/* Discard any data that has already been read from the socket and are

 * lingering around in the input filter chain

 */

static apr_status_t proxy_wstunnel_strip_extra_data(request_rec *r)

{

    apr_bucket_brigade *bb;

    conn_rec *c = r->connection;

    apr_status_t rv;

    apr_off_t len;

    bb = apr_brigade_create(r->pool, c->bucket_alloc);

    rv = ap_get_brigade(c->input_filters, bb, AP_MODE_READBYTES,

                        APR_NONBLOCK_READ, APR_BUCKET_BUFF_SIZE);

    if (APR_STATUS_IS_EAGAIN(rv)) {

	ap_log_rerror(APLOG_MARK, APLOG_TRACE2, rv, r,

		      "client didn't send extra data after "

		      "WebSocket request headers");

	return OK;

    }

    if (rv != APR_SUCCESS) {

	ap_log_rerror(APLOG_MARK, APLOG_ERR, rv, r,

		      "unexpected error when checking for extra data "

		      "after WebSocket request headers");

	return rv;

    }

    rv = apr_brigade_length(bb, 0, &len);

    ap_log_rerror(APLOG_MARK, APLOG_INFO, rv, r,

		  "removed %s bytes extra data received from client "

		  "after WebSocket request headers",

		  apr_off_t_toa(r->pool, len));

    return APR_SUCCESS;

}

    /* Some clients send extra data (e.g. an additional CRLF) after the

     * request headers and before the backend server has sent the

     * "101 Switching Protocols" response. If this data is not meant to

     * be consumend after switching to the websocket protocol, this is a HTTP

     * protocol violation. If proxy-wstunnel-strip-extra-data is set, this

     * extra data is stripped, i.e. not forwarded to the backend server.

     * This can help with backend servers that get confused if the additional

     * CRLF is forwarded later from within proxy_wstunnel_request().

     */

    if (apr_table_get(r->subprocess_env, "proxy-wstunnel-strip-extra-data")) {

        status = proxy_wstunnel_strip_extra_data(r);

        if (status != APR_SUCCESS) {

	    return HTTP_INTERNAL_SERVER_ERROR;

	}

    }