errcode40035errmsg不合法的参数

求助：
python获取token正常，就是上传图片一直报错，返回不合法的参数
def upload(accessToken):
  boundary = '----------%s' % hex(int(time.time() * 1000))
  data = []
  fr=open(r'/tmp/1.png','rb')
  data.append('--%s--\r\n' % boundary)    
  data.append('Content-Disposition: form-data; name="%s"; filename="1.png"' % 'media')
  data.append('Content-Type: %s\r\n' % 'application/octet-stream')
  # data.append('Content-Length: %s\r\n' % '99159')
  data.append(fr.read())
  fr.close()
  data.append('--%s--\r\n' % boundary)    
  http_url='https://oapi.dingtalk.com/media/upload?access_token=' + accessToken +'&type=image'
  http_body='\r\n'.join(data)
  print http_body
  req=urllib2.Request(http_url.encode('utf-8'),http_body)
  req.add_header('Content-Type', 'multipart/form-data; boundary=%s' % boundary)
  # print req.headers
  resp = urllib2.urlopen(req, timeout=5)
  # print resp
  qrcont=resp.read().decode('utf-8')
  print qrcont