2006-04-25 23:04:48 +02:00
|
|
|
<?xml version="1.0" encoding="utf-8" ?>
|
|
|
|
|
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
|
|
|
|
|
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
|
|
|
|
|
<head>
|
2012-01-14 17:04:25 +01:00
|
|
|
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
|
2015-01-01 00:18:11 +01:00
|
|
|
<meta name="generator" content="Docutils 0.12: http://docutils.sourceforge.net/" />
|
2012-01-14 17:04:25 +01:00
|
|
|
<title></title>
|
2014-10-14 04:06:20 +02:00
|
|
|
<meta name="author" content="Arvid Norberg, arvid@libtorrent.org Ludvig Strigeus, ludde@utorrent.com" />
|
2015-05-12 08:23:14 +02:00
|
|
|
<meta name=viewport content="width=device-width, initial-scale=1">
|
2010-12-08 05:44:20 +01:00
|
|
|
<script type="text/javascript">
|
|
|
|
|
/* <![CDATA[ */
|
|
|
|
|
(function() {
|
|
|
|
|
var s = document.createElement('script'), t = document.getElementsByTagName('script')[0];
|
|
|
|
|
s.type = 'text/javascript';
|
|
|
|
|
s.async = true;
|
|
|
|
|
s.src = 'http://api.flattr.com/js/0.6/load.js?mode=auto';
|
|
|
|
|
t.parentNode.insertBefore(s, t);
|
|
|
|
|
})();
|
|
|
|
|
/* ]]> */
|
|
|
|
|
</script>
|
2006-06-20 01:26:38 +02:00
|
|
|
<link rel="stylesheet" href="style.css" type="text/css" />
|
2015-05-12 08:23:14 +02:00
|
|
|
<link rel="stylesheet" type="text/css" href="rst.css" />
|
2008-10-17 05:23:30 +02:00
|
|
|
<style type="text/css">
|
|
|
|
|
/* Hides from IE-mac \*/
|
|
|
|
|
* html pre { height: 1%; }
|
|
|
|
|
/* End hide from IE-mac */
|
|
|
|
|
</style>
|
2006-04-25 23:04:48 +02:00
|
|
|
</head>
|
|
|
|
|
<body>
|
|
|
|
|
<div class="document">
|
2008-10-17 05:23:30 +02:00
|
|
|
<div id="container">
|
2014-10-14 18:36:06 +02:00
|
|
|
<table id="header">
|
|
|
|
|
<tr><td id="orange"></td>
|
|
|
|
|
<td id="logo">libtorrent</td></tr>
|
|
|
|
|
</table>
|
2008-10-17 05:23:30 +02:00
|
|
|
<div id="main">
|
2006-11-28 19:18:37 +01:00
|
|
|
|
2006-04-25 23:04:48 +02:00
|
|
|
<table class="docinfo" frame="void" rules="none">
|
|
|
|
|
<col class="docinfo-name" />
|
|
|
|
|
<col class="docinfo-content" />
|
|
|
|
|
<tbody valign="top">
|
|
|
|
|
<tr><th class="docinfo-name">Author:</th>
|
2014-10-14 04:06:20 +02:00
|
|
|
<td>Arvid Norberg, <a class="reference external" href="mailto:arvid@libtorrent.org">arvid@libtorrent.org</a>
|
2009-03-21 05:36:46 +01:00
|
|
|
Ludvig Strigeus, <a class="last reference external" href="mailto:ludde@utorrent.com">ludde@utorrent.com</a></td></tr>
|
2006-04-25 23:04:48 +02:00
|
|
|
</tbody>
|
|
|
|
|
</table>
|
2008-10-17 05:23:30 +02:00
|
|
|
<div class="section" id="extension-protocol-for-bittorrent">
|
|
|
|
|
<h1>extension protocol for bittorrent</h1>
|
2006-04-25 23:04:48 +02:00
|
|
|
<p>The intention of this protocol is to provide a simple and thin transport
|
|
|
|
|
for extensions to the bittorrent protocol. Supporting this protocol makes
|
|
|
|
|
it easy to add new extensions without interfering with the standard
|
|
|
|
|
bittorrent protocol or clients that don't support this extension or the
|
|
|
|
|
one you want to add.</p>
|
|
|
|
|
<p>To advertise to other clients that you support, one bit from the reserved
|
|
|
|
|
bytes is used.</p>
|
|
|
|
|
<p>The bit selected for the extension protocol is bit 20 from the right (counting
|
|
|
|
|
starts at 0). So (reserved_byte[5] & 0x10) is the expression to use for checking
|
|
|
|
|
if the client supports extended messaging.</p>
|
|
|
|
|
<p>Once support for the protocol is established, the client is supposed to
|
|
|
|
|
support 1 new message:</p>
|
|
|
|
|
<table border="1" class="docutils">
|
|
|
|
|
<colgroup>
|
|
|
|
|
<col width="86%" />
|
|
|
|
|
<col width="14%" />
|
|
|
|
|
</colgroup>
|
|
|
|
|
<thead valign="bottom">
|
|
|
|
|
<tr><th class="head">name</th>
|
|
|
|
|
<th class="head">id</th>
|
|
|
|
|
</tr>
|
|
|
|
|
</thead>
|
|
|
|
|
<tbody valign="top">
|
2013-01-21 20:13:24 +01:00
|
|
|
<tr><td><tt class="docutils literal">extended</tt></td>
|
2006-04-25 23:04:48 +02:00
|
|
|
<td>20</td>
|
|
|
|
|
</tr>
|
|
|
|
|
</tbody>
|
|
|
|
|
</table>
|
|
|
|
|
<p>This message is sent as any other bittorrent message, with a 4 byte length
|
|
|
|
|
prefix and a single byte identifying the message (the single byte being 20
|
|
|
|
|
in this case). At the start of the payload of the message, is a single byte
|
|
|
|
|
message identifier. This identifier can refer to different extension messages
|
|
|
|
|
and only one ID is specified, 0. If the ID is 0, the message is a handshake
|
2013-01-21 20:13:24 +01:00
|
|
|
message which is described below. The layout of a general <tt class="docutils literal">extended</tt> message
|
2006-04-25 23:04:48 +02:00
|
|
|
follows (including the message headers used by the bittorrent protocol):</p>
|
|
|
|
|
<table border="1" class="docutils">
|
|
|
|
|
<colgroup>
|
|
|
|
|
<col width="15%" />
|
|
|
|
|
<col width="85%" />
|
|
|
|
|
</colgroup>
|
|
|
|
|
<thead valign="bottom">
|
|
|
|
|
<tr><th class="head">size</th>
|
|
|
|
|
<th class="head">description</th>
|
|
|
|
|
</tr>
|
|
|
|
|
</thead>
|
|
|
|
|
<tbody valign="top">
|
|
|
|
|
<tr><td>uint32_t</td>
|
|
|
|
|
<td>length prefix. Specifies the number of bytes for the
|
|
|
|
|
entire message. (Big endian)</td>
|
|
|
|
|
</tr>
|
|
|
|
|
<tr><td>uint8_t</td>
|
|
|
|
|
<td>bittorrent message ID, = 20</td>
|
|
|
|
|
</tr>
|
|
|
|
|
<tr><td>uint8_t</td>
|
|
|
|
|
<td>extended message ID. 0 = handshake, >0 = extended
|
|
|
|
|
message as specified by the handshake.</td>
|
|
|
|
|
</tr>
|
|
|
|
|
</tbody>
|
|
|
|
|
</table>
|
2008-10-17 05:23:30 +02:00
|
|
|
<div class="section" id="handshake-message">
|
|
|
|
|
<h2>handshake message</h2>
|
2006-04-25 23:04:48 +02:00
|
|
|
<p>The payload of the handshake message is a bencoded dictionary. All items
|
|
|
|
|
in the dictionary are optional. Any unknown names should be ignored
|
|
|
|
|
by the client. All parts of the dictionary are case sensitive.
|
|
|
|
|
This is the defined item in the dictionary:</p>
|
|
|
|
|
<table border="1" class="docutils">
|
|
|
|
|
<colgroup>
|
|
|
|
|
<col width="11%" />
|
|
|
|
|
<col width="89%" />
|
|
|
|
|
</colgroup>
|
|
|
|
|
<thead valign="bottom">
|
|
|
|
|
<tr><th class="head">name</th>
|
|
|
|
|
<th class="head">description</th>
|
|
|
|
|
</tr>
|
|
|
|
|
</thead>
|
|
|
|
|
<tbody valign="top">
|
|
|
|
|
<tr><td>m</td>
|
2006-11-27 01:04:20 +01:00
|
|
|
<td><p class="first">Dictionary of supported extension messages which maps
|
|
|
|
|
names of extensions to an extended message ID for each
|
|
|
|
|
extension message. The only requirement on these IDs
|
|
|
|
|
is that no extension message share the same one. Setting
|
2006-04-25 23:04:48 +02:00
|
|
|
an extension number to zero means that the extension is
|
|
|
|
|
not supported/disabled. The client should ignore any
|
2006-11-27 01:04:20 +01:00
|
|
|
extension names it doesn't recognize.</p>
|
|
|
|
|
<p class="last">The extension message IDs are the IDs used to send the
|
|
|
|
|
extension messages to the peer sending this handshake.
|
|
|
|
|
i.e. The IDs are local to this particular peer.</p>
|
|
|
|
|
</td>
|
2006-04-25 23:04:48 +02:00
|
|
|
</tr>
|
|
|
|
|
</tbody>
|
|
|
|
|
</table>
|
2006-11-27 01:04:20 +01:00
|
|
|
<p>Here are some other items that an implementation may choose to support:</p>
|
2006-04-25 23:04:48 +02:00
|
|
|
<table border="1" class="docutils">
|
|
|
|
|
<colgroup>
|
2007-08-22 07:31:42 +02:00
|
|
|
<col width="12%" />
|
|
|
|
|
<col width="88%" />
|
2006-04-25 23:04:48 +02:00
|
|
|
</colgroup>
|
|
|
|
|
<thead valign="bottom">
|
|
|
|
|
<tr><th class="head">name</th>
|
|
|
|
|
<th class="head">description</th>
|
|
|
|
|
</tr>
|
|
|
|
|
</thead>
|
|
|
|
|
<tbody valign="top">
|
|
|
|
|
<tr><td>p</td>
|
|
|
|
|
<td>Local TCP listen port. Allows each side to learn about
|
|
|
|
|
the TCP port number of the other side. Note that there is
|
|
|
|
|
no need for the receiving side of the connection to send
|
|
|
|
|
this extension message, since its port number is already
|
|
|
|
|
known.</td>
|
|
|
|
|
</tr>
|
|
|
|
|
<tr><td>v</td>
|
2007-08-22 07:31:42 +02:00
|
|
|
<td>Client name and version (as a utf-8 string).
|
2006-04-25 23:04:48 +02:00
|
|
|
This is a much more reliable way of identifying the
|
|
|
|
|
client than relying on the peer id encoding.</td>
|
|
|
|
|
</tr>
|
2007-08-22 07:31:42 +02:00
|
|
|
<tr><td>yourip</td>
|
|
|
|
|
<td>A string containing the compact representation of the ip
|
|
|
|
|
address this peer sees you as. i.e. this is the
|
|
|
|
|
receiver's external ip address (no port is included).
|
2007-09-10 03:57:40 +02:00
|
|
|
This may be either an IPv4 (4 bytes) or an IPv6
|
|
|
|
|
(16 bytes) address.</td>
|
2007-08-22 07:31:42 +02:00
|
|
|
</tr>
|
2007-10-01 04:47:57 +02:00
|
|
|
<tr><td>ipv6</td>
|
|
|
|
|
<td>If this peer has an IPv6 interface, this is the compact
|
|
|
|
|
representation of that address (16 bytes). The client may
|
|
|
|
|
prefer to connect back via the IPv6 address.</td>
|
|
|
|
|
</tr>
|
|
|
|
|
<tr><td>ipv4</td>
|
|
|
|
|
<td>If this peer has an IPv4 interface, this is the compact
|
|
|
|
|
representation of that address (4 bytes). The client may
|
|
|
|
|
prefer to connect back via this interface.</td>
|
|
|
|
|
</tr>
|
2006-05-15 00:30:05 +02:00
|
|
|
<tr><td>reqq</td>
|
|
|
|
|
<td>An integer, the number of outstanding request messages
|
|
|
|
|
this client supports without dropping any. The default in
|
|
|
|
|
in libtorrent is 250.</td>
|
|
|
|
|
</tr>
|
2006-04-25 23:04:48 +02:00
|
|
|
</tbody>
|
|
|
|
|
</table>
|
|
|
|
|
<p>The handshake dictionary could also include extended handshake
|
|
|
|
|
information, such as support for encrypted headers or anything
|
|
|
|
|
imaginable.</p>
|
|
|
|
|
<p>An example of what the payload of a handshake message could look like:</p>
|
|
|
|
|
<table border="1" class="docutils">
|
|
|
|
|
<colgroup>
|
|
|
|
|
<col width="36%" />
|
|
|
|
|
<col width="64%" />
|
|
|
|
|
</colgroup>
|
|
|
|
|
<thead valign="bottom">
|
|
|
|
|
<tr><th class="head" colspan="2">Dictionary</th>
|
|
|
|
|
</tr>
|
|
|
|
|
</thead>
|
|
|
|
|
<tbody valign="top">
|
2013-01-21 20:13:24 +01:00
|
|
|
<tr><td><tt class="docutils literal">m</tt></td>
|
2006-04-25 23:04:48 +02:00
|
|
|
<td><table border="1" class="first last docutils">
|
|
|
|
|
<colgroup>
|
|
|
|
|
<col width="88%" />
|
|
|
|
|
<col width="12%" />
|
|
|
|
|
</colgroup>
|
|
|
|
|
<thead valign="bottom">
|
|
|
|
|
<tr><th class="head" colspan="2">Dictionary</th>
|
|
|
|
|
</tr>
|
|
|
|
|
</thead>
|
|
|
|
|
<tbody valign="top">
|
2013-01-21 20:13:24 +01:00
|
|
|
<tr><td><tt class="docutils literal">LT_metadata</tt></td>
|
2006-04-25 23:04:48 +02:00
|
|
|
<td>1</td>
|
|
|
|
|
</tr>
|
2013-01-21 20:13:24 +01:00
|
|
|
<tr><td><tt class="docutils literal">ut_pex</tt></td>
|
2006-04-25 23:04:48 +02:00
|
|
|
<td>2</td>
|
|
|
|
|
</tr>
|
|
|
|
|
</tbody>
|
|
|
|
|
</table>
|
|
|
|
|
</td>
|
|
|
|
|
</tr>
|
2013-01-21 20:13:24 +01:00
|
|
|
<tr><td><tt class="docutils literal">p</tt></td>
|
2006-04-25 23:04:48 +02:00
|
|
|
<td>6881</td>
|
|
|
|
|
</tr>
|
2013-01-21 20:13:24 +01:00
|
|
|
<tr><td><tt class="docutils literal">v</tt></td>
|
|
|
|
|
<td>"uTorrent 1.2"</td>
|
2006-04-25 23:04:48 +02:00
|
|
|
</tr>
|
|
|
|
|
</tbody>
|
|
|
|
|
</table>
|
|
|
|
|
<p>and in the encoded form:</p>
|
2013-01-21 20:13:24 +01:00
|
|
|
<p><tt class="docutils literal">d1:md11:LT_metadatai1e6:ut_pexi2ee1:pi6881e1:v12:uTorrent 1.2e</tt></p>
|
2006-04-25 23:04:48 +02:00
|
|
|
<p>To make sure the extension names do not collide by mistake, they should be
|
|
|
|
|
prefixed with the two (or one) character code that is used to identify the
|
|
|
|
|
client that introduced the extension. This applies for both the names of
|
|
|
|
|
extension messages, and for any additional information put inside the
|
|
|
|
|
top-level dictionary. All one and two byte identifiers are invalid to use
|
|
|
|
|
unless defined by this specification.</p>
|
|
|
|
|
<p>This message should be sent immediately after the standard bittorrent handshake
|
|
|
|
|
to any peer that supports this extension protocol. It is valid to send the
|
|
|
|
|
handshake message more than once during the lifetime of a connection,
|
|
|
|
|
the sending client should not be disconnected. An implementation may choose
|
|
|
|
|
to ignore the subsequent handshake messages (or parts of them).</p>
|
|
|
|
|
<p>Subsequent handshake messages can be used to enable/disable extensions
|
|
|
|
|
without restarting the connection. If a peer supports changing extensions
|
2013-01-21 20:13:24 +01:00
|
|
|
at run time, it should note that the <tt class="docutils literal">m</tt> dictionary is additive.
|
2006-04-25 23:04:48 +02:00
|
|
|
It's enough that it contains the actual <em>CHANGES</em> to the extension list.
|
2013-01-21 20:13:24 +01:00
|
|
|
To disable the support for <tt class="docutils literal">LT_metadata</tt> at run-time, without affecting
|
2006-04-25 23:04:48 +02:00
|
|
|
any other extensions, this message should be sent:
|
2013-01-21 20:13:24 +01:00
|
|
|
<tt class="docutils literal">d11:LT_metadatai0ee</tt>.
|
2006-04-25 23:04:48 +02:00
|
|
|
As specified above, the value 0 is used to turn off an extension.</p>
|
|
|
|
|
<p>The extension IDs must be stored for every peer, becuase every peer may have
|
|
|
|
|
different IDs for the same extension.</p>
|
|
|
|
|
<p>This specification, deliberately, does not specify any extensions such as
|
|
|
|
|
peer-exchange or metadata exchange. This protocol is merely a transport
|
|
|
|
|
for the actual extensions to the bittorrent protocol and the extensions
|
2013-01-21 20:13:24 +01:00
|
|
|
named in the example above (such as <tt class="docutils literal">p</tt>) are just examples of possible
|
2006-04-25 23:04:48 +02:00
|
|
|
extensions.</p>
|
|
|
|
|
</div>
|
2008-10-17 05:23:30 +02:00
|
|
|
<div class="section" id="rationale">
|
|
|
|
|
<h2>rationale</h2>
|
2006-04-25 23:04:48 +02:00
|
|
|
<p>The reason why the extension messages' IDs would be defined in the handshake
|
2006-11-27 01:04:20 +01:00
|
|
|
is to avoid having a global registry of message IDs. Instead the names of the
|
|
|
|
|
extension messages requires unique names, which is much easier to do without
|
|
|
|
|
a global registry. The convention is to use a two letter prefix on the
|
|
|
|
|
extension message names, the prefix would identify the client first
|
2013-01-21 20:13:24 +01:00
|
|
|
implementing the extension message. e.g. <tt class="docutils literal">LT_metadata</tt> is implemented by
|
|
|
|
|
libtorrent, and hence it has the <tt class="docutils literal">LT</tt> prefix.</p>
|
2006-04-25 23:04:48 +02:00
|
|
|
<p>If the client supporting the extensions can decide which numbers the messages
|
|
|
|
|
it receives will have, it means they are constants within that client. i.e.
|
2013-01-21 20:13:24 +01:00
|
|
|
they can be used in <tt class="docutils literal">switch</tt> statements. It's easy for the other end to
|
2006-04-25 23:04:48 +02:00
|
|
|
store an array with the ID's we expect for each message and use that for
|
|
|
|
|
lookups each time it sends an extension message.</p>
|
|
|
|
|
<p>The reason for having a dictionary instead of having an array (using
|
|
|
|
|
implicitly assigned index numbers to the extensions) is that if a client
|
|
|
|
|
want to disable some extensions, the ID numbers would change, and it wouldn't
|
2013-01-21 20:13:24 +01:00
|
|
|
be able to use constants (and hence, not use them in a <tt class="docutils literal">switch</tt>). If the
|
2006-04-25 23:04:48 +02:00
|
|
|
messages IDs would map directly to bittorrent message IDs, It would also make
|
|
|
|
|
it possible to map extensions in the handshake to existing extensions with
|
|
|
|
|
fixed message IDs.</p>
|
|
|
|
|
<p>The reasoning behind having a single byte as extended message identifier is
|
|
|
|
|
to follow the the bittorrent spec. with its single byte message identifiers.
|
|
|
|
|
It is also considered to be enough. It won't limit the total number of
|
|
|
|
|
extensions, only the number of extensions used simultaneously.</p>
|
|
|
|
|
<p>The reason for using single byte identifiers for the standardized handshake
|
|
|
|
|
identifiers is 1) The mainline DHT uses single byte identifiers. 2) Saves
|
|
|
|
|
bandwidth. The only advantage of longer messages is that it makes the
|
|
|
|
|
protocol more readable for a human, but the BT protocol wasn't designed to
|
|
|
|
|
be a human readable protocol, so why bother.</p>
|
|
|
|
|
</div>
|
|
|
|
|
</div>
|
2014-09-04 00:28:28 +02:00
|
|
|
<div class="section" id="extensions">
|
|
|
|
|
<h1>extensions</h1>
|
|
|
|
|
<p>These extensions all operates within the <a class="reference external" href="extension_protocol.html">extension protocol</a>. The name of the
|
|
|
|
|
extension is the name used in the extension-list packets, and the payload is
|
|
|
|
|
the data in the extended message (not counting the length-prefix, message-id
|
|
|
|
|
nor extension-id).</p>
|
|
|
|
|
<p>Note that since this protocol relies on one of the reserved bits in the
|
|
|
|
|
handshake, it may be incompatible with future versions of the mainline
|
|
|
|
|
bittorrent client.</p>
|
|
|
|
|
<p>These are the extensions that are currently implemented.</p>
|
|
|
|
|
<div class="section" id="metadata-from-peers">
|
|
|
|
|
<h2>metadata from peers</h2>
|
|
|
|
|
<p>Extension name: "LT_metadata"</p>
|
|
|
|
|
<div class="note">
|
|
|
|
|
<p class="first admonition-title">Note</p>
|
|
|
|
|
<p class="last">This extension is deprecated in favor of the more widely supported
|
|
|
|
|
<tt class="docutils literal">ut_metadata</tt> extension, see <a class="reference external" href="http://bittorrent.org/beps/bep_0009.html">BEP 9</a>.</p>
|
|
|
|
|
</div>
|
|
|
|
|
<p>The point with this extension is that you don't have to distribute the
|
|
|
|
|
metadata (.torrent-file) separately. The metadata can be distributed
|
|
|
|
|
through the bittorrent swarm. The only thing you need to download such
|
|
|
|
|
a torrent is the tracker url and the info-hash of the torrent.</p>
|
|
|
|
|
<p>It works by assuming that the initial seeder has the metadata and that the
|
|
|
|
|
metadata will propagate through the network as more peers join.</p>
|
|
|
|
|
<p>There are three kinds of messages in the metadata extension. These packets are
|
|
|
|
|
put as payload to the extension message. The three packets are:</p>
|
|
|
|
|
<blockquote>
|
|
|
|
|
<ul class="simple">
|
|
|
|
|
<li>request metadata</li>
|
|
|
|
|
<li>metadata</li>
|
|
|
|
|
<li>don't have metadata</li>
|
|
|
|
|
</ul>
|
|
|
|
|
</blockquote>
|
|
|
|
|
<p>request metadata:</p>
|
|
|
|
|
<table border="1" class="docutils">
|
|
|
|
|
<colgroup>
|
|
|
|
|
<col width="17%" />
|
|
|
|
|
<col width="23%" />
|
|
|
|
|
<col width="61%" />
|
|
|
|
|
</colgroup>
|
|
|
|
|
<thead valign="bottom">
|
|
|
|
|
<tr><th class="head">size</th>
|
|
|
|
|
<th class="head">name</th>
|
|
|
|
|
<th class="head">description</th>
|
|
|
|
|
</tr>
|
|
|
|
|
</thead>
|
|
|
|
|
<tbody valign="top">
|
|
|
|
|
<tr><td>uint8_t</td>
|
|
|
|
|
<td>msg_type</td>
|
|
|
|
|
<td>Determines the kind of message this is
|
|
|
|
|
0 means 'request metadata'</td>
|
|
|
|
|
</tr>
|
|
|
|
|
<tr><td>uint8_t</td>
|
|
|
|
|
<td>start</td>
|
|
|
|
|
<td>The start of the metadata block that
|
|
|
|
|
is requested. It is given in 256:ths
|
|
|
|
|
of the total size of the metadata,
|
|
|
|
|
since the requesting client don't know
|
|
|
|
|
the size of the metadata.</td>
|
|
|
|
|
</tr>
|
|
|
|
|
<tr><td>uint8_t</td>
|
|
|
|
|
<td>size</td>
|
|
|
|
|
<td>The size of the metadata block that is
|
|
|
|
|
requested. This is also given in
|
|
|
|
|
256:ths of the total size of the
|
|
|
|
|
metadata. The size is given as size-1.
|
|
|
|
|
That means that if this field is set
|
|
|
|
|
0, the request wants one 256:th of the
|
|
|
|
|
metadata.</td>
|
|
|
|
|
</tr>
|
|
|
|
|
</tbody>
|
|
|
|
|
</table>
|
|
|
|
|
<p>metadata:</p>
|
|
|
|
|
<table border="1" class="docutils">
|
|
|
|
|
<colgroup>
|
|
|
|
|
<col width="17%" />
|
|
|
|
|
<col width="23%" />
|
|
|
|
|
<col width="61%" />
|
|
|
|
|
</colgroup>
|
|
|
|
|
<thead valign="bottom">
|
|
|
|
|
<tr><th class="head">size</th>
|
|
|
|
|
<th class="head">name</th>
|
|
|
|
|
<th class="head">description</th>
|
|
|
|
|
</tr>
|
|
|
|
|
</thead>
|
|
|
|
|
<tbody valign="top">
|
|
|
|
|
<tr><td>uint8_t</td>
|
|
|
|
|
<td>msg_type</td>
|
|
|
|
|
<td>1 means 'metadata'</td>
|
|
|
|
|
</tr>
|
|
|
|
|
<tr><td>int32_t</td>
|
|
|
|
|
<td>total_size</td>
|
|
|
|
|
<td>The total size of the metadata, given
|
|
|
|
|
in number of bytes.</td>
|
|
|
|
|
</tr>
|
|
|
|
|
<tr><td>int32_t</td>
|
|
|
|
|
<td>offset</td>
|
|
|
|
|
<td>The offset of where the metadata block
|
|
|
|
|
in this message belongs in the final
|
|
|
|
|
metadata. This is given in bytes.</td>
|
|
|
|
|
</tr>
|
|
|
|
|
<tr><td>uint8_t[]</td>
|
|
|
|
|
<td>metadata</td>
|
|
|
|
|
<td>The actual metadata block. The size of
|
|
|
|
|
this part is given implicit by the
|
|
|
|
|
length prefix in the bittorrent
|
|
|
|
|
protocol packet.</td>
|
|
|
|
|
</tr>
|
|
|
|
|
</tbody>
|
|
|
|
|
</table>
|
|
|
|
|
<p>Don't have metadata:</p>
|
|
|
|
|
<table border="1" class="docutils">
|
|
|
|
|
<colgroup>
|
|
|
|
|
<col width="17%" />
|
|
|
|
|
<col width="23%" />
|
|
|
|
|
<col width="61%" />
|
|
|
|
|
</colgroup>
|
|
|
|
|
<thead valign="bottom">
|
|
|
|
|
<tr><th class="head">size</th>
|
|
|
|
|
<th class="head">name</th>
|
|
|
|
|
<th class="head">description</th>
|
|
|
|
|
</tr>
|
|
|
|
|
</thead>
|
|
|
|
|
<tbody valign="top">
|
|
|
|
|
<tr><td>uint8_t</td>
|
|
|
|
|
<td>msg_type</td>
|
|
|
|
|
<td>2 means 'I don't have metadata'.
|
|
|
|
|
This message is sent as a reply to a
|
|
|
|
|
metadata request if the the client
|
|
|
|
|
doesn't have any metadata.</td>
|
|
|
|
|
</tr>
|
|
|
|
|
</tbody>
|
|
|
|
|
</table>
|
|
|
|
|
</div>
|
|
|
|
|
<div class="section" id="dont-have">
|
|
|
|
|
<h2>dont_have</h2>
|
|
|
|
|
<p>Extension name: "lt_donthave"</p>
|
|
|
|
|
<p>The <tt class="docutils literal">dont_have</tt> extension message is used to tell peers that the client no
|
|
|
|
|
longer has a specific piece. The extension message should be advertised in the
|
|
|
|
|
<tt class="docutils literal">m</tt> dictionary as <tt class="docutils literal">lt_donthave</tt>. The message format mimics the regular
|
|
|
|
|
<tt class="docutils literal">HAVE</tt> bittorrent message.</p>
|
|
|
|
|
<p>Just like all extension messages, the first 2 bytes in the mssage itself are 20
|
|
|
|
|
(the bittorrent extension message) and the message ID assigned to this
|
|
|
|
|
extension in the <tt class="docutils literal">m</tt> dictionary in the handshake.</p>
|
|
|
|
|
<table border="1" class="docutils">
|
|
|
|
|
<colgroup>
|
|
|
|
|
<col width="17%" />
|
|
|
|
|
<col width="23%" />
|
|
|
|
|
<col width="61%" />
|
|
|
|
|
</colgroup>
|
|
|
|
|
<thead valign="bottom">
|
|
|
|
|
<tr><th class="head">size</th>
|
|
|
|
|
<th class="head">name</th>
|
|
|
|
|
<th class="head">description</th>
|
|
|
|
|
</tr>
|
|
|
|
|
</thead>
|
|
|
|
|
<tbody valign="top">
|
|
|
|
|
<tr><td>uint32_t</td>
|
|
|
|
|
<td>piece</td>
|
|
|
|
|
<td>index of the piece the peer no longer
|
|
|
|
|
has.</td>
|
|
|
|
|
</tr>
|
|
|
|
|
</tbody>
|
|
|
|
|
</table>
|
|
|
|
|
<p>The length of this message (including the extension message prefix) is 6 bytes,
|
|
|
|
|
i.e. one byte longer than the normal <tt class="docutils literal">HAVE</tt> message, because of the extension
|
|
|
|
|
message wrapping.</p>
|
|
|
|
|
</div>
|
|
|
|
|
</div>
|
2014-10-14 18:36:06 +02:00
|
|
|
|
|
|
|
|
</div>
|
|
|
|
|
</div>
|
|
|
|
|
<div id="gradient"></div>
|
|
|
|
|
<div id="footer">
|
|
|
|
|
<table>
|
|
|
|
|
<tr>
|
|
|
|
|
<td><a href="index.html">home</a></td>
|
|
|
|
|
<td><a href="http://blog.libtorrent.org">blog</a></td>
|
|
|
|
|
<td><a href="utp.html">uTP</a></td>
|
|
|
|
|
</tr>
|
|
|
|
|
<tr>
|
|
|
|
|
<td><a href="https://sourceforge.net/projects/libtorrent/files/libtorrent/">download</a></td>
|
|
|
|
|
<td><a href="reference.html">documentation</a></td>
|
|
|
|
|
<td><a href="dht_store.html">DHT put extension</a></td>
|
|
|
|
|
</tr>
|
|
|
|
|
<tr>
|
|
|
|
|
<td><a href="https://sourceforge.net/projects/libtorrent/files/py-libtorrent/">python bindings</a></td>
|
|
|
|
|
<td><a href="features.html">features</a></td>
|
|
|
|
|
<td><a href="dht_sec.html">DHT security extension</a></td>
|
|
|
|
|
</tr>
|
|
|
|
|
<tr>
|
|
|
|
|
<td><a href="http://dir.gmane.org/gmane.network.bit-torrent.libtorrent">mailing list archive</a></td>
|
|
|
|
|
<td><a href="contributing.html">contributing</a></td>
|
|
|
|
|
<td><a href="streaming.html">streaming</a></td>
|
|
|
|
|
</tr>
|
|
|
|
|
<tr>
|
|
|
|
|
<td><a href="http://code.google.com/p/libtorrent/issues/entry">report a bug</a></td>
|
|
|
|
|
<td><a href="building.html">building</a></td>
|
|
|
|
|
<td><a href="bittorrent.pdf">bittorrent slides</a></td>
|
|
|
|
|
</tr>
|
|
|
|
|
</table>
|
|
|
|
|
</div>
|
2015-05-12 08:23:14 +02:00
|
|
|
<div id="filler"></div>
|
2014-10-14 18:36:06 +02:00
|
|
|
|
2006-04-25 23:04:48 +02:00
|
|
|
</div>
|
|
|
|
|
</body>
|
|
|
|
|
</html>
|
