1316958Sdchagin/* 259243Sobrien * Definitions for tcp compression routines. 359243Sobrien * 459243Sobrien * Copyright (c) 1989, 1993 559243Sobrien * The Regents of the University of California. All rights reserved. 659243Sobrien * 759243Sobrien * Redistribution and use in source and binary forms, with or without 859243Sobrien * modification, are permitted provided that the following conditions 959243Sobrien * are met: 1059243Sobrien * 1. Redistributions of source code must retain the above copyright 1159243Sobrien * notice, this list of conditions and the following disclaimer. 1259243Sobrien * 2. Redistributions in binary form must reproduce the above copyright 1359243Sobrien * notice, this list of conditions and the following disclaimer in the 1459243Sobrien * documentation and/or other materials provided with the distribution. 1559243Sobrien * 3. Neither the name of the University nor the names of its contributors 1659243Sobrien * may be used to endorse or promote products derived from this software 17100616Smp * without specific prior written permission. 1859243Sobrien * 1959243Sobrien * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 2059243Sobrien * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 2159243Sobrien * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 2259243Sobrien * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 2359243Sobrien * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 2459243Sobrien * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 2559243Sobrien * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 2659243Sobrien * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 2759243Sobrien * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 2859243Sobrien * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 2959243Sobrien * SUCH DAMAGE. 3059243Sobrien * 3159243Sobrien * Van Jacobson (van@helios.ee.lbl.gov), Dec 31, 1989: 3259243Sobrien * - Initial distribution. 3359243Sobrien * 3459243Sobrien * $FreeBSD$ 35316958Sdchagin */ 3659243Sobrien 3759243Sobrien#define MIN_VJ_STATES 3 3859243Sobrien#define MAX_VJ_STATES 255 3969408Sache#define DEF_VJ_STATES 16 /* must be > 2 and < 256 */ 4059243Sobrien#define MAX_HDR 128 4169408Sache 4259243Sobrien/* 4359243Sobrien * Compressed packet format: 4459243Sobrien * 4559243Sobrien * The first octet contains the packet type (top 3 bits), TCP 4659243Sobrien * 'push' bit, and flags that indicate which of the 4 TCP sequence 4759243Sobrien * numbers have changed (bottom 5 bits). The next octet is a 4859243Sobrien * conversation number that associates a saved IP/TCP header with 4959243Sobrien * the compressed packet. The next two octets are the TCP checksum 5059243Sobrien * from the original datagram. The next 0 to 15 octets are 5159243Sobrien * sequence number changes, one change per bit set in the header 5259243Sobrien * (there may be no changes and there are two special cases where 5359243Sobrien * the receiver implicitly knows what changed -- see below). 5459243Sobrien * 5559243Sobrien * There are 5 numbers which can change (they are always inserted 5659243Sobrien * in the following order): TCP urgent pointer, window, 5759243Sobrien * acknowlegement, sequence number and IP ID. (The urgent pointer 5859243Sobrien * is different from the others in that its value is sent, not the 5959243Sobrien * change in value.) Since typical use of SLIP links is biased 6059243Sobrien * toward small packets (see comments on MTU/MSS below), changes 6159243Sobrien * use a variable length coding with one octet for numbers in the 6259243Sobrien * range 1 - 255 and 3 octets (0, MSB, LSB) for numbers in the 6359243Sobrien * range 256 - 65535 or 0. (If the change in sequence number or 6459243Sobrien * ack is more than 65535, an uncompressed packet is sent.) 6559243Sobrien */ 6659243Sobrien 6759243Sobrien/* 6859243Sobrien * Packet types (must not conflict with IP protocol version) 6959243Sobrien * 7059243Sobrien * The top nibble of the first octet is the packet type. There are 7159243Sobrien * three possible types: IP (not proto TCP or tcp with one of the 7259243Sobrien * control flags set); uncompressed TCP (a normal IP/TCP packet but 7359243Sobrien * with the 8-bit protocol field replaced by an 8-bit connection id -- 7459243Sobrien * this type of packet syncs the sender & receiver); and compressed 7559243Sobrien * TCP (described above). 7659243Sobrien * 7759243Sobrien * LSB of 4-bit field is TCP "PUSH" bit (a worthless anachronism) and 7859243Sobrien * is logically part of the 4-bit "changes" field that follows. Top 7959243Sobrien * three bits are actual packet type. For backward compatibility 80231990Smp * and in the interest of conserving bits, numbers are chosen so the 8159243Sobrien * IP protocol version number (4) which normally appears in this nibble 8259243Sobrien * means "IP packet". 8359243Sobrien */ 8459243Sobrien 8559243Sobrien/* packet types */ 8659243Sobrien#define TYPE_IP 0x40 8759243Sobrien#define TYPE_UNCOMPRESSED_TCP 0x70 8859243Sobrien#define TYPE_COMPRESSED_TCP 0x80 8959243Sobrien#define TYPE_ERROR 0x00 9059243Sobrien 9159243Sobrien/* Bits in first octet of compressed packet */ 9259243Sobrien#define NEW_C 0x40 /* flag bits for what changed in a packet */ 9359243Sobrien#define NEW_I 0x20 9459243Sobrien#define NEW_S 0x08 9559243Sobrien#define NEW_A 0x04 96145479Smp#define NEW_W 0x02 9759243Sobrien#define NEW_U 0x01 98145479Smp 9959243Sobrien/* reserved, special-case values of above */ 10059243Sobrien#define SPECIAL_I (NEW_S|NEW_W|NEW_U) /* echoed interactive traffic */ 10159243Sobrien#define SPECIAL_D (NEW_S|NEW_A|NEW_W|NEW_U) /* unidirectional data */ 10259243Sobrien#define SPECIALS_MASK (NEW_S|NEW_A|NEW_W|NEW_U) 10359243Sobrien 10459243Sobrien#define TCP_PUSH_BIT 0x10 10559243Sobrien 10659243Sobrien/* 10759243Sobrien * "state" data for each active tcp conversation on the wire. This is 10859243Sobrien * basically a copy of the entire IP/TCP header from the last packet 10959243Sobrien * we saw from the conversation together with a small identifier 11059243Sobrien * the transmit & receive ends of the line use to locate saved header. 11159243Sobrien */ 11259243Sobrienstruct cstate { 11359243Sobrien struct cstate *cs_next; /* next most recently used cstate (xmit only) */ 11459243Sobrien u_short cs_hlen; /* size of hdr (receive only) */ 11559243Sobrien u_char cs_id; /* connection # associated with this state */ 11659243Sobrien u_char cs_filler; 11759243Sobrien union { 11859243Sobrien char csu_hdr[MAX_HDR]; 11959243Sobrien struct ip csu_ip; /* ip/tcp hdr from most recent packet */ 12059243Sobrien } slcs_u; 12159243Sobrien}; 12259243Sobrien 12359243Sobrien#define cs_ip slcs_u.csu_ip 12459243Sobrien#define cs_hdr slcs_u.csu_hdr 12559243Sobrien 12659243Sobrien/* 12759243Sobrien * all the state data for one serial line (we need one of these 12859243Sobrien * per line). 12959243Sobrien */ 13059243Sobrienstruct slcompress { 13159243Sobrien struct cstate *last_cs; /* most recently used tstate */ 13259243Sobrien u_char last_recv; /* last rcvd conn. id */ 13359243Sobrien u_char last_xmit; /* last sent conn. id */ 13459243Sobrien u_short flags; 13559243Sobrien struct cstate tstate[MAX_VJ_STATES]; /* xmit connection states */ 13659243Sobrien struct cstate rstate[MAX_VJ_STATES]; /* receive connection states */ 13759243Sobrien}; 13859243Sobrien 13959243Sobrienstruct slstat { 14059243Sobrien int sls_packets; /* outbound packets */ 14159243Sobrien int sls_compressed; /* outbound compressed packets */ 14259243Sobrien int sls_searches; /* searches for connection state */ 14359243Sobrien int sls_misses; /* times couldn't find conn. state */ 144231990Smp int sls_uncompressedin; /* inbound uncompressed packets */ 145167465Smp int sls_compressedin; /* inbound compressed packets */ 146167465Smp int sls_errorin; /* inbound unknown type packets */ 147167465Smp int sls_tossed; /* inbound packets tossed because of error */ 14859243Sobrien}; 14959243Sobrien 150167465Smp/* flag values */ 15159243Sobrien#define SLF_TOSS 1 /* tossing rcvd frames because of input err */ 152231990Smp 153100616Smpstruct mbuf; 154231990Smpstruct cmdargs; 155100616Smp 15659243Sobrienextern void sl_compress_init(struct slcompress *, int); 15759243Sobrienextern u_char sl_compress_tcp(struct mbuf *, struct ip *, struct slcompress *, 15859243Sobrien struct slstat *, int); 15959243Sobrienextern int sl_uncompress_tcp(u_char **, int, u_int, struct slcompress *, 16059243Sobrien struct slstat *, int); 16159243Sobrienextern int sl_Show(struct cmdargs const *); 16259243Sobrien