tcp.h 48.9 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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/*
 *     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_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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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;
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 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_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 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);
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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);
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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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/* 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 *);
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/* From net/ipv6/syncookies.c */
extern struct sock *cookie_v6_check(struct sock *sk, struct sk_buff *skb);
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#ifdef CONFIG_SYN_COOKIES
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extern __u32 cookie_v6_init_sequence(struct sock *sk, const struct sk_buff *skb,
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				     __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);
483
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);
494
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);

498 499
/* tcp_input.c */
extern void tcp_cwnd_application_limited(struct sock *sk);
500 501
extern void tcp_resume_early_retransmit(struct sock *sk);
extern void tcp_rearm_rto(struct sock *sk);
502

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/* tcp_timer.c */
extern void tcp_init_xmit_timers(struct sock *);
505 506 507 508
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)
{
516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531
	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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536
/* tcp.c */
537
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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547 548
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);
550
extern void tcp_valid_rtt_meas(struct sock *sk, u32 seq_rtt);
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552 553 554 555 556 557 558 559 560 561 562
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;
}

563 564
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);
}

577
static inline void tcp_fast_path_check(struct sock *sk)
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{
579 580
	struct tcp_sock *tp = tcp_sk(sk);

581
	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);
}

588 589 590
/* Compute the actual rto_min value */
static inline u32 tcp_rto_min(struct sock *sk)
{
591
	const struct dst_entry *dst = __sk_dst_get(sk);
592 593 594 595 596 597 598
	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
S
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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
640 641 642 643
 * 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])	*/
656

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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)

665 666
	__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]))

672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687
/* 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)
{
693
	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)
{
699
	return skb_shinfo(skb)->gso_size;
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}

702 703 704 705 706 707 708 709 710 711 712 713 714 715 716
/* 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
717 718 719
#define TCP_CA_MAX	128
#define TCP_CA_BUF_MAX	(TCP_CA_NAME_MAX*TCP_CA_MAX)

720 721 722
#define TCP_CONG_NON_RESTRICTED 0x1
#define TCP_CONG_RTT_STAMP	0x2

723 724
struct tcp_congestion_ops {
	struct list_head	list;
725
	unsigned long flags;
726 727

	/* initialize private data (optional) */
728
	void (*init)(struct sock *sk);
729
	/* cleanup private data  (optional) */
730
	void (*release)(struct sock *sk);
731 732

	/* return slow start threshold (required) */
733
	u32 (*ssthresh)(struct sock *sk);
734
	/* lower bound for congestion window (optional) */
735
	u32 (*min_cwnd)(const struct sock *sk);
736
	/* do new cwnd calculation (required) */
737
	void (*cong_avoid)(struct sock *sk, u32 ack, u32 in_flight);
738
	/* call before changing ca_state (optional) */
739
	void (*set_state)(struct sock *sk, u8 new_state);
740
	/* call when cwnd event occurs (optional) */
741
	void (*cwnd_event)(struct sock *sk, enum tcp_ca_event ev);
742
	/* new value of cwnd after loss (optional) */
743
	u32  (*undo_cwnd)(struct sock *sk);
744
	/* hook for packet ack accounting (optional) */
745
	void (*pkts_acked)(struct sock *sk, u32 num_acked, s32 rtt_us);
746
	/* get info for inet_diag (optional) */
747
	void (*get_info)(struct sock *sk, u32 ext, struct sk_buff *skb);
748 749 750 751 752 753 754 755

	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);

756 757
extern void tcp_init_congestion_control(struct sock *sk);
extern void tcp_cleanup_congestion_control(struct sock *sk);
758 759
extern int tcp_set_default_congestion_control(const char *name);
extern void tcp_get_default_congestion_control(char *name);
760
extern void tcp_get_available_congestion_control(char *buf, size_t len);
761 762
extern void tcp_get_allowed_congestion_control(char *buf, size_t len);
extern int tcp_set_allowed_congestion_control(char *allowed);
763
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);
765
extern void tcp_cong_avoid_ai(struct tcp_sock *tp, u32 w);
766

767
extern struct tcp_congestion_ops tcp_init_congestion_ops;
768
extern u32 tcp_reno_ssthresh(struct sock *sk);
769
extern void tcp_reno_cong_avoid(struct sock *sk, u32 ack, u32 in_flight);
770
extern u32 tcp_reno_min_cwnd(const struct sock *sk);
771
extern struct tcp_congestion_ops tcp_reno;
772

773
static inline void tcp_set_ca_state(struct sock *sk, const u8 ca_state)
774
{
775 776 777 778 779
	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;
780 781
}

782
static inline void tcp_ca_event(struct sock *sk, const enum tcp_ca_event event)
783
{
784 785 786 787
	const struct inet_connection_sock *icsk = inet_csk(sk);

	if (icsk->icsk_ca_ops->cwnd_event)
		icsk->icsk_ca_ops->cwnd_event(sk, event);
788 789
}

790 791 792 793 794 795 796 797 798 799 800 801 802
/* 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)
804 805 806 807
{
	return !tcp_is_sack(tp);
}

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808
static inline bool tcp_is_fack(const struct tcp_sock *tp)
809
{
810
	return tp->rx_opt.sack_ok & TCP_FACK_ENABLED;
811 812 813 814
}

static inline void tcp_enable_fack(struct tcp_sock *tp)
{
815
	tp->rx_opt.sack_ok |= TCP_FACK_ENABLED;
816 817
}

Y
Yuchung Cheng 已提交
818 819 820 821 822 823 824
/* 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;
825
	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;
}

833 834 835 836 837
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)
L
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{
854
	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.
 */
868
static inline __u32 tcp_current_ssthresh(const struct sock *sk)
L
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{
870
	const struct tcp_sock *tp = tcp_sk(sk);
871

872
	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)));
}

880 881
/* 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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883
extern void tcp_enter_cwr(struct sock *sk, const int set_ssthresh);
884
extern __u32 tcp_init_cwnd(const struct tcp_sock *tp, const struct dst_entry *dst);
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886 887 888 889 890 891 892 893
/* 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
895 896 897 898
 * 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)
{
902
	return tp->reordering;
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}

905 906 907 908 909
/* 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);
911

912
static inline void tcp_minshall_update(struct tcp_sock *tp, unsigned int mss,
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913
				       const struct sk_buff *skb)
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{
	if (skb->len < mss)
		tp->snd_sml = TCP_SKB_CB(skb)->end_seq;
}

919
static inline void tcp_check_probe_timer(struct sock *sk)
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920
{
921
	const struct tcp_sock *tp = tcp_sk(sk);
922
	const struct inet_connection_sock *icsk = inet_csk(sk);
923

924
	if (!tp->packets_out && !icsk->icsk_pending)
925 926
		inet_csk_reset_xmit_timer(sk, ICSK_TIME_PROBE0,
					  icsk->icsk_rto, TCP_RTO_MAX);
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}

929
static inline void tcp_init_wl(struct tcp_sock *tp, u32 seq)
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{
	tp->snd_wl1 = seq;
}

934
static inline void tcp_update_wl(struct tcp_sock *tp, u32 seq)
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{
	tp->snd_wl1 = seq;
}

/*
 * Calculate(/check) TCP checksum
 */
942 943
static inline __sum16 tcp_v4_check(int len, __be32 saddr,
				   __be32 daddr, __wsum base)
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{
	return csum_tcpudp_magic(saddr,daddr,len,IPPROTO_TCP,base);
}

948
static inline __sum16 __tcp_checksum_complete(struct sk_buff *skb)
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949
{
950
	return __skb_checksum_complete(skb);
L
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951 952
}

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Eric Dumazet 已提交
953
static inline bool tcp_checksum_complete(struct sk_buff *skb)
L
Linus Torvalds 已提交
954
{
955
	return !skb_csum_unnecessary(skb) &&
L
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956 957 958 959 960
		__tcp_checksum_complete(skb);
}

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

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static inline void tcp_prequeue_init(struct tcp_sock *tp)
L
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{
	tp->ucopy.task = NULL;
	tp->ucopy.len = 0;
	tp->ucopy.memory = 0;
	skb_queue_head_init(&tp->ucopy.prequeue);
967 968 969 970 971 972
#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
973 974 975 976 977 978 979 980 981 982
}

/* 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
983
static inline bool tcp_prequeue(struct sock *sk, struct sk_buff *skb)
L
Linus Torvalds 已提交
984 985 986
{
	struct tcp_sock *tp = tcp_sk(sk);

E
Eric Dumazet 已提交
987
	if (sysctl_tcp_low_latency || !tp->ucopy.task)
E
Eric Dumazet 已提交
988
		return false;
E
Eric Dumazet 已提交
989 990 991 992 993 994 995 996 997 998 999 1000

	__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
1001
		}
E
Eric Dumazet 已提交
1002 1003 1004

		tp->ucopy.memory = 0;
	} else if (skb_queue_len(&tp->ucopy.prequeue) == 1) {
E
Eric Dumazet 已提交
1005
		wake_up_interruptible_sync_poll(sk_sleep(sk),
1006
					   POLLIN | POLLRDNORM | POLLRDBAND);
E
Eric Dumazet 已提交
1007 1008
		if (!inet_csk_ack_scheduled(sk))
			inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK,
1009
						  (3 * tcp_rto_min(sk)) / 4,
E
Eric Dumazet 已提交
1010
						  TCP_RTO_MAX);
L
Linus Torvalds 已提交
1011
	}
E
Eric Dumazet 已提交
1012
	return true;
L
Linus Torvalds 已提交
1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024
}


#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
1025
extern void tcp_set_state(struct sock *sk, int state);
L
Linus Torvalds 已提交
1026

A
Andi Kleen 已提交
1027
extern void tcp_done(struct sock *sk);
L
Linus Torvalds 已提交
1028

S
Stephen Hemminger 已提交
1029
static inline void tcp_sack_reset(struct tcp_options_received *rx_opt)
L
Linus Torvalds 已提交
1030 1031 1032 1033 1034 1035 1036 1037
{
	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,
1038 1039
				      int wscale_ok, __u8 *rcv_wscale,
				      __u32 init_rcv_wnd);
L
Linus Torvalds 已提交
1040 1041 1042 1043 1044 1045 1046 1047 1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058 1059

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
1060 1061 1062
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
1063
{
1064 1065
	struct inet_request_sock *ireq = inet_rsk(req);

L
Linus Torvalds 已提交
1066
	req->rcv_wnd = 0;		/* So that tcp_send_synack() knows! */
1067
	req->cookie_ts = 0;
1068
	tcp_rsk(req)->rcv_isn = TCP_SKB_CB(skb)->seq;
L
Linus Torvalds 已提交
1069 1070
	req->mss = rx_opt->mss_clamp;
	req->ts_recent = rx_opt->saw_tstamp ? rx_opt->rcv_tsval : 0;
1071 1072 1073 1074 1075 1076
	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;
1077
	ireq->rmt_port = tcp_hdr(skb)->source;
1078
	ireq->loc_port = tcp_hdr(skb)->dest;
L
Linus Torvalds 已提交
1079 1080
}

1081
extern void tcp_enter_memory_pressure(struct sock *sk);
L
Linus Torvalds 已提交
1082 1083 1084 1085 1086 1087 1088 1089 1090 1091 1092

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
1093 1094 1095 1096 1097
static inline int keepalive_probes(const struct tcp_sock *tp)
{
	return tp->keepalive_probes ? : sysctl_tcp_keepalive_probes;
}

1098 1099 1100 1101 1102 1103 1104 1105
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);
}

1106
static inline int tcp_fin_time(const struct sock *sk)
L
Linus Torvalds 已提交
1107
{
1108 1109
	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
1110

1111 1112
	if (fin_timeout < (rto << 2) - (rto >> 1))
		fin_timeout = (rto << 2) - (rto >> 1);
L
Linus Torvalds 已提交
1113 1114 1115 1116

	return fin_timeout;
}

E
Eric Dumazet 已提交
1117 1118
static inline bool tcp_paws_check(const struct tcp_options_received *rx_opt,
				  int paws_win)
L
Linus Torvalds 已提交
1119
{
I
Ilpo Järvinen 已提交
1120
	if ((s32)(rx_opt->ts_recent - rx_opt->rcv_tsval) <= paws_win)
E
Eric Dumazet 已提交
1121
		return true;
I
Ilpo Järvinen 已提交
1122
	if (unlikely(get_seconds() >= rx_opt->ts_recent_stamp + TCP_PAWS_24DAYS))
E
Eric Dumazet 已提交
1123
		return true;
E
Eric Dumazet 已提交
1124 1125 1126 1127 1128 1129
	/*
	 * 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
1130 1131
		return true;
	return false;
I
Ilpo Järvinen 已提交
1132 1133
}

E
Eric Dumazet 已提交
1134 1135
static inline bool tcp_paws_reject(const struct tcp_options_received *rx_opt,
				   int rst)
I
Ilpo Järvinen 已提交
1136 1137
{
	if (tcp_paws_check(rx_opt, 0))
E
Eric Dumazet 已提交
1138
		return false;
L
Linus Torvalds 已提交
1139 1140 1141 1142 1143 1144 1145 1146 1147 1148 1149 1150 1151

	/* 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.
	 */
1152
	if (rst && get_seconds() >= rx_opt->ts_recent_stamp + TCP_PAWS_MSL)
E
Eric Dumazet 已提交
1153 1154
		return false;
	return true;
L
Linus Torvalds 已提交
1155 1156
}

P
Pavel Emelyanov 已提交
1157
static inline void tcp_mib_init(struct net *net)
L
Linus Torvalds 已提交
1158 1159
{
	/* See RFC 2012 */
1160 1161 1162 1163
	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
1164 1165
}

1166
/* from STCP */
1167
static inline void tcp_clear_retrans_hints_partial(struct tcp_sock *tp)
D
David S. Miller 已提交
1168
{
1169 1170
	tp->lost_skb_hint = NULL;
	tp->scoreboard_skb_hint = NULL;
1171 1172 1173 1174 1175
}

static inline void tcp_clear_all_retrans_hints(struct tcp_sock *tp)
{
	tcp_clear_retrans_hints_partial(tp);
1176
	tp->retransmit_skb_hint = NULL;
1177 1178
}

1179 1180 1181
/* MD5 Signature */
struct crypto_hash;

E
Eric Dumazet 已提交
1182 1183 1184 1185 1186 1187 1188
union tcp_md5_addr {
	struct in_addr  a4;
#if IS_ENABLED(CONFIG_IPV6)
	struct in6_addr	a6;
#endif
};

1189 1190
/* - key database */
struct tcp_md5sig_key {
E
Eric Dumazet 已提交
1191
	struct hlist_node	node;
1192
	u8			keylen;
E
Eric Dumazet 已提交
1193 1194 1195 1196
	u8			family; /* AF_INET or AF_INET6 */
	union tcp_md5_addr	addr;
	u8			key[TCP_MD5SIG_MAXKEYLEN];
	struct rcu_head		rcu;
1197 1198 1199 1200
};

/* - sock block */
struct tcp_md5sig_info {
E
Eric Dumazet 已提交
1201
	struct hlist_head	head;
1202
	struct rcu_head		rcu;
1203 1204 1205 1206 1207 1208 1209 1210 1211 1212 1213 1214 1215 1216 1217 1218 1219 1220 1221 1222
};

/* - 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
1223
#if IS_ENABLED(CONFIG_IPV6)
1224 1225 1226 1227 1228 1229 1230 1231 1232 1233 1234
	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
1235
extern int tcp_v4_md5_hash_skb(char *md5_hash, struct tcp_md5sig_key *key,
E
Eric Dumazet 已提交
1236 1237 1238
			       const struct sock *sk,
			       const struct request_sock *req,
			       const struct sk_buff *skb);
E
Eric Dumazet 已提交
1239 1240 1241 1242 1243 1244 1245
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);
1246

1247
#ifdef CONFIG_TCP_MD5SIG
E
Eric Dumazet 已提交
1248 1249 1250
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)
1251
#else
E
Eric Dumazet 已提交
1252 1253 1254 1255 1256 1257
static inline struct tcp_md5sig_key *tcp_md5_do_lookup(struct sock *sk,
					 const union tcp_md5_addr *addr,
					 int family)
{
	return NULL;
}
1258 1259 1260
#define tcp_twsk_md5_key(twsk)	NULL
#endif

1261
extern struct tcp_md5sig_pool __percpu *tcp_alloc_md5sig_pool(struct sock *);
C
Changli Gao 已提交
1262
extern void tcp_free_md5sig_pool(void);
1263

E
Eric Dumazet 已提交
1264
extern struct tcp_md5sig_pool	*tcp_get_md5sig_pool(void);
C
Changli Gao 已提交
1265
extern void tcp_put_md5sig_pool(void);
E
Eric Dumazet 已提交
1266

1267
extern int tcp_md5_hash_header(struct tcp_md5sig_pool *, const struct tcphdr *);
1268
extern int tcp_md5_hash_skb_data(struct tcp_md5sig_pool *, const struct sk_buff *,
1269
				 unsigned int header_len);
1270
extern int tcp_md5_hash_key(struct tcp_md5sig_pool *hp,
1271
			    const struct tcp_md5sig_key *key);
1272

1273 1274 1275 1276 1277 1278
/* 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)
1279 1280
		sk_wmem_free_skb(sk, skb);
	sk_mem_reclaim(sk);
1281
	tcp_clear_all_retrans_hints(tcp_sk(sk));
1282 1283
}

1284
static inline struct sk_buff *tcp_write_queue_head(const struct sock *sk)
1285
{
1286
	return skb_peek(&sk->sk_write_queue);
1287 1288
}

1289
static inline struct sk_buff *tcp_write_queue_tail(const struct sock *sk)
1290
{
1291
	return skb_peek_tail(&sk->sk_write_queue);
1292 1293
}

1294 1295
static inline struct sk_buff *tcp_write_queue_next(const struct sock *sk,
						   const struct sk_buff *skb)
1296
{
1297
	return skb_queue_next(&sk->sk_write_queue, skb);
1298 1299
}

1300 1301
static inline struct sk_buff *tcp_write_queue_prev(const struct sock *sk,
						   const struct sk_buff *skb)
1302 1303 1304 1305
{
	return skb_queue_prev(&sk->sk_write_queue, skb);
}

1306
#define tcp_for_write_queue(skb, sk)					\
1307
	skb_queue_walk(&(sk)->sk_write_queue, skb)
1308 1309

#define tcp_for_write_queue_from(skb, sk)				\
1310
	skb_queue_walk_from(&(sk)->sk_write_queue, skb)
1311

1312
#define tcp_for_write_queue_from_safe(skb, tmp, sk)			\
1313
	skb_queue_walk_from_safe(&(sk)->sk_write_queue, skb, tmp)
1314

1315
static inline struct sk_buff *tcp_send_head(const struct sock *sk)
1316 1317 1318 1319
{
	return sk->sk_send_head;
}

1320 1321 1322 1323 1324 1325
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);
}

1326
static inline void tcp_advance_send_head(struct sock *sk, const struct sk_buff *skb)
1327
{
1328
	if (tcp_skb_is_last(sk, skb))
1329
		sk->sk_send_head = NULL;
1330 1331
	else
		sk->sk_send_head = tcp_write_queue_next(sk, skb);
1332 1333 1334 1335 1336 1337 1338 1339 1340 1341 1342 1343 1344 1345 1346 1347 1348 1349 1350 1351 1352 1353 1354
}

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. */
1355
	if (sk->sk_send_head == NULL) {
1356
		sk->sk_send_head = skb;
1357 1358 1359 1360

		if (tcp_sk(sk)->highest_sack == NULL)
			tcp_sk(sk)->highest_sack = skb;
	}
1361 1362 1363 1364 1365 1366 1367 1368 1369 1370 1371 1372
}

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)
{
1373
	__skb_queue_after(&sk->sk_write_queue, skb, buff);
1374 1375
}

1376
/* Insert new before skb on the write queue of sk.  */
1377 1378 1379 1380
static inline void tcp_insert_write_queue_before(struct sk_buff *new,
						  struct sk_buff *skb,
						  struct sock *sk)
{
1381
	__skb_queue_before(&sk->sk_write_queue, skb, new);
1382 1383 1384

	if (sk->sk_send_head == skb)
		sk->sk_send_head = new;
1385 1386 1387 1388 1389 1390 1391
}

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
1392
static inline bool tcp_write_queue_empty(struct sock *sk)
1393 1394 1395 1396
{
	return skb_queue_empty(&sk->sk_write_queue);
}

1397 1398 1399 1400 1401 1402 1403 1404 1405
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);
	}
}

1406 1407 1408
/* 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.
1409 1410 1411 1412 1413
 */
static inline u32 tcp_highest_sack_seq(struct tcp_sock *tp)
{
	if (!tp->sacked_out)
		return tp->snd_una;
1414 1415 1416 1417

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

1418 1419 1420
	return TCP_SKB_CB(tp->highest_sack)->seq;
}

1421 1422 1423 1424 1425 1426 1427 1428 1429 1430 1431 1432 1433 1434 1435 1436 1437 1438 1439 1440 1441 1442 1443 1444 1445
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;
}

A
Andreas Petlund 已提交
1446 1447 1448
/* Determines whether this is a thin stream (which may suffer from
 * increased latency). Used to trigger latency-reducing mechanisms.
 */
E
Eric Dumazet 已提交
1449
static inline bool tcp_stream_is_thin(struct tcp_sock *tp)
A
Andreas Petlund 已提交
1450 1451 1452 1453
{
	return tp->packets_out < 4 && !tcp_in_initial_slowstart(tp);
}

L
Linus Torvalds 已提交
1454 1455 1456 1457 1458 1459 1460 1461
/* /proc */
enum tcp_seq_states {
	TCP_SEQ_STATE_LISTENING,
	TCP_SEQ_STATE_OPENREQ,
	TCP_SEQ_STATE_ESTABLISHED,
	TCP_SEQ_STATE_TIME_WAIT,
};

1462 1463
int tcp_seq_open(struct inode *inode, struct file *file);

L
Linus Torvalds 已提交
1464
struct tcp_seq_afinfo {
1465 1466 1467 1468
	char				*name;
	sa_family_t			family;
	const struct file_operations	*seq_fops;
	struct seq_operations		seq_ops;
L
Linus Torvalds 已提交
1469 1470 1471
};

struct tcp_iter_state {
1472
	struct seq_net_private	p;
L
Linus Torvalds 已提交
1473 1474 1475
	sa_family_t		family;
	enum tcp_seq_states	state;
	struct sock		*syn_wait_sk;
1476 1477
	int			bucket, offset, sbucket, num, uid;
	loff_t			last_pos;
L
Linus Torvalds 已提交
1478 1479
};

1480 1481
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);
L
Linus Torvalds 已提交
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1483
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 */