Add current version of libSRTP from CVS.

libsrtp/crypto/include/rdbx.h

+/*
+ * rdbx.h
+ *
+ * replay database with extended packet indices, using a rollover counter
+ *
+ * David A. McGrew
+ * Cisco Systems, Inc.
+ *
+ */
+
+#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 */
+
+
+
+
+
+
+
+
+