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#ifndef _SLHC_H

#define _SLHC_H

/*

 * Definitions for tcp compression routines.

 *

 * $Header: /home/marcus/revision_ctrl_test/oc_cvs/cvs/or1k/uclinux/uClinux-2.0.x/include/net/slhc_vj.h,v 1.1.1.1 2001-09-10 07:44:45 simons Exp $

 *

 * Copyright (c) 1989 Regents of the University of California.

 * All rights reserved.

 *

 * Redistribution and use in source and binary forms are permitted

 * provided that the above copyright notice and this paragraph are

 * duplicated in all such forms and that any documentation,

 * advertising materials, and other materials related to such

 * distribution and use acknowledge that the software was developed

 * by the University of California, Berkeley.  The name of the

 * University may not be used to endorse or promote products derived

 * from this software without specific prior written permission.

 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR

 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED

 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.

 *

 *      Van Jacobson (van@helios.ee.lbl.gov), Dec 31, 1989:

 *      - Initial distribution.

 *

 *

 * modified for KA9Q Internet Software Package by

 * Katie Stevens (dkstevens@ucdavis.edu)

 * University of California, Davis

 * Computing Services

 *      - 01-31-90      initial adaptation

 *

 *      - Feb 1991      Bill_Simpson@um.cc.umich.edu

 *                      variable number of conversation slots

 *                      allow zero or one slots

 *                      separate routines

 *                      status display

 */

/*

 * Compressed packet format:

 *

 * The first octet contains the packet type (top 3 bits), TCP

 * 'push' bit, and flags that indicate which of the 4 TCP sequence

 * numbers have changed (bottom 5 bits).  The next octet is a

 * conversation number that associates a saved IP/TCP header with

 * the compressed packet.  The next two octets are the TCP checksum

 * from the original datagram.  The next 0 to 15 octets are

 * sequence number changes, one change per bit set in the header

 * (there may be no changes and there are two special cases where

 * the receiver implicitly knows what changed -- see below).

 *

 * There are 5 numbers which can change (they are always inserted

 * in the following order): TCP urgent pointer, window,

 * acknowledgment, sequence number and IP ID.  (The urgent pointer

 * is different from the others in that its value is sent, not the

 * change in value.)  Since typical use of SLIP links is biased

 * toward small packets (see comments on MTU/MSS below), changes

 * use a variable length coding with one octet for numbers in the

 * range 1 - 255 and 3 octets (0, MSB, LSB) for numbers in the

 * range 256 - 65535 or 0.  (If the change in sequence number or

 * ack is more than 65535, an uncompressed packet is sent.)

 */

/*

 * Packet types (must not conflict with IP protocol version)

 *

 * The top nibble of the first octet is the packet type.  There are

 * three possible types: IP (not proto TCP or tcp with one of the

 * control flags set); uncompressed TCP (a normal IP/TCP packet but

 * with the 8-bit protocol field replaced by an 8-bit connection id --

 * this type of packet syncs the sender & receiver); and compressed

 * TCP (described above).

 *

 * LSB of 4-bit field is TCP "PUSH" bit (a worthless anachronism) and

 * is logically part of the 4-bit "changes" field that follows.  Top

 * three bits are actual packet type.  For backward compatibility

 * and in the interest of conserving bits, numbers are chosen so the

 * IP protocol version number (4) which normally appears in this nibble

 * means "IP packet".

 */

/* SLIP compression masks for len/vers byte */

#define SL_TYPE_IP 0x40

#define SL_TYPE_UNCOMPRESSED_TCP 0x70

#define SL_TYPE_COMPRESSED_TCP 0x80

#define SL_TYPE_ERROR 0x00

/* Bits in first octet of compressed packet */

#define NEW_C   0x40    /* flag bits for what changed in a packet */

#define NEW_I   0x20

#define NEW_S   0x08

#define NEW_A   0x04

#define NEW_W   0x02

#define NEW_U   0x01

/* reserved, special-case values of above */

#define SPECIAL_I (NEW_S|NEW_W|NEW_U)           /* echoed interactive traffic */

#define SPECIAL_D (NEW_S|NEW_A|NEW_W|NEW_U)     /* unidirectional data */

#define SPECIALS_MASK (NEW_S|NEW_A|NEW_W|NEW_U)

#define TCP_PUSH_BIT 0x10

/*

 * data type and sizes conversion assumptions:

 *

 *      VJ code         KA9Q style      generic

 *      u_char          byte_t          unsigned char    8 bits

 *      u_short         int16           unsigned short  16 bits

 *      u_int           int16           unsigned short  16 bits

 *      u_long          unsigned long   unsigned long   32 bits

 *      int             int32           long            32 bits

 */

typedef unsigned char byte_t;

typedef unsigned long int32;

/*

 * "state" data for each active tcp conversation on the wire.  This is

 * basically a copy of the entire IP/TCP header from the last packet

 * we saw from the conversation together with a small identifier

 * the transmit & receive ends of the line use to locate saved header.

 */

struct cstate {

        byte_t  cs_this;        /* connection id number (xmit) */

        struct cstate *next;    /* next in ring (xmit) */

        struct iphdr cs_ip;     /* ip/tcp hdr from most recent packet */

        struct tcphdr cs_tcp;

        unsigned char cs_ipopt[64];

        unsigned char cs_tcpopt[64];

        int cs_hsize;

};

#define NULLSLSTATE     (struct cstate *)0

/*

 * all the state data for one serial line (we need one of these per line).

 */

struct slcompress {

        struct cstate *tstate;  /* transmit connection states (array)*/

        struct cstate *rstate;  /* receive connection states (array)*/

        byte_t tslot_limit;     /* highest transmit slot id (0-l)*/

        byte_t rslot_limit;     /* highest receive slot id (0-l)*/

        byte_t xmit_oldest;     /* oldest xmit in ring */

        byte_t xmit_current;    /* most recent xmit id */

        byte_t recv_current;    /* most recent rcvd id */

        byte_t flags;

#define SLF_TOSS        0x01    /* tossing rcvd frames until id received */

        int32 sls_o_nontcp;     /* outbound non-TCP packets */

        int32 sls_o_tcp;        /* outbound TCP packets */

        int32 sls_o_uncompressed;       /* outbound uncompressed packets */

        int32 sls_o_compressed; /* outbound compressed packets */

        int32 sls_o_searches;   /* searches for connection state */

        int32 sls_o_misses;     /* times couldn't find conn. state */

        int32 sls_i_uncompressed;       /* inbound uncompressed packets */

        int32 sls_i_compressed; /* inbound compressed packets */

        int32 sls_i_error;      /* inbound error packets */

        int32 sls_i_tossed;     /* inbound packets tossed because of error */

        int32 sls_i_runt;

        int32 sls_i_badcheck;

};

#define NULLSLCOMPR     (struct slcompress *)0

#define __ARGS(x) x

/* In slhc.c: */

struct slcompress *slhc_init __ARGS((int rslots, int tslots));

void slhc_free __ARGS((struct slcompress *comp));

int slhc_compress __ARGS((struct slcompress *comp, unsigned char *icp,

                          int isize, unsigned char *ocp, unsigned char **cpp,

                          int compress_cid));

int slhc_uncompress __ARGS((struct slcompress *comp, unsigned char *icp,

                            int isize));

int slhc_remember __ARGS((struct slcompress *comp, unsigned char *icp,

                          int isize));

int slhc_toss __ARGS((struct slcompress *comp));

void slhc_i_status __ARGS((struct slcompress *comp));

void slhc_o_status __ARGS((struct slcompress *comp));

#endif  /* _SLHC_H */