[unix-history] / sys / net / slcompress.h

/*	slcompress.h	7.4	90/06/28	*/
/*
 * Definitions for tcp compression routines.
 *
 * $Header: slcompress.h,v 1.10 89/12/31 08:53:02 van Exp $
 *
 * Copyright (c) 1989 Regents of the University of California.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by the University of
 *	California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *	Van Jacobson (van@helios.ee.lbl.gov), Dec 31, 1989:
 *	- Initial distribution.
 */

#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 */

extern void sl_compress_init(/* struct slcompress * */);
extern u_char sl_compress_tcp(/* struct mbuf *, struct ip *,
				struct slcompress *, int compress_cid_flag */);
extern int sl_uncompress_tcp(/* u_char **, int,  u_char, struct slcompress * */);
Commit	Line	Data
15637ed4 RG	1	/* slcompress.h 7.4 90/06/28 */
	2	/*
	3	* Definitions for tcp compression routines.
	4	*
	5	* $Header: slcompress.h,v 1.10 89/12/31 08:53:02 van Exp $
	6	*
	7	* Copyright (c) 1989 Regents of the University of California.
	8	* All rights reserved.
	9	*
	10	* Redistribution and use in source and binary forms, with or without
	11	* modification, are permitted provided that the following conditions
	12	* are met:
	13	* 1. Redistributions of source code must retain the above copyright
	14	* notice, this list of conditions and the following disclaimer.
	15	* 2. Redistributions in binary form must reproduce the above copyright
	16	* notice, this list of conditions and the following disclaimer in the
	17	* documentation and/or other materials provided with the distribution.
	18	* 3. All advertising materials mentioning features or use of this software
	19	* must display the following acknowledgement:
	20	* This product includes software developed by the University of
	21	* California, Berkeley and its contributors.
	22	* 4. Neither the name of the University nor the names of its contributors
	23	* may be used to endorse or promote products derived from this software
	24	* without specific prior written permission.
	25	*
	26	* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
	27	* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
	28	* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
	29	* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
	30	* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
	31	* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
	32	* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
	33	* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
	34	* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
	35	* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
	36	* SUCH DAMAGE.
	37	*
	38	* Van Jacobson (van@helios.ee.lbl.gov), Dec 31, 1989:
	39	* - Initial distribution.
	40	*/
	41
	42	#define MAX_STATES 16 /* must be > 2 and < 256 */
	43	#define MAX_HDR MLEN /* XXX 4bsd-ism: should really be 128 */
	44
	45	/*
	46	* Compressed packet format:
	47	*
	48	* The first octet contains the packet type (top 3 bits), TCP
	49	* 'push' bit, and flags that indicate which of the 4 TCP sequence
	50	* numbers have changed (bottom 5 bits). The next octet is a
	51	* conversation number that associates a saved IP/TCP header with
	52	* the compressed packet. The next two octets are the TCP checksum
	53	* from the original datagram. The next 0 to 15 octets are
	54	* sequence number changes, one change per bit set in the header
	55	* (there may be no changes and there are two special cases where
	56	* the receiver implicitly knows what changed -- see below).
	57	*
	58	* There are 5 numbers which can change (they are always inserted
	59	* in the following order): TCP urgent pointer, window,
	60	* acknowlegement, sequence number and IP ID. (The urgent pointer
	61	* is different from the others in that its value is sent, not the
	62	* change in value.) Since typical use of SLIP links is biased
	63	* toward small packets (see comments on MTU/MSS below), changes
	64	* use a variable length coding with one octet for numbers in the
65	* range 1 - 255 and 3 octets (0, MSB, LSB) for numbers in the
66	* range 256 - 65535 or 0. (If the change in sequence number or
67	* ack is more than 65535, an uncompressed packet is sent.)
68	*/
69
70	/*
71	* Packet types (must not conflict with IP protocol version)
72	*
73	* The top nibble of the first octet is the packet type. There are
74	* three possible types: IP (not proto TCP or tcp with one of the
75	* control flags set); uncompressed TCP (a normal IP/TCP packet but
76	* with the 8-bit protocol field replaced by an 8-bit connection id --
77	* this type of packet syncs the sender & receiver); and compressed
78	* TCP (described above).
79	*
80	* LSB of 4-bit field is TCP "PUSH" bit (a worthless anachronism) and
81	* is logically part of the 4-bit "changes" field that follows. Top
82	* three bits are actual packet type. For backward compatibility
83	* and in the interest of conserving bits, numbers are chosen so the
84	* IP protocol version number (4) which normally appears in this nibble
85	* means "IP packet".
86	*/
87
88	/* packet types */
89	#define TYPE_IP 0x40
90	#define TYPE_UNCOMPRESSED_TCP 0x70
91	#define TYPE_COMPRESSED_TCP 0x80
92	#define TYPE_ERROR 0x00
93
94	/* Bits in first octet of compressed packet */
95	#define NEW_C 0x40 /* flag bits for what changed in a packet */
96	#define NEW_I 0x20
97	#define NEW_S 0x08
98	#define NEW_A 0x04
99	#define NEW_W 0x02
100	#define NEW_U 0x01
101
102	/* reserved, special-case values of above */
103	#define SPECIAL_I (NEW_S\|NEW_W\|NEW_U) /* echoed interactive traffic */
104	#define SPECIAL_D (NEW_S\|NEW_A\|NEW_W\|NEW_U) /* unidirectional data */
105	#define SPECIALS_MASK (NEW_S\|NEW_A\|NEW_W\|NEW_U)
106
107	#define TCP_PUSH_BIT 0x10
108
109
110	/*
111	* "state" data for each active tcp conversation on the wire. This is
112	* basically a copy of the entire IP/TCP header from the last packet
113	* we saw from the conversation together with a small identifier
114	* the transmit & receive ends of the line use to locate saved header.
115	*/
116	struct cstate {
117	struct cstate cs_next; / next most recently used cstate (xmit only) */
118	u_short cs_hlen; /* size of hdr (receive only) */
119	u_char cs_id; /* connection # associated with this state */
120	u_char cs_filler;
121	union {
122	char csu_hdr[MAX_HDR];
123	struct ip csu_ip; /* ip/tcp hdr from most recent packet */
124	} slcs_u;
125	};
126	#define cs_ip slcs_u.csu_ip
127	#define cs_hdr slcs_u.csu_hdr
128
129	/*
130	* all the state data for one serial line (we need one of these
131	* per line).
132	*/
133	struct slcompress {
134	struct cstate last_cs; / most recently used tstate */
135	u_char last_recv; /* last rcvd conn. id */
136	u_char last_xmit; /* last sent conn. id */
137	u_short flags;
138	#ifndef SL_NO_STATS
139	int sls_packets; /* outbound packets */
140	int sls_compressed; /* outbound compressed packets */
141	int sls_searches; /* searches for connection state */
142	int sls_misses; /* times couldn't find conn. state */
143	int sls_uncompressedin; /* inbound uncompressed packets */
144	int sls_compressedin; /* inbound compressed packets */
145	int sls_errorin; /* inbound unknown type packets */
146	int sls_tossed; /* inbound packets tossed because of error */
147	#endif
148	struct cstate tstate[MAX_STATES]; /* xmit connection states */
149	struct cstate rstate[MAX_STATES]; /* receive connection states */
150	};
151	/* flag values */
152	#define SLF_TOSS 1 /* tossing rcvd frames because of input err */
153
154	extern void sl_compress_init(/* struct slcompress * */);
155	extern u_char sl_compress_tcp(/* struct mbuf , struct ip ,
156	struct slcompress , int compress_cid_flag /);
157	extern int sl_uncompress_tcp(/* u_char *, int, u_char, struct slcompress */);