342977 - XMLHttpRequest: status 200 (OK) reported instead of 304 (Not modified)

Status: RESOLVED INVALID

(Core :: XML, defect)

Description

[Wing Yung]

User-Agent:       Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8.0.4) Gecko/20060508 Firefox/1.5.0.4
Build Identifier: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8.0.4) Gecko/20060508 Firefox/1.5.0.4

Even when a server responds to a XMLHttpRequest with status 304, the status property is 200. I want to be able to take additional action if the property is 200 (which should signify that the XMLHttpRequest fetched something that has been modified).

Reproducible: Always

Steps to Reproduce:
1. Create a XMLHttpRequest that hits a URL that returns status 304.
2. Get the status of the XMLHttpRequest


Actual Results:  
The status was 200.

Expected Results:  
The status should be 304.

Comment 1

[:Gavin Sharp [email: [e-mail]]]

Bug 305420 would seem to indicate that this used to work, at the very least. Are you sure the server is responding with a 304?

A malformed response status will also result in a status==200, could that be the problem?

http://bonsai.mozilla.org/cvsblame.cgi?file=mozilla/netwerk/protocol/http/src/nsHttpResponseHead.cpp&rev=1.42.2.1#166

Comment 2

[Wing Yung]

Thank you for the quick response.

I'm using the LiveHTTPHeaders Firefox extension to view the headers.

The status line reported is: 

HTTP/1.x 304 Not Modified

(In reply to comment #1)
> Bug 305420 would seem to indicate that this used to work, at the very least.
> Are you sure the server is responding with a 304?
> 
> A malformed response status will also result in a status==200, could that be
> the problem?
> 
> http://bonsai.mozilla.org/cvsblame.cgi?file=mozilla/netwerk/protocol/http/src/nsHttpResponseHead.cpp&rev=1.42.2.1#166
> 

Comment 3

[timeless]

does this happen if you don't have livehttpheaders installed? i've begun to distrust this creature, i'd suggest temporarily testing w/o it, or installing a logging proxy (there's one written in java which isn't too bad if you don't look at it for more than a few minutes).

Comment 4

[Wing Yung]

Attachment: test html file

When I click the button, "status 200" gets printed out, never "status 304".

Comment 5

[Christian :Biesinger (don't email me, ping me on IRC)]

cache is transparent to its users, this is invalid IMO. (in 1.0.x XMLHttpRequest accidentally didn't use the cache, so the cache entry didn't mess with the server-sent status)

Comment 6

[Darin Fisher]

yeah, the current behavior is valid.  it's not a bug that you can't know when the item was taken from the cache vs. being fetched over the network.  at most, this is a feature request, which should be taken up with the w3c ([e-mail])

Comment 7

[Wing Yung]

thanks for everyone's responses.

whether this is a bug or not sounds like it's up for debate - the web server returns status 304 and the XMLHttpRequest says that the status is 200. not sure whether the 304 response should be reinterpreted as 200.

i am interested in this because i'd like to be able to run some additional requests only if the status of the first GET is 200. 

Comment 8

[nrlz]

With the patch from bug 331825 you can work around this by setting the if-modified-since header field.

Comment 9

[Magnus Melin [:mkmelin]]

->INVALID per comment 5, 6. Also workaround is available per comment 8.