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transmission/tests/libtransmission/handshake-test.cc
reardonia 50eacf6933 Consume early pad a/b, improve handshake tests (#6987) 
* properly consume PadA in MSE handshake, check for invalid Ya+PadA

* refactor: make handshake constants public (needed for test coverage)

* test: split test MSE handshakes by blocking steps

* test: use `ASSERT_TRUE` instead of `assert`

* test: fix windows crash by using `recv` and `send`

Co-authored-by: Yat Ho <46261767+tearfur@users.noreply.github.com>

* refactor: use `TR_IF_WIN32` for `LOCAL_SOCKETPAIR_AF`

Co-authored-by: Yat Ho <46261767+tearfur@users.noreply.github.com>

---------

Co-authored-by: Yat Ho <lagoho7@gmail.com>
Co-authored-by: reardonia <reardonia@github.com>
Co-authored-by: Yat Ho <46261767+tearfur@users.noreply.github.com>
2025-01-09 10:26:48 -06:00

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// This file Copyright (C) 2022 Mnemosyne LLC.
// It may be used under GPLv2 (SPDX: GPL-2.0-only), GPLv3 (SPDX: GPL-3.0-only),
// or any future license endorsed by Mnemosyne LLC.
// License text can be found in the licenses/ folder.
#include <algorithm>
#include <array>
#include <cerrno>
#include <cstddef> // size_t, std::byte
#include <cstdint> // uint8_t
#include <map>
#include <memory>
#include <optional>
#include <string_view>
#include <utility>
#ifdef _WIN32
#include <ws2tcpip.h>
#else
#include <sys/socket.h>
#include <unistd.h> // write()
#endif
#include <event2/util.h>
#include <libtransmission/transmission.h>
#include <libtransmission/crypto-utils.h> // tr_sha1_to_string, tr_base...
#include <libtransmission/handshake.h>
#include <libtransmission/net.h>
#include <libtransmission/peer-io.h>
#include <libtransmission/peer-mse.h>
#include <libtransmission/peer-socket.h>
#include <libtransmission/session.h> // tr_peerIdInit()
#include <libtransmission/timer.h>
#include <libtransmission/tr-assert.h>
#include <libtransmission/tr-macros.h>
#include <libtransmission/utils.h>
#include "gtest/gtest.h"
#include "test-fixtures.h"
using namespace std::literals;
#define LOCAL_SOCKETPAIR_AF TR_IF_WIN32(AF_INET, AF_UNIX)
namespace libtransmission::test
{
auto constexpr MaxWaitMsec = 5000;
class HandshakeTest : public SessionTest
{
public:
class MediatorMock final : public tr_handshake::Mediator
{
public:
explicit MediatorMock(tr_session* session)
: session_{ session }
{
}
[[nodiscard]] std::optional<TorrentInfo> torrent(tr_sha1_digest_t const& info_hash) const override
{
if (auto const iter = torrents.find(info_hash); iter != std::end(torrents))
{
return iter->second;
}
return {};
}
[[nodiscard]] std::optional<TorrentInfo> torrent_from_obfuscated(tr_sha1_digest_t const& obfuscated) const override
{
for (auto const& [info_hash, info] : torrents)
{
if (obfuscated == tr_sha1::digest("req2"sv, info.info_hash))
{
return info;
}
}
return {};
}
[[nodiscard]] libtransmission::TimerMaker& timer_maker() override
{
return session_->timerMaker();
}
[[nodiscard]] bool allows_dht() const override
{
return false;
}
[[nodiscard]] bool allows_tcp() const override
{
return true;
}
[[nodiscard]] size_t pad(void* setme, [[maybe_unused]] size_t maxlen) const override
{
TR_ASSERT(maxlen > 10);
auto const len = size_t{ 10 };
std::fill_n(static_cast<char*>(setme), 10, ' ');
return len;
}
[[nodiscard]] tr_message_stream_encryption::DH::private_key_bigend_t private_key() const override
{
return private_key_;
}
void set_utp_failed(tr_sha1_digest_t const& /*info_hash*/, tr_socket_address const& /*socket_address*/) override
{
}
void setPrivateKeyFromBase64(std::string_view b64)
{
auto const str = tr_base64_decode(b64);
TR_ASSERT(std::size(str) == std::size(private_key_));
std::copy_n(reinterpret_cast<std::byte const*>(std::data(str)), std::size(str), std::begin(private_key_));
}
tr_session* const session_;
std::map<tr_sha1_digest_t, TorrentInfo> torrents;
tr_message_stream_encryption::DH::private_key_bigend_t private_key_ = {};
};
template<typename Span>
void sendToClient(evutil_socket_t sock, Span const& data)
{
auto const* walk = std::data(data);
static_assert(sizeof(*walk) == 1);
size_t len = std::size(data);
while (len > 0)
{
auto const n = send(sock, reinterpret_cast<char const*>(walk), len, 0);
TR_ASSERT(n >= 0);
len -= n;
walk += n;
}
}
void sendB64ToClient(evutil_socket_t sock, std::string_view b64)
{
sendToClient(sock, tr_base64_decode(b64));
}
static auto constexpr ReservedBytesNoExtensions = std::array<uint8_t, 8>{ 0, 0, 0, 0, 0, 0, 0, 0 };
static auto constexpr PlaintextProtocolName = "\023BitTorrent protocol"sv;
tr_socket_address const DefaultPeerSockAddr{ *tr_address::from_string("127.0.0.1"sv), tr_port::from_host(8080) };
tr_handshake::Mediator::TorrentInfo const TorrentWeAreSeeding{ tr_sha1::digest("abcde"sv),
tr_peerIdInit(),
tr_torrent_id_t{ 100 },
true /*is_done*/ };
tr_handshake::Mediator::TorrentInfo const UbuntuTorrent{ *tr_sha1_from_string("2c6b6858d61da9543d4231a71db4b1c9264b0685"sv),
tr_peerIdInit(),
tr_torrent_id_t{ 101 },
false /*is_done*/ };
auto createIncomingIo(tr_session* session)
{
auto sockpair = std::array<evutil_socket_t, 2>{ -1, -1 };
EXPECT_EQ(0, evutil_socketpair(LOCAL_SOCKETPAIR_AF, SOCK_STREAM, 0, std::data(sockpair))) << tr_strerror(errno);
EXPECT_EQ(0, evutil_make_socket_nonblocking(sockpair[0]));
EXPECT_EQ(0, evutil_make_socket_nonblocking(sockpair[1]));
return std::pair{ tr_peerIo::new_incoming(
session,
&session->top_bandwidth_,
tr_peer_socket(session, DefaultPeerSockAddr, sockpair[0])),
sockpair[1] };
}
auto createOutgoingIo(tr_session* session, tr_sha1_digest_t const& info_hash)
{
auto sockpair = std::array<evutil_socket_t, 2>{ -1, -1 };
EXPECT_EQ(0, evutil_socketpair(LOCAL_SOCKETPAIR_AF, SOCK_STREAM, 0, std::data(sockpair))) << tr_strerror(errno);
EXPECT_EQ(0, evutil_make_socket_nonblocking(sockpair[0]));
EXPECT_EQ(0, evutil_make_socket_nonblocking(sockpair[1]));
auto peer_io = tr_peerIo::create(session, &session->top_bandwidth_, &info_hash, false /*incoming*/, false /*seed*/);
peer_io->set_socket(tr_peer_socket(session, DefaultPeerSockAddr, sockpair[0]));
return std::pair{ std::move(peer_io), sockpair[1] };
}
static constexpr auto makePeerId(std::string_view sv)
{
auto peer_id = tr_peer_id_t{};
for (size_t i = 0, n = std::size(sv); i < n; ++i)
{
peer_id[i] = sv[i];
}
return peer_id;
}
static auto makeRandomPeerId()
{
auto peer_id = tr_rand_obj<tr_peer_id_t>();
auto const peer_id_prefix = "-UW110Q-"sv;
std::copy(std::begin(peer_id_prefix), std::end(peer_id_prefix), std::begin(peer_id));
return peer_id;
}
static auto startHandshake(
std::optional<tr_handshake::Result>& result,
tr_handshake::Mediator* mediator,
std::shared_ptr<tr_peerIo> const& peer_io,
tr_encryption_mode encryption_mode = TR_CLEAR_PREFERRED)
{
return tr_handshake{ mediator,
peer_io,
encryption_mode,
[&result](auto const& resin)
{
result = resin;
return true;
} };
}
};
TEST_F(HandshakeTest, incomingPlaintext)
{
auto const peer_id = makeRandomPeerId();
auto mediator = MediatorMock{ session_ };
mediator.torrents.emplace(TorrentWeAreSeeding.info_hash, TorrentWeAreSeeding);
// The simplest handshake there is. "The handshake starts with character
// nineteen (decimal) followed by the string 'BitTorrent protocol'.
// The leading character is a length prefix[.]. After the fixed headers
// come eight reserved bytes, which are all zero in all current
// implementations[.] Next comes the 20 byte sha1 hash of the bencoded
// form of the info value from the metainfo file[.] After the download
// hash comes the 20-byte peer id which is reported in tracker requests
// and contained in peer lists in tracker responses."
// https://www.bittorrent.org/beps/bep_0052.html
auto [io, sock] = createIncomingIo(session_);
sendToClient(sock, PlaintextProtocolName);
sendToClient(sock, ReservedBytesNoExtensions);
sendToClient(sock, TorrentWeAreSeeding.info_hash);
sendToClient(sock, peer_id);
auto res = std::optional<tr_handshake::Result>{};
auto const handshake = startHandshake(res, &mediator, io);
waitFor([&res] { return res.has_value(); }, MaxWaitMsec);
// check the results
ASSERT_TRUE(res.has_value());
EXPECT_TRUE(res->is_connected);
EXPECT_TRUE(res->read_anything_from_peer);
EXPECT_EQ(io, res->io);
EXPECT_TRUE(res->peer_id);
EXPECT_EQ(peer_id, res->peer_id);
EXPECT_EQ(TorrentWeAreSeeding.info_hash, io->torrent_hash());
tr_net_close_socket(sock);
}
// The datastream is identical to HandshakeTest.incomingPlaintext,
// but this time we don't recognize the infohash sent by the peer.
TEST_F(HandshakeTest, incomingPlaintextUnknownInfoHash)
{
auto mediator = MediatorMock{ session_ };
mediator.torrents.emplace(TorrentWeAreSeeding.info_hash, TorrentWeAreSeeding);
auto [io, sock] = createIncomingIo(session_);
sendToClient(sock, PlaintextProtocolName);
sendToClient(sock, ReservedBytesNoExtensions);
sendToClient(sock, tr_sha1::digest("some other torrent unknown to us"sv));
sendToClient(sock, makeRandomPeerId());
auto res = std::optional<tr_handshake::Result>{};
auto const handshake = startHandshake(res, &mediator, io);
waitFor([&res] { return res.has_value(); }, MaxWaitMsec);
// check the results
ASSERT_TRUE(res.has_value());
EXPECT_FALSE(res->is_connected);
EXPECT_TRUE(res->read_anything_from_peer);
EXPECT_EQ(io, res->io);
EXPECT_FALSE(res->peer_id);
EXPECT_EQ(tr_sha1_digest_t{}, io->torrent_hash());
tr_net_close_socket(sock);
}
TEST_F(HandshakeTest, outgoingPlaintext)
{
auto const peer_id = makeRandomPeerId();
auto mediator = MediatorMock{ session_ };
mediator.torrents.emplace(UbuntuTorrent.info_hash, TorrentWeAreSeeding);
auto [io, sock] = createOutgoingIo(session_, UbuntuTorrent.info_hash);
sendToClient(sock, PlaintextProtocolName);
sendToClient(sock, ReservedBytesNoExtensions);
sendToClient(sock, UbuntuTorrent.info_hash);
sendToClient(sock, peer_id);
auto res = std::optional<tr_handshake::Result>{};
auto const handshake = startHandshake(res, &mediator, io);
waitFor([&res] { return res.has_value(); }, MaxWaitMsec);
// check the results
ASSERT_TRUE(res.has_value());
EXPECT_TRUE(res->is_connected);
EXPECT_TRUE(res->read_anything_from_peer);
EXPECT_EQ(io, res->io);
EXPECT_TRUE(res->peer_id);
EXPECT_EQ(peer_id, res->peer_id);
EXPECT_EQ(UbuntuTorrent.info_hash, io->torrent_hash());
EXPECT_EQ(tr_sha1_to_string(UbuntuTorrent.info_hash), tr_sha1_to_string(io->torrent_hash()));
tr_net_close_socket(sock);
}
TEST_F(HandshakeTest, incomingEncrypted)
{
static auto constexpr ExpectedPeerId = makePeerId("-TR300Z-w4bd4mkebkbi"sv);
auto mediator = MediatorMock{ session_ };
mediator.torrents.emplace(UbuntuTorrent.info_hash, UbuntuTorrent);
mediator.setPrivateKeyFromBase64("0EYKCwBWQ4Dg9kX3c5xxjVtBDKw="sv);
auto [io, sock] = createIncomingIo(session_);
auto res = std::optional<tr_handshake::Result>{};
auto const handshake = startHandshake(res, &mediator, io);
// Peer->Client data from a successful encrypted handshake recorded
// in the wild for replay here. This test will play as the peer.
// 1. Peer sends Ya.
sendB64ToClient(
sock,
"svkySIFcCsrDTeHjPt516UFbsoR+5vfbe5/m6stE7u5JLZ10kJ19NmP64E10qI"
"nn78sCrJgjw1yEHHwrzOcKiRlYvcMotzJMe+SjrFUnaw3KBfn2bcKBhxb/sfM9"
"J7nJ"sv);
// 2. Wait for client to reply with Yb.
ASSERT_TRUE(waitFor(
[&s = std::as_const(sock), buf = std::array<char, 16>{}, n_read = size_t{}]() mutable
{
if (auto ret = recv(s, std::data(buf), std::size(buf), 0); ret > 0)
{
n_read += ret;
}
return n_read >= tr_handshake::DH::KeySize;
},
MaxWaitMsec));
// 3. Peer sends the rest of the handshake.
sendB64ToClient(
sock,
"ICAgICAgICAgIKdr4jIBZ4xFfO4xNiRV7Gl2azTSuTFuu06NU1WyRPif018JYe"
"VGwrTPstEPu3V5lmzjtMGVLaL5EErlpJ93Xrz+ea6EIQEUZA+D4jKaV/to9NVi"
"04/1W1A2PHgg+I9puac/i9BsFPcjdQeoVtU73lNCbTDQgTieyjDWmwo="sv);
// 4. Wait for handshake to complete.
waitFor([&res] { return res.has_value(); }, MaxWaitMsec);
// check the results
ASSERT_TRUE(res.has_value());
EXPECT_TRUE(res->is_connected);
EXPECT_TRUE(res->read_anything_from_peer);
EXPECT_EQ(io, res->io);
EXPECT_TRUE(res->peer_id);
EXPECT_EQ(ExpectedPeerId, res->peer_id);
EXPECT_EQ(UbuntuTorrent.info_hash, io->torrent_hash());
EXPECT_EQ(tr_sha1_to_string(UbuntuTorrent.info_hash), tr_sha1_to_string(io->torrent_hash()));
tr_net_close_socket(sock);
}
// The datastream is identical to HandshakeTest.incomingEncrypted,
// but this time we don't recognize the infohash sent by the peer.
TEST_F(HandshakeTest, incomingEncryptedUnknownInfoHash)
{
auto mediator = MediatorMock{ session_ };
mediator.setPrivateKeyFromBase64("0EYKCwBWQ4Dg9kX3c5xxjVtBDKw="sv);
auto [io, sock] = createIncomingIo(session_);
auto res = std::optional<tr_handshake::Result>{};
auto const handshake = startHandshake(res, &mediator, io);
// Peer->Client data from a successful encrypted handshake recorded
// in the wild for replay here. This test will play as the peer.
// 1. Peer sends Ya.
sendB64ToClient(
sock,
"svkySIFcCsrDTeHjPt516UFbsoR+5vfbe5/m6stE7u5JLZ10kJ19NmP64E10qI"
"nn78sCrJgjw1yEHHwrzOcKiRlYvcMotzJMe+SjrFUnaw3KBfn2bcKBhxb/sfM9"
"J7nJ"sv);
// 2. Wait for client to reply with Yb.
ASSERT_TRUE(waitFor(
[&s = std::as_const(sock), buf = std::array<char, 16>{}, n_read = size_t{}]() mutable
{
if (auto ret = recv(s, std::data(buf), std::size(buf), 0); ret >= 0)
{
n_read += ret;
}
return n_read >= tr_handshake::DH::KeySize;
},
MaxWaitMsec));
// 3. Peer sends the rest of the handshake.
sendB64ToClient(
sock,
"ICAgICAgICAgIKdr4jIBZ4xFfO4xNiRV7Gl2azTSuTFuu06NU1WyRPif018JYe"
"VGwrTPstEPu3V5lmzjtMGVLaL5EErlpJ93Xrz+ea6EIQEUZA+D4jKaV/to9NVi"
"04/1W1A2PHgg+I9puac/i9BsFPcjdQeoVtU73lNCbTDQgTieyjDWmwo="sv);
// 4. Wait for handshake to complete.
waitFor([&res] { return res.has_value(); }, MaxWaitMsec);
// check the results
ASSERT_TRUE(res.has_value());
EXPECT_FALSE(res->is_connected);
EXPECT_TRUE(res->read_anything_from_peer);
EXPECT_EQ(tr_sha1_digest_t{}, io->torrent_hash());
tr_net_close_socket(sock);
}
TEST_F(HandshakeTest, outgoingEncrypted)
{
static auto constexpr ExpectedPeerId = makePeerId("-qB4250-scysDI_JuVN3"sv);
auto mediator = MediatorMock{ session_ };
mediator.torrents.emplace(UbuntuTorrent.info_hash, UbuntuTorrent);
mediator.setPrivateKeyFromBase64("0EYKCwBWQ4Dg9kX3c5xxjVtBDKw="sv);
auto [io, sock] = createOutgoingIo(session_, UbuntuTorrent.info_hash);
auto res = std::optional<tr_handshake::Result>{};
auto const handshake = startHandshake(res, &mediator, io, TR_ENCRYPTION_PREFERRED);
// Peer->Client data from a successful encrypted handshake recorded
// in the wild for replay here. This test will play as the peer.
// 1. Wait for client to send Ya.
ASSERT_TRUE(waitFor(
[&s = std::as_const(sock), buf = std::array<char, 16>{}, n_read = size_t{}]() mutable
{
if (auto ret = recv(s, std::data(buf), std::size(buf), 0); ret >= 0)
{
n_read += ret;
}
return n_read >= tr_handshake::DH::KeySize;
},
MaxWaitMsec));
// 2. Peer replies with Yb.
sendB64ToClient(
sock,
"Sfgoq/nrQfD4Iwirfk+uhOmQMOC/QwK/vYiOact1NF9TpWXms3cvlKEKxs0VU"
"mnmytRh9bh4Lcs1bswlC6R05XrJGzLhZqAqcLUUAR1VTLA5oKSjR1038zFbhn"
"c71jql"sv);
// 3. Wait for client to send HASH('req1', S).
static auto constexpr WantedLen = tr_handshake::PadbMaxlen + std::tuple_size_v<tr_sha1_digest_t>;
static auto constexpr NeedleBase64 = "mbpZFBwdi4U1snVvboN3sMEpNmU="sv;
auto const needle = tr_base64_decode(NeedleBase64);
auto buf = libtransmission::StackBuffer<WantedLen, char>{};
ASSERT_TRUE(waitFor(
[&s = sock, &buf, &needle, n_read = size_t{}]() mutable
{
static auto constexpr StepSize = 14U;
static_assert(WantedLen % StepSize == 0U);
while (n_read < WantedLen)
{
auto const [cur, curlen] = buf.reserve_space(StepSize);
auto const ret = recv(s, cur, curlen, 0);
if (ret <= 0)
{
return false;
}
buf.commit_space(ret);
n_read += ret;
if (auto const it = std::search(std::begin(buf), std::end(buf), std::begin(needle), std::end(needle));
it != std::end(buf))
{
return true;
}
}
return false;
},
MaxWaitMsec));
// 4. Peer sends the rest of the handshake.
sendB64ToClient(
sock,
"paZ3steQoTE58dNkLfvPJdGfTli1FCa1FcvjqCGkzEigwxVTo7o9MviInBNGZ"
"zetXtP0f4PgD0SubXoMNEi2dza/PsuA5e+7GcnNeNT0fcbw49HWtXgL3wb18s"
"g3puL1I6oi1DQhFfCg1xDDwj2AEKA2cy7zMjhLSTP4n9KNFDfPElrbdZI0Q/F"
"Db1JVyHzNGLJyYSgOnye/+IHiu/lqNmonH2ixTshuSBCW04PTkGGwxxWqFcw9"
"MWNA8fidJaKjPgs6z4/FKXlyHGw+6Sa091zxAmxUNdnAmOS1uUcplSMfEz9Go"
"xok8aLtS+w2xg+eEmIFf+KhW2n0bFqfQDvmAyXKLhXf44lTfq95aMb309APR/"
"Q0QDEdK2SqUKV2dWQIQLgDlxhxSL7cPMHenT8m3rufi6EdkvdPyKcB1iI2zW8"
"qUGbgPYZ+CXxTFjz/UxvxNdZaAePjJKz9tlO9ns4y+YqXe+ABBD9P7vMBo9bd"
"pF4TQ/TjX2rAPqWNucvBjNODNAe/tMSprBz+7Z7cECwBmQEx/N6zsWkjt/qP0"
"XYikCQLBsTCFNPLHAXOVTpqwJo3mKyzaRZ6V1bmrx+Yn++PdMzArtwxJxvYaW"
"2G4l/eU/hFHEWzOqUgr6908KtU"sv);
// 5. Wait for handshake to complete.
waitFor([&res] { return res.has_value(); }, MaxWaitMsec);
// check the results
ASSERT_TRUE(res.has_value());
EXPECT_TRUE(res->is_connected);
EXPECT_TRUE(res->read_anything_from_peer);
EXPECT_EQ(io, res->io);
EXPECT_TRUE(res->peer_id);
EXPECT_EQ(ExpectedPeerId, res->peer_id);
EXPECT_EQ(UbuntuTorrent.info_hash, io->torrent_hash());
EXPECT_EQ(tr_sha1_to_string(UbuntuTorrent.info_hash), tr_sha1_to_string(io->torrent_hash()));
tr_net_close_socket(sock);
}
} // namespace libtransmission::test
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