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.
Let's add some minimalistic LLDP sender support. The idea is that this is
either on or off, and all fields determined automatically rather than
configured explicitly.
Being on the link-layer LLDP is nothing we should turn on only when there's a
link beat. Instead, turn it on, whenever the iface is UP regardless if there's
a link beat or not. This closes the race between a link beat being available
and us subscribing to LLDP as a result.
After all, if we know that an interface exists but networkd did not store any
info about it, then it's definitely unmanaged by it.
(Note that we add this fix-up to networkctl, and not to sd-network, simply
because a missing file might also be result of the interface not existing.)
This way "networkctl status" becomes a bit more useful by default, as router
information is just visible, without any further configuration.
LLDP reception is fully passive and relatively low simple and low traffic,
hence this should be safe to enable by default.
This adds a small and useful field to the "systemctl status" output: the
router(s) the interface is connected to as reported via LLDP. Example output:
● 2: enp0s25
Link File: /usr/lib/systemd/network/99-default.link
Type: ether
State: degraded (configured)
Path: pci-0000:00:19.0
Driver: e1000e
Connected To: GS1900 on port 2 (foobar)
i.e. the last line is the relevant one.
Let's always use the same calls to acquire interface data. Specifically port
"networkctl status" to use acquire_link_info_strv() and acquire_link_info_all()
like the other calls.
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.
Also downgrade non-fatal warnings to log_warning.
Previously rule_add_key() would check the output array and log a cryptic
error and return -1. Most of the time the return value was ignored. This
does not seems right, because the buffer can overflow with enough rules.
It would also check if we have enough space for the *next* rule, even if
there might be not next rule, i.e. off-by-one.
Replace this with a check that we have enough space for a next rule before
we start parsing.
Normally using macros to alter flow is not allowed, but in this case I
think it is worth it, because it allows lots of boilerplate code to be
removed and hides repeated boring parameters, making function logic much
easier to follow.
If the attribute wasn't found, the last filename looked at was returned in
the input/output argument. This just seems bad style.
The return value was ignored, so change function to return void.
Usually, we place the #pragma once before the copyright blurb in header files,
but in a few cases we didn't. Move those around, so that we do the same thing
everywhere.
