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bt_peer_connection.cpp
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bt_peer_connection.cpp
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/*
Copyright (c) 2003-2016, Arvid Norberg
Copyright (c) 2007-2016, Arvid Norberg, Un Shyam
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/config.hpp"
#include <memory> // unique_ptr
#include <vector>
#include <functional>
#include "libtorrent/aux_/disable_warnings_push.hpp"
#include <boost/multiprecision/cpp_int.hpp>
#include <boost/multiprecision/integer.hpp>
// for backwards compatibility with boost < 1.60 which was before export_bits
// and import_bits were introduced
#if BOOST_VERSION < 106000
#include "libtorrent/aux_/cppint_import_export.hpp"
#endif
#include "libtorrent/aux_/disable_warnings_pop.hpp"
#ifndef TORRENT_DISABLE_LOGGING
#include "libtorrent/hex.hpp" // to_hex
#endif
#include "libtorrent/bt_peer_connection.hpp"
#include "libtorrent/session.hpp"
#include "libtorrent/identify_client.hpp"
#include "libtorrent/entry.hpp"
#include "libtorrent/bencode.hpp"
#include "libtorrent/alert_types.hpp"
#include "libtorrent/invariant_check.hpp"
#include "libtorrent/io.hpp"
#include "libtorrent/aux_/io.hpp"
#include "libtorrent/socket_io.hpp"
#include "libtorrent/extensions.hpp"
#include "libtorrent/aux_/session_interface.hpp"
#include "libtorrent/alert_types.hpp"
#include "libtorrent/broadcast_socket.hpp"
#include "libtorrent/peer_info.hpp"
#include "libtorrent/random.hpp"
#include "libtorrent/alloca.hpp"
#include "libtorrent/socket_type.hpp"
#include "libtorrent/performance_counters.hpp" // for counters
#if !defined(TORRENT_DISABLE_ENCRYPTION) && !defined(TORRENT_DISABLE_EXTENSIONS)
#include "libtorrent/pe_crypto.hpp"
#include "libtorrent/hasher.hpp"
#endif
using boost::shared_ptr;
namespace libtorrent
{
namespace mp = boost::multiprecision;
#if !defined(TORRENT_DISABLE_ENCRYPTION) && !defined(TORRENT_DISABLE_EXTENSIONS)
namespace {
// stream key (info hash of attached torrent)
// secret is the DH shared secret
// initializes m_enc_handler
boost::shared_ptr<rc4_handler> init_pe_rc4_handler(key_t const& secret
, sha1_hash const& stream_key, bool const outgoing)
{
hasher h;
static const char keyA[] = {'k', 'e', 'y', 'A'};
static const char keyB[] = {'k', 'e', 'y', 'B'};
// encryption rc4 longkeys
// outgoing connection : hash ('keyA',S,SKEY)
// incoming connection : hash ('keyB',S,SKEY)
std::array<char, 96> secret_buf;
mp::export_bits(secret, reinterpret_cast<std::uint8_t*>(secret_buf.data()), 8);
if (outgoing) h.update(keyA); else h.update(keyB);
h.update(secret_buf);
h.update(stream_key);
sha1_hash const local_key = h.final();
h.reset();
// decryption rc4 longkeys
// outgoing connection : hash ('keyB',S,SKEY)
// incoming connection : hash ('keyA',S,SKEY)
if (outgoing) h.update(keyB); else h.update(keyA);
h.update(secret_buf);
h.update(stream_key);
sha1_hash const remote_key = h.final();
boost::shared_ptr<rc4_handler> ret = boost::make_shared<rc4_handler>();
ret->set_incoming_key(&remote_key[0], 20);
ret->set_outgoing_key(&local_key[0], 20);
return ret;
}
} // anonymous namespace
#endif
bt_peer_connection::bt_peer_connection(peer_connection_args const& pack
, peer_id const& pid)
: peer_connection(pack)
, m_state(read_protocol_identifier)
, m_supports_extensions(false)
, m_supports_dht_port(false)
, m_supports_fast(false)
, m_sent_bitfield(false)
, m_sent_handshake(false)
, m_sent_allowed_fast(false)
#if !defined(TORRENT_DISABLE_ENCRYPTION) && !defined(TORRENT_DISABLE_EXTENSIONS)
, m_encrypted(false)
, m_rc4_encrypted(false)
, m_recv_buffer(peer_connection::m_recv_buffer)
#endif
, m_our_peer_id(pid)
#if !defined(TORRENT_DISABLE_ENCRYPTION) && !defined(TORRENT_DISABLE_EXTENSIONS)
, m_sync_bytes_read(0)
#endif
#ifndef TORRENT_DISABLE_EXTENSIONS
, m_upload_only_id(0)
, m_holepunch_id(0)
#endif
#ifndef TORRENT_DISABLE_EXTENSIONS
, m_dont_have_id(0)
, m_share_mode_id(0)
#endif
#if TORRENT_USE_ASSERTS
, m_in_constructor(true)
#endif
{
#ifndef TORRENT_DISABLE_LOGGING
peer_log(peer_log_alert::info, "CONSTRUCT", "bt_peer_connection");
#endif
#if TORRENT_USE_ASSERTS
m_in_constructor = false;
#endif
#ifndef TORRENT_DISABLE_EXTENSIONS
memset(m_reserved_bits, 0, sizeof(m_reserved_bits));
#endif
}
void bt_peer_connection::start()
{
peer_connection::start();
// start in the state where we are trying to read the
// handshake from the other side
m_recv_buffer.reset(20);
setup_receive();
}
bt_peer_connection::~bt_peer_connection() = default;
#if !defined(TORRENT_DISABLE_ENCRYPTION) && !defined(TORRENT_DISABLE_EXTENSIONS)
void bt_peer_connection::switch_send_crypto(boost::shared_ptr<crypto_plugin> crypto)
{
if (m_enc_handler.switch_send_crypto(crypto, send_buffer_size() - get_send_barrier()))
set_send_barrier(send_buffer_size());
}
void bt_peer_connection::switch_recv_crypto(boost::shared_ptr<crypto_plugin> crypto)
{
m_enc_handler.switch_recv_crypto(crypto, m_recv_buffer);
}
#endif
void bt_peer_connection::on_connected()
{
if (is_disconnecting()) return;
boost::shared_ptr<torrent> t = associated_torrent().lock();
TORRENT_ASSERT(t);
if (t->graceful_pause())
{
#ifndef TORRENT_DISABLE_LOGGING
peer_log(peer_log_alert::info, "ON_CONNECTED", "graceful-paused");
#endif
disconnect(error_code(errors::torrent_paused), op_bittorrent);
return;
}
// make sure are much as possible of the response ends up in the same
// packet, or at least back-to-back packets
cork c_(*this);
#if !defined(TORRENT_DISABLE_ENCRYPTION) && !defined(TORRENT_DISABLE_EXTENSIONS)
std::uint8_t out_policy = m_settings.get_int(settings_pack::out_enc_policy);
#ifdef TORRENT_USE_OPENSSL
// never try an encrypted connection when already using SSL
if (is_ssl(*get_socket()))
out_policy = settings_pack::pe_disabled;
#endif
#ifndef TORRENT_DISABLE_LOGGING
char const* policy_name[] = {"forced", "enabled", "disabled"};
TORRENT_ASSERT(out_policy < sizeof(policy_name)/sizeof(policy_name[0]));
peer_log(peer_log_alert::info, "ENCRYPTION"
, "outgoing encryption policy: %s", policy_name[out_policy]);
#endif
if (out_policy == settings_pack::pe_forced)
{
write_pe1_2_dhkey();
if (is_disconnecting()) return;
m_state = read_pe_dhkey;
m_recv_buffer.reset(dh_key_len);
setup_receive();
}
else if (out_policy == settings_pack::pe_enabled)
{
TORRENT_ASSERT(peer_info_struct());
torrent_peer* pi = peer_info_struct();
if (pi->pe_support == true)
{
// toggle encryption support flag, toggled back to
// true if encrypted portion of the handshake
// completes correctly
pi->pe_support = false;
// if this fails, we need to reconnect
// fast.
fast_reconnect(true);
write_pe1_2_dhkey();
if (is_disconnecting()) return;
m_state = read_pe_dhkey;
m_recv_buffer.reset(dh_key_len);
setup_receive();
}
else // pi->pe_support == false
{
// toggled back to false if standard handshake
// completes correctly (without encryption)
pi->pe_support = true;
write_handshake();
m_recv_buffer.reset(20);
setup_receive();
}
}
else if (out_policy == settings_pack::pe_disabled)
#endif
{
write_handshake();
// start in the state where we are trying to read the
// handshake from the other side
m_recv_buffer.reset(20);
setup_receive();
}
}
void bt_peer_connection::on_metadata()
{
#ifndef TORRENT_DISABLE_LOGGING
peer_log(peer_log_alert::info, "ON_METADATA");
#endif
disconnect_if_redundant();
if (m_disconnecting) return;
if (!m_sent_handshake) return;
// we're still waiting to fully handshake with this peer. At the end of
// the handshake we'll send the bitfield and dht port anyway. It's too
// early to do now
if (m_state < read_packet_size) return;
// connections that are still in the handshake
// will send their bitfield when the handshake
// is done
#ifndef TORRENT_DISABLE_EXTENSIONS
write_upload_only();
#endif
if (m_sent_bitfield) return;
boost::shared_ptr<torrent> t = associated_torrent().lock();
TORRENT_ASSERT(t);
write_bitfield();
TORRENT_ASSERT(m_sent_bitfield);
#ifndef TORRENT_DISABLE_DHT
if (m_supports_dht_port && m_ses.has_dht())
write_dht_port(m_ses.external_udp_port());
#endif
}
void bt_peer_connection::write_dht_port(int listen_port)
{
INVARIANT_CHECK;
TORRENT_ASSERT(m_sent_handshake);
TORRENT_ASSERT(m_sent_bitfield);
#ifndef TORRENT_DISABLE_LOGGING
peer_log(peer_log_alert::outgoing_message, "DHT_PORT", "%d", listen_port);
#endif
char msg[] = {0,0,0,3, msg_dht_port, 0, 0};
char* ptr = msg + 5;
detail::write_uint16(listen_port, ptr);
send_buffer(msg, sizeof(msg));
stats_counters().inc_stats_counter(counters::num_outgoing_dht_port);
}
void bt_peer_connection::write_have_all()
{
INVARIANT_CHECK;
TORRENT_ASSERT(m_sent_handshake);
m_sent_bitfield = true;
#ifndef TORRENT_DISABLE_LOGGING
peer_log(peer_log_alert::outgoing_message, "HAVE_ALL");
#endif
char msg[] = {0,0,0,1, msg_have_all};
send_buffer(msg, sizeof(msg));
stats_counters().inc_stats_counter(counters::num_outgoing_have_all);
}
void bt_peer_connection::write_have_none()
{
INVARIANT_CHECK;
TORRENT_ASSERT(m_sent_handshake);
m_sent_bitfield = true;
#ifndef TORRENT_DISABLE_LOGGING
peer_log(peer_log_alert::outgoing_message, "HAVE_NONE");
#endif
char msg[] = {0,0,0,1, msg_have_none};
send_buffer(msg, sizeof(msg));
stats_counters().inc_stats_counter(counters::num_outgoing_have_none);
}
void bt_peer_connection::write_reject_request(peer_request const& r)
{
INVARIANT_CHECK;
stats_counters().inc_stats_counter(counters::piece_rejects);
if (!m_supports_fast) return;
#ifndef TORRENT_DISABLE_LOGGING
peer_log(peer_log_alert::outgoing_message, "REJECT_PIECE"
, "piece: %d | s: %d | l: %d", r.piece, r.start, r.length);
#endif
TORRENT_ASSERT(m_sent_handshake);
TORRENT_ASSERT(m_sent_bitfield);
TORRENT_ASSERT(associated_torrent().lock()->valid_metadata());
char msg[] = {0,0,0,13, msg_reject_request,0,0,0,0, 0,0,0,0, 0,0,0,0};
char* ptr = msg + 5;
detail::write_int32(r.piece, ptr); // index
detail::write_int32(r.start, ptr); // begin
detail::write_int32(r.length, ptr); // length
send_buffer(msg, sizeof(msg));
stats_counters().inc_stats_counter(counters::num_outgoing_reject);
}
void bt_peer_connection::write_allow_fast(int piece)
{
INVARIANT_CHECK;
if (!m_supports_fast) return;
#ifndef TORRENT_DISABLE_LOGGING
peer_log(peer_log_alert::outgoing_message, "ALLOWED_FAST", "%d", piece);
#endif
TORRENT_ASSERT(m_sent_handshake);
TORRENT_ASSERT(m_sent_bitfield);
TORRENT_ASSERT(associated_torrent().lock()->valid_metadata());
char msg[] = {0,0,0,5, msg_allowed_fast, 0, 0, 0, 0};
char* ptr = msg + 5;
detail::write_int32(piece, ptr);
send_buffer(msg, sizeof(msg));
stats_counters().inc_stats_counter(counters::num_outgoing_allowed_fast);
}
void bt_peer_connection::write_suggest(int piece)
{
INVARIANT_CHECK;
if (!m_supports_fast) return;
TORRENT_ASSERT(m_sent_handshake);
TORRENT_ASSERT(m_sent_bitfield);
boost::shared_ptr<torrent> t = associated_torrent().lock();
TORRENT_ASSERT(t);
TORRENT_ASSERT(t->valid_metadata());
#ifndef TORRENT_DISABLE_LOGGING
peer_log(peer_log_alert::outgoing_message, "SUGGEST"
, "piece: %d num_peers: %d", piece
, t->has_picker() ? t->picker().get_availability(piece) : -1);
#endif
char msg[] = {0,0,0,5, msg_suggest_piece, 0, 0, 0, 0};
char* ptr = msg + 5;
detail::write_int32(piece, ptr);
send_buffer(msg, sizeof(msg));
stats_counters().inc_stats_counter(counters::num_outgoing_suggest);
}
void bt_peer_connection::get_specific_peer_info(peer_info& p) const
{
TORRENT_ASSERT(!associated_torrent().expired());
if (is_interesting()) p.flags |= peer_info::interesting;
if (is_choked()) p.flags |= peer_info::choked;
if (is_peer_interested()) p.flags |= peer_info::remote_interested;
if (has_peer_choked()) p.flags |= peer_info::remote_choked;
if (support_extensions()) p.flags |= peer_info::supports_extensions;
if (is_outgoing()) p.flags |= peer_info::local_connection;
#if TORRENT_USE_I2P
if (is_i2p(*get_socket())) p.flags |= peer_info::i2p_socket;
#endif
if (is_utp(*get_socket())) p.flags |= peer_info::utp_socket;
if (is_ssl(*get_socket())) p.flags |= peer_info::ssl_socket;
#if !defined(TORRENT_DISABLE_ENCRYPTION) && !defined(TORRENT_DISABLE_EXTENSIONS)
if (m_encrypted)
{
p.flags |= m_rc4_encrypted
? peer_info::rc4_encrypted
: peer_info::plaintext_encrypted;
}
#endif
if (!is_connecting() && in_handshake())
p.flags |= peer_info::handshake;
if (is_connecting()) p.flags |= peer_info::connecting;
p.client = m_client_version;
p.connection_type = peer_info::standard_bittorrent;
}
bool bt_peer_connection::in_handshake() const
{
return !m_sent_handshake;
}
#if !defined(TORRENT_DISABLE_ENCRYPTION) && !defined(TORRENT_DISABLE_EXTENSIONS)
namespace {
char random_byte()
{ return random() & 0xff; }
}
void bt_peer_connection::write_pe1_2_dhkey()
{
INVARIANT_CHECK;
TORRENT_ASSERT(!m_encrypted);
TORRENT_ASSERT(!m_rc4_encrypted);
TORRENT_ASSERT(!m_dh_key_exchange.get());
TORRENT_ASSERT(!m_sent_handshake);
#ifndef TORRENT_DISABLE_LOGGING
if (is_outgoing())
peer_log(peer_log_alert::info, "ENCRYPTION", "initiating encrypted handshake");
#endif
m_dh_key_exchange.reset(new (std::nothrow) dh_key_exchange);
if (!m_dh_key_exchange || !m_dh_key_exchange->good())
{
disconnect(errors::no_memory, op_encryption);
return;
}
int const pad_size = random() % 512;
#ifndef TORRENT_DISABLE_LOGGING
peer_log(peer_log_alert::info, "ENCRYPTION", "pad size: %d", pad_size);
#endif
char msg[dh_key_len + 512];
char* ptr = msg;
int const buf_size = dh_key_len + pad_size;
mp::export_bits(m_dh_key_exchange->get_local_key()
, reinterpret_cast<std::uint8_t*>(ptr), 8);
ptr += dh_key_len;
std::generate(ptr, ptr + pad_size, random_byte);
send_buffer(msg, buf_size);
#ifndef TORRENT_DISABLE_LOGGING
peer_log(peer_log_alert::info, "ENCRYPTION", "sent DH key");
#endif
}
void bt_peer_connection::write_pe3_sync()
{
INVARIANT_CHECK;
TORRENT_ASSERT(!m_encrypted);
TORRENT_ASSERT(!m_rc4_encrypted);
TORRENT_ASSERT(is_outgoing());
TORRENT_ASSERT(!m_sent_handshake);
boost::shared_ptr<torrent> t = associated_torrent().lock();
TORRENT_ASSERT(t);
hasher h;
sha1_hash const& info_hash = t->torrent_file().info_hash();
key_t const secret_key = m_dh_key_exchange->get_secret();
std::array<char, 96> secret;
mp::export_bits(secret_key, reinterpret_cast<std::uint8_t*>(secret.data()), 8);
int pad_size = random() % 512;
// synchash,skeyhash,vc,crypto_provide,len(pad),pad,len(ia)
char msg[20 + 20 + 8 + 4 + 2 + 512 + 2];
char* ptr = msg;
static char const req1[4] = {'r', 'e', 'q', '1'};
// sync hash (hash('req1',S))
h.reset();
h.update(req1);
h.update(secret);
sha1_hash const sync_hash = h.final();
std::memcpy(ptr, sync_hash.data(), 20);
ptr += 20;
static char const req2[4] = {'r', 'e', 'q', '2'};
// stream key obfuscated hash [ hash('req2',SKEY) xor hash('req3',S) ]
h.reset();
h.update(req2);
h.update(info_hash);
sha1_hash const streamkey_hash = h.final();
static char const req3[4] = {'r', 'e', 'q', '3'};
h.reset();
h.update(req3);
h.update(secret);
sha1_hash const obfsc_hash = h.final() ^ streamkey_hash;
std::memcpy(ptr, obfsc_hash.data(), 20);
ptr += 20;
// Discard DH key exchange data, setup RC4 keys
m_rc4 = init_pe_rc4_handler(secret_key, info_hash, is_outgoing());
#ifndef TORRENT_DISABLE_LOGGING
peer_log(peer_log_alert::info, "ENCRYPTION", "computed RC4 keys");
#endif
m_dh_key_exchange.reset(); // secret should be invalid at this point
// write the verification constant and crypto field
int encrypt_size = sizeof(msg) - 512 + pad_size - 40;
std::uint8_t crypto_provide = m_settings.get_int(settings_pack::allowed_enc_level);
// this is an invalid setting, but let's just make the best of the situation
if ((crypto_provide & settings_pack::pe_both) == 0)
crypto_provide = settings_pack::pe_both;
#ifndef TORRENT_DISABLE_LOGGING
char const* level[] = {"plaintext", "rc4", "plaintext rc4"};
peer_log(peer_log_alert::info, "ENCRYPTION"
, "%s", level[crypto_provide-1]);
#endif
write_pe_vc_cryptofield(ptr, encrypt_size, crypto_provide, pad_size);
span<char> vec(ptr, encrypt_size);
m_rc4->encrypt(vec);
send_buffer(msg, sizeof(msg) - 512 + pad_size);
}
void bt_peer_connection::write_pe4_sync(int crypto_select)
{
INVARIANT_CHECK;
TORRENT_ASSERT(!is_outgoing());
TORRENT_ASSERT(!m_encrypted);
TORRENT_ASSERT(!m_rc4_encrypted);
TORRENT_ASSERT(crypto_select == 0x02 || crypto_select == 0x01);
TORRENT_ASSERT(!m_sent_handshake);
int const pad_size = random() % 512;
int const buf_size = 8 + 4 + 2 + pad_size;
char msg[512 + 8 + 4 + 2];
write_pe_vc_cryptofield(msg, sizeof(msg), crypto_select, pad_size);
span<char> vec(msg, buf_size);
m_rc4->encrypt(vec);
send_buffer(msg, buf_size);
// encryption method has been negotiated
if (crypto_select == 0x02)
m_rc4_encrypted = true;
else // 0x01
m_rc4_encrypted = false;
#ifndef TORRENT_DISABLE_LOGGING
peer_log(peer_log_alert::info, "ENCRYPTION", " crypto select: %s"
, (crypto_select == 0x01) ? "plaintext" : "rc4");
#endif
}
void bt_peer_connection::write_pe_vc_cryptofield(char* write_buf
, int const len
, int const crypto_field
, int const pad_size)
{
INVARIANT_CHECK;
#if !TORRENT_USE_ASSERTS
TORRENT_UNUSED(len);
#endif
TORRENT_ASSERT(crypto_field <= 0x03 && crypto_field > 0);
// vc,crypto_field,len(pad),pad, (len(ia))
TORRENT_ASSERT((len >= 8+4+2+pad_size+2 && is_outgoing())
|| (len >= 8+4+2+pad_size && !is_outgoing()));
TORRENT_ASSERT(!m_sent_handshake);
// encrypt(vc, crypto_provide/select, len(Pad), len(IA))
// len(pad) is zero for now, len(IA) only for outgoing connections
// vc
memset(write_buf, 0, 8);
write_buf += 8;
detail::write_uint32(crypto_field, write_buf);
detail::write_uint16(pad_size, write_buf); // len (pad)
// fill pad with zeroes
std::generate(write_buf, write_buf + pad_size, random_byte);
write_buf += pad_size;
// append len(ia) if we are initiating
if (is_outgoing())
detail::write_uint16(handshake_len, write_buf); // len(IA)
}
int bt_peer_connection::get_syncoffset(char const* src, int const src_size
, char const* target, int const target_size) const
{
TORRENT_ASSERT(target_size >= src_size);
TORRENT_ASSERT(src_size > 0);
TORRENT_ASSERT(src);
TORRENT_ASSERT(target);
int const traverse_limit = target_size - src_size;
// TODO: this could be optimized using knuth morris pratt
for (int i = 0; i < traverse_limit; ++i)
{
char const* target_ptr = target + i;
if (std::equal(src, src+src_size, target_ptr))
return i;
}
// no complete sync
return -1;
}
void bt_peer_connection::rc4_decrypt(span<char> buf)
{
int consume = 0;
int produce = int(buf.size());
int packet_size = 0;
m_rc4->decrypt(buf, consume, produce, packet_size);
}
namespace {
void regular_c_free(char* buf, void* /* userdata */
, block_cache_reference /* ref */)
{
std::free(buf);
}
}
#endif // #if !defined(TORRENT_DISABLE_ENCRYPTION) && !defined(TORRENT_DISABLE_EXTENSIONS)
void bt_peer_connection::append_const_send_buffer(char const* buffer, int size
, chained_buffer::free_buffer_fun destructor, void* userdata
, block_cache_reference ref)
{
#if !defined(TORRENT_DISABLE_ENCRYPTION) && !defined(TORRENT_DISABLE_EXTENSIONS)
if (!m_enc_handler.is_send_plaintext())
{
// if we're encrypting this buffer, we need to make a copy
// since we'll mutate it
char* buf = static_cast<char*>(std::malloc(size));
std::memcpy(buf, buffer, size);
append_send_buffer(buf, size, ®ular_c_free, nullptr);
destructor(const_cast<char*>(buffer), userdata, ref);
}
else
#endif
{
peer_connection::append_const_send_buffer(buffer, size, destructor
, userdata, ref);
}
}
void bt_peer_connection::write_handshake()
{
INVARIANT_CHECK;
TORRENT_ASSERT(!m_sent_handshake);
m_sent_handshake = true;
boost::shared_ptr<torrent> t = associated_torrent().lock();
TORRENT_ASSERT(t);
// add handshake to the send buffer
const char version_string[] = "BitTorrent protocol";
const int string_len = sizeof(version_string) - 1;
char handshake[1 + string_len + 8 + 20 + 20];
char* ptr = handshake;
// length of version string
detail::write_uint8(string_len, ptr);
// protocol identifier
std::memcpy(ptr, version_string, string_len);
ptr += string_len;
// 8 zeroes
memset(ptr, 0, 8);
#ifndef TORRENT_DISABLE_DHT
// indicate that we support the DHT messages
*(ptr + 7) |= 0x01;
#endif
#ifndef TORRENT_DISABLE_EXTENSIONS
// we support extensions
*(ptr + 5) |= 0x10;
#endif
if (m_settings.get_bool(settings_pack::support_merkle_torrents))
{
// we support merkle torrents
*(ptr + 5) |= 0x08;
}
// we support FAST extension
*(ptr + 7) |= 0x04;
#ifndef TORRENT_DISABLE_LOGGING
std::string bitmask;
for (int k = 0; k < 8; ++k)
{
for (int j = 0; j < 8; ++j)
{
if (ptr[k] & (0x80 >> j)) bitmask += '1';
else bitmask += '0';
}
}
peer_log(peer_log_alert::outgoing_message, "EXTENSIONS"
, "%s", bitmask.c_str());
#endif
ptr += 8;
// info hash
sha1_hash const& ih = t->torrent_file().info_hash();
std::memcpy(ptr, ih.data(), ih.size());
ptr += 20;
// peer id
if (m_settings.get_bool(settings_pack::anonymous_mode))
{
// in anonymous mode, every peer connection
// has a unique peer-id
for (int i = 0; i < 20; ++i)
m_our_peer_id[i] = random() & 0xff;
}
std::memcpy(ptr, m_our_peer_id.data(), 20);
ptr += 20;
#ifndef TORRENT_DISABLE_LOGGING
{
char hex_pid[41];
aux::to_hex(m_our_peer_id, hex_pid);
hex_pid[40] = 0;
peer_log(peer_log_alert::outgoing, "HANDSHAKE"
, "sent peer_id: %s client: %s"
, hex_pid, identify_client(m_our_peer_id).c_str());
}
peer_log(peer_log_alert::outgoing_message, "HANDSHAKE"
, "ih: %s", aux::to_hex(ih).c_str());
#endif
send_buffer(handshake, sizeof(handshake));
}
boost::optional<piece_block_progress> bt_peer_connection::downloading_piece_progress() const
{
boost::shared_ptr<torrent> t = associated_torrent().lock();
TORRENT_ASSERT(t);
span<char const> recv_buffer = m_recv_buffer.get();
// are we currently receiving a 'piece' message?
if (m_state != read_packet
|| int(recv_buffer.size()) <= 9
|| recv_buffer[0] != msg_piece)
return boost::optional<piece_block_progress>();
const char* ptr = recv_buffer.begin() + 1;
peer_request r;
r.piece = detail::read_int32(ptr);
r.start = detail::read_int32(ptr);
r.length = m_recv_buffer.packet_size() - 9;
// is any of the piece message header data invalid?
if (!verify_piece(r))
return boost::optional<piece_block_progress>();
piece_block_progress p;
p.piece_index = r.piece;
p.block_index = r.start / t->block_size();
p.bytes_downloaded = int(recv_buffer.size()) - 9;
p.full_block_bytes = r.length;
return boost::optional<piece_block_progress>(p);
}
// message handlers
// -----------------------------
// --------- KEEPALIVE ---------
// -----------------------------
void bt_peer_connection::on_keepalive()
{
INVARIANT_CHECK;
#ifndef TORRENT_DISABLE_LOGGING
peer_log(peer_log_alert::incoming_message, "KEEPALIVE");
#endif
incoming_keepalive();
}
// -----------------------------
// ----------- CHOKE -----------
// -----------------------------
void bt_peer_connection::on_choke(int received)
{
INVARIANT_CHECK;
TORRENT_ASSERT(received >= 0);
received_bytes(0, received);
if (m_recv_buffer.packet_size() != 1)
{
disconnect(errors::invalid_choke, op_bittorrent, 2);
return;
}
if (!m_recv_buffer.packet_finished()) return;
incoming_choke();
if (is_disconnecting()) return;
if (!m_supports_fast)
{
// we just got choked, and the peer that choked use
// doesn't support fast extensions, so we have to
// assume that the choke message implies that all
// of our requests are rejected. Go through them and
// pretend that we received reject request messages
boost::shared_ptr<torrent> t = associated_torrent().lock();
TORRENT_ASSERT(t);
while (!download_queue().empty())
{
piece_block const& b = download_queue().front().block;
peer_request r;
r.piece = b.piece_index;
r.start = b.block_index * t->block_size();
r.length = t->block_size();
// if it's the last piece, make sure to
// set the length of the request to not
// exceed the end of the torrent. This is
// necessary in order to maintain a correct
// m_outsanding_bytes
if (r.piece == t->torrent_file().num_pieces() - 1)
{
r.length = (std::min)(t->torrent_file().piece_size(
r.piece) - r.start, r.length);
}
incoming_reject_request(r);
}
}
}
// -----------------------------
// ---------- UNCHOKE ----------
// -----------------------------
void bt_peer_connection::on_unchoke(int received)
{
INVARIANT_CHECK;
TORRENT_ASSERT(received >= 0);
received_bytes(0, received);
if (m_recv_buffer.packet_size() != 1)
{
disconnect(errors::invalid_unchoke, op_bittorrent, 2);
return;
}
if (!m_recv_buffer.packet_finished()) return;
incoming_unchoke();
}
// -----------------------------
// -------- INTERESTED ---------
// -----------------------------
void bt_peer_connection::on_interested(int received)
{
INVARIANT_CHECK;
TORRENT_ASSERT(received >= 0);
received_bytes(0, received);
if (m_recv_buffer.packet_size() != 1)
{
disconnect(errors::invalid_interested, op_bittorrent, 2);
return;
}
if (!m_recv_buffer.packet_finished()) return;
// we defer sending the allowed set until the peer says it's interested in
// us. This saves some bandwidth and allows us to omit messages for pieces
// that the peer already has
if (!m_sent_allowed_fast && m_supports_fast)
{
m_sent_allowed_fast = true;
send_allowed_set();
}
incoming_interested();
}
// -----------------------------
// ------ NOT INTERESTED -------
// -----------------------------
void bt_peer_connection::on_not_interested(int received)
{
INVARIANT_CHECK;
TORRENT_ASSERT(received >= 0);
received_bytes(0, received);
if (m_recv_buffer.packet_size() != 1)
{
disconnect(errors::invalid_not_interested, op_bittorrent, 2);
return;
}
if (!m_recv_buffer.packet_finished()) return;
incoming_not_interested();
}