Overhauled IP matching feature.

evennia/utils/utils.py

@@ -11,6 +11,7 @@ import importlib
 import importlib.machinery
 import importlib.util
 import inspect
+import ipaddress
 import math
 import os
 import random
@@ -2942,3 +2943,78 @@ def str2int(number):
             # invalid number-word, raise ValueError
             raise ValueError(f"String {original_input} cannot be converted to int.")
     return sum(sums)
+
+
+def match_ip(address, pattern) -> bool:
+    """
+    Check if an IP address matches a given pattern. The pattern can be a single IP address
+    such as 8.8.8.8 or a CIDR-formatted subnet like 10.0.0.0/8
+
+    IPv6 is supported to, with CIDR-subnets looking like 2001:db8::/48
+
+    Args:
+        address (str): The source address being checked.
+        pattern (str): The single IP address or subnet to check against.
+
+    Returns:
+        result (bool): Whether it was a match or not.
+    """
+    try:
+        # Convert the given IP address to an IPv4Address or IPv6Address object
+        ip_obj = ipaddress.ip_address(address)
+    except ValueError:
+        # Invalid IP address format
+        return False
+
+    try:
+        # Check if pattern is a single IP or a subnet
+        if "/" in pattern:
+            # It's (hopefully) a subnet in CIDR notation
+            network = ipaddress.ip_network(pattern, strict=False)
+            if ip_obj in network:
+                return True
+        else:
+            # It's a single IP address
+            if ip_obj == ipaddress.ip_address(pattern):
+                return True
+    except ValueError:
+        return False
+    return False
+
+
+def ip_from_request(request, exclude=None) -> str:
+    """
+    Retrieves the IP address from a web Request, while respecting X-Forwarded-For and
+    settings.UPSTREAM_IPS.
+
+    Args:
+        request (django Request or twisted.web.http.Request): The web request.
+        exclude: (list, optional): A list of IP addresses to exclude from the check. If left none,
+            then settings.UPSTREAM_IPS will be used.
+
+    Returns:
+        ip (str): The IP address the request originated from.
+    """
+    if exclude is None:
+        exclude = settings.UPSTREAM_IPS
+
+    if hasattr(request, "getClientIP"):
+        # It's a twisted request.
+        remote_addr = request.getClientIP()
+        forwarded = request.getHeader("x-forwarded-for")
+    else:
+        # it's a Django request.
+        remote_addr = request.META.get("REMOTE_ADDR")
+        forwarded = request.META.get("HTTP_X_FORWARDED_FOR")
+
+    addresses = [remote_addr]
+
+    if forwarded:
+        addresses.extend(x.strip() for x in forwarded.split(","))
+
+    for addr in reversed(addresses):
+        if all(not match_ip(addr, pattern) for pattern in exclude):
+            return addr
+
+    logger.log_warn("ip_from_request: No valid IP address found in request. Using remote_addr.")
+    return remote_addr