147 lines
5.7 KiB
C
147 lines
5.7 KiB
C
#define SL_NO_STATS
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#ifndef _COMPRESS
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#define _COMPRESS
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#include "kernel.h"
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#include "streams.h"
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#include "f_ip.h"
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#include "vanj.h"
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#include "van_j.h"
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/*
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* Definitions for tcp compression routines.
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*
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* $Header: /usr/src/cvs/kernel/isdn/van_j/compress.h,v 1.2 1996/09/16 01:03:31 smurf Exp $
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*
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* Copyright (c) 1989 Regents of the University of California. All rights
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* reserved.
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*
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* Redistribution and use in source and binary forms are permitted provided that
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* the above copyright notice and this paragraph are duplicated in all such
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* forms and that any documentation, advertising materials, and other materials
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* related to such distribution and use acknowledge that the software was
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* developed by the University of California, Berkeley. The name of the
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* University may not be used to endorse or promote products derived from this
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* software without specific prior written permission. THIS SOFTWARE IS
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* PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING,
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* WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF MERCHANTIBILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE.
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*
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* Van Jacobson (van@helios.ee.lbl.gov), Dec 31, 1989: - Initial distribution.
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*/
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#define MAX_STATES 16 /* must be > 2 and < 256 */
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#define MAX_HDR 128
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/*
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* Compressed packet format:
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*
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* The first octet contains the packet type (top 3 bits), TCP 'push' bit, and
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* flags that indicate which of the 4 TCP sequence numbers have changed (bottom
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* 5 bits). The next octet is a conversation number that associates a saved
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* IP/TCP header with the compressed packet. The next two octets are the TCP
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* checksum from the original datagram. The next 0 to 15 octets are sequence
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* number changes, one change per bit set in the header (there may be no
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* changes and there are two special cases where the receiver implicitly knows
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* what changed -- see below).
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*
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* There are 5 numbers which can change (they are always inserted in the following
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* order): TCP urgent pointer, window, acknowlegement, sequence number and IP
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* ID. (The urgent pointer is different from the others in that its value is
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* sent, not the change in value.) Since typical use of SLIP links is biased
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* toward small packets (see comments on MTU/MSS below), changes use a variable
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* length coding with one octet for numbers in the range 1 - 255 and 3 octets
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* (0, MSB, LSB) for numbers in the range 256 - 65535 or 0. (If the change in
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* sequence number or ack is more than 65535, an uncompressed packet is sent.)
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*/
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/*
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* Packet types (must not conflict with IP protocol version)
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*
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* The top nibble of the first octet is the packet type. There are three possible
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* types: IP (not proto TCP or tcp with one of the control flags set);
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* uncompressed TCP (a normal IP/TCP packet but with the 8-bit protocol field
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* replaced by an 8-bit connection id -- this type of packet syncs the sender &
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* receiver); and compressed TCP (described above).
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*
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_ LSB of 4-bit field is TCP "PUSH" bit (a worthless anachronism) and is logically
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* part of the 4-bit "changes" field that follows. Top three bits are actual
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* packet type. For backward compatibility and in the interest of conserving
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* bits, numbers are chosen so the IP protocol version number (4) which
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* normally appears in this nibble means "IP packet".
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*/
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/* packet types */
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#define TYPE_IP 0x40
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#define TYPE_UNCOMPRESSED_TCP 0x70
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#define TYPE_COMPRESSED_TCP 0x80
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#define TYPE_ERROR 0x00
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/* Bits in first octet of compressed packet */
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#define NEW_C 0x40 /* flag bits for what changed in a packet */
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#define NEW_I 0x20
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#define NEW_S 0x08
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#define NEW_A 0x04
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#define NEW_W 0x02
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#define NEW_U 0x01
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/* reserved, special-case values of above */
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#define SPECIAL_I (NEW_S|NEW_W|NEW_U) /* echoed interactive traffic */
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#define SPECIAL_D (NEW_S|NEW_A|NEW_W|NEW_U) /* unidirectional data */
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#define SPECIALS_MASK (NEW_S|NEW_A|NEW_W|NEW_U)
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#define TCP_PUSH_BIT 0x10
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/*
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* "state" data for each active tcp conversation on the wire. This is
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* basically a copy of the entire IP/TCP header from the last packet we saw
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* from the conversation together with a small identifier the transmit &
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* receive ends of the line use to locate saved header.
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*/
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struct cstate {
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struct cstate *cs_next; /* next most recently used cstate (xmit only) */
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ushort_t cs_hlen; /* size of hdr (receive only) */
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uchar_t cs_id; /* connection # associated with this state */
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uchar_t cs_filler;
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union {
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char csu_hdr[MAX_HDR];
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struct ip csu_ip; /* ip/tcp hdr from most recent packet */
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} slcs_u;
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};
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#define cs_ip slcs_u.csu_ip
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#define cs_hdr slcs_u.csu_hdr
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/*
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* all the state data for one serial line (we need one of these per line).
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*/
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struct compress {
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struct cstate *last_cs; /* most recently used tstate */
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uchar_t last_recv; /* last rcvd conn. id */
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uchar_t last_xmit; /* last sent conn. id */
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ushort_t flags;
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#ifndef SL_NO_STATS
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int sls_packets; /* outbound packets */
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int sls_compressed; /* outbound compressed packets */
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int sls_searches; /* searches for connection state */
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int sls_misses; /* times couldn't find conn. state */
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int sls_uncompressedin; /* inbound uncompressed packets */
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int sls_compressedin; /* inbound compressed packets */
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int sls_errorin; /* inbound unknown type packets */
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int sls_tossed; /* inbound packets tossed because of error */
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#endif
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struct cstate tstate[MAX_STATES]; /* xmit connection states */
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struct cstate rstate[MAX_STATES]; /* receive connection states */
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};
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/* flag values */
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#define SLF_TOSS 1 /* tossing rcvd frames because of input err */
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void compress_init (struct compress *);
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ushort_t compress_tcp (struct compress *, mblk_t **);
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void uncompress_tcp (struct compress *, mblk_t **, ushort_t);
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#endif
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