parsing a line in nmap's output

I am using nmap::parser to parse the results of an nmap scan.  One thing this module does not provide for is obtaining information about hosts that don't respond to a ping. Nmap reports these hosts as "up", and in the output file the ports scanned are listed as "extraports".  I can get the number of these ports, but not the actual ports themselves.  In order to to do, I am parsing the args variable, which is what I need help with.  This is the content of a sample args variable:
      args = "nmap -sS -P0 -vv -p21,23,25,80 -O ...."

The critical part is here is that I want to search/grep for "-p" in the variable $args, then read everything past the "-p" to the next space.  So in the example above my new variable would contain "21,23,25,80".  I'll then split that via the comma.  What I can't figure out is how to search/grep for "-p" in a variable, and read thru until I hit a space.  Can anyone help me with that in perl?  Thank you.