HTTP Header Settings (Cross-origin Requests)

Precautions

• Some headers cannot be set or deleted. For details, see Constraints.
• You can add up to 10 HTTP response header configurations.

• HTTP header configuration is domain name-specific. When the configuration takes effect, the specified headers will be added to or removed from response messages for any resources under the entire domain. However, HTTP header configuration only affects the response behavior of the clients (browsers). They do not affect the cache behavior of CDN PoPs.
• If your domain name is an OBS bucket and CORS rules are configured on CDN, you also need to configure CORS on OBS.

Supported Response Headers

Huawei Cloud CDN lets you customize the following different HTTP response headers:

• Content-Disposition

  The Content-Disposition header can start a download on the client side and specify the name of the file to be downloaded.

  When a server sends a file to a browser, as long as the file format is supported (for instance TXT or JPG), the file is opened using the browser by default. If the file needs to be treated as an attachment and saved with a specific file name, you can use the Content-Disposition header field to specify this requirement.

  

  If you use an OBS bucket created after January 1, 2022 as the origin server and want to enable online preview, set Content-Disposition to inline. For details, see How Do I Preview Objects in OBS Through a Browser?

• Content-Language

  The Content-Language header specifies the preferred language or language combination of the browser. Content can be customized for different users.

• Access-Control-Allow-Origin

  The Access-Control-Allow-Origin header carries the domain names that are allowed for CORS after server authentication. For a simple CORS request, the browser determines whether to return the requested resource content to the client based on this message header. For a pre-check request, the browser determines whether to initiate an actual CORS request to the server based on this message header.

  

  To prevent cross-domain errors caused by browser cache, clear browser cache after configuring Access-Control-Allow-Origin.

• Access-Control-Allow-Methods

  The Access-Control-Allow-Methods header carries the methods that are allowed for CORS after server authentication. For a simple CORS request, the browser determines whether to return the requested resource content to the client based on this message header. For a pre-check request, the browser determines whether to initiate an actual CORS request to the server based on this message header.

• Access-Control-Max-Age

  The Access-Control-Max-Age header determines how long the pre-check results for CORS requests allowed by the server can be cached. The browser determines the TTL for pre-check request results based on this message header. As long as the period defined by this header has not expired, the browser can determine whether to initiate a CORS request to the server based on the results. Once this period expires, the browser needs to send another pre-check request to the server.

• Access-Control-Expose-Headers

  Access-Control-Expose-Headers specify the response headers that the browser can expose to the client. You can use this field to define the response headers visible to the client. The following response headers are visible to the client by default: Cache-Control, Content-Language, Content-Type, Expires, Last-Modified, and Pragma.

• Custom

  If the preceding response headers cannot meet your needs, you can create response headers. A custom response header can contain 1 to 100 characters, starting with a letter and consisting of letters, digits, and hyphens (-).

Procedure

1. Log in to the CDN console.
2. In the navigation pane, choose Domains.
3. In the domain list, click the target domain name or click Configure in the Operation column.
4. Click the Advanced Settings tab.
5. In the HTTP Headers area, click Edit. The Configure HTTP Headers dialog box is displayed.
   Figure 1 Configuring HTTP headers
   

6. Click Add and select a response header operation from the drop-down list.

   Response Header Operation	Description
   Set	If the header already exists in the response, the header value you configure will overwrite the original one. If the header does not exist in the response, the header will be added to the response.
   Delete	The header will be deleted from the response.

7. Set the header parameter and value.

   Parameter	Description	Example Value
   Content-disposition	Starts a download on the client side and specifies the name of the file to be downloaded. Value requirements: For a typical configuration, see the example on the right.	attachment;filename=FileName.xls
   Content-Language	Specifies the language of the response page of the client. Value requirements: For a typical configuration, see the example on the right.	zh-CN en-US
   Access-Control-Allow-Origin	Specifies the foreign domain URLs (request sources) that are allowed to access the resource in cross-origin resource sharing (CORS). Value requirements: Enter a URL or up to 66 URLs. Wildcard domain names are supported. Enter up to 1,000 characters. Separate URLs with commas (,). Start with http:// or https://. If this is set to *, no URLs are allowed after the wildcard (*). Domain names with port numbers are supported. The value can be null, which is case-insensitive.	Example 1: https://www.example.com Example 2: * Example 3: https://www.example.com,https://www.example01.com,https://*.abc.com
   Access-Control-Allow-Methods	Specifies the HTTP request methods that can be used in a CORS request. Value requirements: Multiple methods can be configured at the same time. Separate them with commas (,).	GET,POST,HEAD
   Access-Control-Max-Age	Specifies how long to cache the pre-check results of CORS requests on specific resources. Value requirements: This value is expressed in seconds and ranges from 0 to 1,000,000,000.	86400
   Access-Control-Expose-Headers	Specifies the response header information visible to the client for a CORS request. Value requirements: Enter 1 to 256 characters. Multiple headers can be configured at the same time. Separate them by commas (,).	Content-Length,Content-Encoding
   Access-control-allow-headers	Specifies the fields that can be carried in a cross-domain request. Value requirements: Enter 1 to 1,000 characters. Multiple fields can be configured at the same time. Separate them by commas (,).	X- Custom-Header
   Custom	Specifies the custom response header for a CORS request. Value requirements: Enter 1 to 1,000 characters, which can contain letters, digits, spaces, and the following special characters: .-_*#!&+|^~'"/:;,=@?<> NOTE: If the custom parameter is Cache-Control, the value can be max-age=*** (*** is a number), private, no-cache, no-store, or public. Only one value can be configured.	x-testcdn

8. Click OK.

Constraints

• If your domain name has special configurations, Content-Type, Expires, or Cache-Control cannot be configured.
• The following response headers can be modified but cannot be deleted.

  Content-Base	Content-Disposition
  Server	Content-Language
  Cache-Control	Expires
  Content-Type	-

• CDN does not support the following response headers:

  A_Dynamic	If-None-Match	Sec-WebSocket-Origin	X-Forward-Peer
  Accept-Ranges	If-Range	Sec-WebSocket-Protocol	X-Forward-Type
  X-Forward-Ip	Keep-Alive	Sec-WebSocket-Version	X-Forward-Uri
  Allow	Key	Set-Cookie	X-Forwarded-For
  Authentication-Info	Last-Modified	Tcp-Retrans	X-IP-Region
  Authorization	Link	Title	X-IP-Region-CN
  X-Forward-Measured	Location	Transfer-Encoding	X-Ip-Blackwhite-List
  Cdn-Qos	Max-Forwards	Upgrade	X-Local-Ip
  Cdn-Server-Ip	Meter	Vary	X-Log-Url
  Cdn-Src-Ip	Mime-Version	Via	X-MAA-Alias
  Conf-Err-Host	Negotiate	WWW-Authenticate	X-MAA-Auth
  Conf-File	Origin	Warning	X-Max-Conns
  Conf-File-List	Partition-Block-Size	Ws-Hdr	X-Mem-Url
  Conf-Option	Pragma	WsTag	X-Mgr-Traffic
  Conf-Other	Proxy-Authenticate	X-Accelerator-Vary	X-Miss-Rate-Limit
  Connection	Proxy-Authentication-Info	X-Appa	X-Miss-Times-Limit
  Content-Encoding	Proxy-Authorization	X-Appa-Origin	X-No-Referer
  Content-Length	Proxy-Connection	X-Black-List	X-Query-Key
  Content-Location	Proxy-Support	X-Bwctrl-Limit	X-Rate-Limit
  Content-MD5	Public	X-Bwctrl-Para	X-Refresh-Pattern
  Content-Range	Purge-Domain	X-Cache	X-Request-Id
  Sec-WebSocket-Nonce	Purge-Extra	X-Cache-2	X-Request-Uri
  Date	Range	X-Cache-Lookup	X-Request-Url
  Dynamic	Request-Range	X-Cacheable	X-Resp-Time
  ETag	Retry-After	X-Cdn-Src-Port	X-Rewrite-Url
  Error	Sec-WebSocket-Accept	X-Client-Ip	X-Squid-Error
  Expect	Sec-WebSocket-Draft	X-DNS-Time	X-Times-Limit
  If-Modified-Since	Sec-WebSocket-Extensions	X-Denyattack-Dynconf	X-Url-Blackwhite-List
  From	Sec-WebSocket-Key	X-Error-Status	X-Via-CDN
  Front-End-Https	Sec-WebSocket-Key1	X-Error-URL	X-White-List
  Host	Sec-WebSocket-Key2	X-Forward-Host	-
  If-Match	Sec-WebSocket-Location	-	-