*: Modify agentx to be allowed to be called

If you had a situation where an operator turned on
ospfd with snmp but not ospf6d and agentx was configured
then you get into a situation where ospf6d would complain
that the config for agentx did not exist.  Let's modify
the code to allow this situation to happen.

Fixes: #15896
Signed-off-by: Donald Sharp <sharpd@nvidia.com>

14 files changed, 109 insertions, 35 deletions

diff --git a/bgpd/bgp_main.c b/bgpd/bgp_main.c
index 44d5ee68cc..2bbd3a4b1b 100644
--- a/bgpd/bgp_main.c
+++ b/bgpd/bgp_main.c
@@ -26,6 +26,7 @@
 #include "bfd.h"
 #include "libfrr.h"
 #include "ns.h"
+#include "libagentx.h"
 
 #include "bgpd/bgpd.h"
 #include "bgpd/bgp_attr.h"
@@ -516,8 +517,10 @@ int main(int argc, char **argv)
 		bgp_option_set(BGP_OPT_NO_ZEBRA);
 	bgp_error_init();
 	/* Initializations. */
+	libagentx_init();
 	bgp_vrf_init();
 
+
 #ifdef HAVE_SCRIPTING
 	bgp_script_init();
 #endif
diff --git a/eigrpd/eigrp_main.c b/eigrpd/eigrp_main.c
index d387b9be18..319ac92533 100644
--- a/eigrpd/eigrp_main.c
+++ b/eigrpd/eigrp_main.c
@@ -36,6 +36,7 @@
 #include "distribute.h"
 #include "libfrr.h"
 #include "routemap.h"
+#include "libagentx.h"
 //#include "if_rmap.h"
 
 #include "eigrpd/eigrp_structs.h"
@@ -178,9 +179,11 @@ int main(int argc, char **argv, char **envp)
 
 	/* EIGRP master init. */
 	eigrp_master_init();
+
 	eigrp_om->master = frr_init();
 	master = eigrp_om->master;
 
+	libagentx_init();
 	eigrp_error_init();
 	eigrp_vrf_init();
 	vrf_init(NULL, NULL, NULL, NULL);
diff --git a/isisd/isis_main.c b/isisd/isis_main.c
index 60ec8cdad4..8dd3a97aa1 100644
--- a/isisd/isis_main.c
+++ b/isisd/isis_main.c
@@ -28,6 +28,7 @@
 #include "libfrr.h"
 #include "routemap.h"
 #include "affinitymap.h"
+#include "libagentx.h"
 
 #include "isisd/isis_affinitymap.h"
 #include "isisd/isis_constants.h"
@@ -307,6 +308,7 @@ int main(int argc, char **argv, char **envp)
 	/*
 	 *  initializations
 	 */
+	libagentx_init();
 	cmd_init_config_callbacks(isis_config_start, isis_config_end);
 	isis_error_init();
 	access_list_init();
diff --git a/ldpd/ldpd.c b/ldpd/ldpd.c
index 492a36b3d6..4d38fdcd02 100644
--- a/ldpd/ldpd.c
+++ b/ldpd/ldpd.c
@@ -36,6 +36,7 @@
 #include "libfrr.h"
 #include "lib_errors.h"
 #include "zlog_recirculate.h"
+#include "libagentx.h"
 
 static void		 ldpd_shutdown(void);
 static pid_t		 start_child(enum ldpd_process, char *, int, int, int);
@@ -370,6 +371,7 @@ main(int argc, char *argv[])
 	zlog_recirculate_subscribe(master, pipe_lde_log[0]);
 	zlog_recirculate_subscribe(master, pipe_ldpe_log[0]);
 
+	libagentx_init();
 	vrf_init(NULL, NULL, NULL, NULL);
 	access_list_init();
 	ldp_vty_init();
diff --git a/lib/agentx.c b/lib/agentx.c
index 70ee6753ff..19f2a6b7fc 100644
--- a/lib/agentx.c
+++ b/lib/agentx.c
@@ -22,12 +22,13 @@
 #include "hook.h"
 #include "libfrr.h"
 #include "xref.h"
+#include "lib/libagentx.h"
 
 XREF_SETUP();
 
 DEFINE_HOOK(agentx_enabled, (), ());
 
-static bool agentx_enabled = false;
+//bool agentx_enabled = false;
 
 static struct event_loop *agentx_tm;
 static struct event *timeout_thr = NULL;
@@ -153,15 +154,6 @@ static void agentx_events_update(void)
 	netsnmp_large_fd_set_cleanup(&lfds);
 }
 
-/* AgentX node. */
-static int config_write_agentx(struct vty *vty);
-static struct cmd_node agentx_node = {
-	.name = "smux",
-	.node = SMUX_NODE,
-	.prompt = "",
-	.config_write = config_write_agentx,
-};
-
 /* Logging NetSNMP messages */
 static int agentx_log_callback(int major, int minor, void *serverarg,
 			       void *clientarg)
@@ -201,17 +193,7 @@ static int agentx_log_callback(int major, int minor, void *serverarg,
 	return SNMP_ERR_NOERROR;
 }
 
-static int config_write_agentx(struct vty *vty)
-{
-	if (agentx_enabled)
-		vty_out(vty, "agentx\n");
-	return 1;
-}
-
-DEFUN (agentx_enable,
-       agentx_enable_cmd,
-       "agentx",
-       "SNMP AgentX protocol settings\n")
+static int agentx_cli_on(void)
 {
 	if (!agentx_enabled) {
 		init_snmp(FRR_SMUX_NAME);
@@ -221,19 +203,14 @@ DEFUN (agentx_enable,
 		hook_call(agentx_enabled);
 	}
 
-	return CMD_SUCCESS;
+	return 1;
 }
 
-DEFUN (no_agentx,
-       no_agentx_cmd,
-       "no agentx",
-       NO_STR
-       "SNMP AgentX protocol settings\n")
+static int agentx_cli_off(void)
 {
 	if (!agentx_enabled)
-		return CMD_SUCCESS;
-	vty_out(vty, "SNMP AgentX support cannot be disabled once enabled\n");
-	return CMD_WARNING_CONFIG_FAILED;
+		return 1;
+	return 0;
 }
 
 static int smux_disable(void)
@@ -252,6 +229,9 @@ void smux_init(struct event_loop *tm)
 {
 	agentx_tm = tm;
 
+	hook_register(agentx_cli_enabled, agentx_cli_on);
+	hook_register(agentx_cli_disabled, agentx_cli_off);
+
 	netsnmp_enable_subagent();
 	snmp_disable_log();
 	snmp_enable_calllog();
@@ -259,10 +239,6 @@ void smux_init(struct event_loop *tm)
 			       agentx_log_callback, NULL);
 	init_agent(FRR_SMUX_NAME);
 
-	install_node(&agentx_node);
-	install_element(CONFIG_NODE, &agentx_enable_cmd);
-	install_element(CONFIG_NODE, &no_agentx_cmd);
-
 	hook_register(frr_early_fini, smux_disable);
 }
 
diff --git a/lib/libagentx.c b/lib/libagentx.c
new file mode 100644
index 0000000000..23826572ed
--- /dev/null
+++ b/lib/libagentx.c
@@ -0,0 +1,63 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/* SNMP cli support
+ * Copyright (C) 2024 Donald Sharp <sharpd@nvidia.com> NVIDIA Corporation
+ */
+#include <zebra.h>
+
+#include "lib/hook.h"
+#include "lib/libagentx.h"
+#include "command.h"
+
+DEFINE_HOOK(agentx_cli_enabled, (), ());
+DEFINE_HOOK(agentx_cli_disabled, (), ());
+
+bool agentx_enabled;
+
+/* AgentX node. */
+static int config_write_agentx(struct vty *vty)
+{
+	if (agentx_enabled)
+		vty_out(vty, "agentx\n");
+	return 1;
+}
+
+static struct cmd_node agentx_node = {
+	.name = "smux",
+	.node = SMUX_NODE,
+	.prompt = "",
+	.config_write = config_write_agentx,
+};
+
+DEFUN(agentx_enable, agentx_enable_cmd, "agentx",
+      "SNMP AgentX protocol settings\n")
+{
+	if (!hook_have_hooks(agentx_cli_enabled)) {
+		zlog_info(
+			"agentx specified but the agentx Module is not loaded, is this intentional?");
+
+		return CMD_SUCCESS;
+	}
+
+	hook_call(agentx_cli_enabled);
+
+	return CMD_SUCCESS;
+}
+
+DEFUN(no_agentx, no_agentx_cmd, "no agentx",
+      NO_STR "SNMP AgentX protocol settings\n")
+{
+	vty_out(vty, "SNMP AgentX support cannot be disabled once enabled\n");
+	if (!hook_call(agentx_cli_disabled))
+		return CMD_WARNING_CONFIG_FAILED;
+
+	return CMD_SUCCESS;
+}
+
+void libagentx_init(void)
+{
+	agentx_enabled = false;
+
+	install_node(&agentx_node);
+	install_element(CONFIG_NODE, &agentx_enable_cmd);
+	install_element(CONFIG_NODE, &no_agentx_cmd);
+}
diff --git a/lib/libagentx.h b/lib/libagentx.h
new file mode 100644
index 0000000000..c3246d975f
--- /dev/null
+++ b/lib/libagentx.h
@@ -0,0 +1,14 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/* SNMP cli support
+ * Copyright (C) 2024 Donald Sharp <sharpd@nvidia.com> NVIDIA Corporation
+ */
+#ifndef __LIBAGENTX_H__
+#define __LIBAGENTX_H__
+
+extern void libagentx_init(void);
+extern bool agentx_enabled;
+
+DECLARE_HOOK(agentx_cli_enabled, (), ());
+DECLARE_HOOK(agentx_cli_disabled, (), ());
+
+#endif
diff --git a/lib/smux.h b/lib/smux.h
index cec4d2a1bf..8ec847afd0 100644
--- a/lib/smux.h
+++ b/lib/smux.h
@@ -99,6 +99,7 @@ struct index_oid {
  */
 extern bool smux_enabled(void);
 
+extern void libagentx_init(void);
 extern void smux_init(struct event_loop *tm);
 extern void smux_agentx_enable(void);
 extern void smux_register_mib(const char *, struct variable *, size_t, int,
diff --git a/lib/subdir.am b/lib/subdir.am
index 221c0b1e1d..3264f31af7 100644
--- a/lib/subdir.am
+++ b/lib/subdir.am
@@ -58,6 +58,7 @@ lib_libfrr_la_SOURCES = \
 	lib/ldp_sync.c \
 	lib/lib_errors.c \
 	lib/lib_vty.c \
+	lib/libagentx.c \
 	lib/libfrr.c \
 	lib/libfrr_trace.c \
 	lib/linklist.c \
@@ -252,6 +253,7 @@ pkginclude_HEADERS += \
 	lib/ldp_sync.h \
 	lib/lib_errors.h \
 	lib/lib_vty.h \
+	lib/libagentx.h \
 	lib/libfrr.h \
 	lib/libfrr_trace.h \
 	lib/libospf.h \
diff --git a/ospf6d/ospf6_main.c b/ospf6d/ospf6_main.c
index abd4320335..8320f11f6c 100644
--- a/ospf6d/ospf6_main.c
+++ b/ospf6d/ospf6_main.c
@@ -24,6 +24,7 @@
 #include "vrf.h"
 #include "bfd.h"
 #include "libfrr.h"
+#include "libagentx.h"
 
 #include "ospf6d.h"
 #include "ospf6_top.h"
@@ -266,6 +267,7 @@ int main(int argc, char *argv[], char *envp[])
 	/* thread master */
 	master = om6->master;
 
+	libagentx_init();
 	keychain_init();
 	ospf6_vrf_init();
 	access_list_init();
diff --git a/ospfd/ospf_main.c b/ospfd/ospf_main.c
index 9e97abba1c..fdb4e5c587 100644
--- a/ospfd/ospf_main.c
+++ b/ospfd/ospf_main.c
@@ -28,6 +28,7 @@
 #include "libfrr.h"
 #include "routemap.h"
 #include "keychain.h"
+#include "libagentx.h"
 
 #include "ospfd/ospfd.h"
 #include "ospfd/ospf_interface.h"
@@ -256,6 +257,7 @@ int main(int argc, char **argv)
 	master = om->master;
 
 	/* Library inits. */
+	libagentx_init();
 	ospf_debug_init();
 	ospf_vrf_init();
 
diff --git a/python/xref2vtysh.py b/python/xref2vtysh.py
index 177de757b0..75d9ccf367 100644
--- a/python/xref2vtysh.py
+++ b/python/xref2vtysh.py
@@ -32,7 +32,7 @@ frr_top_src = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))
 # not quite obvious...
 
 daemon_flags = {
-    "lib/agentx.c": "VTYSH_ISISD|VTYSH_RIPD|VTYSH_OSPFD|VTYSH_OSPF6D|VTYSH_BGPD|VTYSH_ZEBRA",
+    "lib/libagentx.c": "VTYSH_ISISD|VTYSH_RIPD|VTYSH_OSPFD|VTYSH_OSPF6D|VTYSH_BGPD|VTYSH_ZEBRA",
     "lib/filter.c": "VTYSH_ACL_SHOW",
     "lib/filter_cli.c": "VTYSH_ACL_CONFIG",
     "lib/if.c": "VTYSH_INTERFACE",
diff --git a/ripd/rip_main.c b/ripd/rip_main.c
index 734e7ac4d9..67469f5fe5 100644
--- a/ripd/rip_main.c
+++ b/ripd/rip_main.c
@@ -23,6 +23,7 @@
 #include "routemap.h"
 #include "bfd.h"
 #include "mgmt_be_client.h"
+#include "libagentx.h"
 
 #include "ripd/ripd.h"
 #include "ripd/rip_bfd.h"
@@ -190,6 +191,7 @@ int main(int argc, char **argv)
 	master = frr_init();
 
 	/* Library initialization. */
+	libagentx_init();
 	rip_error_init();
 	keychain_init_new(true);
 	rip_vrf_init();
diff --git a/zebra/main.c b/zebra/main.c
index d83f1d0491..ea1e1cbdbb 100644
--- a/zebra/main.c
+++ b/zebra/main.c
@@ -26,6 +26,7 @@
 #include "routemap.h"
 #include "routing_nb.h"
 #include "mgmt_be_client.h"
+#include "libagentx.h"
 
 #include "zebra/zebra_router.h"
 #include "zebra/zebra_errors.h"
@@ -435,6 +436,7 @@ int main(int argc, char **argv)
 	zrouter.master = frr_init();
 
 	/* Zebra related initialize. */
+	libagentx_init();
 	zebra_router_init(asic_offload, notify_on_ack, v6_with_v4_nexthop);
 	zserv_init();
 	zebra_rib_init();