/* IBM_PROLOG_BEGIN_TAG */ /* This is an automatically generated prolog. */ /* */ /* bos720 src/bos/kernel/net/slcompress.h 1.3 */ /* */ /* Licensed Materials - Property of IBM */ /* */ /* COPYRIGHT International Business Machines Corp. 1988,1993 */ /* All Rights Reserved */ /* */ /* US Government Users Restricted Rights - Use, duplication or */ /* disclosure restricted by GSA ADP Schedule Contract with IBM Corp. */ /* */ /* IBM_PROLOG_END_TAG */ /* @(#)20 1.3 src/bos/kernel/net/slcompress.h, sysnet, bos720 2/15/94 17:28:11 */ /* * COMPONENT_NAME: SYSNET * * FUNCTIONS: * * ORIGINS: 26,27,85 * * * (C) COPYRIGHT International Business Machines Corp. 1988,1993 * All Rights Reserved * Licensed Materials - Property of IBM * US Government Users Restricted Rights - Use, duplication or * disclosure restricted by GSA ADP Schedule Contract with IBM Corp. */ /* * * (c) Copyright 1991, OPEN SOFTWARE FOUNDATION, INC. * ALL RIGHTS RESERVED * */ /* * OSF/1 1.2 */ /* * Definitions for tcp compression routines. * * Copyright (c) 1989 Regents of the University of California. * All rights reserved. * * Redistribution and use in source and binary forms are permitted provided * that: (1) source distributions retain this entire copyright notice and * comment, and (2) distributions including binaries display the following * acknowledgement: ``This product includes software developed by the * University of California, Berkeley and its contributors'' in the * documentation or other materials provided with the distribution and in * all advertising materials mentioning features or use of this software. * 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 ``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. * * Base: slcompress.h 7.3 90/01/20 * Base: slcompress.h,v 1.10 89/12/31 08:53:02 van Exp * Merged: slcompress.h 7.4 90/06/28 */ #ifndef _H_SLCOMPRESS #define _H_SLCOMPRESS #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_EI (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 */ #endif /* _H_SLCOMPRESS */