Index: libsrtp/crypto/include/rdbx.h |
=================================================================== |
--- libsrtp/crypto/include/rdbx.h (revision 0) |
+++ libsrtp/crypto/include/rdbx.h (revision 0) |
@@ -0,0 +1,186 @@ |
+/* |
+ * 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 */ |
+ |
+ |
+ |
+ |
+ |
+ |
+ |
+ |
+ |
Property changes on: libsrtp/crypto/include/rdbx.h |
___________________________________________________________________ |
Added: svn:eol-style |
+ LF |