Only set CRC32C and MD5 hashes if they are present in the X-Goog-Hash header.

Author: remmykilonzo

google/cloud/storage/blob.py

@@ -811,15 +811,16 @@ def _extract_headers_from_download(self, response):
  # 'X-Goog-Hash': 'crc32c=4gcgLQ==,md5=CS9tHYTtyFntzj7B9nkkJQ==',
  x_goog_hash = response.headers.get("X-Goog-Hash", "")
 
- digests = {}
- for encoded_digest in x_goog_hash.split(","):
- match = re.match(r"(crc32c|md5)=([\w\d/]+={0,3})", encoded_digest)
- if match:
- method, digest = match.groups()
- digests[method] = digest
-
- self.crc32c = digests.get("crc32c", self.crc32c)
- self.md5_hash = digests.get("md5", self.md5_hash)
+ if x_goog_hash:
+ digests = {}
+ for encoded_digest in x_goog_hash.split(","):
+ match = re.match(r"(crc32c|md5)=([\w\d/\+/]+={0,3})", encoded_digest)
+ if match:
+ method, digest = match.groups()
+ digests[method] = digest
+
+ self.crc32c = digests.get("crc32c", None)
+ self.md5_hash = digests.get("md5", None)
 
  def _do_download(
  self,