Refactor code structure for improved readability and maintainability

libsrtp/crypto/kernel/key.c

@@ -0,0 +1,90 @@
+/*
+ * key.c
+ *
+ * key usage limits enforcement
+ *
+ * David A. Mcgrew
+ * Cisco Systems, Inc.
+ */
+/*
+ *
+ * Copyright (c) 2001-2017 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.
+ *
+ */
+
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+
+#include "key.h"
+
+#define soft_limit 0x10000
+
+srtp_err_status_t srtp_key_limit_set(srtp_key_limit_t key,
+                                     const srtp_xtd_seq_num_t s)
+{
+    if (s < soft_limit) {
+        return srtp_err_status_bad_param;
+    }
+    key->num_left = s;
+    key->state = srtp_key_state_normal;
+    return srtp_err_status_ok;
+}
+
+srtp_err_status_t srtp_key_limit_clone(srtp_key_limit_t original,
+                                       srtp_key_limit_t *new_key)
+{
+    if (original == NULL) {
+        return srtp_err_status_bad_param;
+    }
+    *new_key = original;
+    return srtp_err_status_ok;
+}
+
+srtp_key_event_t srtp_key_limit_update(srtp_key_limit_t key)
+{
+    key->num_left--;
+    if (key->num_left >= soft_limit) {
+        return srtp_key_event_normal; /* we're above the soft limit */
+    }
+    if (key->state == srtp_key_state_normal) {
+        /* we just passed the soft limit, so change the state */
+        key->state = srtp_key_state_past_soft_limit;
+    }
+    if (key->num_left < 1) {
+        /* we just hit the hard limit */
+        key->state = srtp_key_state_expired;
+        return srtp_key_event_hard_limit;
+    }
+    return srtp_key_event_soft_limit;
+}