only add k-cid header if it doesn't exist already

* initiators can provide k-cid

kamailio/presence-fast-pickup.cfg

@@ -60,7 +60,9 @@ route[PRESENCE_FAST_PICKUP_ATTEMPT]
            route(PRESENCE_FAST_PICKUP_OPTION);
            $du = $sht(fp=>$var(md5));
            append_hf("Replaces: $var(replaced_call_id)$var(Pickup)\r\n");
-           append_hf("k-cid: $var(replaced_call_id)\r\n");
+           if(!is_present_hf("k-cid")) {
+               append_hf("k-cid: $var(replaced_call_id)\r\n");
+           }
            xlog("L_INFO", "$ci|log|fast|found shortcut for call-id $var(replaced_call_id) , redirecting ($(ru{uri.user})) to $du\n");
            route(RELAY);
            exit();
@@ -88,7 +90,9 @@ route[PRESENCE_FAST_PICKUP_ATTEMPT]
                   }
                   remove_hf_re("^Replaces");
                   append_hf("Replaces: $var(rep)\r\n");
-                  append_hf("k-cid: $var(replaced_call_id)\r\n");
+                  if(!is_present_hf("k-cid")) {
+                      append_hf("k-cid: $var(replaced_call_id)\r\n");
+                  }
                   xlog("L_INFO", "$ci|log|call-id $var(replaced_call_id) found, redirecting call ($(ru{uri.user})) to $du => $var(rep)\n");
                   route(RELAY);
                   exit();
@@ -109,7 +113,9 @@ route[PRESENCE_FAST_PICKUP_ATTEMPT]
            $var(park) = $_s(*3$(ru{uri.user}{s.substr,2,0})@$(ru{uri.domain}));
            if($sht(park=>$var(park)) != $null) {
                $du = $sht(park=>$var(park));
-               append_hf("k-cid: $sht(park=>$var(park)::callid)\r\n");
+               if(!is_present_hf("k-cid")) {
+                   append_hf("k-cid: $sht(park=>$var(park)::callid)\r\n");
+               }
                xlog("L_INFO", "$ci|log|redirecting park request to $du , callid : $sht(park=>$var(park)::callid)\n");
                route(RELAY);
                exit();
@@ -119,7 +125,9 @@ route[PRESENCE_FAST_PICKUP_ATTEMPT]
 
     if($sht(park=>$(ru{uri.user})@$(ru{uri.domain})) != $null) {
        $du = $sht(park=>$(ru{uri.user})@$(ruri{uri.domain}));
-       append_hf("k-cid: $sht(park=>$(ru{uri.user})@$(ruri{uri.domain})::callid)\r\n");
+       if(!is_present_hf("k-cid")) {
+           append_hf("k-cid: $sht(park=>$(ru{uri.user})@$(ruri{uri.domain})::callid)\r\n");
+       }       
        xlog("L_INFO", "$ci|log|redirecting park request to $du, callid: $sht(park=>$(ru{uri.user})@$(ruri{uri.domain})::callid)\n");
        route(RELAY);
        exit();
@@ -138,7 +146,9 @@ route[PRESENCE_FAST_PICKUP_ATTEMPT]
             $du = $(kzR{kz.json,Channels[0].switch_url});
             if($du != $null) {
                xlog("L_INFO", "$ci|log|redirecting park request to $du from realtime query reply\n");
-               append_hf("k-cid: $(kzR{kz.json,Channels[0].call_id})\r\n");
+               if(!is_present_hf("k-cid")) {
+                   append_hf("k-cid: $(kzR{kz.json,Channels[0].call_id})\r\n");
+               }       
                route(RELAY);
                exit();
             }