more functional design principles

server/plugins/cot.js

@@ -9,8 +9,10 @@ import { registerCleanup } from '../utils/shutdown.js'
 import { COT_AUTH_TIMEOUT_MS } from '../utils/constants.js'
 import { acquire } from '../utils/asyncLock.js'
 
-let tcpServer = null
-let tlsServer = null
+const serverState = {
+  tcpServer: null,
+  tlsServer: null,
+}
 const relaySet = new Set()
 const allSockets = new Set()
 const socketBuffers = new WeakMap()
@@ -44,22 +46,27 @@ function broadcast(senderSocket, rawMessage) {
   }
 }
 
+const createPreview = (payload) => {
+  try {
+    const str = payload.toString('utf8')
+    if (str.startsWith('<')) {
+      const s = str.length <= 120 ? str : str.slice(0, 120) + '...'
+      // eslint-disable-next-line no-control-regex -- sanitize control chars for log preview
+      return s.replace(/[\u0000-\u0008\v\f\u000E-\u001F]/g, '.')
+    }
+    return 'hex:' + payload.subarray(0, Math.min(40, payload.length)).toString('hex')
+  }
+  catch {
+    return 'hex:' + payload.subarray(0, Math.min(40, payload.length)).toString('hex')
+  }
+}
+
 async function processFrame(socket, rawMessage, payload, authenticated) {
   const requireAuth = socket._cotRequireAuth !== false
   const debug = socket._cotDebug === true
   const parsed = parseCotPayload(payload)
   if (debug) {
-    let preview = payload.length
-    try {
-      const str = payload.toString('utf8')
-      if (str.startsWith('<')) {
-        const s = str.length <= 120 ? str : str.slice(0, 120) + '...'
-        // eslint-disable-next-line no-control-regex -- sanitize control chars for log preview
-        preview = s.replace(/[\u0000-\u0008\v\f\u000E-\u001F]/g, '.')
-      }
-      else preview = 'hex:' + payload.subarray(0, Math.min(40, payload.length)).toString('hex')
-    }
-    catch { preview = 'hex:' + payload.subarray(0, Math.min(40, payload.length)).toString('hex') }
+    const preview = createPreview(payload)
     console.log('[cot] payload length:', payload.length, 'parsed:', parsed ? parsed.type : null, 'preview:', preview)
   }
   if (!parsed) return
@@ -108,10 +115,35 @@ async function processFrame(socket, rawMessage, payload, authenticated) {
   }
 }
 
+const parseFrame = (buf) => {
+  const takResult = parseTakStreamFrame(buf)
+  if (takResult) return { result: takResult, frameType: 'tak' }
+  if (buf[0] === 0x3C) {
+    const xmlResult = parseTraditionalXmlFrame(buf)
+    if (xmlResult) return { result: xmlResult, frameType: 'traditional' }
+  }
+  return { result: null, frameType: null }
+}
+
+const processBufferedData = async (socket, buf, authenticated) => {
+  if (buf.length === 0) return buf
+  const { result, frameType } = parseFrame(buf)
+  if (result && socket._cotDebug) {
+    console.log('[cot] frame parsed as', frameType, 'bytesConsumed=', result.bytesConsumed)
+  }
+  if (!result) return buf
+  const { payload, bytesConsumed } = result
+  const rawMessage = buf.subarray(0, bytesConsumed)
+  await processFrame(socket, rawMessage, payload, authenticated)
+  if (socket.destroyed) return null
+  const remainingBuf = buf.subarray(bytesConsumed)
+  socketBuffers.set(socket, remainingBuf)
+  return processBufferedData(socket, remainingBuf, authenticated)
+}
+
 async function onData(socket, data) {
-  let buf = socketBuffers.get(socket)
-  if (!buf) buf = Buffer.alloc(0)
-  buf = Buffer.concat([buf, data])
+  const existingBuf = socketBuffers.get(socket)
+  const buf = Buffer.concat([existingBuf || Buffer.alloc(0), data])
   socketBuffers.set(socket, buf)
   const authenticated = Boolean(socket._cotAuthenticated)
 
@@ -120,22 +152,7 @@ async function onData(socket, data) {
     const hex = buf.subarray(0, Math.min(80, buf.length)).toString('hex')
     console.log('[cot] first chunk len=', buf.length, 'first bytes (hex):', hex, 'starts with 0xBF:', buf[0] === 0xBF, 'starts with <:', buf[0] === 0x3C)
   }
-  while (buf.length > 0) {
-    let result = parseTakStreamFrame(buf)
-    let frameType = 'tak'
-    if (!result && buf[0] === 0x3C) {
-      result = parseTraditionalXmlFrame(buf)
-      frameType = 'traditional'
-    }
-    if (result && socket._cotDebug) console.log('[cot] frame parsed as', frameType, 'bytesConsumed=', result.bytesConsumed)
-    if (!result) break
-    const { payload, bytesConsumed } = result
-    const rawMessage = buf.subarray(0, bytesConsumed)
-    await processFrame(socket, rawMessage, payload, authenticated)
-    if (socket.destroyed) return
-    buf = buf.subarray(bytesConsumed)
-    socketBuffers.set(socket, buf)
-  }
+  await processBufferedData(socket, buf, authenticated)
 }
 
 function setupSocket(socket, tls = false) {
@@ -182,16 +199,16 @@ function startCotServers() {
         key: readFileSync(keyPath),
         rejectUnauthorized: false,
       }
-      tlsServer = createTlsServer(tlsOpts, socket => setupSocket(socket, true))
-      tlsServer.on('error', err => console.error('[cot] TLS server error:', err?.message))
-      tlsServer.listen(port, '0.0.0.0', () => {
+      serverState.tlsServer = createTlsServer(tlsOpts, socket => setupSocket(socket, true))
+      serverState.tlsServer.on('error', err => console.error('[cot] TLS server error:', err?.message))
+      serverState.tlsServer.listen(port, '0.0.0.0', () => {
         console.log('[cot] CoT server listening on 0.0.0.0:' + port + ' (TLS) — use this port in ATAK/iTAK and enable SSL')
       })
     }
     else {
-      tcpServer = createTcpServer(socket => setupSocket(socket, false))
-      tcpServer.on('error', err => console.error('[cot] TCP server error:', err?.message))
-      tcpServer.listen(port, '0.0.0.0', () => {
+      serverState.tcpServer = createTcpServer(socket => setupSocket(socket, false))
+      serverState.tcpServer.on('error', err => console.error('[cot] TCP server error:', err?.message))
+      serverState.tcpServer.listen(port, '0.0.0.0', () => {
         console.log('[cot] CoT server listening on 0.0.0.0:' + port + ' (plain TCP) — use this port in ATAK/iTAK with SSL disabled')
       })
     }
@@ -209,7 +226,18 @@ export default defineNitroPlugin((nitroApp) => {
   // Start immediately so CoT is up before first request in dev; ready may fire late in some setups.
   setImmediate(startCotServers)
 
-  registerCleanup(async () => {
+  const cleanupServers = () => {
+    if (serverState.tcpServer) {
+      serverState.tcpServer.close()
+      serverState.tcpServer = null
+    }
+    if (serverState.tlsServer) {
+      serverState.tlsServer.close()
+      serverState.tlsServer = null
+    }
+  }
+
+  const cleanupSockets = () => {
     for (const s of allSockets) {
       try {
         s.destroy()
@@ -220,34 +248,15 @@ export default defineNitroPlugin((nitroApp) => {
     }
     allSockets.clear()
     relaySet.clear()
-    if (tcpServer) {
-      tcpServer.close()
-      tcpServer = null
-    }
-    if (tlsServer) {
-      tlsServer.close()
-      tlsServer = null
-    }
+  }
+
+  registerCleanup(async () => {
+    cleanupSockets()
+    cleanupServers()
   })
 
   nitroApp.hooks.hook('close', async () => {
-    for (const s of allSockets) {
-      try {
-        s.destroy()
-      }
-      catch {
-        /* ignore */
-      }
-    }
-    allSockets.clear()
-    relaySet.clear()
-    if (tcpServer) {
-      tcpServer.close()
-      tcpServer = null
-    }
-    if (tlsServer) {
-      tlsServer.close()
-      tlsServer = null
-    }
+    cleanupSockets()
+    cleanupServers()
   })
 })