[profile] / bin / hacks / ssh

#! /bin/bash
###
### SSH wrapper to spawn separate SSH master connections on demand
###
### (c) 2010 Mark Wooding
###

###----- Licensing notice ---------------------------------------------------
###
### This program is free software; you can redistribute it and/or modify
### it under the terms of the GNU General Public License as published by
### the Free Software Foundation; either version 2 of the License, or
### (at your option) any later version.
###
### This program is distributed in the hope that it will be useful,
### but WITHOUT ANY WARRANTY; without even the implied warranty of
### MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
### GNU General Public License for more details.
###
### You should have received a copy of the GNU General Public License
### along with this program; if not, write to the Free Software Foundation,
### Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.

###--------------------------------------------------------------------------
### Configuration.

: ${REAL_SSH=/usr/bin/ssh}
: ${SSH_HOME=$(unset HOME; bash -c 'echo ~/.ssh')}
: ${SSH_LOGDIR=$SSH_HOME/log-$(hostname)}

###--------------------------------------------------------------------------
### Parse the command line and dredge out information.

## This is a reasonable approximation to SSH's command-line argument parser.
unset host login
mode=m
declare -a opts masteropts
while :; do
  case "$1,$#" in

    ## Nothing left.  We're done.
    ,0)
      break
      ;;

    ## A command line option group.  Parse it and work out what's going on.
    -*)
      opt=$1
      opts=("${opts[@]}" "$opt")
      while :; do

	## Strip off the first character, because it's the one we dealt with
	## last time.
	opt=${opt#?}
	o=$opt

	## Phase 1: identify the option and whether it needs an argument.
	unset arg
	case "$o" in

	  ## Empty group.  We're done.
	  "")
	    break
	    ;;

	  ## Options with arguments.
	  [bcDeFiLlmOopRSw]*)
	    case "$#,$o" in

	      ## You're going to lose because there's no argument.  But we'll
	      ## let SSH deal with that.
	      1,?)
		arg=
		;;

	      ## There's an argument cuddled on to the end of the option.  It
	      ## will have been committed to the `opts' array as part of the
	      ## option group.
	      *,??*)
		arg=${opt#?}
		opt=
		;;

	      ## Nope.  There's an argument in the next word.  Grab it and
	      ## commit it.
	      *)
		arg="$2"
		opts=("${opts[@]}" "$arg")
		shift
		;;
	    esac
	    ;;

	  ## Anything else.  Let it go even if it's not valid: SSH will moan
	  ## if it wants.  Note that `--' is ignored by SSH, but this isn't
	  ## documented; in particular, `--' is /not/ a POSIX end-of-options
	  ## marker, so we don't try to handle it specially here either.
	  *)
	    ;;
	esac

	## Phase two.  Figure out whether what this means for us.
	case "$mode,$o" in

	  ## `-O foo' and `-S foo' mean that the caller wants to take
	  ## control of the multiplexing process.
	  ?,[MOS]*)
	    mode=p
	    ;;

	  ## Catch the login name if there is one.  Make sure the master
	  ## knows it.
	  ?,l*)
	    masteropts=("${masteropts[@]}" "-l$arg")
	    login=$arg
	    ;;

	  ## Catch the port number.  We want this for building the logfile
	  ## name.
	  ?,p*)
	    masteropts=("${masteropts[@]}" "-p$arg")
	    port=$arg
	    ;;

	  ## These options are interesting to the master connection.
	  m,[aADLlRSwxXv46]*)
	    masteropts=("${masteropts[@]}" "-${o:0:1}$arg")
	    ;;

	  ## SSH options on the command line merit special attention.  Pass
	  ## them onto the master, if necessary.
	  ?,o*)
	    masteropts=("${masteropts[@]}" "${opt:0:1}$arg")
	    case "$mode,$arg" in

	      ## User wants to control the process.  Let him.
	      ?,ControlMaster=* | ?,ControlPath=*)
		mode=p
		;;

	    esac
	    ;;
	esac
      done
      ;;

    ## A bare word.  Maybe it's the hostname, or the start of the command.
    *)
      case ${host-t}${host+nil} in
	t) host=$1 ;;
	*) break ;;
      esac
      ;;
  esac
  shift
done

###--------------------------------------------------------------------------
### Now to actually do the job.

## If there's no host, pass straight through.  We can't do anything useful
## anyway.
case ${host+t} in
  t) ;;
  *) mode=p ;;
esac

## Actually do something useful.
case "$mode" in
  p)
    exec "$REAL_SSH" "${opts[@]}" ${host+"$host"} "$@"
    ;;
  m)
    mkdir -p -m700 "$SSH_LOGDIR"
    logfile=$SSH_LOGDIR/${login+"$login@"}"$host"${port+":$port"}.log
    if ! "$REAL_SSH" -Ocheck \
      ${port+-p$port} ${login+"$login@"}"$host" \
      >/dev/null 2>&1
    then
      "$REAL_SSH" -MNf "${masteropts[@]}" "$host" \
	</dev/null >/dev/null 2>$logfile
    fi
    exec "$REAL_SSH" ${opts[@]} "$host" "$@"
    ;;
esac

###----- That's all, folks --------------------------------------------------
Commit	Line	Data
4d7d040b MW	1	#! /bin/bash
	2	###
	3	### SSH wrapper to spawn separate SSH master connections on demand
	4	###
	5	### (c) 2010 Mark Wooding
	6	###
	7
	8	###----- Licensing notice ---------------------------------------------------
	9	###
	10	### This program is free software; you can redistribute it and/or modify
	11	### it under the terms of the GNU General Public License as published by
	12	### the Free Software Foundation; either version 2 of the License, or
	13	### (at your option) any later version.
	14	###
	15	### This program is distributed in the hope that it will be useful,
	16	### but WITHOUT ANY WARRANTY; without even the implied warranty of
	17	### MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	18	### GNU General Public License for more details.
	19	###
	20	### You should have received a copy of the GNU General Public License
	21	### along with this program; if not, write to the Free Software Foundation,
	22	### Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
	23
	24	###--------------------------------------------------------------------------
	25	### Configuration.
	26
	27	: ${REAL_SSH=/usr/bin/ssh}
e41b452f MW	28	: ${SSH_HOME=$(unset HOME; bash -c 'echo ~/.ssh')}
e41b452f MW	29	: ${SSH_LOGDIR=$SSH_HOME/log-$(hostname)}
4d7d040b MW	30
	31	###--------------------------------------------------------------------------
	32	### Parse the command line and dredge out information.
	33
	34	## This is a reasonable approximation to SSH's command-line argument parser.
	35	unset host login
	36	mode=m
	37	declare -a opts masteropts
	38	while :; do
	39	case "$1,$#" in
	40
	41	## Nothing left. We're done.
	42	,0)
	43	break
	44	;;
	45
	46	## A command line option group. Parse it and work out what's going on.
	47	-*)
	48	opt=$1
	49	opts=("${opts[@]}" "$opt")
	50	while :; do
	51
	52	## Strip off the first character, because it's the one we dealt with
	53	## last time.
	54	opt=${opt#?}
	55	o=$opt
	56
	57	## Phase 1: identify the option and whether it needs an argument.
	58	unset arg
	59	case "$o" in
	60
	61	## Empty group. We're done.
	62	"")
	63	break
	64	;;
	65
	66	## Options with arguments.
	67	[bcDeFiLlmOopRSw]*)
	68	case "$#,$o" in
	69
	70	## You're going to lose because there's no argument. But we'll
	71	## let SSH deal with that.
	72	1,?)
	73	arg=
	74	;;
	75
	76	## There's an argument cuddled on to the end of the option. It
	77	## will have been committed to the `opts' array as part of the
	78	## option group.
	79	,??)
	80	arg=${opt#?}
	81	opt=
	82	;;
	83
	84	## Nope. There's an argument in the next word. Grab it and
	85	## commit it.
	86	*)
	87	arg="$2"
	88	opts=("${opts[@]}" "$arg")
	89	shift
	90	;;
	91	esac
	92	;;
	93
94	## Anything else. Let it go even if it's not valid: SSH will moan
95	## if it wants. Note that `--' is ignored by SSH, but this isn't
96	## documented; in particular, `--' is /not/ a POSIX end-of-options
97	## marker, so we don't try to handle it specially here either.
98	*)
99	;;
100	esac
101
102	## Phase two. Figure out whether what this means for us.
103	case "$mode,$o" in
104
105	## `-O foo' and `-S foo' mean that the caller wants to take
106	## control of the multiplexing process.
107	?,[MOS]*)
108	mode=p
109	;;
110
111	## Catch the login name if there is one. Make sure the master
112	## knows it.
113	?,l*)
114	masteropts=("${masteropts[@]}" "-l$arg")
115	login=$arg
116	;;
117
e41b452f MW	118	## Catch the port number. We want this for building the logfile
	119	## name.
	120	?,p*)
	121	masteropts=("${masteropts[@]}" "-p$arg")
	122	port=$arg
	123	;;
	124
4d7d040b	125	## These options are interesting to the master connection.
ef864444	126	m,[aADLlRSwxXv46]*)
4d7d040b MW	127	masteropts=("${masteropts[@]}" "-${o:0:1}$arg")
	128	;;
	129
	130	## SSH options on the command line merit special attention. Pass
	131	## them onto the master, if necessary.
	132	?,o*)
	133	masteropts=("${masteropts[@]}" "${opt:0:1}$arg")
	134	case "$mode,$arg" in
	135
	136	## User wants to control the process. Let him.
	137	?,ControlMaster=* \| ?,ControlPath=*)
	138	mode=p
	139	;;
	140
	141	esac
	142	;;
	143	esac
	144	done
	145	;;
	146
	147	## A bare word. Maybe it's the hostname, or the start of the command.
	148	*)
af844120	149	case ${host-t}${host+nil} in
4d7d040b MW	150	t) host=$1 ;;
	151	*) break ;;
	152	esac
	153	;;
	154	esac
	155	shift
	156	done
	157
	158	###--------------------------------------------------------------------------
	159	### Now to actually do the job.
	160
	161	## If there's no host, pass straight through. We can't do anything useful
	162	## anyway.
	163	case ${host+t} in
	164	t) ;;
	165	*) mode=p ;;
	166	esac
	167
	168	## Actually do something useful.
	169	case "$mode" in
	170	p)
	171	exec "$REAL_SSH" "${opts[@]}" ${host+"$host"} "$@"
	172	;;
	173	m)
e41b452f MW	174	mkdir -p -m700 "$SSH_LOGDIR"
e41b452f MW	175	logfile=$SSH_LOGDIR/${login+"$login@"}"$host"${port+":$port"}.log
cfed2fe1 MW	176	if ! "$REAL_SSH" -Ocheck \
cfed2fe1 MW	177	${port+-p$port} ${login+"$login@"}"$host" \
afda7f51 MW	178	>/dev/null 2>&1
afda7f51 MW	179	then
e41b452f MW	180	"$REAL_SSH" -MNf "${masteropts[@]}" "$host" \
e41b452f MW	181	</dev/null >/dev/null 2>$logfile
4d7d040b MW	182	fi
	183	exec "$REAL_SSH" ${opts[@]} "$host" "$@"
	184	;;
	185	esac
	186
	187	###----- That's all, folks --------------------------------------------------