commit f661c9c39cf75fa2f2c233dbc8d736fed7faae1d
author Hanno Becker <hanno.becker@arm.com> Fri May 03 13:25:54 2019 +0100
committer Hanno Becker <hanno.becker@arm.com> Mon Jun 03 16:07:50 2019 +0100
tree 325d7895ed8b76fa63500c91033b67622e407b94
parent 37ae952923cd411ae387127184904aab773c8225

Add helper function to check validity of record content type

With the introduction of the CID feature, the stack needs to be able
to handle a change of record content type during record protection,
which in particular means that the record content type check will
need to move or be duplicated.

This commit introduces a tiny static helper function which checks
the validity of record content types, which hopefully makes it
easier to subsequently move or duplicate this check.

library/ssl_tls.c

diff --git a/library/ssl_tls.c b/library/ssl_tls.c
index 1192d24..8c3c74d 100644
--- a/library/ssl_tls.c
+++ b/library/ssl_tls.c
@@ -4793,6 +4793,19 @@
 }
 #endif /* MBEDTLS_SSL_DTLS_CLIENT_PORT_REUSE && MBEDTLS_SSL_SRV_C */
 
+static int ssl_check_record_type( uint8_t record_type )
+{
+    if( record_type != MBEDTLS_SSL_MSG_HANDSHAKE &&
+        record_type != MBEDTLS_SSL_MSG_ALERT &&
+        record_type != MBEDTLS_SSL_MSG_CHANGE_CIPHER_SPEC &&
+        record_type != MBEDTLS_SSL_MSG_APPLICATION_DATA )
+    {
+        return( MBEDTLS_ERR_SSL_INVALID_RECORD );
+    }
+
+    return( 0 );
+}
+
 /*
  * ContentType type;
  * ProtocolVersion version;
@@ -4828,10 +4841,7 @@
                         major_ver, minor_ver, ssl->in_msglen ) );
 
     /* Check record type */
-    if( ssl->in_msgtype != MBEDTLS_SSL_MSG_HANDSHAKE &&
-        ssl->in_msgtype != MBEDTLS_SSL_MSG_ALERT &&
-        ssl->in_msgtype != MBEDTLS_SSL_MSG_CHANGE_CIPHER_SPEC &&
-        ssl->in_msgtype != MBEDTLS_SSL_MSG_APPLICATION_DATA )
+    if( ssl_check_record_type( ssl->in_msgtype ) )
     {
         MBEDTLS_SSL_DEBUG_MSG( 1, ( "unknown record type" ) );