Lighttpd

When If-None-Match is specified and mod_cml gets a cache hit it will not populate the con->physical.etag field leading to a null pointer dereference (in http_response_handle_cachable).

I fixed this by adding (around line 407 of mod_cml_lua.c):

   buffer_copy_string(con->physical.etag, "unknown");

Which works as mod_cml doesn't attempt to send an etag but really it needs to generate etags and handle them properly.