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