Updates #3107. Updates #3127. Squashed commit of the following: commit ad64472566ecd1b0864212cd2644a57439aceb85 Author: Ainar Garipov <A.Garipov@AdGuard.COM> Date: Thu May 13 14:45:21 2021 +0300 dhcpd: refactor validations
Updates #3107. Updates #3127. Squashed commit of the following: commit ad64472566ecd1b0864212cd2644a57439aceb85 Author: Ainar Garipov <A.Garipov@AdGuard.COM> Date: Thu May 13 14:45:21 2021 +0300 dhcpd: refactor validations