The return type of Rdata.to_wire() is Optional[bytes] not bytes. (#1129)

* The return type of Rdata.to_wire() is Optional[bytes] not bytes.
[#1128]

diff --git a/dns/dnssec.py b/dns/dnssec.py
index 9b1647753fe0c53779cef875be32f220b7952ced..77edb202a99e83db8564ea24a06cc4b71d930a05 100644 (file)
--- a/dns/dnssec.py
+++ b/dns/dnssec.py
@@ -118,6 +118,7 @@ def key_id(key: Union[DNSKEY, CDNSKEY]) -> int:
     """
 
     rdata = key.to_wire()
+    assert rdata is not None  # for mypy
     if key.algorithm == Algorithm.RSAMD5:
         return (rdata[-3] << 8) + rdata[-2]
     else:
@@ -245,9 +246,10 @@ def make_ds(
     if isinstance(name, str):
         name = dns.name.from_text(name, origin)
     wire = name.canonicalize().to_wire()
-    assert wire is not None
+    kwire = key.to_wire(origin=origin)
+    assert wire is not None and kwire is not None  # for mypy
     dshash.update(wire)
-    dshash.update(key.to_wire(origin=origin))
+    dshash.update(kwire)
     digest = dshash.digest()
 
     dsrdata = struct.pack("!HBB", key_id(key), key.algorithm, algorithm) + digest
@@ -634,7 +636,9 @@ def _make_rrsig_signature_data(
     rrname, rdataset = _get_rrname_rdataset(rrset)
 
     data = b""
-    data += rrsig.to_wire(origin=signer)[:18]
+    wire = rrsig.to_wire(origin=signer)
+    assert wire is not None  # for mypy
+    data += wire[:18]
     data += rrsig.signer.to_digestable(signer)
 
     # Derelativize the name before considering labels.

diff --git a/dns/rdata.py b/dns/rdata.py
index 5f9d47134ce6906ccf2b690447c61c9c9dcd81aa..8099c26aab9029b454a8709575d6f1fd7aba108d 100644 (file)
--- a/dns/rdata.py
+++ b/dns/rdata.py
@@ -214,7 +214,7 @@ class Rdata:
         compress: Optional[dns.name.CompressType] = None,
         origin: Optional[dns.name.Name] = None,
         canonicalize: bool = False,
-    ) -> bytes:
+    ) -> None:
         raise NotImplementedError  # pragma: no cover
 
     def to_wire(
@@ -223,14 +223,19 @@ class Rdata:
         compress: Optional[dns.name.CompressType] = None,
         origin: Optional[dns.name.Name] = None,
         canonicalize: bool = False,
-    ) -> bytes:
+    ) -> Optional[bytes]:
         """Convert an rdata to wire format.
 
-        Returns a ``bytes`` or ``None``.
+        Returns a ``bytes`` if no output file was specified, or ``None`` otherwise.
         """
 
         if file:
-            return self._to_wire(file, compress, origin, canonicalize)
+            # We call _to_wire() and then return None explicitly instead of
+            # of just returning the None from _to_wire() as mypy's func-returns-value
+            # unhelpfully errors out with "error: "_to_wire" of "Rdata" does not return
+            # a value (it only ever returns None)"
+            self._to_wire(file, compress, origin, canonicalize)
+            return None
         else:
             f = io.BytesIO()
             self._to_wire(f, compress, origin, canonicalize)
@@ -253,8 +258,9 @@ class Rdata:
 
         Returns a ``bytes``.
         """
-
-        return self.to_wire(origin=origin, canonicalize=True)
+        wire = self.to_wire(origin=origin, canonicalize=True)
+        assert wire is not None  # for mypy
+        return wire
 
     def __repr__(self):
         covers = self.covers()