Add support for 'ip' field in announce GET

[Miserlou]

In the BitTorrent spec, it says there should be support for an ip field in the announce GET:

ip
    An optional parameter giving the IP (or dns name) which this peer is at. Generally used for the origin if it's on the same machine as the tracker.

It doesn't look like the bittorrent-tracker client here supports this field, although it does support port (I don't know about the server, I only need it for the client but we might as well add it symmetrically.)

If this is available already, it should be added to the documentation.

[Miserlou]

This looks easy enough to add in, I can submit a PR once somebody can confirm this issue.

Poking the usual suspects, @yciabaud @DiegoRBaquero

[Miserlou]

This may end up being related to #157 depending on the usage.

[Miserlou]

Confirming that this isn't supported in the server either: https://github.com/feross/bittorrent-tracker/blob/master/lib/server/parse-http.js#L34

Again, seems like a really simple fix, just want to confirm you'll meet the spec before I send PR.

[yciabaud]

I can confirm we want to meet the specs but this field is optional and I don't get the use cases for this.
Do you think this should be an option in the client? Or you want to provide the private ip?

[Miserlou]

I personally just need this as an option in the client, but it looks easy enough to implement in the server code as well. This feature is supported by the other server implementations I just quickly looked at.

My use case is for hidden services, but you could also see it being useful for people who want to seed using dynDNS without having to constantly port-forward/NAT-punch and just run their seedbox on a named address instead, etc.

I don't know what 'optional' means in the BEP, but I think that means that it's optional for the client to provide, not for the tracker to implement. For example, if I announce currently with a supplied hostname, then this tracker doesn't recognize it and just uses the connection's rhost, so I'm going to get inbound peers that I don't want because of the non-BEP compliant server.

[Miserlou]

I could imagine this could also be useful to announce permanent/webseeds, ex if I'm a big game studio, I might want to run a seedbox at

seedbox.sega.com:6881

but announce it from my developer machine or CI system at

ci.sega.com:443

With ip as an option, we can announce from a CI but send the traffic to the seedbox, not the originating interface of the CI system.

[yciabaud]

I agree with you and I believe the server must handle it. The client should also be able to announce it.

IMHO... PR welcome!

[Miserlou]

I submitted an initial PR that needs a bit of further discussion, thanks @yciabaud !

[wI2L]

@Miserlou @yciabaud I can confirm that this option MUST be treated as optional by the server, meaning it's not mandatory for the client to send it, in this case the final endpoint (ip:port) of the peer is a composition of the ip address from which the request came from and the parameter port (which is mandatory, the client MUST send it).

Keep in mind that there is also the params ipv4 and ipv6 to deal with, and they are tricky.
ref: http://www.bittorrent.org/beps/bep_0007.html

Also, along with this PR, as I did in my own implementation, you could provide an option to honor the ip parameter only when the address from which the request came from belongs to a private subnet.

[Miserlou]

Hm. BEP07 was never standardized and seems to have some big omissions to me, so I think I'd consider that outside the scope of this issue, although certainly worthy of its own discussion.

[wI2L]

@Miserlou Sure thing. Still i think, even if this BEP is part to the 'Draft BEPS', I do think we can consider it as a de-facto standard due to the many implementations out there (both clients and trackers).

[Miserlou]

Out of curiosity, can you specify any that you're referring to? I started doing some surveying around this and haven't found a single open tracker that met my criteria: https://github.com/Miserlou/bt-ip-support

[wI2L]

Are you looking for implementations of running trackers ?

Based on your criterias, there is chihaya, and I think xbtt might fit your need to, not sure about the IP field but you can always check the sources. ocelot from WhatCD is also honoring the ip field, but it's a private tracker.

EDIT: If i remember well, opentracker does support the ip field too. Need to check tho.

EDIT2 : I read your code and saw that you have a long list of public tracker urls. Tho, it's hard to say what they are using as tracker implementation, but I'd say most of it is xbtt/custom or ocelot. And ip field support could have been disabled. That is why I prefer to rely on existing implementations rather than running services.