*: convert zclient callbacks to table

This removes a giant `switch { }` block from lib/zclient.c and
harmonizes all zclient callback function types to be the same (some had
a subset of the args, some had a void return, now they all have
ZAPI_CALLBACK_ARGS and int return.)

Apart from getting rid of the giant switch, this is a minor security
benefit since the function pointers are now in a `const` array, so they
can't be overwritten by e.g. heap overflows for code execution anymore.

Signed-off-by: David Lamparter <equinox@opensourcerouting.org>

3 files changed, 25 insertions, 18 deletions

diff --git a/nhrpd/netlink_arp.c b/nhrpd/netlink_arp.c
index 0a618056d5..3658cb16bb 100644
--- a/nhrpd/netlink_arp.c
+++ b/nhrpd/netlink_arp.c
@@ -147,7 +147,7 @@ void netlink_set_nflog_group(int nlgroup)
 	}
 }
 
-void nhrp_neighbor_operation(ZAPI_CALLBACK_ARGS)
+int nhrp_neighbor_operation(ZAPI_CALLBACK_ARGS)
 {
 	union sockunion addr = {}, lladdr = {};
 	struct interface *ifp;
@@ -157,7 +157,7 @@ void nhrp_neighbor_operation(ZAPI_CALLBACK_ARGS)
 
 	zclient_neigh_ip_decode(zclient->ibuf, &api);
 	if (api.ip_in.ipa_type == AF_UNSPEC)
-		return;
+		return 0;
 	sockunion_family(&addr) = api.ip_in.ipa_type;
 	memcpy((uint8_t *)sockunion_get_addr(&addr), &api.ip_in.ip.addr,
 	       family2addrsize(api.ip_in.ipa_type));
@@ -172,10 +172,10 @@ void nhrp_neighbor_operation(ZAPI_CALLBACK_ARGS)
 	ndm_state = api.ndm_state;
 
 	if (!ifp)
-		return;
+		return 0;
 	c = nhrp_cache_get(ifp, &addr, 0);
 	if (!c)
-		return;
+		return 0;
 	debugf(NHRP_DEBUG_KERNEL,
 	       "Netlink: %s %pSU dev %s lladdr %pSU nud 0x%x cache used %u type %u",
 	       (cmd == ZEBRA_NHRP_NEIGH_GET)
@@ -200,4 +200,5 @@ void nhrp_neighbor_operation(ZAPI_CALLBACK_ARGS)
 			: ZEBRA_NEIGH_STATE_FAILED;
 		nhrp_cache_set_used(c, state == ZEBRA_NEIGH_STATE_REACHABLE);
 	}
+	return 0;
 }
diff --git a/nhrpd/nhrp_route.c b/nhrpd/nhrp_route.c
index 12a2fc2fa0..76e0978cb6 100644
--- a/nhrpd/nhrp_route.c
+++ b/nhrpd/nhrp_route.c
@@ -366,21 +366,25 @@ static void nhrp_zebra_connected(struct zclient *zclient)
 	nhrp_zebra_register_neigh(VRF_DEFAULT, AFI_IP6, true);
 }
 
+static zclient_handler *const nhrp_handlers[] = {
+	[ZEBRA_INTERFACE_ADDRESS_ADD] = nhrp_interface_address_add,
+	[ZEBRA_INTERFACE_ADDRESS_DELETE] = nhrp_interface_address_delete,
+	[ZEBRA_REDISTRIBUTE_ROUTE_ADD] = nhrp_route_read,
+	[ZEBRA_REDISTRIBUTE_ROUTE_DEL] = nhrp_route_read,
+	[ZEBRA_NHRP_NEIGH_ADDED] = nhrp_neighbor_operation,
+	[ZEBRA_NHRP_NEIGH_REMOVED] = nhrp_neighbor_operation,
+	[ZEBRA_NHRP_NEIGH_GET] = nhrp_neighbor_operation,
+	[ZEBRA_GRE_UPDATE] = nhrp_gre_update,
+};
+
 void nhrp_zebra_init(void)
 {
 	zebra_rib[AFI_IP] = route_table_init();
 	zebra_rib[AFI_IP6] = route_table_init();
 
-	zclient = zclient_new(master, &zclient_options_default);
+	zclient = zclient_new(master, &zclient_options_default, nhrp_handlers,
+			      array_size(nhrp_handlers));
 	zclient->zebra_connected = nhrp_zebra_connected;
-	zclient->interface_address_add = nhrp_interface_address_add;
-	zclient->interface_address_delete = nhrp_interface_address_delete;
-	zclient->redistribute_route_add = nhrp_route_read;
-	zclient->redistribute_route_del = nhrp_route_read;
-	zclient->neighbor_added = nhrp_neighbor_operation;
-	zclient->neighbor_removed = nhrp_neighbor_operation;
-	zclient->neighbor_get = nhrp_neighbor_operation;
-	zclient->gre_update = nhrp_gre_update;
 	zclient_init(zclient, ZEBRA_ROUTE_NHRP, 0, &nhrpd_privs);
 }
 
@@ -476,7 +480,7 @@ void nhrp_zebra_terminate(void)
 	route_table_finish(zebra_rib[AFI_IP6]);
 }
 
-void nhrp_gre_update(ZAPI_CALLBACK_ARGS)
+int nhrp_gre_update(ZAPI_CALLBACK_ARGS)
 {
 	struct stream *s;
 	struct nhrp_gre_info gre_info, *val;
@@ -485,7 +489,7 @@ void nhrp_gre_update(ZAPI_CALLBACK_ARGS)
 	/* result */
 	s = zclient->ibuf;
 	if (vrf_id != VRF_DEFAULT)
-		return;
+		return 0;
 
 	/* read GRE information */
 	STREAM_GETL(s, gre_info.ifindex);
@@ -516,7 +520,9 @@ void nhrp_gre_update(ZAPI_CALLBACK_ARGS)
 	       ifp ? ifp->name : "<none>", gre_info.ifindex, vrf_id);
 	if (ifp)
 		nhrp_interface_update_nbma(ifp, val);
-	return;
+	return 0;
+
 stream_failure:
 	zlog_err("%s(): error reading response ..", __func__);
+	return -1;
 }
diff --git a/nhrpd/nhrpd.h b/nhrpd/nhrpd.h
index 17abb04762..96caa39040 100644
--- a/nhrpd/nhrpd.h
+++ b/nhrpd/nhrpd.h
@@ -363,8 +363,8 @@ int nhrp_interface_up(ZAPI_CALLBACK_ARGS);
 int nhrp_interface_down(ZAPI_CALLBACK_ARGS);
 int nhrp_interface_address_add(ZAPI_CALLBACK_ARGS);
 int nhrp_interface_address_delete(ZAPI_CALLBACK_ARGS);
-void nhrp_neighbor_operation(ZAPI_CALLBACK_ARGS);
-void nhrp_gre_update(ZAPI_CALLBACK_ARGS);
+int nhrp_neighbor_operation(ZAPI_CALLBACK_ARGS);
+int nhrp_gre_update(ZAPI_CALLBACK_ARGS);
 
 void nhrp_interface_notify_add(struct interface *ifp, struct notifier_block *n,
 			       notifier_fn_t fn);