Raise BadTTL for non-decimal Unicode digits in dns.ttl.from_text()

dns/ttl.py

@@ -42,7 +42,7 @@ def from_text(text: str) -> int:
     :rtype: int
     """
 
-    if text.isdigit():
+    if text.isdecimal():
         total = int(text)
     elif len(text) == 0:
         raise BadTTL
@@ -51,7 +51,7 @@ def from_text(text: str) -> int:
         current = 0
         need_digit = True
         for c in text:
-            if c.isdigit():
+            if c.isdecimal():
                 current *= 10
                 current += int(c)
                 need_digit = False

doc/whatsnew.rst

@@ -19,6 +19,12 @@ TBD
   is the bit position, and dns.flags.from_text() / edns_from_text() parse that form
   back, so the conversions round-trip.  See issue #1264.
 
+* dns.ttl.from_text() now raises dns.ttl.BadTTL, rather than leaking a bare
+  ValueError, when the text contains a non-decimal Unicode "digit" (e.g. the
+  superscript ``\u00b2``).  Such characters are accepted by ``str.isdigit()`` but
+  rejected by ``int()``, so they previously escaped the parser's validation.  This
+  also makes zone files with such a TTL fail with a clean dns.exception.SyntaxError.
+
 2.8.0
 -----
 

tests/test_ttl.py

@@ -42,3 +42,12 @@ def test_ttl_technically_too_big(self):
     def test_empty(self):
         with self.assertRaises(dns.ttl.BadTTL):
             dns.ttl.from_text("")
+
+    def test_non_decimal_unicode_digits(self):
+        # str.isdigit() is True for Unicode "digit" characters (e.g. the
+        # superscript "\u00b2" or the Ethiopic "\u1369") that int() cannot
+        # convert, so these must be rejected as a BadTTL rather than leaking a
+        # bare ValueError.
+        for text in ("\u00b2", "1\u00b2", "\u00b2w", "1\u00b2s", "\u1369"):
+            with self.assertRaises(dns.ttl.BadTTL):
+                dns.ttl.from_text(text)