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 FASTRETRANS_DEBUG 1 22 23 #include <linux/list.h> 24 #include <linux/tcp.h> 25 #include <linux/bug.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 #include <linux/memcontrol.h> 49 50 extern struct inet_hashinfo tcp_hashinfo; 51 52 extern struct percpu_counter tcp_orphan_count; 53 extern void tcp_time_wait(struct sock *sk, int state, int timeo); 54 55 #define MAX_TCP_HEADER (128 + MAX_HEADER) 56 #define MAX_TCP_OPTION_SPACE 40 57 58 /* 59 * Never offer a window over 32767 without using window scaling. Some 60 * poor stacks do signed 16bit maths! 61 */ 62 #define MAX_TCP_WINDOW 32767U 63 64 /* Offer an initial receive window of 10 mss. */ 65 #define TCP_DEFAULT_INIT_RCVWND 10 66 67 /* Minimal accepted MSS. It is (60+60+8) - (20+20). */ 68 #define TCP_MIN_MSS 88U 69 70 /* The least MTU to use for probing */ 71 #define TCP_BASE_MSS 512 72 73 /* After receiving this amount of duplicate ACKs fast retransmit starts. */ 74 #define TCP_FASTRETRANS_THRESH 3 75 76 /* Maximal reordering. */ 77 #define TCP_MAX_REORDERING 127 78 79 /* Maximal number of ACKs sent quickly to accelerate slow-start. */ 80 #define TCP_MAX_QUICKACKS 16U 81 82 /* urg_data states */ 83 #define TCP_URG_VALID 0x0100 84 #define TCP_URG_NOTYET 0x0200 85 #define TCP_URG_READ 0x0400 86 87 #define TCP_RETR1 3 /* 88 * This is how many retries it does before it 89 * tries to figure out if the gateway is 90 * down. Minimal RFC value is 3; it corresponds 91 * to ~3sec-8min depending on RTO. 92 */ 93 94 #define TCP_RETR2 15 /* 95 * This should take at least 96 * 90 minutes to time out. 97 * RFC1122 says that the limit is 100 sec. 98 * 15 is ~13-30min depending on RTO. 99 */ 100 101 #define TCP_SYN_RETRIES 6 /* This is how many retries are done 102 * when active opening a connection. 103 * RFC1122 says the minimum retry MUST 104 * be at least 180secs. Nevertheless 105 * this value is corresponding to 106 * 63secs of retransmission with the 107 * current initial RTO. 108 */ 109 110 #define TCP_SYNACK_RETRIES 5 /* This is how may retries are done 111 * when passive opening a connection. 112 * This is corresponding to 31secs of 113 * retransmission with the current 114 * initial RTO. 115 */ 116 117 #define TCP_TIMEWAIT_LEN (60*HZ) /* how long to wait to destroy TIME-WAIT 118 * state, about 60 seconds */ 119 #define TCP_FIN_TIMEOUT TCP_TIMEWAIT_LEN 120 /* BSD style FIN_WAIT2 deadlock breaker. 121 * It used to be 3min, new value is 60sec, 122 * to combine FIN-WAIT-2 timeout with 123 * TIME-WAIT timer. 124 */ 125 126 #define TCP_DELACK_MAX ((unsigned)(HZ/5)) /* maximal time to delay before sending an ACK */ 127 #if HZ >= 100 128 #define TCP_DELACK_MIN ((unsigned)(HZ/25)) /* minimal time to delay before sending an ACK */ 129 #define TCP_ATO_MIN ((unsigned)(HZ/25)) 130 #else 131 #define TCP_DELACK_MIN 4U 132 #define TCP_ATO_MIN 4U 133 #endif 134 #define TCP_RTO_MAX ((unsigned)(120*HZ)) 135 #define TCP_RTO_MIN ((unsigned)(HZ/5)) 136 #define TCP_TIMEOUT_INIT ((unsigned)(1*HZ)) /* RFC6298 2.1 initial RTO value */ 137 #define TCP_TIMEOUT_FALLBACK ((unsigned)(3*HZ)) /* RFC 1122 initial RTO value, now 138 * used as a fallback RTO for the 139 * initial data transmission if no 140 * valid RTT sample has been acquired, 141 * most likely due to retrans in 3WHS. 142 */ 143 144 #define TCP_RESOURCE_PROBE_INTERVAL ((unsigned)(HZ/2U)) /* Maximal interval between probes 145 * for local resources. 146 */ 147 148 #define TCP_KEEPALIVE_TIME (120*60*HZ) /* two hours */ 149 #define TCP_KEEPALIVE_PROBES 9 /* Max of 9 keepalive probes */ 150 #define TCP_KEEPALIVE_INTVL (75*HZ) 151 152 #define MAX_TCP_KEEPIDLE 32767 153 #define MAX_TCP_KEEPINTVL 32767 154 #define MAX_TCP_KEEPCNT 127 155 #define MAX_TCP_SYNCNT 127 156 157 #define TCP_SYNQ_INTERVAL (HZ/5) /* Period of SYNACK timer */ 158 159 #define TCP_PAWS_24DAYS (60 * 60 * 24 * 24) 160 #define TCP_PAWS_MSL 60 /* Per-host timestamps are invalidated 161 * after this time. It should be equal 162 * (or greater than) TCP_TIMEWAIT_LEN 163 * to provide reliability equal to one 164 * provided by timewait state. 165 */ 166 #define TCP_PAWS_WINDOW 1 /* Replay window for per-host 167 * timestamps. It must be less than 168 * minimal timewait lifetime. 169 */ 170 /* 171 * TCP option 172 */ 173 174 #define TCPOPT_NOP 1 /* Padding */ 175 #define TCPOPT_EOL 0 /* End of options */ 176 #define TCPOPT_MSS 2 /* Segment size negotiating */ 177 #define TCPOPT_WINDOW 3 /* Window scaling */ 178 #define TCPOPT_SACK_PERM 4 /* SACK Permitted */ 179 #define TCPOPT_SACK 5 /* SACK Block */ 180 #define TCPOPT_TIMESTAMP 8 /* Better RTT estimations/PAWS */ 181 #define TCPOPT_MD5SIG 19 /* MD5 Signature (RFC2385) */ 182 #define TCPOPT_COOKIE 253 /* Cookie extension (experimental) */ 183 #define TCPOPT_EXP 254 /* Experimental */ 184 /* Magic number to be after the option value for sharing TCP 185 * experimental options. See draft-ietf-tcpm-experimental-options-00.txt 186 */ 187 #define TCPOPT_FASTOPEN_MAGIC 0xF989 188 189 /* 190 * TCP option lengths 191 */ 192 193 #define TCPOLEN_MSS 4 194 #define TCPOLEN_WINDOW 3 195 #define TCPOLEN_SACK_PERM 2 196 #define TCPOLEN_TIMESTAMP 10 197 #define TCPOLEN_MD5SIG 18 198 #define TCPOLEN_EXP_FASTOPEN_BASE 4 199 #define TCPOLEN_COOKIE_BASE 2 /* Cookie-less header extension */ 200 #define TCPOLEN_COOKIE_PAIR 3 /* Cookie pair header extension */ 201 #define TCPOLEN_COOKIE_MIN (TCPOLEN_COOKIE_BASE+TCP_COOKIE_MIN) 202 #define TCPOLEN_COOKIE_MAX (TCPOLEN_COOKIE_BASE+TCP_COOKIE_MAX) 203 204 /* But this is what stacks really send out. */ 205 #define TCPOLEN_TSTAMP_ALIGNED 12 206 #define TCPOLEN_WSCALE_ALIGNED 4 207 #define TCPOLEN_SACKPERM_ALIGNED 4 208 #define TCPOLEN_SACK_BASE 2 209 #define TCPOLEN_SACK_BASE_ALIGNED 4 210 #define TCPOLEN_SACK_PERBLOCK 8 211 #define TCPOLEN_MD5SIG_ALIGNED 20 212 #define TCPOLEN_MSS_ALIGNED 4 213 214 /* Flags in tp->nonagle */ 215 #define TCP_NAGLE_OFF 1 /* Nagle's algo is disabled */ 216 #define TCP_NAGLE_CORK 2 /* Socket is corked */ 217 #define TCP_NAGLE_PUSH 4 /* Cork is overridden for already queued data */ 218 219 /* TCP thin-stream limits */ 220 #define TCP_THIN_LINEAR_RETRIES 6 /* After 6 linear retries, do exp. backoff */ 221 222 /* TCP initial congestion window as per draft-hkchu-tcpm-initcwnd-01 */ 223 #define TCP_INIT_CWND 10 224 225 /* Bit Flags for sysctl_tcp_fastopen */ 226 #define TFO_CLIENT_ENABLE 1 227 #define TFO_SERVER_ENABLE 2 228 #define TFO_CLIENT_NO_COOKIE 4 /* Data in SYN w/o cookie option */ 229 230 /* Process SYN data but skip cookie validation */ 231 #define TFO_SERVER_COOKIE_NOT_CHKED 0x100 232 /* Accept SYN data w/o any cookie option */ 233 #define TFO_SERVER_COOKIE_NOT_REQD 0x200 234 235 /* Force enable TFO on all listeners, i.e., not requiring the 236 * TCP_FASTOPEN socket option. SOCKOPT1/2 determine how to set max_qlen. 237 */ 238 #define TFO_SERVER_WO_SOCKOPT1 0x400 239 #define TFO_SERVER_WO_SOCKOPT2 0x800 240 /* Always create TFO child sockets on a TFO listener even when 241 * cookie/data not present. (For testing purpose!) 242 */ 243 #define TFO_SERVER_ALWAYS 0x1000 244 245 extern struct inet_timewait_death_row tcp_death_row; 246 247 /* sysctl variables for tcp */ 248 extern int sysctl_tcp_timestamps; 249 extern int sysctl_tcp_window_scaling; 250 extern int sysctl_tcp_sack; 251 extern int sysctl_tcp_fin_timeout; 252 extern int sysctl_tcp_keepalive_time; 253 extern int sysctl_tcp_keepalive_probes; 254 extern int sysctl_tcp_keepalive_intvl; 255 extern int sysctl_tcp_syn_retries; 256 extern int sysctl_tcp_synack_retries; 257 extern int sysctl_tcp_retries1; 258 extern int sysctl_tcp_retries2; 259 extern int sysctl_tcp_orphan_retries; 260 extern int sysctl_tcp_syncookies; 261 extern int sysctl_tcp_fastopen; 262 extern int sysctl_tcp_retrans_collapse; 263 extern int sysctl_tcp_stdurg; 264 extern int sysctl_tcp_rfc1337; 265 extern int sysctl_tcp_abort_on_overflow; 266 extern int sysctl_tcp_max_orphans; 267 extern int sysctl_tcp_fack; 268 extern int sysctl_tcp_reordering; 269 extern int sysctl_tcp_dsack; 270 extern int sysctl_tcp_wmem[3]; 271 extern int sysctl_tcp_rmem[3]; 272 extern int sysctl_tcp_app_win; 273 extern int sysctl_tcp_adv_win_scale; 274 extern int sysctl_tcp_tw_reuse; 275 extern int sysctl_tcp_frto; 276 extern int sysctl_tcp_frto_response; 277 extern int sysctl_tcp_low_latency; 278 extern int sysctl_tcp_dma_copybreak; 279 extern int sysctl_tcp_nometrics_save; 280 extern int sysctl_tcp_moderate_rcvbuf; 281 extern int sysctl_tcp_tso_win_divisor; 282 extern int sysctl_tcp_mtu_probing; 283 extern int sysctl_tcp_base_mss; 284 extern int sysctl_tcp_workaround_signed_windows; 285 extern int sysctl_tcp_slow_start_after_idle; 286 extern int sysctl_tcp_max_ssthresh; 287 extern int sysctl_tcp_cookie_size; 288 extern int sysctl_tcp_thin_linear_timeouts; 289 extern int sysctl_tcp_thin_dupack; 290 extern int sysctl_tcp_early_retrans; 291 extern int sysctl_tcp_limit_output_bytes; 292 extern int sysctl_tcp_challenge_ack_limit; 293 294 extern atomic_long_t tcp_memory_allocated; 295 extern struct percpu_counter tcp_sockets_allocated; 296 extern int tcp_memory_pressure; 297 298 /* 299 * The next routines deal with comparing 32 bit unsigned ints 300 * and worry about wraparound (automatic with unsigned arithmetic). 301 */ 302 303 static inline bool before(__u32 seq1, __u32 seq2) 304 { 305 return (__s32)(seq1-seq2) < 0; 306 } 307 #define after(seq2, seq1) before(seq1, seq2) 308 309 /* is s2<=s1<=s3 ? */ 310 static inline bool between(__u32 seq1, __u32 seq2, __u32 seq3) 311 { 312 return seq3 - seq2 >= seq1 - seq2; 313 } 314 315 static inline bool tcp_out_of_memory(struct sock *sk) 316 { 317 if (sk->sk_wmem_queued > SOCK_MIN_SNDBUF && 318 sk_memory_allocated(sk) > sk_prot_mem_limits(sk, 2)) 319 return true; 320 return false; 321 } 322 323 static inline bool tcp_too_many_orphans(struct sock *sk, int shift) 324 { 325 struct percpu_counter *ocp = sk->sk_prot->orphan_count; 326 int orphans = percpu_counter_read_positive(ocp); 327 328 if (orphans << shift > sysctl_tcp_max_orphans) { 329 orphans = percpu_counter_sum_positive(ocp); 330 if (orphans << shift > sysctl_tcp_max_orphans) 331 return true; 332 } 333 return false; 334 } 335 336 extern bool tcp_check_oom(struct sock *sk, int shift); 337 338 /* syncookies: remember time of last synqueue overflow */ 339 static inline void tcp_synq_overflow(struct sock *sk) 340 { 341 tcp_sk(sk)->rx_opt.ts_recent_stamp = jiffies; 342 } 343 344 /* syncookies: no recent synqueue overflow on this listening socket? */ 345 static inline bool tcp_synq_no_recent_overflow(const struct sock *sk) 346 { 347 unsigned long last_overflow = tcp_sk(sk)->rx_opt.ts_recent_stamp; 348 return time_after(jiffies, last_overflow + TCP_TIMEOUT_FALLBACK); 349 } 350 351 extern struct proto tcp_prot; 352 353 #define TCP_INC_STATS(net, field) SNMP_INC_STATS((net)->mib.tcp_statistics, field) 354 #define TCP_INC_STATS_BH(net, field) SNMP_INC_STATS_BH((net)->mib.tcp_statistics, field) 355 #define TCP_DEC_STATS(net, field) SNMP_DEC_STATS((net)->mib.tcp_statistics, field) 356 #define TCP_ADD_STATS_USER(net, field, val) SNMP_ADD_STATS_USER((net)->mib.tcp_statistics, field, val) 357 #define TCP_ADD_STATS(net, field, val) SNMP_ADD_STATS((net)->mib.tcp_statistics, field, val) 358 359 extern void tcp_init_mem(struct net *net); 360 361 extern void tcp_tasklet_init(void); 362 363 extern void tcp_v4_err(struct sk_buff *skb, u32); 364 365 extern void tcp_shutdown (struct sock *sk, int how); 366 367 extern void tcp_v4_early_demux(struct sk_buff *skb); 368 extern int tcp_v4_rcv(struct sk_buff *skb); 369 370 extern int tcp_v4_tw_remember_stamp(struct inet_timewait_sock *tw); 371 extern int tcp_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg, 372 size_t size); 373 extern int tcp_sendpage(struct sock *sk, struct page *page, int offset, 374 size_t size, int flags); 375 extern void tcp_release_cb(struct sock *sk); 376 extern void tcp_write_timer_handler(struct sock *sk); 377 extern void tcp_delack_timer_handler(struct sock *sk); 378 extern int tcp_ioctl(struct sock *sk, int cmd, unsigned long arg); 379 extern int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb, 380 const struct tcphdr *th, unsigned int len); 381 extern int tcp_rcv_established(struct sock *sk, struct sk_buff *skb, 382 const struct tcphdr *th, unsigned int len); 383 extern void tcp_rcv_space_adjust(struct sock *sk); 384 extern void tcp_cleanup_rbuf(struct sock *sk, int copied); 385 extern int tcp_twsk_unique(struct sock *sk, struct sock *sktw, void *twp); 386 extern void tcp_twsk_destructor(struct sock *sk); 387 extern ssize_t tcp_splice_read(struct socket *sk, loff_t *ppos, 388 struct pipe_inode_info *pipe, size_t len, 389 unsigned int flags); 390 391 static inline void tcp_dec_quickack_mode(struct sock *sk, 392 const unsigned int pkts) 393 { 394 struct inet_connection_sock *icsk = inet_csk(sk); 395 396 if (icsk->icsk_ack.quick) { 397 if (pkts >= icsk->icsk_ack.quick) { 398 icsk->icsk_ack.quick = 0; 399 /* Leaving quickack mode we deflate ATO. */ 400 icsk->icsk_ack.ato = TCP_ATO_MIN; 401 } else 402 icsk->icsk_ack.quick -= pkts; 403 } 404 } 405 406 #define TCP_ECN_OK 1 407 #define TCP_ECN_QUEUE_CWR 2 408 #define TCP_ECN_DEMAND_CWR 4 409 #define TCP_ECN_SEEN 8 410 411 enum tcp_tw_status { 412 TCP_TW_SUCCESS = 0, 413 TCP_TW_RST = 1, 414 TCP_TW_ACK = 2, 415 TCP_TW_SYN = 3 416 }; 417 418 419 extern enum tcp_tw_status tcp_timewait_state_process(struct inet_timewait_sock *tw, 420 struct sk_buff *skb, 421 const struct tcphdr *th); 422 extern struct sock * tcp_check_req(struct sock *sk,struct sk_buff *skb, 423 struct request_sock *req, 424 struct request_sock **prev, 425 bool fastopen); 426 extern int tcp_child_process(struct sock *parent, struct sock *child, 427 struct sk_buff *skb); 428 extern bool tcp_use_frto(struct sock *sk); 429 extern void tcp_enter_frto(struct sock *sk); 430 extern void tcp_enter_loss(struct sock *sk, int how); 431 extern void tcp_clear_retrans(struct tcp_sock *tp); 432 extern void tcp_update_metrics(struct sock *sk); 433 extern void tcp_init_metrics(struct sock *sk); 434 extern void tcp_metrics_init(void); 435 extern bool tcp_peer_is_proven(struct request_sock *req, struct dst_entry *dst, bool paws_check); 436 extern bool tcp_remember_stamp(struct sock *sk); 437 extern bool tcp_tw_remember_stamp(struct inet_timewait_sock *tw); 438 extern void tcp_fetch_timewait_stamp(struct sock *sk, struct dst_entry *dst); 439 extern void tcp_disable_fack(struct tcp_sock *tp); 440 extern void tcp_close(struct sock *sk, long timeout); 441 extern void tcp_init_sock(struct sock *sk); 442 extern unsigned int tcp_poll(struct file * file, struct socket *sock, 443 struct poll_table_struct *wait); 444 extern int tcp_getsockopt(struct sock *sk, int level, int optname, 445 char __user *optval, int __user *optlen); 446 extern int tcp_setsockopt(struct sock *sk, int level, int optname, 447 char __user *optval, unsigned int optlen); 448 extern int compat_tcp_getsockopt(struct sock *sk, int level, int optname, 449 char __user *optval, int __user *optlen); 450 extern int compat_tcp_setsockopt(struct sock *sk, int level, int optname, 451 char __user *optval, unsigned int optlen); 452 extern void tcp_set_keepalive(struct sock *sk, int val); 453 extern void tcp_syn_ack_timeout(struct sock *sk, struct request_sock *req); 454 extern int tcp_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg, 455 size_t len, int nonblock, int flags, int *addr_len); 456 extern void tcp_parse_options(const struct sk_buff *skb, 457 struct tcp_options_received *opt_rx, const u8 **hvpp, 458 int estab, struct tcp_fastopen_cookie *foc); 459 extern const u8 *tcp_parse_md5sig_option(const struct tcphdr *th); 460 461 /* 462 * TCP v4 functions exported for the inet6 API 463 */ 464 465 extern void tcp_v4_send_check(struct sock *sk, struct sk_buff *skb); 466 extern int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb); 467 extern struct sock * tcp_create_openreq_child(struct sock *sk, 468 struct request_sock *req, 469 struct sk_buff *skb); 470 extern struct sock * tcp_v4_syn_recv_sock(struct sock *sk, struct sk_buff *skb, 471 struct request_sock *req, 472 struct dst_entry *dst); 473 extern int tcp_v4_do_rcv(struct sock *sk, struct sk_buff *skb); 474 extern int tcp_v4_connect(struct sock *sk, struct sockaddr *uaddr, 475 int addr_len); 476 extern int tcp_connect(struct sock *sk); 477 extern struct sk_buff * tcp_make_synack(struct sock *sk, struct dst_entry *dst, 478 struct request_sock *req, 479 struct request_values *rvp, 480 struct tcp_fastopen_cookie *foc); 481 extern int tcp_disconnect(struct sock *sk, int flags); 482 483 void tcp_connect_init(struct sock *sk); 484 void tcp_finish_connect(struct sock *sk, struct sk_buff *skb); 485 int tcp_send_rcvq(struct sock *sk, struct msghdr *msg, size_t size); 486 void inet_sk_rx_dst_set(struct sock *sk, const struct sk_buff *skb); 487 488 /* From syncookies.c */ 489 extern __u32 syncookie_secret[2][16-4+SHA_DIGEST_WORDS]; 490 extern struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb, 491 struct ip_options *opt); 492 #ifdef CONFIG_SYN_COOKIES 493 extern __u32 cookie_v4_init_sequence(struct sock *sk, struct sk_buff *skb, 494 __u16 *mss); 495 #else 496 static inline __u32 cookie_v4_init_sequence(struct sock *sk, 497 struct sk_buff *skb, 498 __u16 *mss) 499 { 500 return 0; 501 } 502 #endif 503 504 extern __u32 cookie_init_timestamp(struct request_sock *req); 505 extern bool cookie_check_timestamp(struct tcp_options_received *opt, 506 struct net *net, bool *ecn_ok); 507 508 /* From net/ipv6/syncookies.c */ 509 extern struct sock *cookie_v6_check(struct sock *sk, struct sk_buff *skb); 510 #ifdef CONFIG_SYN_COOKIES 511 extern __u32 cookie_v6_init_sequence(struct sock *sk, const struct sk_buff *skb, 512 __u16 *mss); 513 #else 514 static inline __u32 cookie_v6_init_sequence(struct sock *sk, 515 struct sk_buff *skb, 516 __u16 *mss) 517 { 518 return 0; 519 } 520 #endif 521 /* tcp_output.c */ 522 523 extern void __tcp_push_pending_frames(struct sock *sk, unsigned int cur_mss, 524 int nonagle); 525 extern bool tcp_may_send_now(struct sock *sk); 526 extern int __tcp_retransmit_skb(struct sock *, struct sk_buff *); 527 extern int tcp_retransmit_skb(struct sock *, struct sk_buff *); 528 extern void tcp_retransmit_timer(struct sock *sk); 529 extern void tcp_xmit_retransmit_queue(struct sock *); 530 extern void tcp_simple_retransmit(struct sock *); 531 extern int tcp_trim_head(struct sock *, struct sk_buff *, u32); 532 extern int tcp_fragment(struct sock *, struct sk_buff *, u32, unsigned int); 533 534 extern void tcp_send_probe0(struct sock *); 535 extern void tcp_send_partial(struct sock *); 536 extern int tcp_write_wakeup(struct sock *); 537 extern void tcp_send_fin(struct sock *sk); 538 extern void tcp_send_active_reset(struct sock *sk, gfp_t priority); 539 extern int tcp_send_synack(struct sock *); 540 extern bool tcp_syn_flood_action(struct sock *sk, 541 const struct sk_buff *skb, 542 const char *proto); 543 extern void tcp_push_one(struct sock *, unsigned int mss_now); 544 extern void tcp_send_ack(struct sock *sk); 545 extern void tcp_send_delayed_ack(struct sock *sk); 546 547 /* tcp_input.c */ 548 extern void tcp_cwnd_application_limited(struct sock *sk); 549 extern void tcp_resume_early_retransmit(struct sock *sk); 550 extern void tcp_rearm_rto(struct sock *sk); 551 extern void tcp_reset(struct sock *sk); 552 553 /* tcp_timer.c */ 554 extern void tcp_init_xmit_timers(struct sock *); 555 static inline void tcp_clear_xmit_timers(struct sock *sk) 556 { 557 inet_csk_clear_xmit_timers(sk); 558 } 559 560 extern unsigned int tcp_sync_mss(struct sock *sk, u32 pmtu); 561 extern unsigned int tcp_current_mss(struct sock *sk); 562 563 /* Bound MSS / TSO packet size with the half of the window */ 564 static inline int tcp_bound_to_half_wnd(struct tcp_sock *tp, int pktsize) 565 { 566 int cutoff; 567 568 /* When peer uses tiny windows, there is no use in packetizing 569 * to sub-MSS pieces for the sake of SWS or making sure there 570 * are enough packets in the pipe for fast recovery. 571 * 572 * On the other hand, for extremely large MSS devices, handling 573 * smaller than MSS windows in this way does make sense. 574 */ 575 if (tp->max_window >= 512) 576 cutoff = (tp->max_window >> 1); 577 else 578 cutoff = tp->max_window; 579 580 if (cutoff && pktsize > cutoff) 581 return max_t(int, cutoff, 68U - tp->tcp_header_len); 582 else 583 return pktsize; 584 } 585 586 /* tcp.c */ 587 extern void tcp_get_info(const struct sock *, struct tcp_info *); 588 589 /* Read 'sendfile()'-style from a TCP socket */ 590 typedef int (*sk_read_actor_t)(read_descriptor_t *, struct sk_buff *, 591 unsigned int, size_t); 592 extern int tcp_read_sock(struct sock *sk, read_descriptor_t *desc, 593 sk_read_actor_t recv_actor); 594 595 extern void tcp_initialize_rcv_mss(struct sock *sk); 596 597 extern int tcp_mtu_to_mss(struct sock *sk, int pmtu); 598 extern int tcp_mss_to_mtu(struct sock *sk, int mss); 599 extern void tcp_mtup_init(struct sock *sk); 600 extern void tcp_valid_rtt_meas(struct sock *sk, u32 seq_rtt); 601 extern void tcp_init_buffer_space(struct sock *sk); 602 603 static inline void tcp_bound_rto(const struct sock *sk) 604 { 605 if (inet_csk(sk)->icsk_rto > TCP_RTO_MAX) 606 inet_csk(sk)->icsk_rto = TCP_RTO_MAX; 607 } 608 609 static inline u32 __tcp_set_rto(const struct tcp_sock *tp) 610 { 611 return (tp->srtt >> 3) + tp->rttvar; 612 } 613 614 extern void tcp_set_rto(struct sock *sk); 615 616 static inline void __tcp_fast_path_on(struct tcp_sock *tp, u32 snd_wnd) 617 { 618 tp->pred_flags = htonl((tp->tcp_header_len << 26) | 619 ntohl(TCP_FLAG_ACK) | 620 snd_wnd); 621 } 622 623 static inline void tcp_fast_path_on(struct tcp_sock *tp) 624 { 625 __tcp_fast_path_on(tp, tp->snd_wnd >> tp->rx_opt.snd_wscale); 626 } 627 628 static inline void tcp_fast_path_check(struct sock *sk) 629 { 630 struct tcp_sock *tp = tcp_sk(sk); 631 632 if (skb_queue_empty(&tp->out_of_order_queue) && 633 tp->rcv_wnd && 634 atomic_read(&sk->sk_rmem_alloc) < sk->sk_rcvbuf && 635 !tp->urg_data) 636 tcp_fast_path_on(tp); 637 } 638 639 /* Compute the actual rto_min value */ 640 static inline u32 tcp_rto_min(struct sock *sk) 641 { 642 const struct dst_entry *dst = __sk_dst_get(sk); 643 u32 rto_min = TCP_RTO_MIN; 644 645 if (dst && dst_metric_locked(dst, RTAX_RTO_MIN)) 646 rto_min = dst_metric_rtt(dst, RTAX_RTO_MIN); 647 return rto_min; 648 } 649 650 /* Compute the actual receive window we are currently advertising. 651 * Rcv_nxt can be after the window if our peer push more data 652 * than the offered window. 653 */ 654 static inline u32 tcp_receive_window(const struct tcp_sock *tp) 655 { 656 s32 win = tp->rcv_wup + tp->rcv_wnd - tp->rcv_nxt; 657 658 if (win < 0) 659 win = 0; 660 return (u32) win; 661 } 662 663 /* Choose a new window, without checks for shrinking, and without 664 * scaling applied to the result. The caller does these things 665 * if necessary. This is a "raw" window selection. 666 */ 667 extern u32 __tcp_select_window(struct sock *sk); 668 669 void tcp_send_window_probe(struct sock *sk); 670 671 /* TCP timestamps are only 32-bits, this causes a slight 672 * complication on 64-bit systems since we store a snapshot 673 * of jiffies in the buffer control blocks below. We decided 674 * to use only the low 32-bits of jiffies and hide the ugly 675 * casts with the following macro. 676 */ 677 #define tcp_time_stamp ((__u32)(jiffies)) 678 679 #define tcp_flag_byte(th) (((u_int8_t *)th)[13]) 680 681 #define TCPHDR_FIN 0x01 682 #define TCPHDR_SYN 0x02 683 #define TCPHDR_RST 0x04 684 #define TCPHDR_PSH 0x08 685 #define TCPHDR_ACK 0x10 686 #define TCPHDR_URG 0x20 687 #define TCPHDR_ECE 0x40 688 #define TCPHDR_CWR 0x80 689 690 /* This is what the send packet queuing engine uses to pass 691 * TCP per-packet control information to the transmission code. 692 * We also store the host-order sequence numbers in here too. 693 * This is 44 bytes if IPV6 is enabled. 694 * If this grows please adjust skbuff.h:skbuff->cb[xxx] size appropriately. 695 */ 696 struct tcp_skb_cb { 697 union { 698 struct inet_skb_parm h4; 699 #if IS_ENABLED(CONFIG_IPV6) 700 struct inet6_skb_parm h6; 701 #endif 702 } header; /* For incoming frames */ 703 __u32 seq; /* Starting sequence number */ 704 __u32 end_seq; /* SEQ + FIN + SYN + datalen */ 705 __u32 when; /* used to compute rtt's */ 706 __u8 tcp_flags; /* TCP header flags. (tcp[13]) */ 707 708 __u8 sacked; /* State flags for SACK/FACK. */ 709 #define TCPCB_SACKED_ACKED 0x01 /* SKB ACK'd by a SACK block */ 710 #define TCPCB_SACKED_RETRANS 0x02 /* SKB retransmitted */ 711 #define TCPCB_LOST 0x04 /* SKB is lost */ 712 #define TCPCB_TAGBITS 0x07 /* All tag bits */ 713 #define TCPCB_EVER_RETRANS 0x80 /* Ever retransmitted frame */ 714 #define TCPCB_RETRANS (TCPCB_SACKED_RETRANS|TCPCB_EVER_RETRANS) 715 716 __u8 ip_dsfield; /* IPv4 tos or IPv6 dsfield */ 717 /* 1 byte hole */ 718 __u32 ack_seq; /* Sequence number ACK'd */ 719 }; 720 721 #define TCP_SKB_CB(__skb) ((struct tcp_skb_cb *)&((__skb)->cb[0])) 722 723 /* RFC3168 : 6.1.1 SYN packets must not have ECT/ECN bits set 724 * 725 * If we receive a SYN packet with these bits set, it means a network is 726 * playing bad games with TOS bits. In order to avoid possible false congestion 727 * notifications, we disable TCP ECN negociation. 728 */ 729 static inline void 730 TCP_ECN_create_request(struct request_sock *req, const struct sk_buff *skb, 731 struct net *net) 732 { 733 const struct tcphdr *th = tcp_hdr(skb); 734 735 if (net->ipv4.sysctl_tcp_ecn && th->ece && th->cwr && 736 INET_ECN_is_not_ect(TCP_SKB_CB(skb)->ip_dsfield)) 737 inet_rsk(req)->ecn_ok = 1; 738 } 739 740 /* Due to TSO, an SKB can be composed of multiple actual 741 * packets. To keep these tracked properly, we use this. 742 */ 743 static inline int tcp_skb_pcount(const struct sk_buff *skb) 744 { 745 return skb_shinfo(skb)->gso_segs; 746 } 747 748 /* This is valid iff tcp_skb_pcount() > 1. */ 749 static inline int tcp_skb_mss(const struct sk_buff *skb) 750 { 751 return skb_shinfo(skb)->gso_size; 752 } 753 754 /* Events passed to congestion control interface */ 755 enum tcp_ca_event { 756 CA_EVENT_TX_START, /* first transmit when no packets in flight */ 757 CA_EVENT_CWND_RESTART, /* congestion window restart */ 758 CA_EVENT_COMPLETE_CWR, /* end of congestion recovery */ 759 CA_EVENT_FRTO, /* fast recovery timeout */ 760 CA_EVENT_LOSS, /* loss timeout */ 761 CA_EVENT_FAST_ACK, /* in sequence ack */ 762 CA_EVENT_SLOW_ACK, /* other ack */ 763 }; 764 765 /* 766 * Interface for adding new TCP congestion control handlers 767 */ 768 #define TCP_CA_NAME_MAX 16 769 #define TCP_CA_MAX 128 770 #define TCP_CA_BUF_MAX (TCP_CA_NAME_MAX*TCP_CA_MAX) 771 772 #define TCP_CONG_NON_RESTRICTED 0x1 773 #define TCP_CONG_RTT_STAMP 0x2 774 775 struct tcp_congestion_ops { 776 struct list_head list; 777 unsigned long flags; 778 779 /* initialize private data (optional) */ 780 void (*init)(struct sock *sk); 781 /* cleanup private data (optional) */ 782 void (*release)(struct sock *sk); 783 784 /* return slow start threshold (required) */ 785 u32 (*ssthresh)(struct sock *sk); 786 /* lower bound for congestion window (optional) */ 787 u32 (*min_cwnd)(const struct sock *sk); 788 /* do new cwnd calculation (required) */ 789 void (*cong_avoid)(struct sock *sk, u32 ack, u32 in_flight); 790 /* call before changing ca_state (optional) */ 791 void (*set_state)(struct sock *sk, u8 new_state); 792 /* call when cwnd event occurs (optional) */ 793 void (*cwnd_event)(struct sock *sk, enum tcp_ca_event ev); 794 /* new value of cwnd after loss (optional) */ 795 u32 (*undo_cwnd)(struct sock *sk); 796 /* hook for packet ack accounting (optional) */ 797 void (*pkts_acked)(struct sock *sk, u32 num_acked, s32 rtt_us); 798 /* get info for inet_diag (optional) */ 799 void (*get_info)(struct sock *sk, u32 ext, struct sk_buff *skb); 800 801 char name[TCP_CA_NAME_MAX]; 802 struct module *owner; 803 }; 804 805 extern int tcp_register_congestion_control(struct tcp_congestion_ops *type); 806 extern void tcp_unregister_congestion_control(struct tcp_congestion_ops *type); 807 808 extern void tcp_init_congestion_control(struct sock *sk); 809 extern void tcp_cleanup_congestion_control(struct sock *sk); 810 extern int tcp_set_default_congestion_control(const char *name); 811 extern void tcp_get_default_congestion_control(char *name); 812 extern void tcp_get_available_congestion_control(char *buf, size_t len); 813 extern void tcp_get_allowed_congestion_control(char *buf, size_t len); 814 extern int tcp_set_allowed_congestion_control(char *allowed); 815 extern int tcp_set_congestion_control(struct sock *sk, const char *name); 816 extern void tcp_slow_start(struct tcp_sock *tp); 817 extern void tcp_cong_avoid_ai(struct tcp_sock *tp, u32 w); 818 819 extern struct tcp_congestion_ops tcp_init_congestion_ops; 820 extern u32 tcp_reno_ssthresh(struct sock *sk); 821 extern void tcp_reno_cong_avoid(struct sock *sk, u32 ack, u32 in_flight); 822 extern u32 tcp_reno_min_cwnd(const struct sock *sk); 823 extern struct tcp_congestion_ops tcp_reno; 824 825 static inline void tcp_set_ca_state(struct sock *sk, const u8 ca_state) 826 { 827 struct inet_connection_sock *icsk = inet_csk(sk); 828 829 if (icsk->icsk_ca_ops->set_state) 830 icsk->icsk_ca_ops->set_state(sk, ca_state); 831 icsk->icsk_ca_state = ca_state; 832 } 833 834 static inline void tcp_ca_event(struct sock *sk, const enum tcp_ca_event event) 835 { 836 const struct inet_connection_sock *icsk = inet_csk(sk); 837 838 if (icsk->icsk_ca_ops->cwnd_event) 839 icsk->icsk_ca_ops->cwnd_event(sk, event); 840 } 841 842 /* These functions determine how the current flow behaves in respect of SACK 843 * handling. SACK is negotiated with the peer, and therefore it can vary 844 * between different flows. 845 * 846 * tcp_is_sack - SACK enabled 847 * tcp_is_reno - No SACK 848 * tcp_is_fack - FACK enabled, implies SACK enabled 849 */ 850 static inline int tcp_is_sack(const struct tcp_sock *tp) 851 { 852 return tp->rx_opt.sack_ok; 853 } 854 855 static inline bool tcp_is_reno(const struct tcp_sock *tp) 856 { 857 return !tcp_is_sack(tp); 858 } 859 860 static inline bool tcp_is_fack(const struct tcp_sock *tp) 861 { 862 return tp->rx_opt.sack_ok & TCP_FACK_ENABLED; 863 } 864 865 static inline void tcp_enable_fack(struct tcp_sock *tp) 866 { 867 tp->rx_opt.sack_ok |= TCP_FACK_ENABLED; 868 } 869 870 /* TCP early-retransmit (ER) is similar to but more conservative than 871 * the thin-dupack feature. Enable ER only if thin-dupack is disabled. 872 */ 873 static inline void tcp_enable_early_retrans(struct tcp_sock *tp) 874 { 875 tp->do_early_retrans = sysctl_tcp_early_retrans && 876 !sysctl_tcp_thin_dupack && sysctl_tcp_reordering == 3; 877 tp->early_retrans_delayed = 0; 878 } 879 880 static inline void tcp_disable_early_retrans(struct tcp_sock *tp) 881 { 882 tp->do_early_retrans = 0; 883 } 884 885 static inline unsigned int tcp_left_out(const struct tcp_sock *tp) 886 { 887 return tp->sacked_out + tp->lost_out; 888 } 889 890 /* This determines how many packets are "in the network" to the best 891 * of our knowledge. In many cases it is conservative, but where 892 * detailed information is available from the receiver (via SACK 893 * blocks etc.) we can make more aggressive calculations. 894 * 895 * Use this for decisions involving congestion control, use just 896 * tp->packets_out to determine if the send queue is empty or not. 897 * 898 * Read this equation as: 899 * 900 * "Packets sent once on transmission queue" MINUS 901 * "Packets left network, but not honestly ACKed yet" PLUS 902 * "Packets fast retransmitted" 903 */ 904 static inline unsigned int tcp_packets_in_flight(const struct tcp_sock *tp) 905 { 906 return tp->packets_out - tcp_left_out(tp) + tp->retrans_out; 907 } 908 909 #define TCP_INFINITE_SSTHRESH 0x7fffffff 910 911 static inline bool tcp_in_initial_slowstart(const struct tcp_sock *tp) 912 { 913 return tp->snd_ssthresh >= TCP_INFINITE_SSTHRESH; 914 } 915 916 static inline bool tcp_in_cwnd_reduction(const struct sock *sk) 917 { 918 return (TCPF_CA_CWR | TCPF_CA_Recovery) & 919 (1 << inet_csk(sk)->icsk_ca_state); 920 } 921 922 /* If cwnd > ssthresh, we may raise ssthresh to be half-way to cwnd. 923 * The exception is cwnd reduction phase, when cwnd is decreasing towards 924 * ssthresh. 925 */ 926 static inline __u32 tcp_current_ssthresh(const struct sock *sk) 927 { 928 const struct tcp_sock *tp = tcp_sk(sk); 929 930 if (tcp_in_cwnd_reduction(sk)) 931 return tp->snd_ssthresh; 932 else 933 return max(tp->snd_ssthresh, 934 ((tp->snd_cwnd >> 1) + 935 (tp->snd_cwnd >> 2))); 936 } 937 938 /* Use define here intentionally to get WARN_ON location shown at the caller */ 939 #define tcp_verify_left_out(tp) WARN_ON(tcp_left_out(tp) > tp->packets_out) 940 941 extern void tcp_enter_cwr(struct sock *sk, const int set_ssthresh); 942 extern __u32 tcp_init_cwnd(const struct tcp_sock *tp, const struct dst_entry *dst); 943 944 /* The maximum number of MSS of available cwnd for which TSO defers 945 * sending if not using sysctl_tcp_tso_win_divisor. 946 */ 947 static inline __u32 tcp_max_tso_deferred_mss(const struct tcp_sock *tp) 948 { 949 return 3; 950 } 951 952 /* Slow start with delack produces 3 packets of burst, so that 953 * it is safe "de facto". This will be the default - same as 954 * the default reordering threshold - but if reordering increases, 955 * we must be able to allow cwnd to burst at least this much in order 956 * to not pull it back when holes are filled. 957 */ 958 static __inline__ __u32 tcp_max_burst(const struct tcp_sock *tp) 959 { 960 return tp->reordering; 961 } 962 963 /* Returns end sequence number of the receiver's advertised window */ 964 static inline u32 tcp_wnd_end(const struct tcp_sock *tp) 965 { 966 return tp->snd_una + tp->snd_wnd; 967 } 968 extern bool tcp_is_cwnd_limited(const struct sock *sk, u32 in_flight); 969 970 static inline void tcp_minshall_update(struct tcp_sock *tp, unsigned int mss, 971 const struct sk_buff *skb) 972 { 973 if (skb->len < mss) 974 tp->snd_sml = TCP_SKB_CB(skb)->end_seq; 975 } 976 977 static inline void tcp_check_probe_timer(struct sock *sk) 978 { 979 const struct tcp_sock *tp = tcp_sk(sk); 980 const struct inet_connection_sock *icsk = inet_csk(sk); 981 982 if (!tp->packets_out && !icsk->icsk_pending) 983 inet_csk_reset_xmit_timer(sk, ICSK_TIME_PROBE0, 984 icsk->icsk_rto, TCP_RTO_MAX); 985 } 986 987 static inline void tcp_init_wl(struct tcp_sock *tp, u32 seq) 988 { 989 tp->snd_wl1 = seq; 990 } 991 992 static inline void tcp_update_wl(struct tcp_sock *tp, u32 seq) 993 { 994 tp->snd_wl1 = seq; 995 } 996 997 /* 998 * Calculate(/check) TCP checksum 999 */ 1000 static inline __sum16 tcp_v4_check(int len, __be32 saddr, 1001 __be32 daddr, __wsum base) 1002 { 1003 return csum_tcpudp_magic(saddr,daddr,len,IPPROTO_TCP,base); 1004 } 1005 1006 static inline __sum16 __tcp_checksum_complete(struct sk_buff *skb) 1007 { 1008 return __skb_checksum_complete(skb); 1009 } 1010 1011 static inline bool tcp_checksum_complete(struct sk_buff *skb) 1012 { 1013 return !skb_csum_unnecessary(skb) && 1014 __tcp_checksum_complete(skb); 1015 } 1016 1017 /* Prequeue for VJ style copy to user, combined with checksumming. */ 1018 1019 static inline void tcp_prequeue_init(struct tcp_sock *tp) 1020 { 1021 tp->ucopy.task = NULL; 1022 tp->ucopy.len = 0; 1023 tp->ucopy.memory = 0; 1024 skb_queue_head_init(&tp->ucopy.prequeue); 1025 #ifdef CONFIG_NET_DMA 1026 tp->ucopy.dma_chan = NULL; 1027 tp->ucopy.wakeup = 0; 1028 tp->ucopy.pinned_list = NULL; 1029 tp->ucopy.dma_cookie = 0; 1030 #endif 1031 } 1032 1033 /* Packet is added to VJ-style prequeue for processing in process 1034 * context, if a reader task is waiting. Apparently, this exciting 1035 * idea (VJ's mail "Re: query about TCP header on tcp-ip" of 07 Sep 93) 1036 * failed somewhere. Latency? Burstiness? Well, at least now we will 1037 * see, why it failed. 8)8) --ANK 1038 * 1039 * NOTE: is this not too big to inline? 1040 */ 1041 static inline bool tcp_prequeue(struct sock *sk, struct sk_buff *skb) 1042 { 1043 struct tcp_sock *tp = tcp_sk(sk); 1044 1045 if (sysctl_tcp_low_latency || !tp->ucopy.task) 1046 return false; 1047 1048 if (skb->len <= tcp_hdrlen(skb) && 1049 skb_queue_len(&tp->ucopy.prequeue) == 0) 1050 return false; 1051 1052 __skb_queue_tail(&tp->ucopy.prequeue, skb); 1053 tp->ucopy.memory += skb->truesize; 1054 if (tp->ucopy.memory > sk->sk_rcvbuf) { 1055 struct sk_buff *skb1; 1056 1057 BUG_ON(sock_owned_by_user(sk)); 1058 1059 while ((skb1 = __skb_dequeue(&tp->ucopy.prequeue)) != NULL) { 1060 sk_backlog_rcv(sk, skb1); 1061 NET_INC_STATS_BH(sock_net(sk), 1062 LINUX_MIB_TCPPREQUEUEDROPPED); 1063 } 1064 1065 tp->ucopy.memory = 0; 1066 } else if (skb_queue_len(&tp->ucopy.prequeue) == 1) { 1067 wake_up_interruptible_sync_poll(sk_sleep(sk), 1068 POLLIN | POLLRDNORM | POLLRDBAND); 1069 if (!inet_csk_ack_scheduled(sk)) 1070 inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK, 1071 (3 * tcp_rto_min(sk)) / 4, 1072 TCP_RTO_MAX); 1073 } 1074 return true; 1075 } 1076 1077 1078 #undef STATE_TRACE 1079 1080 #ifdef STATE_TRACE 1081 static const char *statename[]={ 1082 "Unused","Established","Syn Sent","Syn Recv", 1083 "Fin Wait 1","Fin Wait 2","Time Wait", "Close", 1084 "Close Wait","Last ACK","Listen","Closing" 1085 }; 1086 #endif 1087 extern void tcp_set_state(struct sock *sk, int state); 1088 1089 extern void tcp_done(struct sock *sk); 1090 1091 static inline void tcp_sack_reset(struct tcp_options_received *rx_opt) 1092 { 1093 rx_opt->dsack = 0; 1094 rx_opt->num_sacks = 0; 1095 } 1096 1097 /* Determine a window scaling and initial window to offer. */ 1098 extern void tcp_select_initial_window(int __space, __u32 mss, 1099 __u32 *rcv_wnd, __u32 *window_clamp, 1100 int wscale_ok, __u8 *rcv_wscale, 1101 __u32 init_rcv_wnd); 1102 1103 static inline int tcp_win_from_space(int space) 1104 { 1105 return sysctl_tcp_adv_win_scale<=0 ? 1106 (space>>(-sysctl_tcp_adv_win_scale)) : 1107 space - (space>>sysctl_tcp_adv_win_scale); 1108 } 1109 1110 /* Note: caller must be prepared to deal with negative returns */ 1111 static inline int tcp_space(const struct sock *sk) 1112 { 1113 return tcp_win_from_space(sk->sk_rcvbuf - 1114 atomic_read(&sk->sk_rmem_alloc)); 1115 } 1116 1117 static inline int tcp_full_space(const struct sock *sk) 1118 { 1119 return tcp_win_from_space(sk->sk_rcvbuf); 1120 } 1121 1122 static inline void tcp_openreq_init(struct request_sock *req, 1123 struct tcp_options_received *rx_opt, 1124 struct sk_buff *skb) 1125 { 1126 struct inet_request_sock *ireq = inet_rsk(req); 1127 1128 req->rcv_wnd = 0; /* So that tcp_send_synack() knows! */ 1129 req->cookie_ts = 0; 1130 tcp_rsk(req)->rcv_isn = TCP_SKB_CB(skb)->seq; 1131 tcp_rsk(req)->rcv_nxt = TCP_SKB_CB(skb)->seq + 1; 1132 tcp_rsk(req)->snt_synack = 0; 1133 req->mss = rx_opt->mss_clamp; 1134 req->ts_recent = rx_opt->saw_tstamp ? rx_opt->rcv_tsval : 0; 1135 ireq->tstamp_ok = rx_opt->tstamp_ok; 1136 ireq->sack_ok = rx_opt->sack_ok; 1137 ireq->snd_wscale = rx_opt->snd_wscale; 1138 ireq->wscale_ok = rx_opt->wscale_ok; 1139 ireq->acked = 0; 1140 ireq->ecn_ok = 0; 1141 ireq->rmt_port = tcp_hdr(skb)->source; 1142 ireq->loc_port = tcp_hdr(skb)->dest; 1143 } 1144 1145 /* Compute time elapsed between SYNACK and the ACK completing 3WHS */ 1146 static inline void tcp_synack_rtt_meas(struct sock *sk, 1147 struct request_sock *req) 1148 { 1149 if (tcp_rsk(req)->snt_synack) 1150 tcp_valid_rtt_meas(sk, 1151 tcp_time_stamp - tcp_rsk(req)->snt_synack); 1152 } 1153 1154 extern void tcp_enter_memory_pressure(struct sock *sk); 1155 1156 static inline int keepalive_intvl_when(const struct tcp_sock *tp) 1157 { 1158 return tp->keepalive_intvl ? : sysctl_tcp_keepalive_intvl; 1159 } 1160 1161 static inline int keepalive_time_when(const struct tcp_sock *tp) 1162 { 1163 return tp->keepalive_time ? : sysctl_tcp_keepalive_time; 1164 } 1165 1166 static inline int keepalive_probes(const struct tcp_sock *tp) 1167 { 1168 return tp->keepalive_probes ? : sysctl_tcp_keepalive_probes; 1169 } 1170 1171 static inline u32 keepalive_time_elapsed(const struct tcp_sock *tp) 1172 { 1173 const struct inet_connection_sock *icsk = &tp->inet_conn; 1174 1175 return min_t(u32, tcp_time_stamp - icsk->icsk_ack.lrcvtime, 1176 tcp_time_stamp - tp->rcv_tstamp); 1177 } 1178 1179 static inline int tcp_fin_time(const struct sock *sk) 1180 { 1181 int fin_timeout = tcp_sk(sk)->linger2 ? : sysctl_tcp_fin_timeout; 1182 const int rto = inet_csk(sk)->icsk_rto; 1183 1184 if (fin_timeout < (rto << 2) - (rto >> 1)) 1185 fin_timeout = (rto << 2) - (rto >> 1); 1186 1187 return fin_timeout; 1188 } 1189 1190 static inline bool tcp_paws_check(const struct tcp_options_received *rx_opt, 1191 int paws_win) 1192 { 1193 if ((s32)(rx_opt->ts_recent - rx_opt->rcv_tsval) <= paws_win) 1194 return true; 1195 if (unlikely(get_seconds() >= rx_opt->ts_recent_stamp + TCP_PAWS_24DAYS)) 1196 return true; 1197 /* 1198 * Some OSes send SYN and SYNACK messages with tsval=0 tsecr=0, 1199 * then following tcp messages have valid values. Ignore 0 value, 1200 * or else 'negative' tsval might forbid us to accept their packets. 1201 */ 1202 if (!rx_opt->ts_recent) 1203 return true; 1204 return false; 1205 } 1206 1207 static inline bool tcp_paws_reject(const struct tcp_options_received *rx_opt, 1208 int rst) 1209 { 1210 if (tcp_paws_check(rx_opt, 0)) 1211 return false; 1212 1213 /* RST segments are not recommended to carry timestamp, 1214 and, if they do, it is recommended to ignore PAWS because 1215 "their cleanup function should take precedence over timestamps." 1216 Certainly, it is mistake. It is necessary to understand the reasons 1217 of this constraint to relax it: if peer reboots, clock may go 1218 out-of-sync and half-open connections will not be reset. 1219 Actually, the problem would be not existing if all 1220 the implementations followed draft about maintaining clock 1221 via reboots. Linux-2.2 DOES NOT! 1222 1223 However, we can relax time bounds for RST segments to MSL. 1224 */ 1225 if (rst && get_seconds() >= rx_opt->ts_recent_stamp + TCP_PAWS_MSL) 1226 return false; 1227 return true; 1228 } 1229 1230 static inline void tcp_mib_init(struct net *net) 1231 { 1232 /* See RFC 2012 */ 1233 TCP_ADD_STATS_USER(net, TCP_MIB_RTOALGORITHM, 1); 1234 TCP_ADD_STATS_USER(net, TCP_MIB_RTOMIN, TCP_RTO_MIN*1000/HZ); 1235 TCP_ADD_STATS_USER(net, TCP_MIB_RTOMAX, TCP_RTO_MAX*1000/HZ); 1236 TCP_ADD_STATS_USER(net, TCP_MIB_MAXCONN, -1); 1237 } 1238 1239 /* from STCP */ 1240 static inline void tcp_clear_retrans_hints_partial(struct tcp_sock *tp) 1241 { 1242 tp->lost_skb_hint = NULL; 1243 tp->scoreboard_skb_hint = NULL; 1244 } 1245 1246 static inline void tcp_clear_all_retrans_hints(struct tcp_sock *tp) 1247 { 1248 tcp_clear_retrans_hints_partial(tp); 1249 tp->retransmit_skb_hint = NULL; 1250 } 1251 1252 /* MD5 Signature */ 1253 struct crypto_hash; 1254 1255 union tcp_md5_addr { 1256 struct in_addr a4; 1257 #if IS_ENABLED(CONFIG_IPV6) 1258 struct in6_addr a6; 1259 #endif 1260 }; 1261 1262 /* - key database */ 1263 struct tcp_md5sig_key { 1264 struct hlist_node node; 1265 u8 keylen; 1266 u8 family; /* AF_INET or AF_INET6 */ 1267 union tcp_md5_addr addr; 1268 u8 key[TCP_MD5SIG_MAXKEYLEN]; 1269 struct rcu_head rcu; 1270 }; 1271 1272 /* - sock block */ 1273 struct tcp_md5sig_info { 1274 struct hlist_head head; 1275 struct rcu_head rcu; 1276 }; 1277 1278 /* - pseudo header */ 1279 struct tcp4_pseudohdr { 1280 __be32 saddr; 1281 __be32 daddr; 1282 __u8 pad; 1283 __u8 protocol; 1284 __be16 len; 1285 }; 1286 1287 struct tcp6_pseudohdr { 1288 struct in6_addr saddr; 1289 struct in6_addr daddr; 1290 __be32 len; 1291 __be32 protocol; /* including padding */ 1292 }; 1293 1294 union tcp_md5sum_block { 1295 struct tcp4_pseudohdr ip4; 1296 #if IS_ENABLED(CONFIG_IPV6) 1297 struct tcp6_pseudohdr ip6; 1298 #endif 1299 }; 1300 1301 /* - pool: digest algorithm, hash description and scratch buffer */ 1302 struct tcp_md5sig_pool { 1303 struct hash_desc md5_desc; 1304 union tcp_md5sum_block md5_blk; 1305 }; 1306 1307 /* - functions */ 1308 extern int tcp_v4_md5_hash_skb(char *md5_hash, struct tcp_md5sig_key *key, 1309 const struct sock *sk, 1310 const struct request_sock *req, 1311 const struct sk_buff *skb); 1312 extern int tcp_md5_do_add(struct sock *sk, const union tcp_md5_addr *addr, 1313 int family, const u8 *newkey, 1314 u8 newkeylen, gfp_t gfp); 1315 extern int tcp_md5_do_del(struct sock *sk, const union tcp_md5_addr *addr, 1316 int family); 1317 extern struct tcp_md5sig_key *tcp_v4_md5_lookup(struct sock *sk, 1318 struct sock *addr_sk); 1319 1320 #ifdef CONFIG_TCP_MD5SIG 1321 extern struct tcp_md5sig_key *tcp_md5_do_lookup(struct sock *sk, 1322 const union tcp_md5_addr *addr, int family); 1323 #define tcp_twsk_md5_key(twsk) ((twsk)->tw_md5_key) 1324 #else 1325 static inline struct tcp_md5sig_key *tcp_md5_do_lookup(struct sock *sk, 1326 const union tcp_md5_addr *addr, 1327 int family) 1328 { 1329 return NULL; 1330 } 1331 #define tcp_twsk_md5_key(twsk) NULL 1332 #endif 1333 1334 extern struct tcp_md5sig_pool __percpu *tcp_alloc_md5sig_pool(struct sock *); 1335 extern void tcp_free_md5sig_pool(void); 1336 1337 extern struct tcp_md5sig_pool *tcp_get_md5sig_pool(void); 1338 extern void tcp_put_md5sig_pool(void); 1339 1340 extern int tcp_md5_hash_header(struct tcp_md5sig_pool *, const struct tcphdr *); 1341 extern int tcp_md5_hash_skb_data(struct tcp_md5sig_pool *, const struct sk_buff *, 1342 unsigned int header_len); 1343 extern int tcp_md5_hash_key(struct tcp_md5sig_pool *hp, 1344 const struct tcp_md5sig_key *key); 1345 1346 /* From tcp_fastopen.c */ 1347 extern void tcp_fastopen_cache_get(struct sock *sk, u16 *mss, 1348 struct tcp_fastopen_cookie *cookie, 1349 int *syn_loss, unsigned long *last_syn_loss); 1350 extern void tcp_fastopen_cache_set(struct sock *sk, u16 mss, 1351 struct tcp_fastopen_cookie *cookie, 1352 bool syn_lost); 1353 struct tcp_fastopen_request { 1354 /* Fast Open cookie. Size 0 means a cookie request */ 1355 struct tcp_fastopen_cookie cookie; 1356 struct msghdr *data; /* data in MSG_FASTOPEN */ 1357 u16 copied; /* queued in tcp_connect() */ 1358 }; 1359 void tcp_free_fastopen_req(struct tcp_sock *tp); 1360 1361 extern struct tcp_fastopen_context __rcu *tcp_fastopen_ctx; 1362 int tcp_fastopen_reset_cipher(void *key, unsigned int len); 1363 void tcp_fastopen_cookie_gen(__be32 addr, struct tcp_fastopen_cookie *foc); 1364 1365 #define TCP_FASTOPEN_KEY_LENGTH 16 1366 1367 /* Fastopen key context */ 1368 struct tcp_fastopen_context { 1369 struct crypto_cipher __rcu *tfm; 1370 __u8 key[TCP_FASTOPEN_KEY_LENGTH]; 1371 struct rcu_head rcu; 1372 }; 1373 1374 /* write queue abstraction */ 1375 static inline void tcp_write_queue_purge(struct sock *sk) 1376 { 1377 struct sk_buff *skb; 1378 1379 while ((skb = __skb_dequeue(&sk->sk_write_queue)) != NULL) 1380 sk_wmem_free_skb(sk, skb); 1381 sk_mem_reclaim(sk); 1382 tcp_clear_all_retrans_hints(tcp_sk(sk)); 1383 } 1384 1385 static inline struct sk_buff *tcp_write_queue_head(const struct sock *sk) 1386 { 1387 return skb_peek(&sk->sk_write_queue); 1388 } 1389 1390 static inline struct sk_buff *tcp_write_queue_tail(const struct sock *sk) 1391 { 1392 return skb_peek_tail(&sk->sk_write_queue); 1393 } 1394 1395 static inline struct sk_buff *tcp_write_queue_next(const struct sock *sk, 1396 const struct sk_buff *skb) 1397 { 1398 return skb_queue_next(&sk->sk_write_queue, skb); 1399 } 1400 1401 static inline struct sk_buff *tcp_write_queue_prev(const struct sock *sk, 1402 const struct sk_buff *skb) 1403 { 1404 return skb_queue_prev(&sk->sk_write_queue, skb); 1405 } 1406 1407 #define tcp_for_write_queue(skb, sk) \ 1408 skb_queue_walk(&(sk)->sk_write_queue, skb) 1409 1410 #define tcp_for_write_queue_from(skb, sk) \ 1411 skb_queue_walk_from(&(sk)->sk_write_queue, skb) 1412 1413 #define tcp_for_write_queue_from_safe(skb, tmp, sk) \ 1414 skb_queue_walk_from_safe(&(sk)->sk_write_queue, skb, tmp) 1415 1416 static inline struct sk_buff *tcp_send_head(const struct sock *sk) 1417 { 1418 return sk->sk_send_head; 1419 } 1420 1421 static inline bool tcp_skb_is_last(const struct sock *sk, 1422 const struct sk_buff *skb) 1423 { 1424 return skb_queue_is_last(&sk->sk_write_queue, skb); 1425 } 1426 1427 static inline void tcp_advance_send_head(struct sock *sk, const struct sk_buff *skb) 1428 { 1429 if (tcp_skb_is_last(sk, skb)) 1430 sk->sk_send_head = NULL; 1431 else 1432 sk->sk_send_head = tcp_write_queue_next(sk, skb); 1433 } 1434 1435 static inline void tcp_check_send_head(struct sock *sk, struct sk_buff *skb_unlinked) 1436 { 1437 if (sk->sk_send_head == skb_unlinked) 1438 sk->sk_send_head = NULL; 1439 } 1440 1441 static inline void tcp_init_send_head(struct sock *sk) 1442 { 1443 sk->sk_send_head = NULL; 1444 } 1445 1446 static inline void __tcp_add_write_queue_tail(struct sock *sk, struct sk_buff *skb) 1447 { 1448 __skb_queue_tail(&sk->sk_write_queue, skb); 1449 } 1450 1451 static inline void tcp_add_write_queue_tail(struct sock *sk, struct sk_buff *skb) 1452 { 1453 __tcp_add_write_queue_tail(sk, skb); 1454 1455 /* Queue it, remembering where we must start sending. */ 1456 if (sk->sk_send_head == NULL) { 1457 sk->sk_send_head = skb; 1458 1459 if (tcp_sk(sk)->highest_sack == NULL) 1460 tcp_sk(sk)->highest_sack = skb; 1461 } 1462 } 1463 1464 static inline void __tcp_add_write_queue_head(struct sock *sk, struct sk_buff *skb) 1465 { 1466 __skb_queue_head(&sk->sk_write_queue, skb); 1467 } 1468 1469 /* Insert buff after skb on the write queue of sk. */ 1470 static inline void tcp_insert_write_queue_after(struct sk_buff *skb, 1471 struct sk_buff *buff, 1472 struct sock *sk) 1473 { 1474 __skb_queue_after(&sk->sk_write_queue, skb, buff); 1475 } 1476 1477 /* Insert new before skb on the write queue of sk. */ 1478 static inline void tcp_insert_write_queue_before(struct sk_buff *new, 1479 struct sk_buff *skb, 1480 struct sock *sk) 1481 { 1482 __skb_queue_before(&sk->sk_write_queue, skb, new); 1483 1484 if (sk->sk_send_head == skb) 1485 sk->sk_send_head = new; 1486 } 1487 1488 static inline void tcp_unlink_write_queue(struct sk_buff *skb, struct sock *sk) 1489 { 1490 __skb_unlink(skb, &sk->sk_write_queue); 1491 } 1492 1493 static inline bool tcp_write_queue_empty(struct sock *sk) 1494 { 1495 return skb_queue_empty(&sk->sk_write_queue); 1496 } 1497 1498 static inline void tcp_push_pending_frames(struct sock *sk) 1499 { 1500 if (tcp_send_head(sk)) { 1501 struct tcp_sock *tp = tcp_sk(sk); 1502 1503 __tcp_push_pending_frames(sk, tcp_current_mss(sk), tp->nonagle); 1504 } 1505 } 1506 1507 /* Start sequence of the skb just after the highest skb with SACKed 1508 * bit, valid only if sacked_out > 0 or when the caller has ensured 1509 * validity by itself. 1510 */ 1511 static inline u32 tcp_highest_sack_seq(struct tcp_sock *tp) 1512 { 1513 if (!tp->sacked_out) 1514 return tp->snd_una; 1515 1516 if (tp->highest_sack == NULL) 1517 return tp->snd_nxt; 1518 1519 return TCP_SKB_CB(tp->highest_sack)->seq; 1520 } 1521 1522 static inline void tcp_advance_highest_sack(struct sock *sk, struct sk_buff *skb) 1523 { 1524 tcp_sk(sk)->highest_sack = tcp_skb_is_last(sk, skb) ? NULL : 1525 tcp_write_queue_next(sk, skb); 1526 } 1527 1528 static inline struct sk_buff *tcp_highest_sack(struct sock *sk) 1529 { 1530 return tcp_sk(sk)->highest_sack; 1531 } 1532 1533 static inline void tcp_highest_sack_reset(struct sock *sk) 1534 { 1535 tcp_sk(sk)->highest_sack = tcp_write_queue_head(sk); 1536 } 1537 1538 /* Called when old skb is about to be deleted (to be combined with new skb) */ 1539 static inline void tcp_highest_sack_combine(struct sock *sk, 1540 struct sk_buff *old, 1541 struct sk_buff *new) 1542 { 1543 if (tcp_sk(sk)->sacked_out && (old == tcp_sk(sk)->highest_sack)) 1544 tcp_sk(sk)->highest_sack = new; 1545 } 1546 1547 /* Determines whether this is a thin stream (which may suffer from 1548 * increased latency). Used to trigger latency-reducing mechanisms. 1549 */ 1550 static inline bool tcp_stream_is_thin(struct tcp_sock *tp) 1551 { 1552 return tp->packets_out < 4 && !tcp_in_initial_slowstart(tp); 1553 } 1554 1555 /* /proc */ 1556 enum tcp_seq_states { 1557 TCP_SEQ_STATE_LISTENING, 1558 TCP_SEQ_STATE_OPENREQ, 1559 TCP_SEQ_STATE_ESTABLISHED, 1560 TCP_SEQ_STATE_TIME_WAIT, 1561 }; 1562 1563 int tcp_seq_open(struct inode *inode, struct file *file); 1564 1565 struct tcp_seq_afinfo { 1566 char *name; 1567 sa_family_t family; 1568 const struct file_operations *seq_fops; 1569 struct seq_operations seq_ops; 1570 }; 1571 1572 struct tcp_iter_state { 1573 struct seq_net_private p; 1574 sa_family_t family; 1575 enum tcp_seq_states state; 1576 struct sock *syn_wait_sk; 1577 int bucket, offset, sbucket, num; 1578 kuid_t uid; 1579 loff_t last_pos; 1580 }; 1581 1582 extern int tcp_proc_register(struct net *net, struct tcp_seq_afinfo *afinfo); 1583 extern void tcp_proc_unregister(struct net *net, struct tcp_seq_afinfo *afinfo); 1584 1585 extern struct request_sock_ops tcp_request_sock_ops; 1586 extern struct request_sock_ops tcp6_request_sock_ops; 1587 1588 extern void tcp_v4_destroy_sock(struct sock *sk); 1589 1590 extern int tcp_v4_gso_send_check(struct sk_buff *skb); 1591 extern struct sk_buff *tcp_tso_segment(struct sk_buff *skb, 1592 netdev_features_t features); 1593 extern struct sk_buff **tcp_gro_receive(struct sk_buff **head, 1594 struct sk_buff *skb); 1595 extern struct sk_buff **tcp4_gro_receive(struct sk_buff **head, 1596 struct sk_buff *skb); 1597 extern int tcp_gro_complete(struct sk_buff *skb); 1598 extern int tcp4_gro_complete(struct sk_buff *skb); 1599 1600 #ifdef CONFIG_PROC_FS 1601 extern int tcp4_proc_init(void); 1602 extern void tcp4_proc_exit(void); 1603 #endif 1604 1605 /* TCP af-specific functions */ 1606 struct tcp_sock_af_ops { 1607 #ifdef CONFIG_TCP_MD5SIG 1608 struct tcp_md5sig_key *(*md5_lookup) (struct sock *sk, 1609 struct sock *addr_sk); 1610 int (*calc_md5_hash) (char *location, 1611 struct tcp_md5sig_key *md5, 1612 const struct sock *sk, 1613 const struct request_sock *req, 1614 const struct sk_buff *skb); 1615 int (*md5_parse) (struct sock *sk, 1616 char __user *optval, 1617 int optlen); 1618 #endif 1619 }; 1620 1621 struct tcp_request_sock_ops { 1622 #ifdef CONFIG_TCP_MD5SIG 1623 struct tcp_md5sig_key *(*md5_lookup) (struct sock *sk, 1624 struct request_sock *req); 1625 int (*calc_md5_hash) (char *location, 1626 struct tcp_md5sig_key *md5, 1627 const struct sock *sk, 1628 const struct request_sock *req, 1629 const struct sk_buff *skb); 1630 #endif 1631 }; 1632 1633 /* Using SHA1 for now, define some constants. 1634 */ 1635 #define COOKIE_DIGEST_WORDS (SHA_DIGEST_WORDS) 1636 #define COOKIE_MESSAGE_WORDS (SHA_MESSAGE_BYTES / 4) 1637 #define COOKIE_WORKSPACE_WORDS (COOKIE_DIGEST_WORDS + COOKIE_MESSAGE_WORDS) 1638 1639 extern int tcp_cookie_generator(u32 *bakery); 1640 1641 /** 1642 * struct tcp_cookie_values - each socket needs extra space for the 1643 * cookies, together with (optional) space for any SYN data. 1644 * 1645 * A tcp_sock contains a pointer to the current value, and this is 1646 * cloned to the tcp_timewait_sock. 1647 * 1648 * @cookie_pair: variable data from the option exchange. 1649 * 1650 * @cookie_desired: user specified tcpct_cookie_desired. Zero 1651 * indicates default (sysctl_tcp_cookie_size). 1652 * After cookie sent, remembers size of cookie. 1653 * Range 0, TCP_COOKIE_MIN to TCP_COOKIE_MAX. 1654 * 1655 * @s_data_desired: user specified tcpct_s_data_desired. When the 1656 * constant payload is specified (@s_data_constant), 1657 * holds its length instead. 1658 * Range 0 to TCP_MSS_DESIRED. 1659 * 1660 * @s_data_payload: constant data that is to be included in the 1661 * payload of SYN or SYNACK segments when the 1662 * cookie option is present. 1663 */ 1664 struct tcp_cookie_values { 1665 struct kref kref; 1666 u8 cookie_pair[TCP_COOKIE_PAIR_SIZE]; 1667 u8 cookie_pair_size; 1668 u8 cookie_desired; 1669 u16 s_data_desired:11, 1670 s_data_constant:1, 1671 s_data_in:1, 1672 s_data_out:1, 1673 s_data_unused:2; 1674 u8 s_data_payload[0]; 1675 }; 1676 1677 static inline void tcp_cookie_values_release(struct kref *kref) 1678 { 1679 kfree(container_of(kref, struct tcp_cookie_values, kref)); 1680 } 1681 1682 /* The length of constant payload data. Note that s_data_desired is 1683 * overloaded, depending on s_data_constant: either the length of constant 1684 * data (returned here) or the limit on variable data. 1685 */ 1686 static inline int tcp_s_data_size(const struct tcp_sock *tp) 1687 { 1688 return (tp->cookie_values != NULL && tp->cookie_values->s_data_constant) 1689 ? tp->cookie_values->s_data_desired 1690 : 0; 1691 } 1692 1693 /** 1694 * struct tcp_extend_values - tcp_ipv?.c to tcp_output.c workspace. 1695 * 1696 * As tcp_request_sock has already been extended in other places, the 1697 * only remaining method is to pass stack values along as function 1698 * parameters. These parameters are not needed after sending SYNACK. 1699 * 1700 * @cookie_bakery: cryptographic secret and message workspace. 1701 * 1702 * @cookie_plus: bytes in authenticator/cookie option, copied from 1703 * struct tcp_options_received (above). 1704 */ 1705 struct tcp_extend_values { 1706 struct request_values rv; 1707 u32 cookie_bakery[COOKIE_WORKSPACE_WORDS]; 1708 u8 cookie_plus:6, 1709 cookie_out_never:1, 1710 cookie_in_always:1; 1711 }; 1712 1713 static inline struct tcp_extend_values *tcp_xv(struct request_values *rvp) 1714 { 1715 return (struct tcp_extend_values *)rvp; 1716 } 1717 1718 extern void tcp_v4_init(void); 1719 extern void tcp_init(void); 1720 1721 #endif /* _TCP_H */ 1722