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Forum Discussion
Can't get PKCE access token uses javascript fetch request
I am trying to utilize the PKCE in a background script of chrome extension
example shows the following:
curl https://api.dropbox.com/oauth2/token \
-d code=<AUTHORIZATION_CODE> \
-d grant_type=authorization_code \
-d code_verifier=<CODE_VERIFIER> \
-d client_id=<APP_KEY>
my code:
var dbxParams = new URLSearchParams({
client_id: client_id,
grant_type: "authorization_code",
code: access_code,
code_verifier: code_verifier,
});
var url = "https://api.dropbox.com/oauth2/token";
fetch(url, {
method: 'POST',
body: dbxParams
})
.then(function(response){
return response.json()
})
.then(function (data) {
console.log('Request succeeded with JSON response', data);
})
.catch(function (error) {
console.log('Request failed', error);
});
i always get the same reply:
{"error_description": "No auth function available for given request", "error": "invalid_request"}
can you help?
yes!
that was the problem
my apologies I missed these arguments in the request URLhowever,
i am now getting the error{error: 'invalid_grant', error_description: 'invalid code verifier'}The URL includes both code_challenge and code_challenge_method
and looks like:https://www.dropbox.com/oauth2/authorize?response_type=code&client_id=<client_id>&code_challenge=<code_challenge>&code_challenge_method=S256
and the parameters sent to oauth2/token are:client_id=<client_id>&grant_type=authorization_code&code=<auth code from dropbox>&code_verifier=<128 char verifier>i also made sure that <code challenge> is a SHA256 hash of <128 char verifier> by testing it at https://emn178.github.io/online-tools/sha256.html
what am i missing?
- Greg-DB
Dropbox Staff
ancso Is this the exact code you're running? I just gave it a try and it works for me when I plug in my own client_id, access_code, and code_verifier. (For reference, redirect_uri is optional in this flow, so that shouldn't be an issue.)
The "No auth function available for given request" error should indicate that the necessary authorization information, such as "code", etc., weren't provided (or weren't provided in a correct format that the Dropbox API servers understood). Can you check the network request, using the developer tools, to see what is/isn't being sent?
according to the de tools all parameters are sent
could it be that one of them is simply of wrong type?
if so I suppose it will be the calculation of the code_verifier
for such a small task i did not want to import a library so i have the following code:var code_verifier = ''; var codeChallenge = ''; /** * */ setDropboxCodes(){ var codes = {}; const base64Encode = (str) => { return str.toString('base64') .replace(/\+/g, '-') .replace(/\//g, '_') .replace(/=/g, ''); } codeVerifier = base64Encode(getRandomString(128)); var code256 = _self.sha256(codes['codeVerifier']) .codeChallenge = base64Encode(code256); } /** * */ getRandomString(length) { var randomChars = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789'; var result = ''; for ( var i = 0; i < length; i++ ) { result += randomChars.charAt(Math.floor(Math.random() * randomChars.length)); } return result; }- Greg-DB
Could you elaborate on what you mean when you say "according to the de tools all parameters are sent"? For instance, could you show the request (headers and body) that your client is sending? Be sure to redact any sensitive values themselves though.
If a parameter was being sent in the correct format but had an incorrect value, the API should respond with a different message than the one you're getting.
Also, it's worth mentioning that I'm not running this in the context of a Chrome extension, so that may be contributing to the difference.
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