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/list.h> 25 #include <linux/tcp.h> 26 #include <linux/slab.h> 27 #include <linux/cache.h> 28 #include <linux/percpu.h> 29 #include <linux/skbuff.h> 30 #include <linux/dmaengine.h> 31 #include <linux/crypto.h> 32 #include <linux/cryptohash.h> 33 #include <linux/kref.h> 34 35 #include <net/inet_connection_sock.h> 36 #include <net/inet_timewait_sock.h> 37 #include <net/inet_hashtables.h> 38 #include <net/checksum.h> 39 #include <net/request_sock.h> 40 #include <net/sock.h> 41 #include <net/snmp.h> 42 #include <net/ip.h> 43 #include <net/tcp_states.h> 44 #include <net/inet_ecn.h> 45 #include <net/dst.h> 46 47 #include <linux/seq_file.h> 48 49 extern struct inet_hashinfo tcp_hashinfo; 50 51 extern struct percpu_counter tcp_orphan_count; 52 extern void tcp_time_wait(struct sock *sk, int state, int timeo); 53 54 #define MAX_TCP_HEADER (128 + MAX_HEADER) 55 #define MAX_TCP_OPTION_SPACE 40 56 57 /* 58 * Never offer a window over 32767 without using window scaling. Some 59 * poor stacks do signed 16bit maths! 60 */ 61 #define MAX_TCP_WINDOW 32767U 62 63 /* Offer an initial receive window of 10 mss. */ 64 #define TCP_DEFAULT_INIT_RCVWND 10 65 66 /* Minimal accepted MSS. It is (60+60+8) - (20+20). */ 67 #define TCP_MIN_MSS 88U 68 69 /* The least MTU to use for probing */ 70 #define TCP_BASE_MSS 512 71 72 /* After receiving this amount of duplicate ACKs fast retransmit starts. */ 73 #define TCP_FASTRETRANS_THRESH 3 74 75 /* Maximal reordering. */ 76 #define TCP_MAX_REORDERING 127 77 78 /* Maximal number of ACKs sent quickly to accelerate slow-start. */ 79 #define TCP_MAX_QUICKACKS 16U 80 81 /* urg_data states */ 82 #define TCP_URG_VALID 0x0100 83 #define TCP_URG_NOTYET 0x0200 84 #define TCP_URG_READ 0x0400 85 86 #define TCP_RETR1 3 /* 87 * This is how many retries it does before it 88 * tries to figure out if the gateway is 89 * down. Minimal RFC value is 3; it corresponds 90 * to ~3sec-8min depending on RTO. 91 */ 92 93 #define TCP_RETR2 15 /* 94 * This should take at least 95 * 90 minutes to time out. 96 * RFC1122 says that the limit is 100 sec. 97 * 15 is ~13-30min depending on RTO. 98 */ 99 100 #define TCP_SYN_RETRIES 5 /* number of times to retry active opening a 101 * connection: ~180sec is RFC minimum */ 102 103 #define TCP_SYNACK_RETRIES 5 /* number of times to retry passive opening a 104 * connection: ~180sec is RFC minimum */ 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)(1*HZ)) /* RFC2988bis initial RTO value */ 126 #define TCP_TIMEOUT_FALLBACK ((unsigned)(3*HZ)) /* RFC 1122 initial RTO value, now 127 * used as a fallback RTO for the 128 * initial data transmission if no 129 * valid RTT sample has been acquired, 130 * most likely due to retrans in 3WHS. 131 */ 132 133 #define TCP_RESOURCE_PROBE_INTERVAL ((unsigned)(HZ/2U)) /* Maximal interval between probes 134 * for local resources. 135 */ 136 137 #define TCP_KEEPALIVE_TIME (120*60*HZ) /* two hours */ 138 #define TCP_KEEPALIVE_PROBES 9 /* Max of 9 keepalive probes */ 139 #define TCP_KEEPALIVE_INTVL (75*HZ) 140 141 #define MAX_TCP_KEEPIDLE 32767 142 #define MAX_TCP_KEEPINTVL 32767 143 #define MAX_TCP_KEEPCNT 127 144 #define MAX_TCP_SYNCNT 127 145 146 #define TCP_SYNQ_INTERVAL (HZ/5) /* Period of SYNACK timer */ 147 148 #define TCP_PAWS_24DAYS (60 * 60 * 24 * 24) 149 #define TCP_PAWS_MSL 60 /* Per-host timestamps are invalidated 150 * after this time. It should be equal 151 * (or greater than) TCP_TIMEWAIT_LEN 152 * to provide reliability equal to one 153 * provided by timewait state. 154 */ 155 #define TCP_PAWS_WINDOW 1 /* Replay window for per-host 156 * timestamps. It must be less than 157 * minimal timewait lifetime. 158 */ 159 /* 160 * TCP option 161 */ 162 163 #define TCPOPT_NOP 1 /* Padding */ 164 #define TCPOPT_EOL 0 /* End of options */ 165 #define TCPOPT_MSS 2 /* Segment size negotiating */ 166 #define TCPOPT_WINDOW 3 /* Window scaling */ 167 #define TCPOPT_SACK_PERM 4 /* SACK Permitted */ 168 #define TCPOPT_SACK 5 /* SACK Block */ 169 #define TCPOPT_TIMESTAMP 8 /* Better RTT estimations/PAWS */ 170 #define TCPOPT_MD5SIG 19 /* MD5 Signature (RFC2385) */ 171 #define TCPOPT_COOKIE 253 /* Cookie extension (experimental) */ 172 173 /* 174 * TCP option lengths 175 */ 176 177 #define TCPOLEN_MSS 4 178 #define TCPOLEN_WINDOW 3 179 #define TCPOLEN_SACK_PERM 2 180 #define TCPOLEN_TIMESTAMP 10 181 #define TCPOLEN_MD5SIG 18 182 #define TCPOLEN_COOKIE_BASE 2 /* Cookie-less header extension */ 183 #define TCPOLEN_COOKIE_PAIR 3 /* Cookie pair header extension */ 184 #define TCPOLEN_COOKIE_MIN (TCPOLEN_COOKIE_BASE+TCP_COOKIE_MIN) 185 #define TCPOLEN_COOKIE_MAX (TCPOLEN_COOKIE_BASE+TCP_COOKIE_MAX) 186 187 /* But this is what stacks really send out. */ 188 #define TCPOLEN_TSTAMP_ALIGNED 12 189 #define TCPOLEN_WSCALE_ALIGNED 4 190 #define TCPOLEN_SACKPERM_ALIGNED 4 191 #define TCPOLEN_SACK_BASE 2 192 #define TCPOLEN_SACK_BASE_ALIGNED 4 193 #define TCPOLEN_SACK_PERBLOCK 8 194 #define TCPOLEN_MD5SIG_ALIGNED 20 195 #define TCPOLEN_MSS_ALIGNED 4 196 197 /* Flags in tp->nonagle */ 198 #define TCP_NAGLE_OFF 1 /* Nagle's algo is disabled */ 199 #define TCP_NAGLE_CORK 2 /* Socket is corked */ 200 #define TCP_NAGLE_PUSH 4 /* Cork is overridden for already queued data */ 201 202 /* TCP thin-stream limits */ 203 #define TCP_THIN_LINEAR_RETRIES 6 /* After 6 linear retries, do exp. backoff */ 204 205 /* TCP initial congestion window as per draft-hkchu-tcpm-initcwnd-01 */ 206 #define TCP_INIT_CWND 10 207 208 extern struct inet_timewait_death_row tcp_death_row; 209 210 /* sysctl variables for tcp */ 211 extern int sysctl_tcp_timestamps; 212 extern int sysctl_tcp_window_scaling; 213 extern int sysctl_tcp_sack; 214 extern int sysctl_tcp_fin_timeout; 215 extern int sysctl_tcp_keepalive_time; 216 extern int sysctl_tcp_keepalive_probes; 217 extern int sysctl_tcp_keepalive_intvl; 218 extern int sysctl_tcp_syn_retries; 219 extern int sysctl_tcp_synack_retries; 220 extern int sysctl_tcp_retries1; 221 extern int sysctl_tcp_retries2; 222 extern int sysctl_tcp_orphan_retries; 223 extern int sysctl_tcp_syncookies; 224 extern int sysctl_tcp_retrans_collapse; 225 extern int sysctl_tcp_stdurg; 226 extern int sysctl_tcp_rfc1337; 227 extern int sysctl_tcp_abort_on_overflow; 228 extern int sysctl_tcp_max_orphans; 229 extern int sysctl_tcp_fack; 230 extern int sysctl_tcp_reordering; 231 extern int sysctl_tcp_ecn; 232 extern int sysctl_tcp_dsack; 233 extern long sysctl_tcp_mem[3]; 234 extern int sysctl_tcp_wmem[3]; 235 extern int sysctl_tcp_rmem[3]; 236 extern int sysctl_tcp_app_win; 237 extern int sysctl_tcp_adv_win_scale; 238 extern int sysctl_tcp_tw_reuse; 239 extern int sysctl_tcp_frto; 240 extern int sysctl_tcp_frto_response; 241 extern int sysctl_tcp_low_latency; 242 extern int sysctl_tcp_dma_copybreak; 243 extern int sysctl_tcp_nometrics_save; 244 extern int sysctl_tcp_moderate_rcvbuf; 245 extern int sysctl_tcp_tso_win_divisor; 246 extern int sysctl_tcp_abc; 247 extern int sysctl_tcp_mtu_probing; 248 extern int sysctl_tcp_base_mss; 249 extern int sysctl_tcp_workaround_signed_windows; 250 extern int sysctl_tcp_slow_start_after_idle; 251 extern int sysctl_tcp_max_ssthresh; 252 extern int sysctl_tcp_cookie_size; 253 extern int sysctl_tcp_thin_linear_timeouts; 254 extern int sysctl_tcp_thin_dupack; 255 256 extern atomic_long_t tcp_memory_allocated; 257 extern struct percpu_counter tcp_sockets_allocated; 258 extern int tcp_memory_pressure; 259 260 /* 261 * The next routines deal with comparing 32 bit unsigned ints 262 * and worry about wraparound (automatic with unsigned arithmetic). 263 */ 264 265 static inline int before(__u32 seq1, __u32 seq2) 266 { 267 return (__s32)(seq1-seq2) < 0; 268 } 269 #define after(seq2, seq1) before(seq1, seq2) 270 271 /* is s2<=s1<=s3 ? */ 272 static inline int between(__u32 seq1, __u32 seq2, __u32 seq3) 273 { 274 return seq3 - seq2 >= seq1 - seq2; 275 } 276 277 static inline bool tcp_too_many_orphans(struct sock *sk, int shift) 278 { 279 struct percpu_counter *ocp = sk->sk_prot->orphan_count; 280 int orphans = percpu_counter_read_positive(ocp); 281 282 if (orphans << shift > sysctl_tcp_max_orphans) { 283 orphans = percpu_counter_sum_positive(ocp); 284 if (orphans << shift > sysctl_tcp_max_orphans) 285 return true; 286 } 287 288 if (sk->sk_wmem_queued > SOCK_MIN_SNDBUF && 289 atomic_long_read(&tcp_memory_allocated) > sysctl_tcp_mem[2]) 290 return true; 291 return false; 292 } 293 294 /* syncookies: remember time of last synqueue overflow */ 295 static inline void tcp_synq_overflow(struct sock *sk) 296 { 297 tcp_sk(sk)->rx_opt.ts_recent_stamp = jiffies; 298 } 299 300 /* syncookies: no recent synqueue overflow on this listening socket? */ 301 static inline int tcp_synq_no_recent_overflow(const struct sock *sk) 302 { 303 unsigned long last_overflow = tcp_sk(sk)->rx_opt.ts_recent_stamp; 304 return time_after(jiffies, last_overflow + TCP_TIMEOUT_FALLBACK); 305 } 306 307 extern struct proto tcp_prot; 308 309 #define TCP_INC_STATS(net, field) SNMP_INC_STATS((net)->mib.tcp_statistics, field) 310 #define TCP_INC_STATS_BH(net, field) SNMP_INC_STATS_BH((net)->mib.tcp_statistics, field) 311 #define TCP_DEC_STATS(net, field) SNMP_DEC_STATS((net)->mib.tcp_statistics, field) 312 #define TCP_ADD_STATS_USER(net, field, val) SNMP_ADD_STATS_USER((net)->mib.tcp_statistics, field, val) 313 #define TCP_ADD_STATS(net, field, val) SNMP_ADD_STATS((net)->mib.tcp_statistics, field, val) 314 315 extern void tcp_v4_err(struct sk_buff *skb, u32); 316 317 extern void tcp_shutdown (struct sock *sk, int how); 318 319 extern int tcp_v4_rcv(struct sk_buff *skb); 320 321 extern struct inet_peer *tcp_v4_get_peer(struct sock *sk, bool *release_it); 322 extern void *tcp_v4_tw_get_peer(struct sock *sk); 323 extern int tcp_v4_tw_remember_stamp(struct inet_timewait_sock *tw); 324 extern int tcp_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg, 325 size_t size); 326 extern int tcp_sendpage(struct sock *sk, struct page *page, int offset, 327 size_t size, int flags); 328 extern int tcp_ioctl(struct sock *sk, int cmd, unsigned long arg); 329 extern int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb, 330 struct tcphdr *th, unsigned len); 331 extern int tcp_rcv_established(struct sock *sk, struct sk_buff *skb, 332 struct tcphdr *th, unsigned len); 333 extern void tcp_rcv_space_adjust(struct sock *sk); 334 extern void tcp_cleanup_rbuf(struct sock *sk, int copied); 335 extern int tcp_twsk_unique(struct sock *sk, struct sock *sktw, void *twp); 336 extern void tcp_twsk_destructor(struct sock *sk); 337 extern ssize_t tcp_splice_read(struct socket *sk, loff_t *ppos, 338 struct pipe_inode_info *pipe, size_t len, 339 unsigned int flags); 340 341 static inline void tcp_dec_quickack_mode(struct sock *sk, 342 const unsigned int pkts) 343 { 344 struct inet_connection_sock *icsk = inet_csk(sk); 345 346 if (icsk->icsk_ack.quick) { 347 if (pkts >= icsk->icsk_ack.quick) { 348 icsk->icsk_ack.quick = 0; 349 /* Leaving quickack mode we deflate ATO. */ 350 icsk->icsk_ack.ato = TCP_ATO_MIN; 351 } else 352 icsk->icsk_ack.quick -= pkts; 353 } 354 } 355 356 #define TCP_ECN_OK 1 357 #define TCP_ECN_QUEUE_CWR 2 358 #define TCP_ECN_DEMAND_CWR 4 359 360 static __inline__ void 361 TCP_ECN_create_request(struct request_sock *req, struct tcphdr *th) 362 { 363 if (sysctl_tcp_ecn && th->ece && th->cwr) 364 inet_rsk(req)->ecn_ok = 1; 365 } 366 367 enum tcp_tw_status { 368 TCP_TW_SUCCESS = 0, 369 TCP_TW_RST = 1, 370 TCP_TW_ACK = 2, 371 TCP_TW_SYN = 3 372 }; 373 374 375 extern enum tcp_tw_status tcp_timewait_state_process(struct inet_timewait_sock *tw, 376 struct sk_buff *skb, 377 const struct tcphdr *th); 378 extern struct sock * tcp_check_req(struct sock *sk,struct sk_buff *skb, 379 struct request_sock *req, 380 struct request_sock **prev); 381 extern int tcp_child_process(struct sock *parent, struct sock *child, 382 struct sk_buff *skb); 383 extern int tcp_use_frto(struct sock *sk); 384 extern void tcp_enter_frto(struct sock *sk); 385 extern void tcp_enter_loss(struct sock *sk, int how); 386 extern void tcp_clear_retrans(struct tcp_sock *tp); 387 extern void tcp_update_metrics(struct sock *sk); 388 extern void tcp_close(struct sock *sk, long timeout); 389 extern unsigned int tcp_poll(struct file * file, struct socket *sock, 390 struct poll_table_struct *wait); 391 extern int tcp_getsockopt(struct sock *sk, int level, int optname, 392 char __user *optval, int __user *optlen); 393 extern int tcp_setsockopt(struct sock *sk, int level, int optname, 394 char __user *optval, unsigned int optlen); 395 extern int compat_tcp_getsockopt(struct sock *sk, int level, int optname, 396 char __user *optval, int __user *optlen); 397 extern int compat_tcp_setsockopt(struct sock *sk, int level, int optname, 398 char __user *optval, unsigned int optlen); 399 extern void tcp_set_keepalive(struct sock *sk, int val); 400 extern void tcp_syn_ack_timeout(struct sock *sk, struct request_sock *req); 401 extern int tcp_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg, 402 size_t len, int nonblock, int flags, int *addr_len); 403 extern void tcp_parse_options(struct sk_buff *skb, 404 struct tcp_options_received *opt_rx, u8 **hvpp, 405 int estab); 406 extern u8 *tcp_parse_md5sig_option(struct tcphdr *th); 407 408 /* 409 * TCP v4 functions exported for the inet6 API 410 */ 411 412 extern void tcp_v4_send_check(struct sock *sk, struct sk_buff *skb); 413 extern int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb); 414 extern struct sock * tcp_create_openreq_child(struct sock *sk, 415 struct request_sock *req, 416 struct sk_buff *skb); 417 extern struct sock * tcp_v4_syn_recv_sock(struct sock *sk, struct sk_buff *skb, 418 struct request_sock *req, 419 struct dst_entry *dst); 420 extern int tcp_v4_do_rcv(struct sock *sk, struct sk_buff *skb); 421 extern int tcp_v4_connect(struct sock *sk, struct sockaddr *uaddr, 422 int addr_len); 423 extern int tcp_connect(struct sock *sk); 424 extern struct sk_buff * tcp_make_synack(struct sock *sk, struct dst_entry *dst, 425 struct request_sock *req, 426 struct request_values *rvp); 427 extern int tcp_disconnect(struct sock *sk, int flags); 428 429 430 /* From syncookies.c */ 431 extern __u32 syncookie_secret[2][16-4+SHA_DIGEST_WORDS]; 432 extern struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb, 433 struct ip_options *opt); 434 extern __u32 cookie_v4_init_sequence(struct sock *sk, struct sk_buff *skb, 435 __u16 *mss); 436 437 extern __u32 cookie_init_timestamp(struct request_sock *req); 438 extern bool cookie_check_timestamp(struct tcp_options_received *opt, bool *); 439 440 /* From net/ipv6/syncookies.c */ 441 extern struct sock *cookie_v6_check(struct sock *sk, struct sk_buff *skb); 442 extern __u32 cookie_v6_init_sequence(struct sock *sk, struct sk_buff *skb, 443 __u16 *mss); 444 445 /* tcp_output.c */ 446 447 extern void __tcp_push_pending_frames(struct sock *sk, unsigned int cur_mss, 448 int nonagle); 449 extern int tcp_may_send_now(struct sock *sk); 450 extern int tcp_retransmit_skb(struct sock *, struct sk_buff *); 451 extern void tcp_retransmit_timer(struct sock *sk); 452 extern void tcp_xmit_retransmit_queue(struct sock *); 453 extern void tcp_simple_retransmit(struct sock *); 454 extern int tcp_trim_head(struct sock *, struct sk_buff *, u32); 455 extern int tcp_fragment(struct sock *, struct sk_buff *, u32, unsigned int); 456 457 extern void tcp_send_probe0(struct sock *); 458 extern void tcp_send_partial(struct sock *); 459 extern int tcp_write_wakeup(struct sock *); 460 extern void tcp_send_fin(struct sock *sk); 461 extern void tcp_send_active_reset(struct sock *sk, gfp_t priority); 462 extern int tcp_send_synack(struct sock *); 463 extern void tcp_push_one(struct sock *, unsigned int mss_now); 464 extern void tcp_send_ack(struct sock *sk); 465 extern void tcp_send_delayed_ack(struct sock *sk); 466 467 /* tcp_input.c */ 468 extern void tcp_cwnd_application_limited(struct sock *sk); 469 470 /* tcp_timer.c */ 471 extern void tcp_init_xmit_timers(struct sock *); 472 static inline void tcp_clear_xmit_timers(struct sock *sk) 473 { 474 inet_csk_clear_xmit_timers(sk); 475 } 476 477 extern unsigned int tcp_sync_mss(struct sock *sk, u32 pmtu); 478 extern unsigned int tcp_current_mss(struct sock *sk); 479 480 /* Bound MSS / TSO packet size with the half of the window */ 481 static inline int tcp_bound_to_half_wnd(struct tcp_sock *tp, int pktsize) 482 { 483 int cutoff; 484 485 /* When peer uses tiny windows, there is no use in packetizing 486 * to sub-MSS pieces for the sake of SWS or making sure there 487 * are enough packets in the pipe for fast recovery. 488 * 489 * On the other hand, for extremely large MSS devices, handling 490 * smaller than MSS windows in this way does make sense. 491 */ 492 if (tp->max_window >= 512) 493 cutoff = (tp->max_window >> 1); 494 else 495 cutoff = tp->max_window; 496 497 if (cutoff && pktsize > cutoff) 498 return max_t(int, cutoff, 68U - tp->tcp_header_len); 499 else 500 return pktsize; 501 } 502 503 /* tcp.c */ 504 extern void tcp_get_info(struct sock *, struct tcp_info *); 505 506 /* Read 'sendfile()'-style from a TCP socket */ 507 typedef int (*sk_read_actor_t)(read_descriptor_t *, struct sk_buff *, 508 unsigned int, size_t); 509 extern int tcp_read_sock(struct sock *sk, read_descriptor_t *desc, 510 sk_read_actor_t recv_actor); 511 512 extern void tcp_initialize_rcv_mss(struct sock *sk); 513 514 extern int tcp_mtu_to_mss(struct sock *sk, int pmtu); 515 extern int tcp_mss_to_mtu(struct sock *sk, int mss); 516 extern void tcp_mtup_init(struct sock *sk); 517 extern void tcp_valid_rtt_meas(struct sock *sk, u32 seq_rtt); 518 519 static inline void tcp_bound_rto(const struct sock *sk) 520 { 521 if (inet_csk(sk)->icsk_rto > TCP_RTO_MAX) 522 inet_csk(sk)->icsk_rto = TCP_RTO_MAX; 523 } 524 525 static inline u32 __tcp_set_rto(const struct tcp_sock *tp) 526 { 527 return (tp->srtt >> 3) + tp->rttvar; 528 } 529 530 static inline void __tcp_fast_path_on(struct tcp_sock *tp, u32 snd_wnd) 531 { 532 tp->pred_flags = htonl((tp->tcp_header_len << 26) | 533 ntohl(TCP_FLAG_ACK) | 534 snd_wnd); 535 } 536 537 static inline void tcp_fast_path_on(struct tcp_sock *tp) 538 { 539 __tcp_fast_path_on(tp, tp->snd_wnd >> tp->rx_opt.snd_wscale); 540 } 541 542 static inline void tcp_fast_path_check(struct sock *sk) 543 { 544 struct tcp_sock *tp = tcp_sk(sk); 545 546 if (skb_queue_empty(&tp->out_of_order_queue) && 547 tp->rcv_wnd && 548 atomic_read(&sk->sk_rmem_alloc) < sk->sk_rcvbuf && 549 !tp->urg_data) 550 tcp_fast_path_on(tp); 551 } 552 553 /* Compute the actual rto_min value */ 554 static inline u32 tcp_rto_min(struct sock *sk) 555 { 556 struct dst_entry *dst = __sk_dst_get(sk); 557 u32 rto_min = TCP_RTO_MIN; 558 559 if (dst && dst_metric_locked(dst, RTAX_RTO_MIN)) 560 rto_min = dst_metric_rtt(dst, RTAX_RTO_MIN); 561 return rto_min; 562 } 563 564 /* Compute the actual receive window we are currently advertising. 565 * Rcv_nxt can be after the window if our peer push more data 566 * than the offered window. 567 */ 568 static inline u32 tcp_receive_window(const struct tcp_sock *tp) 569 { 570 s32 win = tp->rcv_wup + tp->rcv_wnd - tp->rcv_nxt; 571 572 if (win < 0) 573 win = 0; 574 return (u32) win; 575 } 576 577 /* Choose a new window, without checks for shrinking, and without 578 * scaling applied to the result. The caller does these things 579 * if necessary. This is a "raw" window selection. 580 */ 581 extern u32 __tcp_select_window(struct sock *sk); 582 583 /* TCP timestamps are only 32-bits, this causes a slight 584 * complication on 64-bit systems since we store a snapshot 585 * of jiffies in the buffer control blocks below. We decided 586 * to use only the low 32-bits of jiffies and hide the ugly 587 * casts with the following macro. 588 */ 589 #define tcp_time_stamp ((__u32)(jiffies)) 590 591 #define tcp_flag_byte(th) (((u_int8_t *)th)[13]) 592 593 #define TCPHDR_FIN 0x01 594 #define TCPHDR_SYN 0x02 595 #define TCPHDR_RST 0x04 596 #define TCPHDR_PSH 0x08 597 #define TCPHDR_ACK 0x10 598 #define TCPHDR_URG 0x20 599 #define TCPHDR_ECE 0x40 600 #define TCPHDR_CWR 0x80 601 602 /* This is what the send packet queuing engine uses to pass 603 * TCP per-packet control information to the transmission code. 604 * We also store the host-order sequence numbers in here too. 605 * This is 44 bytes if IPV6 is enabled. 606 * If this grows please adjust skbuff.h:skbuff->cb[xxx] size appropriately. 607 */ 608 struct tcp_skb_cb { 609 union { 610 struct inet_skb_parm h4; 611 #if defined(CONFIG_IPV6) || defined (CONFIG_IPV6_MODULE) 612 struct inet6_skb_parm h6; 613 #endif 614 } header; /* For incoming frames */ 615 __u32 seq; /* Starting sequence number */ 616 __u32 end_seq; /* SEQ + FIN + SYN + datalen */ 617 __u32 when; /* used to compute rtt's */ 618 __u8 flags; /* TCP header flags. */ 619 __u8 sacked; /* State flags for SACK/FACK. */ 620 #define TCPCB_SACKED_ACKED 0x01 /* SKB ACK'd by a SACK block */ 621 #define TCPCB_SACKED_RETRANS 0x02 /* SKB retransmitted */ 622 #define TCPCB_LOST 0x04 /* SKB is lost */ 623 #define TCPCB_TAGBITS 0x07 /* All tag bits */ 624 625 #define TCPCB_EVER_RETRANS 0x80 /* Ever retransmitted frame */ 626 #define TCPCB_RETRANS (TCPCB_SACKED_RETRANS|TCPCB_EVER_RETRANS) 627 628 __u32 ack_seq; /* Sequence number ACK'd */ 629 }; 630 631 #define TCP_SKB_CB(__skb) ((struct tcp_skb_cb *)&((__skb)->cb[0])) 632 633 /* Due to TSO, an SKB can be composed of multiple actual 634 * packets. To keep these tracked properly, we use this. 635 */ 636 static inline int tcp_skb_pcount(const struct sk_buff *skb) 637 { 638 return skb_shinfo(skb)->gso_segs; 639 } 640 641 /* This is valid iff tcp_skb_pcount() > 1. */ 642 static inline int tcp_skb_mss(const struct sk_buff *skb) 643 { 644 return skb_shinfo(skb)->gso_size; 645 } 646 647 /* Events passed to congestion control interface */ 648 enum tcp_ca_event { 649 CA_EVENT_TX_START, /* first transmit when no packets in flight */ 650 CA_EVENT_CWND_RESTART, /* congestion window restart */ 651 CA_EVENT_COMPLETE_CWR, /* end of congestion recovery */ 652 CA_EVENT_FRTO, /* fast recovery timeout */ 653 CA_EVENT_LOSS, /* loss timeout */ 654 CA_EVENT_FAST_ACK, /* in sequence ack */ 655 CA_EVENT_SLOW_ACK, /* other ack */ 656 }; 657 658 /* 659 * Interface for adding new TCP congestion control handlers 660 */ 661 #define TCP_CA_NAME_MAX 16 662 #define TCP_CA_MAX 128 663 #define TCP_CA_BUF_MAX (TCP_CA_NAME_MAX*TCP_CA_MAX) 664 665 #define TCP_CONG_NON_RESTRICTED 0x1 666 #define TCP_CONG_RTT_STAMP 0x2 667 668 struct tcp_congestion_ops { 669 struct list_head list; 670 unsigned long flags; 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)(const struct sock *sk); 681 /* do new cwnd calculation (required) */ 682 void (*cong_avoid)(struct sock *sk, u32 ack, u32 in_flight); 683 /* call before changing ca_state (optional) */ 684 void (*set_state)(struct sock *sk, u8 new_state); 685 /* call when cwnd event occurs (optional) */ 686 void (*cwnd_event)(struct sock *sk, enum tcp_ca_event ev); 687 /* new value of cwnd after loss (optional) */ 688 u32 (*undo_cwnd)(struct sock *sk); 689 /* hook for packet ack accounting (optional) */ 690 void (*pkts_acked)(struct sock *sk, u32 num_acked, s32 rtt_us); 691 /* get info for inet_diag (optional) */ 692 void (*get_info)(struct sock *sk, u32 ext, struct sk_buff *skb); 693 694 char name[TCP_CA_NAME_MAX]; 695 struct module *owner; 696 }; 697 698 extern int tcp_register_congestion_control(struct tcp_congestion_ops *type); 699 extern void tcp_unregister_congestion_control(struct tcp_congestion_ops *type); 700 701 extern void tcp_init_congestion_control(struct sock *sk); 702 extern void tcp_cleanup_congestion_control(struct sock *sk); 703 extern int tcp_set_default_congestion_control(const char *name); 704 extern void tcp_get_default_congestion_control(char *name); 705 extern void tcp_get_available_congestion_control(char *buf, size_t len); 706 extern void tcp_get_allowed_congestion_control(char *buf, size_t len); 707 extern int tcp_set_allowed_congestion_control(char *allowed); 708 extern int tcp_set_congestion_control(struct sock *sk, const char *name); 709 extern void tcp_slow_start(struct tcp_sock *tp); 710 extern void tcp_cong_avoid_ai(struct tcp_sock *tp, u32 w); 711 712 extern struct tcp_congestion_ops tcp_init_congestion_ops; 713 extern u32 tcp_reno_ssthresh(struct sock *sk); 714 extern void tcp_reno_cong_avoid(struct sock *sk, u32 ack, u32 in_flight); 715 extern u32 tcp_reno_min_cwnd(const 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 /* These functions determine how the current flow behaves in respect of SACK 736 * handling. SACK is negotiated with the peer, and therefore it can vary 737 * between different flows. 738 * 739 * tcp_is_sack - SACK enabled 740 * tcp_is_reno - No SACK 741 * tcp_is_fack - FACK enabled, implies SACK enabled 742 */ 743 static inline int tcp_is_sack(const struct tcp_sock *tp) 744 { 745 return tp->rx_opt.sack_ok; 746 } 747 748 static inline int tcp_is_reno(const struct tcp_sock *tp) 749 { 750 return !tcp_is_sack(tp); 751 } 752 753 static inline int tcp_is_fack(const struct tcp_sock *tp) 754 { 755 return tp->rx_opt.sack_ok & 2; 756 } 757 758 static inline void tcp_enable_fack(struct tcp_sock *tp) 759 { 760 tp->rx_opt.sack_ok |= 2; 761 } 762 763 static inline unsigned int tcp_left_out(const struct tcp_sock *tp) 764 { 765 return tp->sacked_out + tp->lost_out; 766 } 767 768 /* This determines how many packets are "in the network" to the best 769 * of our knowledge. In many cases it is conservative, but where 770 * detailed information is available from the receiver (via SACK 771 * blocks etc.) we can make more aggressive calculations. 772 * 773 * Use this for decisions involving congestion control, use just 774 * tp->packets_out to determine if the send queue is empty or not. 775 * 776 * Read this equation as: 777 * 778 * "Packets sent once on transmission queue" MINUS 779 * "Packets left network, but not honestly ACKed yet" PLUS 780 * "Packets fast retransmitted" 781 */ 782 static inline unsigned int tcp_packets_in_flight(const struct tcp_sock *tp) 783 { 784 return tp->packets_out - tcp_left_out(tp) + tp->retrans_out; 785 } 786 787 #define TCP_INFINITE_SSTHRESH 0x7fffffff 788 789 static inline bool tcp_in_initial_slowstart(const struct tcp_sock *tp) 790 { 791 return tp->snd_ssthresh >= TCP_INFINITE_SSTHRESH; 792 } 793 794 /* If cwnd > ssthresh, we may raise ssthresh to be half-way to cwnd. 795 * The exception is rate halving phase, when cwnd is decreasing towards 796 * ssthresh. 797 */ 798 static inline __u32 tcp_current_ssthresh(const struct sock *sk) 799 { 800 const struct tcp_sock *tp = tcp_sk(sk); 801 if ((1 << inet_csk(sk)->icsk_ca_state) & (TCPF_CA_CWR | TCPF_CA_Recovery)) 802 return tp->snd_ssthresh; 803 else 804 return max(tp->snd_ssthresh, 805 ((tp->snd_cwnd >> 1) + 806 (tp->snd_cwnd >> 2))); 807 } 808 809 /* Use define here intentionally to get WARN_ON location shown at the caller */ 810 #define tcp_verify_left_out(tp) WARN_ON(tcp_left_out(tp) > tp->packets_out) 811 812 extern void tcp_enter_cwr(struct sock *sk, const int set_ssthresh); 813 extern __u32 tcp_init_cwnd(struct tcp_sock *tp, struct dst_entry *dst); 814 815 /* Slow start with delack produces 3 packets of burst, so that 816 * it is safe "de facto". This will be the default - same as 817 * the default reordering threshold - but if reordering increases, 818 * we must be able to allow cwnd to burst at least this much in order 819 * to not pull it back when holes are filled. 820 */ 821 static __inline__ __u32 tcp_max_burst(const struct tcp_sock *tp) 822 { 823 return tp->reordering; 824 } 825 826 /* Returns end sequence number of the receiver's advertised window */ 827 static inline u32 tcp_wnd_end(const struct tcp_sock *tp) 828 { 829 return tp->snd_una + tp->snd_wnd; 830 } 831 extern int tcp_is_cwnd_limited(const struct sock *sk, u32 in_flight); 832 833 static inline void tcp_minshall_update(struct tcp_sock *tp, unsigned int mss, 834 const struct sk_buff *skb) 835 { 836 if (skb->len < mss) 837 tp->snd_sml = TCP_SKB_CB(skb)->end_seq; 838 } 839 840 static inline void tcp_check_probe_timer(struct sock *sk) 841 { 842 struct tcp_sock *tp = tcp_sk(sk); 843 const struct inet_connection_sock *icsk = inet_csk(sk); 844 845 if (!tp->packets_out && !icsk->icsk_pending) 846 inet_csk_reset_xmit_timer(sk, ICSK_TIME_PROBE0, 847 icsk->icsk_rto, TCP_RTO_MAX); 848 } 849 850 static inline void tcp_init_wl(struct tcp_sock *tp, u32 seq) 851 { 852 tp->snd_wl1 = seq; 853 } 854 855 static inline void tcp_update_wl(struct tcp_sock *tp, u32 seq) 856 { 857 tp->snd_wl1 = seq; 858 } 859 860 /* 861 * Calculate(/check) TCP checksum 862 */ 863 static inline __sum16 tcp_v4_check(int len, __be32 saddr, 864 __be32 daddr, __wsum base) 865 { 866 return csum_tcpudp_magic(saddr,daddr,len,IPPROTO_TCP,base); 867 } 868 869 static inline __sum16 __tcp_checksum_complete(struct sk_buff *skb) 870 { 871 return __skb_checksum_complete(skb); 872 } 873 874 static inline int tcp_checksum_complete(struct sk_buff *skb) 875 { 876 return !skb_csum_unnecessary(skb) && 877 __tcp_checksum_complete(skb); 878 } 879 880 /* Prequeue for VJ style copy to user, combined with checksumming. */ 881 882 static inline void tcp_prequeue_init(struct tcp_sock *tp) 883 { 884 tp->ucopy.task = NULL; 885 tp->ucopy.len = 0; 886 tp->ucopy.memory = 0; 887 skb_queue_head_init(&tp->ucopy.prequeue); 888 #ifdef CONFIG_NET_DMA 889 tp->ucopy.dma_chan = NULL; 890 tp->ucopy.wakeup = 0; 891 tp->ucopy.pinned_list = NULL; 892 tp->ucopy.dma_cookie = 0; 893 #endif 894 } 895 896 /* Packet is added to VJ-style prequeue for processing in process 897 * context, if a reader task is waiting. Apparently, this exciting 898 * idea (VJ's mail "Re: query about TCP header on tcp-ip" of 07 Sep 93) 899 * failed somewhere. Latency? Burstiness? Well, at least now we will 900 * see, why it failed. 8)8) --ANK 901 * 902 * NOTE: is this not too big to inline? 903 */ 904 static inline int tcp_prequeue(struct sock *sk, struct sk_buff *skb) 905 { 906 struct tcp_sock *tp = tcp_sk(sk); 907 908 if (sysctl_tcp_low_latency || !tp->ucopy.task) 909 return 0; 910 911 __skb_queue_tail(&tp->ucopy.prequeue, skb); 912 tp->ucopy.memory += skb->truesize; 913 if (tp->ucopy.memory > sk->sk_rcvbuf) { 914 struct sk_buff *skb1; 915 916 BUG_ON(sock_owned_by_user(sk)); 917 918 while ((skb1 = __skb_dequeue(&tp->ucopy.prequeue)) != NULL) { 919 sk_backlog_rcv(sk, skb1); 920 NET_INC_STATS_BH(sock_net(sk), 921 LINUX_MIB_TCPPREQUEUEDROPPED); 922 } 923 924 tp->ucopy.memory = 0; 925 } else if (skb_queue_len(&tp->ucopy.prequeue) == 1) { 926 wake_up_interruptible_sync_poll(sk_sleep(sk), 927 POLLIN | POLLRDNORM | POLLRDBAND); 928 if (!inet_csk_ack_scheduled(sk)) 929 inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK, 930 (3 * tcp_rto_min(sk)) / 4, 931 TCP_RTO_MAX); 932 } 933 return 1; 934 } 935 936 937 #undef STATE_TRACE 938 939 #ifdef STATE_TRACE 940 static const char *statename[]={ 941 "Unused","Established","Syn Sent","Syn Recv", 942 "Fin Wait 1","Fin Wait 2","Time Wait", "Close", 943 "Close Wait","Last ACK","Listen","Closing" 944 }; 945 #endif 946 extern void tcp_set_state(struct sock *sk, int state); 947 948 extern void tcp_done(struct sock *sk); 949 950 static inline void tcp_sack_reset(struct tcp_options_received *rx_opt) 951 { 952 rx_opt->dsack = 0; 953 rx_opt->num_sacks = 0; 954 } 955 956 /* Determine a window scaling and initial window to offer. */ 957 extern void tcp_select_initial_window(int __space, __u32 mss, 958 __u32 *rcv_wnd, __u32 *window_clamp, 959 int wscale_ok, __u8 *rcv_wscale, 960 __u32 init_rcv_wnd); 961 962 static inline int tcp_win_from_space(int space) 963 { 964 return sysctl_tcp_adv_win_scale<=0 ? 965 (space>>(-sysctl_tcp_adv_win_scale)) : 966 space - (space>>sysctl_tcp_adv_win_scale); 967 } 968 969 /* Note: caller must be prepared to deal with negative returns */ 970 static inline int tcp_space(const struct sock *sk) 971 { 972 return tcp_win_from_space(sk->sk_rcvbuf - 973 atomic_read(&sk->sk_rmem_alloc)); 974 } 975 976 static inline int tcp_full_space(const struct sock *sk) 977 { 978 return tcp_win_from_space(sk->sk_rcvbuf); 979 } 980 981 static inline void tcp_openreq_init(struct request_sock *req, 982 struct tcp_options_received *rx_opt, 983 struct sk_buff *skb) 984 { 985 struct inet_request_sock *ireq = inet_rsk(req); 986 987 req->rcv_wnd = 0; /* So that tcp_send_synack() knows! */ 988 req->cookie_ts = 0; 989 tcp_rsk(req)->rcv_isn = TCP_SKB_CB(skb)->seq; 990 req->mss = rx_opt->mss_clamp; 991 req->ts_recent = rx_opt->saw_tstamp ? rx_opt->rcv_tsval : 0; 992 ireq->tstamp_ok = rx_opt->tstamp_ok; 993 ireq->sack_ok = rx_opt->sack_ok; 994 ireq->snd_wscale = rx_opt->snd_wscale; 995 ireq->wscale_ok = rx_opt->wscale_ok; 996 ireq->acked = 0; 997 ireq->ecn_ok = 0; 998 ireq->rmt_port = tcp_hdr(skb)->source; 999 ireq->loc_port = tcp_hdr(skb)->dest; 1000 } 1001 1002 extern void tcp_enter_memory_pressure(struct sock *sk); 1003 1004 static inline int keepalive_intvl_when(const struct tcp_sock *tp) 1005 { 1006 return tp->keepalive_intvl ? : sysctl_tcp_keepalive_intvl; 1007 } 1008 1009 static inline int keepalive_time_when(const struct tcp_sock *tp) 1010 { 1011 return tp->keepalive_time ? : sysctl_tcp_keepalive_time; 1012 } 1013 1014 static inline int keepalive_probes(const struct tcp_sock *tp) 1015 { 1016 return tp->keepalive_probes ? : sysctl_tcp_keepalive_probes; 1017 } 1018 1019 static inline u32 keepalive_time_elapsed(const struct tcp_sock *tp) 1020 { 1021 const struct inet_connection_sock *icsk = &tp->inet_conn; 1022 1023 return min_t(u32, tcp_time_stamp - icsk->icsk_ack.lrcvtime, 1024 tcp_time_stamp - tp->rcv_tstamp); 1025 } 1026 1027 static inline int tcp_fin_time(const struct sock *sk) 1028 { 1029 int fin_timeout = tcp_sk(sk)->linger2 ? : sysctl_tcp_fin_timeout; 1030 const int rto = inet_csk(sk)->icsk_rto; 1031 1032 if (fin_timeout < (rto << 2) - (rto >> 1)) 1033 fin_timeout = (rto << 2) - (rto >> 1); 1034 1035 return fin_timeout; 1036 } 1037 1038 static inline int tcp_paws_check(const struct tcp_options_received *rx_opt, 1039 int paws_win) 1040 { 1041 if ((s32)(rx_opt->ts_recent - rx_opt->rcv_tsval) <= paws_win) 1042 return 1; 1043 if (unlikely(get_seconds() >= rx_opt->ts_recent_stamp + TCP_PAWS_24DAYS)) 1044 return 1; 1045 /* 1046 * Some OSes send SYN and SYNACK messages with tsval=0 tsecr=0, 1047 * then following tcp messages have valid values. Ignore 0 value, 1048 * or else 'negative' tsval might forbid us to accept their packets. 1049 */ 1050 if (!rx_opt->ts_recent) 1051 return 1; 1052 return 0; 1053 } 1054 1055 static inline int tcp_paws_reject(const struct tcp_options_received *rx_opt, 1056 int rst) 1057 { 1058 if (tcp_paws_check(rx_opt, 0)) 1059 return 0; 1060 1061 /* RST segments are not recommended to carry timestamp, 1062 and, if they do, it is recommended to ignore PAWS because 1063 "their cleanup function should take precedence over timestamps." 1064 Certainly, it is mistake. It is necessary to understand the reasons 1065 of this constraint to relax it: if peer reboots, clock may go 1066 out-of-sync and half-open connections will not be reset. 1067 Actually, the problem would be not existing if all 1068 the implementations followed draft about maintaining clock 1069 via reboots. Linux-2.2 DOES NOT! 1070 1071 However, we can relax time bounds for RST segments to MSL. 1072 */ 1073 if (rst && get_seconds() >= rx_opt->ts_recent_stamp + TCP_PAWS_MSL) 1074 return 0; 1075 return 1; 1076 } 1077 1078 static inline void tcp_mib_init(struct net *net) 1079 { 1080 /* See RFC 2012 */ 1081 TCP_ADD_STATS_USER(net, TCP_MIB_RTOALGORITHM, 1); 1082 TCP_ADD_STATS_USER(net, TCP_MIB_RTOMIN, TCP_RTO_MIN*1000/HZ); 1083 TCP_ADD_STATS_USER(net, TCP_MIB_RTOMAX, TCP_RTO_MAX*1000/HZ); 1084 TCP_ADD_STATS_USER(net, TCP_MIB_MAXCONN, -1); 1085 } 1086 1087 /* from STCP */ 1088 static inline void tcp_clear_retrans_hints_partial(struct tcp_sock *tp) 1089 { 1090 tp->lost_skb_hint = NULL; 1091 tp->scoreboard_skb_hint = NULL; 1092 } 1093 1094 static inline void tcp_clear_all_retrans_hints(struct tcp_sock *tp) 1095 { 1096 tcp_clear_retrans_hints_partial(tp); 1097 tp->retransmit_skb_hint = NULL; 1098 } 1099 1100 /* MD5 Signature */ 1101 struct crypto_hash; 1102 1103 /* - key database */ 1104 struct tcp_md5sig_key { 1105 u8 *key; 1106 u8 keylen; 1107 }; 1108 1109 struct tcp4_md5sig_key { 1110 struct tcp_md5sig_key base; 1111 __be32 addr; 1112 }; 1113 1114 struct tcp6_md5sig_key { 1115 struct tcp_md5sig_key base; 1116 #if 0 1117 u32 scope_id; /* XXX */ 1118 #endif 1119 struct in6_addr addr; 1120 }; 1121 1122 /* - sock block */ 1123 struct tcp_md5sig_info { 1124 struct tcp4_md5sig_key *keys4; 1125 #if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE) 1126 struct tcp6_md5sig_key *keys6; 1127 u32 entries6; 1128 u32 alloced6; 1129 #endif 1130 u32 entries4; 1131 u32 alloced4; 1132 }; 1133 1134 /* - pseudo header */ 1135 struct tcp4_pseudohdr { 1136 __be32 saddr; 1137 __be32 daddr; 1138 __u8 pad; 1139 __u8 protocol; 1140 __be16 len; 1141 }; 1142 1143 struct tcp6_pseudohdr { 1144 struct in6_addr saddr; 1145 struct in6_addr daddr; 1146 __be32 len; 1147 __be32 protocol; /* including padding */ 1148 }; 1149 1150 union tcp_md5sum_block { 1151 struct tcp4_pseudohdr ip4; 1152 #if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE) 1153 struct tcp6_pseudohdr ip6; 1154 #endif 1155 }; 1156 1157 /* - pool: digest algorithm, hash description and scratch buffer */ 1158 struct tcp_md5sig_pool { 1159 struct hash_desc md5_desc; 1160 union tcp_md5sum_block md5_blk; 1161 }; 1162 1163 /* - functions */ 1164 extern int tcp_v4_md5_hash_skb(char *md5_hash, struct tcp_md5sig_key *key, 1165 struct sock *sk, struct request_sock *req, 1166 struct sk_buff *skb); 1167 extern struct tcp_md5sig_key * tcp_v4_md5_lookup(struct sock *sk, 1168 struct sock *addr_sk); 1169 extern int tcp_v4_md5_do_add(struct sock *sk, __be32 addr, u8 *newkey, 1170 u8 newkeylen); 1171 extern int tcp_v4_md5_do_del(struct sock *sk, __be32 addr); 1172 1173 #ifdef CONFIG_TCP_MD5SIG 1174 #define tcp_twsk_md5_key(twsk) ((twsk)->tw_md5_keylen ? \ 1175 &(struct tcp_md5sig_key) { \ 1176 .key = (twsk)->tw_md5_key, \ 1177 .keylen = (twsk)->tw_md5_keylen, \ 1178 } : NULL) 1179 #else 1180 #define tcp_twsk_md5_key(twsk) NULL 1181 #endif 1182 1183 extern struct tcp_md5sig_pool * __percpu *tcp_alloc_md5sig_pool(struct sock *); 1184 extern void tcp_free_md5sig_pool(void); 1185 1186 extern struct tcp_md5sig_pool *tcp_get_md5sig_pool(void); 1187 extern void tcp_put_md5sig_pool(void); 1188 1189 extern int tcp_md5_hash_header(struct tcp_md5sig_pool *, struct tcphdr *); 1190 extern int tcp_md5_hash_skb_data(struct tcp_md5sig_pool *, struct sk_buff *, 1191 unsigned header_len); 1192 extern int tcp_md5_hash_key(struct tcp_md5sig_pool *hp, 1193 struct tcp_md5sig_key *key); 1194 1195 /* write queue abstraction */ 1196 static inline void tcp_write_queue_purge(struct sock *sk) 1197 { 1198 struct sk_buff *skb; 1199 1200 while ((skb = __skb_dequeue(&sk->sk_write_queue)) != NULL) 1201 sk_wmem_free_skb(sk, skb); 1202 sk_mem_reclaim(sk); 1203 tcp_clear_all_retrans_hints(tcp_sk(sk)); 1204 } 1205 1206 static inline struct sk_buff *tcp_write_queue_head(struct sock *sk) 1207 { 1208 return skb_peek(&sk->sk_write_queue); 1209 } 1210 1211 static inline struct sk_buff *tcp_write_queue_tail(struct sock *sk) 1212 { 1213 return skb_peek_tail(&sk->sk_write_queue); 1214 } 1215 1216 static inline struct sk_buff *tcp_write_queue_next(struct sock *sk, struct sk_buff *skb) 1217 { 1218 return skb_queue_next(&sk->sk_write_queue, skb); 1219 } 1220 1221 static inline struct sk_buff *tcp_write_queue_prev(struct sock *sk, struct sk_buff *skb) 1222 { 1223 return skb_queue_prev(&sk->sk_write_queue, skb); 1224 } 1225 1226 #define tcp_for_write_queue(skb, sk) \ 1227 skb_queue_walk(&(sk)->sk_write_queue, skb) 1228 1229 #define tcp_for_write_queue_from(skb, sk) \ 1230 skb_queue_walk_from(&(sk)->sk_write_queue, skb) 1231 1232 #define tcp_for_write_queue_from_safe(skb, tmp, sk) \ 1233 skb_queue_walk_from_safe(&(sk)->sk_write_queue, skb, tmp) 1234 1235 static inline struct sk_buff *tcp_send_head(struct sock *sk) 1236 { 1237 return sk->sk_send_head; 1238 } 1239 1240 static inline bool tcp_skb_is_last(const struct sock *sk, 1241 const struct sk_buff *skb) 1242 { 1243 return skb_queue_is_last(&sk->sk_write_queue, skb); 1244 } 1245 1246 static inline void tcp_advance_send_head(struct sock *sk, struct sk_buff *skb) 1247 { 1248 if (tcp_skb_is_last(sk, skb)) 1249 sk->sk_send_head = NULL; 1250 else 1251 sk->sk_send_head = tcp_write_queue_next(sk, skb); 1252 } 1253 1254 static inline void tcp_check_send_head(struct sock *sk, struct sk_buff *skb_unlinked) 1255 { 1256 if (sk->sk_send_head == skb_unlinked) 1257 sk->sk_send_head = NULL; 1258 } 1259 1260 static inline void tcp_init_send_head(struct sock *sk) 1261 { 1262 sk->sk_send_head = NULL; 1263 } 1264 1265 static inline void __tcp_add_write_queue_tail(struct sock *sk, struct sk_buff *skb) 1266 { 1267 __skb_queue_tail(&sk->sk_write_queue, skb); 1268 } 1269 1270 static inline void tcp_add_write_queue_tail(struct sock *sk, struct sk_buff *skb) 1271 { 1272 __tcp_add_write_queue_tail(sk, skb); 1273 1274 /* Queue it, remembering where we must start sending. */ 1275 if (sk->sk_send_head == NULL) { 1276 sk->sk_send_head = skb; 1277 1278 if (tcp_sk(sk)->highest_sack == NULL) 1279 tcp_sk(sk)->highest_sack = skb; 1280 } 1281 } 1282 1283 static inline void __tcp_add_write_queue_head(struct sock *sk, struct sk_buff *skb) 1284 { 1285 __skb_queue_head(&sk->sk_write_queue, skb); 1286 } 1287 1288 /* Insert buff after skb on the write queue of sk. */ 1289 static inline void tcp_insert_write_queue_after(struct sk_buff *skb, 1290 struct sk_buff *buff, 1291 struct sock *sk) 1292 { 1293 __skb_queue_after(&sk->sk_write_queue, skb, buff); 1294 } 1295 1296 /* Insert new before skb on the write queue of sk. */ 1297 static inline void tcp_insert_write_queue_before(struct sk_buff *new, 1298 struct sk_buff *skb, 1299 struct sock *sk) 1300 { 1301 __skb_queue_before(&sk->sk_write_queue, skb, new); 1302 1303 if (sk->sk_send_head == skb) 1304 sk->sk_send_head = new; 1305 } 1306 1307 static inline void tcp_unlink_write_queue(struct sk_buff *skb, struct sock *sk) 1308 { 1309 __skb_unlink(skb, &sk->sk_write_queue); 1310 } 1311 1312 static inline int tcp_write_queue_empty(struct sock *sk) 1313 { 1314 return skb_queue_empty(&sk->sk_write_queue); 1315 } 1316 1317 static inline void tcp_push_pending_frames(struct sock *sk) 1318 { 1319 if (tcp_send_head(sk)) { 1320 struct tcp_sock *tp = tcp_sk(sk); 1321 1322 __tcp_push_pending_frames(sk, tcp_current_mss(sk), tp->nonagle); 1323 } 1324 } 1325 1326 /* Start sequence of the highest skb with SACKed bit, valid only if 1327 * sacked > 0 or when the caller has ensured validity by itself. 1328 */ 1329 static inline u32 tcp_highest_sack_seq(struct tcp_sock *tp) 1330 { 1331 if (!tp->sacked_out) 1332 return tp->snd_una; 1333 1334 if (tp->highest_sack == NULL) 1335 return tp->snd_nxt; 1336 1337 return TCP_SKB_CB(tp->highest_sack)->seq; 1338 } 1339 1340 static inline void tcp_advance_highest_sack(struct sock *sk, struct sk_buff *skb) 1341 { 1342 tcp_sk(sk)->highest_sack = tcp_skb_is_last(sk, skb) ? NULL : 1343 tcp_write_queue_next(sk, skb); 1344 } 1345 1346 static inline struct sk_buff *tcp_highest_sack(struct sock *sk) 1347 { 1348 return tcp_sk(sk)->highest_sack; 1349 } 1350 1351 static inline void tcp_highest_sack_reset(struct sock *sk) 1352 { 1353 tcp_sk(sk)->highest_sack = tcp_write_queue_head(sk); 1354 } 1355 1356 /* Called when old skb is about to be deleted (to be combined with new skb) */ 1357 static inline void tcp_highest_sack_combine(struct sock *sk, 1358 struct sk_buff *old, 1359 struct sk_buff *new) 1360 { 1361 if (tcp_sk(sk)->sacked_out && (old == tcp_sk(sk)->highest_sack)) 1362 tcp_sk(sk)->highest_sack = new; 1363 } 1364 1365 /* Determines whether this is a thin stream (which may suffer from 1366 * increased latency). Used to trigger latency-reducing mechanisms. 1367 */ 1368 static inline unsigned int tcp_stream_is_thin(struct tcp_sock *tp) 1369 { 1370 return tp->packets_out < 4 && !tcp_in_initial_slowstart(tp); 1371 } 1372 1373 /* /proc */ 1374 enum tcp_seq_states { 1375 TCP_SEQ_STATE_LISTENING, 1376 TCP_SEQ_STATE_OPENREQ, 1377 TCP_SEQ_STATE_ESTABLISHED, 1378 TCP_SEQ_STATE_TIME_WAIT, 1379 }; 1380 1381 struct tcp_seq_afinfo { 1382 char *name; 1383 sa_family_t family; 1384 struct file_operations seq_fops; 1385 struct seq_operations seq_ops; 1386 }; 1387 1388 struct tcp_iter_state { 1389 struct seq_net_private p; 1390 sa_family_t family; 1391 enum tcp_seq_states state; 1392 struct sock *syn_wait_sk; 1393 int bucket, offset, sbucket, num, uid; 1394 loff_t last_pos; 1395 }; 1396 1397 extern int tcp_proc_register(struct net *net, struct tcp_seq_afinfo *afinfo); 1398 extern void tcp_proc_unregister(struct net *net, struct tcp_seq_afinfo *afinfo); 1399 1400 extern struct request_sock_ops tcp_request_sock_ops; 1401 extern struct request_sock_ops tcp6_request_sock_ops; 1402 1403 extern void tcp_v4_destroy_sock(struct sock *sk); 1404 1405 extern int tcp_v4_gso_send_check(struct sk_buff *skb); 1406 extern struct sk_buff *tcp_tso_segment(struct sk_buff *skb, u32 features); 1407 extern struct sk_buff **tcp_gro_receive(struct sk_buff **head, 1408 struct sk_buff *skb); 1409 extern struct sk_buff **tcp4_gro_receive(struct sk_buff **head, 1410 struct sk_buff *skb); 1411 extern int tcp_gro_complete(struct sk_buff *skb); 1412 extern int tcp4_gro_complete(struct sk_buff *skb); 1413 1414 #ifdef CONFIG_PROC_FS 1415 extern int tcp4_proc_init(void); 1416 extern void tcp4_proc_exit(void); 1417 #endif 1418 1419 /* TCP af-specific functions */ 1420 struct tcp_sock_af_ops { 1421 #ifdef CONFIG_TCP_MD5SIG 1422 struct tcp_md5sig_key *(*md5_lookup) (struct sock *sk, 1423 struct sock *addr_sk); 1424 int (*calc_md5_hash) (char *location, 1425 struct tcp_md5sig_key *md5, 1426 struct sock *sk, 1427 struct request_sock *req, 1428 struct sk_buff *skb); 1429 int (*md5_add) (struct sock *sk, 1430 struct sock *addr_sk, 1431 u8 *newkey, 1432 u8 len); 1433 int (*md5_parse) (struct sock *sk, 1434 char __user *optval, 1435 int optlen); 1436 #endif 1437 }; 1438 1439 struct tcp_request_sock_ops { 1440 #ifdef CONFIG_TCP_MD5SIG 1441 struct tcp_md5sig_key *(*md5_lookup) (struct sock *sk, 1442 struct request_sock *req); 1443 int (*calc_md5_hash) (char *location, 1444 struct tcp_md5sig_key *md5, 1445 struct sock *sk, 1446 struct request_sock *req, 1447 struct sk_buff *skb); 1448 #endif 1449 }; 1450 1451 /* Using SHA1 for now, define some constants. 1452 */ 1453 #define COOKIE_DIGEST_WORDS (SHA_DIGEST_WORDS) 1454 #define COOKIE_MESSAGE_WORDS (SHA_MESSAGE_BYTES / 4) 1455 #define COOKIE_WORKSPACE_WORDS (COOKIE_DIGEST_WORDS + COOKIE_MESSAGE_WORDS) 1456 1457 extern int tcp_cookie_generator(u32 *bakery); 1458 1459 /** 1460 * struct tcp_cookie_values - each socket needs extra space for the 1461 * cookies, together with (optional) space for any SYN data. 1462 * 1463 * A tcp_sock contains a pointer to the current value, and this is 1464 * cloned to the tcp_timewait_sock. 1465 * 1466 * @cookie_pair: variable data from the option exchange. 1467 * 1468 * @cookie_desired: user specified tcpct_cookie_desired. Zero 1469 * indicates default (sysctl_tcp_cookie_size). 1470 * After cookie sent, remembers size of cookie. 1471 * Range 0, TCP_COOKIE_MIN to TCP_COOKIE_MAX. 1472 * 1473 * @s_data_desired: user specified tcpct_s_data_desired. When the 1474 * constant payload is specified (@s_data_constant), 1475 * holds its length instead. 1476 * Range 0 to TCP_MSS_DESIRED. 1477 * 1478 * @s_data_payload: constant data that is to be included in the 1479 * payload of SYN or SYNACK segments when the 1480 * cookie option is present. 1481 */ 1482 struct tcp_cookie_values { 1483 struct kref kref; 1484 u8 cookie_pair[TCP_COOKIE_PAIR_SIZE]; 1485 u8 cookie_pair_size; 1486 u8 cookie_desired; 1487 u16 s_data_desired:11, 1488 s_data_constant:1, 1489 s_data_in:1, 1490 s_data_out:1, 1491 s_data_unused:2; 1492 u8 s_data_payload[0]; 1493 }; 1494 1495 static inline void tcp_cookie_values_release(struct kref *kref) 1496 { 1497 kfree(container_of(kref, struct tcp_cookie_values, kref)); 1498 } 1499 1500 /* The length of constant payload data. Note that s_data_desired is 1501 * overloaded, depending on s_data_constant: either the length of constant 1502 * data (returned here) or the limit on variable data. 1503 */ 1504 static inline int tcp_s_data_size(const struct tcp_sock *tp) 1505 { 1506 return (tp->cookie_values != NULL && tp->cookie_values->s_data_constant) 1507 ? tp->cookie_values->s_data_desired 1508 : 0; 1509 } 1510 1511 /** 1512 * struct tcp_extend_values - tcp_ipv?.c to tcp_output.c workspace. 1513 * 1514 * As tcp_request_sock has already been extended in other places, the 1515 * only remaining method is to pass stack values along as function 1516 * parameters. These parameters are not needed after sending SYNACK. 1517 * 1518 * @cookie_bakery: cryptographic secret and message workspace. 1519 * 1520 * @cookie_plus: bytes in authenticator/cookie option, copied from 1521 * struct tcp_options_received (above). 1522 */ 1523 struct tcp_extend_values { 1524 struct request_values rv; 1525 u32 cookie_bakery[COOKIE_WORKSPACE_WORDS]; 1526 u8 cookie_plus:6, 1527 cookie_out_never:1, 1528 cookie_in_always:1; 1529 }; 1530 1531 static inline struct tcp_extend_values *tcp_xv(struct request_values *rvp) 1532 { 1533 return (struct tcp_extend_values *)rvp; 1534 } 1535 1536 extern void tcp_v4_init(void); 1537 extern void tcp_init(void); 1538 1539 #endif /* _TCP_H */ 1540