content-type をリダイレクト考慮して取得

fuck.rb

def head_and_track_redirect(uri, limit = 10)
  raise if limit == 0
  h = Net::HTTP.new(uri.host, uri.port) 
  if uri.scheme == 'https'
    h.use_ssl = true 
    h.verify_mode = OpenSSL::SSL::VERIFY_NONE
  end
  h.start{|http|
    path = uri.path
    path += "?#{uri.query}" unless uri.query.blank?
    response = http.head(path)
    case response
    when Net::HTTPSuccess
      return response
    when Net::HTTPRedirection
      head_and_track_redirect URI.parse(response['location']), limit-1
    end
  }
end

def check_mime_type(url)
  uri = URI.parse url
  response = head_and_track_redirect(uri)
  return response['content-type']
end