conf: Allow address remapped to host to be configured

Because the host and guest share the same IP address with passt/pasta, it's
not possible for the guest to directly address the host.  Therefore we
allow packets from the guest going to a special "NAT to host" address to be
redirected to the host, appearing there as though they have both source and
destination address of loopback.

Currently that special address is always the address of the default
gateway (or none).  That can be a problem if we want that gateway to be
addressable by the guest.  Therefore, allow the special "NAT to host"
address to be overridden on the command line with a new --map-host-loopback
option.

In order to exercise and test it, update the passt_in_ns and perf
tests to use this option and give different mapping addresses for the
two layers of the environment.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>

1 files changed, 73 insertions, 0 deletions

diff --git a/test/passt_in_ns/dhcp b/test/passt_in_ns/dhcp
new file mode 100644
index 0000000..0ceed7c
--- /dev/null
+++ b/test/passt_in_ns/dhcp
@@ -0,0 +1,73 @@
+# SPDX-License-Identifier: GPL-2.0-or-later
+#
+# PASST - Plug A Simple Socket Transport
+#  for qemu/UNIX domain socket mode
+#
+# PASTA - Pack A Subtle Tap Abstraction
+#  for network namespace/tap device mode
+#
+# test/passt/dhcp - Check DHCP and DHCPv6 functionality in passt mode
+#
+# Copyright (c) 2021 Red Hat GmbH
+# Author: Stefano Brivio <sbrivio@redhat.com>
+
+gtools	ip jq dhclient sed tr
+htools	ip jq sed tr head
+
+set	MAP_NS4 192.0.2.2
+set	MAP_NS6 2001:db8:9a55::2
+
+test	Interface name
+gout	IFNAME ip -j link show | jq -rM '.[] | select(.link_type == "ether").ifname'
+hout	HOST_IFNAME ip -j -4 route show|jq -rM '[.[] | select(.dst == "default").dev] | .[0]'
+hout	HOST_IFNAME6 ip -j -6 route show|jq -rM '[.[] | select(.dst == "default").dev] | .[0]'
+check	[ -n "__IFNAME__" ]
+
+test	DHCP: address
+guest	/sbin/dhclient -4 __IFNAME__
+gout	ADDR ip -j -4 addr show|jq -rM '.[] | select(.ifname == "__IFNAME__").addr_info[0].local'
+hout	HOST_ADDR ip -j -4 addr show|jq -rM '.[] | select(.ifname == "__HOST_IFNAME__").addr_info[0].local'
+check	[ "__ADDR__" = "__HOST_ADDR__" ]
+
+test	DHCP: route
+gout	GW ip -j -4 route show|jq -rM '.[] | select(.dst == "default").gateway'
+hout	HOST_GW ip -j -4 route show|jq -rM '[.[] | select(.dst == "default").gateway] | .[0]'
+check	[ "__GW__" = "__HOST_GW__" ]
+
+test	DHCP: MTU
+gout	MTU ip -j link show | jq -rM '.[] | select(.ifname == "__IFNAME__").mtu'
+check	[ __MTU__ = 65520 ]
+
+test	DHCP: DNS
+gout	DNS sed -n 's/^nameserver \([0-9]*\.\)\(.*\)/\1\2/p' /etc/resolv.conf | tr '\n' ',' | sed 's/,$//;s/$/\n/'
+hout	HOST_DNS sed -n 's/^nameserver \([0-9]*\.\)\(.*\)/\1\2/p' /etc/resolv.conf | head -n3 | tr '\n' ',' | sed 's/,$//;s/$/\n/'
+check	[ "__DNS__" = "__HOST_DNS__" ] || ( [ "__DNS__" = "__MAP_NS4__" ] && expr "__HOST_DNS__" : "127[.]" )
+
+# FQDNs should be terminated by dots, but the guest DHCP client might omit them:
+# strip them first
+test	DHCP: search list
+gout	SEARCH sed 's/\. / /g' /etc/resolv.conf | sed 's/\.$//g' | sed -n 's/^search \(.*\)/\1/p' | tr ' \n' ',' | sed 's/,$//;s/$/\n/'
+hout	HOST_SEARCH sed 's/\. / /g' /etc/resolv.conf | sed 's/\.$//g' | sed -n 's/^search \(.*\)/\1/p' | tr ' \n' ',' | sed 's/,$//;s/$/\n/'
+check	[ "__SEARCH__" = "__HOST_SEARCH__" ]
+
+test	DHCPv6: address
+guest	/sbin/dhclient -6 __IFNAME__
+gout	ADDR6 ip -j -6 addr show|jq -rM '[.[] | select(.ifname == "__IFNAME__").addr_info[] | select(.prefixlen == 128).local] | .[0]'
+hout	HOST_ADDR6 ip -j -6 addr show|jq -rM '[.[] | select(.ifname == "__HOST_IFNAME6__").addr_info[] | select(.scope == "global" and .deprecated != true).local] | .[0]'
+check	[ "__ADDR6__" = "__HOST_ADDR6__" ]
+
+test	DHCPv6: route
+gout	GW6 ip -j -6 route show|jq -rM '.[] | select(.dst == "default").gateway'
+hout	HOST_GW6 ip -j -6 route show|jq -rM '[.[] | select(.dst == "default").gateway] | .[0]'
+check	[ "__GW6__" = "__HOST_GW6__" ]
+
+# Strip interface specifier: interface names might differ between host and guest
+test	DHCPv6: DNS
+gout	DNS6 sed -n 's/^nameserver \([^:]*:\)\([^%]*\).*/\1\2/p' /etc/resolv.conf | tr '\n' ',' | sed 's/,$//;s/$/\n/'
+hout	HOST_DNS6 sed -n 's/^nameserver \([^:]*:\)\([^%]*\).*/\1\2/p' /etc/resolv.conf | tr '\n' ',' | sed 's/,$//;s/$/\n/'
+check	[ "__DNS6__" = "__HOST_DNS6__" ] || [ "__DNS6__" = "__MAP_NS6__" -a "__HOST_DNS6__" = "::1" ]
+
+test	DHCPv6: search list
+gout	SEARCH6 sed 's/\. / /g' /etc/resolv.conf | sed 's/\.$//g' | sed -n 's/^search \(.*\)/\1/p' | tr ' \n' ',' | sed 's/,$//;s/$/\n/'
+hout	HOST_SEARCH6 sed 's/\. / /g' /etc/resolv.conf | sed 's/\.$//g' | sed -n 's/^search \(.*\)/\1/p' | tr ' \n' ',' | sed 's/,$//;s/$/\n/'
+check	[ "__SEARCH6__" = "__HOST_SEARCH6__" ]