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 #include <linux/types.h>
21 #include <asm/byteorder.h>
22 #include <linux/socket.h>
23 
24 struct tcphdr {
25 	__be16	source;
26 	__be16	dest;
27 	__be32	seq;
28 	__be32	ack_seq;
29 #if defined(__LITTLE_ENDIAN_BITFIELD)
30 	__u16	res1:4,
31 		doff:4,
32 		fin:1,
33 		syn:1,
34 		rst:1,
35 		psh:1,
36 		ack:1,
37 		urg:1,
38 		ece:1,
39 		cwr:1;
40 #elif defined(__BIG_ENDIAN_BITFIELD)
41 	__u16	doff:4,
42 		res1:4,
43 		cwr:1,
44 		ece:1,
45 		urg:1,
46 		ack:1,
47 		psh:1,
48 		rst:1,
49 		syn:1,
50 		fin:1;
51 #else
52 #error	"Adjust your <asm/byteorder.h> defines"
53 #endif
54 	__be16	window;
55 	__sum16	check;
56 	__be16	urg_ptr;
57 };
58 
59 /*
60  *	The union cast uses a gcc extension to avoid aliasing problems
61  *  (union is compatible to any of its members)
62  *  This means this part of the code is -fstrict-aliasing safe now.
63  */
64 union tcp_word_hdr {
65 	struct tcphdr hdr;
66 	__be32 		  words[5];
67 };
68 
69 #define tcp_flag_word(tp) ( ((union tcp_word_hdr *)(tp))->words [3])
70 
71 enum {
72 	TCP_FLAG_CWR = __cpu_to_be32(0x00800000),
73 	TCP_FLAG_ECE = __cpu_to_be32(0x00400000),
74 	TCP_FLAG_URG = __cpu_to_be32(0x00200000),
75 	TCP_FLAG_ACK = __cpu_to_be32(0x00100000),
76 	TCP_FLAG_PSH = __cpu_to_be32(0x00080000),
77 	TCP_FLAG_RST = __cpu_to_be32(0x00040000),
78 	TCP_FLAG_SYN = __cpu_to_be32(0x00020000),
79 	TCP_FLAG_FIN = __cpu_to_be32(0x00010000),
80 	TCP_RESERVED_BITS = __cpu_to_be32(0x0F000000),
81 	TCP_DATA_OFFSET = __cpu_to_be32(0xF0000000)
82 };
83 
84 /*
85  * TCP general constants
86  */
87 #define TCP_MSS_DEFAULT		 536U	/* IPv4 (RFC1122, RFC2581) */
88 #define TCP_MSS_DESIRED		1220U	/* IPv6 (tunneled), EDNS0 (RFC3226) */
89 
90 /* TCP socket options */
91 #define TCP_NODELAY		1	/* Turn off Nagle's algorithm. */
92 #define TCP_MAXSEG		2	/* Limit MSS */
93 #define TCP_CORK		3	/* Never send partially complete segments */
94 #define TCP_KEEPIDLE		4	/* Start keeplives after this period */
95 #define TCP_KEEPINTVL		5	/* Interval between keepalives */
96 #define TCP_KEEPCNT		6	/* Number of keepalives before death */
97 #define TCP_SYNCNT		7	/* Number of SYN retransmits */
98 #define TCP_LINGER2		8	/* Life time of orphaned FIN-WAIT-2 state */
99 #define TCP_DEFER_ACCEPT	9	/* Wake up listener only when data arrive */
100 #define TCP_WINDOW_CLAMP	10	/* Bound advertised window */
101 #define TCP_INFO		11	/* Information about this connection. */
102 #define TCP_QUICKACK		12	/* Block/reenable quick acks */
103 #define TCP_CONGESTION		13	/* Congestion control algorithm */
104 #define TCP_MD5SIG		14	/* TCP MD5 Signature (RFC2385) */
105 #define TCP_COOKIE_TRANSACTIONS	15	/* TCP Cookie Transactions */
106 #define TCP_THIN_LINEAR_TIMEOUTS 16      /* Use linear timeouts for thin streams*/
107 #define TCP_THIN_DUPACK         17      /* Fast retrans. after 1 dupack */
108 #define TCP_USER_TIMEOUT	18	/* How long for loss retry before timeout */
109 
110 /* for TCP_INFO socket option */
111 #define TCPI_OPT_TIMESTAMPS	1
112 #define TCPI_OPT_SACK		2
113 #define TCPI_OPT_WSCALE		4
114 #define TCPI_OPT_ECN		8 /* ECN was negociated at TCP session init */
115 #define TCPI_OPT_ECN_SEEN	16 /* we received at least one packet with ECT */
116 
117 enum tcp_ca_state {
118 	TCP_CA_Open = 0,
119 #define TCPF_CA_Open	(1<<TCP_CA_Open)
120 	TCP_CA_Disorder = 1,
121 #define TCPF_CA_Disorder (1<<TCP_CA_Disorder)
122 	TCP_CA_CWR = 2,
123 #define TCPF_CA_CWR	(1<<TCP_CA_CWR)
124 	TCP_CA_Recovery = 3,
125 #define TCPF_CA_Recovery (1<<TCP_CA_Recovery)
126 	TCP_CA_Loss = 4
127 #define TCPF_CA_Loss	(1<<TCP_CA_Loss)
128 };
129 
130 struct tcp_info {
131 	__u8	tcpi_state;
132 	__u8	tcpi_ca_state;
133 	__u8	tcpi_retransmits;
134 	__u8	tcpi_probes;
135 	__u8	tcpi_backoff;
136 	__u8	tcpi_options;
137 	__u8	tcpi_snd_wscale : 4, tcpi_rcv_wscale : 4;
138 
139 	__u32	tcpi_rto;
140 	__u32	tcpi_ato;
141 	__u32	tcpi_snd_mss;
142 	__u32	tcpi_rcv_mss;
143 
144 	__u32	tcpi_unacked;
145 	__u32	tcpi_sacked;
146 	__u32	tcpi_lost;
147 	__u32	tcpi_retrans;
148 	__u32	tcpi_fackets;
149 
150 	/* Times. */
151 	__u32	tcpi_last_data_sent;
152 	__u32	tcpi_last_ack_sent;     /* Not remembered, sorry. */
153 	__u32	tcpi_last_data_recv;
154 	__u32	tcpi_last_ack_recv;
155 
156 	/* Metrics. */
157 	__u32	tcpi_pmtu;
158 	__u32	tcpi_rcv_ssthresh;
159 	__u32	tcpi_rtt;
160 	__u32	tcpi_rttvar;
161 	__u32	tcpi_snd_ssthresh;
162 	__u32	tcpi_snd_cwnd;
163 	__u32	tcpi_advmss;
164 	__u32	tcpi_reordering;
165 
166 	__u32	tcpi_rcv_rtt;
167 	__u32	tcpi_rcv_space;
168 
169 	__u32	tcpi_total_retrans;
170 };
171 
172 /* for TCP_MD5SIG socket option */
173 #define TCP_MD5SIG_MAXKEYLEN	80
174 
175 struct tcp_md5sig {
176 	struct __kernel_sockaddr_storage tcpm_addr;	/* address associated */
177 	__u16	__tcpm_pad1;				/* zero */
178 	__u16	tcpm_keylen;				/* key length */
179 	__u32	__tcpm_pad2;				/* zero */
180 	__u8	tcpm_key[TCP_MD5SIG_MAXKEYLEN];		/* key (binary) */
181 };
182 
183 /* for TCP_COOKIE_TRANSACTIONS (TCPCT) socket option */
184 #define TCP_COOKIE_MIN		 8		/*  64-bits */
185 #define TCP_COOKIE_MAX		16		/* 128-bits */
186 #define TCP_COOKIE_PAIR_SIZE	(2*TCP_COOKIE_MAX)
187 
188 /* Flags for both getsockopt and setsockopt */
189 #define TCP_COOKIE_IN_ALWAYS	(1 << 0)	/* Discard SYN without cookie */
190 #define TCP_COOKIE_OUT_NEVER	(1 << 1)	/* Prohibit outgoing cookies,
191 						 * supercedes everything. */
192 
193 /* Flags for getsockopt */
194 #define TCP_S_DATA_IN		(1 << 2)	/* Was data received? */
195 #define TCP_S_DATA_OUT		(1 << 3)	/* Was data sent? */
196 
197 /* TCP_COOKIE_TRANSACTIONS data */
198 struct tcp_cookie_transactions {
199 	__u16	tcpct_flags;			/* see above */
200 	__u8	__tcpct_pad1;			/* zero */
201 	__u8	tcpct_cookie_desired;		/* bytes */
202 	__u16	tcpct_s_data_desired;		/* bytes of variable data */
203 	__u16	tcpct_used;			/* bytes in value */
204 	__u8	tcpct_value[TCP_MSS_DEFAULT];
205 };
206 
207 #ifdef __KERNEL__
208 
209 #include <linux/skbuff.h>
210 #include <linux/dmaengine.h>
211 #include <net/sock.h>
212 #include <net/inet_connection_sock.h>
213 #include <net/inet_timewait_sock.h>
214 
tcp_hdr(const struct sk_buff * skb)215 static inline struct tcphdr *tcp_hdr(const struct sk_buff *skb)
216 {
217 	return (struct tcphdr *)skb_transport_header(skb);
218 }
219 
tcp_hdrlen(const struct sk_buff * skb)220 static inline unsigned int tcp_hdrlen(const struct sk_buff *skb)
221 {
222 	return tcp_hdr(skb)->doff * 4;
223 }
224 
tcp_optlen(const struct sk_buff * skb)225 static inline unsigned int tcp_optlen(const struct sk_buff *skb)
226 {
227 	return (tcp_hdr(skb)->doff - 5) * 4;
228 }
229 
230 /* This defines a selective acknowledgement block. */
231 struct tcp_sack_block_wire {
232 	__be32	start_seq;
233 	__be32	end_seq;
234 };
235 
236 struct tcp_sack_block {
237 	u32	start_seq;
238 	u32	end_seq;
239 };
240 
241 /*These are used to set the sack_ok field in struct tcp_options_received */
242 #define TCP_SACK_SEEN     (1 << 0)   /*1 = peer is SACK capable, */
243 #define TCP_FACK_ENABLED  (1 << 1)   /*1 = FACK is enabled locally*/
244 #define TCP_DSACK_SEEN    (1 << 2)   /*1 = DSACK was received from peer*/
245 
246 struct tcp_options_received {
247 /*	PAWS/RTTM data	*/
248 	long	ts_recent_stamp;/* Time we stored ts_recent (for aging) */
249 	u32	ts_recent;	/* Time stamp to echo next		*/
250 	u32	rcv_tsval;	/* Time stamp value             	*/
251 	u32	rcv_tsecr;	/* Time stamp echo reply        	*/
252 	u16 	saw_tstamp : 1,	/* Saw TIMESTAMP on last packet		*/
253 		tstamp_ok : 1,	/* TIMESTAMP seen on SYN packet		*/
254 		dsack : 1,	/* D-SACK is scheduled			*/
255 		wscale_ok : 1,	/* Wscale seen on SYN packet		*/
256 		sack_ok : 4,	/* SACK seen on SYN packet		*/
257 		snd_wscale : 4,	/* Window scaling received from sender	*/
258 		rcv_wscale : 4;	/* Window scaling to send to receiver	*/
259 	u8	cookie_plus:6,	/* bytes in authenticator/cookie option	*/
260 		cookie_out_never:1,
261 		cookie_in_always:1;
262 	u8	num_sacks;	/* Number of SACK blocks		*/
263 	u16	user_mss;	/* mss requested by user in ioctl	*/
264 	u16	mss_clamp;	/* Maximal mss, negotiated at connection setup */
265 };
266 
tcp_clear_options(struct tcp_options_received * rx_opt)267 static inline void tcp_clear_options(struct tcp_options_received *rx_opt)
268 {
269 	rx_opt->tstamp_ok = rx_opt->sack_ok = 0;
270 	rx_opt->wscale_ok = rx_opt->snd_wscale = 0;
271 	rx_opt->cookie_plus = 0;
272 }
273 
274 /* This is the max number of SACKS that we'll generate and process. It's safe
275  * to increase this, although since:
276  *   size = TCPOLEN_SACK_BASE_ALIGNED (4) + n * TCPOLEN_SACK_PERBLOCK (8)
277  * only four options will fit in a standard TCP header */
278 #define TCP_NUM_SACKS 4
279 
280 struct tcp_cookie_values;
281 struct tcp_request_sock_ops;
282 
283 struct tcp_request_sock {
284 	struct inet_request_sock 	req;
285 #ifdef CONFIG_TCP_MD5SIG
286 	/* Only used by TCP MD5 Signature so far. */
287 	const struct tcp_request_sock_ops *af_specific;
288 #endif
289 	u32				rcv_isn;
290 	u32				snt_isn;
291 	u32				snt_synack; /* synack sent time */
292 };
293 
tcp_rsk(const struct request_sock * req)294 static inline struct tcp_request_sock *tcp_rsk(const struct request_sock *req)
295 {
296 	return (struct tcp_request_sock *)req;
297 }
298 
299 struct tcp_sock {
300 	/* inet_connection_sock has to be the first member of tcp_sock */
301 	struct inet_connection_sock	inet_conn;
302 	u16	tcp_header_len;	/* Bytes of tcp header to send		*/
303 	u16	xmit_size_goal_segs; /* Goal for segmenting output packets */
304 
305 /*
306  *	Header prediction flags
307  *	0x5?10 << 16 + snd_wnd in net byte order
308  */
309 	__be32	pred_flags;
310 
311 /*
312  *	RFC793 variables by their proper names. This means you can
313  *	read the code and the spec side by side (and laugh ...)
314  *	See RFC793 and RFC1122. The RFC writes these in capitals.
315  */
316  	u32	rcv_nxt;	/* What we want to receive next 	*/
317 	u32	copied_seq;	/* Head of yet unread data		*/
318 	u32	rcv_wup;	/* rcv_nxt on last window update sent	*/
319  	u32	snd_nxt;	/* Next sequence we send		*/
320 
321  	u32	snd_una;	/* First byte we want an ack for	*/
322  	u32	snd_sml;	/* Last byte of the most recently transmitted small packet */
323 	u32	rcv_tstamp;	/* timestamp of last received ACK (for keepalives) */
324 	u32	lsndtime;	/* timestamp of last sent data packet (for restart window) */
325 
326 	/* Data for direct copy to user */
327 	struct {
328 		struct sk_buff_head	prequeue;
329 		struct task_struct	*task;
330 		struct iovec		*iov;
331 		int			memory;
332 		int			len;
333 #ifdef CONFIG_NET_DMA
334 		/* members for async copy */
335 		struct dma_chan		*dma_chan;
336 		int			wakeup;
337 		struct dma_pinned_list	*pinned_list;
338 		dma_cookie_t		dma_cookie;
339 #endif
340 	} ucopy;
341 
342 	u32	snd_wl1;	/* Sequence for window update		*/
343 	u32	snd_wnd;	/* The window we expect to receive	*/
344 	u32	max_window;	/* Maximal window ever seen from peer	*/
345 	u32	mss_cache;	/* Cached effective mss, not including SACKS */
346 
347 	u32	window_clamp;	/* Maximal window to advertise		*/
348 	u32	rcv_ssthresh;	/* Current window clamp			*/
349 
350 	u32	frto_highmark;	/* snd_nxt when RTO occurred */
351 	u16	advmss;		/* Advertised MSS			*/
352 	u8	frto_counter;	/* Number of new acks after RTO */
353 	u8	nonagle     : 4,/* Disable Nagle algorithm?             */
354 		thin_lto    : 1,/* Use linear timeouts for thin streams */
355 		thin_dupack : 1,/* Fast retransmit on first dupack      */
356 		unused      : 2;
357 
358 /* RTT measurement */
359 	u32	srtt;		/* smoothed round trip time << 3	*/
360 	u32	mdev;		/* medium deviation			*/
361 	u32	mdev_max;	/* maximal mdev for the last rtt period	*/
362 	u32	rttvar;		/* smoothed mdev_max			*/
363 	u32	rtt_seq;	/* sequence number to update rttvar	*/
364 
365 	u32	packets_out;	/* Packets which are "in flight"	*/
366 	u32	retrans_out;	/* Retransmitted packets out		*/
367 
368 	u16	urg_data;	/* Saved octet of OOB data and control flags */
369 	u8	ecn_flags;	/* ECN status bits.			*/
370 	u8	reordering;	/* Packet reordering metric.		*/
371 	u32	snd_up;		/* Urgent pointer		*/
372 
373 	u8	keepalive_probes; /* num of allowed keep alive probes	*/
374 /*
375  *      Options received (usually on last packet, some only on SYN packets).
376  */
377 	struct tcp_options_received rx_opt;
378 
379 /*
380  *	Slow start and congestion control (see also Nagle, and Karn & Partridge)
381  */
382  	u32	snd_ssthresh;	/* Slow start size threshold		*/
383  	u32	snd_cwnd;	/* Sending congestion window		*/
384 	u32	snd_cwnd_cnt;	/* Linear increase counter		*/
385 	u32	snd_cwnd_clamp; /* Do not allow snd_cwnd to grow above this */
386 	u32	snd_cwnd_used;
387 	u32	snd_cwnd_stamp;
388 	u32	prior_cwnd;	/* Congestion window at start of Recovery. */
389 	u32	prr_delivered;	/* Number of newly delivered packets to
390 				 * receiver in Recovery. */
391 	u32	prr_out;	/* Total number of pkts sent during Recovery. */
392 
393  	u32	rcv_wnd;	/* Current receiver window		*/
394 	u32	write_seq;	/* Tail(+1) of data held in tcp send buffer */
395 	u32	pushed_seq;	/* Last pushed seq, required to talk to windows */
396 	u32	lost_out;	/* Lost packets			*/
397 	u32	sacked_out;	/* SACK'd packets			*/
398 	u32	fackets_out;	/* FACK'd packets			*/
399 	u32	tso_deferred;
400 	u32	bytes_acked;	/* Appropriate Byte Counting - RFC3465 */
401 
402 	/* from STCP, retrans queue hinting */
403 	struct sk_buff* lost_skb_hint;
404 	struct sk_buff *scoreboard_skb_hint;
405 	struct sk_buff *retransmit_skb_hint;
406 
407 	struct sk_buff_head	out_of_order_queue; /* Out of order segments go here */
408 
409 	/* SACKs data, these 2 need to be together (see tcp_build_and_update_options) */
410 	struct tcp_sack_block duplicate_sack[1]; /* D-SACK block */
411 	struct tcp_sack_block selective_acks[4]; /* The SACKS themselves*/
412 
413 	struct tcp_sack_block recv_sack_cache[4];
414 
415 	struct sk_buff *highest_sack;   /* skb just after the highest
416 					 * skb with SACKed bit set
417 					 * (validity guaranteed only if
418 					 * sacked_out > 0)
419 					 */
420 
421 	int     lost_cnt_hint;
422 	u32     retransmit_high;	/* L-bits may be on up to this seqno */
423 
424 	u32	lost_retrans_low;	/* Sent seq after any rxmit (lowest) */
425 
426 	u32	prior_ssthresh; /* ssthresh saved at recovery start	*/
427 	u32	high_seq;	/* snd_nxt at onset of congestion	*/
428 
429 	u32	retrans_stamp;	/* Timestamp of the last retransmit,
430 				 * also used in SYN-SENT to remember stamp of
431 				 * the first SYN. */
432 	u32	undo_marker;	/* tracking retrans started here. */
433 	int	undo_retrans;	/* number of undoable retransmissions. */
434 	u32	total_retrans;	/* Total retransmits for entire connection */
435 
436 	u32	urg_seq;	/* Seq of received urgent pointer */
437 	unsigned int		keepalive_time;	  /* time before keep alive takes place */
438 	unsigned int		keepalive_intvl;  /* time interval between keep alive probes */
439 
440 	int			linger2;
441 
442 /* Receiver side RTT estimation */
443 	struct {
444 		u32	rtt;
445 		u32	seq;
446 		u32	time;
447 	} rcv_rtt_est;
448 
449 /* Receiver queue space */
450 	struct {
451 		int	space;
452 		u32	seq;
453 		u32	time;
454 	} rcvq_space;
455 
456 /* TCP-specific MTU probe information. */
457 	struct {
458 		u32		  probe_seq_start;
459 		u32		  probe_seq_end;
460 	} mtu_probe;
461 
462 #ifdef CONFIG_TCP_MD5SIG
463 /* TCP AF-Specific parts; only used by MD5 Signature support so far */
464 	const struct tcp_sock_af_ops	*af_specific;
465 
466 /* TCP MD5 Signature Option information */
467 	struct tcp_md5sig_info	__rcu *md5sig_info;
468 #endif
469 
470 	/* When the cookie options are generated and exchanged, then this
471 	 * object holds a reference to them (cookie_values->kref).  Also
472 	 * contains related tcp_cookie_transactions fields.
473 	 */
474 	struct tcp_cookie_values  *cookie_values;
475 };
476 
tcp_sk(const struct sock * sk)477 static inline struct tcp_sock *tcp_sk(const struct sock *sk)
478 {
479 	return (struct tcp_sock *)sk;
480 }
481 
482 struct tcp_timewait_sock {
483 	struct inet_timewait_sock tw_sk;
484 	u32			  tw_rcv_nxt;
485 	u32			  tw_snd_nxt;
486 	u32			  tw_rcv_wnd;
487 	u32			  tw_ts_recent;
488 	long			  tw_ts_recent_stamp;
489 #ifdef CONFIG_TCP_MD5SIG
490 	struct tcp_md5sig_key	*tw_md5_key;
491 #endif
492 	/* Few sockets in timewait have cookies; in that case, then this
493 	 * object holds a reference to them (tw_cookie_values->kref).
494 	 */
495 	struct tcp_cookie_values  *tw_cookie_values;
496 };
497 
tcp_twsk(const struct sock * sk)498 static inline struct tcp_timewait_sock *tcp_twsk(const struct sock *sk)
499 {
500 	return (struct tcp_timewait_sock *)sk;
501 }
502 
503 #endif	/* __KERNEL__ */
504 
505 #endif	/* _LINUX_TCP_H */
506