'DecodeError'will replace 'ExpiredSignature'

[cannotcodeanymore]

if you catch DecodeError, you will not get ExpiredSignature.

[excpt]

Hey @ctc1991,

thanks for reporting.

Can you provide sample code to reproduce this issue, please?

[standsleeping]

Hi there @excpt and @ctc1991. I similarly encountered this, and I believe this behavior is attributable to DecodeError being the parent error class of several decoding-related error classes, one of which happens to be ExpiredSignature.

So what this means is that if the code rescues DecodeError ahead of the others, the rescue block will always catch on DecodeError first.

Run this example:

DecodeError = Class.new(StandardError)
ExpiredSignature   = Class.new(DecodeError)

begin
  raise ExpiredSignature.new
rescue DecodeError => exception
  puts "#{exception.class} was raised, rescued in DecodeError"
rescue ExpiredSignature => exception
  puts "#{exception.class} was raised, rescued in ExpiredSignature"
end

This code outputs:

A ExpiredSignature was raised, rescued in DecodeError

Now, reverse the order of those rescue blocks, and the result becomes:

ExpiredSignature was raised, rescued in ExpiredSignature

Which is what I had originally intended when I laid out my first rescue chain.

This behavior can be avoided by making sure the code rescues DecodeError as a last/final measure in the rescue chain. That being said, the reason I happened to have rescued it as the first exception in my code was because it's the error that is raised when no token is present - which in my use case is most common.

By the way, @excpt if you think this is worth looking into, I'd be happy to help on making a change. We could either replace DecodeError as the parent to all of these with a new class (or just use StandardError for all of them), or we could create new specific error classes in the 4-or-so places where DecodeError is used explicitly and not as a parent class:

• 'Nil JSON web token'
• 'Not enough or too many segments'
• 'No verification key available'
• 'Invalid segment encoding'

Let me know! Thanks.