gistfile1.rb

def build_multipart_post_data(params, boundary)
  enter     = "\r\n"
  data      = ''

  params.each do |k,v|
    next if v.nil?
    data << '--' + boundary + enter
    data << %Q[Content-Disposition: form-data; name="#{k.to_s}"]

    if k.to_s == 'file'
      filename = v.split('/').last
      mimetype = file_type[v.split('.').last]

      data << %Q[; filename="#{filename}"] + enter
      data << %Q[Content-Type: application/octet-stream] + enter + enter
      data << File.read(v) + enter
    else
      data << enter + enter
      data << v + enter
    end 
  end
 
  data << '--' + boundary + '--'
end