- Added simple SSL session cache implementation

- Revamped session resumption handling

include/polarssl/ssl_cache.h

@@ -0,0 +1,105 @@
+/**
+ * \file ssl_cache.h
+ *
+ * \brief SSL session cache implementation
+ *
+ *  Copyright (C) 2006-2012, Brainspark B.V.
+ *
+ *  This file is part of PolarSSL (http://www.polarssl.org)
+ *  Lead Maintainer: Paul Bakker <polarssl_maintainer at polarssl.org>
+ *
+ *  All rights reserved.
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 2 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+#ifndef POLARSSL_SSL_CACHE_H
+#define POLARSSL_SSL_CACHE_H
+
+#include "ssl.h"
+
+#define SSL_CACHE_DEFAULT_TIMEOUT 86400 /*!< 1 day  */
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+typedef struct _ssl_cache_context ssl_cache_context;
+typedef struct _ssl_cache_entry ssl_cache_entry;
+
+/**
+ * \brief   This structure is used for storing cache entries
+ */
+struct _ssl_cache_entry
+{
+    time_t timestamp;           /*!< entry timestamp    */
+    ssl_session session;        /*!< entry session      */
+    ssl_cache_entry *next;      /*!< chain pointer      */
+};
+
+/**
+ * \brief Cache context
+ */
+struct _ssl_cache_context
+{
+    ssl_cache_entry *chain;     /*!< start of the chain */
+    int timeout;                /*!< cache timeout      */
+};
+
+/**
+ * \brief          Initialize an SSL cache context
+ *
+ * \param cache    SSL cache context
+ */
+void ssl_cache_init( ssl_cache_context *cache );
+
+/**
+ * \brief          Cache get callback implementation
+ *
+ * \param data     SSL cache context
+ * \param session  session to retrieve entry for
+ */
+int ssl_cache_get( void *data, ssl_session *session );
+
+/**
+ * \brief          Cache set callback implementation
+ *
+ * \param data     SSL cache context
+ * \param session  session to store entry for
+ */
+int ssl_cache_set( void *data, const ssl_session *session );
+
+/**
+ * \brief          Set the cache timeout
+ *                 (Default: SSL_CACHE_DEFAULT_TIMEOUT (1 day))
+ *
+ *                 A timeout of 0 indicates no timeout.
+ *
+ * \param cache    SSL cache context
+ * \param timeout  cache entry timeout
+ */
+void ssl_cache_set_timeout( ssl_cache_context *cache, int timeout );
+
+/**
+ * \brief          Free referenced items in a cache context and clear memory
+ *
+ * \param cache    SSL cache context
+ */
+void ssl_cache_free( ssl_cache_context *cache );
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* ssl_cache.h */