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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