C4/Auth_with_ldap.pm

   1 package C4::Auth_with_ldap;
   2
   3 # Copyright 2000-2002 Katipo Communications
   4 #
   5 # This file is part of Koha.
   6 #
   7 # Koha is free software; you can redistribute it and/or modify it under the
   8 # terms of the GNU General Public License as published by the Free Software
   9 # Foundation; either version 2 of the License, or (at your option) any later
  10 # version.
  11 #
  12 # Koha is distributed in the hope that it will be useful, but WITHOUT ANY
  13 # WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
  14 # A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
  15 #
  16 # You should have received a copy of the GNU General Public License along
  17 # with Koha; if not, write to the Free Software Foundation, Inc.,
  18 # 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  19
  20 use strict;
  21 #use warnings; FIXME - Bug 2505
  22 use Digest::MD5 qw(md5_base64);
  23
  24 use C4::Debug;
  25 use C4::Context;
  26 use C4::Members qw(AddMember changepassword);
  27 use C4::Members::Attributes;
  28 use C4::Members::AttributeTypes;
  29 use C4::Utils qw( :all );
  30 use List::MoreUtils qw( any );
  31 use Net::LDAP;
  32 use Net::LDAP::Filter;
  33
  34 use vars qw($VERSION @ISA @EXPORT @EXPORT_OK %EXPORT_TAGS $debug);
  35
  36 BEGIN {
  37         require Exporter;
  38     $VERSION = 3.07.00.049;     # set the version for version checking
  39         @ISA    = qw(Exporter);
  40         @EXPORT = qw( checkpw_ldap );
  41 }
  42
  43 # Redefine checkpw_ldap:
  44 # connect to LDAP (named or anonymous)
  45 # ~ retrieves $userid from KOHA_CONF mapping
  46 # ~ then compares $password with userPassword
  47 # ~ then gets the LDAP entry
  48 # ~ and calls the memberadd if necessary
  49
  50 sub ldapserver_error {
  51         return sprintf('No ldapserver "%s" defined in KOHA_CONF: ' . $ENV{KOHA_CONF}, shift);
  52 }
  53
  54 use vars qw($mapping @ldaphosts $base $ldapname $ldappassword);
  55 my $context = C4::Context->new()        or die 'C4::Context->new failed';
  56 my $ldap = C4::Context->config("ldapserver") or die 'No "ldapserver" in server hash from KOHA_CONF: ' . $ENV{KOHA_CONF};
  57 my $prefhost  = $ldap->{hostname}       or die ldapserver_error('hostname');
  58 my $base      = $ldap->{base}           or die ldapserver_error('base');
  59 $ldapname     = $ldap->{user}           ;
  60 $ldappassword = $ldap->{pass}           ;
  61 our %mapping  = %{$ldap->{mapping}}; # FIXME dpavlin -- don't die because of || (); from 6eaf8511c70eb82d797c941ef528f4310a15e9f9
  62 my @mapkeys = keys %mapping;
  63 $debug and print STDERR "Got ", scalar(@mapkeys), " ldap mapkeys (  total  ): ", join ' ', @mapkeys, "\n";
  64 @mapkeys = grep {defined $mapping{$_}->{is}} @mapkeys;
  65 $debug and print STDERR "Got ", scalar(@mapkeys), " ldap mapkeys (populated): ", join ' ', @mapkeys, "\n";
  66
  67 my %config = (
  68         anonymous => ($ldapname and $ldappassword) ? 0 : 1,
  69     replicate => defined($ldap->{replicate}) ? $ldap->{replicate} : 1,  #    add from LDAP to Koha database for new user
  70        update => defined($ldap->{update}   ) ? $ldap->{update}    : 1,  # update from LDAP to Koha database for existing user
  71 );
  72
  73 sub description {
  74         my $result = shift or return;
  75         return "LDAP error #" . $result->code
  76                         . ": " . $result->error_name . "\n"
  77                         . "# " . $result->error_text . "\n";
  78 }
  79
  80 sub search_method {
  81     my $db     = shift or return;
  82     my $userid = shift or return;
  83         my $uid_field = $mapping{userid}->{is} or die ldapserver_error("mapping for 'userid'");
  84         my $filter = Net::LDAP::Filter->new("$uid_field=$userid") or die "Failed to create new Net::LDAP::Filter";
  85         my $search = $db->search(
  86                   base => $base,
  87                 filter => $filter,
  88                 # attrs => ['*'],
  89         ) or die "LDAP search failed to return object.";
  90         my $count = $search->count;
  91         if ($search->code > 0) {
  92                 warn sprintf("LDAP Auth rejected : %s gets %d hits\n", $filter->as_string, $count) . description($search);
  93                 return 0;
  94         }
  95         if ($count != 1) {
  96                 warn sprintf("LDAP Auth rejected : %s gets %d hits\n", $filter->as_string, $count);
  97                 return 0;
  98         }
  99     return $search;
 100 }
 101
 102 sub checkpw_ldap {
 103     my ($dbh, $userid, $password) = @_;
 104     my @hosts = split(',', $prefhost);
 105     my $db = Net::LDAP->new(\@hosts);
 106         #$debug and $db->debug(5);
 107     my $userldapentry;
 108         if ( $ldap->{auth_by_bind} ) {
 109         my $principal_name = $ldap->{principal_name};
 110         if ($principal_name and $principal_name =~ /\%/) {
 111             $principal_name = sprintf($principal_name,$userid);
 112         } else {
 113             $principal_name = $userid;
 114         }
 115                 my $res = $db->bind( $principal_name, password => $password );
 116         if ( $res->code ) {
 117             $debug and warn "LDAP bind failed as kohauser $principal_name: ". description($res);
 118             return 0;
 119         }
 120
 121         # FIXME dpavlin -- we really need $userldapentry leater on even if using auth_by_bind!
 122
 123         # BUG #5094
 124         # 2010-08-04 JeremyC
 125         # a $userldapentry is only needed if either updating or replicating are enabled
 126         if($config{update} or $config{replicate}) {
 127             my $search = search_method($db, $userid) or return 0;   # warnings are in the sub
 128             $userldapentry = $search->shift_entry;
 129         }
 130
 131         } else {
 132                 my $res = ($config{anonymous}) ? $db->bind : $db->bind($ldapname, password=>$ldappassword);
 133                 if ($res->code) {               # connection refused
 134                         warn "LDAP bind failed as ldapuser " . ($ldapname || '[ANONYMOUS]') . ": " . description($res);
 135                         return 0;
 136                 }
 137         my $search = search_method($db, $userid) or return 0;   # warnings are in the sub
 138         $userldapentry = $search->shift_entry;
 139                 my $cmpmesg = $db->compare( $userldapentry, attr=>'userpassword', value => $password );
 140                 if ($cmpmesg->code != 6) {
 141                         warn "LDAP Auth rejected : invalid password for user '$userid'. " . description($cmpmesg);
 142                         return 0;
 143                 }
 144         }
 145
 146     # To get here, LDAP has accepted our user's login attempt.
 147     # But we still have work to do.  See perldoc below for detailed breakdown.
 148
 149     my (%borrower);
 150         my ($borrowernumber,$cardnumber,$local_userid,$savedpw) = exists_local($userid);
 151
 152     if (( $borrowernumber and $config{update}   ) or
 153         (!$borrowernumber and $config{replicate})   ) {
 154         %borrower = ldap_entry_2_hash($userldapentry,$userid);
 155         $debug and print STDERR "checkpw_ldap received \%borrower w/ " . keys(%borrower), " keys: ", join(' ', keys %borrower), "\n";
 156     }
 157
 158     if ($borrowernumber) {
 159         if ($config{update}) { # A1, B1
 160             my $c2 = &update_local($local_userid,$password,$borrowernumber,\%borrower) || '';
 161             ($cardnumber eq $c2) or warn "update_local returned cardnumber '$c2' instead of '$cardnumber'";
 162         } else { # C1, D1
 163             # maybe update just the password?
 164                 return(1, $cardnumber, $local_userid);
 165         }
 166     } elsif ($config{replicate}) { # A2, C2
 167         $borrowernumber = AddMember(%borrower) or die "AddMember failed";
 168    } else {
 169         return 0;   # B2, D2
 170     }
 171         if (C4::Context->preference('ExtendedPatronAttributes') && $borrowernumber && ($config{update} ||$config{replicate})) {
 172                 my @types = C4::Members::AttributeTypes::GetAttributeTypes();
 173                 my @attributes = grep{my $key=$_; any{$_ eq $key}@types;} keys %borrower;
 174         my $extended_patron_attributes;
 175         @{$extended_patron_attributes} =
 176           map { { code => $_, value => $borrower{$_} } } @attributes;
 177                 my @errors;
 178                 #Check before add
 179                 for (my $i; $i< scalar(@$extended_patron_attributes)-1;$i++) {
 180                         my $attr=$extended_patron_attributes->[$i];
 181                         unless (C4::Members::Attributes::CheckUniqueness($attr->{code}, $attr->{value}, $borrowernumber)) {
 182                                 unshift @errors, $i;
 183                                 warn "ERROR_extended_unique_id_failed $attr->{code} $attr->{value}";
 184                         }
 185                 }
 186                 #Removing erroneous attributes
 187                 foreach my $index (@errors){
 188                         @$extended_patron_attributes=splice(@$extended_patron_attributes,$index,1);
 189                 }
 190            C4::Members::Attributes::SetBorrowerAttributes($borrowernumber, $extended_patron_attributes);
 191         }
 192 return(1, $cardnumber, $userid);
 193 }
 194
 195 # Pass LDAP entry object and local cardnumber (userid).
 196 # Returns borrower hash.
 197 # Edit KOHA_CONF so $memberhash{'xxx'} fits your ldap structure.
 198 # Ensure that mandatory fields are correctly filled!
 199 #
 200 sub ldap_entry_2_hash {
 201         my $userldapentry = shift;
 202         my %borrower = ( cardnumber => shift );
 203         my %memberhash;
 204         $userldapentry->exists('uid');  # This is bad, but required!  By side-effect, this initializes the attrs hash.
 205         if ($debug) {
 206                 print STDERR "\nkeys(\%\$userldapentry) = " . join(', ', keys %$userldapentry), "\n", $userldapentry->dump();
 207                 foreach (keys %$userldapentry) {
 208                         print STDERR "\n\nLDAP key: $_\t", sprintf('(%s)', ref $userldapentry->{$_}), "\n";
 209                         hashdump("LDAP key: ",$userldapentry->{$_});
 210                 }
 211         }
 212         my $x = $userldapentry->{attrs} or return;
 213         foreach (keys %$x) {
 214                 $memberhash{$_} = join ' ', @{$x->{$_}};
 215                 $debug and print STDERR sprintf("building \$memberhash{%s} = ", $_, join(' ', @{$x->{$_}})), "\n";
 216         }
 217         $debug and print STDERR "Finsihed \%memberhash has ", scalar(keys %memberhash), " keys\n",
 218                                         "Referencing \%mapping with ", scalar(keys %mapping), " keys\n";
 219         foreach my $key (keys %mapping) {
 220                 my  $data = $memberhash{ lc($mapping{$key}->{is}) }; # Net::LDAP returns all names in lowercase
 221                 $debug and printf STDERR "mapping %20s ==> %-20s (%s)\n", $key, $mapping{$key}->{is}, $data;
 222                 unless (defined $data) {
 223                         $data = $mapping{$key}->{content} || '';        # default or failsafe ''
 224                 }
 225                 $borrower{$key} = ($data ne '') ? $data : ' ' ;
 226         }
 227         $borrower{initials} = $memberhash{initials} ||
 228                 ( substr($borrower{'firstname'},0,1)
 229                 . substr($borrower{ 'surname' },0,1)
 230                 . " ");
 231
 232         # check if categorycode exists, if not, fallback to default from koha-conf.xml
 233         my $dbh = C4::Context->dbh;
 234         my $sth = $dbh->prepare("SELECT categorycode FROM categories WHERE categorycode = ?");
 235         $sth->execute( uc($borrower{'categorycode'}) );
 236         unless ( my $row = $sth->fetchrow_hashref ) {
 237                 my $default = $mapping{'categorycode'}->{content};
 238                 $debug && warn "Can't find ", $borrower{'categorycode'}, " default to: $default for ", $borrower{userid};
 239                 $borrower{'categorycode'} = $default
 240         }
 241
 242         return %borrower;
 243 }
 244
 245 sub exists_local {
 246         my $arg = shift;
 247         my $dbh = C4::Context->dbh;
 248         my $select = "SELECT borrowernumber,cardnumber,userid,password FROM borrowers ";
 249
 250         my $sth = $dbh->prepare("$select WHERE userid=?");      # was cardnumber=?
 251         $sth->execute($arg);
 252         $debug and printf STDERR "Userid '$arg' exists_local? %s\n", $sth->rows;
 253         ($sth->rows == 1) and return $sth->fetchrow;
 254
 255         $sth = $dbh->prepare("$select WHERE cardnumber=?");
 256         $sth->execute($arg);
 257         $debug and printf STDERR "Cardnumber '$arg' exists_local? %s\n", $sth->rows;
 258         ($sth->rows == 1) and return $sth->fetchrow;
 259         return 0;
 260 }
 261
 262 sub _do_changepassword {
 263     my ($userid, $borrowerid, $digest) = @_;
 264     $debug and print STDERR "changing local password for borrowernumber=$borrowerid to '$digest'\n";
 265     changepassword($userid, $borrowerid, $digest);
 266
 267         # Confirm changes
 268         my $sth = C4::Context->dbh->prepare("SELECT password,cardnumber FROM borrowers WHERE borrowernumber=? ");
 269         $sth->execute($borrowerid);
 270         if ($sth->rows) {
 271                 my ($md5password, $cardnum) = $sth->fetchrow;
 272         ($digest eq $md5password) and return $cardnum;
 273                 warn "Password mismatch after update to cardnumber=$cardnum (borrowernumber=$borrowerid)";
 274                 return;
 275         }
 276         die "Unexpected error after password update to userid/borrowernumber: $userid / $borrowerid.";
 277 }
 278
 279 sub update_local {
 280         my   $userid   = shift             or return;
 281         my   $digest   = md5_base64(shift) or return;
 282         my $borrowerid = shift             or return;
 283         my $borrower   = shift             or return;
 284         my @keys = keys %$borrower;
 285         my $dbh = C4::Context->dbh;
 286         my $query = "UPDATE  borrowers\nSET     " .
 287                 join(',', map {"$_=?"} @keys) .
 288                 "\nWHERE   borrowernumber=? ";
 289         my $sth = $dbh->prepare($query);
 290         if ($debug) {
 291                 print STDERR $query, "\n",
 292                         join "\n", map {"$_ = '" . $borrower->{$_} . "'"} @keys;
 293                 print STDERR "\nuserid = $userid\n";
 294         }
 295         $sth->execute(
 296                 ((map {$borrower->{$_}} @keys), $borrowerid)
 297         );
 298
 299         # MODIFY PASSWORD/LOGIN
 300         _do_changepassword($userid, $borrowerid, $digest);
 301 }
 302
 303 1;
 304 __END__
 305
 306 =head1 NAME
 307
 308 C4::Auth - Authenticates Koha users
 309
 310 =head1 SYNOPSIS
 311
 312   use C4::Auth_with_ldap;
 313
 314 =head1 LDAP Configuration
 315
 316     This module is specific to LDAP authentification. It requires Net::LDAP package and one or more
 317         working LDAP servers.
 318         To use it :
 319            * Modify ldapserver element in KOHA_CONF
 320            * Establish field mapping in <mapping> element.
 321
 322         For example, if your user records are stored according to the inetOrgPerson schema, RFC#2798,
 323         the username would match the "uid" field, and the password should match the "userpassword" field.
 324
 325         Make sure that ALL required fields are populated by your LDAP database (and mapped in KOHA_CONF).
 326         What are the required fields?  Well, in mysql you can check the database table "borrowers" like this:
 327
 328         mysql> show COLUMNS from borrowers;
 329                 +---------------------+--------------+------+-----+---------+----------------+
 330                 | Field               | Type         | Null | Key | Default | Extra          |
 331                 +---------------------+--------------+------+-----+---------+----------------+
 332                 | borrowernumber      | int(11)      | NO   | PRI | NULL    | auto_increment |
 333                 | cardnumber          | varchar(16)  | YES  | UNI | NULL    |                |
 334                 | surname             | mediumtext   | NO   |     | NULL    |                |
 335                 | firstname           | text         | YES  |     | NULL    |                |
 336                 | title               | mediumtext   | YES  |     | NULL    |                |
 337                 | othernames          | mediumtext   | YES  |     | NULL    |                |
 338                 | initials            | text         | YES  |     | NULL    |                |
 339                 | streetnumber        | varchar(10)  | YES  |     | NULL    |                |
 340                 | streettype          | varchar(50)  | YES  |     | NULL    |                |
 341                 | address             | mediumtext   | NO   |     | NULL    |                |
 342                 | address2            | text         | YES  |     | NULL    |                |
 343                 | city                | mediumtext   | NO   |     | NULL    |                |
 344                 | state               | mediumtext   | YES  |     | NULL    |                |
 345                 | zipcode             | varchar(25)  | YES  |     | NULL    |                |
 346                 | country             | text         | YES  |     | NULL    |                |
 347                 | email               | mediumtext   | YES  |     | NULL    |                |
 348                 | phone               | text         | YES  |     | NULL    |                |
 349                 | mobile              | varchar(50)  | YES  |     | NULL    |                |
 350                 | fax                 | mediumtext   | YES  |     | NULL    |                |
 351                 | emailpro            | text         | YES  |     | NULL    |                |
 352                 | phonepro            | text         | YES  |     | NULL    |                |
 353                 | B_streetnumber      | varchar(10)  | YES  |     | NULL    |                |
 354                 | B_streettype        | varchar(50)  | YES  |     | NULL    |                |
 355                 | B_address           | varchar(100) | YES  |     | NULL    |                |
 356                 | B_address2          | text         | YES  |     | NULL    |                |
 357                 | B_city              | mediumtext   | YES  |     | NULL    |                |
 358                 | B_state             | mediumtext   | YES  |     | NULL    |                |
 359                 | B_zipcode           | varchar(25)  | YES  |     | NULL    |                |
 360                 | B_country           | text         | YES  |     | NULL    |                |
 361                 | B_email             | text         | YES  |     | NULL    |                |
 362                 | B_phone             | mediumtext   | YES  |     | NULL    |                |
 363                 | dateofbirth         | date         | YES  |     | NULL    |                |
 364                 | branchcode          | varchar(10)  | NO   | MUL |         |                |
 365                 | categorycode        | varchar(10)  | NO   | MUL |         |                |
 366                 | dateenrolled        | date         | YES  |     | NULL    |                |
 367                 | dateexpiry          | date         | YES  |     | NULL    |                |
 368                 | gonenoaddress       | tinyint(1)   | YES  |     | NULL    |                |
 369                 | lost                | tinyint(1)   | YES  |     | NULL    |                |
 370                 | debarred            | date         | YES  |     | NULL    |                |
 371                 | debarredcomment     | varchar(255) | YES  |     | NULL    |                |
 372                 | contactname         | mediumtext   | YES  |     | NULL    |                |
 373                 | contactfirstname    | text         | YES  |     | NULL    |                |
 374                 | contacttitle        | text         | YES  |     | NULL    |                |
 375                 | guarantorid         | int(11)      | YES  | MUL | NULL    |                |
 376                 | borrowernotes       | mediumtext   | YES  |     | NULL    |                |
 377                 | relationship        | varchar(100) | YES  |     | NULL    |                |
 378                 | ethnicity           | varchar(50)  | YES  |     | NULL    |                |
 379                 | ethnotes            | varchar(255) | YES  |     | NULL    |                |
 380                 | sex                 | varchar(1)   | YES  |     | NULL    |                |
 381                 | password            | varchar(30)  | YES  |     | NULL    |                |
 382                 | flags               | int(11)      | YES  |     | NULL    |                |
 383                 | userid              | varchar(30)  | YES  | MUL | NULL    |                |
 384                 | opacnote            | mediumtext   | YES  |     | NULL    |                |
 385                 | contactnote         | varchar(255) | YES  |     | NULL    |                |
 386                 | sort1               | varchar(80)  | YES  |     | NULL    |                |
 387                 | sort2               | varchar(80)  | YES  |     | NULL    |                |
 388                 | altcontactfirstname | varchar(255) | YES  |     | NULL    |                |
 389                 | altcontactsurname   | varchar(255) | YES  |     | NULL    |                |
 390                 | altcontactaddress1  | varchar(255) | YES  |     | NULL    |                |
 391                 | altcontactaddress2  | varchar(255) | YES  |     | NULL    |                |
 392                 | altcontactaddress3  | varchar(255) | YES  |     | NULL    |                |
 393                 | altcontactstate     | mediumtext   | YES  |     | NULL    |                |
 394                 | altcontactzipcode   | varchar(50)  | YES  |     | NULL    |                |
 395                 | altcontactcountry   | text         | YES  |     | NULL    |                |
 396                 | altcontactphone     | varchar(50)  | YES  |     | NULL    |                |
 397                 | smsalertnumber      | varchar(50)  | YES  |     | NULL    |                |
 398                 | privacy             | int(11)      | NO   |     | 1       |                |
 399                 +---------------------+--------------+------+-----+---------+----------------+
 400                 66 rows in set (0.00 sec)
 401                 Where Null="NO", the field is required.
 402
 403 =head1 KOHA_CONF and field mapping
 404
 405 Example XML stanza for LDAP configuration in KOHA_CONF.
 406
 407  <config>
 408   ...
 409   <useldapserver>1</useldapserver>
 410   <!-- LDAP SERVER (optional) -->
 411   <ldapserver id="ldapserver">
 412     <hostname>localhost</hostname>
 413     <base>dc=metavore,dc=com</base>
 414     <user>cn=Manager,dc=metavore,dc=com</user>             <!-- DN, if not anonymous -->
 415     <pass>metavore</pass>          <!-- password, if not anonymous -->
 416     <replicate>1</replicate>       <!-- add new users from LDAP to Koha database -->
 417     <update>1</update>             <!-- update existing users in Koha database -->
 418     <auth_by_bind>0</auth_by_bind> <!-- set to 1 to authenticate by binding instead of
 419                                         password comparison, e.g., to use Active Directory -->
 420     <principal_name>%s@my_domain.com</principal_name>
 421                                    <!-- optional, for auth_by_bind: a printf format to make userPrincipalName from koha userid -->
 422     <mapping>                  <!-- match koha SQL field names to your LDAP record field names -->
 423       <firstname    is="givenname"      ></firstname>
 424       <surname      is="sn"             ></surname>
 425       <address      is="postaladdress"  ></address>
 426       <city         is="l"              >Athens, OH</city>
 427       <zipcode      is="postalcode"     ></zipcode>
 428       <branchcode   is="branch"         >MAIN</branchcode>
 429       <userid       is="uid"            ></userid>
 430       <password     is="userpassword"   ></password>
 431       <email        is="mail"           ></email>
 432       <categorycode is="employeetype"   >PT</categorycode>
 433       <phone        is="telephonenumber"></phone>
 434     </mapping>
 435   </ldapserver>
 436  </config>
 437
 438 The <mapping> subelements establish the relationship between mysql fields and LDAP attributes. The element name
 439 is the column in mysql, with the "is" characteristic set to the LDAP attribute name.  Optionally, any content
 440 between the element tags is taken as the default value.  In this example, the default categorycode is "PT" (for
 441 patron).
 442
 443 =head1 CONFIGURATION
 444
 445 Once a user has been accepted by the LDAP server, there are several possibilities for how Koha will behave, depending on
 446 your configuration and the presence of a matching Koha user in your local DB:
 447
 448                          LOCAL_USER
 449  OPTION UPDATE REPLICATE  EXISTS?  RESULT
 450    A1      1       1        1      OK : We're updating them anyway.
 451    A2      1       1        0      OK : We're adding them anyway.
 452    B1      1       0        1      OK : We update them.
 453    B2      1       0        0     FAIL: We cannot add new user.
 454    C1      0       1        1      OK : We do nothing.  (maybe should update password?)
 455    C2      0       1        0      OK : We add the new user.
 456    D1      0       0        1      OK : We do nothing.  (maybe should update password?)
 457    D2      0       0        0     FAIL: We cannot add new user.
 458
 459 Note: failure here just means that Koha will fallback to checking the local DB.  That is, a given user could login with
 460 their LDAP password OR their local one.  If this is a problem, then you should enable update and supply a mapping for
 461 password.  Then the local value will be updated at successful LDAP login and the passwords will be synced.
 462
 463 If you choose NOT to update local users, the borrowers table will not be affected at all.
 464 Note that this means that patron passwords may appear to change if LDAP is ever disabled, because
 465 the local table never contained the LDAP values.
 466
 467 =head2 auth_by_bind
 468
 469 Binds as the user instead of retrieving their record.  Recommended if update disabled.
 470
 471 =head2 principal_name
 472
 473 Provides an optional sprintf-style format for manipulating the userid before the bind.
 474 Even though the userPrincipalName is one intended target, any uniquely identifying
 475 attribute that the server allows to be used for binding could be used.
 476
 477 Currently, principal_name only operates when auth_by_bind is enabled.
 478
 479 =head2 Active Directory
 480
 481 The auth_by_bind and principal_name settings are recommended for Active Directory.
 482
 483 Under default Active Directory rules, we cannot determine the distinguishedName attribute from the Koha userid as reliably as
 484 we would typically under openldap.  Instead of:
 485
 486     distinguishedName: CN=barnes.7,DC=my_company,DC=com
 487
 488 We might get:
 489
 490     distinguishedName: CN=Barnes\, Jim,OU=Test Accounts,OU=User Accounts,DC=my_company,DC=com
 491
 492 Matching that would require us to know more info about the account (firstname, surname) and to include punctuation and whitespace
 493 in Koha userids.  But the userPrincipalName should be consistent, something like:
 494
 495     userPrincipalName: barnes.7@my_company.com
 496
 497 Therefore it is often easier to bind to Active Directory with userPrincipalName, effectively the
 498 canonical email address for that user, or what it would be if email were enabled for them.  If Koha userid values
 499 will match the username portion of the userPrincipalName, and the domain suffix is the same for all users, then use principal_name
 500 like this:
 501     <principal_name>%s@core.my_company.com</principal_name>
 502
 503 The user of the previous example, barnes.7, would then attempt to bind as:
 504     barnes.7@core.my_company.com
 505
 506 =head1 SEE ALSO
 507
 508 CGI(3)
 509
 510 Net::LDAP()
 511
 512 XML::Simple()
 513
 514 Digest::MD5(3)
 515
 516 sprintf()
 517
 518 =cut
 519
 520 # For reference, here's an important difference in the data structure we rely on.
 521 # ========================================
 522 # Using attrs instead of {asn}->attributes
 523 # ========================================
 524 #
 525 #       LDAP key: ->{             cn} = ARRAY w/ 3 members.
 526 #       LDAP key: ->{             cn}->{           sss} = sss
 527 #       LDAP key: ->{             cn}->{   Steve Smith} = Steve Smith
 528 #       LDAP key: ->{             cn}->{Steve S. Smith} = Steve S. Smith
 529 #
 530 #       LDAP key: ->{      givenname} = ARRAY w/ 1 members.
 531 #       LDAP key: ->{      givenname}->{Steve} = Steve
 532 #