From b1b5abc44248257f89d0c2b145a968cfdf356dc9 Mon Sep 17 00:00:00 2001
From: Jino Jose <jinojose@Jinos-MacBook-Pro.local>
Date: Tue, 30 Jun 2026 16:08:49 +0530
Subject: [PATCH] Fix first boot static IP netmask handling

---
 autoinstall/firstboot-setup.sh | 46 ++++++++++++++++++++++++++++++----
 1 file changed, 41 insertions(+), 5 deletions(-)

diff --git a/autoinstall/firstboot-setup.sh b/autoinstall/firstboot-setup.sh
index 33c6a53..9f93518 100644
--- a/autoinstall/firstboot-setup.sh
+++ b/autoinstall/firstboot-setup.sh
@@ -20,6 +20,30 @@ detect_iface() {
 IFACE="$(detect_iface)"
 IFACE="${IFACE:-$(ip -o link show | awk -F': ' '$2 !~ /lo|docker|br-|veth/ {print $2; exit}')}"
 
+netmask_to_prefix() {
+  case "$1" in
+    32|31|30|29|28|27|26|25|24|23|22|21|20|19|18|17|16|15|14|13|12|11|10|9|8|7|6|5|4|3|2|1) echo "$1" ;;
+    255.255.255.255) echo 32 ;;
+    255.255.255.254) echo 31 ;;
+    255.255.255.252) echo 30 ;;
+    255.255.255.248) echo 29 ;;
+    255.255.255.240) echo 28 ;;
+    255.255.255.224) echo 27 ;;
+    255.255.255.192) echo 26 ;;
+    255.255.255.128) echo 25 ;;
+    255.255.255.0)   echo 24 ;;
+    255.255.254.0)   echo 23 ;;
+    255.255.252.0)   echo 22 ;;
+    255.255.248.0)   echo 21 ;;
+    255.255.240.0)   echo 20 ;;
+    255.255.224.0)   echo 19 ;;
+    255.255.192.0)   echo 18 ;;
+    255.255.128.0)   echo 17 ;;
+    255.255.0.0)     echo 16 ;;
+    *) return 1 ;;
+  esac
+}
+
 # ── Colors / terminal setup ────────────────────────────────
 export NEWT_COLORS='
 root=,black
@@ -66,9 +90,16 @@ if [ "$NET_MODE" = "Static" ]; then
     $H $W "" 3>&1 1>&2 2>&3)
 
   NETMASK=$(whiptail --title "$TITLE" \
-    --inputbox "\nEnter subnet mask (CIDR prefix):\n(Example: 24  means 255.255.255.0)" \
+    --inputbox "\nEnter subnet mask / CIDR prefix:\n(Examples: 24 or 255.255.255.0)" \
     $H $W "24" 3>&1 1>&2 2>&3)
 
+  PREFIX="$(netmask_to_prefix "$NETMASK")" || {
+    whiptail --title "$TITLE" \
+      --msgbox "\nInvalid subnet mask or CIDR prefix:\n  ${NETMASK}\n\nUse a CIDR prefix such as 24, or a mask such as 255.255.255.0." \
+      $H $W
+    exit 1
+  }
+
   GATEWAY=$(whiptail --title "$TITLE" \
     --inputbox "\nEnter default gateway:\n(Example: 192.168.1.1)" \
     $H $W "" 3>&1 1>&2 2>&3)
@@ -85,7 +116,7 @@ network:
     ${IFACE}:
       dhcp4: false
       addresses:
-        - ${IP_ADDR}/${NETMASK}
+        - ${IP_ADDR}/${PREFIX}
       routes:
         - to: default
           via: ${GATEWAY}
@@ -93,17 +124,22 @@ network:
         addresses: [${DNS}]
 EOF
 
-  netplan apply 2>/dev/null || true
+  if ! netplan apply; then
+    whiptail --title "$TITLE" \
+      --msgbox "\nFailed to apply network settings.\n\nIP:      ${IP_ADDR}/${PREFIX}\nGateway: ${GATEWAY}\nDNS:     ${DNS}\n\nPlease verify the address, gateway, and subnet." \
+      $H $W
+    exit 1
+  fi
   sleep 3
 
   # Verify connectivity
   if ! ping -c 2 -W 3 8.8.8.8 &>/dev/null; then
     whiptail --title "$TITLE" \
-      --msgbox "\nWARNING: Cannot reach internet with these settings.\n\nIP:      ${IP_ADDR}/${NETMASK}\nGateway: ${GATEWAY}\nDNS:     ${DNS}\n\nPlease verify your network settings. The install requires internet access." \
+      --msgbox "\nWARNING: Cannot reach internet with these settings.\n\nIP:      ${IP_ADDR}/${PREFIX}\nGateway: ${GATEWAY}\nDNS:     ${DNS}\n\nPlease verify your network settings. The install requires internet access." \
       $H $W
   else
     whiptail --title "$TITLE" \
-      --msgbox "\nNetwork configured successfully!\n\nIP:      ${IP_ADDR}/${NETMASK}\nGateway: ${GATEWAY}\nDNS:     ${DNS}" \
+      --msgbox "\nNetwork configured successfully!\n\nIP:      ${IP_ADDR}/${PREFIX}\nGateway: ${GATEWAY}\nDNS:     ${DNS}" \
       $H $W
   fi