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tcp.h
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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 TCP_DEBUG 1
#define FASTRETRANS_DEBUG 1
#include <linux/config.h>
#include <linux/list.h>
#include <linux/tcp.h>
#include <linux/slab.h>
#include <linux/cache.h>
#include <linux/percpu.h>
#include <linux/skbuff.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 <linux/seq_file.h>
extern struct inet_hashinfo tcp_hashinfo;
extern atomic_t tcp_orphan_count;
extern void tcp_time_wait(struct sock *sk, int state, int timeo);
#define MAX_TCP_HEADER (128 + MAX_HEADER)
/*
* 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
/* Minimal RCV_MSS. */
#define TCP_MIN_RCVMSS 536U
/* 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_ORPHAN_RETRIES 7 /* number of times to retry on an orphaned
* socket. 7 is ~50sec-16min.
*/
#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)(3*HZ)) /* RFC 1122 initial RTO value */
#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_SYNQ_HSIZE 512 /* Size of SYNACK hash table */
#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 */
/*
* TCP option lengths
*/
#define TCPOLEN_MSS 4
#define TCPOLEN_WINDOW 3
#define TCPOLEN_SACK_PERM 2
#define TCPOLEN_TIMESTAMP 10
/* 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
/* 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 */
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_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_abc;
extern int sysctl_tcp_mtu_probing;
extern int sysctl_tcp_base_mss;
extern int sysctl_tcp_workaround_signed_windows;
extern atomic_t tcp_memory_allocated;
extern atomic_t 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;
}
static inline int after(__u32 seq1, __u32 seq2)
{
return (__s32)(seq2-seq1) < 0;
}
/* is s2<=s1<=s3 ? */
static inline int between(__u32 seq1, __u32 seq2, __u32 seq3)
{
return seq3 - seq2 >= seq1 - seq2;
}
extern struct proto tcp_prot;
DECLARE_SNMP_STAT(struct tcp_mib, tcp_statistics);
#define TCP_INC_STATS(field) SNMP_INC_STATS(tcp_statistics, field)
#define TCP_INC_STATS_BH(field) SNMP_INC_STATS_BH(tcp_statistics, field)
#define TCP_INC_STATS_USER(field) SNMP_INC_STATS_USER(tcp_statistics, field)
#define TCP_DEC_STATS(field) SNMP_DEC_STATS(tcp_statistics, field)
#define TCP_ADD_STATS_BH(field, val) SNMP_ADD_STATS_BH(tcp_statistics, field, val)
#define TCP_ADD_STATS_USER(field, val) SNMP_ADD_STATS_USER(tcp_statistics, field, val)
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 int tcp_v4_remember_stamp(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 ssize_t tcp_sendpage(struct socket *sock, 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,
struct tcphdr *th,
unsigned len);
extern int tcp_rcv_established(struct sock *sk,
struct sk_buff *skb,
struct tcphdr *th,
unsigned len);
extern void tcp_rcv_space_adjust(struct sock *sk);
extern int tcp_twsk_unique(struct sock *sk,
struct sock *sktw, void *twp);
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;
}
}
extern void tcp_enter_quickack_mode(struct sock *sk);
static inline void tcp_clear_options(struct tcp_options_received *rx_opt)
{
rx_opt->tstamp_ok = rx_opt->sack_ok = rx_opt->wscale_ok = rx_opt->snd_wscale = 0;
}
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 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,
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, int optlen);
extern void tcp_set_keepalive(struct sock *sk, int val);
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(struct sk_buff *skb,
struct tcp_options_received *opt_rx,
int estab);
/*
* TCP v4 functions exported for the inet6 API
*/
extern void tcp_v4_send_check(struct sock *sk, int len,
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);
extern int tcp_disconnect(struct sock *sk, int flags);
extern void tcp_unhash(struct sock *sk);
extern int tcp_v4_hash_connecting(struct sock *sk);
/* From syncookies.c */
extern struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb,
struct ip_options *opt);
extern __u32 cookie_v4_init_sequence(struct sock *sk, struct sk_buff *skb,
__u16 *mss);
/* tcp_output.c */
extern void __tcp_push_pending_frames(struct sock *sk, struct tcp_sock *tp,
unsigned int cur_mss, int nonagle);
extern int tcp_may_send_now(struct sock *sk, struct tcp_sock *tp);
extern int tcp_retransmit_skb(struct sock *, struct sk_buff *);
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 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, int large);
/* tcp.c */
extern 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);
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(struct sock *sk, int pmtu);
extern int tcp_mss_to_mtu(struct sock *sk, int mss);
extern void tcp_mtup_init(struct sock *sk);
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)
{
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 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))
/* 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 36 bytes on 32-bit architectures,
* 40 bytes on 64-bit machines, if this grows please adjust
* skbuff.h:skbuff->cb[xxx] size appropriately.
*/
struct tcp_skb_cb {
union {
struct inet_skb_parm h4;
#if defined(CONFIG_IPV6) || defined (CONFIG_IPV6_MODULE)
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 flags; /* TCP header flags. */
/* NOTE: These must match up to the flags byte in a
* real TCP header.
*/
#define TCPCB_FLAG_FIN 0x01
#define TCPCB_FLAG_SYN 0x02
#define TCPCB_FLAG_RST 0x04
#define TCPCB_FLAG_PSH 0x08
#define TCPCB_FLAG_ACK 0x10
#define TCPCB_FLAG_URG 0x20
#define TCPCB_FLAG_ECE 0x40
#define TCPCB_FLAG_CWR 0x80
__u8 sacked; /* State flags for SACK/FACK. */
#define TCPCB_SACKED_ACKED 0x01 /* SKB ACK'd by a SACK block */
#define TCPCB_SACKED_RETRANS 0x02 /* SKB retransmitted */
#define TCPCB_LOST 0x04 /* SKB is lost */
#define TCPCB_TAGBITS 0x07 /* All tag bits */
#define TCPCB_EVER_RETRANS 0x80 /* Ever retransmitted frame */
#define TCPCB_RETRANS (TCPCB_SACKED_RETRANS|TCPCB_EVER_RETRANS)
#define TCPCB_URG 0x20 /* Urgent pointer advanced here */
#define TCPCB_AT_TAIL (TCPCB_URG)
__u16 urg_ptr; /* Valid w/URG flags is set. */
__u32 ack_seq; /* Sequence number ACK'd */
};
#define TCP_SKB_CB(__skb) ((struct tcp_skb_cb *)&((__skb)->cb[0]))
#include <net/tcp_ecn.h>
/* 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)->tso_segs;
}
/* This is valid iff tcp_skb_pcount() > 1. */
static inline int tcp_skb_mss(const struct sk_buff *skb)
{
return skb_shinfo(skb)->tso_size;
}
static inline void tcp_dec_pcount_approx(__u32 *count,
const struct sk_buff *skb)
{
if (*count) {
*count -= tcp_skb_pcount(skb);
if ((int)*count < 0)
*count = 0;
}
}
static inline void tcp_packets_out_inc(struct sock *sk,
struct tcp_sock *tp,
const struct sk_buff *skb)
{
int orig = tp->packets_out;
tp->packets_out += tcp_skb_pcount(skb);
if (!orig)
inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS,
inet_csk(sk)->icsk_rto, TCP_RTO_MAX);
}
static inline void tcp_packets_out_dec(struct tcp_sock *tp,
const struct sk_buff *skb)
{
tp->packets_out -= tcp_skb_pcount(skb);
}
/* 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
struct tcp_congestion_ops {
struct list_head list;
/* 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)(struct sock *sk);
/* do new cwnd calculation (required) */
void (*cong_avoid)(struct sock *sk, u32 ack,
u32 rtt, u32 in_flight, int good_ack);
/* round trip time sample per acked packet (optional) */
void (*rtt_sample)(struct sock *sk, u32 usrtt);
/* 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);
/* 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 int tcp_set_congestion_control(struct sock *sk, const char *name);
extern void tcp_slow_start(struct tcp_sock *tp);
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 rtt, u32 in_flight, int flag);
extern u32 tcp_reno_min_cwnd(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);
}
/* 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 - tp->left_out + tp->retrans_out);
}
/* 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)));
}
static inline void tcp_sync_left_out(struct tcp_sock *tp)
{
if (tp->rx_opt.sack_ok &&
(tp->sacked_out >= tp->packets_out - tp->lost_out))
tp->sacked_out = tp->packets_out - tp->lost_out;
tp->left_out = tp->sacked_out + tp->lost_out;
}
extern void tcp_enter_cwr(struct sock *sk);
extern __u32 tcp_init_cwnd(struct tcp_sock *tp, struct dst_entry *dst);
/* Slow start with delack produces 3 packets of burst, so that
* it is safe "de facto".
*/
static __inline__ __u32 tcp_max_burst(const struct tcp_sock *tp)
{
return 3;
}
/* RFC2861 Check whether we are limited by application or congestion window
* This is the inverse of cwnd check in tcp_tso_should_defer
*/
static inline int tcp_is_cwnd_limited(const struct sock *sk, u32 in_flight)
{
const struct tcp_sock *tp = tcp_sk(sk);
u32 left;
if (in_flight >= tp->snd_cwnd)
return 1;
if (!(sk->sk_route_caps & NETIF_F_TSO))
return 0;
left = tp->snd_cwnd - in_flight;
if (sysctl_tcp_tso_win_divisor)
return left * sysctl_tcp_tso_win_divisor < tp->snd_cwnd;
else
return left <= tcp_max_burst(tp);
}
static inline void tcp_minshall_update(struct tcp_sock *tp, 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, struct tcp_sock *tp)
{
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_push_pending_frames(struct sock *sk,
struct tcp_sock *tp)
{
__tcp_push_pending_frames(sk, tp, tcp_current_mss(sk, 1), tp->nonagle);
}
static inline void tcp_init_wl(struct tcp_sock *tp, u32 ack, u32 seq)
{
tp->snd_wl1 = seq;
}
static inline void tcp_update_wl(struct tcp_sock *tp, u32 ack, u32 seq)
{
tp->snd_wl1 = seq;
}
/*
* Calculate(/check) TCP checksum
*/
static inline u16 tcp_v4_check(struct tcphdr *th, int len,
unsigned long saddr, unsigned long daddr,
unsigned long base)
{
return csum_tcpudp_magic(saddr,daddr,len,IPPROTO_TCP,base);
}
static inline int __tcp_checksum_complete(struct sk_buff *skb)
{
return __skb_checksum_complete(skb);
}
static inline int tcp_checksum_complete(struct sk_buff *skb)
{
return skb->ip_summed != CHECKSUM_UNNECESSARY &&
__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);
}
/* 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) {
__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->sk_backlog_rcv(sk, skb1);
NET_INC_STATS_BH(LINUX_MIB_TCPPREQUEUEDROPPED);
}
tp->ucopy.memory = 0;
} else if (skb_queue_len(&tp->ucopy.prequeue) == 1) {
wake_up_interruptible(sk->sk_sleep);
if (!inet_csk_ack_scheduled(sk))
inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK,
(3 * TCP_RTO_MIN) / 4,
TCP_RTO_MAX);
}
return 1;
}
return 0;
}
#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
static inline void tcp_set_state(struct sock *sk, int state)
{
int oldstate = sk->sk_state;
switch (state) {
case TCP_ESTABLISHED:
if (oldstate != TCP_ESTABLISHED)
TCP_INC_STATS(TCP_MIB_CURRESTAB);
break;
case TCP_CLOSE:
if (oldstate == TCP_CLOSE_WAIT || oldstate == TCP_ESTABLISHED)
TCP_INC_STATS(TCP_MIB_ESTABRESETS);
sk->sk_prot->unhash(sk);
if (inet_csk(sk)->icsk_bind_hash &&
!(sk->sk_userlocks & SOCK_BINDPORT_LOCK))
inet_put_port(&tcp_hashinfo, sk);
/* fall through */
default:
if (oldstate==TCP_ESTABLISHED)
TCP_DEC_STATS(TCP_MIB_CURRESTAB);
}
/* Change state AFTER socket is unhashed to avoid closed
* socket sitting in hash tables.
*/
sk->sk_state = state;
#ifdef STATE_TRACE
SOCK_DEBUG(sk, "TCP sk=%p, State %s -> %s\n",sk, statename[oldstate],statename[state]);
#endif
}
static inline void tcp_done(struct sock *sk)
{
tcp_set_state(sk, TCP_CLOSE);
tcp_clear_xmit_timers(sk);
sk->sk_shutdown = SHUTDOWN_MASK;
if (!sock_flag(sk, SOCK_DEAD))
sk->sk_state_change(sk);
else
inet_csk_destroy_sock(sk);
}
static inline void tcp_sack_reset(struct tcp_options_received *rx_opt)
{
rx_opt->dsack = 0;
rx_opt->eff_sacks = 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);
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! */
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 = skb->h.th->source;
}
extern void tcp_enter_memory_pressure(void);
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 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 rst)
{
if ((s32)(rx_opt->rcv_tsval - rx_opt->ts_recent) >= 0)
return 0;
if (xtime.tv_sec >= rx_opt->ts_recent_stamp + TCP_PAWS_24DAYS)
return 0;