1 /* SPDX-License-Identifier: GPL-2.0-or-later */
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.
7 * Definitions for the TCP protocol.
9 * Version: @(#)tcp.h 1.0.2 04/28/93
11 * Author: Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
17 #include <linux/skbuff.h>
18 #include <linux/win_minmax.h>
20 #include <net/inet_connection_sock.h>
21 #include <net/inet_timewait_sock.h>
22 #include <uapi/linux/tcp.h>
24 static inline struct tcphdr
*tcp_hdr(const struct sk_buff
*skb
)
26 return (struct tcphdr
*)skb_transport_header(skb
);
29 static inline unsigned int __tcp_hdrlen(const struct tcphdr
*th
)
34 static inline unsigned int tcp_hdrlen(const struct sk_buff
*skb
)
36 return __tcp_hdrlen(tcp_hdr(skb
));
39 static inline struct tcphdr
*inner_tcp_hdr(const struct sk_buff
*skb
)
41 return (struct tcphdr
*)skb_inner_transport_header(skb
);
44 static inline unsigned int inner_tcp_hdrlen(const struct sk_buff
*skb
)
46 return inner_tcp_hdr(skb
)->doff
* 4;
49 static inline unsigned int tcp_optlen(const struct sk_buff
*skb
)
51 return (tcp_hdr(skb
)->doff
- 5) * 4;
55 #define TCP_FASTOPEN_COOKIE_MIN 4 /* Min Fast Open Cookie size in bytes */
56 #define TCP_FASTOPEN_COOKIE_MAX 16 /* Max Fast Open Cookie size in bytes */
57 #define TCP_FASTOPEN_COOKIE_SIZE 8 /* the size employed by this impl. */
59 /* TCP Fast Open Cookie as stored in memory */
60 struct tcp_fastopen_cookie
{
61 __le64 val
[DIV_ROUND_UP(TCP_FASTOPEN_COOKIE_MAX
, sizeof(u64
))];
63 bool exp
; /* In RFC6994 experimental option format */
66 /* This defines a selective acknowledgement block. */
67 struct tcp_sack_block_wire
{
72 struct tcp_sack_block
{
77 /*These are used to set the sack_ok field in struct tcp_options_received */
78 #define TCP_SACK_SEEN (1 << 0) /*1 = peer is SACK capable, */
79 #define TCP_DSACK_SEEN (1 << 2) /*1 = DSACK was received from peer*/
81 struct tcp_options_received
{
83 int ts_recent_stamp
;/* Time we stored ts_recent (for aging) */
84 u32 ts_recent
; /* Time stamp to echo next */
85 u32 rcv_tsval
; /* Time stamp value */
86 u32 rcv_tsecr
; /* Time stamp echo reply */
87 u16 saw_tstamp
: 1, /* Saw TIMESTAMP on last packet */
88 tstamp_ok
: 1, /* TIMESTAMP seen on SYN packet */
89 dsack
: 1, /* D-SACK is scheduled */
90 wscale_ok
: 1, /* Wscale seen on SYN packet */
91 sack_ok
: 3, /* SACK seen on SYN packet */
92 smc_ok
: 1, /* SMC seen on SYN packet */
93 snd_wscale
: 4, /* Window scaling received from sender */
94 rcv_wscale
: 4; /* Window scaling to send to receiver */
95 u8 saw_unknown
:1, /* Received unknown option */
97 u8 num_sacks
; /* Number of SACK blocks */
98 u16 user_mss
; /* mss requested by user in ioctl */
99 u16 mss_clamp
; /* Maximal mss, negotiated at connection setup */
102 static inline void tcp_clear_options(struct tcp_options_received
*rx_opt
)
104 rx_opt
->tstamp_ok
= rx_opt
->sack_ok
= 0;
105 rx_opt
->wscale_ok
= rx_opt
->snd_wscale
= 0;
106 #if IS_ENABLED(CONFIG_SMC)
111 /* This is the max number of SACKS that we'll generate and process. It's safe
112 * to increase this, although since:
113 * size = TCPOLEN_SACK_BASE_ALIGNED (4) + n * TCPOLEN_SACK_PERBLOCK (8)
114 * only four options will fit in a standard TCP header */
115 #define TCP_NUM_SACKS 4
117 struct tcp_request_sock_ops
;
119 struct tcp_request_sock
{
120 struct inet_request_sock req
;
121 const struct tcp_request_sock_ops
*af_specific
;
122 u64 snt_synack
; /* first SYNACK sent time */
125 #if IS_ENABLED(CONFIG_MPTCP)
132 u32 last_oow_ack_time
; /* last SYNACK */
133 u32 rcv_nxt
; /* the ack # by SYNACK. For
134 * FastOpen it's the seq#
140 static inline struct tcp_request_sock
*tcp_rsk(const struct request_sock
*req
)
142 return (struct tcp_request_sock
*)req
;
146 /* inet_connection_sock has to be the first member of tcp_sock */
147 struct inet_connection_sock inet_conn
;
148 u16 tcp_header_len
; /* Bytes of tcp header to send */
149 u16 gso_segs
; /* Max number of segs per GSO packet */
152 * Header prediction flags
153 * 0x5?10 << 16 + snd_wnd in net byte order
158 * RFC793 variables by their proper names. This means you can
159 * read the code and the spec side by side (and laugh ...)
160 * See RFC793 and RFC1122. The RFC writes these in capitals.
162 u64 bytes_received
; /* RFC4898 tcpEStatsAppHCThruOctetsReceived
163 * sum(delta(rcv_nxt)), or how many bytes
166 u32 segs_in
; /* RFC4898 tcpEStatsPerfSegsIn
167 * total number of segments in.
169 u32 data_segs_in
; /* RFC4898 tcpEStatsPerfDataSegsIn
170 * total number of data segments in.
172 u32 rcv_nxt
; /* What we want to receive next */
173 u32 copied_seq
; /* Head of yet unread data */
174 u32 rcv_wup
; /* rcv_nxt on last window update sent */
175 u32 snd_nxt
; /* Next sequence we send */
176 u32 segs_out
; /* RFC4898 tcpEStatsPerfSegsOut
177 * The total number of segments sent.
179 u32 data_segs_out
; /* RFC4898 tcpEStatsPerfDataSegsOut
180 * total number of data segments sent.
182 u64 bytes_sent
; /* RFC4898 tcpEStatsPerfHCDataOctetsOut
183 * total number of data bytes sent.
185 u64 bytes_acked
; /* RFC4898 tcpEStatsAppHCThruOctetsAcked
186 * sum(delta(snd_una)), or how many bytes
189 u32 dsack_dups
; /* RFC4898 tcpEStatsStackDSACKDups
190 * total number of DSACK blocks received
192 u32 snd_una
; /* First byte we want an ack for */
193 u32 snd_sml
; /* Last byte of the most recently transmitted small packet */
194 u32 rcv_tstamp
; /* timestamp of last received ACK (for keepalives) */
195 u32 lsndtime
; /* timestamp of last sent data packet (for restart window) */
196 u32 last_oow_ack_time
; /* timestamp of last out-of-window ACK */
197 u32 compressed_ack_rcv_nxt
;
199 u32 tsoffset
; /* timestamp offset */
201 struct list_head tsq_node
; /* anchor in tsq_tasklet.head list */
202 struct list_head tsorted_sent_queue
; /* time-sorted sent but un-SACKed skbs */
204 u32 snd_wl1
; /* Sequence for window update */
205 u32 snd_wnd
; /* The window we expect to receive */
206 u32 max_window
; /* Maximal window ever seen from peer */
207 u32 mss_cache
; /* Cached effective mss, not including SACKS */
209 u32 window_clamp
; /* Maximal window to advertise */
210 u32 rcv_ssthresh
; /* Current window clamp */
212 /* Information of the most recently (s)acked skb */
214 u64 mstamp
; /* (Re)sent time of the skb */
215 u32 rtt_us
; /* Associated RTT */
216 u32 end_seq
; /* Ending TCP sequence of the skb */
217 u32 last_delivered
; /* tp->delivered at last reo_wnd adj */
218 u8 reo_wnd_steps
; /* Allowed reordering window */
219 #define TCP_RACK_RECOVERY_THRESH 16
220 u8 reo_wnd_persist
:5, /* No. of recovery since last adj */
221 dsack_seen
:1, /* Whether DSACK seen after last adj */
222 advanced
:1; /* mstamp advanced since last lost marking */
224 u16 advmss
; /* Advertised MSS */
226 u8 dup_ack_counter
:2,
227 tlp_retrans
:1, /* TLP is a retransmission */
229 u32 chrono_start
; /* Start time in jiffies of a TCP chrono */
230 u32 chrono_stat
[3]; /* Time in jiffies for chrono_stat stats */
231 u8 chrono_type
:2, /* current chronograph type */
232 rate_app_limited
:1, /* rate_{delivered,interval_us} limited? */
233 fastopen_connect
:1, /* FASTOPEN_CONNECT sockopt */
234 fastopen_no_cookie
:1, /* Allow send/recv SYN+data without a cookie */
235 is_sack_reneg
:1, /* in recovery from loss with SACK reneg? */
236 fastopen_client_fail
:2; /* reason why fastopen failed */
237 u8 nonagle
: 4,/* Disable Nagle algorithm? */
238 thin_lto
: 1,/* Use linear timeouts for thin streams */
239 recvmsg_inq
: 1,/* Indicate # of bytes in queue upon recvmsg */
241 frto
: 1;/* F-RTO (RFC5682) activated in CA_Loss */
243 u8 save_syn
:2, /* Save headers of SYN packet */
244 syn_data
:1, /* SYN includes data */
245 syn_fastopen
:1, /* SYN includes Fast Open option */
246 syn_fastopen_exp
:1,/* SYN includes Fast Open exp. option */
247 syn_fastopen_ch
:1, /* Active TFO re-enabling probe */
248 syn_data_acked
:1,/* data in SYN is acked by SYN-ACK */
249 is_cwnd_limited
:1;/* forward progress limited by snd_cwnd? */
250 u32 tlp_high_seq
; /* snd_nxt at the time of TLP */
252 u32 tcp_tx_delay
; /* delay (in usec) added to TX packets */
253 u64 tcp_wstamp_ns
; /* departure time for next sent data packet */
254 u64 tcp_clock_cache
; /* cache last tcp_clock_ns() (see tcp_mstamp_refresh()) */
256 /* RTT measurement */
257 u64 tcp_mstamp
; /* most recent packet received/sent */
258 u32 srtt_us
; /* smoothed round trip time << 3 in usecs */
259 u32 mdev_us
; /* medium deviation */
260 u32 mdev_max_us
; /* maximal mdev for the last rtt period */
261 u32 rttvar_us
; /* smoothed mdev_max */
262 u32 rtt_seq
; /* sequence number to update rttvar */
263 struct minmax rtt_min
;
265 u32 packets_out
; /* Packets which are "in flight" */
266 u32 retrans_out
; /* Retransmitted packets out */
267 u32 max_packets_out
; /* max packets_out in last window */
268 u32 max_packets_seq
; /* right edge of max_packets_out flight */
270 u16 urg_data
; /* Saved octet of OOB data and control flags */
271 u8 ecn_flags
; /* ECN status bits. */
272 u8 keepalive_probes
; /* num of allowed keep alive probes */
273 u32 reordering
; /* Packet reordering metric. */
274 u32 reord_seen
; /* number of data packet reordering events */
275 u32 snd_up
; /* Urgent pointer */
278 * Options received (usually on last packet, some only on SYN packets).
280 struct tcp_options_received rx_opt
;
283 * Slow start and congestion control (see also Nagle, and Karn & Partridge)
285 u32 snd_ssthresh
; /* Slow start size threshold */
286 u32 snd_cwnd
; /* Sending congestion window */
287 u32 snd_cwnd_cnt
; /* Linear increase counter */
288 u32 snd_cwnd_clamp
; /* Do not allow snd_cwnd to grow above this */
291 u32 prior_cwnd
; /* cwnd right before starting loss recovery */
292 u32 prr_delivered
; /* Number of newly delivered packets to
293 * receiver in Recovery. */
294 u32 prr_out
; /* Total number of pkts sent during Recovery. */
295 u32 delivered
; /* Total data packets delivered incl. rexmits */
296 u32 delivered_ce
; /* Like the above but only ECE marked packets */
297 u32 lost
; /* Total data packets lost incl. rexmits */
298 u32 app_limited
; /* limited until "delivered" reaches this val */
299 u64 first_tx_mstamp
; /* start of window send phase */
300 u64 delivered_mstamp
; /* time we reached "delivered" */
301 u32 rate_delivered
; /* saved rate sample: packets delivered */
302 u32 rate_interval_us
; /* saved rate sample: time elapsed */
304 u32 rcv_wnd
; /* Current receiver window */
305 u32 write_seq
; /* Tail(+1) of data held in tcp send buffer */
306 u32 notsent_lowat
; /* TCP_NOTSENT_LOWAT */
307 u32 pushed_seq
; /* Last pushed seq, required to talk to windows */
308 u32 lost_out
; /* Lost packets */
309 u32 sacked_out
; /* SACK'd packets */
311 struct hrtimer pacing_timer
;
312 struct hrtimer compressed_ack_timer
;
314 /* from STCP, retrans queue hinting */
315 struct sk_buff
* lost_skb_hint
;
316 struct sk_buff
*retransmit_skb_hint
;
318 /* OOO segments go in this rbtree. Socket lock must be held. */
319 struct rb_root out_of_order_queue
;
320 struct sk_buff
*ooo_last_skb
; /* cache rb_last(out_of_order_queue) */
322 /* SACKs data, these 2 need to be together (see tcp_options_write) */
323 struct tcp_sack_block duplicate_sack
[1]; /* D-SACK block */
324 struct tcp_sack_block selective_acks
[4]; /* The SACKS themselves*/
326 struct tcp_sack_block recv_sack_cache
[4];
328 struct sk_buff
*highest_sack
; /* skb just after the highest
329 * skb with SACKed bit set
330 * (validity guaranteed only if
336 u32 prior_ssthresh
; /* ssthresh saved at recovery start */
337 u32 high_seq
; /* snd_nxt at onset of congestion */
339 u32 retrans_stamp
; /* Timestamp of the last retransmit,
340 * also used in SYN-SENT to remember stamp of
342 u32 undo_marker
; /* snd_una upon a new recovery episode. */
343 int undo_retrans
; /* number of undoable retransmissions. */
344 u64 bytes_retrans
; /* RFC4898 tcpEStatsPerfOctetsRetrans
345 * Total data bytes retransmitted
347 u32 total_retrans
; /* Total retransmits for entire connection */
349 u32 urg_seq
; /* Seq of received urgent pointer */
350 unsigned int keepalive_time
; /* time before keep alive takes place */
351 unsigned int keepalive_intvl
; /* time interval between keep alive probes */
356 /* Sock_ops bpf program related variables */
358 u8 bpf_sock_ops_cb_flags
; /* Control calling BPF programs
359 * values defined in uapi/linux/tcp.h
361 #define BPF_SOCK_OPS_TEST_FLAG(TP, ARG) (TP->bpf_sock_ops_cb_flags & ARG)
363 #define BPF_SOCK_OPS_TEST_FLAG(TP, ARG) 0
366 u16 timeout_rehash
; /* Timeout-triggered rehash attempts */
368 u32 rcv_ooopack
; /* Received out-of-order packets, for tcpinfo */
370 /* Receiver side RTT estimation */
371 u32 rcv_rtt_last_tsecr
;
378 /* Receiver queue space */
385 /* TCP-specific MTU probe information. */
390 u32 mtu_info
; /* We received an ICMP_FRAG_NEEDED / ICMPV6_PKT_TOOBIG
391 * while socket was owned by user.
393 #if IS_ENABLED(CONFIG_MPTCP)
396 #if IS_ENABLED(CONFIG_SMC)
397 bool syn_smc
; /* SYN includes SMC */
400 #ifdef CONFIG_TCP_MD5SIG
401 /* TCP AF-Specific parts; only used by MD5 Signature support so far */
402 const struct tcp_sock_af_ops
*af_specific
;
404 /* TCP MD5 Signature Option information */
405 struct tcp_md5sig_info __rcu
*md5sig_info
;
408 /* TCP fastopen related information */
409 struct tcp_fastopen_request
*fastopen_req
;
410 /* fastopen_rsk points to request_sock that resulted in this big
411 * socket. Used to retransmit SYNACKs etc.
413 struct request_sock __rcu
*fastopen_rsk
;
414 struct saved_syn
*saved_syn
;
420 TCP_TSQ_DEFERRED
, /* tcp_tasklet_func() found socket was owned */
421 TCP_WRITE_TIMER_DEFERRED
, /* tcp_write_timer() found socket was owned */
422 TCP_DELACK_TIMER_DEFERRED
, /* tcp_delack_timer() found socket was owned */
423 TCP_MTU_REDUCED_DEFERRED
, /* tcp_v{4|6}_err() could not call
424 * tcp_v{4|6}_mtu_reduced()
429 TSQF_THROTTLED
= (1UL << TSQ_THROTTLED
),
430 TSQF_QUEUED
= (1UL << TSQ_QUEUED
),
431 TCPF_TSQ_DEFERRED
= (1UL << TCP_TSQ_DEFERRED
),
432 TCPF_WRITE_TIMER_DEFERRED
= (1UL << TCP_WRITE_TIMER_DEFERRED
),
433 TCPF_DELACK_TIMER_DEFERRED
= (1UL << TCP_DELACK_TIMER_DEFERRED
),
434 TCPF_MTU_REDUCED_DEFERRED
= (1UL << TCP_MTU_REDUCED_DEFERRED
),
437 static inline struct tcp_sock
*tcp_sk(const struct sock
*sk
)
439 return (struct tcp_sock
*)sk
;
442 struct tcp_timewait_sock
{
443 struct inet_timewait_sock tw_sk
;
444 #define tw_rcv_nxt tw_sk.__tw_common.skc_tw_rcv_nxt
445 #define tw_snd_nxt tw_sk.__tw_common.skc_tw_snd_nxt
450 /* The time we sent the last out-of-window ACK: */
451 u32 tw_last_oow_ack_time
;
453 int tw_ts_recent_stamp
;
455 #ifdef CONFIG_TCP_MD5SIG
456 struct tcp_md5sig_key
*tw_md5_key
;
460 static inline struct tcp_timewait_sock
*tcp_twsk(const struct sock
*sk
)
462 return (struct tcp_timewait_sock
*)sk
;
465 static inline bool tcp_passive_fastopen(const struct sock
*sk
)
467 return sk
->sk_state
== TCP_SYN_RECV
&&
468 rcu_access_pointer(tcp_sk(sk
)->fastopen_rsk
) != NULL
;
471 static inline void fastopen_queue_tune(struct sock
*sk
, int backlog
)
473 struct request_sock_queue
*queue
= &inet_csk(sk
)->icsk_accept_queue
;
474 int somaxconn
= READ_ONCE(sock_net(sk
)->core
.sysctl_somaxconn
);
476 queue
->fastopenq
.max_qlen
= min_t(unsigned int, backlog
, somaxconn
);
479 static inline void tcp_move_syn(struct tcp_sock
*tp
,
480 struct request_sock
*req
)
482 tp
->saved_syn
= req
->saved_syn
;
483 req
->saved_syn
= NULL
;
486 static inline void tcp_saved_syn_free(struct tcp_sock
*tp
)
488 kfree(tp
->saved_syn
);
489 tp
->saved_syn
= NULL
;
492 static inline u32
tcp_saved_syn_len(const struct saved_syn
*saved_syn
)
494 return saved_syn
->mac_hdrlen
+ saved_syn
->network_hdrlen
+
495 saved_syn
->tcp_hdrlen
;
498 struct sk_buff
*tcp_get_timestamping_opt_stats(const struct sock
*sk
,
499 const struct sk_buff
*orig_skb
,
500 const struct sk_buff
*ack_skb
);
502 static inline u16
tcp_mss_clamp(const struct tcp_sock
*tp
, u16 mss
)
504 /* We use READ_ONCE() here because socket might not be locked.
505 * This happens for listeners.
507 u16 user_mss
= READ_ONCE(tp
->rx_opt
.user_mss
);
509 return (user_mss
&& user_mss
< mss
) ? user_mss
: mss
;
512 int tcp_skb_shift(struct sk_buff
*to
, struct sk_buff
*from
, int pcount
,
515 void tcp_sock_set_cork(struct sock
*sk
, bool on
);
516 int tcp_sock_set_keepcnt(struct sock
*sk
, int val
);
517 int tcp_sock_set_keepidle_locked(struct sock
*sk
, int val
);
518 int tcp_sock_set_keepidle(struct sock
*sk
, int val
);
519 int tcp_sock_set_keepintvl(struct sock
*sk
, int val
);
520 void tcp_sock_set_nodelay(struct sock
*sk
);
521 void tcp_sock_set_quickack(struct sock
*sk
, int val
);
522 int tcp_sock_set_syncnt(struct sock
*sk
, int val
);
523 void tcp_sock_set_user_timeout(struct sock
*sk
, u32 val
);
525 #endif /* _LINUX_TCP_H */