citrix-enum-servers-xml can return error

[tatulea]

Describe the bug
I have run the following scan:

NSE: citrix-enum-servers-xml against wordpress.com (192.0.78.9:443) threw an error!
/usr/local/bin/../share/nmap/nselib/citrixxml.lua:50: bad argument #1 to 'char' (value out of range)
stack traceback:
	[C]: in function 'string.char'
	/usr/local/bin/../share/nmap/nselib/citrixxml.lua:50: in function 'citrixxml.decode_xml_document'
	(...tail calls...)
	...al/bin/../share/nmap/scripts/citrix-enum-servers-xml.nse:37: in function <...al/bin/../share/nmap/scripts/citrix-enum-servers-xml.nse:35>
	(...tail calls...)

It seems like the citrixxml.lua has an error. For the scan run above the value of escaped_val is — and the value of hexval is 8212, which can not to converted to char using string.char.

Version info (please complete the following information):

• OS: Ubuntu 20.04
• Output of nmap --version: 7.80

[nnposter]

Thank you for reporting the issue. A fix has been committed as r38146. The implemented change will leave character references with codepoints higher than 255 untouched.