[TCPIP]
[reactos.git] / reactos / lib / drivers / lwip / src / netif / ppp / vj.h
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 MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
20 *
21 * Van Jacobson (van@helios.ee.lbl.gov), Dec 31, 1989:
22 * - Initial distribution.
23 */
24
25 #ifndef VJ_H
26 #define VJ_H
27
28 #include "lwip/ip.h"
29 #include "lwip/tcp_impl.h"
30
31 #define MAX_SLOTS 16 /* must be > 2 and < 256 */
32 #define MAX_HDR 128
33
34 /*
35 * Compressed packet format:
36 *
37 * The first octet contains the packet type (top 3 bits), TCP
38 * 'push' bit, and flags that indicate which of the 4 TCP sequence
39 * numbers have changed (bottom 5 bits). The next octet is a
40 * conversation number that associates a saved IP/TCP header with
41 * the compressed packet. The next two octets are the TCP checksum
42 * from the original datagram. The next 0 to 15 octets are
43 * sequence number changes, one change per bit set in the header
44 * (there may be no changes and there are two special cases where
45 * the receiver implicitly knows what changed -- see below).
46 *
47 * There are 5 numbers which can change (they are always inserted
48 * in the following order): TCP urgent pointer, window,
49 * acknowlegement, sequence number and IP ID. (The urgent pointer
50 * is different from the others in that its value is sent, not the
51 * change in value.) Since typical use of SLIP links is biased
52 * toward small packets (see comments on MTU/MSS below), changes
53 * use a variable length coding with one octet for numbers in the
54 * range 1 - 255 and 3 octets (0, MSB, LSB) for numbers in the
55 * range 256 - 65535 or 0. (If the change in sequence number or
56 * ack is more than 65535, an uncompressed packet is sent.)
57 */
58
59 /*
60 * Packet types (must not conflict with IP protocol version)
61 *
62 * The top nibble of the first octet is the packet type. There are
63 * three possible types: IP (not proto TCP or tcp with one of the
64 * control flags set); uncompressed TCP (a normal IP/TCP packet but
65 * with the 8-bit protocol field replaced by an 8-bit connection id --
66 * this type of packet syncs the sender & receiver); and compressed
67 * TCP (described above).
68 *
69 * LSB of 4-bit field is TCP "PUSH" bit (a worthless anachronism) and
70 * is logically part of the 4-bit "changes" field that follows. Top
71 * three bits are actual packet type. For backward compatibility
72 * and in the interest of conserving bits, numbers are chosen so the
73 * IP protocol version number (4) which normally appears in this nibble
74 * means "IP packet".
75 */
76
77 /* packet types */
78 #define TYPE_IP 0x40
79 #define TYPE_UNCOMPRESSED_TCP 0x70
80 #define TYPE_COMPRESSED_TCP 0x80
81 #define TYPE_ERROR 0x00
82
83 /* Bits in first octet of compressed packet */
84 #define NEW_C 0x40 /* flag bits for what changed in a packet */
85 #define NEW_I 0x20
86 #define NEW_S 0x08
87 #define NEW_A 0x04
88 #define NEW_W 0x02
89 #define NEW_U 0x01
90
91 /* reserved, special-case values of above */
92 #define SPECIAL_I (NEW_S|NEW_W|NEW_U) /* echoed interactive traffic */
93 #define SPECIAL_D (NEW_S|NEW_A|NEW_W|NEW_U) /* unidirectional data */
94 #define SPECIALS_MASK (NEW_S|NEW_A|NEW_W|NEW_U)
95
96 #define TCP_PUSH_BIT 0x10
97
98
99 /*
100 * "state" data for each active tcp conversation on the wire. This is
101 * basically a copy of the entire IP/TCP header from the last packet
102 * we saw from the conversation together with a small identifier
103 * the transmit & receive ends of the line use to locate saved header.
104 */
105 struct cstate {
106 struct cstate *cs_next; /* next most recently used state (xmit only) */
107 u_short cs_hlen; /* size of hdr (receive only) */
108 u_char cs_id; /* connection # associated with this state */
109 u_char cs_filler;
110 union {
111 char csu_hdr[MAX_HDR];
112 struct ip_hdr csu_ip; /* ip/tcp hdr from most recent packet */
113 } vjcs_u;
114 };
115 #define cs_ip vjcs_u.csu_ip
116 #define cs_hdr vjcs_u.csu_hdr
117
118
119 struct vjstat {
120 unsigned long vjs_packets; /* outbound packets */
121 unsigned long vjs_compressed; /* outbound compressed packets */
122 unsigned long vjs_searches; /* searches for connection state */
123 unsigned long vjs_misses; /* times couldn't find conn. state */
124 unsigned long vjs_uncompressedin; /* inbound uncompressed packets */
125 unsigned long vjs_compressedin; /* inbound compressed packets */
126 unsigned long vjs_errorin; /* inbound unknown type packets */
127 unsigned long vjs_tossed; /* inbound packets tossed because of error */
128 };
129
130 /*
131 * all the state data for one serial line (we need one of these per line).
132 */
133 struct vjcompress {
134 struct cstate *last_cs; /* most recently used tstate */
135 u_char last_recv; /* last rcvd conn. id */
136 u_char last_xmit; /* last sent conn. id */
137 u_short flags;
138 u_char maxSlotIndex;
139 u_char compressSlot; /* Flag indicating OK to compress slot ID. */
140 #if LINK_STATS
141 struct vjstat stats;
142 #endif
143 struct cstate tstate[MAX_SLOTS]; /* xmit connection states */
144 struct cstate rstate[MAX_SLOTS]; /* receive connection states */
145 };
146
147 /* flag values */
148 #define VJF_TOSS 1U /* tossing rcvd frames because of input err */
149
150 extern void vj_compress_init (struct vjcompress *comp);
151 extern u_int vj_compress_tcp (struct vjcompress *comp, struct pbuf *pb);
152 extern void vj_uncompress_err (struct vjcompress *comp);
153 extern int vj_uncompress_uncomp(struct pbuf *nb, struct vjcompress *comp);
154 extern int vj_uncompress_tcp (struct pbuf **nb, struct vjcompress *comp);
155
156 #endif /* VJ_H */