Instance allow list for receiving DMs

inbox.py

@@ -11,6 +11,7 @@ import os
 import datetime
 import time
 from linked_data_sig import verifyJsonSignature
+from utils import dmAllowedFromDomain
 from utils import isRecentPost
 from utils import getConfigParam
 from utils import hasUsersPath
@@ -2466,6 +2467,10 @@ def _inboxAfterInitial(recentPostsCache: {}, maxRecentPosts: int,
                             if not isFollowingActor(baseDir,
                                                     nickname, domain,
                                                     sendH):
+                                # DMs may always be allowed from some domains
+                                if not dmAllowedFromDomain(baseDir,
+                                                           nickname, domain,
+                                                           sendingActorDomain):
                                     # send back a bounce DM
                                     if postJsonObject.get('id') and \
                                        postJsonObject.get('object'):

utils.py

@@ -2203,3 +2203,22 @@ def loadTranslationsFromFile(baseDir: str, language: str) -> ({}, str):
         translationsFile = baseDir + '/translations/' + \
             systemLanguage + '.json'
     return loadJson(translationsFile), systemLanguage
+
+
+def dmAllowedFromDomain(baseDir: str,
+                        nickname: str, domain: str,
+                        sendingActorDomain: str):
+    """When a DM is received and the .followDMs flag file exists
+    Then optionally some domains can be specified as allowed,
+    regardless of individual follows.
+    i.e. Mostly you only want DMs from followers, but there are
+    a few particular instances that you trust
+    """
+    dmAllowedDomainsFilename = \
+        baseDir + '/accounts/' + \
+        nickname + '@' + domain + '/dmAllowedDomains.txt'
+    if not os.path.isfile(dmAllowedDomainsFilename):
+        return False
+    if sendingActorDomain + '\n' in open(dmAllowedDomainsFilename).read():
+        return True
+    return False