1 files changed, 87 insertions, 20 deletions

diff --git a/third_party/srtp/crypto/replay/rdbx.c b/third_party/srtp/crypto/replay/rdbx.c
index 12e4e8f8..153676f3 100644
--- a/third_party/srtp/crypto/replay/rdbx.c
+++ b/third_party/srtp/crypto/replay/rdbx.c
@@ -43,20 +43,23 @@
  *
  */
 
+#ifdef HAVE_CONFIG_H
+    #include <config.h>
+#endif
+
 #include "rdbx.h"
 
-#define rdbx_high_bit_in_bitmask 127
 
 /*
- * from draft-ietf-avt-srtp-00.txt:
+ * from RFC 3711:
  *
  * A receiver reconstructs the index i of a packet with sequence
- *  number s using the estimate
+ *  number SEQ using the estimate
  *
- * i = 65,536 * t + s,
+ * i = 2^16 * v + SEQ,
  *
- * where t is chosen from the set { r-1, r, r+1 } such that i is
- * closest to the value 65,536 * r + s_l.  If the value r+1 is used,
+ * where v is chosen from the set { ROC-1, ROC, ROC+1 } such that i is
+ * closest to the value 2^16 * ROC + s_l.  If the value r+1 is used,
  * then the rollover counter r in the cryptographic context is
  * incremented by one (if the packet containing s is authentic).
  */
@@ -146,18 +149,18 @@ index_guess(const xtd_seq_num_t *local,
   if (local_seq < seq_num_median) {
     if (s - local_seq > seq_num_median) {
       guess_roc = local_roc - 1;
-      difference = seq_num_max - s + local_seq;
+      difference = s - local_seq - seq_num_max;
     } else {
       guess_roc = local_roc;
       difference = s - local_seq;
     }
   } else {
     if (local_seq - seq_num_median > s) {
-      guess_roc = local_roc+1;
-      difference = seq_num_max - local_seq + s;
+      guess_roc = local_roc + 1;
+      difference = s - local_seq + seq_num_max;
     } else {
-      difference = s - local_seq;
       guess_roc = local_roc;
+      difference = s - local_seq;
     }
   }
   guess_seq = s;
@@ -180,17 +183,81 @@ index_guess(const xtd_seq_num_t *local,
 
 
 /*
- *  rdbx_init(&r) initalizes the rdbx_t pointed to by r 
+ *  rdbx_init(&r, ws) initializes the rdbx_t pointed to by r with window size ws
  */
 
 err_status_t
-rdbx_init(rdbx_t *rdbx) {
-  v128_set_to_zero(&rdbx->bitmask);
+rdbx_init(rdbx_t *rdbx, unsigned long ws) {
+  if (ws == 0)
+    return err_status_bad_param;
+
+  if (bitvector_alloc(&rdbx->bitmask, ws) != 0)
+    return err_status_alloc_fail;
+
   index_init(&rdbx->index);
 
   return err_status_ok;
 }
 
+/*
+ *  rdbx_dealloc(&r) frees memory for the rdbx_t pointed to by r
+ */
+
+err_status_t
+rdbx_dealloc(rdbx_t *rdbx) {
+  bitvector_dealloc(&rdbx->bitmask);
+
+  return err_status_ok;
+}
+
+/*
+ * 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) {
+  bitvector_set_to_zero(&rdbx->bitmask);
+
+#ifdef NO_64BIT_MATH
+  #error not yet implemented
+#else
+
+  /* make sure that we're not moving backwards */
+  if (roc < (rdbx->index >> 16))
+    return err_status_replay_old;
+
+  rdbx->index &= 0xffff;   /* retain lowest 16 bits */
+  rdbx->index |= ((uint64_t)roc) << 16;  /* set ROC */
+#endif
+
+  return err_status_ok;
+}
+
+/*
+ * rdbx_get_packet_index(rdbx) returns the value of the packet index
+ * for the rdbx_t pointed to by rdbx
+ * 
+ */
+
+xtd_seq_num_t
+rdbx_get_packet_index(const rdbx_t *rdbx) {
+  return rdbx->index;   
+}
+
+/*
+ * rdbx_get_window_size(rdbx) returns the value of the window size
+ * for the rdbx_t pointed to by rdbx
+ * 
+ */
+
+unsigned long
+rdbx_get_window_size(const rdbx_t *rdbx) {
+  return bitvector_get_length(&rdbx->bitmask);
+}
 
 /*
  * rdbx_check(&r, delta) checks to see if the xtd_seq_num_t
@@ -202,11 +269,11 @@ rdbx_check(const rdbx_t *rdbx, int delta) {
   
   if (delta > 0) {       /* if delta is positive, it's good */
     return err_status_ok;
-  } else if (rdbx_high_bit_in_bitmask + delta < 0) {   
+  } else if ((int)(bitvector_get_length(&rdbx->bitmask) - 1) + delta < 0) {   
                          /* if delta is lower than the bitmask, it's bad */
     return err_status_replay_old; 
-  } else if (v128_get_bit(&rdbx->bitmask, 
-			  rdbx_high_bit_in_bitmask + delta) == 1) {
+  } else if (bitvector_get_bit(&rdbx->bitmask, 
+			       (int)(bitvector_get_length(&rdbx->bitmask) - 1) + delta) == 1) {
                          /* delta is within the window, so check the bitmask */
     return err_status_replay_fail;    
   }
@@ -230,11 +297,11 @@ rdbx_add_index(rdbx_t *rdbx, int delta) {
   if (delta > 0) {
     /* shift forward by delta */
     index_advance(&rdbx->index, delta);
-    v128_left_shift(&rdbx->bitmask, delta);
-    v128_set_bit(&rdbx->bitmask, 127);
+    bitvector_left_shift(&rdbx->bitmask, delta);
+    bitvector_set_bit(&rdbx->bitmask, bitvector_get_length(&rdbx->bitmask) - 1);
   } else {
-    /* delta is in window, so flip bit in bitmask */
-    v128_set_bit(&rdbx->bitmask, -delta);
+    /* delta is in window */
+    bitvector_set_bit(&rdbx->bitmask, bitvector_get_length(&rdbx->bitmask) -1 + delta);
   }
 
   /* note that we need not consider the case that delta == 0 */