constructors for the data types, allow multiple TLVs

src/index.js

@@ -19,32 +19,89 @@ function logDataStream(data){
   return strs.map((str) => chunkString(str, 2).join(' ')).join('\n');
 }
 
-function TLV(buf) {
-  this.type = buf.slice(0, 2);
-  this.len = buf.slice(2, 4).readInt16BE(0)
-  this.payload = buf.slice(4, 4 + this.len);
-  this.toString = () => `TLV(${this.type.toString('hex')}, ${this.len}, ${this.payload.toString('ascii')})`;
+class TLV {
+  static fromBuffer(buf) {
+    const type = buf.slice(0, 2).readInt16BE(0);
+    const len = buf.slice(2, 4).readInt16BE(0)
+    const payload = buf.slice(4, 4 + len);
+
+    return new TLV(type, payload);
+  }
+
+  constructor(type, payload) {
+    this.type = type;
+    this.len = payload.length;
+    this.payload = payload;
+  }
+
+  toString() {
+    return `TLV(${this.type}, ${this.len}, ${this.payload.toString('ascii')})`;
+  }
 }
 
-function SNAC(buf) {
-  this.family = buf.slice(0,2).readInt16BE(0);
-  this.service = buf.slice(2,4).readInt16BE(0);
-  this.flags = buf.slice(4, 6);
-  this.requestID = buf.slice(6, 10).readInt32BE(0);
-  this.payload = new TLV(buf.slice(10));
-  this.toString = () => `SNAC(${this.family.toString(16)},${this.service.toString(16)}) #${this.requestID}\n  ${this.payload}`;
+class SNAC {
+  static fromBuffer(buf, payloadLength = 0) {
+    const family = buf.slice(0,2).readInt16BE(0);
+    const service = buf.slice(2,4).readInt16BE(0);
+    const flags = buf.slice(4, 6);
+    const requestID = buf.slice(6, 10).readInt32BE(0);
+    const payload = []; // SNACs can have multiple TLVs
+
+    let payloadIdx = 10;
+    let cb = 0, cbLimit = 10; //circuit breaker
+    while (payloadIdx < payloadLength && cb < cbLimit) {
+      const tlv = TLV.fromBuffer(buf.slice(payloadIdx));
+      payload.push(tlv);
+      payloadIdx += tlv.len + 4; // 4 bytes for TLV type + payload length
+      cb++;
+    }
+    if (cb === cbLimit) {
+      console.error('Application error, cb limit reached');
+      process.exit(1);
+    }
+    
+    return new SNAC(family, service, flags, requestID, payload);
+  }
+
+  constructor(family, service, flags, requestID, payload) {
+    this.family = family;
+    this.service = service;
+    this.flags = flags;
+    this.requestID = requestID;
+    this.payload = payload;
+  }
+
+  toString() {
+    return `SNAC(${this.family.toString(16)},${this.service.toString(16)}) #${this.requestID}\n  ${this.payload}`;
+  }
 }
 
-function FLAP(buf) {
-  assert.equal(buf[0], 0x2a, 'Expected 0x2a FLAP header');
-  this.channel = buf[1];
-  this.datagramNumber = buf.slice(2,4).readInt16BE(0);
-  this.payloadLength = buf.slice(4, 6).readInt16BE(0);
-  this.payload = buf.slice(6, 6 + this.payloadLength);
-  this.toString = () => `ch:${this.channel}, dn: ${this.datagramNumber}, len: ${this.payloadLength}, payload:\n  ${ this.payload instanceof SNAC ? this.payload.toString() : logDataStream(this.payload).split('\n').join('\n  ')}`;
+class FLAP {
+  static fromBuffer(buf) {
+    assert.equal(buf[0], 0x2a, 'Expected 0x2a FLAP header');
+    const channel = parseInt(buf[1], 16);
+    const datagramNumber = buf.slice(2,4).readInt16BE(0);
+    const payloadLength = buf.slice(4, 6).readInt16BE(0);
+    const payload = buf.slice(6, 6 + payloadLength);
 
-  if (this.channel === 2) {
-    this.payload = new SNAC(this.payload);
+    return new FLAP(channel, datagramNumber, payload)
+  }
+
+  constructor(channel, datagramNumber, payload) {
+    this.channel = channel;
+    this.datagramNumber = datagramNumber;
+    this.payload = payload;
+    this.payloadLength = this.payload.length;
+
+    if (channel === 2) {
+      this.payload = SNAC.fromBuffer(this.payload, this.payloadLength);
+    }
+  }
+
+  toString() {
+    const hasSnac = this.payload instanceof SNAC;
+    const payload = hasSnac ? this.payload.toString() : logDataStream(this.payload).split('\n').join('\n  ');
+    return `ch:${this.channel}, dn: ${this.datagramNumber}, len: ${this.payloadLength}, payload:\n  ${payload}`
   }
 }
 
@@ -57,7 +114,7 @@ const server = net.createServer((socket) => {
   });
 
   socket.on('data', (data) => {
-    const flap = new FLAP(Buffer.from(data, 'hex'));
+    const flap = FLAP.fromBuffer(Buffer.from(data, 'hex'));
     console.log('RECV', flap.toString());
   });