Loading...
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 | #ifndef _SLHC_H #define _SLHC_H /* * Definitions for tcp compression routines. * * $Header: slcompress.h,v 1.10 89/12/31 08:53:02 van Exp $ * * Copyright (c) 1989 Regents of the University of California. * All rights reserved. * * Redistribution and use in source and binary forms are permitted * provided that the above copyright notice and this paragraph are * duplicated in all such forms and that any documentation, * advertising materials, and other materials related to such * distribution and use acknowledge that the software was developed * by the University of California, Berkeley. The name of the * University may not be used to endorse or promote products derived * from this software without specific prior written permission. * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. * * Van Jacobson (van@helios.ee.lbl.gov), Dec 31, 1989: * - Initial distribution. * * * modified for KA9Q Internet Software Package by * Katie Stevens (dkstevens@ucdavis.edu) * University of California, Davis * Computing Services * - 01-31-90 initial adaptation * * - Feb 1991 Bill_Simpson@um.cc.umich.edu * variable number of conversation slots * allow zero or one slots * separate routines * status display */ /* * Compressed packet format: * * The first octet contains the packet type (top 3 bits), TCP * 'push' bit, and flags that indicate which of the 4 TCP sequence * numbers have changed (bottom 5 bits). The next octet is a * conversation number that associates a saved IP/TCP header with * the compressed packet. The next two octets are the TCP checksum * from the original datagram. The next 0 to 15 octets are * sequence number changes, one change per bit set in the header * (there may be no changes and there are two special cases where * the receiver implicitly knows what changed -- see below). * * There are 5 numbers which can change (they are always inserted * in the following order): TCP urgent pointer, window, * acknowledgment, sequence number and IP ID. (The urgent pointer * is different from the others in that its value is sent, not the * change in value.) Since typical use of SLIP links is biased * toward small packets (see comments on MTU/MSS below), changes * use a variable length coding with one octet for numbers in the * range 1 - 255 and 3 octets (0, MSB, LSB) for numbers in the * range 256 - 65535 or 0. (If the change in sequence number or * ack is more than 65535, an uncompressed packet is sent.) */ /* * Packet types (must not conflict with IP protocol version) * * The top nibble of the first octet is the packet type. There are * three possible types: IP (not proto TCP or tcp with one of the * control flags set); uncompressed TCP (a normal IP/TCP packet but * with the 8-bit protocol field replaced by an 8-bit connection id -- * this type of packet syncs the sender & receiver); and compressed * TCP (described above). * * LSB of 4-bit field is TCP "PUSH" bit (a worthless anachronism) and * is logically part of the 4-bit "changes" field that follows. Top * three bits are actual packet type. For backward compatibility * and in the interest of conserving bits, numbers are chosen so the * IP protocol version number (4) which normally appears in this nibble * means "IP packet". */ /* SLIP compression masks for len/vers byte */ #define SL_TYPE_IP 0x40 #define SL_TYPE_UNCOMPRESSED_TCP 0x70 #define SL_TYPE_COMPRESSED_TCP 0x80 #define SL_TYPE_ERROR 0x00 /* Bits in first octet of compressed packet */ #define NEW_C 0x40 /* flag bits for what changed in a packet */ #define NEW_I 0x20 #define NEW_S 0x08 #define NEW_A 0x04 #define NEW_W 0x02 #define NEW_U 0x01 /* reserved, special-case values of above */ #define SPECIAL_I (NEW_S|NEW_W|NEW_U) /* echoed interactive traffic */ #define SPECIAL_D (NEW_S|NEW_A|NEW_W|NEW_U) /* unidirectional data */ #define SPECIALS_MASK (NEW_S|NEW_A|NEW_W|NEW_U) #define TCP_PUSH_BIT 0x10 /* * data type and sizes conversion assumptions: * * VJ code KA9Q style generic * u_char byte_t unsigned char 8 bits * u_short int16 unsigned short 16 bits * u_int int16 unsigned short 16 bits * u_long unsigned long unsigned long 32 bits * int int32 long 32 bits */ typedef __u8 byte_t; typedef __u32 int32; /* * "state" data for each active tcp conversation on the wire. This is * basically a copy of the entire IP/TCP header from the last packet * we saw from the conversation together with a small identifier * the transmit & receive ends of the line use to locate saved header. */ struct cstate { byte_t cs_this; /* connection id number (xmit) */ struct cstate *next; /* next in ring (xmit) */ struct iphdr cs_ip; /* ip/tcp hdr from most recent packet */ struct tcphdr cs_tcp; unsigned char cs_ipopt[64]; unsigned char cs_tcpopt[64]; int cs_hsize; }; #define NULLSLSTATE (struct cstate *)0 /* * all the state data for one serial line (we need one of these per line). */ struct slcompress { struct cstate *tstate; /* transmit connection states (array)*/ struct cstate *rstate; /* receive connection states (array)*/ byte_t tslot_limit; /* highest transmit slot id (0-l)*/ byte_t rslot_limit; /* highest receive slot id (0-l)*/ byte_t xmit_oldest; /* oldest xmit in ring */ byte_t xmit_current; /* most recent xmit id */ byte_t recv_current; /* most recent rcvd id */ byte_t flags; #define SLF_TOSS 0x01 /* tossing rcvd frames until id received */ int32 sls_o_nontcp; /* outbound non-TCP packets */ int32 sls_o_tcp; /* outbound TCP packets */ int32 sls_o_uncompressed; /* outbound uncompressed packets */ int32 sls_o_compressed; /* outbound compressed packets */ int32 sls_o_searches; /* searches for connection state */ int32 sls_o_misses; /* times couldn't find conn. state */ int32 sls_i_uncompressed; /* inbound uncompressed packets */ int32 sls_i_compressed; /* inbound compressed packets */ int32 sls_i_error; /* inbound error packets */ int32 sls_i_tossed; /* inbound packets tossed because of error */ int32 sls_i_runt; int32 sls_i_badcheck; }; #define NULLSLCOMPR (struct slcompress *)0 #define __ARGS(x) x /* In slhc.c: */ struct slcompress *slhc_init __ARGS((int rslots, int tslots)); void slhc_free __ARGS((struct slcompress *comp)); int slhc_compress __ARGS((struct slcompress *comp, unsigned char *icp, int isize, unsigned char *ocp, unsigned char **cpp, int compress_cid)); int slhc_uncompress __ARGS((struct slcompress *comp, unsigned char *icp, int isize)); int slhc_remember __ARGS((struct slcompress *comp, unsigned char *icp, int isize)); int slhc_toss __ARGS((struct slcompress *comp)); void slhc_i_status __ARGS((struct slcompress *comp)); void slhc_o_status __ARGS((struct slcompress *comp)); #endif /* _SLHC_H */ |