tcp.h 13 KB
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413
/*
 * INET		An implementation of the TCP/IP protocol suite for the LINUX
 *		operating system.  INET is implemented using the  BSD Socket
 *		interface as the means of communication with the user level.
 *
 *		Definitions for the TCP protocol.
 *
 * Version:	@(#)tcp.h	1.0.2	04/28/93
 *
 * Author:	Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
 *
 *		This program is free software; you can redistribute it and/or
 *		modify it under the terms of the GNU General Public License
 *		as published by the Free Software Foundation; either version
 *		2 of the License, or (at your option) any later version.
 */
#ifndef _LINUX_TCP_H
#define _LINUX_TCP_H


#include <linux/skbuff.h>
#include <net/sock.h>
#include <net/inet_connection_sock.h>
#include <net/inet_timewait_sock.h>
#include <uapi/linux/tcp.h>

static inline struct tcphdr *tcp_hdr(const struct sk_buff *skb)
{
	return (struct tcphdr *)skb_transport_header(skb);
}

static inline unsigned int tcp_hdrlen(const struct sk_buff *skb)
{
	return tcp_hdr(skb)->doff * 4;
}

static inline struct tcphdr *inner_tcp_hdr(const struct sk_buff *skb)
{
	return (struct tcphdr *)skb_inner_transport_header(skb);
}

static inline unsigned int inner_tcp_hdrlen(const struct sk_buff *skb)
{
	return inner_tcp_hdr(skb)->doff * 4;
}

static inline unsigned int tcp_optlen(const struct sk_buff *skb)
{
	return (tcp_hdr(skb)->doff - 5) * 4;
}

/* TCP Fast Open */
#define TCP_FASTOPEN_COOKIE_MIN	4	/* Min Fast Open Cookie size in bytes */
#define TCP_FASTOPEN_COOKIE_MAX	16	/* Max Fast Open Cookie size in bytes */
#define TCP_FASTOPEN_COOKIE_SIZE 8	/* the size employed by this impl. */

/* TCP Fast Open Cookie as stored in memory */
struct tcp_fastopen_cookie {
	s8	len;
	u8	val[TCP_FASTOPEN_COOKIE_MAX];
	bool	exp;	/* In RFC6994 experimental option format */
};

/* This defines a selective acknowledgement block. */
struct tcp_sack_block_wire {
	__be32	start_seq;
	__be32	end_seq;
};

struct tcp_sack_block {
	u32	start_seq;
	u32	end_seq;
};

/*These are used to set the sack_ok field in struct tcp_options_received */
#define TCP_SACK_SEEN     (1 << 0)   /*1 = peer is SACK capable, */
#define TCP_FACK_ENABLED  (1 << 1)   /*1 = FACK is enabled locally*/
#define TCP_DSACK_SEEN    (1 << 2)   /*1 = DSACK was received from peer*/

struct tcp_options_received {
/*	PAWS/RTTM data	*/
	long	ts_recent_stamp;/* Time we stored ts_recent (for aging) */
	u32	ts_recent;	/* Time stamp to echo next		*/
	u32	rcv_tsval;	/* Time stamp value             	*/
	u32	rcv_tsecr;	/* Time stamp echo reply        	*/
	u16 	saw_tstamp : 1,	/* Saw TIMESTAMP on last packet		*/
		tstamp_ok : 1,	/* TIMESTAMP seen on SYN packet		*/
		dsack : 1,	/* D-SACK is scheduled			*/
		wscale_ok : 1,	/* Wscale seen on SYN packet		*/
		sack_ok : 4,	/* SACK seen on SYN packet		*/
		snd_wscale : 4,	/* Window scaling received from sender	*/
		rcv_wscale : 4;	/* Window scaling to send to receiver	*/
	u8	num_sacks;	/* Number of SACK blocks		*/
	u16	user_mss;	/* mss requested by user in ioctl	*/
	u16	mss_clamp;	/* Maximal mss, negotiated at connection setup */
};

static inline void tcp_clear_options(struct tcp_options_received *rx_opt)
{
	rx_opt->tstamp_ok = rx_opt->sack_ok = 0;
	rx_opt->wscale_ok = rx_opt->snd_wscale = 0;
}

/* This is the max number of SACKS that we'll generate and process. It's safe
 * to increase this, although since:
 *   size = TCPOLEN_SACK_BASE_ALIGNED (4) + n * TCPOLEN_SACK_PERBLOCK (8)
 * only four options will fit in a standard TCP header */
#define TCP_NUM_SACKS 4

struct tcp_request_sock_ops;

struct tcp_request_sock {
	struct inet_request_sock 	req;
	const struct tcp_request_sock_ops *af_specific;
	struct skb_mstamp		snt_synack; /* first SYNACK sent time */
	bool				tfo_listener;
	u32				txhash;
	u32				rcv_isn;
	u32				snt_isn;
	u32				last_oow_ack_time; /* last SYNACK */
	u32				rcv_nxt; /* the ack # by SYNACK. For
						  * FastOpen it's the seq#
						  * after data-in-SYN.
						  */
};

static inline struct tcp_request_sock *tcp_rsk(const struct request_sock *req)
{
	return (struct tcp_request_sock *)req;
}

struct tcp_sock {
	/* inet_connection_sock has to be the first member of tcp_sock */
	struct inet_connection_sock	inet_conn;
	u16	tcp_header_len;	/* Bytes of tcp header to send		*/
	u16	gso_segs;	/* Max number of segs per GSO packet	*/

/*
 *	Header prediction flags
 *	0x5?10 << 16 + snd_wnd in net byte order
 */
	__be32	pred_flags;

/*
 *	RFC793 variables by their proper names. This means you can
 *	read the code and the spec side by side (and laugh ...)
 *	See RFC793 and RFC1122. The RFC writes these in capitals.
 */
	u64	bytes_received;	/* RFC4898 tcpEStatsAppHCThruOctetsReceived
				 * sum(delta(rcv_nxt)), or how many bytes
				 * were acked.
				 */
	u32	segs_in;	/* RFC4898 tcpEStatsPerfSegsIn
				 * total number of segments in.
				 */
 	u32	rcv_nxt;	/* What we want to receive next 	*/
	u32	copied_seq;	/* Head of yet unread data		*/
	u32	rcv_wup;	/* rcv_nxt on last window update sent	*/
 	u32	snd_nxt;	/* Next sequence we send		*/
	u32	segs_out;	/* RFC4898 tcpEStatsPerfSegsOut
				 * The total number of segments sent.
				 */
	u64	bytes_acked;	/* RFC4898 tcpEStatsAppHCThruOctetsAcked
				 * sum(delta(snd_una)), or how many bytes
				 * were acked.
				 */
	struct u64_stats_sync syncp; /* protects 64bit vars (cf tcp_get_info()) */

 	u32	snd_una;	/* First byte we want an ack for	*/
 	u32	snd_sml;	/* Last byte of the most recently transmitted small packet */
	u32	rcv_tstamp;	/* timestamp of last received ACK (for keepalives) */
	u32	lsndtime;	/* timestamp of last sent data packet (for restart window) */
	u32	last_oow_ack_time;  /* timestamp of last out-of-window ACK */

	u32	tsoffset;	/* timestamp offset */

	struct list_head tsq_node; /* anchor in tsq_tasklet.head list */
	unsigned long	tsq_flags;

	/* Data for direct copy to user */
	struct {
		struct sk_buff_head	prequeue;
		struct task_struct	*task;
		struct msghdr		*msg;
		int			memory;
		int			len;
	} ucopy;

	u32	snd_wl1;	/* Sequence for window update		*/
	u32	snd_wnd;	/* The window we expect to receive	*/
	u32	max_window;	/* Maximal window ever seen from peer	*/
	u32	mss_cache;	/* Cached effective mss, not including SACKS */

	u32	window_clamp;	/* Maximal window to advertise		*/
	u32	rcv_ssthresh;	/* Current window clamp			*/

	/* Information of the most recently (s)acked skb */
	struct tcp_rack {
		struct skb_mstamp mstamp; /* (Re)sent time of the skb */
		u8 advanced; /* mstamp advanced since last lost marking */
		u8 reord;    /* reordering detected */
	} rack;
	u16	advmss;		/* Advertised MSS			*/
	u8	unused;
	u8	nonagle     : 4,/* Disable Nagle algorithm?             */
		thin_lto    : 1,/* Use linear timeouts for thin streams */
		thin_dupack : 1,/* Fast retransmit on first dupack      */
		repair      : 1,
		frto        : 1;/* F-RTO (RFC5682) activated in CA_Loss */
	u8	repair_queue;
	u8	do_early_retrans:1,/* Enable RFC5827 early-retransmit  */
		syn_data:1,	/* SYN includes data */
		syn_fastopen:1,	/* SYN includes Fast Open option */
		syn_fastopen_exp:1,/* SYN includes Fast Open exp. option */
		syn_data_acked:1,/* data in SYN is acked by SYN-ACK */
		save_syn:1,	/* Save headers of SYN packet */
		is_cwnd_limited:1;/* forward progress limited by snd_cwnd? */
	u32	tlp_high_seq;	/* snd_nxt at the time of TLP retransmit. */

/* RTT measurement */
	u32	srtt_us;	/* smoothed round trip time << 3 in usecs */
	u32	mdev_us;	/* medium deviation			*/
	u32	mdev_max_us;	/* maximal mdev for the last rtt period	*/
	u32	rttvar_us;	/* smoothed mdev_max			*/
	u32	rtt_seq;	/* sequence number to update rttvar	*/
	struct rtt_meas {
		u32 rtt, ts;	/* RTT in usec and sampling time in jiffies. */
	} rtt_min[3];

	u32	packets_out;	/* Packets which are "in flight"	*/
	u32	retrans_out;	/* Retransmitted packets out		*/
	u32	max_packets_out;  /* max packets_out in last window */
	u32	max_packets_seq;  /* right edge of max_packets_out flight */

	u16	urg_data;	/* Saved octet of OOB data and control flags */
	u8	ecn_flags;	/* ECN status bits.			*/
	u8	keepalive_probes; /* num of allowed keep alive probes	*/
	u32	reordering;	/* Packet reordering metric.		*/
	u32	snd_up;		/* Urgent pointer		*/

/*
 *      Options received (usually on last packet, some only on SYN packets).
 */
	struct tcp_options_received rx_opt;

/*
 *	Slow start and congestion control (see also Nagle, and Karn & Partridge)
 */
 	u32	snd_ssthresh;	/* Slow start size threshold		*/
 	u32	snd_cwnd;	/* Sending congestion window		*/
	u32	snd_cwnd_cnt;	/* Linear increase counter		*/
	u32	snd_cwnd_clamp; /* Do not allow snd_cwnd to grow above this */
	u32	snd_cwnd_used;
	u32	snd_cwnd_stamp;
	u32	prior_cwnd;	/* Congestion window at start of Recovery. */
	u32	prr_delivered;	/* Number of newly delivered packets to
				 * receiver in Recovery. */
	u32	prr_out;	/* Total number of pkts sent during Recovery. */

 	u32	rcv_wnd;	/* Current receiver window		*/
	u32	write_seq;	/* Tail(+1) of data held in tcp send buffer */
	u32	notsent_lowat;	/* TCP_NOTSENT_LOWAT */
	u32	pushed_seq;	/* Last pushed seq, required to talk to windows */
	u32	lost_out;	/* Lost packets			*/
	u32	sacked_out;	/* SACK'd packets			*/
	u32	fackets_out;	/* FACK'd packets			*/

	/* from STCP, retrans queue hinting */
	struct sk_buff* lost_skb_hint;
	struct sk_buff *retransmit_skb_hint;

	/* OOO segments go in this list. Note that socket lock must be held,
	 * as we do not use sk_buff_head lock.
	 */
	struct sk_buff_head	out_of_order_queue;

	/* SACKs data, these 2 need to be together (see tcp_options_write) */
	struct tcp_sack_block duplicate_sack[1]; /* D-SACK block */
	struct tcp_sack_block selective_acks[4]; /* The SACKS themselves*/

	struct tcp_sack_block recv_sack_cache[4];

	struct sk_buff *highest_sack;   /* skb just after the highest
					 * skb with SACKed bit set
					 * (validity guaranteed only if
					 * sacked_out > 0)
					 */

	int     lost_cnt_hint;
	u32     retransmit_high;	/* L-bits may be on up to this seqno */

	u32	prior_ssthresh; /* ssthresh saved at recovery start	*/
	u32	high_seq;	/* snd_nxt at onset of congestion	*/

	u32	retrans_stamp;	/* Timestamp of the last retransmit,
				 * also used in SYN-SENT to remember stamp of
				 * the first SYN. */
	u32	undo_marker;	/* snd_una upon a new recovery episode. */
	int	undo_retrans;	/* number of undoable retransmissions. */
	u32	total_retrans;	/* Total retransmits for entire connection */

	u32	urg_seq;	/* Seq of received urgent pointer */
	unsigned int		keepalive_time;	  /* time before keep alive takes place */
	unsigned int		keepalive_intvl;  /* time interval between keep alive probes */

	int			linger2;

/* Receiver side RTT estimation */
	struct {
		u32	rtt;
		u32	seq;
		u32	time;
	} rcv_rtt_est;

/* Receiver queue space */
	struct {
		int	space;
		u32	seq;
		u32	time;
	} rcvq_space;

/* TCP-specific MTU probe information. */
	struct {
		u32		  probe_seq_start;
		u32		  probe_seq_end;
	} mtu_probe;
	u32	mtu_info; /* We received an ICMP_FRAG_NEEDED / ICMPV6_PKT_TOOBIG
			   * while socket was owned by user.
			   */

#ifdef CONFIG_TCP_MD5SIG
/* TCP AF-Specific parts; only used by MD5 Signature support so far */
	const struct tcp_sock_af_ops	*af_specific;

/* TCP MD5 Signature Option information */
	struct tcp_md5sig_info	__rcu *md5sig_info;
#endif

/* TCP fastopen related information */
	struct tcp_fastopen_request *fastopen_req;
	/* fastopen_rsk points to request_sock that resulted in this big
	 * socket. Used to retransmit SYNACKs etc.
	 */
	struct request_sock *fastopen_rsk;
	u32	*saved_syn;
};

enum tsq_flags {
	TSQ_THROTTLED,
	TSQ_QUEUED,
	TCP_TSQ_DEFERRED,	   /* tcp_tasklet_func() found socket was owned */
	TCP_WRITE_TIMER_DEFERRED,  /* tcp_write_timer() found socket was owned */
	TCP_DELACK_TIMER_DEFERRED, /* tcp_delack_timer() found socket was owned */
	TCP_MTU_REDUCED_DEFERRED,  /* tcp_v{4|6}_err() could not call
				    * tcp_v{4|6}_mtu_reduced()
				    */
};

static inline struct tcp_sock *tcp_sk(const struct sock *sk)
{
	return (struct tcp_sock *)sk;
}

struct tcp_timewait_sock {
	struct inet_timewait_sock tw_sk;
#define tw_rcv_nxt tw_sk.__tw_common.skc_tw_rcv_nxt
#define tw_snd_nxt tw_sk.__tw_common.skc_tw_snd_nxt
	u32			  tw_rcv_wnd;
	u32			  tw_ts_offset;
	u32			  tw_ts_recent;

	/* The time we sent the last out-of-window ACK: */
	u32			  tw_last_oow_ack_time;

	long			  tw_ts_recent_stamp;
#ifdef CONFIG_TCP_MD5SIG
	struct tcp_md5sig_key	  *tw_md5_key;
#endif
};

static inline struct tcp_timewait_sock *tcp_twsk(const struct sock *sk)
{
	return (struct tcp_timewait_sock *)sk;
}

static inline bool tcp_passive_fastopen(const struct sock *sk)
{
	return (sk->sk_state == TCP_SYN_RECV &&
		tcp_sk(sk)->fastopen_rsk != NULL);
}

static inline void fastopen_queue_tune(struct sock *sk, int backlog)
{
	struct request_sock_queue *queue = &inet_csk(sk)->icsk_accept_queue;
	int somaxconn = READ_ONCE(sock_net(sk)->core.sysctl_somaxconn);

	queue->fastopenq.max_qlen = min_t(unsigned int, backlog, somaxconn);
}

static inline void tcp_move_syn(struct tcp_sock *tp,
				struct request_sock *req)
{
	tp->saved_syn = req->saved_syn;
	req->saved_syn = NULL;
}

static inline void tcp_saved_syn_free(struct tcp_sock *tp)
{
	kfree(tp->saved_syn);
	tp->saved_syn = NULL;
}

#endif	/* _LINUX_TCP_H */