I always thought Darkplaces does this by default, until someone clarified me yesterday. I'm trying to setup a dedicated server which contains custom maps and player models that clients would need in order to connect. From what I knew, if the server is running a map which the client does not have, it would directly send that file to the client rather than pointing it to an external URL where the files are located (sv_curl_defaulturl).
I don't have a problem with setting up a file server since I already run a website with Apache, but imo it would be important for servers to know how to DCC-send content when it's not found at the specified URL. Some players may wish to start a quick server with custom maps, but not put them on external file hosts and all. I know this would increase bandwitch and cause lag as the map is being sent, but if the owner is willing to pay this price to avoid dependencies to other hosts I think it would be important for this to be possible.
Are there any plans to implement direct file sending in the server code, for servers that would want this feature? Perhaps I should put this on the dev tracker... I highly support this and personally find it an essential thing for any shooter that supports custom content.