private boolean processReferrer()

in app/src/main/java/org/apache/roller/weblogger/ui/rendering/servlets/PageServlet.java [586:678]
67 lines of code
20 McCabe index (conditional complexity)

    private boolean processReferrer(HttpServletRequest request) {

        log.debug("processing referrer for " + request.getRequestURI());

        // bleh! because ref processing does a flush it will close
        // our hibernate session and cause lazy init exceptions on
        // objects we have fetched, so we need to use a separate
        // page request object for this
        WeblogPageRequest pageRequest;
        try {
            pageRequest = new WeblogPageRequest(request);
        } catch (InvalidRequestException ex) {
            return false;
        }

        // if this came from site-wide frontpage then skip it
        if (WebloggerRuntimeConfig.isSiteWideWeblog(pageRequest
                .getWeblogHandle())) {
            return false;
        }

        // if this came from a robot then don't process it
        if (robotPattern != null) {
            String userAgent = request.getHeader("User-Agent");
            if (userAgent != null && userAgent.length() > 0
                    && robotPattern.matcher(userAgent).matches()) {
                log.debug("skipping referrer from robot");
                return false;
            }
        }

        String referrerUrl = null;
        String[] schemes = {"http", "https"};
        UrlValidator urlValidator = new UrlValidator(schemes);
        if (urlValidator.isValid(request.getHeader("Referer"))) {
            referrerUrl = request.getHeader("Referer");
        }
        log.debug("referrer = " + referrerUrl);

        StringBuffer reqsb = request.getRequestURL();
        if (request.getQueryString() != null) {
            reqsb.append("?");
            reqsb.append(request.getQueryString());
        }
        String requestUrl = reqsb.toString();

        // if this came from persons own blog then don't process it
        String selfSiteFragment = "/" + pageRequest.getWeblogHandle();
        if (referrerUrl != null && referrerUrl.contains(selfSiteFragment)) {
            log.debug("skipping referrer from own blog");
            return false;
        }

        // validate the referrer
        if (pageRequest.getWeblogHandle() != null) {

            // Base page URLs, with and without www.
            String basePageUrlWWW = WebloggerRuntimeConfig
                    .getAbsoluteContextURL()
                    + "/"
                    + pageRequest.getWeblogHandle();
            String basePageUrl = basePageUrlWWW;
            if (basePageUrlWWW.startsWith("http://www.")) {
                // chop off the http://www.
                basePageUrl = "http://" + basePageUrlWWW.substring(11);
            }

            // ignore referrers coming from users own blog
            if (referrerUrl == null
                    || (!referrerUrl.startsWith(basePageUrl) && !referrerUrl
                            .startsWith(basePageUrlWWW))) {

                // validate the referrer
                if (referrerUrl != null) {
                    // treat editor referral as direct
                    int lastSlash = requestUrl.indexOf('/', 8);
                    if (lastSlash == -1) {
                        lastSlash = requestUrl.length();
                    }
                    String requestSite = requestUrl.substring(0, lastSlash);

                    return !(referrerUrl.startsWith(requestSite)
                            && referrerUrl.indexOf(".rol") >= requestSite.length())
                            && BannedwordslistChecker.checkReferrer(pageRequest.getWeblog(), referrerUrl);
                }
            } else {
                log.debug("Ignoring referer = " + referrerUrl);
                return false;
            }
        }

        return false;
    }