1 /* SPDX-License-Identifier: GPL-2.0-or-later */
2 /*
3 * INET An implementation of the TCP/IP protocol suite for the LINUX
4 * operating system. INET is implemented using the BSD Socket
5 * interface as the means of communication with the user level.
6 *
7 * Definitions for the TCP protocol.
8 *
9 * Version: @(#)tcp.h 1.0.2 04/28/93
10 *
11 * Author: Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
12 */
13 #ifndef _LINUX_TCP_H
14 #define _LINUX_TCP_H
15
16
17 #include <linux/skbuff.h>
18 #include <linux/win_minmax.h>
19 #include <net/sock.h>
20 #include <net/inet_connection_sock.h>
21 #include <net/inet_timewait_sock.h>
22 #include <uapi/linux/tcp.h>
23
tcp_hdr(const struct sk_buff * skb)24 static inline struct tcphdr *tcp_hdr(const struct sk_buff *skb)
25 {
26 return (struct tcphdr *)skb_transport_header(skb);
27 }
28
__tcp_hdrlen(const struct tcphdr * th)29 static inline unsigned int __tcp_hdrlen(const struct tcphdr *th)
30 {
31 return th->doff * 4;
32 }
33
tcp_hdrlen(const struct sk_buff * skb)34 static inline unsigned int tcp_hdrlen(const struct sk_buff *skb)
35 {
36 return __tcp_hdrlen(tcp_hdr(skb));
37 }
38
inner_tcp_hdr(const struct sk_buff * skb)39 static inline struct tcphdr *inner_tcp_hdr(const struct sk_buff *skb)
40 {
41 return (struct tcphdr *)skb_inner_transport_header(skb);
42 }
43
inner_tcp_hdrlen(const struct sk_buff * skb)44 static inline unsigned int inner_tcp_hdrlen(const struct sk_buff *skb)
45 {
46 return inner_tcp_hdr(skb)->doff * 4;
47 }
48
49 /**
50 * skb_tcp_all_headers - Returns size of all headers for a TCP packet
51 * @skb: buffer
52 *
53 * Used in TX path, for a packet known to be a TCP one.
54 *
55 * if (skb_is_gso(skb)) {
56 * int hlen = skb_tcp_all_headers(skb);
57 * ...
58 */
skb_tcp_all_headers(const struct sk_buff * skb)59 static inline int skb_tcp_all_headers(const struct sk_buff *skb)
60 {
61 return skb_transport_offset(skb) + tcp_hdrlen(skb);
62 }
63
64 /**
65 * skb_inner_tcp_all_headers - Returns size of all headers for an encap TCP packet
66 * @skb: buffer
67 *
68 * Used in TX path, for a packet known to be a TCP one.
69 *
70 * if (skb_is_gso(skb) && skb->encapsulation) {
71 * int hlen = skb_inner_tcp_all_headers(skb);
72 * ...
73 */
skb_inner_tcp_all_headers(const struct sk_buff * skb)74 static inline int skb_inner_tcp_all_headers(const struct sk_buff *skb)
75 {
76 return skb_inner_transport_offset(skb) + inner_tcp_hdrlen(skb);
77 }
78
tcp_optlen(const struct sk_buff * skb)79 static inline unsigned int tcp_optlen(const struct sk_buff *skb)
80 {
81 return (tcp_hdr(skb)->doff - 5) * 4;
82 }
83
84 /* TCP Fast Open */
85 #define TCP_FASTOPEN_COOKIE_MIN 4 /* Min Fast Open Cookie size in bytes */
86 #define TCP_FASTOPEN_COOKIE_MAX 16 /* Max Fast Open Cookie size in bytes */
87 #define TCP_FASTOPEN_COOKIE_SIZE 8 /* the size employed by this impl. */
88
89 /* TCP Fast Open Cookie as stored in memory */
90 struct tcp_fastopen_cookie {
91 __le64 val[DIV_ROUND_UP(TCP_FASTOPEN_COOKIE_MAX, sizeof(u64))];
92 s8 len;
93 bool exp; /* In RFC6994 experimental option format */
94 };
95
96 /* This defines a selective acknowledgement block. */
97 struct tcp_sack_block_wire {
98 __be32 start_seq;
99 __be32 end_seq;
100 };
101
102 struct tcp_sack_block {
103 u32 start_seq;
104 u32 end_seq;
105 };
106
107 /*These are used to set the sack_ok field in struct tcp_options_received */
108 #define TCP_SACK_SEEN (1 << 0) /*1 = peer is SACK capable, */
109 #define TCP_DSACK_SEEN (1 << 2) /*1 = DSACK was received from peer*/
110
111 struct tcp_options_received {
112 /* PAWS/RTTM data */
113 int ts_recent_stamp;/* Time we stored ts_recent (for aging) */
114 u32 ts_recent; /* Time stamp to echo next */
115 u32 rcv_tsval; /* Time stamp value */
116 u32 rcv_tsecr; /* Time stamp echo reply */
117 u16 saw_tstamp : 1, /* Saw TIMESTAMP on last packet */
118 tstamp_ok : 1, /* TIMESTAMP seen on SYN packet */
119 dsack : 1, /* D-SACK is scheduled */
120 wscale_ok : 1, /* Wscale seen on SYN packet */
121 sack_ok : 3, /* SACK seen on SYN packet */
122 smc_ok : 1, /* SMC seen on SYN packet */
123 snd_wscale : 4, /* Window scaling received from sender */
124 rcv_wscale : 4; /* Window scaling to send to receiver */
125 u8 saw_unknown:1, /* Received unknown option */
126 unused:7;
127 u8 num_sacks; /* Number of SACK blocks */
128 u16 user_mss; /* mss requested by user in ioctl */
129 u16 mss_clamp; /* Maximal mss, negotiated at connection setup */
130 };
131
tcp_clear_options(struct tcp_options_received * rx_opt)132 static inline void tcp_clear_options(struct tcp_options_received *rx_opt)
133 {
134 rx_opt->tstamp_ok = rx_opt->sack_ok = 0;
135 rx_opt->wscale_ok = rx_opt->snd_wscale = 0;
136 #if IS_ENABLED(CONFIG_SMC)
137 rx_opt->smc_ok = 0;
138 #endif
139 }
140
141 /* This is the max number of SACKS that we'll generate and process. It's safe
142 * to increase this, although since:
143 * size = TCPOLEN_SACK_BASE_ALIGNED (4) + n * TCPOLEN_SACK_PERBLOCK (8)
144 * only four options will fit in a standard TCP header */
145 #define TCP_NUM_SACKS 4
146
147 struct tcp_request_sock_ops;
148
149 struct tcp_request_sock {
150 struct inet_request_sock req;
151 const struct tcp_request_sock_ops *af_specific;
152 u64 snt_synack; /* first SYNACK sent time */
153 bool tfo_listener;
154 bool is_mptcp;
155 #if IS_ENABLED(CONFIG_MPTCP)
156 bool drop_req;
157 #endif
158 u32 txhash;
159 u32 rcv_isn;
160 u32 snt_isn;
161 u32 ts_off;
162 u32 last_oow_ack_time; /* last SYNACK */
163 u32 rcv_nxt; /* the ack # by SYNACK. For
164 * FastOpen it's the seq#
165 * after data-in-SYN.
166 */
167 u8 syn_tos;
168 };
169
tcp_rsk(const struct request_sock * req)170 static inline struct tcp_request_sock *tcp_rsk(const struct request_sock *req)
171 {
172 return (struct tcp_request_sock *)req;
173 }
174
175 #define TCP_RMEM_TO_WIN_SCALE 8
176
177 struct tcp_sock {
178 /* inet_connection_sock has to be the first member of tcp_sock */
179 struct inet_connection_sock inet_conn;
180 u16 tcp_header_len; /* Bytes of tcp header to send */
181 u16 gso_segs; /* Max number of segs per GSO packet */
182
183 /*
184 * Header prediction flags
185 * 0x5?10 << 16 + snd_wnd in net byte order
186 */
187 __be32 pred_flags;
188
189 /*
190 * RFC793 variables by their proper names. This means you can
191 * read the code and the spec side by side (and laugh ...)
192 * See RFC793 and RFC1122. The RFC writes these in capitals.
193 */
194 u64 bytes_received; /* RFC4898 tcpEStatsAppHCThruOctetsReceived
195 * sum(delta(rcv_nxt)), or how many bytes
196 * were acked.
197 */
198 u32 segs_in; /* RFC4898 tcpEStatsPerfSegsIn
199 * total number of segments in.
200 */
201 u32 data_segs_in; /* RFC4898 tcpEStatsPerfDataSegsIn
202 * total number of data segments in.
203 */
204 u32 rcv_nxt; /* What we want to receive next */
205 u32 copied_seq; /* Head of yet unread data */
206 u32 rcv_wup; /* rcv_nxt on last window update sent */
207 u32 snd_nxt; /* Next sequence we send */
208 u32 segs_out; /* RFC4898 tcpEStatsPerfSegsOut
209 * The total number of segments sent.
210 */
211 u32 data_segs_out; /* RFC4898 tcpEStatsPerfDataSegsOut
212 * total number of data segments sent.
213 */
214 u64 bytes_sent; /* RFC4898 tcpEStatsPerfHCDataOctetsOut
215 * total number of data bytes sent.
216 */
217 u64 bytes_acked; /* RFC4898 tcpEStatsAppHCThruOctetsAcked
218 * sum(delta(snd_una)), or how many bytes
219 * were acked.
220 */
221 u32 dsack_dups; /* RFC4898 tcpEStatsStackDSACKDups
222 * total number of DSACK blocks received
223 */
224 u32 snd_una; /* First byte we want an ack for */
225 u32 snd_sml; /* Last byte of the most recently transmitted small packet */
226 u32 rcv_tstamp; /* timestamp of last received ACK (for keepalives) */
227 u32 lsndtime; /* timestamp of last sent data packet (for restart window) */
228 u32 last_oow_ack_time; /* timestamp of last out-of-window ACK */
229 u32 compressed_ack_rcv_nxt;
230
231 u32 tsoffset; /* timestamp offset */
232
233 struct list_head tsq_node; /* anchor in tsq_tasklet.head list */
234 struct list_head tsorted_sent_queue; /* time-sorted sent but un-SACKed skbs */
235
236 u32 snd_wl1; /* Sequence for window update */
237 u32 snd_wnd; /* The window we expect to receive */
238 u32 max_window; /* Maximal window ever seen from peer */
239 u32 mss_cache; /* Cached effective mss, not including SACKS */
240
241 u32 window_clamp; /* Maximal window to advertise */
242 u32 rcv_ssthresh; /* Current window clamp */
243 u8 scaling_ratio; /* see tcp_win_from_space() */
244 /* Information of the most recently (s)acked skb */
245 struct tcp_rack {
246 u64 mstamp; /* (Re)sent time of the skb */
247 u32 rtt_us; /* Associated RTT */
248 u32 end_seq; /* Ending TCP sequence of the skb */
249 u32 last_delivered; /* tp->delivered at last reo_wnd adj */
250 u8 reo_wnd_steps; /* Allowed reordering window */
251 #define TCP_RACK_RECOVERY_THRESH 16
252 u8 reo_wnd_persist:5, /* No. of recovery since last adj */
253 dsack_seen:1, /* Whether DSACK seen after last adj */
254 advanced:1; /* mstamp advanced since last lost marking */
255 } rack;
256 u16 advmss; /* Advertised MSS */
257 u8 compressed_ack;
258 u8 dup_ack_counter:2,
259 tlp_retrans:1, /* TLP is a retransmission */
260 unused:5;
261 u32 chrono_start; /* Start time in jiffies of a TCP chrono */
262 u32 chrono_stat[3]; /* Time in jiffies for chrono_stat stats */
263 u8 chrono_type:2, /* current chronograph type */
264 rate_app_limited:1, /* rate_{delivered,interval_us} limited? */
265 fastopen_connect:1, /* FASTOPEN_CONNECT sockopt */
266 fastopen_no_cookie:1, /* Allow send/recv SYN+data without a cookie */
267 is_sack_reneg:1, /* in recovery from loss with SACK reneg? */
268 fastopen_client_fail:2; /* reason why fastopen failed */
269 u8 nonagle : 4,/* Disable Nagle algorithm? */
270 thin_lto : 1,/* Use linear timeouts for thin streams */
271 recvmsg_inq : 1,/* Indicate # of bytes in queue upon recvmsg */
272 repair : 1,
273 frto : 1;/* F-RTO (RFC5682) activated in CA_Loss */
274 u8 repair_queue;
275 u8 save_syn:2, /* Save headers of SYN packet */
276 syn_data:1, /* SYN includes data */
277 syn_fastopen:1, /* SYN includes Fast Open option */
278 syn_fastopen_exp:1,/* SYN includes Fast Open exp. option */
279 syn_fastopen_ch:1, /* Active TFO re-enabling probe */
280 syn_data_acked:1,/* data in SYN is acked by SYN-ACK */
281 is_cwnd_limited:1;/* forward progress limited by snd_cwnd? */
282 u32 tlp_high_seq; /* snd_nxt at the time of TLP */
283
284 u32 tcp_tx_delay; /* delay (in usec) added to TX packets */
285 u64 tcp_wstamp_ns; /* departure time for next sent data packet */
286 u64 tcp_clock_cache; /* cache last tcp_clock_ns() (see tcp_mstamp_refresh()) */
287
288 /* RTT measurement */
289 u64 tcp_mstamp; /* most recent packet received/sent */
290 u32 srtt_us; /* smoothed round trip time << 3 in usecs */
291 u32 mdev_us; /* medium deviation */
292 u32 mdev_max_us; /* maximal mdev for the last rtt period */
293 u32 rttvar_us; /* smoothed mdev_max */
294 u32 rtt_seq; /* sequence number to update rttvar */
295 struct minmax rtt_min;
296
297 u32 packets_out; /* Packets which are "in flight" */
298 u32 retrans_out; /* Retransmitted packets out */
299 u32 max_packets_out; /* max packets_out in last window */
300 u32 cwnd_usage_seq; /* right edge of cwnd usage tracking flight */
301
302 u16 urg_data; /* Saved octet of OOB data and control flags */
303 u8 ecn_flags; /* ECN status bits. */
304 u8 keepalive_probes; /* num of allowed keep alive probes */
305 u32 reordering; /* Packet reordering metric. */
306 u32 reord_seen; /* number of data packet reordering events */
307 u32 snd_up; /* Urgent pointer */
308
309 /*
310 * Options received (usually on last packet, some only on SYN packets).
311 */
312 struct tcp_options_received rx_opt;
313
314 /*
315 * Slow start and congestion control (see also Nagle, and Karn & Partridge)
316 */
317 u32 snd_ssthresh; /* Slow start size threshold */
318 u32 snd_cwnd; /* Sending congestion window */
319 u32 snd_cwnd_cnt; /* Linear increase counter */
320 u32 snd_cwnd_clamp; /* Do not allow snd_cwnd to grow above this */
321 u32 snd_cwnd_used;
322 u32 snd_cwnd_stamp;
323 u32 prior_cwnd; /* cwnd right before starting loss recovery */
324 u32 prr_delivered; /* Number of newly delivered packets to
325 * receiver in Recovery. */
326 u32 prr_out; /* Total number of pkts sent during Recovery. */
327 u32 delivered; /* Total data packets delivered incl. rexmits */
328 u32 delivered_ce; /* Like the above but only ECE marked packets */
329 u32 lost; /* Total data packets lost incl. rexmits */
330 u32 app_limited; /* limited until "delivered" reaches this val */
331 u64 first_tx_mstamp; /* start of window send phase */
332 u64 delivered_mstamp; /* time we reached "delivered" */
333 u32 rate_delivered; /* saved rate sample: packets delivered */
334 u32 rate_interval_us; /* saved rate sample: time elapsed */
335
336 u32 rcv_wnd; /* Current receiver window */
337 u32 write_seq; /* Tail(+1) of data held in tcp send buffer */
338 u32 notsent_lowat; /* TCP_NOTSENT_LOWAT */
339 u32 pushed_seq; /* Last pushed seq, required to talk to windows */
340 u32 lost_out; /* Lost packets */
341 u32 sacked_out; /* SACK'd packets */
342
343 struct hrtimer pacing_timer;
344 struct hrtimer compressed_ack_timer;
345
346 /* from STCP, retrans queue hinting */
347 struct sk_buff* lost_skb_hint;
348 struct sk_buff *retransmit_skb_hint;
349
350 /* OOO segments go in this rbtree. Socket lock must be held. */
351 struct rb_root out_of_order_queue;
352 struct sk_buff *ooo_last_skb; /* cache rb_last(out_of_order_queue) */
353
354 /* SACKs data, these 2 need to be together (see tcp_options_write) */
355 struct tcp_sack_block duplicate_sack[1]; /* D-SACK block */
356 struct tcp_sack_block selective_acks[4]; /* The SACKS themselves*/
357
358 struct tcp_sack_block recv_sack_cache[4];
359
360 struct sk_buff *highest_sack; /* skb just after the highest
361 * skb with SACKed bit set
362 * (validity guaranteed only if
363 * sacked_out > 0)
364 */
365
366 int lost_cnt_hint;
367
368 u32 prior_ssthresh; /* ssthresh saved at recovery start */
369 u32 high_seq; /* snd_nxt at onset of congestion */
370
371 u32 retrans_stamp; /* Timestamp of the last retransmit,
372 * also used in SYN-SENT to remember stamp of
373 * the first SYN. */
374 u32 undo_marker; /* snd_una upon a new recovery episode. */
375 int undo_retrans; /* number of undoable retransmissions. */
376 u64 bytes_retrans; /* RFC4898 tcpEStatsPerfOctetsRetrans
377 * Total data bytes retransmitted
378 */
379 u32 total_retrans; /* Total retransmits for entire connection */
380
381 u32 urg_seq; /* Seq of received urgent pointer */
382 unsigned int keepalive_time; /* time before keep alive takes place */
383 unsigned int keepalive_intvl; /* time interval between keep alive probes */
384
385 int linger2;
386
387
388 /* Sock_ops bpf program related variables */
389 #ifdef CONFIG_BPF
390 u8 bpf_sock_ops_cb_flags; /* Control calling BPF programs
391 * values defined in uapi/linux/tcp.h
392 */
393 u8 bpf_chg_cc_inprogress:1; /* In the middle of
394 * bpf_setsockopt(TCP_CONGESTION),
395 * it is to avoid the bpf_tcp_cc->init()
396 * to recur itself by calling
397 * bpf_setsockopt(TCP_CONGESTION, "itself").
398 */
399 #define BPF_SOCK_OPS_TEST_FLAG(TP, ARG) (TP->bpf_sock_ops_cb_flags & ARG)
400 #else
401 #define BPF_SOCK_OPS_TEST_FLAG(TP, ARG) 0
402 #endif
403
404 u16 timeout_rehash; /* Timeout-triggered rehash attempts */
405
406 u32 rcv_ooopack; /* Received out-of-order packets, for tcpinfo */
407
408 /* Receiver side RTT estimation */
409 u32 rcv_rtt_last_tsecr;
410 struct {
411 u32 rtt_us;
412 u32 seq;
413 u64 time;
414 } rcv_rtt_est;
415
416 /* Receiver queue space */
417 struct {
418 u32 space;
419 u32 seq;
420 u64 time;
421 } rcvq_space;
422
423 /* TCP-specific MTU probe information. */
424 struct {
425 u32 probe_seq_start;
426 u32 probe_seq_end;
427 } mtu_probe;
428 u32 plb_rehash; /* PLB-triggered rehash attempts */
429 u32 mtu_info; /* We received an ICMP_FRAG_NEEDED / ICMPV6_PKT_TOOBIG
430 * while socket was owned by user.
431 */
432 #if IS_ENABLED(CONFIG_MPTCP)
433 bool is_mptcp;
434 #endif
435 #if IS_ENABLED(CONFIG_SMC)
436 bool (*smc_hs_congested)(const struct sock *sk);
437 bool syn_smc; /* SYN includes SMC */
438 #endif
439
440 #ifdef CONFIG_TCP_MD5SIG
441 /* TCP AF-Specific parts; only used by MD5 Signature support so far */
442 const struct tcp_sock_af_ops *af_specific;
443
444 /* TCP MD5 Signature Option information */
445 struct tcp_md5sig_info __rcu *md5sig_info;
446 #endif
447
448 /* TCP fastopen related information */
449 struct tcp_fastopen_request *fastopen_req;
450 /* fastopen_rsk points to request_sock that resulted in this big
451 * socket. Used to retransmit SYNACKs etc.
452 */
453 struct request_sock __rcu *fastopen_rsk;
454 struct saved_syn *saved_syn;
455 };
456
457 enum tsq_enum {
458 TSQ_THROTTLED,
459 TSQ_QUEUED,
460 TCP_TSQ_DEFERRED, /* tcp_tasklet_func() found socket was owned */
461 TCP_WRITE_TIMER_DEFERRED, /* tcp_write_timer() found socket was owned */
462 TCP_DELACK_TIMER_DEFERRED, /* tcp_delack_timer() found socket was owned */
463 TCP_MTU_REDUCED_DEFERRED, /* tcp_v{4|6}_err() could not call
464 * tcp_v{4|6}_mtu_reduced()
465 */
466 };
467
468 enum tsq_flags {
469 TSQF_THROTTLED = (1UL << TSQ_THROTTLED),
470 TSQF_QUEUED = (1UL << TSQ_QUEUED),
471 TCPF_TSQ_DEFERRED = (1UL << TCP_TSQ_DEFERRED),
472 TCPF_WRITE_TIMER_DEFERRED = (1UL << TCP_WRITE_TIMER_DEFERRED),
473 TCPF_DELACK_TIMER_DEFERRED = (1UL << TCP_DELACK_TIMER_DEFERRED),
474 TCPF_MTU_REDUCED_DEFERRED = (1UL << TCP_MTU_REDUCED_DEFERRED),
475 };
476
477 #define tcp_sk(ptr) container_of_const(ptr, struct tcp_sock, inet_conn.icsk_inet.sk)
478
479 /* Variant of tcp_sk() upgrading a const sock to a read/write tcp socket.
480 * Used in context of (lockless) tcp listeners.
481 */
482 #define tcp_sk_rw(ptr) container_of(ptr, struct tcp_sock, inet_conn.icsk_inet.sk)
483
484 struct tcp_timewait_sock {
485 struct inet_timewait_sock tw_sk;
486 #define tw_rcv_nxt tw_sk.__tw_common.skc_tw_rcv_nxt
487 #define tw_snd_nxt tw_sk.__tw_common.skc_tw_snd_nxt
488 u32 tw_rcv_wnd;
489 u32 tw_ts_offset;
490 u32 tw_ts_recent;
491
492 /* The time we sent the last out-of-window ACK: */
493 u32 tw_last_oow_ack_time;
494
495 int tw_ts_recent_stamp;
496 u32 tw_tx_delay;
497 #ifdef CONFIG_TCP_MD5SIG
498 struct tcp_md5sig_key *tw_md5_key;
499 #endif
500 };
501
tcp_twsk(const struct sock * sk)502 static inline struct tcp_timewait_sock *tcp_twsk(const struct sock *sk)
503 {
504 return (struct tcp_timewait_sock *)sk;
505 }
506
tcp_passive_fastopen(const struct sock * sk)507 static inline bool tcp_passive_fastopen(const struct sock *sk)
508 {
509 return sk->sk_state == TCP_SYN_RECV &&
510 rcu_access_pointer(tcp_sk(sk)->fastopen_rsk) != NULL;
511 }
512
fastopen_queue_tune(struct sock * sk,int backlog)513 static inline void fastopen_queue_tune(struct sock *sk, int backlog)
514 {
515 struct request_sock_queue *queue = &inet_csk(sk)->icsk_accept_queue;
516 int somaxconn = READ_ONCE(sock_net(sk)->core.sysctl_somaxconn);
517
518 WRITE_ONCE(queue->fastopenq.max_qlen, min_t(unsigned int, backlog, somaxconn));
519 }
520
tcp_move_syn(struct tcp_sock * tp,struct request_sock * req)521 static inline void tcp_move_syn(struct tcp_sock *tp,
522 struct request_sock *req)
523 {
524 tp->saved_syn = req->saved_syn;
525 req->saved_syn = NULL;
526 }
527
tcp_saved_syn_free(struct tcp_sock * tp)528 static inline void tcp_saved_syn_free(struct tcp_sock *tp)
529 {
530 kfree(tp->saved_syn);
531 tp->saved_syn = NULL;
532 }
533
tcp_saved_syn_len(const struct saved_syn * saved_syn)534 static inline u32 tcp_saved_syn_len(const struct saved_syn *saved_syn)
535 {
536 return saved_syn->mac_hdrlen + saved_syn->network_hdrlen +
537 saved_syn->tcp_hdrlen;
538 }
539
540 struct sk_buff *tcp_get_timestamping_opt_stats(const struct sock *sk,
541 const struct sk_buff *orig_skb,
542 const struct sk_buff *ack_skb);
543
tcp_mss_clamp(const struct tcp_sock * tp,u16 mss)544 static inline u16 tcp_mss_clamp(const struct tcp_sock *tp, u16 mss)
545 {
546 /* We use READ_ONCE() here because socket might not be locked.
547 * This happens for listeners.
548 */
549 u16 user_mss = READ_ONCE(tp->rx_opt.user_mss);
550
551 return (user_mss && user_mss < mss) ? user_mss : mss;
552 }
553
554 int tcp_skb_shift(struct sk_buff *to, struct sk_buff *from, int pcount,
555 int shiftlen);
556
557 void __tcp_sock_set_cork(struct sock *sk, bool on);
558 void tcp_sock_set_cork(struct sock *sk, bool on);
559 int tcp_sock_set_keepcnt(struct sock *sk, int val);
560 int tcp_sock_set_keepidle_locked(struct sock *sk, int val);
561 int tcp_sock_set_keepidle(struct sock *sk, int val);
562 int tcp_sock_set_keepintvl(struct sock *sk, int val);
563 void __tcp_sock_set_nodelay(struct sock *sk, bool on);
564 void tcp_sock_set_nodelay(struct sock *sk);
565 void tcp_sock_set_quickack(struct sock *sk, int val);
566 int tcp_sock_set_syncnt(struct sock *sk, int val);
567 int tcp_sock_set_user_timeout(struct sock *sk, int val);
568
569 #endif /* _LINUX_TCP_H */
570