[CI] Use netns to simulate a client-server scenario

Signed-off-by: Andrea Barberio <insomniac@slackware.it>
Signed-off-by: Anatole Denis <anatole@unverle.fr>

.travis.yml

@@ -27,6 +27,7 @@ script: |
   set -x
   case $TEST_SUITE in
   unit)
+      ./.travis/setup-integ.sh
       ./.travis/tests.sh
       ;;
   linters)

.travis/setup-integ.sh

@@ -0,0 +1,107 @@
+#!/bin/bash
+set -ex
+
+if [[ $UID -ne 0 ]] # TODO: check for permissions instead (we can have CAP_NET_ADMIN without root)
+then
+    sudo "$0" "$@"
+    exit $?
+fi
+
+# Topology: with one or 3 netns
+#
+# * 3-netns, for relay operations
+#  --------------------------------
+# | server (cdhcp_srv  <---------) | Upper netns
+#  -----------------------------|--
+#                               | (veth pair)
+#  -----------------------------|---
+# | relay upper (cdhcp_relay_u <-) |
+# |                                | Relay netns
+# | relay lower (cdhcp_relay_d <-) |
+#  -----------------------------|--
+#                               | (veth pair)
+# ------------------------------|--
+# |  client (cdhcp_cli <---------) | Lower netns
+# ---------------------------------
+#
+# For 2-netns operation, remove the entire middle layer:
+#
+#  --------------------------------
+# | server (cdhcp_srv  <---------) | Upper netns
+#  -----------------------------|--
+#                               | (veth pair)
+# ------------------------------|--
+# |  client (cdhcp_cli <---------) | Lower netns
+# ---------------------------------
+#
+
+
+# Interface names are limited to 15 chars (IFNAMSIZ=16)
+if_server=cdhcp_srv
+if_relay_up=cdhcp_relay_u
+if_relay_down=cdhcp_relay_d
+if_client=cdhcp_cli
+
+netns_server=coredhcp-upper
+netns_relay=coredhcp-middle
+netns_client=coredhcp-lower
+
+netns_direct_server=coredhcp-direct-upper
+netns_direct_client=coredhcp-direct-lower
+
+ula_prefix=${ULA_PREFIX:-fd4f:6b37:542c:b643}
+
+all_ns=("$netns_server" "$netns_relay" "$netns_client" "$netns_direct_server" "$netns_direct_client")
+
+# Clean existing namespaces
+for netns in "${all_ns[@]}"; do
+    ip netns delete "$netns" || true
+done
+[[ $1 == teardown ]] && exit
+
+# create namespaces
+for netns in "${all_ns[@]}"; do
+    ip netns add "$netns"
+done
+
+# Create the links in one of the relevant netns, to ensure we don't pollute the main netns
+ip -n "$netns_client" link add "$if_client" type veth peer name "$if_relay_down"
+ip -n "$netns_client" link set "$if_relay_down" netns "$netns_relay"
+ip -n "$netns_server" link add "$if_server" type veth peer name "$if_relay_up"
+ip -n "$netns_server" link set "$if_relay_up" netns "$netns_relay"
+
+# configure networking on the veth interfaces
+ip -n "$netns_server" addr add "${ula_prefix}:a::1/80" dev "$if_server"
+ip -n "$netns_server" addr add "10.0.1.1/24" dev "$if_server"
+ip -n "$netns_server" link set "$if_server" up
+
+ip -n "$netns_client" addr add "${ula_prefix}:b::1/80" dev "$if_client"
+ip -n "$netns_client" addr add "10.0.2.1/24" dev "$if_client"
+ip -n "$netns_client" link set "$if_client" up
+
+ip -n "$netns_relay" addr add "${ula_prefix}:b::2/80" dev "$if_relay_down"
+ip -n "$netns_relay" addr add "${ula_prefix}:a::2/80" dev "$if_relay_up"
+ip -n "$netns_relay" addr add "10.0.2.2/24" dev "$if_relay_down"
+ip -n "$netns_relay" addr add "10.0.1.2/24" dev "$if_relay_up"
+ip -n "$netns_relay" link set "$if_relay_down" up
+ip -n "$netns_relay" link set "$if_relay_up" up
+
+# Now setup the direct-attach ns (with the same addresses as in the relay scenario)
+ip -n "$netns_direct_client" link add "$if_client" type veth peer name "$if_server"
+ip -n "$netns_direct_client" link set "$if_server" netns "$netns_direct_server"
+
+# Use the same addresses as the direct-attached version; with a larger subnet so they can link
+ip -n "$netns_direct_server" addr add "${ula_prefix}:a::1/64" dev "$if_server"
+ip -n "$netns_direct_server" addr add "10.0.1.1/16" dev "$if_server"
+ip -n "$netns_direct_server" link set "$if_server" up
+
+ip -n "$netns_direct_client" addr add "${ula_prefix}:b::1/64" dev "$if_client"
+ip -n "$netns_direct_client" addr add "10.0.2.1/16" dev "$if_client"
+ip -n "$netns_direct_client" link set "$if_client" up
+
+# show what we did
+set +x
+for netns in "${all_ns[@]}"; do
+    echo "# Addresses in $netns:"
+    ip -n "$netns" address list
+done