fix: invalid CONNECT responses (#151)

package.json

@@ -1,6 +1,6 @@
 {
   "name": "proxy-chain",
-  "version": "1.0.3",
+  "version": "1.0.4",
   "description": "Node.js implementation of a proxy server (think Squid) with support for SSL, authentication, upstream proxy chaining, and protocol tunneling.",
   "main": "build/index.js",
   "keywords": [

src/handler_tunnel_chain.js

@@ -17,15 +17,15 @@ export default class HandlerTunnelChain extends HandlerBase {
     run() {
         this.log('Connecting to upstream proxy...');
 
-        const targetHost = `${this.trgParsed.hostname}:${this.trgParsed.port}`;
+        this.targetHost = `${this.trgParsed.hostname}:${this.trgParsed.port}`;
 
         const options = {
             method: 'CONNECT',
             hostname: this.upstreamProxyUrlParsed.hostname,
             port: this.upstreamProxyUrlParsed.port,
-            path: targetHost,
+            path: this.targetHost,
             headers: {
-                Host: targetHost,
+                Host: this.targetHost,
             },
         };
 
@@ -44,6 +44,7 @@ export default class HandlerTunnelChain extends HandlerBase {
 
     onTrgRequestConnect(response, socket, head) {
         if (this.isClosed) return;
+
         this.log('Connected to upstream proxy');
 
         // Attempt to fix https://github.com/apify/proxy-chain/issues/64,
@@ -56,7 +57,7 @@ export default class HandlerTunnelChain extends HandlerBase {
 
         this.srcGotResponse = true;
         this.srcResponse.removeListener('finish', this.onSrcResponseFinish);
-        this.srcResponse.writeHead(200, 'Connection Established');
+        this.srcResponse.writeHead(response.statusCode === 200 ? 200 : 502);
 
         this.emit('tunnelConnectResponded', { response, socket, head });
 
@@ -65,6 +66,13 @@ export default class HandlerTunnelChain extends HandlerBase {
         // See also https://github.com/nodejs/node/blob/master/lib/_http_outgoing.js#L217
         this.srcResponse._send('');
 
+        if (response.statusCode !== 200) {
+            this.log(`Failed to connect to ${this.targetHost} via ${this.upstreamProxyUrlParsed.hostname} (${response.statusCode})`);
+
+            this.close();
+            return;
+        }
+
         // It can happen that this.close() it called in the meanwhile, so this.srcSocket becomes null
         // and the detachSocket() call below fails with "Cannot read property '_httpMessage' of null"
         // See https://github.com/apify/proxy-chain/issues/63

test/server.js

@@ -16,6 +16,7 @@ const WebSocket = require('faye-websocket');
 const { parseUrl, parseProxyAuthorizationHeader } = require('../build/tools');
 const { Server, RequestError } = require('../build/index');
 const { TargetServer } = require('./target_server');
+const ProxyChain = require('../build/index');
 
 /*
 TODO - add following tests:
@@ -1063,6 +1064,64 @@ describe('Server (HTTPS -> Target)', createTestSuite({
     useMainProxy: false,
 }));
 
+describe('non-200 upstream connect response', () => {
+    // No assertion planning :(
+    // https://github.com/chaijs/chai/issues/670
+    let success = false;
+
+    after(() => {
+        if (!success) {
+            throw new Error('Failed');
+        }
+    });
+
+    it('fails downstream with 502', (done) => {
+        const server = http.createServer();
+        server.on('connect', (_request, socket) => {
+            socket.once('error', () => {});
+            socket.end('HTTP/1.1 403 Forbidden\r\ncontent-length: 1\r\n\r\na');
+        });
+        server.listen(() => {
+            const serverPort = server.address().port;
+            const proxyServer = new ProxyChain.Server({
+                port: 0,
+                prepareRequestFunction: () => {
+                    return {
+                        upstreamProxyUrl: `http://localhost:${serverPort}`,
+                    };
+                },
+            });
+            proxyServer.listen(() => {
+                const proxyServerPort = proxyServer.port;
+
+                const req = http.request({
+                    method: 'CONNECT',
+                    host: 'localhost',
+                    port: proxyServerPort,
+                    path: 'example.com:443',
+                    headers: {
+                        host: 'example.com:443',
+                    },
+                });
+                req.once('connect', (response, socket, head) => {
+                    expect(response.statusCode).to.equal(502);
+                    expect(head.length).to.equal(0);
+                    success = true;
+
+                    socket.once('close', () => {
+                        proxyServer.close();
+                        server.close();
+
+                        done();
+                    });
+                });
+
+                req.end();
+            });
+        });
+    });
+});
+
 // Run all combinations of test parameters
 const useSslVariants = [
     false,