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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, <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

#include <linux/tcp.h>

#include <net/checksum.h>

/* This is for all connections with a full identity, no wildcards. */

#define TCP_HTABLE_SIZE         256

/* This is for listening sockets, thus all sockets which possess wildcards. */

#define TCP_LHTABLE_SIZE        32      /* Yes, really, this is all you need. */

/* This is for all sockets, to keep track of the local port allocations. */

#define TCP_BHTABLE_SIZE        64

/* tcp_ipv4.c: These need to be shared by v4 and v6 because the lookup

 *             and hashing code needs to work with different AF's yet

 *             the port space is shared.

 */

extern struct sock *tcp_established_hash[TCP_HTABLE_SIZE];

extern struct sock *tcp_listening_hash[TCP_LHTABLE_SIZE];

extern struct sock *tcp_bound_hash[TCP_BHTABLE_SIZE];

/* These are AF independant. */

static __inline__ int tcp_bhashfn(__u16 lport)

{

        return (lport ^ (lport >> 7)) & (TCP_BHTABLE_SIZE-1);

}

/* Find the next port that hashes h that is larger than lport.

 * If you change the hash, change this function to match, or you will

 * break TCP port selection. This function must also NOT wrap around

 * when the next number exceeds the largest possible port (2^16-1).

 */

static __inline__ int tcp_bhashnext(__u16 lport, __u16 h)

{

        __u32 s;        /* don't change this to a smaller type! */

        s = (lport ^ (h ^ tcp_bhashfn(lport)));

        if (s > lport)

                return s;

        s = lport + TCP_BHTABLE_SIZE;

        return (s ^ (h ^ tcp_bhashfn(s)));

}

static __inline__ int tcp_sk_bhashfn(struct sock *sk)

{

        __u16 lport = sk->num;

        return tcp_bhashfn(lport);

}

/* These can have wildcards, don't try too hard.

 * XXX deal with thousands of IP aliases for listening ports later

 */

static __inline__ int tcp_lhashfn(unsigned short num)

{

        return num & (TCP_LHTABLE_SIZE - 1);

}

static __inline__ int tcp_sk_listen_hashfn(struct sock *sk)

{

        return tcp_lhashfn(sk->num);

}

/* This is IPv4 specific. */

static __inline__ int tcp_hashfn(__u32 laddr, __u16 lport,

                                 __u32 faddr, __u16 fport)

{

        return ((laddr ^ lport) ^ (faddr ^ fport)) & (TCP_HTABLE_SIZE - 1);

}

static __inline__ int tcp_sk_hashfn(struct sock *sk)

{

        __u32 laddr = sk->rcv_saddr;

        __u16 lport = sk->num;

        __u32 faddr = sk->daddr;

        __u16 fport = sk->dummy_th.dest;

        return tcp_hashfn(laddr, lport, faddr, fport);

}

/* Only those holding the sockhash lock call these two things here.

 * Note the slightly gross overloading of sk->prev, AF_UNIX is the

 * only other main benefactor of that member of SK, so who cares.

 */

static __inline__ void tcp_sk_bindify(struct sock *sk)

{

        int hashent = tcp_sk_bhashfn(sk);

        struct sock **htable = &tcp_bound_hash[hashent];

        if((sk->bind_next = *htable) != NULL)

                (*htable)->bind_pprev = &sk->bind_next;

        *htable = sk;

        sk->bind_pprev = htable;

}

static __inline__ void tcp_sk_unbindify(struct sock *sk)

{

        if(sk->bind_next)

                sk->bind_next->bind_pprev = sk->bind_pprev;

        *(sk->bind_pprev) = sk->bind_next;

}

/*

 * 40 is maximal IP options size

 * 4  is TCP option size (MSS)

 */

#define MAX_SYN_SIZE    (sizeof(struct iphdr) + 40 + sizeof(struct tcphdr) + 4 + MAX_HEADER + 15)

#define MAX_FIN_SIZE    (sizeof(struct iphdr) + 40 + sizeof(struct tcphdr) + MAX_HEADER + 15)

#define MAX_ACK_SIZE    (sizeof(struct iphdr) + 40 + sizeof(struct tcphdr) + MAX_HEADER + 15)

#define MAX_RESET_SIZE  (sizeof(struct iphdr) + 40 + sizeof(struct tcphdr) + MAX_HEADER + 15)

#define MAX_WINDOW      32767           /* Never offer a window over 32767 without using

                                           window scaling (not yet supported). Some poor

                                           stacks do signed 16bit maths! */

#define MIN_WINDOW      2048

#define MAX_ACK_BACKLOG 2

#define MAX_DUP_ACKS    3

#define MIN_WRITE_SPACE 2048

#define TCP_WINDOW_DIFF 2048

/* urg_data states */

#define URG_VALID       0x0100

#define URG_NOTYET      0x0200

#define URG_READ        0x0400

#define TCP_RETR1       7       /*

                                 * This is how many retries it does before it

                                 * tries to figure out if the gateway is

                                 * down.

                                 */

#define TCP_RETR2       15      /*

                                 * This should take at least

                                 * 90 minutes to time out.

                                 */

#define TCP_TIMEOUT_LEN (15*60*HZ) /* should be about 15 mins           */

#define TCP_TIMEWAIT_LEN (60*HZ) /* how long to wait to successfully 

                                  * close the socket, about 60 seconds  */

#define TCP_FIN_TIMEOUT (3*60*HZ) /* BSD style FIN_WAIT2 deadlock breaker */                              

#define TCP_ACK_TIME    (3*HZ)  /* time to delay before sending an ACK  */

#define TCP_DONE_TIME   (5*HZ/2)/* maximum time to wait before actually

                                 * destroying a socket                  */

#define TCP_WRITE_TIME  (30*HZ) /* initial time to wait for an ACK,

                                 * after last transmit                  */

#define TCP_TIMEOUT_INIT (3*HZ) /* RFC 1122 initial timeout value       */

#define TCP_SYN_RETRIES  5      /* number of times to retry opening a

                                 * connection   (TCP_RETR2-....)        */

#define TCP_PROBEWAIT_LEN (1*HZ)/* time to wait between probes when

                                 * I've got something to write and

                                 * there is no window                   */

#define TCP_NO_CHECK    0        /* turn to one if you want the default

                                 * to be no checksum                    */

/*

 *      TCP option

 */

#define TCPOPT_NOP              1       /* Padding */

#define TCPOPT_EOL              0        /* End of options */

#define TCPOPT_MSS              2       /* Segment size negotiating */

/*

 *      We don't use these yet, but they are for PAWS and big windows

 */

#define TCPOPT_WINDOW           3       /* Window scaling */

#define TCPOPT_TIMESTAMP        8       /* Better RTT estimations/PAWS */

/*

 * The next routines deal with comparing 32 bit unsigned ints

 * and worry about wraparound (automatic with unsigned arithmetic).

 */

extern __inline int before(__u32 seq1, __u32 seq2)

{

        return (__s32)(seq1-seq2) < 0;

}

extern __inline int after(__u32 seq1, __u32 seq2)

{

        return (__s32)(seq2-seq1) < 0;

}

/* is s2<=s1<=s3 ? */

extern __inline int between(__u32 seq1, __u32 seq2, __u32 seq3)

{

        return (after(seq1+1, seq2) && before(seq1, seq3+1));

}

static __inline__ int min(unsigned int a, unsigned int b)

{

        if (a > b)

                a = b;

        return a;

}

static __inline__ int max(unsigned int a, unsigned int b)

{

        if (a < b)

                a = b;

        return a;

}

extern struct proto tcp_prot;

extern struct tcp_mib tcp_statistics;

extern unsigned short           tcp_good_socknum(void);

extern void     tcp_err(int type, int code, unsigned char *header, __u32 daddr,

                        __u32, struct inet_protocol *protocol, int len);

extern void     tcp_shutdown (struct sock *sk, int how);

extern int      tcp_rcv(struct sk_buff *skb, struct device *dev,

                        struct options *opt, __u32 daddr,

                        unsigned short len, __u32 saddr, int redo,

                        struct inet_protocol *protocol);

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

extern void tcp_v4_unhash(struct sock *sk);

extern void tcp_read_wakeup(struct sock *);

extern void tcp_write_xmit(struct sock *);

extern void tcp_time_wait(struct sock *);

extern void tcp_retransmit(struct sock *, int);

extern void tcp_do_retransmit(struct sock *, int);

extern void tcp_send_check(struct tcphdr *th, unsigned long saddr,

                unsigned long daddr, int len, struct sk_buff *skb);

/* tcp_output.c */

extern void tcp_send_probe0(struct sock *);

extern void tcp_send_partial(struct sock *);

extern void tcp_write_wakeup(struct sock *);

extern void tcp_send_fin(struct sock *sk);

extern void tcp_send_synack(struct sock *, struct sock *, struct sk_buff *, int);

extern void tcp_send_skb(struct sock *, struct sk_buff *);

extern void tcp_send_ack(struct sock *sk);

extern void tcp_send_delayed_ack(struct sock *sk, int max_timeout, unsigned long timeout);

extern void tcp_send_reset(unsigned long saddr, unsigned long daddr, struct tcphdr *th,

          struct proto *prot, struct options *opt, struct device *dev, int tos, int ttl);

extern void tcp_enqueue_partial(struct sk_buff *, struct sock *);

extern struct sk_buff * tcp_dequeue_partial(struct sock *);

extern void tcp_shrink_skb(struct sock *,struct sk_buff *,u32);

/* CONFIG_IP_TRANSPARENT_PROXY */

extern int tcp_chkaddr(struct sk_buff *);

/* tcp_timer.c */

#define     tcp_reset_msl_timer(x,y,z)  reset_timer(x,y,z)

extern void tcp_reset_xmit_timer(struct sock *, int, unsigned long);

extern void tcp_delack_timer(unsigned long);

extern void tcp_retransmit_timer(unsigned long);

static __inline__ int tcp_old_window(struct sock * sk)

{

        return sk->window - (sk->acked_seq - sk->lastwin_seq);

}

extern int tcp_new_window(struct sock *);

/*

 * Return true if we should raise the window when we

 * have cleaned up the receive queue. We don't want to

 * do this normally, only if it makes sense to avoid

 * zero window probes..

 *

 * We do this only if we can raise the window noticeably.

 */

static __inline__ int tcp_raise_window(struct sock * sk)

{

        int new = tcp_new_window(sk);

        return new && (new >= 2*tcp_old_window(sk));

}

static __inline__ unsigned short tcp_select_window(struct sock *sk)

{

        int window = tcp_new_window(sk);

        int oldwin = tcp_old_window(sk);

        /* Don't allow a shrinking window */

        if (window > oldwin) {

                sk->window = window;

                sk->lastwin_seq = sk->acked_seq;

                oldwin = window;

        }

        return oldwin;

}

/*

 * List all states of a TCP socket that can be viewed as a "connected"

 * state.  This now includes TCP_SYN_RECV, although I am not yet fully

 * convinced that this is the solution for the 'getpeername(2)'

 * problem. Thanks to Stephen A. Wood <saw@cebaf.gov>  -FvK

 */

extern __inline const int tcp_connected(const int state)

{

  return(state == TCP_ESTABLISHED || state == TCP_CLOSE_WAIT ||

         state == TCP_FIN_WAIT1   || state == TCP_FIN_WAIT2 ||

         state == TCP_SYN_RECV);

}

/*

 * Calculate(/check) TCP checksum

 */

static __inline__ u16 tcp_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);

}

#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__ void tcp_set_state(struct sock *sk, int state)

{

        int oldstate = sk->state;

        sk->state = state;

#ifdef STATE_TRACE

        if(sk->debug)

                printk("TCP sk=%p, State %s -> %s\n",sk, statename[oldstate],statename[state]);

#endif  

        switch (state) {

        case TCP_ESTABLISHED:

                if (oldstate != TCP_ESTABLISHED) {

                        tcp_statistics.TcpCurrEstab++;

                }

                break;

        case TCP_CLOSE:

                /* Preserve the invariant */

                tcp_v4_unhash(sk);

                /* Should be about 2 rtt's */

                reset_timer(sk, TIME_DONE, min(sk->rtt * 2, TCP_DONE_TIME));

                /* fall through */

        default:

                if (oldstate==TCP_ESTABLISHED)

                        tcp_statistics.TcpCurrEstab--;

        }

}

#endif  /* _TCP_H */