Fleshed out krb plugin and added example of scripting against Python API

doc/examples/python-api.py

@@ -0,0 +1,30 @@
+#!/usr/bin/env python
+
+from ipalib import api
+
+# 1. Initialize ipalib
+#
+# Run ./python-api.py --help to see the global options.  Some useful options:
+#
+#   -v  Produce more verbose output
+#   -d  Produce full debugging output
+#   -e in_server=True  Force running in server mode
+#   -e xmlrpc_uri=https://foo.com/ipa/xml  # Connect to a specific server
+
+api.bootstrap_with_global_options(context='example')
+api.finalize()
+
+# You will need to create a connection.  If you're in_server, call
+# Backend.ldap.connect(), otherwise Backend.xmlclient.connect().
+
+if api.env.in_server:
+    api.Backend.ldap2.connect(
+        ccache=api.Backend.krb.default_ccname()
+     )
+else:
+    api.Backend.xmlclient.connect()
+
+
+# Now that you're connected, you can make calls to api.Command.whatever():
+print 'The admin user:'
+print api.Command.user_show(u'admin')

ipalib/plugins/kerberos.py

@@ -23,12 +23,102 @@ Backend plugin for Kerberos.
 This wraps the python-kerberos and python-krbV bindings.
 """
 
+import sys
 from ipalib import api
 from ipalib.backend import Backend
+import krbV
+
+
+# FIXME: Is it safe to assume the Kerberos library is using UTF-8 for the
+# principal and realm?  If not, how do we query the Kerberos library to find
+# the encoding it's using?
+ENCODING = 'UTF-8'
+FS_ENCODING = (sys.getfilesystemencoding() or sys.getdefaultencoding())
+
 
 class krb(Backend):
     """
     Kerberos backend plugin.
+
+    This wraps the `krbV` bindings (and will eventually wrap the `kerberos`
+    bindings also).  Importantly, this plugin does correct Unicode
+    encoding/decoding of values going-to/coming-from the bindings.
     """
 
+    def __default_ccache(self):
+        """
+        Return the ``krbV.CCache`` for the default credential cache.
+        """
+        return krbV.default_context().default_ccache()
+
+    def __default_principal(self):
+        """
+        Return the ``krb5.Principal`` for the default credential cache.
+        """
+        return self.__default_ccache().principal()
+
+    def __get_ccache(self, ccname):
+        """
+        Return the ``krbV.CCache`` for the ``ccname`` credential ccache.
+        """
+        return krbV.CCache(ccname.encode(FS_ENCODING))
+
+    def __get_principal(self, ccname):
+        """
+        Return the ``krb5.Principal`` for the ``ccname`` credential ccache.
+        """
+        return self.__get_ccache(ccname).principal()
+
+    def default_ccname(self):
+        """
+        Return the default ccache file name.
+
+        This will return something like '/tmp/krb5cc_500'.
+
+        This cannot return anything meaningful if used in the server as a
+        request is processed.
+        """
+        return self.__default_ccache().name.decode(FS_ENCODING)
+
+    def default_principal(self):
+        """
+        Return the principal name in default credential cache.
+
+        This will return something like 'admin@EXAMPLE.COM'.  If no credential
+        cache exists for the invoking user, None is returned.
+
+        This cannot return anything meaningful if used in the server as a
+        request is processed.
+        """
+        return self.__default_principal().name.decode(ENCODING)
+
+    def default_realm(self):
+        """
+        Return the realm from the default credential cache.
+
+        This will return something like 'EXAMPLE.COM'.  If no credential cache
+        exists for the invoking user, None is returned.
+
+        This cannot return anything meaningful if used in the server as a
+        request is processed.
+        """
+        return krbV.default_context().default_realm.decode(ENCODING)
+
+    def get_principal(self, ccname):
+        """
+        Return the principal from credential cache file at ``ccname``.
+
+        This will return something like 'admin@EXAMPLE.COM'.
+        """
+        return self.__get_principal(ccname).name.decode(ENCODING)
+
+    def get_realm(self, ccname):
+        """
+        Return the realm from credential cache file at ``ccname``.
+
+        This will return something like 'EXAMPLE.COM'.
+        """
+        return self.__get_principal(ccname).realm.decode(ENCODING)
+
+
 api.register(krb)