3 # This is part of CGI::Auth::Flexible, a perl CGI authentication module.
5 # This program is free software: you can redistribute it and/or modify
6 # it under the terms of the GNU Affero General Public License as published by
7 # the Free Software Foundation, either version 3 of the License, or
8 # (at your option) any later version, with the "CAF Login Exception"
9 # as published by Ian Jackson (version 1, or at your option any
10 # later version) as an Additional Permission.
12 # This program is distributed in the hope that it will be useful,
13 # but WITHOUT ANY WARRANTY; without even the implied warranty of
14 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 # GNU Affero General Public License for more details.
20 CGI::Auth::Flexible - web authentication optionally using cookies
24 my $verifier = CGI::Auth::Flexible->new_verifier(setting => value,...);
25 my $authreq = $verifier->new_request($cgi);
28 $authreq->check_ok() or return;
30 # sophisticated applications
31 my $divert_kind = $authreq->check_divert();
32 if ($divert_kind) { ... print diversion page and quit ... }
34 # while handling the request
35 $user = $authreq->get_username();
36 $authreq->check_mutate();
40 CGI::Auth::Flexible is a library which you can use to add a
41 forms/cookie-based login facility to a Perl web application.
43 CGI::Auth::Flexible doesn't interfere with your application's URL path
44 namespace and just needs a few (configurable) form parameter and
45 cookie name(s) for its own use. It tries to avoid making assumptions
46 about the implementation structure of your application.
48 Because CGI::Auth::Flexible is licenced under the AGPLv3, you will
49 probably need to provide a facility to allow users (even ones not
50 logged in) to download the source code for your web app. Conveniently
51 by default CGI::Auth::Flexible provides (for pure Perl webapps) a
52 mechanism for users to get the source.
54 CGI::Auth::Flexible is designed to try to stop you accidentally
55 granting access by misunderstanding the API. (Also it, of course,
56 guards against cross-site scripting.) You do need to make sure to
57 call CGI::Auth::Flexible before answering AJAX requests as well as
58 before generating HTML pages, of course, and to call it in every
59 entrypoint to your system.
63 As a minimum you need to do all of the things on this checklist, where
64 applicable. The items marked SECURITY are the ones that you might
65 forget: without them your application may appear to work, but will be
72 Call C<new_verifier> (once at application startup)
76 Call C<new_request> (once per request)
80 B<SECURITY>: Call C<check_ok> or C<check_divert> on every request, and
81 honour the return value.
85 If you're using C<check_ok>, implement either the
86 C<username_password_error> or C<login_ok> hook and provide it as
87 a setting to C<new_verifier>.
91 Provide the setting C<dir> (or provide absolute paths for all the
92 other relevant settings).
96 Call C<get_username> when you need to know who's logged in.
100 B<SECURITY>: Call C<check_mutate> or C<mutate_ok>, if you specified
101 C<promise_check_mutate>.
105 B<SECURITY>: Call C<check_nonpage> for every request which is not a page load
106 (if your application has any of those).
110 When generating URLs and forms (including AJAX requests), include the
111 hidden form parameter using C<secret_hidden_val> or
112 C<secret_hidden_html> when appropriate (see below).
116 B<SECURITY>: If you do not override the source provision facility (see
117 L</SOURCE CODE DOWNLOAD>), check that the assumptions it makes aren't
118 going to leak security-critical data.
122 Set up HTTPS on your webserver, or set the C<encrypted_only> setting
127 These points will now be covered in more detail.
129 =head2 INITIALISATION
131 Your application should, on startup (eg, when it is loaded by
133 C<< $verifier = CGI::Auth::Flexible->new_verifier(settings...) >>.
134 This call can be expensive and is best amortised.
136 The resulting verifier object can be used to process individual
137 requests, in each case with
138 C<< $authreq = CGI::Auth::Flexible->new_request($cgi) >>.
142 =head2 CHECKING AND RESPONSE GENERATION
144 If the user is logged in, your application is to handle the request.
145 Otherwise, the user needs to be presented with a login form or error
146 message, as appropriate. CGI::Auth::Flexible provides two alternative
149 =head3 Simple applications
151 The simplest usage is to call C<< $request->check_ok() >> which will
152 check the user's authentication. If the user is not logged in it will
153 generate a login form (or redirection or other appropriate page) and
154 return false; your application should not then process that request
155 any further. If the user is logged in it will return true.
157 Various hooks are provided to customise the responses generated by
160 After C<check_ok> returns true you should go ahead and process the
161 request; you can use C<< $request->get_username >> to find out which
162 user the request came from.
163 You may also need to call C<check_mutate> and/or C<check_nonpage>
166 =head3 Sophisticated applications
168 If you want to handle the control flow and to generate login forms,
169 redirections, etc., yourself, you can say
170 C<< $divert = $request->check_divert >>. This returns undef if
171 the user is logged in, or a I<divert spec> if some kind of login
172 page or diversion should be generated. See L</DIVERT SPEC> below for
173 details of how to deal with the return value.
175 =head2 MUTATING OPERATIONS AND EXTERNAL LINKS
177 =head3 Mutation-ignorant applications
179 By default CGI::Auth::Flexible does not permit external deep links
181 All GET requests give a "click to continue" page which
182 submits a form which loads your app's main page. In this
183 configuration all your application's forms and AJAX requests should
186 Such applications are also not able to provide user-specific CSS
187 stylesheets, javascript, favicons, etc.
189 This restriction arises from complicated deficiencies
190 in the web's security architecture.
192 =head3 Mutation-aware applications
194 The alternative is for your application to always make a special check
195 when the incoming request is going to do some kind of action (such as
196 modifying the user's setup, purchasing goods, or whatever) rather than
197 just retrieve and/or display information. We term such requests
200 Then non-mutating pages can be linked to from other, untrustworthy,
203 To support external links, and C<GET> requests, pass
204 C<< promise_check_mutate => 1 >> in I<settings>, and then call
205 C<< $authreq->check_mutate() >> before taking any actions. If the
206 incoming request is not suitable then C<< $authreq->check_mutate() >>
209 There have to be no mutating C<GET> requests in your application (but
210 you shouldn't have any of those anyway); if there are, they won't
211 work. (CGI::Auth::Flexible will spot them and cause them to fail,
212 rather than allow them to be insecure.)
214 =head2 GENERATING URLS, FORMS AND AJAX QUERIES
216 When you generate a URL, C<POST> form or AJAX request you may need to
217 include a secret hidden form parameter for the benefit of
218 CGI::Auth::Generic. This form parameter will be checked by
219 C<check_ok>/C<check_divert> and should be ignored by your application.
221 By default the hidden parameter is called C<caf__assochash>.
223 After calling C<check_ok> or C<check_divert> the value to put in your
224 form can be obtained from C<secret_hidden_val>; C<secret_hidden_html>
225 will generate the whole HTML C<< <input...> >> element.
227 =head3 Mutation-ignorant applications
229 For mutation-ignorant applications (see above), all forms etc. should
230 include the hidden parameter (and as discussed, they must all use
231 POST rather than GET).
233 =head3 Mutation-aware applications
235 For mutation-aware applications, whether to include the secret
236 parameter depends on the kind of request. CGI::Auth::Flexible knows
237 when it is necessary. You should find out by calling
240 If it is inconvenient to call C<need_add_hidden> at runtime, you can
241 rely instead on the following promises: All POST requests (which
242 includes all mutating requests) need the parameter. The return value
243 of need_add_hidden depends only on the $method and $reqtype
244 parameters, so you can query it once and remember the answer.
245 HTML page load GETs do not need the parameter. It is better to
246 err on the side of including the parameter.
248 If you really must, you can call C<need_add_hidden> "on the bench"
249 during development and bake the answer into your application code
250 structure. However, if you do that and a new vulnerability was
251 discovered which is fixed by changing the answer, updating
252 CGI::Auth::Flexible wouldn't be sufficient to fix it.
254 =head3 Mutation-aware applications - non-page requests
256 If your mutation-aware application supports non-page resources (AJAX
257 and JSON requests, stylesheets, favicons, etc.) it must inform
258 CGI::Auth::Flexible when it is handling such a request, by calling
261 Normally C<check_nonpage> will simply return (and you can ignore the
262 return value). However, if there is an attack (or, perhaps, a bug) it
263 will die, stopping the attack.
265 (You do not need to call C<check_nonpage> for POST requests, but it is
268 =head3 Mutation-aware applications - novel kinds of request
270 If you want to support a kind of request perhaps not yet known about
271 by CGI::Auth::Flexible, you can provide information about that new
272 request kind using C<update_get_need_add_hidden>.
276 CGI::Auth::Flexible needs to store various information in plain files;
277 it does this in the directory specified by the C<dir> parameter.
279 =head1 SOURCE CODE DOWNLOAD
281 By default, CGI::Auth::Flexible provides a facility for users to
282 download the source code for the running version of your web
285 This facility makes a number of important assumptions which you need
286 to check. Note that if the provided facility is not sufficient
287 because your application is more sophisticated than it copes with (or
288 if you disable the builtin facility), you may need to implement a
289 functioning alternative to avoid violating the AGPLv3 licence.
291 Here are the most important (default) assumptions:
297 Your app's source code is available by looking at @INC, $0 and
298 S<$ENV{'SCRIPT_FILENAME'}> (the B<source items>). See
299 C<srcdump_listitems>. Where these point to files or directories under
300 revision control, the source item is the whole containing vcs tree.
304 Specifically, there are no compiled or autogenerated Perl
305 files, Javascript resources, etc., which are not contained in one of
306 the source item directories. (Files which came with your operating
307 system install don't need to be shipped as they fall under the system
312 You have not installed any modified versions of system
313 libraries (including system-supplied Perl modules) in C</usr> outside
314 C</usr/local>. See C<srcdump_system_dir>.
318 For each source item in a dvcs, the entire dvcs history does
319 not contain anything confidential (or libellous). Also, all files which
320 contain secrets are in the dvcs's I<.ignore> file. See
321 C<srcdump_vcsscript_git> et al.
325 For each source item NOT in a dvcs, there are no confidential
326 files with the world-readable bit set (being in a world-inaccessible
327 directory is not sufficient). See C<srcdump_excludes>.
331 You have none of your app's source code in C</etc>.
335 You don't regard pathnames on your server as secret.
339 You don't intentionally load Perl code by virtue of C<.>
340 being in C<@INC> by default. (See C<srcdump_filter_cwd>.)
344 =head1 MAIN FUNCTIONS AND METHODS
348 =item C<< CGI::Auth::Flexible->new_verifier(setting => value, ...) >>
350 Initialises an instance and returns a verifier object.
351 The arguments are setting pairs like a hash initialiser.
352 See L</SETTINGS> below.
354 =item C<< $verifier->new_request($cgi) >>
356 Prepares to process a request. I<$cgi> should normally
357 be the query object from L<CGI(3perl)>. Most of the default
358 hook methods assume that it is; however if you replace enough of
359 the hook methods then you can pass any value you like and it
360 will be passed to your hooks.
362 The return value is the authentication request object (I<$authreq>)
363 which is used to check the incoming request and will contain
364 information about its credentials.
366 =item C<< $authreq->check_divert() >>
368 Checks whether the user is logged in. Returns undef if the user is
369 logged in and we should service the request. Otherwise returns a
370 divert spec (see L</DIVERT SPEC>) saying what should happen instead.
372 This method may die if it doesn't like the request, in which case
373 the request needs to be rejected.
375 =item C<< $authreq->check_ok() >>
377 Checks whether the user is logged in. Returns true if the user is
378 logged in and we should service the request.
380 Otherwise it handles the request itself, generating any appropriate
381 redirect, login form, or continuation page. It then returns false and
382 the application should not process the request further.
384 =item C<< $verifier->disconnect() >>
386 Discards the resources (open files, etc.) in the verifier object.
390 =head1 REQUEST-RELATED FUNCTIONS AND METHODS
392 All of these are only valid after C<check_divert> or C<check_ok> has
393 been called. (In the case of C<check_ok> it won't normally be sensible
394 to call these functions unless C<check_ok> returned true.)
398 =item C<< $authreq->get_divert() >>
400 Returns the value previously returned by C<check_divert>.
402 =item C<< $authreq->get_username() >>
404 Returns the name of the logged-in user. If the user was not logged
405 in (or their session had timed out, or something), returns undef.
407 =item C<< $authreq->check_mutate() >>
409 Declares to CGI::Auth::Generic that the request being handled will
410 "mutate". That is, it will modify some server-side state (eg, adding
411 items to shopping baskets, posting messages to blogs, sending emails,
414 If you have set the setting C<promise_check_mutate> you must call
415 C<check_mutate> whenever appropriate. If you haven't then it's
416 irrelevant. See L<MUTATING OPERATIONS AND EXTERNAL LINKS>.
418 C<check_mutate> will either return successfully, indicating that all
419 is well and the request should proceed, or it will die. If it dies
420 that means that the request was improper, which can only result from a
421 bug or an attack. So an "internal server error" is a suitable
424 =item C<< $authreq->check_nonpage($method, $reqtype) >>
426 Declares to CGI::Auth::Generic that the request is not a page request,
427 but rather a request of type I<$reqtype>.
429 If your application has set the setting C<promise_check_mutate>,
430 whenever it is handling anything except an HTML page loads, it must
431 call this function. See L</REQUEST TYPES>, and
432 L<GENERATING URLS, FORMS AND AJAX QUERIES>.
434 C<check_nonpage> will either return successfully, indicating that all
435 is well and the request should proceed, or it will die, like
440 =head1 RESPONSE-RELATED FUNCTIONS AND METHODS
444 =item C<< $authreq->url_with_query_params($params, [$nonpagetype]) >>
446 Convenience function which returns a url for a GET request to this
449 I<$params> is a hashref specifying the parameters and the PATH_INFO
450 (not including any parameters related to CGI::Auth::Flexible).
451 The keys are the parameter names, and the values are array refs with
452 the parameter value(s) (as strings, as yet unquoted). (They are array
453 refs because it is possible to pass multiple values for the same
454 parameter in a single request; normally each arrayref would be a
457 The request path will be the path to the application. If a parameter
458 with name C<< '' >> is supplied, it is taken as the PATH_INFO - its
459 value will be appended to the application path. (It should normally
460 start with C<< / >>, and only one value should be supplied.)
462 =item C<< something->need_add_hidden($method, $reqtype) >>
464 Enquires whether a request of type I<$reqtype> using HTTP method
465 I<$method> needs the hidden form parameter. See L</REQUEST TYPES>.
467 =item C<< something->secret_hidden_val() >>
469 Returns the value of the hidden form parameter. This should be
470 included in all POST requests to your application (and thus be a
471 hidden form parameter in all forms).
473 It should also be in some (maybe all) GET requests. If your
474 application is mutation-ignorant, it should be in all GET requests.
475 If you are mutation-aware, you need to consult C<need_add_hidden>.
477 The name of the hidden parameter is the setting C<assoc_param_name>,
478 C<caf_hassochash> by default. xxx rename param and setting
480 =item C<< something->secret_hidden_html() >>
482 Returns the HTML for an C<INPUT> element specifying the hidden form
485 =item C<< something->secret_cookie_val() >>
487 Returns the value of the secret cookie. CGI::Auth::Flexible sets this
488 cookie in the forms generated by C<check_ok>. You may also set it
489 yourself (and indeed you must do so if you use C<check_divert>).
491 =item C<< $authreq->chain_params() >>
493 Returns a hash of the "relevant" parameters to this request, in a form
494 suitable for C<url_with_query_params>. This is all of the query
495 parameters which are not related to CGI::Auth::Flexible's authentication
496 arrangements. (The srcdump request parameters B<are> included.) The
497 PATH_INFO from the request is returned as the parameter C<< '' >>.
501 =head1 OTHER FUNCTIONS AND METHODS
505 =item C<< $verifier_or_authreq->hash($data) >>
507 Hashes the supplied data using the hash function specified by the
508 C<hash_algorithm> setting, and converts the result to a string of hex
511 =item C<< something->update_get_need_add_hidden($reqtype, $value, [$force]) >>
513 Updates CGI::Auth::Generic's knowledge about the various kinds of
514 request, and whether they need the hidden form parameter. This
515 function applies only to GET requests - POST requests always use the
518 I<$reqtype> is the request type (the value which will be passed to
519 C<check_nonpage> and C<need_add_hidden>. If you are supporting a new
520 I<$reqtype> you shouuld coordinate with CGI::Auth::Flexible upstream,
521 or other users, to assign a unique request type name.
523 This method may be called on an authreq or a verifier, in which case
524 it will affect all authreqs using the same verifier. Or it may be
525 called on the class as a whole, in which case it will affect the
526 global default list for all verifiers.
528 If I<$force> is supplied and true, this will override
529 CGI::Auth::Flexible's existing knowledge. Otherwise this new setting
530 will be ignored if CGI::Auth::Flexible already knows about the request
531 type. (When called on a verifier or authreq, it will ignore the
532 update in favour of existing knowledge recorded both globally in the
533 class or due to previous requests on the same verifier.)
535 See L</REQUEST TYPES>.
537 =item C<< CGI::Auth::Flexible::srcdump_dir_cpio($cgi,$verifier,$dumpdir,$dir,$outfn,$how,$script) >>
539 Helper function for implementing the C<srcdump_process_item> hook.
540 Generates a tarball using cpio and includes it in the prepared source
543 The arguments are mostly the same as for that hook. C<$dir> is the
544 root directory at which to start the archive. C<$how> is a short text
545 string which will be mentioned in the log.
547 C<$script> is a shell script fragment which must output a
548 nul-separated list of filenames (e.g. the output of C<find -print0>).
549 It is textually surrounded by C<( )> and will be executed with C<set -e>
550 in force. Its cwd will be C<$dir>.
552 =item C<< $verifier_or_authreq->($data) | CGI::Auth::Flexible-> >>
554 Hashes the supplied data using the hash function specified by the
555 C<hash_algorithm> setting, and converts the result to a string of hex
562 The C<$reqtype> values understood by C<check_nonpage> are strings.
569 A top-level HTML page load. May contain confidential information for
570 the benefit of the logged-in user.
574 An HTML frame. May contain confidential information for
575 the benefit of the logged-in user.
579 An HTML iframe. May contain confidential information for
580 the benefit of the logged-in user.
584 Source dump request, whether for the licence or actual source code
585 tarball; returned value is not secret.
589 CSS stylesheet. B<MUST NOT> contain any confidential data. If the
590 stylesheet depends on the user, then attackers may be able to
591 determine what stylesheet the user is using. Hopefully this is not a
596 "Favicon" - icon for display in the browser's url bar etc. We aren't
597 currently aware of a way that attackers can get a copy of this.
601 C<robots.txt>. Should not contain any confidential data (obviously).
605 Inline image, for an C<< <img src=...> >> element.
607 Unfortunately it is not possible to sensibly show top-level
608 confidential images (that is, have the user's browser directly visit a
609 url which resolves to an image rather than an HTML page with an inline
610 image). This is because images need to have a per-session hidden form
611 parameter to avoid cross-site scripting, which breaks bookmarks etc.
615 JavaScript for a C<< <script> >> element. (Possibly confidential for
620 C<< XMLHttpRequest >> returning XML data. (Possibly
621 confidential for the user.)
625 C<< XMLHttpRequest >> returning JSON data. (Possibly
626 confidential for the user.)
630 C<< XMLHttpRequest >> returning data of some other kind. (Possibly
631 confidential for the user.)
637 The return value from C<check_divert> indicates how the request should
638 be handled. It is C<undef> if all is well and the user is logged in.
640 Otherwise the return value is a hash ref with the following keys:
646 Scalar string indicating the kind of diversion required.
650 Scalar string for display to the user in relation to the diversion.
651 Has already been translated. In HTML but normally does not contain
654 =item C<CookieSecret>
656 The login cookie which should be set along with whatever response is
657 sent to the client. The value in the hash is the actual value
658 of the cookie as a string. C<undef> means no cookie setting header
659 should be sent; C<''> means the cookie should be cleared.
663 Provided with diversion kinds which involve
664 generating a redirection or indirection,
665 perhaps via a login form.
667 The extra hidden form parameters (and the C<PATH_INFO>) which should
668 be set when the subsequent request bounces back from the client, in
669 the form used by C<url_with_query_params>.
671 The contents of this hashref does not include the CAF-specific
672 parameters such as the secret cookie, those which follow from the kind
673 of diversion requested, etc. (But they may include the
674 srcdump_param_name, so that srcdump_needlogin can work properly.)
676 It is correct to always include the contents of C<Params> as hidden
677 parameters in the urls for all redirections, and as hidden input
678 fields in all generated forms. The specific cases where C<Params> is
679 currently relevant are also mentioned in the text for each divert
684 The values of C<Kind> are:
688 =item C<SRCDUMP->I<item>
690 We should respond by sending our application source code. I<item>
691 (which will contain only word characters, and no lower case) is the
692 specific item to send, normally C<SOURCE> or C<LICENCE>.
694 =item C<REDIRECT-HTTPS>
696 We should respond with an HTTP redirect to the HTTPS instance of our
699 =item C<REDIRECT-LOGGEDOUT>
701 We should redirect to a page showing that the user has been logged
702 out. (Ie, to a url with one of the the C<loggedout_param_names> set.)
704 =item C<SMALLPAGE-LOGGEDOUT>
706 We should generate a page showing that the user has been logged out.
707 There can be a link on the page pointing to the login page so that the
708 user can log back in.
710 =item C<SMALLPAGE-NOCOOKIE>
712 We should generate a page reporting that the user does not have
713 cookies enabled. It should probably contain a link pointing to the
714 login page with additionally all the parameters in C<Params>. When
715 this divert spec is generated, C<Message> will explain the problem
716 with cookies so there is no need to do that again in the page body if
717 you include the contents of C<Message>.
721 The user's session was stale (this is described in C<Message>). We
722 should generate a login form.
726 The user supplied bad login credentials. The details are in
727 C<Message>. We should generate a login form (with additionally the
728 parameters from C<Params> as hidden fields).
730 =item C<LOGIN-INCOMINGLINK>
732 We should generate a login form (with the specified parameters); the
733 user is entering the site via a cross-site link but is not yet logged
738 We should generate a login form. The user is not yet logged in.
740 =item C<REDIRECT-LOGGEDIN>
742 We should redirect to our actual application, with the specified
743 parameters. (The user has just logged in.)
747 The user is logged in but the incoming form submission looks like it
748 was from a stale login session. Alternatively, it may have been
749 generated by an attacker's cross-site-scripting attack.
751 Naive applications should generate a small page with a form or link to
752 our own main page without any parameters.
754 A sophisticated application could infer from the submitted form
755 parameters what the user was allegedly trying to do. We could then
756 generate a fresh page showing what the intended action was, with a
757 fresh form which (if the user confirm) would resubmit that action.
758 B<Great care> must be taken to avoid relying on the sanity and
759 coherence of the incoming form parameters. We B<MUST NOT> simply
760 reproduce the incoming parameters in the new form. It is essential
761 that the visual appearance of the generated form correctly shows to
762 the user what the action is that will be taken if the form is
763 submitted. If that action is dangerous, the form should not look like
764 the kind of confirmation pages which the user is likely to simply
765 click through without thinking.
767 =item C<MAINPAGEONLY>
769 We should generate our main page but B<ignoring all form parameters>
770 and B<ignoring the path_info>. Most applications will find this
771 difficult to implement.
773 An alternative is to generate a small page with a form or link which
774 submits our own main page without any parameters.
776 (Applications which set C<promise_check_mutate> do not see this divert
781 Applications should die if they are presented with a divert kind that
782 they don't recognise.
786 C<new_verifier> and C<new_request> each take a list of settings, as
787 a list of pairs C<< key => value >> (like a Perl hash assignment).
789 The settings supplied to C<new_verifier> are stored in the verifier
790 and will apply to all authreqs made from it unless overridden in the
791 call to C<new_request>
793 When a setting is described as a hook function, it should be a
794 coderef. The first argument will be the query object from
795 L<CGI(3perl)> (strictly, it will be whatever value was passed to
796 C<new_request>). The second argument will be the authreq object (the
797 return value from C<new_request>).
798 Ie, C<< sub some_hook ($$...) { my ($cgi,$authreq,@stuff) = @_ ... >>
800 In bullet point headings, the hook functions are shown in the form
801 C<< some_hook($cgi,$authreq,@stuff) >> even though this would not be
802 legal syntax. This should be read to mean that the
803 %implicit_settings_hash{'some_hook'}($cgi,$authreq,@stuff)
804 would be a legal call. (However, the settings hash is not exposed.)
806 When a hook's default implementation is mentioned and named, that
807 function won't also be described in the section on the module's
810 =head2 GENERAL SETTINGS
816 The directory CGI::Auth::Generic should use for its data storage.
817 This is actually just a default absolute path used when the other
818 path settings are relative values.
820 Must be an absolute filename.
824 CGI::Auth::Flexible needs a database for recording users' login
825 session. This database needs to be shared across all instances of the
826 web application, so in a multi-node cluster it needs to be your actual
829 CGI::Auth::Flexible will create the table and index it needs if they
830 don't already exist, and will manage their contents. You do not need
831 to integrate them into the rest of your webapp's data storage. (In
832 particular, there is no need for transactional integrity across
833 changes made by CAF and your own application.)
835 By default, CAF uses a sqlite3 database stored on local disk in the
836 file named by C<db_path>. This will be suitable for all
837 applications which run on a single host.
839 This value, if supplied, should be a DBI handle for the database.
843 This is the DSN to pass to C<< DBI->connect >>. Used only if
844 C<db_dbh> is not supplied.
848 Path to the sqlite3 database used for CAF's session storage. The
849 default is C<caf.db>.
851 Used only if neither C<db_dbh> or C<db_dsn> are supplied.
853 If this is a relative path, it is in C<dir>.
857 Prefix for the SQL tables and indices to use (and to create, if
860 See L</DATABASE TABLES>.
864 Path to the keys file used by CAF. This arrangement will change in
865 the future. See L</BUGS>.
867 =item C<random_source>
869 Special file to read random numbers from. Should return
870 cryptographically secure (pseudo)-random bytes, unpredictable to
871 adversaries (even ones on the same machine).
873 On Linux, there is no device which is properly suitable. This is a
874 bug in Linux. You can use C</dev/random> which can block
875 unnecessarily even though the kernel PRNG has been properly seeded and
876 is fine, or C</dev/urandom> which might return values which attackers
877 can predict if the kernel PRNG has not been properly seeded.
879 The default is C</dev/urandom>.
883 Length of the assoc secret. Defaults to 128.
885 =item C<hash_algorithm>
887 Must be a string suitable for use with C<new Digest>.
888 Defaults to C<SHA-256>.
890 =item C<login_timeout>
892 A user will be logged out this many seconds after they first logged
893 in. Default: 86400 (one day).
895 =item C<login_form_timeout>
897 A login form becomes invalid this many seconds after it has been sent.
898 Default: 3600 seconds (one hour).
900 =item C<key_rollover>
902 The key used for generating assoc secrets is rolled over approximately
903 this often (in seconds). Default: 86400.
905 =item C<assoc_param_name>
907 Name of the hidden form parameter. Default: C<caf_assochash>.
911 Name of the cookie used for login sessions. Default:
914 =item C<password_param_name>
916 Name of the password field in the login form. Default: C<password>.
918 Used by C<login_ok_password> (the default C<login_ok> hook),
919 C<gen_plain_login_form> and the default C<is_login> hook.
921 =item C<username_param_names>
923 Arrayref of name(s) of username form parameters.
925 The first entry is used by C<login_ok_password> (the default
926 C<login_ok> hook) to pass to the C<username_password_error> hook and
927 used as the username if all is well.
929 All the entries are used by C<gen_plain_login_fork> (the default
930 C<gen_login_form> hook for C<check_ok>) to generate form entry fields.
932 The default is C<['username']>.
934 =item C<logout_param_names>
936 Arrayref of name(s) of form parameters indicating that the request is
939 Used by the default C<is_logout> hook.
941 If you want users to be able to explicitly log out, you need to
942 provide a logout button, something like
943 C<< <input type="submit" name="caf_logout" ... >>
945 The default is C<['caf_logout']>
947 =item C<logged_param_names>
949 Arrayref of name(s) of form parameters indicating that user has just
950 logged out. (During the logout process, the actual logout action is a
951 POST request, whose response redirects to the "you have been logged
952 out" page; these form parameters are for this second page.)
954 Used by the default C<is_loggedout> hook.
956 The first entry is used by C<check_ok> to generate the redirection.
958 The default is C<['caf_loggedout']>
960 =item C<promise_check_mutate>
962 Boolean. If true, is a declaration by the application that it is
963 mutatin-aware. See L</MUTATING OPERATIONS AND EXTERNAL LINKS>.
967 =item C<encrypted_only>
969 Boolean. If true, CAF will insist that all transactions be done over
970 an encrypted http connection. It will redirect unencrypted requests
971 to the https instance of the applicattion, and will set the encrypted
972 only flag on its cookie.
976 =item C<< get_url($cgi,$authreq) >>
978 Hook which returns the URL of this web application. By default, we
979 call C<< $cgi->url() >> for each request, but you can fix this if you
982 =item C<< is_login,is_logout,is_loggedout($cgi,$authreq) >>
984 Hook which returns a boolean indicating whether the request was,
985 respectively: a login form submission (ie, username and password); a
986 logout request (submission resulting from the user pressing the
987 "logout" button); "logged out" page (redirection from the logout
990 The default is to check whether any of the corresponding request
991 parameters (C<< login_param_names >> etc.) was supplied, using the
996 =head2 SETTINGS (HOOKS) RELATED TO THE CGI REQUEST OBJECT
1000 =item C<< get_param($cgi,$authreq,$param) >>
1002 Returns the value of a single-valued form parameter.
1003 The default is to call C<< $cgi->param($param) >>.
1004 The semantics are the same as that of C<CGI::param>.
1006 =item C<< get_params($cgi,$authreq) >>
1008 Returns a hash of the parameters. The return value is a hashref whose
1009 keys are the parameter names and whose values are arrayrefs, one entry
1010 in the arrayref for each value.
1012 The default is to call C<< $cgi->Vars() >>, expect the
1013 results to look like those from C<CGI::Vars>, and massage them into
1014 the required form with split.
1016 =item C<< get_path_info($cgi,$authreq) >>
1018 Returns the PATH_INFO of the request. The default is to
1019 call C<< $cgi->path_info() >>.
1021 =item C<< get_cookie($cgi,$authreq) >>
1023 Returns the value of the CAF cookie sent with the request, or undef if
1024 none was supplied. The default is to call C<<
1025 $cgi->cookie($cookie_name) >> (where C<$cookie_name> is from the
1026 setting of the same name). The return value should be the scalar
1027 value of the cookie.
1029 =item C<< get_method($cgi,$authreq) >>
1031 Returns the HTTP method as a string. The default is to call
1032 C<< $cgi->request_method() >>.
1034 =item C<< is_https($cgi,$authreq) >>
1036 Returns a boolean indicating whether the request was over an encrypted
1037 channel. The default is C<< !!$cgi->https() >>. See C<encrypted_only>.
1041 =head2 SETTINGS RELATED TO HTML GENERATION
1043 These are only used if you call C<check_ok> (or other functions
1044 mentioned in this section).
1046 Settings whose names are of the form C<gen_...> are hooks which each
1047 return an array of strings, normally HTML strings, for use by
1048 C<check_ok> (or, in turn, other hooks, or your application). These
1049 are often documented simply by showing the output produced. In many
1050 cases parts of the output are in turn obtained from other hooks. In
1051 some cases the default implementations have been given names for
1052 convenient use by your application. They will be called in array
1055 We'll write C<gettext(something)> even though actually there is a hook
1056 to control the translation function used.
1060 =item C<handle_divert>($cgi,$authreq,$divert))
1062 C<check_ok> calls this hook before producing output of its own. If
1063 you want to handle some but not all diversions yourself, you may set
1064 this hook. The hook should either do nothing and return false, or
1065 return true if it has handled the request (or arrange for the request
1066 to be handled). If the hook returns true then C<check_ok> simply
1069 =item C<gen_login_form>($cgi,$authreq,$divert))
1071 Default: a table (used mostly for layout) containing input fields for
1072 a login form. Must be within a C<< <form> >> element, but doesn't
1073 generate it. Has text fields for every entry in
1074 C<username_param_names> (in each case associated with a description
1075 C<< gettext(ucfirst $parameter_name) >>, a password field (with
1076 description C<gettext("Password")>, and a login submit button (with
1077 description C<gettext("Login")>.
1079 Default is available as the module function C<gen_plain_login_form>.
1081 =item C<gen_login_link>($cgi,$authreq))
1085 <a href="http:...">gettext(Log in again to continue.)</a>
1087 Default is available as the module function C<gen_plain_login_link>.
1089 =item C<gen_postmainpage_form>($cgi,$authreq,$params))
1091 Default: form contents (but not the C<< <form> >> element):
1093 C<$params> (in the form returned by the C<get_params> hook) as hidden
1096 <input type="submit" ... value=getext('Continue')>
1098 Default is available as the module function C<gen_postmainpage_form>.
1100 =item C<gen_start_html>($cgi,$authreq,$title)
1102 Default: C<$cgi->start_html($title)>
1104 =item C<gen_end_html>($cgi,$authreq,$title)
1106 Default: C<$cgi->end_html($title)>
1108 =item C<gen_footer_html>($cgi,$authreq)>
1113 Powered by Free / Libre / Open Source Software
1114 according to the [gen_licence_link_html].
1115 [gen_source_link_html].
1118 Default is available as the module function C<gen_plain_footer_html>.
1120 =item C<gen_licence_link_html>($cgi,$authreq)>
1122 Default: uses C<url_with_query_params> to generate a URL for
1123 downloading the licence, and returns:
1124 <a href="...">GNU Affero GPL</a>
1126 Default is available as the module function C<gen_plain_licence_link_html>.
1128 =item C<gen_source_link_html>($cgi,$authreq)>
1130 Default: uses C<url_with_query_params> to generate a URL for
1131 downloading the source, and returns:
1132 <a href="...">Source available</a>
1134 Default is available as the module function C<gen_plain_source_link_html>.
1136 =item C<form_entry_size>
1138 Size of generated text entry fields. Default is 60.
1140 =item C<dummy_param_name_prefix>
1142 Some of CAF's HTML-generating functions need to invent form parameter
1143 names. They will all start with this string. Default: C<caf__>.
1147 =head2 SETTINGS FOR SOURCE CODE DOWNLOAD FACILITY
1151 =item C<srcdump_needlogin>
1153 Boolean: do users need to log in to be able to download the source
1154 code for the whole application ? Default: 0.
1156 =item C<srcdump_param_name>
1158 Form parameter name used to indicate that this is a source download
1159 request. If this parameter is supplied, C<check_ok> and
1160 C<check_divert> will arrange for the applicaton source code to be
1161 delivered as the response (in C<check_ok>'s case by doing it itself
1162 and in C<check_divert>'s case by asking your application to do so.
1164 Default is C<caf_srcdump>.
1166 =item C<srcdump_path>
1168 Path to the directory used for storing pre-prepared source downloads.
1169 Defaults to C<caf-srcdump>.
1171 If this is a relative path, it is in C<dir>.
1173 =item C<srcdump_dump($cgi,$authreq,$srcobj)>
1175 Dump the source code (C<$srcobj='source'> or licence data
1176 (C<$srcobj='licence'>). The default implementation checks that
1177 C<$srcobj> has reasonable syntax and uses the files C<$srcobj.data>
1178 and C<$srcobj.ctype> with the C<dump> hook.
1180 =item C<dump($cgi,$authreq,$contenttype,$datafilehandle)>
1182 Responds to the request by sending the contents of $datafilehandle
1183 (which should just have been opened) and specifying a content type of
1186 The default implmentation uses the C<print> hook, and also calls
1187 C<$cgi->header('-type' => $contenttype>, and is available as the
1188 module function C<dump_plain>.
1190 =item C<srcdump_prepare($cgi,$verifier)>
1192 Prepares the source code for download when requested. Invoked by
1193 C<new_verifier>, always, immediately before it returns the
1194 just-created verifier object.
1196 The default implementation is the module function
1197 C<srcdump_dirscan_prepare>, which prepares a manifest, licence file
1198 and source code tarball of tarballs, as follows:
1200 It processes each entry in the return value from C<srcdump_listitems>.
1201 These are the software's include directories and any other directories
1202 containing source code. It handles C<.> specially (see
1203 C<srcdump_filter_cwd>).
1205 For each entry it looks, relative to that, for the licence as a file
1206 with a name mentioned in C<srcdump_licence_files>. The first such
1207 file found is considered to be the licence. It then calls the hook
1208 C<srcdump_process_item> for the entry.
1210 The licence, a manifest file, and all the outputs generated by the
1211 calls to C<srcdump_process_item>, are tarred up and compressed as a
1212 single source tarball.
1214 It uses the directory named by C<srcdump_path> as its directory for
1215 working and output files. It uses the filename patterns
1216 C<generate.*>, C<licence.*>, C<s.[a-z][a-z][a-z].*>, C<manifest.*>,
1217 C<source.*> in that directory.
1219 =item C<srcdump_process_item>($cgi,$verifier,$dumpdir,$item,\&outfn,\$needlicence,\%dirsdone)>
1221 Processes a single include directory or software entry, so as to
1222 include the source code found there. Called only by the default
1223 implementation of C<srcdump_prepare>.
1225 C<$dumpdir> is the directory for working and output files. C<$item>
1226 is the real (no symlinks) absolute path to the item.
1228 C<\$needlicence> is a ref to a scalar: this scalar is undef if we have
1229 already found the licence file; otherwise it is the filename to which
1230 the licence should be copied. If the referent is undef on entry,
1231 C<srcdump_process_item> needs to see if it finds the licence; if it
1232 does it should copy it to the named file and then set the scalar to
1235 C<\%dirsdone> is a ref to the hash used by C<srcdump_prepare> to avoid
1236 including a single directory more than once. If
1237 C<srcdump_process_item> decides to process a directory other than
1238 C<$item> it should check this hash with the real absolute path of the
1239 other directoy as a key: if the hash entry is true, it has already
1240 been done and should be skipped; otherwise the hash entry should be set.
1242 C<\&outfn> is a coderef which C<srcdump_process_item> should call each
1243 time it wants to generate a file which should be included as part of
1244 the source code. It should be called using one of these patterns:
1245 $outfn->("message for manifest");
1246 $outfile = $outfn->("message for manifest", "extension");
1247 The former simply prints the message into the manifest in the form
1248 none: message for manifest
1249 The latter generates and returns a filename which should then
1250 be created and filled with some appropriate data. C<"extension">
1251 should be a string for the file extension, eg C<"txt">. The output
1252 can be written directly to the named file: there is no need to
1253 write to a temporary file and rename. C<$outfn> writes the filename
1254 and the message to the manifest, in the form
1255 filename leaf: message
1256 In neither case is the actual name of C<$dir> on the system
1257 disclosed per se although of course some of the contents of some of
1258 the files in the source code dump may mention it.
1260 The default implementation is the module function
1261 C<srcdump_process_item>.
1263 It skips directories for which C<srcdump_system_dir> returns true.
1265 It then searches the item and its parent
1266 directories for a vcs metadata directory (one of the names in
1267 C<srcdump_vcs_dirs>); if found, it calls the C<srcdump_byvcs> hook
1268 (after checking and updaeing C<%dirsdone>).
1269 Otherwise it calls the C<srcdump_novcs> hook.
1271 =item C<srcdump_novcs($cgi,$verifier,$dumpdir,$item,$outfn)>
1273 Called by the default implementation of C<srcdump_process_item>, with
1274 the same arguments, if it doesn't find vcs metadata.
1276 The default implementation is the module function C<srcdump_novcs>.
1278 If C<$item> is a directory, it uses C<srcdump_dir_cpio> to prepare a
1279 tarball of all the files under C<$item> which have the world read bit
1280 set. Directories are not included (and their permissions are
1281 disregarded). The contents of C<srcdump_excludes> are excluded.
1283 If it's a plain file it uses C<srcdump_file> to include the file.
1285 =item C<srcdump_byvcs($cgi,$verifier,$dumpdir,$item,$outfn,$vcs)>
1287 Called by the default implementation of C<srcdump_process_item>, with
1288 the same arguments, if it finds vcs metadata. The additional argument
1289 C<$vcs> is derived from the entry of C<srcump_vcs_dirs> which was
1290 used: it's the first sequence of word characters, lowercased.
1292 The default implementation is the module function C<srcdump_byvcs>.
1293 It simply calls C<srcdump_dir_cpio> with a script from the setting
1294 C<srcdump_vcsscript>.
1296 =item C<srcdump_vcs_dirs>
1298 Array ref of leaf names of vcs metadata directories. Used by the
1299 default implementation of C<srcdump_process_item>. The default value
1300 is C<['.git','.hg','.bzr','.svn']>.
1302 =item C<srcdump_vcs_script>
1304 Hash ref of scripts for generating vcs metadata. Used by the default
1305 implementation of C<srcdump_byvcs>. The keys are values of C<$vcs>
1306 (see C<srcdump_byvcs>); the values are scripts as for
1307 C<srcdump_dir_cpio>.
1309 The default has an entry only for C<git>:
1311 git ls-files -z --others --exclude-from=.gitignore
1314 =item C<srcdump_excludes>
1316 Array ref of exclude glob patterns, used by the default implementation
1317 of C<srcdump_novcs>. The default value is C<['*~','*.bak','*.tmp','#*#']>.
1319 Entries must not contain C<'> or C<\>.
1321 =item C<srcdump_listitems($cgi,$verifier)>
1323 Returns an array of directories which might contain source code of the
1324 web application and which should be therefore be considered for
1325 including in the source code delivery.
1327 Used by the default implementation of C<srcdump_prepare>.
1329 Entries must be directories, plain files, or nonexistent; they may
1330 also be symlinks which resolve to one of those.
1332 If C<.> is included it may be treated specially - see
1333 C<srcdump_filter_cwd>.
1335 The default implementation returns
1336 C<(@INC, $ENV{'SCRIPT_FILENAME'}, $0)>.
1338 =item C<srcdump_system_dir($cgi,$verifier,$dir)>
1340 Determines whether C<$dir> is a "system directory", in which any
1341 source code used by the application should nevertheless not be
1342 included in the source code dump.
1344 Used by the default implementation of C<srcdump_item>.
1346 The default implementation is as follows: Things in C</etc/> are
1347 system directories. Things in C</usr/> are too, unless they are in
1348 C</usr/local/> or C</usr/lib/cgi*>.
1350 =item C<srcdump_filter_cwd>
1352 Boolean which controls the handling of C<.> if it appears in the
1353 return value from C<srcdump_listitems>. Used only by the default
1354 implementation of C<srcdump_prepare>.
1356 If set to false, C<.> is treated normally and no special action is
1359 However often the current directory may be C</>, or a data directory,
1360 or some other directory containing data which is confidential, or
1361 should not be included in the public source code distribution for
1362 other reasons. And for historical reasons Perl has C<@INC> containing
1363 C<.> by default (which is arguably dangerous and wrong).
1365 So the default this setting is true, which has the following effects:
1367 C<.> is not searched for source code even if it appears in C<@INC>.
1368 C<.> is removed from C<@INC> and C<%INC> is checked to see if any
1369 modules appear to have already been loaded by virtue of C<.> appearing
1370 in C<@INC> and if they have it is treated as a fatal error.
1372 Only the literal string C<.> is affected. If the cwd is included by
1373 any other name it is not treated specially regardless of this setting.
1377 =head1 DATABASE TABLES
1379 In a simple application, you do not need to worry about this. But if
1380 your application runs on multiple frontend hosts with a shared
1381 database, you may need to create for yourself the tables and indices
1382 used by CGI::Auth::Flexible.
1384 By default, every time CAF starts up, it attempts to execute certain
1385 fixed database statements to create the tables and indices it needs.
1386 These are run with C<$dbh->{PrintError}> set to 0. The effect with
1387 sqlite (the default database) is that the tables and indices are
1388 created iff they do not already exist, and that no spurious errors are
1391 If you use a different database, or just prefer to do things
1392 differently, you can set up the tables yourself and/or disable or
1393 modify the default setup statements, via the C<db_setup_stmts>
1396 The tables needed are:
1399 xxx document _db_setup_do
1400 xxx make _db_setup_do explicitly overrideable
1403 xxx remaining settings
1405 username_password_error
1412 xxx document cookie usage
1413 xxx document construct_cookie fn
1415 xxx document @default_db_setup_statements
1417 xxx bugs wrong default random on Linux
1419 xxx bugs wrong default random on *BSD
1421 xxx bugs keys not shared should be in db
1423 xxx rename caf_assocsecret default cookie name
1425 xxx mention relationship between login_timeout and cookies