cachedb_redis: Fix a bug with parsing custom ports

This patch fixes an issue where custom Redis ports (i.e. not
6379) in simple URLs with just 1 host were always being parsed as 6379.
Most likely, the issue dates back to the "circular failover hosts"
feature (6917928).

Many thanks to Artiom Druz (@Shkiperion) for a full report + PR attempt!

Fixes OpenSIPS#3168
Closes OpenSIPS#3169

Author: liviuchircu

cachedb/test/test_cachedb.c

@@ -765,6 +765,15 @@ static void test_cachedb_url(void)
 	ok(!db->database);
 	ok(!db->extra_options);
 
+	CDB_PARSE("redis://:[email protected]:6380/1");
+	ok(db->flags == 0);
+	ok(!strcmp(db->username, ""));
+	ok(!strcmp(db->password, "pwd"));
+	ok(!strcmp(db->host, "172.31.180.127"));
+	ok(db->port == 6380);
+	ok(!strcmp(db->database, "1"));
+	ok(!db->extra_options);
+
 	CDB_PARSE("redis:group1://:[email protected]:6379/d?x=1&q=2");
 	ok(db->flags == 0);
 	ok(!strcmp(db->username, ""));

modules/cachedb_redis/cachedb_redis_dbase.c

@@ -399,9 +399,23 @@ redis_con* redis_new_connection(struct cachedb_id* id)
 
 		memset(con,0,sizeof(redis_con));
 
-		if (redis_get_hostport(&it->s, &con->host, &con->port) != 0) {
-			LM_ERR("no more pkg\n");
-			goto out_err;
+		{
+			unsigned short _, *port;
+
+			/* if the DSN has a custom port, inherit it now & bypass parser */
+			if (!(id->flags & CACHEDB_ID_MULTIPLE_HOSTS) && id->port) {
+				con->port = id->port;
+				port = &_;
+			} else {
+				port = &con->port;
+			}
+
+			if (redis_get_hostport(&it->s, &con->host, port) != 0) {
+				LM_ERR("no more pkg\n");
+				goto out_err;
+			}
+
+			LM_DBG("final hostport: %s:%u\n", con->host, con->port);
 		}
 
 		con->id = id;