Calling nl_recvmsgs_default() leads dirctly to recvmsgs() from
"nl.c". This functions reads messages (recvmsg) in a loop and
invokes the callbacks.
Later we want to merge nlh and nlh_event, meaning that we must
anticipate parsing unrelated messages while waiting for an ACK.
While that would be possible by registering different callbacks
and letting them interact, it is actually more complicated. Just
assume full control over the message parsing.
Basically, copy recvmsgs() to event_handler_recvmsg(). For now just
copy the function and do little adjustment (to show the similarity
to the original). Cleanup follows.
The macro EWOULDBLOCK is another name for EAGAIN; they are always the
same in the GNU C Library.
https://www.gnu.org/savannah-checkouts/gnu/libc/manual/html_node/Error-Codes.html
Otherwise, we would need a workaround for EWOULDBLOCK too, because
libnl maps that to NLE_FAILURE. So we would have to detect EAGAIN
as (nle == -NLE_FAILURE && errno == EWOULDBLOCK).
When the errno was accidentally set to EAGAIN or EWOULDBLOCK,
we would only read one single message and return that there is
nothing to read.
This means, if there were more then one messages ready to read,
we would only read the first one and return to the main-loop
(which then again calls back to platform as more data is ready
to be read).
Link related functions should have a "nm_platform_link" prefix. Rename.
Naming is a subjective matter and one might argue that omitting
the "link" part from the name is shorter and even preferred.
However, I think functions related to links should have a common
prefix as the underlyings are strongly related.
Let the link-add functions return the internal pointer to the platform
link object. Similar to link-get, which doesn't copy the link either.
Also adjust the sole users of the add-functions (create-and-realize)
to take the pointer.
Eventually we still copy the returned data, because accessing platform can
invalidate the returned pointer. Thus we don't actually safe any copying
by this (at least every use of the function currently leads to the data
being copied).
Still change it, because I think the API of NMPlatform should look like that.
We potentially emit a lot of signals. Don't look up the
signal by name because that adds quite some additional
overhead, like peeking for a GQuark.
Instead pass the numeric signal-id directly.
This enum was unused and meaningless because the platform signals
are emitted as a consequence of netlink messages. It is not clear
whether a netlink message was received due to an external event
or an internal action.
Unslaving from a bridge causes a wrong RTM_DELLINK event for
the former slave.
# ip link add dummy0 type dummy
# ip link add bridge0 type bridge
# ip link set bridge0 up
# ip link set dummy0 master bridge0
# ip monitor link &
# ip link set dummy0 nomaster
18: dummy0: <BROADCAST,NOARP> mtu 1500 qdisc noop master bridge0 state DOWN group default
link/ether 76:44:5f:b9:38:02 brd ff:ff:ff:ff:ff:ff
18: dummy0: <BROADCAST,NOARP> mtu 1500 master bridge0 state DOWN
link/ether 76:44:5f:b9:38:02
Deleted 18: dummy0: <BROADCAST,NOARP> mtu 1500 master bridge0 state DOWN
link/ether 76:44:5f:b9:38:02
18: dummy0: <BROADCAST,NOARP> mtu 1500 qdisc noop state DOWN group default
link/ether 76:44:5f:b9:38:02 brd ff:ff:ff:ff:ff:ff
19: bridge0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc noqueue state DOWN group default
link/ether 00:00:00:00:00:00 brd ff:ff:ff:ff:ff:ff
19: bridge0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc noqueue state DOWN group default
link/ether 00:00:00:00:00:00 brd ff:ff:ff:ff:ff:ff
Previously, during do_request_link() we would remember the link that is
about to be requested (delayed_deletion) and delay processing a new
RTM_DELLINK message until the end of do_request_link() -- and possibly
forget about about the deletion, if RTM_DELLINK was followed by a
RTM_NEWLINK.
However, this hack does not catch the case where an external command
unslaves the link.
Instead just accept the wrong event and raise a "removed" signal right
away. This brings the cache in an externally visible, wrong state that
will be fixed by a following "added" signal.
Still do that because working around the kernel bug is complicated. Also,
we already might emit wrong "added" signals for devices that are already
removed. As a consequence, a user should not consider the platform signals
until all events are processed.
Listeners to that signal should accept that added/removed link changes
can be wrong and should preferably handle them idly, when the events
have settled.
It can even be worse, that a RTM_DELLINK is not fixed by a following
RTM_NEWLINK:
...
# ip link set dummy0 nomaster
36: dummy0: <BROADCAST,NOARP> mtu 1500 qdisc noop master bridge0 state DOWN
link/ether e2:f2:20:98:3a:be brd ff:ff:ff:ff:ff:ff
36: dummy0: <BROADCAST,NOARP> mtu 1500 master bridge0 state DOWN
link/ether e2:f2:20:98:3a:be
Deleted 36: dummy0: <BROADCAST,NOARP> mtu 1500 master bridge0 state DOWN
link/ether e2:f2:20:98:3a:be
37: bridge0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc noqueue state DOWN
link/ether 00:00:00:00:00:00 brd ff:ff:ff:ff:ff:ff
37: bridge0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc noqueue state DOWN
link/ether 00:00:00:00:00:00 brd ff:ff:ff:ff:ff:ff
So, when a slave is deleted, we have to refetch it too.
https://bugzilla.redhat.com/show_bug.cgi?id=1285719
On some kernels (at least RHEL-7.2) we receive a spurious RTM_NEWLINK
message after the RTM_DELLINK message for deleting a bond master.
On RHEL-7, the following commands give:
# ip link add dummy0 type dummy
# ip link add bond0 type bond
# ip link set bond0 up
# ip link set dummy0 master bond0
# ip monitor link &
# ip link del bond0
21: bond0: <BROADCAST,MULTICAST,MASTER> mtu 1500 qdisc noqueue state DOWN
link/ether 1e:a6:6c:81:c1:8d brd ff:ff:ff:ff:ff:ff
Deleted 21: bond0: <BROADCAST,MULTICAST,MASTER> mtu 1500 qdisc noop state DOWN
link/ether 1e:a6:6c:81:c1:8d brd ff:ff:ff:ff:ff:ff
20: dummy0: <BROADCAST,NOARP,UP,LOWER_UP> mtu 1500 qdisc noqueue state UNKNOWN
link/ether 1e:a6:6c:81:c1:8d brd ff:ff:ff:ff:ff:ff
21: bond0: <BROADCAST,MULTICAST,MASTER> mtu 1500 qdisc noop state DOWN
link/ether da:ee:58:70:6f:e5 brd ff:ff:ff:ff:ff:ff
^^^^^^^^^^^^^^^ RTM_NEWLINK after RTM_DELLINK (and there follows no
RTM_DELLINK afterwards)
21: bond0: <BROADCAST,MULTICAST,MASTER> mtu 1500 qdisc noop state DOWN
link/ether da:ee:58:70:6f:e5 brd ff:ff:ff:ff:ff:ff
20: dummy0: <BROADCAST,NOARP> mtu 1500 qdisc noqueue state DOWN
link/ether 1e:a6:6c:81:c1:8d brd ff:ff:ff:ff:ff:ff
20: dummy0: <BROADCAST,NOARP> mtu 1500 qdisc noqueue state DOWN
link/ether 1e:a6:6c:81:c1:8d brd ff:ff:ff:ff:ff:ff
Fix that by reverting clear_REFRESH_LINK(). This fix has two downsides:
- on kernels where this hack is not necessary, we unnecessarily refetch
a link
- the platform cache first removes the link, adds it again and removes
it. This is ugly, but should have no real consequences because all
listeners to the platform signals delay processing the signals to an
idle handler.
https://bugzilla.redhat.com/show_bug.cgi?id=1285719
This reverts commit f4f4e1cf09.
The related bug rh#1262908 in kernel causes missing netlink notifications
when moving a IFA_LINK interface to another netns.
Add a test for our workaround.
Related: https://bugzilla.redhat.com/show_bug.cgi?id=1262908
The related bug rh#1285827 in kernel causes a missing IFLA_LINK/parent
attribute when creating a veth pair:
# ip monitor link &
[1] 6745
# ip link add dev vm1 type veth peer name vm2
30: vm2@NONE: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN
link/ether be:e3:b7:0e:14:52 brd ff:ff:ff:ff:ff:ff
31: vm1@vm2: <BROADCAST,MULTICAST,M-DOWN> mtu 1500 qdisc noop state DOWN
link/ether da:e6:a6:c5:42:54 brd ff:ff:ff:ff:ff:ff
Add a workaround and test.
Related: https://bugzilla.redhat.com/show_bug.cgi?id=1285827
Due to kernel bugs [1], the first netlink event about a new link
sometimes lacks the IFLA_LINKINFO with the link-type lnk data.
In the case the data is missing, schedule a re-fetch the link
hoping that it gets send.
[1] https://bugzilla.redhat.com/show_bug.cgi?id=1284001
Previsously, _LOGT() could be disabled at compile time. Thus it
was different then the other macros _LOGD(), _LOGI(), etc.
OTOH, _LOGt() was the macro that always was compiled in.
Swap the name of the macros. Now the upper-case macros are always
enabled, while the lower-case macro _LOGt() is enabled depending
on compile configuration.
Previously, we would not set the ifi_change field, so that all
flags in ifi_flags were considered. That required us to lookup
the currently set flags from the cache.
Change that, to set only the flags in the netlink message that
we want to change. This saves us a cache-lookup, but more importantly,
the cache might be out of date.
Previously, we could only set the ingress-qos-mappings/egress-qos-mappings.
Now also cache the mappings and expose them from the platform cache.
Also, support changing the vlan flags not only when creating the vlan
interface.
Instead of using libnl-route-3 library to serialize netlink messages,
construct the netlink messages ourselves.
This has several advantages:
- Creating the netlink message ourself is actually more straight
forward then having an intermediate layer between NM and the kernel.
Now it is immediately clear, how a platform request translates to
a netlink/kernel request.
You can look at the kernel sources how a certain netlink attribute
behaves, and then it's immediately clear how to set that (and vice
versa).
- Older libnl versions might have bugs or missing features for which
we needed to workaround (often by offering a reduced/broken/untested
functionality). Now we can get rid or workaround like _nl_has_capability(),
check_support_libnl_extended_ifa_flags(), HAVE_LIBNL_INET6_TOKEN.
Another example is a libnl bug when setting vlan ingress map which
isn't even yet fixed in libnl upstream.
- We no longer need libnl-route-3 at all and can drop that runtime
requirement, saving some 400k.
Constructing the messages ourselves also gives better performance
because we don't have to create the intermediate libnl object.
- In the future we will add more link-type support which is easier
to support by basing directly on the plain kernel/netlink API,
instead of requiring also libnl3 to expose this functionality.
E.g. adding macvtap support: we already parsed macvtap properties
ourselves because of missing libnl support. To *add* macvtap
support, we also would have to do it ourself (or extend libnl).
Having a static string buffer for convenience is useful not only
for platform. Define the string buffer in NetworkManagerUtils.h,
so that all to-string functions can reuse *one* buffer.
Of course, this has the potential danger, that different
to-string method might reuse the same buffer. Hence, low-level
library functions are adviced to use their own buffer, because
an upper level might already use the global buffer for another
string.
The peer-address (IFA_ADDRESS) can also be all-zero (0.0.0.0).
That is distinct from an usual address without explicit peer-address,
which implicitly has the same peer and local address.
Previously, we treated an all-zero peer_address as having peer and
local address equal. This is especially grave, because the peer is part
of the primary key for an IPv4 address. So we not only get a property of
the address wrong, but we wrongly consider two different addresses as
one and the same.
To properly handle these addresses, we always must explicitly set the peer.
For recent kernels, the peer-ifindex of veths is reported as
parent (IFA_LINK). Prefer that over the ethtool lookup.
For one, this avoids the extra ethtool call which has the
downside of sidestepping the platform cache. Also, looking
up the peer-ifindex in ethtool does not report whether the
peer lifes in another netns (NM_PLATFORM_LINK_OTHER_NETNS).
Only use ethtool as fallback for older kernels.
Previously, while detecting the link type we would lookup the
@kind in case it was missing.
Now, go one step further, and also prefer the link-type from the
cache.
