HTTP Response Headers - Product Documentation: Vancouver

HTTP Response Headers

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HTTP Response Headers

A response header is a simple name-value pair used in an HTTP response to provide additional information about page content or how the client should process it.

You can configure HTTP response headers for all, or specific types of pages, which include Service Portal , UI Page, or UX applications. The ability to configure and pass response headers enables special handling of the page content by a client, most typically a browser.

To learn more about what an HTTP header is, and about configuring the name-value pair for specific HTTP response headers, see: https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers

When configuring response headers, you must look at the definition for the HTTP header to determine how the client would handle the page content. For example, you configure an HTTP header for a specific page or all the pages with a Content-Security-Policy: frame-ancestors 'self' https://www.servicenow.com. When you invoke the page in a browser such as Chrome, you can review it in the Response Headers section of Chrome Developer Tools.

To learn more about how browsers handle a page with frame-ancestors, see https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Content-Security-Policy/frame-ancestors .

Warning: When using URLs with custom name-value pairs, proceed with caution because there is a potential security risk when doing so. The signed security amendment to the Now Platform contract has implied security. You may potentially or accidentally override it when you use custom name-value pairs in the resulting URLs. If you want to entirely disable HTTP response header configuration functions, set the glide.http.headers_config.enabled property to false . Once you set it to false, Now Platform does not use any of the header configurations you defined in the sys_response_header table.

Special handling of the Content-Security-Policy: frame-ancestor header Normally, the Now Platform automatically includes the X-Frame-Options: SAMEORIGIN header. It supports use of this header in all types of browsers, based on the setting of the glide.set_x_frame_options global property, which is enabled by default. When you configure a page with a Content-Security-Policy: frame-ancestor 'self' URL1 URL2 header, the Now Platform does not automatically include the X-Frame-Options: SAMEORIGIN header. Excluding it prevents the browser from being confused, because Content-Security-Policy: frame-ancestor 'self' already has a similar effect.

Special handling of Content-Security-Policy: frame-ancestor header for Internet Explorer Using the Content-Security-Policy: frame-ancestor 'self' URL1 URL2 header enables you to configure multiple URL sources to include the page from within an iFrame rendered from a third-party site. However, Internet Explorer does not support this type of header. Instead, the Internet Explorer only supports the X-Frame-Options: ALLOW-FROM URL (ALLOW-FROM) directive in this header, although the restriction is for a single host URL. If you configure the frame-ancestor 'self' URL1 URL2 header, and Internet Explorer is in use, the Now Platform automatically uses the X-Frame-Options: ALLOW-FROM URL (ALLOW-FROM) header instead.

If the Internet Explorer request includes the referrer URL header: It attempts to match it with the host URLs (full or wildcard http://*.example.com type URL format only) configured in the Content-Security-Policy: frame-ancestor 'self' URL1 URL2 header. If there is a match, include the matched URL as X-Frame-Options: ALLOW-FROM URL1. If there is no referrer header, it uses the first non-wildcard based host URLs configured in the Content-Security-Policy: frame-ancestor 'self' URL1 URL2 header.

Note: When configuring URLs, do not include a forward slash at the end of the URL. This example of an incorrect configuration that may not work properly with this special handling: Name: Content-Security-Policy Value: frame-ancestors 'self' https://microsoft.com/ Use this correct syntax instead: Name: Content-Security-Policy Value: frame-ancestors 'self' https://microsoft.com

Configure HTTP response headers Configure standard name-value pairs for HTTP response headers. You designate if the configuration applies to all pages, or to specific types ( Service Portal , UI Page, or UX application record).

Parent Topic: Web services

Related concepts Control request and response content type

Related topics Cache-Control HTTP header value Content-Security-Policy: frame-ancestor 'self' URL1 URL2 X-Frame-Options: SAMEORIGIN X-Frame-Options: ALLOW-FROM URL