klaemo opened a new issue, #375:
URL: https://github.com/apache/couchdb-nano/issues/375
## Expected Behavior
If the connection breaks off after CouchDB (or a proxy in front of it) has
sent the response headers but before the body is complete, the request promise
should reject. nano 10 (axios) did this.
## Current Behavior
In nano 11 the result depends on the response's content type:
- **`application/json`** (e.g. `db.get`, `db.list`, `db.view`): the request
**resolves with `''`**. `responseHandler` in `lib/nano.js` wraps `await
response.json()` in `try { … } catch { // do nothing }`. That catch was meant
for bodies that aren't valid JSON, but it also catches undici's `TypeError:
terminated` when the body read fails. So `db.get()` of an existing document
resolves `""`. Callers see something like a missing document, crash later with
a `TypeError`, or, worst case, write `{ ...doc }` with `doc === ''` back as a
new document.
- **`text/*`, `multipart/related` and binary bodies** (e.g.
`db.attachment.get`): `response.text()` / `response.arrayBuffer()` throws
inside the async `responseHandler`. `relax()` doesn't await or return it
(`.then((response) => { responseHandler(…) })`), so the request promise **never
settles**. The rejection is unhandled, which crashes the process under Node's
default `--unhandled-rejections=throw`; if the app has an `unhandledRejection`
handler, the call just hangs.
Error responses (non-2xx) aren't affected: if reading the error body fails,
the request still rejects with the status code. Streaming requests
(`*AsStream`) take a separate code path.
## Possible Solution
1. In the 2xx JSON branch, read the body with `response.text()` and only
wrap `JSON.parse()` in the try/catch. A failed read then propagates, and a
complete body that isn't JSON still resolves `''` as it does today.
2. In `relax()`, return the `responseHandler(…)` promise from the `.then()`
callback so that the existing `.catch()` handles failures. A body-read failure
then rejects the same way a connection failure before the headers does: `error
happened in your connection. Reason: SocketError: other side closed`.
I have a patch with tests ready and will open a PR referencing this issue.
## Steps to Reproduce (for bugs)
1. Save this as `repro.js` next to an install of `[email protected]`:
```js
const http = require('node:http')
const Nano = require('nano')
const contentType = process.argv[2] || 'application/json'
// answer 200, promise 100 bytes, send part of a document, then drop the
connection
const server = http.createServer((req, res) => {
res.writeHead(200, { 'content-type': contentType, 'content-length': 100
})
res.write('{"_id":"meta","type":"ev')
setTimeout(() => res.socket.destroy(), 10)
})
server.listen(0, '127.0.0.1', async () => {
const db = Nano(`http://127.0.0.1:${server.address().port}`).use('db')
try {
console.log('resolved:', JSON.stringify(await db.get('meta')))
} catch (e) {
console.log('rejected:', e.message)
}
server.closeAllConnections()
server.close()
})
```
2. `node repro.js` prints `resolved: ""`.
3. `node repro.js text/plain` crashes with an unhandled `TypeError:
terminated` (`[cause]: SocketError: other side closed`). `db.get()` never
settles.
4. Expected in both cases: `rejected: …`.
## Context
I found this while upgrading an app from nano 10 to 11. On a dropped
connection, a `db.get()` of an existing document returned `""` instead of
throwing, and the app treated the document as missing. We're carrying a local
patch for now.
## Your Environment
* Version used: nano 11.0.7 (also current `main`, 53dea92)
* Node.js: 24.21.0 (also reproduced on 20.20.2)
* Operating System and version: Ubuntu 24.04 (Linux 6.8)
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