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1 | #ifndef _SLHC_H |
2 | #define _SLHC_H | |
3 | /* | |
4 | * Definitions for tcp compression routines. | |
5 | * | |
6 | * $Header: slcompress.h,v 1.10 89/12/31 08:53:02 van Exp $ | |
7 | * | |
8 | * Copyright (c) 1989 Regents of the University of California. | |
9 | * All rights reserved. | |
10 | * | |
11 | * Redistribution and use in source and binary forms are permitted | |
12 | * provided that the above copyright notice and this paragraph are | |
13 | * duplicated in all such forms and that any documentation, | |
14 | * advertising materials, and other materials related to such | |
15 | * distribution and use acknowledge that the software was developed | |
16 | * by the University of California, Berkeley. The name of the | |
17 | * University may not be used to endorse or promote products derived | |
18 | * from this software without specific prior written permission. | |
19 | * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR | |
20 | * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED | |
21 | * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. | |
22 | * | |
23 | * Van Jacobson (van@helios.ee.lbl.gov), Dec 31, 1989: | |
24 | * - Initial distribution. | |
25 | * | |
26 | * | |
27 | * modified for KA9Q Internet Software Package by | |
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.umich.edu | |
34 | * variable number of conversation slots | |
35 | * allow zero or one slots | |
36 | * separate routines | |
37 | * status display | |
38 | */ | |
39 | ||
40 | /* | |
41 | * Compressed packet format: | |
42 | * | |
43 | * The first octet contains the packet type (top 3 bits), TCP | |
44 | * 'push' bit, and flags that indicate which of the 4 TCP sequence | |
45 | * numbers have changed (bottom 5 bits). The next octet is a | |
46 | * conversation number that associates a saved IP/TCP header with | |
47 | * the compressed packet. The next two octets are the TCP checksum | |
48 | * from the original datagram. The next 0 to 15 octets are | |
49 | * sequence number changes, one change per bit set in the header | |
50 | * (there may be no changes and there are two special cases where | |
51 | * the receiver implicitly knows what changed -- see below). | |
52 | * | |
53 | * There are 5 numbers which can change (they are always inserted | |
54 | * in the following order): TCP urgent pointer, window, | |
55 | * acknowledgment, sequence number and IP ID. (The urgent pointer | |
56 | * is different from the others in that its value is sent, not the | |
57 | * change in value.) Since typical use of SLIP links is biased | |
58 | * toward small packets (see comments on MTU/MSS below), changes | |
59 | * use a variable length coding with one octet for numbers in the | |
60 | * range 1 - 255 and 3 octets (0, MSB, LSB) for numbers in the | |
61 | * range 256 - 65535 or 0. (If the change in sequence number or | |
62 | * ack is more than 65535, an uncompressed packet is sent.) | |
63 | */ | |
64 | ||
65 | /* | |
66 | * Packet types (must not conflict with IP protocol version) | |
67 | * | |
68 | * The top nibble of the first octet is the packet type. There are | |
69 | * three possible types: IP (not proto TCP or tcp with one of the | |
70 | * control flags set); uncompressed TCP (a normal IP/TCP packet but | |
71 | * with the 8-bit protocol field replaced by an 8-bit connection id -- | |
72 | * this type of packet syncs the sender & receiver); and compressed | |
73 | * TCP (described above). | |
74 | * | |
75 | * LSB of 4-bit field is TCP "PUSH" bit (a worthless anachronism) and | |
76 | * is logically part of the 4-bit "changes" field that follows. Top | |
77 | * three bits are actual packet type. For backward compatibility | |
78 | * and in the interest of conserving bits, numbers are chosen so the | |
79 | * IP protocol version number (4) which normally appears in this nibble | |
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 changed in a packet */ | |
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) /* echoed interactive traffic */ | |
103 | #define SPECIAL_D (NEW_S|NEW_A|NEW_W|NEW_U) /* unidirectional data */ | |
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 generic | |
112 | * u_char byte_t unsigned char 8 bits | |
113 | * u_short int16 unsigned short 16 bits | |
114 | * u_int int16 unsigned short 16 bits | |
115 | * u_long unsigned long unsigned long 32 bits | |
116 | * int int32 long 32 bits | |
117 | */ | |
118 | ||
119 | typedef __u8 byte_t; | |
120 | typedef __u32 int32; | |
121 | ||
122 | /* | |
123 | * "state" data for each active tcp conversation on the wire. This is | |
124 | * basically a copy of the entire IP/TCP header from the last packet | |
125 | * we saw from the conversation together with a small identifier | |
126 | * the transmit & receive ends of the line use to locate saved header. | |
127 | */ | |
128 | struct cstate { | |
129 | byte_t cs_this; /* connection id number (xmit) */ | |
3f01ddb9 | 130 | bool initialized; /* true if initialized */ |
1da177e4 LT |
131 | struct cstate *next; /* next in ring (xmit) */ |
132 | struct iphdr cs_ip; /* ip/tcp hdr from most recent packet */ | |
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 need one of these per line). | |
142 | */ | |
143 | struct slcompress { | |
144 | struct cstate *tstate; /* transmit connection states (array)*/ | |
145 | struct cstate *rstate; /* receive connection states (array)*/ | |
146 | ||
147 | byte_t tslot_limit; /* highest transmit slot id (0-l)*/ | |
148 | byte_t rslot_limit; /* highest receive slot id (0-l)*/ | |
149 | ||
150 | byte_t xmit_oldest; /* oldest xmit in ring */ | |
151 | byte_t xmit_current; /* most recent xmit id */ | |
152 | byte_t recv_current; /* most recent rcvd id */ | |
153 | ||
154 | byte_t flags; | |
155 | #define SLF_TOSS 0x01 /* tossing rcvd frames until id received */ | |
156 | ||
157 | int32 sls_o_nontcp; /* outbound non-TCP packets */ | |
158 | int32 sls_o_tcp; /* outbound TCP packets */ | |
159 | int32 sls_o_uncompressed; /* outbound uncompressed packets */ | |
160 | int32 sls_o_compressed; /* outbound compressed packets */ | |
161 | int32 sls_o_searches; /* searches for connection state */ | |
162 | int32 sls_o_misses; /* times couldn't find conn. state */ | |
163 | ||
164 | int32 sls_i_uncompressed; /* inbound uncompressed packets */ | |
165 | int32 sls_i_compressed; /* inbound compressed packets */ | |
166 | int32 sls_i_error; /* inbound error packets */ | |
167 | int32 sls_i_tossed; /* inbound packets tossed because of error */ | |
168 | ||
169 | int32 sls_i_runt; | |
170 | int32 sls_i_badcheck; | |
171 | }; | |
172 | #define NULLSLCOMPR (struct slcompress *)0 | |
173 | ||
1da177e4 | 174 | /* In slhc.c: */ |
b8259d9a AD |
175 | struct slcompress *slhc_init(int rslots, int tslots); |
176 | void slhc_free(struct slcompress *comp); | |
177 | ||
178 | int slhc_compress(struct slcompress *comp, unsigned char *icp, int isize, | |
179 | unsigned char *ocp, unsigned char **cpp, int compress_cid); | |
180 | int slhc_uncompress(struct slcompress *comp, unsigned char *icp, int isize); | |
181 | int slhc_remember(struct slcompress *comp, unsigned char *icp, int isize); | |
182 | int slhc_toss(struct slcompress *comp); | |
1da177e4 LT |
183 | |
184 | #endif /* _SLHC_H */ |