#!/bin/zsh

coproc  ( : | openssl s_client -connect $1:443 2>/dev/null| awk '/BEGIN CERTIFICATE/,/END CERTIFICATE/' | openssl x509 -in - -noout -startdate -enddate -ext subjectAltName | sed '/X509v3 Subject Alternative Name/ {n ; s/DNS://g ; s/, /\n    /g;}' )

exec 3> >(LC_ALL=C sort)

sort=0
while read -p line
do
    if [[ $line = notBefore=* ]]
    then

    if (( sort == 1 ))
    then
        echo "   $line" >&3
    else
        [[ $line = 'X509v3 Subject Alternative Name:' ]] && sort=1
        echo $line
    fi
done