Introduce specific error for ver/cfg mismatch on deserialization
This commit introduces a new SSL error code
`MBEDTLS_ERR_SSL_VERSION_MISMATCH`
which can be used to indicate operation failure due to a
mismatch of version or configuration.
It is put to use in the implementation of `mbedtls_ssl_session_load()`
to signal the attempt to de-serialize a session which has been serialized
in a build of Mbed TLS using a different version or configuration.
diff --git a/include/mbedtls/ssl.h b/include/mbedtls/ssl.h
index d435a69..df62069 100644
--- a/include/mbedtls/ssl.h
+++ b/include/mbedtls/ssl.h
@@ -123,6 +123,7 @@
#define MBEDTLS_ERR_SSL_ASYNC_IN_PROGRESS -0x6500 /**< The asynchronous operation is not completed yet. */
#define MBEDTLS_ERR_SSL_EARLY_MESSAGE -0x6480 /**< Internal-only message signaling that a message arrived early. */
#define MBEDTLS_ERR_SSL_UNEXPECTED_CID -0x6000 /**< An encrypted DTLS-frame with an unexpected CID was received. */
+#define MBEDTLS_ERR_SSL_VERSION_MISMATCH -0x5F00 /**< An operation failed due to an unexpected version or configuration. */
#define MBEDTLS_ERR_SSL_CRYPTO_IN_PROGRESS -0x7000 /**< A cryptographic operation is in progress. Try again later. */
/*
@@ -2179,6 +2180,9 @@
* \return \c 0 if successful.
* \return #MBEDTLS_ERR_SSL_ALLOC_FAILED if memory allocation failed.
* \return #MBEDTLS_ERR_SSL_BAD_INPUT_DATA if input data is invalid.
+ * \return #MBEDTLS_ERR_SSL_VERSION_MISMATCH if the serialized data
+ * was generated in a different version or configuration of
+ * Mbed TLS.
* \return Another negative value for other kinds of errors (for
* example, unsupported features in the embedded certificate).
*/