Net::HTTPHeader#content_length

# File tmp/rubies/ruby-4.1.0-preview1/lib/net/http/header.rb, line 639
def content_length
  values = @header['content-length']
  return nil if values.nil?

  lengths = []
  values.each do |value|
    value = value.strip
    if value.empty?
      raise Net::HTTPHeaderSyntaxError,
            "empty Content-Length value"
    end
    lengths.concat(value.split(/\s*,\s*/, -1))
  end
  if lengths.uniq.size != 1
    raise Net::HTTPHeaderSyntaxError,
          "Content-Length has multiple different values: " +
          values.join(", ")
  end
  length = lengths.first
  unless /\A\d+\z/.match?(length)
    raise Net::HTTPHeaderSyntaxError,
          "wrong Content-Length format: #{length}"
  end
  length.to_i
end