From 30aaf9820dae6c4dd1657ac1b92f214560765cd6 Mon Sep 17 00:00:00 2001
From: Igor Ryzhov <iryzhov@nfware.com>
Date: Fri, 14 May 2021 01:37:38 +0300
Subject: [PATCH] Revert "bgpd: simplify bgp_global_local_as_modify code"

This reverts commit debb7b1931cdf5b3e06ca244bf09bb009b5a8677.
---
 bgpd/bgp_nb_config.c | 58 ++++++++++++++++++++++++++++++++++++--------
 1 file changed, 48 insertions(+), 10 deletions(-)

diff --git a/bgpd/bgp_nb_config.c b/bgpd/bgp_nb_config.c
index 7573c40cfa..887d6311f4 100644
--- a/bgpd/bgp_nb_config.c
+++ b/bgpd/bgp_nb_config.c
@@ -258,26 +258,64 @@ int bgp_router_destroy(struct nb_cb_destroy_args *args)
 int bgp_global_local_as_modify(struct nb_cb_modify_args *args)
 {
 	struct bgp *bgp;
+	as_t as;
+	const struct lyd_node *vrf_dnode;
+	const char *vrf_name;
+	const char *name = NULL;
+	enum bgp_instance_type inst_type;
+	int ret;
+	bool is_view_inst = false;
 
 	switch (args->event) {
 	case NB_EV_VALIDATE:
-		/*
-		 * Changing AS number is not allowed, but we must allow it
-		 * once, when the BGP instance is created the first time.
-		 * If the instance already exists - return the validation
-		 * error.
-		 */
-		bgp = nb_running_get_entry_non_rec(
-			lyd_parent(lyd_parent(args->dnode)), NULL, false);
-		if (bgp) {
+		as = yang_dnode_get_uint32(args->dnode, NULL);
+
+		inst_type = BGP_INSTANCE_TYPE_DEFAULT;
+
+		vrf_dnode = yang_dnode_get_parent(args->dnode,
+						  "control-plane-protocol");
+		vrf_name = yang_dnode_get_string(vrf_dnode, "./vrf");
+
+		if (strmatch(vrf_name, VRF_DEFAULT_NAME)) {
+			name = NULL;
+		} else {
+			name = vrf_name;
+			inst_type = BGP_INSTANCE_TYPE_VRF;
+		}
+
+		is_view_inst = yang_dnode_get_bool(args->dnode,
+						   "../instance-type-view");
+		if (is_view_inst)
+			inst_type = BGP_INSTANCE_TYPE_VIEW;
+
+		ret = bgp_lookup_by_as_name_type(&bgp, &as, name, inst_type);
+		switch (ret) {
+		case BGP_ERR_AS_MISMATCH:
 			snprintf(args->errmsg, args->errmsg_len,
-				 "Changing AS number is not allowed");
+				 "BGP instance is already running; AS is %u",
+				 as);
+			return NB_ERR_VALIDATION;
+		case BGP_ERR_INSTANCE_MISMATCH:
+			snprintf(args->errmsg, args->errmsg_len,
+				 "BGP instance type mismatch");
 			return NB_ERR_VALIDATION;
 		}
 		break;
 	case NB_EV_PREPARE:
 	case NB_EV_ABORT:
+		return NB_OK;
 	case NB_EV_APPLY:
+		/* NOTE: handled in bgp_global_create callback, the as change
+		 * will be rejected in validate phase.
+		 */
+		as = yang_dnode_get_uint32(args->dnode, NULL);
+		bgp = nb_running_get_entry(args->dnode, NULL, true);
+		if (bgp->as != as) {
+			snprintf(args->errmsg, args->errmsg_len,
+				 "BGP instance is already running; AS is %u",
+				 bgp->as);
+			return NB_ERR_INCONSISTENCY;
+		}
 		break;
 	}
 
-- 
2.39.5