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-rw-r--r--kernel/include/net/tcp.h1715
1 files changed, 1715 insertions, 0 deletions
diff --git a/kernel/include/net/tcp.h b/kernel/include/net/tcp.h
new file mode 100644
index 000000000..6d204f3f9
--- /dev/null
+++ b/kernel/include/net/tcp.h
@@ -0,0 +1,1715 @@
+/*
+ * 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/crypto.h>
+#include <linux/cryptohash.h>
+#include <linux/kref.h>
+#include <linux/ktime.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;
+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
+
+/* 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 1024
+
+/* probing interval, default to 10 minutes as per RFC4821 */
+#define TCP_PROBE_INTERVAL 600
+
+/* Specify interval when tcp mtu probing will stop */
+#define TCP_PROBE_THRESHOLD 8
+
+/* After receiving this amount of duplicate ACKs fast retransmit starts. */
+#define TCP_FASTRETRANS_THRESH 3
+
+/* 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 6 /* This is how many retries are done
+ * when active opening a connection.
+ * RFC1122 says the minimum retry MUST
+ * be at least 180secs. Nevertheless
+ * this value is corresponding to
+ * 63secs of retransmission with the
+ * current initial RTO.
+ */
+
+#define TCP_SYNACK_RETRIES 5 /* This is how may retries are done
+ * when passive opening a connection.
+ * This is corresponding to 31secs of
+ * retransmission with the current
+ * initial RTO.
+ */
+
+#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)) /* RFC6298 2.1 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_FASTOPEN 34 /* Fast open (RFC7413) */
+#define TCPOPT_EXP 254 /* Experimental */
+/* Magic number to be after the option value for sharing TCP
+ * experimental options. See draft-ietf-tcpm-experimental-options-00.txt
+ */
+#define TCPOPT_FASTOPEN_MAGIC 0xF989
+
+/*
+ * 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_FASTOPEN_BASE 2
+#define TCPOLEN_EXP_FASTOPEN_BASE 4
+
+/* 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
+
+/* Bit Flags for sysctl_tcp_fastopen */
+#define TFO_CLIENT_ENABLE 1
+#define TFO_SERVER_ENABLE 2
+#define TFO_CLIENT_NO_COOKIE 4 /* Data in SYN w/o cookie option */
+
+/* Accept SYN data w/o any cookie option */
+#define TFO_SERVER_COOKIE_NOT_REQD 0x200
+
+/* Force enable TFO on all listeners, i.e., not requiring the
+ * TCP_FASTOPEN socket option. SOCKOPT1/2 determine how to set max_qlen.
+ */
+#define TFO_SERVER_WO_SOCKOPT1 0x400
+#define TFO_SERVER_WO_SOCKOPT2 0x800
+
+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_fastopen;
+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_max_reordering;
+extern int sysctl_tcp_dsack;
+extern long sysctl_tcp_mem[3];
+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_low_latency;
+extern int sysctl_tcp_nometrics_save;
+extern int sysctl_tcp_moderate_rcvbuf;
+extern int sysctl_tcp_tso_win_divisor;
+extern int sysctl_tcp_workaround_signed_windows;
+extern int sysctl_tcp_slow_start_after_idle;
+extern int sysctl_tcp_thin_linear_timeouts;
+extern int sysctl_tcp_thin_dupack;
+extern int sysctl_tcp_early_retrans;
+extern int sysctl_tcp_limit_output_bytes;
+extern int sysctl_tcp_challenge_ack_limit;
+extern unsigned int sysctl_tcp_notsent_lowat;
+extern int sysctl_tcp_min_tso_segs;
+extern int sysctl_tcp_autocorking;
+extern int sysctl_tcp_invalid_ratelimit;
+
+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 bool before(__u32 seq1, __u32 seq2)
+{
+ return (__s32)(seq1-seq2) < 0;
+}
+#define after(seq2, seq1) before(seq1, seq2)
+
+/* is s2<=s1<=s3 ? */
+static inline bool 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;
+}
+
+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 bool 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)
+
+void tcp_tasklet_init(void);
+
+void tcp_v4_err(struct sk_buff *skb, u32);
+
+void tcp_shutdown(struct sock *sk, int how);
+
+void tcp_v4_early_demux(struct sk_buff *skb);
+int tcp_v4_rcv(struct sk_buff *skb);
+
+int tcp_v4_tw_remember_stamp(struct inet_timewait_sock *tw);
+int tcp_sendmsg(struct sock *sk, struct msghdr *msg, size_t size);
+int tcp_sendpage(struct sock *sk, struct page *page, int offset, size_t size,
+ int flags);
+void tcp_release_cb(struct sock *sk);
+void tcp_wfree(struct sk_buff *skb);
+void tcp_write_timer_handler(struct sock *sk);
+void tcp_delack_timer_handler(struct sock *sk);
+int tcp_ioctl(struct sock *sk, int cmd, unsigned long arg);
+int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb,
+ const struct tcphdr *th, unsigned int len);
+void tcp_rcv_established(struct sock *sk, struct sk_buff *skb,
+ const struct tcphdr *th, unsigned int len);
+void tcp_rcv_space_adjust(struct sock *sk);
+int tcp_twsk_unique(struct sock *sk, struct sock *sktw, void *twp);
+void tcp_twsk_destructor(struct sock *sk);
+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
+
+enum tcp_tw_status {
+ TCP_TW_SUCCESS = 0,
+ TCP_TW_RST = 1,
+ TCP_TW_ACK = 2,
+ TCP_TW_SYN = 3
+};
+
+
+enum tcp_tw_status tcp_timewait_state_process(struct inet_timewait_sock *tw,
+ struct sk_buff *skb,
+ const struct tcphdr *th);
+struct sock *tcp_check_req(struct sock *sk, struct sk_buff *skb,
+ struct request_sock *req, bool fastopen);
+int tcp_child_process(struct sock *parent, struct sock *child,
+ struct sk_buff *skb);
+void tcp_enter_loss(struct sock *sk);
+void tcp_clear_retrans(struct tcp_sock *tp);
+void tcp_update_metrics(struct sock *sk);
+void tcp_init_metrics(struct sock *sk);
+void tcp_metrics_init(void);
+bool tcp_peer_is_proven(struct request_sock *req, struct dst_entry *dst,
+ bool paws_check, bool timestamps);
+bool tcp_remember_stamp(struct sock *sk);
+bool tcp_tw_remember_stamp(struct inet_timewait_sock *tw);
+void tcp_fetch_timewait_stamp(struct sock *sk, struct dst_entry *dst);
+void tcp_disable_fack(struct tcp_sock *tp);
+void tcp_close(struct sock *sk, long timeout);
+void tcp_init_sock(struct sock *sk);
+unsigned int tcp_poll(struct file *file, struct socket *sock,
+ struct poll_table_struct *wait);
+int tcp_getsockopt(struct sock *sk, int level, int optname,
+ char __user *optval, int __user *optlen);
+int tcp_setsockopt(struct sock *sk, int level, int optname,
+ char __user *optval, unsigned int optlen);
+int compat_tcp_getsockopt(struct sock *sk, int level, int optname,
+ char __user *optval, int __user *optlen);
+int compat_tcp_setsockopt(struct sock *sk, int level, int optname,
+ char __user *optval, unsigned int optlen);
+void tcp_set_keepalive(struct sock *sk, int val);
+void tcp_syn_ack_timeout(const struct request_sock *req);
+int tcp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, int nonblock,
+ int flags, int *addr_len);
+void tcp_parse_options(const struct sk_buff *skb,
+ struct tcp_options_received *opt_rx,
+ int estab, struct tcp_fastopen_cookie *foc);
+const u8 *tcp_parse_md5sig_option(const struct tcphdr *th);
+
+/*
+ * TCP v4 functions exported for the inet6 API
+ */
+
+void tcp_v4_send_check(struct sock *sk, struct sk_buff *skb);
+void tcp_v4_mtu_reduced(struct sock *sk);
+void tcp_req_err(struct sock *sk, u32 seq);
+int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb);
+struct sock *tcp_create_openreq_child(struct sock *sk,
+ struct request_sock *req,
+ struct sk_buff *skb);
+void tcp_ca_openreq_child(struct sock *sk, const struct dst_entry *dst);
+struct sock *tcp_v4_syn_recv_sock(struct sock *sk, struct sk_buff *skb,
+ struct request_sock *req,
+ struct dst_entry *dst);
+int tcp_v4_do_rcv(struct sock *sk, struct sk_buff *skb);
+int tcp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len);
+int tcp_connect(struct sock *sk);
+struct sk_buff *tcp_make_synack(struct sock *sk, struct dst_entry *dst,
+ struct request_sock *req,
+ struct tcp_fastopen_cookie *foc);
+int tcp_disconnect(struct sock *sk, int flags);
+
+void tcp_finish_connect(struct sock *sk, struct sk_buff *skb);
+int tcp_send_rcvq(struct sock *sk, struct msghdr *msg, size_t size);
+void inet_sk_rx_dst_set(struct sock *sk, const struct sk_buff *skb);
+
+/* From syncookies.c */
+int __cookie_v4_check(const struct iphdr *iph, const struct tcphdr *th,
+ u32 cookie);
+struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb);
+#ifdef CONFIG_SYN_COOKIES
+
+/* Syncookies use a monotonic timer which increments every 60 seconds.
+ * This counter is used both as a hash input and partially encoded into
+ * the cookie value. A cookie is only validated further if the delta
+ * between the current counter value and the encoded one is less than this,
+ * i.e. a sent cookie is valid only at most for 2*60 seconds (or less if
+ * the counter advances immediately after a cookie is generated).
+ */
+#define MAX_SYNCOOKIE_AGE 2
+
+static inline u32 tcp_cookie_time(void)
+{
+ u64 val = get_jiffies_64();
+
+ do_div(val, 60 * HZ);
+ return val;
+}
+
+u32 __cookie_v4_init_sequence(const struct iphdr *iph, const struct tcphdr *th,
+ u16 *mssp);
+__u32 cookie_v4_init_sequence(struct sock *sk, const struct sk_buff *skb,
+ __u16 *mss);
+__u32 cookie_init_timestamp(struct request_sock *req);
+bool cookie_timestamp_decode(struct tcp_options_received *opt);
+bool cookie_ecn_ok(const struct tcp_options_received *opt,
+ const struct net *net, const struct dst_entry *dst);
+
+/* From net/ipv6/syncookies.c */
+int __cookie_v6_check(const struct ipv6hdr *iph, const struct tcphdr *th,
+ u32 cookie);
+struct sock *cookie_v6_check(struct sock *sk, struct sk_buff *skb);
+
+u32 __cookie_v6_init_sequence(const struct ipv6hdr *iph,
+ const struct tcphdr *th, u16 *mssp);
+__u32 cookie_v6_init_sequence(struct sock *sk, const struct sk_buff *skb,
+ __u16 *mss);
+#endif
+/* tcp_output.c */
+
+void __tcp_push_pending_frames(struct sock *sk, unsigned int cur_mss,
+ int nonagle);
+bool tcp_may_send_now(struct sock *sk);
+int __tcp_retransmit_skb(struct sock *, struct sk_buff *);
+int tcp_retransmit_skb(struct sock *, struct sk_buff *);
+void tcp_retransmit_timer(struct sock *sk);
+void tcp_xmit_retransmit_queue(struct sock *);
+void tcp_simple_retransmit(struct sock *);
+int tcp_trim_head(struct sock *, struct sk_buff *, u32);
+int tcp_fragment(struct sock *, struct sk_buff *, u32, unsigned int, gfp_t);
+
+void tcp_send_probe0(struct sock *);
+void tcp_send_partial(struct sock *);
+int tcp_write_wakeup(struct sock *);
+void tcp_send_fin(struct sock *sk);
+void tcp_send_active_reset(struct sock *sk, gfp_t priority);
+int tcp_send_synack(struct sock *);
+void tcp_push_one(struct sock *, unsigned int mss_now);
+void tcp_send_ack(struct sock *sk);
+void tcp_send_delayed_ack(struct sock *sk);
+void tcp_send_loss_probe(struct sock *sk);
+bool tcp_schedule_loss_probe(struct sock *sk);
+
+/* tcp_input.c */
+void tcp_resume_early_retransmit(struct sock *sk);
+void tcp_rearm_rto(struct sock *sk);
+void tcp_reset(struct sock *sk);
+
+/* tcp_timer.c */
+void tcp_init_xmit_timers(struct sock *);
+static inline void tcp_clear_xmit_timers(struct sock *sk)
+{
+ inet_csk_clear_xmit_timers(sk);
+}
+
+unsigned int tcp_sync_mss(struct sock *sk, u32 pmtu);
+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 */
+void tcp_get_info(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);
+int tcp_read_sock(struct sock *sk, read_descriptor_t *desc,
+ sk_read_actor_t recv_actor);
+
+void tcp_initialize_rcv_mss(struct sock *sk);
+
+int tcp_mtu_to_mss(struct sock *sk, int pmtu);
+int tcp_mss_to_mtu(struct sock *sk, int mss);
+void tcp_mtup_init(struct sock *sk);
+void tcp_init_buffer_space(struct sock *sk);
+
+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 usecs_to_jiffies((tp->srtt_us >> 3) + tp->rttvar_us);
+}
+
+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;
+}
+
+static inline u32 tcp_rto_min_us(struct sock *sk)
+{
+ return jiffies_to_usecs(tcp_rto_min(sk));
+}
+
+static inline bool tcp_ca_dst_locked(const struct dst_entry *dst)
+{
+ return dst_metric_locked(dst, RTAX_CC_ALGO);
+}
+
+/* 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.
+ */
+u32 __tcp_select_window(struct sock *sk);
+
+void tcp_send_window_probe(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))
+
+static inline u32 tcp_skb_timestamp(const struct sk_buff *skb)
+{
+ return skb->skb_mstamp.stamp_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 {
+ __u32 seq; /* Starting sequence number */
+ __u32 end_seq; /* SEQ + FIN + SYN + datalen */
+ union {
+ /* Note : tcp_tw_isn is used in input path only
+ * (isn chosen by tcp_timewait_state_process())
+ *
+ * tcp_gso_segs is used in write queue only,
+ * cf tcp_skb_pcount()
+ */
+ __u32 tcp_tw_isn;
+ __u32 tcp_gso_segs;
+ };
+ __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 */
+#define TCPCB_REPAIRED 0x10 /* SKB repaired (no skb_mstamp) */
+#define TCPCB_EVER_RETRANS 0x80 /* Ever retransmitted frame */
+#define TCPCB_RETRANS (TCPCB_SACKED_RETRANS|TCPCB_EVER_RETRANS| \
+ TCPCB_REPAIRED)
+
+ __u8 ip_dsfield; /* IPv4 tos or IPv6 dsfield */
+ /* 1 byte hole */
+ __u32 ack_seq; /* Sequence number ACK'd */
+ union {
+ struct inet_skb_parm h4;
+#if IS_ENABLED(CONFIG_IPV6)
+ struct inet6_skb_parm h6;
+#endif
+ } header; /* For incoming frames */
+};
+
+#define TCP_SKB_CB(__skb) ((struct tcp_skb_cb *)&((__skb)->cb[0]))
+
+
+#if IS_ENABLED(CONFIG_IPV6)
+/* This is the variant of inet6_iif() that must be used by TCP,
+ * as TCP moves IP6CB into a different location in skb->cb[]
+ */
+static inline int tcp_v6_iif(const struct sk_buff *skb)
+{
+ return TCP_SKB_CB(skb)->header.h6.iif;
+}
+#endif
+
+/* 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 TCP_SKB_CB(skb)->tcp_gso_segs;
+}
+
+static inline void tcp_skb_pcount_set(struct sk_buff *skb, int segs)
+{
+ TCP_SKB_CB(skb)->tcp_gso_segs = segs;
+}
+
+static inline void tcp_skb_pcount_add(struct sk_buff *skb, int segs)
+{
+ TCP_SKB_CB(skb)->tcp_gso_segs += 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_LOSS, /* loss timeout */
+ CA_EVENT_ECN_NO_CE, /* ECT set, but not CE marked */
+ CA_EVENT_ECN_IS_CE, /* received CE marked IP packet */
+ CA_EVENT_DELAYED_ACK, /* Delayed ack is sent */
+ CA_EVENT_NON_DELAYED_ACK,
+};
+
+/* Information about inbound ACK, passed to cong_ops->in_ack_event() */
+enum tcp_ca_ack_event_flags {
+ CA_ACK_SLOWPATH = (1 << 0), /* In slow path processing */
+ CA_ACK_WIN_UPDATE = (1 << 1), /* ACK updated window */
+ CA_ACK_ECE = (1 << 2), /* ECE bit is set on 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_CA_UNSPEC 0
+
+/* Algorithm can be set on socket without CAP_NET_ADMIN privileges */
+#define TCP_CONG_NON_RESTRICTED 0x1
+/* Requires ECN/ECT set on all packets */
+#define TCP_CONG_NEEDS_ECN 0x2
+
+union tcp_cc_info;
+
+struct tcp_congestion_ops {
+ struct list_head list;
+ u32 key;
+ u32 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);
+ /* do new cwnd calculation (required) */
+ void (*cong_avoid)(struct sock *sk, u32 ack, u32 acked);
+ /* 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);
+ /* call when ack arrives (optional) */
+ void (*in_ack_event)(struct sock *sk, u32 flags);
+ /* 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) */
+ size_t (*get_info)(struct sock *sk, u32 ext, int *attr,
+ union tcp_cc_info *info);
+
+ char name[TCP_CA_NAME_MAX];
+ struct module *owner;
+};
+
+int tcp_register_congestion_control(struct tcp_congestion_ops *type);
+void tcp_unregister_congestion_control(struct tcp_congestion_ops *type);
+
+void tcp_assign_congestion_control(struct sock *sk);
+void tcp_init_congestion_control(struct sock *sk);
+void tcp_cleanup_congestion_control(struct sock *sk);
+int tcp_set_default_congestion_control(const char *name);
+void tcp_get_default_congestion_control(char *name);
+void tcp_get_available_congestion_control(char *buf, size_t len);
+void tcp_get_allowed_congestion_control(char *buf, size_t len);
+int tcp_set_allowed_congestion_control(char *allowed);
+int tcp_set_congestion_control(struct sock *sk, const char *name);
+u32 tcp_slow_start(struct tcp_sock *tp, u32 acked);
+void tcp_cong_avoid_ai(struct tcp_sock *tp, u32 w, u32 acked);
+
+u32 tcp_reno_ssthresh(struct sock *sk);
+void tcp_reno_cong_avoid(struct sock *sk, u32 ack, u32 acked);
+extern struct tcp_congestion_ops tcp_reno;
+
+struct tcp_congestion_ops *tcp_ca_find_key(u32 key);
+u32 tcp_ca_get_key_by_name(const char *name);
+#ifdef CONFIG_INET
+char *tcp_ca_get_name_by_key(u32 key, char *buffer);
+#else
+static inline char *tcp_ca_get_name_by_key(u32 key, char *buffer)
+{
+ return NULL;
+}
+#endif
+
+static inline bool tcp_ca_needs_ecn(const struct sock *sk)
+{
+ const struct inet_connection_sock *icsk = inet_csk(sk);
+
+ return icsk->icsk_ca_ops->flags & TCP_CONG_NEEDS_ECN;
+}
+
+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 bool tcp_is_reno(const struct tcp_sock *tp)
+{
+ return !tcp_is_sack(tp);
+}
+
+static inline bool 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;
+}
+
+/* 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_early_retrans < 4 && !sysctl_tcp_thin_dupack &&
+ sysctl_tcp_reordering == 3;
+}
+
+static inline void tcp_disable_early_retrans(struct tcp_sock *tp)
+{
+ tp->do_early_retrans = 0;
+}
+
+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;
+}
+
+static inline bool tcp_in_cwnd_reduction(const struct sock *sk)
+{
+ return (TCPF_CA_CWR | TCPF_CA_Recovery) &
+ (1 << inet_csk(sk)->icsk_ca_state);
+}
+
+/* If cwnd > ssthresh, we may raise ssthresh to be half-way to cwnd.
+ * The exception is cwnd reduction 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 (tcp_in_cwnd_reduction(sk))
+ 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)
+
+void tcp_enter_cwr(struct sock *sk);
+__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;
+}
+
+/* We follow the spirit of RFC2861 to validate cwnd but implement a more
+ * flexible approach. The RFC suggests cwnd should not be raised unless
+ * it was fully used previously. And that's exactly what we do in
+ * congestion avoidance mode. But in slow start we allow cwnd to grow
+ * as long as the application has used half the cwnd.
+ * Example :
+ * cwnd is 10 (IW10), but application sends 9 frames.
+ * We allow cwnd to reach 18 when all frames are ACKed.
+ * This check is safe because it's as aggressive as slow start which already
+ * risks 100% overshoot. The advantage is that we discourage application to
+ * either send more filler packets or data to artificially blow up the cwnd
+ * usage, and allow application-limited process to probe bw more aggressively.
+ */
+static inline bool tcp_is_cwnd_limited(const struct sock *sk)
+{
+ const struct tcp_sock *tp = tcp_sk(sk);
+
+ /* If in slow start, ensure cwnd grows to twice what was ACKed. */
+ if (tp->snd_cwnd <= tp->snd_ssthresh)
+ return tp->snd_cwnd < 2 * tp->max_packets_out;
+
+ return tp->is_cwnd_limited;
+}
+
+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 bool 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);
+}
+
+bool tcp_prequeue(struct sock *sk, struct sk_buff *skb);
+
+#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
+void tcp_set_state(struct sock *sk, int state);
+
+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;
+}
+
+u32 tcp_default_init_rwnd(u32 mss);
+
+/* Determine a window scaling and initial window to offer. */
+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);
+}
+
+extern void tcp_openreq_init_rwin(struct request_sock *req,
+ struct sock *sk, struct dst_entry *dst);
+
+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 bool 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 true;
+ if (unlikely(get_seconds() >= rx_opt->ts_recent_stamp + TCP_PAWS_24DAYS))
+ return true;
+ /*
+ * 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 true;
+ return false;
+}
+
+static inline bool tcp_paws_reject(const struct tcp_options_received *rx_opt,
+ int rst)
+{
+ if (tcp_paws_check(rx_opt, 0))
+ return false;
+
+ /* 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 false;
+ return true;
+}
+
+bool tcp_oow_rate_limited(struct net *net, const struct sk_buff *skb,
+ int mib_idx, u32 *last_oow_ack_time);
+
+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;
+}
+
+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 */
+int tcp_v4_md5_hash_skb(char *md5_hash, const struct tcp_md5sig_key *key,
+ const struct sock *sk, const struct sk_buff *skb);
+int tcp_md5_do_add(struct sock *sk, const union tcp_md5_addr *addr,
+ int family, const u8 *newkey, u8 newkeylen, gfp_t gfp);
+int tcp_md5_do_del(struct sock *sk, const union tcp_md5_addr *addr,
+ int family);
+struct tcp_md5sig_key *tcp_v4_md5_lookup(struct sock *sk,
+ const struct sock *addr_sk);
+
+#ifdef CONFIG_TCP_MD5SIG
+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
+
+bool tcp_alloc_md5sig_pool(void);
+
+struct tcp_md5sig_pool *tcp_get_md5sig_pool(void);
+static inline void tcp_put_md5sig_pool(void)
+{
+ local_bh_enable();
+}
+
+int tcp_md5_hash_header(struct tcp_md5sig_pool *, const struct tcphdr *);
+int tcp_md5_hash_skb_data(struct tcp_md5sig_pool *, const struct sk_buff *,
+ unsigned int header_len);
+int tcp_md5_hash_key(struct tcp_md5sig_pool *hp,
+ const struct tcp_md5sig_key *key);
+
+/* From tcp_fastopen.c */
+void tcp_fastopen_cache_get(struct sock *sk, u16 *mss,
+ struct tcp_fastopen_cookie *cookie, int *syn_loss,
+ unsigned long *last_syn_loss);
+void tcp_fastopen_cache_set(struct sock *sk, u16 mss,
+ struct tcp_fastopen_cookie *cookie, bool syn_lost,
+ u16 try_exp);
+struct tcp_fastopen_request {
+ /* Fast Open cookie. Size 0 means a cookie request */
+ struct tcp_fastopen_cookie cookie;
+ struct msghdr *data; /* data in MSG_FASTOPEN */
+ size_t size;
+ int copied; /* queued in tcp_connect() */
+};
+void tcp_free_fastopen_req(struct tcp_sock *tp);
+
+extern struct tcp_fastopen_context __rcu *tcp_fastopen_ctx;
+int tcp_fastopen_reset_cipher(void *key, unsigned int len);
+bool tcp_try_fastopen(struct sock *sk, struct sk_buff *skb,
+ struct request_sock *req,
+ struct tcp_fastopen_cookie *foc,
+ struct dst_entry *dst);
+void tcp_fastopen_init_key_once(bool publish);
+#define TCP_FASTOPEN_KEY_LENGTH 16
+
+/* Fastopen key context */
+struct tcp_fastopen_context {
+ struct crypto_cipher *tfm;
+ __u8 key[TCP_FASTOPEN_KEY_LENGTH];
+ struct rcu_head rcu;
+};
+
+/* 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 bool 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 bool 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,
+};
+
+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;
+ kuid_t uid;
+ loff_t last_pos;
+};
+
+int tcp_proc_register(struct net *net, struct tcp_seq_afinfo *afinfo);
+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;
+
+void tcp_v4_destroy_sock(struct sock *sk);
+
+struct sk_buff *tcp_gso_segment(struct sk_buff *skb,
+ netdev_features_t features);
+struct sk_buff **tcp_gro_receive(struct sk_buff **head, struct sk_buff *skb);
+int tcp_gro_complete(struct sk_buff *skb);
+
+void __tcp_v4_send_check(struct sk_buff *skb, __be32 saddr, __be32 daddr);
+
+static inline u32 tcp_notsent_lowat(const struct tcp_sock *tp)
+{
+ return tp->notsent_lowat ?: sysctl_tcp_notsent_lowat;
+}
+
+static inline bool tcp_stream_memory_free(const struct sock *sk)
+{
+ const struct tcp_sock *tp = tcp_sk(sk);
+ u32 notsent_bytes = tp->write_seq - tp->snd_nxt;
+
+ return notsent_bytes < tcp_notsent_lowat(tp);
+}
+
+#ifdef CONFIG_PROC_FS
+int tcp4_proc_init(void);
+void tcp4_proc_exit(void);
+#endif
+
+int tcp_rtx_synack(struct sock *sk, struct request_sock *req);
+int tcp_conn_request(struct request_sock_ops *rsk_ops,
+ const struct tcp_request_sock_ops *af_ops,
+ struct sock *sk, struct sk_buff *skb);
+
+/* TCP af-specific functions */
+struct tcp_sock_af_ops {
+#ifdef CONFIG_TCP_MD5SIG
+ struct tcp_md5sig_key *(*md5_lookup) (struct sock *sk,
+ const struct sock *addr_sk);
+ int (*calc_md5_hash)(char *location,
+ const struct tcp_md5sig_key *md5,
+ const struct sock *sk,
+ const struct sk_buff *skb);
+ int (*md5_parse)(struct sock *sk,
+ char __user *optval,
+ int optlen);
+#endif
+};
+
+struct tcp_request_sock_ops {
+ u16 mss_clamp;
+#ifdef CONFIG_TCP_MD5SIG
+ struct tcp_md5sig_key *(*req_md5_lookup)(struct sock *sk,
+ const struct sock *addr_sk);
+ int (*calc_md5_hash) (char *location,
+ const struct tcp_md5sig_key *md5,
+ const struct sock *sk,
+ const struct sk_buff *skb);
+#endif
+ void (*init_req)(struct request_sock *req, struct sock *sk,
+ struct sk_buff *skb);
+#ifdef CONFIG_SYN_COOKIES
+ __u32 (*cookie_init_seq)(struct sock *sk, const struct sk_buff *skb,
+ __u16 *mss);
+#endif
+ struct dst_entry *(*route_req)(struct sock *sk, struct flowi *fl,
+ const struct request_sock *req,
+ bool *strict);
+ __u32 (*init_seq)(const struct sk_buff *skb);
+ int (*send_synack)(struct sock *sk, struct dst_entry *dst,
+ struct flowi *fl, struct request_sock *req,
+ u16 queue_mapping, struct tcp_fastopen_cookie *foc);
+ void (*queue_hash_add)(struct sock *sk, struct request_sock *req,
+ const unsigned long timeout);
+};
+
+#ifdef CONFIG_SYN_COOKIES
+static inline __u32 cookie_init_sequence(const struct tcp_request_sock_ops *ops,
+ struct sock *sk, struct sk_buff *skb,
+ __u16 *mss)
+{
+ return ops->cookie_init_seq(sk, skb, mss);
+}
+#else
+static inline __u32 cookie_init_sequence(const struct tcp_request_sock_ops *ops,
+ struct sock *sk, struct sk_buff *skb,
+ __u16 *mss)
+{
+ return 0;
+}
+#endif
+
+int tcpv4_offload_init(void);
+
+void tcp_v4_init(void);
+void tcp_init(void);
+
+/*
+ * Save and compile IPv4 options, return a pointer to it
+ */
+static inline struct ip_options_rcu *tcp_v4_save_options(struct sk_buff *skb)
+{
+ const struct ip_options *opt = &TCP_SKB_CB(skb)->header.h4.opt;
+ struct ip_options_rcu *dopt = NULL;
+
+ if (opt->optlen) {
+ int opt_size = sizeof(*dopt) + opt->optlen;
+
+ dopt = kmalloc(opt_size, GFP_ATOMIC);
+ if (dopt && __ip_options_echo(&dopt->opt, skb, opt)) {
+ kfree(dopt);
+ dopt = NULL;
+ }
+ }
+ return dopt;
+}
+
+/* locally generated TCP pure ACKs have skb->truesize == 2
+ * (check tcp_send_ack() in net/ipv4/tcp_output.c )
+ * This is much faster than dissecting the packet to find out.
+ * (Think of GRE encapsulations, IPv4, IPv6, ...)
+ */
+static inline bool skb_is_tcp_pure_ack(const struct sk_buff *skb)
+{
+ return skb->truesize == 2;
+}
+
+static inline void skb_set_tcp_pure_ack(struct sk_buff *skb)
+{
+ skb->truesize = 2;
+}
+
+#endif /* _TCP_H */