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 Carp;
  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::Auth qw(checkpw_internal);
  30 use Koha::AuthUtils qw(hash_password);
  31 use List::MoreUtils qw( any );
  32 use Net::LDAP;
  33 use Net::LDAP::Filter;
  34
  35 use vars qw($VERSION @ISA @EXPORT @EXPORT_OK %EXPORT_TAGS $debug);
  36
  37 BEGIN {
  38         require Exporter;
  39     $VERSION = 3.07.00.049;     # set the version for version checking
  40         @ISA    = qw(Exporter);
  41         @EXPORT = qw( checkpw_ldap );
  42 }
  43
  44 # Redefine checkpw_ldap:
  45 # connect to LDAP (named or anonymous)
  46 # ~ retrieves $userid from KOHA_CONF mapping
  47 # ~ then compares $password with userPassword
  48 # ~ then gets the LDAP entry
  49 # ~ and calls the memberadd if necessary
  50
  51 sub ldapserver_error {
  52         return sprintf('No ldapserver "%s" defined in KOHA_CONF: ' . $ENV{KOHA_CONF}, shift);
  53 }
  54
  55 use vars qw($mapping @ldaphosts $base $ldapname $ldappassword);
  56 my $context = C4::Context->new()        or die 'C4::Context->new failed';
  57 my $ldap = C4::Context->config("ldapserver") or die 'No "ldapserver" in server hash from KOHA_CONF: ' . $ENV{KOHA_CONF};
  58 my $prefhost  = $ldap->{hostname}       or die ldapserver_error('hostname');
  59 my $base      = $ldap->{base}           or die ldapserver_error('base');
  60 $ldapname     = $ldap->{user}           ;
  61 $ldappassword = $ldap->{pass}           ;
  62 our %mapping  = %{$ldap->{mapping}}; # FIXME dpavlin -- don't die because of || (); from 6eaf8511c70eb82d797c941ef528f4310a15e9f9
  63 my @mapkeys = keys %mapping;
  64 $debug and print STDERR "Got ", scalar(@mapkeys), " ldap mapkeys (  total  ): ", join ' ', @mapkeys, "\n";
  65 @mapkeys = grep {defined $mapping{$_}->{is}} @mapkeys;
  66 $debug and print STDERR "Got ", scalar(@mapkeys), " ldap mapkeys (populated): ", join ' ', @mapkeys, "\n";
  67
  68 my %config = (
  69         anonymous => ($ldapname and $ldappassword) ? 0 : 1,
  70     replicate => defined($ldap->{replicate}) ? $ldap->{replicate} : 1,  #    add from LDAP to Koha database for new user
  71        update => defined($ldap->{update}   ) ? $ldap->{update}    : 1,  # update from LDAP to Koha database for existing user
  72 );
  73
  74 sub description {
  75         my $result = shift or return;
  76         return "LDAP error #" . $result->code
  77                         . ": " . $result->error_name . "\n"
  78                         . "# " . $result->error_text . "\n";
  79 }
  80
  81 sub search_method {
  82     my $db     = shift or return;
  83     my $userid = shift or return;
  84         my $uid_field = $mapping{userid}->{is} or die ldapserver_error("mapping for 'userid'");
  85         my $filter = Net::LDAP::Filter->new("$uid_field=$userid") or die "Failed to create new Net::LDAP::Filter";
  86         my $search = $db->search(
  87                   base => $base,
  88                 filter => $filter,
  89                 # attrs => ['*'],
  90         ) or die "LDAP search failed to return object.";
  91         my $count = $search->count;
  92         if ($search->code > 0) {
  93                 warn sprintf("LDAP Auth rejected : %s gets %d hits\n", $filter->as_string, $count) . description($search);
  94                 return 0;
  95         }
  96         if ($count != 1) {
  97                 warn sprintf("LDAP Auth rejected : %s gets %d hits\n", $filter->as_string, $count);
  98                 return 0;
  99         }
 100     return $search;
 101 }
 102
 103 sub checkpw_ldap {
 104     my ($dbh, $userid, $password) = @_;
 105     my @hosts = split(',', $prefhost);
 106     my $db = Net::LDAP->new(\@hosts);
 107     unless ( $db ) {
 108         warn "LDAP connexion failed";
 109         return 0;
 110     }
 111
 112         #$debug and $db->debug(5);
 113     my $userldapentry;
 114
 115     if ( $ldap->{auth_by_bind} ) {
 116         my $principal_name;
 117         if ( $ldap->{anonymous_bind} ) {
 118
 119             # Perform an anonymous bind
 120             my $res = $db->bind;
 121             if ( $res->code ) {
 122                 warn "Anonymous LDAP bind failed: " . description($res);
 123                 return 0;
 124             }
 125
 126             # Perform a LDAP search for the given username
 127             my $search = search_method( $db, $userid )
 128               or return 0;    # warnings are in the sub
 129             $userldapentry = $search->shift_entry;
 130             $principal_name = $userldapentry->dn;
 131         }
 132         else {
 133             $principal_name = $ldap->{principal_name};
 134             if ( $principal_name and $principal_name =~ /\%/ ) {
 135                 $principal_name = sprintf( $principal_name, $userid );
 136             }
 137             else {
 138                 $principal_name = $userid;
 139             }
 140         }
 141
 142         # Perform a LDAP bind for the given username using the matched DN
 143         my $res = $db->bind( $principal_name, password => $password );
 144         if ( $res->code ) {
 145             warn "LDAP bind failed as kohauser $userid: " . description($res);
 146             return 0;
 147         }
 148         if ( !defined($userldapentry)
 149             && ( $config{update} or $config{replicate} ) )
 150         {
 151             my $search = search_method( $db, $userid ) or return 0;
 152             $userldapentry = $search->shift_entry;
 153         }
 154     } else {
 155                 my $res = ($config{anonymous}) ? $db->bind : $db->bind($ldapname, password=>$ldappassword);
 156                 if ($res->code) {               # connection refused
 157                         warn "LDAP bind failed as ldapuser " . ($ldapname || '[ANONYMOUS]') . ": " . description($res);
 158                         return 0;
 159                 }
 160         my $search = search_method($db, $userid) or return 0;   # warnings are in the sub
 161         $userldapentry = $search->shift_entry;
 162                 my $cmpmesg = $db->compare( $userldapentry, attr=>'userpassword', value => $password );
 163                 if ($cmpmesg->code != 6) {
 164                         warn "LDAP Auth rejected : invalid password for user '$userid'. " . description($cmpmesg);
 165                         return 0;
 166                 }
 167         }
 168
 169     # To get here, LDAP has accepted our user's login attempt.
 170     # But we still have work to do.  See perldoc below for detailed breakdown.
 171
 172     my (%borrower);
 173         my ($borrowernumber,$cardnumber,$local_userid,$savedpw) = exists_local($userid);
 174
 175     if (( $borrowernumber and $config{update}   ) or
 176         (!$borrowernumber and $config{replicate})   ) {
 177         %borrower = ldap_entry_2_hash($userldapentry,$userid);
 178         $debug and print STDERR "checkpw_ldap received \%borrower w/ " . keys(%borrower), " keys: ", join(' ', keys %borrower), "\n";
 179     }
 180
 181     if ($borrowernumber) {
 182         if ($config{update}) { # A1, B1
 183             my $c2 = &update_local($local_userid,$password,$borrowernumber,\%borrower) || '';
 184             ($cardnumber eq $c2) or warn "update_local returned cardnumber '$c2' instead of '$cardnumber'";
 185         } else { # C1, D1
 186             # maybe update just the password?
 187                 return(1, $cardnumber, $local_userid);
 188         }
 189     } elsif ($config{replicate}) { # A2, C2
 190         $borrowernumber = AddMember(%borrower) or die "AddMember failed";
 191    } else {
 192         return 0;   # B2, D2
 193     }
 194     if (C4::Context->preference('ExtendedPatronAttributes') && $borrowernumber && ($config{update} ||$config{replicate})) {
 195         my @extended_patron_attributes;
 196         foreach my $attribute_type ( C4::Members::AttributeTypes::GetAttributeTypes() ) {
 197             my $code = $attribute_type->{code};
 198             if ( exists($borrower{$code}) && $borrower{$code} !~ m/^\s*$/ ) { # skip empty values
 199                 push @extended_patron_attributes, { code => $code, value => $borrower{$code} };
 200             }
 201         }
 202         #Check before add
 203         my @unique_attr;
 204         foreach my $attr ( @extended_patron_attributes ) {
 205             if (C4::Members::Attributes::CheckUniqueness($attr->{code}, $attr->{value}, $borrowernumber)) {
 206                 push @unique_attr, $attr;
 207             } else {
 208                 warn "ERROR_extended_unique_id_failed $attr->{code} $attr->{value}";
 209             }
 210         }
 211         C4::Members::Attributes::SetBorrowerAttributes($borrowernumber, \@unique_attr);
 212     }
 213 return(1, $cardnumber, $userid);
 214 }
 215
 216 # Pass LDAP entry object and local cardnumber (userid).
 217 # Returns borrower hash.
 218 # Edit KOHA_CONF so $memberhash{'xxx'} fits your ldap structure.
 219 # Ensure that mandatory fields are correctly filled!
 220 #
 221 sub ldap_entry_2_hash {
 222         my $userldapentry = shift;
 223         my %borrower = ( cardnumber => shift );
 224         my %memberhash;
 225         $userldapentry->exists('uid');  # This is bad, but required!  By side-effect, this initializes the attrs hash.
 226         if ($debug) {
 227                 foreach (keys %$userldapentry) {
 228                         print STDERR "\n\nLDAP key: $_\t", sprintf('(%s)', ref $userldapentry->{$_}), "\n";
 229                 }
 230         }
 231         my $x = $userldapentry->{attrs} or return;
 232         foreach (keys %$x) {
 233                 $memberhash{$_} = join ' ', @{$x->{$_}};
 234                 $debug and print STDERR sprintf("building \$memberhash{%s} = ", $_, join(' ', @{$x->{$_}})), "\n";
 235         }
 236         $debug and print STDERR "Finsihed \%memberhash has ", scalar(keys %memberhash), " keys\n",
 237                                         "Referencing \%mapping with ", scalar(keys %mapping), " keys\n";
 238         foreach my $key (keys %mapping) {
 239                 my  $data = $memberhash{ lc($mapping{$key}->{is}) }; # Net::LDAP returns all names in lowercase
 240                 $debug and printf STDERR "mapping %20s ==> %-20s (%s)\n", $key, $mapping{$key}->{is}, $data;
 241                 unless (defined $data) {
 242                         $data = $mapping{$key}->{content} || '';        # default or failsafe ''
 243                 }
 244                 $borrower{$key} = ($data ne '') ? $data : ' ' ;
 245         }
 246         $borrower{initials} = $memberhash{initials} ||
 247                 ( substr($borrower{'firstname'},0,1)
 248                 . substr($borrower{ 'surname' },0,1)
 249                 . " ");
 250
 251         # check if categorycode exists, if not, fallback to default from koha-conf.xml
 252         my $dbh = C4::Context->dbh;
 253         my $sth = $dbh->prepare("SELECT categorycode FROM categories WHERE categorycode = ?");
 254         $sth->execute( uc($borrower{'categorycode'}) );
 255         unless ( my $row = $sth->fetchrow_hashref ) {
 256                 my $default = $mapping{'categorycode'}->{content};
 257                 $debug && warn "Can't find ", $borrower{'categorycode'}, " default to: $default for ", $borrower{userid};
 258                 $borrower{'categorycode'} = $default
 259         }
 260
 261         return %borrower;
 262 }
 263
 264 sub exists_local {
 265         my $arg = shift;
 266         my $dbh = C4::Context->dbh;
 267         my $select = "SELECT borrowernumber,cardnumber,userid,password FROM borrowers ";
 268
 269         my $sth = $dbh->prepare("$select WHERE userid=?");      # was cardnumber=?
 270         $sth->execute($arg);
 271         $debug and printf STDERR "Userid '$arg' exists_local? %s\n", $sth->rows;
 272         ($sth->rows == 1) and return $sth->fetchrow;
 273
 274         $sth = $dbh->prepare("$select WHERE cardnumber=?");
 275         $sth->execute($arg);
 276         $debug and printf STDERR "Cardnumber '$arg' exists_local? %s\n", $sth->rows;
 277         ($sth->rows == 1) and return $sth->fetchrow;
 278         return 0;
 279 }
 280
 281 sub _do_changepassword {
 282     my ($userid, $borrowerid, $password) = @_;
 283
 284     my $digest = hash_password($password);
 285
 286     $debug and print STDERR "changing local password for borrowernumber=$borrowerid to '$digest'\n";
 287     changepassword($userid, $borrowerid, $digest);
 288
 289     my ($ok, $cardnum) = checkpw_internal(C4::Context->dbh, $userid, $password);
 290     return $cardnum if $ok;
 291
 292     warn "Password mismatch after update to borrowernumber=$borrowerid";
 293     return;
 294 }
 295
 296 sub update_local {
 297     my $userid     = shift or croak "No userid";
 298     my $password   = shift or croak "No password";
 299     my $borrowerid = shift or croak "No borrowerid";
 300     my $borrower   = shift or croak "No borrower record";
 301
 302     my @keys = keys %$borrower;
 303     my $dbh = C4::Context->dbh;
 304     my $query = "UPDATE  borrowers\nSET     " .
 305         join(',', map {"$_=?"} @keys) .
 306         "\nWHERE   borrowernumber=? ";
 307     my $sth = $dbh->prepare($query);
 308     if ($debug) {
 309         print STDERR $query, "\n",
 310             join "\n", map {"$_ = '" . $borrower->{$_} . "'"} @keys;
 311         print STDERR "\nuserid = $userid\n";
 312     }
 313     $sth->execute(
 314         ((map {$borrower->{$_}} @keys), $borrowerid)
 315     );
 316
 317     # MODIFY PASSWORD/LOGIN
 318     _do_changepassword($userid, $borrowerid, $password);
 319 }
 320
 321 1;
 322 __END__
 323
 324 =head1 NAME
 325
 326 C4::Auth - Authenticates Koha users
 327
 328 =head1 SYNOPSIS
 329
 330   use C4::Auth_with_ldap;
 331
 332 =head1 LDAP Configuration
 333
 334     This module is specific to LDAP authentification. It requires Net::LDAP package and one or more
 335         working LDAP servers.
 336         To use it :
 337            * Modify ldapserver element in KOHA_CONF
 338            * Establish field mapping in <mapping> element.
 339
 340         For example, if your user records are stored according to the inetOrgPerson schema, RFC#2798,
 341         the username would match the "uid" field, and the password should match the "userpassword" field.
 342
 343         Make sure that ALL required fields are populated by your LDAP database (and mapped in KOHA_CONF).
 344         What are the required fields?  Well, in mysql you can check the database table "borrowers" like this:
 345
 346         mysql> show COLUMNS from borrowers;
 347                 +---------------------+--------------+------+-----+---------+----------------+
 348                 | Field               | Type         | Null | Key | Default | Extra          |
 349                 +---------------------+--------------+------+-----+---------+----------------+
 350                 | borrowernumber      | int(11)      | NO   | PRI | NULL    | auto_increment |
 351                 | cardnumber          | varchar(16)  | YES  | UNI | NULL    |                |
 352                 | surname             | mediumtext   | NO   |     | NULL    |                |
 353                 | firstname           | text         | YES  |     | NULL    |                |
 354                 | title               | mediumtext   | YES  |     | NULL    |                |
 355                 | othernames          | mediumtext   | YES  |     | NULL    |                |
 356                 | initials            | text         | YES  |     | NULL    |                |
 357                 | streetnumber        | varchar(10)  | YES  |     | NULL    |                |
 358                 | streettype          | varchar(50)  | YES  |     | NULL    |                |
 359                 | address             | mediumtext   | NO   |     | NULL    |                |
 360                 | address2            | text         | YES  |     | NULL    |                |
 361                 | city                | mediumtext   | NO   |     | NULL    |                |
 362                 | state               | mediumtext   | YES  |     | NULL    |                |
 363                 | zipcode             | varchar(25)  | YES  |     | NULL    |                |
 364                 | country             | text         | YES  |     | NULL    |                |
 365                 | email               | mediumtext   | YES  |     | NULL    |                |
 366                 | phone               | text         | YES  |     | NULL    |                |
 367                 | mobile              | varchar(50)  | YES  |     | NULL    |                |
 368                 | fax                 | mediumtext   | YES  |     | NULL    |                |
 369                 | emailpro            | text         | YES  |     | NULL    |                |
 370                 | phonepro            | text         | YES  |     | NULL    |                |
 371                 | B_streetnumber      | varchar(10)  | YES  |     | NULL    |                |
 372                 | B_streettype        | varchar(50)  | YES  |     | NULL    |                |
 373                 | B_address           | varchar(100) | YES  |     | NULL    |                |
 374                 | B_address2          | text         | YES  |     | NULL    |                |
 375                 | B_city              | mediumtext   | YES  |     | NULL    |                |
 376                 | B_state             | mediumtext   | YES  |     | NULL    |                |
 377                 | B_zipcode           | varchar(25)  | YES  |     | NULL    |                |
 378                 | B_country           | text         | YES  |     | NULL    |                |
 379                 | B_email             | text         | YES  |     | NULL    |                |
 380                 | B_phone             | mediumtext   | YES  |     | NULL    |                |
 381                 | dateofbirth         | date         | YES  |     | NULL    |                |
 382                 | branchcode          | varchar(10)  | NO   | MUL |         |                |
 383                 | categorycode        | varchar(10)  | NO   | MUL |         |                |
 384                 | dateenrolled        | date         | YES  |     | NULL    |                |
 385                 | dateexpiry          | date         | YES  |     | NULL    |                |
 386                 | gonenoaddress       | tinyint(1)   | YES  |     | NULL    |                |
 387                 | lost                | tinyint(1)   | YES  |     | NULL    |                |
 388                 | debarred            | date         | YES  |     | NULL    |                |
 389                 | debarredcomment     | varchar(255) | YES  |     | NULL    |                |
 390                 | contactname         | mediumtext   | YES  |     | NULL    |                |
 391                 | contactfirstname    | text         | YES  |     | NULL    |                |
 392                 | contacttitle        | text         | YES  |     | NULL    |                |
 393                 | guarantorid         | int(11)      | YES  | MUL | NULL    |                |
 394                 | borrowernotes       | mediumtext   | YES  |     | NULL    |                |
 395                 | relationship        | varchar(100) | YES  |     | NULL    |                |
 396                 | ethnicity           | varchar(50)  | YES  |     | NULL    |                |
 397                 | ethnotes            | varchar(255) | YES  |     | NULL    |                |
 398                 | sex                 | varchar(1)   | YES  |     | NULL    |                |
 399                 | password            | varchar(30)  | YES  |     | NULL    |                |
 400                 | flags               | int(11)      | YES  |     | NULL    |                |
 401                 | userid              | varchar(30)  | YES  | MUL | NULL    |                |
 402                 | opacnote            | mediumtext   | YES  |     | NULL    |                |
 403                 | contactnote         | varchar(255) | YES  |     | NULL    |                |
 404                 | sort1               | varchar(80)  | YES  |     | NULL    |                |
 405                 | sort2               | varchar(80)  | YES  |     | NULL    |                |
 406                 | altcontactfirstname | varchar(255) | YES  |     | NULL    |                |
 407                 | altcontactsurname   | varchar(255) | YES  |     | NULL    |                |
 408                 | altcontactaddress1  | varchar(255) | YES  |     | NULL    |                |
 409                 | altcontactaddress2  | varchar(255) | YES  |     | NULL    |                |
 410                 | altcontactaddress3  | varchar(255) | YES  |     | NULL    |                |
 411                 | altcontactstate     | mediumtext   | YES  |     | NULL    |                |
 412                 | altcontactzipcode   | varchar(50)  | YES  |     | NULL    |                |
 413                 | altcontactcountry   | text         | YES  |     | NULL    |                |
 414                 | altcontactphone     | varchar(50)  | YES  |     | NULL    |                |
 415                 | smsalertnumber      | varchar(50)  | YES  |     | NULL    |                |
 416                 | privacy             | int(11)      | NO   |     | 1       |                |
 417                 +---------------------+--------------+------+-----+---------+----------------+
 418                 66 rows in set (0.00 sec)
 419                 Where Null="NO", the field is required.
 420
 421 =head1 KOHA_CONF and field mapping
 422
 423 Example XML stanza for LDAP configuration in KOHA_CONF.
 424
 425  <config>
 426   ...
 427   <useldapserver>1</useldapserver>
 428   <!-- LDAP SERVER (optional) -->
 429   <ldapserver id="ldapserver">
 430     <hostname>localhost</hostname>
 431     <base>dc=metavore,dc=com</base>
 432     <user>cn=Manager,dc=metavore,dc=com</user>             <!-- DN, if not anonymous -->
 433     <pass>metavore</pass>          <!-- password, if not anonymous -->
 434     <replicate>1</replicate>       <!-- add new users from LDAP to Koha database -->
 435     <update>1</update>             <!-- update existing users in Koha database -->
 436     <auth_by_bind>0</auth_by_bind> <!-- set to 1 to authenticate by binding instead of
 437                                         password comparison, e.g., to use Active Directory -->
 438     <anonymous_bind>0</anonymous_bind> <!-- set to 1 if users should be searched using
 439                                             an anonymous bind, even when auth_by_bind is on -->
 440     <principal_name>%s@my_domain.com</principal_name>
 441                                    <!-- optional, for auth_by_bind: a printf format to make userPrincipalName from koha userid.
 442                                         Not used with anonymous_bind. -->
 443
 444     <mapping>                  <!-- match koha SQL field names to your LDAP record field names -->
 445       <firstname    is="givenname"      ></firstname>
 446       <surname      is="sn"             ></surname>
 447       <address      is="postaladdress"  ></address>
 448       <city         is="l"              >Athens, OH</city>
 449       <zipcode      is="postalcode"     ></zipcode>
 450       <branchcode   is="branch"         >MAIN</branchcode>
 451       <userid       is="uid"            ></userid>
 452       <password     is="userpassword"   ></password>
 453       <email        is="mail"           ></email>
 454       <categorycode is="employeetype"   >PT</categorycode>
 455       <phone        is="telephonenumber"></phone>
 456     </mapping>
 457   </ldapserver>
 458  </config>
 459
 460 The <mapping> subelements establish the relationship between mysql fields and LDAP attributes. The element name
 461 is the column in mysql, with the "is" characteristic set to the LDAP attribute name.  Optionally, any content
 462 between the element tags is taken as the default value.  In this example, the default categorycode is "PT" (for
 463 patron).
 464
 465 =head1 CONFIGURATION
 466
 467 Once a user has been accepted by the LDAP server, there are several possibilities for how Koha will behave, depending on
 468 your configuration and the presence of a matching Koha user in your local DB:
 469
 470                          LOCAL_USER
 471  OPTION UPDATE REPLICATE  EXISTS?  RESULT
 472    A1      1       1        1      OK : We're updating them anyway.
 473    A2      1       1        0      OK : We're adding them anyway.
 474    B1      1       0        1      OK : We update them.
 475    B2      1       0        0     FAIL: We cannot add new user.
 476    C1      0       1        1      OK : We do nothing.  (maybe should update password?)
 477    C2      0       1        0      OK : We add the new user.
 478    D1      0       0        1      OK : We do nothing.  (maybe should update password?)
 479    D2      0       0        0     FAIL: We cannot add new user.
 480
 481 Note: failure here just means that Koha will fallback to checking the local DB.  That is, a given user could login with
 482 their LDAP password OR their local one.  If this is a problem, then you should enable update and supply a mapping for
 483 password.  Then the local value will be updated at successful LDAP login and the passwords will be synced.
 484
 485 If you choose NOT to update local users, the borrowers table will not be affected at all.
 486 Note that this means that patron passwords may appear to change if LDAP is ever disabled, because
 487 the local table never contained the LDAP values.
 488
 489 =head2 auth_by_bind
 490
 491 Binds as the user instead of retrieving their record.  Recommended if update disabled.
 492
 493 =head2 principal_name
 494
 495 Provides an optional sprintf-style format for manipulating the userid before the bind.
 496 Even though the userPrincipalName is one intended target, any uniquely identifying
 497 attribute that the server allows to be used for binding could be used.
 498
 499 Currently, principal_name only operates when auth_by_bind is enabled.
 500
 501 =head2 Active Directory
 502
 503 The auth_by_bind and principal_name settings are recommended for Active Directory.
 504
 505 Under default Active Directory rules, we cannot determine the distinguishedName attribute from the Koha userid as reliably as
 506 we would typically under openldap.  Instead of:
 507
 508     distinguishedName: CN=barnes.7,DC=my_company,DC=com
 509
 510 We might get:
 511
 512     distinguishedName: CN=Barnes\, Jim,OU=Test Accounts,OU=User Accounts,DC=my_company,DC=com
 513
 514 Matching that would require us to know more info about the account (firstname, surname) and to include punctuation and whitespace
 515 in Koha userids.  But the userPrincipalName should be consistent, something like:
 516
 517     userPrincipalName: barnes.7@my_company.com
 518
 519 Therefore it is often easier to bind to Active Directory with userPrincipalName, effectively the
 520 canonical email address for that user, or what it would be if email were enabled for them.  If Koha userid values
 521 will match the username portion of the userPrincipalName, and the domain suffix is the same for all users, then use principal_name
 522 like this:
 523     <principal_name>%s@core.my_company.com</principal_name>
 524
 525 The user of the previous example, barnes.7, would then attempt to bind as:
 526     barnes.7@core.my_company.com
 527
 528 =head1 SEE ALSO
 529
 530 CGI(3)
 531
 532 Net::LDAP()
 533
 534 XML::Simple()
 535
 536 Digest::MD5(3)
 537
 538 sprintf()
 539
 540 =cut
 541
 542 # For reference, here's an important difference in the data structure we rely on.
 543 # ========================================
 544 # Using attrs instead of {asn}->attributes
 545 # ========================================
 546 #
 547 #       LDAP key: ->{             cn} = ARRAY w/ 3 members.
 548 #       LDAP key: ->{             cn}->{           sss} = sss
 549 #       LDAP key: ->{             cn}->{   Steve Smith} = Steve Smith
 550 #       LDAP key: ->{             cn}->{Steve S. Smith} = Steve S. Smith
 551 #
 552 #       LDAP key: ->{      givenname} = ARRAY w/ 1 members.
 553 #       LDAP key: ->{      givenname}->{Steve} = Steve
 554 #