Hi Daniel!
Thank you for the pointers to some cookie enabled servers!
I tried my code and I see a strange behavior. I even checked with wireshark.
I do send a request with the cookie option. The response contains a cookie opt from the server, but I do not get back my client cookie.
My understanding of the RFC7873 is that the server copies the client cookie from the client request and appends its own server cookie.
Here is what I see
Server 212.80.96.32 Port 53 Zone interconnect.ch
Send Cookie 0x329dadee3437b0d1
Client Cookie 0xf34d81b343a10000 Server Cookie 0x40cec0ebbf00000040cec0ebbf000000
Test9 failure! Client cookie did not match
I tested with several doing something wrong?
/Ulrich