[GitHub] [incubator-ponymail] sbp commented on a change in pull request #517: Add DKIM style ID generation

[GitBox <gi...@apache.org>]

sbp commented on a change in pull request #517:
URL: https://github.com/apache/incubator-ponymail/pull/517#discussion_r483522248



##########
File path: tools/generators.py
##########
@@ -19,14 +19,137 @@
 This file contains the various ID generators for Pony Mail's archivers.
 """
 
+import base64
 import hashlib
 import email.utils
 import time
 import re
 
+# For optional nonce
+config = None
+
+# Headers from RFC 4871, the precursor to RFC 6376
+rfc4871_subset = {
+    b"from", b"sender", b"reply-to", b"subject", b"date",
+    b"message-id", b"to", b"cc", b"mime-version", b"content-type",
+    b"content-transfer-encoding", b"content-id",
+    b"content-description", b"resent-date", b"resent-from",
+    b"resent-sender", b"resent-to", b"resent-cc",
+    b"resent-message-id", b"in-reply-to", b"references", b"list-id",
+    b"list-help", b"list-unsubscribe", b"list-subscribe",
+    b"list-post", b"list-owner", b"list-archive", b"dkim-signature"
+}
+
+# Authenticity headers from RFC 8617
+rfc4871_and_rfc8617_subset = rfc4871_subset | {
+    b"arc-authentication-results", b"arc-message-signature",
+    b"arc-seal"
+}
+
+def rfc822_parse_dkim(suffix,
+        head_canon = False, body_canon = False,
+        head_subset = None, archive_list_id = None):
+    headers = []
+    keep = True
+    list_ids = set()
+
+    while suffix:
+        # Edge case: headers don't end LF (add LF)
+        line, suffix = (suffix.split(b"\n", 1) + [None])[:2]
+        if line in {b"\r", b"", None}:
+            break
+        lf = line.endswith(b"\r") and (suffix is not None)
+        end = b"\n" if lf else b"\r\n"
+        if line[0] in {0x09, 0x20}:
+            # Edge case: starts with a continuation (treat like From)
+            if headers and (keep is True):
+                headers[-1][1] += line + end
+        elif not line.startswith(b"From "):
+            # Edge case: header start contains no colon (use whole line)
+            # "A field-name MUST be contained on one line." (RFC 822 B.2)
+            k, v = (line.split(b":", 1) + [b""])[:2]
+            k_lower = k.lower()
+            if k_lower == "list-id":
+                list_ids.add(k_lower)

Review comment:
       I plan to add type annotations, unit tests, and property checks to guard against this sort of error. This specific `list-id` feature is going to be removed anyway as a consequence of the discussion thread.
   




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