relayd(8): agentx allow re-enabling

[Martijn van Duren]

Via "relayctl reload" agentx can be enabled, disabled, but if it's
enabled->disabled->enabled the final enable won't work because we
never reset the sa.

Also add an extra guard so that we don't accidentally free it
twice.

OK?

martijn@

Index: agentx_control.c
===================================================================
RCS file: /cvs/src/usr.sbin/relayd/agentx_control.c,v
retrieving revision 1.4
diff -u -p -r1.4 agentx_control.c
--- agentx_control.c    27 Oct 2020 18:48:07 -0000      1.4
+++ agentx_control.c    30 Aug 2021 10:49:49 -0000
@@ -124,7 +124,7 @@ static struct snmp_oid      hosttrapoid = {
 #define RELAYDTABLENAME                RELAYDTABLEENTRY, 2
 #define RELAYDTABLESTATUS      RELAYDTABLEENTRY, 3
 
-void agentx_needsock(struct agentx *, void *, int);
+void agentx_nofd(struct agentx *, void *, int);
 
 struct relayd *env;
 
@@ -202,6 +202,7 @@ agentx_init(struct relayd *nenv)
        struct agentx_context *sac;
        struct agentx_region *sar;
        struct agentx_index *session_idxs[2];
+       static int freed;
 
        agentx_log_fatal = fatalx;
        agentx_log_warn = log_warnx;
@@ -211,14 +212,17 @@ agentx_init(struct relayd *nenv)
        env = nenv;
 
        if ((env->sc_conf.flags & F_AGENTX) == 0) {
-               if (sa != NULL)
+               if (sa != NULL && !freed) {
                        agentx_free(sa);
+                       freed = 1;
+               }
                return;
        }
        if (sa != NULL)
                return;
 
-       if ((sa = agentx(agentx_needsock, NULL)) == NULL)
+       freed = 0;
+       if ((sa = agentx(agentx_nofd, NULL)) == NULL)
                fatal("%s: agentx alloc", __func__);
        if ((sas = agentx_session(sa, NULL, 0, "relayd", 0)) == NULL)
                fatal("%s: agentx session alloc", __func__);
@@ -420,9 +424,15 @@ agentx_init(struct relayd *nenv)
 }
 
 void
-agentx_needsock(struct agentx *usa, void *cookie, int fd)
+agentx_nofd(struct agentx *usa, void *cookie, int close)
 {
-       proc_compose(env->sc_ps, PROC_PARENT, IMSG_AGENTXSOCK, NULL, 0);
+       if (!close)
+               proc_compose(env->sc_ps, PROC_PARENT, IMSG_AGENTXSOCK, NULL, 0);
+       else {
+               sa = NULL;
+               agentx_init(env);
+               event_del(&(env->sc_agentxev));
+       }
 }
 
 void