functions

#!/bin/bash

# proxy_port(container, service, from, to)

function add_proxy_port {

  lxc config device add ${1} ${2} proxy \
        listen=tcp:${3} \
        connect=tcp:${4} \
        nat=true

  return $?
}

# Call with a hostname to get an IP address back
function dns_check_A {

    local IP="UNRESOLVED"

    if [ -x /usr/bin/host ]; then
        IP=$(host -4 ${1} | grep ${1} | cut -d' ' -f 4)
    else
        IP=$(systemd-resolve ${1} -4 | grep ${1} | cut -d' ' -f 2)
    fi    

    echo  ${IP}
}

# Call with a domain, get the highest priority MX host.
function dns_check_MX {

    local MX="UNRESOLVED"

    if [ -x /usr/bin/host ]; then
        MX=$(host -t mx ${1}|cut -d' ' -f 6-|sort -n|head -1|cut -d' ' -f 2)
    else
        MX=$(systemd-resolve -t mx ${1}|grep ${1}|cut -d' ' -f 4-|sort -n|head -1|cut -d' ' -f 2)
    fi    

    # Return the response with any trailing '.' removed.
    echo  ${MX%.}
}

# Call with an IP address, and get the PTR host back
function dns_check_PTR {

    local PTR="UNRESOLVED"

    if [ -x /usr/bin/host ]; then
        PTR=$(host ${1}|cut -d' ' -f 5)
    else
        PTR=$(systemd-resolve ${1}|grep 'link:'|cut -d' ' -f 2)
    fi

    # Return the response with any trailing '.' removed.
    echo  ${PTR%.}
}