Implement ping for tailnet

kylecarbs · kylecarbs · commit db65752d5005 · 2022-08-31T00:54:03.000Z
diff --git a/agent/agent_test.go b/agent/agent_test.go
@@ -473,13 +473,14 @@ func TestAgent(t *testing.T) {
 	t.Run("Tailnet", func(t *testing.T) {
 		t.Parallel()
 		derpMap := tailnettest.RunDERPAndSTUN(t)
-		conn := setupSSHSession(t, agent.Metadata{
+		conn := setupAgent(t, agent.Metadata{
 			DERPMap: derpMap,
-		})
+		}, 0)
 		defer conn.Close()
-		output, err := conn.CombinedOutput("echo test")
-		require.NoError(t, err)
-		t.Log(string(output))
+		require.Eventually(t, func() bool {
+			_, err := conn.Ping()
+			return err == nil
+		}, testutil.WaitMedium, testutil.IntervalFast)
 	})
 }
 
diff --git a/agent/conn.go b/agent/conn.go
@@ -15,6 +15,8 @@ import (
 
 	"golang.org/x/crypto/ssh"
 	"golang.org/x/xerrors"
+	"tailscale.com/ipn/ipnstate"
+	"tailscale.com/tailcfg"
 
 	"github.com/coder/coder/peer"
 	"github.com/coder/coder/peerbroker/proto"
@@ -139,8 +141,22 @@ type TailnetConn struct {
 	*tailnet.Conn
 }
 
-func (*TailnetConn) Ping() (time.Duration, error) {
-	return 0, nil
+func (c *TailnetConn) Ping() (time.Duration, error) {
+	errCh := make(chan error, 1)
+	durCh := make(chan time.Duration, 1)
+	c.Conn.Ping(tailnetIP, tailcfg.PingICMP, func(pr *ipnstate.PingResult) {
+		if pr.Err != "" {
+			errCh <- xerrors.New(pr.Err)
+			return
+		}
+		durCh <- time.Duration(pr.LatencySeconds * float64(time.Second))
+	})
+	select {
+	case err := <-errCh:
+		return 0, err
+	case dur := <-durCh:
+		return dur, nil
+	}
 }
 
 func (c *TailnetConn) CloseWithError(_ error) error {
