Files
MultiRoombaRover/server/src/services/balanceBoardService/native/balance_board_worker.cpp
T
2026-08-19 00:10:41 -04:00

1488 lines
59 KiB
C++

// Wii Balance Board native bridge.
//
// Purpose:
// Pair one original Nintendo RVL-WBC-01 through modern BlueZ, then connect to
// its Bluetooth HID channels directly with wiiuse and expose calibrated sensor
// readings as newline-delimited JSON for the Node server.
//
// Why this process exists:
// BlueZ removed its Wii PIN helper in 2025. A Wii device expects six raw PIN
// bytes equal to the host Bluetooth adapter address in wire order. D-Bus represents PINs
// as UTF-8 strings and cannot safely carry arbitrary bytes, so this bridge races
// BlueZ's agent response with the correct raw MGMT_OP_PIN_CODE_REPLY. Only the
// board currently being commissioned is eligible for that reply.
//
// After commissioning, this worker owns both directions of the HID transport.
// Red Sync uses wiiuse's normal outbound connection; the front power button is
// accepted through always-open control and interrupt listeners. This is
// important rather than stylistic: BlueZ's
// input profile applies medium security to bonded HID devices, and an original
// Balance Board rejects that request with EACCES. Direct low-security sockets
// match the board and avoid the failing profile entirely.
//
// Security boundary:
// The installed binary receives CAP_NET_ADMIN solely for the Bluetooth
// management socket and CAP_NET_BIND_SERVICE solely for the reserved HID PSMs.
// The much larger Node server remains unprivileged. Normal sensor access uses
// ordinary Bluetooth L2CAP sockets through wiiuse.
#include <wiiuse.h>
#include <bluetooth/l2cap.h>
#include <algorithm>
#include <array>
#include <atomic>
#include <cerrno>
#include <chrono>
#include <csignal>
#include <cstdint>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <cmath>
#include <fcntl.h>
#include <iomanip>
#include <iostream>
#include <mutex>
#include <optional>
#include <poll.h>
#include <sstream>
#include <string>
#include <sys/socket.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <thread>
#include <unistd.h>
#include <vector>
// Wiiuse exports these two handshake functions from its shared library but
// keeps them out of the public header because ordinary callers receive sockets
// from wiiuse_connect(). The Balance Board's front button reverses the normal
// connection direction for both HID channels, so this bridge must accept those
// sockets and then start the exact same upstream handshake explicitly.
extern "C" void wiiuse_handshake(struct wiimote_t* board, byte* data, uint16_t length);
extern "C" int wiiuse_set_report_type(struct wiimote_t* board);
namespace {
constexpr const char* kBoardBluetoothName = "Nintendo RVL-WBC-01";
constexpr int kBluetoothProtocolHci = 1;
constexpr uint16_t kHciChannelControl = 3;
constexpr uint16_t kHciDeviceNone = 0xffff;
constexpr uint16_t kMgmtCommandCompleteEvent = 0x0001;
constexpr uint16_t kMgmtCommandStatusEvent = 0x0002;
constexpr uint16_t kMgmtNewSettingsEvent = 0x0006;
constexpr uint16_t kMgmtPinCodeRequestEvent = 0x000e;
constexpr uint16_t kMgmtDeviceFoundEvent = 0x0012;
constexpr uint16_t kMgmtDiscoveringEvent = 0x0013;
constexpr uint16_t kMgmtPinCodeReplyCommand = 0x0016;
constexpr uint16_t kMgmtSetConnectableCommand = 0x0007;
constexpr uint16_t kMgmtSetFastConnectableCommand = 0x0008;
constexpr uint16_t kMgmtStartDiscoveryCommand = 0x0023;
constexpr uint16_t kMgmtStopDiscoveryCommand = 0x0024;
constexpr uint16_t kPrimaryControllerIndex = 0;
constexpr uint8_t kBluetoothClassicAddressType = 0;
constexpr uint8_t kBluetoothClassicDiscoveryMask = 1U << 0;
constexpr uint32_t kDeviceFoundLegacyPairingFlag = 1U << 1;
constexpr uint8_t kEirClassOfDeviceType = 0x0d;
constexpr uint32_t kBalanceBoardClassOfDevice = 0x00002504;
constexpr uint32_t kControllerConnectableSetting = 1U << 1;
constexpr uint32_t kControllerFastConnectableSetting = 1U << 2;
constexpr int kManagementCommandTimeoutMs = 2000;
constexpr int kFrameIntervalMs = 50;
constexpr int kDiscoveryRestartDelayMs = 1000;
constexpr int kDiscoveryStartDeadlineMs = 5000;
constexpr uint16_t kHidControlPsm = 0x0011;
constexpr uint16_t kHidInterruptPsm = 0x0013;
constexpr int kCommissioningConnectWindowMs = 15000;
constexpr int kIncomingChannelPairTimeoutMs = 5000;
constexpr int kHandshakeWarningMs = 10000;
constexpr int kMovementThresholdCentiKg = 50;
constexpr int kStillSleepDelayMs = 2 * 60 * 1000;
std::atomic<bool> running{true};
std::mutex output_mutex;
struct BluetoothAddress {
std::string display;
// The kernel Bluetooth management API carries addresses least-significant
// byte first. These exact six bytes are also the Wii pairing PIN.
std::array<uint8_t, 6> wire{};
};
struct PairingSharedState {
std::mutex mutex;
std::optional<BluetoothAddress> active_target;
std::optional<BluetoothAddress> active_pin;
std::optional<std::string> commissioned_address;
// Discovery commands and events use the same kernel management socket as
// raw Wii PIN replies. The main thread owns socket reads while the
// commissioning thread consumes this small synchronized state, avoiding a
// second reader that could steal PIN or controller-setting events.
std::optional<BluetoothAddress> discovery_candidate;
std::string discovery_error;
bool discovery_start_pending = false;
bool discovery_stop_pending = false;
bool discovery_session_started = false;
bool discovery_active = false;
bool commissioning = false;
bool outbound_connection_requested = false;
};
struct BoardReadings {
int top_right = 0;
int bottom_right = 0;
int top_left = 0;
int bottom_left = 0;
};
struct CommandResult {
int exit_code = -1;
std::string output;
};
struct ManagementRuntimeState {
// Runtime reassertions are asynchronous so a temporary controller setting
// change cannot block PIN or HID handling. Track each outstanding opcode to
// avoid submitting the same command repeatedly while BlueZ is acknowledging
// the first request.
bool connectable_pending = false;
bool fast_connectable_pending = false;
};
uint64_t monotonic_ms() {
using namespace std::chrono;
return duration_cast<milliseconds>(steady_clock::now().time_since_epoch()).count();
}
std::string json_escape(const std::string& value) {
std::ostringstream out;
for (unsigned char ch : value) {
switch (ch) {
case '\\': out << "\\\\"; break;
case '"': out << "\\\""; break;
case '\n': out << "\\n"; break;
case '\r': out << "\\r"; break;
case '\t': out << "\\t"; break;
default:
if (ch < 0x20) {
out << "\\u" << std::hex << std::setw(4) << std::setfill('0')
<< static_cast<int>(ch) << std::dec;
} else {
out << static_cast<char>(ch);
}
}
}
return out.str();
}
void emit_json(const std::string& fields) {
// Pairing and input monitoring run on separate threads. Serialize complete
// lines so two status changes can never interleave and corrupt Node's parser.
std::lock_guard<std::mutex> lock(output_mutex);
std::cout << "{" << fields << "}\n";
std::cout.flush();
}
void emit_status(const std::string& state, const std::string& address = "",
const std::string& error = "") {
std::ostringstream fields;
fields << "\"type\":\"status\",\"state\":\"" << json_escape(state) << "\"";
if (!address.empty()) fields << ",\"address\":\"" << json_escape(address) << "\"";
if (!error.empty()) fields << ",\"error\":\"" << json_escape(error) << "\"";
emit_json(fields.str());
}
void emit_frame(const BoardReadings& readings, std::optional<int> battery_percent = std::nullopt) {
std::ostringstream fields;
fields << "\"type\":\"frame\",\"corners\":{"
<< "\"topRight\":" << readings.top_right << ","
<< "\"bottomRight\":" << readings.bottom_right << ","
<< "\"topLeft\":" << readings.top_left << ","
<< "\"bottomLeft\":" << readings.bottom_left << "}";
if (battery_percent.has_value()) fields << ",\"batteryPercent\":" << *battery_percent;
emit_json(fields.str());
}
void signal_handler(int) {
running.store(false);
}
std::optional<BluetoothAddress> parse_address(const std::string& raw) {
std::array<unsigned int, 6> bytes{};
if (std::sscanf(raw.c_str(), "%2x:%2x:%2x:%2x:%2x:%2x",
&bytes[0], &bytes[1], &bytes[2], &bytes[3], &bytes[4], &bytes[5]) != 6) {
return std::nullopt;
}
BluetoothAddress address;
char normalized[18]{};
std::snprintf(normalized, sizeof(normalized), "%02X:%02X:%02X:%02X:%02X:%02X",
bytes[0], bytes[1], bytes[2], bytes[3], bytes[4], bytes[5]);
address.display = normalized;
for (std::size_t i = 0; i < address.wire.size(); ++i) {
address.wire[i] = static_cast<uint8_t>(bytes[address.wire.size() - 1 - i]);
}
return address;
}
BluetoothAddress address_from_management_wire(const uint8_t* wire) {
BluetoothAddress address;
if (!wire) return address;
// Management packets carry Bluetooth addresses least-significant byte first,
// while every BlueZ command and user-facing status expects the conventional
// most-significant-byte-first representation. Preserve both forms because
// the original wire bytes are later compared with the kernel PIN request.
std::copy(wire, wire + address.wire.size(), address.wire.begin());
char address_buffer[18]{};
std::snprintf(
address_buffer, sizeof(address_buffer), "%02X:%02X:%02X:%02X:%02X:%02X",
address.wire[5], address.wire[4], address.wire[3],
address.wire[2], address.wire[1], address.wire[0]);
address.display = address_buffer;
return address;
}
CommandResult run_command(const std::vector<std::string>& args) {
CommandResult result;
if (args.empty()) return result;
int pipe_fds[2]{};
if (pipe(pipe_fds) != 0) {
result.output = std::strerror(errno);
return result;
}
const pid_t pid = fork();
if (pid == 0) {
dup2(pipe_fds[1], STDOUT_FILENO);
dup2(pipe_fds[1], STDERR_FILENO);
close(pipe_fds[0]);
close(pipe_fds[1]);
std::vector<char*> argv;
argv.reserve(args.size() + 1);
for (const auto& arg : args) argv.push_back(const_cast<char*>(arg.c_str()));
argv.push_back(nullptr);
execvp(argv[0], argv.data());
_exit(127);
}
close(pipe_fds[1]);
if (pid < 0) {
close(pipe_fds[0]);
result.output = std::strerror(errno);
return result;
}
std::array<char, 1024> buffer{};
ssize_t count = 0;
while ((count = read(pipe_fds[0], buffer.data(), buffer.size())) > 0) {
result.output.append(buffer.data(), static_cast<std::size_t>(count));
}
close(pipe_fds[0]);
int status = 0;
while (waitpid(pid, &status, 0) < 0 && errno == EINTR) {}
if (WIFEXITED(status)) result.exit_code = WEXITSTATUS(status);
return result;
}
bool candidate_is_balance_board(const BluetoothAddress& address) {
const CommandResult info = run_command({
"bluetoothctl", "--timeout", "2", "info", address.display});
if (info.output.find(kBoardBluetoothName) != std::string::npos) return true;
// Original Wii input devices identify as legacy-pairing gaming peripherals.
// This fallback is deliberately applied only to an address delivered by the
// kernel's legacy-pairing Device Found event during active commissioning.
// That physical red-Sync action is the selection boundary when an adapter
// cannot resolve Nintendo's remote name in time.
const bool gaming_peripheral =
info.output.find("Class: 0x00002504") != std::string::npos &&
info.output.find("Icon: input-gaming") != std::string::npos;
const bool legacy_pairing =
info.output.find("LegacyPairing: yes") != std::string::npos;
return gaming_peripheral && legacy_pairing;
}
std::string command_error_summary(const std::string& raw, const std::string& fallback) {
std::string summary;
summary.reserve(std::min<std::size_t>(raw.size(), 400));
bool previous_was_space = false;
int ansi_state = 0;
for (unsigned char ch : raw) {
// bluetoothctl emits terminal color CSI sequences even when its output is
// captured by a pipe. Drop the entire ESC ... final-byte sequence so the UI
// never exposes fragments such as `[[0;93mCHG[0m]` as a pairing error.
if (ch == 0x1b) {
ansi_state = 1;
continue;
}
if (ansi_state == 1) {
ansi_state = ch == '[' ? 2 : 0;
continue;
}
if (ansi_state == 2) {
if (ch >= 0x40 && ch <= 0x7e) ansi_state = 0;
continue;
}
const bool is_space = ch == ' ' || ch == '\t' || ch == '\n' || ch == '\r';
if (is_space) {
if (!summary.empty() && !previous_was_space) summary.push_back(' ');
} else if (ch >= 0x20) {
summary.push_back(static_cast<char>(ch));
}
previous_was_space = is_space;
if (summary.size() >= 400) break;
}
while (!summary.empty() && summary.back() == ' ') summary.pop_back();
return summary.empty() ? fallback : summary;
}
bool command_succeeded(const CommandResult& result) {
// bluetoothctl has returned exit code zero for some D-Bus failures across
// releases. Check its stable failure text as well so commissioning never
// stores an address when BlueZ did not actually finish the bond.
return result.exit_code == 0 &&
result.output.find("Failed") == std::string::npos &&
result.output.find("not available") == std::string::npos;
}
std::optional<BluetoothAddress> find_default_controller() {
const CommandResult controller = run_command({"bluetoothctl", "show"});
std::istringstream lines(controller.output);
std::string line;
while (std::getline(lines, line)) {
const std::size_t controller_prefix = line.find("Controller ");
if (controller_prefix == std::string::npos || line.size() < controller_prefix + 28) continue;
if (auto address = parse_address(line.substr(controller_prefix + 11, 17))) return address;
}
return std::nullopt;
}
bool start_management_discovery(int fd, PairingSharedState* shared,
std::string* error);
void stop_management_discovery(int fd, PairingSharedState* shared);
void commissioning_loop(PairingSharedState* shared, int management_fd) {
while (running.load()) {
bool should_commission = false;
{
std::lock_guard<std::mutex> lock(shared->mutex);
should_commission = shared->commissioning && !shared->commissioned_address.has_value();
}
if (!should_commission) {
std::this_thread::sleep_for(std::chrono::milliseconds(250));
continue;
}
emit_status("commissioning");
// Discovery is deliberately performed through the kernel management
// socket already required for Wii PIN replies. Long-running bluetoothctl
// output proved version- and terminal-dependent on the production server;
// MGMT Device Found events are the stable interface underneath BlueZ and
// arrive on this socket without parsing human-oriented terminal output.
std::string discovery_error;
if (!start_management_discovery(
management_fd, shared, &discovery_error)) {
emit_status("error", "", "Bluetooth discovery could not start: " +
discovery_error);
std::this_thread::sleep_for(std::chrono::milliseconds(kDiscoveryRestartDelayMs));
continue;
}
std::optional<BluetoothAddress> address;
while (running.load() && !address.has_value()) {
std::optional<BluetoothAddress> candidate;
bool still_commissioning = false;
{
std::lock_guard<std::mutex> lock(shared->mutex);
still_commissioning = shared->commissioning &&
!shared->commissioned_address.has_value();
candidate = shared->discovery_candidate;
shared->discovery_candidate.reset();
discovery_error = shared->discovery_error;
}
if (!still_commissioning) break;
if (!discovery_error.empty()) {
emit_status("error", "", discovery_error);
break;
}
if (candidate.has_value()) {
emit_status("device-detected", candidate->display,
"Classic Bluetooth device detected; checking whether it is the Balance Board.");
// Class, icon, and legacy-pairing properties can arrive just after the
// first raw inquiry result. Retry that bounded local property lookup at
// quarter-second intervals while the board is awake; this replaces the
// old dependence on a later human-readable bluetoothctl change line.
// The exact identity gate remains mandatory, so an unrelated controller
// can never arm the privileged Wii PIN response.
for (int attempt = 0; attempt < 5 && !address.has_value(); ++attempt) {
if (candidate_is_balance_board(*candidate)) {
address = candidate;
break;
}
if (attempt < 4) {
std::this_thread::sleep_for(std::chrono::milliseconds(250));
}
}
}
std::this_thread::sleep_for(std::chrono::milliseconds(25));
}
if (!address.has_value()) {
stop_management_discovery(management_fd, shared);
if (running.load()) {
std::this_thread::sleep_for(std::chrono::milliseconds(kDiscoveryRestartDelayMs));
}
continue;
}
const auto controller = find_default_controller();
if (!controller.has_value()) {
stop_management_discovery(management_fd, shared);
emit_status("error", address->display,
"no powered Bluetooth controller is available for pairing");
std::this_thread::sleep_for(std::chrono::milliseconds(kDiscoveryRestartDelayMs));
continue;
}
{
std::lock_guard<std::mutex> lock(shared->mutex);
shared->active_target = address;
// Red-Sync commissioning stores the host as the board's future reconnect
// target. BlueZ's retired wiimote plugin therefore used the local adapter
// address—not the board address—as the six raw PIN bytes.
shared->active_pin = controller;
}
emit_status("pairing", address->display);
// The management-socket listener answers the PIN request while this command
// keeps BlueZ's normal device, SDP, bonding, and input-profile machinery in
// charge of everything else.
const CommandResult pair_result = run_command({
"bluetoothctl", "--timeout", "12", "--agent", "NoInputNoOutput", "pair", address->display});
// Keep kernel discovery alive through Pair(). BlueZ pairing by address
// requires the fresh device record, and the board's Sync window is too
// short to stop and recreate discovery before bonding begins.
stop_management_discovery(management_fd, shared);
{
std::lock_guard<std::mutex> lock(shared->mutex);
shared->active_target.reset();
shared->active_pin.reset();
}
if (!command_succeeded(pair_result)) {
emit_status("error", address->display,
"pairing failed: " + command_error_summary(
pair_result.output, "BlueZ returned an unknown pairing error"));
std::this_thread::sleep_for(std::chrono::milliseconds(kDiscoveryRestartDelayMs));
continue;
}
{
std::lock_guard<std::mutex> lock(shared->mutex);
shared->commissioned_address = address->display;
shared->commissioning = false;
// Red Sync makes the board discoverable rather than initiating its normal
// host reconnect. Give wiiuse one bounded outbound window immediately
// after commissioning; every later front-button wake arrives through the
// two HID listeners instead.
shared->outbound_connection_requested = true;
}
emit_json("\"type\":\"paired\",\"address\":\"" + json_escape(address->display) + "\"");
// The direct connection loop notices this address immediately. Pairing and
// sensor transport stay separate so the red Sync button is needed only for
// commissioning; later front-button wakes are caught automatically.
emit_status("waiting", address->display);
}
}
#pragma pack(push, 1)
struct SockaddrHci {
uint16_t family;
uint16_t device;
uint16_t channel;
};
#pragma pack(pop)
int open_management_socket() {
const int fd = socket(AF_BLUETOOTH, SOCK_RAW | SOCK_CLOEXEC | SOCK_NONBLOCK,
kBluetoothProtocolHci);
if (fd < 0) return -1;
const SockaddrHci address{
static_cast<uint16_t>(AF_BLUETOOTH), kHciDeviceNone, kHciChannelControl};
if (bind(fd, reinterpret_cast<const sockaddr*>(&address), sizeof(address)) != 0) {
close(fd);
return -1;
}
return fd;
}
void write_u16_le(uint8_t* output, uint16_t value) {
output[0] = static_cast<uint8_t>(value & 0xff);
output[1] = static_cast<uint8_t>((value >> 8) & 0xff);
}
uint16_t read_u16_le(const uint8_t* input) {
return static_cast<uint16_t>(input[0] | (input[1] << 8));
}
uint32_t read_u32_le(const uint8_t* input) {
return static_cast<uint32_t>(input[0]) |
(static_cast<uint32_t>(input[1]) << 8) |
(static_cast<uint32_t>(input[2]) << 16) |
(static_cast<uint32_t>(input[3]) << 24);
}
bool management_event_has_balance_board_class(const uint8_t* payload,
uint16_t payload_size) {
// Device Found has a fixed 14-byte prefix followed by standard EIR fields.
// Each field begins with a byte count that includes its one-byte type. Parse
// defensively because this data originates over the radio and a malformed
// length must never let commissioning inspect beyond the management packet.
constexpr std::size_t fixed_size = 14;
if (!payload || payload_size < fixed_size) return false;
const uint16_t eir_size = read_u16_le(payload + 12);
if (eir_size > payload_size - fixed_size) return false;
const uint8_t* eir = payload + fixed_size;
std::size_t offset = 0;
while (offset < eir_size) {
const uint8_t field_size = eir[offset];
if (field_size == 0) break;
if (offset + 1 + field_size > eir_size) return false;
const uint8_t field_type = eir[offset + 1];
const std::size_t data_size = field_size - 1;
if (field_type == kEirClassOfDeviceType && data_size >= 3) {
const uint32_t device_class =
static_cast<uint32_t>(eir[offset + 2]) |
(static_cast<uint32_t>(eir[offset + 3]) << 8) |
(static_cast<uint32_t>(eir[offset + 4]) << 16);
return device_class == kBalanceBoardClassOfDevice;
}
offset += 1 + field_size;
}
return false;
}
std::string management_status_description(uint8_t status) {
// These are the management statuses that setting controller modes can
// realistically return. Retain the numeric value as well because it remains
// actionable if a newer kernel introduces a status this worker does not yet
// name.
const char* description = "unknown management status";
switch (status) {
case 0x00: description = "success"; break;
case 0x03: description = "failed"; break;
case 0x0a: description = "busy"; break;
case 0x0c: description = "not supported"; break;
case 0x0d: description = "invalid parameters"; break;
case 0x0f: description = "controller not powered"; break;
case 0x11: description = "invalid controller index"; break;
case 0x14: description = "permission denied"; break;
}
std::ostringstream result;
result << description << " (0x" << std::hex << std::setw(2)
<< std::setfill('0') << static_cast<int>(status) << ")";
return result.str();
}
bool write_management_boolean_command(int fd, uint16_t opcode, bool enabled) {
if (fd < 0) return false;
constexpr std::size_t header_size = 6;
std::array<uint8_t, header_size + 1> packet{};
write_u16_le(packet.data(), opcode);
write_u16_le(packet.data() + 2, kPrimaryControllerIndex);
write_u16_le(packet.data() + 4, 1);
packet[header_size] = enabled ? 1 : 0;
return write(fd, packet.data(), packet.size()) ==
static_cast<ssize_t>(packet.size());
}
bool write_management_discovery_command(int fd, uint16_t opcode) {
if (fd < 0) return false;
constexpr std::size_t header_size = 6;
std::array<uint8_t, header_size + 1> packet{};
write_u16_le(packet.data(), opcode);
write_u16_le(packet.data() + 2, kPrimaryControllerIndex);
write_u16_le(packet.data() + 4, 1);
// The Balance Board is a Classic Bluetooth device. Restricting discovery to
// BR/EDR avoids irrelevant LE advertisements and ensures every Device Found
// event uses the address type expected by the Wii pairing path.
packet[header_size] = kBluetoothClassicDiscoveryMask;
return write(fd, packet.data(), packet.size()) ==
static_cast<ssize_t>(packet.size());
}
bool start_management_discovery(int fd, PairingSharedState* shared,
std::string* error) {
if (fd < 0 || !shared) {
if (error) *error = "Bluetooth management socket is unavailable";
return false;
}
{
std::lock_guard<std::mutex> lock(shared->mutex);
shared->discovery_candidate.reset();
shared->discovery_error.clear();
shared->discovery_start_pending = true;
shared->discovery_stop_pending = false;
shared->discovery_session_started = false;
shared->discovery_active = false;
}
if (!write_management_discovery_command(fd, kMgmtStartDiscoveryCommand)) {
const std::string detail = "could not send Start Discovery: " +
std::string(std::strerror(errno));
{
std::lock_guard<std::mutex> lock(shared->mutex);
shared->discovery_start_pending = false;
shared->discovery_error = detail;
}
if (error) *error = detail;
return false;
}
// Command Complete proves the kernel accepted the session, while the
// Discovering event proves inquiry is actually active on the controller.
// Require both so the UI can never repeat the earlier false "listening"
// state where a process existed but no radio scan was running.
const uint64_t deadline = monotonic_ms() + kDiscoveryStartDeadlineMs;
while (running.load() && monotonic_ms() < deadline) {
std::string discovery_error;
bool ready = false;
{
std::lock_guard<std::mutex> lock(shared->mutex);
discovery_error = shared->discovery_error;
ready = shared->discovery_session_started && shared->discovery_active;
}
if (!discovery_error.empty()) {
if (error) *error = discovery_error;
return false;
}
if (ready) return true;
std::this_thread::sleep_for(std::chrono::milliseconds(10));
}
if (error) *error = "kernel accepted no active BR/EDR discovery session within 5 seconds";
stop_management_discovery(fd, shared);
return false;
}
void stop_management_discovery(int fd, PairingSharedState* shared) {
if (fd < 0 || !shared) return;
bool should_stop = false;
{
std::lock_guard<std::mutex> lock(shared->mutex);
should_stop = shared->discovery_start_pending ||
shared->discovery_session_started || shared->discovery_active;
shared->discovery_candidate.reset();
if (should_stop) shared->discovery_stop_pending = true;
}
if (!should_stop) return;
if (!write_management_discovery_command(fd, kMgmtStopDiscoveryCommand)) {
std::lock_guard<std::mutex> lock(shared->mutex);
shared->discovery_stop_pending = false;
shared->discovery_error = "could not send Stop Discovery: " +
std::string(std::strerror(errno));
return;
}
// Pairing retries should not collide with a previous inquiry session. Wait
// briefly for the matching command response, but never let a misbehaving
// adapter hold server shutdown or commissioning indefinitely.
const uint64_t deadline = monotonic_ms() + kManagementCommandTimeoutMs;
while (running.load() && monotonic_ms() < deadline) {
bool stopped = false;
{
std::lock_guard<std::mutex> lock(shared->mutex);
stopped = !shared->discovery_stop_pending &&
!shared->discovery_session_started;
}
if (stopped) return;
std::this_thread::sleep_for(std::chrono::milliseconds(10));
}
}
bool set_management_boolean_and_wait(int fd, uint16_t opcode,
const std::string& setting_name,
std::string* error) {
if (!write_management_boolean_command(fd, opcode, true)) {
if (error) *error = "could not send the " + setting_name + " command: " +
std::string(std::strerror(errno));
return false;
}
// A successful write only queues a request to the kernel. Wait for the
// matching Command Complete/Status event so the worker never advertises a
// reliable wake listener when the adapter actually rejected the setting.
const uint64_t deadline = monotonic_ms() + kManagementCommandTimeoutMs;
while (running.load()) {
const uint64_t now = monotonic_ms();
if (now >= deadline) break;
const int remaining = static_cast<int>(deadline - now);
pollfd descriptor{fd, POLLIN, 0};
const int ready = poll(&descriptor, 1, std::max(1, remaining));
if (ready < 0) {
if (errno == EINTR) continue;
if (error) *error = "could not wait for the " + setting_name +
" response: " + std::string(std::strerror(errno));
return false;
}
if (ready == 0) break;
std::array<uint8_t, 1024> response{};
const ssize_t count = read(fd, response.data(), response.size());
if (count < 9) continue;
const uint16_t event = read_u16_le(response.data());
const uint16_t response_opcode = read_u16_le(response.data() + 6);
if ((event != kMgmtCommandCompleteEvent && event != kMgmtCommandStatusEvent) ||
response_opcode != opcode) {
// Startup occurs before pairing and connection threads exist, so the only
// expected extra packet is New Settings generated by the command itself.
// The matching completion is still queued immediately after it.
continue;
}
const uint8_t status = response[8];
if (status == 0) return true;
if (error) *error = setting_name + " was rejected: " +
management_status_description(status);
return false;
}
if (error) *error = "timed out waiting for the " + setting_name + " response";
return false;
}
bool enable_incoming_connections(int fd, std::string* error) {
if (fd < 0) {
if (error) *error = "management socket is unavailable";
return false;
}
// Set Connectable enables the BR/EDR page scan that accepts the board's
// incoming front-button connection. Fast Connectable increases the page-scan
// duty cycle so the controller can catch the board during its unusually short
// one-to-two-second wake attempt. A stationary server can accept the modest
// adapter power cost in exchange for reliable unattended operation.
if (!set_management_boolean_and_wait(
fd, kMgmtSetConnectableCommand, "connectable setting", error)) {
return false;
}
return set_management_boolean_and_wait(
fd, kMgmtSetFastConnectableCommand, "fast connectable setting", error);
}
void answer_pin_request(int fd, uint16_t adapter_index,
const BluetoothAddress& target,
const BluetoothAddress& pin) {
// Packet layout is a six-byte mgmt header followed by mgmt_addr_info,
// pin_len, and the fixed sixteen-byte PIN buffer. Serializing by hand avoids
// compiler padding and documents every privileged byte sent to the kernel.
constexpr std::size_t header_size = 6;
constexpr std::size_t payload_size = 7 + 1 + 16;
std::array<uint8_t, header_size + payload_size> packet{};
write_u16_le(packet.data(), kMgmtPinCodeReplyCommand);
write_u16_le(packet.data() + 2, adapter_index);
write_u16_le(packet.data() + 4, payload_size);
std::copy(target.wire.begin(), target.wire.end(), packet.begin() + header_size);
packet[header_size + 6] = kBluetoothClassicAddressType;
packet[header_size + 7] = 6;
std::copy(pin.wire.begin(), pin.wire.end(), packet.begin() + header_size + 8);
if (write(fd, packet.data(), packet.size()) != static_cast<ssize_t>(packet.size())) {
emit_status("error", target.display, "failed to answer the Wii pairing PIN request");
}
}
void queue_runtime_management_setting(int fd, uint16_t opcode,
const std::string& setting_name,
bool* pending) {
if (!pending || *pending) return;
if (!write_management_boolean_command(fd, opcode, true)) {
emit_status("error", "", "Could not restore the Bluetooth " + setting_name +
": " + std::string(std::strerror(errno)));
return;
}
*pending = true;
}
void process_management_events(int fd, PairingSharedState* shared,
ManagementRuntimeState* management) {
if (fd < 0) return;
std::array<uint8_t, 1024> buffer{};
ssize_t count = 0;
while ((count = read(fd, buffer.data(), buffer.size())) > 0) {
if (count < 6) continue;
const uint16_t event = read_u16_le(buffer.data());
const uint16_t adapter_index = read_u16_le(buffer.data() + 2);
const uint16_t payload_size = read_u16_le(buffer.data() + 4);
if (count < 6 + payload_size) continue;
if ((event == kMgmtCommandCompleteEvent || event == kMgmtCommandStatusEvent) &&
payload_size >= 3) {
const uint16_t opcode = read_u16_le(buffer.data() + 6);
const uint8_t status = buffer[8];
if (opcode == kMgmtStartDiscoveryCommand ||
opcode == kMgmtStopDiscoveryCommand) {
std::lock_guard<std::mutex> lock(shared->mutex);
if (opcode == kMgmtStartDiscoveryCommand) {
shared->discovery_start_pending = false;
if (status == 0) {
shared->discovery_session_started = true;
} else {
shared->discovery_session_started = false;
shared->discovery_active = false;
shared->discovery_error = "Start Discovery was rejected: " +
management_status_description(status);
}
} else {
shared->discovery_stop_pending = false;
if (status == 0) {
shared->discovery_start_pending = false;
shared->discovery_session_started = false;
shared->discovery_active = false;
} else {
shared->discovery_error = "Stop Discovery was rejected: " +
management_status_description(status);
}
}
continue;
}
bool recognized = false;
std::string setting_name;
if (management && opcode == kMgmtSetConnectableCommand) {
management->connectable_pending = false;
recognized = true;
setting_name = "connectable setting";
} else if (management && opcode == kMgmtSetFastConnectableCommand) {
management->fast_connectable_pending = false;
recognized = true;
setting_name = "fast connectable setting";
}
if (recognized && status != 0) {
emit_status("error", "", "Bluetooth " + setting_name +
" reassertion was rejected: " + management_status_description(status));
}
continue;
}
if (event == kMgmtDiscoveringEvent && payload_size >= 2 &&
adapter_index == kPrimaryControllerIndex) {
const uint8_t address_types = buffer[6];
const bool active = buffer[7] != 0;
bool announce_discovery = false;
{
std::lock_guard<std::mutex> lock(shared->mutex);
if (shared->commissioning &&
(address_types & kBluetoothClassicDiscoveryMask) != 0) {
announce_discovery = active && !shared->discovery_active;
shared->discovery_active = active;
}
}
if (announce_discovery) emit_status("discovering");
continue;
}
if (event == kMgmtDeviceFoundEvent && payload_size >= 14 &&
adapter_index == kPrimaryControllerIndex) {
const uint8_t* payload = buffer.data() + 6;
const uint8_t address_type = payload[6];
const uint32_t flags = read_u32_le(payload + 8);
const bool balance_board_class =
management_event_has_balance_board_class(payload, payload_size);
// Some controllers provide the gaming-device class in the first inquiry
// result and add Legacy Pairing only after name resolution; others do the
// reverse. Either radio-level signal is narrow enough to justify the
// bounded BlueZ property check, while ordinary Classic devices never
// disturb the panel or launch repeated identity commands.
if (address_type == kBluetoothClassicAddressType &&
(balance_board_class ||
(flags & kDeviceFoundLegacyPairingFlag) != 0)) {
const BluetoothAddress candidate =
address_from_management_wire(payload);
std::lock_guard<std::mutex> lock(shared->mutex);
if (shared->commissioning &&
!shared->commissioned_address.has_value()) {
shared->discovery_candidate = candidate;
}
}
continue;
}
if (event == kMgmtNewSettingsEvent && payload_size >= 4 &&
adapter_index == kPrimaryControllerIndex && management) {
const uint32_t settings = read_u32_le(buffer.data() + 6);
// BlueZ or another controller operation can replace the page-scan modes
// after worker startup. Reassert only missing modes and let their normal
// command responses below report any rejection; pending flags prevent a
// burst of New Settings events from queuing duplicate commands.
if ((settings & kControllerConnectableSetting) == 0) {
queue_runtime_management_setting(
fd, kMgmtSetConnectableCommand, "connectable setting",
&management->connectable_pending);
} else if ((settings & kControllerFastConnectableSetting) == 0) {
// Fast Connectable is meaningful only after ordinary Connectable has
// taken effect. Sequencing them avoids a transient Busy/Rejected reply
// when a controller reset removed both modes at the same time.
queue_runtime_management_setting(
fd, kMgmtSetFastConnectableCommand, "fast connectable setting",
&management->fast_connectable_pending);
}
continue;
}
if (event == kMgmtPinCodeRequestEvent && payload_size >= 8) {
std::optional<BluetoothAddress> target;
std::optional<BluetoothAddress> pin;
{
std::lock_guard<std::mutex> lock(shared->mutex);
target = shared->active_target;
pin = shared->active_pin;
}
if (target.has_value() && pin.has_value() &&
std::equal(target->wire.begin(), target->wire.end(), buffer.begin() + 6)) {
answer_pin_request(fd, adapter_index, *target, *pin);
}
continue;
}
}
}
std::optional<std::string> extract_command_value(const std::string& line, const std::string& key) {
const std::string token = "\"" + key + "\"";
const std::size_t key_at = line.find(token);
if (key_at == std::string::npos) return std::nullopt;
const std::size_t colon = line.find(':', key_at + token.size());
const std::size_t first_quote = line.find('"', colon + 1);
const std::size_t second_quote = line.find('"', first_quote + 1);
if (colon == std::string::npos || first_quote == std::string::npos || second_quote == std::string::npos) {
return std::nullopt;
}
return line.substr(first_quote + 1, second_quote - first_quote - 1);
}
void handle_command(const std::string& line, PairingSharedState* shared) {
(void)shared;
const std::string command = extract_command_value(line, "command").value_or("");
// Pairing and reconnect are deliberately automatic. The only command the
// Node supervisor needs is a clean shutdown signal; removing manual pair,
// forget, and disconnect modes keeps the hardware flow single-purpose.
if (command == "stop") {
running.store(false);
}
}
void stdin_loop(PairingSharedState* shared) {
std::string line;
while (running.load() && std::getline(std::cin, line)) handle_command(line, shared);
}
bool sleeping_connection_error(int error_number) {
// A powered-off board normally answers an outgoing page with one of these
// transport errors. They mean "keep waiting for the front button," not that
// installation is broken. Every other errno is surfaced verbatim in the UI.
return error_number == EHOSTDOWN || error_number == EHOSTUNREACH ||
error_number == ETIMEDOUT || error_number == ECONNREFUSED;
}
void close_wiiuse_sockets(wiimote_t* board) {
if (!board) return;
// Wiiuse 0.15.5 can leave a socket allocated when the second L2CAP connect
// fails. Close both descriptors explicitly so an unattended server can page
// a sleeping board forever without leaking one descriptor per attempt.
const int output_socket = board->out_sock;
const int input_socket = board->in_sock;
if (output_socket >= 0) close(output_socket);
if (input_socket >= 0 && input_socket != output_socket) close(input_socket);
board->out_sock = -1;
board->in_sock = -1;
}
void prepare_wiiuse_address(wiimote_t* board, const std::string& address) {
// Supplying the saved address and DEV_FOUND flag tells wiiuse to skip its own
// discovery pass. That makes every reconnect a direct page of the one board
// already commissioned to this server.
str2ba(address.c_str(), &board->bdaddr);
std::snprintf(board->bdaddr_str, sizeof(board->bdaddr_str), "%s", address.c_str());
board->state |= WIIMOTE_STATE_DEV_FOUND;
}
wiimote_t** initialize_wiiuse() {
// wiiuse_init prints one version banner directly to stdout rather than using
// its logger. Suppress only that initialization call before any worker
// threads exist, then restore stdout for the JSON protocol.
std::fflush(stdout);
const int saved_stdout = dup(STDOUT_FILENO);
const int null_output = open("/dev/null", O_WRONLY | O_CLOEXEC);
if (saved_stdout >= 0 && null_output >= 0) dup2(null_output, STDOUT_FILENO);
wiimote_t** boards = wiiuse_init(1);
std::fflush(stdout);
if (saved_stdout >= 0) {
dup2(saved_stdout, STDOUT_FILENO);
close(saved_stdout);
}
if (null_output >= 0) close(null_output);
// Wiiuse resets its log targets inside wiiuse_init, so configure them after
// initialization. Retain actual library errors on stderr, but discard normal
// connect/disconnect chatter that repeats for every page while the board is
// asleep; structured JSON already describes that state for the panel.
wiiuse_set_output(LOGLEVEL_ERROR, stderr);
wiiuse_set_output(LOGLEVEL_WARNING, nullptr);
wiiuse_set_output(LOGLEVEL_INFO, nullptr);
wiiuse_set_output(LOGLEVEL_DEBUG, nullptr);
return boards;
}
bool request_low_bluetooth_security(int fd, std::string* error) {
bt_security security{};
security.level = BT_SECURITY_LOW;
if (setsockopt(fd, SOL_BLUETOOTH, BT_SECURITY, &security, sizeof(security)) == 0) {
return true;
}
if (error) *error = std::strerror(errno);
return false;
}
int open_hid_listener(uint16_t psm, std::string* error) {
const int fd = socket(AF_BLUETOOTH,
SOCK_SEQPACKET | SOCK_CLOEXEC | SOCK_NONBLOCK,
BTPROTO_L2CAP);
if (fd < 0) {
if (error) *error = std::strerror(errno);
return -1;
}
// The bonded BlueZ input profile requested medium security and produced the
// original EACCES failure. Wii hardware HID channels are intentionally low
// security; applying that level to the listener also makes it inherit onto
// every accepted front-button connection.
if (!request_low_bluetooth_security(fd, error)) {
close(fd);
return -1;
}
sockaddr_l2 local{};
local.l2_family = AF_BLUETOOTH;
local.l2_psm = htobs(psm);
// Value initialization leaves l2_bdaddr at the all-zero BDADDR_ANY value.
// Avoid BlueZ's C-only compound-literal macro, which is not valid C++17.
if (bind(fd, reinterpret_cast<const sockaddr*>(&local), sizeof(local)) != 0 ||
listen(fd, 1) != 0) {
if (error) *error = std::strerror(errno);
close(fd);
return -1;
}
return fd;
}
std::optional<int> accept_board_channel(int listener,
const std::string& expected_address,
std::string* error) {
sockaddr_l2 remote{};
socklen_t remote_size = sizeof(remote);
const int fd = accept4(listener, reinterpret_cast<sockaddr*>(&remote),
&remote_size, SOCK_CLOEXEC);
if (fd < 0) {
if (errno != EAGAIN && errno != EWOULDBLOCK && errno != EINTR && error) {
*error = std::strerror(errno);
}
return std::nullopt;
}
char remote_text[18]{};
ba2str(&remote.l2_bdaddr, remote_text);
const auto normalized = parse_address(remote_text);
if (!normalized.has_value() || normalized->display != expected_address) {
// Both HID PSMs are global to the adapter. The installer dedicates them to
// this worker, but still reject any unrelated controller instead of
// attaching an arbitrary input device to the Balance Board parser.
close(fd);
return std::nullopt;
}
return fd;
}
void attach_incoming_board(wiimote_t* board, int control_fd, int interrupt_fd,
const std::string& address) {
// A reconnecting Wii device opens both channels toward the remembered host:
// control on PSM 0x11 followed by interrupt on PSM 0x13. Once both accepted
// sockets exist, their direction and semantics are identical to the pair
// created by wiiuse_connect(). Attach them and run the upstream handshake.
close_wiiuse_sockets(board);
wiiuse_disconnected(board);
prepare_wiiuse_address(board, address);
board->out_sock = control_fd;
board->in_sock = interrupt_fd;
board->state |= WIIMOTE_STATE_CONNECTED;
wiiuse_handshake(board, nullptr, 0);
wiiuse_set_report_type(board);
}
struct PendingIncomingChannels {
int control_fd = -1;
int interrupt_fd = -1;
uint64_t first_channel_at = 0;
};
void close_pending_channels(PendingIncomingChannels* pending) {
if (!pending) return;
if (pending->control_fd >= 0) close(pending->control_fd);
if (pending->interrupt_fd >= 0 && pending->interrupt_fd != pending->control_fd) {
close(pending->interrupt_fd);
}
pending->control_fd = -1;
pending->interrupt_fd = -1;
pending->first_channel_at = 0;
}
void direct_connection_loop(PairingSharedState* shared, wiimote_t** boards) {
wiimote_t* board = boards ? boards[0] : nullptr;
if (!board) {
emit_status("error", "", "wiiuse could not initialize the Balance Board connection");
return;
}
std::string control_listener_error;
const int control_listener = open_hid_listener(kHidControlPsm, &control_listener_error);
if (control_listener < 0) {
emit_status("error", "",
"Cannot listen for the Balance Board control channel: " +
control_listener_error +
". Run the installer to configure the dedicated Bluetooth listener.");
return;
}
std::string interrupt_listener_error;
const int interrupt_listener = open_hid_listener(
kHidInterruptPsm, &interrupt_listener_error);
if (interrupt_listener < 0) {
close(control_listener);
emit_status("error", "",
"Cannot listen for the Balance Board interrupt channel: " +
interrupt_listener_error +
". Run the installer to configure the dedicated Bluetooth listener.");
return;
}
std::string prepared_address;
uint64_t outbound_connect_until = 0;
PendingIncomingChannels pending;
while (running.load()) {
std::optional<std::string> address;
bool outbound_requested = false;
{
std::lock_guard<std::mutex> lock(shared->mutex);
address = shared->commissioned_address;
outbound_requested = shared->outbound_connection_requested;
shared->outbound_connection_requested = false;
}
if (!address.has_value()) {
std::this_thread::sleep_for(std::chrono::milliseconds(100));
continue;
}
if (prepared_address != *address) {
// Never combine a channel from the previous configured board with a
// channel from the new one. This normally matters only after Forget and
// re-pair, but keeping the socket pair atomic prevents a misleading
// handshake failure during that transition.
close_pending_channels(&pending);
close_wiiuse_sockets(board);
wiiuse_disconnected(board);
prepare_wiiuse_address(board, *address);
prepared_address = *address;
}
if (outbound_requested) {
outbound_connect_until = monotonic_ms() + kCommissioningConnectWindowMs;
}
bool transport_connected = false;
std::string control_error;
if (auto control_fd = accept_board_channel(
control_listener, *address, &control_error)) {
if (pending.control_fd >= 0) close(pending.control_fd);
pending.control_fd = *control_fd;
if (pending.first_channel_at == 0) {
pending.first_channel_at = monotonic_ms();
emit_status("link-detected", *address,
"Front button reached the Bluetooth control channel.");
}
} else if (!control_error.empty()) {
emit_status("connection-failed", *address,
"Balance Board control listener failed: " + control_error);
}
std::string interrupt_error;
if (auto interrupt_fd = accept_board_channel(
interrupt_listener, *address, &interrupt_error)) {
if (pending.interrupt_fd >= 0) close(pending.interrupt_fd);
pending.interrupt_fd = *interrupt_fd;
if (pending.first_channel_at == 0) {
pending.first_channel_at = monotonic_ms();
emit_status("link-detected", *address,
"Front button reached the Bluetooth interrupt channel.");
}
} else if (!interrupt_error.empty()) {
emit_status("connection-failed", *address,
"Balance Board interrupt listener failed: " + interrupt_error);
}
if (pending.control_fd >= 0 && pending.interrupt_fd >= 0) {
attach_incoming_board(
board, pending.control_fd, pending.interrupt_fd, *address);
pending.control_fd = -1;
pending.interrupt_fd = -1;
pending.first_channel_at = 0;
transport_connected = true;
} else if (pending.first_channel_at != 0 &&
monotonic_ms() - pending.first_channel_at >=
kIncomingChannelPairTimeoutMs) {
const bool control_arrived = pending.control_fd >= 0;
close_pending_channels(&pending);
emit_status(
"connection-failed", *address,
control_arrived
? "Front button reached the control channel, but the interrupt channel did not arrive."
: "Front button reached the interrupt channel, but the control channel did not arrive.");
}
if (!transport_connected && pending.first_channel_at == 0 &&
monotonic_ms() < outbound_connect_until) {
// Red Sync makes the board discoverable instead of reconnecting to the
// remembered host. During the short post-commissioning window only,
// retain wiiuse's normal outbound connector so the first session starts
// without asking for a second physical button press.
errno = 0;
const int connected_count = wiiuse_connect(boards, 1);
const int connection_error = errno;
if (connected_count == 1 && WIIMOTE_IS_CONNECTED(board)) {
transport_connected = true;
outbound_connect_until = 0;
emit_status("link-detected", *address);
} else {
close_wiiuse_sockets(board);
wiiuse_disconnected(board);
prepare_wiiuse_address(board, *address);
if (connection_error != 0 && !sleeping_connection_error(connection_error)) {
emit_status("connection-failed", *address,
"Initial Balance Board connection failed: " +
std::string(std::strerror(connection_error)));
}
}
}
if (!transport_connected) {
std::this_thread::sleep_for(std::chrono::milliseconds(25));
continue;
}
bool board_ready = false;
bool handshake_warning_sent = false;
bool intentional_sleep = false;
std::optional<BoardReadings> activity_reference;
uint64_t connected_at = monotonic_ms();
uint64_t last_movement_at = connected_at;
uint64_t last_frame_at = 0;
while (running.load() && WIIMOTE_IS_CONNECTED(board)) {
wiiuse_poll(boards, 1);
if (board->event == WIIUSE_DISCONNECT ||
board->event == WIIUSE_UNEXPECTED_DISCONNECT) {
break;
}
if (board->exp.type == EXP_WII_BOARD) {
if (!board_ready) {
board_ready = true;
// The Balance Board has one blue player light. Wiiuse clears all LEDs
// during its handshake, which leaves the light flashing even though
// measurements work. A solid first LED is the unambiguous connected
// indication used for the rest of this session.
wiiuse_set_leds(board, WIIMOTE_LED_1);
emit_status("connected", *address);
}
const uint64_t now = monotonic_ms();
if (now - last_frame_at >= kFrameIntervalMs) {
// Wiiuse interpolates each sensor using the board's factory 0/17/34kg
// calibration values. Preserve the existing centi-kilogram wire unit
// so Node can apply its persisted installation zero per corner without
// losing the native sensor resolution.
const wii_board_t& weights = board->exp.wb;
BoardReadings readings{
static_cast<int>(std::lround(std::max(0.0F, weights.tr) * 100.0F)),
static_cast<int>(std::lround(std::max(0.0F, weights.br) * 100.0F)),
static_cast<int>(std::lround(std::max(0.0F, weights.tl) * 100.0F)),
static_cast<int>(std::lround(std::max(0.0F, weights.bl) * 100.0F)),
};
const int battery = static_cast<int>(std::lround(
std::clamp(board->battery_level, 0.0F, 1.0F) * 100.0F));
emit_frame(readings, battery);
last_frame_at = now;
if (!activity_reference.has_value()) {
activity_reference = readings;
last_movement_at = now;
} else {
// Compare against the last meaningful activity snapshot rather
// than the immediately previous frame. That lets slow movement
// accumulate past the noise threshold while ordinary sensor jitter
// cannot keep the board awake forever. All four corners matter, so
// shifting a load without changing total weight still counts.
const int movement =
std::abs(readings.top_right - activity_reference->top_right) +
std::abs(readings.bottom_right - activity_reference->bottom_right) +
std::abs(readings.top_left - activity_reference->top_left) +
std::abs(readings.bottom_left - activity_reference->bottom_left);
if (movement >= kMovementThresholdCentiKg) {
activity_reference = readings;
last_movement_at = now;
}
}
if (now - last_movement_at >= kStillSleepDelayMs) {
intentional_sleep = true;
emit_status("sleeping", *address,
"Board is asleep. Press the front power button to wake it.");
break;
}
}
} else if (!handshake_warning_sent &&
monotonic_ms() - connected_at >= kHandshakeWarningMs) {
// A live ACL connection without the permanent Balance Board expansion
// means sensor calibration never completed. Report that precise stage
// while continuing to poll, since a delayed response can still recover.
handshake_warning_sent = true;
emit_status("connection-failed", *address,
"Bluetooth connected, but the board did not finish sensor calibration.");
}
std::this_thread::sleep_for(std::chrono::milliseconds(10));
}
close_wiiuse_sockets(board);
wiiuse_disconnected(board);
prepare_wiiuse_address(board, *address);
if (intentional_sleep) {
// Closing both HID channels makes the board abandon the host connection
// and power itself down. Both HID listeners stay open without paging it,
// so only a later front-button connection starts another session.
} else {
emit_status("waiting", *address, "Board disconnected. Press the front power button.");
}
}
close_pending_channels(&pending);
close(control_listener);
close(interrupt_listener);
close_wiiuse_sockets(board);
wiiuse_disconnected(board);
}
void simulated_loop() {
// Exercise the same status contract as real hardware so development UI
// builds cannot silently break merely because CI lacks a physical board.
emit_status("waiting", "SIMULATED");
const std::array<BoardReadings, 12> sequence{{
{0, 0, 0, 0}, {0, 0, 0, 0}, {40, 30, 35, 25}, {95, 82, 90, 76},
{103, 97, 101, 99}, {104, 98, 101, 99}, {103, 98, 102, 99},
{103, 98, 101, 100}, {104, 98, 101, 99}, {75, 65, 70, 60},
{20, 12, 15, 10}, {0, 0, 0, 0},
}};
while (running.load()) {
emit_status("connected", "SIMULATED");
for (const auto& readings : sequence) {
for (int frame = 0; frame < 12 && running.load(); ++frame) {
emit_frame(readings, 82);
std::this_thread::sleep_for(std::chrono::milliseconds(kFrameIntervalMs));
}
}
emit_status("waiting", "SIMULATED");
for (int pause = 0; pause < 30 && running.load(); ++pause) {
std::this_thread::sleep_for(std::chrono::milliseconds(100));
}
}
}
} // namespace
int main() {
std::signal(SIGINT, signal_handler);
std::signal(SIGTERM, signal_handler);
const std::string simulation = std::getenv("BALANCE_BOARD_SIMULATE")
? std::getenv("BALANCE_BOARD_SIMULATE") : "";
if (simulation == "1" || simulation == "true" || simulation == "cycle") {
simulated_loop();
return 0;
}
wiimote_t** boards = initialize_wiiuse();
PairingSharedState pairing;
const std::string configured_address = std::getenv("BALANCE_BOARD_ADDRESS")
? std::getenv("BALANCE_BOARD_ADDRESS") : "";
if (auto parsed = parse_address(configured_address)) {
pairing.commissioned_address = parsed->display;
} else {
pairing.commissioning = true;
}
const int management_fd = open_management_socket();
bool bluetooth_startup_ready = true;
std::string incoming_connection_error;
if (management_fd < 0) {
// The socket now serves both commissioning and front-button wake: it sends
// the raw six-byte PIN and keeps hci0 connectable for incoming pages. Never
// pretend an already-known address can wake reliably without it.
pairing.commissioning = false;
bluetooth_startup_ready = false;
emit_status("error", configured_address,
"Bluetooth management socket unavailable; install the worker capability");
} else if (!enable_incoming_connections(
management_fd, &incoming_connection_error)) {
bluetooth_startup_ready = false;
emit_status("error", configured_address,
"Could not enable reliable incoming Bluetooth connections on hci0: " +
incoming_connection_error);
}
std::thread commission_thread;
std::thread connection_thread;
if (bluetooth_startup_ready) {
commission_thread = std::thread(
commissioning_loop, &pairing, management_fd);
connection_thread = std::thread(direct_connection_loop, &pairing, boards);
}
std::thread input_thread(stdin_loop, &pairing);
if (bluetooth_startup_ready &&
(management_fd >= 0 || pairing.commissioned_address.has_value())) {
emit_status(pairing.commissioning ? "commissioning" : "waiting", configured_address);
}
ManagementRuntimeState management;
while (running.load()) {
process_management_events(management_fd, &pairing, &management);
std::this_thread::sleep_for(std::chrono::milliseconds(10));
}
if (management_fd >= 0) close(management_fd);
if (input_thread.joinable()) input_thread.detach();
if (commission_thread.joinable()) commission_thread.join();
if (connection_thread.joinable()) connection_thread.join();
if (boards) wiiuse_cleanup(boards, 1);
return 0;
}