Wireshark · Wireshark-dev: [Wireshark-dev] Correct way of adding a HTTP subdissector on port 80 with no content type?

[Tarjei Knapstad <tarjei.knapstad@xxxxxxxxx>]

I'm having problems getting my subdissector to run on HTTP packets on
port 80 that does not include a content type in the HTTP header. I've
tried:

1. dissector_add_string("media_type", "Internet media type", xxx_handle);

2. heur_dissector_add("http", dissect_xxx_heur, proto_xxx);

3. dissector_add("tcp.port", 80, xxx_handle);

4. dissector_add("http", 80, xxx_handle);

However, my dissector (or heurisic dissector) never gets called in any
of these cases. What is the correct way of adding a subdissector to
HTTP traffic on port 80 when I don't have a content type?
Specifically I'm trying to extract info from HTTP GET requests.

Thanks,
Tarjei