Disable redirect in fetch request using React native - redirect

Question

I'm trying to crawl a web using React Native which has no API. It's written in PHP.
To log an user, a POST request must be sent. The response returns a cookie with a PHPSessid cookie which I must capture to use in subsequent requests.
I would like to capture the cookie value, buy the POST response is a 302 and the redirection is followed automatically, so I can't see the cookie. In node I was able to do it with redirect:manual, but it does not work in react native.
The cookie is sent automatically in subsequent requests, buy I'm trying to manage cookies by hand with react-native-cookie and I'd like to know if it's possible.
Do you know a way to stop the redirection?

Answer 1

I've been checking the code and what I did was the following:
Clear all cookies
Launch an empty login request
Capture the PHPSessID coookie
Launch a login request with that PHPSessID
After that, the subsequent fetch requests would have automatically a PHPSessID cookie with a valid logged in user, so we can use the site with simple fetchs
Here is some code, but the important thing is that you do a first empty login request, capture the PHPSessid and launch the real login request with that PHPSessid.
This would be the main function:
import Cookie from 'react-native-cookie';
// I think this is used only to clear the cookies
function login(user, pass){
// clear all cookies for all domains
// We need to start withouth authorization token
Cookie.clear();
const makeLoginRequest = (sessid) =>
makeLoginRequestForUserAndPass(user,pass,sessid);
return makeInitialRequest()
.then(getSessionIDFromResponse)
.then(makeLoginRequest)
.then(checkIfLoggedAndGetSessionID);
}
The initial request is a request to the login script. Note that I used GET because it worked with my site, perhaps an empty post would be necessary:
function makeInitialRequest() {
const INIT_PATH = '/index.php?r=site/login';
const INIT_URL = site + INIT_PATH;
const request = new Request(INIT_URL, options....);
return fetch(request);
}
We have the session ID in the response. I used a simple regex to extract it. Note that we are not logged in; PHP has created a session and that's what we have here:
function getSessionIDFromResponse(response) {
return getPHPSessIdFromCookie(response.headers.get('set-cookie'));
}
function getPHPSessIdFromCookie(header) {
const regex = /PHPSESSID=(\w*)/;
const match = regex.exec(header);
return match ? match[1] : '';
}
Now the login request. Note that I can't stop redirection here, but I't have to do it because we can have PHPSessid later. Redirection must be set to manual in POST request:
function makeLoginRequestForUserAndPass(user, pass, sessid) {
const request = buildLoginRequest(user, pass, sessid);
return fetch(request);
}
// This is where we build the real login request
function buildLoginRequest(user, pass, sessid) {
const LOGIN_PATH = '/index.php?r=site/login';
const LOGIN_URL = site + LOGIN_PATH;
const fields = [
{name: 'LoginForm[username]', value: user},
{name: 'LoginForm[password]', value: pass},
etc...
];
const data = translateFieldsToURLEncodedData(fields);
const headers = {
'Content-type': 'application/x-www-form-urlencoded',
Cookie: `PHPSESSID=${sessid}`, // HERE is where you put the data
};
const options = { method: 'POST',
headers: headers,
mode: 'cors',
cache: 'default',
agent: proxy,
body: data,
redirect: 'manual' // VERY IMPORTANT: if you don't do it, the cookie is lost
};
return new Request(LOGIN_URL, options);
}
// Simple utility function
function translateFieldsToURLEncodedData(fields){
let pairs = fields.map( (field) => {
return encodeURIComponent(field.name) + '=' + encodeURIComponent(field.value);
});
return pairs.join('&');
}
This is the last part. To see if I was logged in I checked if the response had text belonging to login error's page. I also got the PHPSessid (I think it changed after login, not sure, it was a year ago) but I don't know if I used it, I believe it was included automatically in subsequent requests. I think this part could be simplified an improved:
function checkIfLoggedAndGetSessionID(response) {
return (
checkIfLoggedOK(response)
.then(() => getSessionIDFromResponse(response))
);
}
function checkIfLoggedOK(response){
return getTextFromResponse(response)
.then(throwErrorIfNotLogedOk);
}
function getTextFromResponse(response) {
return response.text();
}
function throwErrorIfNotLogedOk(page) {
if(isErrorPage(page)) throw new Error("Login failed");
}
function isErrorPage(text) {
const ERROR_MESSAGE = 'Something that appears in login failed page of your site';
let n = text.search(ERROR_MESSAGE);
return n !== -1;
}
Hope this can be useful.