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const Minipass = require('minipass')
const MinipassPipeline = require('minipass-pipeline')
const fetch = require('minipass-fetch')
const promiseRetry = require('promise-retry')
const ssri = require('ssri')
const getAgent = require('./agent.js')
const pkg = require('../package.json')
const USER_AGENT = `${pkg.name}/${pkg.version} (+https://npm.im/${pkg.name})`
const RETRY_ERRORS = [
'ECONNRESET', // remote socket closed on us
'ECONNREFUSED', // remote host refused to open connection
'EADDRINUSE', // failed to bind to a local port (proxy?)
'ETIMEDOUT', // someone in the transaction is WAY TOO SLOW
'ERR_SOCKET_TIMEOUT', // same as above, but this one comes from agentkeepalive
// Known codes we do NOT retry on:
// ENOTFOUND (getaddrinfo failure. Either bad hostname, or offline)
]
const RETRY_TYPES = [
'request-timeout',
]
// make a request directly to the remote source,
// retrying certain classes of errors as well as
// following redirects (through the cache if necessary)
// and verifying response integrity
const remoteFetch = (request, options) => {
const agent = getAgent(request.url, options)
if (!request.headers.has('connection'))
request.headers.set('connection', agent ? 'keep-alive' : 'close')
if (!request.headers.has('user-agent'))
request.headers.set('user-agent', USER_AGENT)
// keep our own options since we're overriding the agent
// and the redirect mode
const _opts = {
...options,
agent,
redirect: 'manual',
}
return promiseRetry(async (retryHandler, attemptNum) => {
const req = new fetch.Request(request, _opts)
try {
let res = await fetch(req, _opts)
if (_opts.integrity && res.status === 200) {
// we got a 200 response and the user has specified an expected
// integrity value, so wrap the response in an ssri stream to verify it
const integrityStream = ssri.integrityStream({ integrity: _opts.integrity })
res = new fetch.Response(new MinipassPipeline(res.body, integrityStream), res)
}
res.headers.set('x-fetch-attempts', attemptNum)
// do not retry POST requests, or requests with a streaming body
// do retry requests with a 408, 420, 429 or 500+ status in the response
const isStream = Minipass.isStream(req.body)
const isRetriable = req.method !== 'POST' &&
!isStream &&
([408, 420, 429].includes(res.status) || res.status >= 500)
if (isRetriable) {
if (typeof options.onRetry === 'function')
options.onRetry(res)
return retryHandler(res)
}
return res
} catch (err) {
const code = (err.code === 'EPROMISERETRY')
? err.retried.code
: err.code
// err.retried will be the thing that was thrown from above
// if it's a response, we just got a bad status code and we
// can re-throw to allow the retry
const isRetryError = err.retried instanceof fetch.Response ||
(RETRY_ERRORS.includes(code) && RETRY_TYPES.includes(err.type))
if (req.method === 'POST' || isRetryError)
throw err
if (typeof options.onRetry === 'function')
options.onRetry(err)
return retryHandler(err)
}
}, options.retry).catch((err) => {
// don't reject for http errors, just return them
if (err.status >= 400 && err.type !== 'system')
return err
throw err
})
}
module.exports = remoteFetch