[dragonfly.git] / contrib / tcpdump / slcompress.h

/*
 * Definitions for tcp compression routines.
 *
 * @(#) $Header: /tcpdump/master/tcpdump/slcompress.h,v 1.2 2000/10/09 02:03:44 guy Exp $ (LBL)
 *
 * Copyright (c) 1989, 1990, 1992, 1993 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@ee.lbl.gov), Dec 31, 1989:
 *	- Initial distribution.
 */

/*
 * 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
Commit	Line	Data
c8cf0f94 PA	1	/*
	2	* Definitions for tcp compression routines.
	3	*
	4	* @(#) $Header: /tcpdump/master/tcpdump/slcompress.h,v 1.2 2000/10/09 02:03:44 guy Exp $ (LBL)
	5	*
	6	* Copyright (c) 1989, 1990, 1992, 1993 Regents of the University of
	7	* California. All rights reserved.
	8	*
	9	* Redistribution and use in source and binary forms are permitted
	10	* provided that the above copyright notice and this paragraph are
	11	* duplicated in all such forms and that any documentation,
	12	* advertising materials, and other materials related to such
	13	* distribution and use acknowledge that the software was developed
	14	* by the University of California, Berkeley. The name of the
	15	* University may not be used to endorse or promote products derived
	16	* from this software without specific prior written permission.
	17	* THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
	18	* IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
	19	* WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
	20	*
	21	* Van Jacobson (van@ee.lbl.gov), Dec 31, 1989:
	22	* - Initial distribution.
	23	*/
	24
	25	/*
	26	* Compressed packet format:
	27	*
	28	* The first octet contains the packet type (top 3 bits), TCP
	29	* 'push' bit, and flags that indicate which of the 4 TCP sequence
	30	* numbers have changed (bottom 5 bits). The next octet is a
	31	* conversation number that associates a saved IP/TCP header with
	32	* the compressed packet. The next two octets are the TCP checksum
	33	* from the original datagram. The next 0 to 15 octets are
	34	* sequence number changes, one change per bit set in the header
	35	* (there may be no changes and there are two special cases where
	36	* the receiver implicitly knows what changed -- see below).
	37	*
	38	* There are 5 numbers which can change (they are always inserted
	39	* in the following order): TCP urgent pointer, window,
	40	* acknowlegement, sequence number and IP ID. (The urgent pointer
	41	* is different from the others in that its value is sent, not the
	42	* change in value.) Since typical use of SLIP links is biased
	43	* toward small packets (see comments on MTU/MSS below), changes
	44	* use a variable length coding with one octet for numbers in the
	45	* range 1 - 255 and 3 octets (0, MSB, LSB) for numbers in the
	46	* range 256 - 65535 or 0. (If the change in sequence number or
	47	* ack is more than 65535, an uncompressed packet is sent.)
	48	*/
	49
	50	/*
	51	* Packet types (must not conflict with IP protocol version)
	52	*
	53	* The top nibble of the first octet is the packet type. There are
	54	* three possible types: IP (not proto TCP or tcp with one of the
	55	* control flags set); uncompressed TCP (a normal IP/TCP packet but
	56	* with the 8-bit protocol field replaced by an 8-bit connection id --
	57	* this type of packet syncs the sender & receiver); and compressed
	58	* TCP (described above).
	59	*
	60	* LSB of 4-bit field is TCP "PUSH" bit (a worthless anachronism) and
	61	* is logically part of the 4-bit "changes" field that follows. Top
	62	* three bits are actual packet type. For backward compatibility
	63	* and in the interest of conserving bits, numbers are chosen so the
	64	* IP protocol version number (4) which normally appears in this nibble
65	* means "IP packet".
66	*/
67
68	/* packet types */
69	#define TYPE_IP 0x40
70	#define TYPE_UNCOMPRESSED_TCP 0x70
71	#define TYPE_COMPRESSED_TCP 0x80
72	#define TYPE_ERROR 0x00
73
74	/* Bits in first octet of compressed packet */
75	#define NEW_C 0x40 /* flag bits for what changed in a packet */
76	#define NEW_I 0x20
77	#define NEW_S 0x08
78	#define NEW_A 0x04
79	#define NEW_W 0x02
80	#define NEW_U 0x01
81
82	/* reserved, special-case values of above */
83	#define SPECIAL_I (NEW_S\|NEW_W\|NEW_U) /* echoed interactive traffic */
84	#define SPECIAL_D (NEW_S\|NEW_A\|NEW_W\|NEW_U) /* unidirectional data */
85	#define SPECIALS_MASK (NEW_S\|NEW_A\|NEW_W\|NEW_U)
86
87	#define TCP_PUSH_BIT 0x10