Summary:
It's currently possible to crash React Native on iOS when using XMLHTTPRequest with onreadystatechange by having the server send a bunch of bad unicode (we found the problem when a bad deploy caused this to happen).
This is due to an integer overflow when handling carryover data in decodeTextData.
Create Express server with mock endpoint:
```js
var express = require('express');
var app = express();
app.get('/', function(req, res) {
res.writeHead(200, {'content-type': 'text/plain; charset=utf-8'});
res.flushHeaders();
res.write(new Buffer(Array(4097).join(0x48).concat(0xC2)));
res.write(new Buffer([0xA9]));
res.end();
});
app.listen(3000);
```
Create React Native application which tries to hit the endpoint:
```js
export default class App extends Component<{}> {
componentDidMount() {
const xhr = new XMLHttpRequest()
xhr.open('get', 'http://localhost:3000', true);
xhr.onreadystatechange = function () {
if(xhr.readyState === XMLHttpRequest.DONE && xhr.status === 200) {
console.warn(xhr.responseText);
}
};
xhr.send();
}
render() {
return null;
}
}
```
Observe that the application crashes when running master and doesn't when including the changes from this pull request.
[IOS] [BUGFIX] [RCTNetworking] - |Check against integer overflow when parsing response|
Closes https://github.com/facebook/react-native/pull/16286
Differential Revision: D6060975
Pulled By: hramos
fbshipit-source-id: 650e401a3bc033725078ea064f8fbca5441f9db5
1c04ceeb4b