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 "lwip/ip.h" 32 #include "lwip/priv/tcp_priv.h" 33 34 #ifdef __cplusplus 35 extern "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 */ 112 struct 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 124 125 126 struct 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 */ 140 struct 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 */ 156 157 extern void vj_compress_init (struct vjcompress *comp); 158 extern u8_t vj_compress_tcp (struct vjcompress *comp, struct pbuf **pb); 159 extern void vj_uncompress_err (struct vjcompress *comp); 160 extern int vj_uncompress_uncomp(struct pbuf *nb, struct vjcompress *comp); 161 extern 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 */ 170