Return friendly error when AMQP 1.0 receiver has no source

[lukebakken]

When a client attaches an AMQP 1.0 receiver link without specifying a source address, RabbitMQ crashes with a function_clause error and returns an Erlang stack trace to the client. This makes it difficult for developers to understand what went wrong.

Previously, the client received:

SessionError: function_clause
[{rabbit_amqp_session,ensure_source,
     [undefined,false,<<...>>,<<...>>,
      {user,<<...>>,[administrator],[...]},
      <<...>>,<0.585.0>,[],[]],
     [{file,"rabbit_amqp_session.erl"},{line,2665}]},
 {rabbit_amqp_session,handle_attach,2,...},
 ...]

This change adds a new clause to ensure_source/9 that catches the case where the source is undefined. Instead of crashing, the function now returns {error, source_address_required}, which handle_attach/2 maps to an amqp:invalid-field error with a clear message.

Now, the client receives:

LinkError: Attach refused: source_address_required
  condition: 'amqp:invalid-field',
  description: 'Attach refused: source_address_required'

The error condition amqp:invalid-field is appropriate here because the client failed to provide a required field in the attach frame, not because a resource was not found.

Fixes #14300

[lukebakken]

@ansd I added the code to reproduce the error here - https://github.com/lukebakken/rabbitmq-server-14300

[ansd]

I added the code to reproduce the error here - https://github.com/lukebakken/rabbitmq-server-14300

Thank you.

Thanks. I merged and did a follow-up commit in #15152

[lukebakken]

Thanks. I merged and did a follow-up commit in

Any time you'd like to change something, feel free to change my code in a PR on my original branch. No need for a follow-up! 😸

[ansd]

feel free to change my code in a PR on my original branch

I don't have permissions to push to your branch? 🙃

[lukebakken]

Huh, I thought that pretty much always was the case with PR branches. The next time I open one, I'll make sure that's the case. Thanks for letting me know.

UPDATE: hm I bet amazon-mq/upstream-to-rabbitmq-server is an organization-owned fork, and thus that setting isn't available 💩