- Added simple SSL session cache implementation

- Revamped session resumption handling

library/ssl_cache.c

@@ -0,0 +1,152 @@
+/*
+ *  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.
+ */
+/*
+ * These session callbacks use a simple chained list
+ * to store and retrieve the session information.
+ */
+
+#include "polarssl/config.h"
+
+#if defined(POLARSSL_SSL_CACHE_C)
+
+#include "polarssl/ssl_cache.h"
+
+#include <stdlib.h>
+
+void ssl_cache_init( ssl_cache_context *cache )
+{
+    memset( cache, 0, sizeof( ssl_cache_context ) );
+
+    cache->timeout = SSL_CACHE_DEFAULT_TIMEOUT;
+}
+
+int ssl_cache_get( void *data, ssl_session *session )
+{
+    time_t t = time( NULL );
+    ssl_cache_context *cache = (ssl_cache_context *) data;
+    ssl_cache_entry *cur, *entry;
+
+    cur = cache->chain;
+    entry = NULL;
+
+    while( cur != NULL )
+    {
+        entry = cur;
+        cur = cur->next;
+
+        if( cache->timeout != 0 &&
+            (int) ( t - entry->timestamp ) > cache->timeout )
+            continue;
+
+        if( session->ciphersuite != entry->session.ciphersuite ||
+            session->compression != entry->session.compression ||
+            session->length != entry->session.length )
+            continue;
+
+        if( memcmp( session->id, entry->session.id,
+                    entry->session.length ) != 0 )
+            continue;
+
+        memcpy( session->master, entry->session.master, 48 );
+        return( 0 );
+    }
+
+    return( 1 );
+}
+
+int ssl_cache_set( void *data, const ssl_session *session )
+{
+    time_t t = time( NULL );
+    ssl_cache_context *cache = (ssl_cache_context *) data;
+    ssl_cache_entry *cur, *prv;
+
+    cur = cache->chain;
+    prv = NULL;
+
+    while( cur != NULL )
+    {
+        if( cache->timeout != 0 &&
+            (int) ( t - cur->timestamp ) > cache->timeout )
+        {
+            cur->timestamp = t;
+            break; /* expired, reuse this slot, update timestamp */
+        }
+
+        if( memcmp( session->id, cur->session.id, cur->session.length ) == 0 )
+            break; /* client reconnected, keep timestamp for session id */
+
+        prv = cur;
+        cur = cur->next;
+    }
+
+    if( cur == NULL )
+    {
+        cur = (ssl_cache_entry *) malloc( sizeof( ssl_cache_entry ) );
+        if( cur == NULL )
+            return( 1 );
+
+        memset( cur, 0, sizeof( ssl_cache_entry ) );
+
+        if( prv == NULL )
+            cache->chain = cur;
+        else
+            prv->next = cur;
+
+        cur->timestamp = t;
+    }
+
+    memcpy( &cur->session, session, sizeof( ssl_session ) );
+    
+    // Do not include peer_cert in cache entry
+    //
+    cur->session.peer_cert = NULL;
+
+    return( 0 );
+}
+
+void ssl_cache_set_timeout( ssl_cache_context *cache, int timeout )
+{
+    if( timeout < 0 ) timeout = 0;
+
+    cache->timeout = timeout;
+}
+
+void ssl_cache_free( ssl_cache_context *cache )
+{
+    ssl_cache_entry *cur, *prv;
+
+    cur = cache->chain;
+
+    while( cur != NULL )
+    {
+        prv = cur;
+        cur = cur->next;
+
+        ssl_session_free( &prv->session );
+        free( prv );
+    }
+}
+
+#endif /* POLARSSL_SSL_CACHE_C */