Initial structure

internal/checks/icmp.go

@@ -0,0 +1,48 @@
+package checks
+
+import (
+	"context"
+	"runtime"
+	"time"
+
+	probing "github.com/prometheus-community/pro-bing"
+
+	"github.com/jasper/quptime/internal/config"
+)
+
+type icmpProber struct{}
+
+// Probe sends a single ICMP echo. On Linux we default to unprivileged
+// "udp" mode so the daemon does not require CAP_NET_RAW. Operators
+// who can grant the cap (or run as root) get raw ICMP automatically.
+func (icmpProber) Probe(ctx context.Context, c *config.Check) Result {
+	start := time.Now()
+	pinger, err := probing.NewPinger(c.Target)
+	if err != nil {
+		return Result{OK: false, Detail: "resolve: " + err.Error()}
+	}
+	pinger.Count = 1
+	pinger.Timeout = c.Timeout
+	if pinger.Timeout <= 0 {
+		pinger.Timeout = 5 * time.Second
+	}
+	pinger.SetPrivileged(runtime.GOOS != "linux")
+
+	doneCh := make(chan struct{})
+	go func() {
+		_ = pinger.RunWithContext(ctx)
+		close(doneCh)
+	}()
+	select {
+	case <-doneCh:
+	case <-ctx.Done():
+		pinger.Stop()
+		return Result{OK: false, Detail: "timeout", Latency: time.Since(start)}
+	}
+
+	stats := pinger.Statistics()
+	if stats.PacketsRecv == 0 {
+		return Result{OK: false, Detail: "no reply", Latency: time.Since(start)}
+	}
+	return Result{OK: true, Latency: stats.AvgRtt}
+}