Passing correct host header to proxy in ProxyAgent (nodejs#1624)

* slight refactor of test

* failing test for nodejs#1623

* ProxyAgent passing correct host headers to proxy, fixes nodejs#1623

* add issue # to test

* import fetch for proxy text

lib/proxy-agent.js

@@ -60,7 +60,7 @@ class ProxyAgent extends DispatcherBase {
     }
 
     const resolvedUrl = new URL(opts.uri)
-    const { origin, port } = resolvedUrl
+    const { origin, port, host } = resolvedUrl
 
     const connect = buildConnector({ ...opts.proxyTls })
     this[kConnectEndpoint] = buildConnector({ ...opts.requestTls })
@@ -80,7 +80,7 @@ class ProxyAgent extends DispatcherBase {
             signal: opts.signal,
             headers: {
               ...this[kProxyHeaders],
-              host: opts.host
+              host
             }
           })
           if (statusCode !== 200) {

test/proxy-agent.js

@@ -1,7 +1,7 @@
 'use strict'
 
 const { test } = require('tap')
-const { request, setGlobalDispatcher, getGlobalDispatcher } = require('..')
+const { request, fetch, setGlobalDispatcher, getGlobalDispatcher } = require('..')
 const { InvalidArgumentError } = require('../lib/core/errors')
 const { readFileSync } = require('fs')
 const { join } = require('path')
@@ -240,8 +240,9 @@ test('use proxy-agent with setGlobalDispatcher', async (t) => {
   proxyAgent.close()
 })
 
-test('ProxyAgent correctly sends headers when using fetch - #1355', { skip: nodeMajor < 16 }, async (t) => {
-  const { getGlobalDispatcher, setGlobalDispatcher, fetch } = require('../index')
+test('ProxyAgent correctly sends headers when using fetch - #1355, #1623', { skip: nodeMajor < 16 }, async (t) => {
+  t.plan(2)
+  const defaultDispatcher = getGlobalDispatcher()
 
   const server = await buildServer()
   const proxy = await buildProxy()
@@ -250,7 +251,9 @@ test('ProxyAgent correctly sends headers when using fetch - #1355', { skip: node
   const proxyUrl = `http://localhost:${proxy.address().port}`
 
   const proxyAgent = new ProxyAgent(proxyUrl)
-  const oldDispatcher = getGlobalDispatcher()
+  setGlobalDispatcher(proxyAgent)
+
+  t.teardown(() => setGlobalDispatcher(defaultDispatcher))
 
   const expectedHeaders = {
     host: `localhost:${server.address().port}`,
@@ -263,16 +266,23 @@ test('ProxyAgent correctly sends headers when using fetch - #1355', { skip: node
     'accept-encoding': 'gzip, deflate'
   }
 
+  const expectedProxyHeaders = {
+    host: `localhost:${proxy.address().port}`,
+    connection: 'keep-alive'
+  }
+
+  proxy.on('connect', (req, res) => {
+    t.same(req.headers, expectedProxyHeaders)
+  })
+
   server.on('request', (req, res) => {
     t.same(req.headers, expectedHeaders)
     res.end('goodbye')
   })
 
-  setGlobalDispatcher(proxyAgent)
   await fetch(serverUrl, {
     headers: { 'Test-header': 'value' }
   })
-  setGlobalDispatcher(oldDispatcher)
 
   server.close()
   proxy.close()