[Xen-changelog] [xen-unstable] [XEND] Add some docstrings about XendAuthSessions

[Xen patchbot-unstable <patchbot-unstable@xxxxxxxxxxxxxxxxxxx>]

# HG changeset patch
# User Alastair Tse <atse@xxxxxxxxxxxxx>
# Node ID f0c7f258c19e0bd1f231dab4185287a0cff4db73
# Parent  f895b7c94f1044b737d7eeb718caa8da076419ed
[XEND] Add some docstrings about XendAuthSessions

Signed-off-by: Alastair Tse <atse@xxxxxxxxxxxxx>
---
 tools/python/xen/xend/XendAuthSessions.py |   33 +++++++++++++++++++++++++++---
 1 files changed, 30 insertions(+), 3 deletions(-)

diff -r f895b7c94f10 -r f0c7f258c19e tools/python/xen/xend/XendAuthSessions.py
--- a/tools/python/xen/xend/XendAuthSessions.py Thu Oct 19 17:46:08 2006 +0100
+++ b/tools/python/xen/xend/XendAuthSessions.py Thu Oct 19 17:46:54 2006 +0100
@@ -16,15 +16,21 @@
 #============================================================================
 
 import time
-import PAM
 
 from xen.xend import uuid
 from xen.xend.XendError import *
 from xen.xend.XendLogging import log
 
+try:
+    import PAM
+except ImportError:
+    log.warn("python-pam is required for XenAPI support.")
+
 class XendAuthSessions:
-    """Keeps track of Xen API Login Sessions. (Example only)"""
+    """Keeps track of Xen API Login Sessions using PAM.
 
+    Note: Login sessions are not valid across instances of Xend.
+    """
     def __init__(self):
         self.sessions = {}
 
@@ -32,6 +38,12 @@ class XendAuthSessions:
         pass
 
     def login_with_password(self, username, password):
+        """Returns a session UUID if valid, otherwise raises an error.
+
+        @raises XendError: If login fails.
+        @rtype: string
+        @return: Session UUID
+        """
         if self.is_authorized(username, password):
             new_session = uuid.createString()
             self.sessions[new_session] = (username, time.time())
@@ -40,16 +52,31 @@ class XendAuthSessions:
         raise XendError("Login failed")
 
     def logout(self, session):
+        """Delete session of it exists."""
         if self.is_session_valid(session):
             del self.sessions[session]
 
     def is_session_valid(self, session):
+        """Returns true is session is valid."""
         if type(session) == type(str()):
             return (session in self.sessions)
         return False
 
     def is_authorized(self, username, password):
-        pam_auth = PAM.pam()
+        """Returns true is a user is authorised via PAM.
+
+        Note: We use the 'login' PAM stack rather than inventing
+              our own.
+
+        @rtype: boolean
+        """
+        pam_auth = None
+        try:
+            pam_auth = PAM.pam()
+        except NameError:
+            # if PAM doesn't exist, let's ignore it
+            return False
+        
         pam_auth.start("login")
         pam_auth.set_item(PAM.PAM_USER, username)
 

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