Ok. I didn't make 2.4.0 in 2000. Tough. I tried, but we had some

[davej-history.git] / include / net / tcp.h

/*
 * 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, <bir7@leland.Stanford.Edu>
 * 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 TCP_DEBUG 1
#define FASTRETRANS_DEBUG 1

/* Be paranoid about data immediately beyond right edge of window. */
#undef TCP_FORMAL_WINDOW

/* Cancel timers, when they are not required. */
#undef TCP_CLEAR_TIMERS

#include <linux/config.h>
#include <linux/tcp.h>
#include <linux/slab.h>
#include <net/checksum.h>
#include <net/sock.h>

/* This is for all connections with a full identity, no wildcards.
 * New scheme, half the table is for TIME_WAIT, the other half is
 * for the rest. I'll experiment with dynamic table growth later.
 */
struct tcp_ehash_bucket {
 rwlock_t lock;
struct sock *chain;
}__attribute__((__aligned__(8)));

/* This is for listening sockets, thus all sockets which possess wildcards. */
#define TCP_LHTABLE_SIZE 32/* Yes, really, this is all you need. */

/* There are a few simple rules, which allow for local port reuse by
 * an application. In essence:
 *
 * 1) Sockets bound to different interfaces may share a local port.
 * Failing that, goto test 2.
 * 2) If all sockets have sk->reuse set, and none of them are in
 * TCP_LISTEN state, the port may be shared.
 * Failing that, goto test 3.
 * 3) If all sockets are bound to a specific sk->rcv_saddr local
 * address, and none of them are the same, the port may be
 * shared.
 * Failing this, the port cannot be shared.
 *
 * The interesting point, is test #2. This is what an FTP server does
 * all day. To optimize this case we use a specific flag bit defined
 * below. As we add sockets to a bind bucket list, we perform a
 * check of: (newsk->reuse && (newsk->state != TCP_LISTEN))
 * As long as all sockets added to a bind bucket pass this test,
 * the flag bit will be set.
 * The resulting situation is that tcp_v[46]_verify_bind() can just check
 * for this flag bit, if it is set and the socket trying to bind has
 * sk->reuse set, we don't even have to walk the owners list at all,
 * we return that it is ok to bind this socket to the requested local port.
 *
 * Sounds like a lot of work, but it is worth it. In a more naive
 * implementation (ie. current FreeBSD etc.) the entire list of ports
 * must be walked for each data port opened by an ftp server. Needless
 * to say, this does not scale at all. With a couple thousand FTP
 * users logged onto your box, isn't it nice to know that new data
 * ports are created in O(1) time? I thought so. ;-) -DaveM
 */
struct tcp_bind_bucket {
unsigned short port;
unsigned short fastreuse;
struct tcp_bind_bucket *next;
struct sock *owners;
struct tcp_bind_bucket **pprev;
};

struct tcp_bind_hashbucket {
 spinlock_t lock;
struct tcp_bind_bucket *chain;
};

externstruct tcp_hashinfo {
/* This is for sockets with full identity only. Sockets here will
 * always be without wildcards and will have the following invariant:
 *
 * TCP_ESTABLISHED <= sk->state < TCP_CLOSE
 *
 * First half of the table is for sockets not in TIME_WAIT, second half
 * is for TIME_WAIT sockets only.
 */
struct tcp_ehash_bucket *__tcp_ehash;

/* Ok, let's try this, I give up, we do need a local binding
 * TCP hash as well as the others for fast bind/connect.
 */
struct tcp_bind_hashbucket *__tcp_bhash;

int __tcp_bhash_size;
int __tcp_ehash_size;

/* All sockets in TCP_LISTEN state will be in here. This is the only
 * table where wildcard'd TCP sockets can exist. Hash function here
 * is just local port number.
 */
struct sock *__tcp_listening_hash[TCP_LHTABLE_SIZE];

/* All the above members are written once at bootup and
 * never written again _or_ are predominantly read-access.
 *
 * Now align to a new cache line as all the following members
 * are often dirty.
 */
 rwlock_t __tcp_lhash_lock
__attribute__((__aligned__(SMP_CACHE_BYTES)));
 atomic_t __tcp_lhash_users;
 wait_queue_head_t __tcp_lhash_wait;
 spinlock_t __tcp_portalloc_lock;
} tcp_hashinfo;

#define tcp_ehash (tcp_hashinfo.__tcp_ehash)
#define tcp_bhash (tcp_hashinfo.__tcp_bhash)
#define tcp_ehash_size (tcp_hashinfo.__tcp_ehash_size)
#define tcp_bhash_size (tcp_hashinfo.__tcp_bhash_size)
#define tcp_listening_hash (tcp_hashinfo.__tcp_listening_hash)
#define tcp_lhash_lock (tcp_hashinfo.__tcp_lhash_lock)
#define tcp_lhash_users (tcp_hashinfo.__tcp_lhash_users)
#define tcp_lhash_wait (tcp_hashinfo.__tcp_lhash_wait)
#define tcp_portalloc_lock (tcp_hashinfo.__tcp_portalloc_lock)

extern kmem_cache_t *tcp_bucket_cachep;
externstruct tcp_bind_bucket *tcp_bucket_create(struct tcp_bind_hashbucket *head,
unsigned short snum);
externvoidtcp_bucket_unlock(struct sock *sk);
externint tcp_port_rover;
externstruct sock *tcp_v4_lookup_listener(u32 addr,unsigned short hnum,int dif);

/* These are AF independent. */
static __inline__ inttcp_bhashfn(__u16 lport)
{
return(lport & (tcp_bhash_size -1));
}

/* This is a TIME_WAIT bucket. It works around the memory consumption
 * problems of sockets in such a state on heavily loaded servers, but
 * without violating the protocol specification.
 */
struct tcp_tw_bucket {
/* These _must_ match the beginning of struct sock precisely.
 * XXX Yes I know this is gross, but I'd have to edit every single
 * XXX networking file if I created a "struct sock_header". -DaveM
 */
 __u32 daddr;
 __u32 rcv_saddr;
 __u16 dport;
unsigned short num;
int bound_dev_if;
struct sock *next;
struct sock **pprev;
struct sock *bind_next;
struct sock **bind_pprev;
unsigned char state,
 substate;/* "zapped" is replaced with "substate" */
 __u16 sport;
unsigned short family;
unsigned char reuse,
 rcv_wscale;/* It is also TW bucket specific */
 atomic_t refcnt;

/* And these are ours. */
int hashent;
int timeout;
 __u32 rcv_nxt;
 __u32 snd_nxt;
 __u32 rcv_wnd;
 __u32 syn_seq;
 __u32 ts_recent;
long ts_recent_stamp;
unsigned long ttd;
struct tcp_bind_bucket *tb;
struct tcp_tw_bucket *next_death;
struct tcp_tw_bucket **pprev_death;

#if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
struct in6_addr v6_daddr;
struct in6_addr v6_rcv_saddr;
#endif
};

extern kmem_cache_t *tcp_timewait_cachep;

staticinlinevoidtcp_tw_put(struct tcp_tw_bucket *tw)
{
if(atomic_dec_and_test(&tw->refcnt)) {
#ifdef INET_REFCNT_DEBUG
printk(KERN_DEBUG "tw_bucket %p released\n", tw);
#endif
kmem_cache_free(tcp_timewait_cachep, tw);
}
}

extern atomic_t tcp_orphan_count;
externint tcp_tw_count;
externvoidtcp_time_wait(struct sock *sk,int state,int timeo);
externvoidtcp_timewait_kill(struct tcp_tw_bucket *tw);
externvoidtcp_tw_schedule(struct tcp_tw_bucket *tw,int timeo);
externvoidtcp_tw_deschedule(struct tcp_tw_bucket *tw);


/* Socket demux engine toys. */
#ifdef __BIG_ENDIAN
#define TCP_COMBINED_PORTS(__sport, __dport) \
 (((__u32)(__sport)<<16) | (__u32)(__dport))
#else/* __LITTLE_ENDIAN */
#define TCP_COMBINED_PORTS(__sport, __dport) \
 (((__u32)(__dport)<<16) | (__u32)(__sport))
#endif

#if (BITS_PER_LONG == 64)
#ifdef __BIG_ENDIAN
#define TCP_V4_ADDR_COOKIE(__name, __saddr, __daddr) \
 __u64 __name = (((__u64)(__saddr))<<32)|((__u64)(__daddr));
#else/* __LITTLE_ENDIAN */
#define TCP_V4_ADDR_COOKIE(__name, __saddr, __daddr) \
 __u64 __name = (((__u64)(__daddr))<<32)|((__u64)(__saddr));
#endif/* __BIG_ENDIAN */
#define TCP_IPV4_MATCH(__sk, __cookie, __saddr, __daddr, __ports, __dif)\
 (((*((__u64 *)&((__sk)->daddr)))== (__cookie)) && \
 ((*((__u32 *)&((__sk)->dport)))== (__ports)) && \
 (!((__sk)->bound_dev_if) || ((__sk)->bound_dev_if == (__dif))))
#else/* 32-bit arch */
#define TCP_V4_ADDR_COOKIE(__name, __saddr, __daddr)
#define TCP_IPV4_MATCH(__sk, __cookie, __saddr, __daddr, __ports, __dif)\
 (((__sk)->daddr == (__saddr)) && \
 ((__sk)->rcv_saddr == (__daddr)) && \
 ((*((__u32 *)&((__sk)->dport)))== (__ports)) && \
 (!((__sk)->bound_dev_if) || ((__sk)->bound_dev_if == (__dif))))
#endif/* 64-bit arch */

#define TCP_IPV6_MATCH(__sk, __saddr, __daddr, __ports, __dif) \
 (((*((__u32 *)&((__sk)->dport)))== (__ports)) && \
 ((__sk)->family == AF_INET6) && \
 !ipv6_addr_cmp(&(__sk)->net_pinfo.af_inet6.daddr, (__saddr)) && \
 !ipv6_addr_cmp(&(__sk)->net_pinfo.af_inet6.rcv_saddr, (__daddr)) && \
 (!((__sk)->bound_dev_if) || ((__sk)->bound_dev_if == (__dif))))

/* These can have wildcards, don't try too hard. */
static __inline__ inttcp_lhashfn(unsigned short num)
{
return num & (TCP_LHTABLE_SIZE -1);
}

static __inline__ inttcp_sk_listen_hashfn(struct sock *sk)
{
returntcp_lhashfn(sk->num);
}

#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 32767

/* Minimal accepted MSS. It is (60+60+8) - (20+20). */
#define TCP_MIN_MSS 88

/* Minimal RCV_MSS. */
#define TCP_MIN_RCVMSS 536

/* 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 16

/* 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 minumum */

#define TCP_SYNACK_RETRIES 5/* number of times to retry passive opening a
 * connection: ~180sec is RFC minumum */


#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 (HZ/5)/* maximal time to delay before sending an ACK */
#if HZ >= 100
#define TCP_DELACK_MIN (HZ/25)/* minimal time to delay before sending an ACK */
#define TCP_ATO_MIN (HZ/25)
#else
#define TCP_DELACK_MIN 4
#define TCP_ATO_MIN 4
#endif
#define TCP_RTO_MAX (120*HZ)
#define TCP_RTO_MIN (HZ/5)
#define TCP_TIMEOUT_INIT (3*HZ)/* RFC 1122 initial RTO value */

#define TCP_RESOURCE_PROBE_INTERVAL (HZ/2)/* 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

/* TIME_WAIT reaping mechanism. */
#define TCP_TWKILL_SLOTS 8/* Please keep this a power of 2. */
#define TCP_TWKILL_PERIOD (TCP_TIMEWAIT_LEN/TCP_TWKILL_SLOTS)

#define TCP_SYNQ_INTERVAL (HZ/5)/* Period of SYNACK timer */
#define TCP_SYNQ_HSIZE 64/* 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.
 */

#define TCP_TW_RECYCLE_SLOTS_LOG 5
#define TCP_TW_RECYCLE_SLOTS (1<<TCP_TW_RECYCLE_SLOTS_LOG)

/* If time > 4sec, it is "slow" path, no recycling is required,
 so that we select tick to get range about 4 seconds.
 */

#if HZ <= 16 || HZ > 4096
# error Unsupported: HZ <= 16 or HZ > 4096
#elif HZ <= 32
# define TCP_TW_RECYCLE_TICK (5+2-TCP_TW_RECYCLE_SLOTS_LOG)
#elif HZ <= 64
# define TCP_TW_RECYCLE_TICK (6+2-TCP_TW_RECYCLE_SLOTS_LOG)
#elif HZ <= 128
# define TCP_TW_RECYCLE_TICK (7+2-TCP_TW_RECYCLE_SLOTS_LOG)
#elif HZ <= 256
# define TCP_TW_RECYCLE_TICK (8+2-TCP_TW_RECYCLE_SLOTS_LOG)
#elif HZ <= 512
# define TCP_TW_RECYCLE_TICK (9+2-TCP_TW_RECYCLE_SLOTS_LOG)
#elif HZ <= 1024
# define TCP_TW_RECYCLE_TICK (10+2-TCP_TW_RECYCLE_SLOTS_LOG)
#elif HZ <= 2048
# define TCP_TW_RECYCLE_TICK (11+2-TCP_TW_RECYCLE_SLOTS_LOG)
#else
# define TCP_TW_RECYCLE_TICK (12+2-TCP_TW_RECYCLE_SLOTS_LOG)
#endif

/*
 * 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

#define TCP_TIME_RETRANS 1/* Retransmit timer */
#define TCP_TIME_DACK 2/* Delayed ack timer */
#define TCP_TIME_PROBE0 3/* Zero window probe timer */
#define TCP_TIME_KEEPOPEN 4/* Keepalive timer */

/* sysctl variables for tcp */
externint sysctl_max_syn_backlog;
externint sysctl_tcp_timestamps;
externint sysctl_tcp_window_scaling;
externint sysctl_tcp_sack;
externint sysctl_tcp_fin_timeout;
externint sysctl_tcp_tw_recycle;
externint sysctl_tcp_keepalive_time;
externint sysctl_tcp_keepalive_probes;
externint sysctl_tcp_keepalive_intvl;
externint sysctl_tcp_syn_retries;
externint sysctl_tcp_synack_retries;
externint sysctl_tcp_retries1;
externint sysctl_tcp_retries2;
externint sysctl_tcp_orphan_retries;
externint sysctl_tcp_syncookies;
externint sysctl_tcp_retrans_collapse;
externint sysctl_tcp_stdurg;
externint sysctl_tcp_rfc1337;
externint sysctl_tcp_tw_recycle;
externint sysctl_tcp_abort_on_overflow;
externint sysctl_tcp_max_orphans;
externint sysctl_tcp_max_tw_buckets;
externint sysctl_tcp_fack;
externint sysctl_tcp_reordering;
externint sysctl_tcp_ecn;
externint sysctl_tcp_dsack;
externint sysctl_tcp_mem[3];
externint sysctl_tcp_wmem[3];
externint sysctl_tcp_rmem[3];
externint sysctl_tcp_app_win;
externint sysctl_tcp_adv_win_scale;

extern atomic_t tcp_memory_allocated;
extern atomic_t tcp_sockets_allocated;
externint tcp_memory_pressure;

struct open_request;

struct or_calltable {
int family;
int(*rtx_syn_ack) (struct sock *sk,struct open_request *req,struct dst_entry*);
void(*send_ack) (struct sk_buff *skb,struct open_request *req);
void(*destructor) (struct open_request *req);
void(*send_reset) (struct sk_buff *skb);
};

struct tcp_v4_open_req {
 __u32 loc_addr;
 __u32 rmt_addr;
struct ip_options *opt;
};

#if defined(CONFIG_IPV6) || defined (CONFIG_IPV6_MODULE)
struct tcp_v6_open_req {
struct in6_addr loc_addr;
struct in6_addr rmt_addr;
struct sk_buff *pktopts;
int iif;
};
#endif

/* this structure is too big */
struct open_request {
struct open_request *dl_next;/* Must be first member! */
 __u32 rcv_isn;
 __u32 snt_isn;
 __u16 rmt_port;
 __u16 mss;
 __u8 retrans;
 __u8 index;
 __u16 snd_wscale :4,
 rcv_wscale :4,
 tstamp_ok :1,
 sack_ok :1,
 wscale_ok :1,
 ecn_ok :1,
 acked :1;
/* The following two fields can be easily recomputed I think -AK */
 __u32 window_clamp;/* window clamp at creation time */
 __u32 rcv_wnd;/* rcv_wnd offered first time */
 __u32 ts_recent;
unsigned long expires;
struct or_calltable *class;
struct sock *sk;
union{
struct tcp_v4_open_req v4_req;
#if defined(CONFIG_IPV6) || defined (CONFIG_IPV6_MODULE)
struct tcp_v6_open_req v6_req;
#endif
} af;
};

/* SLAB cache for open requests. */
extern kmem_cache_t *tcp_openreq_cachep;

#define tcp_openreq_alloc() kmem_cache_alloc(tcp_openreq_cachep, SLAB_ATOMIC)
#define tcp_openreq_fastfree(req) kmem_cache_free(tcp_openreq_cachep, req)

staticinlinevoidtcp_openreq_free(struct open_request *req)
{
 req->class->destructor(req);
tcp_openreq_fastfree(req);
}

#if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
#define TCP_INET_FAMILY(fam) ((fam) == AF_INET)
#else
#define TCP_INET_FAMILY(fam) 1
#endif

/*
 * Pointers to address related TCP functions
 * (i.e. things that depend on the address family)
 *
 * BUGGG_FUTURE: all the idea behind this struct is wrong.
 * It mixes socket frontend with transport function.
 * With port sharing between IPv6/v4 it gives the only advantage,
 * only poor IPv6 needs to permanently recheck, that it
 * is still IPv6 8)8) It must be cleaned up as soon as possible.
 * --ANK (980802)
 */

struct tcp_func {
int(*queue_xmit) (struct sk_buff *skb);

void(*send_check) (struct sock *sk,
struct tcphdr *th,
int len,
struct sk_buff *skb);

int(*rebuild_header) (struct sock *sk);

int(*conn_request) (struct sock *sk,
struct sk_buff *skb);

struct sock * (*syn_recv_sock) (struct sock *sk,
struct sk_buff *skb,
struct open_request *req,
struct dst_entry *dst);

int(*hash_connecting) (struct sock *sk);

int(*remember_stamp) (struct sock *sk);

 __u16 net_header_len;

int(*setsockopt) (struct sock *sk,
int level,
int optname,
char*optval,
int optlen);

int(*getsockopt) (struct sock *sk,
int level,
int optname,
char*optval,
int*optlen);


void(*addr2sockaddr) (struct sock *sk,
struct sockaddr *);

int sockaddr_len;
};

/*
 * The next routines deal with comparing 32 bit unsigned ints
 * and worry about wraparound (automatic with unsigned arithmetic).
 */

extern __inline intbefore(__u32 seq1, __u32 seq2)
{
return(__s32)(seq1-seq2) <0;
}

extern __inline intafter(__u32 seq1, __u32 seq2)
{
return(__s32)(seq2-seq1) <0;
}


/* is s2<=s1<=s3 ? */
extern __inline intbetween(__u32 seq1, __u32 seq2, __u32 seq3)
{
return seq3 - seq2 >= seq1 - seq2;
}


externstruct proto tcp_prot;

externstruct tcp_mib tcp_statistics[NR_CPUS*2];
#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)

externvoidtcp_put_port(struct sock *sk);
externvoid__tcp_put_port(struct sock *sk);
externvoidtcp_inherit_port(struct sock *sk,struct sock *child);

externvoidtcp_v4_err(struct sk_buff *skb,
unsigned char*,int);

externvoidtcp_shutdown(struct sock *sk,int how);

externinttcp_v4_rcv(struct sk_buff *skb,
unsigned short len);

externinttcp_v4_remember_stamp(struct sock *sk);

externinttcp_v4_tw_remember_stamp(struct tcp_tw_bucket *tw);

externinttcp_sendmsg(struct sock *sk,struct msghdr *msg,int size);

externinttcp_ioctl(struct sock *sk,
int cmd,
unsigned long arg);

externinttcp_rcv_state_process(struct sock *sk,
struct sk_buff *skb,
struct tcphdr *th,
unsigned len);

externinttcp_rcv_established(struct sock *sk,
struct sk_buff *skb,
struct tcphdr *th,
unsigned len);

enum tcp_ack_state_t
{
 TCP_ACK_SCHED =1,
 TCP_ACK_TIMER =2,
 TCP_ACK_PUSHED=4
};

staticinlinevoidtcp_schedule_ack(struct tcp_opt *tp)
{
 tp->ack.pending |= TCP_ACK_SCHED;
}

staticinlineinttcp_ack_scheduled(struct tcp_opt *tp)
{
return tp->ack.pending&TCP_ACK_SCHED;
}

static __inline__ voidtcp_dec_quickack_mode(struct tcp_opt *tp)
{
if(tp->ack.quick && --tp->ack.quick ==0) {
/* Leaving quickack mode we deflate ATO. */
 tp->ack.ato = TCP_ATO_MIN;
}
}

externvoidtcp_enter_quickack_mode(struct tcp_opt *tp);

static __inline__ voidtcp_delack_init(struct tcp_opt *tp)
{
memset(&tp->ack,0,sizeof(tp->ack));
}

staticinlinevoidtcp_clear_options(struct tcp_opt *tp)
{
 tp->tstamp_ok = tp->sack_ok = tp->wscale_ok = tp->snd_wscale =0;
}

enum tcp_tw_status
{
 TCP_TW_SUCCESS =0,
 TCP_TW_RST =1,
 TCP_TW_ACK =2,
 TCP_TW_SYN =3
};


externenum tcp_tw_status tcp_timewait_state_process(struct tcp_tw_bucket *tw,
struct sk_buff *skb,
struct tcphdr *th,
unsigned len);

externstruct sock *tcp_check_req(struct sock *sk,struct sk_buff *skb,
struct open_request *req,
struct open_request **prev);
externinttcp_child_process(struct sock *parent,
struct sock *child,
struct sk_buff *skb);
externvoidtcp_enter_loss(struct sock *sk,int how);
externvoidtcp_clear_retrans(struct tcp_opt *tp);
externvoidtcp_update_metrics(struct sock *sk);

externvoidtcp_close(struct sock *sk,
long timeout);
externstruct sock *tcp_accept(struct sock *sk,int flags,int*err);
externunsigned inttcp_poll(struct file * file,struct socket *sock,struct poll_table_struct *wait);
externvoidtcp_write_space(struct sock *sk);

externinttcp_getsockopt(struct sock *sk,int level,
int optname,char*optval,
int*optlen);
externinttcp_setsockopt(struct sock *sk,int level,
int optname,char*optval,
int optlen);
externvoidtcp_set_keepalive(struct sock *sk,int val);
externinttcp_recvmsg(struct sock *sk,
struct msghdr *msg,
int len,int nonblock,
int flags,int*addr_len);

externinttcp_listen_start(struct sock *sk);

externvoidtcp_parse_options(struct sk_buff *skb,
struct tcp_opt *tp,
int estab);

/*
 * TCP v4 functions exported for the inet6 API
 */

externinttcp_v4_rebuild_header(struct sock *sk);

externinttcp_v4_build_header(struct sock *sk,
struct sk_buff *skb);

externvoidtcp_v4_send_check(struct sock *sk,
struct tcphdr *th,int len,
struct sk_buff *skb);

externinttcp_v4_conn_request(struct sock *sk,
struct sk_buff *skb);

externstruct sock *tcp_create_openreq_child(struct sock *sk,
struct open_request *req,
struct sk_buff *skb);

externstruct sock *tcp_v4_syn_recv_sock(struct sock *sk,
struct sk_buff *skb,
struct open_request *req,
struct dst_entry *dst);

externinttcp_v4_do_rcv(struct sock *sk,
struct sk_buff *skb);

externinttcp_v4_connect(struct sock *sk,
struct sockaddr *uaddr,
int addr_len);

externinttcp_connect(struct sock *sk,
struct sk_buff *skb);

externstruct sk_buff *tcp_make_synack(struct sock *sk,
struct dst_entry *dst,
struct open_request *req);

externinttcp_disconnect(struct sock *sk,int flags);

externvoidtcp_unhash(struct sock *sk);

externinttcp_v4_hash_connecting(struct sock *sk);


/* From syncookies.c */
externstruct 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 */

externinttcp_write_xmit(struct sock *);
externinttcp_retransmit_skb(struct sock *,struct sk_buff *);
externvoidtcp_xmit_retransmit_queue(struct sock *);
externvoidtcp_simple_retransmit(struct sock *);

externvoidtcp_send_probe0(struct sock *);
externvoidtcp_send_partial(struct sock *);
externinttcp_write_wakeup(struct sock *);
externvoidtcp_send_fin(struct sock *sk);
externvoidtcp_send_active_reset(struct sock *sk,int priority);
externinttcp_send_synack(struct sock *);
externinttcp_transmit_skb(struct sock *,struct sk_buff *);
externvoidtcp_send_skb(struct sock *,struct sk_buff *,int force_queue,unsigned mss_now);
externvoidtcp_send_ack(struct sock *sk);
externvoidtcp_send_delayed_ack(struct sock *sk);

/* tcp_timer.c */
externvoidtcp_init_xmit_timers(struct sock *);
externvoidtcp_clear_xmit_timers(struct sock *);

externvoidtcp_delete_keepalive_timer(struct sock *);
externvoidtcp_reset_keepalive_timer(struct sock *,unsigned long);
externinttcp_sync_mss(struct sock *sk, u32 pmtu);

externconst char timer_bug_msg[];


staticinlinevoidtcp_clear_xmit_timer(struct sock *sk,int what)
{
struct tcp_opt *tp = &sk->tp_pinfo.af_tcp;

switch(what) {
case TCP_TIME_RETRANS:
case TCP_TIME_PROBE0:
 tp->pending =0;

#ifdef TCP_CLEAR_TIMERS
if(timer_pending(&tp->retransmit_timer) &&
del_timer(&tp->retransmit_timer))
__sock_put(sk);
#endif
break;
case TCP_TIME_DACK:
 tp->ack.blocked =0;
 tp->ack.pending =0;

#ifdef TCP_CLEAR_TIMERS
if(timer_pending(&tp->delack_timer) &&
del_timer(&tp->delack_timer))
__sock_put(sk);
#endif
break;
default:
printk(timer_bug_msg);
return;
};

}

/*
 * Reset the retransmission timer
 */
staticinlinevoidtcp_reset_xmit_timer(struct sock *sk,int what,unsigned long when)
{
struct tcp_opt *tp = &sk->tp_pinfo.af_tcp;

if(when > TCP_RTO_MAX) {
#ifdef TCP_DEBUG
printk(KERN_DEBUG "reset_xmit_timer sk=%p %d when=0x%lx, caller=%p\n", sk, what, when,current_text_addr());
#endif
 when = TCP_RTO_MAX;
}

switch(what) {
case TCP_TIME_RETRANS:
case TCP_TIME_PROBE0:
 tp->pending = what;
 tp->timeout = jiffies+when;
if(!mod_timer(&tp->retransmit_timer, tp->timeout))
sock_hold(sk);
break;

case TCP_TIME_DACK:
 tp->ack.pending |= TCP_ACK_TIMER;
 tp->ack.timeout = jiffies+when;
if(!mod_timer(&tp->delack_timer, tp->ack.timeout))
sock_hold(sk);
break;

default:
printk(KERN_DEBUG "bug: unknown timer value\n");
};
}

/* Compute the current effective MSS, taking SACKs and IP options,
 * and even PMTU discovery events into account.
 */

static __inline__ unsigned inttcp_current_mss(struct sock *sk)
{
struct tcp_opt *tp = &sk->tp_pinfo.af_tcp;
struct dst_entry *dst =__sk_dst_get(sk);
int mss_now = tp->mss_cache;

if(dst && dst->pmtu != tp->pmtu_cookie)
 mss_now =tcp_sync_mss(sk, dst->pmtu);

if(tp->eff_sacks)
 mss_now -= (TCPOLEN_SACK_BASE_ALIGNED +
(tp->eff_sacks * TCPOLEN_SACK_PERBLOCK));
return mss_now;
}

/* Initialize RCV_MSS value.
 * RCV_MSS is an our guess about MSS used by the peer.
 * We haven't any direct information about the MSS.
 * It's better to underestimate the RCV_MSS rather than overestimate.
 * Overestimations make us ACKing less frequently than needed.
 * Underestimations are more easy to detect and fix by tcp_measure_rcv_mss().
 */

staticinlinevoidtcp_initialize_rcv_mss(struct sock *sk)
{
struct tcp_opt *tp = &sk->tp_pinfo.af_tcp;
int hint =min(tp->advmss, tp->mss_cache);

 hint =min(hint, tp->rcv_wnd/2);

 tp->ack.rcv_mss =max(min(hint, TCP_MIN_RCVMSS), TCP_MIN_MSS);
}

static __inline__ void__tcp_fast_path_on(struct tcp_opt *tp, u32 snd_wnd)
{
 tp->pred_flags =htonl((tp->tcp_header_len <<26) |
ntohl(TCP_FLAG_ACK) |
 snd_wnd);
}

static __inline__ voidtcp_fast_path_on(struct tcp_opt *tp)
{
__tcp_fast_path_on(tp, tp->snd_wnd>>tp->snd_wscale);
}

/* 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(struct tcp_opt *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 decidely
 * only use of 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 queueing 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 advenced 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]))

#define for_retrans_queue(skb, sk, tp) \
 for (skb = (sk)->write_queue.next; \
 (skb != (tp)->send_head) && \
 (skb != (struct sk_buff *)&(sk)->write_queue); \
 skb=skb->next)


#include <net/tcp_ecn.h>


/*
 * Compute minimal free write space needed to queue new packets. 
 */
staticinlineinttcp_min_write_space(struct sock *sk)
{
return sk->wmem_queued/2;
}

staticinlineinttcp_wspace(struct sock *sk)
{
return sk->sndbuf - sk->wmem_queued;
}


/* 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__ inttcp_packets_in_flight(struct tcp_opt *tp)
{
return tp->packets_out - tp->left_out + tp->retrans_out;
}

/* Recalculate snd_ssthresh, we want to set it to:
 *
 * one half the current congestion window, but no
 * less than two segments
 */
staticinline __u32 tcp_recalc_ssthresh(struct tcp_opt *tp)
{
returnmax(tp->snd_cwnd>>1,2);
}

/* 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.
 */
staticinline __u32 tcp_current_ssthresh(struct tcp_opt *tp)
{
if((1<<tp->ca_state)&(TCPF_CA_CWR|TCPF_CA_Recovery))
return tp->snd_ssthresh;
else
returnmax(tp->snd_ssthresh, (tp->snd_cwnd>>1)+(tp->snd_cwnd>>2));
}

externvoidtcp_cwnd_application_limited(struct sock *sk);

/* Congestion window validation. (RFC2861) */

staticinlinevoidtcp_cwnd_validate(struct sock *sk,struct tcp_opt *tp)
{
if(tp->packets_out >= tp->snd_cwnd) {
/* Network is feed fully. */
 tp->snd_cwnd_used =0;
 tp->snd_cwnd_stamp = tcp_time_stamp;
}else{
/* Network starves. */
if(tp->packets_out > tp->snd_cwnd_used)
 tp->snd_cwnd_used = tp->packets_out;

if((s32)(tcp_time_stamp - tp->snd_cwnd_stamp) >= tp->rto)
tcp_cwnd_application_limited(sk);
}
}

/* Set slow start threshould and cwnd not falling to slow start */
staticinlinevoid__tcp_enter_cwr(struct tcp_opt *tp)
{
 tp->undo_marker =0;
 tp->snd_ssthresh =tcp_recalc_ssthresh(tp);
 tp->snd_cwnd =min(tp->snd_cwnd,tcp_packets_in_flight(tp)+1);
 tp->snd_cwnd_cnt =0;
 tp->high_seq = tp->snd_nxt;
 tp->snd_cwnd_stamp = tcp_time_stamp;
TCP_ECN_queue_cwr(tp);
}

staticinlinevoidtcp_enter_cwr(struct tcp_opt *tp)
{
 tp->prior_ssthresh =0;
if(tp->ca_state < TCP_CA_CWR) {
__tcp_enter_cwr(tp);
 tp->ca_state = TCP_CA_CWR;
}
}

extern __u32 tcp_init_cwnd(struct tcp_opt *tp);

/* Slow start with delack produces 3 packets of burst, so that
 * it is safe "de facto".
 */
static __inline__ __u32 tcp_max_burst(struct tcp_opt *tp)
{
return3;
}

static __inline__ inttcp_minshall_check(struct tcp_opt *tp)
{
returnafter(tp->snd_sml,tp->snd_una) &&
!after(tp->snd_sml, tp->snd_nxt);
}

static __inline__ voidtcp_minshall_update(struct tcp_opt *tp,int mss,struct sk_buff *skb)
{
if(skb->len < mss)
 tp->snd_sml =TCP_SKB_CB(skb)->end_seq;
}

/* Return 0, if packet can be sent now without violation Nagle's rules:
 1. It is full sized.
 2. Or it contains FIN.
 3. Or TCP_NODELAY was set.
 4. Or TCP_CORK is not set, and all sent packets are ACKed.
 With Minshall's modification: all sent small packets are ACKed.
 */

static __inline__ int
tcp_nagle_check(struct tcp_opt *tp,struct sk_buff *skb,unsigned mss_now,int nonagle)
{
return(skb->len < mss_now &&
!(TCP_SKB_CB(skb)->flags & TCPCB_FLAG_FIN) &&
(nonagle ==2||
(!nonagle &&
 tp->packets_out &&
tcp_minshall_check(tp))));
}

/* This checks if the data bearing packet SKB (usually tp->send_head)
 * should be put on the wire right now.
 */
static __inline__ inttcp_snd_test(struct tcp_opt *tp,struct sk_buff *skb,
unsigned cur_mss,int nonagle)
{
/* RFC 1122 - section 4.2.3.4
 *
 * We must queue if
 *
 * a) The right edge of this frame exceeds the window
 * b) There are packets in flight and we have a small segment
 * [SWS avoidance and Nagle algorithm]
 * (part of SWS is done on packetization)
 * Minshall version sounds: there are no _small_
 * segments in flight. (tcp_nagle_check)
 * c) We have too many packets 'in flight'
 *
 * Don't use the nagle rule for urgent data (or
 * for the final FIN -DaveM).
 *
 * Also, Nagle rule does not apply to frames, which
 * sit in the middle of queue (they have no chances
 * to get new data) and if room at tail of skb is
 * not enough to save something seriously (<32 for now).
 */

/* Don't be strict about the congestion window for the
 * final FIN frame. -DaveM
 */
return((nonagle==1|| tp->urg_mode
|| !tcp_nagle_check(tp, skb, cur_mss, nonagle)) &&
((tcp_packets_in_flight(tp) < tp->snd_cwnd) ||
(TCP_SKB_CB(skb)->flags & TCPCB_FLAG_FIN)) &&
!after(TCP_SKB_CB(skb)->end_seq, tp->snd_una + tp->snd_wnd));
}

static __inline__ voidtcp_check_probe_timer(struct sock *sk,struct tcp_opt *tp)
{
if(!tp->packets_out && !tp->pending)
tcp_reset_xmit_timer(sk, TCP_TIME_PROBE0, tp->rto);
}

static __inline__ inttcp_skb_is_last(struct sock *sk,struct sk_buff *skb)
{
return(skb->next == (struct sk_buff*)&sk->write_queue);
}

/* Push out any pending frames which were held back due to
 * TCP_CORK or attempt at coalescing tiny packets.
 * The socket must be locked by the caller.
 */
static __inline__ void__tcp_push_pending_frames(struct sock *sk,
struct tcp_opt *tp,
unsigned cur_mss,
int nonagle)
{
struct sk_buff *skb = tp->send_head;

if(skb) {
if(!tcp_skb_is_last(sk, skb))
 nonagle =1;
if(!tcp_snd_test(tp, skb, cur_mss, nonagle) ||
tcp_write_xmit(sk))
tcp_check_probe_timer(sk, tp);
}
tcp_cwnd_validate(sk, tp);
}

static __inline__ voidtcp_push_pending_frames(struct sock *sk,
struct tcp_opt *tp)
{
__tcp_push_pending_frames(sk, tp,tcp_current_mss(sk), tp->nonagle);
}

static __inline__ inttcp_may_send_now(struct sock *sk,struct tcp_opt *tp)
{
struct sk_buff *skb = tp->send_head;

return(skb &&
tcp_snd_test(tp, skb,tcp_current_mss(sk),
tcp_skb_is_last(sk, skb) ?1: tp->nonagle));
}

static __inline__ voidtcp_init_wl(struct tcp_opt *tp, u32 ack, u32 seq)
{
 tp->snd_wl1 = seq;
}

static __inline__ voidtcp_update_wl(struct tcp_opt *tp, u32 ack, u32 seq)
{
 tp->snd_wl1 = seq;
}

externvoidtcp_destroy_sock(struct sock *sk);


/*
 * Calculate(/check) TCP checksum
 */
static __inline__ u16 tcp_v4_check(struct tcphdr *th,int len,
unsigned long saddr,unsigned long daddr,
unsigned long base)
{
returncsum_tcpudp_magic(saddr,daddr,len,IPPROTO_TCP,base);
}

static __inline__ int__tcp_checksum_complete(struct sk_buff *skb)
{
return(unsigned short)csum_fold(csum_partial(skb->h.raw, skb->len, skb->csum));
}

static __inline__ inttcp_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__ voidtcp_prequeue_init(struct tcp_opt *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
 */
static __inline__ inttcp_prequeue(struct sock *sk,struct sk_buff *skb)
{
struct tcp_opt *tp = &sk->tp_pinfo.af_tcp;

if(tp->ucopy.task) {
if((tp->ucopy.memory += skb->truesize) <= (sk->rcvbuf<<1)) {
__skb_queue_tail(&tp->ucopy.prequeue, skb);
if(skb_queue_len(&tp->ucopy.prequeue) ==1) {
wake_up_interruptible(sk->sleep);
if(!tcp_ack_scheduled(tp))
tcp_reset_xmit_timer(sk, TCP_TIME_DACK, (3*TCP_RTO_MIN)/4);
}
}else{
NET_INC_STATS_BH(TCPPrequeueDropped);
 tp->ucopy.memory -= skb->truesize;
__kfree_skb(skb);
}
return1;
}
return0;
}


#undef STATE_TRACE

#ifdef STATE_TRACE
static 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__ voidtcp_set_state(struct sock *sk,int state)
{
int oldstate = sk->state;

switch(state) {
case TCP_ESTABLISHED:
if(oldstate != TCP_ESTABLISHED)
TCP_INC_STATS(TcpCurrEstab);
break;

case TCP_CLOSE:
 sk->prot->unhash(sk);
if(sk->prev && !(sk->userlocks&SOCK_BINDPORT_LOCK))
tcp_put_port(sk);
/* fall through */
default:
if(oldstate==TCP_ESTABLISHED)
 tcp_statistics[smp_processor_id()*2+!in_softirq()].TcpCurrEstab--;
}

/* Change state AFTER socket is unhashed to avoid closed
 * socket sitting in hash tables.
 */
 sk->state = state;

#ifdef STATE_TRACE
SOCK_DEBUG(sk,"TCP sk=%p, State %s -> %s\n",sk, statename[oldstate],statename[state]);
#endif 
}

static __inline__ voidtcp_done(struct sock *sk)
{
tcp_set_state(sk, TCP_CLOSE);
tcp_clear_xmit_timers(sk);

 sk->shutdown = SHUTDOWN_MASK;

if(!sk->dead)
 sk->state_change(sk);
else
tcp_destroy_sock(sk);
}

static __inline__ voidtcp_sack_reset(struct tcp_opt *tp)
{
 tp->dsack =0;
 tp->eff_sacks =0;
 tp->num_sacks =0;
}

static __inline__ voidtcp_build_and_update_options(__u32 *ptr,struct tcp_opt *tp, __u32 tstamp)
{
if(tp->tstamp_ok) {
*ptr++ =__constant_htonl((TCPOPT_NOP <<24) |
(TCPOPT_NOP <<16) |
(TCPOPT_TIMESTAMP <<8) |
 TCPOLEN_TIMESTAMP);
*ptr++ =htonl(tstamp);
*ptr++ =htonl(tp->ts_recent);
}
if(tp->eff_sacks) {
struct tcp_sack_block *sp = tp->dsack ? tp->duplicate_sack : tp->selective_acks;
int this_sack;

*ptr++ =__constant_htonl((TCPOPT_NOP <<24) |
(TCPOPT_NOP <<16) |
(TCPOPT_SACK <<8) |
(TCPOLEN_SACK_BASE +
(tp->eff_sacks * TCPOLEN_SACK_PERBLOCK)));
for(this_sack =0; this_sack < tp->eff_sacks; this_sack++) {
*ptr++ =htonl(sp[this_sack].start_seq);
*ptr++ =htonl(sp[this_sack].end_seq);
}
if(tp->dsack) {
 tp->dsack =0;
 tp->eff_sacks--;
}
}
}

/* Construct a tcp options header for a SYN or SYN_ACK packet.
 * If this is every changed make sure to change the definition of
 * MAX_SYN_SIZE to match the new maximum number of options that you
 * can generate.
 */
staticinlinevoidtcp_syn_build_options(__u32 *ptr,int mss,int ts,int sack,
int offer_wscale,int wscale, __u32 tstamp, __u32 ts_recent)
{
/* We always get an MSS option.
 * The option bytes which will be seen in normal data
 * packets should timestamps be used, must be in the MSS
 * advertised. But we subtract them from tp->mss_cache so
 * that calculations in tcp_sendmsg are simpler etc.
 * So account for this fact here if necessary. If we
 * don't do this correctly, as a receiver we won't
 * recognize data packets as being full sized when we
 * should, and thus we won't abide by the delayed ACK
 * rules correctly.
 * SACKs don't matter, we never delay an ACK when we
 * have any of those going out.
 */
*ptr++ =htonl((TCPOPT_MSS <<24) | (TCPOLEN_MSS <<16) | mss);
if(ts) {
if(sack)
*ptr++ =__constant_htonl((TCPOPT_SACK_PERM <<24) | (TCPOLEN_SACK_PERM <<16) |
(TCPOPT_TIMESTAMP <<8) | TCPOLEN_TIMESTAMP);
else
*ptr++ =__constant_htonl((TCPOPT_NOP <<24) | (TCPOPT_NOP <<16) |
(TCPOPT_TIMESTAMP <<8) | TCPOLEN_TIMESTAMP);
*ptr++ =htonl(tstamp);/* TSVAL */
*ptr++ =htonl(ts_recent);/* TSECR */
}else if(sack)
*ptr++ =__constant_htonl((TCPOPT_NOP <<24) | (TCPOPT_NOP <<16) |
(TCPOPT_SACK_PERM <<8) | TCPOLEN_SACK_PERM);
if(offer_wscale)
*ptr++ =htonl((TCPOPT_NOP <<24) | (TCPOPT_WINDOW <<16) | (TCPOLEN_WINDOW <<8) | (wscale));
}

/* Determine a window scaling and initial window to offer.
 * Based on the assumption that the given amount of space
 * will be offered. Store the results in the tp structure.
 * NOTE: for smooth operation initial space offering should
 * be a multiple of mss if possible. We assume here that mss >= 1.
 * This MUST be enforced by all callers.
 */
staticinlinevoidtcp_select_initial_window(int space, __u32 mss,
 __u32 *rcv_wnd,
 __u32 *window_clamp,
int wscale_ok,
 __u8 *rcv_wscale)
{
/* If no clamp set the clamp to the max possible scaled window */
if(*window_clamp ==0)
(*window_clamp) = (65535<<14);
 space =min(*window_clamp,space);

/* Quantize space offering to a multiple of mss if possible. */
if(space > mss)
 space = (space/mss)*mss;

/* NOTE: offering an initial window larger than 32767
 * will break some buggy TCP stacks. We try to be nice.
 * If we are not window scaling, then this truncates
 * our initial window offering to 32k. There should also
 * be a sysctl option to stop being nice.
 */
(*rcv_wnd) =min(space, MAX_TCP_WINDOW);
(*rcv_wscale) =0;
if(wscale_ok) {
/* See RFC1323 for an explanation of the limit to 14 */
while(space >65535&& (*rcv_wscale) <14) {
 space >>=1;
(*rcv_wscale)++;
}
if(*rcv_wscale && sysctl_tcp_app_win && space>=mss &&
 space -max((space>>sysctl_tcp_app_win), mss>>*rcv_wscale) <65536/2)
(*rcv_wscale)--;
}

/* Set initial window to value enough for senders,
 * following RFC1414. Senders, not following this RFC,
 * will be satisfied with 2.
 */
if(mss > (1<<*rcv_wscale)) {
int init_cwnd =4;
if(mss >1460*3)
 init_cwnd =2;
else if(mss >1460)
 init_cwnd =3;
if(*rcv_wnd > init_cwnd*mss)
*rcv_wnd = init_cwnd*mss;
}
/* Set the clamp no higher than max representable value */
(*window_clamp) =min(65535<<(*rcv_wscale),*window_clamp);
}

staticinlineinttcp_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 */
staticinlineinttcp_space(struct sock *sk)
{
returntcp_win_from_space(sk->rcvbuf -atomic_read(&sk->rmem_alloc));
}

staticinlineinttcp_full_space(struct sock *sk)
{
returntcp_win_from_space(sk->rcvbuf);
}

staticinlinevoidtcp_acceptq_removed(struct sock *sk)
{
 sk->ack_backlog--;
}

staticinlinevoidtcp_acceptq_added(struct sock *sk)
{
 sk->ack_backlog++;
}

staticinlineinttcp_acceptq_is_full(struct sock *sk)
{
return sk->ack_backlog > sk->max_ack_backlog;
}

staticinlinevoidtcp_acceptq_queue(struct sock *sk,struct open_request *req,
struct sock *child)
{
struct tcp_opt *tp = &sk->tp_pinfo.af_tcp;

 req->sk = child;
tcp_acceptq_added(sk);

if(!tp->accept_queue_tail) {
 tp->accept_queue = req;
}else{
 tp->accept_queue_tail->dl_next = req;
}
 tp->accept_queue_tail = req;
 req->dl_next = NULL;
}

struct tcp_listen_opt
{
 u8 max_qlen_log;/* log_2 of maximal queued SYNs */
int qlen;
int qlen_young;
int clock_hand;
struct open_request *syn_table[TCP_SYNQ_HSIZE];
};

staticinlinevoid
tcp_synq_removed(struct sock *sk,struct open_request *req)
{
struct tcp_listen_opt *lopt = sk->tp_pinfo.af_tcp.listen_opt;

if(--lopt->qlen ==0)
tcp_delete_keepalive_timer(sk);
if(req->retrans ==0)
 lopt->qlen_young--;
}

staticinlinevoidtcp_synq_added(struct sock *sk)
{
struct tcp_listen_opt *lopt = sk->tp_pinfo.af_tcp.listen_opt;

if(lopt->qlen++ ==0)
tcp_reset_keepalive_timer(sk, TCP_TIMEOUT_INIT);
 lopt->qlen_young++;
}

staticinlineinttcp_synq_len(struct sock *sk)
{
return sk->tp_pinfo.af_tcp.listen_opt->qlen;
}

staticinlineinttcp_synq_young(struct sock *sk)
{
return sk->tp_pinfo.af_tcp.listen_opt->qlen_young;
}

staticinlineinttcp_synq_is_full(struct sock *sk)
{
returntcp_synq_len(sk)>>sk->tp_pinfo.af_tcp.listen_opt->max_qlen_log;
}

staticinlinevoidtcp_synq_unlink(struct tcp_opt *tp,struct open_request *req,
struct open_request **prev)
{
write_lock(&tp->syn_wait_lock);
*prev = req->dl_next;
write_unlock(&tp->syn_wait_lock);
}

staticinlinevoidtcp_synq_drop(struct sock *sk,struct open_request *req,
struct open_request **prev)
{
tcp_synq_unlink(&sk->tp_pinfo.af_tcp, req, prev);
tcp_synq_removed(sk, req);
tcp_openreq_free(req);
}

static __inline__ voidtcp_openreq_init(struct open_request *req,
struct tcp_opt *tp,
struct sk_buff *skb)
{
 req->rcv_wnd =0;/* So that tcp_send_synack() knows! */
 req->rcv_isn =TCP_SKB_CB(skb)->seq;
 req->mss = tp->mss_clamp;
 req->ts_recent = tp->saw_tstamp ? tp->rcv_tsval :0;
 req->tstamp_ok = tp->tstamp_ok;
 req->sack_ok = tp->sack_ok;
 req->snd_wscale = tp->snd_wscale;
 req->wscale_ok = tp->wscale_ok;
 req->acked =0;
 req->ecn_ok =0;
 req->rmt_port = skb->h.th->source;
}

#define TCP_MEM_QUANTUM ((int)PAGE_SIZE)

staticinlinevoidtcp_free_skb(struct sock *sk,struct sk_buff *skb)
{
 sk->tp_pinfo.af_tcp.queue_shrunk =1;
 sk->wmem_queued -= skb->truesize;
 sk->forward_alloc += skb->truesize;
__kfree_skb(skb);
}

staticinlinevoidtcp_charge_skb(struct sock *sk,struct sk_buff *skb)
{
 sk->wmem_queued += skb->truesize;
 sk->forward_alloc -= skb->truesize;
}

externvoid__tcp_mem_reclaim(struct sock *sk);
externinttcp_mem_schedule(struct sock *sk,int size,int kind);

staticinlinevoidtcp_mem_reclaim(struct sock *sk)
{
if(sk->forward_alloc >= TCP_MEM_QUANTUM)
__tcp_mem_reclaim(sk);
}

staticinlinevoidtcp_enter_memory_pressure(void)
{
if(!tcp_memory_pressure) {
NET_INC_STATS(TCPMemoryPressures);
 tcp_memory_pressure =1;
}
}

staticinlinevoidtcp_moderate_sndbuf(struct sock *sk)
{
if(!(sk->userlocks&SOCK_SNDBUF_LOCK)) {
 sk->sndbuf =min(sk->sndbuf, sk->wmem_queued/2);
 sk->sndbuf =max(sk->sndbuf, SOCK_MIN_SNDBUF);
}
}

staticinlinestruct sk_buff *tcp_alloc_skb(struct sock *sk,int size,int gfp)
{
struct sk_buff *skb =alloc_skb(size, gfp);

if(skb) {
if(sk->forward_alloc >= (int)skb->truesize ||
tcp_mem_schedule(sk, skb->truesize,0))
return skb;
__kfree_skb(skb);
}else{
tcp_enter_memory_pressure();
tcp_moderate_sndbuf(sk);
}
return NULL;
}

staticinlinevoidtcp_writequeue_purge(struct sock *sk)
{
struct sk_buff *skb;

while((skb =__skb_dequeue(&sk->write_queue)) != NULL)
tcp_free_skb(sk, skb);
tcp_mem_reclaim(sk);
}

externvoidtcp_rfree(struct sk_buff *skb);

staticinlinevoidtcp_set_owner_r(struct sk_buff *skb,struct sock *sk)
{
 skb->sk = sk;
 skb->destructor = tcp_rfree;
atomic_add(skb->truesize, &sk->rmem_alloc);
 sk->forward_alloc -= skb->truesize;
}

externvoidtcp_listen_wlock(void);

/* - We may sleep inside this lock.
 * - If sleeping is not required (or called from BH),
 * use plain read_(un)lock(&tcp_lhash_lock).
 */

staticinlinevoidtcp_listen_lock(void)
{
/* read_lock synchronizes to candidates to writers */
read_lock(&tcp_lhash_lock);
atomic_inc(&tcp_lhash_users);
read_unlock(&tcp_lhash_lock);
}

staticinlinevoidtcp_listen_unlock(void)
{
if(atomic_dec_and_test(&tcp_lhash_users))
wake_up(&tcp_lhash_wait);
}

staticinlineintkeepalive_intvl_when(struct tcp_opt *tp)
{
return tp->keepalive_intvl ? : sysctl_tcp_keepalive_intvl;
}

staticinlineintkeepalive_time_when(struct tcp_opt *tp)
{
return tp->keepalive_time ? : sysctl_tcp_keepalive_time;
}

staticinlineinttcp_fin_time(struct tcp_opt *tp)
{
int fin_timeout = tp->linger2 ? : sysctl_tcp_fin_timeout;

if(fin_timeout < (tp->rto<<2) - (tp->rto>>1))
 fin_timeout = (tp->rto<<2) - (tp->rto>>1);

return fin_timeout;
}

staticinlineinttcp_paws_check(struct tcp_opt *tp,int rst)
{
if((s32)(tp->rcv_tsval - tp->ts_recent) >=0)
return0;
if(xtime.tv_sec >= tp->ts_recent_stamp + TCP_PAWS_24DAYS)
return0;

/* 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 && xtime.tv_sec >= tp->ts_recent_stamp + TCP_PAWS_MSL)
return0;
return1;
}

#define TCP_CHECK_TIMER(sk) do { } while (0);

#endif/* _TCP_H */