Improve documentation of (D)TLSInnerPlaintext handling
Signed-off-by: Hanno Becker <hanno.becker@arm.com>
diff --git a/library/ssl_msg.c b/library/ssl_msg.c
index e739e2f..6151cbd 100644
--- a/library/ssl_msg.c
+++ b/library/ssl_msg.c
@@ -578,16 +578,21 @@
return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
}
+ /* The following two code paths implement the (D)TLSInnerPlaintext
+ * structure present in TLS 1.3 and DTLS 1.2 + CID.
+ *
+ * See ssl_build_inner_plaintext() for more information.
+ *
+ * Note that this changes `rec->data_len`, and hence
+ * `post_avail` needs to be recalculated afterwards.
+ *
+ * Note also that the two code paths cannot occur simultaneously
+ * since they apply to different versions of the protocol. There
+ * is hence no risk of double-addition of the inner plaintext.
+ */
#if defined(MBEDTLS_SSL_PROTO_TLS1_3_EXPERIMENTAL)
if( transform->minor_ver == MBEDTLS_SSL_MINOR_VERSION_4 )
{
- /*
- * Wrap plaintext into TLSInnerPlaintext structure.
- * See ssl_build_inner_plaintext() for more information.
- *
- * Note that this changes `rec->data_len`, and hence
- * `post_avail` needs to be recalculated afterwards.
- */
if( ssl_build_inner_plaintext( data,
&rec->data_len,
post_avail,
