refactor testing

server/utils/cotParser.js

@@ -1,7 +1,15 @@
 import { XMLParser } from 'fast-xml-parser'
 import { MAX_PAYLOAD_BYTES } from './constants.js'
 
-const TAK_MAGIC = 0xBF
+// CoT protocol detection constants
+export const COT_FIRST_BYTE_TAK = 0xBF
+export const COT_FIRST_BYTE_XML = 0x3C
+
+/** @param {number} byte - First byte of stream. @returns {boolean} */
+export function isCotFirstByte(byte) {
+  return byte === COT_FIRST_BYTE_TAK || byte === COT_FIRST_BYTE_XML
+}
+
 const TRADITIONAL_DELIMITER = Buffer.from('</event>', 'utf8')
 
 /**
@@ -30,7 +38,7 @@ function readVarint(buf, offset) {
  * @returns {{ payload: Buffer, bytesConsumed: number } | null} Frame or null if incomplete/invalid.
  */
 export function parseTakStreamFrame(buf) {
-  if (!buf || buf.length < 2 || buf[0] !== TAK_MAGIC) return null
+  if (!buf || buf.length < 2 || buf[0] !== COT_FIRST_BYTE_TAK) return null
   const { value: length, bytesRead } = readVarint(buf, 1)
   if (length < 0 || length > MAX_PAYLOAD_BYTES) return null
   const bytesConsumed = 1 + bytesRead + length
@@ -44,7 +52,7 @@ export function parseTakStreamFrame(buf) {
  * @returns {{ payload: Buffer, bytesConsumed: number } | null} Frame or null if incomplete.
  */
 export function parseTraditionalXmlFrame(buf) {
-  if (!buf || buf.length < 8 || buf[0] !== 0x3C) return null
+  if (!buf || buf.length < 8 || buf[0] !== COT_FIRST_BYTE_XML) return null
   const idx = buf.indexOf(TRADITIONAL_DELIMITER)
   if (idx === -1) return null
   const bytesConsumed = idx + TRADITIONAL_DELIMITER.length