+++ /dev/null
-/*
- * Definitions for tcp compression routines.
- *
- * $Id: slcompress.h,v 1.4 1994/09/21 06:50:08 paulus Exp $
- *
- * Copyright (c) 1989 Regents of the University of California.
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms are permitted
- * provided that the above copyright notice and this paragraph are
- * duplicated in all such forms and that any documentation,
- * advertising materials, and other materials related to such
- * distribution and use acknowledge that the software was developed
- * by the University of California, Berkeley. The name of the
- * University may not be used to endorse or promote products derived
- * from this software without specific prior written permission.
- * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
- * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
- * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
- *
- * Van Jacobson (van@helios.ee.lbl.gov), Dec 31, 1989:
- * - Initial distribution.
- */
-
-#ifndef _SLCOMPRESS_H_
-#define _SLCOMPRESS_H_
-
-#define MAX_STATES 16 /* must be > 2 and < 256 */
-#define MAX_HDR MLEN /* XXX 4bsd-ism: should really be 128 */
-
-/*
- * Compressed packet format:
- *
- * The first octet contains the packet type (top 3 bits), TCP
- * 'push' bit, and flags that indicate which of the 4 TCP sequence
- * numbers have changed (bottom 5 bits). The next octet is a
- * conversation number that associates a saved IP/TCP header with
- * the compressed packet. The next two octets are the TCP checksum
- * from the original datagram. The next 0 to 15 octets are
- * sequence number changes, one change per bit set in the header
- * (there may be no changes and there are two special cases where
- * the receiver implicitly knows what changed -- see below).
- *
- * There are 5 numbers which can change (they are always inserted
- * in the following order): TCP urgent pointer, window,
- * acknowlegement, sequence number and IP ID. (The urgent pointer
- * is different from the others in that its value is sent, not the
- * change in value.) Since typical use of SLIP links is biased
- * toward small packets (see comments on MTU/MSS below), changes
- * use a variable length coding with one octet for numbers in the
- * range 1 - 255 and 3 octets (0, MSB, LSB) for numbers in the
- * range 256 - 65535 or 0. (If the change in sequence number or
- * ack is more than 65535, an uncompressed packet is sent.)
- */
-
-/*
- * Packet types (must not conflict with IP protocol version)
- *
- * The top nibble of the first octet is the packet type. There are
- * three possible types: IP (not proto TCP or tcp with one of the
- * control flags set); uncompressed TCP (a normal IP/TCP packet but
- * with the 8-bit protocol field replaced by an 8-bit connection id --
- * this type of packet syncs the sender & receiver); and compressed
- * TCP (described above).
- *
- * LSB of 4-bit field is TCP "PUSH" bit (a worthless anachronism) and
- * is logically part of the 4-bit "changes" field that follows. Top
- * three bits are actual packet type. For backward compatibility
- * and in the interest of conserving bits, numbers are chosen so the
- * IP protocol version number (4) which normally appears in this nibble
- * means "IP packet".
- */
-
-/* packet types */
-#define TYPE_IP 0x40
-#define TYPE_UNCOMPRESSED_TCP 0x70
-#define TYPE_COMPRESSED_TCP 0x80
-#define TYPE_ERROR 0x00
-
-/* Bits in first octet of compressed packet */
-#define NEW_C 0x40 /* flag bits for what changed in a packet */
-#define NEW_I 0x20
-#define NEW_S 0x08
-#define NEW_A 0x04
-#define NEW_W 0x02
-#define NEW_U 0x01
-
-/* reserved, special-case values of above */
-#define SPECIAL_I (NEW_S|NEW_W|NEW_U) /* echoed interactive traffic */
-#define SPECIAL_D (NEW_S|NEW_A|NEW_W|NEW_U) /* unidirectional data */
-#define SPECIALS_MASK (NEW_S|NEW_A|NEW_W|NEW_U)
-
-#define TCP_PUSH_BIT 0x10
-
-
-/*
- * "state" data for each active tcp conversation on the wire. This is
- * basically a copy of the entire IP/TCP header from the last packet
- * we saw from the conversation together with a small identifier
- * the transmit & receive ends of the line use to locate saved header.
- */
-struct cstate {
- struct cstate *cs_next; /* next most recently used cstate (xmit only) */
- u_short cs_hlen; /* size of hdr (receive only) */
- u_char cs_id; /* connection # associated with this state */
- u_char cs_filler;
- union {
- char csu_hdr[MAX_HDR];
- struct ip csu_ip; /* ip/tcp hdr from most recent packet */
- } slcs_u;
-};
-#define cs_ip slcs_u.csu_ip
-#define cs_hdr slcs_u.csu_hdr
-
-/*
- * all the state data for one serial line (we need one of these
- * per line).
- */
-struct slcompress {
- struct cstate *last_cs; /* most recently used tstate */
- u_char last_recv; /* last rcvd conn. id */
- u_char last_xmit; /* last sent conn. id */
- u_short flags;
-#ifndef SL_NO_STATS
- int sls_packets; /* outbound packets */
- int sls_compressed; /* outbound compressed packets */
- int sls_searches; /* searches for connection state */
- int sls_misses; /* times couldn't find conn. state */
- int sls_uncompressedin; /* inbound uncompressed packets */
- int sls_compressedin; /* inbound compressed packets */
- int sls_errorin; /* inbound unknown type packets */
- int sls_tossed; /* inbound packets tossed because of error */
-#endif
- struct cstate tstate[MAX_STATES]; /* xmit connection states */
- struct cstate rstate[MAX_STATES]; /* receive connection states */
-};
-/* flag values */
-#define SLF_TOSS 1 /* tossing rcvd frames because of input err */
-
-void sl_compress_init(struct slcompress *);
-void sl_compress_setup(struct slcompress *, int);
-u_int sl_compress_tcp(struct mbuf *,
- struct ip *, struct slcompress *, int);
-int sl_uncompress_tcp(u_char **, int, u_int, struct slcompress *);
-int sl_uncompress_tcp_core(u_char *, int, int, u_int,
- struct slcompress *, u_char **, u_int *);
-
-#endif /* _SLCOMPRESS_H_ */
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