Introduce the gssapi-console utilitiy

This utility provides an interactive Python session that automatically
sets up and tears down a self-contained krb5 realm.  It does this
through the use of the `gssapi.tests.k5test` module.  The created
`K5Realm` class is accessible inside the session as `REALM`, provides
methods for manipulating the realm setup (such as creating principals,
kinit-ing, etc).  Additionally, `gssapi` and `gssapi.raw as gb` are
automatically imported.

Just like the normal Python interpreter, when no file is passed,
interactive mode is used.  Otherwise if a file is passed, the file
is simply run in the context of the realm, unless the `-i` option
is used.  Comma-separated boolean options can also be passed to
the realm constructor via the `--realm-args` option, in the form
of `key=(true|false)`.

Author: DirectXMan12

gssapi-console.py

@@ -0,0 +1,142 @@
+#!/usr/bin/env python
+
+# interactive console with easy access to krb5 test harness stuff
+
+import code
+import os
+import sys
+import copy
+
+from gssapi.tests import k5test
+
+
+READLINE_SRC = """
+# python startup file
+import readline
+import rlcompleter
+import atexit
+import os
+
+completer = rlcompleter.Completer(globals())
+readline.set_completer(completer.complete)
+
+# tab completion
+readline.parse_and_bind('Control-space: complete')
+# history file
+histfile = os.path.join(os.environ['HOME'], '.pythonhistory')
+try:
+    readline.read_history_file(histfile)
+except IOError:
+    pass
+
+atexit.register(readline.write_history_file, histfile)
+del os, histfile, readline, rlcompleter
+"""
+
+BANNER = """GSSAPI Interactive console
+Python {ver} on {platform}
+Type "help", "copyright", "credits" or "license" for more information about Python.
+
+mechansim: {mech}, realm: {realm}, user: {user}, host: {host}
+(functions for controlling the realm available in `REALM`)"""
+
+
+class GSSAPIConsole(code.InteractiveConsole):
+    def __init__(self, use_readline=True, realm_args={}, *args, **kwargs):
+        code.InteractiveConsole.__init__(self, *args, **kwargs)
+
+        self.realm = self._create_realm(realm_args)
+        self.locals['REALM'] = self.realm
+
+        self.runsource('import gssapi')
+        self.runsource('import gssapi.raw as gb')
+
+        if use_readline:
+            self._add_readline()
+
+        if os.environ.get('LD_LIBRARY_PATH'):
+            self.realm.env['LD_LIBRARY_PATH'] = os.environ['LD_LIBRARY_PATH']
+
+    def _create_realm(self):
+        return None
+
+    def _add_readline(self):
+        res = self.runsource(READLINE_SRC, '<readline setup>', 'exec')
+
+
+class Krb5Console(GSSAPIConsole):
+    def _create_realm(self, realm_args):
+        return k5test.K5Realm(**realm_args)
+
+
+MECH_MAP = {'krb5': Krb5Console}
+
+
+import argparse
+parser = argparse.ArgumentParser(description='An interactive Python console with krb5 setup')
+parser.add_argument('file', metavar='FILE', nargs='?',
+                    help='a file to run', default=None)
+parser.add_argument('-i', default=False, dest='force_interactive',
+                    action='store_const', const=True,
+                    help='Force interactive mode when running with a file')
+parser.add_argument('--realm-args', default=None,
+                    help='A comma-separated list of key=(true|false) values to '
+                         'pass to the realm constructor')
+parser.add_argument('--mech', default='krb5',
+                    help='Which environment to setup up '
+                         '(supports krb5 [default])')
+
+PARSED_ARGS = parser.parse_args()
+
+
+if PARSED_ARGS.mech not in MECH_MAP:
+    sys.exit('The %s environment is not supported by the '
+             'GSSAPI console' % PARSED_ARGS.mech)
+
+
+realm_args = {}
+if PARSED_ARGS.realm_args:
+    for arg in PARSED_ARGS.realm_args.split(','):
+        key, raw_val = arg.split('=')
+        realm_args[key] = (raw_val.lower() == 'true')
+
+console = MECH_MAP[PARSED_ARGS.mech](realm_args=realm_args)
+SAVED_ENV = None
+
+try:
+    # create the banner
+    banner_text = BANNER.format(ver=sys.version, platform=sys.platform,
+                                mech=PARSED_ARGS.mech,
+                                realm=console.realm.realm,
+                                user=console.realm.user_princ,
+                                host=console.realm.host_princ)
+
+    # import the env
+    SAVED_ENV = copy.deepcopy(os.environ)
+    for k,v in console.realm.env.items():
+        os.environ[k] = v
+
+    INTER = True
+    # run the interactive interpreter
+    if PARSED_ARGS.file is not None:
+        if not PARSED_ARGS.force_interactive:
+            INTER = False
+
+        with open(PARSED_ARGS.file) as src:
+            console.runsource(src.read(), src.name, 'exec')
+
+    if INTER:
+        console.interact(banner_text)
+
+except (KeyboardInterrupt, EOFError):
+    pass
+finally:
+    # restore the env
+    if SAVED_ENV is not None:
+        for k in copy.deepcopy(os.environ):
+            if k in SAVED_ENV:
+                os.environ[k] = SAVED_ENV[k]
+            else:
+                del os.environ[k]
+
+    console.realm.stop()