Pass nil to Nginx::Headers_in[]= causes segmentaion fault

[yano3]

Pass nil to Nginx::Headers_in[]= causes segmentaion fault.

Reproduce

server {
    listen       80;

    location / {
        mruby_content_handler_code '
          h = Nginx::Headers_in.new
          Nginx.echo h["X-FOO"]
          h["X-FOO"] = nil
        ';
    }
}

$ curl -H "X-FOO: foo" http://localhost:10080/
curl: (52) Empty reply from server

The following error is output to error.log.

2020/08/17 07:34:24 [alert] 1#1: worker process 27 exited on signal 11

This also happen with Nginx::Headers_out[]= too.

[yyamano]

@yano3 Thank you for the report. What is the expected behavior? Is throwing an exception fine?

[yano3]

In my use case, there is no problem with the behavior of throwing an exception. I only expect to avoid segmentation fault.

IMO, following behavior is good.

• If specified header exists, delete it.
• If specified header does not exist, do nothing.

For example, it's natural in the following case.

h = Nginx::Headers_in.new

# get header that does not exist
foo = h["X-FOO"] # => nil
h["X-FOO"] = foo

[yyamano]

Sounds good. I just sent a pull request #475

[yano3]

Thank you!

[matsumotory]

@yano3 @yyamano Thank you for your proposal!