When receiving a large uid set, net-imap will consume a significant amount of CPU resources and take long time to raise ResponseParseError.

[xiaoge1001]

The test code comes from:
GHSA-7fc5-f82f-cx69

require "net/imap"

def test(size)
  input = "A004 OK [COPYUID 1 1:#{size} 1:#{size}] too large?\r\n"
  parser = Net::IMAP::ResponseParser.new
  parser.parse input
end

when size = 99999999:

when size = 4294967295:

when size = 4294967295, it occupies over 90% of CPU resources:

[nevans]

Ah, thanks for catching that. I used Range#count but I should've used Range#size!

[nevans]

Fortunately this is only an issue for v0.3. v0.4 and v0.5 both use Net::IMAP::SequenceSet, which uses a much more efficient ranges.sum(count) {|min, max| max - min }

[nevans]

It looks like Range#count in ruby 3.3 and 3.4 doesn't have this issue, which must be why I never noticed it during testing. ruby 2.6 through 3.2 are all affected. I'll have an update later today or tomorrow.

[xiaoge1001]

It looks like Range#count in ruby 3.3 and 3.4 doesn't have this issue, which must be why I never noticed it during testing. ruby 3.1 and 3.2 are both affected. I'll have an update later today or tomorrow.

Thanks for your quick response, the problem has been resolved.