confd: add support for dummy interfaces

Dummy interfaces are useful for configuring routes and testing network
services without having to allocate physical or virtual interfaces.

Signed-off-by: Joachim Wiberg <troglobit@gmail.com>

src/confd/src/ietf-interfaces.c

@@ -227,6 +227,8 @@ static int ifchange_cand_infer_type(sr_session_ctx_t *session, const char *path)
 		inferred.data.string_val = "infix-if-type:bridge";
 	else if (!fnmatch("docker+([0-9])", ifname, FNM_EXTMATCH))
 		inferred.data.string_val = "infix-if-type:bridge";
+	else if (!fnmatch("dummy+([0-9])", ifname, FNM_EXTMATCH))
+		inferred.data.string_val = "infix-if-type:dummy";
 	else if (!fnmatch("podman+([0-9])", ifname, FNM_EXTMATCH))
 		inferred.data.string_val = "infix-if-type:bridge";
 	else if (!fnmatch("lag+([0-9])", ifname, FNM_EXTMATCH))
@@ -1522,6 +1524,16 @@ out:
 	return err;
 }
 
+static int netdag_gen_dummy(struct dagger *net, struct lyd_node *dif,
+			    struct lyd_node *cif, FILE *ip)
+{
+	const char *ifname = lydx_get_cattr(cif, "name");
+
+	fprintf(ip, "link add dev %s type dummy\n", ifname);
+
+	return 0;
+}
+
 static int netdag_gen_veth(struct dagger *net, struct lyd_node *dif,
 			   struct lyd_node *cif, FILE *ip)
 {
@@ -1665,6 +1677,8 @@ static int netdag_gen_afspec_add(sr_session_ctx_t *session, struct dagger *net,
 
 	if (!strcmp(iftype, "infix-if-type:bridge")) {
 		err = netdag_gen_bridge(session, net, dif, cif, ip, 1);
+	} else if (!strcmp(iftype, "infix-if-type:dummy")) {
+		err = netdag_gen_dummy(net, NULL, cif, ip);
 	} else if (!strcmp(iftype, "infix-if-type:veth")) {
 		err = netdag_gen_veth(net, NULL, cif, ip);
 	} else if (!strcmp(iftype, "infix-if-type:vlan")) {

src/confd/yang/confd.inc

@@ -26,7 +26,7 @@ MODULES=(
 	"infix-hardware@2024-04-25.yang"
 	"ieee802-dot1q-types@2022-10-29.yang"
 	"infix-ip@2024-09-16.yang"
-	"infix-if-type@2024-01-29.yang"
+	"infix-if-type@2024-10-13.yang"
 	"infix-routing@2024-10-01.yang"
 	"ieee802-dot1ab-lldp@2022-03-15.yang"
 	"infix-lldp@2023-08-23.yang"

src/confd/yang/infix-if-type.yang

@@ -11,15 +11,20 @@ module infix-if-type {
   contact      "kernelkit@googlegroups.com";
   description  "Infix extensions to IANA interfaces types";
 
-  revision 2023-08-21 {
-    description "Add infix-inteface-type to reduce number of supported
-                 interfaces.  The derived identities are based on both
-                 this new identity and their parent iana-if-type.";
+  revision 2024-10-13 {
+    description "Add new interface type dummy.";
     reference "internal";
   }
 
   revision 2024-01-29 {
-    description "Add new interface type etherlike";
+    description "Add new interface type etherlike.";
+    reference "internal";
+  }
+
+  revision 2023-08-21 {
+    description "Add infix-inteface-type to reduce number of supported
+                 interfaces.  The derived identities are based on both
+                 this new identity and their parent iana-if-type.";
     reference "internal";
   }
 
@@ -42,6 +47,11 @@ module infix-if-type {
     base ianaift:bridge;
     description "IEEE bridge interface.";
   }
+  identity dummy {
+    base infix-interface-type;
+    base ianaift:other;
+    description "Linux dummy interface.  Useful mostly for testing.";
+  }
   identity ethernet {
     base infix-interface-type;
     base ianaift:ethernetCsmacd;

src/statd/python/yanger/yanger.py

@@ -45,6 +45,9 @@ def json_get_yang_type(iface_in):
     if iface_in['linkinfo']['info_kind'] == "dsa":
         return "infix-if-type:ethernet"
 
+    if iface_in['linkinfo']['info_kind'] == "dummy":
+        return "infix-if-type:dummy"
+
     # Fallback
     return "infix-if-type:ethernet"