Custom headers possible with URLRequest/URLStream using method GET?

Question

Quite simple really:

var req:URLRequest=new URLRequest();
req.url="http://somesite.com";
var header:URLRequestHeader=new URLRequestHeader("my-bespoke-header","1");
req.requestHeaders.push(header);
req.method=URLRequestMethod.GET;
stream.load(req);

Yet, if I inspect the traffic with WireShark, the my-bespoke-header is not being sent. If I change to URLRequestMethod.POST and append some data to req.data, then the header is sent, but the receiving application requires a GET not a POST.

The documentation mentions a blacklist of headers that will not get sent. my-bespoke-header is not one of these. It's possibly worth mentioning that the originating request is from a different port on the same domain. Nothing is reported in the policyfile log, so it seems unlikely, but is this something that can be remedied by force loading a crossdomain.xml with a allow-http-request-headers-from despite the fact that this is not a crossdomain issue? Or is it simply an undocumented feature of the Flash Player that it can only send custom headers with a POST request?

Answer 1

From what I can gather, it seems like your assumption about the lack of custom headers support for HTTP GET is indeed an undocumented feature (or a bug?) in the standard libraries.

In any case, you might want to see if as3httpclient would fit your purposes and let you work around this issue. Here's a relevant snippet from a post in the blog of the developer of this library:

"I was not able to set the header of a HTTP/GET request. Macromedia Flash Player allows you set the header only for POST requests. I discussed this issues with Ted Patrick and he told me how I can us Socket to achieve the desired and he was very kind to give a me code-snippet, which got me started."

Answer 2

If this limitation was undocumented at one time, that's no longer the case. See:

http://livedocs.adobe.com/flex/3/langref/flash/net/URLRequest.html#requestHeaders

"[...] Due to browser limitations, custom HTTP request headers are only supported for POST requests, not for GET requests. [...]"

Answer 3

yes, there is really a browser limitation. when i use same swf in browser it doesn't send custom headers but when i run it as flash player alone it does send custom headers. does anyone know what is the reason for browser doesn't support this and limit flash in browser to send custom headers?