Decode TLS-PSK identities as UTF-8 rather than ASCII

RFC4279 states these are UTF-8. Add unit test using non-ASCII chars
python · gpshead · Nov 27, 2023 · Mar 29, 2023 · Apr 3, 2023 · May 14, 2023
commit 18302e3c46a10757c82f34c7c7c4310addc98f83
@@ -4259,6 +4259,17 @@ def server_callback(identity):
         with self.assertRaisesRegex(ssl.SSLError, 'Cannot add PSK client callback'):
             server_context.set_psk_client_callback(client_callback)
 
+        # test with UTF-8 identities
+        identity_hint = '身份暗示'  # Translation: "Identity hint"
+        client_identity = '客户身份'  # Translation: "Customer identity"
+
+        client_context.set_psk_client_callback(client_callback)
+        server_context.set_psk_server_callback(server_callback, identity_hint)
+        server = ThreadedEchoServer(context=server_context)
+        with server:
+            with client_context.wrap_socket(socket.socket()) as s:
+                s.connect((HOST, server.port))
+
     @requires_tls_version('TLSv1_3')
     def test_psk_tls1_3(self):
         psk = bytes.fromhex('deadbeef')

@@ -4646,7 +4646,7 @@ static unsigned int psk_client_callback(SSL *s,
     }
 
     PyObject *hint_str = (hint != NULL) ?
-            PyUnicode_DecodeASCII(hint, strlen(hint), "strict") :
+            PyUnicode_DecodeUTF8(hint, strlen(hint), "strict") :
             Py_NewRef(Py_None);
     if (hint_str == NULL) {
         goto error;
@@ -4743,7 +4743,7 @@ static unsigned int psk_server_callback(SSL *s,
     }
 
     PyObject *identity_str = (identity[0] != '\0') ?
-            PyUnicode_DecodeASCII(identity, strlen(identity), "strict") :
+            PyUnicode_DecodeUTF8(identity, strlen(identity), "strict") :
             Py_NewRef(Py_None);
     if (identity_str == NULL) {
         goto error;