gh-118658: Return consistent types from `get_un/verified_chain` in `SSLObject` and `SSLSocket` (#118669)

Co-authored-by: Gregory P. Smith [Google LLC] <greg@krypto.org>

Lib/ssl.py

@@ -1164,11 +1164,21 @@ def getpeercert(self, binary_form=False):
 
     @_sslcopydoc
     def get_verified_chain(self):
-        return self._sslobj.get_verified_chain()
+        chain = self._sslobj.get_verified_chain()
+
+        if chain is None:
+            return []
+
+        return [cert.public_bytes(_ssl.ENCODING_DER) for cert in chain]
 
     @_sslcopydoc
     def get_unverified_chain(self):
-        return self._sslobj.get_unverified_chain()
+        chain = self._sslobj.get_unverified_chain()
+
+        if chain is None:
+            return []
+
+        return [cert.public_bytes(_ssl.ENCODING_DER) for cert in chain]
 
     @_sslcopydoc
     def selected_npn_protocol(self):

Lib/test/certdata/cert3.pem

@@ -0,0 +1,34 @@
+-----BEGIN CERTIFICATE-----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+Y2EvcmV2b2NhdGlvbi5jcmwwDQYJKoZIhvcNAQELBQADggGBAMo0usXQzycxMtYN
+JzC42xfftzmnu7E7hsQx/fur22MazJCruU6rNEkMXow+cKOnay+nmiV7AVoYlkh2
++DZ4dPq8fWh/5cqmnXvccr2jJVEXaOjp1wKGLH0WfLXcRLIK4/fJM6NRNoO81HDN
+hJGfBrot0gUKZcPZVQmouAlpu5OGwrfCkHR8v/BdvA5jE4zr+g/x+uUScE0M64wu
+okJCAAQP/PkfQZxjePBmk7KPLuiTHFDLLX+2uldvUmLXOQsJgqumU03MBT4Z8NTA
+zqmtEM65ceSP8lo8Zbrcy+AEkCulFaZ92tyjtbe8oN4wTmTLFw06oFLSZzuiOgDV
+OaphdVKf/pvA6KBpr6izox0KQFIE5z3AAJZfKzMGDDD20xhy7jjQZNMAhjfsT+k4
+SeYB/6KafNxq08uoulj7w4Z4R/EGpkXnU96ZHYHmvGN0RnxwI1cpYHCazG8AjsK/
+anN9brBi5twTGrn+D8LRBqF5Yn+2MKkD0EdXJdtIENHP+32sPQ==
+-----END CERTIFICATE-----

Lib/test/test_ssl.py

@@ -103,6 +103,7 @@ def data_file(*name):
 
 # Two keys and certs signed by the same CA (for SNI tests)
 SIGNED_CERTFILE = data_file("keycert3.pem")
+SINGED_CERTFILE_ONLY = data_file("cert3.pem")
 SIGNED_CERTFILE_HOSTNAME = 'localhost'
 
 SIGNED_CERTFILE_INFO = {
@@ -4720,6 +4721,40 @@ def test_internal_chain_client(self):
                     ssl.PEM_cert_to_DER_cert(pem), der
                 )
 
+    def test_certificate_chain(self):
+        client_context, server_context, hostname = testing_context(
+            server_chain=False
+        )
+        server = ThreadedEchoServer(context=server_context, chatty=False)
+
+        with open(SIGNING_CA) as f:
+            expected_ca_cert = ssl.PEM_cert_to_DER_cert(f.read())
+
+        with open(SINGED_CERTFILE_ONLY) as f:
+            expected_ee_cert = ssl.PEM_cert_to_DER_cert(f.read())
+
+        with server:
+            with client_context.wrap_socket(
+                socket.socket(),
+                server_hostname=hostname
+            ) as s:
+                s.connect((HOST, server.port))
+                vc = s.get_verified_chain()
+                self.assertEqual(len(vc), 2)
+
+                ee, ca = vc
+                self.assertIsInstance(ee, bytes)
+                self.assertIsInstance(ca, bytes)
+                self.assertEqual(expected_ca_cert, ca)
+                self.assertEqual(expected_ee_cert, ee)
+
+                uvc = s.get_unverified_chain()
+                self.assertEqual(len(uvc), 1)
+                self.assertIsInstance(uvc[0], bytes)
+
+                self.assertEqual(ee, uvc[0])
+                self.assertNotEqual(ee, ca)
+
     def test_internal_chain_server(self):
         client_context, server_context, hostname = testing_context()
         client_context.load_cert_chain(SIGNED_CERTFILE)

Misc/NEWS.d/next/Library/2023-09-19-17-56-24.gh-issue-109109.WJvvX2.rst

@@ -0,0 +1,5 @@
+You can now get the raw TLS certificate chains from TLS connections via
+:meth:`ssl.SSLSocket.get_verified_chain` and
+:meth:`ssl.SSLSocket.get_unverified_chain` methods.
+
+Contributed by Mateusz Nowak.