[dispatcher] Fix hackish extraction of TO URI upon pinging

Better use the URI stored in callback params, rather then using the hackish way of extracting the URI from the T-stored To hdr.

This is a side effect of 9af1926
Reported by @denyspozniak
Closes #3000

modules/dispatcher/dispatch.c

@@ -2599,9 +2599,7 @@ int ds_print_mi_list(mi_item_t *part_item, ds_partition_t *partition, int full)
 static void ds_options_callback( struct cell *t, int type,
 		struct tmcb_params *ps )
 {
-	str uri = {0, 0};
-
-	/* The Param does contain the group, in which the failed host
+	/* The Param contains the URI+ group, in which the failed host
 	 * can be found.*/
 	if (!ps->param) {
 		LM_DBG("No parameter provided, OPTIONS-Request was finished"
@@ -2615,27 +2613,22 @@ static void ds_options_callback( struct cell *t, int type,
 	ds_options_callback_param_t *cb_param =
 		(ds_options_callback_param_t*)(*ps->param);
 
-	/* The SIP-URI is taken from the Transaction.
-	 * Remove the "To: " (s+4) and the trailing new-line (s - 4 (To: )
-	 * - 2 (\r\n)). */
-	uri.s = t->to.s + 4;
-	uri.len = t->to.len - 6;
 	LM_DBG("OPTIONS-Request was finished with code %d (to %.*s, group %d)\n",
-			ps->code, uri.len, uri.s, cb_param->set_id);
+			ps->code, cb_param->uri.len, cb_param->uri.s, cb_param->set_id);
 
 	/* ps->code contains the result-code of the request;
 	 * We accept "200 OK" by default and the custom codes
 	 * defined in options_reply_codes parameter*/
 	if ((ps->code == 200) || check_options_rplcode(ps->code)) {
 		/* Set the according entry back to "Active":
 		 *  remove the Probing/Inactive Flag and reset the failure counter. */
-		if (ds_set_state(cb_param->set_id, &uri,
+		if (ds_set_state(cb_param->set_id, &cb_param->uri,
 			DS_INACTIVE_DST|DS_PROBING_DST|DS_RESET_FAIL_DST, 0,
 			cb_param->partition, 1, 0, MI_SSTR("200 OK probing reply")
 					) != 0)
 		{
-			LM_ERR("Setting the state failed (%.*s, group %d)\n", uri.len,
-					uri.s, cb_param->set_id);
+			LM_ERR("Setting the state failed (%.*s, group %d)\n",
+				cb_param->uri.len, cb_param->uri.s, cb_param->set_id);
 		}
 	}
 	/* if we always probe, and we get a timeout
@@ -2644,11 +2637,11 @@ static void ds_options_callback( struct cell *t, int type,
 	if((ds_probing_mode==1 || cb_param->always_probe) && ps->code != 200 &&
 	(ps->code == 408 || !check_options_rplcode(ps->code)))
 	{
-		if (ds_set_state(cb_param->set_id, &uri, DS_PROBING_DST, 1,
+		if (ds_set_state(cb_param->set_id, &cb_param->uri, DS_PROBING_DST, 1,
 			cb_param->partition, 1, 0, MI_SSTR("negative probing reply")) != 0)
 		{
 			LM_ERR("Setting the probing state failed (%.*s, group %d)\n",
-					uri.len, uri.s, cb_param->set_id);
+				cb_param->uri.len, cb_param->uri.s, cb_param->set_id);
 		}
 	}
 
@@ -2668,7 +2661,6 @@ void ds_check_timer(unsigned int ticks, void* param)
 		ds_options_callback_param_t params;
 
 		struct socket_info *sock;
-		str uri;
 		struct usr_avp *avps;
 
 		struct gw_prob_pack *next;
@@ -2732,11 +2724,6 @@ void ds_check_timer(unsigned int ticks, void* param)
 						break;
 					}
 
-					pack->uri.s = (char*)(pack+1);
-					memcpy(pack->uri.s, list->dlist[j].uri.s,
-						list->dlist[j].uri.len);
-					pack->uri.len = list->dlist[j].uri.len;
-
 					pack->sock = list->dlist[j].sock;
 
 					if (partition->attrs_avp_name>=0) {
@@ -2751,6 +2738,11 @@ void ds_check_timer(unsigned int ticks, void* param)
 					} else
 						pack->avps = NULL;
 
+					pack->params.uri.s = (char*)(pack+1);
+					memcpy(pack->params.uri.s, list->dlist[j].uri.s,
+						list->dlist[j].uri.len);
+					pack->params.uri.len = list->dlist[j].uri.len;
+
 					pack->params.partition = partition;
 					pack->params.set_id = list->id;
 					pack->params.always_probe =
@@ -2778,7 +2770,7 @@ void ds_check_timer(unsigned int ticks, void* param)
 			/* Execute the Dialog using the "request"-Method of the
 			 * TM-Module.*/
 			if (tmb.new_auto_dlg_uac(&ds_ping_from,
-			&pack->uri, NULL, NULL,
+			&pack->params.uri, NULL, NULL,
 			pack->sock?pack->sock:probing_sock,
 			&dlg) != 0 ) {
 				LM_ERR("failed to create new TM dlg\n");

modules/dispatcher/dispatch.h

@@ -164,6 +164,8 @@ typedef struct
 	ds_partition_t *partition;
 	int set_id;
 	int always_probe;
+	str uri; /* Note: the URI string is allocated together with
+	          * this structure, so no need of separate freeing */
 } ds_options_callback_param_t;
 
 typedef struct _ds_selected_dst