From 714461d1d0a76a55fd41f30f53559d3a9c46a820 Mon Sep 17 00:00:00 2001
From: Thomas Sileo <t@a4.io>
Date: Fri, 22 Jun 2018 23:46:38 +0200
Subject: [PATCH] Add caching to urlutils.check_url

---
 little_boxes/activitypub.py |  3 +--
 little_boxes/urlutils.py    | 10 ++++++++++
 2 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/little_boxes/activitypub.py b/little_boxes/activitypub.py
index 619c3d6..8f66b71 100644
--- a/little_boxes/activitypub.py
+++ b/little_boxes/activitypub.py
@@ -15,11 +15,10 @@ from .backend import Backend
 from .collection import parse_collection
 from .errors import BadActivityError
 from .errors import Error
-from .errors import RemoteActivityGoneError
 from .errors import NotFromOutboxError
+from .errors import RemoteActivityGoneError
 from .errors import UnexpectedActivityTypeError
 
-
 logger = logging.getLogger(__name__)
 
 UninitializedBackendError = Error("a backend must be initialized")
diff --git a/little_boxes/urlutils.py b/little_boxes/urlutils.py
index 3729e01..e962ed7 100644
--- a/little_boxes/urlutils.py
+++ b/little_boxes/urlutils.py
@@ -2,6 +2,7 @@ import ipaddress
 import logging
 import os
 import socket
+from typing import Dict
 from urllib.parse import urlparse
 
 from . import strtobool
@@ -10,6 +11,9 @@ from .errors import Error
 logger = logging.getLogger(__name__)
 
 
+_CACHE: Dict[str, bool] = {}
+
+
 class InvalidURLError(Error):
     pass
 
@@ -27,6 +31,9 @@ def is_url_valid(url: str) -> bool:
     if parsed.hostname in ["localhost"]:
         return False
 
+    if _CACHE.get(parsed.hostname, False):
+        return True
+
     try:
         ip_address = ipaddress.ip_address(parsed.hostname)
     except ValueError:
@@ -35,14 +42,17 @@ def is_url_valid(url: str) -> bool:
             logger.debug(f"dns lookup: {parsed.hostname} -> {ip_address}")
         except socket.gaierror:
             logger.exception(f"failed to lookup url {url}")
+            _CACHE[parsed.hostname] = False
             return False
 
     logger.debug(f"{ip_address}")
 
     if ipaddress.ip_address(ip_address).is_private:
         logger.info(f"rejecting private URL {url}")
+        _CACHE[parsed.hostname] = False
         return False
 
+    _CACHE[parsed.hostname] = True
     return True