doc/plugin.txt

   1 A FEW NOTES ON THE PLUGIN ARCHITECTURE
   2 ======================================
   3
   4 The plugin architecture of SquirrelMail is designed to make it
   5 possible to add new features without having to patch SquirrelMail
   6 itself. At the moment the plugin part of SquirrelMail should be
   7 considered "alpha" or "beta" quality code.
   8
   9 Until the functionality and code is more stable, be prepared for
  10 plugins to suddenly stop working.
  11
  12 Functionality like password changing, displaying ads and calendars
  13 should be possible to add as plugins.
  14
  15
  16 The idea
  17 --------
  18
  19 The idea is to be able to run random code at given places in the
  20 SquirrelMail code. This random code should then be able to do whatever
  21 needed to enhance the functionality of SquirrelMail. The places where
  22 code can be executed are called "hooks".
  23
  24 There are some limitations in what these hooks can do. It is difficult
  25 to use them to change the layout and to change functionality that
  26 already is in SquirrelMail.
  27
  28 Some way for the plugins to interact with the help subsystem and
  29 translations will be provided.
  30
  31
  32 The implementation
  33 ------------------
  34
  35 In the main SquirrelMail files the file functions/plugin.php. In
  36 places where hooks are made available they are executed by calling the
  37 function do_hook("hookname").
  38
  39 The do_hook traverses the array $squirrelmail_plugin_hooks["hookname"]
  40 and executes all the functions that are named in that array.
  41
  42 A plugin must reside in a subdirectory in the plugins/ directory. The
  43 name of the subdirectory is considered the name of the plugin.
  44
  45 To start using a plugin, its name must be added to the $plugins array
  46 in config.php like this:
  47
  48   $plugins[0] = "plugin_name";
  49
  50 When a plugin is registered the file plugins/plugin_name/setup.php is
  51 included and the function squirrelmail_plugin_init_plugin_name is
  52 called with no parameters.
  53
  54
  55 Writing plugins
  56 ---------------
  57
  58 A plugin must consist of at least a file called setup.php. All other
  59 files the plugin consist of should also be in the plugin directory.
  60
  61 The function squirrelmail_plugin_init_plugin_name is called to
  62 initalize a plugin. This function could look something like this:
  63
  64 function squirrelmail_plugin_init_demo () {
  65   global $squirrelmail_plugin_hooks;
  66
  67   $squirrelmail_plugin_hooks["generic_header"]["demo"] = "plugin_demo_header";
  68   $squirrelmail_plugin_hooks["menuline"]["demo"] = "plugin_demo_menuline";
  69 }
  70
  71 Note that the SquirrelMail files assume that all other SquirrelMail
  72 files are available as ../directory/file. This means that if some file
  73 in the plugin directory is requested, it must do a chdir("..") before
  74 including any of the standard SquirrelMail files.
  75
  76
  77 Hook Data Passed
  78 ----------------
  79 Hooks, when executed, are called with one parameter, an array of data
  80 that is passed to the hook.  The first element in the array is the name
  81 of the hook that is being called.  Any other elements in the array are
  82 dependant on the type of hook that is being called.
  83
  84 Some of the information in the array may be changed.  By default, the
  85 plugins should never change data unless it is documented otherwise.
  86
  87
  88 List of hooks
  89 -------------
  90   generic_header                  functions/page_header.php
  91   menuline                        functions/page_header.php
  92   compose_button_row              src/compose.php
  93   compose_bottom                  src/compose.php
  94   compose_form                    src/compose.php
  95   compose_send                    src/compose.php
  96   left_main_before                src/left_main.php
  97   left_main_after                 src/left_main.php
  98   * options_save                  src/options.php  (see note on options)
  99   * options_link_and_description  src/options.php  (see note on options)
 100   * options_highlight_bottom      src/options_highlight.php
 101   * options_personal_bottom       src/options_personal.php
 102   * options_personal_inside       src/options_personal.php
 103   * options_personal_save         src/options_personal.php
 104   * options_display_bottom        src/options_display.php
 105   * options_display_inside        src/options_display.php
 106   * options_display_save          src/options_display.php
 107   * options_folders_bottom        src/options_folders.php
 108   * options_folders_inside        src/options_folders.php
 109   * options_folders_save          src/options_folders.php
 110   & options_identities_process    src/options_identities.php
 111   & options_identities_top        src/options_identities.php
 112   & options_identities_renumber   src/options_identities.php (multiple places)
 113   & options_identities_table      src/options_identities.php
 114   & options_identities_buttons    src/options_identities.php
 115   logout                          src/signout.php
 116   logout_above_text               src/signout.php
 117   login_before                    src/webmail.php
 118   login_verified                  src/webmail.php
 119   loading_prefs                   src/load_prefs.php
 120   mailbox_index_before            functions/mailbox_display.php
 121   mailbox_index_after             functions/mailbox_display.php
 122   mailbox_form_before             functions/mailbox_display.php
 123   subject_link                    functions/mailbox_display.php
 124   right_main_after_header         src/right_main.php
 125   right_main_bottom               src/right_main.php
 126   login_top                       src/login.php
 127   login_bottom                    src/login.php
 128   html_top                        src/read_body.php
 129   read_body_top                   src/read_body.php
 130   read_body_bottom                src/read_body.php
 131   html_bottom                     src/read_body.php
 132   read_body_header                src/read_body.php
 133   read_body_header_right          src/read_body.php
 134   search_before_form              src/search.php
 135   search_after_form               src/search.php
 136   search_bottom                   src/search.php
 137   help_top                        src/help.php
 138   help_bottom                     src/help.php
 139   help_chapter                    src/help.php
 140   addrbook_html_search_below      src/addrbook_search_html.php
 141   addressbook_bottom              src/addressbook.php
 142   ^ attachment $type0/$type1      functions/mime.php (see note on attachments)
 143
 144
 145 (*) Options
 146 -----------
 147 There are two ways to do options for your plugin.  First, you can incorporate it
 148 into an existing section of the preferences (Display, Personal, or Folders).
 149 The second way, you create your own section that they can choose from and it
 150 displays its own range of options.
 151
 152
 153 First:  Integrating into existing options
 154 -----------------------------------------
 155 There are two hooks you need to use for this one:
 156
 157 1.  options_YOUCHOOSE_inside
 158     This is the code that goes inside the table for the section you choose.  Since
 159     it is going inside an existing table, it must be in this form:
 160     ------cut here-------
 161       <tr>
 162          <td>
 163             OPTION_NAME
 164          </td>
 165          <td>
 166             OPTION_INPUT
 167          </td>
 168       </tr>
 169     ------cut here-------
 170
 171 2.  options_YOUCHOOSE_save
 172     This is the code that saves your preferences into the users' preference
 173     file.  For an example of how to do this, see src/options.php.
 174
 175
 176 Second:  Create your own section
 177 -------------------------------
 178 It is possible to create your own options sections with plugins.  There are
 179 three hooks you will need to use.
 180
 181 1.  options_link_and_description
 182     This creates the link and has a description that are shown on the options
 183     page.  This should output HTML that looks like this.  Make sure to read
 184     the section on outputting your own pages.
 185
 186     -----cut here-----
 187       function my_plugin_name_my_function() {
 188          global $color
 189          ?>
 190          <table width=50% cellpadding=3 cellspacing=0 border=0 align=center>
 191             <tr>
 192                <td bgcolor="<? echo $color[9] ?>">
 193                   <a href="../plugins/YOUR_PLUGIN/YOUR_OPTIONS.php">YOUR OPTIONS NAME</a>
 194                </td>
 195             </tr>
 196             <tr>
 197                <td bgcolor="<? echo $color[0] ?>">
 198                   YOUR DESCRIPTION
 199                </td>
 200             </tr>
 201          </table>
 202          <?php
 203       }
 204     -----cut here-----
 205
 206 2.  options_save
 207     Here is the code that you need to do to save your options in the
 208     preference files or manipulate whatever data you are trying to change
 209     through the options section.  You can look at options.php for details
 210     on how this is to be done.
 211
 212 3.  loading_prefs (optional)
 213     If you are wanting to save preferences to the preference files, then
 214     you need to do this step as well.  Otherwise if you are manipulating
 215     other data, ignore this step.
 216
 217     You should put the code in here that loads your preferences back
 218     into usable variables.  Examples of this can be found in the file
 219     src/load_prefs.php
 220
 221
 222 (&) Identity Hooks
 223 ------------------
 224 Some hooks are passed special information in the array of arguments.  See
 225 the SpamCop plugin for how to use them.
 226
 227 options_identities_process
 228    [0] = Hook's name
 229    [1] = Should I run the SaveUpdateFunction() (alterable)
 230
 231 options_identities_renumber
 232    [0] = Hook's name
 233    [1] = Renumber it from ('default' or 1 through # idents - 1)
 234    [2] = Renumber it to (same thing)
 235
 236 options_identities_table
 237    [0] = Hook's name
 238    [1] = Color of table (use it like   <tr<?PHP echo $Info[1]?>>   in your
 239          plugin)
 240    [2] = Is this an empty section?
 241    [3] = What is the 'post' value?
 242
 243 options_identities_buttons
 244    [0] = Hook's name
 245    [1] = Is this an empty section (the one at the end of the list)?
 246    [2] = What is the 'post' value?
 247
 248
 249 (^) Attachment Hooks
 250 --------------------
 251 When a message has attachments, this hook is called with the MIME types.  For
 252 instance, a .zip file hook is "attachment application/x-zip".  The hook should
 253 probably show a link to do a specific action, such as "Verify" or "View" for a
 254 .zip file.
 255
 256 This is a breakdown of the data passed in the array to the hook that is called:
 257
 258   [0] = Hook's name ('attachment text/plain')
 259   [1] = Array of links of actions (more below) (Alterable)
 260   [2] = Used for returning to mail message (startMessage)
 261   [3] = Used for finding message to display (id)
 262   [4] = Mailbox name, urlencode()'d (urlMailbox)
 263   [5] = Entity ID inside mail message (ent)
 264   [6] = Default URL to go to when filename is clicked on (Alterable)
 265   [7] = Filename that is displayed for the attachment
 266   [8] = Sent if message was found from a search (where)
 267   [9] = Sent if message was found from a search (what)
 268
 269 To set up links for actions, you assign them like this:
 270
 271   $Args[1]['your_plugin_name']['href'] = 'URL to link to';
 272   $Args[1]['your_plugin_name']['text'] = 'What to display';
 273
 274
 275 Outputting Your Own Pages
 276 -------------------------
 277
 278 Often, when you want to provide your own customized options screen or create
 279 another web page instead of just using standard hooks, you will be creating
 280 your own .php files.  An example of this is the attachment_common plugin's
 281 image.php file.
 282
 283 To make sure that security is maintained and standards are followed, the top
 284 of your PHP script should look very similar to this:
 285
 286   <?PHP
 287     /* This is my php file.
 288      * description goes here.
 289      */
 290
 291     chdir('..');
 292     include('../src/validate.php');
 293
 294 The validate.php script will include internationalization support,
 295 config.php variables, strings.php functions, and also authenticate that the
 296 user is truly logged in.  Validate.php also calls stripslashes() on incoming
 297 data (if gpc_magic_quotes() is on).  You should never need to worry about
 298 that stuff again.  As a warning, this has only really been ironed out in
 299 1.1.1.  If you create/modify a plugin to follow these rules, you must
 300 mention that it requires SquirrelMail 1.1.1 or later.
 301
 302 After that, if you need further functions, just use
 303
 304   include('../functions/filename.php');
 305
 306 in your script.  Since 1.0.5, it was no longer necessary (nor recommended)
 307 to use the "if (! isset($filename_php))" syntax.