1 | /* $NetBSD: slcompress.h,v 1.18 2008/02/20 17:05:53 matt Exp $ */ |
2 | /* Id: slcompress.h,v 1.4 1994/09/21 06:50:08 paulus Exp */ |
3 | |
4 | /* |
5 | * Copyright (c) 1989, 1993 |
6 | * The Regents of the University of California. All rights reserved. |
7 | * |
8 | * Redistribution and use in source and binary forms, with or without |
9 | * modification, are permitted provided that the following conditions |
10 | * are met: |
11 | * 1. Redistributions of source code must retain the above copyright |
12 | * notice, this list of conditions and the following disclaimer. |
13 | * 2. Redistributions in binary form must reproduce the above copyright |
14 | * notice, this list of conditions and the following disclaimer in the |
15 | * documentation and/or other materials provided with the distribution. |
16 | * 3. Neither the name of the University nor the names of its contributors |
17 | * may be used to endorse or promote products derived from this software |
18 | * without specific prior written permission. |
19 | * |
20 | * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND |
21 | * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
22 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
23 | * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE |
24 | * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL |
25 | * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS |
26 | * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) |
27 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
28 | * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY |
29 | * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
30 | * SUCH DAMAGE. |
31 | * |
32 | * @(#)slcompress.h 8.1 (Berkeley) 6/10/93 |
33 | */ |
34 | |
35 | /* |
36 | * Definitions for tcp compression routines. |
37 | * |
38 | * Van Jacobson (van@helios.ee.lbl.gov), Dec 31, 1989: |
39 | * - Initial distribution. |
40 | */ |
41 | |
42 | #ifndef _NET_SLCOMPRESS_H_ |
43 | #define _NET_SLCOMPRESS_H_ |
44 | |
45 | #define MAX_STATES 16 /* must be > 2 and < 256 */ |
46 | #define MAX_HDR MLEN /* XXX 4bsd-ism: should really be 128 */ |
47 | |
48 | /* |
49 | * Compressed packet format: |
50 | * |
51 | * The first octet contains the packet type (top 3 bits), TCP |
52 | * 'push' bit, and flags that indicate which of the 4 TCP sequence |
53 | * numbers have changed (bottom 5 bits). The next octet is a |
54 | * conversation number that associates a saved IP/TCP header with |
55 | * the compressed packet. The next two octets are the TCP checksum |
56 | * from the original datagram. The next 0 to 15 octets are |
57 | * sequence number changes, one change per bit set in the header |
58 | * (there may be no changes and there are two special cases where |
59 | * the receiver implicitly knows what changed -- see below). |
60 | * |
61 | * There are 5 numbers which can change (they are always inserted |
62 | * in the following order): TCP urgent pointer, window, |
63 | * acknowlegement, sequence number and IP ID. (The urgent pointer |
64 | * is different from the others in that its value is sent, not the |
65 | * change in value.) Since typical use of SLIP links is biased |
66 | * toward small packets (see comments on MTU/MSS below), changes |
67 | * use a variable length coding with one octet for numbers in the |
68 | * range 1 - 255 and 3 octets (0, MSB, LSB) for numbers in the |
69 | * range 256 - 65535 or 0. (If the change in sequence number or |
70 | * ack is more than 65535, an uncompressed packet is sent.) |
71 | */ |
72 | |
73 | /* |
74 | * Packet types (must not conflict with IP protocol version) |
75 | * |
76 | * The top nibble of the first octet is the packet type. There are |
77 | * three possible types: IP (not proto TCP or tcp with one of the |
78 | * control flags set); uncompressed TCP (a normal IP/TCP packet but |
79 | * with the 8-bit protocol field replaced by an 8-bit connection id -- |
80 | * this type of packet syncs the sender & receiver); and compressed |
81 | * TCP (described above). |
82 | * |
83 | * LSB of 4-bit field is TCP "PUSH" bit (a worthless anachronism) and |
84 | * is logically part of the 4-bit "changes" field that follows. Top |
85 | * three bits are actual packet type. For backward compatibility |
86 | * and in the interest of conserving bits, numbers are chosen so the |
87 | * IP protocol version number (4) which normally appears in this nibble |
88 | * means "IP packet". |
89 | */ |
90 | |
91 | /* packet types */ |
92 | #define TYPE_IP 0x40 |
93 | #define TYPE_UNCOMPRESSED_TCP 0x70 |
94 | #define TYPE_COMPRESSED_TCP 0x80 |
95 | #define TYPE_ERROR 0x00 |
96 | |
97 | /* Bits in first octet of compressed packet */ |
98 | #define NEW_C 0x40 /* flag bits for what changed in a packet */ |
99 | #define NEW_I 0x20 |
100 | #define NEW_S 0x08 |
101 | #define NEW_A 0x04 |
102 | #define NEW_W 0x02 |
103 | #define NEW_U 0x01 |
104 | |
105 | /* reserved, special-case values of above */ |
106 | #define SPECIAL_I (NEW_S|NEW_W|NEW_U) /* echoed interactive traffic */ |
107 | #define SPECIAL_D (NEW_S|NEW_A|NEW_W|NEW_U) /* unidirectional data */ |
108 | #define SPECIALS_MASK (NEW_S|NEW_A|NEW_W|NEW_U) |
109 | |
110 | #define TCP_PUSH_BIT 0x10 |
111 | |
112 | |
113 | /* |
114 | * "state" data for each active tcp conversation on the wire. This is |
115 | * basically a copy of the entire IP/TCP header from the last packet |
116 | * we saw from the conversation together with a small identifier |
117 | * the transmit & receive ends of the line use to locate saved header. |
118 | */ |
119 | struct cstate { |
120 | struct cstate *cs_next; /* next most recently used cstate (xmit only) */ |
121 | uint16_t cs_hlen; /* size of hdr (receive only) */ |
122 | u_char cs_id; /* connection # associated with this state */ |
123 | u_char cs_filler; |
124 | union { |
125 | char csu_hdr[MAX_HDR]; |
126 | #ifdef INET |
127 | struct ip csu_ip; /* ip/tcp hdr from most recent packet */ |
128 | #endif |
129 | } slcs_u; |
130 | }; |
131 | #define cs_ip slcs_u.csu_ip |
132 | #define cs_hdr slcs_u.csu_hdr |
133 | |
134 | /* |
135 | * all the state data for one serial line (we need one of these |
136 | * per line). |
137 | */ |
138 | struct slcompress { |
139 | struct cstate *last_cs; /* most recently used tstate */ |
140 | u_char last_recv; /* last rcvd conn. id */ |
141 | u_char last_xmit; /* last sent conn. id */ |
142 | uint16_t flags; |
143 | #ifndef SL_NO_STATS |
144 | int sls_packets; /* outbound packets */ |
145 | int sls_compressed; /* outbound compressed packets */ |
146 | int sls_searches; /* searches for connection state */ |
147 | int sls_misses; /* times couldn't find conn. state */ |
148 | int sls_uncompressedin; /* inbound uncompressed packets */ |
149 | int sls_compressedin; /* inbound compressed packets */ |
150 | int sls_errorin; /* inbound unknown type packets */ |
151 | int sls_tossed; /* inbound packets tossed because of error */ |
152 | #endif |
153 | struct cstate tstate[MAX_STATES]; /* xmit connection states */ |
154 | struct cstate rstate[MAX_STATES]; /* receive connection states */ |
155 | }; |
156 | /* flag values */ |
157 | #define SLF_TOSS 1 /* tossing rcvd frames because of input err */ |
158 | |
159 | void sl_compress_init(struct slcompress *); |
160 | void sl_compress_setup(struct slcompress *, int); |
161 | #ifdef INET |
162 | u_int sl_compress_tcp(struct mbuf *, |
163 | struct ip *, struct slcompress *, int); |
164 | #endif |
165 | int sl_uncompress_tcp(u_char **, int, u_int, struct slcompress *); |
166 | int sl_uncompress_tcp_core(u_char *, int, int, u_int, |
167 | struct slcompress *, u_char **, u_int *); |
168 | |
169 | #endif /* !_NET_SLCOMPRESS_H_ */ |
170 | |