CGI Server application from first principles

Ruby on the Web example from a Well House Consultants training course
More on Ruby on the Web [link]

This example is described in the following article(s):
• Ruby on the web - a simple example using CGI - [link]

Source code: south.rb Module: R114

#!/usr/bin/env ruby

# CGI Server application from first principles

# For CGI, need to tell web server the type of content
# and to terminate the headers with a blank line
print "Content-type: text/html\n\n"

# Output the HTML
puts "<html><head><title>Hello ;-)</title></head><body bgcolor=#FDEDCA>"
puts "<h1>Ruby and CGI</h1>"
puts "Two pints of lager and a packet of <b>pork scratchings</b><br><br>"

pairs = ENV["QUERY_STRING"].split(/&/)
invals = {}
for twosome in pairs
        name, value = twosome.split(/=/)

        # URL decoding

        value.gsub! /\+/," "
        value.gsub! (/%(..)/) { "%c" % $1.to_i(16) }

        invals[name] = value
end

if invals["search"]
        gotten = 0
        counter = 0

        # Only allow limited range of characters in search string

        if invals["search"] =~ /^[-\w\s]+$/
                fh = File.new("/Library/WebServer/live_html/lua52/railstats.txt")
                print "Looking for #{invals["search"]}<br />"
                print "<br><table border=1>"
                while lyne = fh.gets
                        if lyne =~ /#{invals["search"]}/i
                                print "<tr><td>"
                                # Note - our data does NOT contain any < or & characters!
                                # otherwise we would need to gsub like in the "else" section
                                print lyne.gsub /\t/,"</td><td>"
                                print "</td></tr>"
                                gotten += 1
                        end
                        counter += 1
                end
                print "</table>"
                print "<br />Matched #{gotten} out of #{counter}"
        else

                # Echoing back user input that may include nasty injections - sanitise them!

                invals["search"].gsub! /&/,"&"
                invals["search"].gsub! /</,"<"
                print "Looking for #{invals["search"]} - not allowed due to invalid character for search<br />"
        end

else

        print "Results will appear here"
end

puts "<hr /><form>Whatcha Wanalook 4 <input name=search></form>"
puts "<br/>Copyright, contacts, links etc</body></html>"

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* Ruby Programming
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