Moved, renamed, and deleted files

The original directory structure was scattered and unorganized.
Changes are basically to make it look like kernel structure.

1 files changed, 1581 insertions, 0 deletions

diff --git a/include/net/tcp.h b/include/net/tcp.h
new file mode 100644
index 00000000..50660b3e
--- /dev/null
+++ b/include/net/tcp.h
@@ -0,0 +1,1581 @@
+/*
+ * 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
+ *
+ * Authors:	Ross Biro
+ *		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>
+#include <linux/bug.h>
+#include <linux/slab.h>
+#include <linux/cache.h>
+#include <linux/percpu.h>
+#include <linux/skbuff.h>
+#include <linux/dmaengine.h>
+#include <linux/crypto.h>
+#include <linux/cryptohash.h>
+#include <linux/kref.h>
+
+#include <net/inet_connection_sock.h>
+#include <net/inet_timewait_sock.h>
+#include <net/inet_hashtables.h>
+#include <net/checksum.h>
+#include <net/request_sock.h>
+#include <net/sock.h>
+#include <net/snmp.h>
+#include <net/ip.h>
+#include <net/tcp_states.h>
+#include <net/inet_ecn.h>
+#include <net/dst.h>
+
+#include <linux/seq_file.h>
+#include <linux/memcontrol.h>
+
+extern struct inet_hashinfo tcp_hashinfo;
+
+extern struct percpu_counter tcp_orphan_count;
+extern void tcp_time_wait(struct sock *sk, int state, int timeo);
+
+#define MAX_TCP_HEADER	(128 + MAX_HEADER)
+#define MAX_TCP_OPTION_SPACE 40
+
+/* 
+ * Never offer a window over 32767 without using window scaling. Some
+ * poor stacks do signed 16bit maths! 
+ */
+#define MAX_TCP_WINDOW		32767U
+
+/* Offer an initial receive window of 10 mss. */
+#define TCP_DEFAULT_INIT_RCVWND	10
+
+/* Minimal accepted MSS. It is (60+60+8) - (20+20). */
+#define TCP_MIN_MSS		88U
+
+/* The least MTU to use for probing */
+#define TCP_BASE_MSS		512
+
+/* 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
+				 * connection: ~180sec is RFC minimum	*/
+
+#define TCP_SYNACK_RETRIES 5	/* number of times to retry passive opening a
+				 * connection: ~180sec is RFC minimum	*/
+
+#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))
+#define TCP_TIMEOUT_INIT ((unsigned)(1*HZ))	/* RFC2988bis initial RTO value	*/
+#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.
+						 */
+
+#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 */
+#define TCPOPT_MD5SIG		19	/* MD5 Signature (RFC2385) */
+#define TCPOPT_COOKIE		253	/* Cookie extension (experimental) */
+
+/*
+ *     TCP option lengths
+ */
+
+#define TCPOLEN_MSS            4
+#define TCPOLEN_WINDOW         3
+#define TCPOLEN_SACK_PERM      2
+#define TCPOLEN_TIMESTAMP      10
+#define TCPOLEN_MD5SIG         18
+#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)
+
+/* 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
+#define TCPOLEN_MD5SIG_ALIGNED		20
+#define TCPOLEN_MSS_ALIGNED		4
+
+/* Flags in tp->nonagle */
+#define TCP_NAGLE_OFF		1	/* Nagle's algo is disabled */
+#define TCP_NAGLE_CORK		2	/* Socket is corked	    */
+#define TCP_NAGLE_PUSH		4	/* Cork is overridden for already queued data */
+
+/* TCP thin-stream limits */
+#define TCP_THIN_LINEAR_RETRIES 6       /* After 6 linear retries, do exp. backoff */
+
+/* TCP initial congestion window as per draft-hkchu-tcpm-initcwnd-01 */
+#define TCP_INIT_CWND		10
+
+extern struct inet_timewait_death_row tcp_death_row;
+
+/* 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;
+extern int sysctl_tcp_frto_response;
+extern int sysctl_tcp_low_latency;
+extern int sysctl_tcp_dma_copybreak;
+extern int sysctl_tcp_nometrics_save;
+extern int sysctl_tcp_moderate_rcvbuf;
+extern int sysctl_tcp_tso_win_divisor;
+extern int sysctl_tcp_abc;
+extern int sysctl_tcp_mtu_probing;
+extern int sysctl_tcp_base_mss;
+extern int sysctl_tcp_workaround_signed_windows;
+extern int sysctl_tcp_slow_start_after_idle;
+extern int sysctl_tcp_max_ssthresh;
+extern int sysctl_tcp_cookie_size;
+extern int sysctl_tcp_thin_linear_timeouts;
+extern int sysctl_tcp_thin_dupack;
+
+extern atomic_long_t tcp_memory_allocated;
+extern struct percpu_counter tcp_sockets_allocated;
+extern int tcp_memory_pressure;
+
+/*
+ * The next routines deal with comparing 32 bit unsigned ints
+ * and worry about wraparound (automatic with unsigned arithmetic).
+ */
+
+static inline int before(__u32 seq1, __u32 seq2)
+{
+        return (__s32)(seq1-seq2) < 0;
+}
+#define after(seq2, seq1) 	before(seq1, seq2)
+
+/* is s2<=s1<=s3 ? */
+static inline int between(__u32 seq1, __u32 seq2, __u32 seq3)
+{
+	return seq3 - seq2 >= seq1 - seq2;
+}
+
+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;
+}
+
+static inline bool tcp_too_many_orphans(struct sock *sk, int shift)
+{
+	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;
+}
+
+extern bool tcp_check_oom(struct sock *sk, int shift);
+
+/* 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? */
+static inline int tcp_synq_no_recent_overflow(const struct sock *sk)
+{
+	unsigned long last_overflow = tcp_sk(sk)->rx_opt.ts_recent_stamp;
+	return time_after(jiffies, last_overflow + TCP_TIMEOUT_FALLBACK);
+}
+
+extern struct proto tcp_prot;
+
+#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)
+#define TCP_ADD_STATS(net, field, val)	SNMP_ADD_STATS((net)->mib.tcp_statistics, field, val)
+
+extern void tcp_init_mem(struct net *net);
+
+extern void tcp_v4_err(struct sk_buff *skb, u32);
+
+extern void tcp_shutdown (struct sock *sk, int how);
+
+extern int tcp_v4_rcv(struct sk_buff *skb);
+
+extern struct inet_peer *tcp_v4_get_peer(struct sock *sk, bool *release_it);
+extern void *tcp_v4_tw_get_peer(struct sock *sk);
+extern int tcp_v4_tw_remember_stamp(struct inet_timewait_sock *tw);
+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);
+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,
+				 const struct tcphdr *th, unsigned int len);
+extern int tcp_rcv_established(struct sock *sk, struct sk_buff *skb,
+			       const struct tcphdr *th, unsigned int len);
+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);
+
+static inline void tcp_dec_quickack_mode(struct sock *sk,
+					 const unsigned int pkts)
+{
+	struct inet_connection_sock *icsk = inet_csk(sk);
+
+	if (icsk->icsk_ack.quick) {
+		if (pkts >= icsk->icsk_ack.quick) {
+			icsk->icsk_ack.quick = 0;
+			/* Leaving quickack mode we deflate ATO. */
+			icsk->icsk_ack.ato   = TCP_ATO_MIN;
+		} else
+			icsk->icsk_ack.quick -= pkts;
+	}
+}
+
+#define	TCP_ECN_OK		1
+#define	TCP_ECN_QUEUE_CWR	2
+#define	TCP_ECN_DEMAND_CWR	4
+#define	TCP_ECN_SEEN		8
+
+static __inline__ void
+TCP_ECN_create_request(struct request_sock *req, struct tcphdr *th)
+{
+	if (sysctl_tcp_ecn && th->ece && th->cwr)
+		inet_rsk(req)->ecn_ok = 1;
+}
+
+enum tcp_tw_status {
+	TCP_TW_SUCCESS = 0,
+	TCP_TW_RST = 1,
+	TCP_TW_ACK = 2,
+	TCP_TW_SYN = 3
+};
+
+
+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);
+extern int tcp_use_frto(struct sock *sk);
+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);
+extern void tcp_close(struct sock *sk, long timeout);
+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);
+extern void tcp_parse_options(const struct sk_buff *skb,
+			      struct tcp_options_received *opt_rx, const u8 **hvpp,
+			      int estab);
+extern const u8 *tcp_parse_md5sig_option(const struct tcphdr *th);
+
+/*
+ *	TCP v4 functions exported for the inet6 API
+ */
+
+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,
+					      struct sk_buff *skb);
+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);
+
+
+/* From syncookies.c */
+extern __u32 syncookie_secret[2][16-4+SHA_DIGEST_WORDS];
+extern struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb, 
+				    struct ip_options *opt);
+#ifdef CONFIG_SYN_COOKIES
+extern __u32 cookie_v4_init_sequence(struct sock *sk, struct sk_buff *skb, 
+				     __u16 *mss);
+#else
+static inline __u32 cookie_v4_init_sequence(struct sock *sk,
+					    struct sk_buff *skb,
+					    __u16 *mss)
+{
+	return 0;
+}
+#endif
+
+extern __u32 cookie_init_timestamp(struct request_sock *req);
+extern bool cookie_check_timestamp(struct tcp_options_received *opt, bool *);
+
+/* From net/ipv6/syncookies.c */
+extern struct sock *cookie_v6_check(struct sock *sk, struct sk_buff *skb);
+#ifdef CONFIG_SYN_COOKIES
+extern __u32 cookie_v6_init_sequence(struct sock *sk, const struct sk_buff *skb,
+				     __u16 *mss);
+#else
+static inline __u32 cookie_v6_init_sequence(struct sock *sk,
+					    struct sk_buff *skb,
+					    __u16 *mss)
+{
+	return 0;
+}
+#endif
+/* tcp_output.c */
+
+extern void __tcp_push_pending_frames(struct sock *sk, unsigned int cur_mss,
+				      int nonagle);
+extern int tcp_may_send_now(struct sock *sk);
+extern int tcp_retransmit_skb(struct sock *, struct sk_buff *);
+extern void tcp_retransmit_timer(struct sock *sk);
+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);
+extern int tcp_fragment(struct sock *, struct sk_buff *, u32, unsigned int);
+
+extern void tcp_send_probe0(struct sock *);
+extern void tcp_send_partial(struct sock *);
+extern int tcp_write_wakeup(struct sock *);
+extern void tcp_send_fin(struct sock *sk);
+extern void tcp_send_active_reset(struct sock *sk, gfp_t priority);
+extern int tcp_send_synack(struct sock *);
+extern int tcp_syn_flood_action(struct sock *sk,
+				const struct sk_buff *skb,
+				const char *proto);
+extern void tcp_push_one(struct sock *, unsigned int mss_now);
+extern void tcp_send_ack(struct sock *sk);
+extern void tcp_send_delayed_ack(struct sock *sk);
+
+/* tcp_input.c */
+extern void tcp_cwnd_application_limited(struct sock *sk);
+
+/* tcp_timer.c */
+extern void tcp_init_xmit_timers(struct sock *);
+static inline void tcp_clear_xmit_timers(struct sock *sk)
+{
+	inet_csk_clear_xmit_timers(sk);
+}
+
+extern unsigned int tcp_sync_mss(struct sock *sk, u32 pmtu);
+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)
+{
+	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);
+	else
+		return pktsize;
+}
+
+/* tcp.c */
+extern void tcp_get_info(const struct sock *, struct tcp_info *);
+
+/* 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);
+
+extern void tcp_initialize_rcv_mss(struct sock *sk);
+
+extern int tcp_mtu_to_mss(const struct sock *sk, int pmtu);
+extern int tcp_mss_to_mtu(const struct sock *sk, int mss);
+extern void tcp_mtup_init(struct sock *sk);
+extern void tcp_valid_rtt_meas(struct sock *sk, u32 seq_rtt);
+
+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;
+}
+
+static inline void __tcp_fast_path_on(struct tcp_sock *tp, u32 snd_wnd)
+{
+	tp->pred_flags = htonl((tp->tcp_header_len << 26) |
+			       ntohl(TCP_FLAG_ACK) |
+			       snd_wnd);
+}
+
+static inline void tcp_fast_path_on(struct tcp_sock *tp)
+{
+	__tcp_fast_path_on(tp, tp->snd_wnd >> tp->rx_opt.snd_wscale);
+}
+
+static inline void tcp_fast_path_check(struct sock *sk)
+{
+	struct tcp_sock *tp = tcp_sk(sk);
+
+	if (skb_queue_empty(&tp->out_of_order_queue) &&
+	    tp->rcv_wnd &&
+	    atomic_read(&sk->sk_rmem_alloc) < sk->sk_rcvbuf &&
+	    !tp->urg_data)
+		tcp_fast_path_on(tp);
+}
+
+/* Compute the actual rto_min value */
+static inline u32 tcp_rto_min(struct sock *sk)
+{
+	const struct dst_entry *dst = __sk_dst_get(sk);
+	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;
+}
+
+/* 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.
+ */
+static inline u32 tcp_receive_window(const struct tcp_sock *tp)
+{
+	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.
+ */
+extern u32 __tcp_select_window(struct sock *sk);
+
+/* TCP timestamps are only 32-bits, this causes a slight
+ * complication on 64-bit systems since we store a snapshot
+ * of jiffies in the buffer control blocks below.  We decided
+ * to use only the low 32-bits of jiffies and hide the ugly
+ * casts with the following macro.
+ */
+#define tcp_time_stamp		((__u32)(jiffies))
+
+#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
+
+/* This is what the send packet queuing engine uses to pass
+ * 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.
+ */
+struct tcp_skb_cb {
+	union {
+		struct inet_skb_parm	h4;
+#if IS_ENABLED(CONFIG_IPV6)
+		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	*/
+	__u8		tcp_flags;	/* TCP header flags. (tcp[13])	*/
+	__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			*/
+	__u8		ip_dsfield;	/* IPv4 tos or IPv6 dsfield	*/
+	/* 1 byte hole */
+#define TCPCB_EVER_RETRANS	0x80	/* Ever retransmitted frame	*/
+#define TCPCB_RETRANS		(TCPCB_SACKED_RETRANS|TCPCB_EVER_RETRANS)
+
+	__u32		ack_seq;	/* Sequence number ACK'd	*/
+};
+
+#define TCP_SKB_CB(__skb)	((struct tcp_skb_cb *)&((__skb)->cb[0]))
+
+/* 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)
+{
+	return skb_shinfo(skb)->gso_segs;
+}
+
+/* This is valid iff tcp_skb_pcount() > 1. */
+static inline int tcp_skb_mss(const struct sk_buff *skb)
+{
+	return skb_shinfo(skb)->gso_size;
+}
+
+/* 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
+#define TCP_CA_MAX	128
+#define TCP_CA_BUF_MAX	(TCP_CA_NAME_MAX*TCP_CA_MAX)
+
+#define TCP_CONG_NON_RESTRICTED 0x1
+#define TCP_CONG_RTT_STAMP	0x2
+
+struct tcp_congestion_ops {
+	struct list_head	list;
+	unsigned long flags;
+
+	/* initialize private data (optional) */
+	void (*init)(struct sock *sk);
+	/* cleanup private data  (optional) */
+	void (*release)(struct sock *sk);
+
+	/* return slow start threshold (required) */
+	u32 (*ssthresh)(struct sock *sk);
+	/* lower bound for congestion window (optional) */
+	u32 (*min_cwnd)(const struct sock *sk);
+	/* do new cwnd calculation (required) */
+	void (*cong_avoid)(struct sock *sk, u32 ack, u32 in_flight);
+	/* call before changing ca_state (optional) */
+	void (*set_state)(struct sock *sk, u8 new_state);
+	/* call when cwnd event occurs (optional) */
+	void (*cwnd_event)(struct sock *sk, enum tcp_ca_event ev);
+	/* new value of cwnd after loss (optional) */
+	u32  (*undo_cwnd)(struct sock *sk);
+	/* hook for packet ack accounting (optional) */
+	void (*pkts_acked)(struct sock *sk, u32 num_acked, s32 rtt_us);
+	/* get info for inet_diag (optional) */
+	void (*get_info)(struct sock *sk, u32 ext, struct sk_buff *skb);
+
+	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);
+
+extern void tcp_init_congestion_control(struct sock *sk);
+extern void tcp_cleanup_congestion_control(struct sock *sk);
+extern int tcp_set_default_congestion_control(const char *name);
+extern void tcp_get_default_congestion_control(char *name);
+extern void tcp_get_available_congestion_control(char *buf, size_t len);
+extern void tcp_get_allowed_congestion_control(char *buf, size_t len);
+extern int tcp_set_allowed_congestion_control(char *allowed);
+extern int tcp_set_congestion_control(struct sock *sk, const char *name);
+extern void tcp_slow_start(struct tcp_sock *tp);
+extern void tcp_cong_avoid_ai(struct tcp_sock *tp, u32 w);
+
+extern struct tcp_congestion_ops tcp_init_congestion_ops;
+extern u32 tcp_reno_ssthresh(struct sock *sk);
+extern void tcp_reno_cong_avoid(struct sock *sk, u32 ack, u32 in_flight);
+extern u32 tcp_reno_min_cwnd(const struct sock *sk);
+extern struct tcp_congestion_ops tcp_reno;
+
+static inline void tcp_set_ca_state(struct sock *sk, const u8 ca_state)
+{
+	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;
+}
+
+static inline void tcp_ca_event(struct sock *sk, const enum tcp_ca_event event)
+{
+	const struct inet_connection_sock *icsk = inet_csk(sk);
+
+	if (icsk->icsk_ca_ops->cwnd_event)
+		icsk->icsk_ca_ops->cwnd_event(sk, event);
+}
+
+/* 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;
+}
+
+static inline int tcp_is_reno(const struct tcp_sock *tp)
+{
+	return !tcp_is_sack(tp);
+}
+
+static inline int tcp_is_fack(const struct tcp_sock *tp)
+{
+	return tp->rx_opt.sack_ok & TCP_FACK_ENABLED;
+}
+
+static inline void tcp_enable_fack(struct tcp_sock *tp)
+{
+	tp->rx_opt.sack_ok |= TCP_FACK_ENABLED;
+}
+
+static inline unsigned int tcp_left_out(const struct tcp_sock *tp)
+{
+	return tp->sacked_out + tp->lost_out;
+}
+
+/* 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"
+ */
+static inline unsigned int tcp_packets_in_flight(const struct tcp_sock *tp)
+{
+	return tp->packets_out - tcp_left_out(tp) + tp->retrans_out;
+}
+
+#define TCP_INFINITE_SSTHRESH	0x7fffffff
+
+static inline bool tcp_in_initial_slowstart(const struct tcp_sock *tp)
+{
+	return tp->snd_ssthresh >= TCP_INFINITE_SSTHRESH;
+}
+
+/* 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.
+ */
+static inline __u32 tcp_current_ssthresh(const struct sock *sk)
+{
+	const struct tcp_sock *tp = tcp_sk(sk);
+
+	if ((1 << inet_csk(sk)->icsk_ca_state) & (TCPF_CA_CWR | TCPF_CA_Recovery))
+		return tp->snd_ssthresh;
+	else
+		return max(tp->snd_ssthresh,
+			   ((tp->snd_cwnd >> 1) +
+			    (tp->snd_cwnd >> 2)));
+}
+
+/* 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)
+
+extern void tcp_enter_cwr(struct sock *sk, const int set_ssthresh);
+extern __u32 tcp_init_cwnd(const struct tcp_sock *tp, const struct dst_entry *dst);
+
+/* 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;
+}
+
+/* Slow start with delack produces 3 packets of burst, so that
+ * 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.
+ */
+static __inline__ __u32 tcp_max_burst(const struct tcp_sock *tp)
+{
+	return tp->reordering;
+}
+
+/* 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;
+}
+extern int tcp_is_cwnd_limited(const struct sock *sk, u32 in_flight);
+
+static inline void tcp_minshall_update(struct tcp_sock *tp, unsigned int mss,
+				       const struct sk_buff *skb)
+{
+	if (skb->len < mss)
+		tp->snd_sml = TCP_SKB_CB(skb)->end_seq;
+}
+
+static inline void tcp_check_probe_timer(struct sock *sk)
+{
+	const struct tcp_sock *tp = tcp_sk(sk);
+	const struct inet_connection_sock *icsk = inet_csk(sk);
+
+	if (!tp->packets_out && !icsk->icsk_pending)
+		inet_csk_reset_xmit_timer(sk, ICSK_TIME_PROBE0,
+					  icsk->icsk_rto, TCP_RTO_MAX);
+}
+
+static inline void tcp_init_wl(struct tcp_sock *tp, u32 seq)
+{
+	tp->snd_wl1 = seq;
+}
+
+static inline void tcp_update_wl(struct tcp_sock *tp, u32 seq)
+{
+	tp->snd_wl1 = seq;
+}
+
+/*
+ * Calculate(/check) TCP checksum
+ */
+static inline __sum16 tcp_v4_check(int len, __be32 saddr,
+				   __be32 daddr, __wsum base)
+{
+	return csum_tcpudp_magic(saddr,daddr,len,IPPROTO_TCP,base);
+}
+
+static inline __sum16 __tcp_checksum_complete(struct sk_buff *skb)
+{
+	return __skb_checksum_complete(skb);
+}
+
+static inline int tcp_checksum_complete(struct sk_buff *skb)
+{
+	return !skb_csum_unnecessary(skb) &&
+		__tcp_checksum_complete(skb);
+}
+
+/* Prequeue for VJ style copy to user, combined with checksumming. */
+
+static inline void tcp_prequeue_init(struct tcp_sock *tp)
+{
+	tp->ucopy.task = NULL;
+	tp->ucopy.len = 0;
+	tp->ucopy.memory = 0;
+	skb_queue_head_init(&tp->ucopy.prequeue);
+#ifdef CONFIG_NET_DMA
+	tp->ucopy.dma_chan = NULL;
+	tp->ucopy.wakeup = 0;
+	tp->ucopy.pinned_list = NULL;
+	tp->ucopy.dma_cookie = 0;
+#endif
+}
+
+/* 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?
+ */
+static inline int tcp_prequeue(struct sock *sk, struct sk_buff *skb)
+{
+	struct tcp_sock *tp = tcp_sk(sk);
+
+	if (sysctl_tcp_low_latency || !tp->ucopy.task)
+		return 0;
+
+	__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);
+		}
+
+		tp->ucopy.memory = 0;
+	} else if (skb_queue_len(&tp->ucopy.prequeue) == 1) {
+		wake_up_interruptible_sync_poll(sk_sleep(sk),
+					   POLLIN | POLLRDNORM | POLLRDBAND);
+		if (!inet_csk_ack_scheduled(sk))
+			inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK,
+						  (3 * tcp_rto_min(sk)) / 4,
+						  TCP_RTO_MAX);
+	}
+	return 1;
+}
+
+
+#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
+extern void tcp_set_state(struct sock *sk, int state);
+
+extern void tcp_done(struct sock *sk);
+
+static inline void tcp_sack_reset(struct tcp_options_received *rx_opt)
+{
+	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,
+				      int wscale_ok, __u8 *rcv_wscale,
+				      __u32 init_rcv_wnd);
+
+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); 
+}
+
+static inline void tcp_openreq_init(struct request_sock *req,
+				    struct tcp_options_received *rx_opt,
+				    struct sk_buff *skb)
+{
+	struct inet_request_sock *ireq = inet_rsk(req);
+
+	req->rcv_wnd = 0;		/* So that tcp_send_synack() knows! */
+	req->cookie_ts = 0;
+	tcp_rsk(req)->rcv_isn = TCP_SKB_CB(skb)->seq;
+	req->mss = rx_opt->mss_clamp;
+	req->ts_recent = rx_opt->saw_tstamp ? rx_opt->rcv_tsval : 0;
+	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;
+	ireq->rmt_port = tcp_hdr(skb)->source;
+	ireq->loc_port = tcp_hdr(skb)->dest;
+}
+
+extern void tcp_enter_memory_pressure(struct sock *sk);
+
+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;
+}
+
+static inline int keepalive_probes(const struct tcp_sock *tp)
+{
+	return tp->keepalive_probes ? : sysctl_tcp_keepalive_probes;
+}
+
+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);
+}
+
+static inline int tcp_fin_time(const struct sock *sk)
+{
+	int fin_timeout = tcp_sk(sk)->linger2 ? : sysctl_tcp_fin_timeout;
+	const int rto = inet_csk(sk)->icsk_rto;
+
+	if (fin_timeout < (rto << 2) - (rto >> 1))
+		fin_timeout = (rto << 2) - (rto >> 1);
+
+	return fin_timeout;
+}
+
+static inline int tcp_paws_check(const struct tcp_options_received *rx_opt,
+				 int paws_win)
+{
+	if ((s32)(rx_opt->ts_recent - rx_opt->rcv_tsval) <= paws_win)
+		return 1;
+	if (unlikely(get_seconds() >= rx_opt->ts_recent_stamp + TCP_PAWS_24DAYS))
+		return 1;
+	/*
+	 * 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)
+		return 1;
+	return 0;
+}
+
+static inline int tcp_paws_reject(const struct tcp_options_received *rx_opt,
+				  int rst)
+{
+	if (tcp_paws_check(rx_opt, 0))
+		return 0;
+
+	/* 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.
+	 */
+	if (rst && get_seconds() >= rx_opt->ts_recent_stamp + TCP_PAWS_MSL)
+		return 0;
+	return 1;
+}
+
+static inline void tcp_mib_init(struct net *net)
+{
+	/* See RFC 2012 */
+	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);
+}
+
+/* from STCP */
+static inline void tcp_clear_retrans_hints_partial(struct tcp_sock *tp)
+{
+	tp->lost_skb_hint = NULL;
+	tp->scoreboard_skb_hint = NULL;
+}
+
+static inline void tcp_clear_all_retrans_hints(struct tcp_sock *tp)
+{
+	tcp_clear_retrans_hints_partial(tp);
+	tp->retransmit_skb_hint = NULL;
+}
+
+/* MD5 Signature */
+struct crypto_hash;
+
+union tcp_md5_addr {
+	struct in_addr  a4;
+#if IS_ENABLED(CONFIG_IPV6)
+	struct in6_addr	a6;
+#endif
+};
+
+/* - key database */
+struct tcp_md5sig_key {
+	struct hlist_node	node;
+	u8			keylen;
+	u8			family; /* AF_INET or AF_INET6 */
+	union tcp_md5_addr	addr;
+	u8			key[TCP_MD5SIG_MAXKEYLEN];
+	struct rcu_head		rcu;
+};
+
+/* - sock block */
+struct tcp_md5sig_info {
+	struct hlist_head	head;
+	struct rcu_head		rcu;
+};
+
+/* - 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;
+#if IS_ENABLED(CONFIG_IPV6)
+	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 */
+extern int tcp_v4_md5_hash_skb(char *md5_hash, struct tcp_md5sig_key *key,
+			       const struct sock *sk,
+			       const struct request_sock *req,
+			       const struct sk_buff *skb);
+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);
+
+#ifdef CONFIG_TCP_MD5SIG
+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)
+#else
+static inline struct tcp_md5sig_key *tcp_md5_do_lookup(struct sock *sk,
+					 const union tcp_md5_addr *addr,
+					 int family)
+{
+	return NULL;
+}
+#define tcp_twsk_md5_key(twsk)	NULL
+#endif
+
+extern struct tcp_md5sig_pool __percpu *tcp_alloc_md5sig_pool(struct sock *);
+extern void tcp_free_md5sig_pool(void);
+
+extern struct tcp_md5sig_pool	*tcp_get_md5sig_pool(void);
+extern void tcp_put_md5sig_pool(void);
+
+extern int tcp_md5_hash_header(struct tcp_md5sig_pool *, const struct tcphdr *);
+extern int tcp_md5_hash_skb_data(struct tcp_md5sig_pool *, const struct sk_buff *,
+				 unsigned header_len);
+extern int tcp_md5_hash_key(struct tcp_md5sig_pool *hp,
+			    const struct tcp_md5sig_key *key);
+
+/* 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)
+		sk_wmem_free_skb(sk, skb);
+	sk_mem_reclaim(sk);
+	tcp_clear_all_retrans_hints(tcp_sk(sk));
+}
+
+static inline struct sk_buff *tcp_write_queue_head(const struct sock *sk)
+{
+	return skb_peek(&sk->sk_write_queue);
+}
+
+static inline struct sk_buff *tcp_write_queue_tail(const struct sock *sk)
+{
+	return skb_peek_tail(&sk->sk_write_queue);
+}
+
+static inline struct sk_buff *tcp_write_queue_next(const struct sock *sk,
+						   const struct sk_buff *skb)
+{
+	return skb_queue_next(&sk->sk_write_queue, skb);
+}
+
+static inline struct sk_buff *tcp_write_queue_prev(const struct sock *sk,
+						   const struct sk_buff *skb)
+{
+	return skb_queue_prev(&sk->sk_write_queue, skb);
+}
+
+#define tcp_for_write_queue(skb, sk)					\
+	skb_queue_walk(&(sk)->sk_write_queue, skb)
+
+#define tcp_for_write_queue_from(skb, sk)				\
+	skb_queue_walk_from(&(sk)->sk_write_queue, skb)
+
+#define tcp_for_write_queue_from_safe(skb, tmp, sk)			\
+	skb_queue_walk_from_safe(&(sk)->sk_write_queue, skb, tmp)
+
+static inline struct sk_buff *tcp_send_head(const struct sock *sk)
+{
+	return sk->sk_send_head;
+}
+
+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);
+}
+
+static inline void tcp_advance_send_head(struct sock *sk, const struct sk_buff *skb)
+{
+	if (tcp_skb_is_last(sk, skb))
+		sk->sk_send_head = NULL;
+	else
+		sk->sk_send_head = tcp_write_queue_next(sk, skb);
+}
+
+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. */
+	if (sk->sk_send_head == NULL) {
+		sk->sk_send_head = skb;
+
+		if (tcp_sk(sk)->highest_sack == NULL)
+			tcp_sk(sk)->highest_sack = skb;
+	}
+}
+
+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)
+{
+	__skb_queue_after(&sk->sk_write_queue, skb, buff);
+}
+
+/* Insert new before skb on the write queue of sk.  */
+static inline void tcp_insert_write_queue_before(struct sk_buff *new,
+						  struct sk_buff *skb,
+						  struct sock *sk)
+{
+	__skb_queue_before(&sk->sk_write_queue, skb, new);
+
+	if (sk->sk_send_head == skb)
+		sk->sk_send_head = new;
+}
+
+static inline void tcp_unlink_write_queue(struct sk_buff *skb, struct sock *sk)
+{
+	__skb_unlink(skb, &sk->sk_write_queue);
+}
+
+static inline int tcp_write_queue_empty(struct sock *sk)
+{
+	return skb_queue_empty(&sk->sk_write_queue);
+}
+
+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);
+	}
+}
+
+/* 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.
+ */
+static inline u32 tcp_highest_sack_seq(struct tcp_sock *tp)
+{
+	if (!tp->sacked_out)
+		return tp->snd_una;
+
+	if (tp->highest_sack == NULL)
+		return tp->snd_nxt;
+
+	return TCP_SKB_CB(tp->highest_sack)->seq;
+}
+
+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;
+}
+
+/* Determines whether this is a thin stream (which may suffer from
+ * increased latency). Used to trigger latency-reducing mechanisms.
+ */
+static inline unsigned int tcp_stream_is_thin(struct tcp_sock *tp)
+{
+	return tp->packets_out < 4 && !tcp_in_initial_slowstart(tp);
+}
+
+/* /proc */
+enum tcp_seq_states {
+	TCP_SEQ_STATE_LISTENING,
+	TCP_SEQ_STATE_OPENREQ,
+	TCP_SEQ_STATE_ESTABLISHED,
+	TCP_SEQ_STATE_TIME_WAIT,
+};
+
+int tcp_seq_open(struct inode *inode, struct file *file);
+
+struct tcp_seq_afinfo {
+	char				*name;
+	sa_family_t			family;
+	const struct file_operations	*seq_fops;
+	struct seq_operations		seq_ops;
+};
+
+struct tcp_iter_state {
+	struct seq_net_private	p;
+	sa_family_t		family;
+	enum tcp_seq_states	state;
+	struct sock		*syn_wait_sk;
+	int			bucket, offset, sbucket, num, uid;
+	loff_t			last_pos;
+};
+
+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);
+
+extern struct request_sock_ops tcp_request_sock_ops;
+extern struct request_sock_ops tcp6_request_sock_ops;
+
+extern void tcp_v4_destroy_sock(struct sock *sk);
+
+extern int tcp_v4_gso_send_check(struct sk_buff *skb);
+extern struct sk_buff *tcp_tso_segment(struct sk_buff *skb,
+				       netdev_features_t features);
+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);
+
+extern int tcp_nuke_addr(struct net *net, struct sockaddr *addr);
+
+#ifdef CONFIG_PROC_FS
+extern int tcp4_proc_init(void);
+extern void tcp4_proc_exit(void);
+#endif
+
+/* 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,
+						  const struct sock *sk,
+						  const struct request_sock *req,
+						  const struct sk_buff *skb);
+	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);
+	int			(*calc_md5_hash) (char *location,
+						  struct tcp_md5sig_key *md5,
+						  const struct sock *sk,
+						  const struct request_sock *req,
+						  const struct sk_buff *skb);
+#endif
+};
+
+/* 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);
+
+/**
+ *	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;
+}
+
+extern void tcp_v4_init(void);
+extern void tcp_init(void);
+
+#endif	/* _TCP_H */