source: code/branches/presentationFS14/data/tcl/irk/lib/irkauth.tcl @ 10105

# irkauth.tcl:
#
# Various procedures that deal with user authentication:

namespace eval ::irk {

    # The AUTH module keeps information about each user and facility ($fac)
    # in the state array:
    #
    # auth(auth,$fac,$user)             If set, then $user has authenticated
    #                                   successfully for the facility $fac.
    # auth(user,$fac,$user,pass)        The password for this $user and $fac.
    # auth(user,$fac,$user,ident)       The ident token for this $user & $fac.
    #
    # auth(ident,$fac,$ident,pass)      The password for this $ident and $fac.
    # auth(ident,$fac,$ident,user)      The user for this $ident and $fac.
    #
    # auth(identcounter,$fac)           The ident token counter for $fac. This
    #                                   is incremented each time a new user
    #                                   establishes themselves with $fac.

    # This procedure can be called by programs using the IRK library
    # when a user sends a password.

    proc pass {token fac nick user rest} {
        variable auth

        if {[llength $rest] != 1} {
            # Incorrect syntax:

            set reply "$nick, syntax is !pass <yourpass> (one word, no spaces)"
        } elseif {[info exists auth(user,$fac,$user,pass)]} {

            # If this user has already established a password,
            # check that they're giving the right password.

            if {[string compare $auth(user,$fac,$user,pass) \
                                [lindex $rest 0]]} {
                set reply "$nick, sorry, wrong password!"
            } else {
                set reply "$nick, thanks for entering your password!"
                set auth(auth,$fac,$user) 1
            }
        } else {

            # This is the first time we're seeing this user. Accept
            # their password and send them an ident token. They can
            # use the ident token to reestablish themselves when their
            # user mask changes significantly.

            if {![info exists auth(identcounter,$fac)]} {
                set auth(identcounter,$fac) 0
            }
            set ident $auth(identcounter,$fac)
            incr auth(identcounter,$fac)

            set auth(ident,$fac,$ident,user) $user
            set auth(ident,$fac,$ident,pass) [lindex $rest 0]

            set auth(user,$fac,$user,ident) $ident
            set auth(user,$fac,$user,pass) [lindex $rest 0]

            # Save the changes

            saveauth

            # Save them a step and also authorize them:

            set auth(ident,$fac,$user) 1

            set reply [list \
                $nick, your password is [lindex $rest 0]. Your ident is \
                $ident, write it down, you will need it later to \
                reidentify yourself if your user mask changes. \
                You user mask is currently $user. You are now authorised \
                to use $fac.]
        }

        # Tell them what happened:

        ::irk::say $token $nick $reply

        return ""
    }

    # This procedure can be called by programs when the user attempts to
    # reestablish themselves with the existing ident and password.

    proc id {token fac nick user rest} {
        variable auth

        set len [llength $rest]
        set reply "Wrong syntax. Call !ident or !ident <ident> <pass>"

        if {$len == 0} {

            # Calling ident with zero arguments. The user is trying to
            # retrieve their ident. Give it to them only if they did
            # identify successfully with the correct password.

            if {![info exists auth(user,$fac,$user,pass)]} {
                set reply "$nick, first set a password"
            } elseif {[info exists auth(auth,$fac,$user)]} {
                set reply \
                    "$nick, your ident is $auth(user,$fac,$user,ident)"
            } else {
                set reply \
                   "$nick, identify with password before getting your ident!"
            }
        } elseif {$len == 2} {

            # Calling ident with two arguments. The user is trying to
            # establish a new value for $user to associate with this
            # ident and password. If $auth($ident,pass) is the password
            # she gave, then they're the rightfull owner of the ident and
            # so we now recognize the new $user mask.

            set ident [lindex $rest 0]
            set pass [lindex $rest 1]

            if {[info exists auth(ident,$fac,$ident,pass)]} {
                if {![string compare $auth(ident,$fac,$ident,pass) $pass]} {

                    # Identify the old user mask they were using:

                    set olduser $auth(ident,$fac,$ident,user)

                    # Clean up the state associated with the old mask:

                    array unset auth user,$fac,$olduser,*
                    catch {unset auth(ident,$face,$olduser)}

                    # Link up the new state:

                    set auth(ident,$fac,$ident,user) $user

                    set auth(user,$fac,$user,ident) $ident
                    set auth(user,$fac,$user,pass) $pass

                    # Save the changes

                    saveauth

                    # Save them a step and also treat them as authenticated:

                    set auth(ident,$fac,$user) 1

                    set reply \
                            "OK, $nick, I'm now recognising you as $user.\
                             You are now authorised to use $fac."
                } else {
                    set reply "$nick, sorry, wrong ident or password"
                }
            } else {
                set reply "$nick, sorry, wrong ident or password"
            }
        }

        # Tell them what happened:

        ::irk::say $token $nick $reply

        return ""
    }

    # This procedure can be invoked by a program when a user tries to
    # change her password.

    proc np {token fac nick user rest} {
        variable auth

        set reply "Wrong syntax. Call !newpass <oldpass> <newpass>"

        if {[llength $rest] == 2} {
            set opw [lindex $rest 0]
            set npw [lindex $rest 1]

            if {![info exists auth(user,$fac,$user,pass)]} {
                # Unknown $user, probably their user mask changed. Help
                # them reestablish the connection.

                set reply \
                   [list $nick, I don't have you in my database. Perhaps \
                         your user mask changed drastically. If so, please \
                         reestablish your user mask by using !ident <ident> \
                         <oldpass>.]
            } elseif {[string compare $auth(user,$fac,$user,pass) $opw]} {
                # Wrong old password!

                set reply "$nick, sorry, wrong old password!"
            } else {
                # Their user mask matches and they gave the correct old
                # password, so we accept their new password:

                set ident $auth(user,$fac,$user,ident)

                set auth(ident,$fac,$ident,pass) $npw
                set auth(user,$fac,$user,pass) $npw

                # Save the changes:

                saveauth

                # Save them a step by also recording that they
                # authenticated:

                set auth(auth,$fac,$user) 1

                set reply "OK, $nick, your new password is now $npw"
            }
        }

        # Tell them what happened:

        ::irk::say $token $nick $reply

        return ""
    }

    # This procedure can be called by programs when the user wants to
    # "log out" or lose her authentication with a given facility:

    proc logout {token fac nick user rest} {
        variable auth

        set reply "You were not logged into $fac. Now you certainly aren't."

        if {[info exists auth(auth,$fac,$user)]} {
            unset auth(auth,$fac,$user)

            set reply \
                [list $nick, you logged out successfully from $fac. Thank you \
                      for using $fac.]
        }

        # Tell them what happened:

        ::irk::say $token $nick $reply

        return ""
    }

    # Is the user authenticated with the given facility?

    proc userauthenticated {fac user} {
        variable auth

        # If auth(auth,$fac,$user) exists, then she is authenticated.

        if {[info exists auth(auth,$fac,$user)]} {
            return 1
        }
        return 0
    }

    # This procedure automatically saves the authorization database:

    proc saveauth {} {
        variable state
        variable auth

        puts "Saving!"

        # Define the patterns to save:

        set p1 "identcounter,*"
        set p2 "user,*"
        set p3 "ident,*"

        # Try to open the save file:

        if {[info exists state(auth,save,file)]} {
            if {![catch {set fd [open $state(auth,save,file) w]}]} {
                puts $fd "array set ::irk::auth [list [array get auth $p1]]"
                puts $fd "array set ::irk::auth [list [array get auth $p2]]"
                puts $fd "array set ::irk::auth [list [array get auth $p3]]"

                catch {close $fd}
            }
        }
    }

    # This procedure restores the authorization database:

    proc restoreauth {} {
        variable state

        if {[info exists state(auth,save,file)]} {
            catch {uplevel #0 source $state(auth,save,file)}
        }
        set state(auth,restored) 1
    }

    # If this is the first time we're loading the IRK package, then
    # restore the authorization database. Otherwise we'd be overwriting
    # a potentially unsaved state.

    variable state

    if {![info exists state(auth,restored)]} {
        restoreauth
    }
}