Loop of death when DNS queries a service that was registered wrong

[sielaq]

Overview of the Issue

Consul gets out of memory and dies or machine hangs
due to the loop of DNS resolve
when buggy service has been registered
and one DNS query was asked

Reproduction Steps

0. dnsmasq (or unbound) with config like:

server=/service/127.0.0.1#8600
server=/service.domain.com/127.0.0.1#8600

1. register service that points to itself via giving as Address
   not an IP, but hostname from domain that is gonna be resolve again via consul

{
  "Node": "foo",
  "Address": "foo.service.domain.com",
  "Service": {
    "Service": "foo",
    "Port": 8500
  }
}

2. query it

dig @localhost -p 8600 foo.service.domain.com

(of course the simple .domain.com can be .consul
or even no domain need at all, if you register services like foo.service
but having 1st entry in dnsmasq)

affected versions

all version of consul > 0.7

Operating system and Environment details

Reproducible on Linux (amd64)

Log Fragments

-log-level=TRACE is not giving anything special

Expected behavior

consul is not dying

[pierresouchay]

@sielaq Should be fixed with #4918

[sielaq]

@pierresouchay awesome, thx a lot!