nataraid(4): Add devstat support.
[dragonfly.git] / sys / net / slcompress.h
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1/*
2 * Definitions for tcp compression routines.
3 *
4 * Copyright (c) 1989, 1993
5 * The Regents of the University of California. All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 * 3. All advertising materials mentioning features or use of this software
16 * must display the following acknowledgement:
17 * This product includes software developed by the University of
18 * California, Berkeley and its contributors.
19 * 4. Neither the name of the University nor the names of its contributors
20 * may be used to endorse or promote products derived from this software
21 * without specific prior written permission.
22 *
23 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
24 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
25 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
26 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
27 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
28 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
29 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
30 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
31 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
32 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
33 * SUCH DAMAGE.
34 *
35 * Van Jacobson (van@helios.ee.lbl.gov), Dec 31, 1989:
36 * - Initial distribution.
37 * $FreeBSD: src/sys/net/slcompress.h,v 1.14.2.1 2000/05/05 13:37:06 jlemon Exp $
03d6a592 38 * $DragonFly: src/sys/net/slcompress.h,v 1.5 2006/05/21 03:43:45 dillon Exp $
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39 */
40
41#ifndef _NET_SLCOMPRESS_H_
42#define _NET_SLCOMPRESS_H_
43
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44#ifndef _SYS_TYPES_H_
45#include <sys/types.h>
46#endif
47#ifndef _NETINET_IP_H_
48#include <netinet/ip.h>
49#endif
50
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51#define MAX_STATES 16 /* must be > 2 and < 256 */
52#define MAX_HDR 128
53
54/*
55 * Compressed packet format:
56 *
57 * The first octet contains the packet type (top 3 bits), TCP
58 * 'push' bit, and flags that indicate which of the 4 TCP sequence
59 * numbers have changed (bottom 5 bits). The next octet is a
60 * conversation number that associates a saved IP/TCP header with
61 * the compressed packet. The next two octets are the TCP checksum
62 * from the original datagram. The next 0 to 15 octets are
63 * sequence number changes, one change per bit set in the header
64 * (there may be no changes and there are two special cases where
65 * the receiver implicitly knows what changed -- see below).
66 *
67 * There are 5 numbers which can change (they are always inserted
68 * in the following order): TCP urgent pointer, window,
69 * acknowledgement, sequence number and IP ID. (The urgent pointer
70 * is different from the others in that its value is sent, not the
71 * change in value.) Since typical use of SLIP links is biased
72 * toward small packets (see comments on MTU/MSS below), changes
73 * use a variable length coding with one octet for numbers in the
74 * range 1 - 255 and 3 octets (0, MSB, LSB) for numbers in the
75 * range 256 - 65535 or 0. (If the change in sequence number or
76 * ack is more than 65535, an uncompressed packet is sent.)
77 */
78
79/*
80 * Packet types (must not conflict with IP protocol version)
81 *
82 * The top nibble of the first octet is the packet type. There are
83 * three possible types: IP (not proto TCP or tcp with one of the
84 * control flags set); uncompressed TCP (a normal IP/TCP packet but
85 * with the 8-bit protocol field replaced by an 8-bit connection id --
86 * this type of packet syncs the sender & receiver); and compressed
87 * TCP (described above).
88 *
89 * LSB of 4-bit field is TCP "PUSH" bit (a worthless anachronism) and
90 * is logically part of the 4-bit "changes" field that follows. Top
91 * three bits are actual packet type. For backward compatibility
92 * and in the interest of conserving bits, numbers are chosen so the
93 * IP protocol version number (4) which normally appears in this nibble
94 * means "IP packet".
95 */
96
97/* packet types */
98#define TYPE_IP 0x40
99#define TYPE_UNCOMPRESSED_TCP 0x70
100#define TYPE_COMPRESSED_TCP 0x80
101#define TYPE_ERROR 0x00
102
103/* Bits in first octet of compressed packet */
104#define NEW_C 0x40 /* flag bits for what changed in a packet */
105#define NEW_I 0x20
106#define NEW_S 0x08
107#define NEW_A 0x04
108#define NEW_W 0x02
109#define NEW_U 0x01
110
111/* reserved, special-case values of above */
112#define SPECIAL_I (NEW_S|NEW_W|NEW_U) /* echoed interactive traffic */
113#define SPECIAL_D (NEW_S|NEW_A|NEW_W|NEW_U) /* unidirectional data */
114#define SPECIALS_MASK (NEW_S|NEW_A|NEW_W|NEW_U)
115
116#define TCP_PUSH_BIT 0x10
117
118
119/*
120 * "state" data for each active tcp conversation on the wire. This is
121 * basically a copy of the entire IP/TCP header from the last packet
122 * we saw from the conversation together with a small identifier
123 * the transmit & receive ends of the line use to locate saved header.
124 */
125struct cstate {
126 struct cstate *cs_next; /* next most recently used cstate (xmit only) */
127 u_int16_t cs_hlen; /* size of hdr (receive only) */
128 u_char cs_id; /* connection # associated with this state */
129 u_char cs_filler;
130 union {
131 char csu_hdr[MAX_HDR];
132 struct ip csu_ip; /* ip/tcp hdr from most recent packet */
133 } slcs_u;
134};
135#define cs_ip slcs_u.csu_ip
136#define cs_hdr slcs_u.csu_hdr
137
138/*
139 * all the state data for one serial line (we need one of these
140 * per line).
141 */
142struct slcompress {
143 struct cstate *last_cs; /* most recently used tstate */
144 u_char last_recv; /* last rcvd conn. id */
145 u_char last_xmit; /* last sent conn. id */
146 u_int16_t flags;
147#ifndef SL_NO_STATS
148 int sls_packets; /* outbound packets */
149 int sls_compressed; /* outbound compressed packets */
150 int sls_searches; /* searches for connection state */
151 int sls_misses; /* times couldn't find conn. state */
152 int sls_uncompressedin; /* inbound uncompressed packets */
153 int sls_compressedin; /* inbound compressed packets */
154 int sls_errorin; /* inbound unknown type packets */
155 int sls_tossed; /* inbound packets tossed because of error */
156#endif
157 struct cstate tstate[MAX_STATES]; /* xmit connection states */
158 struct cstate rstate[MAX_STATES]; /* receive connection states */
159};
160/* flag values */
161#define SLF_TOSS 1 /* tossing rcvd frames because of input err */
162
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163struct mbuf;
164
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165void sl_compress_init (struct slcompress *, int);
166u_int sl_compress_tcp (struct mbuf *,
167 struct ip *, struct slcompress *, int);
168int sl_uncompress_tcp (u_char **, int, u_int, struct slcompress *);
169int sl_uncompress_tcp_core (u_char *, int, int, u_int,
170 struct slcompress *, u_char **, u_int *);
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171
172#endif /* !_NET_SLCOMPRESS_H_ */