Скачать или смотреть Resolving SSO Issues in Custom Teams Person Tabs

Discover how to fix Single Sign-On (SSO) issues for custom Microsoft Teams Person Tabs, specifically when using C# MVC applications. We'll explore the solution and implications of removing authentication properties.
---
This video is based on the question https://stackoverflow.com/q/77309753/ asked by the user 'Clownish Carnage' ( https://stackoverflow.com/u/300172/ ) and on the answer https://stackoverflow.com/a/77309754/ provided by the user 'Clownish Carnage' ( https://stackoverflow.com/u/300172/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

Visit these links for original content and any more details, such as alternate solutions, latest updates/developments on topic, comments, revision history etc. For example, the original title of the Question was: Custom Teams Person Tab's SSO no longer working

Also, Content (except music) licensed under CC BY-SA https://meta.stackexchange.com/help/l...
The original Question post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license, and the original Answer post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license.

If anything seems off to you, please feel free to write me at vlogize [AT] gmail [DOT] com.
---
Troubleshooting SSO Issues in Custom Teams Person Tabs

When developing custom applications for Microsoft Teams, many developers implement Single Sign-On (SSO) functionality to streamline user authentication. However, encountering issues with SSO can be frustrating — particularly when updates and changes to the Teams environment interfere with previously functioning solutions. Recently, we faced an SSO problem in our custom Teams tab application that needed a careful examination. Let’s dive into the problem and how we resolved it.

The Problem: SSO No Longer Working

Our scenario began when a client reported that the SSO functionality in our custom Teams tab application was not working correctly. This issue surfaced specifically in Teams Classic and later in the new Teams Public Preview (2023). Given that our application was built using C# MVC, we relied on SSO for user authentication through access tokens.

The flow on the welcome page involved checks to determine if the application was running in the Teams desktop client or a web browser. If it detected the Teams desktop application, it would attempt to retrieve the access token. The code snippet responsible for this included a significant portion for handling authentication:

[[See Video to Reveal this Text or Code Snippet]]

However, despite our efforts to troubleshoot, we faced consistent failures in functionality across different clients.

Diagnosis: Exploring the Code and Environment

After three weeks of debugging, we needed to compare our code against working examples. When an external developer reviewed our SSO handling code, they found that our SSO method only malfunctioned when we included authenticationProperties in HttpContext.SignInAsync. This was a critical discovery that led us to consider the implementation of our SSO solution in relation to recent updates in Teams.

Why the Issue Happened

We speculated that the issue stemmed from the transition of the Teams backend from Chromium to Microsoft Edge in the Public Preview’s rollout. Microsoft Edge imposes stricter cookie length limits (4096 bytes), which might have affected how our access token — a considerable 2222 characters long — was being processed and stored in memory.

The Solution: Removing Authentication Properties

Upon identifying the problematic code piece, we tested the removal of the following line:

[[See Video to Reveal this Text or Code Snippet]]

This action resolved the issue, leading to successful SSO functionality across affected clients. While we lamented the loss of the token storage capability, we noted that the immediate problem was resolved without apparent negative impacts on user experience.

What This Means for Developers

Removing the StoreTokens functionality begs the question: What are the potential long-term consequences? Here are some considerations:

Token Storage: If you do choose to omit token storage, be aware that your application may lose access to the authentication tokens unless you find alternative storage methods.

Security: Depending on how tokens are managed post-removal, ensuring secure token handling practices will be essential for protecting user data.

User Experience: Monitor user feedback to determine if this change impacts the authentication process on the user end.

Conclusion

The shift from Chromium to Edge in Teams could lead to unexpected changes in how SSO functions, particularly in custom applications. Always be ready to adapt your code and examine the consequences of any changes, especially regarding authentication properties. Keeping an eye on updates from Microsoft could also be beneficial to preemptively catch any new poten