When accessing mongodb through SSL, Regexp attributes can't be read from the database. https://github.com/mongodb/bson-ruby/blob/master/lib/bson/regexp.rb#L156 hangs indefinitely as the options are NULL_BYTE terminated.

Note that this issue only occurs when connecting through SSL. On an unencrypted connection, options are indeed "0" terminated and the bug thus doesn't manifest itself using non-encrypted connections.

The parsing of the options itself is also subject to differences between SSL and non-SSL connections. I will submit an pull request shortly but also wanted to create an issue here for reference and discussion.

Test case in Rails:

class TestRecord
  include Mongoid::Document
  field :regex, type: Regexp
end

TestRecord.create(regex: //).reload # Will never return when connecting to MongoDB through SSL