UbixOS V2 2.0

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 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 #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 "net/ip.h"
32 #include "net/priv/tcp_priv.h"
33
34 #define MAX_SLOTS 16 /* must be > 2 and < 256 */
35 #define MAX_HDR 128
36
37 /*
38 * Compressed packet format:
39 *
40 * The first octet contains the packet type (top 3 bits), TCP
41 * 'push' bit, and flags that indicate which of the 4 TCP sequence
42 * numbers have changed (bottom 5 bits). The next octet is a
43 * conversation number that associates a saved IP/TCP header with
44 * the compressed packet. The next two octets are the TCP checksum
45 * from the original datagram. The next 0 to 15 octets are
46 * sequence number changes, one change per bit set in the header
47 * (there may be no changes and there are two special cases where
48 * the receiver implicitly knows what changed -- see below).
49 *
50 * There are 5 numbers which can change (they are always inserted
51 * in the following order): TCP urgent pointer, window,
52 * acknowlegement, sequence number and IP ID. (The urgent pointer
53 * is different from the others in that its value is sent, not the
54 * change in value.) Since typical use of SLIP links is biased
55 * toward small packets (see comments on MTU/MSS below), changes
56 * use a variable length coding with one octet for numbers in the
57 * range 1 - 255 and 3 octets (0, MSB, LSB) for numbers in the
58 * range 256 - 65535 or 0. (If the change in sequence number or
59 * ack is more than 65535, an uncompressed packet is sent.)
60 */
61
62 /*
63 * Packet types (must not conflict with IP protocol version)
64 *
65 * The top nibble of the first octet is the packet type. There are
66 * three possible types: IP (not proto TCP or tcp with one of the
67 * control flags set); uncompressed TCP (a normal IP/TCP packet but
68 * with the 8-bit protocol field replaced by an 8-bit connection id --
69 * this type of packet syncs the sender & receiver); and compressed
70 * TCP (described above).
71 *
72 * LSB of 4-bit field is TCP "PUSH" bit (a worthless anachronism) and
73 * is logically part of the 4-bit "changes" field that follows. Top
74 * three bits are actual packet type. For backward compatibility
75 * and in the interest of conserving bits, numbers are chosen so the
76 * IP protocol version number (4) which normally appears in this nibble
77 * means "IP packet".
78 */
79
80 /* packet types */
81 #define TYPE_IP 0x40
82 #define TYPE_UNCOMPRESSED_TCP 0x70
83 #define TYPE_COMPRESSED_TCP 0x80
84 #define TYPE_ERROR 0x00
85
86 /* Bits in first octet of compressed packet */
87 #define NEW_C 0x40 /* flag bits for what changed in a packet */
88 #define NEW_I 0x20
89 #define NEW_S 0x08
90 #define NEW_A 0x04
91 #define NEW_W 0x02
92 #define NEW_U 0x01
93
94 /* reserved, special-case values of above */
95 #define SPECIAL_I (NEW_S|NEW_W|NEW_U) /* echoed interactive traffic */
96 #define SPECIAL_D (NEW_S|NEW_A|NEW_W|NEW_U) /* unidirectional data */
97 #define SPECIALS_MASK (NEW_S|NEW_A|NEW_W|NEW_U)
98
99 #define TCP_PUSH_BIT 0x10
100
101
102 /*
103 * "state" data for each active tcp conversation on the wire. This is
104 * basically a copy of the entire IP/TCP header from the last packet
105 * we saw from the conversation together with a small identifier
106 * the transmit & receive ends of the line use to locate saved header.
107 */
108 struct cstate {
109 struct cstate *cs_next; /* next most recently used state (xmit only) */
110 u16_t cs_hlen; /* size of hdr (receive only) */
111 u8_t cs_id; /* connection # associated with this state */
112 u8_t cs_filler;
113 union {
114 char csu_hdr[MAX_HDR];
115 struct ip_hdr csu_ip; /* ip/tcp hdr from most recent packet */
116 } vjcs_u;
117 };
118 #define cs_ip vjcs_u.csu_ip
119 #define cs_hdr vjcs_u.csu_hdr
120
121
122 struct vjstat {
123 u32_t vjs_packets; /* outbound packets */
124 u32_t vjs_compressed; /* outbound compressed packets */
125 u32_t vjs_searches; /* searches for connection state */
126 u32_t vjs_misses; /* times couldn't find conn. state */
127 u32_t vjs_uncompressedin; /* inbound uncompressed packets */
128 u32_t vjs_compressedin; /* inbound compressed packets */
129 u32_t vjs_errorin; /* inbound unknown type packets */
130 u32_t vjs_tossed; /* inbound packets tossed because of error */
131 };
132
133 /*
134 * all the state data for one serial line (we need one of these per line).
135 */
136 struct vjcompress {
137 struct cstate *last_cs; /* most recently used tstate */
138 u8_t last_recv; /* last rcvd conn. id */
139 u8_t last_xmit; /* last sent conn. id */
140 u16_t flags;
141 u8_t maxSlotIndex;
142 u8_t compressSlot; /* Flag indicating OK to compress slot ID. */
143 #if LINK_STATS
144 struct vjstat stats;
145 #endif
146 struct cstate tstate[MAX_SLOTS]; /* xmit connection states */
147 struct cstate rstate[MAX_SLOTS]; /* receive connection states */
148 };
149
150 /* flag values */
151 #define VJF_TOSS 1U /* tossing rcvd frames because of input err */
152
153 extern void vj_compress_init (struct vjcompress *comp);
154 extern u8_t vj_compress_tcp (struct vjcompress *comp, struct pbuf **pb);
155 extern void vj_uncompress_err (struct vjcompress *comp);
156 extern int vj_uncompress_uncomp(struct pbuf *nb, struct vjcompress *comp);
157 extern int vj_uncompress_tcp (struct pbuf **nb, struct vjcompress *comp);
158
159 #endif /* VJ_H */
160
161 #endif /* PPP_SUPPORT && VJ_SUPPORT */
u16_t
uint16_t u16_t
Definition: arch.h:124
u32_t
uint32_t u32_t
Definition: arch.h:126
ip_hdr
Definition: ip4.h:71
u8_t
uint8_t u8_t
Definition: arch.h:122
tcp_priv.h
ip.h
ppp_opts.h
pbuf
Definition: pbuf.h:142