core: Add support for dtoi usage ping parameter

Server side implementation for brave/brave-core#5720

src/common.js

@@ -100,6 +100,22 @@ exports.countryCodeFrom = (request) => {
   return (request.headers['x-brave-country-code'] || 'unknown').toUpperCase()
 }
 
+/* Country codes with, on average, less than 100 DAU that we want to exclude
+ * from certain collections for privacy purposes. Eventually we will want to
+  * make this a dynamic list. */
+const countryCodesLowDAU = new Set([
+  'AX', 'AS', 'AI', 'AQ', 'AG', 'BQ', 'BV', 'IO', 'BI', 'CV', 'CF', 'TD', 'CX',
+  'CC', 'KM', 'CG', 'CK', 'DJ', 'DM', 'GQ', 'ER', 'FK', 'FO', 'GF', 'TF', 'GM',
+  'GL', 'GD', 'GG', 'GN', 'GW', 'HM', 'VA', 'KI', 'KP', 'LS', 'LI', 'MH', 'MR',
+  'KN', 'MF', 'PM', 'VC', 'WS', 'SM', 'ST', 'SC', 'SL', 'SX', 'SB', 'GS', 'SS',
+  'SJ', 'TJ', 'TL', 'TK', 'TO', 'TC', 'TV', 'UM', 'VU', 'VI', 'WF', 'EH', 'YT',
+  'FM', 'MC', 'MS', 'NR', 'NE', 'NU', 'NF', 'MP', 'PW', 'PN', 'BL', 'SH',
+])
+
+exports.shouldExcludeCountryCode = function(countryCode) {
+  return countryCodesLowDAU.has(countryCode)
+}
+
 // promisified request
 exports.prequest = function (url) {
   return new Promise((resolve, reject) => {

src/controllers/braveCore.js

@@ -22,14 +22,16 @@ let validator = {
     monthly: Joi.valid(booleanString).required(),
     first: Joi.valid(booleanString).required(),
     woi: Joi.string(),
+    dtoi: Joi.string().optional(),
     ref: Joi.string()
   }
 }
 
 // Build a usage object if query parameters passed in
 let buildUsage = (request) => {
   if (request.query.daily) {
-    return {
+    const country_code = common.countryCodeFrom(request)
+    const usagePing = {
       daily: request.query.daily === 'true',
       weekly: request.query.weekly === 'true',
       monthly: request.query.monthly === 'true',
@@ -39,8 +41,13 @@ let buildUsage = (request) => {
       channel: request.query.channel || 'unknown',
       woi: request.query.woi || '2016-01-04',
       ref: request.query.ref || 'none',
-      country_code: common.countryCodeFrom(request)
+      country_code: country_code
     }
+    const dtoi = request.query.dtoi
+    if (!common.shouldExcludeCountryCode(country_code) && dtoi
+          && dtoi !== 'null')
+      usagePing.dtoi = request.query.dtoi
+    return usagePing
   } else {
     return null
   }

src/db.js

@@ -21,6 +21,7 @@ const usageSchema = Joi.object().keys({
   version: Joi.string(),
   channel: Joi.string(),
   woi: Joi.string(),
+  dtoi: Joi.string().optional(),
   ref: Joi.string(),
   country_code: Joi.string(),
   braveDataCenter: Joi.boolean(),