tcp.h 50.5 KB
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/*
 * 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 module.
 *
 * Version:	@(#)tcp.h	1.0.5	05/23/93
 *
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 * Authors:	Ross Biro
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 *		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 _TCP_H
#define _TCP_H

#define FASTRETRANS_DEBUG 1

#include <linux/list.h>
#include <linux/tcp.h>
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#include <linux/bug.h>
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#include <linux/slab.h>
#include <linux/cache.h>
#include <linux/percpu.h>
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#include <linux/skbuff.h>
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#include <linux/dmaengine.h>
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#include <linux/crypto.h>
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#include <linux/cryptohash.h>
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#include <linux/kref.h>
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#include <net/inet_connection_sock.h>
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#include <net/inet_timewait_sock.h>
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#include <net/inet_hashtables.h>
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#include <net/checksum.h>
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#include <net/request_sock.h>
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#include <net/sock.h>
#include <net/snmp.h>
#include <net/ip.h>
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#include <net/tcp_states.h>
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#include <net/inet_ecn.h>
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#include <net/dst.h>
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#include <linux/seq_file.h>
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#include <linux/memcontrol.h>
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extern struct inet_hashinfo tcp_hashinfo;
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extern struct percpu_counter tcp_orphan_count;
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extern void tcp_time_wait(struct sock *sk, int state, int timeo);

#define MAX_TCP_HEADER	(128 + MAX_HEADER)
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#define MAX_TCP_OPTION_SPACE 40
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/* 
 * Never offer a window over 32767 without using window scaling. Some
 * poor stacks do signed 16bit maths! 
 */
#define MAX_TCP_WINDOW		32767U

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/* Offer an initial receive window of 10 mss. */
#define TCP_DEFAULT_INIT_RCVWND	10

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/* Minimal accepted MSS. It is (60+60+8) - (20+20). */
#define TCP_MIN_MSS		88U

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/* The least MTU to use for probing */
#define TCP_BASE_MSS		512

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/* After receiving this amount of duplicate ACKs fast retransmit starts. */
#define TCP_FASTRETRANS_THRESH 3

/* Maximal reordering. */
#define TCP_MAX_REORDERING	127

/* Maximal number of ACKs sent quickly to accelerate slow-start. */
#define TCP_MAX_QUICKACKS	16U

/* urg_data states */
#define TCP_URG_VALID	0x0100
#define TCP_URG_NOTYET	0x0200
#define TCP_URG_READ	0x0400

#define TCP_RETR1	3	/*
				 * This is how many retries it does before it
				 * tries to figure out if the gateway is
				 * down. Minimal RFC value is 3; it corresponds
				 * to ~3sec-8min depending on RTO.
				 */

#define TCP_RETR2	15	/*
				 * This should take at least
				 * 90 minutes to time out.
				 * RFC1122 says that the limit is 100 sec.
				 * 15 is ~13-30min depending on RTO.
				 */

#define TCP_SYN_RETRIES	 5	/* number of times to retry active opening a
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				 * connection: ~180sec is RFC minimum	*/
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#define TCP_SYNACK_RETRIES 5	/* number of times to retry passive opening a
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				 * connection: ~180sec is RFC minimum	*/
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#define TCP_TIMEWAIT_LEN (60*HZ) /* how long to wait to destroy TIME-WAIT
				  * state, about 60 seconds	*/
#define TCP_FIN_TIMEOUT	TCP_TIMEWAIT_LEN
                                 /* BSD style FIN_WAIT2 deadlock breaker.
				  * It used to be 3min, new value is 60sec,
				  * to combine FIN-WAIT-2 timeout with
				  * TIME-WAIT timer.
				  */

#define TCP_DELACK_MAX	((unsigned)(HZ/5))	/* maximal time to delay before sending an ACK */
#if HZ >= 100
#define TCP_DELACK_MIN	((unsigned)(HZ/25))	/* minimal time to delay before sending an ACK */
#define TCP_ATO_MIN	((unsigned)(HZ/25))
#else
#define TCP_DELACK_MIN	4U
#define TCP_ATO_MIN	4U
#endif
#define TCP_RTO_MAX	((unsigned)(120*HZ))
#define TCP_RTO_MIN	((unsigned)(HZ/5))
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#define TCP_TIMEOUT_INIT ((unsigned)(1*HZ))	/* RFC6298 2.1 initial RTO value	*/
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#define TCP_TIMEOUT_FALLBACK ((unsigned)(3*HZ))	/* RFC 1122 initial RTO value, now
						 * used as a fallback RTO for the
						 * initial data transmission if no
						 * valid RTT sample has been acquired,
						 * most likely due to retrans in 3WHS.
						 */
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#define TCP_RESOURCE_PROBE_INTERVAL ((unsigned)(HZ/2U)) /* Maximal interval between probes
					                 * for local resources.
					                 */

#define TCP_KEEPALIVE_TIME	(120*60*HZ)	/* two hours */
#define TCP_KEEPALIVE_PROBES	9		/* Max of 9 keepalive probes	*/
#define TCP_KEEPALIVE_INTVL	(75*HZ)

#define MAX_TCP_KEEPIDLE	32767
#define MAX_TCP_KEEPINTVL	32767
#define MAX_TCP_KEEPCNT		127
#define MAX_TCP_SYNCNT		127

#define TCP_SYNQ_INTERVAL	(HZ/5)	/* Period of SYNACK timer */

#define TCP_PAWS_24DAYS	(60 * 60 * 24 * 24)
#define TCP_PAWS_MSL	60		/* Per-host timestamps are invalidated
					 * after this time. It should be equal
					 * (or greater than) TCP_TIMEWAIT_LEN
					 * to provide reliability equal to one
					 * provided by timewait state.
					 */
#define TCP_PAWS_WINDOW	1		/* Replay window for per-host
					 * timestamps. It must be less than
					 * minimal timewait lifetime.
					 */
/*
 *	TCP option
 */
 
#define TCPOPT_NOP		1	/* Padding */
#define TCPOPT_EOL		0	/* End of options */
#define TCPOPT_MSS		2	/* Segment size negotiating */
#define TCPOPT_WINDOW		3	/* Window scaling */
#define TCPOPT_SACK_PERM        4       /* SACK Permitted */
#define TCPOPT_SACK             5       /* SACK Block */
#define TCPOPT_TIMESTAMP	8	/* Better RTT estimations/PAWS */
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#define TCPOPT_MD5SIG		19	/* MD5 Signature (RFC2385) */
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#define TCPOPT_COOKIE		253	/* Cookie extension (experimental) */
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#define TCPOPT_EXP		254	/* Experimental */
/* Magic number to be after the option value for sharing TCP
 * experimental options. See draft-ietf-tcpm-experimental-options-00.txt
 */
#define TCPOPT_FASTOPEN_MAGIC	0xF989
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/*
 *     TCP option lengths
 */

#define TCPOLEN_MSS            4
#define TCPOLEN_WINDOW         3
#define TCPOLEN_SACK_PERM      2
#define TCPOLEN_TIMESTAMP      10
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#define TCPOLEN_MD5SIG         18
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#define TCPOLEN_EXP_FASTOPEN_BASE  4
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#define TCPOLEN_COOKIE_BASE    2	/* Cookie-less header extension */
#define TCPOLEN_COOKIE_PAIR    3	/* Cookie pair header extension */
#define TCPOLEN_COOKIE_MIN     (TCPOLEN_COOKIE_BASE+TCP_COOKIE_MIN)
#define TCPOLEN_COOKIE_MAX     (TCPOLEN_COOKIE_BASE+TCP_COOKIE_MAX)
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/* But this is what stacks really send out. */
#define TCPOLEN_TSTAMP_ALIGNED		12
#define TCPOLEN_WSCALE_ALIGNED		4
#define TCPOLEN_SACKPERM_ALIGNED	4
#define TCPOLEN_SACK_BASE		2
#define TCPOLEN_SACK_BASE_ALIGNED	4
#define TCPOLEN_SACK_PERBLOCK		8
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#define TCPOLEN_MD5SIG_ALIGNED		20
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#define TCPOLEN_MSS_ALIGNED		4
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/* Flags in tp->nonagle */
#define TCP_NAGLE_OFF		1	/* Nagle's algo is disabled */
#define TCP_NAGLE_CORK		2	/* Socket is corked	    */
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#define TCP_NAGLE_PUSH		4	/* Cork is overridden for already queued data */
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/* TCP thin-stream limits */
#define TCP_THIN_LINEAR_RETRIES 6       /* After 6 linear retries, do exp. backoff */

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/* TCP initial congestion window as per draft-hkchu-tcpm-initcwnd-01 */
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#define TCP_INIT_CWND		10

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/* Bit Flags for sysctl_tcp_fastopen */
#define	TFO_CLIENT_ENABLE	1
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#define	TFO_CLIENT_NO_COOKIE	4	/* Data in SYN w/o cookie option */
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extern struct inet_timewait_death_row tcp_death_row;

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/* sysctl variables for tcp */
extern int sysctl_tcp_timestamps;
extern int sysctl_tcp_window_scaling;
extern int sysctl_tcp_sack;
extern int sysctl_tcp_fin_timeout;
extern int sysctl_tcp_keepalive_time;
extern int sysctl_tcp_keepalive_probes;
extern int sysctl_tcp_keepalive_intvl;
extern int sysctl_tcp_syn_retries;
extern int sysctl_tcp_synack_retries;
extern int sysctl_tcp_retries1;
extern int sysctl_tcp_retries2;
extern int sysctl_tcp_orphan_retries;
extern int sysctl_tcp_syncookies;
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extern int sysctl_tcp_fastopen;
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extern int sysctl_tcp_retrans_collapse;
extern int sysctl_tcp_stdurg;
extern int sysctl_tcp_rfc1337;
extern int sysctl_tcp_abort_on_overflow;
extern int sysctl_tcp_max_orphans;
extern int sysctl_tcp_fack;
extern int sysctl_tcp_reordering;
extern int sysctl_tcp_ecn;
extern int sysctl_tcp_dsack;
extern int sysctl_tcp_wmem[3];
extern int sysctl_tcp_rmem[3];
extern int sysctl_tcp_app_win;
extern int sysctl_tcp_adv_win_scale;
extern int sysctl_tcp_tw_reuse;
extern int sysctl_tcp_frto;
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extern int sysctl_tcp_frto_response;
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extern int sysctl_tcp_low_latency;
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extern int sysctl_tcp_dma_copybreak;
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extern int sysctl_tcp_nometrics_save;
extern int sysctl_tcp_moderate_rcvbuf;
extern int sysctl_tcp_tso_win_divisor;
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extern int sysctl_tcp_abc;
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extern int sysctl_tcp_mtu_probing;
extern int sysctl_tcp_base_mss;
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extern int sysctl_tcp_workaround_signed_windows;
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extern int sysctl_tcp_slow_start_after_idle;
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extern int sysctl_tcp_max_ssthresh;
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extern int sysctl_tcp_cookie_size;
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extern int sysctl_tcp_thin_linear_timeouts;
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extern int sysctl_tcp_thin_dupack;
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extern int sysctl_tcp_early_retrans;
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extern int sysctl_tcp_limit_output_bytes;
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extern int sysctl_tcp_challenge_ack_limit;
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extern atomic_long_t tcp_memory_allocated;
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extern struct percpu_counter tcp_sockets_allocated;
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extern int tcp_memory_pressure;

/*
 * The next routines deal with comparing 32 bit unsigned ints
 * and worry about wraparound (automatic with unsigned arithmetic).
 */

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static inline bool before(__u32 seq1, __u32 seq2)
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{
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        return (__s32)(seq1-seq2) < 0;
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}
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#define after(seq2, seq1) 	before(seq1, seq2)
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/* is s2<=s1<=s3 ? */
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static inline bool between(__u32 seq1, __u32 seq2, __u32 seq3)
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{
	return seq3 - seq2 >= seq1 - seq2;
}

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static inline bool tcp_out_of_memory(struct sock *sk)
{
	if (sk->sk_wmem_queued > SOCK_MIN_SNDBUF &&
	    sk_memory_allocated(sk) > sk_prot_mem_limits(sk, 2))
		return true;
	return false;
}

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static inline bool tcp_too_many_orphans(struct sock *sk, int shift)
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{
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	struct percpu_counter *ocp = sk->sk_prot->orphan_count;
	int orphans = percpu_counter_read_positive(ocp);

	if (orphans << shift > sysctl_tcp_max_orphans) {
		orphans = percpu_counter_sum_positive(ocp);
		if (orphans << shift > sysctl_tcp_max_orphans)
			return true;
	}
	return false;
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}
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extern bool tcp_check_oom(struct sock *sk, int shift);

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/* syncookies: remember time of last synqueue overflow */
static inline void tcp_synq_overflow(struct sock *sk)
{
	tcp_sk(sk)->rx_opt.ts_recent_stamp = jiffies;
}

/* syncookies: no recent synqueue overflow on this listening socket? */
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static inline bool tcp_synq_no_recent_overflow(const struct sock *sk)
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{
	unsigned long last_overflow = tcp_sk(sk)->rx_opt.ts_recent_stamp;
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	return time_after(jiffies, last_overflow + TCP_TIMEOUT_FALLBACK);
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}

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extern struct proto tcp_prot;

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#define TCP_INC_STATS(net, field)	SNMP_INC_STATS((net)->mib.tcp_statistics, field)
#define TCP_INC_STATS_BH(net, field)	SNMP_INC_STATS_BH((net)->mib.tcp_statistics, field)
#define TCP_DEC_STATS(net, field)	SNMP_DEC_STATS((net)->mib.tcp_statistics, field)
#define TCP_ADD_STATS_USER(net, field, val) SNMP_ADD_STATS_USER((net)->mib.tcp_statistics, field, val)
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#define TCP_ADD_STATS(net, field, val)	SNMP_ADD_STATS((net)->mib.tcp_statistics, field, val)
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extern void tcp_init_mem(struct net *net);

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extern void tcp_tasklet_init(void);

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extern void tcp_v4_err(struct sk_buff *skb, u32);

extern void tcp_shutdown (struct sock *sk, int how);

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extern void tcp_v4_early_demux(struct sk_buff *skb);
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extern int tcp_v4_rcv(struct sk_buff *skb);

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extern struct inet_peer *tcp_v4_get_peer(struct sock *sk);
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extern int tcp_v4_tw_remember_stamp(struct inet_timewait_sock *tw);
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extern int tcp_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
		       size_t size);
extern int tcp_sendpage(struct sock *sk, struct page *page, int offset,
			size_t size, int flags);
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extern void tcp_release_cb(struct sock *sk);
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extern void tcp_write_timer_handler(struct sock *sk);
extern void tcp_delack_timer_handler(struct sock *sk);
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extern int tcp_ioctl(struct sock *sk, int cmd, unsigned long arg);
extern int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb,
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				 const struct tcphdr *th, unsigned int len);
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extern int tcp_rcv_established(struct sock *sk, struct sk_buff *skb,
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			       const struct tcphdr *th, unsigned int len);
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extern void tcp_rcv_space_adjust(struct sock *sk);
extern void tcp_cleanup_rbuf(struct sock *sk, int copied);
extern int tcp_twsk_unique(struct sock *sk, struct sock *sktw, void *twp);
extern void tcp_twsk_destructor(struct sock *sk);
extern ssize_t tcp_splice_read(struct socket *sk, loff_t *ppos,
			       struct pipe_inode_info *pipe, size_t len,
			       unsigned int flags);
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static inline void tcp_dec_quickack_mode(struct sock *sk,
					 const unsigned int pkts)
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{
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	struct inet_connection_sock *icsk = inet_csk(sk);
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	if (icsk->icsk_ack.quick) {
		if (pkts >= icsk->icsk_ack.quick) {
			icsk->icsk_ack.quick = 0;
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			/* Leaving quickack mode we deflate ATO. */
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			icsk->icsk_ack.ato   = TCP_ATO_MIN;
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		} else
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			icsk->icsk_ack.quick -= pkts;
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	}
}

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#define	TCP_ECN_OK		1
#define	TCP_ECN_QUEUE_CWR	2
#define	TCP_ECN_DEMAND_CWR	4
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#define	TCP_ECN_SEEN		8
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enum tcp_tw_status {
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	TCP_TW_SUCCESS = 0,
	TCP_TW_RST = 1,
	TCP_TW_ACK = 2,
	TCP_TW_SYN = 3
};


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extern enum tcp_tw_status tcp_timewait_state_process(struct inet_timewait_sock *tw,
						     struct sk_buff *skb,
						     const struct tcphdr *th);
extern struct sock * tcp_check_req(struct sock *sk,struct sk_buff *skb,
				   struct request_sock *req,
				   struct request_sock **prev);
extern int tcp_child_process(struct sock *parent, struct sock *child,
			     struct sk_buff *skb);
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extern bool tcp_use_frto(struct sock *sk);
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extern void tcp_enter_frto(struct sock *sk);
extern void tcp_enter_loss(struct sock *sk, int how);
extern void tcp_clear_retrans(struct tcp_sock *tp);
extern void tcp_update_metrics(struct sock *sk);
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extern void tcp_init_metrics(struct sock *sk);
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extern void tcp_metrics_init(void);
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extern bool tcp_peer_is_proven(struct request_sock *req, struct dst_entry *dst, bool paws_check);
extern bool tcp_remember_stamp(struct sock *sk);
extern bool tcp_tw_remember_stamp(struct inet_timewait_sock *tw);
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extern void tcp_fastopen_cache_get(struct sock *sk, u16 *mss,
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				   struct tcp_fastopen_cookie *cookie,
				   int *syn_loss, unsigned long *last_syn_loss);
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extern void tcp_fastopen_cache_set(struct sock *sk, u16 mss,
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				   struct tcp_fastopen_cookie *cookie,
				   bool syn_lost);
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extern void tcp_fetch_timewait_stamp(struct sock *sk, struct dst_entry *dst);
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extern void tcp_disable_fack(struct tcp_sock *tp);
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extern void tcp_close(struct sock *sk, long timeout);
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extern void tcp_init_sock(struct sock *sk);
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extern unsigned int tcp_poll(struct file * file, struct socket *sock,
			     struct poll_table_struct *wait);
extern int tcp_getsockopt(struct sock *sk, int level, int optname,
			  char __user *optval, int __user *optlen);
extern int tcp_setsockopt(struct sock *sk, int level, int optname,
			  char __user *optval, unsigned int optlen);
extern int compat_tcp_getsockopt(struct sock *sk, int level, int optname,
				 char __user *optval, int __user *optlen);
extern int compat_tcp_setsockopt(struct sock *sk, int level, int optname,
				 char __user *optval, unsigned int optlen);
extern void tcp_set_keepalive(struct sock *sk, int val);
extern void tcp_syn_ack_timeout(struct sock *sk, struct request_sock *req);
extern int tcp_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
		       size_t len, int nonblock, int flags, int *addr_len);
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extern void tcp_parse_options(const struct sk_buff *skb,
			      struct tcp_options_received *opt_rx, const u8 **hvpp,
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			      int estab, struct tcp_fastopen_cookie *foc);
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extern const u8 *tcp_parse_md5sig_option(const struct tcphdr *th);
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/*
 *	TCP v4 functions exported for the inet6 API
 */

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extern void tcp_v4_send_check(struct sock *sk, struct sk_buff *skb);
extern int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb);
extern struct sock * tcp_create_openreq_child(struct sock *sk,
					      struct request_sock *req,
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					      struct sk_buff *skb);
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extern struct sock * tcp_v4_syn_recv_sock(struct sock *sk, struct sk_buff *skb,
					  struct request_sock *req,
					  struct dst_entry *dst);
extern int tcp_v4_do_rcv(struct sock *sk, struct sk_buff *skb);
extern int tcp_v4_connect(struct sock *sk, struct sockaddr *uaddr,
			  int addr_len);
extern int tcp_connect(struct sock *sk);
extern struct sk_buff * tcp_make_synack(struct sock *sk, struct dst_entry *dst,
					struct request_sock *req,
					struct request_values *rvp);
extern int tcp_disconnect(struct sock *sk, int flags);
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void tcp_connect_init(struct sock *sk);
void tcp_finish_connect(struct sock *sk, struct sk_buff *skb);
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int tcp_send_rcvq(struct sock *sk, struct msghdr *msg, size_t size);
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void inet_sk_rx_dst_set(struct sock *sk, const struct sk_buff *skb);
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/* From syncookies.c */
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extern __u32 syncookie_secret[2][16-4+SHA_DIGEST_WORDS];
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extern struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb, 
				    struct ip_options *opt);
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#ifdef CONFIG_SYN_COOKIES
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extern __u32 cookie_v4_init_sequence(struct sock *sk, struct sk_buff *skb, 
				     __u16 *mss);
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#else
static inline __u32 cookie_v4_init_sequence(struct sock *sk,
					    struct sk_buff *skb,
					    __u16 *mss)
{
	return 0;
}
#endif
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extern __u32 cookie_init_timestamp(struct request_sock *req);
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extern bool cookie_check_timestamp(struct tcp_options_received *opt, bool *);
487

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/* From net/ipv6/syncookies.c */
extern struct sock *cookie_v6_check(struct sock *sk, struct sk_buff *skb);
490
#ifdef CONFIG_SYN_COOKIES
491
extern __u32 cookie_v6_init_sequence(struct sock *sk, const struct sk_buff *skb,
492
				     __u16 *mss);
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#else
static inline __u32 cookie_v6_init_sequence(struct sock *sk,
					    struct sk_buff *skb,
					    __u16 *mss)
{
	return 0;
}
#endif
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/* tcp_output.c */

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extern void __tcp_push_pending_frames(struct sock *sk, unsigned int cur_mss,
				      int nonagle);
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extern bool tcp_may_send_now(struct sock *sk);
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extern int tcp_retransmit_skb(struct sock *, struct sk_buff *);
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extern void tcp_retransmit_timer(struct sock *sk);
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extern void tcp_xmit_retransmit_queue(struct sock *);
extern void tcp_simple_retransmit(struct sock *);
extern int tcp_trim_head(struct sock *, struct sk_buff *, u32);
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extern int tcp_fragment(struct sock *, struct sk_buff *, u32, unsigned int);
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extern void tcp_send_probe0(struct sock *);
extern void tcp_send_partial(struct sock *);
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extern int tcp_write_wakeup(struct sock *);
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extern void tcp_send_fin(struct sock *sk);
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extern void tcp_send_active_reset(struct sock *sk, gfp_t priority);
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extern int tcp_send_synack(struct sock *);
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extern bool tcp_syn_flood_action(struct sock *sk,
				 const struct sk_buff *skb,
				 const char *proto);
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extern void tcp_push_one(struct sock *, unsigned int mss_now);
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extern void tcp_send_ack(struct sock *sk);
extern void tcp_send_delayed_ack(struct sock *sk);

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/* tcp_input.c */
extern void tcp_cwnd_application_limited(struct sock *sk);
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extern void tcp_resume_early_retransmit(struct sock *sk);
extern void tcp_rearm_rto(struct sock *sk);
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/* tcp_timer.c */
extern void tcp_init_xmit_timers(struct sock *);
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static inline void tcp_clear_xmit_timers(struct sock *sk)
{
	inet_csk_clear_xmit_timers(sk);
}
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extern unsigned int tcp_sync_mss(struct sock *sk, u32 pmtu);
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extern unsigned int tcp_current_mss(struct sock *sk);

/* Bound MSS / TSO packet size with the half of the window */
static inline int tcp_bound_to_half_wnd(struct tcp_sock *tp, int pktsize)
{
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	int cutoff;

	/* When peer uses tiny windows, there is no use in packetizing
	 * to sub-MSS pieces for the sake of SWS or making sure there
	 * are enough packets in the pipe for fast recovery.
	 *
	 * On the other hand, for extremely large MSS devices, handling
	 * smaller than MSS windows in this way does make sense.
	 */
	if (tp->max_window >= 512)
		cutoff = (tp->max_window >> 1);
	else
		cutoff = tp->max_window;

	if (cutoff && pktsize > cutoff)
		return max_t(int, cutoff, 68U - tp->tcp_header_len);
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	else
		return pktsize;
}
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/* tcp.c */
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extern void tcp_get_info(const struct sock *, struct tcp_info *);
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/* Read 'sendfile()'-style from a TCP socket */
typedef int (*sk_read_actor_t)(read_descriptor_t *, struct sk_buff *,
				unsigned int, size_t);
extern int tcp_read_sock(struct sock *sk, read_descriptor_t *desc,
			 sk_read_actor_t recv_actor);

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extern void tcp_initialize_rcv_mss(struct sock *sk);
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extern int tcp_mtu_to_mss(struct sock *sk, int pmtu);
extern int tcp_mss_to_mtu(struct sock *sk, int mss);
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extern void tcp_mtup_init(struct sock *sk);
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extern void tcp_valid_rtt_meas(struct sock *sk, u32 seq_rtt);
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static inline void tcp_bound_rto(const struct sock *sk)
{
	if (inet_csk(sk)->icsk_rto > TCP_RTO_MAX)
		inet_csk(sk)->icsk_rto = TCP_RTO_MAX;
}

static inline u32 __tcp_set_rto(const struct tcp_sock *tp)
{
	return (tp->srtt >> 3) + tp->rttvar;
}

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extern void tcp_set_rto(struct sock *sk);

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static inline void __tcp_fast_path_on(struct tcp_sock *tp, u32 snd_wnd)
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{
	tp->pred_flags = htonl((tp->tcp_header_len << 26) |
			       ntohl(TCP_FLAG_ACK) |
			       snd_wnd);
}

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static inline void tcp_fast_path_on(struct tcp_sock *tp)
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{
	__tcp_fast_path_on(tp, tp->snd_wnd >> tp->rx_opt.snd_wscale);
}

605
static inline void tcp_fast_path_check(struct sock *sk)
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{
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	struct tcp_sock *tp = tcp_sk(sk);

609
	if (skb_queue_empty(&tp->out_of_order_queue) &&
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	    tp->rcv_wnd &&
	    atomic_read(&sk->sk_rmem_alloc) < sk->sk_rcvbuf &&
	    !tp->urg_data)
		tcp_fast_path_on(tp);
}

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/* Compute the actual rto_min value */
static inline u32 tcp_rto_min(struct sock *sk)
{
619
	const struct dst_entry *dst = __sk_dst_get(sk);
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	u32 rto_min = TCP_RTO_MIN;

	if (dst && dst_metric_locked(dst, RTAX_RTO_MIN))
		rto_min = dst_metric_rtt(dst, RTAX_RTO_MIN);
	return rto_min;
}

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/* Compute the actual receive window we are currently advertising.
 * Rcv_nxt can be after the window if our peer push more data
 * than the offered window.
 */
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static inline u32 tcp_receive_window(const struct tcp_sock *tp)
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{
	s32 win = tp->rcv_wup + tp->rcv_wnd - tp->rcv_nxt;

	if (win < 0)
		win = 0;
	return (u32) win;
}

/* Choose a new window, without checks for shrinking, and without
 * scaling applied to the result.  The caller does these things
 * if necessary.  This is a "raw" window selection.
 */
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extern u32 __tcp_select_window(struct sock *sk);
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void tcp_send_window_probe(struct sock *sk);

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/* TCP timestamps are only 32-bits, this causes a slight
 * complication on 64-bit systems since we store a snapshot
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 * of jiffies in the buffer control blocks below.  We decided
 * to use only the low 32-bits of jiffies and hide the ugly
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 * casts with the following macro.
 */
#define tcp_time_stamp		((__u32)(jiffies))

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#define tcp_flag_byte(th) (((u_int8_t *)th)[13])

#define TCPHDR_FIN 0x01
#define TCPHDR_SYN 0x02
#define TCPHDR_RST 0x04
#define TCPHDR_PSH 0x08
#define TCPHDR_ACK 0x10
#define TCPHDR_URG 0x20
#define TCPHDR_ECE 0x40
#define TCPHDR_CWR 0x80

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/* This is what the send packet queuing engine uses to pass
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 * TCP per-packet control information to the transmission code.
 * We also store the host-order sequence numbers in here too.
 * This is 44 bytes if IPV6 is enabled.
 * If this grows please adjust skbuff.h:skbuff->cb[xxx] size appropriately.
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 */
struct tcp_skb_cb {
	union {
		struct inet_skb_parm	h4;
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#if IS_ENABLED(CONFIG_IPV6)
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		struct inet6_skb_parm	h6;
#endif
	} header;	/* For incoming frames		*/
	__u32		seq;		/* Starting sequence number	*/
	__u32		end_seq;	/* SEQ + FIN + SYN + datalen	*/
	__u32		when;		/* used to compute rtt's	*/
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	__u8		tcp_flags;	/* TCP header flags. (tcp[13])	*/
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	__u8		sacked;		/* State flags for SACK/FACK.	*/
#define TCPCB_SACKED_ACKED	0x01	/* SKB ACK'd by a SACK block	*/
#define TCPCB_SACKED_RETRANS	0x02	/* SKB retransmitted		*/
#define TCPCB_LOST		0x04	/* SKB is lost			*/
#define TCPCB_TAGBITS		0x07	/* All tag bits			*/
#define TCPCB_EVER_RETRANS	0x80	/* Ever retransmitted frame	*/
#define TCPCB_RETRANS		(TCPCB_SACKED_RETRANS|TCPCB_EVER_RETRANS)

693 694
	__u8		ip_dsfield;	/* IPv4 tos or IPv6 dsfield	*/
	/* 1 byte hole */
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	__u32		ack_seq;	/* Sequence number ACK'd	*/
};

#define TCP_SKB_CB(__skb)	((struct tcp_skb_cb *)&((__skb)->cb[0]))

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/* RFC3168 : 6.1.1 SYN packets must not have ECT/ECN bits set
 *
 * If we receive a SYN packet with these bits set, it means a network is
 * playing bad games with TOS bits. In order to avoid possible false congestion
 * notifications, we disable TCP ECN negociation.
 */
static inline void
TCP_ECN_create_request(struct request_sock *req, const struct sk_buff *skb)
{
	const struct tcphdr *th = tcp_hdr(skb);

	if (sysctl_tcp_ecn && th->ece && th->cwr &&
	    INET_ECN_is_not_ect(TCP_SKB_CB(skb)->ip_dsfield))
		inet_rsk(req)->ecn_ok = 1;
}

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/* Due to TSO, an SKB can be composed of multiple actual
 * packets.  To keep these tracked properly, we use this.
 */
static inline int tcp_skb_pcount(const struct sk_buff *skb)
{
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	return skb_shinfo(skb)->gso_segs;
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}

/* This is valid iff tcp_skb_pcount() > 1. */
static inline int tcp_skb_mss(const struct sk_buff *skb)
{
727
	return skb_shinfo(skb)->gso_size;
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}

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/* Events passed to congestion control interface */
enum tcp_ca_event {
	CA_EVENT_TX_START,	/* first transmit when no packets in flight */
	CA_EVENT_CWND_RESTART,	/* congestion window restart */
	CA_EVENT_COMPLETE_CWR,	/* end of congestion recovery */
	CA_EVENT_FRTO,		/* fast recovery timeout */
	CA_EVENT_LOSS,		/* loss timeout */
	CA_EVENT_FAST_ACK,	/* in sequence ack */
	CA_EVENT_SLOW_ACK,	/* other ack */
};

/*
 * Interface for adding new TCP congestion control handlers
 */
#define TCP_CA_NAME_MAX	16
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#define TCP_CA_MAX	128
#define TCP_CA_BUF_MAX	(TCP_CA_NAME_MAX*TCP_CA_MAX)

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#define TCP_CONG_NON_RESTRICTED 0x1
#define TCP_CONG_RTT_STAMP	0x2

751 752
struct tcp_congestion_ops {
	struct list_head	list;
753
	unsigned long flags;
754 755

	/* initialize private data (optional) */
756
	void (*init)(struct sock *sk);
757
	/* cleanup private data  (optional) */
758
	void (*release)(struct sock *sk);
759 760

	/* return slow start threshold (required) */
761
	u32 (*ssthresh)(struct sock *sk);
762
	/* lower bound for congestion window (optional) */
763
	u32 (*min_cwnd)(const struct sock *sk);
764
	/* do new cwnd calculation (required) */
765
	void (*cong_avoid)(struct sock *sk, u32 ack, u32 in_flight);
766
	/* call before changing ca_state (optional) */
767
	void (*set_state)(struct sock *sk, u8 new_state);
768
	/* call when cwnd event occurs (optional) */
769
	void (*cwnd_event)(struct sock *sk, enum tcp_ca_event ev);
770
	/* new value of cwnd after loss (optional) */
771
	u32  (*undo_cwnd)(struct sock *sk);
772
	/* hook for packet ack accounting (optional) */
773
	void (*pkts_acked)(struct sock *sk, u32 num_acked, s32 rtt_us);
774
	/* get info for inet_diag (optional) */
775
	void (*get_info)(struct sock *sk, u32 ext, struct sk_buff *skb);
776 777 778 779 780 781 782 783

	char 		name[TCP_CA_NAME_MAX];
	struct module 	*owner;
};

extern int tcp_register_congestion_control(struct tcp_congestion_ops *type);
extern void tcp_unregister_congestion_control(struct tcp_congestion_ops *type);

784 785
extern void tcp_init_congestion_control(struct sock *sk);
extern void tcp_cleanup_congestion_control(struct sock *sk);
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extern int tcp_set_default_congestion_control(const char *name);
extern void tcp_get_default_congestion_control(char *name);
788
extern void tcp_get_available_congestion_control(char *buf, size_t len);
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extern void tcp_get_allowed_congestion_control(char *buf, size_t len);
extern int tcp_set_allowed_congestion_control(char *allowed);
791
extern int tcp_set_congestion_control(struct sock *sk, const char *name);
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extern void tcp_slow_start(struct tcp_sock *tp);
793
extern void tcp_cong_avoid_ai(struct tcp_sock *tp, u32 w);
794

795
extern struct tcp_congestion_ops tcp_init_congestion_ops;
796
extern u32 tcp_reno_ssthresh(struct sock *sk);
797
extern void tcp_reno_cong_avoid(struct sock *sk, u32 ack, u32 in_flight);
798
extern u32 tcp_reno_min_cwnd(const struct sock *sk);
799
extern struct tcp_congestion_ops tcp_reno;
800

801
static inline void tcp_set_ca_state(struct sock *sk, const u8 ca_state)
802
{
803 804 805 806 807
	struct inet_connection_sock *icsk = inet_csk(sk);

	if (icsk->icsk_ca_ops->set_state)
		icsk->icsk_ca_ops->set_state(sk, ca_state);
	icsk->icsk_ca_state = ca_state;
808 809
}

810
static inline void tcp_ca_event(struct sock *sk, const enum tcp_ca_event event)
811
{
812 813 814 815
	const struct inet_connection_sock *icsk = inet_csk(sk);

	if (icsk->icsk_ca_ops->cwnd_event)
		icsk->icsk_ca_ops->cwnd_event(sk, event);
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}

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/* These functions determine how the current flow behaves in respect of SACK
 * handling. SACK is negotiated with the peer, and therefore it can vary
 * between different flows.
 *
 * tcp_is_sack - SACK enabled
 * tcp_is_reno - No SACK
 * tcp_is_fack - FACK enabled, implies SACK enabled
 */
static inline int tcp_is_sack(const struct tcp_sock *tp)
{
	return tp->rx_opt.sack_ok;
}

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static inline bool tcp_is_reno(const struct tcp_sock *tp)
832 833 834 835
{
	return !tcp_is_sack(tp);
}

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static inline bool tcp_is_fack(const struct tcp_sock *tp)
837
{
838
	return tp->rx_opt.sack_ok & TCP_FACK_ENABLED;
839 840 841 842
}

static inline void tcp_enable_fack(struct tcp_sock *tp)
{
843
	tp->rx_opt.sack_ok |= TCP_FACK_ENABLED;
844 845
}

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/* TCP early-retransmit (ER) is similar to but more conservative than
 * the thin-dupack feature.  Enable ER only if thin-dupack is disabled.
 */
static inline void tcp_enable_early_retrans(struct tcp_sock *tp)
{
	tp->do_early_retrans = sysctl_tcp_early_retrans &&
		!sysctl_tcp_thin_dupack && sysctl_tcp_reordering == 3;
853
	tp->early_retrans_delayed = 0;
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}

static inline void tcp_disable_early_retrans(struct tcp_sock *tp)
{
	tp->do_early_retrans = 0;
}

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static inline unsigned int tcp_left_out(const struct tcp_sock *tp)
{
	return tp->sacked_out + tp->lost_out;
}

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/* This determines how many packets are "in the network" to the best
 * of our knowledge.  In many cases it is conservative, but where
 * detailed information is available from the receiver (via SACK
 * blocks etc.) we can make more aggressive calculations.
 *
 * Use this for decisions involving congestion control, use just
 * tp->packets_out to determine if the send queue is empty or not.
 *
 * Read this equation as:
 *
 *	"Packets sent once on transmission queue" MINUS
 *	"Packets left network, but not honestly ACKed yet" PLUS
 *	"Packets fast retransmitted"
 */
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static inline unsigned int tcp_packets_in_flight(const struct tcp_sock *tp)
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{
882
	return tp->packets_out - tcp_left_out(tp) + tp->retrans_out;
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}

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#define TCP_INFINITE_SSTHRESH	0x7fffffff

static inline bool tcp_in_initial_slowstart(const struct tcp_sock *tp)
{
	return tp->snd_ssthresh >= TCP_INFINITE_SSTHRESH;
}

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/* If cwnd > ssthresh, we may raise ssthresh to be half-way to cwnd.
 * The exception is rate halving phase, when cwnd is decreasing towards
 * ssthresh.
 */
896
static inline __u32 tcp_current_ssthresh(const struct sock *sk)
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{
898
	const struct tcp_sock *tp = tcp_sk(sk);
899

900
	if ((1 << inet_csk(sk)->icsk_ca_state) & (TCPF_CA_CWR | TCPF_CA_Recovery))
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		return tp->snd_ssthresh;
	else
		return max(tp->snd_ssthresh,
			   ((tp->snd_cwnd >> 1) +
			    (tp->snd_cwnd >> 2)));
}

908 909
/* Use define here intentionally to get WARN_ON location shown at the caller */
#define tcp_verify_left_out(tp)	WARN_ON(tcp_left_out(tp) > tp->packets_out)
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911
extern void tcp_enter_cwr(struct sock *sk, const int set_ssthresh);
912
extern __u32 tcp_init_cwnd(const struct tcp_sock *tp, const struct dst_entry *dst);
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/* The maximum number of MSS of available cwnd for which TSO defers
 * sending if not using sysctl_tcp_tso_win_divisor.
 */
static inline __u32 tcp_max_tso_deferred_mss(const struct tcp_sock *tp)
{
	return 3;
}

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/* Slow start with delack produces 3 packets of burst, so that
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 * it is safe "de facto".  This will be the default - same as
 * the default reordering threshold - but if reordering increases,
 * we must be able to allow cwnd to burst at least this much in order
 * to not pull it back when holes are filled.
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 */
static __inline__ __u32 tcp_max_burst(const struct tcp_sock *tp)
{
930
	return tp->reordering;
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}

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/* Returns end sequence number of the receiver's advertised window */
static inline u32 tcp_wnd_end(const struct tcp_sock *tp)
{
	return tp->snd_una + tp->snd_wnd;
}
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extern bool tcp_is_cwnd_limited(const struct sock *sk, u32 in_flight);
939

940
static inline void tcp_minshall_update(struct tcp_sock *tp, unsigned int mss,
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				       const struct sk_buff *skb)
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{
	if (skb->len < mss)
		tp->snd_sml = TCP_SKB_CB(skb)->end_seq;
}

947
static inline void tcp_check_probe_timer(struct sock *sk)
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{
949
	const struct tcp_sock *tp = tcp_sk(sk);
950
	const struct inet_connection_sock *icsk = inet_csk(sk);
951

952
	if (!tp->packets_out && !icsk->icsk_pending)
953 954
		inet_csk_reset_xmit_timer(sk, ICSK_TIME_PROBE0,
					  icsk->icsk_rto, TCP_RTO_MAX);
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}

957
static inline void tcp_init_wl(struct tcp_sock *tp, u32 seq)
L
Linus Torvalds 已提交
958 959 960 961
{
	tp->snd_wl1 = seq;
}

962
static inline void tcp_update_wl(struct tcp_sock *tp, u32 seq)
L
Linus Torvalds 已提交
963 964 965 966 967 968 969
{
	tp->snd_wl1 = seq;
}

/*
 * Calculate(/check) TCP checksum
 */
970 971
static inline __sum16 tcp_v4_check(int len, __be32 saddr,
				   __be32 daddr, __wsum base)
L
Linus Torvalds 已提交
972 973 974 975
{
	return csum_tcpudp_magic(saddr,daddr,len,IPPROTO_TCP,base);
}

976
static inline __sum16 __tcp_checksum_complete(struct sk_buff *skb)
L
Linus Torvalds 已提交
977
{
978
	return __skb_checksum_complete(skb);
L
Linus Torvalds 已提交
979 980
}

E
Eric Dumazet 已提交
981
static inline bool tcp_checksum_complete(struct sk_buff *skb)
L
Linus Torvalds 已提交
982
{
983
	return !skb_csum_unnecessary(skb) &&
L
Linus Torvalds 已提交
984 985 986 987 988
		__tcp_checksum_complete(skb);
}

/* Prequeue for VJ style copy to user, combined with checksumming. */

S
Stephen Hemminger 已提交
989
static inline void tcp_prequeue_init(struct tcp_sock *tp)
L
Linus Torvalds 已提交
990 991 992 993 994
{
	tp->ucopy.task = NULL;
	tp->ucopy.len = 0;
	tp->ucopy.memory = 0;
	skb_queue_head_init(&tp->ucopy.prequeue);
995 996 997 998 999 1000
#ifdef CONFIG_NET_DMA
	tp->ucopy.dma_chan = NULL;
	tp->ucopy.wakeup = 0;
	tp->ucopy.pinned_list = NULL;
	tp->ucopy.dma_cookie = 0;
#endif
L
Linus Torvalds 已提交
1001 1002 1003 1004 1005 1006 1007 1008 1009 1010
}

/* Packet is added to VJ-style prequeue for processing in process
 * context, if a reader task is waiting. Apparently, this exciting
 * idea (VJ's mail "Re: query about TCP header on tcp-ip" of 07 Sep 93)
 * failed somewhere. Latency? Burstiness? Well, at least now we will
 * see, why it failed. 8)8)				  --ANK
 *
 * NOTE: is this not too big to inline?
 */
E
Eric Dumazet 已提交
1011
static inline bool tcp_prequeue(struct sock *sk, struct sk_buff *skb)
L
Linus Torvalds 已提交
1012 1013 1014
{
	struct tcp_sock *tp = tcp_sk(sk);

E
Eric Dumazet 已提交
1015
	if (sysctl_tcp_low_latency || !tp->ucopy.task)
E
Eric Dumazet 已提交
1016
		return false;
E
Eric Dumazet 已提交
1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 1028

	__skb_queue_tail(&tp->ucopy.prequeue, skb);
	tp->ucopy.memory += skb->truesize;
	if (tp->ucopy.memory > sk->sk_rcvbuf) {
		struct sk_buff *skb1;

		BUG_ON(sock_owned_by_user(sk));

		while ((skb1 = __skb_dequeue(&tp->ucopy.prequeue)) != NULL) {
			sk_backlog_rcv(sk, skb1);
			NET_INC_STATS_BH(sock_net(sk),
					 LINUX_MIB_TCPPREQUEUEDROPPED);
L
Linus Torvalds 已提交
1029
		}
E
Eric Dumazet 已提交
1030 1031 1032

		tp->ucopy.memory = 0;
	} else if (skb_queue_len(&tp->ucopy.prequeue) == 1) {
E
Eric Dumazet 已提交
1033
		wake_up_interruptible_sync_poll(sk_sleep(sk),
1034
					   POLLIN | POLLRDNORM | POLLRDBAND);
E
Eric Dumazet 已提交
1035 1036
		if (!inet_csk_ack_scheduled(sk))
			inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK,
1037
						  (3 * tcp_rto_min(sk)) / 4,
E
Eric Dumazet 已提交
1038
						  TCP_RTO_MAX);
L
Linus Torvalds 已提交
1039
	}
E
Eric Dumazet 已提交
1040
	return true;
L
Linus Torvalds 已提交
1041 1042 1043 1044 1045 1046 1047 1048 1049 1050 1051 1052
}


#undef STATE_TRACE

#ifdef STATE_TRACE
static const char *statename[]={
	"Unused","Established","Syn Sent","Syn Recv",
	"Fin Wait 1","Fin Wait 2","Time Wait", "Close",
	"Close Wait","Last ACK","Listen","Closing"
};
#endif
I
Ilpo Järvinen 已提交
1053
extern void tcp_set_state(struct sock *sk, int state);
L
Linus Torvalds 已提交
1054

A
Andi Kleen 已提交
1055
extern void tcp_done(struct sock *sk);
L
Linus Torvalds 已提交
1056

S
Stephen Hemminger 已提交
1057
static inline void tcp_sack_reset(struct tcp_options_received *rx_opt)
L
Linus Torvalds 已提交
1058 1059 1060 1061 1062 1063 1064 1065
{
	rx_opt->dsack = 0;
	rx_opt->num_sacks = 0;
}

/* Determine a window scaling and initial window to offer. */
extern void tcp_select_initial_window(int __space, __u32 mss,
				      __u32 *rcv_wnd, __u32 *window_clamp,
1066 1067
				      int wscale_ok, __u8 *rcv_wscale,
				      __u32 init_rcv_wnd);
L
Linus Torvalds 已提交
1068 1069 1070 1071 1072 1073 1074 1075 1076 1077 1078 1079 1080 1081 1082 1083 1084 1085 1086 1087

static inline int tcp_win_from_space(int space)
{
	return sysctl_tcp_adv_win_scale<=0 ?
		(space>>(-sysctl_tcp_adv_win_scale)) :
		space - (space>>sysctl_tcp_adv_win_scale);
}

/* Note: caller must be prepared to deal with negative returns */ 
static inline int tcp_space(const struct sock *sk)
{
	return tcp_win_from_space(sk->sk_rcvbuf -
				  atomic_read(&sk->sk_rmem_alloc));
} 

static inline int tcp_full_space(const struct sock *sk)
{
	return tcp_win_from_space(sk->sk_rcvbuf); 
}

S
Stephen Hemminger 已提交
1088 1089 1090
static inline void tcp_openreq_init(struct request_sock *req,
				    struct tcp_options_received *rx_opt,
				    struct sk_buff *skb)
L
Linus Torvalds 已提交
1091
{
1092 1093
	struct inet_request_sock *ireq = inet_rsk(req);

L
Linus Torvalds 已提交
1094
	req->rcv_wnd = 0;		/* So that tcp_send_synack() knows! */
1095
	req->cookie_ts = 0;
1096
	tcp_rsk(req)->rcv_isn = TCP_SKB_CB(skb)->seq;
L
Linus Torvalds 已提交
1097 1098
	req->mss = rx_opt->mss_clamp;
	req->ts_recent = rx_opt->saw_tstamp ? rx_opt->rcv_tsval : 0;
1099 1100 1101 1102 1103 1104
	ireq->tstamp_ok = rx_opt->tstamp_ok;
	ireq->sack_ok = rx_opt->sack_ok;
	ireq->snd_wscale = rx_opt->snd_wscale;
	ireq->wscale_ok = rx_opt->wscale_ok;
	ireq->acked = 0;
	ireq->ecn_ok = 0;
1105
	ireq->rmt_port = tcp_hdr(skb)->source;
1106
	ireq->loc_port = tcp_hdr(skb)->dest;
L
Linus Torvalds 已提交
1107 1108
}

1109
extern void tcp_enter_memory_pressure(struct sock *sk);
L
Linus Torvalds 已提交
1110 1111 1112 1113 1114 1115 1116 1117 1118 1119 1120

static inline int keepalive_intvl_when(const struct tcp_sock *tp)
{
	return tp->keepalive_intvl ? : sysctl_tcp_keepalive_intvl;
}

static inline int keepalive_time_when(const struct tcp_sock *tp)
{
	return tp->keepalive_time ? : sysctl_tcp_keepalive_time;
}

E
Eric Dumazet 已提交
1121 1122 1123 1124 1125
static inline int keepalive_probes(const struct tcp_sock *tp)
{
	return tp->keepalive_probes ? : sysctl_tcp_keepalive_probes;
}

1126 1127 1128 1129 1130 1131 1132 1133
static inline u32 keepalive_time_elapsed(const struct tcp_sock *tp)
{
	const struct inet_connection_sock *icsk = &tp->inet_conn;

	return min_t(u32, tcp_time_stamp - icsk->icsk_ack.lrcvtime,
			  tcp_time_stamp - tp->rcv_tstamp);
}

1134
static inline int tcp_fin_time(const struct sock *sk)
L
Linus Torvalds 已提交
1135
{
1136 1137
	int fin_timeout = tcp_sk(sk)->linger2 ? : sysctl_tcp_fin_timeout;
	const int rto = inet_csk(sk)->icsk_rto;
L
Linus Torvalds 已提交
1138

1139 1140
	if (fin_timeout < (rto << 2) - (rto >> 1))
		fin_timeout = (rto << 2) - (rto >> 1);
L
Linus Torvalds 已提交
1141 1142 1143 1144

	return fin_timeout;
}

E
Eric Dumazet 已提交
1145 1146
static inline bool tcp_paws_check(const struct tcp_options_received *rx_opt,
				  int paws_win)
L
Linus Torvalds 已提交
1147
{
I
Ilpo Järvinen 已提交
1148
	if ((s32)(rx_opt->ts_recent - rx_opt->rcv_tsval) <= paws_win)
E
Eric Dumazet 已提交
1149
		return true;
I
Ilpo Järvinen 已提交
1150
	if (unlikely(get_seconds() >= rx_opt->ts_recent_stamp + TCP_PAWS_24DAYS))
E
Eric Dumazet 已提交
1151
		return true;
E
Eric Dumazet 已提交
1152 1153 1154 1155 1156 1157
	/*
	 * Some OSes send SYN and SYNACK messages with tsval=0 tsecr=0,
	 * then following tcp messages have valid values. Ignore 0 value,
	 * or else 'negative' tsval might forbid us to accept their packets.
	 */
	if (!rx_opt->ts_recent)
E
Eric Dumazet 已提交
1158 1159
		return true;
	return false;
I
Ilpo Järvinen 已提交
1160 1161
}

E
Eric Dumazet 已提交
1162 1163
static inline bool tcp_paws_reject(const struct tcp_options_received *rx_opt,
				   int rst)
I
Ilpo Järvinen 已提交
1164 1165
{
	if (tcp_paws_check(rx_opt, 0))
E
Eric Dumazet 已提交
1166
		return false;
L
Linus Torvalds 已提交
1167 1168 1169 1170 1171 1172 1173 1174 1175 1176 1177 1178 1179

	/* RST segments are not recommended to carry timestamp,
	   and, if they do, it is recommended to ignore PAWS because
	   "their cleanup function should take precedence over timestamps."
	   Certainly, it is mistake. It is necessary to understand the reasons
	   of this constraint to relax it: if peer reboots, clock may go
	   out-of-sync and half-open connections will not be reset.
	   Actually, the problem would be not existing if all
	   the implementations followed draft about maintaining clock
	   via reboots. Linux-2.2 DOES NOT!

	   However, we can relax time bounds for RST segments to MSL.
	 */
1180
	if (rst && get_seconds() >= rx_opt->ts_recent_stamp + TCP_PAWS_MSL)
E
Eric Dumazet 已提交
1181 1182
		return false;
	return true;
L
Linus Torvalds 已提交
1183 1184
}

P
Pavel Emelyanov 已提交
1185
static inline void tcp_mib_init(struct net *net)
L
Linus Torvalds 已提交
1186 1187
{
	/* See RFC 2012 */
1188 1189 1190 1191
	TCP_ADD_STATS_USER(net, TCP_MIB_RTOALGORITHM, 1);
	TCP_ADD_STATS_USER(net, TCP_MIB_RTOMIN, TCP_RTO_MIN*1000/HZ);
	TCP_ADD_STATS_USER(net, TCP_MIB_RTOMAX, TCP_RTO_MAX*1000/HZ);
	TCP_ADD_STATS_USER(net, TCP_MIB_MAXCONN, -1);
L
Linus Torvalds 已提交
1192 1193
}

1194
/* from STCP */
1195
static inline void tcp_clear_retrans_hints_partial(struct tcp_sock *tp)
D
David S. Miller 已提交
1196
{
1197 1198
	tp->lost_skb_hint = NULL;
	tp->scoreboard_skb_hint = NULL;
1199 1200 1201 1202 1203
}

static inline void tcp_clear_all_retrans_hints(struct tcp_sock *tp)
{
	tcp_clear_retrans_hints_partial(tp);
1204
	tp->retransmit_skb_hint = NULL;
1205 1206
}

1207 1208 1209
/* MD5 Signature */
struct crypto_hash;

E
Eric Dumazet 已提交
1210 1211 1212 1213 1214 1215 1216
union tcp_md5_addr {
	struct in_addr  a4;
#if IS_ENABLED(CONFIG_IPV6)
	struct in6_addr	a6;
#endif
};

1217 1218
/* - key database */
struct tcp_md5sig_key {
E
Eric Dumazet 已提交
1219
	struct hlist_node	node;
1220
	u8			keylen;
E
Eric Dumazet 已提交
1221 1222 1223 1224
	u8			family; /* AF_INET or AF_INET6 */
	union tcp_md5_addr	addr;
	u8			key[TCP_MD5SIG_MAXKEYLEN];
	struct rcu_head		rcu;
1225 1226 1227 1228
};

/* - sock block */
struct tcp_md5sig_info {
E
Eric Dumazet 已提交
1229
	struct hlist_head	head;
1230
	struct rcu_head		rcu;
1231 1232 1233 1234 1235 1236 1237 1238 1239 1240 1241 1242 1243 1244 1245 1246 1247 1248 1249 1250
};

/* - pseudo header */
struct tcp4_pseudohdr {
	__be32		saddr;
	__be32		daddr;
	__u8		pad;
	__u8		protocol;
	__be16		len;
};

struct tcp6_pseudohdr {
	struct in6_addr	saddr;
	struct in6_addr daddr;
	__be32		len;
	__be32		protocol;	/* including padding */
};

union tcp_md5sum_block {
	struct tcp4_pseudohdr ip4;
E
Eric Dumazet 已提交
1251
#if IS_ENABLED(CONFIG_IPV6)
1252 1253 1254 1255 1256 1257 1258 1259 1260 1261 1262
	struct tcp6_pseudohdr ip6;
#endif
};

/* - pool: digest algorithm, hash description and scratch buffer */
struct tcp_md5sig_pool {
	struct hash_desc	md5_desc;
	union tcp_md5sum_block	md5_blk;
};

/* - functions */
C
Changli Gao 已提交
1263
extern int tcp_v4_md5_hash_skb(char *md5_hash, struct tcp_md5sig_key *key,
E
Eric Dumazet 已提交
1264 1265 1266
			       const struct sock *sk,
			       const struct request_sock *req,
			       const struct sk_buff *skb);
E
Eric Dumazet 已提交
1267 1268 1269 1270 1271 1272 1273
extern int tcp_md5_do_add(struct sock *sk, const union tcp_md5_addr *addr,
			  int family, const u8 *newkey,
			  u8 newkeylen, gfp_t gfp);
extern int tcp_md5_do_del(struct sock *sk, const union tcp_md5_addr *addr,
			  int family);
extern struct tcp_md5sig_key *tcp_v4_md5_lookup(struct sock *sk,
					 struct sock *addr_sk);
1274

1275
#ifdef CONFIG_TCP_MD5SIG
E
Eric Dumazet 已提交
1276 1277 1278
extern struct tcp_md5sig_key *tcp_md5_do_lookup(struct sock *sk,
			const union tcp_md5_addr *addr, int family);
#define tcp_twsk_md5_key(twsk)	((twsk)->tw_md5_key)
1279
#else
E
Eric Dumazet 已提交
1280 1281 1282 1283 1284 1285
static inline struct tcp_md5sig_key *tcp_md5_do_lookup(struct sock *sk,
					 const union tcp_md5_addr *addr,
					 int family)
{
	return NULL;
}
1286 1287 1288
#define tcp_twsk_md5_key(twsk)	NULL
#endif

1289
extern struct tcp_md5sig_pool __percpu *tcp_alloc_md5sig_pool(struct sock *);
C
Changli Gao 已提交
1290
extern void tcp_free_md5sig_pool(void);
1291

E
Eric Dumazet 已提交
1292
extern struct tcp_md5sig_pool	*tcp_get_md5sig_pool(void);
C
Changli Gao 已提交
1293
extern void tcp_put_md5sig_pool(void);
E
Eric Dumazet 已提交
1294

1295
extern int tcp_md5_hash_header(struct tcp_md5sig_pool *, const struct tcphdr *);
1296
extern int tcp_md5_hash_skb_data(struct tcp_md5sig_pool *, const struct sk_buff *,
1297
				 unsigned int header_len);
1298
extern int tcp_md5_hash_key(struct tcp_md5sig_pool *hp,
1299
			    const struct tcp_md5sig_key *key);
1300

1301 1302 1303 1304 1305 1306 1307 1308 1309
struct tcp_fastopen_request {
	/* Fast Open cookie. Size 0 means a cookie request */
	struct tcp_fastopen_cookie	cookie;
	struct msghdr			*data;  /* data in MSG_FASTOPEN */
	u16				copied;	/* queued in tcp_connect() */
};

void tcp_free_fastopen_req(struct tcp_sock *tp);

1310 1311 1312 1313 1314 1315
/* write queue abstraction */
static inline void tcp_write_queue_purge(struct sock *sk)
{
	struct sk_buff *skb;

	while ((skb = __skb_dequeue(&sk->sk_write_queue)) != NULL)
1316 1317
		sk_wmem_free_skb(sk, skb);
	sk_mem_reclaim(sk);
1318
	tcp_clear_all_retrans_hints(tcp_sk(sk));
1319 1320
}

1321
static inline struct sk_buff *tcp_write_queue_head(const struct sock *sk)
1322
{
1323
	return skb_peek(&sk->sk_write_queue);
1324 1325
}

1326
static inline struct sk_buff *tcp_write_queue_tail(const struct sock *sk)
1327
{
1328
	return skb_peek_tail(&sk->sk_write_queue);
1329 1330
}

1331 1332
static inline struct sk_buff *tcp_write_queue_next(const struct sock *sk,
						   const struct sk_buff *skb)
1333
{
1334
	return skb_queue_next(&sk->sk_write_queue, skb);
1335 1336
}

1337 1338
static inline struct sk_buff *tcp_write_queue_prev(const struct sock *sk,
						   const struct sk_buff *skb)
1339 1340 1341 1342
{
	return skb_queue_prev(&sk->sk_write_queue, skb);
}

1343
#define tcp_for_write_queue(skb, sk)					\
1344
	skb_queue_walk(&(sk)->sk_write_queue, skb)
1345 1346

#define tcp_for_write_queue_from(skb, sk)				\
1347
	skb_queue_walk_from(&(sk)->sk_write_queue, skb)
1348

1349
#define tcp_for_write_queue_from_safe(skb, tmp, sk)			\
1350
	skb_queue_walk_from_safe(&(sk)->sk_write_queue, skb, tmp)
1351

1352
static inline struct sk_buff *tcp_send_head(const struct sock *sk)
1353 1354 1355 1356
{
	return sk->sk_send_head;
}

1357 1358 1359 1360 1361 1362
static inline bool tcp_skb_is_last(const struct sock *sk,
				   const struct sk_buff *skb)
{
	return skb_queue_is_last(&sk->sk_write_queue, skb);
}

1363
static inline void tcp_advance_send_head(struct sock *sk, const struct sk_buff *skb)
1364
{
1365
	if (tcp_skb_is_last(sk, skb))
1366
		sk->sk_send_head = NULL;
1367 1368
	else
		sk->sk_send_head = tcp_write_queue_next(sk, skb);
1369 1370 1371 1372 1373 1374 1375 1376 1377 1378 1379 1380 1381 1382 1383 1384 1385 1386 1387 1388 1389 1390 1391
}

static inline void tcp_check_send_head(struct sock *sk, struct sk_buff *skb_unlinked)
{
	if (sk->sk_send_head == skb_unlinked)
		sk->sk_send_head = NULL;
}

static inline void tcp_init_send_head(struct sock *sk)
{
	sk->sk_send_head = NULL;
}

static inline void __tcp_add_write_queue_tail(struct sock *sk, struct sk_buff *skb)
{
	__skb_queue_tail(&sk->sk_write_queue, skb);
}

static inline void tcp_add_write_queue_tail(struct sock *sk, struct sk_buff *skb)
{
	__tcp_add_write_queue_tail(sk, skb);

	/* Queue it, remembering where we must start sending. */
1392
	if (sk->sk_send_head == NULL) {
1393
		sk->sk_send_head = skb;
1394 1395 1396 1397

		if (tcp_sk(sk)->highest_sack == NULL)
			tcp_sk(sk)->highest_sack = skb;
	}
1398 1399 1400 1401 1402 1403 1404 1405 1406 1407 1408 1409
}

static inline void __tcp_add_write_queue_head(struct sock *sk, struct sk_buff *skb)
{
	__skb_queue_head(&sk->sk_write_queue, skb);
}

/* Insert buff after skb on the write queue of sk.  */
static inline void tcp_insert_write_queue_after(struct sk_buff *skb,
						struct sk_buff *buff,
						struct sock *sk)
{
1410
	__skb_queue_after(&sk->sk_write_queue, skb, buff);
1411 1412
}

1413
/* Insert new before skb on the write queue of sk.  */
1414 1415 1416 1417
static inline void tcp_insert_write_queue_before(struct sk_buff *new,
						  struct sk_buff *skb,
						  struct sock *sk)
{
1418
	__skb_queue_before(&sk->sk_write_queue, skb, new);
1419 1420 1421

	if (sk->sk_send_head == skb)
		sk->sk_send_head = new;
1422 1423 1424 1425 1426 1427 1428
}

static inline void tcp_unlink_write_queue(struct sk_buff *skb, struct sock *sk)
{
	__skb_unlink(skb, &sk->sk_write_queue);
}

E
Eric Dumazet 已提交
1429
static inline bool tcp_write_queue_empty(struct sock *sk)
1430 1431 1432 1433
{
	return skb_queue_empty(&sk->sk_write_queue);
}

1434 1435 1436 1437 1438 1439 1440 1441 1442
static inline void tcp_push_pending_frames(struct sock *sk)
{
	if (tcp_send_head(sk)) {
		struct tcp_sock *tp = tcp_sk(sk);

		__tcp_push_pending_frames(sk, tcp_current_mss(sk), tp->nonagle);
	}
}

1443 1444 1445
/* Start sequence of the skb just after the highest skb with SACKed
 * bit, valid only if sacked_out > 0 or when the caller has ensured
 * validity by itself.
1446 1447 1448 1449 1450
 */
static inline u32 tcp_highest_sack_seq(struct tcp_sock *tp)
{
	if (!tp->sacked_out)
		return tp->snd_una;
1451 1452 1453 1454

	if (tp->highest_sack == NULL)
		return tp->snd_nxt;

1455 1456 1457
	return TCP_SKB_CB(tp->highest_sack)->seq;
}

1458 1459 1460 1461 1462 1463 1464 1465 1466 1467 1468 1469 1470 1471 1472 1473 1474 1475 1476 1477 1478 1479 1480 1481 1482
static inline void tcp_advance_highest_sack(struct sock *sk, struct sk_buff *skb)
{
	tcp_sk(sk)->highest_sack = tcp_skb_is_last(sk, skb) ? NULL :
						tcp_write_queue_next(sk, skb);
}

static inline struct sk_buff *tcp_highest_sack(struct sock *sk)
{
	return tcp_sk(sk)->highest_sack;
}

static inline void tcp_highest_sack_reset(struct sock *sk)
{
	tcp_sk(sk)->highest_sack = tcp_write_queue_head(sk);
}

/* Called when old skb is about to be deleted (to be combined with new skb) */
static inline void tcp_highest_sack_combine(struct sock *sk,
					    struct sk_buff *old,
					    struct sk_buff *new)
{
	if (tcp_sk(sk)->sacked_out && (old == tcp_sk(sk)->highest_sack))
		tcp_sk(sk)->highest_sack = new;
}

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/* Determines whether this is a thin stream (which may suffer from
 * increased latency). Used to trigger latency-reducing mechanisms.
 */
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static inline bool tcp_stream_is_thin(struct tcp_sock *tp)
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{
	return tp->packets_out < 4 && !tcp_in_initial_slowstart(tp);
}

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/* /proc */
enum tcp_seq_states {
	TCP_SEQ_STATE_LISTENING,
	TCP_SEQ_STATE_OPENREQ,
	TCP_SEQ_STATE_ESTABLISHED,
	TCP_SEQ_STATE_TIME_WAIT,
};

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int tcp_seq_open(struct inode *inode, struct file *file);

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struct tcp_seq_afinfo {
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	char				*name;
	sa_family_t			family;
	const struct file_operations	*seq_fops;
	struct seq_operations		seq_ops;
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};

struct tcp_iter_state {
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	struct seq_net_private	p;
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	sa_family_t		family;
	enum tcp_seq_states	state;
	struct sock		*syn_wait_sk;
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	int			bucket, offset, sbucket, num, uid;
	loff_t			last_pos;
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};

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extern int tcp_proc_register(struct net *net, struct tcp_seq_afinfo *afinfo);
extern void tcp_proc_unregister(struct net *net, struct tcp_seq_afinfo *afinfo);
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extern struct request_sock_ops tcp_request_sock_ops;
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extern struct request_sock_ops tcp6_request_sock_ops;
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extern void tcp_v4_destroy_sock(struct sock *sk);
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extern int tcp_v4_gso_send_check(struct sk_buff *skb);
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extern struct sk_buff *tcp_tso_segment(struct sk_buff *skb,
				       netdev_features_t features);
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extern struct sk_buff **tcp_gro_receive(struct sk_buff **head,
					struct sk_buff *skb);
extern struct sk_buff **tcp4_gro_receive(struct sk_buff **head,
					 struct sk_buff *skb);
extern int tcp_gro_complete(struct sk_buff *skb);
extern int tcp4_gro_complete(struct sk_buff *skb);
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#ifdef CONFIG_PROC_FS
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extern int tcp4_proc_init(void);
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extern void tcp4_proc_exit(void);
#endif

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/* TCP af-specific functions */
struct tcp_sock_af_ops {
#ifdef CONFIG_TCP_MD5SIG
	struct tcp_md5sig_key	*(*md5_lookup) (struct sock *sk,
						struct sock *addr_sk);
	int			(*calc_md5_hash) (char *location,
						  struct tcp_md5sig_key *md5,
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						  const struct sock *sk,
						  const struct request_sock *req,
						  const struct sk_buff *skb);
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	int			(*md5_parse) (struct sock *sk,
					      char __user *optval,
					      int optlen);
#endif
};

struct tcp_request_sock_ops {
#ifdef CONFIG_TCP_MD5SIG
	struct tcp_md5sig_key	*(*md5_lookup) (struct sock *sk,
						struct request_sock *req);
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	int			(*calc_md5_hash) (char *location,
						  struct tcp_md5sig_key *md5,
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						  const struct sock *sk,
						  const struct request_sock *req,
						  const struct sk_buff *skb);
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#endif
};

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/* Using SHA1 for now, define some constants.
 */
#define COOKIE_DIGEST_WORDS (SHA_DIGEST_WORDS)
#define COOKIE_MESSAGE_WORDS (SHA_MESSAGE_BYTES / 4)
#define COOKIE_WORKSPACE_WORDS (COOKIE_DIGEST_WORDS + COOKIE_MESSAGE_WORDS)

extern int tcp_cookie_generator(u32 *bakery);

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/**
 *	struct tcp_cookie_values - each socket needs extra space for the
 *	cookies, together with (optional) space for any SYN data.
 *
 *	A tcp_sock contains a pointer to the current value, and this is
 *	cloned to the tcp_timewait_sock.
 *
 * @cookie_pair:	variable data from the option exchange.
 *
 * @cookie_desired:	user specified tcpct_cookie_desired.  Zero
 *			indicates default (sysctl_tcp_cookie_size).
 *			After cookie sent, remembers size of cookie.
 *			Range 0, TCP_COOKIE_MIN to TCP_COOKIE_MAX.
 *
 * @s_data_desired:	user specified tcpct_s_data_desired.  When the
 *			constant payload is specified (@s_data_constant),
 *			holds its length instead.
 *			Range 0 to TCP_MSS_DESIRED.
 *
 * @s_data_payload:	constant data that is to be included in the
 *			payload of SYN or SYNACK segments when the
 *			cookie option is present.
 */
struct tcp_cookie_values {
	struct kref	kref;
	u8		cookie_pair[TCP_COOKIE_PAIR_SIZE];
	u8		cookie_pair_size;
	u8		cookie_desired;
	u16		s_data_desired:11,
			s_data_constant:1,
			s_data_in:1,
			s_data_out:1,
			s_data_unused:2;
	u8		s_data_payload[0];
};

static inline void tcp_cookie_values_release(struct kref *kref)
{
	kfree(container_of(kref, struct tcp_cookie_values, kref));
}

/* The length of constant payload data.  Note that s_data_desired is
 * overloaded, depending on s_data_constant: either the length of constant
 * data (returned here) or the limit on variable data.
 */
static inline int tcp_s_data_size(const struct tcp_sock *tp)
{
	return (tp->cookie_values != NULL && tp->cookie_values->s_data_constant)
		? tp->cookie_values->s_data_desired
		: 0;
}

/**
 *	struct tcp_extend_values - tcp_ipv?.c to tcp_output.c workspace.
 *
 *	As tcp_request_sock has already been extended in other places, the
 *	only remaining method is to pass stack values along as function
 *	parameters.  These parameters are not needed after sending SYNACK.
 *
 * @cookie_bakery:	cryptographic secret and message workspace.
 *
 * @cookie_plus:	bytes in authenticator/cookie option, copied from
 *			struct tcp_options_received (above).
 */
struct tcp_extend_values {
	struct request_values		rv;
	u32				cookie_bakery[COOKIE_WORKSPACE_WORDS];
	u8				cookie_plus:6,
					cookie_out_never:1,
					cookie_in_always:1;
};

static inline struct tcp_extend_values *tcp_xv(struct request_values *rvp)
{
	return (struct tcp_extend_values *)rvp;
}

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extern void tcp_v4_init(void);
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extern void tcp_init(void);

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#endif	/* _TCP_H */