B4J Question Get URI fragment portion

Blueforcer · Feb 16, 2024

im trying to create a authentication flow for Twich.

Getting OAuth Access Tokens

dev.twitch.tv

i started a server wich listens to the callback url, wich already works, but im unable to get the token.

the important part of the documentation:

B4X:

If the user authorizes your application by clicking Authorize, the server sends the access token to your redirect URI in the fragment portion of the URI (see the access_token parameter):

http://localhost:3000/
    #access_token=73d0f8mkabpbmjp921asv2jaidwxn
    &scope=channel%3Amanage%3Apolls+channel%3Aread%3Apolls
    &state=c3ab8aa609ea11e793ae92361f002671
    &token_type=bearer

NOTE In JavaScript, you can access the fragment using document.location.hash.

How can i get the token?

i also tried to open the authorization page in a webview instead of the local browser, but here i also dont get the token.

aeric · Feb 16, 2024

B4X:

Dim url As String = $"http://localhost:3000/
#access_token=73d0f8mkabpbmjp921asv2jaidwxn
&scope=channel%3Amanage%3Apolls+channel%3Aread%3Apolls
&state=c3ab8aa609ea11e793ae92361f002671
&token_type=bearer"$
Dim access_token As String = url.SubString2(url.IndexOf("#access_token="), url.IndexOf("&")).Trim.Replace("#access_token=", "")
Log(access_token)

Blueforcer · Feb 16, 2024

aeric said:

B4X:

Dim url As String = $"http://localhost:3000/
#access_token=73d0f8mkabpbmjp921asv2jaidwxn
&scope=channel%3Amanage%3Apolls+channel%3Aread%3Apolls
&state=c3ab8aa609ea11e793ae92361f002671
&token_type=bearer"$
Dim access_token As String = url.SubString2(url.IndexOf("#access_token="), url.IndexOf("&")).Trim.Replace("#access_token=", "")
Log(access_token)

Not really. I need to get the token from the response URl wich isnt directly visible in the URI

Daestrum · Feb 16, 2024

I may be wrong but I don't believe anything after # actually gets sent to the server.

In your example url

http://localhost:3000/#access_token=73d0f8mkabpbmjp921asv2jaidwxn&scope=channel%3Amanage%3Apolls+channel%3Aread%3Apolls&state=c3ab8aa609ea11e793ae92361f002671&token_type=bearer

All the server sees is

http://localhost:3000/

You will need to add some javascript to get it sent to server
you need to send document.location.href like

B4X:

Sub Handle(req As ServletRequest, resp As ServletResponse)
    Log("in test")
    Log(req.GetParameter("from"))
    resp.Write($"<html><form action="/login" method="post">
  <div>
    <label>Username:</label>
    <input type="text" name="username"/><br/>
  </div>
  <div>
    <label>Password:</label>
    <input type="password" name="password"/>
  </div>
  <!-- XXXXXXXXX CLEVER BIT XXXXXXXXXX-->
  <script>
    document.write('<input type="hidden" name="from" value="'+document.location.href+'"/>');
  </script>
  <!-- XXXXXXXXXX-->
  <div>
    <input class="submit-button" type="submit" value="Submit"/>
  </div>
</form></html>"$)
   
End Sub

you can then use

B4X:

req.GetParameter("from")

which gives you

http://localhost:51042/#access_token=73d0f8mkabpbmjp921asv2jaidwxn&scope=channel%3Amanage%3Apolls+channel%3Aread%3Apolls&state=c3ab8aa609ea11e793ae92361f002671&token_type=bearer

and get the #access_token from that string

Original code posted on SO https://stackoverflow.com/questions/8033537/getting-hash-parameters-from-request-url

Blueforcer · Feb 18, 2024

Thanks for the Hint. This is working:

B4X:

Sub server_Handle (req As ServletRequest, resp As ServletResponse)
    If req.GetRequestURI = "/token" Then
        Dim accessToken As String = req.ParameterMap.Get("access_token")
        Log(accessToken)
    Else
        resp.SendString($"<!DOCTYPE html>
            <html>
            <body>
            <script>
            if(window.location.hash) {
                const hash = window.location.hash.substring(1);
                const params = new URLSearchParams(hash);
                const accessToken = params.get('access_token');
                fetch('http://localhost:3000/token?access_token=' + accessToken);
            }
            </script>
            </body>
            </html>"$)
    End If
End Sub

B4J Question Get URI fragment portion

Blueforcer

Well-Known Member

Getting OAuth Access Tokens

aeric

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Blueforcer

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Daestrum

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Blueforcer

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