16059Samurai/* 26059Samurai * Definitions for tcp compression routines. 36059Samurai * 4139979Sbrian * Copyright (c) 1989, 1993 5139979Sbrian * The Regents of the University of California. All rights reserved. 66059Samurai * 7139979Sbrian * Redistribution and use in source and binary forms, with or without 8139979Sbrian * modification, are permitted provided that the following conditions 9139979Sbrian * are met: 10139979Sbrian * 1. Redistributions of source code must retain the above copyright 11139979Sbrian * notice, this list of conditions and the following disclaimer. 12139979Sbrian * 2. Redistributions in binary form must reproduce the above copyright 13139979Sbrian * notice, this list of conditions and the following disclaimer in the 14139979Sbrian * documentation and/or other materials provided with the distribution. 15139979Sbrian * 3. Neither the name of the University nor the names of its contributors 16139979Sbrian * may be used to endorse or promote products derived from this software 17139979Sbrian * without specific prior written permission. 188857Srgrimes * 19139979Sbrian * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 20139979Sbrian * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21139979Sbrian * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22139979Sbrian * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 23139979Sbrian * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24139979Sbrian * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 25139979Sbrian * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 26139979Sbrian * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27139979Sbrian * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28139979Sbrian * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29139979Sbrian * SUCH DAMAGE. 308857Srgrimes * 316059Samurai * Van Jacobson (van@helios.ee.lbl.gov), Dec 31, 1989: 326059Samurai * - Initial distribution. 33139979Sbrian * 34139979Sbrian * $FreeBSD$ 356059Samurai */ 366059Samurai 3736285Sbrian#define MIN_VJ_STATES 3 3836285Sbrian#define MAX_VJ_STATES 255 3936285Sbrian#define DEF_VJ_STATES 16 /* must be > 2 and < 256 */ 4036285Sbrian#define MAX_HDR 128 416059Samurai 426059Samurai/* 436059Samurai * Compressed packet format: 446059Samurai * 456059Samurai * The first octet contains the packet type (top 3 bits), TCP 466059Samurai * 'push' bit, and flags that indicate which of the 4 TCP sequence 476059Samurai * numbers have changed (bottom 5 bits). The next octet is a 486059Samurai * conversation number that associates a saved IP/TCP header with 496059Samurai * the compressed packet. The next two octets are the TCP checksum 506059Samurai * from the original datagram. The next 0 to 15 octets are 516059Samurai * sequence number changes, one change per bit set in the header 526059Samurai * (there may be no changes and there are two special cases where 536059Samurai * the receiver implicitly knows what changed -- see below). 548857Srgrimes * 556059Samurai * There are 5 numbers which can change (they are always inserted 566059Samurai * in the following order): TCP urgent pointer, window, 576059Samurai * acknowlegement, sequence number and IP ID. (The urgent pointer 586059Samurai * is different from the others in that its value is sent, not the 596059Samurai * change in value.) Since typical use of SLIP links is biased 606059Samurai * toward small packets (see comments on MTU/MSS below), changes 616059Samurai * use a variable length coding with one octet for numbers in the 626059Samurai * range 1 - 255 and 3 octets (0, MSB, LSB) for numbers in the 636059Samurai * range 256 - 65535 or 0. (If the change in sequence number or 646059Samurai * ack is more than 65535, an uncompressed packet is sent.) 656059Samurai */ 666059Samurai 676059Samurai/* 686059Samurai * Packet types (must not conflict with IP protocol version) 696059Samurai * 706059Samurai * The top nibble of the first octet is the packet type. There are 716059Samurai * three possible types: IP (not proto TCP or tcp with one of the 726059Samurai * control flags set); uncompressed TCP (a normal IP/TCP packet but 736059Samurai * with the 8-bit protocol field replaced by an 8-bit connection id -- 746059Samurai * this type of packet syncs the sender & receiver); and compressed 756059Samurai * TCP (described above). 766059Samurai * 776059Samurai * LSB of 4-bit field is TCP "PUSH" bit (a worthless anachronism) and 786059Samurai * is logically part of the 4-bit "changes" field that follows. Top 796059Samurai * three bits are actual packet type. For backward compatibility 806059Samurai * and in the interest of conserving bits, numbers are chosen so the 816059Samurai * IP protocol version number (4) which normally appears in this nibble 826059Samurai * means "IP packet". 836059Samurai */ 846059Samurai 856059Samurai/* packet types */ 866059Samurai#define TYPE_IP 0x40 876059Samurai#define TYPE_UNCOMPRESSED_TCP 0x70 886059Samurai#define TYPE_COMPRESSED_TCP 0x80 896059Samurai#define TYPE_ERROR 0x00 906059Samurai 916059Samurai/* Bits in first octet of compressed packet */ 9228679Sbrian#define NEW_C 0x40 /* flag bits for what changed in a packet */ 936059Samurai#define NEW_I 0x20 946059Samurai#define NEW_S 0x08 956059Samurai#define NEW_A 0x04 966059Samurai#define NEW_W 0x02 976059Samurai#define NEW_U 0x01 986059Samurai 996059Samurai/* reserved, special-case values of above */ 10028679Sbrian#define SPECIAL_I (NEW_S|NEW_W|NEW_U) /* echoed interactive traffic */ 1016059Samurai#define SPECIAL_D (NEW_S|NEW_A|NEW_W|NEW_U) /* unidirectional data */ 1026059Samurai#define SPECIALS_MASK (NEW_S|NEW_A|NEW_W|NEW_U) 1036059Samurai 1046059Samurai#define TCP_PUSH_BIT 0x10 1056059Samurai 1066059Samurai/* 1076059Samurai * "state" data for each active tcp conversation on the wire. This is 1086059Samurai * basically a copy of the entire IP/TCP header from the last packet 1096059Samurai * we saw from the conversation together with a small identifier 1106059Samurai * the transmit & receive ends of the line use to locate saved header. 1116059Samurai */ 1126059Samuraistruct cstate { 11328679Sbrian struct cstate *cs_next; /* next most recently used cstate (xmit only) */ 11428679Sbrian u_short cs_hlen; /* size of hdr (receive only) */ 11528679Sbrian u_char cs_id; /* connection # associated with this state */ 11628679Sbrian u_char cs_filler; 11759005Sgj union { 11859005Sgj char csu_hdr[MAX_HDR]; 11959005Sgj struct ip csu_ip; /* ip/tcp hdr from most recent packet */ 12059005Sgj } slcs_u; 12159187Sbrian}; 12228679Sbrian 12359005Sgj#define cs_ip slcs_u.csu_ip 12459005Sgj#define cs_hdr slcs_u.csu_hdr 12559005Sgj 1266059Samurai/* 1276059Samurai * all the state data for one serial line (we need one of these 1286059Samurai * per line). 1296059Samurai */ 1306059Samuraistruct slcompress { 13128679Sbrian struct cstate *last_cs; /* most recently used tstate */ 13228679Sbrian u_char last_recv; /* last rcvd conn. id */ 13328679Sbrian u_char last_xmit; /* last sent conn. id */ 13428679Sbrian u_short flags; 13536285Sbrian struct cstate tstate[MAX_VJ_STATES]; /* xmit connection states */ 13636285Sbrian struct cstate rstate[MAX_VJ_STATES]; /* receive connection states */ 1376059Samurai}; 1386059Samurai 13936285Sbrianstruct slstat { 14036285Sbrian int sls_packets; /* outbound packets */ 14136285Sbrian int sls_compressed; /* outbound compressed packets */ 14236285Sbrian int sls_searches; /* searches for connection state */ 14336285Sbrian int sls_misses; /* times couldn't find conn. state */ 14436285Sbrian int sls_uncompressedin; /* inbound uncompressed packets */ 14536285Sbrian int sls_compressedin; /* inbound compressed packets */ 14636285Sbrian int sls_errorin; /* inbound unknown type packets */ 14736285Sbrian int sls_tossed; /* inbound packets tossed because of error */ 14836285Sbrian}; 14936285Sbrian 1506059Samurai/* flag values */ 1516059Samurai#define SLF_TOSS 1 /* tossing rcvd frames because of input err */ 1526059Samurai 15336285Sbrianstruct mbuf; 15436285Sbrianstruct cmdargs; 15536285Sbrian 15630715Sbrianextern void sl_compress_init(struct slcompress *, int); 15736285Sbrianextern u_char sl_compress_tcp(struct mbuf *, struct ip *, struct slcompress *, 15836285Sbrian struct slstat *, int); 15936285Sbrianextern int sl_uncompress_tcp(u_char **, int, u_int, struct slcompress *, 16036960Sbrian struct slstat *, int); 16136285Sbrianextern int sl_Show(struct cmdargs const *); 162