feat: alert when HTTP client connection fails

src/programs/echo_sender.ts

@@ -59,6 +59,7 @@ export class SingleEcho extends ProgramBase {
     );
     let src: { ip: IpAddress; mac: MacAddress },
       dst: { ip: IpAddress; mac: MacAddress },
+      nextHop: { ip: IpAddress; mac: MacAddress },
       sendingIface: number;
     if (!forwardingData) {
       console.warn(
@@ -74,23 +75,23 @@ export class SingleEcho extends ProgramBase {
       };
       sendingIface = 0;
     } else {
-      ({ src, dst, sendingIface } = forwardingData);
+      ({ src, dst, nextHop, sendingIface } = forwardingData);
     }
     const echoRequest = new EchoRequest(0);
     // Wrap in IP datagram
     const ipPacket = new IPv4Packet(src.ip, dst.ip, echoRequest);
 
     // Resolve destination MAC address
-    const dstMac = srcDevice.resolveAddress(dst.ip);
-    if (!dstMac) {
+    const nextHopMac = srcDevice.resolveAddress(nextHop.ip);
+    if (!nextHopMac) {
       console.debug(
-        `Device ${this.srcId} couldn't resolve MAC address for device with IP ${dst.ip.toString()}. Program cancelled`,
+        `Device ${this.srcId} couldn't resolve MAC address for device with IP ${nextHop.ip.toString()}. Program cancelled`,
       );
       return;
     }
 
     // Wrap in Ethernet frame
-    const ethernetFrame = new EthernetFrame(src.mac, dst.mac, ipPacket);
+    const ethernetFrame = new EthernetFrame(src.mac, nextHopMac.mac, ipPacket);
     sendViewPacket(this.viewgraph, this.srcId, ethernetFrame, sendingIface);
   }
 

src/programs/http_client.ts

@@ -90,7 +90,8 @@ export class HttpClient extends ProgramBase {
     // Write request
     const socket = await this.runner.tcpConnect(this.dstId);
     if (!socket) {
-      console.warn("HttpClient failed to connect");
+      console.error("HttpClient failed to connect");
+      showError("Failed to connect to HTTP server. Make sure the forwarding table is set up correctly.");
       return;
     }
     if (this.stopped) {

src/types/network-modules/tcp/tcpState.ts

@@ -57,23 +57,20 @@ function sendIpPacket(
     console.warn(`Device ${dst.id} is not reachable from device ${src.id}`);
     return false;
   }
-  const [srcData, dstData, sendingIface] = [
-    forwardingData.src,
-    forwardingData.dst,
-    forwardingData.sendingIface,
-  ];
+  const [srcData, dstData] = [forwardingData.src, forwardingData.dst];
+  const {nextHop, sendingIface} = forwardingData;
 
   // Resolve destination MAC address
-  const dstMac = src.resolveAddress(dstData.ip);
-  if (!dstMac) {
+  const nextHopMac = src.resolveAddress(nextHop.ip);
+  if (!nextHopMac) {
     console.warn(
-      `Device ${src.id} couldn't resolve MAC address for device with IP ${dstData.ip.toString()}. Program cancelled`,
+      `Device ${src.id} couldn't resolve MAC address for device with IP ${nextHop.ip.toString()}. Program cancelled`,
     );
     return false;
   }
 
   const ipPacket = new IPv4Packet(srcData.ip, dstData.ip, payload);
-  const frame = new EthernetFrame(srcData.mac, dstData.mac, ipPacket);
+  const frame = new EthernetFrame(srcData.mac, nextHopMac.mac, ipPacket);
 
   sendViewPacket(src.viewgraph, src.id, frame, sendingIface);
   return true;

src/types/view-devices/vDevice.ts

@@ -45,7 +45,6 @@ export enum DeviceType {
 export interface NetworkInterface {
   name: string;
   mac: MacAddress;
-  // TODO: add IP address
   ip?: IpAddress;
 }
 

src/types/view-devices/vNetworkDevice.ts

@@ -35,6 +35,10 @@ interface ForwardingData {
     ip: IpAddress;
     mac: MacAddress;
   };
+  nextHop: {
+    ip: IpAddress;
+    mac: MacAddress;
+  };
   sendingIface: number;
 }
 
@@ -84,20 +88,21 @@ export abstract class ViewNetworkDevice extends ViewDevice {
     const dstDevice = viewgraph.getDevice(dstId);
     const dstIface = dstDevice.interfaces[receivingIface];
     // Get dstMac
-    let dstMac: MacAddress = dstIface.mac;
+    let nextHop = dstIface;
     for (const idx of path.slice(1).keys()) {
       const [sendingId, receivingId] = [path[idx], path[idx + 1]];
       const receivingDevice = viewgraph.getDevice(receivingId);
       if (receivingDevice instanceof ViewNetworkDevice) {
         const edge = viewgraph.getEdge(sendingId, receivingId);
         const receivingIface = edge.getDeviceInterface(receivingId);
-        dstMac = receivingDevice.interfaces[receivingIface].mac;
+        nextHop = receivingDevice.interfaces[receivingIface];
         break;
       }
     }
     const forwardingData = {
       src: { mac: srcIface.mac, ip: srcIface.ip },
-      dst: { mac: dstMac, ip: dstIface.ip },
+      dst: { mac: dstIface.mac, ip: dstIface.ip },
+      nextHop: { mac: nextHop.mac, ip: nextHop.ip },
       sendingIface,
     };
     return forwardingData;
@@ -204,7 +209,7 @@ export abstract class ViewNetworkDevice extends ViewDevice {
     const { sha, spa, tha, tpa } = packet;
     const { mac, ip } = this.interfaces[iface];
     if (packet.op === ARP_REQUEST_CODE) {
-      // NOTE: We don’t take into account htype, ptype, hlen and plen,
+      // NOTE: We don't take into account htype, ptype, hlen and plen,
       // as they always will be MAC Address and IP address
       // Check if tpa is device ip
       if (!tpa.equals(ip)) {