Per von Zweigbergk created GUACAMOLE-2290:
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Summary: White screen with no error message when localStorage
GUAC_AUTH_TOKEN is "undefined"
Key: GUACAMOLE-2290
URL: https://issues.apache.org/jira/browse/GUACAMOLE-2290
Project: Guacamole
Issue Type: Bug
Components: guacamole-client
Reporter: Per von Zweigbergk
I have run into an issue where Guacamole fails to load and presents the user
with a white screen, instead of the expected login page. Refreshing doesn't
resolve the issue.
After some investigation, I found an error message like this in the Javascript
console:
jquery.min.js:2 {color:#e10000}Uncaught SyntaxError: "undefined" is not valid
JSON at JSON.parse (<anonymous>) at a.getItem (localStorageService.js:125:25)
at h.getCurrentToken (authenticationService.js:466:36) at h.request
(authenticationService.js:536:34) at Object.getLanguages
(languageService.js:45:38) at v (translationLoader.js:74:25) at
translationLoader.js:149:9 at Object.invoke (angular.min.js:45:264){color}
| | |
The relevant code appears to be here:
[https://github.com/apache/guacamole-client/blame/27922fe19823942e7bc3a6b70560cebabec44e64/guacamole/src/main/frontend/src/app/storage/services/localStorageService.js#L125]
Investigating the local storage, the {{GUAC_AUTH_TOKEN}} value seems to be set
to the string "undefined" whenever this problem occurs.
I've not been able to figure out *why* the GUAC_AUTH_TOKEN value is set to
"undefined". It could be an interaction with the Barracuda WAF we have in
front. But either way, it appears there is a specific bug in this part of the
code. There is no proper handling of the exception thrown by the
JSON.parse(data) call, if data is invalid JSON (in this case, the string
"undefined").
Either way, the fact that guacamole-client itself chokes in case the
GUAC_AUTH_TOKEN value ends up being corrupted is a bug in its own right, and
could be easy enough to fix by just handling the SyntaxError exception being
thrown by JSON.parse and treating it as an empty value in this case.
As a workaround, I've been telling my users to run the following command in the
Javascript console to clear out this state:
{{localStorage.removeItem('GUAC_AUTH_TOKEN');}} and this seems to temporarilly
fix the issue, which leads me to believe that adding some guards around JSON
parsing and treating an unparsable value as missing would properly mask your
problem.
I'm up submitting a PR for this if this approach to the fix is accepted.
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