undefined method `split` for 2:Integer when updating falcon

[renatolond]

Hey!

I'm not sure if this belongs here or in falcon, so sorry if it's better to be in Falcon instead. When I tried upgrading falcon to 0.42.x, I had an issue because I write an Integer header which used to be auto-converted and now it's not anymore.
Here's the backtrace:

 2.16s    error: Protocol::Rack::Adapter::Rack2 [oid=0x1860] [ec=0x1810] [pid=78517] [2022-08-30 11:04:33 +0200]
               |   NoMethodError: undefined method `split' for 2:Integer
               |
               |                                                        value.split("\n").each do |value|
               |                                                             ^^^^^^
               |   → /home/renatolond/.rvm/rubies/ruby-3.1.2-jemalloc/lib/ruby/gems/3.1.0/gems/protocol-rack-0.2.2/lib/protocol/rack/adapter/rack2.rb:112 in `block in wrap_headers'
               |     /home/renatolond/.rvm/rubies/ruby-3.1.2-jemalloc/lib/ruby/gems/3.1.0/gems/rack-2.2.4/lib/rack/utils.rb:449 in `block in each'
               |     /home/renatolond/.rvm/rubies/ruby-3.1.2-jemalloc/lib/ruby/gems/3.1.0/gems/rack-2.2.4/lib/rack/utils.rb:448 in `each'
               |     /home/renatolond/.rvm/rubies/ruby-3.1.2-jemalloc/lib/ruby/gems/3.1.0/gems/rack-2.2.4/lib/rack/utils.rb:448 in `each'
               |     /home/renatolond/.rvm/rubies/ruby-3.1.2-jemalloc/lib/ruby/gems/3.1.0/gems/protocol-rack-0.2.2/lib/protocol/rack/adapter/rack2.rb:106 in `wrap_headers'
               |     /home/renatolond/.rvm/rubies/ruby-3.1.2-jemalloc/lib/ruby/gems/3.1.0/gems/protocol-rack-0.2.2/lib/protocol/rack/adapter/rack2.rb:84 in `call'
               |     /home/renatolond/.rvm/rubies/ruby-3.1.2-jemalloc/lib/ruby/gems/3.1.0/gems/protocol-http-0.23.10/lib/protocol/http/middleware.rb:50 in `call'
               |     /home/renatolond/.rvm/rubies/ruby-3.1.2-jemalloc/lib/ruby/gems/3.1.0/gems/protocol-rack-0.2.2/lib/protocol/rack/rewindable.rb:58 in `call'
               |     /home/renatolond/.rvm/rubies/ruby-3.1.2-jemalloc/lib/ruby/gems/3.1.0/gems/protocol-http-0.23.10/lib/protocol/http/middleware.rb:50 in `call'
               |     /home/renatolond/.rvm/rubies/ruby-3.1.2-jemalloc/lib/ruby/gems/3.1.0/gems/protocol-http-0.23.10/lib/protocol/http/content_encoding.rb:46 in `call'
               |     /home/renatolond/.rvm/rubies/ruby-3.1.2-jemalloc/lib/ruby/gems/3.1.0/gems/protocol-http-0.23.10/lib/protocol/http/middleware.rb:50 in `call'
               |     /home/renatolond/.rvm/rubies/ruby-3.1.2-jemalloc/lib/ruby/gems/3.1.0/gems/async-http-0.59.2/lib/async/http/server.rb:67 in `block in accept'
               |     /home/renatolond/.rvm/rubies/ruby-3.1.2-jemalloc/lib/ruby/gems/3.1.0/gems/async-http-0.59.2/lib/async/http/protocol/http1/server.rb:62 in `each'
               |     /home/renatolond/.rvm/rubies/ruby-3.1.2-jemalloc/lib/ruby/gems/3.1.0/gems/async-http-0.59.2/lib/async/http/server.rb:56 in `accept'
               |     /home/renatolond/.rvm/rubies/ruby-3.1.2-jemalloc/lib/ruby/gems/3.1.0/gems/async-io-1.34.0/lib/async/io/server.rb:32 in `block in accept_each'
               |     /home/renatolond/.rvm/rubies/ruby-3.1.2-jemalloc/lib/ruby/gems/3.1.0/gems/async-io-1.34.0/lib/async/io/socket.rb:73 in `block in accept'
               |     /home/renatolond/.rvm/rubies/ruby-3.1.2-jemalloc/lib/ruby/gems/3.1.0/gems/async-1.30.3/lib/async/task.rb:261 in `block in make_fiber'

I use grape for my API, here's an example code that has the issue

# frozen_string_literal: true

# A sample Gemfile
source "https://rubygems.org"

gem "grape"
gem "falcon"

#!/usr/bin/env falcon --verbose serve -c
# frozen_string_literal: true

# Save this as `config.ru`, make it executable and then run it (or run falcon serve by hand)

# Middleware that responds to incoming requests:
require 'grape'
class MyApp < Grape::API
  get "/" do
    header "my-header", 123
    "ok"
  end
end

run MyApp

My tests did not catch the issue, rack-test accepts the integer header and I'm assuming casts it to a string.

[bragovo]

The same thing, in my case: x-cache-hit: false, so, false can't be splitted.

[ioquatix]

I believe in this case, the header value should be a string.

Maybe Rack::Protocol should call to_s on header values. Let me check what the spec says.

[ioquatix]

Header values must be either a String instance, or an Array of String instances, such that each String instance must not contain characters below 037.

https://github.com/rack/rack/blob/main/SPEC.rdoc#the-headers-

[ioquatix]

Okay, I've opted to fix this by allowing non-string header values, which is an extension of the Rack spec. You may find that your applications are incompatible with other Rack web servers or middleware. The correct solution is to ensure your header values are strings, not integers, e.g. "123" in your example.

[ioquatix]

cc @dblock for visibility, since the original issue was header x, y allowing non-string values. Just a thought: maybe grape can call #to_s if this is acceptable, or issue a warning, etc.

[dblock]

thanks @ioquatix for tagging me - I don't quite fully remember/understand the details here, would you be so kind to open an issue in https://github.com/ruby-grape/grape/issues/new and explain in which cases grape is going to start breaking? :)