class Excon::Connection

def setup_proxy
  unless @data[:scheme] == UNIX
    if no_proxy_env = ENV["no_proxy"] || ENV["NO_PROXY"]
      no_proxy_list = no_proxy_env.scan(/\*?\.?([^\s,:]+)(?::(\d+))?/i).map { |s| [s[0], s[1]] }
    end
    unless no_proxy_env && no_proxy_list.index { |h| /(^|\.)#{h[0]}$/.match(@data[:host]) && (h[1].nil? || h[1].to_i == @data[:port]) }
      if @data[:scheme] == HTTPS && (ENV.has_key?('https_proxy') || ENV.has_key?('HTTPS_PROXY'))
        @data[:proxy] = ENV['https_proxy'] || ENV['HTTPS_PROXY']
      elsif (ENV.has_key?('http_proxy') || ENV.has_key?('HTTP_PROXY'))
        @data[:proxy] = ENV['http_proxy'] || ENV['HTTP_PROXY']
      end
    end
    case @data[:proxy]
    when String
      uri = URI.parse(@data[:proxy])
      unless uri.host && uri.port && uri.scheme
        raise Excon::Errors::ProxyParseError, "Proxy is invalid"
      end
      @data[:proxy] = {
        :host       => uri.host,
        :port       => uri.port,
        :scheme     => uri.scheme,
      }
      if uri.password
        @data[:proxy][:password] = uri.password
      end
      if uri.user
        @data[:proxy][:user] = uri.user
      end
    end
    if @data.has_key?(:proxy) && @data[:scheme] == 'http'
      @data[:headers]['Proxy-Connection'] ||= 'Keep-Alive'
      # https credentials happen in handshake
      if @data[:proxy].has_key?(:user) || @data[:proxy].has_key?(:password)
        user, pass = Utils.unescape_form(@data[:proxy][:user].to_s), Utils.unescape_form(@data[:proxy][:password].to_s)
        auth = ['' << user << ':' << pass].pack('m').delete(Excon::CR_NL)
        @data[:headers]['Proxy-Authorization'] = 'Basic ' << auth
      end
    end
  end
end