premiere-libtorrent/src/kademlia/traversal_algorithm.cpp

/*

Copyright (c) 2006, Arvid Norberg & Daniel Wallin
All rights reserved.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions
are met:

    * Redistributions of source code must retain the above copyright
      notice, this list of conditions and the following disclaimer.
    * Redistributions in binary form must reproduce the above copyright
      notice, this list of conditions and the following disclaimer in
      the documentation and/or other materials provided with the distribution.
    * Neither the name of the author nor the names of its
      contributors may be used to endorse or promote products derived
      from this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
POSSIBILITY OF SUCH DAMAGE.

*/

#include "libtorrent/pch.hpp"

#include <libtorrent/kademlia/traversal_algorithm.hpp>
#include <libtorrent/kademlia/routing_table.hpp>
#include <libtorrent/kademlia/rpc_manager.hpp>
#include <libtorrent/kademlia/node.hpp>
#include <libtorrent/session_status.hpp>

#include <boost/bind.hpp>

namespace libtorrent { namespace dht
{
#ifdef TORRENT_DHT_VERBOSE_LOGGING
TORRENT_DEFINE_LOG(traversal)
#endif

void traversal_algorithm::add_entry(node_id const& id, udp::endpoint addr, unsigned char flags)
{
	result entry(id, addr, flags);
	if (entry.id.is_all_zeros())
	{
		entry.id = generate_id();
		entry.flags |= result::no_id;
	}

	std::vector<result>::iterator i = std::lower_bound(
		m_results.begin()
		, m_results.end()
		, entry
		, boost::bind(
			compare_ref
			, boost::bind(&result::id, _1)
			, boost::bind(&result::id, _2)
			, m_target
		)
	);

	if (i == m_results.end() || i->id != id)
	{
		TORRENT_ASSERT(std::find_if(m_results.begin(), m_results.end()
			, boost::bind(&result::id, _1) == id) == m_results.end());
#ifdef TORRENT_DHT_VERBOSE_LOGGING
		TORRENT_LOG(traversal) << "[" << this << "] adding result: " << id << " " << addr;
#endif
		m_results.insert(i, entry);
	}
}

void traversal_algorithm::start()
{
	// in case the routing table is empty, use the
	// router nodes in the table
	if (m_results.empty()) add_router_entries();
	init();
	add_requests();
}

boost::pool<>& traversal_algorithm::allocator() const
{
	return m_node.m_rpc.allocator();
}

void traversal_algorithm::traverse(node_id const& id, udp::endpoint addr)
{
#ifdef TORRENT_DHT_VERBOSE_LOGGING
	if (id.is_all_zeros())
		TORRENT_LOG(traversal) << time_now_string() << "[" << this << "] WARNING: "
			"node returned a list which included a node with id 0";
#endif
	add_entry(id, addr, 0);
}

void traversal_algorithm::finished(udp::endpoint const& ep)
{
	std::vector<result>::iterator i = std::find_if(
		m_results.begin()
		, m_results.end()
		, boost::bind(
			std::equal_to<udp::endpoint>()
			, boost::bind(&result::endpoint, _1)
			, ep
		)
	);

	TORRENT_ASSERT(i != m_results.end());

	if (i != m_results.end())
	{
		// if this flag is set, it means we increased the
		// branch factor for it, and we should restore it
		if (i->flags & result::short_timeout)
			--m_branch_factor;
	}

	i->flags |= result::alive;

	++m_responses;
	--m_invoke_count;
	TORRENT_ASSERT(m_invoke_count >= 0);
	add_requests();
	if (m_invoke_count == 0) done();
}

// prevent request means that the total number of requests has
// overflown. This query failed because it was the oldest one.
// So, if this is true, don't make another request
void traversal_algorithm::failed(udp::endpoint const& ep, int flags)
{
	TORRENT_ASSERT(m_invoke_count >= 0);

	if (m_results.empty()) return;

	std::vector<result>::iterator i = std::find_if(
		m_results.begin()
		, m_results.end()
		, boost::bind(
			std::equal_to<udp::endpoint>()
			, boost::bind(&result::endpoint, _1)
			, ep
		)
	);

	TORRENT_ASSERT(i != m_results.end());

	if (i != m_results.end())
	{
		TORRENT_ASSERT(i->flags & result::queried);
		if (flags & short_timeout)
		{
			// short timeout means that it has been more than
			// two seconds since we sent the request, and that
			// we'll most likely not get a response. But, in case
			// we do get a late response, keep the handler
			// around for some more, but open up the slot
			// by increasing the branch factor
			if ((i->flags & result::short_timeout) == 0)
				++m_branch_factor;
			i->flags |= result::short_timeout;
		}
		else
		{
			i->flags |= result::failed;
#ifdef TORRENT_DHT_VERBOSE_LOGGING
			TORRENT_LOG(traversal) << " [" << this << "] failed: "
				<< i->id << " " << i->endpoint();
#endif
			// if this flag is set, it means we increased the
			// branch factor for it, and we should restore it
			if (i->flags & result::short_timeout)
				--m_branch_factor;

			// don't tell the routing table about
			// node ids that we just generated ourself
			if ((i->flags & result::no_id) == 0)
				m_node.m_table.node_failed(i->id);
			++m_timeouts;
			--m_invoke_count;
			TORRENT_ASSERT(m_invoke_count >= 0);
		}
	}

	if (flags & prevent_request)
	{
		--m_branch_factor;
		if (m_branch_factor <= 0) m_branch_factor = 1;
	}
	add_requests();
	if (m_invoke_count == 0) done();
}

namespace
{
	bool bitwise_nand(unsigned char lhs, unsigned char rhs)
	{
		return (lhs & rhs) == 0;
	}
}

void traversal_algorithm::add_requests()
{
	int results_target = m_node.m_table.bucket_size();

	// Find the first node that hasn't already been queried.
	for (std::vector<result>::iterator i = m_results.begin()
		, end(m_results.end()); i != end
		&& results_target > 0 && m_invoke_count < m_branch_factor; ++i)
	{
		if (i->flags & result::alive) --results_target;
		if (i->flags & result::queried) continue;

#ifdef TORRENT_DHT_VERBOSE_LOGGING
		TORRENT_LOG(traversal) << " [" << this << "] nodes left: "
			<< (m_results.end() - i);
#endif

		if (invoke(i->endpoint()))
		{
			TORRENT_ASSERT(m_invoke_count >= 0);
			++m_invoke_count;
			i->flags |= result::queried;
		}
	}
}

void traversal_algorithm::add_router_entries()
{
#ifdef TORRENT_DHT_VERBOSE_LOGGING
	TORRENT_LOG(traversal) << " using router nodes to initiate traversal algorithm. "
		<< std::distance(m_node.m_table.router_begin(), m_node.m_table.router_end()) << " routers";
#endif
	for (routing_table::router_iterator i = m_node.m_table.router_begin()
		, end(m_node.m_table.router_end()); i != end; ++i)
	{
		add_entry(node_id(0), *i, result::initial);
	}
}

void traversal_algorithm::init()
{
	// update the last activity of this bucket
	m_node.m_table.touch_bucket(m_target);
	m_branch_factor = m_node.branch_factor();
	m_node.add_traversal_algorithm(this);
}

traversal_algorithm::~traversal_algorithm()
{
	m_node.remove_traversal_algorithm(this);
}

void traversal_algorithm::status(dht_lookup& l)
{
	l.timeouts = m_timeouts;
	l.responses = m_responses;
	l.outstanding_requests = m_invoke_count;
	l.branch_factor = m_branch_factor;
	l.type = name();
	l.nodes_left = 0;
	for (std::vector<result>::iterator i = m_results.begin()
		, end(m_results.end()); i != end; ++i)
	{
		if (i->flags & result::queried) continue;
		++l.nodes_left;
	}
}

} } // namespace libtorrent::dht