生成多部分边界 [英] Generating multipart boundary

问题描述

我正在编写一个脚本，该脚本将文件上传到需要多个部分请求的cgi脚本，例如HTML页面上的表单. boundary是唯一的令牌，用于注释请求正文中的文件内容.这是一个示例正文:

I'm writing a script that uploads a file to a cgi script that expects a multipart request, such as a form on a HTML page. The boundary is a unique token that annotates the file contents in the request body. Here's an example body:

--BOUNDARY
Content-Disposition: form-data; name="paramname"; filename="foo.txt"
Content-Type: text/plain

... file contents here ...
--BOUNDARY--

出于明显的原因，boundary不能出现在文件内容中.

The boundary cannot be present in the file contents, for obvious reasons.

我应该怎么做才能创建一个唯一的边界?我应该生成一个随机字符串，检查它是否在文件内容中，如果存在，请生成一个新字符串，冲洗并重复直到我拥有唯一的字符串为止?还是相当随机的令牌"(例如，时间戳，进程ID等的组合)就足够了?

What should I do in order to create an unique boundary? Should I generate a random string, check to see if it is in the file contents, and if it is, generate a new, rinse and repeat, until I have a unique string? Or would a "pretty random token" (say, combination of timestamp, process id, etc) be enough?

推荐答案

如果使用足够随机的东西(例如GUID)，则不需要搜索有效载荷来检查边界的别名.像这样:-

If you use something random enough like a GUID there shouldn't be any need to hunt through the payload to check for an alias of the boundary. Something like:-

---- == NextPart_3676416B-9AD6-440C-B3C8-FC66DDC7DB45
标头:....

----=NextPart_3676416B-9AD6-440C-B3C8-FC66DDC7DB45
Header:....

有效载荷
---- = NextPart_3676416B-9AD6-440C-B3C8-FC66DDC7DB45-

Payload
----=NextPart_3676416B-9AD6-440C-B3C8-FC66DDC7DB45--

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