Hi
On 05/12/11 15:39, Benson Margulies wrote:
On Mon, Dec 5, 2011 at 10:15 AM, Sergey Beryozkin<sberyoz...@gmail.com> wrote:
On 05/12/11 13:23, Benson Margulies wrote:
On Mon, Dec 5, 2011 at 7:15 AM, Sergey Beryozkin<sberyoz...@gmail.com>
wrote:
Hi Benson, all
At the moment the in CORS filter returns 'null' during a preflight check,
whenever some check fails, which means that most likely an HTTP status
code
will be returned to do with failure at the selection algorithm stage, but
that status code may not necessarily to be the one expected by the CORS
client ? I'm wondering of we should return some more specific HTTP status
code instead of depending on the runtime to eventually fail this
preflight
request.
Maybe I don't understand filters.
The cors spec never, ever, calls for failing the overall HTTP request.
It calls for adding extra headers if the request is good, and not
adding them if it is bad, and otherwise leaving it alone.
Are you referring to the actual request which follows a preflight request ?
I'm looking at [1] and I'm not sure how does the client (browser ?) can
decide that a preflight request was not successful.
The filter returns Response.ok().build() in the end of the preflight check,
which indeed will let the out CORS filter to finalize the preflight response
but in cases where the preflight check was not good then I believe a random
HTTP error status will be returned depending on where the selection
algorithm fails afterwards (may be it is a path mismatch or unexpected
verb/content-type/accept-type).
Yes, I see the problem here, but I don't quite know what to do.
Preflight seems to be carefully defined to get along with any existing
OPTIONS handling that is going on. So, if the programmer has an
OPTIONS method that matches, the situation is supposed to be the same
as the situation with simple requests and, say, GET handlers.
Will the JAX-RS code ever dispatch OPTIONS to a function that doesn't
have an @OPTIONS?
No
If so, I think that the problem here is more
serious. If not, I'm not sure we have a problem. I'm also not sure
that the CORS spec exactly makes sense, and I'm going to send them
some email.
My understanding now is that the client decides on whether a preflight
failed or not by checking the response headers.
Our in filter adds them one by one, or rather it prepares the info for
the out filter to decide what to add in case of preflights being processed.
Thus if the client always expects OK and only uses headers to figure out
what happened then the in filter should just always return Response.OK,
the earlier it does so the less info it will save for the response
filter and the less chance the response filter will have to provide all
the expected headers - but some clarifications at the spec level will help
Cheers, Sergey
Cheers, Sergey
Now, we could design a unified JAX-RS security feature that
incorporated CORS as part of its job. It could, if asked, fail
requests if they failed to meet the requirements.
[1] http://www.w3.org/TR/cors/
The other question which we've discussed with Benson is what to do in the
case like this:
@Path("/somepath")
public class Resource {
@GET
@Produces("application/xml")
public Book getXML() {}
@GET
@Produces("application/json")
public Book getXML() {}
}
The info CORS provides is sufficient enough to select either of the the
above 2 methods thus the question is what to do at the preflight check.
In this case we thought we can expect a CrossResourceSharingAnnotation
being
added to the 'good' method, or even to the all of them, possibly uing a
class-level annotation:
@Path("/somepath")
@CrossResourceSharingAnnotation(...)
public class Resource {
@GET
@Produces("application/xml")
public Book getXML() {}
@GET
@Produces("application/json")
public Book getXML() {}
}
or in case of POST:
@Path("/somepath")
public class Resource {
@POST
@Consumes("application/xml")
@CrossResourceSharingAnnotation(...)
public void addXML(Book) {}
@POST
@Consumes("multipart/form-data")
public void upload(MultipartBody) {}
}
We can also think of some configuration tricks.
Ex, if the consumer does know that only an upload POST method is 'valid'
then we can configure a CORS filter with the acceptType value which will
be
passed on to the JAXRS runtime to confirm that such a method actually
exists
For the record, as agreed with Benson, I updated the filter to delegate
to
the runtime to find a valid matching method during a preflight check
which
is more secure than depending on the custom annotation
Cheers, Sergey
--
Sergey Beryozkin
Talend Community Coders
http://coders.talend.com/
Blog: http://sberyozkin.blogspot.com
--
Sergey Beryozkin
Talend Community Coders
http://coders.talend.com/
Blog: http://sberyozkin.blogspot.com
