dist/tools/ethos: add setup_network.sh script

dist/tools/ethos/README.md

@@ -13,3 +13,19 @@ To use, add
 
 to app Makefile, "make clean all flash", then run this tool as follows:
     # sudo ./ethos <tap-device> <serial>
+
+## setup_network.sh
+
+This script sets up a tap device, configures a prefix and starts a uhcpd server
+serving that prefix towards the tap device.
+The tap device will be owned by the calling user, or if called with sudo, with
+the user that uses sudo. That way, ethos can use it without being root / using
+sudo.
+
+E.g., use as follows:
+
+    $ sudo ./setup_network.sh riot0 2001:db8::0/64
+
+Keep that running, then in another shell start ethos:
+
+    $ ethos riot0 <serial>

dist/tools/ethos/setup_network.sh

@@ -0,0 +1,49 @@
+#!/bin/sh
+
+create_tap() {
+    ip tuntap add ${TAP} mode tap user ${_USER}
+    sysctl -w net.ipv6.conf.${TAP}.forwarding=1
+    sysctl -w net.ipv6.conf.${TAP}.accept_ra=0
+    ip link set ${TAP} up
+    ip a a fe80::1/64 dev ${TAP}
+    ip a a fd00:dead:beef::1/128 dev lo
+    ip route add ${PREFIX} via fe80::2 dev ${TAP}
+}
+
+remove_tap() {
+    ip tuntap del ${TAP} mode tap
+}
+
+cleanup() {
+    echo "Cleaning up..."
+    remove_tap
+    ip a d fd00:dead:beef::1/128 dev lo
+    trap "" INT QUIT TERM EXIT
+}
+
+start_uhcpd() {
+    ${UHCPD} ${TAP} ${PREFIX}
+}
+
+TAP=$1
+PREFIX=$2
+_USER=$3
+: ${UHCPD:="$(readlink -f $(dirname $0)"/../uhcpd/bin")/uhcpd"}
+
+[ -z "${TAP}" -o -z "${PREFIX}" ] && {
+    echo "usage: $0 <tap-device> <prefix> [<user>]"
+    exit 1
+}
+
+if [ -z "$_USER" ]; then
+    if [ -n "$SUDO_USER" ] ; then
+        _USER=$SUDO_USER
+    else
+        _USER=$USER
+    fi
+fi
+
+trap "cleanup" INT QUIT TERM EXIT
+
+
+create_tap && start_uhcpd