Rawhide NetworkManager

[Nils Philippsen]

On Tue, 2005-03-22 at 12:42 -0500, Dan Williams wrote:
> On Tue, 2005-03-22 at 18:06 +0100, Nils Philippsen wrote:
> > On Tue, 2005-03-22 at 10:56 -0500, Dan Williams wrote:
> > 
> > > 3) Full access to DHCP options.  NetworkManager provides a DBUS API for
> > > applications to access DHCP options returned by the server.  For
> > > example, ntpd could listen to NetworkManager events and then restart
> > > itself with the new server address without ever having to read a config
> > > file.  xchat could listen to events and find out the corporate IRC
> > > server to connect to without ever needing user intervention.  There's a
> > > wealth of information passed along in DHCP options that applications can
> > > use.  I'm unaware of any method that "dhclient" has that could provide
> > > this information to NetworkManager.
> > 
> > Again, I currently use FC3 stuff, so I'm not sure how this applies here,
> > but when I last looked at it, only few information where passed to the
> > NMTester.py script in the examples directory. Maybe I got things wrong
> > (perhaps the app has to ask for DHCP specific stuff -- I'm a complete
> 
> Yes, the app must ask for the dhcp options itself.  This should be
> fairly easy from Python.  In pseudo code:
> 
> object_path = "/org/freedesktop/NetworkManager/DhcpOptions"
> interface = "org.freedesktop.NetworkManager.DhcpOptions"
> 
> type = dbus_call(object_path, interface, "getType", "NTP Servers")
> if type == DBUS_TYPE_ARRAY
>     ip_ary = dbus_call(object_path, interface, "getIntegerv", "NTP
> Servers")
>     ip = ip_ary[0]
> else
>     ip = dbus_call(object_path, interface, "getInteger", "NTP Servers")

Hmm, I couldn't make much heads or tails out of it, mostly because I
don't know what's pseudo in there and what not ;-), anyway: "dbus_call"
isn't wrapped in python. I tried to access the DHCP options like this:

--- 8< ---
import dbus

service = 'org.freedesktop.NetworkManager'
object_path = "/org/freedesktop/NetworkManager/DhcpOptions"
interface = "org.freedesktop.NetworkManager.DhcpOptions"

bus = dbus.Bus (dbus.Bus.TYPE_SYSTEM)
NWM_service = bus.get_service (service)
dhcpOptions = NWM_service.get_object (object_path, interface)
--- >8 ---

but the resulting dhcpOptions options doesn't have many methods to begin
with:

dhcpOptions: ['__doc__', '__getattr__', '__init__', '__module__',
'_interface', '_object_path', '_service', 'connect_to_signal']

Any clues for me here?

> and now "ip" contains the uint32 representation of an IP address for the
> first ntp server returned by the DHCP server, if any.  Remember that the
> server can return an arbitrary # of servers.
> 
> In the future, the DHCP options API from NetworkManager will always
> return an array, even for options that can only have 1 item.  That
> greatly simplifies bindings and code.
> 
> > neophyte when it comes to dbus e.a.), but I didn't see any information
> > related to DHCP there. Furthermore: AFAIK DHCP options get only
> > transmitted from the server when the client asks for them, so how would
> > I go about "custom" DHCP options I wanted to evaluate?
> 
> The client can request DHCP options from the server, but the server
> doesn't necessarily have to provide them.  The server is also free to
> provide more options than the client asked for I believe.

I found that you don't e.g. get the interface-mtu unless you ask for it.
It would be good if people could set it somewhere, even more so for non-
standard custom options that you want to be able to ask from NWM later
on in some python script (assuming you get it working of course).

Nils
-- 
     Nils Philippsen    /    Red Hat    /    nphilipp at redhat.com
"They that can give up essential liberty to obtain a little temporary
 safety deserve neither liberty nor safety."     -- B. Franklin, 1759
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