Where is dhcpd's syslog message formats documented?
Why parse the log files? What you really want to read is the leases file. That's where all the useful information is, and its format is very machine-readable.
I experienced the same agony just like you. I seached on Google for several hours but no result. Finally, I found in the "man in.dhcpd", at the part of "-l syslog_local_facility", there is a format description for the log file.