fix redos

[ooooooo-q]

Fixed ReDoS when receiving crafted response headers.

PoC

require 'benchmark'

def attack_text(length)
  text = 'charset=' + "\t" * length + "a" + "\t" * length + "a"
  /\bcharset=\s*(.+?)\s*(;|$)/.match(text)
end

Benchmark.bm do |x|
  x.report { attack_text(10) }
  x.report { attack_text(100) }
  x.report { attack_text(1000) }
  x.report { attack_text(10000) }
  x.report { attack_text(100000) }
end

❯ bundle exec ruby encoded_body_benchmark.rb
       user     system      total        real
   0.000009   0.000001   0.000010 (  0.000006)
   0.000062   0.000001   0.000063 (  0.000063)
   0.005081   0.000026   0.005107 (  0.005110)
   0.513256   0.001069   0.514325 (  0.514344)
  53.361165   0.264545  53.625710 ( 53.686721)

[iMacTia]

This is some serious Regex stuff 👏 , thank you for finding and fixing this performance issue 🙏 !