- Added simple SSL session cache implementation

- Revamped session resumption handling

ChangeLog

@@ -26,6 +26,7 @@ Features
    * Added PKCS#5 PBKDF2 key derivation function
    * Added Secure Renegotiation (RFC 5746)
    * Added predefined DHM groups from RFC 5114
+   * Added simple SSL session cache implementation
 
 Changes
    * Removed redundant POLARSSL_DEBUG_MSG define
@@ -38,6 +39,7 @@ Changes
    * Cipher layer cipher_mode_t POLARSSL_MODE_CFB128 is renamed to
      POLARSSL_MODE_CFB, to also handle different block size CFB modes.
    * Removed handling for SSLv2 Client Hello (as per RFC 5246 recommendation)
+   * Revamped session resumption handling
 
 Bugfix
    * Fixed handling error in mpi_cmp_mpi() on longer B values (found by

include/polarssl/config.h

@@ -3,7 +3,7 @@
  *
  * \brief Configuration options (set of defines)
  *
- *  Copyright (C) 2006-2011, Brainspark B.V.
+ *  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>
@@ -683,6 +683,18 @@
  */
 #define POLARSSL_SHA4_C
 
+/**
+ * \def POLARSSL_SSL_CACHE_C
+ *
+ * Enable simple SSL cache implementation.
+ *
+ * Module:  library/ssl_cache.c
+ * Caller:
+ *
+ * Requires: POLARSSL_SSL_CACHE_C
+ */
+#define POLARSSL_SSL_CACHE_C
+
 /**
  * \def POLARSSL_SSL_CLI_C
  *

include/polarssl/ssl.h

@@ -284,7 +284,7 @@ typedef struct _ssl_transform ssl_transform;
 typedef struct _ssl_handshake_params ssl_handshake_params;
 
 /*
- * This structure is used for session resuming.
+ * This structure is used for storing current session data.
  */
 struct _ssl_session
 {
@@ -295,7 +295,6 @@ struct _ssl_session
     unsigned char id[32];       /*!< session identifier */
     unsigned char master[48];   /*!< the master secret  */
     x509_cert *peer_cert;       /*!< peer X.509 cert chain */
-    ssl_session *next;          /*!< next session entry */
 };
 
 /*
@@ -362,6 +361,8 @@ struct _ssl_handshake_params
 
     unsigned char randbytes[64];        /*!<  random bytes            */
     unsigned char premaster[256];       /*!<  premaster secret        */
+
+    int resume;                         /*!<  session resume indicator*/
 };
 
 struct _ssl_context
@@ -386,24 +387,24 @@ struct _ssl_context
     int (*f_recv)(void *, unsigned char *, size_t);
     int (*f_send)(void *, const unsigned char *, size_t);
     int (*f_vrfy)(void *, x509_cert *, int, int);
+    int (*f_get_cache)(void *, ssl_session *);
+    int (*f_set_cache)(void *, const ssl_session *);
 
     void *p_rng;                /*!< context for the RNG function     */
     void *p_dbg;                /*!< context for the debug function   */
     void *p_recv;               /*!< context for reading operations   */
     void *p_send;               /*!< context for writing operations   */
     void *p_vrfy;               /*!< context for verification         */
+    void *p_get_cache;          /*!< context for cache retrieval      */
+    void *p_set_cache;          /*!< context for cache store          */
 
     /*
      * Session layer
      */
-    int resume;                         /*!<  session resuming flag   */
-    int timeout;                        /*!<  sess. expiration time   */
     ssl_session *session_in;            /*!<  current session data (in)   */
     ssl_session *session_out;           /*!<  current session data (out)  */
     ssl_session *session;               /*!<  negotiated session data     */
     ssl_session *session_negotiate;     /*!<  session data in negotiation */
-    int (*s_get)(ssl_context *);        /*!<  (server) get callback   */
-    int (*s_set)(ssl_context *);        /*!<  (server) set callback   */
 
     ssl_handshake_params *handshake;    /*!<  params required only during
                                               the handshake process        */
@@ -636,26 +637,59 @@ void ssl_set_bio( ssl_context *ssl,
         int (*f_send)(void *, const unsigned char *, size_t), void *p_send );
 
 /**
- * \brief          Set the session callbacks (server-side only)
+ * \brief          Set the session cache callbacks (server-side only)
+ *                 If not set, no session resuming is done.
+ *
+ *                 The session cache has the responsibility to check for stale
+ *                 entries based on timeout. See RFC 5246 for recommendations.
+ *
+ *                 Warning: session.peer_cert is cleared by the SSL/TLS layer on
+ *                 connection shutdown, so do not cache the pointer! Either set
+ *                 it to NULL or make a full copy of the certificate.
+ *
+ *                 The get callback is called once during the initial handshake
+ *                 to enable session resuming. The get function has the
+ *                 following parameters: (void *parameter, ssl_session *session)
+ *                 If a valid entry is found, it should fill the master of
+ *                 the session object with the cached values and return 0,
+ *                 return 1 otherwise. Optionally peer_cert can be set as well
+ *                 if it is properly present in cache entry.
+ *
+ *                 The set callback is called once during the initial handshake
+ *                 to enable session resuming after the entire handshake has
+ *                 been finished. The set function has the following parameters:
+ *                 (void *parameter, const ssl_session *session). The function
+ *                 should create a cache entry for future retrieval based on
+ *                 the data in the session structure and should keep in mind
+ *                 that the ssl_session object presented (and all its referenced
+ *                 data) is cleared by the SSL/TLS layer when the connection is
+ *                 terminated. It is recommended to add metadata to determine if
+ *                 an entry is still valid in the future. Return 0 if
+ *                 successfully cached, return 0 otherwise.
  *
  * \param ssl            SSL context
- * \param s_get    session get callback
+ * \param f_get_cache    session get callback
- * \param s_set    session set callback
+ * \param p_get_cache    session get parameter
+ * \param f_set_cache    session set callback
+ * \param p_set_cache    session set parameter
  */
-void ssl_set_scb( ssl_context *ssl,
+void ssl_set_session_cache( ssl_context *ssl,
-                  int (*s_get)(ssl_context *),
+        int (*f_get_cache)(void *, ssl_session *), void *p_get_cache,
-                  int (*s_set)(ssl_context *) );
+        int (*f_set_cache)(void *, const ssl_session *), void *p_set_cache );
 
 /**
- * \brief          Set the session resuming flag, timeout and data
+ * \brief          Request resumption of session (client-side only)
+ *                 Session data is copied from presented session structure.
+ *
+ *                 Warning: session.peer_cert is cleared by the SSL/TLS layer on
+ *                 connection shutdown, so do not cache the pointer! Either set
+ *                 it to NULL or make a full copy of the certificate when
+ *                 storing the session for use in this function.
  *
  * \param ssl      SSL context
- * \param resume   if 0 (default), the session will not be resumed
- * \param timeout  session timeout in seconds, or 0 (no timeout)
  * \param session  session context
  */
-void ssl_set_session( ssl_context *ssl, int resume, int timeout,
+void ssl_set_session( ssl_context *ssl, const ssl_session *session );
-                      ssl_session *session );
 
 /**
  * \brief               Set the list of allowed ciphersuites
@@ -900,8 +934,8 @@ int ssl_close_notify( ssl_context *ssl );
 void ssl_free( ssl_context *ssl );
 
 /**
- * \brief          Free referenced items in an SSL session and free all
+ * \brief          Free referenced items in an SSL session including the
- *                 sessions in the chain. Memory is cleared
+ *                 peer certificate and clear memory
  *
  * \param session  SSL session
  */

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 */

library/CMakeLists.txt

@@ -35,6 +35,7 @@ set(src
      sha1.c
      sha2.c
      sha4.c
+     ssl_cache.c
      ssl_cli.c 
      ssl_srv.c 
      ssl_tls.c

library/Makefile

@@ -44,11 +44,11 @@ OBJS=	aes.o		arc4.o		asn1parse.o		\
 		padlock.o	pbkdf2.o	pem.o			\
 		pkcs11.o								\
 		rsa.o		sha1.o		sha2.o			\
-		sha4.o		ssl_cli.o	ssl_srv.o		\
+		sha4.o		ssl_cache.o	ssl_cli.o		\
+		ssl_srv.o								\
 		ssl_tls.o	timing.o	version.o		\
 		x509parse.o	x509write.o	xtea.o
 
-
 .SILENT:
 
 all: static

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 */

library/ssl_cli.c

@@ -111,9 +111,8 @@ static int ssl_write_client_hello( ssl_context *ssl )
      */
     n = ssl->session_negotiate->length;
 
-    if( n < 16 || n > 32 || ssl->resume == 0 ||
+    if( ssl->renegotiation != SSL_INITIAL_HANDSHAKE || n < 16 || n > 32 ||
-        ( ssl->timeout != 0 &&
+        ssl->handshake->resume == 0 )
-          t - ssl->session_negotiate->start > ssl->timeout ) )
         n = 0;
 
     *p++ = (unsigned char) n;
@@ -473,14 +472,15 @@ static int ssl_parse_server_hello( ssl_context *ssl )
     /*
      * Check if the session can be resumed
      */
-    if( ssl->resume == 0 || n == 0 ||
+    if( ssl->renegotiation != SSL_INITIAL_HANDSHAKE ||
+        ssl->handshake->resume == 0 || n == 0 ||
         ssl->session_negotiate->ciphersuite != i ||
         ssl->session_negotiate->compression != comp ||
         ssl->session_negotiate->length != n ||
         memcmp( ssl->session_negotiate->id, buf + 39, n ) != 0 )
     {
         ssl->state++;
-        ssl->resume = 0;
+        ssl->handshake->resume = 0;
         ssl->session_negotiate->start = time( NULL );
         ssl->session_negotiate->ciphersuite = i;
         ssl->session_negotiate->compression = comp;
@@ -499,7 +499,7 @@ static int ssl_parse_server_hello( ssl_context *ssl )
     }
 
     SSL_DEBUG_MSG( 3, ( "%s session has been resumed",
-                   ssl->resume ? "a" : "no" ) );
+                   ssl->handshake->resume ? "a" : "no" ) );
 
     SSL_DEBUG_MSG( 3, ( "server hello, chosen ciphersuite: %d", i ) );
     SSL_DEBUG_MSG( 3, ( "server hello, compress alg.: %d", buf[41 + n] ) );

library/ssl_srv.c

@@ -456,21 +456,16 @@ static int ssl_write_server_hello( ssl_context *ssl )
     ssl->session_negotiate->length = n = 32;
     *p++ = (unsigned char) ssl->session_negotiate->length;
 
-    if( ssl->s_get == NULL ||
+    if( ssl->renegotiation != SSL_INITIAL_HANDSHAKE ||
-        ssl->s_get( ssl ) != 0 )
+        ssl->f_get_cache == NULL ||
+        ssl->f_get_cache( ssl->p_get_cache, ssl->session_negotiate ) != 0 )
     {
         /*
          * Not found, create a new session id
          */
-        ssl->resume = 0;
+        ssl->handshake->resume = 0;
         ssl->state++;
 
-        if( ssl->session_negotiate == NULL )
-        {
-            SSL_DEBUG_MSG( 1, ( "No session struct set" ) );
-            return( POLARSSL_ERR_SSL_BAD_INPUT_DATA );
-        }
-
         if( ( ret = ssl->f_rng( ssl->p_rng, ssl->session_negotiate->id,
                                 n ) ) != 0 )
             return( ret );
@@ -478,9 +473,9 @@ static int ssl_write_server_hello( ssl_context *ssl )
     else
     {
         /*
-         * Found a matching session, resume it
+         * Found a matching session, resuming it
          */
-        ssl->resume = 1;
+        ssl->handshake->resume = 1;
         ssl->state = SSL_SERVER_CHANGE_CIPHER_SPEC;
 
         if( ( ret = ssl_derive_keys( ssl ) ) != 0 )
@@ -496,7 +491,7 @@ static int ssl_write_server_hello( ssl_context *ssl )
     SSL_DEBUG_MSG( 3, ( "server hello, session id len.: %d", n ) );
     SSL_DEBUG_BUF( 3,   "server hello, session id", buf + 39, n );
     SSL_DEBUG_MSG( 3, ( "%s session has been resumed",
-                   ssl->resume ? "a" : "no" ) );
+                   ssl->handshake->resume ? "a" : "no" ) );
 
     *p++ = (unsigned char)( ssl->session_negotiate->ciphersuite >> 8 );
     *p++ = (unsigned char)( ssl->session_negotiate->ciphersuite      );
@@ -987,9 +982,6 @@ static int ssl_parse_client_key_exchange( ssl_context *ssl )
         return( ret );
     }
 
-    if( ssl->s_set != NULL )
-        ssl->s_set( ssl );
-
     ssl->state++;
 
     SSL_DEBUG_MSG( 2, ( "<= parse client key exchange" ) );

library/ssl_tls.c

@@ -317,7 +317,7 @@ int ssl_derive_keys( ssl_context *ssl )
      * TLSv1:
      *   master = PRF( premaster, "master secret", randbytes )[0..47]
      */
-    if( ssl->resume == 0 )
+    if( handshake->resume == 0 )
     {
         SSL_DEBUG_BUF( 3, "premaster secret", handshake->premaster,
                        handshake->pmslen );
@@ -2641,25 +2641,21 @@ void ssl_handshake_wrapup( ssl_context *ssl )
     ssl->transform = ssl->transform_negotiate;
     ssl->transform_negotiate = NULL;
 
-    /*
+    if( ssl->session )
-     * Migrate data to existing session structure (in chain)
+    {
-     * Step 1. Clear existing data (but not the rest of the chain)
-     * Step 2. Migrate data to existing object in chain
-     * Step 3. Remove negotiation session object without removing items pointed
-     *         to
-     */
-    ssl->session_negotiate->next = ssl->session->next;
-    ssl->session->next = NULL;
         ssl_session_free( ssl->session );
-
+        free( ssl->session );
-    memcpy( ssl->session, ssl->session_negotiate, sizeof(ssl_session) );
+    }
-    ssl->session_in = ssl->session;
+    ssl->session = ssl->session_negotiate;
-    ssl->session_out = ssl->session;
-
-    memset( ssl->session_negotiate, 0, sizeof(ssl_session) );
-    free( ssl->session_negotiate );
     ssl->session_negotiate = NULL;
 
+    /*
+     * Add cache entry
+     */
+    if( ssl->f_set_cache != NULL )
+        if( ssl->f_set_cache( ssl->p_set_cache, ssl->session ) != 0 )
+            SSL_DEBUG_MSG( 1, ( "cache did not store session" ) );
+
     ssl->state++;
 
     SSL_DEBUG_MSG( 3, ( "<= handshake wrapup" ) );
@@ -2687,7 +2683,7 @@ int ssl_write_finished( ssl_context *ssl )
      * In case of session resuming, invert the client and server
      * ChangeCipherSpec messages order.
      */
-    if( ssl->resume != 0 )
+    if( ssl->handshake->resume != 0 )
     {
         if( ssl->endpoint == SSL_IS_CLIENT )
             ssl->state = SSL_HANDSHAKE_WRAPUP;
@@ -2765,7 +2761,7 @@ int ssl_parse_finished( ssl_context *ssl )
     ssl->verify_data_len = hash_len;
     memcpy( ssl->peer_verify_data, buf, hash_len );
 
-    if( ssl->resume != 0 )
+    if( ssl->handshake->resume != 0 )
     {
         if( ssl->endpoint == SSL_IS_CLIENT )
             ssl->state = SSL_CLIENT_CHANGE_CIPHER_SPEC;
@@ -2970,20 +2966,20 @@ void ssl_set_bio( ssl_context *ssl,
     ssl->p_send     = p_send;
 }
 
-void ssl_set_scb( ssl_context *ssl,
+void ssl_set_session_cache( ssl_context *ssl,
-                  int (*s_get)(ssl_context *),
+        int (*f_get_cache)(void *, ssl_session *), void *p_get_cache,
-                  int (*s_set)(ssl_context *) )
+        int (*f_set_cache)(void *, const ssl_session *), void *p_set_cache )
 {
-    ssl->s_get      = s_get;
+    ssl->f_get_cache = f_get_cache;
-    ssl->s_set      = s_set;
+    ssl->p_get_cache = p_get_cache;
+    ssl->f_set_cache = f_set_cache;
+    ssl->p_set_cache = p_set_cache;
 }
 
-void ssl_set_session( ssl_context *ssl, int resume, int timeout,
+void ssl_set_session( ssl_context *ssl, const ssl_session *session )
-                      ssl_session *session )
 {
-    ssl->resume     = resume;
+    memcpy( ssl->session_negotiate, session, sizeof(ssl_session) );
-    ssl->timeout    = timeout;
+    ssl->handshake->resume = 1;
-    ssl->session    = session;
 }
 
 void ssl_set_ciphersuites( ssl_context *ssl, const int *ciphersuites )
@@ -3687,23 +3683,13 @@ void ssl_handshake_free( ssl_handshake_params *handshake )
 
 void ssl_session_free( ssl_session *session )
 {
-    ssl_session *cur = session, *prv;
+    if( session->peer_cert != NULL )
-
-    while( cur != NULL )
     {
-        prv = cur;
+        x509_free( session->peer_cert );
-        cur = cur->next;
+        free( session->peer_cert );
-
-        if( prv->peer_cert != NULL )
-        {
-            x509_free( prv->peer_cert );
-            free( prv->peer_cert );
     }
 
-        memset( prv, 0, sizeof( ssl_session ) );
+    memset( session, 0, sizeof( ssl_session ) );
-        if( prv != session )
-            free( prv );
-    }
 }
 
 /*

programs/ssl/ssl_client1.c

@@ -78,7 +78,6 @@ int main( int argc, char *argv[] )
     entropy_context entropy;
     ctr_drbg_context ctr_drbg;
     ssl_context ssl;
-    ssl_session ssn;
 
     ((void) argc);
     ((void) argv);
@@ -86,7 +85,6 @@ int main( int argc, char *argv[] )
     /*
      * 0. Initialize the RNG and the session data
      */
-    memset( &ssn, 0, sizeof( ssl_session ) );
     memset( &ssl, 0, sizeof( ssl_context ) );
 
     printf( "\n  . Seeding the random number generator..." );
@@ -141,7 +139,6 @@ int main( int argc, char *argv[] )
                        net_send, &server_fd );
 
     ssl_set_ciphersuites( &ssl, ssl_default_ciphersuites );
-    ssl_set_session( &ssl, 1, 600, &ssn );
 
     /*
      * 3. Write the GET request

programs/ssl/ssl_client2.c

@@ -131,7 +131,6 @@ int main( int argc, char *argv[] )
     entropy_context entropy;
     ctr_drbg_context ctr_drbg;
     ssl_context ssl;
-    ssl_session ssn;
     x509_cert cacert;
     x509_cert clicert;
     rsa_context rsa;
@@ -144,7 +143,6 @@ int main( int argc, char *argv[] )
      * Make sure memory references are valid.
      */
     server_fd = 0;
-    memset( &ssn, 0, sizeof( ssl_session ) );
     memset( &ssl, 0, sizeof( ssl_context ) );
     memset( &cacert, 0, sizeof( x509_cert ) );
     memset( &clicert, 0, sizeof( x509_cert ) );
@@ -389,8 +387,6 @@ int main( int argc, char *argv[] )
     ssl_set_renegotiation( &ssl, opt.renegotiation );
     ssl_legacy_renegotiation( &ssl, opt.allow_legacy );
 
-    ssl_set_session( &ssl, 1, 600, &ssn );
-
     ssl_set_ca_chain( &ssl, &cacert, NULL, opt.server_name );
     ssl_set_own_cert( &ssl, &clicert, &rsa );
 
@@ -518,7 +514,6 @@ exit:
     x509_free( &clicert );
     x509_free( &cacert );
     rsa_free( &rsa );
-    ssl_session_free( &ssn );
     ssl_free( &ssl );
 
     memset( &ssl, 0, sizeof( ssl ) );

programs/ssl/ssl_fork_server.c

@@ -126,80 +126,6 @@ void my_debug( void *ctx, int level, const char *str )
     }
 }
 
-/*
- * These session callbacks use a simple chained list
- * to store and retrieve the session information.
- */
-ssl_session *s_list_1st = NULL;
-ssl_session *cur, *prv;
-
-static int my_get_session( ssl_context *ssl )
-{
-    time_t t = time( NULL );
-
-    if( ssl->resume == 0 )
-        return( 1 );
-
-    cur = s_list_1st;
-    prv = NULL;
-
-    while( cur != NULL )
-    {
-        prv = cur;
-        cur = cur->next;
-
-        if( ssl->timeout != 0 && t - prv->start > ssl->timeout )
-            continue;
-
-        if( ssl->session->ciphersuite != prv->ciphersuite ||
-            ssl->session->length != prv->length )
-            continue;
-
-        if( memcmp( ssl->session->id, prv->id, prv->length ) != 0 )
-            continue;
-
-        memcpy( ssl->session->master, prv->master, 48 );
-        return( 0 );
-    }
-
-    return( 1 );
-}
-
-static int my_set_session( ssl_context *ssl )
-{
-    time_t t = time( NULL );
-
-    cur = s_list_1st;
-    prv = NULL;
-
-    while( cur != NULL )
-    {
-        if( ssl->timeout != 0 && t - cur->start > ssl->timeout )
-            break; /* expired, reuse this slot */
-
-        if( memcmp( ssl->session->id, cur->id, cur->length ) == 0 )
-            break; /* client reconnected */
-
-        prv = cur;
-        cur = cur->next;
-    }
-
-    if( cur == NULL )
-    {
-        cur = (ssl_session *) malloc( sizeof( ssl_session ) );
-        if( cur == NULL )
-            return( 1 );
-
-        if( prv == NULL )
-              s_list_1st = cur;
-        else  prv->next  = cur;
-    }
-
-    memcpy( cur, ssl->session, sizeof( ssl_session ) );
-
-    return( 0 );
-}
-
 int main( int argc, char *argv[] )
 {
     int ret, len, cnt = 0, pid;
@@ -211,7 +137,6 @@ int main( int argc, char *argv[] )
     entropy_context entropy;
     ctr_drbg_context ctr_drbg;
     ssl_context ssl;
-    ssl_session ssn;
     x509_cert srvcert;
     rsa_context rsa;
 
@@ -369,13 +294,8 @@ int main( int argc, char *argv[] )
         ssl_set_dbg( &ssl, my_debug, stdout );
         ssl_set_bio( &ssl, net_recv, &client_fd,
                            net_send, &client_fd );
-        ssl_set_scb( &ssl, my_get_session,
-                           my_set_session );
 
         ssl_set_ciphersuites( &ssl, my_ciphersuites );
-        ssl_set_session( &ssl, 1, 0, &ssn );
-
-        memset( &ssn, 0, sizeof( ssl_session ) );
 
         ssl_set_ca_chain( &ssl, srvcert.next, NULL, NULL );
         ssl_set_own_cert( &ssl, &srvcert, &rsa );
@@ -482,17 +402,6 @@ exit:
     rsa_free( &rsa );
     ssl_free( &ssl );
 
-    cur = s_list_1st;
-    while( cur != NULL )
-    {
-        prv = cur;
-        cur = cur->next;
-        memset( prv, 0, sizeof( ssl_session ) );
-        free( prv );
-    }
-
-    memset( &ssl, 0, sizeof( ssl_context ) );
-
 #if defined(_WIN32)
     printf( "  Press Enter to exit this program.\n" );
     fflush( stdout ); getchar();

programs/ssl/ssl_mail_client.c

@@ -349,7 +349,6 @@ int main( int argc, char *argv[] )
     entropy_context entropy;
     ctr_drbg_context ctr_drbg;
     ssl_context ssl;
-    ssl_session ssn;
     x509_cert cacert;
     x509_cert clicert;
     rsa_context rsa;
@@ -362,8 +361,6 @@ int main( int argc, char *argv[] )
      * Make sure memory references are valid.
      */
     server_fd = 0;
-    memset( &ssn, 0, sizeof( ssl_session ) );
-    memset( &ssl, 0, sizeof( ssl_context ) );
     memset( &cacert, 0, sizeof( x509_cert ) );
     memset( &clicert, 0, sizeof( x509_cert ) );
     memset( &rsa, 0, sizeof( rsa_context ) );
@@ -607,8 +604,6 @@ int main( int argc, char *argv[] )
     else
         ssl_set_ciphersuites( &ssl, opt.force_ciphersuite );
 
-    ssl_set_session( &ssl, 1, 600, &ssn );
-
     ssl_set_ca_chain( &ssl, &cacert, NULL, opt.server_name );
     ssl_set_own_cert( &ssl, &clicert, &rsa );
 
@@ -804,11 +799,8 @@ exit:
     x509_free( &clicert );
     x509_free( &cacert );
     rsa_free( &rsa );
-    ssl_session_free( &ssn );
     ssl_free( &ssl );
 
-    memset( &ssl, 0, sizeof( ssl ) );
-
 #if defined(_WIN32)
     printf( "  + Press Enter to exit this program.\n" );
     fflush( stdout ); getchar();

programs/ssl/ssl_server.c

@@ -45,6 +45,10 @@
 #include "polarssl/net.h"
 #include "polarssl/error.h"
 
+#if defined(POLARSSL_SSL_CACHE_C)
+#include "polarssl/ssl_cache.h"
+#endif
+
 #define HTTP_RESPONSE \
     "HTTP/1.0 200 OK\r\nContent-Type: text/html\r\n\r\n" \
     "<h2>PolarSSL Test Server</h2>\r\n" \
@@ -153,80 +157,6 @@ void my_debug( void *ctx, int level, const char *str )
     }
 }
 
-/*
- * These session callbacks use a simple chained list
- * to store and retrieve the session information.
- */
-ssl_session *s_list_1st = NULL;
-ssl_session *cur, *prv;
-
-static int my_get_session( ssl_context *ssl )
-{
-    time_t t = time( NULL );
-
-    if( ssl->resume == 0 )
-        return( 1 );
-
-    cur = s_list_1st;
-    prv = NULL;
-
-    while( cur != NULL )
-    {
-        prv = cur;
-        cur = cur->next;
-
-        if( ssl->timeout != 0 && (int) ( t - prv->start ) > ssl->timeout )
-            continue;
-
-        if( ssl->session->ciphersuite != prv->ciphersuite ||
-            ssl->session->length != prv->length )
-            continue;
-
-        if( memcmp( ssl->session->id, prv->id, prv->length ) != 0 )
-            continue;
-
-        memcpy( ssl->session->master, prv->master, 48 );
-        return( 0 );
-    }
-
-    return( 1 );
-}
-
-static int my_set_session( ssl_context *ssl )
-{
-    time_t t = time( NULL );
-
-    cur = s_list_1st;
-    prv = NULL;
-
-    while( cur != NULL )
-    {
-        if( ssl->timeout != 0 && (int) ( t - cur->start ) > ssl->timeout )
-            break; /* expired, reuse this slot */
-
-        if( memcmp( ssl->session->id, cur->id, cur->length ) == 0 )
-            break; /* client reconnected */
-
-        prv = cur;
-        cur = cur->next;
-    }
-
-    if( cur == NULL )
-    {
-        cur = (ssl_session *) malloc( sizeof( ssl_session ) );
-        if( cur == NULL )
-            return( 1 );
-
-        if( prv == NULL )
-              s_list_1st = cur;
-        else  prv->next  = cur;
-    }
-
-    memcpy( cur, ssl->session, sizeof( ssl_session ) );
-
-    return( 0 );
-}
-
 #if !defined(POLARSSL_BIGNUM_C) || !defined(POLARSSL_CERTS_C) ||    \
     !defined(POLARSSL_ENTROPY_C) || !defined(POLARSSL_SSL_TLS_C) || \
     !defined(POLARSSL_SSL_SRV_C) || !defined(POLARSSL_NET_C) ||   \
@@ -254,14 +184,17 @@ int main( int argc, char *argv[] )
     entropy_context entropy;
     ctr_drbg_context ctr_drbg;
     ssl_context ssl;
-    ssl_session ssn;
     x509_cert srvcert;
     rsa_context rsa;
 
     ((void) argc);
     ((void) argv);
 
-    memset( &ssl, 0, sizeof( ssl_context ) );
+#if defined(POLARSSL_SSL_CACHE_C)
+    ssl_cache_context cache;
+
+    ssl_cache_init( &cache );
+#endif
 
     /*
      * 1. Load the certificates and private RSA key
@@ -351,13 +284,12 @@ int main( int argc, char *argv[] )
     ssl_set_rng( &ssl, ctr_drbg_random, &ctr_drbg );
     ssl_set_dbg( &ssl, my_debug, stdout );
 
-    ssl_set_scb( &ssl, my_get_session,
+#if defined(POLARSSL_SSL_CACHE_C)
-                       my_set_session );
+    ssl_set_session_cache( &ssl, ssl_cache_get, &cache,
+                                 ssl_cache_set, &cache );
+#endif
 
     ssl_set_ciphersuites( &ssl, my_ciphersuites );
-    ssl_set_session( &ssl, 1, 0, &ssn );
-
-    memset( &ssn, 0, sizeof( ssl_session ) );
 
     ssl_set_ca_chain( &ssl, srvcert.next, NULL, NULL );
     ssl_set_own_cert( &ssl, &srvcert, &rsa );
@@ -527,9 +459,10 @@ exit:
     net_close( client_fd );
     x509_free( &srvcert );
     rsa_free( &rsa );
-    ssl_session_free( &ssn );
-    ssl_session_free( s_list_1st );
     ssl_free( &ssl );
+#if defined(POLARSSL_SSL_CACHE_C)
+    ssl_cache_free( &cache );
+#endif
 
 #if defined(_WIN32)
     printf( "  Press Enter to exit this program.\n" );

programs/ssl/ssl_server2.c

@@ -45,6 +45,10 @@
 #include "polarssl/x509.h"
 #include "polarssl/error.h"
 
+#if defined(POLARSSL_SSL_CACHE_C)
+#include "polarssl/ssl_cache.h"
+#endif
+
 #define DFL_SERVER_PORT         4433
 #define DFL_REQUEST_PAGE        "/"
 #define DFL_DEBUG_LEVEL         0
@@ -94,80 +98,6 @@ void my_debug( void *ctx, int level, const char *str )
     }
 }
 
-/*
- * These session callbacks use a simple chained list
- * to store and retrieve the session information.
- */
-ssl_session *s_list_1st = NULL;
-ssl_session *cur, *prv;
-
-static int my_get_session( ssl_context *ssl )
-{
-    time_t t = time( NULL );
-
-    if( ssl->resume == 0 )
-        return( 1 );
-
-    cur = s_list_1st;
-    prv = NULL;
-
-    while( cur != NULL )
-    {
-        prv = cur;
-        cur = cur->next;
-
-        if( ssl->timeout != 0 && (int) ( t - prv->start ) > ssl->timeout )
-            continue;
-
-        if( ssl->session->ciphersuite != prv->ciphersuite ||
-            ssl->session->length != prv->length )
-            continue;
-
-        if( memcmp( ssl->session->id, prv->id, prv->length ) != 0 )
-            continue;
-
-        memcpy( ssl->session->master, prv->master, 48 );
-        return( 0 );
-    }
-
-    return( 1 );
-}
-
-static int my_set_session( ssl_context *ssl )
-{
-    time_t t = time( NULL );
-
-    cur = s_list_1st;
-    prv = NULL;
-
-    while( cur != NULL )
-    {
-        if( ssl->timeout != 0 && (int) ( t - cur->start ) > ssl->timeout )
-            break; /* expired, reuse this slot */
-
-        if( memcmp( ssl->session->id, cur->id, cur->length ) == 0 )
-            break; /* client reconnected */
-
-        prv = cur;
-        cur = cur->next;
-    }
-
-    if( cur == NULL )
-    {
-        cur = (ssl_session *) malloc( sizeof( ssl_session ) );
-        if( cur == NULL )
-            return( 1 );
-
-        if( prv == NULL )
-              s_list_1st = cur;
-        else  prv->next  = cur;
-    }
-
-    memcpy( cur, ssl->session, sizeof( ssl_session ) );
-
-    return( 0 );
-}
-
 #if defined(POLARSSL_FS_IO)
 #define USAGE_IO \
     "    ca_file=%%s          default: \"\" (pre-loaded)\n" \
@@ -218,10 +148,12 @@ int main( int argc, char *argv[] )
     entropy_context entropy;
     ctr_drbg_context ctr_drbg;
     ssl_context ssl;
-    ssl_session ssn;
     x509_cert cacert;
     x509_cert srvcert;
     rsa_context rsa;
+#if defined(POLARSSL_SSL_CACHE_C)
+    ssl_cache_context cache;
+#endif
 
     int i;
     size_t j, n;
@@ -232,11 +164,12 @@ int main( int argc, char *argv[] )
      * Make sure memory references are valid.
      */
     listen_fd = 0;
-    memset( &ssn, 0, sizeof( ssl_session ) );
-    memset( &ssl, 0, sizeof( ssl_context ) );
     memset( &cacert, 0, sizeof( x509_cert ) );
     memset( &srvcert, 0, sizeof( x509_cert ) );
     memset( &rsa, 0, sizeof( rsa_context ) );
+#if defined(POLARSSL_SSL_CACHE_C)
+    ssl_cache_init( &cache );
+#endif
 
     if( argc == 0 )
     {
@@ -455,8 +388,10 @@ int main( int argc, char *argv[] )
     ssl_set_rng( &ssl, ctr_drbg_random, &ctr_drbg );
     ssl_set_dbg( &ssl, my_debug, stdout );
 
-    ssl_set_scb( &ssl, my_get_session,
+#if defined(POLARSSL_SSL_CACHE_C)
-                       my_set_session );
+    ssl_set_session_cache( &ssl, ssl_cache_get, &cache,
+                                 ssl_cache_set, &cache );
+#endif
 
     if( opt.force_ciphersuite[0] == DFL_FORCE_CIPHER )
         ssl_set_ciphersuites( &ssl, ssl_default_ciphersuites );
@@ -466,8 +401,6 @@ int main( int argc, char *argv[] )
     ssl_set_renegotiation( &ssl, opt.renegotiation );
     ssl_legacy_renegotiation( &ssl, opt.allow_legacy );
 
-    ssl_set_session( &ssl, 1, 0, &ssn );
-
     ssl_set_ca_chain( &ssl, &cacert, NULL, NULL );
     ssl_set_own_cert( &ssl, &srvcert, &rsa );
 
@@ -673,10 +606,12 @@ exit:
     x509_free( &srvcert );
     x509_free( &cacert );
     rsa_free( &rsa );
-    ssl_session_free( &ssn );
-    ssl_session_free( s_list_1st );
     ssl_free( &ssl );
 
+#if defined(POLARSSL_SSL_CACHE_C)
+    ssl_cache_free( &cache );
+#endif
+
 #if defined(_WIN32)
     printf( "  + Press Enter to exit this program.\n" );
     fflush( stdout ); getchar();

programs/test/ssl_test.c

@@ -167,7 +167,6 @@ static int ssl_test( struct options *opt )
     entropy_context entropy;
     ctr_drbg_context ctr_drbg;
     ssl_context ssl;
-    ssl_session ssn;
     x509_cert srvcert;
     rsa_context rsa;
 
@@ -273,9 +272,6 @@ static int ssl_test( struct options *opt )
     ssl_set_bio( &ssl, net_recv, &client_fd,
                        net_send, &client_fd );
 
-    ssl_set_session( &ssl, opt->session_reuse,
-                           opt->session_lifetime, &ssn );
-
     if( opt->force_ciphersuite[0] == DFL_FORCE_CIPHER )
           ssl_set_ciphersuites( &ssl, ssl_default_ciphersuites );
     else  ssl_set_ciphersuites( &ssl, opt->force_ciphersuite );

programs/x509/cert_app.c

@@ -108,7 +108,6 @@ int main( int argc, char *argv[] )
     entropy_context entropy;
     ctr_drbg_context ctr_drbg;
     ssl_context ssl;
-    ssl_session ssn;
     x509_cert clicert;
     rsa_context rsa;
     int i, j, n;
@@ -119,8 +118,6 @@ int main( int argc, char *argv[] )
      * Set to sane values
      */
     server_fd = 0;
-    memset( &ssl, 0, sizeof( ssl_context ) );
-    memset( &ssn, 0, sizeof( ssl_session ) );
     memset( &clicert, 0, sizeof( x509_cert ) );
     memset( &rsa, 0, sizeof( rsa_context ) );
 
@@ -288,7 +285,6 @@ int main( int argc, char *argv[] )
                 net_send, &server_fd );
 
         ssl_set_ciphersuites( &ssl, ssl_default_ciphersuites );
-        ssl_set_session( &ssl, 1, 600, &ssn );
 
         ssl_set_own_cert( &ssl, &clicert, &rsa );
 
@@ -333,7 +329,6 @@ exit:
         net_close( server_fd );
     x509_free( &clicert );
     rsa_free( &rsa );
-    ssl_session_free( &ssn );
     ssl_free( &ssl );
 
 #if defined(_WIN32)