net/announce: Add HMP optional ID

Add the optional ID to the HMP command.

e.g.
   # start an announce for a long time on eth1
   migrate_set_parameter announce-rounds 1000
   announce_self "eth1" e1

   # start an announce on eth2
   announce_self "eth2" e2

   # Change e1 to be announcing on eth1 and eth3
   announce_self "eth1,eth3" e1

   # Cancel e1
   migrate_set_parameter announce-rounds 0
   announce_self "" e1

Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>

hmp-commands.hx

@@ -955,8 +955,8 @@ ETEXI
 
     {
         .name       = "announce_self",
-        .args_type  = "interfaces:s?",
-        .params     = "[interfaces]",
+        .args_type  = "interfaces:s?,id:s?",
+        .params     = "[interfaces] [id]",
         .help       = "Trigger GARP/RARP announcements",
         .cmd        = hmp_announce_self,
     },
@@ -968,7 +968,8 @@ Trigger a round of GARP/RARP broadcasts; this is useful for explicitly updating
 network infrastructure after a reconfiguration or some forms of migration.
 The timings of the round are set by the migration announce parameters.
 An optional comma separated @var{interfaces} list restricts the announce to the
-named set of interfaces.
+named set of interfaces. An optional @var{id} can be used to start a separate announce
+timer and to change the parameters of it later.
 ETEXI
 
     {

monitor/hmp-cmds.c

@@ -1660,12 +1660,15 @@ void hmp_info_snapshots(Monitor *mon, const QDict *qdict)
 void hmp_announce_self(Monitor *mon, const QDict *qdict)
 {
     const char *interfaces_str = qdict_get_try_str(qdict, "interfaces");
+    const char *id = qdict_get_try_str(qdict, "id");
     AnnounceParameters *params = QAPI_CLONE(AnnounceParameters,
                                             migrate_announce_params());
 
     qapi_free_strList(params->interfaces);
     params->interfaces = strList_from_comma_list(interfaces_str);
     params->has_interfaces = params->interfaces != NULL;
+    params->id = g_strdup(id);
+    params->has_id = !!params->id;
     qmp_announce_self(params, NULL);
     qapi_free_AnnounceParameters(params);
 }