error handling: edge cases

[arnaudgeiser]

The error-handling branch contains a lot of changes we are not really comfortable with to safely integrate them on master. Still, this branch contains some unit tests that are valuable.

Instead of trying to rebase this branch on top of master, I decided to start from the unit tests and add the fixes for the tests that were failing. Here is how I end up with this PR.

As a reminder, here is what @kachayev intended to address :

• both servers and clients close connection (context, to be more precise) in case of exceptions
• error-logger parameter is added for HTTP client/server, Websocket client/server to customize exceptions logging for those exceptions that could not be visible to user's code in any other way (e.g. something that happens within HTTP server pipeline)
• TimeoutException handlers are fixed in HTTP client (to avoid double disposal of the connections)
• HTTP decoder errors are now properly handled to deal with bad traffic, error code statuses are fixed
• HTTP client propagates throwable to the caller whenever possible (rather than just relying on connection being closed later)
• :aleph/interrupted? flag is introduce as a part of ring request object for HTTP server, making it's possible to track if streaming body was closed because of an error (e.g. decoder exception, premature close, etc)
• a lot of unit tests to check failure scenarios

Some bits of those issues were fixed on various PR over last year. This PR brings only some improvements on the following topics:

• HTTP decoder errors are now properly handled to deal with bad traffic, error code statuses are fixed
  • HTTP client propagates throwable to the caller whenever possible (rather than just relying on connection being closed later)
  • a lot of unit tests to check failure scenarios

I would propose to merge this PR and close this one : https://github.com/clj-commons/aleph/pull/553

[arnaudgeiser]

Rebased on master, no changes.

[arnaudgeiser]

On my side, I consider this ready. Ignore the last commit as it's part of another PR for tests stabilization [1]

[1] : https://github.com/clj-commons/aleph/pull/661

[KingMob]

See my comment in the other PR about using port 0 for simpler, safer randomization.

[arnaudgeiser]

Comments addressed. Having a look at the diff might be simpler than looking at the last commit.

[arnaudgeiser]

I will rebase when the PR has been Approved (+ resolve conflicts and revert the changes to TCP/UDP tests)

[KingMob]

Merge when ready 👍🏻