Add parse_url to _utils.

The patch adds parse_url to _utils as an attempt to find a common url
format that satisfies most drivers needs. The code isn't definitive but
instead the beginning for further discussions. Current code parses
transport urls like this:

qpid://test/test
{'exchange': 'test',
 'hosts': [{'host': 'test', 'password': '', 'username': ''}],
 'parameters': {},
 'transport': 'qpid'}

qpid://test:port/test
{'exchange': 'test',
 'hosts': [{'host': 'test:port', 'password': '', 'username': ''}],
 'parameters': {},
 'transport': 'qpid'}

qpid://username:password@test:port/test
{'exchange': 'test',
 'hosts': [{'host': 'test:port',
            'password': 'password',
            'username': 'username'}],
 'parameters': {},
 'transport': 'qpid'}

qpid://username:password@test:port
{'exchange': None,
 'hosts': [{'host': 'test:port',
            'password': 'password',
            'username': 'username'}],
 'parameters': {},
 'transport': 'qpid'}

qpid://username:password@test:port,test2:port2/test
{'exchange': 'test',
 'hosts': [{'host': 'test:port',
            'password': 'password',
            'username': 'username'},
           {'host': 'test2:port2',
            'password': 'password',
            'username': 'username'}],
 'parameters': {},
 'transport': 'qpid'}

qpid://username:password@test:port,:@test2:port2/test
{'exchange': 'test',
 'hosts': [{'host': 'test:port',
            'password': 'password',
            'username': 'username'},
           {'host': 'test2:port2', 'password': '', 'username': ''}],
 'parameters': {},
 'transport': 'qpid'}

qpid://username:password@test:port,:@test2:port2/test?option=value
{'exchange': 'test',
 'hosts': [{'host': 'test:port',
            'password': 'password',
            'username': 'username'},
           {'host': 'test2:port2', 'password': '', 'username': ''}],
 'parameters': {'option': ['value']},
 'transport': 'qpid'}

openstack/common/messaging/_utils.py

@@ -34,6 +34,103 @@ def version_is_compatible(imp_version, version):
     return True
 
 
+def parse_url(url, default_exchange=None):
+    """Parse an url.
+
+    Assimung a URL takes the form of:
+
+        transport://username:password@host1:port[,hostN:portN]/exchange[?option=value]
+
+    then parse the URL and return a dictionary with the following structure:
+
+        {
+            'exchange': 'exchange'
+            'transport': 'transport',
+            'hosts': [{'username': 'username',
+                       'password': 'password'
+                       'host': 'host1:port1'},
+                       ...],
+            'parameters': {'option': 'value'}
+        }
+
+    Netloc is parsed following the sequence bellow:
+
+    * It is first splitted by ',' in order to support multiple hosts
+    * The last parsed username and password will be propagated to the rest
+    of hotsts specified:
+
+      user:passwd@host1:port1,host2:port2
+
+      [
+       {"username": "user", "password": "passwd", "host": "host1:port1"},
+       {"username": "user", "password": "passwd", "host": "host2:port2"}
+      ]
+
+    * In order to avoid the above propagation, it is possible to alter the order
+    in which the hosts are specified or specify a set of fake credentials using
+    ",:@host2:port2"
+
+
+      user:passwd@host1:port1,:@host2:port2
+
+      [
+       {"username": "user", "password": "passwd", "host": "host1:port1"},
+       {"username": "", "password": "", "host": "host2:port2"}
+      ]
+
+    :param url: The URL to parse
+    :type url: str
+    :param default_exchange: what to return if no exchange found in URL
+    :type default_exchange: str
+    :returns: A dictionary with the parsed data
+    """
+
+    # NOTE(flaper87): Not PY3K compliant
+    if not isinstance(url, basestring):
+        raise TypeError(_("Wrong URL type"))
+
+    url = urlparse.urlparse(url)
+
+    parsed = dict(transport=url.scheme)
+
+    # NOTE(flaper87): Set the exchange.
+    # if it is / or None then use the
+    # default one.
+    exchange = default_exchange
+    if url.path and url.path != "/":
+        exchange = url.path[1:].split("/")[0]
+    parsed["exchange"] = exchange
+
+    # NOTE(flaper87): Parse netloc.
+    hosts = []
+    username = password = ''
+    for host in url.netloc.split(","):
+        if not host:
+            continue
+
+        if "@" in host:
+            creds, host = host.split("@")
+            username, password = creds.split(":")
+
+        hosts.append({
+            "host": host,
+            "username": username,
+            "password": password,
+        })
+
+    parsed["hosts"] = hosts
+
+    parameters = {}
+    if url.query:
+        # NOTE(flaper87): This returns a dict with
+        # key -> [value], those values need to be
+        # normalized
+        parameters = urlparse.parse_qs(url.query)
+    parsed['parameters'] = parameters
+
+    return parsed
+
+
 def exchange_from_url(self, url, default_exchange=None):
     """Parse an exchange name from a URL.