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 <linux/dmaengine.h>
23 #include <net/sock.h>
24 #include <net/inet_connection_sock.h>
25 #include <net/inet_timewait_sock.h>
26 #include <uapi/linux/tcp.h>
27
tcp_hdr(const struct sk_buff * skb)28 static inline struct tcphdr *tcp_hdr(const struct sk_buff *skb)
29 {
30 return (struct tcphdr *)skb_transport_header(skb);
31 }
32
tcp_hdrlen(const struct sk_buff * skb)33 static inline unsigned int tcp_hdrlen(const struct sk_buff *skb)
34 {
35 return tcp_hdr(skb)->doff * 4;
36 }
37
inner_tcp_hdr(const struct sk_buff * skb)38 static inline struct tcphdr *inner_tcp_hdr(const struct sk_buff *skb)
39 {
40 return (struct tcphdr *)skb_inner_transport_header(skb);
41 }
42
inner_tcp_hdrlen(const struct sk_buff * skb)43 static inline unsigned int inner_tcp_hdrlen(const struct sk_buff *skb)
44 {
45 return inner_tcp_hdr(skb)->doff * 4;
46 }
47
tcp_optlen(const struct sk_buff * skb)48 static inline unsigned int tcp_optlen(const struct sk_buff *skb)
49 {
50 return (tcp_hdr(skb)->doff - 5) * 4;
51 }
52
53 /* TCP Fast Open */
54 #define TCP_FASTOPEN_COOKIE_MIN 4 /* Min Fast Open Cookie size in bytes */
55 #define TCP_FASTOPEN_COOKIE_MAX 16 /* Max Fast Open Cookie size in bytes */
56 #define TCP_FASTOPEN_COOKIE_SIZE 8 /* the size employed by this impl. */
57
58 /* TCP Fast Open Cookie as stored in memory */
59 struct tcp_fastopen_cookie {
60 s8 len;
61 u8 val[TCP_FASTOPEN_COOKIE_MAX];
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_cookie_values;
111 struct tcp_request_sock_ops;
112
113 struct tcp_request_sock {
114 struct inet_request_sock req;
115 #ifdef CONFIG_TCP_MD5SIG
116 /* Only used by TCP MD5 Signature so far. */
117 const struct tcp_request_sock_ops *af_specific;
118 #endif
119 struct sock *listener; /* needed for TFO */
120 u32 rcv_isn;
121 u32 snt_isn;
122 u32 snt_synack; /* synack sent time */
123 u32 rcv_nxt; /* the ack # by SYNACK. For
124 * FastOpen it's the seq#
125 * after data-in-SYN.
126 */
127 };
128
tcp_rsk(const struct request_sock * req)129 static inline struct tcp_request_sock *tcp_rsk(const struct request_sock *req)
130 {
131 return (struct tcp_request_sock *)req;
132 }
133
134 struct tcp_sock {
135 /* inet_connection_sock has to be the first member of tcp_sock */
136 struct inet_connection_sock inet_conn;
137 u16 tcp_header_len; /* Bytes of tcp header to send */
138 u16 xmit_size_goal_segs; /* Goal for segmenting output packets */
139
140 /*
141 * Header prediction flags
142 * 0x5?10 << 16 + snd_wnd in net byte order
143 */
144 __be32 pred_flags;
145
146 /*
147 * RFC793 variables by their proper names. This means you can
148 * read the code and the spec side by side (and laugh ...)
149 * See RFC793 and RFC1122. The RFC writes these in capitals.
150 */
151 u32 rcv_nxt; /* What we want to receive next */
152 u32 copied_seq; /* Head of yet unread data */
153 u32 rcv_wup; /* rcv_nxt on last window update sent */
154 u32 snd_nxt; /* Next sequence we send */
155
156 u32 snd_una; /* First byte we want an ack for */
157 u32 snd_sml; /* Last byte of the most recently transmitted small packet */
158 u32 rcv_tstamp; /* timestamp of last received ACK (for keepalives) */
159 u32 lsndtime; /* timestamp of last sent data packet (for restart window) */
160
161 u32 tsoffset; /* timestamp offset */
162
163 struct list_head tsq_node; /* anchor in tsq_tasklet.head list */
164 unsigned long tsq_flags;
165
166 /* Data for direct copy to user */
167 struct {
168 struct sk_buff_head prequeue;
169 struct task_struct *task;
170 struct iovec *iov;
171 int memory;
172 int len;
173 #ifdef CONFIG_NET_DMA
174 /* members for async copy */
175 struct dma_chan *dma_chan;
176 int wakeup;
177 struct dma_pinned_list *pinned_list;
178 dma_cookie_t dma_cookie;
179 #endif
180 } ucopy;
181
182 u32 snd_wl1; /* Sequence for window update */
183 u32 snd_wnd; /* The window we expect to receive */
184 u32 max_window; /* Maximal window ever seen from peer */
185 u32 mss_cache; /* Cached effective mss, not including SACKS */
186
187 u32 window_clamp; /* Maximal window to advertise */
188 u32 rcv_ssthresh; /* Current window clamp */
189
190 u16 advmss; /* Advertised MSS */
191 u8 unused;
192 u8 nonagle : 4,/* Disable Nagle algorithm? */
193 thin_lto : 1,/* Use linear timeouts for thin streams */
194 thin_dupack : 1,/* Fast retransmit on first dupack */
195 repair : 1,
196 frto : 1;/* F-RTO (RFC5682) activated in CA_Loss */
197 u8 repair_queue;
198 u8 do_early_retrans:1,/* Enable RFC5827 early-retransmit */
199 syn_data:1, /* SYN includes data */
200 syn_fastopen:1, /* SYN includes Fast Open option */
201 syn_data_acked:1;/* data in SYN is acked by SYN-ACK */
202 u32 tlp_high_seq; /* snd_nxt at the time of TLP retransmit. */
203
204 /* RTT measurement */
205 u32 srtt; /* smoothed round trip time << 3 */
206 u32 mdev; /* medium deviation */
207 u32 mdev_max; /* maximal mdev for the last rtt period */
208 u32 rttvar; /* smoothed mdev_max */
209 u32 rtt_seq; /* sequence number to update rttvar */
210
211 u32 packets_out; /* Packets which are "in flight" */
212 u32 retrans_out; /* Retransmitted packets out */
213
214 u16 urg_data; /* Saved octet of OOB data and control flags */
215 u8 ecn_flags; /* ECN status bits. */
216 u8 reordering; /* Packet reordering metric. */
217 u32 snd_up; /* Urgent pointer */
218
219 u8 keepalive_probes; /* num of allowed keep alive probes */
220 /*
221 * Options received (usually on last packet, some only on SYN packets).
222 */
223 struct tcp_options_received rx_opt;
224
225 /*
226 * Slow start and congestion control (see also Nagle, and Karn & Partridge)
227 */
228 u32 snd_ssthresh; /* Slow start size threshold */
229 u32 snd_cwnd; /* Sending congestion window */
230 u32 snd_cwnd_cnt; /* Linear increase counter */
231 u32 snd_cwnd_clamp; /* Do not allow snd_cwnd to grow above this */
232 u32 snd_cwnd_used;
233 u32 snd_cwnd_stamp;
234 u32 prior_cwnd; /* Congestion window at start of Recovery. */
235 u32 prr_delivered; /* Number of newly delivered packets to
236 * receiver in Recovery. */
237 u32 prr_out; /* Total number of pkts sent during Recovery. */
238
239 u32 rcv_wnd; /* Current receiver window */
240 u32 write_seq; /* Tail(+1) of data held in tcp send buffer */
241 u32 pushed_seq; /* Last pushed seq, required to talk to windows */
242 u32 lost_out; /* Lost packets */
243 u32 sacked_out; /* SACK'd packets */
244 u32 fackets_out; /* FACK'd packets */
245 u32 tso_deferred;
246
247 /* from STCP, retrans queue hinting */
248 struct sk_buff* lost_skb_hint;
249 struct sk_buff *scoreboard_skb_hint;
250 struct sk_buff *retransmit_skb_hint;
251
252 struct sk_buff_head out_of_order_queue; /* Out of order segments go here */
253
254 /* SACKs data, these 2 need to be together (see tcp_options_write) */
255 struct tcp_sack_block duplicate_sack[1]; /* D-SACK block */
256 struct tcp_sack_block selective_acks[4]; /* The SACKS themselves*/
257
258 struct tcp_sack_block recv_sack_cache[4];
259
260 struct sk_buff *highest_sack; /* skb just after the highest
261 * skb with SACKed bit set
262 * (validity guaranteed only if
263 * sacked_out > 0)
264 */
265
266 int lost_cnt_hint;
267 u32 retransmit_high; /* L-bits may be on up to this seqno */
268
269 u32 lost_retrans_low; /* Sent seq after any rxmit (lowest) */
270
271 u32 prior_ssthresh; /* ssthresh saved at recovery start */
272 u32 high_seq; /* snd_nxt at onset of congestion */
273
274 u32 retrans_stamp; /* Timestamp of the last retransmit,
275 * also used in SYN-SENT to remember stamp of
276 * the first SYN. */
277 u32 undo_marker; /* tracking retrans started here. */
278 int undo_retrans; /* number of undoable retransmissions. */
279 u32 total_retrans; /* Total retransmits for entire connection */
280
281 u32 urg_seq; /* Seq of received urgent pointer */
282 unsigned int keepalive_time; /* time before keep alive takes place */
283 unsigned int keepalive_intvl; /* time interval between keep alive probes */
284
285 int linger2;
286
287 /* Receiver side RTT estimation */
288 struct {
289 u32 rtt;
290 u32 seq;
291 u32 time;
292 } rcv_rtt_est;
293
294 /* Receiver queue space */
295 struct {
296 int space;
297 u32 seq;
298 u32 time;
299 } rcvq_space;
300
301 /* TCP-specific MTU probe information. */
302 struct {
303 u32 probe_seq_start;
304 u32 probe_seq_end;
305 } mtu_probe;
306 u32 mtu_info; /* We received an ICMP_FRAG_NEEDED / ICMPV6_PKT_TOOBIG
307 * while socket was owned by user.
308 */
309
310 #ifdef CONFIG_TCP_MD5SIG
311 /* TCP AF-Specific parts; only used by MD5 Signature support so far */
312 const struct tcp_sock_af_ops *af_specific;
313
314 /* TCP MD5 Signature Option information */
315 struct tcp_md5sig_info __rcu *md5sig_info;
316 #endif
317
318 /* TCP fastopen related information */
319 struct tcp_fastopen_request *fastopen_req;
320 /* fastopen_rsk points to request_sock that resulted in this big
321 * socket. Used to retransmit SYNACKs etc.
322 */
323 struct request_sock *fastopen_rsk;
324 };
325
326 enum tsq_flags {
327 TSQ_THROTTLED,
328 TSQ_QUEUED,
329 TCP_TSQ_DEFERRED, /* tcp_tasklet_func() found socket was owned */
330 TCP_WRITE_TIMER_DEFERRED, /* tcp_write_timer() found socket was owned */
331 TCP_DELACK_TIMER_DEFERRED, /* tcp_delack_timer() found socket was owned */
332 TCP_MTU_REDUCED_DEFERRED, /* tcp_v{4|6}_err() could not call
333 * tcp_v{4|6}_mtu_reduced()
334 */
335 };
336
tcp_sk(const struct sock * sk)337 static inline struct tcp_sock *tcp_sk(const struct sock *sk)
338 {
339 return (struct tcp_sock *)sk;
340 }
341
342 struct tcp_timewait_sock {
343 struct inet_timewait_sock tw_sk;
344 u32 tw_rcv_nxt;
345 u32 tw_snd_nxt;
346 u32 tw_rcv_wnd;
347 u32 tw_ts_offset;
348 u32 tw_ts_recent;
349 long tw_ts_recent_stamp;
350 #ifdef CONFIG_TCP_MD5SIG
351 struct tcp_md5sig_key *tw_md5_key;
352 #endif
353 };
354
tcp_twsk(const struct sock * sk)355 static inline struct tcp_timewait_sock *tcp_twsk(const struct sock *sk)
356 {
357 return (struct tcp_timewait_sock *)sk;
358 }
359
tcp_passive_fastopen(const struct sock * sk)360 static inline bool tcp_passive_fastopen(const struct sock *sk)
361 {
362 return (sk->sk_state == TCP_SYN_RECV &&
363 tcp_sk(sk)->fastopen_rsk != NULL);
364 }
365
fastopen_cookie_present(struct tcp_fastopen_cookie * foc)366 static inline bool fastopen_cookie_present(struct tcp_fastopen_cookie *foc)
367 {
368 return foc->len != -1;
369 }
370
371 extern void tcp_sock_destruct(struct sock *sk);
372
fastopen_init_queue(struct sock * sk,int backlog)373 static inline int fastopen_init_queue(struct sock *sk, int backlog)
374 {
375 struct request_sock_queue *queue =
376 &inet_csk(sk)->icsk_accept_queue;
377
378 if (queue->fastopenq == NULL) {
379 queue->fastopenq = kzalloc(
380 sizeof(struct fastopen_queue),
381 sk->sk_allocation);
382 if (queue->fastopenq == NULL)
383 return -ENOMEM;
384
385 sk->sk_destruct = tcp_sock_destruct;
386 spin_lock_init(&queue->fastopenq->lock);
387 }
388 queue->fastopenq->max_qlen = backlog;
389 return 0;
390 }
391
392 #endif /* _LINUX_TCP_H */
393