Add a method to validate bucket names

This change adds a method validate_bucket_name which can be used
to determine if the bucket names meet S3 standards or not.

It is currently unused, but in a future commit it will be called
from BucketController's PUT method.

swift3/middleware.py

@@ -59,6 +59,7 @@
 from simplejson import loads
 import email.utils
 import datetime
+import re
 
 from swift.common.utils import split_path
 from swift.common.utils import get_logger
@@ -292,6 +293,35 @@ def swift_acl_translate(acl, group='', user=''):
 
     return swift_acl[acl]
 
+def validate_bucket_name(name):
+    """
+    Validates the name of the bucket against S3 criteria, 
+    http://docs.amazonwebservices.com/AmazonS3/latest/BucketRestrictions.html
+    True if valid, False otherwise
+    """
+
+    if '_' in name or len(name) < 3 or len(name) > 63 or not name[-1].isalnum():
+       """
+       Bucket names should not contain underscores (_)
+       Bucket names must end with a lowercase letter or number
+       Bucket names should be between 3 and 63 characters long
+       """
+       return False
+    elif '.-' in name or '-.' in name or '..' in name or not name[0].isalnum():
+       """
+       Bucket names cannot contain dashes next to periods
+       Bucket names cannot contain two adjacent periods
+       Bucket names Must start with a lowercase letter or a number 
+       """
+       return False
+    elif re.match("^(([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\.){3}"\
+                  "([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])$", name):
+       """
+       Bucket names cannot be formatted as an IP Address
+       """
+       return False
+    else:
+       return True
 
 class ServiceController(WSGIContext):
     """