From 75c5eeba448b547cf4e0a7a2a21642f016195ef2 Mon Sep 17 00:00:00 2001
From: Michel Roegl-Brunner <michel.roegl-brunner@htl-braunau.at>
Date: Tue, 21 Jan 2025 13:47:20 +0100
Subject: [PATCH] Add input sanity checking

---
 misc/build.func | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/misc/build.func b/misc/build.func
index 7834135a1..03b4ecdfd 100644
--- a/misc/build.func
+++ b/misc/build.func
@@ -862,7 +862,12 @@ config_file(){
   fi
 
   if [[ ! -z "$MTU" ]]; then
-    echo -e "${DEFAULT}${BOLD}${DGN}Interface MTU Size: ${BGN}$MTU${CL}"
+    if [[ "$MTU" =~ ^-?[0-9]+$ ]]; then
+      echo -e "${DEFAULT}${BOLD}${DGN}Interface MTU Size: ${BGN}$MTU${CL}"
+    else
+      msg_error "MTU must be an integer"
+      exit
+    fi
   else
     MTU=""
     echo -e "${DEFAULT}${BOLD}${DGN}Interface MTU Size: ${BGN}Default${CL}"