Watt-32 tcp/ip  2.2 dev-rel.10
slcompre.h
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1 
5 /* $NetBSD: slcompress.h,v 1.11 1997/05/17 21:12:11 christos Exp $ */
6 /* Id: slcompress.h,v 1.4 1994/09/21 06:50:08 paulus Exp */
7 
8 /*
9  * Copyright (c) 1989, 1993
10  * The Regents of the University of California. All rights reserved.
11  *
12  * Redistribution and use in source and binary forms, with or without
13  * modification, are permitted provided that the following conditions
14  * are met:
15  * 1. Redistributions of source code must retain the above copyright
16  * notice, this list of conditions and the following disclaimer.
17  * 2. Redistributions in binary form must reproduce the above copyright
18  * notice, this list of conditions and the following disclaimer in the
19  * documentation and/or other materials provided with the distribution.
20  * 3. All advertising materials mentioning features or use of this software
21  * must display the following acknowledgement:
22  * This product includes software developed by the University of
23  * California, Berkeley and its contributors.
24  * 4. Neither the name of the University nor the names of its contributors
25  * may be used to endorse or promote products derived from this software
26  * without specific prior written permission.
27  *
28  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
29  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
30  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
31  * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
32  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
33  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
34  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
35  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
36  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
37  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
38  * SUCH DAMAGE.
39  *
40  * @(#)slcompress.h 8.1 (Berkeley) 6/10/93
41  */
42 
43 /*
44  * Definitions for tcp compression routines.
45  *
46  * Van Jacobson (van@helios.ee.lbl.gov), Dec 31, 1989:
47  * - Initial distribution.
48  */
49 
50 #ifndef __NET_SLCOMPRESS_H
51 #define __NET_SLCOMPRESS_H
52 
53 #ifndef __SYS_MBUF_H
54 #include <sys/mbuf.h>
55 #endif
56 
57 #ifndef MLEN
58 #define MLEN 128
59 #endif
60 
61 #define MAX_STATES 16 /* must be > 2 and < 256 */
62 #define MAX_HDR MLEN /* XXX 4bsd-ism: should really be 128 */
63 
64 /*
65  * Compressed packet format:
66  *
67  * The first octet contains the packet type (top 3 bits), TCP
68  * 'push' bit, and flags that indicate which of the 4 TCP sequence
69  * numbers have changed (bottom 5 bits). The next octet is a
70  * conversation number that associates a saved IP/TCP header with
71  * the compressed packet. The next two octets are the TCP checksum
72  * from the original datagram. The next 0 to 15 octets are
73  * sequence number changes, one change per bit set in the header
74  * (there may be no changes and there are two special cases where
75  * the receiver implicitly knows what changed -- see below).
76  *
77  * There are 5 numbers which can change (they are always inserted
78  * in the following order): TCP urgent pointer, window,
79  * acknowlegement, sequence number and IP ID. (The urgent pointer
80  * is different from the others in that its value is sent, not the
81  * change in value.) Since typical use of SLIP links is biased
82  * toward small packets (see comments on MTU/MSS below), changes
83  * use a variable length coding with one octet for numbers in the
84  * range 1 - 255 and 3 octets (0, MSB, LSB) for numbers in the
85  * range 256 - 65535 or 0. (If the change in sequence number or
86  * ack is more than 65535, an uncompressed packet is sent.)
87  */
88 
89 /*
90  * Packet types (must not conflict with IP protocol version)
91  *
92  * The top nibble of the first octet is the packet type. There are
93  * three possible types: IP (not proto TCP or tcp with one of the
94  * control flags set); uncompressed TCP (a normal IP/TCP packet but
95  * with the 8-bit protocol field replaced by an 8-bit connection id --
96  * this type of packet syncs the sender & receiver); and compressed
97  * TCP (described above).
98  *
99  * LSB of 4-bit field is TCP "PUSH" bit (a worthless anachronism) and
100  * is logically part of the 4-bit "changes" field that follows. Top
101  * three bits are actual packet type. For backward compatibility
102  * and in the interest of conserving bits, numbers are chosen so the
103  * IP protocol version number (4) which normally appears in this nibble
104  * means "IP packet".
105  */
106 
107 /* packet types */
108 #define TYPE_IP 0x40
109 #define TYPE_UNCOMPRESSED_TCP 0x70
110 #define TYPE_COMPRESSED_TCP 0x80
111 #define TYPE_ERROR 0x00
112 
113 /* Bits in first octet of compressed packet */
114 #define NEW_C 0x40 /* flag bits for what changed in a packet */
115 #define NEW_I 0x20
116 #define NEW_S 0x08
117 #define NEW_A 0x04
118 #define NEW_W 0x02
119 #define NEW_U 0x01
120 
121 /* reserved, special-case values of above */
122 #define SPECIAL_I (NEW_S|NEW_W|NEW_U) /* echoed interactive traffic */
123 #define SPECIAL_D (NEW_S|NEW_A|NEW_W|NEW_U) /* unidirectional data */
124 #define SPECIALS_MASK (NEW_S|NEW_A|NEW_W|NEW_U)
125 
126 #define TCP_PUSH_BIT 0x10
127 
128 
129 /*
130  * "state" data for each active tcp conversation on the wire. This is
131  * basically a copy of the entire IP/TCP header from the last packet
132  * we saw from the conversation together with a small identifier
133  * the transmit & receive ends of the line use to locate saved header.
134  */
135 struct cstate {
136  struct cstate *cs_next; /* next most recently used cstate (xmit only) */
137  u_int16_t cs_hlen; /* size of hdr (receive only) */
138  u_char cs_id; /* connection # associated with this state */
139  u_char cs_filler;
140  union {
141  char csu_hdr[MAX_HDR];
142  struct ip csu_ip; /* ip/tcp hdr from most recent packet */
143  } slcs_u;
144 };
145 #define cs_ip slcs_u.csu_ip
146 #define cs_hdr slcs_u.csu_hdr
147 
148 /*
149  * all the state data for one serial line (we need one of these
150  * per line).
151  */
152 struct slcompress {
153  struct cstate *last_cs; /* most recently used tstate */
154  u_char last_recv; /* last rcvd conn. id */
155  u_char last_xmit; /* last sent conn. id */
156  u_int16_t flags;
157 #ifndef SL_NO_STATS
158  int sls_packets; /* outbound packets */
159  int sls_compressed; /* outbound compressed packets */
160  int sls_searches; /* searches for connection state */
161  int sls_misses; /* times couldn't find conn. state */
162  int sls_uncompressedin; /* inbound uncompressed packets */
163  int sls_compressedin; /* inbound compressed packets */
164  int sls_errorin; /* inbound unknown type packets */
165  int sls_tossed; /* inbound packets tossed because of error */
166 #endif
167  struct cstate tstate[MAX_STATES]; /* xmit connection states */
168  struct cstate rstate[MAX_STATES]; /* receive connection states */
169 };
170 /* flag values */
171 #define SLF_TOSS 1 /* tossing rcvd frames because of input err */
172 
173 void sl_compress_init (struct slcompress *);
174 void sl_compress_setup (struct slcompress *, int);
175 u_int sl_compress_tcp (struct mbuf *, struct ip *, struct slcompress *, int);
176 int sl_uncompress_tcp (u_char **, int, u_int, struct slcompress *);
177 int sl_uncompress_tcp_core (u_char *, int, int, u_int, struct slcompress *, u_char **, u_int *);
178 
179 #endif
Definition: pcpkt.h:135
Definition: ip.h:67
Definition: mbuf.h:6