| 1 | BEP: 7 |
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| 2 | Title: IPv6 Tracker Extension |
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| 3 | Version: $Revision$ |
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| 4 | Last-Modified: $Date$ |
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| 5 | Author: Greg Hazel <greg@bittorrent.com>, Arvid Norberg <arvid@bittorrent.com> |
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| 6 | Status: Draft |
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| 7 | Type: Standards Track |
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| 8 | Created: 31-Jan-2008 |
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| 9 | Post-History: |
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| 10 | |
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| 11 | This extension extends the tracker response to better support IPv6 peers as |
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| 12 | well as defines a way for multi homed machines to announce multiple addresses |
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| 13 | at the same time. This proposal addresses the use case where peers |
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| 14 | are either on an IPv4 network running Teredo_ or peers are on |
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| 15 | an IPv6 network with an IPv4 tunnel interface. |
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| 16 | |
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| 17 | .. _Teredo: https://www.microsoft.com/technet/network/ipv6/teredo.mspx |
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| 18 | |
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| 19 | The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", |
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| 20 | "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to |
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| 21 | be interpreted as described in IETF `RFC 2119`_. |
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| 22 | |
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| 23 | .. _`RFC 2119`: http://tools.ietf.org/html/rfc2119 |
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| 24 | |
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| 25 | Announce Parameter |
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| 26 | ================== |
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| 27 | |
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| 28 | The client MAY add an ``&ipv6=`` parameter to the HTTP GET request it sends |
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| 29 | to the tracker. The value is either an IPv6 endpoint (address and port) or |
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| 30 | just an IPv6 address. In the case where only an address is supplied, the IPv6 |
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| 31 | port is assumed to be the same as specified by the ``&port=`` parameter. |
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| 32 | |
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| 33 | The tracker SHOULD perform a NAT check on the IPv6 endpoint. |
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| 34 | |
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| 35 | In case the client contacts the tracker on an IPv6 interface, it may add |
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| 36 | an ``&ipv4=`` parameter with its IPv4 address or endpoint. The value MUST |
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| 37 | be either an IPv4 endpoint (address and port) or just an IPv4 address. If only |
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| 38 | an address is supplied, the port is assumed to be the same as the ``&port=`` |
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| 39 | parameter. |
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| 40 | |
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| 41 | The endpoints are encoded as strings as defined by `RFC 2732`_. |
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| 42 | |
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| 43 | .. _`RFC 2732`: http://tools.ietf.org/html/rfc2732 |
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| 44 | |
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| 45 | If both an ``&ipv4=`` and an ``&ipv6=`` parameter are specified, the tracker |
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| 46 | MAY ignore the address family that is the same as the source address of the |
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| 47 | request. i.e. If the client connects to the tracker with an IPv4 source |
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| 48 | address, the tracker MAY ignore any ``&ipv4=`` address and if the client |
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| 49 | connects to the tracker with an IPv6 source address, the tracker MAY ignore |
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| 50 | any ``&ipv6=`` parameter. |
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| 51 | |
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| 52 | Announce Response |
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| 53 | ================= |
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| 54 | |
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| 55 | In case the tracker does not support the ``compact`` response as |
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| 56 | described in `BEP-23`_, no change is necessary. Since the |
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| 57 | original ``peers`` response returns peer endpoints in their expanded |
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| 58 | string form, IPv6 addresses can be passed back this way. |
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| 59 | |
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| 60 | In case a compact response is requested, the tracker MAY add another key |
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| 61 | to the response; ``peers6``. This key has the same layout as ``peers`` in |
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| 62 | compact mode, but instead of using 6 bytes per endpoint, 18 bytes are used. |
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| 63 | peers6 contains address-port pairs where the addresses are all IPv6. |
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| 64 | |
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| 65 | .. _`BEP-23`: http://www.bittorrent.org/beps/bep_0023.html |
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| 66 | |
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| 67 | Examples |
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| 68 | ======== |
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| 69 | |
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| 70 | Example announce string with ``2001::53aa:64c:0:7f83:bc43:dec9`` as IPv6 |
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| 71 | address:: |
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| 72 | |
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| 73 | GET /announce?peer_id=aaaaaaaaaaaaaaaaaaaa&info_hash=aaaaaaaaaaaaaaaaaaaa |
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| 74 | &port=6881&left=0&downloaded=100&uploaded=0&compact=1 |
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| 75 | &ipv6=2001%3A%3A53Aa%3A64c%3A0%3A7f83%3Abc43%3Adec9 |
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| 76 | |
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| 77 | Example announce string with ``[2001::53aa:64c:0:7f83:bc43:dec9]:6882`` as IPv6 endpoint:: |
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| 78 | |
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| 79 | GET /announce?peer_id=aaaaaaaaaaaaaaaaaaaa&info_hash=aaaaaaaaaaaaaaaaaaaa |
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| 80 | &port=6881&left=0&downloaded=100&uploaded=0&compact=1 |
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| 81 | &ipv6=%5B2001%3A%3A53Aa%3A64c%3A0%3A7f83%3Abc43%3Adec9%5D%3A6882 |
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| 82 | |
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| 83 | Example announce string with ``2001::53aa:64c:0:7f83:bc43:dec9`` as IPv6 |
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| 84 | address and ``261.52.89.12`` as IPv4 address:: |
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| 85 | |
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| 86 | GET /announce?peer_id=aaaaaaaaaaaaaaaaaaaa&info_hash=aaaaaaaaaaaaaaaaaaaa |
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| 87 | &port=6881&left=0&downloaded=100&uploaded=0&compact=1 |
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| 88 | &ipv6=2001%3A%3A53Aa%3A64c%3A0%3A7f83%3Abc43%3Adec9&ipv4=261.52.89.12 |
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| 89 | |
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| 90 | Example response:: |
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| 91 | |
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| 92 | d8:intervali1800e5:peers6:iiiipp6:peers618:iiiiiiiiiiiiiiiippe |
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| 93 | |
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| 94 | Rationale |
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| 95 | ========= |
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| 96 | |
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| 97 | The naming of ``peers6`` is chosen not to collide with the current ``peers`` |
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| 98 | response and to be backwards compatible. It is also a simple addition to the |
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| 99 | current response, using the same encoding. |
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| 100 | |
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| 101 | |
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| 102 | Copyright |
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| 103 | ========= |
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| 104 | |
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| 105 | This document has been placed in the public domain. |
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| 106 | |
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| 107 | |
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| 108 | |
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| 109 | .. |
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| 110 | Local Variables: |
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| 111 | mode: indented-text |
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| 112 | indent-tabs-mode: nil |
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| 113 | sentence-end-double-space: t |
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| 114 | fill-column: 70 |
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| 115 | coding: utf-8 |
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| 116 | End: |
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