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https://github.com/fosrl/newt.git
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Add wgtester
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347
wgtester/wgtester.go
Normal file
347
wgtester/wgtester.go
Normal file
@@ -0,0 +1,347 @@
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package wgtester
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import (
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"context"
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"encoding/binary"
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"log"
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"net"
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"sync"
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"time"
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)
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const (
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// Magic bytes to identify our packets
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magicHeader uint32 = 0xDEADBEEF
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// Request packet type
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packetTypeRequest uint8 = 1
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// Response packet type
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packetTypeResponse uint8 = 2
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// Packet format:
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// - 4 bytes: magic header (0xDEADBEEF)
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// - 1 byte: packet type (1 = request, 2 = response)
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// - 8 bytes: timestamp (for round-trip timing)
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packetSize = 13
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)
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// Server handles listening for connection check requests
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type Server struct {
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conn *net.UDPConn
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listenAddr string
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shutdownCh chan struct{}
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isRunning bool
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runningLock sync.Mutex
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}
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// NewServer creates a new connection test server
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func NewServer(listenAddr string) *Server {
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return &Server{
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listenAddr: listenAddr,
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shutdownCh: make(chan struct{}),
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}
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}
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// Start begins listening for connection test packets
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func (s *Server) Start() error {
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s.runningLock.Lock()
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defer s.runningLock.Unlock()
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if s.isRunning {
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return nil
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}
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addr, err := net.ResolveUDPAddr("udp", s.listenAddr)
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if err != nil {
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return err
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}
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s.conn, err = net.ListenUDP("udp", addr)
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if err != nil {
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return err
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}
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s.isRunning = true
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go s.handleConnections()
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log.Printf("Server listening on %s", s.listenAddr)
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return nil
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}
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// Stop shuts down the server
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func (s *Server) Stop() {
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s.runningLock.Lock()
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defer s.runningLock.Unlock()
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if !s.isRunning {
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return
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}
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close(s.shutdownCh)
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if s.conn != nil {
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s.conn.Close()
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}
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s.isRunning = false
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log.Println("Server stopped")
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}
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// handleConnections processes incoming packets
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func (s *Server) handleConnections() {
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buffer := make([]byte, packetSize)
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for {
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select {
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case <-s.shutdownCh:
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return
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default:
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// Set read deadline to avoid blocking forever
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s.conn.SetReadDeadline(time.Now().Add(1 * time.Second))
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n, addr, err := s.conn.ReadFromUDP(buffer)
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if err != nil {
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if netErr, ok := err.(net.Error); ok && netErr.Timeout() {
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// Just a timeout, keep going
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continue
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}
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log.Printf("Error reading from UDP: %v", err)
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continue
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}
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if n != packetSize {
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continue // Ignore malformed packets
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}
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// Check magic header
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magic := binary.BigEndian.Uint32(buffer[0:4])
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if magic != magicHeader {
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continue // Not our packet
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}
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// Check packet type
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packetType := buffer[4]
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if packetType != packetTypeRequest {
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continue // Not a request packet
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}
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// Keep the timestamp the same (for RTT calculation)
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// Just change the packet type to response
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buffer[4] = packetTypeResponse
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// Send response
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_, err = s.conn.WriteToUDP(buffer, addr)
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if err != nil {
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log.Printf("Error sending response: %v", err)
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}
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}
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}
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}
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// Client handles checking connectivity to a server
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type Client struct {
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conn *net.UDPConn
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serverAddr string
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monitorRunning bool
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monitorLock sync.Mutex
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shutdownCh chan struct{}
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packetInterval time.Duration
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timeout time.Duration
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maxAttempts int
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}
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// ConnectionStatus represents the current connection state
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type ConnectionStatus struct {
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Connected bool
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RTT time.Duration
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}
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// NewClient creates a new connection test client
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func NewClient(serverAddr string) (*Client, error) {
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return &Client{
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serverAddr: serverAddr,
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shutdownCh: make(chan struct{}),
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packetInterval: 2 * time.Second,
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timeout: 500 * time.Millisecond, // Timeout for individual packets
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maxAttempts: 3, // Default max attempts
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}, nil
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}
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// SetPacketInterval changes how frequently packets are sent in monitor mode
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func (c *Client) SetPacketInterval(interval time.Duration) {
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c.packetInterval = interval
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}
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// SetTimeout changes the timeout for waiting for responses
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func (c *Client) SetTimeout(timeout time.Duration) {
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c.timeout = timeout
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}
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// SetMaxAttempts changes the maximum number of attempts for TestConnection
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func (c *Client) SetMaxAttempts(attempts int) {
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c.maxAttempts = attempts
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}
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// Close cleans up client resources
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func (c *Client) Close() {
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c.StopMonitor()
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if c.conn != nil {
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c.conn.Close()
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c.conn = nil
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}
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}
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// ensureConnection makes sure we have an active UDP connection
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func (c *Client) ensureConnection() error {
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if c.conn != nil {
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return nil
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}
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serverAddr, err := net.ResolveUDPAddr("udp", c.serverAddr)
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if err != nil {
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return err
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}
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c.conn, err = net.DialUDP("udp", nil, serverAddr)
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if err != nil {
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return err
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}
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return nil
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}
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// TestConnection checks if the connection to the server is working
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// Returns true if connected, false otherwise
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func (c *Client) TestConnection(ctx context.Context) (bool, time.Duration) {
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if err := c.ensureConnection(); err != nil {
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return false, 0
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}
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// Prepare packet buffer
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packet := make([]byte, packetSize)
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binary.BigEndian.PutUint32(packet[0:4], magicHeader)
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packet[4] = packetTypeRequest
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// Send multiple attempts as specified
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for attempt := 0; attempt < c.maxAttempts; attempt++ {
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select {
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case <-ctx.Done():
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return false, 0
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default:
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// Add current timestamp to packet
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timestamp := time.Now().UnixNano()
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binary.BigEndian.PutUint64(packet[5:13], uint64(timestamp))
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// Send the packet
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_, err := c.conn.Write(packet)
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if err != nil {
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log.Printf("Error sending packet: %v", err)
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continue
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}
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// Set read deadline
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c.conn.SetReadDeadline(time.Now().Add(c.timeout))
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// Wait for response
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responseBuffer := make([]byte, packetSize)
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n, err := c.conn.Read(responseBuffer)
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if err != nil {
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if netErr, ok := err.(net.Error); ok && netErr.Timeout() {
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// Timeout, try next attempt
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time.Sleep(100 * time.Millisecond) // Brief pause between attempts
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continue
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}
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log.Printf("Error reading response: %v", err)
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continue
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}
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if n != packetSize {
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continue // Malformed packet
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}
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// Verify response
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magic := binary.BigEndian.Uint32(responseBuffer[0:4])
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packetType := responseBuffer[4]
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if magic != magicHeader || packetType != packetTypeResponse {
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continue // Not our response
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}
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// Extract the original timestamp and calculate RTT
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sentTimestamp := int64(binary.BigEndian.Uint64(responseBuffer[5:13]))
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rtt := time.Duration(time.Now().UnixNano() - sentTimestamp)
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return true, rtt
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}
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}
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return false, 0
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}
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// TestConnectionWithTimeout tries to test connection with a timeout
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// Returns true if connected, false otherwise
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func (c *Client) TestConnectionWithTimeout(timeout time.Duration) (bool, time.Duration) {
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ctx, cancel := context.WithTimeout(context.Background(), timeout)
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defer cancel()
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return c.TestConnection(ctx)
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}
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// MonitorCallback is the function type for connection status change callbacks
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type MonitorCallback func(status ConnectionStatus)
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// StartMonitor begins monitoring the connection and calls the callback
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// when the connection status changes
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func (c *Client) StartMonitor(callback MonitorCallback) error {
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c.monitorLock.Lock()
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defer c.monitorLock.Unlock()
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if c.monitorRunning {
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return nil // Already running
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}
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if err := c.ensureConnection(); err != nil {
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return err
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}
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c.monitorRunning = true
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c.shutdownCh = make(chan struct{})
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go func() {
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var lastConnected bool
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firstRun := true
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ticker := time.NewTicker(c.packetInterval)
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defer ticker.Stop()
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for {
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select {
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case <-c.shutdownCh:
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return
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case <-ticker.C:
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ctx, cancel := context.WithTimeout(context.Background(), c.timeout)
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connected, rtt := c.TestConnection(ctx)
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cancel()
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// Callback if status changed or it's the first check
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if connected != lastConnected || firstRun {
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callback(ConnectionStatus{
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Connected: connected,
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RTT: rtt,
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})
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lastConnected = connected
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firstRun = false
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}
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}
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}
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}()
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return nil
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}
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// StopMonitor stops the connection monitoring
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func (c *Client) StopMonitor() {
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c.monitorLock.Lock()
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defer c.monitorLock.Unlock()
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if !c.monitorRunning {
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return
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}
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close(c.shutdownCh)
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c.monitorRunning = false
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}
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