Support format for msgpack < 1.0 in token formatter

msgpack v1.0 changed its data format [1] and during a rolling upgrade, attempts
to unpack cached tokens with old data format with the new default raw=False
result in the following error:

  UnicodeDecodeError: 'utf-8' codec can't decode byte 0x87 in
  position 3: invalid start byte

This passes raw=True to support backward-compat with the old format
until we are guaranteed to have msgpack >= 1.0 in the N-1 release of
a rolling upgrade.

Closes-Bug: #1891244

[1]
https://github.com/msgpack/msgpack-python/blob/v1.0.0/README.md#major-breaking-changes-in-msgpack-10

Change-Id: I6c61df6c097fef698c659c79402c4381ec7f3586

1 files changed, 9 insertions, 1 deletions

diff --git a/keystone/token/token_formatters.py b/keystone/token/token_formatters.py
index f25a7a591..c251ac6d5 100644
--- a/keystone/token/token_formatters.py
+++ b/keystone/token/token_formatters.py
@@ -170,7 +170,15 @@ class TokenFormatter(object):
 
         """
         serialized_payload = self.unpack(token)
-        versioned_payload = msgpack.unpackb(serialized_payload)
+        # TODO(melwitt): msgpack changed their data format in version 1.0, so
+        # in order to support a rolling upgrade, we must pass raw=True to
+        # to support the old format. The try-except may be removed in the once
+        # the N-1 release no longer supports msgpack < 1.0.
+        try:
+            versioned_payload = msgpack.unpackb(serialized_payload)
+        except UnicodeDecodeError:
+            versioned_payload = msgpack.unpackb(serialized_payload, raw=True)
+
         version, payload = versioned_payload[0], versioned_payload[1:]
 
         for payload_class in _PAYLOAD_CLASSES: