presence: Fix database purge of activewatchers (clustering, no fallback2db)

When clustering sharing_tags were added to presence, they were added to
the fallback2db "on" case only:

There are a couple of dimensions with differing behaviours:

                +------------+------------+
                | fallback2- | fallback2- |
                | -db = on   | -db = off  |
  +-clustering:-+------------+------------+
  | - no        | OK         | OK         |
  | - tagless   | PR-2519    | PR-2519    |
  | - active    | OK         | this       |
  +-------------+------------+------------+

The non-OK behaviour above refers to the activewatcher table getting
filled up with stale/expired items.

fallback2db on or off:
  ```
  modparam("presence", "fallback2db", 0)  # or 1=on
  ```

The no-clustering case:
  ```
  handle_subscribe();
  ```

The tagless case:
  ```
  modparam("presence", "cluster_id", 1)
  modparam("clusterer", "my_node_id", 2)

  handle_subscribe();
  ```

The active case:
  ```
  modparam("presence", "cluster_id", 1)
  modparam("clusterer", "my_node_id", 2)
  modparam("clusterer", "sharing_tag", "node2/1=active")

  handle_subscribe("0", "node2");
  ```

Where PR OpenSIPS#2519 fixes the tagless case, this PR fixes the fallback2db=0
case by writing the sharing_tag to the database so the records can get
found and cleaned up.

(Sidenote: subscriptions which ended with a timeout or 481 *would* get
cleaned up. This makes sense in all cases: if they have an error before
their expiry, it makes sense to purge them from the DB immediately. And
the periodic cleanup had cleaned those records already, it would not be
an issue.)

Author: wdoekes

modules/presence/subscribe.c

@@ -1364,9 +1364,10 @@ void update_db_subs(db_con_t *db,db_func_t *dbf, shtable_t hash_table,
 	db_op_t update_ops[2];
 	subs_t* del_s;
 	int pres_uri_col, to_user_col, to_domain_col, from_user_col, from_domain_col,
-		callid_col, totag_col, fromtag_col, event_col,status_col, event_id_col,
+		callid_col, totag_col, fromtag_col, event_col, status_col, event_id_col,
 		local_cseq_col, remote_cseq_col, expires_col, record_route_col,
-		contact_col, local_contact_col, version_col,socket_info_col,reason_col;
+		contact_col, local_contact_col, version_col, socket_info_col,
+		sharing_tag_col, reason_col;
 	int u_expires_col, u_local_cseq_col, u_remote_cseq_col, u_version_col,
 		u_reason_col, u_status_col, u_contact_col;
 	int i;
@@ -1472,14 +1473,19 @@ void update_db_subs(db_con_t *db,db_func_t *dbf, shtable_t hash_table,
 		query_vals[local_contact_col].nul = 0;
 		n_query_cols++;
 
+		query_cols[version_col= n_query_cols]=&str_version_col;
+		query_vals[version_col].type = DB_INT;
+		query_vals[version_col].nul = 0;
+		n_query_cols++;
+
 		query_cols[socket_info_col= n_query_cols] =&str_socket_info_col;
 		query_vals[socket_info_col].type = DB_STR;
 		query_vals[socket_info_col].nul = 0;
 		n_query_cols++;
 
-		query_cols[version_col= n_query_cols]=&str_version_col;
-		query_vals[version_col].type = DB_INT;
-		query_vals[version_col].nul = 0;
+		query_cols[sharing_tag_col= n_query_cols] =&str_sharing_tag_col;
+		query_vals[sharing_tag_col].type = DB_STR;
+		query_vals[sharing_tag_col].nul = 0;
 		n_query_cols++;
 
 		/* cols and values used for update */
@@ -1639,10 +1645,16 @@ void update_db_subs(db_con_t *db,db_func_t *dbf, shtable_t hash_table,
 							query_vals[socket_info_col].val.str_val.s = 0;
 							query_vals[socket_info_col].val.str_val.len = 0;
 						}
+						if (s->sh_tag.len == 0) {
+							query_vals[sharing_tag_col].nul = 1;
+						} else {
+							query_vals[sharing_tag_col].nul = 0;
+							query_vals[sharing_tag_col].val.str_val = s->sh_tag;
+						}
 
 						CON_SET_CURR_PS(db, &my_ps_insert);
 						if (dbf->insert( db, query_cols, query_vals,
-						n_query_cols) < 0)
+								n_query_cols) < 0)
 						{
 							LM_ERR("unsuccessful sql insert\n");
 						}