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43a0881274
A user reported that if they set <forward mode='nat|route' dev='blah'> starting the network would fail if the device 'blah' didn't already exist. This is caused by using "iif" and "oif" in nftables rules to check for the forwarding device - these two commands work by saving the named interface's ifindex (an unsigned integer) when the rule is added, and comparing it to the ifindex associated with the packet's path at runtime. This works great if the interface both 1) exists when the rule is added, and 2) is never deleted and re-created after the rule is added (since it would end up with a different ifindex). When checking for the network's bridge device, it is okay for us to use "iif" and "oif", because the bridge device is created before the firewall rules are added, and will continue to exist until just after the firewall rules are deleted when the network is shutdown. But since the forward device might be deleted/re-added during the lifetime of the network's firewall rules, we must instead us "oifname" and "iifname" - these are much less efficient than "Xif" because they do a string compare of the interface's name rather than just comparing two integers (ifindex), but they don't require the interface to exist when the rule is added, and they can properly cope with the named interface being deleted and re-added later. Fixes: a4f38f6ffe6a9edc001d18890ccfc3f38e72fb94 Signed-off-by: Laine Stump <laine@redhat.com> Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
libvirt library code README
===========================
The directory provides the bulk of the libvirt codebase. Everything
except for the libvirtd daemon and client tools. The build uses a
large number of libtool convenience libraries - one for each child
directory, and then links them together for the final libvirt.so,
although some bits get linked directly to libvirtd daemon instead.
The files directly in this directory are supporting the public API
entry points & data structures.
There are two core shared modules to be aware of:
* util/ - a collection of shared APIs that can be used by any
code. This directory is always in the include path
for all things built
* conf/ - APIs for parsing / manipulating all the official XML
files used by the public API. This directory is only
in the include path for driver implementation modules
* vmx/ - VMware VMX config handling (used by esx/ and vmware/)
Then there are the hypervisor implementations:
* bhyve - bhyve - The BSD Hypervisor
* esx/ - VMware ESX and GSX support using vSphere API over SOAP
* hyperv/ - Microsoft Hyper-V support using WinRM
* lxc/ - Linux Native Containers
* openvz/ - OpenVZ containers using cli tools
* qemu/ - QEMU / KVM using qemu CLI/monitor
* remote/ - Generic libvirt native RPC client
* test/ - A "mock" driver for testing
* vbox/ - Virtual Box using native API
* vmware/ - VMware Workstation and Player using the vmrun tool
* xen/ - Xen using hypercalls, XenD SEXPR & XenStore
Finally some secondary drivers that are shared for several HVs.
Currently these are used by LXC, OpenVZ, QEMU and Xen drivers.
The ESX, Hyper-V, Remote, Test & VirtualBox drivers all
implement the secondary drivers directly
* cpu/ - CPU feature management
* interface/ - Host network interface management
* network/ - Virtual NAT networking
* nwfilter/ - Network traffic filtering rules
* node_device/ - Host device enumeration
* secret/ - Secret management
* security/ - Mandatory access control drivers
* storage/ - Storage management drivers
Since both the hypervisor and secondary drivers can be built as
dlopen()able modules, it is *FORBIDDEN* to have build dependencies
between these directories. Drivers are only allowed to depend on
the public API, and the internal APIs in the util/ and conf/
directories