Add host/port "switchboard" module

Centrally list all hostnames and port numbers here. Need to push
this into IDZ further but I'm a bit short on time (so what else is
new).

src/switchboard.ts

@@ -0,0 +1,84 @@
+import * as os from "os";
+
+const cfgHostExt: string | undefined = process.env.HOST_EXT;
+const cfgHostInt: string | undefined = process.env.HOST_INT;
+
+export const HOST_EXT = cfgHostExt !== undefined ? cfgHostExt : os.hostname();
+export const HOST_INT = cfgHostInt !== undefined ? cfgHostInt : "127.0.0.1";
+
+//
+// Core services. These ports cannot be changed
+//
+
+export const PORT_AIMEDB = 22345;
+export const PORT_BILLING = 8443;
+export const PORT_STARTUP = 80;
+
+//
+// Title services. These can be freely chosen.
+//
+
+export const PORT_CHUNITHM = 9001;
+export const PORT_DIVA = 9000;
+export const PORT_IDZ = {
+  // Most of these seem to be unused relics
+
+  USERDB: {
+    TCP: 10000,
+    HTTP: 10001,
+  },
+  MATCH: {
+    TCP: 10002,
+    UDP_SEND: 10003,
+    UDP_RECV: 10004,
+  },
+  TAG_MATCH: {
+    TCP: 10005,
+    UDP_SEND: 10006,
+    UDP_RECV: 10007,
+  },
+  EVENT: 10008,
+  SCREENSHOT: 10009,
+  ECHO1: 10010,
+  ECHO2: 10011,
+};
+
+//
+// Startup responses
+//
+
+const startupHosts = new Map<string, string>();
+
+startupHosts.set("SDDF", `${HOST_EXT}:${PORT_IDZ.USERDB.TCP}`);
+
+const startupUris = new Map<string, string>();
+
+startupUris.set("SDBT", `http://${HOST_EXT}:${PORT_CHUNITHM}/`);
+startupUris.set("SBZV", `http://${HOST_EXT}:${PORT_DIVA}/`);
+
+export function startupHost(model: string): string {
+  const val = startupHosts.get(model);
+
+  return val !== undefined ? val : "";
+}
+
+export function startupUri(model: string): string {
+  const val = startupUris.get(model);
+
+  return val !== undefined ? val : "";
+}
+
+//
+// Diagnostic dump
+//
+
+console.log(
+  `Switchboard: HOST_EXT: ${HOST_EXT} (Service host name sent to clients)`
+);
+console.log(`Switchboard: HOST_INT: ${HOST_INT} (Bind address)`);
+
+if (cfgHostExt === undefined || cfgHostInt === undefined) {
+  console.log(
+    "Switchboard: Warning: Check .env and env vars! Using unreliable fallback."
+  );
+}