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tcp.h
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/*
* INET An implementation of the TCP/IP protocol suite for the LINUX
* operating system. INET is implemented using the BSD Socket
* interface as the means of communication with the user level.
*
* Definitions for the TCP module.
*
* Version: @(#)tcp.h 1.0.5 05/23/93
*
* Authors: Ross Biro
* Fred N. van Kempen, <[email protected]>
*
* 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/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>
#include <linux/bpf-cgroup.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
/* Maximal number of window scale according to RFC1323 */
#define TCP_MAX_WSCALE 14U
/* 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_MIN (2U) /* Min timeout for TCP timers in jiffies */
#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
#define TCPOPT_SMC_MAGIC 0xE2D4C3D9
/*
* 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
#define TCPOLEN_EXP_SMC_BASE 6
/* 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
#define TCPOLEN_EXP_SMC_BASE_ALIGNED 8
/* 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 rfc6928 */
#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.
*/
#define TFO_SERVER_WO_SOCKOPT1 0x400
/* sysctl variables for tcp */
extern int sysctl_tcp_max_orphans;
extern long sysctl_tcp_mem[3];
#define TCP_RACK_LOSS_DETECTION 0x1 /* Use RACK to detect losses */
#define TCP_RACK_STATIC_REO_WND 0x2 /* Use static RACK reo wnd */
extern atomic_long_t tcp_memory_allocated;
extern struct percpu_counter tcp_sockets_allocated;
extern unsigned long tcp_memory_pressure;
/* optimized version of sk_under_memory_pressure() for TCP sockets */
static inline bool tcp_under_memory_pressure(const struct sock *sk)
{
if (mem_cgroup_sockets_enabled && sk->sk_memcg &&
mem_cgroup_under_socket_pressure(sk->sk_memcg))
return true;
return 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;
}
void sk_forced_mem_schedule(struct sock *sk, int size);
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);
extern struct proto tcp_prot;
#define TCP_INC_STATS(net, field) SNMP_INC_STATS((net)->mib.tcp_statistics, field)
#define __TCP_INC_STATS(net, field) __SNMP_INC_STATS((net)->mib.tcp_statistics, field)
#define TCP_DEC_STATS(net, field) SNMP_DEC_STATS((net)->mib.tcp_statistics, field)
#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);
int 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_sendmsg_locked(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);
int tcp_sendpage_locked(struct sock *sk, struct page *page, int offset,
size_t size, int flags);
ssize_t do_tcp_sendpages(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);
void tcp_rcv_established(struct sock *sk, struct sk_buff *skb,
const struct tcphdr *th);
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_cwnd_reduction(struct sock *sk, int newly_acked_sacked, int flag);
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);
void tcp_close(struct sock *sk, long timeout);
void tcp_init_sock(struct sock *sk);
void tcp_init_transfer(struct sock *sk, int bpf_op);
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 net *net, 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, bool abort);
int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb);
struct sock *tcp_create_openreq_child(const 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(const struct sock *sk, struct sk_buff *skb,
struct request_sock *req,
struct dst_entry *dst,
struct request_sock *req_unhash,
bool *own_req);
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);
enum tcp_synack_type {
TCP_SYNACK_NORMAL,
TCP_SYNACK_FASTOPEN,
TCP_SYNACK_COOKIE,
};
struct sk_buff *tcp_make_synack(const struct sock *sk, struct dst_entry *dst,
struct request_sock *req,
struct tcp_fastopen_cookie *foc,
enum tcp_synack_type synack_type);
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 */
struct sock *tcp_get_cookie_sock(struct sock *sk, struct sk_buff *skb,
struct request_sock *req,
struct dst_entry *dst, u32 tsoff);
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
#define TCP_SYNCOOKIE_PERIOD (60 * HZ)
#define TCP_SYNCOOKIE_VALID (MAX_SYNCOOKIE_AGE * TCP_SYNCOOKIE_PERIOD)
/* syncookies: remember time of last synqueue overflow
* But do not dirty this field too often (once per second is enough)
* It is racy as we do not hold a lock, but race is very minor.
*/
static inline void tcp_synq_overflow(const struct sock *sk)
{
unsigned long last_overflow = tcp_sk(sk)->rx_opt.ts_recent_stamp;
unsigned long now = jiffies;
if (time_after(now, last_overflow + HZ))
tcp_sk(sk)->rx_opt.ts_recent_stamp = now;
}
/* 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_SYNCOOKIE_VALID);
}
static inline u32 tcp_cookie_time(void)
{
u64 val = get_jiffies_64();
do_div(val, TCP_SYNCOOKIE_PERIOD);
return val;
}
u32 __cookie_v4_init_sequence(const struct iphdr *iph, const struct tcphdr *th,
u16 *mssp);
__u32 cookie_v4_init_sequence(const struct sk_buff *skb, __u16 *mss);
u64 cookie_init_timestamp(struct request_sock *req);
bool cookie_timestamp_decode(const struct net *net,
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(const struct sk_buff *skb, __u16 *mss);
#endif
/* tcp_output.c */
u32 tcp_tso_autosize(const struct sock *sk, unsigned int mss_now,
int min_tso_segs);
void __tcp_push_pending_frames(struct sock *sk, unsigned int cur_mss,
int nonagle);
int __tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb, int segs);
int tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb, int segs);
void tcp_retransmit_timer(struct sock *sk);
void tcp_xmit_retransmit_queue(struct sock *);
void tcp_simple_retransmit(struct sock *);
void tcp_enter_recovery(struct sock *sk, bool ece_ack);
int tcp_trim_head(struct sock *, struct sk_buff *, u32);
enum tcp_queue {
TCP_FRAG_IN_WRITE_QUEUE,
TCP_FRAG_IN_RTX_QUEUE,
};
int tcp_fragment(struct sock *sk, enum tcp_queue tcp_queue,
struct sk_buff *skb, u32 len,
unsigned int mss_now, gfp_t gfp);
void tcp_send_probe0(struct sock *);
void tcp_send_partial(struct sock *);
int tcp_write_wakeup(struct sock *, int mib);
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, bool advancing_rto);
void tcp_skb_collapse_tstamp(struct sk_buff *skb,
const struct sk_buff *next_skb);
/* tcp_input.c */
void tcp_rearm_rto(struct sock *sk);
void tcp_synack_rtt_meas(struct sock *sk, struct request_sock *req);
void tcp_reset(struct sock *sk);
void tcp_skb_mark_lost_uncond_verify(struct tcp_sock *tp, struct sk_buff *skb);
void tcp_fin(struct sock *sk);
/* tcp_timer.c */
void tcp_init_xmit_timers(struct sock *);
static inline void tcp_clear_xmit_timers(struct sock *sk)
{
hrtimer_cancel(&tcp_sk(sk)->pacing_timer);
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 > TCP_MSS_DEFAULT)
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 */
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 (RB_EMPTY_ROOT(&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);
}
/* Minimum RTT in usec. ~0 means not available. */
static inline u32 tcp_min_rtt(const struct tcp_sock *tp)
{
return minmax_get(&tp->rtt_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.
*/
u32 __tcp_select_window(struct sock *sk);
void tcp_send_window_probe(struct sock *sk);
/* TCP uses 32bit jiffies to save some space.
* Note that this is different from tcp_time_stamp, which
* historically has been the same until linux-4.13.
*/
#define tcp_jiffies32 ((u32)jiffies)
/*
* Deliver a 32bit value for TCP timestamp option (RFC 7323)
* It is no longer tied to jiffies, but to 1 ms clock.
* Note: double check if you want to use tcp_jiffies32 instead of this.
*/
#define TCP_TS_HZ 1000
static inline u64 tcp_clock_ns(void)
{
return local_clock();
}
static inline u64 tcp_clock_us(void)
{
return div_u64(tcp_clock_ns(), NSEC_PER_USEC);
}
/* This should only be used in contexts where tp->tcp_mstamp is up to date */
static inline u32 tcp_time_stamp(const struct tcp_sock *tp)
{
return div_u64(tp->tcp_mstamp, USEC_PER_SEC / TCP_TS_HZ);
}
/* Could use tcp_clock_us() / 1000, but this version uses a single divide */
static inline u32 tcp_time_stamp_raw(void)
{
return div_u64(tcp_clock_ns(), NSEC_PER_SEC / TCP_TS_HZ);
}
/* Refresh 1us clock of a TCP socket,
* ensuring monotically increasing values.
*/
static inline void tcp_mstamp_refresh(struct tcp_sock *tp)
{
u64 val = tcp_clock_us();
if (val > tp->tcp_mstamp)
tp->tcp_mstamp = val;
}
static inline u32 tcp_stamp_us_delta(u64 t1, u64 t0)
{
return max_t(s64, t1 - t0, 0);
}
static inline u32 tcp_skb_timestamp(const struct sk_buff *skb)
{
return div_u64(skb->skb_mstamp, USEC_PER_SEC / TCP_TS_HZ);
}
#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
#define TCPHDR_SYN_ECN (TCPHDR_SYN | TCPHDR_ECE | TCPHDR_CWR)
/* 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/size are used in write queue only,
* cf tcp_skb_pcount()/tcp_skb_mss()
*/
__u32 tcp_tw_isn;
struct {
u16 tcp_gso_segs;
u16 tcp_gso_size;
};
};
__u8 tcp_flags; /* TCP header flags. (tcp[13]) */
__u8 sacked; /* State flags for SACK. */
#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 */
__u8 txstamp_ack:1, /* Record TX timestamp for ack? */
eor:1, /* Is skb MSG_EOR marked? */
has_rxtstamp:1, /* SKB has a RX timestamp */
unused:5;
__u32 ack_seq; /* Sequence number ACK'd */
union {
struct {
/* There is space for up to 24 bytes */
__u32 in_flight:30,/* Bytes in flight at transmit */
is_app_limited:1, /* cwnd not fully used? */
unused:1;
/* pkts S/ACKed so far upon tx of skb, incl retrans: */
__u32 delivered;
/* start of send pipeline phase */
u64 first_tx_mstamp;
/* when we reached the "delivered" count */
u64 delivered_mstamp;
} tx; /* only used for outgoing skbs */
union {
struct inet_skb_parm h4;
#if IS_ENABLED(CONFIG_IPV6)
struct inet6_skb_parm h6;
#endif
} header; /* For incoming skbs */
struct {
__u32 key;
__u32 flags;
struct bpf_map *map;
void *data_end;
} bpf;
};
};
#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)
{
bool l3_slave = ipv6_l3mdev_skb(TCP_SKB_CB(skb)->header.h6.flags);
return l3_slave ? skb->skb_iif : TCP_SKB_CB(skb)->header.h6.iif;
}
/* TCP_SKB_CB reference means this can not be used from early demux */
static inline int tcp_v6_sdif(const struct sk_buff *skb)
{
#if IS_ENABLED(CONFIG_NET_L3_MASTER_DEV)
if (skb && ipv6_l3mdev_skb(TCP_SKB_CB(skb)->header.h6.flags))
return TCP_SKB_CB(skb)->header.h6.iif;
#endif
return 0;
}
#endif
/* TCP_SKB_CB reference means this can not be used from early demux */
static inline bool inet_exact_dif_match(struct net *net, struct sk_buff *skb)
{
#if IS_ENABLED(CONFIG_NET_L3_MASTER_DEV)
if (!net->ipv4.sysctl_tcp_l3mdev_accept &&
skb && ipv4_l3mdev_skb(TCP_SKB_CB(skb)->header.h4.flags))
return true;
#endif
return false;
}
/* TCP_SKB_CB reference means this can not be used from early demux */
static inline int tcp_v4_sdif(struct sk_buff *skb)
{
#if IS_ENABLED(CONFIG_NET_L3_MASTER_DEV)
if (skb && ipv4_l3mdev_skb(TCP_SKB_CB(skb)->header.h4.flags))
return TCP_SKB_CB(skb)->header.h4.iif;
#endif
return 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 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 skb is in write queue and tcp_skb_pcount() > 1. */
static inline int tcp_skb_mss(const struct sk_buff *skb)
{
return TCP_SKB_CB(skb)->tcp_gso_size;
}
static inline bool tcp_skb_can_collapse_to(const struct sk_buff *skb)
{
return likely(!TCP_SKB_CB(skb)->eor);
}
/* 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 ack_sample {
u32 pkts_acked;
s32 rtt_us;
u32 in_flight;
};
/* A rate sample measures the number of (original/retransmitted) data
* packets delivered "delivered" over an interval of time "interval_us".
* The tcp_rate.c code fills in the rate sample, and congestion
* control modules that define a cong_control function to run at the end
* of ACK processing can optionally chose to consult this sample when
* setting cwnd and pacing rate.
* A sample is invalid if "delivered" or "interval_us" is negative.
*/
struct rate_sample {
u64 prior_mstamp; /* starting timestamp for interval */
u32 prior_delivered; /* tp->delivered at "prior_mstamp" */
s32 delivered; /* number of packets delivered over interval */
long interval_us; /* time for tp->delivered to incr "delivered" */
long rtt_us; /* RTT of last (S)ACKed packet (or -1) */
int losses; /* number of packets marked lost upon ACK */
u32 acked_sacked; /* number of packets newly (S)ACKed upon ACK */
u32 prior_in_flight; /* in flight before this ACK */
bool is_app_limited; /* is sample from packet with bubble in pipe? */
bool is_retrans; /* is sample from retransmission? */
};
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 (required) */
u32 (*undo_cwnd)(struct sock *sk);
/* hook for packet ack accounting (optional) */
void (*pkts_acked)(struct sock *sk, const struct ack_sample *sample);
/* suggest number of segments for each skb to transmit (optional) */
u32 (*tso_segs_goal)(struct sock *sk);
/* returns the multiplier used in tcp_sndbuf_expand (optional) */
u32 (*sndbuf_expand)(struct sock *sk);
/* call when packets are delivered to update cwnd and pacing rate,
* after all the ca_state processing. (optional)
*/
void (*cong_control)(struct sock *sk, const struct rate_sample *rs);
/* 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);