Casting necessary for the case size_t is smaller than int.
Casting is not needed, but is good practice

Always cast negative values in unsigned types since in some cases bugs
might be hidden. See:

https://www.securecoding.cert.org/confluence/display/seccode/INT18-C.+Evaluate+integer+expressions+in+a+larger+size+before+comparing+or+assigning+to+that+size#INT18-C.Evaluateintegerexpressionsinalargersizebeforecomparingorassigningtothatsize-NoncompliantCodeExample%28size_t%29
Turn on reverse DNS lookups when there are admit_hostname rules.
Rename variable masking identically named variable of different type.
Clarification comment.
Acceptance tests for admit_hostnames and deny_hostnames.
Merge pull request #1932 from jimis/admit_hostnames_should_reverse_lookup

Admit hostnames should reverse lookup