Setting schema-less URL for proxy URLs results in NullPointerException

[aaronq]

In slack-api-client v1.28.0, there seems to be a bug with whole proxies can be set in the SlackConfig object.

Upon initialization of SlackConfig, it will call initProxyUrl() which looks at a bunch of system variables and if they are not set, environment variables. I believe the code is expecting HTTPS_PROXY or HTTP_PROXY to be set to the full url of the proxy (eg. http://proxy.com:8080/) which gets parsed later in ProxyUrlUtil.parse().

However, in our case, these environment variables are set with the syntax(which I believe is the norm) - hostname:port (eg. proxy.somewhere.com:8080) so when it gets parsed, it will throw a NPE when it tries to split the proxy string by ://.

Also it seems that setting slackConfig.setProxy() manually takes no effect after the config has been initialized and it has found a value in one of these variables.

The Slack SDK version

[INFO] +- com.slack.api:bolt-socket-mode:jar:1.28.0:compile
[INFO] | +- com.slack.api:slack-api-model:jar:1.28.0:compile
[INFO] | +- com.slack.api:slack-api-client:jar:1.28.0:compile
[INFO] | +- com.slack.api:slack-app-backend:jar:1.28.0:compile
[INFO] | - com.slack.api:bolt:jar:1.28.0:compile

Java Runtime version

openjdk version "11.0.9" 2020-10-20 LTS
OpenJDK Runtime Environment Zulu11.43+54-SA (build 11.0.9+11-LTS)
OpenJDK 64-Bit Server VM Zulu11.43+54-SA (build 11.0.9+11-LTS, mixed mode)

OS info

ProductName: macOS
ProductVersion: 13.2.1
BuildVersion: 22D68
Darwin Kernel Version 22.3.0: Mon Jan 30 20:42:11 PST 2023; root:xnu-8792.81.3~2/RELEASE_X86_64

Steps to reproduce:

Export HTTPS_PROXY='proxy.somewhere.com:8080' to set the environment variable

SlackConfig slackConfig = new SlackConfig();
slack = Slack.getInstance(slackConfig);

You should get NPE after you try running this code

Expected result:

Proxy logic should be able to handle the case where it doesn't have a scheme associated with it, and just generate the url if it sees that its only hostname:port

Actual result:

NPE happens because in this part of the code in ProxyUrlUtil#parse():

 String[] proxyUrlElements = proxyUrl.split("://");
 String schema = proxyUrlElements[0] + "://";
 String urlWithoutSchema = proxyUrlElements[1];

Will NPE when it tries to grab a value from proxyUrlElements[1]

It would be nice if slackConfig.setProxy() would work after the the SlackConfig is initialized. I think it works if the library detects no environment variables and proxyUrl is null. (At least this is what happens in v1.13.0 of the library, but because this version does not try to look at the HTTPS_PROXY and HTTP_PROXY environment variables)

[seratch]

Hi @aaronq, thanks for reporting this. The parsing logic can be improved in future releases.

It would be nice if slackConfig.setProxy() would work after the the SlackConfig is initialized.

I am not sure if we can do this properly but will check.

[seratch]

I'll come up with a pull request for fixing the error with schema-less patterns and the change will be released in the next patch version shortly. However, the second point need careful consideration (consistency, race condition etc.) and efforts. So, I've created a new issue for it: #1132