ci: configure servers to use IPv4 in respdiff

IPv6 isn't currently supported in our Docker image and using
it during resolution leads to a larger amount of timeouts.

ci/Dockerfile

@@ -61,10 +61,11 @@ RUN pip3 install flake8
 
 # Unbound for respdiff
 RUN apt-get install unbound unbound-anchor -y -qqq
-RUN printf "server:\n interface: 127.0.0.1@53535\n use-syslog: yes\nremote-control:\n control-enable: no\n" >> /etc/unbound/unbound.conf
+RUN printf "server:\n interface: 127.0.0.1@53535\n use-syslog: yes\n do-ip6: no\nremote-control:\n control-enable: no\n" >> /etc/unbound/unbound.conf
 
 # BIND for respdiff
 RUN apt-get install bind9 -y -qqq
+RUN printf '\nOPTIONS="-4 $OPTIONS"' >> /etc/default/bind9
 RUN printf 'options {\n directory "/var/cache/bind";\n listen-on port 53533 { 127.0.0.1; };\n listen-on-v6 port 53533 { ::1; };\n};\n' > /etc/bind/named.conf.options
 
 # PowerDNS Recursor for Deckard CI

ci/respdiff/kresd.config

 -- Refer to manual: https://knot-resolver.readthedocs.io/en/latest/daemon.html#configuration
 -- Listen on localhost and external interface
 net.listen('127.0.0.1', 5353)
-net.listen('::1', 5353)
 net.listen('127.0.0.1', 8853, { tls = true })
-net.listen('::1', 8853, { tls = true })
+net.ipv6=false
 
 -- Auto-maintain root TA
 trust_anchors.file = '.local/etc/knot-resolver/root.keys'

ci/respdiff/respdiff-tcp.conf

@@ -12,7 +12,7 @@ names = kresd, bind, unbound
 # each symbolic name in [servers] section refers to config section
 # containing IP address and port of particular server
 [kresd]
-ip = ::1
+ip = 127.0.0.1
 port = 5353
 transport = tcp
 

ci/respdiff/respdiff-tls.conf

@@ -12,7 +12,7 @@ names = kresd, bind, unbound
 # each symbolic name in [servers] section refers to config section
 # containing IP address and port of particular server
 [kresd]
-ip = ::1
+ip = 127.0.0.1
 port = 8853
 transport = tls
 

ci/respdiff/respdiff-udp.conf

@@ -12,7 +12,7 @@ names = kresd, bind, unbound
 # each symbolic name in [servers] section refers to config section
 # containing IP address and port of particular server
 [kresd]
-ip = ::1
+ip = 127.0.0.1
 port = 5353
 transport = udp