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added first version of an IPv6 extension and docs

This commit is contained in:
Arvid Norberg 2006-09-21 18:22:26 +00:00
parent 978fe778ec
commit 004d3771cb
2 changed files with 113 additions and 31 deletions
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39
docs/dht_extensions.rst Normal file
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@ -0,0 +1,39 @@
:Author: Arvid Norberg, arvid@rasterbar.com
Mainline DHT extensions
=======================
libtorrent implements a few extensions to the Mainline DHT protocol.
client identification
---------------------
In each DHT packet, an extra key is inserted named "v". This is a string
describing the client and version used. This can help alot when debugging
and finding errors in client implementations. The string is encoded as four
characters, two characters describing the client and two characters interpreted
as a binary number describing the client version.
Currently known clients:
+---------------+--------+
| uTorrent | ``UT`` |
+---------------+--------+
| libtorrent | ``LT`` |
+---------------+--------+
| MooPolice | ``MP`` |
+---------------+--------+
| GetRight | ``GR`` |
+---------------+--------+
IPv6 support
------------
The only DHT messages that don't support IPv6 is the ``nodes`` reply. It
encodes all the contacts as 6 bytes sequences packet together in sequence in
string. The problem is that IPv6 endpoints cannot be encoded as 6 bytes, but
18 bytes. The extension libtorrent applies is to add another key, called
``nodes2`` which is encoded as a list of strings. Each string represents one
contact and is encoded as 20 bytes node-id and then a variable length encoded
IP address (6 bytes in IPv4 case and 18 bytes in IPv6 case).

105
src/kademlia/dht_tracker.cpp
View File

@ -103,6 +103,25 @@ namespace
return boost::optional<node_id>(
boost::lexical_cast<node_id>(nid->string()));
}
template <class EndpointType>
void read_endpoint_list(libtorrent::entry const* n, std::vector<EndpointType>& epl)
{
using namespace libtorrent;
entry::list_type const& contacts = n->list();
for (entry::list_type::const_iterator i = contacts.begin()
, end(contacts.end()); i != end; ++i)
{
std::string const& p = i->string();
if (p.size() < 6) continue;
std::string::const_iterator in = p.begin();
if (p.size() == 6)
epl.push_back(read_v4_endpoint<EndpointType>(in));
else if (p.size() == 18)
epl.push_back(read_v6_endpoint<EndpointType>(in));
}
}
}
namespace libtorrent { namespace dht
@ -161,24 +180,11 @@ namespace libtorrent { namespace dht
if (bootstrap.type() == entry::dictionary_t)
{
if (entry const* nodes = bootstrap.find_key("nodes"))
try
{
if (nodes->type() == entry::list_t)
{
entry::list_type const& node_list = nodes->list();
for (entry::list_type::const_iterator i = node_list.begin()
, end(node_list.end()); i != end; ++i)
{
if (i->type() != entry::string_t) continue;
std::string const& str = i->string();
std::string::const_iterator in(str.begin());
if (str.length() == 6)
initial_nodes.push_back(read_v4_endpoint<udp::endpoint>(in));
else if (str.length() == 18)
initial_nodes.push_back(read_v6_endpoint<udp::endpoint>(in));
}
}
}
if (entry const* nodes = bootstrap.find_key("nodes"))
read_endpoint_list<udp::endpoint>(nodes, initial_nodes);
} catch (std::exception&) {}
}
m_dht.bootstrap(initial_nodes, bind(&dht_tracker::on_bootstrap, this));
@ -436,26 +442,15 @@ namespace libtorrent { namespace dht
if (entry const* n = r.find_key("values"))
{
m.peers.clear();
entry::list_type const& peers = n->list();
for (entry::list_type::const_iterator i = peers.begin()
, end(peers.end()); i != end; ++i)
{
std::string const& p = i->string();
if (p.size() < 6) continue;
std::string::const_iterator in = p.begin();
if (p.size() == 6)
m.peers.push_back(read_v4_endpoint<tcp::endpoint>(in));
else if (p.size() == 18)
m.peers.push_back(read_v6_endpoint<tcp::endpoint>(in));
}
read_endpoint_list<tcp::endpoint>(n, m.peers);
#ifdef TORRENT_DHT_VERBOSE_LOGGING
TORRENT_LOG(dht_tracker) << " peers: " << m.peers.size();
#endif
}
m.nodes.clear();
if (entry const* n = r.find_key("nodes"))
{
m.nodes.clear();
std::string const& nodes = n->string();
std::string::const_iterator i = nodes.begin();
std::string::const_iterator end = nodes.end();
@ -473,6 +468,31 @@ namespace libtorrent { namespace dht
#endif
}
if (entry const* n = r.find_key("nodes2"))
{
entry::list_type const& contacts = n->list();
for (entry::list_type::const_iterator i = contacts.begin()
, end(contacts.end()); i != end; ++i)
{
std::string const& p = i->string();
if (p.size() < 6 + 20) continue;
std::string::const_iterator in = p.begin();
node_id id;
std::copy(in, in + 20, id.begin());
in += 20;
if (p.size() == 6 + 20)
m.nodes.push_back(libtorrent::dht::node_entry(
id, read_v4_endpoint<udp::endpoint>(in)));
else if (p.size() == 18 + 20)
m.nodes.push_back(libtorrent::dht::node_entry(
id, read_v6_endpoint<udp::endpoint>(in)));
}
#ifdef TORRENT_DHT_VERBOSE_LOGGING
TORRENT_LOG(dht_tracker) << " nodes2 + nodes: " << m.nodes.size();
#endif
}
entry const* token = r.find_key("token");
if (token) m.write_token = *token;
}
@ -697,17 +717,39 @@ namespace libtorrent { namespace dht
break;
case messages::find_node:
{
bool ipv6_nodes = false;
r["nodes"] = entry(entry::string_t);
entry& n = r["nodes"];
std::back_insert_iterator<std::string> out(n.string());
for (msg::nodes_t::const_iterator i = m.nodes.begin()
, end(m.nodes.end()); i != end; ++i)
{
if (!i->addr.address().is_v4())
{
ipv6_nodes = true;
continue;
}
std::copy(i->id.begin(), i->id.end(), out);
write_endpoint(i->addr, out);
}
if (ipv6_nodes)
{
r["nodes2"] = entry(entry::list_t);
entry& p = r["nodes2"];
std::string endpoint;
endpoint.resize(6);
for (msg::nodes_t::const_iterator i = m.nodes.begin()
, end(m.nodes.end()); i != end; ++i)
{
std::string::iterator out = endpoint.begin();
std::copy(i->id.begin(), i->id.end(), out);
write_endpoint(i->addr, out);
p.list().push_back(entry(endpoint));
}
}
#ifdef TORRENT_DHT_VERBOSE_LOGGING
TORRENT_LOG(dht_tracker) << " nodes: " << m.nodes.size();
TORRENT_LOG(dht_tracker) << " nodes: " << m.nodes.size();
#endif
break;
}
@ -721,6 +763,7 @@ namespace libtorrent { namespace dht
for (msg::nodes_t::const_iterator i = m.nodes.begin()
, end(m.nodes.end()); i != end; ++i)
{
if (!i->addr.address().is_v4()) continue;
std::copy(i->id.begin(), i->id.end(), out);
write_endpoint(i->addr, out);
}