1 /* 2 * rdbx.h 3 * 4 * replay database with extended packet indices, using a rollover counter 5 * 6 * David A. McGrew 7 * Cisco Systems, Inc. 8 * 9 */ 10 /* 11 * 12 * Copyright (c) 2001-2006, Cisco Systems, Inc. 13 * All rights reserved. 14 * 15 * Redistribution and use in source and binary forms, with or without 16 * modification, are permitted provided that the following conditions 17 * are met: 18 * 19 * Redistributions of source code must retain the above copyright 20 * notice, this list of conditions and the following disclaimer. 21 * 22 * Redistributions in binary form must reproduce the above 23 * copyright notice, this list of conditions and the following 24 * disclaimer in the documentation and/or other materials provided 25 * with the distribution. 26 * 27 * Neither the name of the Cisco Systems, Inc. nor the names of its 28 * contributors may be used to endorse or promote products derived 29 * from this software without specific prior written permission. 30 * 31 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 32 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 33 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS 34 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 35 * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, 36 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES 37 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR 38 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 39 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, 40 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 41 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED 42 * OF THE POSSIBILITY OF SUCH DAMAGE. 43 * 44 */ 45 46 #ifndef RDBX_H 47 #define RDBX_H 48 49 #include "datatypes.h" 50 #include "err.h" 51 52 /* #define ROC_TEST */ 53 54 #ifndef ROC_TEST 55 56 typedef uint16_t sequence_number_t; /* 16 bit sequence number */ 57 typedef uint32_t rollover_counter_t; /* 32 bit rollover counter */ 58 59 #else /* use small seq_num and roc datatypes for testing purposes */ 60 61 typedef unsigned char sequence_number_t; /* 8 bit sequence number */ 62 typedef uint16_t rollover_counter_t; /* 16 bit rollover counter */ 63 64 #endif 65 66 #define seq_num_median (1 << (8*sizeof(sequence_number_t) - 1)) 67 #define seq_num_max (1 << (8*sizeof(sequence_number_t))) 68 69 /* 70 * An xtd_seq_num_t is a 64-bit unsigned integer used as an 'extended' 71 * sequence number. 72 */ 73 74 typedef uint64_t xtd_seq_num_t; 75 76 77 /* 78 * An rdbx_t is a replay database with extended range; it uses an 79 * xtd_seq_num_t and a bitmask of recently received indices. 80 */ 81 82 typedef struct { 83 xtd_seq_num_t index; 84 bitvector_t bitmask; 85 } rdbx_t; 86 87 88 /* 89 * rdbx_init(rdbx_ptr, ws) 90 * 91 * initializes the rdbx pointed to by its argument with the window size ws, 92 * setting the rollover counter and sequence number to zero 93 */ 94 95 err_status_t 96 rdbx_init(rdbx_t *rdbx, unsigned long ws); 97 98 99 /* 100 * rdbx_dealloc(rdbx_ptr) 101 * 102 * frees memory associated with the rdbx 103 */ 104 105 err_status_t 106 rdbx_dealloc(rdbx_t *rdbx); 107 108 109 /* 110 * rdbx_estimate_index(rdbx, guess, s) 111 * 112 * given an rdbx and a sequence number s (from a newly arrived packet), 113 * sets the contents of *guess to contain the best guess of the packet 114 * index to which s corresponds, and returns the difference between 115 * *guess and the locally stored synch info 116 */ 117 118 int 119 rdbx_estimate_index(const rdbx_t *rdbx, 120 xtd_seq_num_t *guess, 121 sequence_number_t s); 122 123 /* 124 * rdbx_check(rdbx, delta); 125 * 126 * rdbx_check(&r, delta) checks to see if the xtd_seq_num_t 127 * which is at rdbx->window_start + delta is in the rdb 128 * 129 */ 130 131 err_status_t 132 rdbx_check(const rdbx_t *rdbx, int difference); 133 134 /* 135 * replay_add_index(rdbx, delta) 136 * 137 * adds the xtd_seq_num_t at rdbx->window_start + delta to replay_db 138 * (and does *not* check if that xtd_seq_num_t appears in db) 139 * 140 * this function should be called *only* after replay_check has 141 * indicated that the index does not appear in the rdbx, and a mutex 142 * should protect the rdbx between these calls if necessary. 143 */ 144 145 err_status_t 146 rdbx_add_index(rdbx_t *rdbx, int delta); 147 148 149 /* 150 * rdbx_set_roc(rdbx, roc) initalizes the rdbx_t at the location rdbx 151 * to have the rollover counter value roc. If that value is less than 152 * the current rollover counter value, then the function returns 153 * err_status_replay_old; otherwise, err_status_ok is returned. 154 * 155 */ 156 157 err_status_t 158 rdbx_set_roc(rdbx_t *rdbx, uint32_t roc); 159 160 /* 161 * rdbx_get_roc(rdbx) returns the value of the rollover counter for 162 * the rdbx_t pointed to by rdbx 163 * 164 */ 165 166 xtd_seq_num_t 167 rdbx_get_packet_index(const rdbx_t *rdbx); 168 169 /* 170 * xtd_seq_num_t functions - these are *internal* functions of rdbx, and 171 * shouldn't be used to manipulate rdbx internal values. use the rdbx 172 * api instead! 173 */ 174 175 /* 176 * rdbx_get_ws(rdbx_ptr) 177 * 178 * gets the window size which was used to initialize the rdbx 179 */ 180 181 unsigned long 182 rdbx_get_window_size(const rdbx_t *rdbx); 183 184 185 /* index_init(&pi) initializes a packet index pi (sets it to zero) */ 186 187 void 188 index_init(xtd_seq_num_t *pi); 189 190 /* index_advance(&pi, s) advances a xtd_seq_num_t forward by s */ 191 192 void 193 index_advance(xtd_seq_num_t *pi, sequence_number_t s); 194 195 196 /* 197 * index_guess(local, guess, s) 198 * 199 * given a xtd_seq_num_t local (which represents the highest 200 * known-to-be-good index) and a sequence number s (from a newly 201 * arrived packet), sets the contents of *guess to contain the best 202 * guess of the packet index to which s corresponds, and returns the 203 * difference between *guess and *local 204 */ 205 206 int 207 index_guess(const xtd_seq_num_t *local, 208 xtd_seq_num_t *guess, 209 sequence_number_t s); 210 211 212 #endif /* RDBX_H */ 213 214 215 216 217 218 219 220 221 222
