Constants MAX_MULTIPART_LENGTH in cgi/core.rb
Reported by Andreas Kraus via gmail.
I try to understand why the
MAX_MULTIPART_LENGTHis a Constant and i can't change it.
If i uload a Multipart file which is larger than 128 MB raise an error "too large multipart data.",
but why i can't change this value to upload larger files.
The Constant comes with this Change:
The only sense i see, is that the Author of cgialt uses max 128MB files und build in this Constant ...
I would like to know why this constant is in place and how to change it's behaviour.
My requirement is to upload files larger than the given limit of 128MB.
#4 Updated by Leif Eriksen about 1 year ago
From my reading of RFC-1867, this constant/constraint is not required.
If a server detects space constraints for an upload, it can terminate the connection at any time.
Servers can indicate a maximum length via the MAXLENGTH attribute, but clients are not required to limit themselves to it.
Clients are generally required to supply an overall content-length for the upload - servers can act on that at the commencement of transmission, or terminate at a later time according to whatever policy has been set up.
There is no reason, that I can see, to artificially limit the upload size on the client side, the server can accept or reject at any time.
I will raise a git pull request from my commit https://github.com/leriksen/ruby/commit/77f3a6bbb92e3f395851e7998556d7df160f4da1
#5 Updated by Yusuke Endoh about 1 year ago
There is no reason, that I can see, to artificially limit the upload size on the client side
I think that MAX_MULTIPART_LENGTH is the limit on the server side.
The limit itself is actually required to prevent shortage of server resource.
I agree that the limit should be configuable by users.
In fact, the author of cgialt, Makoto Kuwata, said in the proposal,
For simplicity, the limit is specified by a constant,
but if needed, please use class variable or instance variable
to specify it.
So, what we need is not a patch that just removes the check,
but a patch that enables a user to configure it.
Yusuke Endoh firstname.lastname@example.org
#6 Updated by Leif Eriksen about 1 year ago
OK, yeah I got the wrong end of the conversation - CGI is all about the server side.....
OK an idea comes to mind
A new option in the options_hash in the constructor - currently only :tag_maker and :accept_charset are defined
The multipart handling is in the private method initialize_query(), which is only referenced in the constructor. So the only opportunity to set this up is from CGI.new.
I propose a new option in the initialize method - :max_multipart_length
It will default to the old value of 128 *1024 *1024 bytes, and can take as a value either a simple integer scalar, or a lambda. A lambda will allow the user to use more complex logic than a simple integer to determine the size of multipart forms to accept.
Would that work ?
#8 Updated by Leif Eriksen about 1 year ago
Well I'm only trying to solve the problem in the CGI library, not the underlying web server, and the only place that will reference MAX_MULTIPART_LENGTH is in the request parsing. That happens only in the CGI constructor. I dont think I should stray too far from that use-case.
If a user does not specify a MAX_MULTIPART_LENGTH in the constructor, it will default to 128 * 1024 *1024 bytes. Otherwise a user can specify a new length, or a lambda that will calculate it at parse time (say there is a need to query the file system, or get a size from a users account etc).
I will add a getter/setter pair, though I cant think of a use-case for them. But Makoto did mention using an instance variable, so might as well complete that part.
I'll go ahead with this plan, and note the commit/pull-request in my next comment.
#10 Updated by Leif Eriksen about 1 year ago
Used the pattern for passing accept_charset, which can be read/modified by a class method, and read by an instance method. That seems reasonable, let me know if a setter instance methods is also required, will do as a separate piece.
I updated the multipart tests to also take an options hash, to make constructing the CGI instance under test a little easier.