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123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114// Copyright (c) Tailscale Inc & contributors// SPDX-License-Identifier: BSD-3-Clause
//go:build linux && !android
package tailssh
import ( "context" "os" "os/signal" "path/filepath" "strconv" "strings" "syscall" "testing" "time")
// TestMonitorWatchdogHelperProcess is re-exec'd as a monitor-owned session// or one-shot forwarding child. Both ignore parent-death SIGHUP so only// orderly monitor teardown (including its SIGKILL pass) can stop them.func TestMonitorWatchdogHelperProcess(t *testing.T) { for i, arg := range os.Args { if arg != "--" || i+2 >= len(os.Args) || os.Args[i+1] != "watchdog-helper" { continue } signal.Ignore(syscall.SIGHUP) if err := os.WriteFile(os.Args[i+2], []byte(strconv.Itoa(os.Getpid())), 0600); err != nil { os.Exit(3) } time.Sleep(25 * time.Second) os.Exit(0) }}
// TestMonitorCloseWatchdogForwardChild reproduces the case where a stalled// forwarding op consumes the watchdog before the monitor can tear down its// HUP-immune session and forwarding child groups.func TestMonitorCloseWatchdogForwardChild(t *testing.T) { markerDir := t.TempDir() forwardMarker := filepath.Join(markerDir, "forward-pid") t.Setenv("TS_TEST_SSH_FWD_PREFIX", strings.Join([]string{ "-test.run=^TestMonitorWatchdogHelperProcess$", "-test.timeout=0", "--", "watchdog-helper", forwardMarker, }, " ")) mc := startTestMonitor(t, os.Getuid(), os.Getgid(), testGroups(t))
// The session must be running and ignoring HUP before Close starts. sessionMarker := filepath.Join(markerDir, "session-pid") ctx, cancel := testCtx() session, err := mc.Exec(ctx, []string{monitorExe(t), "-test.run=^TestMonitorWatchdogHelperProcess$", "-test.timeout=0", "--", "watchdog-helper", sessionMarker}, nil, "/", false, nil) cancel() if err != nil { t.Fatalf("start session: %v", err) } defer func() { // Only signal this test's own session group, never a reused PID. if b, err := os.ReadFile(sessionMarker); err == nil && strings.TrimSpace(string(b)) == strconv.Itoa(session.PID) && !processDead(session.PID) { _ = syscall.Kill(-session.PID, syscall.SIGKILL) } }() waitWatchdogMarker(t, sessionMarker, session.PID)
requestDone := make(chan error, 1) go func() { ctx, cancel := context.WithTimeout(context.Background(), 16*time.Second) defer cancel() _, err := mc.Listen(ctx, "tcp", "127.0.0.1:0", false) requestDone <- err }() forwardPID := waitWatchdogMarker(t, forwardMarker, 0) defer func() { if !processDead(forwardPID) { _ = syscall.Kill(forwardPID, syscall.SIGKILL) } }()
start := time.Now() err = mc.Close() t.Logf("Close duration=%v error=%v; session=%d forward=%d", time.Since(start), err, session.PID, forwardPID) if err != nil { t.Errorf("monitor failed to complete teardown: %v", err) } select { case err := <-requestDone: t.Logf("inflight Listen returned: %v", err) case <-time.After(2 * time.Second): t.Error("inflight Listen did not return after Close") } if !processDead(forwardPID) { t.Errorf("HUP-immune forwarding child %d survived Close", forwardPID) } if !processDead(session.PID) { t.Errorf("HUP-immune session child %d survived Close", session.PID) }}
func waitWatchdogMarker(t *testing.T, path string, wantPID int) int { t.Helper() deadline := time.Now().Add(5 * time.Second) for time.Now().Before(deadline) { if b, err := os.ReadFile(path); err == nil { pid, err := strconv.Atoi(strings.TrimSpace(string(b))) if err != nil || pid <= 0 || (wantPID > 0 && pid != wantPID) { t.Fatalf("invalid helper PID marker %q: %q", path, b) } return pid } time.Sleep(20 * time.Millisecond) } t.Fatalf("helper did not write PID marker %q", path) return 0}