HTTP 403使用mechanize检索robots.txt时出错

Question

此shell命令成功

$ curl -A "Mozilla/5.0 (X11; Linux x86_64; rv:18.0) Gecko/20100101 Firefox/18.0 (compatible;)" http://fifa-infinity.com/robots.txt

并打印robots.txt。省略user-agent选项会导致服务器出现403错误。检查robots.txt文件会发现允许对http://www.fifa-infinity.com/board下的内容进行爬网。但是，以下代码会失败(python代码)：

import logging
import mechanize
from mechanize import Browser

ua = 'Mozilla/5.0 (X11; Linux x86_64; rv:18.0) Gecko/20100101 Firefox/18.0 (compatible;)'
br = Browser()
br.addheaders = [('User-Agent', ua)]
br.set_debug_http(True)
br.set_debug_responses(True)
logging.getLogger('mechanize').setLevel(logging.DEBUG)
br.open('http://www.fifa-infinity.com/robots.txt')

在我的控制台上的输出是：

No handlers could be found for logger "mechanize.cookies"
send: 'GET /robots.txt HTTP/1.1\r\nAccept-Encoding: identity\r\nHost: www.fifa-infinity.com\r\nConnection: close\r\nUser-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:18.0) Gecko/20100101 Firefox/18.0 (compatible;)\r\n\r\n'
reply: 'HTTP/1.1 403 Bad Behavior\r\n'
header: Date: Wed, 13 Feb 2013 15:37:16 GMT
header: Server: Apache
header: X-Powered-By: PHP/5.2.17
header: Vary: User-Agent,Accept-Encoding
header: Connection: close
header: Transfer-Encoding: chunked
header: Content-Type: text/html
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/home/moshev/Projects/forumscrawler/lib/python2.7/site-packages/mechanize/_mechanize.py", line 203, in open
    return self._mech_open(url, data, timeout=timeout)
  File "/home/moshev/Projects/forumscrawler/lib/python2.7/site-packages/mechanize/_mechanize.py", line 255, in _mech_open
    raise response
mechanize._response.httperror_seek_wrapper: HTTP Error 403: Bad Behavior

奇怪的是，在没有设置用户代理的情况下使用curl会导致"403:禁止“，而不是"403:坏行为”。

我是不是做错了什么，或者这是mechanize/urllib2中的一个bug？我不明白简单地获取robots.txt怎么会是“坏行为”？

Answer 1

通过实验验证，您需要添加一个Accept标头来指定可接受的内容类型(只要存在"Accept“标头，任何类型都可以)。例如，更改后即可正常工作：

br.addheaders = [('User-Agent', ua)]

至：

br.addheaders = [('User-Agent', ua), ('Accept', '*/*')]