package main

import (
	"net"

	"github.com/coreos/go-systemd/activation"
)

func Listeners() ([]net.Listener, error) {
	files := activation.Files(false)
	listeners := make([]net.Listener, len(files))

	for i, f := range files {
		if pc, err := net.FileListener(f); err == nil {
			listeners[i] = pc
			f.Close()
		}
	}
	return listeners, nil
}

// PacketConns returns a slice containing a net.PacketConn for each matching socket type
// passed to this process.
//
// The order of the file descriptors is preserved in the returned slice.
// Nil values are used to fill any gaps. For example if systemd were to return file descriptors
// corresponding with "udp, tcp, udp", then the slice would contain {net.PacketConn, nil, net.PacketConn}
func PacketConns() ([]net.PacketConn, error) {
	files := activation.Files(false)
	conns := make([]net.PacketConn, len(files))

	for i, f := range files {
		if pc, err := net.FilePacketConn(f); err == nil {
			conns[i] = pc
			f.Close()
		}
	}
	return conns, nil
}