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     unless ( $db ) {
 107         warn "LDAP connexion failed";
 108         return 0;
 109     }
 110
 111         #$debug and $db->debug(5);
 112     my $userldapentry;
 113
 114   if ( $ldap->{auth_by_bind} ) {
 115     # Perform an anonymous bind
 116     my $res = $db->bind;
 117     if ( $res->code ) {
 118       $debug and warn "Anonymous LDAP bind failed: ". description($res);
 119       return 0;
 120     }
 121
 122     # Perform a LDAP search for the given username
 123     my $search = search_method($db, $userid) or return 0;   # warnings are in the sub
 124     $userldapentry = $search->shift_entry;
 125
 126     # Perform a LDAP bind for the given username using the matched DN
 127     $res = $db->bind( $userldapentry->dn, password => $password );
 128     if ( $res->code ) {
 129       $debug and warn "LDAP bind failed as kohauser $userid: ". description($res);
 130       return 0;
 131     }
 132
 133   } else {
 134                 my $res = ($config{anonymous}) ? $db->bind : $db->bind($ldapname, password=>$ldappassword);
 135                 if ($res->code) {               # connection refused
 136                         warn "LDAP bind failed as ldapuser " . ($ldapname || '[ANONYMOUS]') . ": " . description($res);
 137                         return 0;
 138                 }
 139         my $search = search_method($db, $userid) or return 0;   # warnings are in the sub
 140         $userldapentry = $search->shift_entry;
 141                 my $cmpmesg = $db->compare( $userldapentry, attr=>'userpassword', value => $password );
 142                 if ($cmpmesg->code != 6) {
 143                         warn "LDAP Auth rejected : invalid password for user '$userid'. " . description($cmpmesg);
 144                         return 0;
 145                 }
 146         }
 147
 148     # To get here, LDAP has accepted our user's login attempt.
 149     # But we still have work to do.  See perldoc below for detailed breakdown.
 150
 151     my (%borrower);
 152         my ($borrowernumber,$cardnumber,$local_userid,$savedpw) = exists_local($userid);
 153
 154     if (( $borrowernumber and $config{update}   ) or
 155         (!$borrowernumber and $config{replicate})   ) {
 156         %borrower = ldap_entry_2_hash($userldapentry,$userid);
 157         $debug and print STDERR "checkpw_ldap received \%borrower w/ " . keys(%borrower), " keys: ", join(' ', keys %borrower), "\n";
 158     }
 159
 160     if ($borrowernumber) {
 161         if ($config{update}) { # A1, B1
 162             my $c2 = &update_local($local_userid,$password,$borrowernumber,\%borrower) || '';
 163             ($cardnumber eq $c2) or warn "update_local returned cardnumber '$c2' instead of '$cardnumber'";
 164         } else { # C1, D1
 165             # maybe update just the password?
 166                 return(1, $cardnumber, $local_userid);
 167         }
 168     } elsif ($config{replicate}) { # A2, C2
 169         $borrowernumber = AddMember(%borrower) or die "AddMember failed";
 170    } else {
 171         return 0;   # B2, D2
 172     }
 173         if (C4::Context->preference('ExtendedPatronAttributes') && $borrowernumber && ($config{update} ||$config{replicate})) {
 174         my $extended_patron_attributes;
 175         foreach my $attribute_type ( C4::Members::AttributeTypes::GetAttributeTypes() ) {
 176                 my $code = $attribute_type->{code};
 177                 if ( exists($borrower{$code}) && $borrower{$code} !~ m/^\s*$/ ) { # skip empty values
 178                         push @$extended_patron_attributes, { code => $code, value => $borrower{$code} };
 179                 }
 180         }
 181                 my @errors;
 182                 #Check before add
 183                 for (my $i; $i< scalar(@$extended_patron_attributes)-1;$i++) {
 184                         my $attr=$extended_patron_attributes->[$i];
 185                         unless (C4::Members::Attributes::CheckUniqueness($attr->{code}, $attr->{value}, $borrowernumber)) {
 186                                 unshift @errors, $i;
 187                                 warn "ERROR_extended_unique_id_failed $attr->{code} $attr->{value}";
 188                         }
 189                 }
 190                 #Removing erroneous attributes
 191                 foreach my $index (@errors){
 192                         @$extended_patron_attributes=splice(@$extended_patron_attributes,$index,1);
 193                 }
 194            C4::Members::Attributes::SetBorrowerAttributes($borrowernumber, $extended_patron_attributes);
 195         }
 196 return(1, $cardnumber, $userid);
 197 }
 198
 199 # Pass LDAP entry object and local cardnumber (userid).
 200 # Returns borrower hash.
 201 # Edit KOHA_CONF so $memberhash{'xxx'} fits your ldap structure.
 202 # Ensure that mandatory fields are correctly filled!
 203 #
 204 sub ldap_entry_2_hash {
 205         my $userldapentry = shift;
 206         my %borrower = ( cardnumber => shift );
 207         my %memberhash;
 208         $userldapentry->exists('uid');  # This is bad, but required!  By side-effect, this initializes the attrs hash.
 209         if ($debug) {
 210                 print STDERR "\nkeys(\%\$userldapentry) = " . join(', ', keys %$userldapentry), "\n", $userldapentry->dump();
 211                 foreach (keys %$userldapentry) {
 212                         print STDERR "\n\nLDAP key: $_\t", sprintf('(%s)', ref $userldapentry->{$_}), "\n";
 213                         hashdump("LDAP key: ",$userldapentry->{$_});
 214                 }
 215         }
 216         my $x = $userldapentry->{attrs} or return;
 217         foreach (keys %$x) {
 218                 $memberhash{$_} = join ' ', @{$x->{$_}};
 219                 $debug and print STDERR sprintf("building \$memberhash{%s} = ", $_, join(' ', @{$x->{$_}})), "\n";
 220         }
 221         $debug and print STDERR "Finsihed \%memberhash has ", scalar(keys %memberhash), " keys\n",
 222                                         "Referencing \%mapping with ", scalar(keys %mapping), " keys\n";
 223         foreach my $key (keys %mapping) {
 224                 my  $data = $memberhash{ lc($mapping{$key}->{is}) }; # Net::LDAP returns all names in lowercase
 225                 $debug and printf STDERR "mapping %20s ==> %-20s (%s)\n", $key, $mapping{$key}->{is}, $data;
 226                 unless (defined $data) {
 227                         $data = $mapping{$key}->{content} || '';        # default or failsafe ''
 228                 }
 229                 $borrower{$key} = ($data ne '') ? $data : ' ' ;
 230         }
 231         $borrower{initials} = $memberhash{initials} ||
 232                 ( substr($borrower{'firstname'},0,1)
 233                 . substr($borrower{ 'surname' },0,1)
 234                 . " ");
 235
 236         # check if categorycode exists, if not, fallback to default from koha-conf.xml
 237         my $dbh = C4::Context->dbh;
 238         my $sth = $dbh->prepare("SELECT categorycode FROM categories WHERE categorycode = ?");
 239         $sth->execute( uc($borrower{'categorycode'}) );
 240         unless ( my $row = $sth->fetchrow_hashref ) {
 241                 my $default = $mapping{'categorycode'}->{content};
 242                 $debug && warn "Can't find ", $borrower{'categorycode'}, " default to: $default for ", $borrower{userid};
 243                 $borrower{'categorycode'} = $default
 244         }
 245
 246         return %borrower;
 247 }
 248
 249 sub exists_local {
 250         my $arg = shift;
 251         my $dbh = C4::Context->dbh;
 252         my $select = "SELECT borrowernumber,cardnumber,userid,password FROM borrowers ";
 253
 254         my $sth = $dbh->prepare("$select WHERE userid=?");      # was cardnumber=?
 255         $sth->execute($arg);
 256         $debug and printf STDERR "Userid '$arg' exists_local? %s\n", $sth->rows;
 257         ($sth->rows == 1) and return $sth->fetchrow;
 258
 259         $sth = $dbh->prepare("$select WHERE cardnumber=?");
 260         $sth->execute($arg);
 261         $debug and printf STDERR "Cardnumber '$arg' exists_local? %s\n", $sth->rows;
 262         ($sth->rows == 1) and return $sth->fetchrow;
 263         return 0;
 264 }
 265
 266 sub _do_changepassword {
 267     my ($userid, $borrowerid, $digest) = @_;
 268     $debug and print STDERR "changing local password for borrowernumber=$borrowerid to '$digest'\n";
 269     changepassword($userid, $borrowerid, $digest);
 270
 271         # Confirm changes
 272         my $sth = C4::Context->dbh->prepare("SELECT password,cardnumber FROM borrowers WHERE borrowernumber=? ");
 273         $sth->execute($borrowerid);
 274         if ($sth->rows) {
 275                 my ($md5password, $cardnum) = $sth->fetchrow;
 276         ($digest eq $md5password) and return $cardnum;
 277                 warn "Password mismatch after update to cardnumber=$cardnum (borrowernumber=$borrowerid)";
 278                 return;
 279         }
 280         die "Unexpected error after password update to userid/borrowernumber: $userid / $borrowerid.";
 281 }
 282
 283 sub update_local {
 284         my   $userid   = shift             or return;
 285         my   $digest   = md5_base64(shift) or return;
 286         my $borrowerid = shift             or return;
 287         my $borrower   = shift             or return;
 288         my @keys = keys %$borrower;
 289         my $dbh = C4::Context->dbh;
 290         my $query = "UPDATE  borrowers\nSET     " .
 291                 join(',', map {"$_=?"} @keys) .
 292                 "\nWHERE   borrowernumber=? ";
 293         my $sth = $dbh->prepare($query);
 294         if ($debug) {
 295                 print STDERR $query, "\n",
 296                         join "\n", map {"$_ = '" . $borrower->{$_} . "'"} @keys;
 297                 print STDERR "\nuserid = $userid\n";
 298         }
 299         $sth->execute(
 300                 ((map {$borrower->{$_}} @keys), $borrowerid)
 301         );
 302
 303         # MODIFY PASSWORD/LOGIN
 304         _do_changepassword($userid, $borrowerid, $digest);
 305 }
 306
 307 1;
 308 __END__
 309
 310 =head1 NAME
 311
 312 C4::Auth - Authenticates Koha users
 313
 314 =head1 SYNOPSIS
 315
 316   use C4::Auth_with_ldap;
 317
 318 =head1 LDAP Configuration
 319
 320     This module is specific to LDAP authentification. It requires Net::LDAP package and one or more
 321         working LDAP servers.
 322         To use it :
 323            * Modify ldapserver element in KOHA_CONF
 324            * Establish field mapping in <mapping> element.
 325
 326         For example, if your user records are stored according to the inetOrgPerson schema, RFC#2798,
 327         the username would match the "uid" field, and the password should match the "userpassword" field.
 328
 329         Make sure that ALL required fields are populated by your LDAP database (and mapped in KOHA_CONF).
 330         What are the required fields?  Well, in mysql you can check the database table "borrowers" like this:
 331
 332         mysql> show COLUMNS from borrowers;
 333                 +---------------------+--------------+------+-----+---------+----------------+
 334                 | Field               | Type         | Null | Key | Default | Extra          |
 335                 +---------------------+--------------+------+-----+---------+----------------+
 336                 | borrowernumber      | int(11)      | NO   | PRI | NULL    | auto_increment |
 337                 | cardnumber          | varchar(16)  | YES  | UNI | NULL    |                |
 338                 | surname             | mediumtext   | NO   |     | NULL    |                |
 339                 | firstname           | text         | YES  |     | NULL    |                |
 340                 | title               | mediumtext   | YES  |     | NULL    |                |
 341                 | othernames          | mediumtext   | YES  |     | NULL    |                |
 342                 | initials            | text         | YES  |     | NULL    |                |
 343                 | streetnumber        | varchar(10)  | YES  |     | NULL    |                |
 344                 | streettype          | varchar(50)  | YES  |     | NULL    |                |
 345                 | address             | mediumtext   | NO   |     | NULL    |                |
 346                 | address2            | text         | YES  |     | NULL    |                |
 347                 | city                | mediumtext   | NO   |     | NULL    |                |
 348                 | state               | mediumtext   | YES  |     | NULL    |                |
 349                 | zipcode             | varchar(25)  | YES  |     | NULL    |                |
 350                 | country             | text         | YES  |     | NULL    |                |
 351                 | email               | mediumtext   | YES  |     | NULL    |                |
 352                 | phone               | text         | YES  |     | NULL    |                |
 353                 | mobile              | varchar(50)  | YES  |     | NULL    |                |
 354                 | fax                 | mediumtext   | YES  |     | NULL    |                |
 355                 | emailpro            | text         | YES  |     | NULL    |                |
 356                 | phonepro            | text         | YES  |     | NULL    |                |
 357                 | B_streetnumber      | varchar(10)  | YES  |     | NULL    |                |
 358                 | B_streettype        | varchar(50)  | YES  |     | NULL    |                |
 359                 | B_address           | varchar(100) | YES  |     | NULL    |                |
 360                 | B_address2          | text         | YES  |     | NULL    |                |
 361                 | B_city              | mediumtext   | YES  |     | NULL    |                |
 362                 | B_state             | mediumtext   | YES  |     | NULL    |                |
 363                 | B_zipcode           | varchar(25)  | YES  |     | NULL    |                |
 364                 | B_country           | text         | YES  |     | NULL    |                |
 365                 | B_email             | text         | YES  |     | NULL    |                |
 366                 | B_phone             | mediumtext   | YES  |     | NULL    |                |
 367                 | dateofbirth         | date         | YES  |     | NULL    |                |
 368                 | branchcode          | varchar(10)  | NO   | MUL |         |                |
 369                 | categorycode        | varchar(10)  | NO   | MUL |         |                |
 370                 | dateenrolled        | date         | YES  |     | NULL    |                |
 371                 | dateexpiry          | date         | YES  |     | NULL    |                |
 372                 | gonenoaddress       | tinyint(1)   | YES  |     | NULL    |                |
 373                 | lost                | tinyint(1)   | YES  |     | NULL    |                |
 374                 | debarred            | date         | YES  |     | NULL    |                |
 375                 | debarredcomment     | varchar(255) | YES  |     | NULL    |                |
 376                 | contactname         | mediumtext   | YES  |     | NULL    |                |
 377                 | contactfirstname    | text         | YES  |     | NULL    |                |
 378                 | contacttitle        | text         | YES  |     | NULL    |                |
 379                 | guarantorid         | int(11)      | YES  | MUL | NULL    |                |
 380                 | borrowernotes       | mediumtext   | YES  |     | NULL    |                |
 381                 | relationship        | varchar(100) | YES  |     | NULL    |                |
 382                 | ethnicity           | varchar(50)  | YES  |     | NULL    |                |
 383                 | ethnotes            | varchar(255) | YES  |     | NULL    |                |
 384                 | sex                 | varchar(1)   | YES  |     | NULL    |                |
 385                 | password            | varchar(30)  | YES  |     | NULL    |                |
 386                 | flags               | int(11)      | YES  |     | NULL    |                |
 387                 | userid              | varchar(30)  | YES  | MUL | NULL    |                |
 388                 | opacnote            | mediumtext   | YES  |     | NULL    |                |
 389                 | contactnote         | varchar(255) | YES  |     | NULL    |                |
 390                 | sort1               | varchar(80)  | YES  |     | NULL    |                |
 391                 | sort2               | varchar(80)  | YES  |     | NULL    |                |
 392                 | altcontactfirstname | varchar(255) | YES  |     | NULL    |                |
 393                 | altcontactsurname   | varchar(255) | YES  |     | NULL    |                |
 394                 | altcontactaddress1  | varchar(255) | YES  |     | NULL    |                |
 395                 | altcontactaddress2  | varchar(255) | YES  |     | NULL    |                |
 396                 | altcontactaddress3  | varchar(255) | YES  |     | NULL    |                |
 397                 | altcontactstate     | mediumtext   | YES  |     | NULL    |                |
 398                 | altcontactzipcode   | varchar(50)  | YES  |     | NULL    |                |
 399                 | altcontactcountry   | text         | YES  |     | NULL    |                |
 400                 | altcontactphone     | varchar(50)  | YES  |     | NULL    |                |
 401                 | smsalertnumber      | varchar(50)  | YES  |     | NULL    |                |
 402                 | privacy             | int(11)      | NO   |     | 1       |                |
 403                 +---------------------+--------------+------+-----+---------+----------------+
 404                 66 rows in set (0.00 sec)
 405                 Where Null="NO", the field is required.
 406
 407 =head1 KOHA_CONF and field mapping
 408
 409 Example XML stanza for LDAP configuration in KOHA_CONF.
 410
 411  <config>
 412   ...
 413   <useldapserver>1</useldapserver>
 414   <!-- LDAP SERVER (optional) -->
 415   <ldapserver id="ldapserver">
 416     <hostname>localhost</hostname>
 417     <base>dc=metavore,dc=com</base>
 418     <user>cn=Manager,dc=metavore,dc=com</user>             <!-- DN, if not anonymous -->
 419     <pass>metavore</pass>          <!-- password, if not anonymous -->
 420     <replicate>1</replicate>       <!-- add new users from LDAP to Koha database -->
 421     <update>1</update>             <!-- update existing users in Koha database -->
 422     <auth_by_bind>0</auth_by_bind> <!-- set to 1 to authenticate by binding instead of
 423                                         password comparison, e.g., to use Active Directory -->
 424     <mapping>                  <!-- match koha SQL field names to your LDAP record field names -->
 425       <firstname    is="givenname"      ></firstname>
 426       <surname      is="sn"             ></surname>
 427       <address      is="postaladdress"  ></address>
 428       <city         is="l"              >Athens, OH</city>
 429       <zipcode      is="postalcode"     ></zipcode>
 430       <branchcode   is="branch"         >MAIN</branchcode>
 431       <userid       is="uid"            ></userid>
 432       <password     is="userpassword"   ></password>
 433       <email        is="mail"           ></email>
 434       <categorycode is="employeetype"   >PT</categorycode>
 435       <phone        is="telephonenumber"></phone>
 436     </mapping>
 437   </ldapserver>
 438  </config>
 439
 440 The <mapping> subelements establish the relationship between mysql fields and LDAP attributes. The element name
 441 is the column in mysql, with the "is" characteristic set to the LDAP attribute name.  Optionally, any content
 442 between the element tags is taken as the default value.  In this example, the default categorycode is "PT" (for
 443 patron).
 444
 445 =head1 CONFIGURATION
 446
 447 Once a user has been accepted by the LDAP server, there are several possibilities for how Koha will behave, depending on
 448 your configuration and the presence of a matching Koha user in your local DB:
 449
 450                          LOCAL_USER
 451  OPTION UPDATE REPLICATE  EXISTS?  RESULT
 452    A1      1       1        1      OK : We're updating them anyway.
 453    A2      1       1        0      OK : We're adding them anyway.
 454    B1      1       0        1      OK : We update them.
 455    B2      1       0        0     FAIL: We cannot add new user.
 456    C1      0       1        1      OK : We do nothing.  (maybe should update password?)
 457    C2      0       1        0      OK : We add the new user.
 458    D1      0       0        1      OK : We do nothing.  (maybe should update password?)
 459    D2      0       0        0     FAIL: We cannot add new user.
 460
 461 Note: failure here just means that Koha will fallback to checking the local DB.  That is, a given user could login with
 462 their LDAP password OR their local one.  If this is a problem, then you should enable update and supply a mapping for
 463 password.  Then the local value will be updated at successful LDAP login and the passwords will be synced.
 464
 465 If you choose NOT to update local users, the borrowers table will not be affected at all.
 466 Note that this means that patron passwords may appear to change if LDAP is ever disabled, because
 467 the local table never contained the LDAP values.
 468
 469 =head2 auth_by_bind
 470
 471 Binds as the user instead of retrieving their record.  Recommended if update disabled.
 472
 473 =head2 principal_name
 474
 475 Provides an optional sprintf-style format for manipulating the userid before the bind.
 476 Even though the userPrincipalName is one intended target, any uniquely identifying
 477 attribute that the server allows to be used for binding could be used.
 478
 479 Currently, principal_name only operates when auth_by_bind is enabled.
 480
 481 =head2 Active Directory
 482
 483 The auth_by_bind and principal_name settings are recommended for Active Directory.
 484
 485 Under default Active Directory rules, we cannot determine the distinguishedName attribute from the Koha userid as reliably as
 486 we would typically under openldap.  Instead of:
 487
 488     distinguishedName: CN=barnes.7,DC=my_company,DC=com
 489
 490 We might get:
 491
 492     distinguishedName: CN=Barnes\, Jim,OU=Test Accounts,OU=User Accounts,DC=my_company,DC=com
 493
 494 Matching that would require us to know more info about the account (firstname, surname) and to include punctuation and whitespace
 495 in Koha userids.  But the userPrincipalName should be consistent, something like:
 496
 497     userPrincipalName: barnes.7@my_company.com
 498
 499 Therefore it is often easier to bind to Active Directory with userPrincipalName, effectively the
 500 canonical email address for that user, or what it would be if email were enabled for them.  If Koha userid values
 501 will match the username portion of the userPrincipalName, and the domain suffix is the same for all users, then use principal_name
 502 like this:
 503     <principal_name>%s@core.my_company.com</principal_name>
 504
 505 The user of the previous example, barnes.7, would then attempt to bind as:
 506     barnes.7@core.my_company.com
 507
 508 =head1 SEE ALSO
 509
 510 CGI(3)
 511
 512 Net::LDAP()
 513
 514 XML::Simple()
 515
 516 Digest::MD5(3)
 517
 518 sprintf()
 519
 520 =cut
 521
 522 # For reference, here's an important difference in the data structure we rely on.
 523 # ========================================
 524 # Using attrs instead of {asn}->attributes
 525 # ========================================
 526 #
 527 #       LDAP key: ->{             cn} = ARRAY w/ 3 members.
 528 #       LDAP key: ->{             cn}->{           sss} = sss
 529 #       LDAP key: ->{             cn}->{   Steve Smith} = Steve Smith
 530 #       LDAP key: ->{             cn}->{Steve S. Smith} = Steve S. Smith
 531 #
 532 #       LDAP key: ->{      givenname} = ARRAY w/ 1 members.
 533 #       LDAP key: ->{      givenname}->{Steve} = Steve
 534 #