[dnsdist] DynBlockRulesGroup function call exception

[chunyuliu106667777]

Release note:
dnsdist 1.8.4 (Lua 5.1.4 [LuaJIT 2.1.0-beta3])
Enabled features: cdb dns-over-tls(gnutls openssl) dns-over-https(DOH) dnscrypt ebpf fstrm ipcipher libedit libsodium lmdb outgoing-dns-over-https(nghttp2) protobuf re2 recvmmsg/sendmmsg snmp systemd

Configuration:
`
addDOHLocal("0.0.0.0:443", {"/etc/dnsdist/cert.pem"}, {"/etc/dnsdist/key.pem"}, "/dns-query", {reusePort=true})
newServer({address="127.0.0.1:530", useClientSubnet=true, healthCheckMode="up"})
setECSSourcePrefixV4(32)
setECSSourcePrefixV6(128)
setECSOverride(true)

local dbr = dynBlockRulesGroup()
dbr:setQueryRate(30, 10, "Exceeded query rate", 60)
dbr:setRCodeRate(dnsdist.NXDOMAIN, 20, 10, "Exceeded NXD rate", 60)
dbr:setRCodeRate(dnsdist.SERVFAIL, 20, 10, "Exceeded ServFail rate", 60)
dbr:setQTypeRate(dnsdist.ANY, 5, 10, "Exceeded ANY rate", 60)
dbr:setResponseByteRate(10000, 10, "Exceeded resp BW rate", 60)
function maintenance()
dbr:apply()
end
`

Problem:
When I call the dbr: setQueryRate script, the following exception message appears in the service log, causing the dnsdist service to fail to start successfully. If I only initialize dynBlockRulesGroup() and do not call its internal functions, the entire service is fine.

Error message:
dnsdist[148436]: Fatal Lua error: [string "chunk"]:102: attempt to index global 'dnsdist' (a nil value) stack traceback: [string "chunk"]:102: in main chunk

[miodvallat]

Have you tried to replace

dbr:setRCodeRate(dnsdist.NXDOMAIN, 20, 10, "Exceeded NXD rate", 60)
dbr:setRCodeRate(dnsdist.SERVFAIL, 20, 10, "Exceeded ServFail rate", 60)
dbr:setQTypeRate(dnsdist.ANY, 5, 10, "Exceeded ANY rate", 60)

with

dbr:setRCodeRate(DNSRCode.NXDOMAIN, 20, 10, "Exceeded NXD rate", 60)
dbr:setRCodeRate(DNSRCode.SERVFAIL, 20, 10, "Exceeded ServFail rate", 60)
dbr:setQTypeRate(DNSQType.ANY, 5, 10, "Exceeded ANY rate", 60)

and does it fix your problem?

[chunyuliu106667777]

Oh, I understand, Thaks a lot！but why is the example in the document dnsdist.

[miodvallat]

Because human errors happen. Thanks for raising our attention, we'll fix this ASAP.

[rgacogne]

dnsdist. used to be a valid syntax before 1.4.0: https://www.dnsdist.org/upgrade_guide.html#x-to-1-4-0 Clearly we failed to update this part of the documentation, sorry about that.