| 1 | /* |
| 2 | * Definitions for tcp compression routines. |
| 3 | * |
| 4 | * Copyright (c) 1989, 1993 |
| 5 | * The Regents of the University of California. All rights reserved. |
| 6 | * |
| 7 | * Redistribution and use in source and binary forms, with or without |
| 8 | * modification, are permitted provided that the following conditions |
| 9 | * are met: |
| 10 | * 1. Redistributions of source code must retain the above copyright |
| 11 | * notice, this list of conditions and the following disclaimer. |
| 12 | * 2. Redistributions in binary form must reproduce the above copyright |
| 13 | * notice, this list of conditions and the following disclaimer in the |
| 14 | * documentation and/or other materials provided with the distribution. |
| 15 | * 3. All advertising materials mentioning features or use of this software |
| 16 | * must display the following acknowledgement: |
| 17 | * This product includes software developed by the University of |
| 18 | * California, Berkeley and its contributors. |
| 19 | * 4. Neither the name of the University nor the names of its contributors |
| 20 | * may be used to endorse or promote products derived from this software |
| 21 | * without specific prior written permission. |
| 22 | * |
| 23 | * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND |
| 24 | * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
| 25 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
| 26 | * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE |
| 27 | * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL |
| 28 | * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS |
| 29 | * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) |
| 30 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
| 31 | * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY |
| 32 | * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
| 33 | * SUCH DAMAGE. |
| 34 | * |
| 35 | * Van Jacobson (van@helios.ee.lbl.gov), Dec 31, 1989: |
| 36 | * - Initial distribution. |
| 37 | * $FreeBSD: src/sys/net/slcompress.h,v 1.14.2.1 2000/05/05 13:37:06 jlemon Exp $ |
| 38 | * $DragonFly: src/sys/net/slcompress.h,v 1.5 2006/05/21 03:43:45 dillon Exp $ |
| 39 | */ |
| 40 | |
| 41 | #ifndef _NET_SLCOMPRESS_H_ |
| 42 | #define _NET_SLCOMPRESS_H_ |
| 43 | |
| 44 | #ifndef _SYS_TYPES_H_ |
| 45 | #include <sys/types.h> |
| 46 | #endif |
| 47 | #ifndef _NETINET_IP_H_ |
| 48 | #include <netinet/ip.h> |
| 49 | #endif |
| 50 | |
| 51 | #define MAX_STATES 16 /* must be > 2 and < 256 */ |
| 52 | #define MAX_HDR 128 |
| 53 | |
| 54 | /* |
| 55 | * Compressed packet format: |
| 56 | * |
| 57 | * The first octet contains the packet type (top 3 bits), TCP |
| 58 | * 'push' bit, and flags that indicate which of the 4 TCP sequence |
| 59 | * numbers have changed (bottom 5 bits). The next octet is a |
| 60 | * conversation number that associates a saved IP/TCP header with |
| 61 | * the compressed packet. The next two octets are the TCP checksum |
| 62 | * from the original datagram. The next 0 to 15 octets are |
| 63 | * sequence number changes, one change per bit set in the header |
| 64 | * (there may be no changes and there are two special cases where |
| 65 | * the receiver implicitly knows what changed -- see below). |
| 66 | * |
| 67 | * There are 5 numbers which can change (they are always inserted |
| 68 | * in the following order): TCP urgent pointer, window, |
| 69 | * acknowledgement, sequence number and IP ID. (The urgent pointer |
| 70 | * is different from the others in that its value is sent, not the |
| 71 | * change in value.) Since typical use of SLIP links is biased |
| 72 | * toward small packets (see comments on MTU/MSS below), changes |
| 73 | * use a variable length coding with one octet for numbers in the |
| 74 | * range 1 - 255 and 3 octets (0, MSB, LSB) for numbers in the |
| 75 | * range 256 - 65535 or 0. (If the change in sequence number or |
| 76 | * ack is more than 65535, an uncompressed packet is sent.) |
| 77 | */ |
| 78 | |
| 79 | /* |
| 80 | * Packet types (must not conflict with IP protocol version) |
| 81 | * |
| 82 | * The top nibble of the first octet is the packet type. There are |
| 83 | * three possible types: IP (not proto TCP or tcp with one of the |
| 84 | * control flags set); uncompressed TCP (a normal IP/TCP packet but |
| 85 | * with the 8-bit protocol field replaced by an 8-bit connection id -- |
| 86 | * this type of packet syncs the sender & receiver); and compressed |
| 87 | * TCP (described above). |
| 88 | * |
| 89 | * LSB of 4-bit field is TCP "PUSH" bit (a worthless anachronism) and |
| 90 | * is logically part of the 4-bit "changes" field that follows. Top |
| 91 | * three bits are actual packet type. For backward compatibility |
| 92 | * and in the interest of conserving bits, numbers are chosen so the |
| 93 | * IP protocol version number (4) which normally appears in this nibble |
| 94 | * means "IP packet". |
| 95 | */ |
| 96 | |
| 97 | /* packet types */ |
| 98 | #define TYPE_IP 0x40 |
| 99 | #define TYPE_UNCOMPRESSED_TCP 0x70 |
| 100 | #define TYPE_COMPRESSED_TCP 0x80 |
| 101 | #define TYPE_ERROR 0x00 |
| 102 | |
| 103 | /* Bits in first octet of compressed packet */ |
| 104 | #define NEW_C 0x40 /* flag bits for what changed in a packet */ |
| 105 | #define NEW_I 0x20 |
| 106 | #define NEW_S 0x08 |
| 107 | #define NEW_A 0x04 |
| 108 | #define NEW_W 0x02 |
| 109 | #define NEW_U 0x01 |
| 110 | |
| 111 | /* reserved, special-case values of above */ |
| 112 | #define SPECIAL_I (NEW_S|NEW_W|NEW_U) /* echoed interactive traffic */ |
| 113 | #define SPECIAL_D (NEW_S|NEW_A|NEW_W|NEW_U) /* unidirectional data */ |
| 114 | #define SPECIALS_MASK (NEW_S|NEW_A|NEW_W|NEW_U) |
| 115 | |
| 116 | #define TCP_PUSH_BIT 0x10 |
| 117 | |
| 118 | |
| 119 | /* |
| 120 | * "state" data for each active tcp conversation on the wire. This is |
| 121 | * basically a copy of the entire IP/TCP header from the last packet |
| 122 | * we saw from the conversation together with a small identifier |
| 123 | * the transmit & receive ends of the line use to locate saved header. |
| 124 | */ |
| 125 | struct cstate { |
| 126 | struct cstate *cs_next; /* next most recently used cstate (xmit only) */ |
| 127 | u_int16_t cs_hlen; /* size of hdr (receive only) */ |
| 128 | u_char cs_id; /* connection # associated with this state */ |
| 129 | u_char cs_filler; |
| 130 | union { |
| 131 | char csu_hdr[MAX_HDR]; |
| 132 | struct ip csu_ip; /* ip/tcp hdr from most recent packet */ |
| 133 | } slcs_u; |
| 134 | }; |
| 135 | #define cs_ip slcs_u.csu_ip |
| 136 | #define cs_hdr slcs_u.csu_hdr |
| 137 | |
| 138 | /* |
| 139 | * all the state data for one serial line (we need one of these |
| 140 | * per line). |
| 141 | */ |
| 142 | struct slcompress { |
| 143 | struct cstate *last_cs; /* most recently used tstate */ |
| 144 | u_char last_recv; /* last rcvd conn. id */ |
| 145 | u_char last_xmit; /* last sent conn. id */ |
| 146 | u_int16_t flags; |
| 147 | #ifndef SL_NO_STATS |
| 148 | int sls_packets; /* outbound packets */ |
| 149 | int sls_compressed; /* outbound compressed packets */ |
| 150 | int sls_searches; /* searches for connection state */ |
| 151 | int sls_misses; /* times couldn't find conn. state */ |
| 152 | int sls_uncompressedin; /* inbound uncompressed packets */ |
| 153 | int sls_compressedin; /* inbound compressed packets */ |
| 154 | int sls_errorin; /* inbound unknown type packets */ |
| 155 | int sls_tossed; /* inbound packets tossed because of error */ |
| 156 | #endif |
| 157 | struct cstate tstate[MAX_STATES]; /* xmit connection states */ |
| 158 | struct cstate rstate[MAX_STATES]; /* receive connection states */ |
| 159 | }; |
| 160 | /* flag values */ |
| 161 | #define SLF_TOSS 1 /* tossing rcvd frames because of input err */ |
| 162 | |
| 163 | struct mbuf; |
| 164 | |
| 165 | void sl_compress_init (struct slcompress *, int); |
| 166 | u_int sl_compress_tcp (struct mbuf *, |
| 167 | struct ip *, struct slcompress *, int); |
| 168 | int sl_uncompress_tcp (u_char **, int, u_int, struct slcompress *); |
| 169 | int sl_uncompress_tcp_core (u_char *, int, int, u_int, |
| 170 | struct slcompress *, u_char **, u_int *); |
| 171 | |
| 172 | #endif /* !_NET_SLCOMPRESS_H_ */ |