Adding Swift Temporary URL support

Temporary URLs allow a user to sign an object URL with a shared
secret to so that the object can be downloaded without auth for
a specified amount of time.

http://docs.openstack.org/trunk/config-reference/content/object-storage-tempurl.html

Change-Id: Ife0b6c98c975e074d4dad0a31145573b784747c5

1 files changed, 49 insertions, 0 deletions

diff --git a/swiftclient/utils.py b/swiftclient/utils.py
index 058181d..0f442b3 100644
--- a/swiftclient/utils.py
+++ b/swiftclient/utils.py
@@ -13,6 +13,10 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 """Miscellaneous utility functions for use with Swift."""
+import hashlib
+import hmac
+import logging
+import time
 
 import six
 
@@ -59,6 +63,51 @@ def prt_bytes(bytes, human_flag):
     return(bytes)
 
 
+def generate_temp_url(path, seconds, key, method):
+    """ Generates a temporary URL that gives unauthenticated access to the
+    Swift object.
+
+    :param path: The full path to the Swift object. Example:
+    /v1/AUTH_account/c/o.
+    :param seconds: The amount of time in seconds the temporary URL will
+    be valid for.
+    :param key: The secret temporary URL key set on the Swift cluster.
+    To set a key, run 'swift post -m
+    "Temp-URL-Key:b3968d0207b54ece87cccc06515a89d4"'
+    :param method: A HTTP method, typically either GET or PUT, to allow for
+    this temporary URL.
+    :raises: ValueError if seconds is not a positive integer
+    :raises: TypeError if seconds is not an integer
+    :return: the path portion of a temporary URL
+    """
+    if seconds < 0:
+        raise ValueError('seconds must be a positive integer')
+    try:
+        expiration = int(time.time() + seconds)
+    except TypeError:
+        raise TypeError('seconds must be an integer')
+
+    standard_methods = ['GET', 'PUT', 'HEAD', 'POST', 'DELETE']
+    if method.upper() not in standard_methods:
+        logger = logging.getLogger("swiftclient")
+        logger.warning('Non default HTTP method %s for tempurl specified, '
+                       'possibly an error', method.upper())
+
+    hmac_body = '\n'.join([method.upper(), str(expiration), path])
+
+    # Encode to UTF-8 for py3 compatibility
+    sig = hmac.new(key.encode(),
+                   hmac_body.encode(),
+                   hashlib.sha1).hexdigest()
+
+    return ('{path}?temp_url_sig='
+            '{sig}&temp_url_expires={exp}'.format(
+                path=path,
+                sig=sig,
+                exp=expiration)
+            )
+
+
 class LengthWrapper(object):
 
     def __init__(self, readable, length):