From 18bed41c6600ed556acf8d60fd0f04f78274de74 Mon Sep 17 00:00:00 2001
From: Lethja <150316953+Lethja@users.noreply.github.com>
Date: Wed, 10 Sep 2025 16:41:03 +1000
Subject: [PATCH] Mac Address (#123)

* Initial implementation of mac_address.sh

* Added manual MAC address entry.

* Fixed wrong variable in update_mac() function.

* Added clear commands before exiting.

* Spelling and grammar.

* Added some comments.

* Added shebang.

* Corrected terminal output of dialog commands.

* Allow startup dialogs to show on any console.

* Corrected valid MAC addresses being marked as invalid. Improved manual MAC address entry.

* Replaced hardcoded redirects to '/dev/tty2' with redirects to scripts stderr and swap where applicable

* Make MAC address discovery optional.

* Modified sed regex to improve finding and replacing ethaddr variable in update_uboot()

* Code cleanup.

* Check important commands exist before running the script.

* Generate locally administered, unicast addresses in a smarter way.

* Simplify script

* Code cleanup and minor experence changes

* Moved mac_address.sh from other_authors to repository root
---
 mac_address.sh | 114 +++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 114 insertions(+)
 create mode 100755 mac_address.sh

diff --git a/mac_address.sh b/mac_address.sh
new file mode 100755
index 0000000..b97601c
--- /dev/null
+++ b/mac_address.sh
@@ -0,0 +1,114 @@
+#!/usr/bin/env bash
+
+# Hardcoded for MiSTer
+iface="eth0"
+file="/media/fat/linux/u-boot.txt"
+
+update_uboot() {
+	if [ -n "$1" ]; then
+		if [ ! -e "$file" ]; then
+			echo "ethaddr=${1^^}" > "$file"
+		elif grep -q 'ethaddr=' "$file"; then
+			sed -i "s/\(ethaddr=\)[0-9A-Fa-f:]\+/\1${1^^}/" "$file"
+		else
+			echo "ethaddr=${1^^}" >> "$file"
+		fi
+	fi
+}
+
+valid() {
+	# Convert to a locally administistored unicast MAC address
+	local byte=$(( 16#${1:0:2} ))
+	byte=$(( (byte & ~1) | 2 ))
+	byte=$(printf "%02x" $byte)
+
+	local mac="${byte}${1:2}"
+	echo "${mac^^}"
+
+	if [[ "${1^^}" != "${mac^^}" ]]; then
+		return 0 # Input was not valid
+	fi
+
+	return 1 # Input was already valid
+}
+
+finished() {
+	if dialog --yesno "The MAC address has been changed to '$1'.\nYou will need to do a cold reboot for this to take effect.\n\nWould you like to cold reboot now?" 10 38 1>&2; then
+		dialog --infobox "Rebooting please wait..."  3 28 1>&2
+		reboot
+	else
+		dialog --clear
+	fi
+	exit 0
+}
+
+auto() {
+	local mac
+	mac=$(tr -dc '0-9a-f' </dev/urandom | head -c 12 | sed 's/../&:/g; s/:$//')
+	mac=$(valid "$mac")
+	update_uboot "$mac"
+	finished "$mac"
+}
+
+manual() {
+	local current input
+	current=$(cat "/sys/class/net/$iface/address")
+	current="${current^^}"
+	input=$current
+
+	while true; do
+		if ! input=$(dialog --inputbox "The MAC address for $iface is currently '$current'\n\nPlease enter a new MAC address..." 11 42 "$input" 3>&1 1>&2 2>&3); then
+			return
+		fi
+
+		# Format MAC address
+		input=${input^^}
+		input=${input//-/:}
+
+		# Validate user input is a MAC address
+		if [[ ! "$input" =~ ^([0-9A-F]{2}([-:])){5}([0-9A-Fa-f]{2})$ ]]; then
+			dialog --msgbox "Not a valid MAC address." 5 52 1>&2
+			continue
+		fi
+
+		local mac sta
+		mac=$(valid "$input")
+		sta=$?
+
+		if [ $sta -eq 0 ]; then
+			if dialog --yesno "'${input^^}' is not a suitable MAC address.\n\nWould you like to use '$mac' instead?" 7 64 1>&2; then
+				input="$mac"
+				break
+			fi
+		else
+			if [ "$input" = "$current" ]; then
+				dialog --msgbox "'$input' is the current MAC address." 5 52 1>&2
+				continue
+			fi
+			break
+		fi
+	done
+
+	update_uboot "$mac"
+	finished "$mac"
+}
+
+while true; do
+	local addr
+	local choice
+	addr=$(cat "/sys/class/net/$iface/address")
+	choice=$(dialog --menu "The current MAC address for $iface is '${addr^^}'.\n\nWhat do you want to do?" 12 44 3 \
+		A "Automatically generate MAC address" M "Manually set MAC address..." 3>&1 1>&2 2>&3)
+
+	case $choice in
+		A)
+			auto
+		;;
+		M)
+			manual
+		;;
+		*)
+			exit 0
+		;;
+	esac
+done