162 lines
6.6 KiB
C
162 lines
6.6 KiB
C
/* slcompress.h 8.1 93/06/10 */
|
|
/*
|
|
* Definitions for tcp compression routines.
|
|
*
|
|
* Copyright (c) 1989, 1993
|
|
* The Regents of the University of California. All rights reserved.
|
|
*
|
|
* Redistribution and use in source and binary forms, with or without
|
|
* modification, are permitted provided that the following conditions
|
|
* are met:
|
|
* 1. Redistributions of source code must retain the above copyright
|
|
* notice, this list of conditions and the following disclaimer.
|
|
* 2. Redistributions in binary form must reproduce the above copyright
|
|
* notice, this list of conditions and the following disclaimer in the
|
|
* documentation and/or other materials provided with the distribution.
|
|
* 3. All advertising materials mentioning features or use of this software
|
|
* must display the following acknowledgement:
|
|
* This product includes software developed by the University of
|
|
* California, Berkeley and its contributors.
|
|
* 4. Neither the name of the University nor the names of its contributors
|
|
* may be used to endorse or promote products derived from this software
|
|
* without specific prior written permission.
|
|
*
|
|
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
|
|
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
|
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
|
|
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
|
|
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
|
|
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
|
|
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
|
|
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
|
|
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
|
|
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
|
|
* SUCH DAMAGE.
|
|
*
|
|
* Van Jacobson (van@helios.ee.lbl.gov), Dec 31, 1989:
|
|
* - Initial distribution.
|
|
* $Id: slcompress.h,v 1.4 1994/08/21 19:06:48 paul Exp $
|
|
*/
|
|
|
|
#ifndef _NET_SLCOMPRESS_H_
|
|
#define _NET_SLCOMPRESS_H_
|
|
|
|
#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".
|
|
*/
|
|
|
|
/* packet types */
|
|
#define TYPE_IP 0x40
|
|
#define TYPE_UNCOMPRESSED_TCP 0x70
|
|
#define TYPE_COMPRESSED_TCP 0x80
|
|
#define 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
|
|
|
|
|
|
/*
|
|
* "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) */
|
|
u_short cs_hlen; /* size of hdr (receive only) */
|
|
u_char cs_id; /* connection # associated with this state */
|
|
u_char cs_filler;
|
|
union {
|
|
char csu_hdr[MAX_HDR];
|
|
struct ip 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 */
|
|
u_char last_recv; /* last rcvd conn. id */
|
|
u_char last_xmit; /* last sent conn. id */
|
|
u_short flags;
|
|
#ifndef SL_NO_STATS
|
|
int sls_packets; /* outbound packets */
|
|
int sls_compressed; /* outbound compressed packets */
|
|
int sls_searches; /* searches for connection state */
|
|
int sls_misses; /* times couldn't find conn. state */
|
|
int sls_uncompressedin; /* inbound uncompressed packets */
|
|
int sls_compressedin; /* inbound compressed packets */
|
|
int sls_errorin; /* inbound unknown type packets */
|
|
int 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 */
|
|
|
|
void sl_compress_init __P((struct slcompress *));
|
|
u_int sl_compress_tcp __P((struct mbuf *,
|
|
struct ip *, struct slcompress *, int));
|
|
int sl_uncompress_tcp __P((u_char **, int, u_int, struct slcompress *));
|
|
|
|
#endif /* !_NET_SLCOMPRESS_H_ */
|