496 lines
14 KiB
C++
496 lines
14 KiB
C++
/*
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Copyright (c) 2003-2018, Arvid Norberg
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Copyright (c) 2007-2018, Arvid Norberg, Un Shyam
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All rights reserved.
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Redistribution and use in source and binary forms, with or without
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modification, are permitted provided that the following conditions
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are met:
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* Redistributions of source code must retain the above copyright
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notice, this list of conditions and the following disclaimer.
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* Redistributions in binary form must reproduce the above copyright
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notice, this list of conditions and the following disclaimer in
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the documentation and/or other materials provided with the distribution.
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* Neither the name of the author nor the names of its
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contributors may be used to endorse or promote products derived
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from this software without specific prior written permission.
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
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LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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POSSIBILITY OF SUCH DAMAGE.
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*/
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#ifndef TORRENT_BT_PEER_CONNECTION_HPP_INCLUDED
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#define TORRENT_BT_PEER_CONNECTION_HPP_INCLUDED
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#include <ctime>
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#include <algorithm>
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#include <vector>
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#include <string>
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#include <array>
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#include <cstdint>
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#include "libtorrent/debug.hpp"
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#include "libtorrent/buffer.hpp"
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#include "libtorrent/peer_connection.hpp"
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#include "libtorrent/socket.hpp"
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#include "libtorrent/peer_id.hpp"
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#include "libtorrent/stat.hpp"
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#include "libtorrent/alert.hpp"
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#include "libtorrent/torrent.hpp"
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#include "libtorrent/peer_request.hpp"
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#include "libtorrent/piece_block_progress.hpp"
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#include "libtorrent/config.hpp"
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#include "libtorrent/pe_crypto.hpp"
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#include "libtorrent/io.hpp"
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namespace libtorrent {
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#ifndef TORRENT_DISABLE_EXTENSIONS
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struct TORRENT_EXTRA_EXPORT ut_pex_peer_store
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{
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// stores all peers this peer is connected to. These lists
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// are updated with each pex message and are limited in size
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// to protect against malicious clients. These lists are also
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// used for looking up which peer a peer that supports holepunch
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// came from.
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// these are vectors to save memory and keep the items close
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// together for performance. Inserting and removing is relatively
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// cheap since the lists' size is limited
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using peers4_t = std::vector<std::pair<address_v4::bytes_type, std::uint16_t>>;
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peers4_t m_peers;
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using peers6_t = std::vector<std::pair<address_v6::bytes_type, std::uint16_t>>;
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peers6_t m_peers6;
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bool was_introduced_by(tcp::endpoint const& ep);
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virtual ~ut_pex_peer_store() {}
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};
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#endif
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class TORRENT_EXTRA_EXPORT bt_peer_connection
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: public peer_connection
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{
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friend class invariant_access;
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public:
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// this is the constructor where the we are the active part.
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// The peer_connection should handshake and verify that the
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// other end has the correct id
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explicit bt_peer_connection(peer_connection_args const& pack);
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void start() override;
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enum
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{
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// pex_msg = 1,
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// metadata_msg = 2,
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upload_only_msg = 3,
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holepunch_msg = 4,
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// recommend_msg = 5,
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// comment_msg = 6,
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dont_have_msg = 7,
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share_mode_msg = 8
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};
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~bt_peer_connection() override;
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peer_id our_pid() const override { return m_our_peer_id; }
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#if !defined TORRENT_DISABLE_ENCRYPTION
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bool supports_encryption() const
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{ return m_encrypted; }
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bool rc4_encrypted() const
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{ return m_rc4_encrypted; }
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void switch_send_crypto(std::shared_ptr<crypto_plugin> crypto);
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void switch_recv_crypto(std::shared_ptr<crypto_plugin> crypto);
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#endif
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connection_type type() const override
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{ return connection_type::bittorrent; }
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enum message_type
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{
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// standard messages
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msg_choke = 0,
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msg_unchoke,
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msg_interested,
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msg_not_interested,
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msg_have,
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msg_bitfield,
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msg_request,
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msg_piece,
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msg_cancel,
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// DHT extension
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msg_dht_port,
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// FAST extension
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msg_suggest_piece = 0xd,
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msg_have_all,
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msg_have_none,
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msg_reject_request,
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msg_allowed_fast,
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// extension protocol message
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msg_extended = 20,
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num_supported_messages
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};
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enum class hp_message : std::uint8_t
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{
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// msg_types
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rendezvous = 0,
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connect = 1,
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failed = 2
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};
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enum class hp_error
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{
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// error codes
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no_error = 0,
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no_such_peer = 1,
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not_connected = 2,
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no_support = 3,
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no_self = 4
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};
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// called from the main loop when this connection has any
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// work to do.
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void on_sent(error_code const& error
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, std::size_t bytes_transferred) override;
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void on_receive(error_code const& error
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, std::size_t bytes_transferred) override;
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void on_receive_impl(std::size_t bytes_transferred);
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#if !defined TORRENT_DISABLE_ENCRYPTION
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// next_barrier, buffers-to-prepend
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std::tuple<int, span<span<char const>>>
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hit_send_barrier(span<span<char>> iovec) override;
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#endif
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void get_specific_peer_info(peer_info& p) const override;
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bool in_handshake() const override;
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bool packet_finished() const { return m_recv_buffer.packet_finished(); }
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bool supports_holepunch() const { return m_holepunch_id != 0; }
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#ifndef TORRENT_DISABLE_EXTENSIONS
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void set_ut_pex(std::weak_ptr<ut_pex_peer_store> ut_pex)
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{ m_ut_pex = std::move(ut_pex); }
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bool was_introduced_by(tcp::endpoint const& ep) const
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{ auto p = m_ut_pex.lock(); return p && p->was_introduced_by(ep); }
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#endif
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bool support_extensions() const { return m_supports_extensions; }
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// the message handlers are called
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// each time a recv() returns some new
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// data, the last time it will be called
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// is when the entire packet has been
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// received, then it will no longer
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// be called. i.e. most handlers need
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// to check how much of the packet they
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// have received before any processing
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void on_choke(int received);
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void on_unchoke(int received);
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void on_interested(int received);
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void on_not_interested(int received);
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void on_have(int received);
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void on_bitfield(int received);
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void on_request(int received);
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void on_piece(int received);
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void on_cancel(int received);
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// DHT extension
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void on_dht_port(int received);
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// FAST extension
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void on_suggest_piece(int received);
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void on_have_all(int received);
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void on_have_none(int received);
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void on_reject_request(int received);
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void on_allowed_fast(int received);
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void on_holepunch();
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void on_extended(int received);
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void on_extended_handshake();
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// the following functions appends messages
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// to the send buffer
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void write_choke() override;
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void write_unchoke() override;
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void write_interested() override;
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void write_not_interested() override;
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void write_request(peer_request const& r) override;
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void write_cancel(peer_request const& r) override;
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void write_bitfield() override;
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void write_have(piece_index_t index) override;
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void write_dont_have(piece_index_t index) override;
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void write_piece(peer_request const& r, disk_buffer_holder buffer) override;
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void write_keepalive() override;
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void write_handshake();
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void write_upload_only(bool enabled) override;
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void write_extensions();
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void write_share_mode();
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void write_holepunch_msg(hp_message type, tcp::endpoint const& ep
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, hp_error error = hp_error::no_error);
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// DHT extension
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void write_dht_port(int listen_port);
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// FAST extension
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void write_have_all();
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void write_have_none();
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void write_reject_request(peer_request const&) override;
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void write_allow_fast(piece_index_t piece) override;
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void write_suggest(piece_index_t piece) override;
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void on_connected() override;
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void on_metadata() override;
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#if TORRENT_USE_INVARIANT_CHECKS
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void check_invariant() const;
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time_point m_last_choke;
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#endif
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private:
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template <typename... Args>
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void send_message(message_type const type
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, counters::stats_counter_t const counter
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, Args... args)
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{
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TORRENT_ASSERT(m_sent_handshake);
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TORRENT_ASSERT(m_sent_bitfield);
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char msg[5 + sizeof...(Args) * 4]
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= { 0,0,0,1 + sizeof...(Args) * 4, static_cast<char>(type) };
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char* ptr = msg + 5;
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TORRENT_UNUSED(ptr);
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int tmp[] = {0, (detail::write_int32(args, ptr), 0)...};
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TORRENT_UNUSED(tmp);
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send_buffer(msg);
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stats_counters().inc_stats_counter(counter);
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}
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void write_dht_port();
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bool dispatch_message(int received);
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// returns the block currently being
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// downloaded. And the progress of that
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// block. If the peer isn't downloading
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// a piece for the moment, the boost::optional
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// will be invalid.
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piece_block_progress downloading_piece_progress() const override;
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#if !defined TORRENT_DISABLE_ENCRYPTION
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// if (is_local()), we are 'a' otherwise 'b'
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//
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// 1. a -> b dhkey, pad
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// 2. b -> a dhkey, pad
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// 3. a -> b sync, payload
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// 4. b -> a sync, payload
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// 5. a -> b payload
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void write_pe1_2_dhkey();
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void write_pe3_sync();
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void write_pe4_sync(int crypto_select);
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void write_pe_vc_cryptofield(span<char> write_buf
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, int crypto_field, int pad_size);
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// helper to cut down on boilerplate
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void rc4_decrypt(span<char> buf);
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#endif
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public:
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// these functions encrypt the send buffer if m_rc4_encrypted
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// is true, otherwise it passes the call to the
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// peer_connection functions of the same names
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template <typename Holder>
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void append_const_send_buffer(Holder holder, int size)
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{
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#if !defined TORRENT_DISABLE_ENCRYPTION
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if (!m_enc_handler.is_send_plaintext())
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{
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// if we're encrypting this buffer, we need to make a copy
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// since we'll mutate it
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buffer buf(size, {holder.data(), size});
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append_send_buffer(std::move(buf), size);
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}
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else
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#endif
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{
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append_send_buffer(std::move(holder), size);
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}
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}
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private:
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enum class state_t : std::uint8_t
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{
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#if !defined TORRENT_DISABLE_ENCRYPTION
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read_pe_dhkey,
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read_pe_syncvc,
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read_pe_synchash,
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read_pe_skey_vc,
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read_pe_cryptofield,
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read_pe_pad,
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read_pe_ia,
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init_bt_handshake,
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#endif
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read_protocol_identifier,
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read_info_hash,
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read_peer_id,
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// handshake complete
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read_packet_size,
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read_packet
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};
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// state of on_receive. one of the enums in state_t
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state_t m_state = state_t::read_protocol_identifier;
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// this is set to true if the handshake from
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// the peer indicated that it supports the
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// extension protocol
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bool m_supports_extensions:1;
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bool m_supports_dht_port:1;
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bool m_supports_fast:1;
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// this is set to true when we send the bitfield message.
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// for magnet links we can't do that right away,
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// since we don't know how many pieces there are in
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// the torrent.
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bool m_sent_bitfield:1;
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// true if we're done sending the bittorrent handshake,
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// and can send bittorrent messages
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bool m_sent_handshake:1;
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// set to true once we send the allowed-fast messages. This is
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// only done once per connection
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bool m_sent_allowed_fast:1;
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#if !defined TORRENT_DISABLE_ENCRYPTION
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// this is set to true after the encryption method has been
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// successfully negotiated (either plaintext or rc4), to signal
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// automatic encryption/decryption.
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bool m_encrypted:1;
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// true if rc4, false if plaintext
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bool m_rc4_encrypted:1;
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// this is a legitimate use of a shadow field
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#ifdef __clang__
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#pragma clang diagnostic push
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// macOS clang doesn't have -Wshadow-field
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#pragma clang diagnostic ignored "-Wunknown-pragmas"
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// Xcode 9 needs this
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#pragma clang diagnostic ignored "-Wunknown-warning-option"
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#pragma clang diagnostic ignored "-Wshadow-field"
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#endif
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crypto_receive_buffer m_recv_buffer;
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#ifdef __clang__
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#pragma clang diagnostic pop
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#endif
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#endif
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std::string m_client_version;
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// the peer ID we advertise for ourself
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peer_id const m_our_peer_id;
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// this is a queue of ranges that describes
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// where in the send buffer actual payload
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// data is located. This is currently
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// only used to be able to gather statistics
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// separately on payload and protocol data.
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struct range
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{
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range(int s, int l)
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: start(s)
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, length(l)
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{
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TORRENT_ASSERT(s >= 0);
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TORRENT_ASSERT(l > 0);
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}
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int start;
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int length;
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};
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std::vector<range> m_payloads;
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#if !defined TORRENT_DISABLE_ENCRYPTION
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// initialized during write_pe1_2_dhkey, and destroyed on
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// creation of m_enc_handler. Cannot reinitialize once
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// initialized.
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std::unique_ptr<dh_key_exchange> m_dh_key_exchange;
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// used during an encrypted handshake then moved
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// into m_enc_handler if rc4 encryption is negotiated
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// otherwise it is destroyed when the handshake completes
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std::shared_ptr<rc4_handler> m_rc4;
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// if encryption is negotiated, this is used for
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// encryption/decryption during the entire session.
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encryption_handler m_enc_handler;
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// (outgoing only) synchronize verification constant with
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// remote peer, this will hold rc4_decrypt(vc). Destroyed
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// after the sync step.
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std::unique_ptr<char[]> m_sync_vc;
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// (incoming only) synchronize hash with remote peer, holds
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// the sync hash (hash("req1",secret)). Destroyed after the
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// sync step.
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std::unique_ptr<sha1_hash> m_sync_hash;
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// used to disconnect peer if sync points are not found within
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// the maximum number of bytes
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int m_sync_bytes_read = 0;
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#endif
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// the message ID for upload only message
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// 0 if not supported
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std::uint8_t m_upload_only_id = 0;
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// the message ID for holepunch messages
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std::uint8_t m_holepunch_id = 0;
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// the message ID for don't-have message
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std::uint8_t m_dont_have_id = 0;
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// the message ID for share mode message
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// 0 if not supported
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std::uint8_t m_share_mode_id = 0;
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#ifndef TORRENT_DISABLE_EXTENSIONS
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std::weak_ptr<ut_pex_peer_store> m_ut_pex;
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#endif
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std::array<char, 8> m_reserved_bits;
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};
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}
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#endif // TORRENT_BT_PEER_CONNECTION_HPP_INCLUDED
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