116 Citrix NetScaler Policy Configuration and Reference Guide
Prefixes for HTTP Headers

The following table describes expression prefixes that extract HTTP headers.

Prefixes That Extract HTTP Headers
HTTP Header Prefix Description
HTTP.REQ.HEADER("header_name") Returns the contents of the HTTP header
specified by the header_name argument. The
header name cannot exceed 32 characters.
Note that this prefix returns the value from the
Host header by default. To use this value as a
host name you need to typecast it as follows:
http.req.header("host").typecast_
http_hostname_t
For more information on typecasting, see
“Transforming Text and Numbers into
Different Data Types,” on page 169.
HTTP.REQ.FULL_HEADER("header_
name") Returns the contents of the HTTP header
specified by the header_name argument,
including the terminating \r\n\r\n. The
header name cannot exceed 32 characters.
HTTP.REQ.DATE Returns the contents of the HTTP Date
header.The following date formats are
recognized:
RFC822. Sun, 06 Jan 1980 8:49:37 GMT
RFC850. Sunday, 06-Jan-80 9:49:37 GMT
ASCII TIME. Sun Jan 6 08:49:37 1980
To evaluate a Date header as a date object, see
“Advanced Expressions: Working with
Dates, Times, and Numbers,” on page 95.
HTTP.REQ.COOKIE (Name/Value List) Returns the contents of the
HTTP Cookie header.
HTTP.REQ.TXID Returns the HTTP transaction ID. The value
is a function of an internal transaction
number, system boot time and system MAC
address.
HTTP.RES.HEADER("header_name") Returns the contents of the HTTP header
specified by the header_name argument. The
header name cannot exceed 32 characters.
HTTP.RES.FULL_HEADER("header_
name") Returns the contents of the HTTP header
specified by the header_name argument,
including the terminating \r\n\r\n. The
header name cannot exceed 32 characters.