Annotation of sys/net/slcompress.h, Revision 1.1
1.1 ! nbrk 1: /* $OpenBSD: slcompress.h,v 1.7 2003/06/02 23:28:12 millert Exp $ */
! 2: /* $NetBSD: slcompress.h,v 1.11 1997/05/17 21:12:11 christos Exp $ */
! 3:
! 4: /*
! 5: * Copyright (c) 1989, 1993
! 6: * The Regents of the University of California. All rights reserved.
! 7: *
! 8: * Redistribution and use in source and binary forms, with or without
! 9: * modification, are permitted provided that the following conditions
! 10: * are met:
! 11: * 1. Redistributions of source code must retain the above copyright
! 12: * notice, this list of conditions and the following disclaimer.
! 13: * 2. Redistributions in binary form must reproduce the above copyright
! 14: * notice, this list of conditions and the following disclaimer in the
! 15: * documentation and/or other materials provided with the distribution.
! 16: * 3. Neither the name of the University nor the names of its contributors
! 17: * may be used to endorse or promote products derived from this software
! 18: * without specific prior written permission.
! 19: *
! 20: * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
! 21: * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
! 22: * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
! 23: * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
! 24: * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
! 25: * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
! 26: * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
! 27: * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
! 28: * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
! 29: * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
! 30: * SUCH DAMAGE.
! 31: *
! 32: * @(#)slcompress.h 8.1 (Berkeley) 6/10/93
! 33: */
! 34:
! 35: /*
! 36: * Definitions for tcp compression routines.
! 37: *
! 38: * Van Jacobson (van@helios.ee.lbl.gov), Dec 31, 1989:
! 39: * - Initial distribution.
! 40: */
! 41:
! 42: #ifndef _NET_SLCOMPRESS_H_
! 43: #define _NET_SLCOMPRESS_H_
! 44:
! 45: #define MAX_STATES 16 /* must be > 2 and < 256 */
! 46: #define MAX_HDR MLEN /* XXX 4bsd-ism: should really be 128 */
! 47:
! 48: /*
! 49: * Compressed packet format:
! 50: *
! 51: * The first octet contains the packet type (top 3 bits), TCP
! 52: * 'push' bit, and flags that indicate which of the 4 TCP sequence
! 53: * numbers have changed (bottom 5 bits). The next octet is a
! 54: * conversation number that associates a saved IP/TCP header with
! 55: * the compressed packet. The next two octets are the TCP checksum
! 56: * from the original datagram. The next 0 to 15 octets are
! 57: * sequence number changes, one change per bit set in the header
! 58: * (there may be no changes and there are two special cases where
! 59: * the receiver implicitly knows what changed -- see below).
! 60: *
! 61: * There are 5 numbers which can change (they are always inserted
! 62: * in the following order): TCP urgent pointer, window,
! 63: * acknowledgement, sequence number and IP ID. (The urgent pointer
! 64: * is different from the others in that its value is sent, not the
! 65: * change in value.) Since typical use of SLIP links is biased
! 66: * toward small packets (see comments on MTU/MSS below), changes
! 67: * use a variable length coding with one octet for numbers in the
! 68: * range 1 - 255 and 3 octets (0, MSB, LSB) for numbers in the
! 69: * range 256 - 65535 or 0. (If the change in sequence number or
! 70: * ack is more than 65535, an uncompressed packet is sent.)
! 71: */
! 72:
! 73: /*
! 74: * Packet types (must not conflict with IP protocol version)
! 75: *
! 76: * The top nibble of the first octet is the packet type. There are
! 77: * three possible types: IP (not proto TCP or tcp with one of the
! 78: * control flags set); uncompressed TCP (a normal IP/TCP packet but
! 79: * with the 8-bit protocol field replaced by an 8-bit connection id --
! 80: * this type of packet syncs the sender & receiver); and compressed
! 81: * TCP (described above).
! 82: *
! 83: * LSB of 4-bit field is TCP "PUSH" bit (a worthless anachronism) and
! 84: * is logically part of the 4-bit "changes" field that follows. Top
! 85: * three bits are actual packet type. For backward compatibility
! 86: * and in the interest of conserving bits, numbers are chosen so the
! 87: * IP protocol version number (4) which normally appears in this nibble
! 88: * means "IP packet".
! 89: */
! 90:
! 91: /* packet types */
! 92: #define TYPE_IP 0x40
! 93: #define TYPE_UNCOMPRESSED_TCP 0x70
! 94: #define TYPE_COMPRESSED_TCP 0x80
! 95: #define TYPE_ERROR 0x00
! 96:
! 97: /* Bits in first octet of compressed packet */
! 98: #define NEW_C 0x40 /* flag bits for what changed in a packet */
! 99: #define NEW_I 0x20
! 100: #define NEW_S 0x08
! 101: #define NEW_A 0x04
! 102: #define NEW_W 0x02
! 103: #define NEW_U 0x01
! 104:
! 105: /* reserved, special-case values of above */
! 106: #define SPECIAL_I (NEW_S|NEW_W|NEW_U) /* echoed interactive traffic */
! 107: #define SPECIAL_D (NEW_S|NEW_A|NEW_W|NEW_U) /* unidirectional data */
! 108: #define SPECIALS_MASK (NEW_S|NEW_A|NEW_W|NEW_U)
! 109:
! 110: #define TCP_PUSH_BIT 0x10
! 111:
! 112:
! 113: /*
! 114: * "state" data for each active tcp conversation on the wire. This is
! 115: * basically a copy of the entire IP/TCP header from the last packet
! 116: * we saw from the conversation together with a small identifier
! 117: * the transmit & receive ends of the line use to locate saved header.
! 118: */
! 119: struct cstate {
! 120: struct cstate *cs_next; /* next most recently used cstate (xmit only) */
! 121: u_int16_t cs_hlen; /* size of hdr (receive only) */
! 122: u_char cs_id; /* connection # associated with this state */
! 123: u_char cs_filler;
! 124: union {
! 125: char csu_hdr[MAX_HDR];
! 126: struct ip csu_ip; /* ip/tcp hdr from most recent packet */
! 127: } slcs_u;
! 128: };
! 129: #define cs_ip slcs_u.csu_ip
! 130: #define cs_hdr slcs_u.csu_hdr
! 131:
! 132: /*
! 133: * all the state data for one serial line (we need one of these
! 134: * per line).
! 135: */
! 136: struct slcompress {
! 137: struct cstate *last_cs; /* most recently used tstate */
! 138: u_char last_recv; /* last rcvd conn. id */
! 139: u_char last_xmit; /* last sent conn. id */
! 140: u_int16_t flags;
! 141: #ifndef SL_NO_STATS
! 142: int sls_packets; /* outbound packets */
! 143: int sls_compressed; /* outbound compressed packets */
! 144: int sls_searches; /* searches for connection state */
! 145: int sls_misses; /* times couldn't find conn. state */
! 146: int sls_uncompressedin; /* inbound uncompressed packets */
! 147: int sls_compressedin; /* inbound compressed packets */
! 148: int sls_errorin; /* inbound unknown type packets */
! 149: int sls_tossed; /* inbound packets tossed because of error */
! 150: #endif
! 151: struct cstate tstate[MAX_STATES]; /* xmit connection states */
! 152: struct cstate rstate[MAX_STATES]; /* receive connection states */
! 153: };
! 154: /* flag values */
! 155: #define SLF_TOSS 1 /* tossing rcvd frames because of input err */
! 156:
! 157: void sl_compress_init(struct slcompress *);
! 158: void sl_compress_setup(struct slcompress *, int);
! 159: u_int sl_compress_tcp(struct mbuf *,
! 160: struct ip *, struct slcompress *, int);
! 161: int sl_uncompress_tcp(u_char **, int, u_int, struct slcompress *);
! 162: int sl_uncompress_tcp_core(u_char *, int, int, u_int,
! 163: struct slcompress *, u_char **, u_int *);
! 164:
! 165: #endif /* _NET_SLCOMPRESS_H_ */
CVSweb
![[BACK]](/icons/back.gif){kind=icon}
Return to slcompress.h CVS log ![[TXT]](/icons/text.gif){kind=icon}
![[DIR]](/icons/dir.gif){kind=icon}
Up to [local] / sys / net