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1.1 root 1: #ifndef _SLHC_H
2: #define _SLHC_H
3: /*
4: * Definitions for tcp compression routines.
5: *
6: * $Header: /afs/sipb.mit.edu/project/hurddev/cvsroot/gnumach/linux/src/include/net/slhc_vj.h,v 1.1 1999/04/26 05:57:54 tb 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 ([email protected]), Dec 31, 1989:
24: * - Initial distribution.
25: *
26: *
27: * modified for KA9Q Internet Software Package by
28: * Katie Stevens ([email protected])
29: * University of California, Davis
30: * Computing Services
31: * - 01-31-90 initial adaptation
32: *
33: * - Feb 1991 [email protected]
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: /* SLIP compression masks for len/vers byte */
84: #define SL_TYPE_IP 0x40
85: #define SL_TYPE_UNCOMPRESSED_TCP 0x70
86: #define SL_TYPE_COMPRESSED_TCP 0x80
87: #define SL_TYPE_ERROR 0x00
88:
89: /* Bits in first octet of compressed packet */
90: #define NEW_C 0x40 /* flag bits for what changed in a packet */
91: #define NEW_I 0x20
92: #define NEW_S 0x08
93: #define NEW_A 0x04
94: #define NEW_W 0x02
95: #define NEW_U 0x01
96:
97: /* reserved, special-case values of above */
98: #define SPECIAL_I (NEW_S|NEW_W|NEW_U) /* echoed interactive traffic */
99: #define SPECIAL_D (NEW_S|NEW_A|NEW_W|NEW_U) /* unidirectional data */
100: #define SPECIALS_MASK (NEW_S|NEW_A|NEW_W|NEW_U)
101:
102: #define TCP_PUSH_BIT 0x10
103:
104: /*
105: * data type and sizes conversion assumptions:
106: *
107: * VJ code KA9Q style generic
108: * u_char byte_t unsigned char 8 bits
109: * u_short int16 unsigned short 16 bits
110: * u_int int16 unsigned short 16 bits
111: * u_long unsigned long unsigned long 32 bits
112: * int int32 long 32 bits
113: */
114:
115: typedef unsigned char byte_t;
116: typedef unsigned long int32;
117:
118: /*
119: * "state" data for each active tcp conversation on the wire. This is
120: * basically a copy of the entire IP/TCP header from the last packet
121: * we saw from the conversation together with a small identifier
122: * the transmit & receive ends of the line use to locate saved header.
123: */
124: struct cstate {
125: byte_t cs_this; /* connection id number (xmit) */
126: struct cstate *next; /* next in ring (xmit) */
127: struct iphdr cs_ip; /* ip/tcp hdr from most recent packet */
128: struct tcphdr cs_tcp;
129: unsigned char cs_ipopt[64];
130: unsigned char cs_tcpopt[64];
131: int cs_hsize;
132: };
133: #define NULLSLSTATE (struct cstate *)0
134:
135: /*
136: * all the state data for one serial line (we need one of these per line).
137: */
138: struct slcompress {
139: struct cstate *tstate; /* transmit connection states (array)*/
140: struct cstate *rstate; /* receive connection states (array)*/
141:
142: byte_t tslot_limit; /* highest transmit slot id (0-l)*/
143: byte_t rslot_limit; /* highest receive slot id (0-l)*/
144:
145: byte_t xmit_oldest; /* oldest xmit in ring */
146: byte_t xmit_current; /* most recent xmit id */
147: byte_t recv_current; /* most recent rcvd id */
148:
149: byte_t flags;
150: #define SLF_TOSS 0x01 /* tossing rcvd frames until id received */
151:
152: int32 sls_o_nontcp; /* outbound non-TCP packets */
153: int32 sls_o_tcp; /* outbound TCP packets */
154: int32 sls_o_uncompressed; /* outbound uncompressed packets */
155: int32 sls_o_compressed; /* outbound compressed packets */
156: int32 sls_o_searches; /* searches for connection state */
157: int32 sls_o_misses; /* times couldn't find conn. state */
158:
159: int32 sls_i_uncompressed; /* inbound uncompressed packets */
160: int32 sls_i_compressed; /* inbound compressed packets */
161: int32 sls_i_error; /* inbound error packets */
162: int32 sls_i_tossed; /* inbound packets tossed because of error */
163:
164: int32 sls_i_runt;
165: int32 sls_i_badcheck;
166: };
167: #define NULLSLCOMPR (struct slcompress *)0
168:
169: #define __ARGS(x) x
170:
171: /* In slhc.c: */
172: struct slcompress *slhc_init __ARGS((int rslots, int tslots));
173: void slhc_free __ARGS((struct slcompress *comp));
174:
175: int slhc_compress __ARGS((struct slcompress *comp, unsigned char *icp,
176: int isize, unsigned char *ocp, unsigned char **cpp,
177: int compress_cid));
178: int slhc_uncompress __ARGS((struct slcompress *comp, unsigned char *icp,
179: int isize));
180: int slhc_remember __ARGS((struct slcompress *comp, unsigned char *icp,
181: int isize));
182: int slhc_toss __ARGS((struct slcompress *comp));
183:
184: void slhc_i_status __ARGS((struct slcompress *comp));
185: void slhc_o_status __ARGS((struct slcompress *comp));
186:
187: #endif /* _SLHC_H */
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