From 527bded1b20b94a688d840123de3235a0087f5ba Mon Sep 17 00:00:00 2001
From: Kroese <kroese@users.noreply.github.com>
Date: Thu, 28 Dec 2023 20:25:04 +0100
Subject: [PATCH] feat: Detect default interface

* feat: Detect default interface
---
 src/check.sh   |  6 +++---
 src/network.sh | 11 +++++++++--
 src/print.sh   |  4 ++--
 src/reset.sh   |  3 ++-
 4 files changed, 16 insertions(+), 8 deletions(-)

diff --git a/src/check.sh b/src/check.sh
index f49f785..d61f998 100644
--- a/src/check.sh
+++ b/src/check.sh
@@ -1,12 +1,12 @@
 #!/usr/bin/env bash
 set -Eeuo pipefail
 
-: ${VM_NET_DEV:='eth0'}
-
 [ -f "/run/qemu.end" ] && echo "QEMU is shutting down.." && exit 1
 [ ! -f "/run/qemu.pid" ] && echo "QEMU is not running yet.." && exit 0
 
 file="/run/dsm.url"
+address="/run/qemu.ip"
+
 [ ! -f  "$file" ] && echo "DSM has not enabled networking yet.." && exit 1
 
 location=$(cat "$file")
@@ -19,7 +19,7 @@ if ! curl -m 20 -ILfSs "http://$location/" > /dev/null; then
     echo "Failed to reach DSM at port $port"
   else
     echo "Failed to reach DSM at http://$location"
-    ip=$(ip address show dev "$VM_NET_DEV" | grep inet | awk '/inet / { print $2 }' | cut -f1 -d/)
+    ip="$(cat "$address")"
   fi
 
   echo "You might need to whitelist IP $ip in the DSM firewall." && exit 1
diff --git a/src/network.sh b/src/network.sh
index e294d3b..5107975 100644
--- a/src/network.sh
+++ b/src/network.sh
@@ -6,8 +6,8 @@ set -Eeuo pipefail
 : ${DHCP:='N'}
 : ${MAC:='02:11:32:AA:BB:CC'}
 
+: ${VM_NET_DEV:=''}
 : ${VM_NET_TAP:='dsm'}
-: ${VM_NET_DEV:='eth0'}
 : ${VM_NET_MAC:="$MAC"}
 : ${VM_NET_HOST:='VirtualDSM'}
 
@@ -204,14 +204,21 @@ fi
 update-alternatives --set iptables /usr/sbin/iptables-legacy > /dev/null
 update-alternatives --set ip6tables /usr/sbin/ip6tables-legacy > /dev/null
 
+if [ -z "$VM_NET_DEV" ]; then
+  # Automaticly detect the default network interface
+  VM_NET_DEV=$(awk '$2 == 00000000 { print $1 }' /proc/net/route)
+  [ -z "$VM_NET_DEV" ] && VM_NET_DEV="eth0"
+fi
+
 if [ ! -d "/sys/class/net/$VM_NET_DEV" ]; then
-  error "Network interface $VM_NET_DEV does not exist inside the container!"
+  error "Network interface '$VM_NET_DEV' does not exist inside the container!"
   error "$ADD_ERR -e \"VM_NET_DEV=NAME\" to specify another interface name." && exit 27
 fi
 
 VM_NET_MAC="${VM_NET_MAC//-/:}"
 GATEWAY=$(ip r | grep default | awk '{print $3}')
 IP=$(ip address show dev "$VM_NET_DEV" | grep inet | awk '/inet / { print $2 }' | cut -f1 -d/)
+echo "$IP" > /run/qemu.ip
 
 if [[ "$DEBUG" == [Yy1]* ]]; then
   info "Container IP is $IP with gateway $GATEWAY" && echo
diff --git a/src/print.sh b/src/print.sh
index 463ba34..dbfa250 100644
--- a/src/print.sh
+++ b/src/print.sh
@@ -2,12 +2,12 @@
 set -Eeuo pipefail
 
 : ${DHCP:='N'}
-: ${VM_NET_DEV:='eth0'}
 
 info () { printf "%b%s%b" "\E[1;34m❯ \E[1;36m" "$1" "\E[0m\n" >&2; }
 error () { printf "%b%s%b" "\E[1;31m❯ " "ERROR: $1" "\E[0m\n" >&2; }
 
 file="/run/dsm.url"
+address="/run/qemu.ip"
 shutdown="/run/qemu.end"
 url="http://127.0.0.1:2210/read?command=10"
 
@@ -69,7 +69,7 @@ if [[ "$location" != "20.20"* ]]; then
 
 else
 
-  ip=$(ip address show dev "$VM_NET_DEV" | grep inet | awk '/inet / { print $2 }' | cut -f1 -d/)
+  ip="$(cat "$address")"
   port="${location##*:}"
 
   if [[ "$ip" == "172."* ]]; then
diff --git a/src/reset.sh b/src/reset.sh
index 6539058..53666ba 100644
--- a/src/reset.sh
+++ b/src/reset.sh
@@ -38,6 +38,7 @@ STORAGE="/storage"
 # Cleanup files
 
 rm -f /run/dsm.url
+rm -f /run/qemu.ip
 rm -f /run/qemu.log
 rm -f /run/qemu.pid
 rm -f /run/qemu.end
@@ -120,7 +121,7 @@ setCountry() {
   return 0
 }
 
-addPackage () {
+addPackage() {
   local pkg=$1
   local desc=$2