It might very well return EAGAIN in case of packet checksum problems and
suchlike, hence let's better handle this nicely, the same way as we do it in
the other sd-network libraries for incoming datagrams.
Let's make sd-lldp a bit more like sd-ndisc ant the other APIs, and add proper
ref counting and a separate call for setting the ifindex.
This also adds a new lldp_reset() call we can use at various places to close
all fds. This is also similar to how sd-ndisc already does it.
It's a good idea to store away the recption time of LLDP packets in the
neighbor object, simply because the LLDP data only has a validity of a certain
amount of time.
Hence, let's record the timestamp when we receive the datagram and expose an
API for it. Also, automatically expire LLDP neighbors based on this new
timestamp.
lldp_start_timer() was only called during sd_lldp_get_neighbors().
Ensure that the timer is (re-)started when a new neighbor appears.
Otherwise, the timer is not started when relying on the events alone.
Fixes: 34437b4f9c
Instead of just notifying about the fact that something changed in the
database, actually inform the callback what precisely changed. This is useful,
so that the LLDP tx logic can be put into "fast" mode as soon as a previously
unknown peer appears, as suggested by the LLDP spec.
This reworks the sd-lldp substantially, simplifying things on one hand, and
extending the logic a bit on the other.
Specifically:
- Besides the sd_lldp object only one other object is maintained now,
sd_lldp_neighbor. It's used both as storage for literal LLDP packets, and for
maintainging info about peers in the database. Separation between packet, TLV
and chassis data is not maintained anymore. This should be a major
simplification.
- The sd-lldp API has been extended so that a couple of per-neighbor fields may
be queried directly, without iterating through the object. Other fields that
may appear multiple times, OTOH have to be iterated through.
- The maximum number of entries in the neighbor database is now configurable
during runtime.
- The generation of callbacks from sd_lldp objects is more restricted:
callbacks are only invoked when actual data changed.
- The TTL information is now hooked with a timer event, so that removals from
the neighbor database due to TTLs now result in a callback event.
- Querying LLDP neighbor database will now return a strictly ordered array, to
guarantee stability.
- A "capabilities" mask may now be configured, that selects what type of LLDP
neighbor data is collected. This may be used to restrict collection of LLDP
info about routers instead of all neighbors. This is now exposed via
networkd's LLDP= setting.
- sd-lldp's API to serialize the collected data to text files has been removed.
Instead, there's now an API to extract the raw binary data from LLDP neighbor
objects, as well as one to convert this raw binary data back to an LLDP
neighbor object. networkd will save this raw binary data to /run now, and the
client side can simply parse the information.
- support for parsing the more exotic TLVs has been removed, since we are not
using that. Instead there are now APIs to extract the raw data from TLVs.
Given how easy it is to parse the TLVs clients should do so now directly
instead of relying on our APIs for that.
- A lot of the APIs that parse out LLDP strings have been simplified so that
they actually return strings, instead of char arrays with a length. To deal
with possibly dangerous characters the strings are escaped if needed.
- APIs to extract and format the chassis and port IDs as strings has been
added.
- lldp.h has been simplified a lot. The enums are anonymous now, since they
were never used as enums, but simply as constants. Most definitions we don't
actually use ourselves have eben removed.
Let's just keep the few parts we actually need of it in the main sd_lldp
object, so that we can simplify things quite a bit.
While we are at it, remove ifname and mac fields which we make no use of
whatsoever.
There's really no point in maintaining a state, the state machine is trivial,
and we actually never look at the state anyway, we just keep updating it.
GLIB has recently started to officially support the gcc cleanup
attribute in its public API, hence let's do the same for our APIs.
With this patch we'll define an xyz_unrefp() call for each public
xyz_unref() call, to make it easy to use inside a
__attribute__((cleanup())) expression. Then, all code is ported over to
make use of this.
The new calls are also documented in the man pages, with examples how to
use them (well, I only added docs where the _unref() call itself already
had docs, and the examples, only cover sd_bus_unrefp() and
sd_event_unrefp()).
This also renames sd_lldp_free() to sd_lldp_unref(), since that's how we
tend to call our destructors these days.
Note that this defines no public macro that wraps gcc's attribute and
makes it easier to use. While I think it's our duty in the library to
make our stuff easy to use, I figure it's not our duty to make gcc's own
features easy to use on its own. Most likely, client code which wants to
make use of this should define its own:
#define _cleanup_(function) __attribute__((cleanup(function)))
Or similar, to make the gcc feature easier to use.
Making this logic public has the benefit that we can remove three header
files whose only purpose was to define these functions internally.
See #2008.
There are more than enough calls doing string manipulations to deserve
its own files, hence do something about it.
This patch also sorts the #include blocks of all files that needed to be
updated, according to the sorting suggestions from CODING_STYLE. Since
pretty much every file needs our string manipulation functions this
effectively means that most files have sorted #include blocks now.
Also touches a few unrelated include files.
Make sure all variable-length inputs are properly terminated or that
their length is encoded in some way. This avoids ambiguity of
adjacent inputs.
E.g., in case of a hash function taking two strings, compressing "ab"
followed by "c" is now distinct from "a" followed by "bc".
All our hash functions are based on siphash24(), factor out
siphash_init() and siphash24_finalize() and pass the siphash
state to the hash functions rather than the hash key.
This simplifies the hash functions, and in particular makes
composition simpler as calling siphash24_compress() repeatedly
on separate chunks of input has the same effect as first
concatenating the input and then calling siphash23_compress()
on the result.
LLDP TLVs of type 127 are used to carry organizationally specific
information and include additional fields to specify the OUI and
subtype.
Add support for parsing such fields and functions to access the most
common IEEE 802.1 specific TLVs.
Add a public function to get a list of current LLDP neighbours' TLV
packets. The function populates an array of pointers to the opaque
type sd_lldp_packet and returns the number of elements found. Callers
must take care of freeing the array and decreasing the refcount of
elements when done.
Currently, sd-lldp.h exports "UPDATE_INFO".. and defines it to a magic
constant '10'. This is completely bogus, so fix it to follow our coding
standards:
- Prefix exported symbols by SD_LLDP_*
- Define a separate event-enum for event types
- Translate internal state to external event-types
We should avoid using CLOCK_BOOTTIME directly unless we actually can
sensible distuingish it from CLOCK_MONOTONIC. CLOCK_BOOTTIME is only
fully feature on very recent Linux kernels, hence we should stick to a
fallback logic, which is already available in the
clock_boottime_or_monotonic() call.
Some places invoked fflush() directly with their own manual error
checking, let's unify all that by using fflush_and_check().
This also unifies the general error paths of fflush()+rename() file
writers.
This patch removes includes that are not used. The removals were found with
include-what-you-use which checks if any of the symbols from a header is
in use.
Fix a bunch of needless memzero() calls, a bunch of use-after-free
regarding _cleanup_free_ and drop unused variables.
Hint: Do NOT use _cleanup_free_ for temporary strappend() helpers that are
freed multiple times. All you safe is the last free() call, which is
really not worth the trouble resetting it to NULL all the time.
* (potentially) public headers must reside in src/systemd/ (not in
src/libsystemd*)
* some private (not prefixed with sd_) functions moved from sd-lldp.h to
lldp-internal.h
* introduce lldp-util.h for the cleanup macro, as these should not be public
* rename the cleanup macro, we always name them _cleanup_foo_, never
_cleanup_sd_foo_
* mark some function arguments as 'const'
This patch introduces LLDP support to networkd. it implements the
receiver side of the protocol.
The Link Layer Discovery Protocol (LLDP) is an industry-standard,
vendor-neutral method to allow networked devices to advertise
capabilities, identity, and other information onto a LAN. The Layer 2
protocol, detailed in IEEE 802.1AB-2005.LLDP allows network devices
that operate at the lower layers of a protocol stack (such as
Layer 2 bridges and switches) to learn some of the capabilities
and characteristics of LAN devices available to higher
layer protocols.
