makeKey can not be redirected using shell

[Gunni]

• Program: dnsdist
• Issue type: Bug report

Short description

I was attempting to use echo "makeKey()" | dnsdist to get a usable console key, it works, but when I then did echo "makeKey()" | dnsdist | grep setKey it stopped working.

Environment

• Operating system: Fedora 30
• Software version: 1.3.3 (Lua 5.1.4 [LuaJIT 2.1.0-beta3]) with dns-over-tls(openssl) dnscrypt ebpf libsodium protobuf recvmmsg/sendmmsg systemd
• Software source: Operating system repository

Steps to reproduce

1. echo "makeKey()" | dnsdist works
2. echo "makeKey()" | dnsdist -C /dev/null works (config is not relevant)
3. echo "makeKey()" | dnsdist | cat does not work, because setKey is not printed when piped

Expected behaviour

The setKey line gets printed.

Actual behaviour

The setKey does not get printed when stdout/stderr is redirected.

Other information

makeKey is implemented here but I can not find where g_outputBuffer is printed.

Usecase

My idea was to make ansible run echo "makeKey()" | dnsdist | grep setKey > /etc/dnsdist/key/key.conf if it didn't exist and then to do a includeDirectory /etc/dnsdist/key in the main config file.

Description

It would be nice if there was a dnsdist --print-new-key command that just printed a new key, no reading configs, or starting the server or listening on sockets or anything.