Re: [RFC] Xend XML-RPC Refactoring

[Anthony Liguori <aliguori@us.ibm.com>]

Ewan Mellor wrote:
> On Sat, Mar 11, 2006 at 04:36:57PM -0500, Daniel Veillard wrote:
>
> Turning the server on and off is just for basic sanity -- the admin gets
> to choose which ports they want open so that they don't have to audit
> aspects in which they aren't interested.
>
> Of course, a full user / permissions system for the protocol would be a
> good idea, but like you say, it's not trivial work.  We could kick that
> discussion off if you want, but it's going to need someone to design
> the permissions semantics, management of users and roles, etc.  Is
> anyone interested in starting this?
>   
We can do basic authentication and require root credentials as a start.  
That's really easy to do but I'm not sure sending the root password as 
clear text really makes things much better :-)

Python, unfortunately, doesn't have server-side SSL bindings so basic 
authentication over SSL is not an option without some custom OpenSSL 
bindings.

Regards,

Anthony Liguori
> At the moment, the XML-RPC is over a Unix domain socket, so only root
> can use it anyway (as controlled by the permission on the socket file).
>
>   
>>>> diff -r c369d960f96b -r 095ac0d95d9c tools/python/xen/util/xmlrpclib2.py
>>>> --- /dev/null	Tue Feb 28 16:45:20 2006
>>>> +++ b/tools/python/xen/util/xmlrpclib2.py	Tue Feb 28 22:08:47 2006
>>>>
>>>> [Snip lots]
>>>>
>>>> +class ServerProxy(xmlrpclib.ServerProxy):
>>>> +    def __init__(self, uri, transport=None, encoding=None, verbose=0,
>>>> +                 allow_none=1):
>>>> +        if transport == None:
>>>> +            protocol = uri.split(':')[0]
>>>> +            if protocol == 'httpu':
>>>> +                uri = 'http:' + ':'.join(uri.split(':')[1:])
>>>> +                transport = UnixTransport()
>>>>         
>>> How about
>>>
>>> (protocol, rest) = uri.split(':', 1)
>>> if protocol == 'httpu':
>>>     uri = 'http:' + rest
>>>     transport = UnixTransport()
>>>       
>>   hum, do we really need to invent a new transport for local access ?
>> I don't remember seeing 'httpu' anywhere, sounds weird to me
>>     
>
> httpu is HTTP over a unix domain socket, as opposed to over TCP.  It's
> used elsewhere (though not widely, obviously).  It gives you basic
> protection from non-root users (see your complaint above).
>
>   
>> [...]
>>     
>>>>          except SystemExit:
>>>> +            sys.exit(1)
>>>> +        except xmlrpclib.Fault, ex:
>>>> +#            print "Xend generated an internal fault:"
>>>> +#            sys.stderr.write(ex.faultString)
>>>> +#            sys.exit(1)
>>>> +            print "Error: Internal Xend error"
>>>>         
>>> I expect we can do better than just printing "Internal Xend Error".  How
>>> much structure and useful information is there in an xmlrpclib.Fault at
>>> the moment?
>>>       
>>   Another good question, as we are defining an API to Xend I think
>> the error handling question will become more and more important. The client
>> will need more structure and informations about processing error, the 
>> full stack trace within xend might not be that useful (except for low level
>> debugging) to the clients, but currently I just extract a string like
>>   "No such domain test"
>> which is a bit hard to process correctly even in context. A list of predefined
>> error code and meaning could help quite a bit along with just the error message.
>>     
>
> Sure.  Do you have a list of error codes already (for libvirt, for
> example)?
>
> Ewan.
>