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deluge/libtorrent/src/bt_peer_connection.cpp

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/*
Copyright (c) 2003 - 2006, Arvid Norberg
Copyright (c) 2007, 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/pch.hpp"
#include <vector>
#include <iostream>
#include <iomanip>
#include <limits>
#include <boost/bind.hpp>
#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/version.hpp"
#include "libtorrent/extensions.hpp"
#include "libtorrent/aux_/session_impl.hpp"
#ifndef TORRENT_DISABLE_ENCRYPTION
#include "libtorrent/pe_crypto.hpp"
#include "libtorrent/hasher.hpp"
#endif
using boost::bind;
using boost::shared_ptr;
using libtorrent::aux::session_impl;
namespace libtorrent
{
const bt_peer_connection::message_handler
bt_peer_connection::m_message_handler[] =
{
&bt_peer_connection::on_choke,
&bt_peer_connection::on_unchoke,
&bt_peer_connection::on_interested,
&bt_peer_connection::on_not_interested,
&bt_peer_connection::on_have,
&bt_peer_connection::on_bitfield,
&bt_peer_connection::on_request,
&bt_peer_connection::on_piece,
&bt_peer_connection::on_cancel,
&bt_peer_connection::on_dht_port,
0, 0, 0,
// FAST extension messages
&bt_peer_connection::on_suggest_piece,
&bt_peer_connection::on_have_all,
&bt_peer_connection::on_have_none,
&bt_peer_connection::on_reject_request,
&bt_peer_connection::on_allowed_fast,
0, 0,
&bt_peer_connection::on_extended
};
bt_peer_connection::bt_peer_connection(
session_impl& ses
, boost::weak_ptr<torrent> tor
, shared_ptr<socket_type> s
, tcp::endpoint const& remote
, policy::peer* peerinfo)
: peer_connection(ses, tor, s, remote
, peerinfo)
, m_state(read_protocol_identifier)
#ifndef TORRENT_DISABLE_EXTENSIONS
, m_supports_extensions(false)
#endif
, m_supports_dht_port(false)
, m_supports_fast(false)
#ifndef TORRENT_DISABLE_ENCRYPTION
, m_encrypted(false)
, m_rc4_encrypted(false)
, m_sync_bytes_read(0)
, m_enc_send_buffer(0, 0)
#endif
#ifndef NDEBUG
, m_sent_bitfield(false)
, m_in_constructor(true)
, m_sent_handshake(false)
#endif
{
#ifdef TORRENT_VERBOSE_LOGGING
(*m_logger) << "*** bt_peer_connection\n";
#endif
#ifndef NDEBUG
m_in_constructor = false;
#endif
}
bt_peer_connection::bt_peer_connection(
session_impl& ses
, boost::shared_ptr<socket_type> s
, policy::peer* peerinfo)
: peer_connection(ses, s, peerinfo)
, m_state(read_protocol_identifier)
#ifndef TORRENT_DISABLE_EXTENSIONS
, m_supports_extensions(false)
#endif
, m_supports_dht_port(false)
, m_supports_fast(false)
#ifndef TORRENT_DISABLE_ENCRYPTION
, m_encrypted(false)
, m_rc4_encrypted(false)
, m_sync_bytes_read(0)
, m_enc_send_buffer(0, 0)
#endif
#ifndef NDEBUG
, m_sent_bitfield(false)
, m_in_constructor(true)
, m_sent_handshake(false)
#endif
{
// we are not attached to any torrent yet.
// we have to wait for the handshake to see
// which torrent the connector want's to connect to
// upload bandwidth will only be given to connections
// that are part of a torrent. Since this is an incoming
// connection, we have to give it some initial bandwidth
// to send the handshake.
#ifndef TORRENT_DISABLE_ENCRYPTION
m_bandwidth_limit[download_channel].assign(2048);
m_bandwidth_limit[upload_channel].assign(2048);
#else
m_bandwidth_limit[download_channel].assign(80);
m_bandwidth_limit[upload_channel].assign(80);
#endif
// start in the state where we are trying to read the
// handshake from the other side
reset_recv_buffer(20);
setup_receive();
#ifndef NDEBUG
m_in_constructor = false;
#endif
}
bt_peer_connection::~bt_peer_connection()
{
}
void bt_peer_connection::on_connected()
{
#ifndef TORRENT_DISABLE_ENCRYPTION
pe_settings::enc_policy const& out_enc_policy = m_ses.get_pe_settings().out_enc_policy;
if (out_enc_policy == pe_settings::forced)
{
write_pe1_2_dhkey();
m_state = read_pe_dhkey;
reset_recv_buffer(dh_key_len);
setup_receive();
}
else if (out_enc_policy == pe_settings::enabled)
{
TORRENT_ASSERT(peer_info_struct());
policy::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();
m_state = read_pe_dhkey;
reset_recv_buffer(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();
reset_recv_buffer(20);
setup_receive();
}
}
else if (out_enc_policy == pe_settings::disabled)
#endif
{
write_handshake();
// start in the state where we are trying to read the
// handshake from the other side
reset_recv_buffer(20);
setup_receive();
}
}
void bt_peer_connection::on_metadata()
{
boost::shared_ptr<torrent> t = associated_torrent().lock();
TORRENT_ASSERT(t);
write_bitfield(t->pieces());
#ifndef TORRENT_DISABLE_DHT
if (m_supports_dht_port && m_ses.m_dht)
write_dht_port(m_ses.get_dht_settings().service_port);
#endif
}
void bt_peer_connection::write_dht_port(int listen_port)
{
INVARIANT_CHECK;
TORRENT_ASSERT(m_sent_handshake && m_sent_bitfield);
#ifdef TORRENT_VERBOSE_LOGGING
(*m_logger) << time_now_string()
<< " ==> DHT_PORT [ " << listen_port << " ]\n";
#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));
}
void bt_peer_connection::write_have_all()
{
INVARIANT_CHECK;
TORRENT_ASSERT(m_sent_handshake && !m_sent_bitfield);
#ifndef NDEBUG
m_sent_bitfield = true;
#endif
#ifdef TORRENT_VERBOSE_LOGGING
(*m_logger) << time_now_string()
<< " ==> HAVE_ALL\n";
#endif
char msg[] = {0,0,0,1, msg_have_all};
send_buffer(msg, sizeof(msg));
}
void bt_peer_connection::write_have_none()
{
INVARIANT_CHECK;
TORRENT_ASSERT(m_sent_handshake && !m_sent_bitfield);
#ifndef NDEBUG
m_sent_bitfield = true;
#endif
#ifdef TORRENT_VERBOSE_LOGGING
(*m_logger) << time_now_string()
<< " ==> HAVE_NONE\n";
#endif
char msg[] = {0,0,0,1, msg_have_none};
send_buffer(msg, sizeof(msg));
}
void bt_peer_connection::write_reject_request(peer_request const& r)
{
INVARIANT_CHECK;
if (!m_supports_fast) return;
TORRENT_ASSERT(m_sent_handshake && 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));
}
void bt_peer_connection::write_allow_fast(int piece)
{
INVARIANT_CHECK;
TORRENT_ASSERT(m_sent_handshake && m_sent_bitfield);
TORRENT_ASSERT(associated_torrent().lock()->valid_metadata());
TORRENT_ASSERT(m_supports_fast);
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));
}
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_local()) p.flags |= peer_info::local_connection;
#ifndef TORRENT_DISABLE_ENCRYPTION
if (m_encrypted)
{
m_rc4_encrypted ?
p.flags |= peer_info::rc4_encrypted :
p.flags |= peer_info::plaintext_encrypted;
}
#endif
if (!is_connecting() && in_handshake())
p.flags |= peer_info::handshake;
if (is_connecting() && !is_queued()) p.flags |= peer_info::connecting;
if (is_queued()) p.flags |= peer_info::queued;
p.client = m_client_version;
p.connection_type = peer_info::standard_bittorrent;
}
bool bt_peer_connection::in_handshake() const
{
return m_state < read_packet_size;
}
#ifndef TORRENT_DISABLE_ENCRYPTION
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);
#ifdef TORRENT_VERBOSE_LOGGING
if (is_local())
(*m_logger) << " initiating encrypted handshake\n";
#endif
m_DH_key_exchange.reset(new DH_key_exchange);
int pad_size = std::rand() % 512;
#ifdef TORRENT_VERBOSE_LOGGING
(*m_logger) << " pad size: " << pad_size << "\n";
#endif
buffer::interval send_buf = allocate_send_buffer(dh_key_len + pad_size);
std::copy(m_DH_key_exchange->get_local_key(),
m_DH_key_exchange->get_local_key() + dh_key_len,
send_buf.begin);
std::generate(send_buf.begin + dh_key_len, send_buf.end, std::rand);
setup_send();
#ifdef TORRENT_VERBOSE_LOGGING
(*m_logger) << " sent DH key\n";
#endif
}
void bt_peer_connection::write_pe3_sync()
{
INVARIANT_CHECK;
TORRENT_ASSERT(!m_encrypted);
TORRENT_ASSERT(!m_rc4_encrypted);
TORRENT_ASSERT(is_local());
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();
char const* const secret = m_DH_key_exchange->get_secret();
int pad_size = rand() % 512;
// synchash,skeyhash,vc,crypto_provide,len(pad),pad,len(ia)
buffer::interval send_buf =
allocate_send_buffer(20 + 20 + 8 + 4 + 2 + pad_size + 2);
// sync hash (hash('req1',S))
h.reset();
h.update("req1",4);
h.update(secret, dh_key_len);
sha1_hash sync_hash = h.final();
std::copy(sync_hash.begin(), sync_hash.end(), send_buf.begin);
send_buf.begin += 20;
// stream key obfuscated hash [ hash('req2',SKEY) xor hash('req3',S) ]
h.reset();
h.update("req2",4);
h.update((const char*)info_hash.begin(), 20);
sha1_hash streamkey_hash = h.final();
h.reset();
h.update("req3",4);
h.update(secret, dh_key_len);
sha1_hash obfsc_hash = h.final();
obfsc_hash ^= streamkey_hash;
std::copy(obfsc_hash.begin(), obfsc_hash.end(), send_buf.begin);
send_buf.begin += 20;
// Discard DH key exchange data, setup RC4 keys
init_pe_RC4_handler(secret, info_hash);
m_DH_key_exchange.reset(); // secret should be invalid at this point
// write the verification constant and crypto field
TORRENT_ASSERT(send_buf.left() == 8 + 4 + 2 + pad_size + 2);
int encrypt_size = send_buf.left();
int crypto_provide = 0;
pe_settings::enc_level const& allowed_enc_level = m_ses.get_pe_settings().allowed_enc_level;
if (allowed_enc_level == pe_settings::both)
crypto_provide = 0x03;
else if (allowed_enc_level == pe_settings::rc4)
crypto_provide = 0x02;
else if (allowed_enc_level == pe_settings::plaintext)
crypto_provide = 0x01;
#ifdef TORRENT_VERBOSE_LOGGING
(*m_logger) << " crypto provide : [ ";
if (allowed_enc_level == pe_settings::both)
(*m_logger) << "plaintext rc4 ]\n";
else if (allowed_enc_level == pe_settings::rc4)
(*m_logger) << "rc4 ]\n";
else if (allowed_enc_level == pe_settings::plaintext)
(*m_logger) << "plaintext ]\n";
#endif
write_pe_vc_cryptofield(send_buf, crypto_provide, pad_size);
m_RC4_handler->encrypt(send_buf.end - encrypt_size, encrypt_size);
TORRENT_ASSERT(send_buf.begin == send_buf.end);
setup_send();
}
void bt_peer_connection::write_pe4_sync(int crypto_select)
{
INVARIANT_CHECK;
TORRENT_ASSERT(!is_local());
TORRENT_ASSERT(!m_encrypted);
TORRENT_ASSERT(!m_rc4_encrypted);
TORRENT_ASSERT(crypto_select == 0x02 || crypto_select == 0x01);
TORRENT_ASSERT(!m_sent_handshake);
int pad_size =rand() % 512;
const int buf_size = 8 + 4 + 2 + pad_size;
buffer::interval send_buf = allocate_send_buffer(buf_size);
write_pe_vc_cryptofield(send_buf, crypto_select, pad_size);
m_RC4_handler->encrypt(send_buf.end - buf_size, buf_size);
setup_send();
// encryption method has been negotiated
if (crypto_select == 0x02)
m_rc4_encrypted = true;
else // 0x01
m_rc4_encrypted = false;
#ifdef TORRENT_VERBOSE_LOGGING
(*m_logger) << " crypto select : [ ";
if (crypto_select == 0x01)
(*m_logger) << "plaintext ]\n";
else
(*m_logger) << "rc4 ]\n";
#endif
}
void bt_peer_connection::write_pe_vc_cryptofield(buffer::interval& write_buf
, int crypto_field, int pad_size)
{
INVARIANT_CHECK;
TORRENT_ASSERT(crypto_field <= 0x03 && crypto_field > 0);
// vc,crypto_field,len(pad),pad, (len(ia))
TORRENT_ASSERT( (write_buf.left() == 8+4+2+pad_size+2 && is_local()) ||
(write_buf.left() == 8+4+2+pad_size && !is_local()) );
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
std::fill(write_buf.begin, write_buf.begin + 8, 0);
write_buf.begin += 8;
detail::write_uint32(crypto_field, write_buf.begin);
detail::write_uint16(pad_size, write_buf.begin); // len (pad)
// fill pad with zeroes
std::generate(write_buf.begin, write_buf.begin + pad_size, &std::rand);
write_buf.begin += pad_size;
// append len(ia) if we are initiating
if (is_local())
detail::write_uint16(handshake_len, write_buf.begin); // len(IA)
TORRENT_ASSERT(write_buf.begin == write_buf.end);
}
void bt_peer_connection::init_pe_RC4_handler(char const* secret, sha1_hash const& stream_key)
{
INVARIANT_CHECK;
TORRENT_ASSERT(secret);
hasher h;
static const char keyA[] = "keyA";
static const char keyB[] = "keyB";
// encryption rc4 longkeys
// outgoing connection : hash ('keyA',S,SKEY)
// incoming connection : hash ('keyB',S,SKEY)
is_local() ? h.update(keyA, 4) : h.update(keyB, 4);
h.update(secret, dh_key_len);
h.update((char const*)stream_key.begin(), 20);
const sha1_hash local_key = h.final();
h.reset();
// decryption rc4 longkeys
// outgoing connection : hash ('keyB',S,SKEY)
// incoming connection : hash ('keyA',S,SKEY)
is_local() ? h.update(keyB, 4) : h.update(keyA, 4);
h.update(secret, dh_key_len);
h.update((char const*)stream_key.begin(), 20);
const sha1_hash remote_key = h.final();
TORRENT_ASSERT(!m_RC4_handler.get());
m_RC4_handler.reset(new RC4_handler (local_key, remote_key));
#ifdef TORRENT_VERBOSE_LOGGING
(*m_logger) << " computed RC4 keys\n";
#endif
}
void bt_peer_connection::send_buffer(char* buf, int size)
{
TORRENT_ASSERT(buf);
TORRENT_ASSERT(size > 0);
if (m_encrypted && m_rc4_encrypted)
m_RC4_handler->encrypt(buf, size);
peer_connection::send_buffer(buf, size);
}
buffer::interval bt_peer_connection::allocate_send_buffer(int size)
{
if (m_encrypted && m_rc4_encrypted)
{
TORRENT_ASSERT(m_enc_send_buffer.left() == 0);
m_enc_send_buffer = peer_connection::allocate_send_buffer(size);
return m_enc_send_buffer;
}
else
{
buffer::interval i = peer_connection::allocate_send_buffer(size);
return i;
}
}
void bt_peer_connection::setup_send()
{
if (m_encrypted && m_rc4_encrypted && m_enc_send_buffer.left())
{
TORRENT_ASSERT(m_enc_send_buffer.begin);
TORRENT_ASSERT(m_enc_send_buffer.end);
m_RC4_handler->encrypt(m_enc_send_buffer.begin, m_enc_send_buffer.left());
m_enc_send_buffer.end = m_enc_send_buffer.begin;
}
peer_connection::setup_send();
}
int bt_peer_connection::get_syncoffset(char const* src, int src_size,
char const* target, int target_size) const
{
TORRENT_ASSERT(target_size >= src_size);
TORRENT_ASSERT(src_size > 0);
TORRENT_ASSERT(src);
TORRENT_ASSERT(target);
int 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;
}
// // Partial sync
// for (int i = 0; i < target_size; ++i)
// {
// // first is iterator in src[] at which mismatch occurs
// // second is iterator in target[] at which mismatch occurs
// std::pair<const char*, const char*> ret;
// int src_sync_size;
// if (i > traverse_limit) // partial sync test
// {
// ret = std::mismatch(src, src + src_size - (i - traverse_limit), &target[i]);
// src_sync_size = ret.first - src;
// if (src_sync_size == (src_size - (i - traverse_limit)))
// return i;
// }
// else // complete sync test
// {
// ret = std::mismatch(src, src + src_size, &target[i]);
// src_sync_size = ret.first - src;
// if (src_sync_size == src_size)
// return i;
// }
// }
// no complete sync
return -1;
}
#endif // #ifndef TORRENT_DISABLE_ENCRYPTION
void bt_peer_connection::write_handshake()
{
INVARIANT_CHECK;
TORRENT_ASSERT(!m_sent_handshake);
#ifndef NDEBUG
m_sent_handshake = true;
#endif
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;
buffer::interval i = allocate_send_buffer(1 + string_len + 8 + 20 + 20);
// length of version string
*i.begin = string_len;
++i.begin;
// version string itself
std::copy(
version_string
, version_string + string_len
, i.begin);
i.begin += string_len;
// 8 zeroes
std::fill(i.begin, i.begin + 8, 0);
#ifndef TORRENT_DISABLE_DHT
// indicate that we support the DHT messages
*(i.begin + 7) |= 0x01;
#endif
#ifndef TORRENT_DISABLE_EXTENSIONS
// we support extensions
*(i.begin + 5) |= 0x10;
#endif
// we support FAST extension
*(i.begin + 7) |= 0x04;
i.begin += 8;
// info hash
sha1_hash const& ih = t->torrent_file().info_hash();
std::copy(ih.begin(), ih.end(), i.begin);
i.begin += 20;
// peer id
std::copy(
m_ses.get_peer_id().begin()
, m_ses.get_peer_id().end()
, i.begin);
i.begin += 20;
TORRENT_ASSERT(i.begin == i.end);
#ifdef TORRENT_VERBOSE_LOGGING
(*m_logger) << time_now_string() << " ==> HANDSHAKE\n";
#endif
setup_send();
}
boost::optional<piece_block_progress> bt_peer_connection::downloading_piece_progress() const
{
boost::shared_ptr<torrent> t = associated_torrent().lock();
TORRENT_ASSERT(t);
buffer::const_interval recv_buffer = receive_buffer();
// are we currently receiving a 'piece' message?
if (m_state != read_packet
|| recv_buffer.left() < 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 = 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 = recv_buffer.left() - 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;
#ifdef TORRENT_VERBOSE_LOGGING
(*m_logger) << time_now_string() << " <== KEEPALIVE\n";
#endif
incoming_keepalive();
}
// -----------------------------
// ----------- CHOKE -----------
// -----------------------------
void bt_peer_connection::on_choke(int received)
{
INVARIANT_CHECK;
TORRENT_ASSERT(received > 0);
if (packet_size() != 1)
throw protocol_error("'choke' message size != 1");
m_statistics.received_bytes(0, received);
if (!packet_finished()) return;
incoming_choke();
if (!m_supports_fast)
{
boost::shared_ptr<torrent> t = associated_torrent().lock();
TORRENT_ASSERT(t);
while (!download_queue().empty())
{
piece_block const& b = download_queue().front();
peer_request r;
r.piece = b.piece_index;
r.start = b.block_index * t->block_size();
r.length = t->block_size();
incoming_reject_request(r);
}
}
}
// -----------------------------
// ---------- UNCHOKE ----------
// -----------------------------
void bt_peer_connection::on_unchoke(int received)
{
INVARIANT_CHECK;
TORRENT_ASSERT(received > 0);
if (packet_size() != 1)
throw protocol_error("'unchoke' message size != 1");
m_statistics.received_bytes(0, received);
if (!packet_finished()) return;
incoming_unchoke();
}
// -----------------------------
// -------- INTERESTED ---------
// -----------------------------
void bt_peer_connection::on_interested(int received)
{
INVARIANT_CHECK;
TORRENT_ASSERT(received > 0);
if (packet_size() != 1)
throw protocol_error("'interested' message size != 1");
m_statistics.received_bytes(0, received);
if (!packet_finished()) return;
incoming_interested();
}
// -----------------------------
// ------ NOT INTERESTED -------
// -----------------------------
void bt_peer_connection::on_not_interested(int received)
{
INVARIANT_CHECK;
TORRENT_ASSERT(received > 0);
if (packet_size() != 1)
throw protocol_error("'not interested' message size != 1");
m_statistics.received_bytes(0, received);
if (!packet_finished()) return;
incoming_not_interested();
}
// -----------------------------
// ----------- HAVE ------------
// -----------------------------
void bt_peer_connection::on_have(int received)
{
INVARIANT_CHECK;
TORRENT_ASSERT(received > 0);
if (packet_size() != 5)
throw protocol_error("'have' message size != 5");
m_statistics.received_bytes(0, received);
if (!packet_finished()) return;
buffer::const_interval recv_buffer = receive_buffer();
const char* ptr = recv_buffer.begin + 1;
int index = detail::read_int32(ptr);
incoming_have(index);
}
// -----------------------------
// --------- BITFIELD ----------
// -----------------------------
void bt_peer_connection::on_bitfield(int received)
{
INVARIANT_CHECK;
TORRENT_ASSERT(received > 0);
boost::shared_ptr<torrent> t = associated_torrent().lock();
TORRENT_ASSERT(t);
// if we don't have the metedata, we cannot
// verify the bitfield size
if (t->valid_metadata()
&& packet_size() - 1 != ((int)get_bitfield().size() + 7) / 8)
throw protocol_error("bitfield with invalid size");
m_statistics.received_bytes(0, received);
if (!packet_finished()) return;
buffer::const_interval recv_buffer = receive_buffer();
std::vector<bool> bitfield;
if (!t->valid_metadata())
bitfield.resize((packet_size() - 1) * 8);
else
bitfield.resize(get_bitfield().size());
// if we don't have metadata yet
// just remember the bitmask
// don't update the piecepicker
// (since it doesn't exist yet)
for (int i = 0; i < (int)bitfield.size(); ++i)
bitfield[i] = (recv_buffer[1 + (i>>3)] & (1 << (7 - (i&7)))) != 0;
incoming_bitfield(bitfield);
}
// -----------------------------
// ---------- REQUEST ----------
// -----------------------------
void bt_peer_connection::on_request(int received)
{
INVARIANT_CHECK;
TORRENT_ASSERT(received > 0);
if (packet_size() != 13)
throw protocol_error("'request' message size != 13");
m_statistics.received_bytes(0, received);
if (!packet_finished()) return;
buffer::const_interval recv_buffer = receive_buffer();
peer_request r;
const char* ptr = recv_buffer.begin + 1;
r.piece = detail::read_int32(ptr);
r.start = detail::read_int32(ptr);
r.length = detail::read_int32(ptr);
incoming_request(r);
}
// -----------------------------
// ----------- PIECE -----------
// -----------------------------
void bt_peer_connection::on_piece(int received)
{
INVARIANT_CHECK;
TORRENT_ASSERT(received > 0);
buffer::const_interval recv_buffer = receive_buffer();
int recv_pos = recv_buffer.end - recv_buffer.begin;
// classify the received data as protocol chatter
// or data payload for the statistics
if (recv_pos <= 9)
// only received protocol data
m_statistics.received_bytes(0, received);
else if (recv_pos - received >= 9)
// only received payload data
m_statistics.received_bytes(received, 0);
else
{
// received a bit of both
TORRENT_ASSERT(recv_pos - received < 9);
TORRENT_ASSERT(recv_pos > 9);
TORRENT_ASSERT(9 - (recv_pos - received) <= 9);
m_statistics.received_bytes(
recv_pos - 9
, 9 - (recv_pos - received));
}
incoming_piece_fragment();
if (!packet_finished()) return;
const char* ptr = recv_buffer.begin + 1;
peer_request p;
p.piece = detail::read_int32(ptr);
p.start = detail::read_int32(ptr);
p.length = packet_size() - 9;
incoming_piece(p, recv_buffer.begin + 9);
}
// -----------------------------
// ---------- CANCEL -----------
// -----------------------------
void bt_peer_connection::on_cancel(int received)
{
INVARIANT_CHECK;
TORRENT_ASSERT(received > 0);
if (packet_size() != 13)
throw protocol_error("'cancel' message size != 13");
m_statistics.received_bytes(0, received);
if (!packet_finished()) return;
buffer::const_interval recv_buffer = receive_buffer();
peer_request r;
const char* ptr = recv_buffer.begin + 1;
r.piece = detail::read_int32(ptr);
r.start = detail::read_int32(ptr);
r.length = detail::read_int32(ptr);
incoming_cancel(r);
}
// -----------------------------
// --------- DHT PORT ----------
// -----------------------------
void bt_peer_connection::on_dht_port(int received)
{
INVARIANT_CHECK;
if (!m_supports_dht_port)
throw protocol_error("got 'dht_port' message from peer that doesn't support it");
TORRENT_ASSERT(received > 0);
if (packet_size() != 3)
throw protocol_error("'dht_port' message size != 3");
m_statistics.received_bytes(0, received);
if (!packet_finished()) return;
buffer::const_interval recv_buffer = receive_buffer();
const char* ptr = recv_buffer.begin + 1;
int listen_port = detail::read_uint16(ptr);
incoming_dht_port(listen_port);
}
void bt_peer_connection::on_suggest_piece(int received)
{
INVARIANT_CHECK;
if (!m_supports_fast)
throw protocol_error("got 'suggest_piece' without FAST extension support");
m_statistics.received_bytes(0, received);
if (!packet_finished()) return;
buffer::const_interval recv_buffer = receive_buffer();
const char* ptr = recv_buffer.begin + 1;
int piece = detail::read_uint32(ptr);
incoming_suggest(piece);
}
void bt_peer_connection::on_have_all(int received)
{
INVARIANT_CHECK;
if (!m_supports_fast)
throw protocol_error("got 'have_all' without FAST extension support");
m_statistics.received_bytes(0, received);
incoming_have_all();
}
void bt_peer_connection::on_have_none(int received)
{
INVARIANT_CHECK;
if (!m_supports_fast)
throw protocol_error("got 'have_none' without FAST extension support");
m_statistics.received_bytes(0, received);
incoming_have_none();
}
void bt_peer_connection::on_reject_request(int received)
{
INVARIANT_CHECK;
if (!m_supports_fast)
throw protocol_error("got 'reject_request' without FAST extension support");
m_statistics.received_bytes(0, received);
if (!packet_finished()) return;
buffer::const_interval recv_buffer = receive_buffer();
peer_request r;
const char* ptr = recv_buffer.begin + 1;
r.piece = detail::read_int32(ptr);
r.start = detail::read_int32(ptr);
r.length = detail::read_int32(ptr);
incoming_reject_request(r);
}
void bt_peer_connection::on_allowed_fast(int received)
{
INVARIANT_CHECK;
if (!m_supports_fast)
throw protocol_error("got 'allowed_fast' without FAST extension support");
m_statistics.received_bytes(0, received);
if (!packet_finished()) return;
buffer::const_interval recv_buffer = receive_buffer();
const char* ptr = recv_buffer.begin + 1;
int index = detail::read_int32(ptr);
incoming_allowed_fast(index);
}
// -----------------------------
// --------- EXTENDED ----------
// -----------------------------
void bt_peer_connection::on_extended(int received)
{
INVARIANT_CHECK;
TORRENT_ASSERT(received > 0);
m_statistics.received_bytes(0, received);
if (packet_size() < 2)
throw protocol_error("'extended' message smaller than 2 bytes");
if (associated_torrent().expired())
throw protocol_error("'extended' message sent before proper handshake");
buffer::const_interval recv_buffer = receive_buffer();
if (recv_buffer.left() < 2) return;
TORRENT_ASSERT(*recv_buffer.begin == msg_extended);
++recv_buffer.begin;
int extended_id = detail::read_uint8(recv_buffer.begin);
if (extended_id == 0)
{
on_extended_handshake();
return;
}
#ifndef TORRENT_DISABLE_EXTENSIONS
for (extension_list_t::iterator i = m_extensions.begin()
, end(m_extensions.end()); i != end; ++i)
{
if ((*i)->on_extended(packet_size() - 2, extended_id
, recv_buffer))
return;
}
#endif
throw protocol_error("unknown extended message id: "
+ boost::lexical_cast<std::string>(extended_id));
}
void bt_peer_connection::on_extended_handshake()
{
if (!packet_finished()) return;
boost::shared_ptr<torrent> t = associated_torrent().lock();
TORRENT_ASSERT(t);
buffer::const_interval recv_buffer = receive_buffer();
entry root;
try
{
root = bdecode(recv_buffer.begin + 2, recv_buffer.end);
}
catch (std::exception& exc)
{
#ifdef TORRENT_VERBOSE_LOGGING
(*m_logger) << "invalid extended handshake: " << exc.what() << "\n";
#endif
return;
}
#ifdef TORRENT_VERBOSE_LOGGING
std::stringstream ext;
root.print(ext);
(*m_logger) << "<== EXTENDED HANDSHAKE: \n" << ext.str();
#endif
#ifndef TORRENT_DISABLE_EXTENSIONS
for (extension_list_t::iterator i = m_extensions.begin()
, end(m_extensions.end()); i != end;)
{
// a false return value means that the extension
// isn't supported by the other end. So, it is removed.
if (!(*i)->on_extension_handshake(root))
i = m_extensions.erase(i);
else
++i;
}
#endif
// there is supposed to be a remote listen port
if (entry* listen_port = root.find_key("p"))
{
if (listen_port->type() == entry::int_t
&& peer_info_struct() != 0)
{
t->get_policy().update_peer_port(listen_port->integer()
, peer_info_struct(), peer_info::incoming);
}
}
// there should be a version too
// but where do we put that info?
if (entry* client_info = root.find_key("v"))
{
if (client_info->type() == entry::string_t)
m_client_version = client_info->string();
}
if (entry* reqq = root.find_key("reqq"))
{
if (reqq->type() == entry::int_t)
m_max_out_request_queue = reqq->integer();
if (m_max_out_request_queue < 1)
m_max_out_request_queue = 1;
}
if (entry* myip = root.find_key("yourip"))
{
// TODO: don't trust this blindly
if (myip->type() == entry::string_t)
{
std::string const& my_ip = myip->string().c_str();
if (my_ip.size() == address_v4::bytes_type::static_size)
{
address_v4::bytes_type bytes;
std::copy(my_ip.begin(), my_ip.end(), bytes.begin());
m_ses.m_external_address = address_v4(bytes);
}
else if (my_ip.size() == address_v6::bytes_type::static_size)
{
address_v6::bytes_type bytes;
std::copy(my_ip.begin(), my_ip.end(), bytes.begin());
m_ses.m_external_address = address_v6(bytes);
}
}
}
}
bool bt_peer_connection::dispatch_message(int received)
{
INVARIANT_CHECK;
TORRENT_ASSERT(received > 0);
// this means the connection has been closed already
if (associated_torrent().expired()) return false;
buffer::const_interval recv_buffer = receive_buffer();
int packet_type = recv_buffer[0];
if (packet_type < 0
|| packet_type >= num_supported_messages
|| m_message_handler[packet_type] == 0)
{
#ifndef TORRENT_DISABLE_EXTENSIONS
for (extension_list_t::iterator i = m_extensions.begin()
, end(m_extensions.end()); i != end; ++i)
{
if ((*i)->on_unknown_message(packet_size(), packet_type
, buffer::const_interval(recv_buffer.begin+1
, recv_buffer.end)))
return packet_finished();
}
#endif
throw protocol_error("unknown message id: "
+ boost::lexical_cast<std::string>(packet_type)
+ " size: " + boost::lexical_cast<std::string>(packet_size()));
}
TORRENT_ASSERT(m_message_handler[packet_type] != 0);
// call the correct handler for this packet type
(this->*m_message_handler[packet_type])(received);
return packet_finished();
}
void bt_peer_connection::write_keepalive()
{
INVARIANT_CHECK;
// Don't require the bitfield to have been sent at this point
// the case where m_sent_bitfield may not be true is if the
// torrent doesn't have any metadata, and a peer is timimg out.
// then the keep-alive message will be sent before the bitfield
// this is a violation to the original protocol, but necessary
// for the metadata extension.
TORRENT_ASSERT(m_sent_handshake);
char msg[] = {0,0,0,0};
send_buffer(msg, sizeof(msg));
}
void bt_peer_connection::write_cancel(peer_request const& r)
{
INVARIANT_CHECK;
TORRENT_ASSERT(m_sent_handshake && m_sent_bitfield);
TORRENT_ASSERT(associated_torrent().lock()->valid_metadata());
char msg[17] = {0,0,0,13, msg_cancel};
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));
if (!m_supports_fast)
incoming_reject_request(r);
}
void bt_peer_connection::write_request(peer_request const& r)
{
INVARIANT_CHECK;
TORRENT_ASSERT(m_sent_handshake && m_sent_bitfield);
TORRENT_ASSERT(associated_torrent().lock()->valid_metadata());
char msg[17] = {0,0,0,13, msg_request};
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));
}
void bt_peer_connection::write_bitfield(std::vector<bool> const& bitfield)
{
INVARIANT_CHECK;
boost::shared_ptr<torrent> t = associated_torrent().lock();
TORRENT_ASSERT(t);
TORRENT_ASSERT(m_sent_handshake && !m_sent_bitfield);
TORRENT_ASSERT(t->valid_metadata());
// in this case, have_all or have_none should be sent instead
TORRENT_ASSERT(!m_supports_fast || !t->is_seed() || t->num_pieces() != 0);
if (m_supports_fast && t->is_seed())
{
write_have_all();
send_allowed_set();
return;
}
else if (m_supports_fast && t->num_pieces() == 0)
{
write_have_none();
send_allowed_set();
return;
}
int num_pieces = bitfield.size();
int lazy_pieces[50];
int num_lazy_pieces = 0;
int lazy_piece = 0;
TORRENT_ASSERT(t->is_seed() == (std::count(bitfield.begin(), bitfield.end(), true) == num_pieces));
if (t->is_seed() && m_ses.settings().lazy_bitfields)
{
num_lazy_pieces = (std::min)(50, num_pieces / 10);
if (num_lazy_pieces < 1) num_lazy_pieces = 1;
for (int i = 0; i < num_pieces; ++i)
{
if (rand() % (num_pieces - i) >= num_lazy_pieces - lazy_piece) continue;
lazy_pieces[lazy_piece++] = i;
}
TORRENT_ASSERT(lazy_piece == num_lazy_pieces);
lazy_piece = 0;
}
#ifdef TORRENT_VERBOSE_LOGGING
(*m_logger) << time_now_string() << " ==> BITFIELD ";
std::stringstream bitfield_string;
for (int i = 0; i < (int)get_bitfield().size(); ++i)
{
if (lazy_piece < num_lazy_pieces
&& lazy_pieces[lazy_piece] == i)
{
bitfield_string << "0";
++lazy_piece;
continue;
}
if (bitfield[i]) bitfield_string << "1";
else bitfield_string << "0";
}
bitfield_string << "\n";
(*m_logger) << bitfield_string.str();
lazy_piece = 0;
#endif
const int packet_size = (num_pieces + 7) / 8 + 5;
buffer::interval i = allocate_send_buffer(packet_size);
detail::write_int32(packet_size - 4, i.begin);
detail::write_uint8(msg_bitfield, i.begin);
std::fill(i.begin, i.end, 0);
for (int c = 0; c < num_pieces; ++c)
{
if (lazy_piece < num_lazy_pieces
&& lazy_pieces[lazy_piece] == c)
{
++lazy_piece;
continue;
}
if (bitfield[c])
i.begin[c >> 3] |= 1 << (7 - (c & 7));
}
TORRENT_ASSERT(i.end - i.begin == (num_pieces + 7) / 8);
#ifndef NDEBUG
m_sent_bitfield = true;
#endif
setup_send();
if (num_lazy_pieces > 0)
{
for (int i = 0; i < num_lazy_pieces; ++i)
{
write_have(lazy_pieces[i]);
#ifdef TORRENT_VERBOSE_LOGGING
(*m_logger) << time_now_string()
<< " ==> HAVE [ piece: " << lazy_pieces[i] << "]\n";
#endif
}
}
if (m_supports_fast)
send_allowed_set();
}
#ifndef TORRENT_DISABLE_EXTENSIONS
void bt_peer_connection::write_extensions()
{
INVARIANT_CHECK;
#ifdef TORRENT_VERBOSE_LOGGING
(*m_logger) << time_now_string() << " ==> EXTENSIONS\n";
#endif
TORRENT_ASSERT(m_supports_extensions);
TORRENT_ASSERT(m_sent_handshake);
entry handshake(entry::dictionary_t);
entry extension_list(entry::dictionary_t);
handshake["m"] = extension_list;
// only send the port in case we bade the connection
// on incoming connections the other end already knows
// our listen port
if (is_local()) handshake["p"] = m_ses.listen_port();
handshake["v"] = m_ses.settings().user_agent;
std::string remote_address;
std::back_insert_iterator<std::string> out(remote_address);
detail::write_address(remote().address(), out);
handshake["yourip"] = remote_address;
handshake["reqq"] = m_ses.settings().max_allowed_in_request_queue;
tcp::endpoint ep = m_ses.get_ipv6_interface();
if (ep != tcp::endpoint())
{
std::string ipv6_address;
std::back_insert_iterator<std::string> out(ipv6_address);
detail::write_address(ep.address(), out);
handshake["ipv6"] = ipv6_address;
}
// loop backwards, to make the first extension be the last
// to fill in the handshake (i.e. give the first extensions priority)
for (extension_list_t::reverse_iterator i = m_extensions.rbegin()
, end(m_extensions.rend()); i != end; ++i)
{
(*i)->add_handshake(handshake);
}
std::vector<char> msg;
bencode(std::back_inserter(msg), handshake);
// make room for message
buffer::interval i = allocate_send_buffer(6 + msg.size());
// write the length of the message
detail::write_int32((int)msg.size() + 2, i.begin);
detail::write_uint8(msg_extended, i.begin);
// signal handshake message
detail::write_uint8(0, i.begin);
std::copy(msg.begin(), msg.end(), i.begin);
i.begin += msg.size();
TORRENT_ASSERT(i.begin == i.end);
#ifdef TORRENT_VERBOSE_LOGGING
std::stringstream ext;
handshake.print(ext);
(*m_logger) << "==> EXTENDED HANDSHAKE: \n" << ext.str();
#endif
setup_send();
}
#endif
void bt_peer_connection::write_choke()
{
INVARIANT_CHECK;
TORRENT_ASSERT(m_sent_handshake && m_sent_bitfield);
if (is_choked()) return;
char msg[] = {0,0,0,1,msg_choke};
send_buffer(msg, sizeof(msg));
}
void bt_peer_connection::write_unchoke()
{
INVARIANT_CHECK;
TORRENT_ASSERT(m_sent_handshake && m_sent_bitfield);
char msg[] = {0,0,0,1,msg_unchoke};
send_buffer(msg, sizeof(msg));
}
void bt_peer_connection::write_interested()
{
INVARIANT_CHECK;
TORRENT_ASSERT(m_sent_handshake && m_sent_bitfield);
char msg[] = {0,0,0,1,msg_interested};
send_buffer(msg, sizeof(msg));
}
void bt_peer_connection::write_not_interested()
{
INVARIANT_CHECK;
TORRENT_ASSERT(m_sent_handshake && m_sent_bitfield);
char msg[] = {0,0,0,1,msg_not_interested};
send_buffer(msg, sizeof(msg));
}
void bt_peer_connection::write_have(int index)
{
INVARIANT_CHECK;
TORRENT_ASSERT(associated_torrent().lock()->valid_metadata());
TORRENT_ASSERT(index >= 0);
TORRENT_ASSERT(index < associated_torrent().lock()->torrent_file().num_pieces());
TORRENT_ASSERT(m_sent_handshake && m_sent_bitfield);
char msg[] = {0,0,0,5,msg_have,0,0,0,0};
char* ptr = msg + 5;
detail::write_int32(index, ptr);
send_buffer(msg, sizeof(msg));
}
void bt_peer_connection::write_piece(peer_request const& r, char* buffer)
{
INVARIANT_CHECK;
TORRENT_ASSERT(m_sent_handshake && m_sent_bitfield);
boost::shared_ptr<torrent> t = associated_torrent().lock();
TORRENT_ASSERT(t);
char msg[4 + 1 + 4 + 4];
char* ptr = msg;
TORRENT_ASSERT(r.length <= 16 * 1024);
detail::write_int32(r.length + 1 + 4 + 4, ptr);
detail::write_uint8(msg_piece, ptr);
detail::write_int32(r.piece, ptr);
detail::write_int32(r.start, ptr);
send_buffer(msg, sizeof(msg));
append_send_buffer(buffer, r.length
, boost::bind(&session_impl::free_disk_buffer
, boost::ref(m_ses), _1));
m_payloads.push_back(range(send_buffer_size() - r.length, r.length));
setup_send();
}
namespace
{
struct match_peer_id
{
match_peer_id(peer_id const& id, peer_connection const* pc)
: m_id(id), m_pc(pc)
{ TORRENT_ASSERT(pc); }
bool operator()(std::pair<const address, policy::peer> const& p) const
{
return p.second.connection != m_pc
&& p.second.connection
&& p.second.connection->pid() == m_id
&& !p.second.connection->pid().is_all_zeros()
&& p.second.ip.address() == m_pc->remote().address();
}
peer_id const& m_id;
peer_connection const* m_pc;
};
}
// --------------------------
// RECEIVE DATA
// --------------------------
// throws exception when the client should be disconnected
void bt_peer_connection::on_receive(asio::error_code const& error
, std::size_t bytes_transferred)
{
INVARIANT_CHECK;
if (error) return;
boost::shared_ptr<torrent> t = associated_torrent().lock();
if (in_handshake())
m_statistics.received_bytes(0, bytes_transferred);
#ifndef TORRENT_DISABLE_ENCRYPTION
TORRENT_ASSERT(in_handshake() || !m_rc4_encrypted || m_encrypted);
if (m_rc4_encrypted && m_encrypted)
{
buffer::interval wr_buf = wr_recv_buffer();
m_RC4_handler->decrypt((wr_buf.end - bytes_transferred), bytes_transferred);
}
#endif
buffer::const_interval recv_buffer = receive_buffer();
#ifndef TORRENT_DISABLE_ENCRYPTION
// m_state is set to read_pe_dhkey in initial state
// (read_protocol_identifier) for incoming, or in constructor
// for outgoing
if (m_state == read_pe_dhkey)
{
assert (!m_encrypted);
assert (!m_rc4_encrypted);
assert (packet_size() == dh_key_len);
assert (recv_buffer == receive_buffer());
if (!packet_finished()) return;
// write our dh public key. m_DH_key_exchange is
// initialized in write_pe1_2_dhkey()
if (!is_local())
write_pe1_2_dhkey();
// read dh key, generate shared secret
m_DH_key_exchange->compute_secret (recv_buffer.begin); // TODO handle errors
#ifdef TORRENT_VERBOSE_LOGGING
(*m_logger) << " received DH key\n";
#endif
// PadA/B can be a max of 512 bytes, and 20 bytes more for
// the sync hash (if incoming), or 8 bytes more for the
// encrypted verification constant (if outgoing). Instead
// of requesting the maximum possible, request the maximum
// possible to ensure we do not overshoot the standard
// handshake.
if (is_local())
{
m_state = read_pe_syncvc;
write_pe3_sync();
// initial payload is the standard handshake, this is
// always rc4 if sent here. m_rc4_encrypted is flagged
// again according to peer selection.
m_rc4_encrypted = true;
m_encrypted = true;
write_handshake();
m_rc4_encrypted = false;
m_encrypted = false;
// vc,crypto_select,len(pad),pad, encrypt(handshake)
// 8+4+2+0+handshake_len
reset_recv_buffer(8+4+2+0+handshake_len);
}
else
{
// already written dh key
m_state = read_pe_synchash;
// synchash,skeyhash,vc,crypto_provide,len(pad),pad,encrypt(handshake)
reset_recv_buffer(20+20+8+4+2+0+handshake_len);
}
TORRENT_ASSERT(!packet_finished());
return;
}
// cannot fall through into
if (m_state == read_pe_synchash)
{
TORRENT_ASSERT(!m_encrypted);
TORRENT_ASSERT(!m_rc4_encrypted);
TORRENT_ASSERT(!is_local());
TORRENT_ASSERT(recv_buffer == receive_buffer());
if (recv_buffer.left() < 20)
{
if (packet_finished())
{
throw protocol_error ("sync hash not found");
}
// else
return;
}
if (!m_sync_hash.get())
{
TORRENT_ASSERT(m_sync_bytes_read == 0);
hasher h;
// compute synchash (hash('req1',S))
h.update("req1", 4);
h.update(m_DH_key_exchange->get_secret(), dh_key_len);
m_sync_hash.reset(new sha1_hash(h.final()));
}
int syncoffset = get_syncoffset((char*)m_sync_hash->begin(), 20
, recv_buffer.begin, recv_buffer.left());
// No sync
if (syncoffset == -1)
{
std::size_t bytes_processed = recv_buffer.left() - 20;
m_sync_bytes_read += bytes_processed;
if (m_sync_bytes_read >= 512)
throw protocol_error("sync hash not found within 532 bytes");
cut_receive_buffer(bytes_processed, (std::min)(packet_size(), (512+20) - m_sync_bytes_read));
TORRENT_ASSERT(!packet_finished());
return;
}
// found complete sync
else
{
std::size_t bytes_processed = syncoffset + 20;
#ifdef TORRENT_VERBOSE_LOGGING
(*m_logger) << " sync point (hash) found at offset "
<< m_sync_bytes_read + bytes_processed - 20 << "\n";
#endif
m_state = read_pe_skey_vc;
// skey,vc - 28 bytes
m_sync_hash.reset();
cut_receive_buffer(bytes_processed, 28);
}
}
if (m_state == read_pe_skey_vc)
{
TORRENT_ASSERT(!m_encrypted);
TORRENT_ASSERT(!m_rc4_encrypted);
TORRENT_ASSERT(!is_local());
TORRENT_ASSERT(packet_size() == 28);
if (!packet_finished()) return;
recv_buffer = receive_buffer();
// only calls info_hash() on the torrent_handle's, which
// never throws.
session_impl::mutex_t::scoped_lock l(m_ses.m_mutex);
std::vector<torrent_handle> active_torrents = m_ses.get_torrents();
std::vector<torrent_handle>::const_iterator i;
hasher h;
sha1_hash skey_hash, obfs_hash;
for (i = active_torrents.begin(); i != active_torrents.end(); ++i)
{
torrent_handle const& t_h = *i; // TODO possible errors
sha1_hash const& info_hash = t_h.info_hash();
// TODO Does info_hash need to be checked for validity?
h.reset();
h.update("req2", 4);
h.update((char*)info_hash.begin(), 20);
skey_hash = h.final();
h.reset();
h.update("req3", 4);
h.update(m_DH_key_exchange->get_secret(), dh_key_len);
obfs_hash = h.final();
obfs_hash ^= skey_hash;
if (std::equal (recv_buffer.begin, recv_buffer.begin + 20,
(char*)obfs_hash.begin()))
{
if (!t)
{
attach_to_torrent(info_hash);
t = associated_torrent().lock();
TORRENT_ASSERT(t);
}
init_pe_RC4_handler(m_DH_key_exchange->get_secret(), info_hash);
#ifdef TORRENT_VERBOSE_LOGGING
(*m_logger) << " stream key found, torrent located.\n";
#endif
continue; // TODO Check flow control with multiple torrents
}
}
if (!m_RC4_handler.get())
throw protocol_error("invalid streamkey identifier (info hash) in encrypted handshake");
// verify constant
buffer::interval wr_recv_buf = wr_recv_buffer();
m_RC4_handler->decrypt(wr_recv_buf.begin + 20, 8);
wr_recv_buf.begin += 28;
const char sh_vc[] = {0,0,0,0, 0,0,0,0};
if (!std::equal(sh_vc, sh_vc+8, recv_buffer.begin + 20))
{
throw protocol_error("unable to verify constant");
}
#ifdef TORRENT_VERBOSE_LOGGING
(*m_logger) << " verification constant found\n";
#endif
m_state = read_pe_cryptofield;
reset_recv_buffer(4 + 2);
}
// cannot fall through into
if (m_state == read_pe_syncvc)
{
TORRENT_ASSERT(is_local());
TORRENT_ASSERT(!m_encrypted);
TORRENT_ASSERT(!m_rc4_encrypted);
TORRENT_ASSERT(recv_buffer == receive_buffer());
if (recv_buffer.left() < 8)
{
if (packet_finished())
{
throw protocol_error ("sync verification constant not found");
}
// else
return;
}
// generate the verification constant
if (!m_sync_vc.get())
{
TORRENT_ASSERT(m_sync_bytes_read == 0);
m_sync_vc.reset (new char[8]);
std::fill(m_sync_vc.get(), m_sync_vc.get() + 8, 0);
m_RC4_handler->decrypt(m_sync_vc.get(), 8);
}
TORRENT_ASSERT(m_sync_vc.get());
int syncoffset = get_syncoffset(m_sync_vc.get(), 8
, recv_buffer.begin, recv_buffer.left());
// No sync
if (syncoffset == -1)
{
std::size_t bytes_processed = recv_buffer.left() - 8;
m_sync_bytes_read += bytes_processed;
if (m_sync_bytes_read >= 512)
throw protocol_error("sync verification constant not found within 520 bytes");
cut_receive_buffer(bytes_processed, (std::min)(packet_size(), (512+8) - m_sync_bytes_read));
TORRENT_ASSERT(!packet_finished());
return;
}
// found complete sync
else
{
std::size_t bytes_processed = syncoffset + 8;
#ifdef TORRENT_VERBOSE_LOGGING
(*m_logger) << " sync point (verification constant) found at offset "
<< m_sync_bytes_read + bytes_processed - 8 << "\n";
#endif
cut_receive_buffer (bytes_processed, 4 + 2);
// delete verification constant
m_sync_vc.reset();
m_state = read_pe_cryptofield;
// fall through
}
}
if (m_state == read_pe_cryptofield) // local/remote
{
TORRENT_ASSERT(!m_encrypted);
TORRENT_ASSERT(!m_rc4_encrypted);
TORRENT_ASSERT(packet_size() == 4+2);
if (!packet_finished()) return;
buffer::interval wr_buf = wr_recv_buffer();
m_RC4_handler->decrypt(wr_buf.begin, packet_size());
recv_buffer = receive_buffer();
int crypto_field = detail::read_int32(recv_buffer.begin);
#ifdef TORRENT_VERBOSE_LOGGING
if (!is_local())
(*m_logger) << " crypto provide : [ ";
else
(*m_logger) << " crypto select : [ ";
if (crypto_field & 0x01)
(*m_logger) << "plaintext ";
if (crypto_field & 0x02)
(*m_logger) << "rc4 ";
(*m_logger) << "]\n";
#endif
if (!is_local())
{
int crypto_select = 0;
// select a crypto method
switch (m_ses.get_pe_settings().allowed_enc_level)
{
case (pe_settings::plaintext):
{
if (!(crypto_field & 0x01))
throw protocol_error("plaintext not provided");
crypto_select = 0x01;
}
break;
case (pe_settings::rc4):
{
if (!(crypto_field & 0x02))
throw protocol_error("rc4 not provided");
crypto_select = 0x02;
}
break;
case (pe_settings::both):
{
if (m_ses.get_pe_settings().prefer_rc4)
{
if (crypto_field & 0x02)
crypto_select = 0x02;
else if (crypto_field & 0x01)
crypto_select = 0x01;
}
else
{
if (crypto_field & 0x01)
crypto_select = 0x01;
else if (crypto_field & 0x02)
crypto_select = 0x02;
}
if (!crypto_select)
throw protocol_error("rc4/plaintext not provided");
}
} // switch
// write the pe4 step
write_pe4_sync(crypto_select);
}
else // is_local()
{
// check if crypto select is valid
pe_settings::enc_level const& allowed_enc_level = m_ses.get_pe_settings().allowed_enc_level;
if (crypto_field == 0x02)
{
if (allowed_enc_level == pe_settings::plaintext)
throw protocol_error("rc4 selected by peer when not provided");
m_rc4_encrypted = true;
}
else if (crypto_field == 0x01)
{
if (allowed_enc_level == pe_settings::rc4)
throw protocol_error("plaintext selected by peer when not provided");
m_rc4_encrypted = false;
}
else
throw protocol_error("unsupported crypto method selected by peer");
}
int len_pad = detail::read_int16(recv_buffer.begin);
if (len_pad < 0 || len_pad > 512)
throw protocol_error("invalid pad length");
m_state = read_pe_pad;
if (!is_local())
reset_recv_buffer(len_pad + 2); // len(IA) at the end of pad
else
{
if (len_pad == 0)
{
m_encrypted = true;
m_state = init_bt_handshake;
}
else
reset_recv_buffer(len_pad);
}
}
if (m_state == read_pe_pad)
{
TORRENT_ASSERT(!m_encrypted);
if (!packet_finished()) return;
int pad_size = is_local() ? packet_size() : packet_size() - 2;
buffer::interval wr_buf = wr_recv_buffer();
m_RC4_handler->decrypt(wr_buf.begin, packet_size());
recv_buffer = receive_buffer();
if (!is_local())
{
recv_buffer.begin += pad_size;
int len_ia = detail::read_int16(recv_buffer.begin);
if (len_ia < 0) throw protocol_error("invalid len_ia in handshake");
#ifdef TORRENT_VERBOSE_LOGGING
(*m_logger) << " len(IA) : " << len_ia << "\n";
#endif
if (len_ia == 0)
{
// everything after this is Encrypt2
m_encrypted = true;
m_state = init_bt_handshake;
}
else
{
m_state = read_pe_ia;
reset_recv_buffer(len_ia);
}
}
else // is_local()
{
// everything that arrives after this is Encrypt2
m_encrypted = true;
m_state = init_bt_handshake;
}
}
if (m_state == read_pe_ia)
{
TORRENT_ASSERT(!is_local());
TORRENT_ASSERT(!m_encrypted);
if (!packet_finished()) return;
// ia is always rc4, so decrypt it
buffer::interval wr_buf = wr_recv_buffer();
m_RC4_handler->decrypt(wr_buf.begin, packet_size());
#ifdef TORRENT_VERBOSE_LOGGING
(*m_logger) << " decrypted ia : " << packet_size() << " bytes\n";
#endif
if (!m_rc4_encrypted)
{
m_RC4_handler.reset();
#ifdef TORRENT_VERBOSE_LOGGING
(*m_logger) << " destroyed rc4 keys\n";
#endif
}
// everything that arrives after this is Encrypt2
m_encrypted = true;
m_state = read_protocol_identifier;
cut_receive_buffer(0, 20);
}
if (m_state == init_bt_handshake)
{
TORRENT_ASSERT(m_encrypted);
// decrypt remaining received bytes
if (m_rc4_encrypted)
{
buffer::interval wr_buf = wr_recv_buffer();
wr_buf.begin += packet_size();
m_RC4_handler->decrypt(wr_buf.begin, wr_buf.left());
#ifdef TORRENT_VERBOSE_LOGGING
(*m_logger) << " decrypted remaining " << wr_buf.left() << " bytes\n";
#endif
}
else // !m_rc4_encrypted
{
m_RC4_handler.reset();
#ifdef TORRENT_VERBOSE_LOGGING
(*m_logger) << " destroyed rc4 keys\n";
#endif
}
// payload stream, start with 20 handshake bytes
m_state = read_protocol_identifier;
reset_recv_buffer(20);
// encrypted portion of handshake completed, toggle
// peer_info pe_support flag back to true
if (is_local() &&
m_ses.get_pe_settings().out_enc_policy == pe_settings::enabled)
{
policy::peer* pi = peer_info_struct();
TORRENT_ASSERT(pi);
pi->pe_support = true;
}
}
#endif // #ifndef TORRENT_DISABLE_ENCRYPTION
if (m_state == read_protocol_identifier)
{
assert (packet_size() == 20);
if (!packet_finished()) return;
recv_buffer = receive_buffer();
int packet_size = recv_buffer[0];
const char protocol_string[] = "BitTorrent protocol";
if (packet_size != 19 ||
!std::equal(recv_buffer.begin + 1, recv_buffer.begin + 19, protocol_string))
{
#ifndef TORRENT_DISABLE_ENCRYPTION
if (!is_local() && m_ses.get_pe_settings().in_enc_policy == pe_settings::disabled)
throw protocol_error("encrypted incoming connections disabled");
// Don't attempt to perform an encrypted handshake
// within an encrypted connection
if (!m_encrypted && !is_local())
{
#ifdef TORRENT_VERBOSE_LOGGING
(*m_logger) << " attempting encrypted connection\n";
#endif
m_state = read_pe_dhkey;
cut_receive_buffer(0, dh_key_len);
TORRENT_ASSERT(!packet_finished());
return;
}
assert ((!is_local() && m_encrypted) || is_local());
#endif // #ifndef TORRENT_DISABLE_ENCRYPTION
throw protocol_error("incorrect protocol identifier");
}
#ifndef TORRENT_DISABLE_ENCRYPTION
assert (m_state != read_pe_dhkey);
if (!is_local() &&
(m_ses.get_pe_settings().in_enc_policy == pe_settings::forced) &&
!m_encrypted)
throw protocol_error("non encrypted incoming connections disabled");
#endif
#ifdef TORRENT_VERBOSE_LOGGING
(*m_logger) << " BitTorrent protocol\n";
#endif
m_state = read_info_hash;
reset_recv_buffer(28);
}
// fall through
if (m_state == read_info_hash)
{
TORRENT_ASSERT(packet_size() == 28);
if (!packet_finished()) return;
recv_buffer = receive_buffer();
#ifdef TORRENT_VERBOSE_LOGGING
for (int i=0; i < 8; ++i)
{
for (int j=0; j < 8; ++j)
{
if (recv_buffer[i] & (0x80 >> j)) (*m_logger) << "1";
else (*m_logger) << "0";
}
}
(*m_logger) << "\n";
if (recv_buffer[7] & 0x01)
(*m_logger) << "supports DHT port message\n";
if (recv_buffer[7] & 0x04)
(*m_logger) << "supports FAST extensions\n";
if (recv_buffer[5] & 0x10)
(*m_logger) << "supports extensions protocol\n";
#endif
#ifndef DISABLE_EXTENSIONS
if ((recv_buffer[5] & 0x10))
m_supports_extensions = true;
#endif
if (recv_buffer[7] & 0x01)
m_supports_dht_port = true;
if (recv_buffer[7] & 0x04)
m_supports_fast = true;
// ok, now we have got enough of the handshake. Is this connection
// attached to a torrent?
if (!t)
{
// now, we have to see if there's a torrent with the
// info_hash we got from the peer
sha1_hash info_hash;
std::copy(recv_buffer.begin + 8, recv_buffer.begin + 28
, (char*)info_hash.begin());
attach_to_torrent(info_hash);
}
else
{
// verify info hash
if (!std::equal(recv_buffer.begin + 8, recv_buffer.begin + 28
, (const char*)t->torrent_file().info_hash().begin()))
{
#ifdef TORRENT_VERBOSE_LOGGING
(*m_logger) << " received invalid info_hash\n";
#endif
throw protocol_error("invalid info-hash in handshake");
}
#ifdef TORRENT_VERBOSE_LOGGING
(*m_logger) << " info_hash received\n";
#endif
}
t = associated_torrent().lock();
TORRENT_ASSERT(t);
// if this is a local connection, we have already
// sent the handshake
if (!is_local()) write_handshake();
// if (t->valid_metadata())
// write_bitfield(t->pieces());
TORRENT_ASSERT(t->get_policy().has_connection(this));
m_state = read_peer_id;
reset_recv_buffer(20);
}
// fall through
if (m_state == read_peer_id)
{
if (!t)
{
TORRENT_ASSERT(!packet_finished()); // TODO
return;
}
TORRENT_ASSERT(packet_size() == 20);
if (!packet_finished()) return;
recv_buffer = receive_buffer();
#ifdef TORRENT_VERBOSE_LOGGING
{
peer_id tmp;
std::copy(recv_buffer.begin, recv_buffer.begin + 20, (char*)tmp.begin());
std::stringstream s;
s << "received peer_id: " << tmp << " client: " << identify_client(tmp) << "\n";
s << "as ascii: ";
for (peer_id::iterator i = tmp.begin(); i != tmp.end(); ++i)
{
if (std::isprint(*i)) s << *i;
else s << ".";
}
s << "\n";
(*m_logger) << s.str();
}
#endif
peer_id pid;
std::copy(recv_buffer.begin, recv_buffer.begin + 20, (char*)pid.begin());
set_pid(pid);
if (t->settings().allow_multiple_connections_per_ip)
{
// now, let's see if this connection should be closed
policy& p = t->get_policy();
policy::iterator i = std::find_if(p.begin_peer(), p.end_peer()
, match_peer_id(pid, this));
if (i != p.end_peer())
{
TORRENT_ASSERT(i->second.connection->pid() == pid);
// we found another connection with the same peer-id
// which connection should be closed in order to be
// sure that the other end closes the same connection?
// the peer with greatest peer-id is the one allowed to
// initiate connections. So, if our peer-id is greater than
// the others, we should close the incoming connection,
// if not, we should close the outgoing one.
if (pid < m_ses.get_peer_id() && is_local())
{
i->second.connection->disconnect();
}
else
{
throw protocol_error("duplicate peer-id, connection closed");
}
}
}
if (pid == m_ses.get_peer_id())
{
throw protocol_error("closing connection to ourself");
}
m_client_version = identify_client(pid);
boost::optional<fingerprint> f = client_fingerprint(pid);
if (f && std::equal(f->name, f->name + 2, "BC"))
{
// if this is a bitcomet client, lower the request queue size limit
if (m_max_out_request_queue > 50) m_max_out_request_queue = 50;
}
// disconnect if the peer has the same peer-id as ourself
// since it most likely is ourself then
if (pid == m_ses.get_peer_id())
throw std::runtime_error("closing connection to ourself");
#ifndef TORRENT_DISABLE_EXTENSIONS
for (extension_list_t::iterator i = m_extensions.begin()
, end(m_extensions.end()); i != end;)
{
if (!(*i)->on_handshake())
{
i = m_extensions.erase(i);
}
else
{
++i;
}
}
if (m_supports_extensions) write_extensions();
#endif
#ifdef TORRENT_VERBOSE_LOGGING
(*m_logger) << time_now_string() << " <== HANDSHAKE\n";
#endif
// consider this a successful connection, reset the failcount
if (peer_info_struct()) peer_info_struct()->failcount = 0;
#ifndef TORRENT_DISABLE_ENCRYPTION
// Toggle pe_support back to false if this is a
// standard successful connection
if (is_local() && !m_encrypted &&
m_ses.get_pe_settings().out_enc_policy == pe_settings::enabled)
{
policy::peer* pi = peer_info_struct();
TORRENT_ASSERT(pi);
pi->pe_support = false;
}
#endif
m_state = read_packet_size;
reset_recv_buffer(4);
if (t->valid_metadata())
{
write_bitfield(t->pieces());
#ifndef TORRENT_DISABLE_DHT
if (m_supports_dht_port && m_ses.m_dht)
write_dht_port(m_ses.get_dht_settings().service_port);
#endif
}
TORRENT_ASSERT(!packet_finished());
return;
}
// cannot fall through into
if (m_state == read_packet_size)
{
// Make sure this is not fallen though into
assert (recv_buffer == receive_buffer());
if (!t) return;
m_statistics.received_bytes(0, bytes_transferred);
if (!packet_finished()) return;
const char* ptr = recv_buffer.begin;
int packet_size = detail::read_int32(ptr);
// don't accept packets larger than 1 MB
if (packet_size > 1024*1024 || packet_size < 0)
{
// packet too large
throw std::runtime_error("packet > 1 MB ("
+ boost::lexical_cast<std::string>(
(unsigned int)packet_size) + " bytes)");
}
if (packet_size == 0)
{
incoming_keepalive();
// keepalive message
m_state = read_packet_size;
reset_recv_buffer(4);
}
else
{
m_state = read_packet;
reset_recv_buffer(packet_size);
}
TORRENT_ASSERT(!packet_finished());
return;
}
if (m_state == read_packet)
{
TORRENT_ASSERT(recv_buffer == receive_buffer());
if (!t) return;
if (dispatch_message(bytes_transferred))
{
m_state = read_packet_size;
reset_recv_buffer(4);
}
TORRENT_ASSERT(!packet_finished());
return;
}
TORRENT_ASSERT(!packet_finished());
}
// --------------------------
// SEND DATA
// --------------------------
// throws exception when the client should be disconnected
void bt_peer_connection::on_sent(asio::error_code const& error
, std::size_t bytes_transferred)
{
INVARIANT_CHECK;
if (error) return;
// manage the payload markers
int amount_payload = 0;
if (!m_payloads.empty())
{
for (std::deque<range>::iterator i = m_payloads.begin();
i != m_payloads.end(); ++i)
{
i->start -= bytes_transferred;
if (i->start < 0)
{
if (i->start + i->length <= 0)
{
amount_payload += i->length;
}
else
{
amount_payload += -i->start;
i->length -= -i->start;
i->start = 0;
}
}
}
}
// TODO: move the erasing into the loop above
// remove all payload ranges that has been sent
m_payloads.erase(
std::remove_if(m_payloads.begin(), m_payloads.end(), range_below_zero)
, m_payloads.end());
TORRENT_ASSERT(amount_payload <= (int)bytes_transferred);
m_statistics.sent_bytes(amount_payload, bytes_transferred - amount_payload);
}
#ifndef NDEBUG
void bt_peer_connection::check_invariant() const
{
#ifndef TORRENT_DISABLE_ENCRYPTION
TORRENT_ASSERT( (bool(m_state != read_pe_dhkey) || m_DH_key_exchange.get())
|| !is_local());
TORRENT_ASSERT(!m_rc4_encrypted || m_RC4_handler.get());
#endif
if (!in_handshake())
{
TORRENT_ASSERT(m_sent_handshake);
}
if (!m_in_constructor)
peer_connection::check_invariant();
if (!m_payloads.empty())
{
for (std::deque<range>::const_iterator i = m_payloads.begin();
i != m_payloads.end() - 1; ++i)
{
TORRENT_ASSERT(i->start + i->length <= (i+1)->start);
}
}
}
#endif
}
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