1 files changed, 108 insertions, 0 deletions
diff --git a/tests/e2e/sharing_test.go b/tests/e2e/sharing_test.go
new file mode 100644
index 0000000..b0971f9
--- /dev/null
+++ b/tests/e2e/sharing_test.go
@@ -0,0 +1,108 @@
+package e2e
+
+import (
+	"bufio"
+	"fmt"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"strings"
+	"testing"
+)
+
+func TestNamespaceSharing(t *testing.T) {
+	binaryPath, err := GetBinaryPath()
+	if err != nil {
+		t.Skipf("Skipping test: %v", err)
+	}
+
+	tmpRuntimeDir := t.TempDir()
+	tmpConfigDir := t.TempDir()
+	profile := "sharing-test"
+
+	// Write a valid dummy profile so it doesn't run in bare isolation
+	profilesDir := filepath.Join(tmpConfigDir, "wg-wrap", "profiles")
+	if err := os.MkdirAll(profilesDir, 0755); err != nil {
+		t.Fatal(err)
+	}
+	profileConfPath := filepath.Join(profilesDir, profile+".conf")
+	conf := `[Interface]
+Address = 10.0.0.2/24
+PrivateKey = 0000000000000000000000000000000000000000000000000000000000000000
+DNS = 1.1.1.1
+
+[Peer]
+PublicKey = 0000000000000000000000000000000000000000000000000000000000000000
+AllowedIPs = 0.0.0.0/0
+Endpoint = 1.1.1.1:51820
+`
+	if err := os.WriteFile(profileConfPath, []byte(conf), 0644); err != nil {
+		t.Fatal(err)
+	}
+
+	pidsDir := filepath.Join(tmpRuntimeDir, "profiles", profile, "pids")
+
+	// Start Process A running a command that outputs its netns and sleeps
+	cmdA := exec.Command(binaryPath, "--profile", profile, "--", "sh", "-c", "readlink /proc/self/ns/net && sleep 5")
+	cmdA.Env = append(os.Environ(),
+		fmt.Sprintf("XDG_RUNTIME_DIR=%s", tmpRuntimeDir),
+		fmt.Sprintf("XDG_CONFIG_HOME=%s", tmpConfigDir),
+	)
+
+	outA, err := cmdA.StdoutPipe()
+	if err != nil {
+		t.Fatalf("Failed to create stdout pipe for Process A: %v", err)
+	}
+
+	if err := cmdA.Start(); err != nil {
+		t.Fatalf("Failed to start Process A: %v", err)
+	}
+	defer func() { _ = cmdA.Process.Kill() }()
+
+	// Wait for Process A to output its netns ID line by line
+	var parsedNetnsA string
+	scannerA := bufio.NewScanner(outA)
+	for scannerA.Scan() {
+		line := strings.TrimSpace(scannerA.Text())
+		if strings.HasPrefix(line, "net:[") {
+			parsedNetnsA = line
+			break
+		}
+	}
+
+	if parsedNetnsA == "" {
+		t.Fatalf("Failed to get netns ID from Process A")
+	}
+
+	// Wait for Process A's PID to be registered on the host
+	waitForPids(t, pidsDir, 1)
+
+	// Start Process B to check its netns ID
+	cmdB := exec.Command(binaryPath, "--profile", profile, "--", "readlink", "/proc/self/ns/net")
+	cmdB.Env = append(os.Environ(),
+		fmt.Sprintf("XDG_RUNTIME_DIR=%s", tmpRuntimeDir),
+		fmt.Sprintf("XDG_CONFIG_HOME=%s", tmpConfigDir),
+	)
+
+	outB, err := cmdB.CombinedOutput()
+	if err != nil {
+		t.Fatalf("Process B failed to execute: %v\nOutput: %s", err, string(outB))
+	}
+
+	var parsedNetnsB string
+	for _, line := range strings.Split(string(outB), "\n") {
+		trimmed := strings.TrimSpace(line)
+		if strings.HasPrefix(trimmed, "net:[") {
+			parsedNetnsB = trimmed
+			break
+		}
+	}
+
+	if parsedNetnsB == "" {
+		t.Fatalf("Invalid netns ID format from Process B: %q", string(outB))
+	}
+
+	if parsedNetnsA != parsedNetnsB {
+		t.Errorf("BUG: Process A and Process B do not share the same network namespace!\nProcess A: %s\nProcess B: %s", parsedNetnsA, parsedNetnsB)
+	}
+}