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, 231 insertions, 0 deletions

diff --git a/src/tests/core/internal_network/socket_proxy.cpp b/src/tests/core/internal_network/socket_proxy.cpp
new file mode 100644
index 0000000000..d97d7d5102
--- /dev/null
+++ b/src/tests/core/internal_network/socket_proxy.cpp
@@ -0,0 +1,231 @@
+// SPDX-FileCopyrightText: Copyright 2026 Eden Emulator Project
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#include <array>
+#include <chrono>
+#include <thread>
+
+#include <catch2/catch_test_macros.hpp>
+
+#include "common/socket_types.h"
+#include "common/zstd_compression.h"
+#include "core/internal_network/socket_proxy.h"
+
+namespace {
+
+void BindSocket(Network::ProxySocket& socket, Network::Protocol protocol) {
+    const auto type =
+        protocol == Network::Protocol::TCP ? Network::Type::STREAM : Network::Type::DGRAM;
+    REQUIRE(socket.Initialize(Network::Domain::INET, type, protocol) == Network::Errno::SUCCESS);
+    REQUIRE(socket.Bind({.family = Network::Domain::INET,
+                         .ip = {192, 168, 1, 1},
+                         .portno = 35000}) == Network::Errno::SUCCESS);
+}
+
+template <std::size_t N>
+void QueuePacket(Network::ProxySocket& socket, Network::Protocol protocol,
+                 const std::array<u8, N>& payload) {
+    Network::ProxyPacket packet{};
+    packet.local_endpoint = {.family = Network::Domain::INET,
+                             .ip = {192, 168, 1, 2},
+                             .portno = 35000};
+    packet.remote_endpoint = {.family = Network::Domain::INET,
+                              .ip = {192, 168, 1, 1},
+                              .portno = 35000};
+    packet.protocol = protocol;
+    packet.data = Common::Compression::CompressDataZSTDDefault(payload.data(), payload.size());
+    socket.HandleProxyPacket(packet);
+}
+
+} // namespace
+
+TEST_CASE("Room UDP sockets receive queued datagrams with recv", "[core][sockets]") {
+    Network::ProxySocket socket;
+    BindSocket(socket, Network::Protocol::UDP);
+    REQUIRE(socket.SetNonBlock(true) == Network::Errno::SUCCESS);
+
+    const std::array<u8, 4> payload{1, 2, 3, 4};
+    QueuePacket(socket, Network::Protocol::UDP, payload);
+
+    std::array<u8, 4> received{};
+    const auto [count, error] = socket.Recv(0, received);
+    REQUIRE(error == Network::Errno::SUCCESS);
+    REQUIRE(count == payload.size());
+    REQUIRE(received == payload);
+
+    const auto [empty_count, empty_error] = socket.Recv(0, received);
+    REQUIRE(empty_count == -1);
+    REQUIRE(empty_error == Network::Errno::AGAIN);
+}
+
+TEST_CASE("Room sockets peek without consuming", "[core][sockets]") {
+    Network::ProxySocket socket;
+    BindSocket(socket, Network::Protocol::UDP);
+    REQUIRE(socket.SetNonBlock(true) == Network::Errno::SUCCESS);
+
+    const std::array<u8, 4> payload{1, 2, 3, 4};
+    QueuePacket(socket, Network::Protocol::UDP, payload);
+
+    std::array<u8, 4> received{};
+    REQUIRE(socket.Recv(Network::FLAG_MSG_PEEK, received) ==
+            std::pair<s32, Network::Errno>{4, Network::Errno::SUCCESS});
+    REQUIRE(socket.Recv(0, received) == std::pair<s32, Network::Errno>{4, Network::Errno::SUCCESS});
+    REQUIRE(received == payload);
+    REQUIRE(socket.Recv(0, received).second == Network::Errno::AGAIN);
+}
+
+TEST_CASE("Room UDP sockets truncate oversized datagrams", "[core][sockets]") {
+    Network::ProxySocket socket;
+    BindSocket(socket, Network::Protocol::UDP);
+    REQUIRE(socket.SetNonBlock(true) == Network::Errno::SUCCESS);
+
+    QueuePacket(socket, Network::Protocol::UDP, std::array<u8, 4>{1, 2, 3, 4});
+
+    std::array<u8, 2> received{};
+    REQUIRE(socket.Recv(0, received) == std::pair<s32, Network::Errno>{2, Network::Errno::SUCCESS});
+    REQUIRE(received == std::array<u8, 2>{1, 2});
+    REQUIRE(socket.Recv(0, received).second == Network::Errno::AGAIN);
+}
+
+TEST_CASE("Room TCP sockets keep the unread part of a packet", "[core][sockets]") {
+    Network::ProxySocket socket;
+    BindSocket(socket, Network::Protocol::TCP);
+    REQUIRE(socket.SetNonBlock(true) == Network::Errno::SUCCESS);
+
+    QueuePacket(socket, Network::Protocol::TCP, std::array<u8, 6>{1, 2, 3, 4, 5, 6});
+
+    std::array<u8, 4> received{};
+    REQUIRE(socket.Recv(0, received) == std::pair<s32, Network::Errno>{4, Network::Errno::SUCCESS});
+    REQUIRE(received == std::array<u8, 4>{1, 2, 3, 4});
+    REQUIRE(socket.Recv(0, received) == std::pair<s32, Network::Errno>{2, Network::Errno::SUCCESS});
+    REQUIRE(received[0] == 5);
+    REQUIRE(received[1] == 6);
+    REQUIRE(socket.Recv(0, received) == std::pair<s32, Network::Errno>{0, Network::Errno::SUCCESS});
+}
+
+TEST_CASE("Room TCP sockets read a packet in small parts and peek at the unread part",
+          "[core][sockets]") {
+    Network::ProxySocket socket;
+    BindSocket(socket, Network::Protocol::TCP);
+    REQUIRE(socket.SetNonBlock(true) == Network::Errno::SUCCESS);
+
+    QueuePacket(socket, Network::Protocol::TCP, std::array<u8, 5>{1, 2, 3, 4, 5});
+    QueuePacket(socket, Network::Protocol::TCP, std::array<u8, 2>{6, 7});
+
+    std::array<u8, 2> received{};
+    REQUIRE(socket.Recv(0, received) == std::pair<s32, Network::Errno>{2, Network::Errno::SUCCESS});
+    REQUIRE(received == std::array<u8, 2>{1, 2});
+    REQUIRE(socket.Recv(Network::FLAG_MSG_PEEK, received) ==
+            std::pair<s32, Network::Errno>{2, Network::Errno::SUCCESS});
+    REQUIRE(received == std::array<u8, 2>{3, 4});
+    REQUIRE(socket.Recv(0, received) == std::pair<s32, Network::Errno>{2, Network::Errno::SUCCESS});
+    REQUIRE(received == std::array<u8, 2>{3, 4});
+    REQUIRE(socket.Recv(0, received) == std::pair<s32, Network::Errno>{1, Network::Errno::SUCCESS});
+    REQUIRE(received[0] == 5);
+    REQUIRE(socket.Recv(0, received) == std::pair<s32, Network::Errno>{2, Network::Errno::SUCCESS});
+    REQUIRE(received == std::array<u8, 2>{6, 7});
+}
+
+TEST_CASE("Room TCP sockets report an empty queue as end of stream", "[core][sockets]") {
+    Network::ProxySocket socket;
+    BindSocket(socket, Network::Protocol::TCP);
+
+    std::array<u8, 4> received{};
+    const auto start = std::chrono::steady_clock::now();
+    REQUIRE(socket.Recv(0, received) == std::pair<s32, Network::Errno>{0, Network::Errno::SUCCESS});
+    REQUIRE(std::chrono::steady_clock::now() - start < std::chrono::seconds{1});
+}
+
+TEST_CASE("Blocking room sockets wait for packets and time out with EAGAIN", "[core][sockets]") {
+    Network::ProxySocket socket;
+    BindSocket(socket, Network::Protocol::UDP);
+    REQUIRE(socket.SetRcvTimeo(50) == Network::Errno::SUCCESS);
+
+    std::array<u8, 4> received{};
+    const auto start = std::chrono::steady_clock::now();
+    REQUIRE(socket.Recv(0, received) == std::pair<s32, Network::Errno>{-1, Network::Errno::AGAIN});
+    REQUIRE(std::chrono::steady_clock::now() - start >= std::chrono::milliseconds{50});
+
+    REQUIRE(socket.SetRcvTimeo(5000) == Network::Errno::SUCCESS);
+    const std::array<u8, 4> payload{1, 2, 3, 4};
+    std::jthread sender([&socket, &payload] {
+        std::this_thread::sleep_for(std::chrono::milliseconds{20});
+        QueuePacket(socket, Network::Protocol::UDP, payload);
+    });
+    REQUIRE(socket.Recv(0, received) == std::pair<s32, Network::Errno>{4, Network::Errno::SUCCESS});
+    REQUIRE(received == payload);
+}
+
+TEST_CASE("Closing a room socket wakes a blocked recv and drops queued packets", "[core][sockets]") {
+    Network::ProxySocket socket;
+    BindSocket(socket, Network::Protocol::UDP);
+    REQUIRE(socket.SetRcvTimeo(5000) == Network::Errno::SUCCESS);
+
+    std::array<u8, 4> received{};
+    const auto start = std::chrono::steady_clock::now();
+    std::jthread closer([&socket] {
+        std::this_thread::sleep_for(std::chrono::milliseconds{20});
+        socket.Close();
+    });
+    REQUIRE(socket.Recv(0, received) == std::pair<s32, Network::Errno>{-1, Network::Errno::BADF});
+    REQUIRE(std::chrono::steady_clock::now() - start < std::chrono::seconds{1});
+    closer.join();
+
+    Network::ProxySocket queued;
+    BindSocket(queued, Network::Protocol::UDP);
+    QueuePacket(queued, Network::Protocol::UDP, std::array<u8, 4>{1, 2, 3, 4});
+    REQUIRE(queued.Close() == Network::Errno::SUCCESS);
+    QueuePacket(queued, Network::Protocol::UDP, std::array<u8, 4>{5, 6, 7, 8});
+    REQUIRE(queued.Recv(0, received) == std::pair<s32, Network::Errno>{-1, Network::Errno::BADF});
+}
+
+TEST_CASE("Room stream sockets with the default protocol keep stream behavior", "[core][sockets]") {
+    // socket(AF_INET, SOCK_STREAM, 0) leaves the protocol unspecified
+    Network::ProxySocket socket;
+    REQUIRE(socket.Initialize(Network::Domain::INET, Network::Type::STREAM,
+                              Network::Protocol::Unspecified) == Network::Errno::SUCCESS);
+    REQUIRE(socket.Bind({.family = Network::Domain::INET,
+                         .ip = {192, 168, 1, 1},
+                         .portno = 35000}) == Network::Errno::SUCCESS);
+    REQUIRE(socket.SetRcvTimeo(1000) == Network::Errno::SUCCESS);
+
+    std::array<u8, 2> received{};
+    const auto start = std::chrono::steady_clock::now();
+    REQUIRE(socket.Recv(0, received) == std::pair<s32, Network::Errno>{0, Network::Errno::SUCCESS});
+    REQUIRE(std::chrono::steady_clock::now() - start < std::chrono::milliseconds{500});
+
+    QueuePacket(socket, Network::Protocol::Unspecified, std::array<u8, 4>{1, 2, 3, 4});
+    REQUIRE(socket.Recv(0, received) == std::pair<s32, Network::Errno>{2, Network::Errno::SUCCESS});
+    REQUIRE(received == std::array<u8, 2>{1, 2});
+    REQUIRE(socket.Recv(0, received) == std::pair<s32, Network::Errno>{2, Network::Errno::SUCCESS});
+    REQUIRE(received == std::array<u8, 2>{3, 4});
+}
+
+TEST_CASE("One room packet wakes every blocked peek reader", "[core][sockets]") {
+    Network::ProxySocket socket;
+    BindSocket(socket, Network::Protocol::UDP);
+    REQUIRE(socket.SetRcvTimeo(2000) == Network::Errno::SUCCESS);
+
+    // Catch2 assertions are not thread-safe here, so the readers only record their results
+    std::array<std::pair<s32, Network::Errno>, 2> results{};
+    std::array<std::chrono::steady_clock::time_point, 2> finished{};
+    std::chrono::steady_clock::time_point queued{};
+    {
+        std::array<std::jthread, 2> readers;
+        for (std::size_t i = 0; i < readers.size(); ++i) {
+            readers[i] = std::jthread([&socket, &results, &finished, i] {
+                std::array<u8, 4> peeked{};
+                results[i] = socket.Recv(Network::FLAG_MSG_PEEK, peeked);
+                finished[i] = std::chrono::steady_clock::now();
+            });
+        }
+        std::this_thread::sleep_for(std::chrono::milliseconds{50});
+        queued = std::chrono::steady_clock::now();
+        QueuePacket(socket, Network::Protocol::UDP, std::array<u8, 4>{1, 2, 3, 4});
+    }
+
+    for (std::size_t i = 0; i < results.size(); ++i) {
+        REQUIRE(results[i] == std::pair<s32, Network::Errno>{4, Network::Errno::SUCCESS});
+        REQUIRE(finished[i] - queued < std::chrono::milliseconds{1000});
+    }
+}