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#!/bin/sh
# Copyright 2023 Helmut Grohne <helmut@subdivi.de>
# SPDX-License-Identifier: MIT
: <<'POD2MAN'
=head1 NAME
debvm-waitssh - Wait for a ssh server to be reachable
=head1 SYNOPSIS
B<debvm-waitssh> [B<-q>] [B<-t> I<timeout>] [I<hostname>:]I<port>
=head1 DESCRIPTION
B<debvm-waitssh> can be used to wait for a virtual machine with exposed ssh port to be reachable on that port.
If no hostname is given, B<127.0.0.1> is assumed. No authentication is attempted by B<debvm-waitssh>, so neither
a username nor a key have to be supplied.
=head1 OPTIONS
=over 8
=item B<-t> I<timeout>, B<--timeout>=I<timeout>
Set the maximum duration for waiting in seconds.
Defaults to one minute.
=item B<-q>, B<--quiet>
Be quiet. Output nothing on standard error, not even error messages.
=back
=head1 EXIT VALUES
=over 8
=item B<0>
The server is reachable.
=item B<1>
A timeout was reached before the server answered.
=item B<2>
Usage error.
=back
=head1 SEE ALSO
debvm-run(1)
=cut
POD2MAN
set -u
TOTALTIMEOUT=60
SCANTIMEOUT=10
SCANDELAY=1
VERBOSITY=1
nth_arg() {
shift "$1"
printf "%s" "$1"
}
die() {
echo "$*" >&2
exit 2
}
usage() {
die "usage: $0 [-q] [-t <timeout>] [<host>:]<port>"
}
usage_error() {
echo "error: $*" >&2
usage
}
opt_help() {
# shellcheck disable=SC2317 # not dead, called as "opt_$OPTARG"
usage
}
opt_quiet() {
VERBOSITY=0
}
opt_timeout() {
TOTALTIMEOUT=$1
}
while getopts :qt:-: OPTCHAR; do
case "$OPTCHAR" in
q) opt_quiet ;;
t) opt_timeout "$OPTARG" ;;
-)
case "$OPTARG" in
help|quiet)
"opt_$OPTARG"
;;
timeout)
test "$OPTIND" -gt "$#" && usage_error "missing argument for --$OPTARG"
"opt_$OPTARG" "$(nth_arg "$OPTIND" "$@")"
OPTIND=$((OPTIND+1))
;;
timeout=)
"opt_${OPTARG%%=*}" "${OPTARG#*=}"
;;
*)
usage_error "unrecognized option --$OPTARG"
;;
esac
;;
:)
usage_error "missing argument for -$OPTARG"
;;
'?')
usage_error "unrecognized option -$OPTARG"
;;
*)
die "internal error while parsing command options, please report a bug"
;;
esac
done
shift "$((OPTIND - 1))"
test "$#" = 1 || usage
case "$1" in
"")
usage
;;
*:*)
HOST=${1%:*}
PORT=${1##*:}
;;
*)
HOST=127.0.0.1
PORT=$1
;;
esac
case "$HOST" in *@*)
if [ "$VERBOSITY" -ge 1 ]; then
echo "$0: hostname '$HOST' must not contain the '@' character. No username is required." >&2
fi
exit 1
;;
esac
# Guard against strings containing anything but digits, strings starting with
# zero and empty strings as the port number.
#
# We cannot use [!0-9] because that matches on any character (or possibly
# multi-character collation element) that sorts in between 0 and 9.
case "$PORT" in *[!0123456789]*|0?*|""|??????*)
if [ "$VERBOSITY" -ge 1 ]; then
echo "$0: port '$PORT' is not a positive integer between 1 and 99999" >&2
fi
exit 1
;;
esac
now=$(date +%s)
deadline=$((now + TOTALTIMEOUT))
while test "$now" -lt "$deadline"; do
start=$now
ssh-keyscan -t rsa -T "$SCANTIMEOUT" -p "$PORT" "$HOST" >/dev/null 2>&1 && exit 0
now=$(date +%s)
if test "$((now - start))" -lt "$SCANTIMEOUT"; then
sleep "$SCANDELAY"
now=$(date +%s)
fi
done
if [ "$VERBOSITY" -ge 1 ]; then
echo "$0: timeout reached trying to contact $HOST:$PORT after waiting $TOTALTIMEOUT seconds." >&2
fi
exit 1
|
