premiere-libtorrent/include/libtorrent/policy.hpp

/*

Copyright (c) 2003-2013, Arvid Norberg
All rights reserved.

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modification, are permitted provided that the following conditions
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    * Redistributions in binary form must reproduce the above copyright
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      the documentation and/or other materials provided with the distribution.
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      contributors may be used to endorse or promote products derived
      from this software without specific prior written permission.

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AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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*/

#ifndef TORRENT_POLICY_HPP_INCLUDED
#define TORRENT_POLICY_HPP_INCLUDED

#include <algorithm>
#include <deque>
#include "libtorrent/string_util.hpp" // for allocate_string_copy

#include "libtorrent/peer.hpp"
#include "libtorrent/piece_picker.hpp"
#include "libtorrent/socket.hpp"
#include "libtorrent/address.hpp"
#include "libtorrent/size_type.hpp"
#include "libtorrent/invariant_check.hpp"
#include "libtorrent/config.hpp"

namespace libtorrent
{

	class torrent;
	class peer_connection;
	struct external_ip;

	// this is compressed as an unsigned floating point value
	// the top 13 bits are the mantissa and the low
	// 3 bits is the unsigned exponent. The exponent
	// has an implicit + 4 as well.
	// This means that the resolution is no less than 16
	// The actual rate is: (upload_rate >> 4) << ((upload_rate & 0xf) + 4)
	// the resolution gets worse the higher the value is
	// min value is 0, max value is 16775168
	struct ufloat16
	{
		ufloat16():m_val(0) {}
		ufloat16(int v)
		{ *this = v; }
		operator int()
		{
			return (m_val >> 3) << ((m_val & 7) + 4);
		}

		ufloat16& operator=(int v)
		{
			if (v > 0x1fff << (7 + 4)) m_val = 0xffff;
			else if (v <= 0) m_val = 0;
			else
			{
				int exp = 4;
				v >>= 4;
				while (v > 0x1fff)
				{
					v >>= 1;
					++exp;
				}
				TORRENT_ASSERT(exp <= 7);
				m_val = (v << 3) || (exp & 7);
			}
			return *this;
		}
	private:
		boost::uint16_t m_val;
	};

	enum
	{
		// the limits of the download queue size
		min_request_queue = 2,

		// the amount of free upload allowed before
		// the peer is choked
		free_upload_amount = 4 * 16 * 1024
	};

	// calculate the priority of a peer based on its address. One of the
	// endpoint should be our own. The priority is symmetric, so it doesn't
	// matter which is which
	TORRENT_EXTRA_EXPORT boost::uint32_t peer_priority(
		tcp::endpoint e1, tcp::endpoint e2);

	void request_a_block(torrent& t, peer_connection& c);

	class TORRENT_EXTRA_EXPORT policy
	{
	public:

		policy(torrent* t);

		struct peer;

#if TORRENT_USE_I2P
		policy::peer* add_i2p_peer(char const* destination, int source, char flags);
#endif

		// this is called once for every peer we get from
		// the tracker, pex, lsd or dht.
		policy::peer* add_peer(const tcp::endpoint& remote, const peer_id& pid
			, int source, char flags);

		// false means duplicate connection
		bool update_peer_port(int port, policy::peer* p, int src);

		// called when an incoming connection is accepted
		// false means the connection was refused or failed
		bool new_connection(peer_connection& c, int session_time);

		// the given connection was just closed
		void connection_closed(const peer_connection& c, int session_time);

		void ban_peer(policy::peer* p);
		void set_connection(policy::peer* p, peer_connection* c);
		void set_failcount(policy::peer* p, int f);

		// the peer has got at least one interesting piece
		void peer_is_interesting(peer_connection& c);

		void ip_filter_updated();

		void set_seed(policy::peer* p, bool s);

		// this clears all cached peer priorities. It's called when
		// our external IP changes
		void clear_peer_prio();

#if TORRENT_USE_ASSERTS
		bool has_connection(const peer_connection* p);
#endif
#if TORRENT_USE_INVARIANT_CHECKS
		void check_invariant() const;
#endif

		struct TORRENT_EXTRA_EXPORT peer
		{
			peer(boost::uint16_t port, bool connectable, int src);

			size_type total_download() const;
			size_type total_upload() const;
			
			boost::uint32_t rank(external_ip const& external, int external_port) const;

			libtorrent::address address() const;
			char const* dest() const;

			tcp::endpoint ip() const { return tcp::endpoint(address(), port); }

			// this is the accumulated amount of
			// uploaded and downloaded data to this
			// peer. It only accounts for what was
			// shared during the last connection to
			// this peer. i.e. These are only updated
			// when the connection is closed. For the
			// total amount of upload and download
			// we'll have to add thes figures with the
			// statistics from the peer_connection.
			// since these values don't need to be stored
			// with byte-precision, they specify the number
			// of kiB. i.e. shift left 10 bits to compare to
			// byte counters.
			boost::uint32_t prev_amount_upload;
			boost::uint32_t prev_amount_download;

			// if the peer is connected now, this
			// will refer to a valid peer_connection
			peer_connection* connection;

#ifndef TORRENT_DISABLE_GEO_IP
#ifdef TORRENT_DEBUG
			// only used in debug mode to assert that
			// the first entry in the AS pair keeps the same
			boost::uint16_t inet_as_num;
#endif
			// The AS this peer belongs to
			std::pair<const int, int>* inet_as;
#endif

			// as computed by hashing our IP with the remote
			// IP of this peer
			// calculated lazily
			mutable boost::uint32_t peer_rank;

			// the time when this peer was optimistically unchoked
			// the last time. in seconds since session was created
			// 16 bits is enough to last for 18.2 hours
			// when the session time reaches 18 hours, it jumps back by
			// 9 hours, and all peers' times are updated to be
			// relative to that new time offset
			boost::uint16_t last_optimistically_unchoked;

			// the time when the peer connected to us
			// or disconnected if it isn't connected right now
			// in number of seconds since session was created
			boost::uint16_t last_connected;

			// the port this peer is or was connected on
			boost::uint16_t port;

			// the upload and download rate limits set for this peer
			ufloat16 upload_rate_limit;
			ufloat16 download_rate_limit;

			// the number of times this peer has been
			// part of a piece that failed the hash check
			boost::uint8_t hashfails;

			// the number of failed connection attempts
			// this peer has
			unsigned failcount:5; // [0, 31]

			// incoming peers (that don't advertize their listen port)
			// will not be considered connectable. Peers that
			// we have a listen port for will be assumed to be.
			bool connectable:1;

			// true if this peer currently is unchoked
			// because of an optimistic unchoke.
			// when the optimistic unchoke is moved to
			// another peer, this peer will be choked
			// if this is true
			bool optimistically_unchoked:1;

			// this is true if the peer is a seed
			bool seed:1;

			// the number of times we have allowed a fast
			// reconnect for this peer.
			unsigned fast_reconnects:4;

			// for every valid piece we receive where this
			// peer was one of the participants, we increase
			// this value. For every invalid piece we receive
			// where this peer was a participant, we decrease
			// this value. If it sinks below a threshold, its
			// considered a bad peer and will be banned.
			signed trust_points:4; // [-7, 8]

			// a bitmap combining the peer_source flags
			// from peer_info.
			unsigned source:6;

#ifndef TORRENT_DISABLE_ENCRYPTION
			// Hints encryption support of peer. Only effective
			// for and when the outgoing encryption policy
			// allows both encrypted and non encrypted
			// connections (pe_settings::out_enc_policy
			// == enabled). The initial state of this flag
			// determines the initial connection attempt
			// type (true = encrypted, false = standard).
			// This will be toggled everytime either an
			// encrypted or non-encrypted handshake fails.
			bool pe_support:1;
#endif

#if TORRENT_USE_IPV6
			// this is true if the v6 union member in addr is
			// the one to use, false if it's the v4 one
			bool is_v6_addr:1;
#endif
#if TORRENT_USE_I2P
			// set if the i2p_destination is in use in the addr union
			bool is_i2p_addr:1;
#endif

			// if this is true, the peer has previously
			// participated in a piece that failed the piece
			// hash check. This will put the peer on parole
			// and only request entire pieces. If a piece pass
			// that was partially requested from this peer it
			// will leave parole mode and continue download
			// pieces as normal peers.
			bool on_parole:1;

			// is set to true if this peer has been banned
			bool banned:1;

#ifndef TORRENT_DISABLE_DHT
			// this is set to true when this peer as been
			// pinged by the DHT
			bool added_to_dht:1;
#endif
			// we think this peer supports uTP
			bool supports_utp:1;
			// we have been connected via uTP at least once
			bool confirmed_supports_utp:1;
			bool supports_holepunch:1;
			// this is set to one for web seeds. Web seeds
			// are not stored in the policy m_peers list,
			// and are excempt from connect candidate bookkeeping
			// so, any peer with the web_seed bit set, is
			// never considered a connect candidate
			bool web_seed:1;
#if TORRENT_USE_ASSERTS
			bool in_use:1;
#endif
		};

		struct TORRENT_EXTRA_EXPORT ipv4_peer : peer
		{
			ipv4_peer(tcp::endpoint const& ip, bool connectable, int src);

			address_v4 addr;
		};

#if TORRENT_USE_I2P
		struct TORRENT_EXTRA_EXPORT i2p_peer : peer
		{
			i2p_peer(char const* destination, bool connectable, int src);
			~i2p_peer();

			char* destination;
		};
#endif

#if TORRENT_USE_IPV6
		struct TORRENT_EXTRA_EXPORT ipv6_peer : peer
		{
			ipv6_peer(tcp::endpoint const& ip, bool connectable, int src);

			const address_v6::bytes_type addr;
		};
#endif

		int num_peers() const { return m_peers.size(); }

		struct peer_address_compare
		{
			bool operator()(
				peer const* lhs, libtorrent::address const& rhs) const
			{
				return lhs->address() < rhs;
			}

			bool operator()(
				libtorrent::address const& lhs, peer const* rhs) const
			{
				return lhs < rhs->address();
			}

#if TORRENT_USE_I2P
			bool operator()(
				peer const* lhs, char const* rhs) const
			{
				return strcmp(lhs->dest(), rhs) < 0;
			}

			bool operator()(
				char const* lhs, peer const* rhs) const
			{
				return strcmp(lhs, rhs->dest()) < 0;
			}
#endif

			bool operator()(
				peer const* lhs, peer const* rhs) const
			{
#if TORRENT_USE_I2P
				if (rhs->is_i2p_addr == lhs->is_i2p_addr)
					return strcmp(lhs->dest(), rhs->dest()) < 0;
#endif
				return lhs->address() < rhs->address();
			}
		};

		typedef std::deque<peer*> peers_t;

		typedef peers_t::iterator iterator;
		typedef peers_t::const_iterator const_iterator;
		iterator begin_peer() { return m_peers.begin(); }
		iterator end_peer() { return m_peers.end(); }
		const_iterator begin_peer() const { return m_peers.begin(); }
		const_iterator end_peer() const { return m_peers.end(); }

		std::pair<iterator, iterator> find_peers(address const& a)
		{
			return std::equal_range(
				m_peers.begin(), m_peers.end(), a, peer_address_compare());
		}

		std::pair<const_iterator, const_iterator> find_peers(address const& a) const
		{
			return std::equal_range(
				m_peers.begin(), m_peers.end(), a, peer_address_compare());
		}

		bool connect_one_peer(int session_time);

		bool has_peer(policy::peer const* p) const;

		int num_seeds() const { return m_num_seeds; }
		int num_connect_candidates() const { return m_num_connect_candidates; }
		void recalculate_connect_candidates();

		void erase_peer(policy::peer* p);
		void erase_peer(iterator i);

	private:

		void update_peer(policy::peer* p, int src, int flags
		, tcp::endpoint const& remote, char const* destination);
		bool insert_peer(policy::peer* p, iterator iter, int flags);

		bool compare_peer_erase(policy::peer const& lhs, policy::peer const& rhs) const;
		bool compare_peer(policy::peer const& lhs, policy::peer const& rhs
			, external_ip const& external, int source_port) const;

		iterator find_connect_candidate(int session_time);

		bool is_connect_candidate(peer const& p, bool finished) const;
		bool is_erase_candidate(peer const& p, bool finished) const;
		bool is_force_erase_candidate(peer const& pe) const;
		bool should_erase_immediately(peer const& p) const;

		enum flags_t { force_erase = 1 };
		void erase_peers(int flags = 0);

		peers_t m_peers;

		torrent* m_torrent;

		// this shouldbe NULL for the most part. It's set
		// to point to a valid torrent_peer object if that
		// object needs to be kept alive. If we ever feel
		// like removing a torrent_peer from m_peers, we
		// first check if the peer matches this one, and
		// if so, don't delete it.
		peer* m_locked_peer;

		// since the peer list can grow too large
		// to scan all of it, start at this iterator
		int m_round_robin;

		// The number of peers in our peer list
		// that are connect candidates. i.e. they're
		// not already connected and they have not
		// yet reached their max try count and they
		// have the connectable state (we have a listen
		// port for them).
		int m_num_connect_candidates;

		// the number of seeds in the peer list
		int m_num_seeds;

		// this was the state of the torrent the
		// last time we recalculated the number of
		// connect candidates. Since seeds (or upload
		// only) peers are not connect candidates
		// when we're finished, the set depends on
		// this state. Every time m_torrent->is_finished()
		// is different from this state, we need to
		// recalculate the connect candidates.
		bool m_finished:1;
	};

	inline policy::ipv4_peer::ipv4_peer(
		tcp::endpoint const& ep, bool c, int src
	)
		: peer(ep.port(), c, src)
		, addr(ep.address().to_v4())
	{
#if TORRENT_USE_IPV6
		is_v6_addr = false;
#endif
#if TORRENT_USE_I2P
		is_i2p_addr = false;
#endif
	}

#if TORRENT_USE_I2P
	inline policy::i2p_peer::i2p_peer(char const* dest, bool connectable, int src)
		: peer(0, connectable, src), destination(allocate_string_copy(dest))
	{
#if TORRENT_USE_IPV6
		is_v6_addr = false;
#endif
		is_i2p_addr = true;
	}

	inline policy::i2p_peer::~i2p_peer()
	{ free(destination); }
#endif // TORRENT_USE_I2P

#if TORRENT_USE_IPV6
	inline policy::ipv6_peer::ipv6_peer(
		tcp::endpoint const& ep, bool c, int src
	)
		: peer(ep.port(), c, src)
		, addr(ep.address().to_v6().to_bytes())
	{
		is_v6_addr = true;
#if TORRENT_USE_I2P
		is_i2p_addr = false;
#endif
	}

#endif // TORRENT_USE_IPV6

#if TORRENT_USE_I2P
	inline char const* policy::peer::dest() const
	{
		if (is_i2p_addr)
			return static_cast<policy::i2p_peer const*>(this)->destination;
		return "";
	}
#endif
	
	inline libtorrent::address policy::peer::address() const
	{
#if TORRENT_USE_IPV6
		if (is_v6_addr)
			return libtorrent::address_v6(
				static_cast<policy::ipv6_peer const*>(this)->addr);
		else
#endif
#if TORRENT_USE_I2P
		if (is_i2p_addr) return libtorrent::address();
		else
#endif
		return static_cast<policy::ipv4_peer const*>(this)->addr;
	}

}

#endif // TORRENT_POLICY_HPP_INCLUDED