#!/bin/sh
# -*- tcl -*-
# The next line is executed by /bin/sh, but not tcl \
exec tclsh "$0" ${1+"$@"}

package require Expect


# mkpasswd - make a password, if username given, set it.
# Author: Don Libes, NIST

# defaults
set length 9
set minnum 2
set minlower 2
set minupper 2
set minspecial 1
set verbose 0
set distribute 0

if {[file executable /bin/nispasswd]} {
	set defaultprog /bin/nispasswd
} elseif {[file executable /bin/yppasswd]} {
	set defaultprog /bin/yppasswd
} elseif {[file executable /bin/passwd]} {
	set defaultprog /bin/passwd
} else {
	set defaultprog passwd
}
set prog $defaultprog

while {[llength $argv]>0} {
	set flag [lindex $argv 0]
	switch -- $flag \
	"-l" {
		set length [lindex $argv 1]
		set argv [lrange $argv 2 end]
	} "-d" {
		set minnum [lindex $argv 1]
		set argv [lrange $argv 2 end]
	} "-c" {
		set minlower [lindex $argv 1]
		set argv [lrange $argv 2 end]
	} "-C" {
		set minupper [lindex $argv 1]
		set argv [lrange $argv 2 end]
	} "-s" {
		set minspecial [lindex $argv 1]
		set argv [lrange $argv 2 end]
	} "-v" {
		set verbose 1
		set argv [lrange $argv 1 end]
	} "-p" {
		set prog [lindex $argv 1]
		set argv [lrange $argv 2 end]
	} "-2" {
		set distribute 1
		set argv [lrange $argv 1 end]
	} default {
		set user [lindex $argv 0]
		set argv [lrange $argv 1 end]
		break
	}
}

if {[llength $argv]} {
	puts "usage: mkpasswd \[args] \[user]"
	puts "  where arguments are:"
	puts "    -l #      (length of password, default = $length)"
	puts "    -d #      (min # of digits, default = $minnum)"
	puts "    -c #      (min # of lowercase chars, default = $minlower)"
	puts "    -C #      (min # of uppercase chars, default = $minupper)"
	puts "    -s #      (min # of special chars, default = $minspecial)"
	puts "    -v        (verbose, show passwd interaction)"
	puts "    -p prog   (program to set password, default = $defaultprog)"
	exit 1
}

if {$minnum + $minlower + $minupper + $minspecial > $length} {
	puts "impossible to generate $length-character password\
		with $minnum numbers, $minlower lowercase letters,\
		$minupper uppercase letters and\
		$minspecial special characters."
	exit 1
}

# if there is any underspecification, use additional lowercase letters
set minlower [expr {$length - ($minnum + $minupper + $minspecial)}]

set lpass ""		;# password chars typed by left hand
set rpass ""		;# password chars typed by right hand

# insert char into password at a random position, thereby spreading
# the different kinds of characters throughout the password
proc insert {pvar char} {
    upvar $pvar p

    set p [linsert $p [rand [expr {(1+[llength $p])}]] $char]
}

proc rand {m} {
    set device /dev/urandom            ;# /dev/random can block
    set fileId [open $device r]
    binary scan [read $fileId 4] i1 number
    set clipped [expr $number % $m]
#    puts "number is $number"
#    puts "clipped is $clipped"
    close $fileId
    return $clipped
}

# choose left or right starting hand
set initially_left [set isleft [rand 2]]

# given a size, distribute between left and right hands
# taking into account where we left off
proc psplit {max lvar rvar} {
	upvar $lvar left $rvar right
	global isleft

	if {$isleft} {
		set right [expr $max/2]
		set left [expr $max-$right]
		set isleft [expr !($max%2)]
	} else {
		set left [expr $max/2]
		set right [expr $max-$left]
		set isleft [expr $max%2]
	}
}

if {$distribute} {
	set lkeys {q w e r t a s d f g z x c v b}
	set rkeys {y u i o p h j k l n m}
	set lnums {1 2 3 4 5 6}
	set rnums {7 8 9 0}
	set lspec {! @ # \$ %}
	set rspec {^ & * ( ) - = _ + [ ] "{" "}" \\ | ; : ' \" < > , . ? /}
} else {
	set lkeys {a b c d e f g h i j k l m n o p q r s t u v w x y z}
	set rkeys {a b c d e f g h i j k l m n o p q r s t u v w x y z}
	set lnums {0 1 2 3 4 5 6 7 8 9}
	set rnums {0 1 2 3 4 5 6 7 8 9}
	set lspec {! @ # \$ % ~ ^ & * ( ) - = _ + [ ] "{" "}" \\ | ; : ' \" < > , . ? /}
	set rspec {! @ # \$ % ~ ^ & * ( ) - = _ + [ ] "{" "}" \\ | ; : ' \" < > , . ? /}
}

set lkeys_length [llength $lkeys]
set rkeys_length [llength $rkeys]
set lnums_length [llength $lnums]
set rnums_length [llength $rnums]
set lspec_length [llength $lspec]
set rspec_length [llength $rspec]

psplit $minnum left right
for {set i 0} {$i<$left} {incr i} {
	insert lpass [lindex $lnums [rand $lnums_length]]
}
for {set i 0} {$i<$right} {incr i} {
	insert rpass [lindex $rnums [rand $rnums_length]]
}

psplit $minlower left right
for {set i 0} {$i<$left} {incr i} {
	insert lpass [lindex $lkeys [rand $lkeys_length]]
}
for {set i 0} {$i<$right} {incr i} {
	insert rpass [lindex $rkeys [rand $rkeys_length]]
}

psplit $minupper left right
for {set i 0} {$i<$left} {incr i} {
	insert lpass [string toupper [lindex $lkeys [rand $lkeys_length]]]
}
for {set i 0} {$i<$right} {incr i} {
	insert rpass [string toupper [lindex $rkeys [rand $rkeys_length]]]
}

psplit $minspecial left right
for {set i 0} {$i<$left} {incr i} {
	insert lpass [lindex $lspec [rand $lspec_length]]
}
for {set i 0} {$i<$right} {incr i} {
	insert rpass [lindex $rspec [rand $rspec_length]]
}

# merge results together
foreach l $lpass r $rpass {
    if {$initially_left} {
	append password $l $r
    } else {
	append password $r $l
    }
}

if {[info exists user]} {
	if {!$verbose} {
		log_user 0
	}

	spawn $prog $user
	expect {
		"assword*:" {
			# some systems say "Password (again):"
			send -- "$password\r"
			# "--" because of passwords beginning with dash
			exp_continue
		}
	}

	# if user isn't watching, check status
	if {!$verbose} {
		if {[lindex [wait] 3]} {
			puts -nonewline "$expect_out(buffer)"
			exit 1
		}
	}

        if {$verbose} {
	    puts -nonewline "password for $user is "
        }
}

puts "$password"