https support for proxy relay

src/chain.ts

@@ -1,4 +1,5 @@
 import http from 'http';
+import https from 'https';
 import dns from 'dns';
 import { URL } from 'url';
 import { EventEmitter } from 'events';
@@ -80,7 +81,8 @@ export const chain = (
         options.headers.push('proxy-authorization', getBasicAuthorizationHeader(proxy));
     }
 
-    const client = http.request(proxy.origin, options as unknown as http.ClientRequestArgs);
+    const fn = proxy.protocol === 'https:' ? https.request : http.request;
+    const client = fn(proxy.origin, options as unknown as http.ClientRequestArgs);
 
     client.on('connect', (response, targetSocket, clientHead) => {
         countTargetBytes(sourceSocket, targetSocket);

src/server.ts

@@ -453,9 +453,9 @@ export class Server extends EventEmitter {
                 throw new Error(`Invalid "upstreamProxyUrl" provided: ${error} (was "${funcResult.upstreamProxyUrl}"`);
             }
 
-            if (!['http:', ...SOCKS_PROTOCOLS].includes(handlerOpts.upstreamProxyUrlParsed.protocol)) {
+            if (!['http:', 'https:', ...SOCKS_PROTOCOLS].includes(handlerOpts.upstreamProxyUrlParsed.protocol)) {
                 // eslint-disable-next-line max-len
-                throw new Error(`Invalid "upstreamProxyUrl" provided: URL must have one of the following protocols: "http", ${SOCKS_PROTOCOLS.map((p) => `"${p.replace(':', '')}"`).join(', ')} (was "${funcResult.upstreamProxyUrl}")`);
+                throw new Error(`Invalid "upstreamProxyUrl" provided: URL must have one of the following protocols: "http", "https", ${SOCKS_PROTOCOLS.map((p) => `"${p.replace(':', '')}"`).join(', ')} (was "${funcResult.upstreamProxyUrl}")`);
             }
         }
 

test/server.js

@@ -9,6 +9,7 @@ const util = require('util');
 const { expect, assert } = require('chai');
 const proxy = require('proxy');
 const http = require('http');
+const https = require('https');
 const portastic = require('portastic');
 const request = require('request');
 const WebSocket = require('faye-websocket');
@@ -1337,6 +1338,45 @@ it('supports localAddress', async () => {
     }
 });
 
+it('supports https proxy relay', async () => {
+    const target = https.createServer(() => {
+    });
+    target.listen(() => {
+    });
+
+    const proxyServer = new ProxyChain.Server({
+        port: 6666,
+        prepareRequestFunction: () => {
+            console.log(`https://localhost:${target.address().port}`);
+            return {
+                upstreamProxyUrl: `https://localhost:${target.address().port}`,
+            };
+        },
+    });
+    let proxyServerError = false;
+    proxyServer.on('requestFailed', () => {
+        // requestFailed will be called if we pass an invalid proxy url
+        proxyServerError = true;
+    })
+
+    await proxyServer.listen();
+
+    try {
+        await requestPromised({
+            url: 'https://www.google.com',
+            proxy: 'http://localhost:6666',
+            strictSSL: false,
+        });
+    } catch (e) {
+        // the request will fail with the following error:
+        // Error: tunneling socket could not be established, statusCode=599
+    }
+    expect(proxyServerError).to.be.equal(false);
+
+    proxyServer.close();
+    target.close();
+});
+
 it('supports custom CONNECT server handler', async () => {
     const server = new Server({
         port: 0,