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 /*

  * rdbx.h

  *

  * replay database with extended packet indices, using a rollover counter

  *

  * David A. McGrew

  * Cisco Systems, Inc.

  *

  */

 /*

  *	

  * Copyright (c) 2001-2006, Cisco Systems, Inc.

  * All rights reserved.

  * 

  * Redistribution and use in source and binary forms, with or without

  * modification, are permitted provided that the following conditions

  * are met:

  * 

  *   Redistributions of source code must retain the above copyright

  *   notice, this list of conditions and the following disclaimer.

  * 

  *   Redistributions in binary form must reproduce the above

  *   copyright notice, this list of conditions and the following

  *   disclaimer in the documentation and/or other materials provided

  *   with the distribution.

  * 

  *   Neither the name of the Cisco Systems, Inc. nor the names of its

  *   contributors may be used to endorse or promote products derived

  *   from this software without specific prior written permission.

  * 

  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS

  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT

  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS

  * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE

  * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,

  * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES

  * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR

  * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)

  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,

  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)

  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED

  * OF THE POSSIBILITY OF SUCH DAMAGE.

  *

  */

 #ifndef RDBX_H

 #define RDBX_H

 #include "datatypes.h"

 #include "err.h"

 /* #define ROC_TEST */  

 #ifndef ROC_TEST

 typedef uint16_t sequence_number_t;   /* 16 bit sequence number  */

 typedef uint32_t rollover_counter_t;   /* 32 bit rollover counter */

 #else  /* use small seq_num and roc datatypes for testing purposes */

 typedef unsigned char sequence_number_t;         /* 8 bit sequence number   */

 typedef uint16_t rollover_counter_t;   /* 16 bit rollover counter */

 #endif

 #define seq_num_median (1 << (8*sizeof(sequence_number_t) - 1))

 #define seq_num_max    (1 << (8*sizeof(sequence_number_t)))

 /*

  * An xtd_seq_num_t is a 64-bit unsigned integer used as an 'extended'

  * sequence number.  

  */

 typedef uint64_t xtd_seq_num_t;

 /*

  * An rdbx_t is a replay database with extended range; it uses an

  * xtd_seq_num_t and a bitmask of recently received indices.

  */

 typedef struct {

   xtd_seq_num_t index;

   bitvector_t bitmask;

 } rdbx_t;

 /*

  * rdbx_init(rdbx_ptr, ws)

  *

  * initializes the rdbx pointed to by its argument with the window size ws,

  * setting the rollover counter and sequence number to zero

  */

 err_status_t

 rdbx_init(rdbx_t *rdbx, unsigned long ws);

 /*

  * rdbx_dealloc(rdbx_ptr)

  *

  * frees memory associated with the rdbx

  */

 err_status_t

 rdbx_dealloc(rdbx_t *rdbx);

 /*

  * rdbx_estimate_index(rdbx, guess, s)

  * 

  * given an rdbx and a sequence number s (from a newly arrived packet),

  * sets the contents of *guess to contain the best guess of the packet

  * index to which s corresponds, and returns the difference between

  * *guess and the locally stored synch info

  */

 int

 rdbx_estimate_index(const rdbx_t *rdbx,

 		    xtd_seq_num_t *guess,

 		    sequence_number_t s);

 /*

  * rdbx_check(rdbx, delta);

  *

  * rdbx_check(&r, delta) checks to see if the xtd_seq_num_t

  * which is at rdbx->window_start + delta is in the rdb

  *

  */

 err_status_t

 rdbx_check(const rdbx_t *rdbx, int difference);

 /*

  * replay_add_index(rdbx, delta)

  * 

  * adds the xtd_seq_num_t at rdbx->window_start + delta to replay_db

  * (and does *not* check if that xtd_seq_num_t appears in db)

  *

  * this function should be called *only* after replay_check has

  * indicated that the index does not appear in the rdbx, and a mutex

  * should protect the rdbx between these calls if necessary.

  */

 err_status_t

 rdbx_add_index(rdbx_t *rdbx, int delta);

 /*

  * rdbx_set_roc(rdbx, roc) initalizes the rdbx_t at the location rdbx

  * to have the rollover counter value roc.  If that value is less than

  * the current rollover counter value, then the function returns

  * err_status_replay_old; otherwise, err_status_ok is returned.

  * 

  */

 err_status_t

 rdbx_set_roc(rdbx_t *rdbx, uint32_t roc);

 /*

  * rdbx_get_roc(rdbx) returns the value of the rollover counter for

  * the rdbx_t pointed to by rdbx

  * 

  */

 xtd_seq_num_t

 rdbx_get_packet_index(const rdbx_t *rdbx);

 /*

  * xtd_seq_num_t functions - these are *internal* functions of rdbx, and

  * shouldn't be used to manipulate rdbx internal values.  use the rdbx

  * api instead!

  */

 /*

  * rdbx_get_ws(rdbx_ptr)

  *

  * gets the window size which was used to initialize the rdbx

  */

 unsigned long

 rdbx_get_window_size(const rdbx_t *rdbx);

 /* index_init(&pi) initializes a packet index pi (sets it to zero) */

 void

 index_init(xtd_seq_num_t *pi);

 /* index_advance(&pi, s) advances a xtd_seq_num_t forward by s */

 void

 index_advance(xtd_seq_num_t *pi, sequence_number_t s);

 /*

  * index_guess(local, guess, s)

  * 

  * given a xtd_seq_num_t local (which represents the highest

  * known-to-be-good index) and a sequence number s (from a newly

  * arrived packet), sets the contents of *guess to contain the best

  * guess of the packet index to which s corresponds, and returns the

  * difference between *guess and *local

  */

 int

 index_guess(const xtd_seq_num_t *local,

 		   xtd_seq_num_t *guess,

 		   sequence_number_t s);

 #endif /* RDBX_H */