module Excon::Utils

def headers_hash_to_s(headers)
  headers_str = String.new
  headers.each do |key, values|
    if key.to_s.match(/[\r\n]/)
      raise Excon::Errors::InvalidHeaderKey.new(key.to_s.inspect + ' contains forbidden "\r" or "\n"')
    end
    [values].flatten.each do |value|
      if value.to_s.match(/[\r\n]/)
        # Don't include the potentially sensitive header value (i.e. authorization token) in the message
        raise Excon::Errors::InvalidHeaderValue.new(key.to_s + ' header value contains forbidden "\r" or "\n"')
      end
      headers_str << key.to_s << ': ' << value.to_s << CR_NL
    end
  end
  headers_str
end