newtypedecl 0.0.1

declarative newtype macro
Documentation 
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# -*- mode: sh; sh-shell: bash -*-
# vim: set ft=bash:
# shellcheck shell=bash

### Low level networking functions

function net_canon_hostname ## <host> - Canonalize 'host' to a FQDN.
{
    getent hosts "$1" | awk '{print $2}'
}

function net_host_reachable ## <host> [timeout [tries]] - checks if 'host' is reachable.
{
    ## The check uses ICMP ping to check for reachability.
    ## The [timeout] defaults to 10 seconds and [tries] defaults to 3.
    local i
    for (( i=0; i<${3:-1}; ++i)); do
        ping -q -W"${2:-10}" -c1 "$1" >/dev/null && return 0
    done
}

function net_wakeonlan ## <host> - Sends a wake-on-lan signal.
{
    ## 'host' is a hostname. '/etc/ethers' must have entries to resolve hosts. See
    ## 'contrib/update-ethers.sh' for automatically discover and maintain '/etc/ethers'. Waits
    ## for the host to become reachable. Fails when it is not reachable.
    is_command_installed wakeonlan || {
        error "wakeonlan is not installed"
        return 1
    }
    local host
    host="$(net_canon_hostname "$1")"
    if [[ -n "$host" ]]; then
        wakeonlan "$host"
        net_host_reachable "$host" 10 10 && return 0
    fi
    error "host $1 is not reachable"
    return 1
}