add validation for db parameter in adapter config

lib/prepare-adapter.js

@@ -89,6 +89,7 @@ module.exports = function (app){
             var redisClientConnectionError;
             var pubReady;
             var subReady;
+            var db;
             adapterConfig.pubClient.once('ready', function (){
               if (pubReady) return;
               pubReady = true;
@@ -136,9 +137,16 @@ module.exports = function (app){
               return cb();
             }
 
-            // if `db` was supplied, call `select` on that redis database
-            adapterConfig.pubClient.select(adapterConfig.db, function() {
-              adapterConfig.subClient.select(adapterConfig.db, function (){
+            // if `db` was supplied, validate the value
+            db = parseInt(adapterConfig.db, 10);
+            if(isNaN(db) || db > 15 || db < 0){
+               db = 0;
+               sails.log.warn('socket.io-redis db adapter paramter must be a number between 0 and 15');
+               sails.log.warn('Falling back to database 0');
+            }
+            // then call `select` on that redis database
+            adapterConfig.pubClient.select(db, function() {
+              adapterConfig.subClient.select(db, function (){
                 return cb();
               });
             });