Let's make sure the inline functions for retrieving TLV data actually carry TLV
in the name, so that we don#t assume they retrieve the whole, raw packet data.
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.h contains definitions of LLDP types, subtypes and capabilities which
should be exposed in public headers. Get rid of the file and move those
definitions to sd-lldp.h with the SD_ prefix.
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.
