Add script to fetch public IP from multiple providers

This script attempts to retrieve the public IP address by querying multiple services in a randomized order. If successful, it writes the IP to /currentip; otherwise, it outputs an error message.

qbittorrent/rootfs/etc/helpers/public_ip.sh

@@ -0,0 +1,33 @@
+#!/bin/bash
+
+get_public_ip() {
+    local urls=(
+        "https://ifconfig.co/ip"
+        "https://api64.ipify.org"
+        "https://ipecho.net/plain"
+    )
+    local i j tmp url ip
+
+    # Fisher–Yates shuffle to randomize the order
+    for ((i=${#urls[@]}-1; i>0; i--)); do
+        j=$((RANDOM % (i + 1)))
+        tmp=${urls[i]}
+        urls[i]=${urls[j]}
+        urls[j]=$tmp
+    done
+
+    # Try each provider in random order until one works
+    for url in "${urls[@]}"; do
+        if ip=$(curl -fsS --max-time 10 "$url"); then
+            printf '%s\n' "$ip"
+            return 0
+        fi
+    done
+
+    return 1
+}
+
+# Write to /currentip, fail if none of the services respond
+if ! get_public_ip > /currentip; then
+    echo "Failed to get public IP from all providers" >&2
+fi