ReactOS 0.4.16-dev-297-gc569aee
vj.h
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1/*
2 * Definitions for tcp compression routines.
3 *
4 * $Id: vj.h,v 1.7 2010/02/22 17:52:09 goldsimon Exp $
5 *
6 * Copyright (c) 1989 Regents of the University of California.
7 * All rights reserved.
8 *
9 * Redistribution and use in source and binary forms are permitted
10 * provided that the above copyright notice and this paragraph are
11 * duplicated in all such forms and that any documentation,
12 * advertising materials, and other materials related to such
13 * distribution and use acknowledge that the software was developed
14 * by the University of California, Berkeley. The name of the
15 * University may not be used to endorse or promote products derived
16 * from this software without specific prior written permission.
17 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
18 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
19 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
20 *
21 * Van Jacobson (van@helios.ee.lbl.gov), Dec 31, 1989:
22 * - Initial distribution.
23 */
24
25#include "netif/ppp/ppp_opts.h"
26#if PPP_SUPPORT && VJ_SUPPORT /* don't build if not configured for use in lwipopts.h */
27
28#ifndef VJ_H
29#define VJ_H
30
31#include "lwip/ip.h"
32#include "lwip/priv/tcp_priv.h"
33
34#ifdef __cplusplus
35extern "C" {
36#endif
37
38#define MAX_SLOTS 16 /* must be > 2 and < 256 */
39#define MAX_HDR 128
40
41/*
42 * Compressed packet format:
43 *
44 * The first octet contains the packet type (top 3 bits), TCP
45 * 'push' bit, and flags that indicate which of the 4 TCP sequence
46 * numbers have changed (bottom 5 bits). The next octet is a
47 * conversation number that associates a saved IP/TCP header with
48 * the compressed packet. The next two octets are the TCP checksum
49 * from the original datagram. The next 0 to 15 octets are
50 * sequence number changes, one change per bit set in the header
51 * (there may be no changes and there are two special cases where
52 * the receiver implicitly knows what changed -- see below).
53 *
54 * There are 5 numbers which can change (they are always inserted
55 * in the following order): TCP urgent pointer, window,
56 * acknowlegement, sequence number and IP ID. (The urgent pointer
57 * is different from the others in that its value is sent, not the
58 * change in value.) Since typical use of SLIP links is biased
59 * toward small packets (see comments on MTU/MSS below), changes
60 * use a variable length coding with one octet for numbers in the
61 * range 1 - 255 and 3 octets (0, MSB, LSB) for numbers in the
62 * range 256 - 65535 or 0. (If the change in sequence number or
63 * ack is more than 65535, an uncompressed packet is sent.)
64 */
65
66/*
67 * Packet types (must not conflict with IP protocol version)
68 *
69 * The top nibble of the first octet is the packet type. There are
70 * three possible types: IP (not proto TCP or tcp with one of the
71 * control flags set); uncompressed TCP (a normal IP/TCP packet but
72 * with the 8-bit protocol field replaced by an 8-bit connection id --
73 * this type of packet syncs the sender & receiver); and compressed
74 * TCP (described above).
75 *
76 * LSB of 4-bit field is TCP "PUSH" bit (a worthless anachronism) and
77 * is logically part of the 4-bit "changes" field that follows. Top
78 * three bits are actual packet type. For backward compatibility
79 * and in the interest of conserving bits, numbers are chosen so the
80 * IP protocol version number (4) which normally appears in this nibble
81 * means "IP packet".
82 */
83
84/* packet types */
85#define TYPE_IP 0x40
86#define TYPE_UNCOMPRESSED_TCP 0x70
87#define TYPE_COMPRESSED_TCP 0x80
88#define TYPE_ERROR 0x00
89
90/* Bits in first octet of compressed packet */
91#define NEW_C 0x40 /* flag bits for what changed in a packet */
92#define NEW_I 0x20
93#define NEW_S 0x08
94#define NEW_A 0x04
95#define NEW_W 0x02
96#define NEW_U 0x01
97
98/* reserved, special-case values of above */
99#define SPECIAL_I (NEW_S|NEW_W|NEW_U) /* echoed interactive traffic */
100#define SPECIAL_D (NEW_S|NEW_A|NEW_W|NEW_U) /* unidirectional data */
101#define SPECIALS_MASK (NEW_S|NEW_A|NEW_W|NEW_U)
102
103#define TCP_PUSH_BIT 0x10
104
105
106/*
107 * "state" data for each active tcp conversation on the wire. This is
108 * basically a copy of the entire IP/TCP header from the last packet
109 * we saw from the conversation together with a small identifier
110 * the transmit & receive ends of the line use to locate saved header.
111 */
112struct cstate {
113 struct cstate *cs_next; /* next most recently used state (xmit only) */
114 u16_t cs_hlen; /* size of hdr (receive only) */
115 u8_t cs_id; /* connection # associated with this state */
116 u8_t cs_filler;
117 union {
118 char csu_hdr[MAX_HDR];
119 struct ip_hdr csu_ip; /* ip/tcp hdr from most recent packet */
120 } vjcs_u;
121};
122#define cs_ip vjcs_u.csu_ip
123#define cs_hdr vjcs_u.csu_hdr
124
125
126struct vjstat {
127 u32_t vjs_packets; /* outbound packets */
128 u32_t vjs_compressed; /* outbound compressed packets */
129 u32_t vjs_searches; /* searches for connection state */
130 u32_t vjs_misses; /* times couldn't find conn. state */
131 u32_t vjs_uncompressedin; /* inbound uncompressed packets */
132 u32_t vjs_compressedin; /* inbound compressed packets */
133 u32_t vjs_errorin; /* inbound unknown type packets */
134 u32_t vjs_tossed; /* inbound packets tossed because of error */
135};
136
137/*
138 * all the state data for one serial line (we need one of these per line).
139 */
140struct vjcompress {
141 struct cstate *last_cs; /* most recently used tstate */
142 u8_t last_recv; /* last rcvd conn. id */
143 u8_t last_xmit; /* last sent conn. id */
144 u16_t flags;
145 u8_t maxSlotIndex;
146 u8_t compressSlot; /* Flag indicating OK to compress slot ID. */
147#if LINK_STATS
148 struct vjstat stats;
149#endif
150 struct cstate tstate[MAX_SLOTS]; /* xmit connection states */
151 struct cstate rstate[MAX_SLOTS]; /* receive connection states */
152};
153
154/* flag values */
155#define VJF_TOSS 1U /* tossing rcvd frames because of input err */
156
157extern void vj_compress_init (struct vjcompress *comp);
158extern u8_t vj_compress_tcp (struct vjcompress *comp, struct pbuf **pb);
159extern void vj_uncompress_err (struct vjcompress *comp);
160extern int vj_uncompress_uncomp(struct pbuf *nb, struct vjcompress *comp);
161extern int vj_uncompress_tcp (struct pbuf **nb, struct vjcompress *comp);
162
163#ifdef __cplusplus
164}
165#endif
166
167#endif /* VJ_H */
168
169#endif /* PPP_SUPPORT && VJ_SUPPORT */
GLbitfield flags
Definition: glext.h:7161
uint32_t u32_t
Definition: arch.h:129
uint8_t u8_t
Definition: arch.h:125
uint16_t u16_t
Definition: arch.h:127
Definition: ip4.h:73
Definition: pbuf.h:186