bsd/net/slcompress.h

   1 /*
   2  * Copyright (c) 2000 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * Copyright (c) 1999-2003 Apple Computer, Inc.  All Rights Reserved.
   7  *
   8  * This file contains Original Code and/or Modifications of Original Code
   9  * as defined in and that are subject to the Apple Public Source License
  10  * Version 2.0 (the 'License'). You may not use this file except in
  11  * compliance with the License. Please obtain a copy of the License at
  12  * http://www.opensource.apple.com/apsl/ and read it before using this
  13  * file.
  14  *
  15  * The Original Code and all software distributed under the License are
  16  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  17  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  18  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  19  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  20  * Please see the License for the specific language governing rights and
  21  * limitations under the License.
  22  *
  23  * @APPLE_LICENSE_HEADER_END@
  24  */
  25 /*
  26  * Definitions for tcp compression routines.
  27  *
  28  * Copyright (c) 1989, 1993
  29  *      The Regents of the University of California.  All rights reserved.
  30  *
  31  * Redistribution and use in source and binary forms, with or without
  32  * modification, are permitted provided that the following conditions
  33  * are met:
  34  * 1. Redistributions of source code must retain the above copyright
  35  *    notice, this list of conditions and the following disclaimer.
  36  * 2. Redistributions in binary form must reproduce the above copyright
  37  *    notice, this list of conditions and the following disclaimer in the
  38  *    documentation and/or other materials provided with the distribution.
  39  * 3. All advertising materials mentioning features or use of this software
  40  *    must display the following acknowledgement:
  41  *      This product includes software developed by the University of
  42  *      California, Berkeley and its contributors.
  43  * 4. Neither the name of the University nor the names of its contributors
  44  *    may be used to endorse or promote products derived from this software
  45  *    without specific prior written permission.
  46  *
  47  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  48  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  49  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  50  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  51  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  52  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  53  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  54  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  55  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  56  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  57  * SUCH DAMAGE.
  58  *
  59  *      Van Jacobson (van@helios.ee.lbl.gov), Dec 31, 1989:
  60  *      - Initial distribution.
  61  * $FreeBSD: src/sys/net/slcompress.h,v 1.14.2.1 2000/05/05 13:37:06 jlemon Exp $
  62  */
  63
  64 #ifndef _NET_SLCOMPRESS_H_
  65 #define _NET_SLCOMPRESS_H_
  66 #include <sys/appleapiopts.h>
  67
  68 #include <netinet/ip.h>
  69
  70 #define MAX_STATES 16           /* must be > 2 and < 256 */
  71 #define MAX_HDR 128
  72
  73 /*
  74  * Compressed packet format:
  75  *
  76  * The first octet contains the packet type (top 3 bits), TCP
  77  * 'push' bit, and flags that indicate which of the 4 TCP sequence
  78  * numbers have changed (bottom 5 bits).  The next octet is a
  79  * conversation number that associates a saved IP/TCP header with
  80  * the compressed packet.  The next two octets are the TCP checksum
  81  * from the original datagram.  The next 0 to 15 octets are
  82  * sequence number changes, one change per bit set in the header
  83  * (there may be no changes and there are two special cases where
  84  * the receiver implicitly knows what changed -- see below).
  85  *
  86  * There are 5 numbers which can change (they are always inserted
  87  * in the following order): TCP urgent pointer, window,
  88  * acknowledgement, sequence number and IP ID.  (The urgent pointer
  89  * is different from the others in that its value is sent, not the
  90  * change in value.)  Since typical use of SLIP links is biased
  91  * toward small packets (see comments on MTU/MSS below), changes
  92  * use a variable length coding with one octet for numbers in the
  93  * range 1 - 255 and 3 octets (0, MSB, LSB) for numbers in the
  94  * range 256 - 65535 or 0.  (If the change in sequence number or
  95  * ack is more than 65535, an uncompressed packet is sent.)
  96  */
  97
  98 /*
  99  * Packet types (must not conflict with IP protocol version)
 100  *
 101  * The top nibble of the first octet is the packet type.  There are
 102  * three possible types: IP (not proto TCP or tcp with one of the
 103  * control flags set); uncompressed TCP (a normal IP/TCP packet but
 104  * with the 8-bit protocol field replaced by an 8-bit connection id --
 105  * this type of packet syncs the sender & receiver); and compressed
 106  * TCP (described above).
 107  *
 108  * LSB of 4-bit field is TCP "PUSH" bit (a worthless anachronism) and
 109  * is logically part of the 4-bit "changes" field that follows.  Top
 110  * three bits are actual packet type.  For backward compatibility
 111  * and in the interest of conserving bits, numbers are chosen so the
 112  * IP protocol version number (4) which normally appears in this nibble
 113  * means "IP packet".
 114  */
 115
 116 /* packet types */
 117 #define TYPE_IP 0x40
 118 #define TYPE_UNCOMPRESSED_TCP 0x70
 119 #define TYPE_COMPRESSED_TCP 0x80
 120 #define TYPE_ERROR 0x00
 121
 122 /* Bits in first octet of compressed packet */
 123 #define NEW_C   0x40    /* flag bits for what changed in a packet */
 124 #define NEW_I   0x20
 125 #define NEW_S   0x08
 126 #define NEW_A   0x04
 127 #define NEW_W   0x02
 128 #define NEW_U   0x01
 129
 130 /* reserved, special-case values of above */
 131 #define SPECIAL_I (NEW_S|NEW_W|NEW_U)           /* echoed interactive traffic */
 132 #define SPECIAL_D (NEW_S|NEW_A|NEW_W|NEW_U)     /* unidirectional data */
 133 #define SPECIALS_MASK (NEW_S|NEW_A|NEW_W|NEW_U)
 134
 135 #define TCP_PUSH_BIT 0x10
 136
 137
 138 /*
 139  * "state" data for each active tcp conversation on the wire.  This is
 140  * basically a copy of the entire IP/TCP header from the last packet
 141  * we saw from the conversation together with a small identifier
 142  * the transmit & receive ends of the line use to locate saved header.
 143  */
 144 struct cstate {
 145         struct cstate *cs_next; /* next most recently used cstate (xmit only) */
 146         u_int16_t cs_hlen;      /* size of hdr (receive only) */
 147         u_char cs_id;           /* connection # associated with this state */
 148         u_char cs_filler;
 149         union {
 150                 char csu_hdr[MAX_HDR];
 151                 struct ip csu_ip;       /* ip/tcp hdr from most recent packet */
 152         } slcs_u;
 153 };
 154 #define cs_ip slcs_u.csu_ip
 155 #define cs_hdr slcs_u.csu_hdr
 156
 157 /*
 158  * all the state data for one serial line (we need one of these
 159  * per line).
 160  */
 161 struct slcompress {
 162         struct cstate *last_cs; /* most recently used tstate */
 163         u_char last_recv;       /* last rcvd conn. id */
 164         u_char last_xmit;       /* last sent conn. id */
 165         u_int16_t flags;
 166 #ifndef SL_NO_STATS
 167         int sls_packets;        /* outbound packets */
 168         int sls_compressed;     /* outbound compressed packets */
 169         int sls_searches;       /* searches for connection state */
 170         int sls_misses;         /* times couldn't find conn. state */
 171         int sls_uncompressedin; /* inbound uncompressed packets */
 172         int sls_compressedin;   /* inbound compressed packets */
 173         int sls_errorin;        /* inbound unknown type packets */
 174         int sls_tossed;         /* inbound packets tossed because of error */
 175 #endif
 176         struct cstate tstate[MAX_STATES];       /* xmit connection states */
 177         struct cstate rstate[MAX_STATES];       /* receive connection states */
 178 };
 179 /* flag values */
 180 #define SLF_TOSS 1              /* tossing rcvd frames because of input err */
 181
 182 #if !defined(KERNEL) || defined(__APPLE_API_PRIVATE)
 183 void     sl_compress_init __P((struct slcompress *, int));
 184 u_int    sl_compress_tcp __P((struct mbuf *,
 185             struct ip *, struct slcompress *, int));
 186 int      sl_uncompress_tcp __P((u_char **, int, u_int, struct slcompress *));
 187 int      sl_uncompress_tcp_core __P((u_char *, int, int, u_int,
 188             struct slcompress *, u_char **, u_int *));
 189
 190 #endif /* !KERNEL || __APPLE_API_PRIVATE */
 191 #endif /* !_NET_SLCOMPRESS_H_ */