First Publicly Shared Version of ODKiTEE v15

oemcrypto_ta/oemcrypto_nonce_table.c

@@ -0,0 +1,81 @@
+/* Copyright 2019 Google LLC. All Rights Reserved. This file and proprietary
+   source code may only be used and distributed under the Widevine Master
+   License Agreement. */
+
+#include "oemcrypto_nonce_table.h"
+
+#include "stddef.h"
+
+#include "assert_interface.h"
+
+void AddNonce(NonceTable* nonce_table, uint32_t nonce) {
+  ASSERT(nonce_table != NULL, "nonce_table is NULL");
+  int new_slot = -1;
+  int oldest_slot = -1;
+
+  /* Flush any nonce_table->nonces that have been checked but not flushed.
+     After flush, nonce_table->nonces will be either valid or invalid. */
+  FlushNonces(nonce_table);
+
+  for (int i = 0; i < NONCE_TABLE_SIZE; i++) {
+    /* Increase nonce_table->age of all valid nonce_table->nonces. */
+    if (nonce_table->state[i] == NT_STATE_VALID) {
+      nonce_table->age[i]++;
+      if (oldest_slot == -1) {
+        oldest_slot = i;
+      } else {
+        if (nonce_table->age[i] > nonce_table->age[oldest_slot]) {
+          oldest_slot = i;
+        }
+      }
+    } else {
+      if (new_slot == -1) {
+        nonce_table->age[i] = 0;
+        nonce_table->nonces[i] = nonce;
+        nonce_table->state[i] = NT_STATE_VALID;
+        new_slot = i;
+      }
+    }
+  }
+  if (new_slot == -1) {
+    /* reuse oldest */
+    ASSERT(oldest_slot != -1, "oldest_slot is -1");
+    int i = oldest_slot;
+    nonce_table->age[i] = 0;
+    nonce_table->nonces[i] = nonce;
+    nonce_table->state[i] = NT_STATE_VALID;
+  }
+}
+
+bool CheckNonce(NonceTable* nonce_table, uint32_t nonce) {
+  ASSERT(nonce_table != NULL, "nonce_table is NULL");
+  for (int i = 0; i < NONCE_TABLE_SIZE; i++) {
+    if (nonce_table->state[i] != NT_STATE_INVALID) {
+      if (nonce_table->nonces[i] == nonce) {
+        nonce_table->state[i] = NT_STATE_FLUSH_PENDING;
+        return true;
+      }
+    }
+  }
+  return false;
+}
+
+bool NonceCollision(NonceTable* nonce_table, uint32_t nonce) {
+  ASSERT(nonce_table != NULL, "nonce_table is NULL");
+  for (int i = 0; i < NONCE_TABLE_SIZE; i++) {
+    if (nonce_table->nonces[i] == nonce &&
+        nonce_table->state[i] != NT_STATE_INVALID) {
+      return true;
+    }
+  }
+  return false;
+}
+
+void FlushNonces(NonceTable* nonce_table) {
+  ASSERT(nonce_table != NULL, "nonce_table is NULL");
+  for (int i = 0; i < NONCE_TABLE_SIZE; i++) {
+    if (nonce_table->state[i] == NT_STATE_FLUSH_PENDING) {
+      nonce_table->state[i] = NT_STATE_INVALID;
+    }
+  }
+}