Citrix Systems 9.2 manual Http.res.header.myheader

42Citrix NetScaler Policy Configuration and Reference Guide

•The prefix http.req.url designates an HTTP URL in URL- encoded format.

•SERVER: Identifies an element in the server that is either processing a request or sending a response.

•SYS: Identifies a characteristic of the NetScaler that is processing the traffic.

•TARGET:Represents all the strings that result from a search in the target text. This prefix can be used only in the string expression that specifies replacement text in a rewrite action. The expression that is used to search the target text must be a regular expression, and the type of action must be

REPLACE_ALL, INSERT_AFTER_ALL, or INSERT_BEFORE_ALL. Any operator that is used with the TARGET prefix operates on all the strings that are found in the target text.

For example, if a search that uses a regular expression finds n occurrences of the specified string, and if the action type is REPLACE_ALL, the expression TARGET.TO_UPPER changes the case of all n occurrences of the string to upper case.

Note: DNS policies support only SYS, CLIENT, and SERVER objects.

In addition, in the Access Gateway, the Clientless VPN function can use the following types of prefixes:

•TEXT: Identifies any text element in a request or a response.

•TARGET: Identifies the target of a connection.

•URL: Identifies an element in the URL portion of an HTTP request or response.

As a general rule of thumb, any expression prefix can be a self-contained expression. For example, the following prefix is a complete expression that returns the contents of the HTTP header specified in the string argument (enclosed in quotation marks):

http.res.header.("myheader")

Or you can combine prefixes with simple operations to determine TRUE and FALSE values. For example, the following returns a value of TRUE or FALSE:

http.res.header.("myheader").exists

You can also use complex operations on individual prefixes and multiple prefixes within an expression, as in the following example:

http.req.url.length + http.req.cookie.length <= 500