fix: retry downloads on retryable errors (#3308)

Assisted-by: Claude Opus 4.6

Signed-off-by: David Sanders <dsanders11@ucsbalum.com>

Author: dsanders11

lib/download.js

@@ -1,5 +1,5 @@
 const { Readable } = require('stream')
-const { EnvHttpProxyAgent } = require('undici')
+const { Agent, EnvHttpProxyAgent, RetryAgent } = require('undici')
 const { promises: fs } = require('graceful-fs')
 const log = require('./log')
 
@@ -48,7 +48,7 @@ async function createDispatcher (gyp) {
   const env = process.env
   const hasProxyEnv = env.http_proxy || env.HTTP_PROXY || env.https_proxy || env.HTTPS_PROXY
   if (!gyp.opts.proxy && !gyp.opts.cafile && !hasProxyEnv) {
-    return undefined
+    return new RetryAgent(new Agent(), { maxRetries: 3 })
   }
 
   const opts = {}
@@ -69,7 +69,7 @@ async function createDispatcher (gyp) {
   if (gyp.opts.noproxy) {
     opts.noProxy = gyp.opts.noproxy
   }
-  return new EnvHttpProxyAgent(opts)
+  return new RetryAgent(new EnvHttpProxyAgent(opts), { maxRetries: 3 })
 }
 
 async function readCAFile (filename) {

test/test-download.js

@@ -218,6 +218,32 @@ describe('download', function () {
     assert.notStrictEqual(cas[0], cas[1])
   })
 
+  it('download will retry on ECONNRESET', async function () {
+    let requestCount = 0
+    const server = http.createServer((req, res) => {
+      requestCount++
+      if (requestCount < 3) {
+        req.socket.destroy()
+        return
+      }
+      res.end('ok')
+    })
+
+    after(() => new Promise((resolve) => server.close(resolve)))
+
+    const host = 'localhost'
+    await new Promise((resolve) => server.listen(0, host, resolve))
+    const { port } = server.address()
+    const gyp = {
+      opts: {},
+      version: '42'
+    }
+    const url = `http://${host}:${port}`
+    const res = await download(gyp, url)
+    assert.strictEqual(await res.text(), 'ok')
+    assert.ok(requestCount >= 2, `expected at least 2 requests but got ${requestCount}`)
+  })
+
   // only run this test if we are running a version of Node with predictable version path behavior
 
   it('download headers (actual)', async function () {