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 #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 */ 162