int mbedtls_ssl_handle_message_type( mbedtls_ssl_context *ssl )
{
    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;

    /*
     * Handle particular types of records
     */
    if( ssl->in_msgtype == MBEDTLS_SSL_MSG_HANDSHAKE )
    {
        if( ( ret = mbedtls_ssl_prepare_handshake_record( ssl ) ) != 0 )
        {
            return( ret );
        }
    }

    if( ssl->in_msgtype == MBEDTLS_SSL_MSG_CHANGE_CIPHER_SPEC )
    {
        if( ssl->in_msglen != 1 )
        {
            MBEDTLS_SSL_DEBUG_MSG( 1, ( "invalid CCS message, len: %" MBEDTLS_PRINTF_SIZET,
                           ssl->in_msglen ) );
            return( MBEDTLS_ERR_SSL_INVALID_RECORD );
        }

        if( ssl->in_msg[0] != 1 )
        {
            MBEDTLS_SSL_DEBUG_MSG( 1, ( "invalid CCS message, content: %02x",
                                        ssl->in_msg[0] ) );
            return( MBEDTLS_ERR_SSL_INVALID_RECORD );
        }

#if defined(MBEDTLS_SSL_PROTO_DTLS)
        if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM &&
            ssl->state != MBEDTLS_SSL_CLIENT_CHANGE_CIPHER_SPEC    &&
            ssl->state != MBEDTLS_SSL_SERVER_CHANGE_CIPHER_SPEC )
        {
            if( ssl->handshake == NULL )
            {
                MBEDTLS_SSL_DEBUG_MSG( 1, ( "dropping ChangeCipherSpec outside handshake" ) );
                return( MBEDTLS_ERR_SSL_UNEXPECTED_RECORD );
            }

            MBEDTLS_SSL_DEBUG_MSG( 1, ( "received out-of-order ChangeCipherSpec - remember" ) );
            return( MBEDTLS_ERR_SSL_EARLY_MESSAGE );
        }
#endif
    }

    if( ssl->in_msgtype == MBEDTLS_SSL_MSG_ALERT )
    {
        if( ssl->in_msglen != 2 )
        {
            /* Note: Standard allows for more than one 2 byte alert
               to be packed in a single message, but Mbed TLS doesn't
               currently support this. */
            MBEDTLS_SSL_DEBUG_MSG( 1, ( "invalid alert message, len: %" MBEDTLS_PRINTF_SIZET,
                           ssl->in_msglen ) );
            return( MBEDTLS_ERR_SSL_INVALID_RECORD );
        }

        MBEDTLS_SSL_DEBUG_MSG( 2, ( "got an alert message, type: [%u:%u]",
                       ssl->in_msg[0], ssl->in_msg[1] ) );

        /*
         * Ignore non-fatal alerts, except close_notify and no_renegotiation
         */
        if( ssl->in_msg[0] == MBEDTLS_SSL_ALERT_LEVEL_FATAL )
        {
            MBEDTLS_SSL_DEBUG_MSG( 1, ( "is a fatal alert message (msg %d)",
                           ssl->in_msg[1] ) );
            return( MBEDTLS_ERR_SSL_FATAL_ALERT_MESSAGE );
        }

        if( ssl->in_msg[0] == MBEDTLS_SSL_ALERT_LEVEL_WARNING &&
            ssl->in_msg[1] == MBEDTLS_SSL_ALERT_MSG_CLOSE_NOTIFY )
        {
            MBEDTLS_SSL_DEBUG_MSG( 2, ( "is a close notify message" ) );
            return( MBEDTLS_ERR_SSL_PEER_CLOSE_NOTIFY );
        }

#if defined(MBEDTLS_SSL_RENEGOTIATION_ENABLED)
        if( ssl->in_msg[0] == MBEDTLS_SSL_ALERT_LEVEL_WARNING &&
            ssl->in_msg[1] == MBEDTLS_SSL_ALERT_MSG_NO_RENEGOTIATION )
        {
            MBEDTLS_SSL_DEBUG_MSG( 2, ( "is a SSLv3 no renegotiation alert" ) );
            /* Will be handled when trying to parse ServerHello */
            return( 0 );
        }
#endif

#if defined(MBEDTLS_SSL_PROTO_SSL3) && defined(MBEDTLS_SSL_SRV_C)
        if( ssl->minor_ver == MBEDTLS_SSL_MINOR_VERSION_0 &&
            ssl->conf->endpoint == MBEDTLS_SSL_IS_SERVER &&
            ssl->in_msg[0] == MBEDTLS_SSL_ALERT_LEVEL_WARNING &&
            ssl->in_msg[1] == MBEDTLS_SSL_ALERT_MSG_NO_CERT )
        {
            MBEDTLS_SSL_DEBUG_MSG( 2, ( "is a SSLv3 no_cert" ) );
            /* Will be handled in mbedtls_ssl_parse_certificate() */
            return( 0 );
        }
#endif /* MBEDTLS_SSL_PROTO_SSL3 && MBEDTLS_SSL_SRV_C */

        /* Silently ignore: fetch new message */
        return MBEDTLS_ERR_SSL_NON_FATAL;
    }

#if defined(MBEDTLS_SSL_PROTO_DTLS)
    if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM )
    {
        /* Drop unexpected ApplicationData records,
         * except at the beginning of renegotiations */
        if( ssl->in_msgtype == MBEDTLS_SSL_MSG_APPLICATION_DATA &&
            ssl->state != MBEDTLS_SSL_HANDSHAKE_OVER
#if defined(MBEDTLS_SSL_RENEGOTIATION)
            && ! ( ssl->renego_status == MBEDTLS_SSL_RENEGOTIATION_IN_PROGRESS &&
                   ssl->state == MBEDTLS_SSL_SERVER_HELLO )
#endif
            )
        {
            MBEDTLS_SSL_DEBUG_MSG( 1, ( "dropping unexpected ApplicationData" ) );
            return( MBEDTLS_ERR_SSL_NON_FATAL );
        }

        if( ssl->handshake != NULL &&
            ssl->state == MBEDTLS_SSL_HANDSHAKE_OVER  )
        {
            mbedtls_ssl_handshake_wrapup_free_hs_transform( ssl );
        }
    }
#endif /* MBEDTLS_SSL_PROTO_DTLS */

    return( 0 );
}
int mbedtls_ssl_handle_message_type( mbedtls_ssl_context *ssl )
{
    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;

     
    if( ssl->in_msgtype == MBEDTLS_SSL_MSG_HANDSHAKE )
    {
        if( ( ret = mbedtls_ssl_prepare_handshake_record( ssl ) ) != 0 )
        {
            return( ret );
        }
    }

    if( ssl->in_msgtype == MBEDTLS_SSL_MSG_CHANGE_CIPHER_SPEC )
    {
        if( ssl->in_msglen != 1 )
        {
            MBEDTLS_SSL_DEBUG_MSG( 1, ( "invalid CCS message, len: %" MBEDTLS_PRINTF_SIZET,
                           ssl->in_msglen ) );
            return( MBEDTLS_ERR_SSL_INVALID_RECORD );
        }

        if( ssl->in_msg[0] != 1 )
        {
            MBEDTLS_SSL_DEBUG_MSG( 1, ( "invalid CCS message, content: %02x",
                                        ssl->in_msg[0] ) );
            return( MBEDTLS_ERR_SSL_INVALID_RECORD );
        }

#if defined(MBEDTLS_SSL_PROTO_DTLS)
        if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM &&
            ssl->state != MBEDTLS_SSL_CLIENT_CHANGE_CIPHER_SPEC    &&
            ssl->state != MBEDTLS_SSL_SERVER_CHANGE_CIPHER_SPEC )
        {
            if( ssl->handshake == NULL )
            {
                MBEDTLS_SSL_DEBUG_MSG( 1, ( "dropping ChangeCipherSpec outside handshake" ) );
                return( MBEDTLS_ERR_SSL_UNEXPECTED_RECORD );
            }

            MBEDTLS_SSL_DEBUG_MSG( 1, ( "received out-of-order ChangeCipherSpec - remember" ) );
            return( MBEDTLS_ERR_SSL_EARLY_MESSAGE );
        }
#endif
    }

    if( ssl->in_msgtype == MBEDTLS_SSL_MSG_ALERT )
    {
        if( ssl->in_msglen != 2 )
        {
             
            MBEDTLS_SSL_DEBUG_MSG( 1, ( "invalid alert message, len: %" MBEDTLS_PRINTF_SIZET,
                           ssl->in_msglen ) );
            return( MBEDTLS_ERR_SSL_INVALID_RECORD );
        }

        MBEDTLS_SSL_DEBUG_MSG( 2, ( "got an alert message, type: [%u:%u]",
                       ssl->in_msg[0], ssl->in_msg[1] ) );

         
        if( ssl->in_msg[0] == MBEDTLS_SSL_ALERT_LEVEL_FATAL )
        {
            MBEDTLS_SSL_DEBUG_MSG( 1, ( "is a fatal alert message (msg %d)",
                           ssl->in_msg[1] ) );
            return( MBEDTLS_ERR_SSL_FATAL_ALERT_MESSAGE );
        }

        if( ssl->in_msg[0] == MBEDTLS_SSL_ALERT_LEVEL_WARNING &&
            ssl->in_msg[1] == MBEDTLS_SSL_ALERT_MSG_CLOSE_NOTIFY )
        {
            MBEDTLS_SSL_DEBUG_MSG( 2, ( "is a close notify message" ) );
            return( MBEDTLS_ERR_SSL_PEER_CLOSE_NOTIFY );
        }

#if defined(MBEDTLS_SSL_RENEGOTIATION_ENABLED)
        if( ssl->in_msg[0] == MBEDTLS_SSL_ALERT_LEVEL_WARNING &&
            ssl->in_msg[1] == MBEDTLS_SSL_ALERT_MSG_NO_RENEGOTIATION )
        {
            MBEDTLS_SSL_DEBUG_MSG( 2, ( "is a SSLv3 no renegotiation alert" ) );
             
            return( 0 );
        }
#endif

#if defined(MBEDTLS_SSL_PROTO_SSL3) && defined(MBEDTLS_SSL_SRV_C)
        if( ssl->minor_ver == MBEDTLS_SSL_MINOR_VERSION_0 &&
            ssl->conf->endpoint == MBEDTLS_SSL_IS_SERVER &&
            ssl->in_msg[0] == MBEDTLS_SSL_ALERT_LEVEL_WARNING &&
            ssl->in_msg[1] == MBEDTLS_SSL_ALERT_MSG_NO_CERT )
        {
            MBEDTLS_SSL_DEBUG_MSG( 2, ( "is a SSLv3 no_cert" ) );
             
            return( 0 );
        }
#endif  

         
        return MBEDTLS_ERR_SSL_NON_FATAL;
    }

#if defined(MBEDTLS_SSL_PROTO_DTLS)
    if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM )
    {
         
        if( ssl->in_msgtype == MBEDTLS_SSL_MSG_APPLICATION_DATA &&
            ssl->state != MBEDTLS_SSL_HANDSHAKE_OVER
#if defined(MBEDTLS_SSL_RENEGOTIATION)
            && ! ( ssl->renego_status == MBEDTLS_SSL_RENEGOTIATION_IN_PROGRESS &&
                   ssl->state == MBEDTLS_SSL_SERVER_HELLO )
#endif
            )
        {
            MBEDTLS_SSL_DEBUG_MSG( 1, ( "dropping unexpected ApplicationData" ) );
            return( MBEDTLS_ERR_SSL_NON_FATAL );
        }

        if( ssl->handshake != NULL &&
            ssl->state == MBEDTLS_SSL_HANDSHAKE_OVER  )
        {
            mbedtls_ssl_handshake_wrapup_free_hs_transform( ssl );
        }
    }
#endif  

    return( 0 );
}