From 7cf60fd0bdaa45311eea886cee6d1f290a4ac2d2 Mon Sep 17 00:00:00 2001
From: Gabriel Goller <g.goller@proxmox.com>
Date: Tue, 25 Feb 2025 10:13:34 +0100
Subject: [PATCH 4/6] zebra: add ZEBRA_IF_DUMMY flag for dummy interfaces

Introduce ZEBRA_IF_DUMMY interface flag to identify Linux dummy interfaces [0].
These interfaces behave similarly to loopback interfaces and can be
specially handled by daemons.

[0]: https://github.com/torvalds/linux/blob/master/drivers/net/dummy.c

Link: https://github.com/FRRouting/frr/pull/18242
Signed-off-by: Gabriel Goller <g.goller@proxmox.com>
---
 lib/if.h               | 1 +
 zebra/if_netlink.c     | 3 +++
 zebra/interface.c      | 7 +++++++
 zebra/interface.h      | 6 +++++-
 zebra/zebra_nb_state.c | 3 +++
 5 files changed, 19 insertions(+), 1 deletion(-)

Index: b/lib/if.h
===================================================================
--- a/lib/if.h	2025-03-07 11:09:47.571424092 +0100
+++ b/lib/if.h	2025-03-07 11:09:47.568424088 +0100
@@ -242,6 +242,7 @@
 #define ZEBRA_INTERFACE_SUB        (1 << 1)
 #define ZEBRA_INTERFACE_LINKDETECTION (1 << 2)
 #define ZEBRA_INTERFACE_VRF_LOOPBACK (1 << 3)
+#define ZEBRA_INTERFACE_DUMMY (1 << 4)
 
 	/* Interface flags. */
 	uint64_t flags;
Index: b/zebra/if_netlink.c
===================================================================
--- a/zebra/if_netlink.c	2025-03-07 11:09:47.571424092 +0100
+++ b/zebra/if_netlink.c	2025-03-07 11:09:47.568424088 +0100
@@ -221,6 +221,8 @@
 		*zif_type = ZEBRA_IF_BOND;
 	else if (strcmp(kind, "gre") == 0)
 		*zif_type = ZEBRA_IF_GRE;
+	else if (strcmp(kind, "dummy") == 0)
+		*zif_type = ZEBRA_IF_DUMMY;
 }
 
 static void netlink_vrf_change(struct nlmsghdr *h, struct rtattr *tb,
@@ -576,6 +578,7 @@
 	case ZEBRA_IF_MACVLAN:
 	case ZEBRA_IF_VETH:
 	case ZEBRA_IF_BOND:
+	case ZEBRA_IF_DUMMY:
 		break;
 	}
 }
Index: b/zebra/interface.c
===================================================================
--- a/zebra/interface.c	2025-03-07 11:09:47.571424092 +0100
+++ b/zebra/interface.c	2025-03-07 11:09:47.568424088 +0100
@@ -584,6 +584,9 @@
 
 	zebra_interface_add_update(ifp);
 
+	if (IS_ZEBRA_IF_DUMMY(ifp))
+		SET_FLAG(ifp->status, ZEBRA_INTERFACE_DUMMY);
+
 	if (!CHECK_FLAG(ifp->status, ZEBRA_INTERFACE_ACTIVE)) {
 		SET_FLAG(ifp->status, ZEBRA_INTERFACE_ACTIVE);
 
@@ -1646,6 +1649,7 @@
 	case ZEBRA_IF_MACVLAN:
 	case ZEBRA_IF_VETH:
 	case ZEBRA_IF_BOND:
+	case ZEBRA_IF_DUMMY:
 		break;
 	}
 }
@@ -2398,6 +2402,9 @@
 	case ZEBRA_IF_GRE:
 		return "GRE";
 
+	case ZEBRA_IF_DUMMY:
+		return "dummy";
+
 	default:
 		return "Unknown";
 	}
Index: b/zebra/interface.h
===================================================================
--- a/zebra/interface.h	2025-03-07 11:09:47.571424092 +0100
+++ b/zebra/interface.h	2025-03-07 11:09:47.569424090 +0100
@@ -39,7 +39,8 @@
 	ZEBRA_IF_MACVLAN,   /* MAC VLAN interface*/
 	ZEBRA_IF_VETH,      /* VETH interface*/
 	ZEBRA_IF_BOND,	    /* Bond */
-	ZEBRA_IF_GRE,      /* GRE interface */
+	ZEBRA_IF_GRE,       /* GRE interface */
+	ZEBRA_IF_DUMMY,     /* Dummy interface */
 };
 
 /* Zebra "slave" interface type */
@@ -246,6 +247,9 @@
 #define IS_ZEBRA_IF_GRE(ifp)                                               \
 	(((struct zebra_if *)(ifp->info))->zif_type == ZEBRA_IF_GRE)
 
+#define IS_ZEBRA_IF_DUMMY(ifp)                                               \
+	(((struct zebra_if *)(ifp->info))->zif_type == ZEBRA_IF_DUMMY)
+
 #define IS_ZEBRA_IF_BRIDGE_SLAVE(ifp)					\
 	(((struct zebra_if *)(ifp->info))->zif_slave_type                      \
 	 == ZEBRA_IF_SLAVE_BRIDGE)
Index: b/zebra/zebra_nb_state.c
===================================================================
--- a/zebra/zebra_nb_state.c	2025-03-07 11:09:47.571424092 +0100
+++ b/zebra/zebra_nb_state.c	2025-03-07 11:09:47.569424090 +0100
@@ -87,6 +87,9 @@
 	case ZEBRA_IF_GRE:
 		type = "frr-zebra:zif-gre";
 		break;
+	case ZEBRA_IF_DUMMY:
+		type = "frr-zebra:zif-dummy";
+		break;
 	}
 
 	if (!type)