premiere-libtorrent/include/libtorrent/aux_/session_impl.hpp

/*

Copyright (c) 2006, Arvid Norberg
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.

*/

#ifndef TORRENT_SESSION_IMPL_HPP_INCLUDED
#define TORRENT_SESSION_IMPL_HPP_INCLUDED

#include <algorithm>
#include <vector>
#include <set>
#include <list>

#ifndef TORRENT_DISABLE_GEO_IP
#ifdef WITH_SHIPPED_GEOIP_H
#include "libtorrent/GeoIP.h"
#else
#include <GeoIP.h>
#endif
#endif

#ifdef _MSC_VER
#pragma warning(push, 1)
#endif

#include <boost/pool/object_pool.hpp>

#ifdef _MSC_VER
#pragma warning(pop)
#endif

#include "libtorrent/torrent_handle.hpp"
#include "libtorrent/entry.hpp"
#include "libtorrent/socket.hpp"
#include "libtorrent/peer_id.hpp"
#include "libtorrent/tracker_manager.hpp"
#include "libtorrent/debug.hpp"
#include "libtorrent/piece_block_progress.hpp"
#include "libtorrent/ip_filter.hpp"
#include "libtorrent/config.hpp"
#include "libtorrent/session_settings.hpp"
#include "libtorrent/session_status.hpp"
#include "libtorrent/add_torrent_params.hpp"
#include "libtorrent/stat.hpp"
#include "libtorrent/file_pool.hpp"
#include "libtorrent/bandwidth_manager.hpp"
#include "libtorrent/socket_type.hpp"
#include "libtorrent/connection_queue.hpp"
#include "libtorrent/disk_io_thread.hpp"
#include "libtorrent/udp_socket.hpp"
#include "libtorrent/assert.hpp"
#include "libtorrent/thread.hpp"
#include "libtorrent/policy.hpp" // for policy::peer
#include "libtorrent/alert.hpp" // for alert_manager
#include "libtorrent/deadline_timer.hpp"
#include "libtorrent/socket_io.hpp" // for print_address
#include "libtorrent/address.hpp"
#include "libtorrent/utp_socket_manager.hpp"
#include "libtorrent/bloom_filter.hpp"
#include "libtorrent/rss.hpp"

#if TORRENT_COMPLETE_TYPES_REQUIRED
#include "libtorrent/peer_connection.hpp"
#endif

#ifdef TORRENT_USE_OPENSSL
#include <boost/asio/ssl/context.hpp>
#endif

#if defined TORRENT_STATS && defined __MACH__
#include <mach/vm_statistics.h>
#include <mach/mach_init.h>
#include <mach/host_info.h>
#include <mach/mach_host.h>
#endif

namespace libtorrent
{

	struct plugin;
	class upnp;
	class natpmp;
	class lsd;
	struct fingerprint;
	class torrent;
	class alert;

	namespace dht
	{
		struct dht_tracker;
	}

	struct bencode_map_entry;

	struct listen_socket_t
	{
		listen_socket_t(): external_port(0), ssl(false) {}

		// this is typically empty but can be set
		// to the WAN IP address of NAT-PMP or UPnP router
		address external_address;

		// this is typically set to the same as the local
		// listen port. In case a NAT port forward was
		// successfully opened, this will be set to the
		// port that is open on the external (NAT) interface
		// on the NAT box itself. This is the port that has
		// to be published to peers, since this is the port
		// the client is reachable through.
		int external_port;

		// set to true if this is an SSL listen socket
		bool ssl;

		// the actual socket
		boost::shared_ptr<socket_acceptor> sock;
	};

	namespace aux
	{
		struct session_impl;

#if defined TORRENT_STATS && !defined __MACH__
		struct vm_statistics_data_t
		{
			boost::uint64_t active_count;
			boost::uint64_t inactive_count;
			boost::uint64_t wire_count;
			boost::uint64_t free_count;
			boost::uint64_t pageins;
			boost::uint64_t pageouts;
			boost::uint64_t faults;
		};
#endif

		struct thread_cpu_usage
		{
			ptime user_time;
			ptime system_time;
		};

#if defined TORRENT_VERBOSE_LOGGING || defined TORRENT_LOGGING || defined TORRENT_ERROR_LOGGING
		struct tracker_logger;
#endif

		// used to initialize the g_current_time before
		// anything else
		struct initialize_timer
		{
			initialize_timer();
		};

		std::pair<bencode_map_entry*, int> settings_map();

		// this is the link between the main thread and the
		// thread started to run the main downloader loop
		struct TORRENT_EXPORT session_impl: boost::noncopyable, initialize_timer
			, boost::enable_shared_from_this<session_impl>
		{

			// the size of each allocation that is chained in the send buffer
			enum { send_buffer_size = 128 };

#ifdef TORRENT_DEBUG
			friend class ::libtorrent::peer_connection;
#endif
			friend struct checker_impl;
			friend class invariant_access;
			typedef std::set<boost::intrusive_ptr<peer_connection> > connection_map;
			typedef std::map<sha1_hash, boost::shared_ptr<torrent> > torrent_map;

			session_impl(
				std::pair<int, int> listen_port_range
				, fingerprint const& cl_fprint
				, char const* listen_interface
				, boost::uint32_t alert_mask
#if defined TORRENT_VERBOSE_LOGGING || defined TORRENT_LOGGING || defined TORRENT_ERROR_LOGGING
				, std::string const& logpath
#endif
				);
			~session_impl();
			void init();
			void start_session();

#ifndef TORRENT_DISABLE_EXTENSIONS
			void add_extension(boost::function<boost::shared_ptr<torrent_plugin>(
				torrent*, void*)> ext);
			void add_ses_extension(boost::shared_ptr<plugin> ext);
#endif
#ifdef TORRENT_DEBUG
			bool has_peer(peer_connection const* p) const
			{
				TORRENT_ASSERT(is_network_thread());
				return std::find_if(m_connections.begin(), m_connections.end()
					, boost::bind(&boost::intrusive_ptr<peer_connection>::get, _1) == p)
					!= m_connections.end();
			}
#endif
			void main_thread();

			void open_listen_port(int flags, error_code& ec);

			// if we are listening on an IPv6 interface
			// this will return one of the IPv6 addresses on this
			// machine, otherwise just an empty endpoint
			tcp::endpoint get_ipv6_interface() const;
			tcp::endpoint get_ipv4_interface() const;

			void async_accept(boost::shared_ptr<socket_acceptor> const& listener, bool ssl);
			void on_accept_connection(boost::shared_ptr<socket_type> const& s
				, boost::weak_ptr<socket_acceptor> listener, error_code const& e, bool ssl);
			void on_socks_accept(boost::shared_ptr<socket_type> const& s
				, error_code const& e);

			void incoming_connection(boost::shared_ptr<socket_type> const& s);
		
#if defined TORRENT_DEBUG || TORRENT_RELEASE_ASSERTS
			bool is_network_thread() const
			{
#if defined BOOST_HAS_PTHREADS
				if (m_network_thread == 0) return true;
				return m_network_thread == pthread_self();
#endif
				return true;
			}
#endif

			feed_handle add_feed(feed_settings const& feed);
			void remove_feed(feed_handle h);
			void get_feeds(std::vector<feed_handle>* f) const;

			boost::weak_ptr<torrent> find_torrent(sha1_hash const& info_hash);
			boost::weak_ptr<torrent> find_torrent(std::string const& uuid);

			peer_id const& get_peer_id() const { return m_peer_id; }

			void close_connection(peer_connection const* p, error_code const& ec);

			void set_settings(session_settings const& s);
			session_settings const& settings() const { return m_settings; }

#ifndef TORRENT_DISABLE_DHT	
			void add_dht_node_name(std::pair<std::string, int> const& node);
			void add_dht_node(udp::endpoint n);
			void add_dht_router(std::pair<std::string, int> const& node);
			void set_dht_settings(dht_settings const& s);
			dht_settings const& get_dht_settings() const { return m_dht_settings; }
			void start_dht();
			void stop_dht();
			void start_dht(entry const& startup_state);

#ifndef TORRENT_NO_DEPRECATE
			entry dht_state() const;
#endif
			void on_dht_announce(error_code const& e);
			void on_dht_router_name_lookup(error_code const& e
				, tcp::resolver::iterator host);
#endif

			void maybe_update_udp_mapping(int nat, int local_port, int external_port);

#ifndef TORRENT_DISABLE_ENCRYPTION
			void set_pe_settings(pe_settings const& settings);
			pe_settings const& get_pe_settings() const { return m_pe_settings; }
#endif

			void on_port_map_log(char const* msg, int map_transport);

			void on_lsd_announce(error_code const& e);

			// called when a port mapping is successful, or a router returns
			// a failure to map a port
			void on_port_mapping(int mapping, address const& ip, int port
				, error_code const& ec, int nat_transport);

			bool is_aborted() const { return m_abort; }
			bool is_paused() const { return m_paused; }

			void pause();
			void resume();

			void set_ip_filter(ip_filter const& f);
			ip_filter const& get_ip_filter() const;
			
			void set_port_filter(port_filter const& f);

			void  listen_on(
				std::pair<int, int> const& port_range
				, error_code& ec
				, const char* net_interface = 0
				, int flags = 0);
			bool is_listening() const;

			torrent_handle add_torrent(add_torrent_params const&, error_code& ec);
			void async_add_torrent(add_torrent_params* params);

			void remove_torrent(torrent_handle const& h, int options);
			void remove_torrent_impl(boost::shared_ptr<torrent> tptr, int options);

			void get_torrent_status(std::vector<torrent_status>* ret
				, boost::function<bool(torrent_status const&)> const& pred
				, boost::uint32_t flags) const;
			void refresh_torrent_status(std::vector<torrent_status>* ret
				, boost::uint32_t flags) const;
			void post_torrent_updates();

			std::vector<torrent_handle> get_torrents() const;
			
			void queue_check_torrent(boost::shared_ptr<torrent> const& t);
			void dequeue_check_torrent(boost::shared_ptr<torrent> const& t);

			void set_alert_mask(boost::uint32_t m);
			size_t set_alert_queue_size_limit(size_t queue_size_limit_);
			std::auto_ptr<alert> pop_alert();
			void pop_alerts(std::deque<alert*>* alerts);
			void set_alert_dispatch(boost::function<void(std::auto_ptr<alert>)> const&);
			void post_alert(const alert& alert_);

			alert const* wait_for_alert(time_duration max_wait);

#ifndef TORRENT_NO_DEPRECATE
			int upload_rate_limit() const;
			int download_rate_limit() const;
			int local_upload_rate_limit() const;
			int local_download_rate_limit() const;

			void set_local_download_rate_limit(int bytes_per_second);
			void set_local_upload_rate_limit(int bytes_per_second);
			void set_download_rate_limit(int bytes_per_second);
			void set_upload_rate_limit(int bytes_per_second);
			void set_max_half_open_connections(int limit);
			void set_max_connections(int limit);
			void set_max_uploads(int limit);

			int max_connections() const;
			int max_uploads() const;
			int max_half_open_connections() const;

#endif

			int num_uploads() const { return m_num_unchoked; }
			int num_connections() const
			{ return m_connections.size(); }

			void unchoke_peer(peer_connection& c);
			void choke_peer(peer_connection& c);

			session_status status() const;
			void set_peer_id(peer_id const& id);
			void set_key(int key);
			address listen_address() const;
			boost::uint16_t listen_port() const;
			boost::uint16_t ssl_listen_port() const;
			
			void abort();
			
			torrent_handle find_torrent_handle(sha1_hash const& info_hash);

			void announce_lsd(sha1_hash const& ih, int port, bool broadcast = false);

			void save_state(entry* e, boost::uint32_t flags) const;
			void load_state(lazy_entry const* e);

			void set_proxy(proxy_settings const& s);
			proxy_settings const& proxy() const { return m_proxy; }

#ifndef TORRENT_NO_DEPRECATE
			void set_peer_proxy(proxy_settings const& s) { set_proxy(s); }
			void set_web_seed_proxy(proxy_settings const& s) { set_proxy(s); }
			void set_tracker_proxy(proxy_settings const& s) { set_proxy(s); }
			proxy_settings const& peer_proxy() const { return proxy(); }
			proxy_settings const& web_seed_proxy() const { return proxy(); }
			proxy_settings const& tracker_proxy() const { return proxy(); }

#ifndef TORRENT_DISABLE_DHT
			void set_dht_proxy(proxy_settings const& s) { set_proxy(s); }
			proxy_settings const& dht_proxy() const { return proxy(); }
#endif
#endif // TORRENT_NO_DEPRECATE

#ifndef TORRENT_DISABLE_DHT
			bool is_dht_running() const { return m_dht; }
#endif

#if TORRENT_USE_I2P
			void set_i2p_proxy(proxy_settings const& s)
			{
				m_i2p_conn.open(s, boost::bind(&session_impl::on_i2p_open, this, _1));
				open_new_incoming_i2p_connection();
			}
			void on_i2p_open(error_code const& ec);
			proxy_settings const& i2p_proxy() const
			{ return m_i2p_conn.proxy(); }
			void open_new_incoming_i2p_connection();
			void on_i2p_accept(boost::shared_ptr<socket_type> const& s
				, error_code const& e);
#endif

#ifndef TORRENT_DISABLE_GEO_IP
			std::string as_name_for_ip(address const& a);
			int as_for_ip(address const& a);
			std::pair<const int, int>* lookup_as(int as);
			void load_asnum_db(std::string file);
			bool has_asnum_db() const { return m_asnum_db; }

			void load_country_db(std::string file);
			bool has_country_db() const { return m_country_db; }
			char const* country_for_ip(address const& a);

#if TORRENT_USE_WSTRING
			void load_asnum_dbw(std::wstring file);
			void load_country_dbw(std::wstring file);
#endif // TORRENT_USE_WSTRING
#endif // TORRENT_DISABLE_GEO_IP

			void start_lsd();
			natpmp* start_natpmp();
			upnp* start_upnp();

			void stop_lsd();
			void stop_natpmp();
			void stop_upnp();

			int next_port();

			void add_redundant_bytes(size_type b, int reason)
			{
				TORRENT_ASSERT(b > 0);
				m_total_redundant_bytes += b;
				m_redundant_bytes[reason] += b;
			}

			void add_failed_bytes(size_type b)
			{
				TORRENT_ASSERT(b > 0);
				m_total_failed_bytes += b;
			}

			char* allocate_buffer();
			void free_buffer(char* buf);

			char* allocate_disk_buffer(char const* category);
			void free_disk_buffer(char* buf);

			enum
			{
				source_dht = 1,
				source_peer = 2,
				source_tracker = 4,
				source_router = 8
			};

			void set_external_address(address const& ip
				, int source_type, address const& source);
			address const& external_address() const { return m_external_address; }

			bool can_write_to_disk() const
			{ return m_disk_thread.can_write(); }

			// used when posting synchronous function
			// calls to session_impl and torrent objects
			mutable libtorrent::mutex mut;
			mutable libtorrent::condition cond;

			void inc_disk_queue(int channel)
			{
				TORRENT_ASSERT(channel >= 0 && channel < 2);
				++m_disk_queues[channel];
			}

			void dec_disk_queue(int channel)
			{
				TORRENT_ASSERT(channel >= 0 && channel < 2);
				TORRENT_ASSERT(m_disk_queues[channel] > 0);
				--m_disk_queues[channel];
			}

#if defined TORRENT_DEBUG || TORRENT_RELEASE_ASSERTS
			bool in_state_updates(boost::shared_ptr<torrent> t)
			{
				return std::find_if(m_state_updates.begin(), m_state_updates.end()
					, boost::bind(&boost::weak_ptr<torrent>::lock, _1) == t) != m_state_updates.end();
			}
#endif

			void add_to_update_queue(boost::weak_ptr<torrent> t)
			{
				TORRENT_ASSERT(std::find_if(m_state_updates.begin(), m_state_updates.end()
					, boost::bind(&boost::weak_ptr<torrent>::lock, _1) == t.lock()) == m_state_updates.end());
				m_state_updates.push_back(t);
			}

//		private:

			void update_connections_limit();
			void update_unchoke_limit();
			void update_rate_settings();

			void update_disk_thread_settings();
			void on_lsd_peer(tcp::endpoint peer, sha1_hash const& ih);
			void setup_socket_buffers(socket_type& s);

			// the settings for the client
			session_settings m_settings;

			// this is a shared pool where policy_peer objects
			// are allocated. It's a pool since we're likely
			// to have tens of thousands of peers, and a pool
			// saves significant overhead
#ifdef TORRENT_STATS
			struct logging_allocator
			{
				typedef std::size_t size_type;
				typedef std::ptrdiff_t difference_type;

				static char* malloc(const size_type bytes)
				{
					allocated_bytes += bytes;
					++allocations;
					return (char*)::malloc(bytes);
				}

				static void free(char* const block)
				{
					--allocations;
					return ::free(block);
				}
			
				static int allocations;
				static int allocated_bytes;
			};
			boost::object_pool<
				policy::ipv4_peer, logging_allocator> m_ipv4_peer_pool;
#if TORRENT_USE_IPV6
			boost::object_pool<
				policy::ipv6_peer, logging_allocator> m_ipv6_peer_pool;
#endif
#if TORRENT_USE_I2P
			boost::object_pool<
				policy::i2p_peer, logging_allocator> m_i2p_peer_pool;
#endif
#else
			boost::object_pool<policy::ipv4_peer> m_ipv4_peer_pool;
#if TORRENT_USE_IPV6
			boost::object_pool<policy::ipv6_peer> m_ipv6_peer_pool;
#endif
#if TORRENT_USE_I2P
			boost::object_pool<policy::i2p_peer> m_i2p_peer_pool;
#endif
#endif

			// this vector is used to store the block_info
			// objects pointed to by partial_piece_info returned
			// by torrent::get_download_queue.
			std::vector<block_info> m_block_info_storage;

#ifndef TORRENT_DISABLE_POOL_ALLOCATOR
			// this pool is used to allocate and recycle send
			// buffers from.
			boost::pool<> m_send_buffers;
#endif

			// the file pool that all storages in this session's
			// torrents uses. It sets a limit on the number of
			// open files by this session.
			// file pool must be destructed after the torrents
			// since they will still have references to it
			// when they are destructed.
			file_pool m_files;

			// this is where all active sockets are stored.
			// the selector can sleep while there's no activity on
			// them
			mutable io_service m_io_service;

#ifdef TORRENT_USE_OPENSSL
			// this is a generic SSL context used when talking to
			// unauthenticated HTTPS servers
			asio::ssl::context m_ssl_ctx;
#endif

			// handles delayed alerts
			alert_manager m_alerts;

			// handles disk io requests asynchronously
			// peers have pointers into the disk buffer
			// pool, and must be destructed before this
			// object. The disk thread relies on the file
			// pool object, and must be destructed before
			// m_files. The disk io thread posts completion
			// events to the io service, and needs to be
			// constructed after it.
			disk_io_thread m_disk_thread;

			// this is a list of half-open tcp connections
			// (only outgoing connections)
			// this has to be one of the last
			// members to be destructed
			connection_queue m_half_open;

			// the bandwidth manager is responsible for
			// handing out bandwidth to connections that
			// asks for it, it can also throttle the
			// rate.
			bandwidth_manager m_download_rate;
			bandwidth_manager m_upload_rate;

			// the global rate limiter bandwidth channels
			bandwidth_channel m_download_channel;
			bandwidth_channel m_upload_channel;

			// bandwidth channels for local peers when
			// rate limits are ignored. They are only
			// throttled by these global rate limiters
			// and they don't have a rate limit set by
			// default
			bandwidth_channel m_local_download_channel;
			bandwidth_channel m_local_upload_channel;

			// all tcp peer connections are subject to these
			// bandwidth limits. Local peers are excempted
			// from this limit. The purpose is to be able to
			// throttle TCP that passes over the internet
			// bottleneck (i.e. modem) to avoid starving out
			// uTP connections.
			bandwidth_channel m_tcp_download_channel;
			bandwidth_channel m_tcp_upload_channel;

			bandwidth_channel* m_bandwidth_channel[2];

			// the number of peer connections that are waiting
			// for the disk. one for each channel.
			// upload_channel means waiting to read from disk
			// and download_channel is waiting to write to disk
			int m_disk_queues[2];

			tracker_manager m_tracker_manager;
			torrent_map m_torrents;
			std::map<std::string, boost::shared_ptr<torrent> > m_uuids;

			// these are all the torrents using full AES-256 encryption of
			// all peer connections. When receiving a handshake that's encrypred
			// these are the torrents we need to try to decrypt it with to
			// find the decryption key
			std::set<boost::shared_ptr<torrent> > m_encrypted_torrents;

			typedef std::list<boost::shared_ptr<torrent> > check_queue_t;

			// this has all torrents that wants to be checked in it
			check_queue_t m_queued_for_checking;

			// this maps sockets to their peer_connection
			// object. It is the complete list of all connected
			// peers.
			connection_map m_connections;
			
			// filters incoming connections
			ip_filter m_ip_filter;

			// filters outgoing connections
			port_filter m_port_filter;
			
			// the peer id that is generated at the start of the session
			peer_id m_peer_id;

			// the key is an id that is used to identify the
			// client with the tracker only. It is randomized
			// at startup
			int m_key;

			// the number of retries we make when binding the
			// listen socket. For each retry the port number
			// is incremented by one
			int m_listen_port_retries;

			// the ip-address of the interface
			// we are supposed to listen on.
			// if the ip is set to zero, it means
			// that we should let the os decide which
			// interface to listen on
			tcp::endpoint m_listen_interface;

			// if we're listening on an IPv6 interface
			// this is one of the non local IPv6 interfaces
			// on this machine
			tcp::endpoint m_ipv6_interface;
			tcp::endpoint m_ipv4_interface;
			
			// since we might be listening on multiple interfaces
			// we might need more than one listen socket
			std::list<listen_socket_t> m_listen_sockets;

#ifdef TORRENT_USE_OPENSSL
			void ssl_handshake(error_code const& ec, boost::shared_ptr<socket_type> s);
#endif

			// when as a socks proxy is used for peers, also
			// listen for incoming connections on a socks connection
			boost::shared_ptr<socket_type> m_socks_listen_socket;
			boost::uint16_t m_socks_listen_port;

			void open_new_incoming_socks_connection();

#if TORRENT_USE_I2P
			i2p_connection m_i2p_conn;
			boost::shared_ptr<socket_type> m_i2p_listen_socket;
#endif

			void setup_listener(listen_socket_t* s, tcp::endpoint ep, int retries
				, bool v6_only, int flags, error_code& ec);

			// the proxy used for bittorrent
			proxy_settings m_proxy;

#ifndef TORRENT_DISABLE_DHT	
			entry m_dht_state;
#endif
			// set to true when the session object
			// is being destructed and the thread
			// should exit
			bool m_abort;

			// is true if the session is paused
			bool m_paused;

			// the number of unchoked peers as set by the auto-unchoker
			// this should always be >= m_max_uploads
			int m_allowed_upload_slots;

			// the number of unchoked peers
			int m_num_unchoked;

			// this is initialized to the unchoke_interval
			// session_setting and decreased every second.
			// when it reaches zero, it is reset to the
			// unchoke_interval and the unchoke set is
			// recomputed.
			int m_unchoke_time_scaler;

			// this is used to decide when to recalculate which
			// torrents to keep queued and which to activate
			int m_auto_manage_time_scaler;

			// works like unchoke_time_scaler but it
			// is only decresed when the unchoke set
			// is recomputed, and when it reaches zero,
			// the optimistic unchoke is moved to another peer.
			int m_optimistic_unchoke_time_scaler;

			// works like unchoke_time_scaler. Each time
			// it reaches 0, and all the connections are
			// used, the worst connection will be disconnected
			// from the torrent with the most peers
			int m_disconnect_time_scaler;

			// when this scaler reaches zero, it will
			// scrape one of the auto managed, paused,
			// torrents.
			int m_auto_scrape_time_scaler;

			// the index of the torrent that we'll
			// refresh the next time
			int m_next_explicit_cache_torrent;

			// this is a counter of the number of seconds until
			// the next time the read cache is rotated, if we're
			// using an explicit read read cache.
			int m_cache_rotation_timer;

			// statistics gathered from all torrents.
			stat m_stat;

			int m_peak_up_rate;
			int m_peak_down_rate;

			// is false by default and set to true when
			// the first incoming connection is established
			// this is used to know if the client is behind
			// NAT or not.
			bool m_incoming_connection;
			
			void on_disk_queue();
			void on_tick(error_code const& e);

			void auto_manage_torrents(std::vector<torrent*>& list
				, int& dht_limit, int& tracker_limit, int& lsd_limit
				, int& hard_limit, int type_limit);
			void recalculate_auto_managed_torrents();
			void recalculate_unchoke_slots(int congested_torrents
				, int uncongested_torrents);
			void recalculate_optimistic_unchoke_slots();

			ptime m_created;
			int session_time() const { return total_seconds(time_now() - m_created); }

			ptime m_last_tick;
			ptime m_last_second_tick;
			// used to limit how often disk warnings are generated
			ptime m_last_disk_performance_warning;
			ptime m_last_disk_queue_performance_warning;

			// the last time we went through the peers
			// to decide which ones to choke/unchoke
			ptime m_last_choke;

			// the time when the next rss feed needs updating
			ptime m_next_rss_update;

			// update any rss feeds that need updating and
			// recalculate m_next_rss_update
			void update_rss_feeds();

			// when outgoing_ports is configured, this is the
			// port we'll bind the next outgoing socket to
			int m_next_port;

#ifndef TORRENT_DISABLE_DHT
			boost::intrusive_ptr<dht::dht_tracker> m_dht;
			dht_settings m_dht_settings;
			
			// these are used when starting the DHT
			// (and bootstrapping it), and then erased
			std::list<udp::endpoint> m_dht_router_nodes;

			// this announce timer is used
			// by the DHT.
			deadline_timer m_dht_announce_timer;
#endif

			void on_receive_udp(error_code const& e
				, udp::endpoint const& ep, char const* buf, int len);

			void on_receive_udp_hostname(error_code const& e
				, char const* hostname, char const* buf, int len);

			// see m_external_listen_port. This is the same
			// but for the udp port used by the DHT.
			int m_external_udp_port;

			rate_limited_udp_socket m_udp_socket;

			utp_socket_manager m_utp_socket_manager;

			// the number of torrent connection boosts
			// connections that have been made this second
			// this is deducted from the connect speed
			int m_boost_connections;

#ifndef TORRENT_DISABLE_ENCRYPTION
			pe_settings m_pe_settings;
#endif

			boost::intrusive_ptr<natpmp> m_natpmp;
			boost::intrusive_ptr<upnp> m_upnp;
			boost::intrusive_ptr<lsd> m_lsd;

			// mask is a bitmask of which protocols to remap on:
			// 1: NAT-PMP
			// 2: UPnP
			void remap_tcp_ports(boost::uint32_t mask, int tcp_port, int ssl_port);

			// 0 is natpmp 1 is upnp
			int m_tcp_mapping[2];
			int m_udp_mapping[2];
#ifdef TORRENT_USE_OPENSSL
			int m_ssl_mapping[2];
#endif

			// the timer used to fire the tick
			deadline_timer m_timer;

			// torrents are announced on the local network in a
			// round-robin fashion. All torrents are cycled through
			// within the LSD announce interval (which defaults to
			// 5 minutes)
			torrent_map::iterator m_next_lsd_torrent;

#ifndef TORRENT_DISABLE_DHT
			// torrents are announced on the DHT in a
			// round-robin fashion. All torrents are cycled through
			// within the DHT announce interval (which defaults to
			// 15 minutes)
			torrent_map::iterator m_next_dht_torrent;
#endif

			// this announce timer is used
			// by Local service discovery
			deadline_timer m_lsd_announce_timer;

			tcp::resolver m_host_resolver;

			// the index of the torrent that will be offered to
			// connect to a peer next time on_tick is called.
			// This implements a round robin.
			torrent_map::iterator m_next_connect_torrent;

			// this is the round-robin cursor for peers that
			// get to download again after the disk has been
			// blocked
			connection_map::iterator m_next_disk_peer;
#ifdef TORRENT_DEBUG
			void check_invariant() const;
#endif

#ifdef TORRENT_DISK_STATS
			void log_buffer_usage();
			// used to log send buffer usage statistics
			std::ofstream m_buffer_usage_logger;
			// the number of send buffers that are allocated
			int m_buffer_allocations;
#endif

#ifdef TORRENT_REQUEST_LOGGING
			// used to log all requests from peers
			FILE* m_request_log;
#endif

#ifdef TORRENT_STATS
			void rotate_stats_log();
			void print_log_line(int tick_interval_ms, ptime now);
			void reset_stat_counters();
			void enable_stats_logging(bool s);

			bool m_stats_logging_enabled;

			// the last time we rotated the log file
			ptime m_last_log_rotation;
	
			// logger used to write bandwidth usage statistics
			FILE* m_stats_logger;
			// sequence number for log file. Log files are
			// rotated every hour and the sequence number is
			// incremented by one
			int m_log_seq;
			// the number of peers that were disconnected this
			// tick due to protocol error
			int m_error_peers;
			int m_disconnected_peers;
			int m_eof_peers;
			int m_connreset_peers;
			// the number of times the piece picker fell through
			// to the end-game mode
			int m_end_game_piece_picker_blocks;
			int m_piece_picker_blocks;
			int m_piece_picks;
			int m_reject_piece_picks;
			int m_unchoke_piece_picks;
			int m_incoming_redundant_piece_picks;
			int m_incoming_piece_picks;
			int m_end_game_piece_picks;
			int m_snubbed_piece_picks;
			int m_connect_timeouts;
			int m_uninteresting_peers;
			int m_timeout_peers;
			int m_no_memory_peers;
			int m_too_many_peers;
			int m_transport_timeout_peers;
			cache_status m_last_cache_status;
			size_type m_last_failed;
			size_type m_last_redundant;
			size_type m_last_uploaded;
			size_type m_last_downloaded;
			int m_connection_attempts;
			int m_num_banned_peers;
			int m_banned_for_hash_failure;
			vm_statistics_data_t m_last_vm_stat;
			thread_cpu_usage m_network_thread_cpu_usage;
			sliding_average<20> m_read_ops;
			sliding_average<20> m_write_ops;;
			enum
			{
				on_read_counter,
				on_write_counter,
				on_tick_counter,
				on_lsd_counter,
				on_lsd_peer_counter,
				on_udp_counter,
				on_accept_counter,
				on_disk_queue_counter,
				on_disk_read_counter,
				on_disk_write_counter,
				max_messages
			};
			int m_num_messages[max_messages];
			// 8, 16, 32, 64, 128, 256, 512, 1024, 2048, 4096, 8192,
			// 16384, 32768, 65536, 131072, 262144, 524288, 1048576
			int m_send_buffer_sizes[18];
			int m_recv_buffer_sizes[18];
#endif

			// each second tick the timer takes a little
			// bit longer than one second to trigger. The
			// extra time it took is accumulated into this
			// counter. Every time it exceeds 1000, torrents
			// will tick their timers 2 seconds instead of one.
			// this keeps the timers more accurate over time
			// as a kind of "leap second" to adjust for the
			// accumulated error
			boost::uint16_t m_tick_residual;

			// the number of torrents that have apply_ip_filter
			// set to false. This is typically 0
			int m_non_filtered_torrents;

#if defined TORRENT_VERBOSE_LOGGING || defined TORRENT_LOGGING || defined TORRENT_ERROR_LOGGING
			boost::shared_ptr<logger> create_log(std::string const& name
				, int instance, bool append = true);
			
			// this list of tracker loggers serves as tracker_callbacks when
			// shutting down. This list is just here to keep them alive during
			// whe shutting down process
			std::list<boost::shared_ptr<tracker_logger> > m_tracker_loggers;

			std::string m_logpath;
		public:
			boost::shared_ptr<logger> m_logger;

		private:

#endif
#ifdef TORRENT_UPNP_LOGGING
			std::ofstream m_upnp_log;
#endif
			struct external_ip_t
			{
				external_ip_t(): sources(0), num_votes(0) {}

				bool add_vote(sha1_hash const& k, int type);
				bool operator<(external_ip_t const& rhs) const
				{
					if (num_votes < rhs.num_votes) return true;
					if (rhs.num_votes > num_votes) return false;
					return sources < rhs.sources;
				}

				// this is a bloom filter of the IPs that have
				// reported this address
				bloom_filter<16> voters;
				// this is the actual external address
				address addr;
				// a bitmask of sources the reporters have come from
				boost::uint16_t sources;
				// the total number of votes for this IP
				boost::uint16_t num_votes;
			};

			// this is a bloom filter of all the IPs that have
			// been the first to report an external address. Each
			// IP only gets to add a new item once.
			bloom_filter<32> m_external_address_voters;
			std::vector<external_ip_t> m_external_addresses;
			address m_external_address;

#ifndef TORRENT_DISABLE_EXTENSIONS
			typedef std::list<boost::function<boost::shared_ptr<
				torrent_plugin>(torrent*, void*)> > extension_list_t;

			extension_list_t m_extensions;

			typedef std::list<boost::shared_ptr<plugin> > ses_extension_list_t;
			ses_extension_list_t m_ses_extensions;
#endif

#ifndef TORRENT_DISABLE_GEO_IP
			GeoIP* m_asnum_db;
			GeoIP* m_country_db;

			// maps AS number to the peak download rate
			// we've seen from it. Entries are never removed
			// from this map. Pointers to its elements
			// are kept in the policy::peer structures.
			std::map<int, int> m_as_peak;
#endif

			// total redundant and failed bytes
			size_type m_total_failed_bytes;
			size_type m_total_redundant_bytes;

			// redundant bytes per category
			size_type m_redundant_bytes[7];

			std::vector<boost::shared_ptr<feed> > m_feeds;

			// this is the set of (subscribed) torrents that have changed
			// their states since the last time the user requested updates.
			std::vector<boost::weak_ptr<torrent> > m_state_updates;

			// the main working thread
			boost::scoped_ptr<thread> m_thread;

#if (defined TORRENT_DEBUG || TORRENT_RELEASE_ASSERTS) && defined BOOST_HAS_PTHREADS
			pthread_t m_network_thread;
#endif
		};
		
#if defined TORRENT_VERBOSE_LOGGING || defined TORRENT_LOGGING || defined TORRENT_ERROR_LOGGING
		struct tracker_logger : request_callback
		{
			tracker_logger(session_impl& ses): m_ses(ses) {}
			void tracker_warning(tracker_request const& req
				, std::string const& str)
			{
				debug_log("*** tracker warning: " + str);
			}

			void tracker_response(tracker_request const&
				, libtorrent::address const& tracker_ip
				, std::list<address> const& ip_list
				, std::vector<peer_entry>& peers
				, int interval
				, int min_interval
				, int complete
				, int incomplete
				, address const& external_ip
				, std::string const& tracker_id)
			{
				std::string s;
				s = "TRACKER RESPONSE:\n";
				char tmp[200];
				snprintf(tmp, 200, "interval: %d\nmin_interval: %d\npeers:\n", interval, min_interval);
				s += tmp;
				for (std::vector<peer_entry>::const_iterator i = peers.begin();
					i != peers.end(); ++i)
				{
					char pid[41];
					to_hex((const char*)&i->pid[0], 20, pid);
					if (i->pid.is_all_zeros()) pid[0] = 0;

					snprintf(tmp, 200, " %-16s %-5d %s\n", i->ip.c_str(), i->port, pid);
					s += tmp;
				}
				snprintf(tmp, 200, "external ip: %s\n", print_address(external_ip).c_str());
				s += tmp;
				debug_log(s);
			}

			void tracker_request_timed_out(
				tracker_request const&)
			{
				debug_log("*** tracker timed out");
			}

			void tracker_request_error(tracker_request const& r
				, int response_code, error_code const& ec, const std::string& str
				, int retry_interval)
			{
				char msg[256];
				snprintf(msg, sizeof(msg), "*** tracker error: %d: %s %s"
					, response_code, ec.message().c_str(), str.c_str());
				debug_log(msg);
			}
			
			void debug_log(const std::string& line)
			{
				(*m_ses.m_logger) << time_now_string() << " " << line << "\n";
			}
			session_impl& m_ses;
		};
#endif

	}
}


#endif