tests: cover room ProxySocket receives and the LDN join handshake

Add unit tests for the room LAN fixes in this branch. The socket tests
check datagram truncation, TCP remainders and peeks, timeouts, wakeups on
close and on a new packet, and stream behavior with the default protocol.
The LDN tests check that a join waits for the host's reply, rejects bad or
duplicate joins, ignores late replies and uses fresh identities.

Assisted-by: Sol (LDN join tests)
Assisted-by: Claude Opus 5.5 (room socket tests)

1 files changed, 202 insertions, 0 deletions

diff --git a/src/tests/core/ldn.cpp b/src/tests/core/ldn.cpp
new file mode 100644
index 0000000000..4e6da2d52e
--- /dev/null
+++ b/src/tests/core/ldn.cpp
@@ -0,0 +1,202 @@
+// SPDX-FileCopyrightText: Copyright 2026 Eden Emulator Project
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#include <algorithm>
+#include <chrono>
+#include <cstring>
+#include <future>
+#include <mutex>
+#include <thread>
+#include <catch2/catch_test_macros.hpp>
+
+#include "core/hle/service/ldn/lan_discovery.h"
+#include "core/internal_network/network_interface.h"
+
+using namespace std::chrono_literals;
+
+namespace {
+
+class TestLANDiscovery : public Service::LDN::LANDiscovery {
+public:
+    void SetConnectionTimeout(std::chrono::nanoseconds timeout) {
+        connection_timeout = timeout;
+    }
+
+    std::chrono::nanoseconds GetConnectionTimeout() const {
+        return connection_timeout;
+    }
+
+    bool WaitUntilConnecting() {
+        const auto deadline = std::chrono::steady_clock::now() + 5s;
+        do {
+            {
+                std::scoped_lock lock{packet_mutex};
+                if (host_ip) {
+                    // Connect has published its target and released this lock to wait for a reply.
+                    return true;
+                }
+            }
+            std::this_thread::sleep_for(1ms);
+        } while (std::chrono::steady_clock::now() < deadline);
+        return false;
+    }
+};
+
+} // namespace
+
+TEST_CASE("LDN waits for the selected host's connection reply", "[core][ldn]") {
+    using namespace Service::LDN;
+    if (!Network::GetSelectedNetworkInterface()) {
+        SKIP("LDN requires a host IPv4 interface");
+    }
+
+    TestLANDiscovery station;
+    REQUIRE(station.Initialize([] {}).IsSuccess());
+    REQUIRE(station.OpenStation().IsSuccess());
+
+    NetworkInfo info{};
+    info.network_id.session_id = {1, 2};
+    info.ldn.node_count = 1;
+    info.ldn.node_count_max = 8;
+    info.ldn.nodes[0].ipv4_address = {1, 0, 168, 192};
+
+    Network::LDNPacket reply{};
+    reply.type = Network::LDNPacketType::SyncNetwork;
+    reply.local_ip = {192, 168, 0, 1};
+    reply.data.resize(sizeof(info));
+    std::memcpy(reply.data.data(), &info, sizeof(info));
+
+    // A scan result or unsolicited sync must not connect an idle station.
+    station.ReceivePacket(reply);
+    REQUIRE(station.GetState() == State::StationOpened);
+
+    auto connecting = std::async(std::launch::async, [&] { return station.Connect(info, {}, 1); });
+    REQUIRE(station.WaitUntilConnecting());
+
+    auto unrelated = reply;
+    unrelated.local_ip[3] = 2;
+    station.ReceivePacket(unrelated);
+    REQUIRE(connecting.wait_for(0ms) == std::future_status::timeout);
+
+    auto stale = info;
+    stale.network_id.session_id.low++;
+    std::memcpy(unrelated.data.data(), &stale, sizeof(stale));
+    unrelated.local_ip = reply.local_ip;
+    station.ReceivePacket(unrelated);
+    REQUIRE(connecting.wait_for(0ms) == std::future_status::timeout);
+
+    unrelated.data.resize(1);
+    station.ReceivePacket(unrelated);
+    REQUIRE(connecting.wait_for(0ms) == std::future_status::timeout);
+
+    station.ReceivePacket(reply);
+    REQUIRE(connecting.wait_for(5s) == std::future_status::ready);
+    REQUIRE(connecting.get().IsSuccess());
+    REQUIRE(station.GetState() == State::StationConnected);
+    REQUIRE(station.Finalize().IsSuccess());
+}
+
+TEST_CASE("LDN host validates join packets and does not allocate duplicate stations",
+          "[core][ldn]") {
+    using namespace Service::LDN;
+    if (!Network::GetSelectedNetworkInterface()) {
+        SKIP("LDN requires a host IPv4 interface");
+    }
+
+    LANDiscovery host;
+    REQUIRE(host.Initialize([] {}).IsSuccess());
+    REQUIRE(host.OpenAccessPoint().IsSuccess());
+    NetworkConfig config{};
+    config.node_count_max = 2;
+    REQUIRE(host.CreateNetwork({}, {}, config).IsSuccess());
+
+    NodeInfo node{};
+    node.is_connected = 1;
+    node.mac_address.raw[5] = 1;
+    Network::LDNPacket request{};
+    request.type = Network::LDNPacketType::Connect;
+    request.local_ip = {192, 168, 0, 2};
+    request.data.resize(sizeof(node));
+    std::memcpy(request.data.data(), &node, sizeof(node));
+    host.ReceivePacket(request);
+    NetworkInfo info{};
+    REQUIRE(host.GetNetworkInfo(info).IsSuccess());
+    REQUIRE(info.ldn.node_count == 2);
+
+    host.ReceivePacket(request);
+    REQUIRE(host.GetNetworkInfo(info).IsSuccess());
+    REQUIRE(info.ldn.node_count == 2);
+
+    // A third console cannot enter a two-console network.
+    request.local_ip[3] = 3;
+    host.ReceivePacket(request);
+    REQUIRE(host.GetNetworkInfo(info).IsSuccess());
+    REQUIRE(info.ldn.node_count == 2);
+
+    request.type = Network::LDNPacketType::Disconnect;
+    request.data.resize(1);
+    host.ReceivePacket(request);
+    REQUIRE(host.GetNetworkInfo(info).IsSuccess());
+    REQUIRE(info.ldn.node_count == 2);
+    REQUIRE(host.Finalize().IsSuccess());
+}
+
+TEST_CASE("LDN reports a missing connection reply and ignores late replies", "[core][ldn]") {
+    using namespace Service::LDN;
+    if (!Network::GetSelectedNetworkInterface()) {
+        SKIP("LDN requires a host IPv4 interface");
+    }
+
+    TestLANDiscovery station;
+    REQUIRE(station.GetConnectionTimeout() == 5s);
+    station.SetConnectionTimeout(25ms);
+    REQUIRE(station.Initialize([] {}).IsSuccess());
+    REQUIRE(station.OpenStation().IsSuccess());
+    NetworkInfo info{};
+    info.ldn.node_count = 1;
+    info.ldn.nodes[0].ipv4_address = {1, 0, 168, 192};
+    REQUIRE(station.Connect(info, {}, 1) == ResultAuthenticationTimeout);
+    REQUIRE(station.GetState() == State::StationOpened);
+
+    Network::LDNPacket reply{};
+    reply.type = Network::LDNPacketType::SyncNetwork;
+    reply.local_ip = {192, 168, 0, 1};
+    reply.data.resize(sizeof(info));
+    std::memcpy(reply.data.data(), &info, sizeof(info));
+    station.ReceivePacket(reply);
+    REQUIRE(station.GetState() == State::StationOpened);
+    REQUIRE(station.Finalize().IsSuccess());
+}
+
+TEST_CASE("LDN creates fresh identities for recreated networks and separate hosts", "[core][ldn]") {
+    using namespace Service::LDN;
+    if (!Network::GetSelectedNetworkInterface()) {
+        SKIP("LDN requires a host IPv4 interface");
+    }
+
+    LANDiscovery host;
+    LANDiscovery other_host;
+    REQUIRE(host.Initialize([] {}).IsSuccess());
+    REQUIRE(other_host.Initialize([] {}).IsSuccess());
+    REQUIRE(host.OpenAccessPoint().IsSuccess());
+    REQUIRE(other_host.OpenAccessPoint().IsSuccess());
+    NetworkConfig config{};
+    config.node_count_max = 2;
+    REQUIRE(host.CreateNetwork({}, {}, config).IsSuccess());
+    NetworkInfo first{};
+    REQUIRE(host.GetNetworkInfo(first).IsSuccess());
+
+    REQUIRE(host.DestroyNetwork().IsSuccess());
+    REQUIRE(host.CreateNetwork({}, {}, config).IsSuccess());
+    NetworkInfo recreated{};
+    REQUIRE(host.GetNetworkInfo(recreated).IsSuccess());
+    REQUIRE(recreated.network_id.session_id != first.network_id.session_id);
+
+    REQUIRE(other_host.CreateNetwork({}, {}, config).IsSuccess());
+    NetworkInfo other{};
+    REQUIRE(other_host.GetNetworkInfo(other).IsSuccess());
+    REQUIRE(other.network_id.session_id != first.network_id.session_id);
+    REQUIRE(other.network_id.session_id != recreated.network_id.session_id);
+    REQUIRE(host.Finalize().IsSuccess());
+    REQUIRE(other_host.Finalize().IsSuccess());
+}