QRZ! Ham Radio 5/QRZ Ham Radio Callsign Database - Volume 5.iso/files/tcpip/amiga/asrc29p.lha/slcompre.h

C/C++ Source or Header | 1993-12-29 | 7.2 KB | 210 lines

/*
 * Definitions for tcp compression routines.
 *
 * $Header: slcompress.h,v 1.10 89/12/31 08:53:02 van 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 MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 *
 *    Van Jacobson ([e-mail]), Dec 31, 1989:
 *    - Initial distribution.
 */
/*
 * modified for KA9Q Internet Software Package by
 * Katie Stevens ([e-mail])
 * University of California, Davis
 * Computing Services
 *    - 01-31-90    initial adaptation
 */
#include "global.h"

#ifndef SL_TYPE_IP

#define MLEN 128
#define MAX_STATES 16        /* must be > 2 and < 256 */
#define MAX_HDR MLEN        /* XXX 4bsd-ism: should really be 128 */

/*
 * 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,
 * acknowlegement, 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        unsigned char    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
 */

/*
 * define header structures to allow scan of IP and TCP
 * headers of packets ready for transmission
 */
struct iphdr {
    unsigned char ipvers_hlen;
    unsigned char ip_tos;
    int16 ip_totlen;
    int16 ip_id;
    int16 ip_fragoff;
    unsigned char ip_ttl;
    unsigned char ip_protocol;
    int16 ip_csum;
    unsigned long ip_source;
    unsigned long ip_dest;
};
struct tcphdr {
    int16 th_sport;
    int16 th_dport;
    unsigned long th_seq;
    unsigned long th_ack;
    unsigned char th_off;
    unsigned char th_flags;
#define    TH_FIN    0x01
#define    TH_SYN    0x02
#define    TH_RST    0x04
#define    TH_PUSH    0x08
#define    TH_ACK    0x10
#define    TH_URG    0x20
    int16 th_win;
    int16 th_csum;
    int16 th_urgpt;
};


/*
 * "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 {
    struct cstate *cs_next;    /* next most recently used cstate (xmit only) */
    int16 cs_hlen;        /* size of hdr (receive only) */
    unsigned char cs_id;    /* connection # associated with this state */
    unsigned char cs_filler;
    union {
        char csu_hdr[MAX_HDR];
        struct iphdr csu_ip;    /* ip/tcp hdr from most recent packet */
    } slcs_u;
};
#define cs_ip slcs_u.csu_ip
#define cs_hdr slcs_u.csu_hdr

/*
 * all the state data for one serial line (we need one of these
 * per line).
 */
struct slcompress {
    struct cstate *last_cs;    /* most recently used tstate */
    unsigned char last_recv;    /* last rcvd conn. id */
    unsigned char last_xmit;    /* last sent conn. id */
    int16 flags;
#ifndef SL_NO_STATS
    int32 sls_nontcp;    /* outbound non-TCP packets */
    int32 sls_asistcp;    /* outbound TCP packets */
    int32 sls_compressed;    /* outbound compressed packets */
    int32 sls_uncompressed;    /* outbound uncompressed packets */
    int32 sls_searches;    /* searches for connection state */
    int32 sls_misses;    /* times couldn't find conn. state */
    int32 sls_nontcpin;    /* inbound non-TCP packets */
    int32 sls_tcpin;    /* inbound TCP packets */
    int32 sls_uncompressedin;    /* inbound uncompressed packets */
    int32 sls_compressedin;    /* inbound compressed packets */
    int32 sls_errorin;    /* inbound unknown type packets */
    int32 sls_tossed;    /* inbound packets tossed because of error */
#endif
    struct cstate tstate[MAX_STATES];    /* xmit connection states */
    struct cstate rstate[MAX_STATES];    /* receive connection states */
};
/* flag values */
#define SLF_TOSS 1        /* tossing rcvd frames because of input err */
/* Null pointer */
#define NULLSLCOMPR    (struct slcompress *)0

extern struct slcompress *Slcomp;

/* In slcompress.c: */
void sl_compress_init __ARGS((struct slcompress *comp));
unsigned char sl_compress_tcp __ARGS((struct mbuf **bpp,
    register struct iphdr *iph, struct slcompress *comp,
    int compress_cid));
int sl_uncompress_tcp __ARGS((struct mbuf **bufp, int len,
    int16 type, struct slcompress *comp));

#endif