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 protocol.
7 *
8 * Version: @(#)tcp.h 1.0.2 04/28/93
9 *
10 * Author: Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
11 *
12 * This program is free software; you can redistribute it and/or
13 * modify it under the terms of the GNU General Public License
14 * as published by the Free Software Foundation; either version
15 * 2 of the License, or (at your option) any later version.
16 */
17 #ifndef _LINUX_TCP_H
18 #define _LINUX_TCP_H
19
20
21 #include <linux/skbuff.h>
22 #include <net/sock.h>
23 #include <net/inet_connection_sock.h>
24 #include <net/inet_timewait_sock.h>
25 #include <uapi/linux/tcp.h>
26
tcp_hdr(const struct sk_buff * skb)27 static inline struct tcphdr *tcp_hdr(const struct sk_buff *skb)
28 {
29 return (struct tcphdr *)skb_transport_header(skb);
30 }
31
tcp_hdrlen(const struct sk_buff * skb)32 static inline unsigned int tcp_hdrlen(const struct sk_buff *skb)
33 {
34 return tcp_hdr(skb)->doff * 4;
35 }
36
inner_tcp_hdr(const struct sk_buff * skb)37 static inline struct tcphdr *inner_tcp_hdr(const struct sk_buff *skb)
38 {
39 return (struct tcphdr *)skb_inner_transport_header(skb);
40 }
41
inner_tcp_hdrlen(const struct sk_buff * skb)42 static inline unsigned int inner_tcp_hdrlen(const struct sk_buff *skb)
43 {
44 return inner_tcp_hdr(skb)->doff * 4;
45 }
46
tcp_optlen(const struct sk_buff * skb)47 static inline unsigned int tcp_optlen(const struct sk_buff *skb)
48 {
49 return (tcp_hdr(skb)->doff - 5) * 4;
50 }
51
52 /* TCP Fast Open */
53 #define TCP_FASTOPEN_COOKIE_MIN 4 /* Min Fast Open Cookie size in bytes */
54 #define TCP_FASTOPEN_COOKIE_MAX 16 /* Max Fast Open Cookie size in bytes */
55 #define TCP_FASTOPEN_COOKIE_SIZE 8 /* the size employed by this impl. */
56
57 /* TCP Fast Open Cookie as stored in memory */
58 struct tcp_fastopen_cookie {
59 s8 len;
60 u8 val[TCP_FASTOPEN_COOKIE_MAX];
61 bool exp; /* In RFC6994 experimental option format */
62 };
63
64 /* This defines a selective acknowledgement block. */
65 struct tcp_sack_block_wire {
66 __be32 start_seq;
67 __be32 end_seq;
68 };
69
70 struct tcp_sack_block {
71 u32 start_seq;
72 u32 end_seq;
73 };
74
75 /*These are used to set the sack_ok field in struct tcp_options_received */
76 #define TCP_SACK_SEEN (1 << 0) /*1 = peer is SACK capable, */
77 #define TCP_FACK_ENABLED (1 << 1) /*1 = FACK is enabled locally*/
78 #define TCP_DSACK_SEEN (1 << 2) /*1 = DSACK was received from peer*/
79
80 struct tcp_options_received {
81 /* PAWS/RTTM data */
82 long ts_recent_stamp;/* Time we stored ts_recent (for aging) */
83 u32 ts_recent; /* Time stamp to echo next */
84 u32 rcv_tsval; /* Time stamp value */
85 u32 rcv_tsecr; /* Time stamp echo reply */
86 u16 saw_tstamp : 1, /* Saw TIMESTAMP on last packet */
87 tstamp_ok : 1, /* TIMESTAMP seen on SYN packet */
88 dsack : 1, /* D-SACK is scheduled */
89 wscale_ok : 1, /* Wscale seen on SYN packet */
90 sack_ok : 4, /* SACK seen on SYN packet */
91 snd_wscale : 4, /* Window scaling received from sender */
92 rcv_wscale : 4; /* Window scaling to send to receiver */
93 u8 num_sacks; /* Number of SACK blocks */
94 u16 user_mss; /* mss requested by user in ioctl */
95 u16 mss_clamp; /* Maximal mss, negotiated at connection setup */
96 };
97
tcp_clear_options(struct tcp_options_received * rx_opt)98 static inline void tcp_clear_options(struct tcp_options_received *rx_opt)
99 {
100 rx_opt->tstamp_ok = rx_opt->sack_ok = 0;
101 rx_opt->wscale_ok = rx_opt->snd_wscale = 0;
102 }
103
104 /* This is the max number of SACKS that we'll generate and process. It's safe
105 * to increase this, although since:
106 * size = TCPOLEN_SACK_BASE_ALIGNED (4) + n * TCPOLEN_SACK_PERBLOCK (8)
107 * only four options will fit in a standard TCP header */
108 #define TCP_NUM_SACKS 4
109
110 struct tcp_request_sock_ops;
111
112 struct tcp_request_sock {
113 struct inet_request_sock req;
114 const struct tcp_request_sock_ops *af_specific;
115 bool tfo_listener;
116 u32 rcv_isn;
117 u32 snt_isn;
118 u32 snt_synack; /* synack sent time */
119 u32 last_oow_ack_time; /* last SYNACK */
120 u32 rcv_nxt; /* the ack # by SYNACK. For
121 * FastOpen it's the seq#
122 * after data-in-SYN.
123 */
124 };
125
tcp_rsk(const struct request_sock * req)126 static inline struct tcp_request_sock *tcp_rsk(const struct request_sock *req)
127 {
128 return (struct tcp_request_sock *)req;
129 }
130
131 struct tcp_sock {
132 /* inet_connection_sock has to be the first member of tcp_sock */
133 struct inet_connection_sock inet_conn;
134 u16 tcp_header_len; /* Bytes of tcp header to send */
135 u16 gso_segs; /* Max number of segs per GSO packet */
136
137 /*
138 * Header prediction flags
139 * 0x5?10 << 16 + snd_wnd in net byte order
140 */
141 __be32 pred_flags;
142
143 /*
144 * RFC793 variables by their proper names. This means you can
145 * read the code and the spec side by side (and laugh ...)
146 * See RFC793 and RFC1122. The RFC writes these in capitals.
147 */
148 u64 bytes_received; /* RFC4898 tcpEStatsAppHCThruOctetsReceived
149 * sum(delta(rcv_nxt)), or how many bytes
150 * were acked.
151 */
152 u32 rcv_nxt; /* What we want to receive next */
153 u32 copied_seq; /* Head of yet unread data */
154 u32 rcv_wup; /* rcv_nxt on last window update sent */
155 u32 snd_nxt; /* Next sequence we send */
156
157 u64 bytes_acked; /* RFC4898 tcpEStatsAppHCThruOctetsAcked
158 * sum(delta(snd_una)), or how many bytes
159 * were acked.
160 */
161 struct u64_stats_sync syncp; /* protects 64bit vars (cf tcp_get_info()) */
162
163 u32 snd_una; /* First byte we want an ack for */
164 u32 snd_sml; /* Last byte of the most recently transmitted small packet */
165 u32 rcv_tstamp; /* timestamp of last received ACK (for keepalives) */
166 u32 lsndtime; /* timestamp of last sent data packet (for restart window) */
167 u32 last_oow_ack_time; /* timestamp of last out-of-window ACK */
168
169 u32 tsoffset; /* timestamp offset */
170
171 struct list_head tsq_node; /* anchor in tsq_tasklet.head list */
172 unsigned long tsq_flags;
173
174 /* Data for direct copy to user */
175 struct {
176 struct sk_buff_head prequeue;
177 struct task_struct *task;
178 struct msghdr *msg;
179 int memory;
180 int len;
181 } ucopy;
182
183 u32 snd_wl1; /* Sequence for window update */
184 u32 snd_wnd; /* The window we expect to receive */
185 u32 max_window; /* Maximal window ever seen from peer */
186 u32 mss_cache; /* Cached effective mss, not including SACKS */
187
188 u32 window_clamp; /* Maximal window to advertise */
189 u32 rcv_ssthresh; /* Current window clamp */
190
191 u16 advmss; /* Advertised MSS */
192 u8 unused;
193 u8 nonagle : 4,/* Disable Nagle algorithm? */
194 thin_lto : 1,/* Use linear timeouts for thin streams */
195 thin_dupack : 1,/* Fast retransmit on first dupack */
196 repair : 1,
197 frto : 1;/* F-RTO (RFC5682) activated in CA_Loss */
198 u8 repair_queue;
199 u8 do_early_retrans:1,/* Enable RFC5827 early-retransmit */
200 syn_data:1, /* SYN includes data */
201 syn_fastopen:1, /* SYN includes Fast Open option */
202 syn_fastopen_exp:1,/* SYN includes Fast Open exp. option */
203 syn_data_acked:1,/* data in SYN is acked by SYN-ACK */
204 is_cwnd_limited:1;/* forward progress limited by snd_cwnd? */
205 u32 tlp_high_seq; /* snd_nxt at the time of TLP retransmit. */
206
207 /* RTT measurement */
208 u32 srtt_us; /* smoothed round trip time << 3 in usecs */
209 u32 mdev_us; /* medium deviation */
210 u32 mdev_max_us; /* maximal mdev for the last rtt period */
211 u32 rttvar_us; /* smoothed mdev_max */
212 u32 rtt_seq; /* sequence number to update rttvar */
213
214 u32 packets_out; /* Packets which are "in flight" */
215 u32 retrans_out; /* Retransmitted packets out */
216 u32 max_packets_out; /* max packets_out in last window */
217 u32 max_packets_seq; /* right edge of max_packets_out flight */
218
219 u16 urg_data; /* Saved octet of OOB data and control flags */
220 u8 ecn_flags; /* ECN status bits. */
221 u8 keepalive_probes; /* num of allowed keep alive probes */
222 u32 reordering; /* Packet reordering metric. */
223 u32 snd_up; /* Urgent pointer */
224
225 /*
226 * Options received (usually on last packet, some only on SYN packets).
227 */
228 struct tcp_options_received rx_opt;
229
230 /*
231 * Slow start and congestion control (see also Nagle, and Karn & Partridge)
232 */
233 u32 snd_ssthresh; /* Slow start size threshold */
234 u32 snd_cwnd; /* Sending congestion window */
235 u32 snd_cwnd_cnt; /* Linear increase counter */
236 u32 snd_cwnd_clamp; /* Do not allow snd_cwnd to grow above this */
237 u32 snd_cwnd_used;
238 u32 snd_cwnd_stamp;
239 u32 prior_cwnd; /* Congestion window at start of Recovery. */
240 u32 prr_delivered; /* Number of newly delivered packets to
241 * receiver in Recovery. */
242 u32 prr_out; /* Total number of pkts sent during Recovery. */
243
244 u32 rcv_wnd; /* Current receiver window */
245 u32 write_seq; /* Tail(+1) of data held in tcp send buffer */
246 u32 notsent_lowat; /* TCP_NOTSENT_LOWAT */
247 u32 pushed_seq; /* Last pushed seq, required to talk to windows */
248 u32 lost_out; /* Lost packets */
249 u32 sacked_out; /* SACK'd packets */
250 u32 fackets_out; /* FACK'd packets */
251
252 /* from STCP, retrans queue hinting */
253 struct sk_buff* lost_skb_hint;
254 struct sk_buff *retransmit_skb_hint;
255
256 /* OOO segments go in this list. Note that socket lock must be held,
257 * as we do not use sk_buff_head lock.
258 */
259 struct sk_buff_head out_of_order_queue;
260
261 /* SACKs data, these 2 need to be together (see tcp_options_write) */
262 struct tcp_sack_block duplicate_sack[1]; /* D-SACK block */
263 struct tcp_sack_block selective_acks[4]; /* The SACKS themselves*/
264
265 struct tcp_sack_block recv_sack_cache[4];
266
267 struct sk_buff *highest_sack; /* skb just after the highest
268 * skb with SACKed bit set
269 * (validity guaranteed only if
270 * sacked_out > 0)
271 */
272
273 int lost_cnt_hint;
274 u32 retransmit_high; /* L-bits may be on up to this seqno */
275
276 u32 lost_retrans_low; /* Sent seq after any rxmit (lowest) */
277
278 u32 prior_ssthresh; /* ssthresh saved at recovery start */
279 u32 high_seq; /* snd_nxt at onset of congestion */
280
281 u32 retrans_stamp; /* Timestamp of the last retransmit,
282 * also used in SYN-SENT to remember stamp of
283 * the first SYN. */
284 u32 undo_marker; /* snd_una upon a new recovery episode. */
285 int undo_retrans; /* number of undoable retransmissions. */
286 u32 total_retrans; /* Total retransmits for entire connection */
287
288 u32 urg_seq; /* Seq of received urgent pointer */
289 unsigned int keepalive_time; /* time before keep alive takes place */
290 unsigned int keepalive_intvl; /* time interval between keep alive probes */
291
292 int linger2;
293
294 /* Receiver side RTT estimation */
295 struct {
296 u32 rtt;
297 u32 seq;
298 u32 time;
299 } rcv_rtt_est;
300
301 /* Receiver queue space */
302 struct {
303 int space;
304 u32 seq;
305 u32 time;
306 } rcvq_space;
307
308 /* TCP-specific MTU probe information. */
309 struct {
310 u32 probe_seq_start;
311 u32 probe_seq_end;
312 } mtu_probe;
313 u32 mtu_info; /* We received an ICMP_FRAG_NEEDED / ICMPV6_PKT_TOOBIG
314 * while socket was owned by user.
315 */
316
317 #ifdef CONFIG_TCP_MD5SIG
318 /* TCP AF-Specific parts; only used by MD5 Signature support so far */
319 const struct tcp_sock_af_ops *af_specific;
320
321 /* TCP MD5 Signature Option information */
322 struct tcp_md5sig_info __rcu *md5sig_info;
323 #endif
324
325 /* TCP fastopen related information */
326 struct tcp_fastopen_request *fastopen_req;
327 /* fastopen_rsk points to request_sock that resulted in this big
328 * socket. Used to retransmit SYNACKs etc.
329 */
330 struct request_sock *fastopen_rsk;
331 };
332
333 enum tsq_flags {
334 TSQ_THROTTLED,
335 TSQ_QUEUED,
336 TCP_TSQ_DEFERRED, /* tcp_tasklet_func() found socket was owned */
337 TCP_WRITE_TIMER_DEFERRED, /* tcp_write_timer() found socket was owned */
338 TCP_DELACK_TIMER_DEFERRED, /* tcp_delack_timer() found socket was owned */
339 TCP_MTU_REDUCED_DEFERRED, /* tcp_v{4|6}_err() could not call
340 * tcp_v{4|6}_mtu_reduced()
341 */
342 };
343
tcp_sk(const struct sock * sk)344 static inline struct tcp_sock *tcp_sk(const struct sock *sk)
345 {
346 return (struct tcp_sock *)sk;
347 }
348
349 struct tcp_timewait_sock {
350 struct inet_timewait_sock tw_sk;
351 u32 tw_rcv_nxt;
352 u32 tw_snd_nxt;
353 u32 tw_rcv_wnd;
354 u32 tw_ts_offset;
355 u32 tw_ts_recent;
356
357 /* The time we sent the last out-of-window ACK: */
358 u32 tw_last_oow_ack_time;
359
360 long tw_ts_recent_stamp;
361 #ifdef CONFIG_TCP_MD5SIG
362 struct tcp_md5sig_key *tw_md5_key;
363 #endif
364 };
365
tcp_twsk(const struct sock * sk)366 static inline struct tcp_timewait_sock *tcp_twsk(const struct sock *sk)
367 {
368 return (struct tcp_timewait_sock *)sk;
369 }
370
tcp_passive_fastopen(const struct sock * sk)371 static inline bool tcp_passive_fastopen(const struct sock *sk)
372 {
373 return (sk->sk_state == TCP_SYN_RECV &&
374 tcp_sk(sk)->fastopen_rsk != NULL);
375 }
376
377 extern void tcp_sock_destruct(struct sock *sk);
378
fastopen_init_queue(struct sock * sk,int backlog)379 static inline int fastopen_init_queue(struct sock *sk, int backlog)
380 {
381 struct request_sock_queue *queue =
382 &inet_csk(sk)->icsk_accept_queue;
383
384 if (queue->fastopenq == NULL) {
385 queue->fastopenq = kzalloc(
386 sizeof(struct fastopen_queue),
387 sk->sk_allocation);
388 if (queue->fastopenq == NULL)
389 return -ENOMEM;
390
391 sk->sk_destruct = tcp_sock_destruct;
392 spin_lock_init(&queue->fastopenq->lock);
393 }
394 queue->fastopenq->max_qlen = backlog;
395 return 0;
396 }
397
398 #endif /* _LINUX_TCP_H */
399