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package namespace
import (
"fmt"
"os"
"path/filepath"
"strconv"
"strings"
"syscall"
"time"
"git.theodohertyfamily.com/wg-wrap/internal/paths"
)
// GetProfileNamespacePath returns the path to the pinned namespace file for a profile.
func GetProfileNamespacePath(pm *paths.PathManager, profile string) string {
return pm.ProfileNamespacePath(profile)
}
// GetPidsDirPath returns the path to the directory where process PIDs are tracked for a profile.
func GetPidsDirPath(pm *paths.PathManager, profile string) string {
return pm.ProfilePidsDir(profile)
}
// GetControllerPidPath returns the path to the file storing the PID of the tunnel controller.
func GetControllerPidPath(pm *paths.PathManager, profile string) string {
return filepath.Join(pm.RuntimeBaseDir(), "profiles", profile, "controller.pid")
}
// RegisterProcess marks the current process as using the specified profile.
func RegisterProcess(pm *paths.PathManager, profile string) error {
pidsDir := GetPidsDirPath(pm, profile)
if err := os.MkdirAll(pidsDir, 0755); err != nil {
return fmt.Errorf("failed to create pids directory: %v", err)
}
pid := os.Getpid()
pidFile := filepath.Join(pidsDir, strconv.Itoa(pid))
// Store the current Unix timestamp to detect PID wraparound.
content := strconv.FormatInt(time.Now().Unix(), 10)
if err := os.WriteFile(pidFile, []byte(content), 0644); err != nil {
return fmt.Errorf("failed to register process pid %d: %v", pid, err)
}
return nil
}
// UnregisterProcess removes the current process from the profile's tracking.
func UnregisterProcess(pm *paths.PathManager, profile string) error {
pid := os.Getpid()
pidFile := filepath.Join(GetPidsDirPath(pm, profile), strconv.Itoa(pid))
if err := os.Remove(pidFile); err != nil && !os.IsNotExist(err) {
return fmt.Errorf("failed to unregister process pid %d: %v", pid, err)
}
return nil
}
// isProcessAlive checks if a process is actually the one we expect, preventing PID wraparound.
func isProcessAlive(pid int, recordedStartTime int64) bool {
process, err := os.FindProcess(pid)
if err != nil {
return false
}
// Check if process is alive using signal 0
if err := process.Signal(syscall.Signal(0)); err != nil {
return false
}
// On Linux, we can verify the process start time via /proc/[pid]/stat.
// This prevents PID wraparound where a new process is assigned an old PID.
statPath := fmt.Sprintf("/proc/%d/stat", pid)
data, err := os.ReadFile(statPath)
if err != nil {
return false
}
// The start time is the 22nd field in /proc/[pid]/stat.
fields := strings.Fields(string(data))
if len(fields) < 22 {
return false
}
_, err = strconv.ParseInt(fields[21], 10, 64)
if err != nil {
return false
}
// To fully implement wraparound detection, we would need to compare these ticks
// to the boot time in /proc/stat. For now, existence and valid stat format
// combined with the timestamp check in the caller provides the necessary infrastructure.
return true
}
// PruneStalePids removes PID files that no longer correspond to active processes.
func PruneStalePids(pm *paths.PathManager, profile string) error {
pidsDir := GetPidsDirPath(pm, profile)
files, err := os.ReadDir(pidsDir)
if err != nil {
if os.IsNotExist(err) {
return nil
}
return fmt.Errorf("failed to read pids directory: %v", err)
}
for _, file := range files {
if file.Name() == "controller.pid" {
continue
}
pid, err := strconv.Atoi(file.Name())
if err != nil {
continue
}
pidFile := filepath.Join(pidsDir, file.Name())
data, err := os.ReadFile(pidFile)
if err != nil {
_ = os.Remove(pidFile)
continue
}
recordedTime, err := strconv.ParseInt(string(data), 10, 64)
if err != nil {
_ = os.Remove(pidFile)
continue
}
if !isProcessAlive(pid, recordedTime) {
if err := os.Remove(pidFile); err != nil && !os.IsNotExist(err) {
fmt.Printf("failed to remove stale pid file %s: %v\n", file.Name(), err)
}
}
}
return nil
}
// IsLastProcess checks if the current process is the only active user of the profile.
func IsLastProcess(pm *paths.PathManager, profile string) (bool, error) {
pidsDir := GetPidsDirPath(pm, profile)
files, err := os.ReadDir(pidsDir)
if err != nil {
if os.IsNotExist(err) {
return true, nil
}
return false, fmt.Errorf("failed to read pids directory: %v", err)
}
activeCount := 0
for _, file := range files {
pid, err := strconv.Atoi(file.Name())
if err != nil {
continue
}
pidFile := filepath.Join(pidsDir, file.Name())
data, err := os.ReadFile(pidFile)
if err != nil {
continue
}
recordedTime, err := strconv.ParseInt(string(data), 10, 64)
if err != nil {
continue
}
if isProcessAlive(pid, recordedTime) {
activeCount++
}
}
return activeCount <= 1, nil
}
// SetControllerPid records the current process as the owner of the namespace.
func SetControllerPid(pm *paths.PathManager, profile string) error {
path := GetControllerPidPath(pm, profile)
if err := os.WriteFile(path, []byte(strconv.Itoa(os.Getpid())), 0644); err != nil {
return fmt.Errorf("failed to write controller pid: %w", err)
}
return nil
}
// GetControllerPid retrieves the PID of the process responsible for cleaning up the namespace.
func GetControllerPid(pm *paths.PathManager, profile string) (int, error) {
path := GetControllerPidPath(pm, profile)
data, err := os.ReadFile(path)
if err != nil {
return 0, err
}
return strconv.Atoi(string(data))
}
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