rdesktop-wrapper

#!/bin/bash
# rdesktop-wrapper
# This is a wrapper around rdesktop to handle ssh tunnels and a nickname index
#
# * You can specify a tunneled host as if it were in your local network
# * You can specify a host mapped in your ~/.rdesktop_table file
# * You can specify user accounts as part of the hostname, like user@host
# * Three new options:  --list-maps, --map-help, --completion-help
# * You can have entries in '~/.rdesktop_table' like:
##     #title   [user@]server[:port]    # default port=3389, user=$USER
##     hannibal localhost:13389
##     wipeout  cyn@wipeout
## * If you use alternate remote desktop ports in your ssh tunnels, you can
##   put a comment that says "rdesktop" above it.  Say "rdesktop next 4" to
##   indicate that the next four nonwhitespace lines are remote desktop tunnels.
##
## v0.6, (c) 2006-2012 < cyn.cc >
##########################################
### 0.1 Initial alpha-release; stable for ME, used more than daily.
###     Rather messy code, known bug with spaced arguments, needs rehaul,
###     and the inclusion of perl is silly (but more reliable than sed -r).
### 0.2 Better help
### 0.3 Fixed bug with more than one tunnel per host in ssh_config, zsh comp fix
### 0.4 Fixed nmap bug, there are likely more...
### 0.5 Now using bash for arrays so this works with quoted (spaced) parameters
### 0.6 Rewrote ssh_config parser, allow ssh_config comment hint
### You can debug this by setting $DEBUG to "true" before running this script
##########################################
### TODO
###   * Rewrite the whole thing in perl (lots of work; it works fine as is...)
###   * Reconsider blanket exclusion of wildcard hosts in sshd_config
###   * Test to see if connected to a host before okaying its ssh tunnels
###   * Get somebody to say they use and like this script
##########################################

help() { sed -e '/^## /!d' -e 's///' "`which $0 || echo $0`"; }

completion_help() { echo \
'For hosts tab completion in zsh, add these lines to your .zshrc:
 function _get_rdesktops() {
  reply=(`
    rdesktop --list-maps 2>/dev/null |sed -r "s/^port.*maps ([^:]+):.*ough/\1/"
    _get_hosts
  `)
 }
 compctl -K _get_rdesktops rdesktop'
}

lookup_table=~/.rdesktop_table
[ -n "$DEBUG" ] && debug() { echo "$*" >&2; } || debug() { true; }

# get list of maps from lookup table file
get_lookups() {
  [ -s "$lookup_table" ] && \
    perl -ne 's/\W*#.*//; s/^(\S+)\s+/$1   \t/s; print if /./;' <"$lookup_table"
}

# get list of ssh tunnels for port 3389 (and my alt, 33389) from ~/.ssh/config
get_tunnels() {
  perl -e '
    sub report_tunnel {
      my ($forward, $target, $host) = @_;
      while ( length($forward) < 8 ) { $forward .= " "; }
      $target =~ s/:3389$//;
      while ( length($target) < 30 ) { $target .= " "; }
      print "port $forward maps $target through $host\n";
    }

    open (SSH_CONFIG, "< $ENV{HOME}/.ssh/config") or die $!;
    while (<SSH_CONFIG>) {
      chomp;
      next unless /Host\s+([^*]+)$/;
      my $host = $1;
      do {
        $_ = <SSH_CONFIG>;
        last if ! defined;
        if (/#.*\brdesktop\s*(?:(?:next\s*)?(\d+\b))?/) {
          my $n = 1;
          $n = $1 if ( defined($1) && $1 > 1 );
          for (1; $n > 0; $n--) {
            $_ = <SSH_CONFIG>;
            last if ! defined;
            s/#.*$//;
            $_ = <SSH_CONFIG> if (/^\s*$/);
            last if ! defined || ! /LocalForward\s+((?:\S*:)?\d+)\s+(\S+)/;
            report_tunnel ($1, $2, $host);
          }
        }
        if (/LocalForward(?:\s+|\s*=\s*)((?:\S*:)?\d+)\s+(\S+:3?3389\d*)\b/) {
          report_tunnel ($1, $2, $host);
        }
      } while (! /Host\s/);
    }
    close (SSH_CONFIG);
  '
}

# just show the list and exit
case x$*${args[*]} in
  *-completion* ) completion_help; exit 0;;
  *--map-help*  ) help; exit 0;;
  *--????-maps* ) get_lookups; get_tunnels; exit 0;;
  *--tunneltest*) get_tunnels; exit 0;;
  *-h*          ) help=true ;;
esac

# list order in path, like 'which -a' w/out aliases
scanpath() {
  for d in `echo $PATH |sed 's/:/ /g'`; do ls "$d/$1" 2>/dev/null; done
}

debug "finding 'rdesktop' in path"
[ -n "`echo $0 |grep /`" ] && apath="$0" && aline=1 || aline=2
run=`scanpath rdesktop |grep -v "^$apath$" |sed "${aline}q;d"`
[ -z "$run" ] && echo "No rdesktop executable found in path" <&2 && exit 2
debug "we will use the second hit in the path, which is '$run'"

if [ -n "$help" ]; then
  help; echo ''; $run -h; exit 0
fi

# throw all but last argument into $args array
while [ -n "$2" ]; do
  # can't have -g and -A, so nix the -g (it doesn't make any sense anyway)
  echo "x$*"|grep ".-A" >/dev/null && [ "$1" != "${1#-g}" ] && shift && continue
  args[${i:-1}]="$1"
  i=$(($i+1))
  shift
done

rd=`echo $1 |sed 's/^.*@//'`
user=`echo $1 |sed -e "/@/!d" -e "s/@$rd$//" -e "s/^/-u /"`
#user=`echo $1 |perl -ne 'if /\@/ { s/^([^@]+)\@.*$/-u $1/; print; }'`
local=`echo $1 |perl -ne 'print if /\b(127\.0\.[0-9.]+|localhost.*)/'`
[ -n "$local" ] && [ -z "`echo $local|grep :`" ] && local="$local:3389"

# try lookup table
if [ -s "$lookup_table" ]; then
  table=`get_lookups |perl -ne "print if /^\S*$rd\b/"`
  debug "lookup table has data, host '$rd' best match is '$table'"
fi

# try ssh config (but not if we are local!)
if [ -z "$table" ]; then
  debug "no match on table lookup, trying to search for '$rd' in ssh conf"

  if [ -n "$local" ]; then
    port=`echo $local|sed 's/^.*://'` # we already set the default port above
  else
    port=`get_tunnels |perl -ne \
      "if (/\b$rd\b/) "'{ s/^\S+\s(\d+).*$/$1/; print; }'`
  fi

  [ -n "$port" ] && title=`get_tunnels |perl -ne \
  "if (/port $port\\b.*\\b$rd\\b/)
    { s/^.*maps\s//; s/[\t ]+/-/g; s/-$//; s/:3?3389//g; print; }"`

  [ -n "$title" ] && table="$title localhost:$port" \
    && debug "found ssh-tunnel titled '$title' matching '$rd'" \
    || debug "no ssh tunnel matches query '$rd'"

fi

# try the host literally
if [ -z "$table" ]; then
  debug "no match on ssh conf, testing if '$rd' is a literal host or host:port"
  host=`echo $rd |sed "s/:.*$//"`
  port=`echo $rd |sed "s/$host:*//"`
  [ -z "$port" ] && port=3389
  debug "  testing $host:$port"

  # nmap with timeouts (version 4+) is awesome!  ... why doens't 2s work!?
  my_nmap() {
    $tsocks nmap -P0 -sT -T4 --host-timeout 1501 -p"$1" "$2" 2>&1 |grep "$3";
  }
  # fall back to telnet if nmap doesn't report on the requested port
  if my_nmap 25 localhost '^25/' >/dev/null
    then
      p=`my_nmap $port $host "^$port.*open"`
      if [ -z "$p" ]; then
        tsocks=tsocks && p=`my_nmap $port $host "^$port.*open"`
        [ -z "$p" ] && unset tsocks || echo "works with tsocks"
      fi
      [ -n "$p" ] && go=true
    else echo X |telnet -e X "$1" $2 >/dev/null 2>&1 && go=true
  fi
  [ -n "$go" ] && table="$rd $host:$port" && debug "literal works, using '$rd'"
fi

if [ -z "$table" ]; then
  debug "still nothing ... is '$rd' an argument?"
  case $rd in
    # no host, let real rdesktop give errors/help
    -*) $run "${args[@]}" $rd; exit $? ;;
  esac

  debug "not an argument ... spit out error message"
  echo "`basename $0`: could not connect to \`$rd'"
  [ -s "$lookup_table" ] && match=" match in the" \
                         || map_help="- see `basename $0` --map-help"
  echo "
Found no$match lookup table at \`$lookup_table' $map_help
Found no match in your ssh config for a tunneled rdesktop port (3389)
Server \`$host' does not appear to accept TCP connections on port \`$port'
Trying ping..."
  ping -n -c3 "$host" 2>/dev/null

exit 2
fi

if [[ -z "$tsocks" && "$table" =~ (10\.0\.101\.[0-9]+|\.bf)(:[0-9]+)?$ ]]; then
  tsocks=tsocks
  debug "tsocks enabled for table '$table'"
fi

[ -z "$user" ] && [ -n "`echo $table|grep '@'`" ] && \
  user=`echo $table |perl -pne 's/^.*\b([^\@]+)\@.*$/-u $1/'` # extract username
[ -n "$user" ] && debug "a username will be specified with '$user'"

table=`echo $table |perl -pne 's/\s[^\@]+\@/ /'` # remove username form table

dbrun="$tsocks $run ${args[@]} $user -T $table"
#debug "running '$dbrun'..."
if debug is-on 2>&1 |grep is-on >/dev/null; then
  debug "running:  '$run \\"
  for a in "${args[@]}"; do debug "    \"$a\" \\"; done
  debug "    $user \\"
  debug "    -T $table"
fi
$tsocks $run "${args[@]}" $user -T $table
RETVAL=$?
[ $RETVAL != 0 ] && debug "command '$dbrun' failed with exit code '$RETVAL'" >&2
exit $RETVAL