Handle UDP scrapes when they don't follow the /announce idiom

[rb07]

When the tracker is an UDP tracker the scrape is never made.

Simple fix attached.

[rb07]

Enables scrape with UDP trackers.

[jordan]

rb07, could you explain this patch a little bit?

So, for example a sample linux torrent I've got has this announce URL:

udp://tracker.openbittorrent.com:80/announce

and it looks to me like that will be correctly converted in the existing tr_convertAnnounceToScrape() code. What's the case that you're seeing that the current code isn't handling?

[rb07]

Replying to jordan:

So, for example a sample linux torrent I've got has this announce URL:

udp://tracker.openbittorrent.com:80/announce

and it looks to me like that will be correctly converted in the existing tr_convertAnnounceToScrape() code.

Agree.

What's the case that you're seeing that the current code isn't handling?

Most UDP trackers don't have an 'announce', this patch fixes that since tr_tracker_udp_announce() already handles the action (which is a parameter on the request, not an URL).

Example UDP trackers (copied from one torrent):

udp://tracker.openbittorrent.com:80/
udp://tracker.publicbt.com:80
udp://tracker.ccc.de:80
udp://tracker.istole.it:80

If you like I can show a "before & after" screen shot. The before shows those trackers forever "Queued to ask for peer counts", the after shows successful scrapes.

[livings124]

Is this specified in the bittorrent spec anywhere?

[rb07]

No, I found it specified here: ​http://xbtt.sourceforge.net/udp_tracker_protocol.html, and probably somewhere else.

And it was already implemented in libtransmission, except that announce.c's tierNeedsToScrape() always returns false in this case (no 'announce' in the URL) since tr_convertAnnounceToScrape() return NULL; my fix just changes that with the valid UDP URL (which is the same as the announce URL).

[rb07]

BTW Livings, how does Transmission in Mac OSX get the scrape info on http URLs that don't have the 'announce' string?

Sorry for the off-topic, but I've been trying to solve this other minor bug/annoyance. Similar to this case, but somebody showed me a screenshot of Transmission-Mac showing the seeders and leechers stats. He also said that this could have changed on newer versions, he's using an old one (2.33 I think).

[rb07]

screen shot before applying patch.

[rb07]

screen shot after applying patch.

[jordan]

I don't see that this is spec'ed anywhere, but after testing a pile of .torrent files I do see thee udp-without-/announce idiom used in maybe 20% of them.

[jordan]

Fixed in r13311

[rb07]

Replying to jordan:

I don't see that this is spec'ed anywhere, but after testing a pile of .torrent files I do see thee udp-without-/announce idiom used in maybe 20% of them.

The xbtt page I showed does have the "scrape"-less URL definition at the top.

Since the UDP scrape protocol is binary, what sense does it make to have the "announce" string in the URL? i.e. there is no http GET. So it must be just for show on those 80%.