basic working prototype

Author: Victoria Hall

src/http/httpProxy.ts

@@ -4,6 +4,7 @@
 import { serialize as serializeCookie } from 'cookie';
 import { EventEmitter } from 'events';
 import * as http from 'http';
+import * as net from 'net';
 import { AzFuncSystemError, ensureErrorType } from '../errors';
 import { nonNullProp } from '../utils/nonNull';
 import { workerSystemLog } from '../utils/workerSystemLog';
@@ -16,13 +17,16 @@ const invocRequestEmitter = new EventEmitter();
 
 export async function waitForProxyRequest(invocationId: string): Promise<http.IncomingMessage> {
     return new Promise((resolve, _reject) => {
+        workerSystemLog('debug', 'Waiting for proxy request', { invocationId });
         const req = requests[invocationId];
         if (req) {
             resolve(req);
+            workerSystemLog('debug', 'Proxy request found', { invocationId });
             delete requests[invocationId];
         } else {
             invocRequestEmitter.once(invocationId, () => {
                 const req = requests[invocationId];
+                workerSystemLog('debug', 'Proxy request else statement');
                 if (req) {
                     resolve(req);
                     delete requests[invocationId];
@@ -34,11 +38,13 @@ export async function waitForProxyRequest(invocationId: string): Promise<http.In
 
 const invocationIdHeader = 'x-ms-invocation-id';
 export async function sendProxyResponse(invocationId: string, userRes: HttpResponse): Promise<void> {
+    workerSystemLog('debug', 'Sending proxy response', { invocationId });
     const proxyRes = nonNullProp(responses, invocationId);
     delete responses[invocationId];
     for (const [key, val] of userRes.headers.entries()) {
         proxyRes.setHeader(key, val);
     }
+    workerSystemLog('debug', 'Http proxy headers set');
     proxyRes.setHeader(invocationIdHeader, invocationId);
     proxyRes.statusCode = userRes.status;
 
@@ -48,7 +54,9 @@ export async function sendProxyResponse(invocationId: string, userRes: HttpRespo
 
     if (userRes.body) {
         for await (const chunk of userRes.body.values()) {
+            workerSystemLog('debug', 'Writing proxy response chunk');
             proxyRes.write(chunk);
+            workerSystemLog('debug', 'Http proxy response chunks written');
         }
     }
     proxyRes.end();
@@ -86,10 +94,12 @@ function setCookies(userRes: HttpResponse, proxyRes: http.ServerResponse): void
 export async function setupHttpProxy(): Promise<string> {
     return new Promise((resolve, reject) => {
         const server = http.createServer();
+        workerSystemLog('debug', 'Http proxy server created');
 
         server.on('request', (req, res) => {
             const invocationId = req.headers[invocationIdHeader];
             if (typeof invocationId === 'string') {
+                workerSystemLog('debug', 'Http proxy request received', { invocationId });
                 requests[invocationId] = req;
                 responses[invocationId] = res;
                 invocRequestEmitter.emit(invocationId);
@@ -103,12 +113,22 @@ export async function setupHttpProxy(): Promise<string> {
             workerSystemLog('error', `Http proxy error: ${err.stack || err.message}`);
         });
 
-        server.listen(() => {
-            const address = server.address();
-            if (address !== null && typeof address === 'object') {
-                resolve(`http://localhost:${address.port}/`);
+        server.listen(0, () => {
+            workerSystemLog('debug', `VICTORIA: auto-assigned port: ${server.address().port}`);
+
+            // If port is still 0, find and bind to an open port
+            if (server.address().port === 0) {
+                workerSystemLog('debug', `VICTORIA: Port 0 assigned. Finding open port.`);
+                findOpenPort(51929, (openPort) => {
+                    workerSystemLog('debug', `VICTORIA: found open port: ${openPort}`);
+                    server.close();  // Close the server
+                    server.listen(openPort, () => {
+                        workerSystemLog('debug', `VICTORIA: server is now listening on found open port: ${openPort}`);
+                    });
+                    resolve(`http://localhost:${openPort}/`);
+                });
             } else {
-                reject(new AzFuncSystemError('Unexpected server address during http proxy setup'));
+                resolve(`http://localhost:${server.address().port}/`);
             }
         });
 
@@ -117,3 +137,28 @@ export async function setupHttpProxy(): Promise<string> {
         });
     });
 }
+
+
+// Function to find an open port starting from a specified port
+function findOpenPort(startingPort, callback) {
+    const server = net.createServer();
+
+    function tryPort(port) {
+      server.once('error', () => {
+        // If the port is unavailable, increment and try the next one
+        tryPort(port + 1);
+      });
+
+      server.once('listening', () => {
+        const port = server.address().port;
+        server.close();
+        callback(port);
+      });
+
+      // Try binding to the given port
+      server.listen(port);
+    }
+
+    // Start trying from the specified starting port
+    tryPort(startingPort);
+  }