https://bugzilla.redhat.com/show_bug.cgi?id=1047577

When a client closes its connection to libvirtd early during
virConnectOpen, more specifically just after making
REMOTE_PROC_CONNECT_SUPPORTS_FEATURE call to check if
VIR_DRV_FEATURE_PROGRAM_KEEPALIVE is supported without even waiting for
the result, libvirtd may crash due to a race in keep-alive
initialization. Once receiving the REMOTE_PROC_CONNECT_SUPPORTS_FEATURE
call, the daemon's event loop delegates it to a worker thread. In case
the event loop detects EOF on the connection and calls
virNetServerClientClose before the worker thread starts to handle
REMOTE_PROC_CONNECT_SUPPORTS_FEATURE call, client->keepalive will be
disposed by the time virNetServerClientStartKeepAlive gets called from
remoteDispatchConnectSupportsFeature. Because the flow is common for
both authenticated and read-only connections, even unprivileged clients
may cause the daemon to crash.

To avoid the crash, virNetServerClientStartKeepAlive needs to check if
the connection is still open before starting keep-alive protocol.

Every libvirt release since 0.9.8 is affected by this bug.

Any test suite which involves a virDomainDefPtr should
call virDomainDefCheckABIStability with itself just as
a basic sanity check that the identity-comparison always
succeeds. This would have caught the recent NULL pointer
access crash.

Make sure we cope with def->name being NULL since the
VMWare config parser produces NULL names.
Signed-off-by: NDaniel P. Berrange <berrange@redhat.com>

When idmap was added to LXC, we forgot to cover it in the testsuite.
The schema was missing an <element> layer, and as a result,
virt-xml-validate was failing on valid dumpxml output.

Reported by Eduard - Gabriel Munteanu on IRC.

* docs/schemas/domaincommon.rng (idmap): Include <idmap> element,
and support interleaves.
* tests/lxcxml2xmldata/lxc-idmap.xml: New file.
* tests/lxcxml2xmltest.c (mymain): Test it.
Signed-off-by: NEric Blake <eblake@redhat.com>

Include the name of the storage backend in the error message instead of
just the number.

Change code ordering to avoid the need for a forward declaration.

The comment was talking about creating the pool while the function is
deleting it. Fix the mismatch.

Ever since commit 61ac8ce0, Coverity complained about
remoteNetworkBuildEventLifecycle not checking for NULL failure
to build an event, compared to other calls in the code base.
But the problem is latent from copy and paste; all 17 of our
remote*BuildEvent* functions in remote_driver.c have the same
issue - if an OOM causes an event to not be built, we happily
pass NULL to remoteEventQueue(), but that function has marked
event as a nonnull parameter.  We were getting lucky (the
event queue's first use of the event happened to be a call to
virIsObjectClass(), which acts gracefully on NULL, so there
was no way to crash); but this is a latent bug waiting to bite
us due to the disregard for the nonnull attribute, as well as
a waste of resources in the event queue.  Better is to just
refuse to queue NULL.  The discard is silent, since the problem
only happens on OOM, and since events are already best effort -
if we fail to get an event, it's not like we have any memory
left to report the issue, nor any idea of who would benefit
from knowing we couldn't create or queue the event.

* src/remote/remote_driver.c (remoteEventQueue): Ignore NULL event.
Signed-off-by: NEric Blake <eblake@redhat.com>

Our fixes for CVE-2013-4400 were so effective at "fixing" bugs
in virt-login-shell that we ended up fixing it into a useless
do-nothing program.

Commit 3e2f27e1 picked the name LIBVIRT_SETUID_RPC_CLIENT for
the witness macro when we are doing secure compilation.  But
commit 9cd6a57d checked whether the name IN_VIRT_LOGIN_SHELL,
from an earlier version of the patch series, was defined; with
the net result that virt-login-shell invariably detected that
it was setuid and failed virInitialize.

Commit b7fcc799 closed all fds larger than stderr, but in the
wrong place.  Looking at the larger context, we mistakenly did
the close in between obtaining the set of namespace fds, then
actually using those fds to switch namespace, which means that
virt-login-shell will ALWAYS fail.

This is the minimal patch to fix the regressions, although
further patches are also worth having to clean up poor
semantics of the resulting program (for example, it is rude to
not pass on the exit status of the wrapped program back to the
invoking shell).

* tools/virt-login-shell.c (main): Don't close fds until after
namespace swap.
* src/libvirt.c (virGlobalInit): Use correct macro.
Signed-off-by: NEric Blake <eblake@redhat.com>

The existing check of domain snapshots validated that they
point to a domain, but did not validate that the domain
points to a connection, even though any errors blindly assume
the connection is valid.  On the other hand, as mentioned in
commit 6e130ddc, any valid domain is already tied to a valid
connection, and VIR_IS_SNAPSHOT vs. VIR_IS_DOMAIN_SNAPSHOT
makes no real difference; it's best to just validate the chain
of all three.  For consistency with previous patches, continue
the trend of using a common macro.  For now, we don't need
virCheckDomainSnapshotGoto().

* src/datatypes.h (virCheckDomainSnapshotReturn): New macro.
(VIR_IS_SNAPSHOT, VIR_IS_DOMAIN_SNAPSHOT):
Drop unused macros.
* src/libvirt.c: Use macro throughout.
(virLibDomainSnapshotError): Drop unused macro.
Signed-off-by: NEric Blake <eblake@redhat.com>

While all errors related to invalid nwfilters appeared to be
consistent, we might as well continue the trend of using a
common macro.  As in commit 6e130ddc, the difference between
VIR_IS_NWFILTER and VIR_IS_CONNECTED_NWFILTER is moot, since
reference counting means any valid nwfilter is also tied to
a valid connection.  For now, we don't need virCheckNWFilterGoto().

* src/datatypes.h (virCheckNWFilterReturn): New macro.
(VIR_IS_NWFILTER, VIR_IS_CONNECTED_NWFILTER): Drop unused macros.
* src/libvirt.c: Use macro throughout.
(virLibNWFilterError): Drop unused macro.
Signed-off-by: NEric Blake <eblake@redhat.com>

For streams validation, we weren't consistent on whether to
use VIR_FROM_NONE or VIR_FROM_STREAMS.  Furthermore, in many
API, we want to ensure that a stream is tied to the same
connection as the other object we are operating on; while
other API failed to validate the stream at all.  And the
difference between VIR_IS_STREAM and VIR_IS_CONNECTED_STREAM
is moot; as in commit 6e130ddc, we know that reference
counting means a valid stream will always be tied to a valid
connection.  Similar to previous patches, use a common macro
to make it nicer.

* src/datatypes.h (virCheckStreamReturn, virCheckStreamGoto):
New macros.
(VIR_IS_STREAM, VIR_IS_CONNECTED_STREAM): Drop unused macros.
* src/libvirt.c: Use macro throughout.
(virLibStreamError): Drop unused macro.
Signed-off-by: NEric Blake <eblake@redhat.com>

While all errors related to invalid secrets appeared to be
consistent, we might as well continue the trend of using a
common macro.  Just as in commit 6e130ddc, the difference
between VIR_IS_SECRET and VIR_IS_CONNECTED_SECRET is moot
(due to reference counting, any valid secret must be tied to
a valid domain).  For now, we don't need virCheckSecretGoto().

* src/datatypes.h (virCheckSecretReturn): New macro.
(VIR_IS_SECRET, VIR_IS_CONNECTED_SECRET): Drop unused macros.
* src/libvirt.c: Use macro throughout.
(virLibSecretError): Drop unused macro.
Signed-off-by: NEric Blake <eblake@redhat.com>

While all errors related to invalid node device appeared to be
consistent, we might as well continue the trend of using a
common macro.  For now, we don't need virCheckNodeDeviceGoto().

* src/datatypes.h (virCheckNodeDeviceReturn): New macro.
(VIR_IS_NODE_DEVICE, VIR_IS_CONNECTED_NODE_DEVICE): Drop
unused macros.
* src/libvirt.c: Use macro throughout.
(virLibNodeDeviceError): Drop unused macro.
Signed-off-by: NEric Blake <eblake@redhat.com>

The commit cad3cf9a introduced a crash
due to wrong order of parameters being passed to the function.  When
deleting an element, the function decreased the iterator instead of
count and if listing volumes after that (or undefining the pool, NULL
was being dereferenced.
Signed-off-by: NMartin Kletzander <mkletzan@redhat.com>

Yet another advice appeared on the Multiqueue wiki page:

http://www.linux-kvm.org/page/Multiqueue#Enable_MQ_feature

We should add vectors=N onto the qemu command line, where
N = 2 * (number of queues) + 1.

For storage volume validation, we weren't consistent on
whether to use VIR_FROM_NONE or VIR_FROM_STORAGE.  Similar
to previous patches, use a common macro to make it nicer.
Furthermore, just as in commit 6e130ddc, the difference
between VIR_IS_STORAGE_VOL and VIR_IS_CONNECTED_STORAGE_VOL
is moot (due to reference counting, any valid volume must
be tied to a valid connection).

virStorageVolCreateXMLFrom allows cross-connection cloning,
where the error is reported against the connection of the
destination pool.

* src/datatypes.h (virCheckStorageVolReturn)
(virCheckStorageVolGoto): New macros.
(VIR_IS_STORAGE_VOL, VIR_IS_CONNECTED_STORAGE_VOL): Drop
unused macros.
* src/libvirt.c: Use macro throughout.
(virLibStorageVolError): Drop unused macro.
Signed-off-by: NEric Blake <eblake@redhat.com>

We point to the manpages where available and redirect to libvirt's
homepage as a last resort.

This basically reverts commit ba64b971
"libxl: Allow libxl to set NIC devid". However assigning devid's
before calling libxlMakeNic does not work as that is calling
libxl_device_nic_init which sets it back to -1.
Right now auto-assignment only works in the hotplug case. But even if
that would be fixed at some point (if that is possible at all), this
would add a weird dependency between Xen and libvirt versions.
The change here should accept any auto-assignment that makes it into
libxl_device_nic_init. My understanding is that a caller always is
allowed to make the devid choice itself. And assuming libxlMakeNicList
is only used on domain creation, a sequential numbering should be ok.
Signed-off-by: NStefan Bader <stefan.bader@canonical.com>

virStoragePoolBuild reported an invalid pool as if it were an
invalid network.  Likewise, we weren't consistent on whether to
use VIR_FROM_NONE or VIR_FROM_STORAGE.  Similar to previous
patches, use a common macro to make it nicer.  Furthermore, just
as in commit 6e130ddc, the difference between VIR_IS_STORAGE_POOL
and VIR_IS_CONNECTED_STORAGE_POOL is moot (due to reference
counting, any valid pool must be tied to a valid connection).
For now, we don't need virCheckStoragePoolGoto().

* src/datatypes.h (virCheckStoragePoolReturn): New macro.
(VIR_IS_STORAGE_POOL, VIR_IS_CONNECTED_STORAGE_POOL): Drop
unused macros.
* src/libvirt.c: Use macro throughout.
(virLibStoragePoolError): Drop unused macro.
Signed-off-by: NEric Blake <eblake@redhat.com>

There is no easy way to test authentication against libvirt.  This
commit modifies the test driver to allow simple username/password
authentication.

You modify the test XML by adding:

 <node>
   ...
   <auth>
     <user password="123456">rich</user>
     <user>jane</user>
   </auth>
 </node>

If there are any /node/auth/user elements, then authentication is
required by the test driver (if none are present, then the test driver
will work as before and not require authentication).

In the example above, two phony users are added:

 rich  password: 123456
 jane  no password required

The test driver will demand a username.  If the password attribute is
present (or if the username entered is wrong), then the password is
also asked for and checked:

 $ virsh -c test://$(pwd)/testnode.xml list
 Enter username for localhost: rich
 Enter rich's password for localhost: ***
  Id    Name                           State
 ----------------------------------------------------
  1     fv0                            running
  2     fc4                            running
Signed-off-by: NRichard W.M. Jones <rjones@redhat.com>

When checking for a valid interface, we weren't consistent on
whether we reported as VIR_FROM_NONE or VIR_FROM_INTERFACE.
Similar to previous patches, use a common macro to make it nicer.
Furthermore, just as in commit 6e130ddc, the difference between
VIR_IS_INTERFACE and VIR_IS_CONNECTED_INTERFACE is moot (due to
reference counting, any valid interface must be tied to a valid
connection).  For now, we don't need virCheckInterfaceGoto().

* src/datatypes.h (virCheckInterfaceReturn): New macro.
(VIR_IS_INTERFACE, VIR_IS_CONNECTED_INTERFACE): Drop unused
macros.
* src/libvirt.c: Use macro throughout.
(virLibInterfaceError): Drop unused macro.
Signed-off-by: NEric Blake <eblake@redhat.com>

Commit cfd62c1f was incomplete; I found more cases where error
messages were being overwritten, and where the code between
the three registration/deregistration APIs was not consistent.

Since it is fairly easy to trigger an attempt to deregister an
unregistered object through public API, I also changed the error
message from VIR_ERR_INTERNAL_ERROR to VIR_ERR_INVALID_ARG.

* src/conf/object_event.c (virObjectEventCallbackListEventID):
Inline...
(virObjectEventStateEventID): ...into lone caller, and report
error on failure.
(virObjectEventCallbackListAddID, virObjectEventStateCallbackID)
(virObjectEventCallbackListRemoveID)
(virObjectEventCallbackListMarkDeleteID): Tweak error category.
* src/remote/remote_driver.c (remoteConnectDomainEventRegister):
Don't leak registration on failure.
(remoteConnectDomainEventDeregisterAny)
(remoteConnectNetworkEventDeregisterAny): Don't overwrite error.
Signed-off-by: NEric Blake <eblake@redhat.com>

When checking for a valid network, we weren't consistent on
whether we reported an invalid network or a connection.  Similar
to previous patches such as commit 6e130ddc, the difference
between VIR_IS_NETWORK and VIR_IS_CONNECTED_NETWORK is moot (due
to reference counting, any valid network must be tied to a valid
connection).  Use a common macro to make the error reporting
for invalid networks nicer.

* src/datatypes.h (virCheckNetworkReturn, virCheckNetworkGoto): New
macros.
(VIR_IS_NETWORK, VIR_IS_CONNECTED_NETWORK): Drop unused macros.
* src/libvirt.c: Use macro throughout.
(virLibNetworkError): Drop unused macro.
Signed-off-by: NEric Blake <eblake@redhat.com>

Like commit 94a26c7e from Eric Blake, the old fuzzy code should
be replaced by the new array management macros now.

And the type of scsi->count should be changed into "size_t", and
thus virSCSIDeviceListCount should return size_t instead, similar
for vir{PCI,USB}DeviceListCount.

Signed-off-by: NChen Hanxiao <chenhanxiao@cn.fujitsu.com>

the unix socket /var/run/libvirt/lxc/domain.sock is not created
under the selinux context which configured by <seclabel>.

If we try to connect the domain.sock under the selinux context
of domain in virtLXCProcessConnectMonitor,selinux will deny
this connect operation.

type=AVC msg=audit(1387953696.067:662): avc:  denied  { connectto } for  pid=21206 comm="libvirtd" path="/usr/local/var/run/libvirt/lxc/systemd.sock" scontext=unconfined_u:system_r:svirt_lxc_net_t:s0:c770,c848 tcontext=unconfined_u:system_r:unconfined_t:s0-s0:c0.c1023 tclass=unix_stream_socket

fix this problem by creating socket under selinux context of domain.
Signed-off-by: NGao feng <gaofeng@cn.fujitsu.com>

Signed-off-by: NMartin Kletzander <mkletzan@redhat.com>

https://bugzilla.redhat.com/show_bug.cgi?id=1049529

The 'detach-disk' command in virsh used the active XML definition of a
domain even when attempting to remove a disk from the config only. If
the disk was only in the inactive definition the operation failed. Fix
this by using the inactive XML in case that only the config is affected.

https://bugzilla.redhat.com/show_bug.cgi?id=1049529

The legacy virDomainAttachDevice and virDomainDetachDevice operate only
on active domains. When a user specified --current flag with an inactive
domain the old API was used and reported an error. Fix it by calling the
new API if --current is specified explicitly.

The function checks for @conn to be valid and locks its mutex. Then, it
checks if callee is unregistering the same callback that he registered
previously. If this fails an error is reported and  the control jumps to
'error' label. Here, if @conn has some errors (and it certainly does -
the one that's been just reported) the conn->mutex is locked again -
without any previous unlock:

  Thread 1 (Thread 0x7fb500ef1800 (LWP 18982)):
  #0  __lll_lock_wait () at ../nptl/sysdeps/unix/sysv/linux/x86_64/lowlevellock.S:135
  #1  0x00007fb4fd99ce56 in _L_lock_918 () from /lib64/libpthread.so.0
  #2  0x00007fb4fd99ccaa in __GI___pthread_mutex_lock (mutex=0x7fb50153b670) at pthread_mutex_lock.c:64
  #3  0x00007fb5007e574d in virMutexLock (m=m@entry=0x7fb50153b670) at util/virthreadpthread.c:85
  #4  0x00007fb5007b198e in virDispatchError (conn=conn@entry=0x7fb50153b5e0) at util/virerror.c:594
  #5  0x00007fb5008a3735 in virConnectUnregisterCloseCallback (conn=0x7fb50153b5e0, cb=cb@entry=0x7fb500f588e0 <vshCatchDisconnect>) at libvirt.c:21025
  #6  0x00007fb500f5d690 in vshReconnect (ctl=ctl@entry=0x7fffff60e710) at virsh.c:328
  #7  0x00007fb500f5dc50 in vshCommandRun (ctl=ctl@entry=0x7fffff60e710, cmd=0x7fb50152ca80) at virsh.c:1755
  #8  0x00007fb500f5861b in main (argc=<optimized out>, argv=<optimized out>) at virsh.c:3393

And since the conn's mutex is not recursive, the virDispatchError will
never ever lock it successfully.
Signed-off-by: NMichal Privoznik <mprivozn@redhat.com>

Cleanup after a previous patch, commit 6e130ddc.  In particular,
note that xenDomainUsedCpus can only be reached from
xenUnifiedDomainGetXMLDesc, which in turn is only reached from
public API that already validated the domain.

* src/xen/xen_driver.c (xenDomainUsedCpus): Drop redundant check.
* src/datatypes.h (VIR_IS_DOMAIN, VIR_IS_CONNECTED_DOMAIN):
Delete, and inline into all callers, since no other file uses it
any more.
Signed-off-by: NEric Blake <eblake@redhat.com>

Make it easy to install the shipped examples. The aim is to have
reasonably working templates so that distros only need to minimally
patch these and can feed things upstream more easily.

This was prompted by http://bugs.debian.org/725144

In datatype.c, virGetDomainSnapshot could result in the message:

error: invalid domain pointer in bad domain

Furthermore, while there are a few functions in libvirt.c that
only care about a virDomainPtr without regards to the connection
(such as virDomainGetName), most functions also require a valid
connection.  Yet several functions were blindly dereferencing
the conn member without checking it for validity first (such as
virDomainOpenConsole).  Rather than try and correct all usage
of VIR_IS_DOMAIN vs. VIR_IS_CONNECTED_DOMAIN, it is easier to
just blindly require that a valid domain object always has a
valid connection object (which should be true anyways, since
every domain object holds a reference to its connection, so the
connection will not be closed until all domain objects have
also been closed to release their reference).

After this patch, all places that validate a domain consistently
report:

error: invalid domain pointer in someFunc

* src/datatypes.h (virCheckDomainReturn, virCheckDomainGoto): New
macros.
* src/datatypes.c (virGetDomainSnapshot): Use new macro.
(virLibConnError): Delete unused macro.
Signed-off-by: NEric Blake <eblake@redhat.com>

While comparing network and domain events, I noticed that the
test driver had to do a cast in one place and not the other.
For consistency, we should hide the necessary casting as low
as possible in the stack, with everything else using saner
types.

* src/conf/network_event.h (virNetworkEventStateRegisterID): Alter
type.
* src/conf/network_event.c (virNetworkEventStateRegisterID): Hoist
cast here.
* src/test/test_driver.c (testConnectNetworkEventRegisterAny):
Simplify callers.
* src/remote/remote_driver.c
(remoteConnectNetworkEventRegisterAny): Likewise.
* src/network/bridge_driver.c
(networkConnectNetworkEventRegisterAny): Likewise.
Signed-off-by: NEric Blake <eblake@redhat.com>

If a user registers for a domain event filtered to a particular
domain, but the persistent domain is offline at the time, then
the code silently failed to set up the filter.  As a result,
the event fires for all domains, rather than being filtered.
Network events were immune, since they always passed an id
0 argument.

The key to this patch is realizing that
virObjectEventDispatchMatchCallback() only cared about uuid;
so refusing to create a meta for a negative id is pointless,
and in fact, malloc'ing meta at all was overkill; instead,
just directly store a uuid and a flag of whether to filter.

Note that virObjectEventPtr still needs all fields of meta,
because this is how we reconstruct a virDomainPtr inside the
dispatch handler before calling the end user's callback
pointer with the correct object, even though only the uuid
portion of meta is used in deciding whether a callback
matches the given event.  So while uuid is optional for
callbacks, it is mandatory for events.

The change to testDomainCreateXMLMixed is merely on the setup
scenario (as you can't register for a domain unless it is either
running or persistent).  I actually first wrote that test for
this patch, then rebased it to also cover a prior patch (commit
4221d64f), but had to adjust it for that patch to use Create
instead of Define for setting up the domain long enough to
register the event in order to work around this bug.  But while
the setup is changed, the main body of the test is still about
whether creation events fire as expected.

* src/conf/object_event_private.h (_virObjectEventCallback):
Replace meta with uuid and flag.
(virObjectEventCallbackListAddID): Update signature.
* src/conf/object_event.h (virObjectEventStateRegisterID):
Likewise.
* src/conf/object_event_private.h (virObjectEventNew): Document
use of name and uuid in events.
* src/conf/object_event.c (virObjectEventCallbackListAddID): Drop
arguments that don't affect filtering.
(virObjectEventCallbackListRemoveID)
(virObjectEventDispatchMatchCallback)
(virObjectEventStateRegisterID): Update clients.
* src/conf/domain_event.c (virDomainEventCallbackListAdd)
(virDomainEventStateRegisterID): Likewise.
* src/conf/network_event.c (virNetworkEventStateRegisterID):
Likewise.
* tests/objecteventtest.c (testDomainCreateXMLMixed): Enhance test.
Signed-off-by: NEric Blake <eblake@redhat.com>

Consider these two calls, in either order:

id1 = virConnectDomainEventRegisterAny(conn, NULL,
   VIR_DOMAIN_EVENT_ID_LIFECYCLE,
   VIR_DOMAIN_EVENT_CALLBACK(callback), NULL, NULL);
virConnectDomainEventRegister(conn, callback, NULL, NULL);

Right now, the second call fails, because under the hood, the
old-style function registration is tightly coupled to the
new style lifecycle eventID, and the two calls both try
to register the same global eventID callback representation.

We've alreay documented that users should avoid old-style
registration and deregistration, so anyone heeding the advice
won't run into this situation.  But it would be even nicer if
we pretend the two interfaces are completely separate, and
disallow any cross-linking.  That is, a call to old-style
deregister should never remove a new-style callback even if it
is the same function pointer, and a call to new-style callback
using only callbackIDs obtained legitimately should never
remove an old-style callback (of course, since our callback
IDs are sequential, and there is still coupling under the
hood, you can easily guess the callbackID of an old style
registration and use new-style deregistration to nuke it - but
that starts to be blatantly bad coding on your part rather
than a surprising result on what looks like reasonable
stand-alone API).

With this patch, you can now register a global lifecycle event
handler twice, by using both old and new APIs; if such an event
occurs, your callback will be entered twice.  But that is not a
problem in practice, since it is already possible to use the
new API to register both a global and per-domain event handler
using the same function, which will likewise fire your callback
twice for that domain.  Duplicates are still prevented when
using the same API with same parameters twice (old-style twice,
new-style global twice, or new-style per-domain with same domain
twice), and things are still bounded (it is not possible to
register a single function pointer more than N+2 times per event
id, where N is the number of domains available on the connection).
Besides, it has always been possible to register as many
separate function pointers on the same event id as desired,
through either old or new style API, where the bound there is
the physical limitation of writing a program with enough
distinct function pointers.

Adding another event registration in the testsuite is sufficient
to cover this, where the test fails without the rest of the patch.

* src/conf/object_event.c (_virObjectEventCallback): Add field.
(virObjectEventCallbackLookup): Add argument.
(virObjectEventCallbackListAddID, virObjectEventStateCallbackID):
Adjust callers.
* tests/objecteventtest.c (testDomainCreateXMLMixed): Enhance test.
Signed-off-by: NEric Blake <eblake@redhat.com>

On the surface, this sequence of API calls should succeed:

id1 = virConnectDomainEventRegisterAny(..., VIR_DOMAIN_EVENT_ID_LIFECYCLE,...);
id2 = virConnectDomainEventRegisterAny(..., VIR_DOMAIN_EVENT_ID_RTC_CHANGE,...);
virConnectDomainEventDeregisterAny(id1);
id1 = virConnectDomainEventRegisterAny(..., VIR_DOMAIN_EVENT_ID_LIFECYCLE,...);

And for test:///default, it does.  But for qemu:///system, it fails:
libvirt: XML-RPC error : internal error: domain event 0 already registered

Looking closer, the bug is caused by miscommunication between
the object event engine and the client side of the remote driver.
In our implementation, we set up a single server-side event per
eventID, then the client side replicates that one event to all
callbacks that have been registered client side.  To know when
to turn the server side eventID on or off, the client side must
track how many events for the same eventID have been registered.
But while our code was filtering by eventID on event registration,
it did not filter on event deregistration.  So the above API calls
resulted in the deregister returning 1 instead of 0, so no RPC
deregister was issued, and the final register detects on the
server side that the server is already handling eventID 0.

Unfortunately, since the problem is only observable on remote
connections, it's not possible to enhance objecteventtest to
expose the semantics using only public API entry points.

* src/conf/object_event.c (virObjectEventCallbackListCount): New
function.
(virObjectEventCallbackListAddID)
(virObjectEventCallbackListRemoveID)
(virObjectEventCallbackListMarkDeleteID): Use it.
Signed-off-by: NEric Blake <eblake@redhat.com>

When the host is configured with very restrictive firewall (default policy
is DROP for all chains, including OUTPUT), the bridge driver for Linux
adds netfilter entries to allow DHCP and DNS requests to go from the VM
to the dnsmasq of the host.

The issue that this commit fixes is the fact that a DROP policy on the OUTPUT
chain blocks the DHCP replies from the host’s dnsmasq to the VM.
As DHCP replies are sent in UDP, they are not caught by any --ctstate ESTABLISHED
rule and so, need to be explicitly allowed.
Signed-off-by: NLénaïc Huard <lenaic@lhuard.fr.eu.org>