added get segments by hash prefix

src/utils/hashPrefixTester.js

@@ -0,0 +1,11 @@
+const config = require('../config.js');
+const logger = require('./logger.js');
+
+const minimumPrefix = config.minimumPrefix || '3';
+const maximumPrefix = config.maximumPrefix || '32'; // Half the hash.
+
+const prefixChecker = new RegExp('^[\\da-f]{' + minimumPrefix + ',' + maximumPrefix + '}$', 'i');
+
+module.exports = (prefix) => {
+    return prefixChecker.test(prefix);
+};