public static boolean isRedirectValid()

in src/main/java/org/apache/sling/auth/core/AuthUtil.java [456:517]
49 lines of code
18 McCabe index (conditional complexity)

    public static boolean isRedirectValid(final HttpServletRequest request, final String target) {
        if (target == null || target.length() == 0) {
            getLog().warn("isRedirectValid: Redirect target must not be empty or null");
            return false;
        }

        try {
            new URI(target);
        } catch (URISyntaxException e) {
            getLog().warn("isRedirectValid: Redirect target '{}' contains illegal characters", target);
            return false;
        }

        if (target.contains("://")) {
            getLog().warn("isRedirectValid: Redirect target '{}' must not be an URL", target);
            return false;
        }

        if (target.contains("//") || target.contains("/../") || target.contains("/./") || target.endsWith("/.")
            || target.endsWith("/..")) {
            getLog().warn("isRedirectValid: Redirect target '{}' is not normalized", target);
            return false;
        }

        final String ctxPath = getContextPath(request);
        if (ctxPath.length() > 0 && !target.startsWith(ctxPath)) {
            getLog().warn("isRedirectValid: Redirect target '{}' does not start with servlet context path '{}'",
                target, ctxPath);
            return false;
        }

        // special case of requesting the servlet context root path
        if (ctxPath.length() == target.length()) {
            return true;
        }

        final String localTarget = target.substring(ctxPath.length());
        if (!localTarget.startsWith("/")) {
            getLog().warn(
                "isRedirectValid: Redirect target '{}' without servlet context path '{}' must be an absolute path",
                target, ctxPath);
            return false;
        }

        final int query = localTarget.indexOf('?');
        final String path = (query > 0) ? localTarget.substring(0, query) : localTarget;

        ResourceResolver resolver = getResourceResolver(request);
        // assume all is fine if the path resolves to a resource
        if (resolver != null && !ResourceUtil.isNonExistingResource(resolver.resolve(request, path))) {
            return true;
        }

        // not resolving to a resource, check for illegal characters
        final Pattern illegal = Pattern.compile("[<>'\"]");
        if (illegal.matcher(path).find()) {
            getLog().warn("isRedirectValid: Redirect target '{}' must not contain any of <>'\"", target);
            return false;
        }

        return true;
    }