Add middleware/erratic

[miekg]

This middleware allows playing with responses. Only one type is
implemented: it allows you to drop queries. I.e. withhold the response
from the client.

[johnbelamaric]

Nice! Should this be so uniform though? For example by default it drops every-other-query. I guess that's OK, but I wonder if there should be some randomness. I suppose if you have multiple clients it will appear essentially random, so it's probably not worth making it more complicated.

[miekg]

Yeah, had those thoughts as well, but went for the most simple solution. Upside of this is that testing is easier because of the non-randomness.

…

On 5 Jan 2017 10:51 pm, "John Belamaric" ***@***.***> wrote: ***@***.**** commented on this pull request. ------------------------------ In middleware/erratic/erratic.go <#471 (review)>: > +// Erratic is a middleware that returns erratic repsonses to each client. +type Erratic struct { + amount uint64 + + q uint64 // counter of queries +} + +// ServeDNS implements the middleware.Handler interface. +func (e *Erratic) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (int, error) { + state := request.Request{W: w, Req: r} + + drop := false + if e.amount > 0 { + queryNr := atomic.LoadUint64(&e.q) + + if queryNr%e.amount == 0 { Nice! Should this be so uniform though? For example by default it drops every-other-query. I guess that's OK, but I wonder if there should be some randomness. I suppose if you have multiple clients it will appear essentially random, so it's probably not worth making it more complicated. — You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub <#471 (review)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AAVkW6IRPT5T5QZtZMoBa-n0K95Zl2w1ks5rPXPqgaJpZM4LcNsM> .

[codecov-io]

Current coverage is 38.92% (diff: 73.77%)

Merging #471 into master will increase coverage by 0.41%

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+ Hits           2149       2196    +47   
- Misses         3255       3267    +12   
- Partials        176        178     +2   

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