add script to configure ip address

.gitignore

@@ -2,3 +2,4 @@ rsa_key.priv
 ecdsa_key.priv
 tinc.conf
 tinc-macaddr
+tinc-subnet

tinc-up

@@ -3,6 +3,7 @@ set -eu
 
 DIR=$(cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd)
 MAC_ADDRESS_FILE=${DIR}/tinc-macaddr
+TINC_SUBNET_FILE=${DIR}/tinc-subnet
 
 has() {
   command -v "$1" >/dev/null 2>&1
@@ -31,6 +32,40 @@ set_mac() {
   fi
 }
 
+mask2cidr() {
+  local netmask=$1
+  local nbits=0
+  IFS=.
+  for dec in "$netmask"; do
+    case $dec in
+      255) let nbits+=8;;
+      254) let nbits+=7;;
+      252) let nbits+=6;;
+      248) let nbits+=5;;
+      240) let nbits+=4;;
+      224) let nbits+=3;;
+      192) let nbits+=2;;
+      128) let nbits+=1;;
+      0);;
+      *) die "Error: $dec is not recognised"
+    esac
+  done
+  echo "$nbits"
+}
+
+set_ip() {
+  local interface=$1
+  local ip=$2
+  local netmask=$3
+  if has ifconfig; then
+    ifconfig "$interface" "$ip" netmask "$netmask"
+  elif has ip; then
+    ip addr add "$ip" dev "$interface"
+  else
+    die "no suitable program found to set ip address, need iproute2 or ifconfig"
+  fi
+}
+
 start_dhcp() {
   local interface=$1
   if has dhcpcd; then
@@ -54,4 +89,13 @@ fi
 read -r MAC_ADDRESS <"$MAC_ADDRESS_FILE"
 set_mac "$INTERFACE" "$MAC_ADDRESS"
 
-start_dhcp "$INTERFACE"
+if [ -e $TINC_SUBNET_FILE ]; then
+  read -a SUBNET <"$TINC_SUBNET_FILE"
+  IP=${SUBNET[0]}
+  NETMASK=${SUBNET[1]}
+  [ -z "$IP" ] && die "no ip set in '$TINC_SUBNET_FILE'"
+  [ -z "$NETMASK" ] && die "no netmask set in '$TINC_SUBNET_FILE'"
+  set_ip "$INTERFACE" "$IP" "$NETMASK"
+else
+  start_dhcp "$INTERFACE"
+fi