From cb8d92befbbc0c5868b2a25147904a89091717df Mon Sep 17 00:00:00 2001
From: Jannis R <mail@jannisr.de>
Date: Sun, 7 Feb 2021 22:17:02 +0100
Subject: [PATCH] configure iface address used via LOCAL_ADDRESS env var

---
 lib/request.js | 28 +++++++++++++++++++++++++---
 package.json   |  1 +
 2 files changed, 26 insertions(+), 3 deletions(-)

diff --git a/lib/request.js b/lib/request.js
index f9f02de5..0db3ca4f 100644
--- a/lib/request.js
+++ b/lib/request.js
@@ -3,18 +3,40 @@
 const DEV = process.env.NODE_ENV === 'dev'
 const DEBUG = /\bhafas-client\b/.test(process.env.DEBUG || '')
 
+const ProxyAgent = require('https-proxy-agent')
+const {isIP} = require('net')
+const {Agent: HttpsAgent} = require('https')
+const roundRobin = require('@derhuerst/round-robin-scheduler')
 const {randomBytes} = require('crypto')
 const createHash = require('create-hash')
 const pick = require('lodash/pick')
 const captureStackTrace = DEV ? require('capture-stack-trace') : () => {}
 const {stringify} = require('qs')
-const ProxyAgent = require('https-proxy-agent')
 const Promise = require('pinkie-promise')
 const {fetch} = require('fetch-ponyfill')({Promise})
 const {addErrorInfo} = require('./errors')
 
 const proxyAddress = process.env.HTTPS_PROXY || process.env.HTTP_PROXY || null
-const proxyAgent = proxyAddress ? new ProxyAgent(proxyAddress) : null
+const localAddresses = process.env.LOCAL_ADDRESS || null
+
+if (proxyAddress && localAddresses) {
+	console.error('Both env vars HTTPS_PROXY/HTTP_PROXY and LOCAL_ADDRESS are not supported.')
+	process.exit(1)
+}
+let getAgent = () => null
+if (proxyAddress) {
+	const agent = new ProxyAgent(proxyAddress)
+	getAgent = () => agent
+} else if (localAddresses) {
+	const agents = process.env.LOCAL_ADDRESS.split(',')
+	.map((addr) => {
+		const family = isIP(addr)
+		if (family === 0) throw new Error('invalid local address:' + addr)
+		return new HttpsAgent({addr, family})
+	})
+	const pool = roundRobin(agents)
+	getAgent = () => pool.get()
+}
 
 const id = randomBytes(6).toString('hex')
 const randomizeUserAgent = (userAgent) => {
@@ -42,7 +64,7 @@ const request = (ctx, userAgent, reqData) => {
 	if (DEBUG) console.error(JSON.stringify(body))
 
 	const req = profile.transformReq(ctx, {
-		agent: proxyAgent,
+		agent: getAgent(),
 		method: 'post',
 		// todo: CORS? referrer policy?
 		body: JSON.stringify(body),
diff --git a/package.json b/package.json
index 0cce9f2c..4f50a861 100644
--- a/package.json
+++ b/package.json
@@ -40,6 +40,7 @@
 	},
 	"dependencies": {
 		"@derhuerst/br2nl": "^1.0.0",
+		"@derhuerst/round-robin-scheduler": "^1.0.4",
 		"capture-stack-trace": "^1.0.0",
 		"create-hash": "^1.2.0",
 		"fetch-ponyfill": "^7.0.0",