feat: improve stringToHexStripped (#88)

lib/utils.js

@@ -13,14 +13,20 @@ function normalizeIPv4 (host) {
   }
 }
 
-function stringToHexStripped (input) {
+/**
+ * @param {string[]} input
+ * @param {boolean} [keepZero=false]
+ * @returns {string|undefined}
+ */
+function stringArrayToHexStripped (input, keepZero = false) {
   let acc = ''
   let strip = true
   for (const c of input) {
-    if (c !== '0' && strip === true) strip = false
     if (HEX[c] === undefined) return undefined
+    if (c !== '0' && strip === true) strip = false
     if (!strip) acc += c
   }
+  if (keepZero && acc.length === 0) acc = '0'
   return acc
 }
 
@@ -36,7 +42,7 @@ function getIPV6 (input) {
   function consume () {
     if (buffer.length) {
       if (isZone === false) {
-        const hex = stringToHexStripped(buffer.join(''))
+        const hex = stringArrayToHexStripped(buffer)
         if (hex !== undefined) {
           address.push(hex)
         } else {
@@ -83,7 +89,7 @@ function getIPV6 (input) {
     } else if (endIpv6) {
       address.push(buffer.join(''))
     } else {
-      address.push(stringToHexStripped(buffer.join('')))
+      address.push(stringArrayToHexStripped(buffer))
     }
   }
   output.address = address.join('')
@@ -232,5 +238,5 @@ module.exports = {
   removeDotSegments,
   normalizeIPv4,
   normalizeIPv6,
-  stringToHexStripped
+  stringArrayToHexStripped
 }

test/util.test.js

@@ -0,0 +1,24 @@
+'use strict'
+
+const tap = require('tap')
+const test = tap.test
+const {
+  stringArrayToHexStripped
+} = require('../lib/utils')
+
+test('stringArrayToHexStripped', (t) => {
+  const testCases = [
+    [[['0', '0', '0', '0']], ''],
+    [[['0', '0', '0', '0'], false], ''],
+    [[['0', '0', '0', '0'], true], '0'],
+    [[['0', '1', '0', '0'], false], '100'],
+    [[['1', '0', '0', '0'], false], '1000'],
+    [[['1', '0', '0', '0'], true], '1000']
+  ]
+
+  t.plan(testCases.length)
+
+  testCases.forEach(([input, expected]) => {
+    t.strictSame(stringArrayToHexStripped(input[0], input[1]), expected)
+  })
+})