Refactor source IP resolution logic

netbox/utilities/request.py

@@ -0,0 +1,27 @@
+import ipaddress
+
+__all__ = (
+    'get_client_ip',
+)
+
+
+def get_client_ip(request, additional_headers=()):
+    """
+    Return the client (source) IP address of the given request.
+    """
+    HTTP_HEADERS = (
+        'HTTP_X_REAL_IP',
+        'HTTP_X_FORWARDED_FOR',
+        'REMOTE_ADDR',
+        *additional_headers
+    )
+    for header in HTTP_HEADERS:
+        if header in request.META:
+            client_ip = request.META[header].split(',')[0]
+            try:
+                return ipaddress.ip_address(client_ip)
+            except ValueError:
+                raise ValueError(f"Invalid IP address set for {header}: {client_ip}")
+
+    # Could not determine the client IP address from request headers
+    return None