f-21: lib: add ebatable wrapper

Signed-off-by: GnomeZworc <nicolas.boufidjeline@g3e.fr>

internal/ebtables/ebtables.go

@@ -0,0 +1,58 @@
+package ebtables
+
+import (
+	"fmt"
+	"os/exec"
+)
+
+func addRule(args ...string) error {
+	return exec.Command("ebtables", append([]string{"-A"}, args...)...).Run()
+}
+
+func deleteRule(args ...string) error {
+	return exec.Command("ebtables", append([]string{"-D"}, args...)...).Run()
+}
+
+func DropARPToGateway(bridge, gatewayIP string) error {
+	if err := addRule("FORWARD",
+		"--out-interface", bridge,
+		"-p", "arp",
+		"--arp-op", "Request",
+		"--arp-ip-dst", gatewayIP,
+		"-j", "DROP"); err != nil {
+		return fmt.Errorf("ebtables arp rule: %w", err)
+	}
+	return nil
+}
+
+func DropDHCP(bridge string) error {
+	if err := addRule("FORWARD",
+		"--out-interface", bridge,
+		"-p", "IPv4",
+		"--ip-protocol", "udp",
+		"--ip-source-port", "67:68",
+		"--ip-destination-port", "67:68",
+		"-j", "DROP"); err != nil {
+		return fmt.Errorf("ebtables dhcp rule: %w", err)
+	}
+	return nil
+}
+
+func DeleteARPToGateway(bridge, gatewayIP string) error {
+	return deleteRule("FORWARD",
+		"--out-interface", bridge,
+		"-p", "arp",
+		"--arp-op", "Request",
+		"--arp-ip-dst", gatewayIP,
+		"-j", "DROP")
+}
+
+func DeleteDHCP(bridge string) error {
+	return deleteRule("FORWARD",
+		"--out-interface", bridge,
+		"-p", "IPv4",
+		"--ip-protocol", "udp",
+		"--ip-source-port", "67:68",
+		"--ip-destination-port", "67:68",
+		"-j", "DROP")
+}