1 #ifndef _SLHC_H 1
2 #define _SLHC_H
3 /*
4 * Definitions for tcp compression routines.
5 *
6 * $Header: slcompress.h,v 1.10 89/12/31 08:53
7 *
8 * Copyright (c) 1989 Regents of the Universit
9 * All rights reserved.
10 *
11 * Redistribution and use in source and binary
12 * provided that the above copyright notice an
13 * duplicated in all such forms and that any d
14 * advertising materials, and other materials
15 * distribution and use acknowledge that the s
16 * by the University of California, Berkeley.
17 * University may not be used to endorse or pr
18 * from this software without specific prior w
19 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WIT
20 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMI
21 * WARRANTIES OF MERCHANTABILITY AND FITNESS F
22 *
23 * Van Jacobson (van@helios.ee.lbl.gov),
24 * - Initial distribution.
25 *
26 *
27 * modified for KA9Q Internet Software Package
28 * Katie Stevens (dkstevens@ucdavis.edu)
29 * University of California, Davis
30 * Computing Services
31 * - 01-31-90 initial adaptation
32 *
33 * - Feb 1991 Bill_Simpson@um.cc.umi
34 * variable number of con
35 * allow zero or one slot
36 * separate routines
37 * status display
38 */
39
40 /*
41 * Compressed packet format:
42 *
43 * The first octet contains the packet type (t
44 * 'push' bit, and flags that indicate which o
45 * numbers have changed (bottom 5 bits). The
46 * conversation number that associates a saved
47 * the compressed packet. The next two octets
48 * from the original datagram. The next 0 to
49 * sequence number changes, one change per bit
50 * (there may be no changes and there are two
51 * the receiver implicitly knows what changed
52 *
53 * There are 5 numbers which can change (they
54 * in the following order): TCP urgent pointer
55 * acknowledgment, sequence number and IP ID.
56 * is different from the others in that its va
57 * change in value.) Since typical use of SLI
58 * toward small packets (see comments on MTU/M
59 * use a variable length coding with one octet
60 * range 1 - 255 and 3 octets (0, MSB, LSB) fo
61 * range 256 - 65535 or 0. (If the change in
62 * ack is more than 65535, an uncompressed pac
63 */
64
65 /*
66 * Packet types (must not conflict with IP pro
67 *
68 * The top nibble of the first octet is the pa
69 * three possible types: IP (not proto TCP or
70 * control flags set); uncompressed TCP (a nor
71 * with the 8-bit protocol field replaced by a
72 * this type of packet syncs the sender & rece
73 * TCP (described above).
74 *
75 * LSB of 4-bit field is TCP "PUSH" bit (a wor
76 * is logically part of the 4-bit "changes" fi
77 * three bits are actual packet type. For bac
78 * and in the interest of conserving bits, num
79 * IP protocol version number (4) which normal
80 * means "IP packet".
81 */
82
83
84 #include <linux/ip.h>
85 #include <linux/tcp.h>
86
87 /* SLIP compression masks for len/vers byte */
88 #define SL_TYPE_IP 0x40
89 #define SL_TYPE_UNCOMPRESSED_TCP 0x70
90 #define SL_TYPE_COMPRESSED_TCP 0x80
91 #define SL_TYPE_ERROR 0x00
92
93 /* Bits in first octet of compressed packet */
94 #define NEW_C 0x40 /* flag bits for what
95 #define NEW_I 0x20
96 #define NEW_S 0x08
97 #define NEW_A 0x04
98 #define NEW_W 0x02
99 #define NEW_U 0x01
100
101 /* reserved, special-case values of above */
102 #define SPECIAL_I (NEW_S|NEW_W|NEW_U)
103 #define SPECIAL_D (NEW_S|NEW_A|NEW_W|NEW_U)
104 #define SPECIALS_MASK (NEW_S|NEW_A|NEW_W|NEW_U
105
106 #define TCP_PUSH_BIT 0x10
107
108 /*
109 * data type and sizes conversion assumptions:
110 *
111 * VJ code KA9Q style generi
112 * u_char byte_t unsign
113 * u_short int16 unsign
114 * u_int int16 unsign
115 * u_long unsigned long unsign
116 * int int32 long
117 */
118
119 typedef __u8 byte_t;
120 typedef __u32 int32;
121
122 /*
123 * "state" data for each active tcp conversati
124 * basically a copy of the entire IP/TCP heade
125 * we saw from the conversation together with
126 * the transmit & receive ends of the line use
127 */
128 struct cstate {
129 byte_t cs_this; /* connection
130 bool initialized; /* true if ini
131 struct cstate *next; /* next in rin
132 struct iphdr cs_ip; /* ip/tcp hdr
133 struct tcphdr cs_tcp;
134 unsigned char cs_ipopt[64];
135 unsigned char cs_tcpopt[64];
136 int cs_hsize;
137 };
138 #define NULLSLSTATE (struct cstate *)0
139
140 /*
141 * all the state data for one serial line (we
142 */
143 struct slcompress {
144 struct cstate *tstate; /* transmit co
145 struct cstate *rstate; /* receive con
146
147 byte_t tslot_limit; /* highest tra
148 byte_t rslot_limit; /* highest rec
149
150 byte_t xmit_oldest; /* oldest xmit
151 byte_t xmit_current; /* most recent
152 byte_t recv_current; /* most recent
153
154 byte_t flags;
155 #define SLF_TOSS 0x01 /* tossing rcv
156
157 int32 sls_o_nontcp; /* outbound no
158 int32 sls_o_tcp; /* outbound TC
159 int32 sls_o_uncompressed; /* out
160 int32 sls_o_compressed; /* outbound co
161 int32 sls_o_searches; /* searches fo
162 int32 sls_o_misses; /* times could
163
164 int32 sls_i_uncompressed; /* inb
165 int32 sls_i_compressed; /* inbound com
166 int32 sls_i_error; /* inbound err
167 int32 sls_i_tossed; /* inbound pac
168
169 int32 sls_i_runt;
170 int32 sls_i_badcheck;
171 };
172 #define NULLSLCOMPR (struct slcompress *)0
173
174 /* In slhc.c: */
175 struct slcompress *slhc_init(int rslots, int t
176 void slhc_free(struct slcompress *comp);
177
178 int slhc_compress(struct slcompress *comp, uns
179 unsigned char *ocp, unsigned
180 int slhc_uncompress(struct slcompress *comp, u
181 int slhc_remember(struct slcompress *comp, uns
182 int slhc_toss(struct slcompress *comp);
183
184 #endif /* _SLHC_H */
185
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