modules: mbedtls: Extend generic config with SSL cache

Add Kconfig configuration options which allow to configure
session caching in mbed TLS.

Note, that mbed TLS only takes care of server-side caching, the
application (socket layer) needs to implement a session storage for
client.

Signed-off-by: Robert Lubos <[email protected]>

Author: rlubos

modules/mbedtls/Kconfig.tls-generic

@@ -396,4 +396,19 @@ config MBEDTLS_PKCS5_C
 	help
 	  Enable PKCS5 functions
 
+config MBEDTLS_SSL_CACHE_C
+	bool "SSL session cache support"
+	help
+	  "This option enables simple SSL cache implementation (server side)."
+
+config MBEDTLS_SSL_CACHE_DEFAULT_TIMEOUT
+	int "Default timeout for SSL cache entires"
+	depends on MBEDTLS_SSL_CACHE_C
+	default 86400
+
+config MBEDTLS_SSL_CACHE_DEFAULT_MAX_ENTRIES
+	int "Maximum number of SSL cache entires"
+	depends on MBEDTLS_SSL_CACHE_C
+	default 5
+
 endmenu

modules/mbedtls/configs/config-tls-generic.h

@@ -434,6 +434,12 @@
 #define MBEDTLS_SSL_SERVER_NAME_INDICATION
 #endif
 
+#if defined(CONFIG_MBEDTLS_SSL_CACHE_C)
+#define MBEDTLS_SSL_CACHE_C
+#define MBEDTLS_SSL_CACHE_DEFAULT_TIMEOUT CONFIG_MBEDTLS_SSL_CACHE_DEFAULT_TIMEOUT
+#define MBEDTLS_SSL_CACHE_DEFAULT_MAX_ENTRIES CONFIG_MBEDTLS_SSL_CACHE_DEFAULT_MAX_ENTRIES
+#endif
+
 /* User config file */
 
 #if defined(CONFIG_MBEDTLS_USER_CONFIG_FILE)