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 #ifndef RDBX_H 12 #define RDBX_H 13 14 #include "datatypes.h" 15 #include "err.h" 16 17 /* #define ROC_TEST */ 18 19 #ifndef ROC_TEST 20 21 typedef uint16_t sequence_number_t; /* 16 bit sequence number */ 22 typedef uint32_t rollover_counter_t; /* 32 bit rollover counter */ 23 24 #else /* use small seq_num and roc datatypes for testing purposes */ 25 26 typedef unsigned char sequence_number_t; /* 8 bit sequence number */ 27 typedef uint16_t rollover_counter_t; /* 16 bit rollover counter */ 28 29 #endif 30 31 #define seq_num_median (1 << (8*sizeof(sequence_number_t) - 1)) 32 #define seq_num_max (1 << (8*sizeof(sequence_number_t))) 33 34 /* 35 * An xtd_seq_num_t is a 64-bit unsigned integer used as an 'extended' 36 * sequence number. 37 */ 38 39 typedef uint64_t xtd_seq_num_t; 40 41 42 /* 43 * An rdbx_t is a replay database with extended range; it uses an 44 * xtd_seq_num_t and a bitmask of recently received indices. 45 */ 46 47 typedef struct { 48 xtd_seq_num_t index; 49 bitvector_t bitmask; 50 } rdbx_t; 51 52 53 /* 54 * rdbx_init(rdbx_ptr, ws) 55 * 56 * initializes the rdbx pointed to by its argument with the window size ws, 57 * setting the rollover counter and sequence number to zero 58 */ 59 60 err_status_t 61 rdbx_init(rdbx_t *rdbx, unsigned long ws); 62 63 64 /* 65 * rdbx_uninit(rdbx_ptr) 66 * 67 * frees memory associated with the rdbx 68 */ 69 70 err_status_t 71 rdbx_uninit(rdbx_t *rdbx); 72 73 74 /* 75 * rdbx_estimate_index(rdbx, guess, s) 76 * 77 * given an rdbx and a sequence number s (from a newly arrived packet), 78 * sets the contents of *guess to contain the best guess of the packet 79 * index to which s corresponds, and returns the difference between 80 * *guess and the locally stored synch info 81 */ 82 83 int 84 rdbx_estimate_index(const rdbx_t *rdbx, 85 xtd_seq_num_t *guess, 86 sequence_number_t s); 87 88 /* 89 * rdbx_check(rdbx, delta); 90 * 91 * rdbx_check(&r, delta) checks to see if the xtd_seq_num_t 92 * which is at rdbx->window_start + delta is in the rdb 93 * 94 */ 95 96 err_status_t 97 rdbx_check(const rdbx_t *rdbx, int difference); 98 99 /* 100 * replay_add_index(rdbx, delta) 101 * 102 * adds the xtd_seq_num_t at rdbx->window_start + delta to replay_db 103 * (and does *not* check if that xtd_seq_num_t appears in db) 104 * 105 * this function should be called *only* after replay_check has 106 * indicated that the index does not appear in the rdbx, and a mutex 107 * should protect the rdbx between these calls if necessary. 108 */ 109 110 err_status_t 111 rdbx_add_index(rdbx_t *rdbx, int delta); 112 113 114 /* 115 * rdbx_set_roc(rdbx, roc) initalizes the rdbx_t at the location rdbx 116 * to have the rollover counter value roc. If that value is less than 117 * the current rollover counter value, then the function returns 118 * err_status_replay_old; otherwise, err_status_ok is returned. 119 * 120 */ 121 122 err_status_t 123 rdbx_set_roc(rdbx_t *rdbx, uint32_t roc); 124 125 /* 126 * rdbx_get_roc(rdbx) returns the value of the rollover counter for 127 * the rdbx_t pointed to by rdbx 128 * 129 */ 130 131 xtd_seq_num_t 132 rdbx_get_packet_index(const rdbx_t *rdbx); 133 134 /* 135 * xtd_seq_num_t functions - these are *internal* functions of rdbx, and 136 * shouldn't be used to manipulate rdbx internal values. use the rdbx 137 * api instead! 138 */ 139 140 /* 141 * rdbx_get_ws(rdbx_ptr) 142 * 143 * gets the window size which was used to initialize the rdbx 144 */ 145 146 unsigned long 147 rdbx_get_window_size(const rdbx_t *rdbx); 148 149 150 /* index_init(&pi) initializes a packet index pi (sets it to zero) */ 151 152 void 153 index_init(xtd_seq_num_t *pi); 154 155 /* index_advance(&pi, s) advances a xtd_seq_num_t forward by s */ 156 157 void 158 index_advance(xtd_seq_num_t *pi, sequence_number_t s); 159 160 161 /* 162 * index_guess(local, guess, s) 163 * 164 * given a xtd_seq_num_t local (which represents the highest 165 * known-to-be-good index) and a sequence number s (from a newly 166 * arrived packet), sets the contents of *guess to contain the best 167 * guess of the packet index to which s corresponds, and returns the 168 * difference between *guess and *local 169 */ 170 171 int 172 index_guess(const xtd_seq_num_t *local, 173 xtd_seq_num_t *guess, 174 sequence_number_t s); 175 176 177 #endif /* RDBX_H */ 178 179 180 181 182 183 184 185 186 187