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1.1 root 1: /* slcompress.h 7.4 90/06/28 */
2: /*
3: * Definitions for tcp compression routines.
4: *
1.1.1.3 ! root 5: * /b/source/CVS/src/sys/net/slcompress.h,v 1.3 1993/05/20 03:06:13 cgd Exp
1.1 root 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 ([email protected]), Dec 31, 1989:
39: * - Initial distribution.
1.1.1.3 ! root 40: *
! 41: * slcompress.h,v 1.3 1993/05/20 03:06:13 cgd Exp
1.1 root 42: */
43:
1.1.1.3 ! root 44: #ifndef _NET_SLCOMPRESS_H_
! 45: #define _NET_SLCOMPRESS_H_
! 46:
1.1 root 47: #define MAX_STATES 16 /* must be > 2 and < 256 */
48: #define MAX_HDR MLEN /* XXX 4bsd-ism: should really be 128 */
49:
50: /*
51: * Compressed packet format:
52: *
53: * The first octet contains the packet type (top 3 bits), TCP
54: * 'push' bit, and flags that indicate which of the 4 TCP sequence
55: * numbers have changed (bottom 5 bits). The next octet is a
56: * conversation number that associates a saved IP/TCP header with
57: * the compressed packet. The next two octets are the TCP checksum
58: * from the original datagram. The next 0 to 15 octets are
59: * sequence number changes, one change per bit set in the header
60: * (there may be no changes and there are two special cases where
61: * the receiver implicitly knows what changed -- see below).
62: *
63: * There are 5 numbers which can change (they are always inserted
64: * in the following order): TCP urgent pointer, window,
65: * acknowlegement, sequence number and IP ID. (The urgent pointer
66: * is different from the others in that its value is sent, not the
67: * change in value.) Since typical use of SLIP links is biased
68: * toward small packets (see comments on MTU/MSS below), changes
69: * use a variable length coding with one octet for numbers in the
70: * range 1 - 255 and 3 octets (0, MSB, LSB) for numbers in the
71: * range 256 - 65535 or 0. (If the change in sequence number or
72: * ack is more than 65535, an uncompressed packet is sent.)
73: */
74:
75: /*
76: * Packet types (must not conflict with IP protocol version)
77: *
78: * The top nibble of the first octet is the packet type. There are
79: * three possible types: IP (not proto TCP or tcp with one of the
80: * control flags set); uncompressed TCP (a normal IP/TCP packet but
81: * with the 8-bit protocol field replaced by an 8-bit connection id --
82: * this type of packet syncs the sender & receiver); and compressed
83: * TCP (described above).
84: *
85: * LSB of 4-bit field is TCP "PUSH" bit (a worthless anachronism) and
86: * is logically part of the 4-bit "changes" field that follows. Top
87: * three bits are actual packet type. For backward compatibility
88: * and in the interest of conserving bits, numbers are chosen so the
89: * IP protocol version number (4) which normally appears in this nibble
90: * means "IP packet".
91: */
92:
93: /* packet types */
94: #define TYPE_IP 0x40
95: #define TYPE_UNCOMPRESSED_TCP 0x70
96: #define TYPE_COMPRESSED_TCP 0x80
97: #define TYPE_ERROR 0x00
98:
99: /* Bits in first octet of compressed packet */
100: #define NEW_C 0x40 /* flag bits for what changed in a packet */
101: #define NEW_I 0x20
102: #define NEW_S 0x08
103: #define NEW_A 0x04
104: #define NEW_W 0x02
105: #define NEW_U 0x01
106:
107: /* reserved, special-case values of above */
108: #define SPECIAL_I (NEW_S|NEW_W|NEW_U) /* echoed interactive traffic */
109: #define SPECIAL_D (NEW_S|NEW_A|NEW_W|NEW_U) /* unidirectional data */
110: #define SPECIALS_MASK (NEW_S|NEW_A|NEW_W|NEW_U)
111:
112: #define TCP_PUSH_BIT 0x10
113:
114:
115: /*
116: * "state" data for each active tcp conversation on the wire. This is
117: * basically a copy of the entire IP/TCP header from the last packet
118: * we saw from the conversation together with a small identifier
119: * the transmit & receive ends of the line use to locate saved header.
120: */
121: struct cstate {
122: struct cstate *cs_next; /* next most recently used cstate (xmit only) */
123: u_short cs_hlen; /* size of hdr (receive only) */
124: u_char cs_id; /* connection # associated with this state */
125: u_char cs_filler;
126: union {
127: char csu_hdr[MAX_HDR];
128: struct ip csu_ip; /* ip/tcp hdr from most recent packet */
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: u_short 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: extern void sl_compress_init(/* struct slcompress * */);
160: extern u_char sl_compress_tcp(/* struct mbuf *, struct ip *,
161: struct slcompress *, int compress_cid_flag */);
162: extern int sl_uncompress_tcp(/* u_char **, int, u_char, struct slcompress * */);
1.1.1.3 ! root 163:
! 164: #endif /* !_NET_SLCOMPRESS_H_ */
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