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