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1 | =head1 NAME |
2 | |
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3 | Catalyst::Manual::Tutorial::Authorization - Catalyst Tutorial - Part 6: Authorization |
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4 | |
5 | |
6 | =head1 OVERVIEW |
7 | |
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8 | This is B<Part 6 of 10> for the Catalyst tutorial. |
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9 | |
10 | L<Tutorial Overview|Catalyst::Manual::Tutorial> |
11 | |
12 | =over 4 |
13 | |
14 | =item 1 |
15 | |
16 | L<Introduction|Catalyst::Manual::Tutorial::Intro> |
17 | |
18 | =item 2 |
19 | |
20 | L<Catalyst Basics|Catalyst::Manual::Tutorial::CatalystBasics> |
21 | |
22 | =item 3 |
23 | |
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24 | L<More Catalyst Basics|Catalyst::Manual::Tutorial::MoreCatalystBasics> |
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25 | |
26 | =item 4 |
27 | |
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28 | L<Basic CRUD|Catalyst::Manual::Tutorial::BasicCRUD> |
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29 | |
30 | =item 5 |
31 | |
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32 | L<Authentication|Catalyst::Manual::Tutorial::Authentication> |
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33 | |
34 | =item 6 |
35 | |
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36 | B<Authorization> |
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37 | |
38 | =item 7 |
39 | |
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40 | L<Debugging|Catalyst::Manual::Tutorial::Debugging> |
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41 | |
42 | =item 8 |
43 | |
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44 | L<Testing|Catalyst::Manual::Tutorial::Testing> |
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45 | |
46 | =item 9 |
47 | |
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48 | L<Advanced CRUD|Catalyst::Manual::Tutorial::AdvancedCRUD> |
49 | |
50 | =item 10 |
51 | |
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52 | L<Appendices|Catalyst::Manual::Tutorial::Appendices> |
53 | |
54 | =back |
55 | |
56 | |
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57 | =head1 DESCRIPTION |
58 | |
59 | This part of the tutorial adds role-based authorization to the existing |
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60 | authentication implemented in Part 5. It provides simple examples of |
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61 | how to use roles in both TT templates and controller actions. The first |
62 | half looks at manually configured authorization. The second half looks |
63 | at how the ACL authorization plugin can simplify your code. |
64 | |
65 | You can checkout the source code for this example from the catalyst |
66 | subversion repository as per the instructions in |
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67 | L<Catalyst::Manual::Tutorial::Intro|Catalyst::Manual::Tutorial::Intro>. |
68 | |
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69 | |
70 | =head1 BASIC AUTHORIZATION |
71 | |
72 | In this section you learn how to manually configure authorization. |
73 | |
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74 | |
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75 | =head2 Update Plugins to Include Support for Authorization |
76 | |
77 | Edit C<lib/MyApp.pm> and add C<Authorization::Roles> to the list: |
78 | |
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79 | __PACKAGE__->setup(qw/ |
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80 | -Debug |
81 | ConfigLoader |
82 | Static::Simple |
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83 | |
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84 | StackTrace |
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85 | |
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86 | Authentication |
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87 | Authorization::Roles |
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88 | |
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89 | Session |
90 | Session::Store::FastMmap |
91 | Session::State::Cookie |
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92 | /; |
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93 | |
94 | |
95 | =head2 Add Config Information for Authorization |
96 | |
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97 | Edit C<myapp.conf> and update it to match the following (the |
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98 | C<role_relation> and C<role_field> definitions are new): |
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99 | |
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100 | # rename this file to MyApp.yml and put a : in front of "name" if |
101 | # you want to use yaml like in old versions of Catalyst |
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102 | name MyApp |
103 | <authentication> |
104 | default_realm dbic |
105 | <realms> |
106 | <dbic> |
107 | <credential> |
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108 | # Note this first definition would be the same as setting |
109 | # __PACKAGE__->config->{authentication}->{realms}->{dbic} |
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110 | # ->{credential} = 'Password' in lib/MyApp.pm |
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111 | # |
112 | # Specify that we are going to do password-based auth |
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113 | class Password |
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114 | # This is the name of the field in the users table with the |
115 | # password stored in it |
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116 | password_field password |
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117 | # Switch to more secure hashed passwords |
118 | password_type hashed |
119 | # Use the SHA-1 hashing algorithm |
120 | password_hash_type SHA-1 |
121 | </credential> |
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122 | <store> |
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123 | # Use DBIC to retrieve username, password & role information |
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124 | class DBIx::Class |
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125 | # This is the model object created by Catalyst::Model::DBIC |
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126 | # from your schema (you created 'MyApp::Schema::User' but as |
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127 | # the Catalyst startup debug messages show, it was loaded as |
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128 | # 'MyApp::Model::DB::Users'). |
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129 | # NOTE: Omit 'MyApp::Model' here just as you would when using |
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130 | # '$c->model("DB::Users)' |
131 | user_class DB::Users |
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132 | # This is the name of a many_to_many relation in the users |
133 | # object that points to the roles for that user |
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134 | role_relation roles |
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135 | # This is the name of field in the roles table that contains |
136 | # the role information |
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137 | role_field role |
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138 | </store> |
139 | </dbic> |
140 | </realms> |
141 | </authentication> |
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142 | |
143 | |
144 | =head2 Add Role-Specific Logic to the "Book List" Template |
145 | |
146 | Open C<root/src/books/list.tt2> in your editor and add the following |
147 | lines to the bottom of the file: |
148 | |
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149 | <p>Hello [% c.user.username %], you have the following roles:</p> |
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150 | |
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151 | <ul> |
152 | [% # Dump list of roles -%] |
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153 | [% FOR role = c.user.roles %]<li>[% role %]</li>[% END %] |
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154 | </ul> |
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155 | |
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156 | <p> |
157 | [% # Add some simple role-specific logic to template %] |
158 | [% # Use $c->check_user_roles() to check authz -%] |
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159 | [% IF c.check_user_roles('user') %] |
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160 | [% # Give normal users a link for 'logout' %] |
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161 | <a href="[% c.uri_for('/logout') %]">Logout</a> |
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162 | [% END %] |
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163 | |
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164 | [% # Can also use $c->user->check_roles() to check authz -%] |
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165 | [% IF c.check_user_roles('admin') %] |
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166 | [% # Give admin users a link for 'create' %] |
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167 | <a href="[% c.uri_for('form_create') %]">Create</a> |
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168 | [% END %] |
169 | </p> |
170 | |
171 | This code displays a different combination of links depending on the |
172 | roles assigned to the user. |
173 | |
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174 | |
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175 | =head2 Limit C<Books::add> to C<admin> Users |
176 | |
177 | C<IF> statements in TT templates simply control the output that is sent |
178 | to the user's browser; it provides no real enforcement (if users know or |
179 | guess the appropriate URLs, they are still perfectly free to hit any |
180 | action within your application). We need to enhance the controller |
181 | logic to wrap restricted actions with role-validation logic. |
182 | |
183 | For example, we might want to restrict the "formless create" action to |
184 | admin-level users by editing C<lib/MyApp/Controller/Books.pm> and |
185 | updating C<url_create> to match the following code: |
186 | |
187 | =head2 url_create |
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188 | |
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189 | Create a book with the supplied title and rating, |
190 | with manual authorization |
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191 | |
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192 | =cut |
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193 | |
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194 | sub url_create : Local { |
195 | # In addition to self & context, get the title, rating & author_id args |
196 | # from the URL. Note that Catalyst automatically puts extra information |
197 | # after the "/<controller_name>/<action_name/" into @_ |
198 | my ($self, $c, $title, $rating, $author_id) = @_; |
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199 | |
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200 | # Check the user's roles |
201 | if ($c->check_user_roles('admin')) { |
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202 | # Call create() on the book model object. Pass the table |
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203 | # columns/field values we want to set as hash values |
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204 | my $book = $c->model('DB::Books')->create({ |
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205 | title => $title, |
206 | rating => $rating |
207 | }); |
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208 | |
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209 | # Add a record to the join table for this book, mapping to |
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210 | # appropriate author |
211 | $book->add_to_book_authors({author_id => $author_id}); |
212 | # Note: Above is a shortcut for this: |
213 | # $book->create_related('book_authors', {author_id => $author_id}); |
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214 | |
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215 | # Assign the Book object to the stash for display in the view |
216 | $c->stash->{book} = $book; |
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217 | |
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218 | # This is a hack to disable XSUB processing in Data::Dumper |
219 | # (it's used in the view). This is a work-around for a bug in |
220 | # the interaction of some versions or Perl, Data::Dumper & DBIC. |
221 | # You won't need this if you aren't using Data::Dumper (or if |
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222 | # you are running DBIC 0.06001 or greater), but adding it doesn't |
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223 | # hurt anything either. |
224 | $Data::Dumper::Useperl = 1; |
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225 | |
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226 | # Set the TT template to use |
227 | $c->stash->{template} = 'books/create_done.tt2'; |
228 | } else { |
229 | # Provide very simple feedback to the user |
230 | $c->response->body('Unauthorized!'); |
231 | } |
232 | } |
233 | |
234 | |
235 | To add authorization, we simply wrap the main code of this method in an |
236 | C<if> statement that calls C<check_user_roles>. If the user does not |
237 | have the appropriate permissions, they receive an "Unauthorized!" |
238 | message. Note that we intentionally chose to display the message this |
239 | way to demonstrate that TT templates will not be used if the response |
240 | body has already been set. In reality you would probably want to use a |
241 | technique that maintains the visual continuity of your template layout |
242 | (for example, using the "status" or "error" message feature added in |
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243 | Part 3). |
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244 | |
245 | B<TIP>: If you want to keep your existing C<url_create> method, you can |
246 | create a new copy and comment out the original by making it look like a |
247 | Pod comment. For example, put something like C<=begin> before C<sub add |
248 | : Local {> and C<=end> after the closing C<}>. |
249 | |
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250 | |
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251 | =head2 Try Out Authentication And Authorization |
252 | |
253 | Press C<Ctrl-C> to kill the previous server instance (if it's still |
254 | running) and restart it: |
255 | |
256 | $ script/myapp_server.pl |
257 | |
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258 | Now trying going to L<http://localhost:3000/books/list> and you should |
259 | be taken to the login page (you might have to C<Shift+Reload> or |
260 | C<Ctrl+Reload> your browser and/or click the "Logout" link on the book |
261 | list page). Try logging in with both C<test01> and C<test02> (both |
262 | use a password of C<mypass>) and notice how the roles information |
263 | updates at the bottom of the "Book List" page. Also try the C<Logout> |
264 | link on the book list page. |
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265 | |
266 | Now the "url_create" URL will work if you are already logged in as user |
267 | C<test01>, but receive an authorization failure if you are logged in as |
268 | C<test02>. Try: |
269 | |
270 | http://localhost:3000/books/url_create/test/1/6 |
271 | |
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272 | while logged in as each user. Use one of the 'Logout' links (or go to |
273 | L<http://localhost:3000/logout> in your browser directly) when you are |
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274 | done. |
275 | |
276 | |
277 | =head1 ENABLE ACL-BASED AUTHORIZATION |
278 | |
279 | This section takes a brief look at how the |
280 | L<Catalyst::Plugin::Authorization::ACL|Catalyst::Plugin::Authorization::ACL> |
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281 | plugin can automate much of the work required to perform role-based |
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282 | authorization in a Catalyst application. |
283 | |
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284 | |
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285 | =head2 Add the C<Catalyst::Plugin::Authorization::ACL> Plugin |
286 | |
287 | Open C<lib/MyApp.pm> in your editor and add the following plugin to the |
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288 | C<__PACKAGE__-E<gt>setup> statement: |
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289 | |
290 | Authorization::ACL |
291 | |
292 | Note that the remaining C<use Catalyst> plugins from earlier sections |
293 | are not shown here, but they should still be included. |
294 | |
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295 | |
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296 | =head2 Add ACL Rules to the Application Class |
297 | |
298 | Open C<lib/MyApp.pm> in your editor and add the following B<BELOW> the |
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299 | C<__PACKAGE__-E<gt>setup> statement: |
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300 | |
301 | # Authorization::ACL Rules |
302 | __PACKAGE__->deny_access_unless( |
303 | "/books/form_create", |
304 | [qw/admin/], |
305 | ); |
306 | __PACKAGE__->deny_access_unless( |
307 | "/books/form_create_do", |
308 | [qw/admin/], |
309 | ); |
310 | __PACKAGE__->deny_access_unless( |
311 | "/books/delete", |
312 | [qw/user admin/], |
313 | ); |
314 | |
315 | Each of the three statements above comprises an ACL plugin "rule". The |
316 | first two rules only allow admin-level users to create new books using |
317 | the form (both the form itself and the data submission logic are |
318 | protected). The third statement allows both users and admins to delete |
319 | books. The C</books/url_create> action will continue to be protected by |
320 | the "manually configured" authorization created earlier in this part of |
321 | the tutorial. |
322 | |
323 | The ACL plugin permits you to apply allow/deny logic in a variety of |
324 | ways. The following provides a basic overview of the capabilities: |
325 | |
326 | =over 4 |
327 | |
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328 | =item * |
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329 | |
330 | The ACL plugin only operates on the Catalyst "private namespace". You |
331 | are using the private namespace when you use C<Local> actions. C<Path>, |
332 | C<Regex>, and C<Global> allow you to specify actions where the path and |
333 | the namespace differ -- the ACL plugin will not work in these cases. |
334 | |
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335 | =item * |
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336 | |
337 | Each rule is expressed in a separate |
338 | C<__PACKAGE__-E<gt>deny_access_unless()> or |
339 | C<__PACKAGE__-E<gt>allow_access_if()> line (there are several other |
340 | methods that can be used for more complex policies, see the C<METHODS> |
341 | portion of the |
342 | L<Catalyst::Plugin::Authorization::ACL|Catalyst::Plugin::Authorization::ACL> |
343 | documentation for more details). |
344 | |
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345 | =item * |
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346 | |
347 | Each rule can contain multiple roles but only a single path. |
348 | |
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349 | =item * |
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350 | |
351 | The rules are tried in order (with the "most specific" rules tested |
352 | first), and processing stops at the first "match" where an allow or deny |
353 | is specified. Rules "fall through" if there is not a "match" (where a |
354 | "match" means the user has the specified role). If a "match" is found, |
355 | then processing stops there and the appropriate allow/deny action is |
356 | taken. |
357 | |
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358 | =item * |
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359 | |
360 | If none of the rules match, then access is allowed. |
361 | |
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362 | =item * |
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363 | |
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364 | The rules currently need to be specified in the application class |
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365 | C<lib\MyApp.pm> B<after> the C<__PACKAGE__-E<gt>setup;> line. |
366 | |
367 | =back |
368 | |
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369 | |
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370 | =head2 Add a Method to Handle Access Violations |
371 | |
372 | By default, |
373 | L<Catalyst::Plugin::Authorization::ACL|Catalyst::Plugin::Authorization::ACL> |
374 | throws an exception when authorization fails. This will take the user |
375 | to the Catalyst debug screen, or a "Please come back later" message if |
376 | you are not using the C<-Debug> flag. This step uses the |
377 | C<access_denied> method in order to provide more appropriate feedback to |
378 | the user. |
379 | |
380 | Open C<lib/MyApp/Controller/Books.pm> in your editor and add the |
381 | following method: |
382 | |
383 | =head2 access_denied |
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384 | |
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385 | Handle Catalyst::Plugin::Authorization::ACL access denied exceptions |
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386 | |
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387 | =cut |
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388 | |
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389 | sub access_denied : Private { |
390 | my ($self, $c) = @_; |
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391 | |
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392 | # Set the error message |
393 | $c->stash->{error_msg} = 'Unauthorized!'; |
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394 | |
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395 | # Display the list |
396 | $c->forward('list'); |
397 | } |
398 | |
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399 | Then run the Catalyst development server script: |
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400 | |
401 | $ script/myapp_server.pl |
402 | |
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403 | Log in as C<test02>. Once at the book list, click the "Create" link |
404 | to try the C<form_create> action. You should receive a red |
405 | "Unauthorized!" error message at the top of the list. (Note that in |
406 | the example code the "Create" link code in C<root/src/books/list.tt2> |
407 | is inside an C<IF> statement that only displays the list to |
408 | admin-level users.) If you log in as C<test01> you should be able to |
409 | view the C<form_create> form and add a new book. |
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410 | |
411 | When you are done, use one of the 'Logout' links (or go to the |
412 | L<http://localhost:3000/logout> URL directly) when you are done. |
413 | |
414 | |
415 | =head1 AUTHOR |
416 | |
417 | Kennedy Clark, C<hkclark@gmail.com> |
418 | |
419 | Please report any errors, issues or suggestions to the author. The |
420 | most recent version of the Catalyst Tutorial can be found at |
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421 | L<http://dev.catalyst.perl.org/repos/Catalyst/trunk/Catalyst-Manual/lib/Catalyst/Manual/Tutorial/>. |
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422 | |
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423 | Copyright 2006-2008, Kennedy Clark, under Creative Commons License |
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424 | (L<http://creativecommons.org/licenses/by-sa/3.0/us/>). |
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425 | |