#
# This scripts changes a password on the local system or a remote host.
# Connections to the remote (this can also be localhost) are made by ssh, rsh,
# telnet or rlogin.

# @author  Gaudenz Steinlin <gaudenz@soziologie.ch>

# For sudo support alter sudoers (using visudo) so that it contains the
# following information (replace 'apache' if your webserver runs under another
# user):
# -----
# # Needed for Horde's passwd module
# Runas_Alias     REGULARUSERS = ALL, !root
# apache ALL=(REGULARUSERS) NOPASSWD:/usr/bin/passwd
# -----

# @stdin              The username, oldpassword, newpassword (in this order)
#                     will be taken from stdin
# @param -prompt      regexp for the shell prompt
# @param -password    regexp password prompt
# @param -oldpassword regexp for the old password
# @param -newpassword regexp for the new password
# @param -verify      regexp for verifying the password
# @param -success     regexp for success changing the password
# @param -login       regexp for the telnet prompt for the loginname
# @param -host        hostname to be connected
# @param -timeout     timeout for each step
# @param -log         file for writing error messages
# @param -output      file for logging the output
# @param -telnet      use telnet
# @param -ssh         use ssh (default)
# @param -rlogin      use rlogin
# @param -slogin      use slogin
# @param -sudo        use sudo
# @param -program     command for changing passwords
#
# @return             0 on success, 1 on failure
#


# default values
set host               "localhost"
set login              "ssh"
set program            "passwd"
set prompt_string      "(%|\\\$|>)"
set fingerprint_string "The authenticity of host.* can't be established.*\n(RSA|ECDSA) key fingerprint is.*\nAre you sure you want to continue connecting.*"
set password_string    "(P|p)assword.*"
set oldpassword_string "((O|o)ld|login|\\\(current\\\) UNIX) (P|p)assword.*"
set newpassword_string "(N|n)ew.* (P|p)assword.*"
set badoldpassword_string "(Authentication token manipulation error).*"
set badpassword_string "((passwd|BAD PASSWORD).*|(passwd|Bad:).*\r)"
set verify_string      "((R|r)e-*enter.*(P|p)assword|Retype new( UNIX)? password|(V|v)erification|(V|v)erify|(A|a)gain).*"
set success_string     "((P|p)assword.* changed|successfully)"
set login_string       "(((L|l)ogin|(U|u)sername).*)"
set timeout            20
set log                "/tmp/passwd.out"
set output             false
set output_file        "/tmp/passwd.log"

# read input from stdin
fconfigure stdin -blocking 1

gets stdin user
gets stdin password(old)
gets stdin password(new)

# alternative: read input from command line
#if {$argc < 3} {
#    send_user "Too few arguments: Usage $argv0 username oldpass newpass"
#    exit 1
#}
#set user [lindex $argv 0]
#set password(old) [lindex $argv 1]
#set password(new) [lindex $argv 2]

# no output to the user
log_user 0

# read in other options
for {set i 0} {$i<$argc} {incr i} {
    set arg [lindex $argv $i]
    switch -- $arg "-prompt" {
        incr i
        set prompt_string [lindex $argv $i]
        continue
    } "-password" {
        incr i
        set password_string [lindex $argv $i]
        continue
    } "-oldpassword" {
        incr i
        set oldpassword_string [lindex $argv $i]
        continue
    } "-newpassword" {
        incr i
        set newpassword_string [lindex $argv $i]
        continue
    } "-verify" {
        incr i
        set verify_string [lindex $argv $i]
        continue
    } "-success" {
        incr i
        set success_string [lindex $argv $i]
        continue
    } "-login" {
        incr i
        set login_string [lindex $argv $i]
        continue
    } "-host" {
        incr i
        set host [lindex $argv $i]
        continue
    } "-timeout" {
        incr i
        set timeout [lindex $argv $i]
        continue
    } "-log" {
        incr i
        set log [lindex $argv $i]
        continue
    } "-output" {
        incr i
        set output_file [lindex $argv $i]
        set output true
        continue
    } "-telnet" {
        set login "telnet"
        continue
    } "-ssh" {
        set login "ssh"
        continue
    } "-ssh-exec" {
        set login "ssh-exec"
        continue
    } "-rlogin" {
        set login "rlogin"
        continue
    } "-slogin" {
        set login "slogin"
        continue
    } "-sudo" {
        set login "sudo"
        continue
    } "-program" {
        incr i
        set program [lindex $argv $i]
        continue
    }
}

# log session
if {$output} {
   log_file $output_file
}

set err [open $log "w" "0600"]

# start remote session
if {[string match $login "rlogin"]} {
   set pid [spawn rlogin $host -l $user]
} elseif {[string match $login "slogin"]} {
   set pid [spawn slogin $host -l $user]
} elseif {[string match $login "ssh"]} {
   set pid [spawn ssh $host -l $user]
} elseif {[string match $login "ssh-exec"]} {
   set pid [spawn ssh $host -l $user $program]
} elseif {[string match $login "sudo"]} {
   set pid [spawn sudo -u $user $program]
} elseif {[string match $login "telnet"]} {
   set pid [spawn telnet $host]
   expect -re $login_string {
     sleep .5
     send "$user\r"
   }
} else {
   puts $err "Invalid login mode. Valid modes: rlogin, slogin, ssh, telnet, sudo\n"
   close $err
   exit 1
}

set old_password_notentered true

if {![string match $login "sudo"]} {
  # log in
  expect {
    -re $fingerprint_string {sleep .5
                             send yes\r
                             exp_continue}
    -re $password_string    {sleep .5
                             send $password(old)\r}
    timeout                 {puts $err "Could not login to system (no password prompt)\n"
                             close $err
                             exit 1}
  }

  # start password changing program
  expect {
    -re $prompt_string      {sleep .5
                             send $program\r}
    # The following is for when passwd is the login shell or ssh-exec is used
    -re $oldpassword_string {sleep .5
                             send $password(old)\r
                             set old_password_notentered false}
    timeout                 {puts $err  "Could not login to system (bad old password?)\n"
                             close $err
                             exit 1}
  }
}

# send old password
if {$old_password_notentered} {
  expect {
    -re $oldpassword_string {sleep .5
                             send $password(old)\r}
    timeout                 {puts $err "Could not start passwd program (no old password prompt)\n"
                             close $err
                             exit 1}
  }
}

# send new password
expect {
  -re $newpassword_string {sleep .5
                           send $password(new)\r}
  -re $badoldpassword_string {puts $err "Old password is incorrect\n"
                           close $err
                           exit 1}
  timeout                 {puts "Could not change password (bad old password?)\n"
                           close $err
                           exit 1}
}

# send new password again
expect {
  -re $badpassword_string {puts $err "$expect_out(0,string)"
                           close $err
                           send \003
                           sleep .5
                           exit 1}
  -re $verify_string      {sleep .5
                           send $password(new)\r}
  timeout                 {puts $err "New password not valid (too short, bad password, too similar, ...)\n"
                           close $err
                           send \003
                           sleep .5
                           exit 1}
}

# check response
expect {
  -re $success_string {sleep .5
                       send exit\r}
  -re $badpassword_string {puts $err "$expect_out(0,string)"
                           close $err
                           exit 1}
  timeout             {puts $err "Could not change password.\n"
                       close $err
                       exit 1}
}

# exit successfully
expect {
  eof {close $err
       exit 0}
}
close $err