fix: detect JetBrains running on local ipv6 (#11653)

agent/agent_test.go

@@ -214,46 +214,59 @@ func TestAgent_Stats_Magic(t *testing.T) {
 		_, b, _, ok := runtime.Caller(0)
 		require.True(t, ok)
 		dir := filepath.Join(filepath.Dir(b), "../scripts/echoserver/main.go")
-		echoServerCmd := exec.Command("go", "run", dir,
-			"-D", agentssh.MagicProcessCmdlineJetBrains)
-		stdout, err := echoServerCmd.StdoutPipe()
-		require.NoError(t, err)
-		err = echoServerCmd.Start()
-		require.NoError(t, err)
-		defer echoServerCmd.Process.Kill()
 
-		// The echo server prints its port as the first line.
+		spawnServer := func(network string) (string, *exec.Cmd) {
-		sc := bufio.NewScanner(stdout)
+			echoServerCmd := exec.Command("go", "run", dir,
-		sc.Scan()
+				network, "-D", agentssh.MagicProcessCmdlineJetBrains)
-		remotePort := sc.Text()
+			stdout, err := echoServerCmd.StdoutPipe()
+			require.NoError(t, err)
+			err = echoServerCmd.Start()
+			require.NoError(t, err)
+			t.Cleanup(func() {
+				echoServerCmd.Process.Kill()
+			})
+
+			// The echo server prints its port as the first line.
+			sc := bufio.NewScanner(stdout)
+			sc.Scan()
+			return sc.Text(), echoServerCmd
+		}
+
+		port4, cmd4 := spawnServer("tcp4")
+		port6, cmd6 := spawnServer("tcp6")
 
 		//nolint:dogsled
 		conn, _, stats, _, _ := setupAgent(t, agentsdk.Manifest{}, 0)
+		defer conn.Close()
+
 		sshClient, err := conn.SSHClient(ctx)
 		require.NoError(t, err)
 
-		tunneledConn, err := sshClient.Dial("tcp", fmt.Sprintf("127.0.0.1:%s", remotePort))
+		tunnel4, err := sshClient.Dial("tcp4", fmt.Sprintf("127.0.0.1:%s", port4))
 		require.NoError(t, err)
-		t.Cleanup(func() {
+		defer tunnel4.Close()
-			// always close on failure of test
+
-			_ = conn.Close()
+		tunnel6, err := sshClient.Dial("tcp6", fmt.Sprintf("[::]:%s", port6))
-			_ = tunneledConn.Close()
+		require.NoError(t, err)
-		})
+		defer tunnel6.Close()
 
 		require.Eventuallyf(t, func() bool {
 			s, ok := <-stats
 			t.Logf("got stats with conn open: ok=%t, ConnectionCount=%d, SessionCountJetBrains=%d",
 				ok, s.ConnectionCount, s.SessionCountJetBrains)
 			return ok && s.ConnectionCount > 0 &&
-				s.SessionCountJetBrains == 1
+				s.SessionCountJetBrains == 2
 		}, testutil.WaitLong, testutil.IntervalFast,
 			"never saw stats with conn open",
 		)
 
 		// Kill the server and connection after checking for the echo.
-		requireEcho(t, tunneledConn)
+		requireEcho(t, tunnel4)
-		_ = echoServerCmd.Process.Kill()
+		requireEcho(t, tunnel6)
-		_ = tunneledConn.Close()
+		_ = cmd4.Process.Kill()
+		_ = cmd6.Process.Kill()
+		_ = tunnel4.Close()
+		_ = tunnel6.Close()
 
 		require.Eventuallyf(t, func() bool {
 			s, ok := <-stats

agent/agentssh/portinspection_supported.go

@@ -3,6 +3,7 @@
 package agentssh
 
 import (
+	"errors"
 	"fmt"
 	"os"
 
@@ -11,24 +12,33 @@ import (
 )
 
 func getListeningPortProcessCmdline(port uint32) (string, error) {
-	tabs, err := netstat.TCPSocks(func(s *netstat.SockTabEntry) bool {
+	acceptFn := func(s *netstat.SockTabEntry) bool {
 		return s.LocalAddr != nil && uint32(s.LocalAddr.Port) == port
-	})
-	if err != nil {
-		return "", xerrors.Errorf("inspect port %d: %w", port, err)
 	}
-	if len(tabs) == 0 {
+	tabs, err := netstat.TCPSocks(acceptFn)
-		return "", nil
+	tabs6, err6 := netstat.TCP6Socks(acceptFn)
+
+	// Only return the error if the other method found nothing.
+	if (err != nil && len(tabs6) == 0) || (err6 != nil && len(tabs) == 0) {
+		return "", xerrors.Errorf("inspect port %d: %w", port, errors.Join(err, err6))
 	}
 
-	// Defensive check.
+	var proc *netstat.Process
-	if tabs[0].Process == nil {
+	if len(tabs) > 0 {
+		proc = tabs[0].Process
+	} else if len(tabs6) > 0 {
+		proc = tabs6[0].Process
+	}
+	if proc == nil {
+		// Either nothing is listening on this port or we were unable to read the
+		// process details (permission issues reading /proc/$pid/* potentially).
+		// Or, perhaps /proc/net/tcp{,6} is not listing the port for some reason.
 		return "", nil
 	}
 
 	// The process name provided by go-netstat does not include the full command
 	// line so grab that instead.
-	pid := tabs[0].Process.Pid
+	pid := proc.Pid
 	data, err := os.ReadFile(fmt.Sprintf("/proc/%d/cmdline", pid))
 	if err != nil {
 		return "", xerrors.Errorf("read /proc/%d/cmdline: %w", pid, err)

scripts/echoserver/main.go

@@ -9,10 +9,21 @@ import (
 	"io"
 	"log"
 	"net"
+	"os"
 )
 
 func main() {
-	l, err := net.Listen("tcp", "127.0.0.1:0")
+	network := os.Args[1]
+	var address string
+	switch network {
+	case "tcp4":
+		address = "127.0.0.1"
+	case "tcp6":
+		address = "[::]"
+	default:
+		log.Fatalf("invalid network: %s", network)
+	}
+	l, err := net.Listen(network, address+":0")
 	if err != nil {
 		log.Fatalf("listen error: err=%s", err)
 	}