From 78d641b591ec056c21a44c59aa0ebbbb2feed397 Mon Sep 17 00:00:00 2001
From: "Ulf D." <1coderookie@quantentunnel.de>
Date: Sun, 15 Jun 2025 13:42:38 +0200
Subject: [PATCH] Add files via upload

---
 latest/RESOURCES/OPTIONS/app_dns/app_dns.sh | 51 +++++++++++++++++++++
 1 file changed, 51 insertions(+)
 create mode 100644 latest/RESOURCES/OPTIONS/app_dns/app_dns.sh

diff --git a/latest/RESOURCES/OPTIONS/app_dns/app_dns.sh b/latest/RESOURCES/OPTIONS/app_dns/app_dns.sh
new file mode 100644
index 0000000..a2bcc2b
--- /dev/null
+++ b/latest/RESOURCES/OPTIONS/app_dns/app_dns.sh
@@ -0,0 +1,51 @@
+#!/bin/bash
+
+# check the parameters
+if [ $# != 2 ]; then
+  echo "usage : $0 <project_root> <dns_replacement>"
+  exit 1
+fi
+
+project_root="$1"
+dns_replacement="$2"
+
+# check the required tools
+check_tools "printf dd grep cut xargs"
+
+# check the project root folder
+if [ ! -d "$project_root" ]; then
+  echo -e "${RED}ERROR: Cannot find the folder '$project_root' ${NC}"
+  exit 2
+fi
+
+# check the target file
+def_target="$ROOTFS_DIR/app/app"
+if [ ! -f "$def_target" ]; then
+  echo -e "${RED}ERROR: Cannot find the target file '$def_target' ${NC}"
+  exit 3
+fi
+
+# patch the app
+old_dns=$(echo -n "$dns_replacement" | cut -d "|" -f 1)
+new_dns=$(echo -n "$dns_replacement" | cut -d "|" -f 2)
+if [ -z "$old_dns" ] || [ -z "$new_dns" ]; then
+  echo -e "${RED}ERROR: The requested DNS replacement is not valid: '$dns_replacement' ${NC}"
+  exit 4
+fi
+dns_url="udp://$old_dns:53"
+# find all records with offsets that match the requested old DNS
+results=$(grep --binary-files=text -b -o "$dns_url" "$def_target" | xargs echo -n)
+if [ -z "$results" ]; then
+  echo -e "${RED}ERROR: The 'app' might be already patched. Cannot find the expected DNS '$dns_url' ${NC}"
+  echo -e "${YELLOW}INFO: Will not patch the 'app' file...${NC}"
+  exit 0
+fi
+# replace all found old DNS with the new one
+for result in $results; do
+  offset=$(echo -n "$result" | awk -F: '{print $1}')
+  printf "udp://%s:53\x00" "$new_dns" | dd of="$def_target" bs=1 seek="$offset" conv=notrunc &>>/dev/null
+done
+
+echo -e "${GREEN}SUCCESS: The 'app' has been patched with the new DNS '$new_dns' ${NC}"
+
+exit 0