maybe endless loop in fileupload with firefox

[aiomaster]

We have detected an issue using jquery file upload and a github version of rack.
Problem is, that larger fileuploads (larger than 50M) with firefox stop working in the rack middleware and produce 100% CPU load, so it looks like an infinit loop.
We have traced the commit that introduced the behaviour in rack: 534ef35

The interesting stuff is, that the same files work in chrome but not in firefox.
So we compared the Request-Headers and the main difference is, that firefox uses other boundaries in the Content-Type-Header than Chrome.

Example-Header in Chrome:
Content-Type: multipart/form-data; boundary=----WebKitFormBoundarydEXn76YwP9nKSKO3

Example-Header in Firefox:
Content-Type: multipart/form-data; boundary=---------------------------100673423314366417001080588648

This is just a guessing, that the boundary parsing is involved here.

[aiomaster]

Ok it boils down to this line, that does not return somehow:

rack/lib/rack/multipart/parser.rb

Line 268 in 5559676

if @sbuf.check_until(@body_regex) # check but do not advance the pointer yet

The content of the @body_regex is:

/(.*?)(
)?\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-84208446911303861091947234149(
|--)/m

I don't know if that helps in a way.

[jeremyevans]

Fixed by #1309