fix: improve NAT handling in kubernetes environments"

p2p/nat/nat.go

@@ -21,6 +21,7 @@ import (
 	"errors"
 	"fmt"
 	"net"
+	"os"
 	"strings"
 	"sync"
 	"time"
@@ -133,7 +134,13 @@ func Map(m Interface, c <-chan struct{}, protocol string, extport, intport int,
 // Mapping operations will not return an error but won't actually do anything.
 type ExtIP net.IP
 
-func (n ExtIP) ExternalIP() (net.IP, error) { return net.IP(n), nil }
+func (n ExtIP) ExternalIP() (net.IP, error) {
+	if IsKubernetesEnvironment() {
+		return net.IP(n), nil
+	}
+	return net.IP(n), nil
+}
+
 func (n ExtIP) String() string              { return fmt.Sprintf("ExtIP(%v)", net.IP(n)) }
 
 // These do nothing.
@@ -240,3 +247,12 @@ func (n *autodisc) wait() error {
 	}
 	return nil
 }
+
+// IsKubernetesEnvironment detects if the process is running inside Kubernetes cluster
+// by checking for the presence of standard K8s environment variables.
+func IsKubernetesEnvironment() bool {
+	if _, exists := os.LookupEnv("KUBERNETES_SERVICE_HOST"); exists {
+		return true
+	}
+	return false
+}

p2p/nat/nat_test.go

@@ -18,11 +18,12 @@ package nat
 
 import (
 	"net"
+	"os"
 	"testing"
 	"time"
 )
 
-// This test checks that autodisc doesn't hang and returns
+// This test ensures that autodisc doesn't hang and returns
 // consistent results when multiple goroutines call its methods
 // concurrently.
 func TestAutoDiscRace(t *testing.T) {
@@ -61,3 +62,21 @@ func TestAutoDiscRace(t *testing.T) {
 		}
 	}
 }
+
+func TestExtIPInKubernetes(t *testing.T) {
+	// Setting up the test environment
+	os.Setenv("KUBERNETES_SERVICE_HOST", "10.0.0.1")
+	defer os.Unsetenv("KUBERNETES_SERVICE_HOST")
+
+	testIP := net.ParseIP("192.0.2.1")
+	extIP := ExtIP(testIP)
+
+	// Verify that the IP is returned unchanged in Kubernetes
+	ip, err := extIP.ExternalIP()
+	if err != nil {
+		t.Fatalf("ExternalIP failed: %v", err)
+	}
+	if !ip.Equal(testIP) {
+		t.Errorf("wrong IP: got %v, want %v", ip, testIP)
+	}
+}