I2P: crash while seeding in mixed mode

[Vort]

Sometimes when torrents are seeding, assertion failure happens.
I was able to reproduce it with such settings and with 5 torrents seeding:
--allow_i2p_mixed=true --i2p_hostname=127.0.0.1 --i2p_port=7656 --i2p_inbound_quantity=8 --i2p_outbound_quantity=8 --i2p_inbound_length=1 --i2p_outbound_length=1
Most likely, mixed mode is important for reproduction and quantity/length are not, but who knows - bug happens randomly.

It happens on this line:

libtorrent/src/hasher.cpp

Line 216 in 96d055b

TORRENT_ASSERT(!data.empty());

libtorrent::assert_fail assert.cpp:362
libtorrent::lcrypto::hasher256::update hasher.cpp:216
libtorrent::lcrypto::hasher256::hasher256 hasher.cpp:181
libtorrent::bt_peer_connection::get_specific_peer_info bt_peer_connection.cpp:496
libtorrent::peer_connection::get_peer_info peer_connection.cpp:4613
libtorrent::torrent::get_peer_info torrent.cpp:7267
libtorrent::torrent::post_peer_info torrent.cpp:7274
libtorrent::torrent_handle::async_call<void (libtorrent::torrent::*)()>(void (libtorrent::torrent::*)()) const::{lambda()#1}::operator()() const torrent_handle.cpp:130
boost::asio::detail::binder0<libtorrent::torrent_handle::async_call<void (libtorrent::torrent::*)()>(void (libtorrent::torrent::*)()) const::{lambda()#1}>::operator()() bind_handler.hpp:60
boost_asio_handler_invoke_helpers::invoke<boost::asio::detail::binder0<libtorrent::torrent_handle::async_call<void (libtorrent::torrent::*)()>(void (libtorrent::torrent::*)()) const::{lambda()#1}>, boost::asio::detail::binder0<libtorrent::torrent_handle::async_call<void (libtorrent::torrent::*)()>(void (libtorrent::torrent::*)()) const::{lambda()#1}> >(boost::asio::detail::binder0<libtorrent::torrent_handle::async_call<void (libtorrent::torrent::*)()>(void (libtorrent::torrent::*)()) const::{lambda()#1}>&, boost::asio::detail::binder0<libtorrent::torrent_handle::async_call<void (libtorrent::torrent::*)()>(void (libtorrent::torrent::*)()) const::{lambda()#1}>&) handler_invoke_helpers.hpp:51
boost::asio::detail::executor_op<boost::asio::detail::binder0<libtorrent::torrent_handle::async_call<void (libtorrent::torrent::*)()>(void (libtorrent::torrent::*)()) const::{lambda()#1}>, std::__1::allocator<void>, boost::asio::detail::win_iocp_operation>::do_complete(void*, boost::asio::detail::win_iocp_operation*, boost::system::error_code const&, unsigned long long) executor_op.hpp:70
boost::asio::detail::win_iocp_operation::complete win_iocp_operation.hpp:47
boost::asio::detail::win_iocp_io_context::do_one win_iocp_io_context.ipp:473
boost::asio::detail::win_iocp_io_context::run win_iocp_io_context.ipp:204
boost::asio::io_context::run io_context.ipp:63
libtorrent::session::start(libtorrent::flags::bitfield_flag<unsigned char, libtorrent::session_flags_tag, void>, libtorrent::session_params&&, boost::asio::io_context*)::$_0::operator()() const session.cpp:344
std::__1::__invoke[abi:v15007]<libtorrent::session::start(libtorrent::flags::bitfield_flag<unsigned char, libtorrent::session_flags_tag, void>, libtorrent::session_params&&, boost::asio::io_context*)::$_0>(libtorrent::session::start(libtorrent::flags::bitfield_flag<unsigned char, libtorrent::session_flags_tag, void>, libtorrent::session_params&&, boost::asio::io_context*)::$_0&&) invoke.h:394
std::__1::__thread_execute[abi:v15007]<std::__1::unique_ptr<std::__1::__thread_struct, std::__1::default_delete<std::__1::__thread_struct> >, libtorrent::session::start(libtorrent::flags::bitfield_flag<unsigned char, libtorrent::session_flags_tag, void>, libtorrent::session_params&&, boost::asio::io_context*)::$_0>(std::__1::tuple<std::__1::unique_ptr<std::__1::__thread_struct, std::__1::default_delete<std::__1::__thread_struct> >, libtorrent::session::start(libtorrent::flags::bitfield_flag<unsigned char, libtorrent::session_flags_tag, void>, libtorrent::session_params&&, boost::asio::io_context*)::$_0>&, std::__1::__tuple_indices<>) thread:284
std::__1::__thread_proxy[abi:v15007]<std::__1::tuple<std::__1::unique_ptr<std::__1::__thread_struct, std::__1::default_delete<std::__1::__thread_struct> >, libtorrent::session::start(libtorrent::flags::bitfield_flag<unsigned char, libtorrent::session_flags_tag, void>, libtorrent::session_params&&, boost::asio::io_context*)::$_0> >(void*) thread:295
ucrtbase!_crt_at_quick_exit 0x000007fef5c5be1d
KERNEL32!BaseThreadInitThunk 0x00000000770f55dd
ntdll!RtlUserThreadStart 0x0000000077352b1d

libtorrent version (or branch): 96d055b + #7354
platform/architecture: Windows x64
compiler and compiler version: clang 15.0.7

[arvidn]

it looks like the destination address of the peer is an empty string. which is unexpected

[arvidn]

could you try this? #7390

[arvidn]

@Vort thanks for your report and analysis. I have a new patch in the works.

[arvidn]

#7392

I don't think the mixed-mode makes a difference. As far as I can tell, just any incoming i2p connections were a problem.

[Vort]

I don't think the mixed-mode makes a difference. As far as I can tell, just any incoming i2p connections were a problem.

After I found mismatch between object types (ipv4_peer / i2p_peer), I also thought that mixed mode should not make difference.
However I made additional tests and they showed that without mixed mode there was no crash for many hours, when with mixed mode crash happened in ~10-30 minutes.
Maybe it is just "luck", maybe some unaccounted factors exists.
However it looks like there are no much sense in trying figuring it out now.
Instead I will just test #7392 and post additional message when I will have some results.

[Vort]

Solved with #7392. Thanks.