use $vn for password

initialize password variable as
variables persist in the sip process

use $vn for password which supports $null value

kamailio/pusher-role.cfg

@@ -126,7 +126,6 @@ route[PUSHER_ATTEMPT_REGISTRATION]
 
     if($hdr(X-Token-Reg) != $null) {
         if($sht(push_cache=>$hdr(X-Token-Reg)) != $null) {
-           $var(password) = $null;
            $sht(push_cache=>$hdr(X-Token-Reg)) = $null;
            xlog("L_INFO", "$ci|pusher|registration with x-token-reg $hdr(X-Token-Reg)\n");
            $xavp(ulattrs=>custom_channel_vars) = "{}";
@@ -140,7 +139,6 @@ route[PUSHER_ATTEMPT_REGISTRATION]
 
     if($(sel(contact.uri){uri.param,x-token-reg}) != "") {
         if($sht(push_cache=>$(sel(contact.uri){uri.param,x-token-reg})) != $null) {
-           $var(password) = $null;
            $sht(push_cache=>$(sel(contact.uri){uri.param,x-token-reg})) = $null;
            xlog("L_INFO", "$ci|pusher|registration with x-token-reg $(sel(contact.uri){uri.param,x-token-reg})\n");
            $xavp(ulattrs=>custom_channel_vars) = "{}";
@@ -154,7 +152,6 @@ route[PUSHER_ATTEMPT_REGISTRATION]
 
     if($(sel(contact){tobody.params}{param.value,x-token-reg}) != "") {
         if($sht(push_cache=>$(sel(contact){tobody.params}{param.value,x-token-reg})) != $null) {
-           $var(password) = $null;
            $sht(push_cache=>$(sel(contact){tobody.params}{param.value,x-token-reg})) = $null;
            xlog("L_INFO", "$ci|pusher|registration with x-token-reg $(sel(contact){tobody.params}{param.value,x-token-reg})\n");
            $xavp(ulattrs=>custom_channel_vars) = "{}";

kamailio/registrar-role.cfg

@@ -177,6 +177,7 @@ route[HANDLE_REGISTER]
         return;
     }
 
+    $vn(password) = $null;
     route_if_exists("CUSTOM_HANDLER_REGISTER");
 
     #!ifdef PUSHER_ROLE
@@ -203,7 +204,7 @@ route[HANDLE_REGISTER]
             $xavp(regcfg=>match_received) = $su;
             if(registered("location", "$rz:$Au", 2, 1) == 1) {
                if($(xavp(ulattrs=>custom_channel_vars){s.len}) > 1) {
-                  $var(password) = $sht(auth_cache=>$Au);
+                  $vn(password) = $sht(auth_cache=>$Au);
                   update_stat("registrar:cached", "+1");
                   route(SAVE_LOCATION);
                   exit;
@@ -283,7 +284,7 @@ onreply_route[KZ_AUTHORIZATION_REPLY]
     $var(delta_to_start) = $var(StartRoute) - $(kzR{kz.json,AMQP-Received});
     $var(delta_from_query) = $(kzR{kz.json,AMQP-Received}) - $xavp(deltas=>query);
     xlog("L_INFO", "$ci|log|received $(kzR{kz.json,Event-Category}) $(kzR{kz.json,Event-Name}) reply from $(kzR{kz.json,App-Name})-$(kzR{kz.json,App-Version}) (Δ1 $(kzR{kz.json,AMQP-Elapsed-Micro}) μs , Δ2 $var(delta_to_start) μs, Δ3 $var(delta_from_query) μs)\n");
-    $var(password) = $(kzR{kz.json,Auth-Password});
+    $vn(password) = $(kzR{kz.json,Auth-Password});
     $var(nonce) = $adn;
     if( $(kzR{kz.json,Event-Name}) == "authn_err" ) {
        if($(kzR{kz.json,Permanent-Error}) == "true") {
@@ -316,7 +317,7 @@ onreply_route[KZ_AUTHORIZATION_REPLY]
 route[CHECK_AUTHORIZATION]
 {
 
-    if (!pv_auth_check("$fd", "$var(password)", "0", "0")) {
+    if (!pv_auth_check("$fd", "$vn(password)", "0", "0")) {
         #!ifdef ANTIFLOOD_ROLE
         route(ANITFLOOD_FAILED_AUTH);
         #!endif
@@ -349,10 +350,10 @@ route[SUCCESS_AUTHORIZATION]
 route[SAVE_LOCATION]
 {
 
-    if ($sht(auth_cache=>$Au) == $null && $var(password) != $null) {
+    if ($sht(auth_cache=>$Au) == $null && $vn(password) != $null) {
         xlog("L_INFO", "$ci|log|caching sip credentials for $Au\n");
     };
-    $sht(auth_cache=>$Au) = $var(password);
+    $sht(auth_cache=>$Au) = $vn(password);
 
     route(REGISTRAR_NAT_FLAGS);