346 icsk->icsk_ack.ato = TCP_ATO_MIN; 347 } else 348 icsk->icsk_ack.quick -= pkts; 349 } 350 } 351 352 extern void tcp_enter_quickack_mode(struct sock *sk); 353 354 static inline void tcp_clear_options(struct tcp_options_received *rx_opt) 355 { 356 rx_opt->tstamp_ok = rx_opt->sack_ok = rx_opt->wscale_ok = rx_opt->snd_wscale = 0; 357 } 358 359 enum tcp_tw_status 360 { 361 TCP_TW_SUCCESS = 0, 362 TCP_TW_RST = 1, 363 TCP_TW_ACK = 2, 364 TCP_TW_SYN = 3 365 }; 366 367 368 extern enum tcp_tw_status tcp_timewait_state_process(struct inet_timewait_sock *tw, 369 struct sk_buff *skb, 370 const struct tcphdr *th); 371 372 extern struct sock * tcp_check_req(struct sock *sk,struct sk_buff *skb, 373 struct request_sock *req, 374 struct request_sock **prev); 375 extern int tcp_child_process(struct sock *parent, 376 struct sock *child, 377 struct sk_buff *skb); 378 extern void tcp_enter_frto(struct sock *sk); 379 extern void tcp_enter_loss(struct sock *sk, int how); 380 extern void tcp_clear_retrans(struct tcp_sock *tp); 381 extern void tcp_update_metrics(struct sock *sk); 382 383 extern void tcp_close(struct sock *sk, 384 long timeout); 385 extern unsigned int tcp_poll(struct file * file, struct socket *sock, struct poll_table_struct *wait); 386 387 extern int tcp_getsockopt(struct sock *sk, int level, 388 int optname, 389 char __user *optval, 390 int __user *optlen); 391 extern int tcp_setsockopt(struct sock *sk, int level, 392 int optname, char __user *optval, 393 int optlen); 394 extern void tcp_set_keepalive(struct sock *sk, int val); 395 extern int tcp_recvmsg(struct kiocb *iocb, struct sock *sk, 396 struct msghdr *msg, 397 size_t len, int nonblock, 398 int flags, int *addr_len); 399 400 extern void tcp_parse_options(struct sk_buff *skb, 401 struct tcp_options_received *opt_rx, 402 int estab); 403 404 /* 405 * TCP v4 functions exported for the inet6 API 406 */ 407 408 extern void tcp_v4_send_check(struct sock *sk, 409 struct tcphdr *th, int len, 410 struct sk_buff *skb); 411 412 extern int tcp_v4_conn_request(struct sock *sk, 413 struct sk_buff *skb); 414 415 extern struct sock * tcp_create_openreq_child(struct sock *sk, 416 struct request_sock *req, 417 struct sk_buff *skb); 418 419 extern struct sock * tcp_v4_syn_recv_sock(struct sock *sk, 420 struct sk_buff *skb, 421 struct request_sock *req, 422 struct dst_entry *dst); 423 424 extern int tcp_v4_do_rcv(struct sock *sk, 425 struct sk_buff *skb); 426 427 extern int tcp_v4_connect(struct sock *sk, 428 struct sockaddr *uaddr, 429 int addr_len); 430 431 extern int tcp_connect(struct sock *sk); 432 433 extern struct sk_buff * tcp_make_synack(struct sock *sk, 434 struct dst_entry *dst, 435 struct request_sock *req); 436 437 extern int tcp_disconnect(struct sock *sk, int flags); 438 439 extern void tcp_unhash(struct sock *sk); 440 441 extern int tcp_v4_hash_connecting(struct sock *sk); 442 443 444 /* From syncookies.c */ 445 extern struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb, 446 struct ip_options *opt); 447 extern __u32 cookie_v4_init_sequence(struct sock *sk, struct sk_buff *skb, 448 __u16 *mss); 449 450 /* tcp_output.c */ 451 452 extern void __tcp_push_pending_frames(struct sock *sk, struct tcp_sock *tp, 453 unsigned int cur_mss, int nonagle); 454 extern int tcp_may_send_now(struct sock *sk, struct tcp_sock *tp); 455 extern int tcp_retransmit_skb(struct sock *, struct sk_buff *); 456 extern void tcp_xmit_retransmit_queue(struct sock *); 457 extern void tcp_simple_retransmit(struct sock *); 458 extern int tcp_trim_head(struct sock *, struct sk_buff *, u32); 459 extern int tcp_fragment(struct sock *, struct sk_buff *, u32, unsigned int); 460 461 extern void tcp_send_probe0(struct sock *); 462 extern void tcp_send_partial(struct sock *); 463 extern int tcp_write_wakeup(struct sock *); 464 extern void tcp_send_fin(struct sock *sk); 465 extern void tcp_send_active_reset(struct sock *sk, gfp_t priority); 466 extern int tcp_send_synack(struct sock *); 467 extern void tcp_push_one(struct sock *, unsigned int mss_now); 468 extern void tcp_send_ack(struct sock *sk); 469 extern void tcp_send_delayed_ack(struct sock *sk); 470 471 /* tcp_input.c */ 472 extern void tcp_cwnd_application_limited(struct sock *sk); 473 474 /* tcp_timer.c */ 475 extern void tcp_init_xmit_timers(struct sock *); 476 static inline void tcp_clear_xmit_timers(struct sock *sk) 477 { 478 inet_csk_clear_xmit_timers(sk); 479 } 480 481 extern unsigned int tcp_sync_mss(struct sock *sk, u32 pmtu); 482 extern unsigned int tcp_current_mss(struct sock *sk, int large); 483 484 /* tcp.c */ 485 extern void tcp_get_info(struct sock *, struct tcp_info *); 486 487 /* Read 'sendfile()'-style from a TCP socket */ 488 typedef int (*sk_read_actor_t)(read_descriptor_t *, struct sk_buff *, 489 unsigned int, size_t); 490 extern int tcp_read_sock(struct sock *sk, read_descriptor_t *desc, 491 sk_read_actor_t recv_actor); 492 493 /* Initialize RCV_MSS value. 494 * RCV_MSS is an our guess about MSS used by the peer. 495 * We haven't any direct information about the MSS. 496 * It's better to underestimate the RCV_MSS rather than overestimate. 497 * Overestimations make us ACKing less frequently than needed. 498 * Underestimations are more easy to detect and fix by tcp_measure_rcv_mss(). 499 */ 500 501 static inline void tcp_initialize_rcv_mss(struct sock *sk) 502 { 503 struct tcp_sock *tp = tcp_sk(sk); 504 unsigned int hint = min_t(unsigned int, tp->advmss, tp->mss_cache); 505 506 hint = min(hint, tp->rcv_wnd/2); 507 hint = min(hint, TCP_MIN_RCVMSS); 508 hint = max(hint, TCP_MIN_MSS); 509 510 inet_csk(sk)->icsk_ack.rcv_mss = hint; 511 } 512 513 static __inline__ void __tcp_fast_path_on(struct tcp_sock *tp, u32 snd_wnd) 514 { 515 tp->pred_flags = htonl((tp->tcp_header_len << 26) | 516 ntohl(TCP_FLAG_ACK) | 517 snd_wnd); 518 } 519 520 static __inline__ void tcp_fast_path_on(struct tcp_sock *tp) 521 { 522 __tcp_fast_path_on(tp, tp->snd_wnd >> tp->rx_opt.snd_wscale); 523 } 524 525 static inline void tcp_fast_path_check(struct sock *sk, struct tcp_sock *tp) 526 { 527 if (skb_queue_empty(&tp->out_of_order_queue) && 528 tp->rcv_wnd && 529 atomic_read(&sk->sk_rmem_alloc) < sk->sk_rcvbuf && 530 !tp->urg_data) 531 tcp_fast_path_on(tp); 532 } 533 534 /* Compute the actual receive window we are currently advertising. 535 * Rcv_nxt can be after the window if our peer push more data 536 * than the offered window. 537 */ 538 static __inline__ u32 tcp_receive_window(const struct tcp_sock *tp) 539 { 540 s32 win = tp->rcv_wup + tp->rcv_wnd - tp->rcv_nxt; 541 542 if (win < 0) 543 win = 0; 544 return (u32) win; 545 } 546 547 /* Choose a new window, without checks for shrinking, and without 548 * scaling applied to the result. The caller does these things 549 * if necessary. This is a "raw" window selection. 550 */ 551 extern u32 __tcp_select_window(struct sock *sk); 552 553 /* TCP timestamps are only 32-bits, this causes a slight 554 * complication on 64-bit systems since we store a snapshot 555 * of jiffies in the buffer control blocks below. We decided 556 * to use only the low 32-bits of jiffies and hide the ugly 557 * casts with the following macro. 558 */ 559 #define tcp_time_stamp ((__u32)(jiffies)) 560 561 /* This is what the send packet queuing engine uses to pass 562 * TCP per-packet control information to the transmission 563 * code. We also store the host-order sequence numbers in 564 * here too. This is 36 bytes on 32-bit architectures, 565 * 40 bytes on 64-bit machines, if this grows please adjust 566 * skbuff.h:skbuff->cb[xxx] size appropriately. 567 */ 568 struct tcp_skb_cb { 569 union { 570 struct inet_skb_parm h4; 571 #if defined(CONFIG_IPV6) || defined (CONFIG_IPV6_MODULE) 572 struct inet6_skb_parm h6; 573 #endif 574 } header; /* For incoming frames */ 575 __u32 seq; /* Starting sequence number */ 576 __u32 end_seq; /* SEQ + FIN + SYN + datalen */ 577 __u32 when; /* used to compute rtt's */ 578 __u8 flags; /* TCP header flags. */ 579 580 /* NOTE: These must match up to the flags byte in a 581 * real TCP header. 582 */ 583 #define TCPCB_FLAG_FIN 0x01 584 #define TCPCB_FLAG_SYN 0x02 585 #define TCPCB_FLAG_RST 0x04 586 #define TCPCB_FLAG_PSH 0x08 587 #define TCPCB_FLAG_ACK 0x10 588 #define TCPCB_FLAG_URG 0x20 589 #define TCPCB_FLAG_ECE 0x40 590 #define TCPCB_FLAG_CWR 0x80 591 592 __u8 sacked; /* State flags for SACK/FACK. */ 593 #define TCPCB_SACKED_ACKED 0x01 /* SKB ACK'd by a SACK block */ 594 #define TCPCB_SACKED_RETRANS 0x02 /* SKB retransmitted */ 595 #define TCPCB_LOST 0x04 /* SKB is lost */ 596 #define TCPCB_TAGBITS 0x07 /* All tag bits */ 597 598 #define TCPCB_EVER_RETRANS 0x80 /* Ever retransmitted frame */ 599 #define TCPCB_RETRANS (TCPCB_SACKED_RETRANS|TCPCB_EVER_RETRANS) 600 601 #define TCPCB_URG 0x20 /* Urgent pointer advanced here */ 602 603 #define TCPCB_AT_TAIL (TCPCB_URG) 604 605 __u16 urg_ptr; /* Valid w/URG flags is set. */ 606 __u32 ack_seq; /* Sequence number ACK'd */ 607 }; 608 609 #define TCP_SKB_CB(__skb) ((struct tcp_skb_cb *)&((__skb)->cb[0])) 610 611 #include <net/tcp_ecn.h> 612 613 /* Due to TSO, an SKB can be composed of multiple actual 614 * packets. To keep these tracked properly, we use this. 615 */ 616 static inline int tcp_skb_pcount(const struct sk_buff *skb) 617 { 618 return skb_shinfo(skb)->tso_segs; 619 } 620 621 /* This is valid iff tcp_skb_pcount() > 1. */ 622 static inline int tcp_skb_mss(const struct sk_buff *skb) 623 { 624 return skb_shinfo(skb)->tso_size; 625 } 626 627 static inline void tcp_dec_pcount_approx(__u32 *count, 628 const struct sk_buff *skb) 629 { 630 if (*count) { 631 *count -= tcp_skb_pcount(skb); 632 if ((int)*count < 0) 633 *count = 0; 634 } 635 } 636 637 static inline void tcp_packets_out_inc(struct sock *sk, 638 struct tcp_sock *tp, 639 const struct sk_buff *skb) 640 { 641 int orig = tp->packets_out; 642 643 tp->packets_out += tcp_skb_pcount(skb); 644 if (!orig) 645 inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, 646 inet_csk(sk)->icsk_rto, TCP_RTO_MAX); 647 } 648 649 static inline void tcp_packets_out_dec(struct tcp_sock *tp, 650 const struct sk_buff *skb) 651 { 652 tp->packets_out -= tcp_skb_pcount(skb); 653 } 654 655 /* Events passed to congestion control interface */ 656 enum tcp_ca_event { 657 CA_EVENT_TX_START, /* first transmit when no packets in flight */ 658 CA_EVENT_CWND_RESTART, /* congestion window restart */ 659 CA_EVENT_COMPLETE_CWR, /* end of congestion recovery */ 660 CA_EVENT_FRTO, /* fast recovery timeout */ 661 CA_EVENT_LOSS, /* loss timeout */ 662 CA_EVENT_FAST_ACK, /* in sequence ack */ 663 CA_EVENT_SLOW_ACK, /* other ack */ 664 }; 665 666 /* 667 * Interface for adding new TCP congestion control handlers 668 */ 669 #define TCP_CA_NAME_MAX 16 670 struct tcp_congestion_ops { 671 struct list_head list; 672 673 /* initialize private data (optional) */ 674 void (*init)(struct sock *sk); 675 /* cleanup private data (optional) */ 676 void (*release)(struct sock *sk); 677 678 /* return slow start threshold (required) */ 679 u32 (*ssthresh)(struct sock *sk); 680 /* lower bound for congestion window (optional) */ 681 u32 (*min_cwnd)(struct sock *sk); 682 /* do new cwnd calculation (required) */ 683 void (*cong_avoid)(struct sock *sk, u32 ack, 684 u32 rtt, u32 in_flight, int good_ack); 685 /* round trip time sample per acked packet (optional) */ 686 void (*rtt_sample)(struct sock *sk, u32 usrtt); 687 /* call before changing ca_state (optional) */ 688 void (*set_state)(struct sock *sk, u8 new_state); 689 /* call when cwnd event occurs (optional) */ 690 void (*cwnd_event)(struct sock *sk, enum tcp_ca_event ev); 691 /* new value of cwnd after loss (optional) */ 692 u32 (*undo_cwnd)(struct sock *sk); 693 /* hook for packet ack accounting (optional) */ 694 void (*pkts_acked)(struct sock *sk, u32 num_acked); 695 /* get info for inet_diag (optional) */ 696 void (*get_info)(struct sock *sk, u32 ext, struct sk_buff *skb); 697 698 char name[TCP_CA_NAME_MAX]; 699 struct module *owner; 700 }; 701 702 extern int tcp_register_congestion_control(struct tcp_congestion_ops *type); 703 extern void tcp_unregister_congestion_control(struct tcp_congestion_ops *type); 704 705 extern void tcp_init_congestion_control(struct sock *sk); 706 extern void tcp_cleanup_congestion_control(struct sock *sk); 707 extern int tcp_set_default_congestion_control(const char *name); 708 extern void tcp_get_default_congestion_control(char *name); 709 extern int tcp_set_congestion_control(struct sock *sk, const char *name); 710 711 extern struct tcp_congestion_ops tcp_init_congestion_ops; 712 extern u32 tcp_reno_ssthresh(struct sock *sk); 713 extern void tcp_reno_cong_avoid(struct sock *sk, u32 ack, 714 u32 rtt, u32 in_flight, int flag); 715 extern u32 tcp_reno_min_cwnd(struct sock *sk); 716 extern struct tcp_congestion_ops tcp_reno; 717 718 static inline void tcp_set_ca_state(struct sock *sk, const u8 ca_state) 719 { 720 struct inet_connection_sock *icsk = inet_csk(sk); 721 722 if (icsk->icsk_ca_ops->set_state) 723 icsk->icsk_ca_ops->set_state(sk, ca_state); 724 icsk->icsk_ca_state = ca_state; 725 } 726 727 static inline void tcp_ca_event(struct sock *sk, const enum tcp_ca_event event) 728 { 729 const struct inet_connection_sock *icsk = inet_csk(sk); 730 731 if (icsk->icsk_ca_ops->cwnd_event) 732 icsk->icsk_ca_ops->cwnd_event(sk, event); 733 } 734 735 /* This determines how many packets are "in the network" to the best 736 * of our knowledge. In many cases it is conservative, but where 737 * detailed information is available from the receiver (via SACK 738 * blocks etc.) we can make more aggressive calculations. 739 * 740 * Use this for decisions involving congestion control, use just 741 * tp->packets_out to determine if the send queue is empty or not. 742 * 743 * Read this equation as: 744 * 745 * "Packets sent once on transmission queue" MINUS 746 * "Packets left network, but not honestly ACKed yet" PLUS 747 * "Packets fast retransmitted" 748 */ 749 static __inline__ unsigned int tcp_packets_in_flight(const struct tcp_sock *tp) 750 { 751 return (tp->packets_out - tp->left_out + tp->retrans_out); 752 } 753 754 /* If cwnd > ssthresh, we may raise ssthresh to be half-way to cwnd. 755 * The exception is rate halving phase, when cwnd is decreasing towards 756 * ssthresh. 757 */ 758 static inline __u32 tcp_current_ssthresh(const struct sock *sk) 759 { 760 const struct tcp_sock *tp = tcp_sk(sk); 761 if ((1 << inet_csk(sk)->icsk_ca_state) & (TCPF_CA_CWR | TCPF_CA_Recovery)) 762 return tp->snd_ssthresh; 763 else 764 return max(tp->snd_ssthresh, 765 ((tp->snd_cwnd >> 1) + 766 (tp->snd_cwnd >> 2))); 767 } 768 769 /* 770 * Linear increase during slow start 771 */ 772 static inline void tcp_slow_start(struct tcp_sock *tp) 773 { 774 if (sysctl_tcp_abc) { 775 /* RFC3465: Slow Start 776 * TCP sender SHOULD increase cwnd by the number of 777 * previously unacknowledged bytes ACKed by each incoming 778 * acknowledgment, provided the increase is not more than L 779 */ 780 if (tp->bytes_acked < tp->mss_cache) 781 return; 782 783 /* We MAY increase by 2 if discovered delayed ack */ 784 if (sysctl_tcp_abc > 1 && tp->bytes_acked > 2*tp->mss_cache) { 785 if (tp->snd_cwnd < tp->snd_cwnd_clamp) 786 tp->snd_cwnd++; 787 } 788 } 789 tp->bytes_acked = 0; 790 791 if (tp->snd_cwnd < tp->snd_cwnd_clamp) 792 tp->snd_cwnd++; 793 } 794 795 796 static inline void tcp_sync_left_out(struct tcp_sock *tp) 797 { 798 if (tp->rx_opt.sack_ok && 799 (tp->sacked_out >= tp->packets_out - tp->lost_out)) 800 tp->sacked_out = tp->packets_out - tp->lost_out; 801 tp->left_out = tp->sacked_out + tp->lost_out; 802 } 803 804 /* Set slow start threshold and cwnd not falling to slow start */ 805 static inline void __tcp_enter_cwr(struct sock *sk) 806 { 807 const struct inet_connection_sock *icsk = inet_csk(sk); 808 struct tcp_sock *tp = tcp_sk(sk); 809 810 tp->undo_marker = 0; 811 tp->snd_ssthresh = icsk->icsk_ca_ops->ssthresh(sk); 812 tp->snd_cwnd = min(tp->snd_cwnd, 813 tcp_packets_in_flight(tp) + 1U); 814 tp->snd_cwnd_cnt = 0; 815 tp->high_seq = tp->snd_nxt; 816 tp->snd_cwnd_stamp = tcp_time_stamp; 817 TCP_ECN_queue_cwr(tp); 818 } 819 820 static inline void tcp_enter_cwr(struct sock *sk) 821 { 822 struct tcp_sock *tp = tcp_sk(sk); 823 824 tp->prior_ssthresh = 0; 825 tp->bytes_acked = 0; 826 if (inet_csk(sk)->icsk_ca_state < TCP_CA_CWR) { 827 __tcp_enter_cwr(sk); 828 tcp_set_ca_state(sk, TCP_CA_CWR); 829 } 830 } 831 832 extern __u32 tcp_init_cwnd(struct tcp_sock *tp, struct dst_entry *dst); 833 834 /* Slow start with delack produces 3 packets of burst, so that 835 * it is safe "de facto". 836 */ 837 static __inline__ __u32 tcp_max_burst(const struct tcp_sock *tp) 838 { 839 return 3; 840 } 841 842 /* RFC2861 Check whether we are limited by application or congestion window 843 * This is the inverse of cwnd check in tcp_tso_should_defer 844 */ 845 static inline int tcp_is_cwnd_limited(const struct sock *sk, u32 in_flight) 846 { 847 const struct tcp_sock *tp = tcp_sk(sk); 848 u32 left; 849 850 if (in_flight >= tp->snd_cwnd) 851 return 1; 852 853 if (!(sk->sk_route_caps & NETIF_F_TSO)) 854 return 0; 855 856 left = tp->snd_cwnd - in_flight; 857 if (sysctl_tcp_tso_win_divisor) 858 return left * sysctl_tcp_tso_win_divisor < tp->snd_cwnd; 859 else 860 return left <= tcp_max_burst(tp); 861 } 862 863 static __inline__ void tcp_minshall_update(struct tcp_sock *tp, int mss, 864 const struct sk_buff *skb) 865 { 866 if (skb->len < mss) 867 tp->snd_sml = TCP_SKB_CB(skb)->end_seq; 868 } 869 870 static __inline__ void tcp_check_probe_timer(struct sock *sk, struct tcp_sock *tp) 871 { 872 const struct inet_connection_sock *icsk = inet_csk(sk); 873 if (!tp->packets_out && !icsk->icsk_pending) 874 inet_csk_reset_xmit_timer(sk, ICSK_TIME_PROBE0, 875 icsk->icsk_rto, TCP_RTO_MAX); 876 } 877 878 static __inline__ void tcp_push_pending_frames(struct sock *sk, 879 struct tcp_sock *tp) 880 { 881 __tcp_push_pending_frames(sk, tp, tcp_current_mss(sk, 1), tp->nonagle); 882 } 883 884 static __inline__ void tcp_init_wl(struct tcp_sock *tp, u32 ack, u32 seq) 885 { 886 tp->snd_wl1 = seq; 887 } 888 889 static __inline__ void tcp_update_wl(struct tcp_sock *tp, u32 ack, u32 seq) 890 { 891 tp->snd_wl1 = seq; 892 } 893 894 /* 895 * Calculate(/check) TCP checksum 896 */ 897 static __inline__ u16 tcp_v4_check(struct tcphdr *th, int len, 898 unsigned long saddr, unsigned long daddr, 899 unsigned long base) 900 { 901 return csum_tcpudp_magic(saddr,daddr,len,IPPROTO_TCP,base); 902 } 903 904 static __inline__ int __tcp_checksum_complete(struct sk_buff *skb) 905 { 906 return __skb_checksum_complete(skb); 907 } 908 909 static __inline__ int tcp_checksum_complete(struct sk_buff *skb) 910 { 911 return skb->ip_summed != CHECKSUM_UNNECESSARY && 912 __tcp_checksum_complete(skb); 913 } 914 915 /* Prequeue for VJ style copy to user, combined with checksumming. */ 916 917 static __inline__ void tcp_prequeue_init(struct tcp_sock *tp) 918 { 919 tp->ucopy.task = NULL; 920 tp->ucopy.len = 0; 921 tp->ucopy.memory = 0; 922 skb_queue_head_init(&tp->ucopy.prequeue); 923 } 924 925 /* Packet is added to VJ-style prequeue for processing in process 926 * context, if a reader task is waiting. Apparently, this exciting 927 * idea (VJ's mail "Re: query about TCP header on tcp-ip" of 07 Sep 93) 928 * failed somewhere. Latency? Burstiness? Well, at least now we will 929 * see, why it failed. 8)8) --ANK 930 * 931 * NOTE: is this not too big to inline? 932 */ 933 static __inline__ int tcp_prequeue(struct sock *sk, struct sk_buff *skb) 934 { 935 struct tcp_sock *tp = tcp_sk(sk); 936 937 if (!sysctl_tcp_low_latency && tp->ucopy.task) { 938 __skb_queue_tail(&tp->ucopy.prequeue, skb); 939 tp->ucopy.memory += skb->truesize; 940 if (tp->ucopy.memory > sk->sk_rcvbuf) { 941 struct sk_buff *skb1; 942 943 BUG_ON(sock_owned_by_user(sk)); 944 945 while ((skb1 = __skb_dequeue(&tp->ucopy.prequeue)) != NULL) { 946 sk->sk_backlog_rcv(sk, skb1); 947 NET_INC_STATS_BH(LINUX_MIB_TCPPREQUEUEDROPPED); 948 } 949 950 tp->ucopy.memory = 0; 951 } else if (skb_queue_len(&tp->ucopy.prequeue) == 1) { 952 wake_up_interruptible(sk->sk_sleep); 953 if (!inet_csk_ack_scheduled(sk)) 954 inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK, 955 (3 * TCP_RTO_MIN) / 4, 956 TCP_RTO_MAX); 957 } 958 return 1; 959 } 960 return 0; 961 } 962 963 964 #undef STATE_TRACE 965 966 #ifdef STATE_TRACE 967 static const char *statename[]={ 968 "Unused","Established","Syn Sent","Syn Recv", 969 "Fin Wait 1","Fin Wait 2","Time Wait", "Close", 970 "Close Wait","Last ACK","Listen","Closing" 971 }; 972 #endif 973 974 static __inline__ void tcp_set_state(struct sock *sk, int state) 975 { 976 int oldstate = sk->sk_state; 977 978 switch (state) { 979 case TCP_ESTABLISHED: 980 if (oldstate != TCP_ESTABLISHED) 981 TCP_INC_STATS(TCP_MIB_CURRESTAB); 982 break; 983 984 case TCP_CLOSE: 985 if (oldstate == TCP_CLOSE_WAIT || oldstate == TCP_ESTABLISHED) 986 TCP_INC_STATS(TCP_MIB_ESTABRESETS); 987 988 sk->sk_prot->unhash(sk); 989 if (inet_csk(sk)->icsk_bind_hash && 990 !(sk->sk_userlocks & SOCK_BINDPORT_LOCK)) 991 inet_put_port(&tcp_hashinfo, sk); 992 /* fall through */ 993 default: 994 if (oldstate==TCP_ESTABLISHED) 995 TCP_DEC_STATS(TCP_MIB_CURRESTAB); 996 } 997 998 /* Change state AFTER socket is unhashed to avoid closed 999 * socket sitting in hash tables. 1000 */ 1001 sk->sk_state = state; 1002 1003 #ifdef STATE_TRACE 1004 SOCK_DEBUG(sk, "TCP sk=%p, State %s -> %s\n",sk, statename[oldstate],statename[state]); 1005 #endif 1006 } 1007 1008 static __inline__ void tcp_done(struct sock *sk) 1009 { 1010 tcp_set_state(sk, TCP_CLOSE); 1011 tcp_clear_xmit_timers(sk); 1012 1013 sk->sk_shutdown = SHUTDOWN_MASK; 1014 1015 if (!sock_flag(sk, SOCK_DEAD)) 1016 sk->sk_state_change(sk); 1017 else 1018 inet_csk_destroy_sock(sk); 1019 } 1020 1021 static __inline__ void tcp_sack_reset(struct tcp_options_received *rx_opt) 1022 { 1023 rx_opt->dsack = 0; 1024 rx_opt->eff_sacks = 0; 1025 rx_opt->num_sacks = 0; 1026 } 1027 1028 static __inline__ void tcp_build_and_update_options(__u32 *ptr, struct tcp_sock *tp, __u32 tstamp) 1029 { 1030 if (tp->rx_opt.tstamp_ok) { 1031 *ptr++ = __constant_htonl((TCPOPT_NOP << 24) | 1032 (TCPOPT_NOP << 16) | 1033 (TCPOPT_TIMESTAMP << 8) | 1034 TCPOLEN_TIMESTAMP); 1035 *ptr++ = htonl(tstamp); 1036 *ptr++ = htonl(tp->rx_opt.ts_recent); 1037 } 1038 if (tp->rx_opt.eff_sacks) { 1039 struct tcp_sack_block *sp = tp->rx_opt.dsack ? tp->duplicate_sack : tp->selective_acks; 1040 int this_sack; 1041 1042 *ptr++ = __constant_htonl((TCPOPT_NOP << 24) | 1043 (TCPOPT_NOP << 16) | 1044 (TCPOPT_SACK << 8) | 1045 (TCPOLEN_SACK_BASE + 1046 (tp->rx_opt.eff_sacks * TCPOLEN_SACK_PERBLOCK))); 1047 for(this_sack = 0; this_sack < tp->rx_opt.eff_sacks; this_sack++) { 1048 *ptr++ = htonl(sp[this_sack].start_seq); 1049 *ptr++ = htonl(sp[this_sack].end_seq); 1050 } 1051 if (tp->rx_opt.dsack) { 1052 tp->rx_opt.dsack = 0; 1053 tp->rx_opt.eff_sacks--; 1054 } 1055 } 1056 } 1057 1058 /* Construct a tcp options header for a SYN or SYN_ACK packet. 1059 * If this is every changed make sure to change the definition of 1060 * MAX_SYN_SIZE to match the new maximum number of options that you 1061 * can generate. 1062 */ 1063 static inline void tcp_syn_build_options(__u32 *ptr, int mss, int ts, int sack, 1064 int offer_wscale, int wscale, __u32 tstamp, __u32 ts_recent) 1065 { 1066 /* We always get an MSS option. 1067 * The option bytes which will be seen in normal data 1068 * packets should timestamps be used, must be in the MSS 1069 * advertised. But we subtract them from tp->mss_cache so 1070 * that calculations in tcp_sendmsg are simpler etc. 1071 * So account for this fact here if necessary. If we 1072 * don't do this correctly, as a receiver we won't 1073 * recognize data packets as being full sized when we 1074 * should, and thus we won't abide by the delayed ACK 1075 * rules correctly. 1076 * SACKs don't matter, we never delay an ACK when we 1077 * have any of those going out. 1078 */ 1079 *ptr++ = htonl((TCPOPT_MSS << 24) | (TCPOLEN_MSS << 16) | mss); 1080 if (ts) { 1081 if(sack) 1082 *ptr++ = __constant_htonl((TCPOPT_SACK_PERM << 24) | (TCPOLEN_SACK_PERM << 16) | 1083 (TCPOPT_TIMESTAMP << 8) | TCPOLEN_TIMESTAMP); 1084 else 1085 *ptr++ = __constant_htonl((TCPOPT_NOP << 24) | (TCPOPT_NOP << 16) | 1086 (TCPOPT_TIMESTAMP << 8) | TCPOLEN_TIMESTAMP); 1087 *ptr++ = htonl(tstamp); /* TSVAL */ 1088 *ptr++ = htonl(ts_recent); /* TSECR */ 1089 } else if(sack) 1090 *ptr++ = __constant_htonl((TCPOPT_NOP << 24) | (TCPOPT_NOP << 16) | 1091 (TCPOPT_SACK_PERM << 8) | TCPOLEN_SACK_PERM); 1092 if (offer_wscale) 1093 *ptr++ = htonl((TCPOPT_NOP << 24) | (TCPOPT_WINDOW << 16) | (TCPOLEN_WINDOW << 8) | (wscale)); 1094 } 1095 1096 /* Determine a window scaling and initial window to offer. */ 1097 extern void tcp_select_initial_window(int __space, __u32 mss, 1098 __u32 *rcv_wnd, __u32 *window_clamp, 1099 int wscale_ok, __u8 *rcv_wscale); 1100 1101 static inline int tcp_win_from_space(int space) 1102 { 1103 return sysctl_tcp_adv_win_scale<=0 ? 1104 (space>>(-sysctl_tcp_adv_win_scale)) : 1105 space - (space>>sysctl_tcp_adv_win_scale); 1106 } 1107 1108 /* Note: caller must be prepared to deal with negative returns */ 1109 static inline int tcp_space(const struct sock *sk) 1110 { 1111 return tcp_win_from_space(sk->sk_rcvbuf - 1112 atomic_read(&sk->sk_rmem_alloc)); 1113 } 1114 1115 static inline int tcp_full_space(const struct sock *sk) 1116 { 1117 return tcp_win_from_space(sk->sk_rcvbuf); 1118 } 1119 1120 static __inline__ void tcp_openreq_init(struct request_sock *req, 1121 struct tcp_options_received *rx_opt, 1122 struct sk_buff *skb) 1123 { 1124 struct inet_request_sock *ireq = inet_rsk(req); 1125 1126 req->rcv_wnd = 0; /* So that tcp_send_synack() knows! */ 1127 tcp_rsk(req)->rcv_isn = TCP_SKB_CB(skb)->seq; 1128 req->mss = rx_opt->mss_clamp; 1129 req->ts_recent = rx_opt->saw_tstamp ? rx_opt->rcv_tsval : 0; 1130 ireq->tstamp_ok = rx_opt->tstamp_ok; 1131 ireq->sack_ok = rx_opt->sack_ok; 1132 ireq->snd_wscale = rx_opt->snd_wscale; 1133 ireq->wscale_ok = rx_opt->wscale_ok; 1134 ireq->acked = 0; 1135 ireq->ecn_ok = 0; 1136 ireq->rmt_port = skb->h.th->source; 1137 } 1138 1139 extern void tcp_enter_memory_pressure(void); 1140 1141 static inline int keepalive_intvl_when(const struct tcp_sock *tp) 1142 { 1143 return tp->keepalive_intvl ? : sysctl_tcp_keepalive_intvl; 1144 } 1145 1146 static inline int keepalive_time_when(const struct tcp_sock *tp) 1147 { 1148 return tp->keepalive_time ? : sysctl_tcp_keepalive_time; 1149 } 1150 1151 static inline int tcp_fin_time(const struct sock *sk) 1152 { 1153 int fin_timeout = tcp_sk(sk)->linger2 ? : sysctl_tcp_fin_timeout; 1154 const int rto = inet_csk(sk)->icsk_rto; 1155 1156 if (fin_timeout < (rto << 2) - (rto >> 1)) 1157 fin_timeout = (rto << 2) - (rto >> 1); 1158 1159 return fin_timeout; 1160 } 1161 1162 static inline int tcp_paws_check(const struct tcp_options_received *rx_opt, int rst) 1163 { 1164 if ((s32)(rx_opt->rcv_tsval - rx_opt->ts_recent) >= 0) 1165 return 0; 1166 if (xtime.tv_sec >= rx_opt->ts_recent_stamp + TCP_PAWS_24DAYS) 1167 return 0; 1168 1169 /* RST segments are not recommended to carry timestamp, 1170 and, if they do, it is recommended to ignore PAWS because 1171 "their cleanup function should take precedence over timestamps." 1172 Certainly, it is mistake. It is necessary to understand the reasons 1173 of this constraint to relax it: if peer reboots, clock may go 1174 out-of-sync and half-open connections will not be reset. 1175 Actually, the problem would be not existing if all 1176 the implementations followed draft about maintaining clock 1177 via reboots. Linux-2.2 DOES NOT! 1178 1179 However, we can relax time bounds for RST segments to MSL. 1180 */ 1181 if (rst && xtime.tv_sec >= rx_opt->ts_recent_stamp + TCP_PAWS_MSL) 1182 return 0; 1183 return 1; 1184 } 1185 1186 #define TCP_CHECK_TIMER(sk) do { } while (0) 1187 1188 static inline int tcp_use_frto(const struct sock *sk) 1189 { 1190 const struct tcp_sock *tp = tcp_sk(sk); 1191 1192 /* F-RTO must be activated in sysctl and there must be some 1193 * unsent new data, and the advertised window should allow 1194 * sending it. 1195 */ 1196 return (sysctl_tcp_frto && sk->sk_send_head && 1197 !after(TCP_SKB_CB(sk->sk_send_head)->end_seq, 1198 tp->snd_una + tp->snd_wnd)); 1199 } 1200 1201 static inline void tcp_mib_init(void) 1202 { 1203 /* See RFC 2012 */ 1204 TCP_ADD_STATS_USER(TCP_MIB_RTOALGORITHM, 1); 1205 TCP_ADD_STATS_USER(TCP_MIB_RTOMIN, TCP_RTO_MIN*1000/HZ); 1206 TCP_ADD_STATS_USER(TCP_MIB_RTOMAX, TCP_RTO_MAX*1000/HZ); 1207 TCP_ADD_STATS_USER(TCP_MIB_MAXCONN, -1); 1208 } 1209 1210 /*from STCP */ 1211 static inline void clear_all_retrans_hints(struct tcp_sock *tp){ 1212 tp->lost_skb_hint = NULL; 1213 tp->scoreboard_skb_hint = NULL; 1214 tp->retransmit_skb_hint = NULL; 1215 tp->forward_skb_hint = NULL; 1216 tp->fastpath_skb_hint = NULL; 1217 } 1218 1219 /* /proc */ 1220 enum tcp_seq_states { 1221 TCP_SEQ_STATE_LISTENING, 1222 TCP_SEQ_STATE_OPENREQ, 1223 TCP_SEQ_STATE_ESTABLISHED, 1224 TCP_SEQ_STATE_TIME_WAIT, 1225 }; 1226 1227 struct tcp_seq_afinfo { 1228 struct module *owner; 1229 char *name; 1230 sa_family_t family; 1231 int (*seq_show) (struct seq_file *m, void *v); 1232 struct file_operations *seq_fops; 1233 }; 1234 1235 struct tcp_iter_state { 1236 sa_family_t family; 1237 enum tcp_seq_states state; 1238 struct sock *syn_wait_sk; 1239 int bucket, sbucket, num, uid; 1240 struct seq_operations seq_ops; 1241 }; 1242 1243 extern int tcp_proc_register(struct tcp_seq_afinfo *afinfo); 1244 extern void tcp_proc_unregister(struct tcp_seq_afinfo *afinfo); 1245 1246 extern struct request_sock_ops tcp_request_sock_ops; 1247 1248 extern int tcp_v4_destroy_sock(struct sock *sk); 1249 1250 #ifdef CONFIG_PROC_FS 1251 extern int tcp4_proc_init(void); 1252 extern void tcp4_proc_exit(void); 1253 #endif 1254 1255 extern void tcp_v4_init(struct net_proto_family *ops); 1256 extern void tcp_init(void); 1257 1258 #endif /* _TCP_H */ 1259