Fix MAC and IP address comparison logic in generators (#164)

This commit corrects the comparison logic in setMacGenerator and
setIpGenerator methods to accurately compare MAC and IP addresses byte
by byte.

The previous method relied on array reference comparison, which led to
incorrect maximum address detection and subsequent address duplication.
The newly introduced helper functions, compareMacs and compareIps,
ensure element-wise comparison, preventing duplication by correctly
identifying and initializing the maximum address for each generator.

before:


![image](https://github.com/user-attachments/assets/dd776ef4-8f92-4ed8-99ed-3c9d834a4326)


after:

![image](https://github.com/user-attachments/assets/b88f08a2-ae91-4629-9cae-95be602e396b)

Author: pgallino

src/context.ts

@@ -7,10 +7,14 @@ import {
   urManager,
 } from "./types/viewportManager";
 import { Layer } from "./types/devices/device";
-import { IpAddress, IpAddressGenerator } from "./packets/ip";
+import { compareIps, IpAddress, IpAddressGenerator } from "./packets/ip";
 import { layerFromName } from "./types/devices/layer";
 import { SpeedMultiplier } from "./types/devices/speedMultiplier";
-import { MacAddress, MacAddressGenerator } from "./packets/ethernet";
+import {
+  compareMacs,
+  MacAddress,
+  MacAddressGenerator,
+} from "./packets/ethernet";
 import { Colors } from "./utils";
 
 export class GlobalContext {
@@ -136,15 +140,19 @@ export class GlobalContext {
 
   private setIpGenerator() {
     let maxIp = IpAddress.parse("10.0.0.0");
+
     for (const [, device] of this.datagraph.getDevices()) {
       if (isNetworkNode(device)) {
         const ip = IpAddress.parse(device.ip);
-        if (maxIp.octets < ip.octets) {
-          maxIp = ip;
+        if (ip === null) {
+          console.error("Failed to parse IP address: " + device.ip);
+        } else {
+          if (compareIps(maxIp, ip) < 0) {
+            maxIp = ip;
+          }
         }
       }
     }
-    // TODO: we should use IpAddress instead of string here and in Datagraph
     const baseIp = maxIp.toString();
     const mask = "255.255.255.255";
     this.ipGenerator = new IpAddressGenerator(baseIp, mask);
@@ -155,7 +163,7 @@ export class GlobalContext {
     for (const [, device] of this.datagraph.getDevices()) {
       if (isLinkNode(device)) {
         const mac = MacAddress.parse(device.mac);
-        if (maxMac.octets < mac.octets) {
+        if (compareMacs(maxMac, mac) < 0) {
           maxMac = mac;
         }
       }

src/packets/ethernet.ts

@@ -166,3 +166,11 @@ export interface FramePayload {
   // Get details of the payload
   getDetails(layer: Layer): Record<string, string | number | object>;
 }
+
+export function compareMacs(mac1: MacAddress, mac2: MacAddress): number {
+  for (let i = 0; i < 6; i++) {
+    if (mac1.octets[i] < mac2.octets[i]) return -1;
+    if (mac1.octets[i] > mac2.octets[i]) return 1;
+  }
+  return 0; // equal
+}

src/packets/ip.ts

@@ -299,3 +299,11 @@ export function computeIpChecksum(octets: Uint8Array): number {
   const carry = sum >> 16;
   return 0xffff ^ (checksum + carry);
 }
+
+export function compareIps(ip1: IpAddress, ip2: IpAddress): number {
+  for (let i = 0; i < 4; i++) {
+    if (ip1.octets[i] < ip2.octets[i]) return -1;
+    if (ip1.octets[i] > ip2.octets[i]) return 1;
+  }
+  return 0; // equal
+}