Resolver Mangles Case

[gyCfjSnO]

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Prerequisites

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• I am running the latest version
• I checked the documentation and found no answer
• I checked to make sure that this issue has not already been filed

Issue Details

• Version of AdGuard Home server:
  • v0.106.3
• How did you install AdGuard Home:
  • AdGuard Ubuntu Appliance for Raspberry Pi
• How did you setup DNS configuration:
  • Router
• If it's a router or IoT, please write device model:
  • Asus RT-AX58U Asuswrt-merlin 386.3_2
• CPU architecture:
  • N/A
• Operating system and version:
  • N/A

Expected Behavior

RFC 1034, which defines DNS, states in Section 3.1 that the letter case of a query (i.e. whether the domain name is spelled in upper case, lower case or a mix of the two) should be preserved.

Actual Behavior

AdGuard Home does not preserve the letter case of queries

Additional Information

I discovered this as the RIPE Atlas Probe I am running gives an error message that the DNS queries it is sending out is not coming back in the same letter case.

I confirmed it to be AdGuard Home causing the issue as I first did nslookup on my PC using AdGuard Home using a mangled query to 'GooGle.com' but the result comes back as 'google.com'. When changing my DNS to 9.9.9.9 or 1.1.1.1 for example the mangled query comes back the same.

[ainar-g]

Sounds like a duplicate of #3194, which is fixed in the edge and beta channels.