Track progress of an HTTP GET request while following HTTP Redirections

get_request_progress.rb

def fetch(link, level, options = {})
  raise RuntimeError, 'HTTP redirect too deep' if level == 0
  
  buf = OpenURI::Buffer.new
 
  uri = URI.parse(link)
  http = Net::HTTP.new(uri.host, uri.port)
  response = nil
  http.start {
    req = Net::HTTP::Get.new(uri.request_uri)
    http.request(req) { |resp|
      response = resp
      if options[:content_length_proc] && Net::HTTPSuccess === response
        if response.key?('Content-Length') && 0 < response['Content-Length'].to_i
          options[:content_length_proc].call(response['Content-Length'])
        else
          options[:content_length_proc].call(nil)
        end
      end
      response.read_body {|str|
        buf << str
        if options[:progress_proc] && Net::HTTPSuccess === response
          options[:progress_proc].call(buf.size)
        end
      }
    }
  }
 
  io = buf.io
  io.rewind
  io.status = [response.code, response.message]
  response.each {|name,value| buf.io.meta_add_field name, value }
  case response
  when Net::HTTPSuccess
       Net::HTTPOK
    return response, io.read
  when Net::HTTPMovedPermanently, # 301
       Net::HTTPFound, # 302
       Net::HTTPSeeOther, # 303
       Net::HTTPTemporaryRedirect # 307
    return fetch(response['location'], level - 1, options)
  else
    raise OpenURI::HTTPError.new(io.status.join(' '), io)
  end
 
  puts "WARN!!! shouldn't be here"      
 
end