client.sh

#!/usr/bin/env bash

if [[ $# != 2 ]]; then
    echo "Usage:"
    echo "      $0 hostname message"
    exit 1
fi

StartDate=$(date -u +"%s.%N")

# create message, remove padding
stripped_b32=$(echo "$2" | base32 | tr -d =)
# create domain
crafted_domain="${stripped_b32}.$1"
# make the DNS query and retrieve the answers
answer=$(dig @$1 "$crafted_domain" TXT)
# decode answer
message=$(echo "$answer" | grep -A 1 ";; ANSWER SECTION:" | tail -n 1 | grep -E -o "\".+\"" | cut -c 2- | rev | cut -c 2- | rev)
length=$((4 - $(echo -n "$message" | wc -c) % 4))
# add padding back accordingly
case "$length" in
"1")
    message="${message}="
    ;;
"2")
    message="${message}=="
    ;;
"3")
    message="${message}==="
    ;;
*)
    ;;
esac
# decode
decoded=$(echo "$message" | base64 -d)

FinalDate=$(date -u +"%s.%N")
elapsed=$(date -u -d "0 $FinalDate sec - $StartDate sec" +"%S.%N")
echo "Received in $elapsed seconds"
echo "$decoded" | tr "|" "\n"