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//go:build linux
package namespace
import (
"fmt"
"os"
"path/filepath"
"strconv"
"git.theodohertyfamily.com/wg-wrap/internal/paths"
"golang.org/x/sys/unix"
)
// PinNamespace binds the current network namespace to the profile's namespace path.
// This prevents the kernel from destroying the namespace when all processes exit.
func PinNamespace(pm *paths.PathManager, profile string) error {
nsPath := GetProfileNamespacePath(pm, profile)
profilesDir := filepath.Dir(nsPath)
if err := os.MkdirAll(profilesDir, 0755); err != nil {
return fmt.Errorf("failed to create profiles directory: %w", err)
}
// 1. Create an empty file to serve as the mount point
if err := os.WriteFile(nsPath, []byte(""), 0644); err != nil {
return fmt.Errorf("failed to create namespace pin file: %w", err)
}
// 2. Bind-mount the current network namespace to the file.
// This increments the kernel's reference count for the namespace.
if err := unix.Mount("/proc/self/ns/net", nsPath, "", unix.MS_BIND, ""); err != nil {
return fmt.Errorf("failed to bind-mount network namespace: %w", err)
}
return nil
}
// UnpinNamespace unmounts and removes the pinned namespace file.
func UnpinNamespace(pm *paths.PathManager, profile string) error {
nsPath := GetProfileNamespacePath(pm, profile)
if _, err := os.Stat(nsPath); os.IsNotExist(err) {
return nil
}
// 1. Unmount the namespace first.
// If this is the last reference to the namespace, the kernel will destroy it.
if err := unix.Unmount(nsPath, 0); err != nil {
return fmt.Errorf("failed to unmount namespace %s: %w", nsPath, err)
}
// 2. Remove the mount point file.
if err := os.Remove(nsPath); err != nil {
return fmt.Errorf("failed to remove pin file %s: %w", nsPath, err)
}
pidsDir := GetPidsDirPath(pm, profile)
// Try to remove pids directory and empty parent directories
_ = os.Remove(pidsDir)
_ = os.Remove(filepath.Dir(pidsDir))
_ = os.Remove(filepath.Dir(filepath.Dir(pidsDir)))
return nil
}
// FindActiveProfilePid looks for an active PID running under the specified profile.
// Returns 0 if no active process is found.
func FindActiveProfilePid(pm *paths.PathManager, profile string) (int, error) {
if err := PruneStalePids(pm, profile); err != nil {
return 0, fmt.Errorf("failed to prune stale pids: %w", err)
}
pidsDir := GetPidsDirPath(pm, profile)
files, err := os.ReadDir(pidsDir)
if err != nil {
if os.IsNotExist(err) {
return 0, nil
}
return 0, fmt.Errorf("failed to read pids dir: %w", err)
}
for _, file := range files {
pid, err := strconv.Atoi(file.Name())
if err != nil {
continue
}
// Since we already pruned stale pids, the first file we find is an active pid!
return pid, nil
}
return 0, nil
}
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