URI::Generic

 
               # File open-uri.rb, line 709
def find_proxy
  name = self.scheme.downcase + '_proxy'
  proxy_uri = nil
  if name == 'http_proxy' && ENV.include?('REQUEST_METHOD') # CGI?
    # HTTP_PROXY conflicts with *_proxy for proxy settings and
    # HTTP_* for header information in CGI.
    # So it should be careful to use it.
    pairs = ENV.reject {|k, v| /\Ahttp_proxy\z/ !~ k }
    case pairs.length
    when 0 # no proxy setting anyway.
      proxy_uri = nil
    when 1
      k, _ = pairs.shift
      if k == 'http_proxy' && ENV[k.upcase] == nil
        # http_proxy is safe to use because ENV is case sensitive.
        proxy_uri = ENV[name]
      else
        proxy_uri = nil
      end
    else # http_proxy is safe to use because ENV is case sensitive.
      proxy_uri = ENV.to_hash[name]
    end
    if !proxy_uri
      # Use CGI_HTTP_PROXY.  cf. libwww-perl.
      proxy_uri = ENV["CGI_#{name.upcase}"]
    end
  elsif name == 'http_proxy'
    unless proxy_uri = ENV[name]
      if proxy_uri = ENV[name.upcase]
        warn 'The environment variable HTTP_PROXY is discouraged.  Use http_proxy.'
      end
    end
  else
    proxy_uri = ENV[name] || ENV[name.upcase]
  end

  if proxy_uri && self.hostname
    require 'socket'
    begin
      addr = IPSocket.getaddress(self.hostname)
      proxy_uri = nil if /\A127\.|\A::1\z/ =~ addr
    rescue SocketError
    end
  end

  if proxy_uri
    proxy_uri = URI.parse(proxy_uri)
    name = 'no_proxy'
    if no_proxy = ENV[name] || ENV[name.upcase]
      no_proxy.scan(/([^:,]*)(?::(\d+))?/) {|host, port|
        if /(\A|\.)#{Regexp.quote host}\z/ =~ self.host &&
           (!port || self.port == port.to_i)
          proxy_uri = nil
          break
        end
      }
    end
    proxy_uri
  else
    nil
  end
end