What were you trying to do that didn't work?

While doing range checking of lldp configuration properties using lldpcli I found the software silently accepts invalid values for tx-hold and tx-interval.

Per the IEEE 802.1AB standard, tx-hold should be between 1 and 100 (Clause 9.2.5.6) and tx-interval should be between 1 and 3600 (Clause 9.2.5.7).

These values are multiplied to determine a "time to live" which is limited to the range 0-65535, with too-large numbers essentially resulting a modulo to determine the TTL (e.g: tx-interval of 3600 and tx-hold of 20 result in a TTL of 6464).

Trying to set either value to 0 is ignored with no error, although since it would result in a TTL of 0 which means "forget me" (Clause 8.5.4) it doesn't actually break anything.

While no error messages are returned, tx-hold can be configured with values up to 1569325056 and tx-interval is taking values up to 1661993.

Please provide the package NVR for which bug is seen:

lldpd-1.0.18-3.el9.x86_64

How reproducible:

Always

Steps to reproduce

1. With lldpd running , use lldpcli to set tx-hold and tx-interval to values which violate the standard
2. Observe: no errors are returned
3. Set tx-hold and tx-interval to values which will result in a TTL larger than 65535
4. Observe: TTL is set to (tx-interval & tx-hold) % 65536.

Expected results

There should be some validation while setting tx-interval and tx-hold to comply with the standard

Actual results

There is no validation or error messaging when configuring lldpd with illegal values.