main/framehook.c

   1 /*
   2  * Asterisk -- An open source telephony toolkit.
   3  *
   4  * Copyright (C) 2010, Digium, Inc.
   5  *
   6  * David Vossel <dvossel@digium.com>
   7  *
   8  * See http://www.asterisk.org for more information about
   9  * the Asterisk project. Please do not directly contact
  10  * any of the maintainers of this project for assistance;
  11  * the project provides a web site, mailing lists and IRC
  12  * channels for your use.
  13  *
  14  * This program is free software, distributed under the terms of
  15  * the GNU General Public License Version 2. See the LICENSE file
  16  * at the top of the source tree.
  17  */
  18
  19 /*! \file
  20  *
  21  * \brief FrameHooks Architecture
  22  *
  23  * \author David Vossel <dvossel@digium.com>
  24  */
  25
  26 /*** MODULEINFO
  27         <support_level>core</support_level>
  28  ***/
  29
  30 #include "asterisk.h"
  31
  32 #include "asterisk/channel.h"
  33 #include "asterisk/linkedlists.h"
  34 #include "asterisk/framehook.h"
  35 #include "asterisk/frame.h"
  36
  37 struct ast_framehook {
  38         struct ast_framehook_interface i;
  39         /*! This pointer to ast_channel the framehook is attached to. */
  40         struct ast_channel *chan;
  41         /*! the id representing this framehook on a channel */
  42         unsigned int id;
  43         /*! when set, this signals the read and write function to detach the hook */
  44         int detach_and_destroy_me;
  45         /*! list entry for ast_framehook_list object */
  46         AST_LIST_ENTRY(ast_framehook) list;
  47 };
  48
  49 struct ast_framehook_list {
  50         /*! the number of hooks currently present */
  51         unsigned int count;
  52         /*! id for next framehook added */
  53         unsigned int id_count;
  54         AST_LIST_HEAD_NOLOCK(, ast_framehook) list;
  55 };
  56
  57 enum framehook_detachment_mode
  58 {
  59         /*! Destroy the framehook outright. */
  60         FRAMEHOOK_DETACH_DESTROY = 0,
  61         /*! Remove the framehook from the channel, but don't destroy the data since
  62          *  it will be used by a replacement framehook on another channel. */
  63         FRAMEHOOK_DETACH_PRESERVE,
  64 };
  65
  66 static void framehook_detach(struct ast_framehook *framehook, enum framehook_detachment_mode mode)
  67 {
  68         struct ast_frame *frame;
  69         frame = framehook->i.event_cb(framehook->chan, NULL, AST_FRAMEHOOK_EVENT_DETACHED, framehook->i.data);
  70         /* never assume anything about this function. If you can return a frame during
  71          * the detached event, then assume someone will. */
  72         if (frame) {
  73                 ast_frfree(frame);
  74         }
  75         framehook->chan = NULL;
  76
  77         if (mode == FRAMEHOOK_DETACH_DESTROY && framehook->i.destroy_cb) {
  78                 framehook->i.destroy_cb(framehook->i.data);
  79         }
  80         ast_free(framehook);
  81 }
  82
  83 static struct ast_frame *framehook_list_push_event(struct ast_framehook_list *framehooks, struct ast_frame *frame, enum ast_framehook_event event)
  84 {
  85         struct ast_framehook *framehook;
  86         struct ast_frame *original_frame;
  87         int *skip;
  88         size_t skip_size;
  89
  90         if (!framehooks) {
  91                 return frame;
  92         }
  93
  94         skip_size = sizeof(int) * framehooks->count;
  95         skip = ast_alloca(skip_size);
  96         memset(skip, 0, skip_size);
  97
  98         do {
  99                 unsigned int num = 0;
 100                 original_frame = frame;
 101
 102                 AST_LIST_TRAVERSE_SAFE_BEGIN(&framehooks->list, framehook, list) {
 103                         if (framehook->detach_and_destroy_me) {
 104                                 /* this guy is signaled for destruction */
 105                                 AST_LIST_REMOVE_CURRENT(list);
 106                                 framehook_detach(framehook, FRAMEHOOK_DETACH_DESTROY);
 107                                 continue;
 108                         }
 109
 110                         /* If this framehook has been marked as needing to be skipped, do so */
 111                         if (skip[num]) {
 112                                 num++;
 113                                 continue;
 114                         }
 115
 116                         frame = framehook->i.event_cb(framehook->chan, frame, event, framehook->i.data);
 117
 118                         if (frame != original_frame) {
 119                                 /* To prevent looping we skip any framehooks that have already provided a modified frame */
 120                                 skip[num] = 1;
 121                                 break;
 122                         }
 123
 124                         num++;
 125                 }
 126                 AST_LIST_TRAVERSE_SAFE_END;
 127         } while (frame != original_frame);
 128
 129         return frame;
 130 }
 131
 132 int ast_framehook_attach(struct ast_channel *chan, struct ast_framehook_interface *i)
 133 {
 134         struct ast_framehook *framehook;
 135         struct ast_framehook_list *fh_list;
 136         struct ast_frame *frame;
 137         if (i->version != AST_FRAMEHOOK_INTERFACE_VERSION) {
 138                 ast_log(LOG_ERROR, "Version '%hu' of framehook interface not what we compiled against (%i)\n",
 139                         i->version, AST_FRAMEHOOK_INTERFACE_VERSION);
 140                 return -1;
 141         }
 142         if (!i->event_cb || !(framehook = ast_calloc(1, sizeof(*framehook)))) {
 143                 return -1;
 144         }
 145         framehook->i = *i;
 146         framehook->chan = chan;
 147
 148         /* create the framehook list if it didn't already exist */
 149         if (!ast_channel_framehooks(chan)) {
 150                 if (!(fh_list = ast_calloc(1, sizeof(*ast_channel_framehooks(chan))))) {
 151                         ast_free(framehook);
 152                         return -1;
 153                 }
 154                 ast_channel_framehooks_set(chan, fh_list);
 155         }
 156
 157         ast_channel_framehooks(chan)->count++;
 158         framehook->id = ++ast_channel_framehooks(chan)->id_count;
 159         AST_LIST_INSERT_TAIL(&ast_channel_framehooks(chan)->list, framehook, list);
 160
 161         /* Tell the event callback we're live and rocking */
 162         frame = framehook->i.event_cb(framehook->chan, NULL, AST_FRAMEHOOK_EVENT_ATTACHED, framehook->i.data);
 163
 164         /* Never assume anything about this function. If you can return a frame during
 165          * the attached event, then assume someone will. */
 166         if (frame) {
 167                 ast_frfree(frame);
 168         }
 169
 170         if (ast_channel_is_bridged(chan)) {
 171                 ast_channel_set_unbridged_nolock(chan, 1);
 172         }
 173
 174         return framehook->id;
 175 }
 176
 177 int ast_framehook_detach(struct ast_channel *chan, int id)
 178 {
 179         struct ast_framehook *framehook;
 180         int res = -1;
 181
 182         if (!ast_channel_framehooks(chan)) {
 183                 return res;
 184         }
 185
 186         AST_LIST_TRAVERSE_SAFE_BEGIN(&ast_channel_framehooks(chan)->list, framehook, list) {
 187                 if (framehook->id == id) {
 188                         /* we mark for detachment rather than doing explicitly here because
 189                          * it needs to be safe for this function to be called within the
 190                          * event callback.  If we allowed the hook to actually be destroyed
 191                          * immediately here, the event callback would crash on exit. */
 192                         framehook->detach_and_destroy_me = 1;
 193                         res = 0;
 194                         break;
 195                 }
 196         }
 197         AST_LIST_TRAVERSE_SAFE_END;
 198
 199         if (!res && ast_channel_is_bridged(chan)) {
 200                 ast_channel_set_unbridged_nolock(chan, 1);
 201         }
 202
 203         return res;
 204 }
 205
 206 int ast_framehook_list_destroy(struct ast_channel *chan)
 207 {
 208         struct ast_framehook *framehook;
 209
 210         if (!ast_channel_framehooks(chan)) {
 211                 return 0;
 212         }
 213         AST_LIST_TRAVERSE_SAFE_BEGIN(&ast_channel_framehooks(chan)->list, framehook, list) {
 214                 AST_LIST_REMOVE_CURRENT(list);
 215                 framehook_detach(framehook, FRAMEHOOK_DETACH_DESTROY);
 216         }
 217         AST_LIST_TRAVERSE_SAFE_END;
 218         ast_free(ast_channel_framehooks(chan));
 219         ast_channel_framehooks_set(chan, NULL);
 220         return 0;
 221 }
 222
 223 void ast_framehook_list_fixup(struct ast_channel *old_chan, struct ast_channel *new_chan)
 224 {
 225         struct ast_framehook *framehook;
 226         int moved_framehook_id;
 227
 228         if (ast_channel_framehooks(new_chan)) {
 229                 AST_LIST_TRAVERSE_SAFE_BEGIN(&ast_channel_framehooks(new_chan)->list, framehook, list) {
 230                         if (framehook->i.disable_inheritance) {
 231                                 ast_framehook_detach(new_chan, framehook->id);
 232                                 continue;
 233                         }
 234
 235                         if (framehook->i.chan_breakdown_cb) {
 236                                 framehook->i.chan_breakdown_cb(framehook->i.data, framehook->id,
 237                                         old_chan, new_chan);
 238                         }
 239                 }
 240                 AST_LIST_TRAVERSE_SAFE_END;
 241         }
 242
 243         if (!ast_channel_framehooks(old_chan)) {
 244                 return;
 245         }
 246
 247         if (!AST_LIST_EMPTY(&ast_channel_framehooks(old_chan)->list)
 248                 && ast_channel_is_bridged(old_chan)) {
 249                 ast_channel_set_unbridged_nolock(old_chan, 1);
 250         }
 251         while ((framehook = AST_LIST_REMOVE_HEAD(&ast_channel_framehooks(old_chan)->list, list))) {
 252                 /* If inheritance is not allowed for this framehook, just destroy it. */
 253                 if (framehook->i.disable_inheritance) {
 254                         framehook_detach(framehook, FRAMEHOOK_DETACH_DESTROY);
 255                         continue;
 256                 }
 257
 258                 /* Otherwise move it to the other channel and perform any fixups set by the framehook interface */
 259                 moved_framehook_id = ast_framehook_attach(new_chan, &framehook->i);
 260                 if (moved_framehook_id < 0) {
 261                         ast_log(LOG_WARNING, "Failed framehook copy during masquerade. Expect loss of features.\n");
 262                         framehook_detach(framehook, FRAMEHOOK_DETACH_DESTROY);
 263                 } else {
 264                         if (framehook->i.chan_fixup_cb) {
 265                                 framehook->i.chan_fixup_cb(framehook->i.data, moved_framehook_id,
 266                                         old_chan, new_chan);
 267                         }
 268
 269                         framehook_detach(framehook, FRAMEHOOK_DETACH_PRESERVE);
 270                 }
 271         }
 272 }
 273
 274 int ast_framehook_list_is_empty(struct ast_framehook_list *framehooks)
 275 {
 276         if (!framehooks) {
 277                 return 1;
 278         }
 279         return AST_LIST_EMPTY(&framehooks->list) ? 1 : 0;
 280 }
 281
 282 int ast_framehook_list_contains_no_active(struct ast_framehook_list *framehooks)
 283 {
 284         return ast_framehook_list_contains_no_active_of_type(framehooks, 0);
 285 }
 286
 287 int ast_framehook_list_contains_no_active_of_type(struct ast_framehook_list *framehooks,
 288         enum ast_frame_type type)
 289 {
 290         struct ast_framehook *cur;
 291
 292         if (!framehooks) {
 293                 return 1;
 294         }
 295
 296         if (AST_LIST_EMPTY(&framehooks->list)) {
 297                 return 1;
 298         }
 299
 300         AST_LIST_TRAVERSE(&framehooks->list, cur, list) {
 301                 if (cur->detach_and_destroy_me) {
 302                         continue;
 303                 }
 304                 if (type && cur->i.consume_cb && !cur->i.consume_cb(cur->i.data, type)) {
 305                         continue;
 306                 }
 307                 return 0;
 308         }
 309
 310         return 1;
 311 }
 312
 313 struct ast_frame *ast_framehook_list_write_event(struct ast_framehook_list *framehooks, struct ast_frame *frame)
 314 {
 315         return framehook_list_push_event(framehooks, frame, AST_FRAMEHOOK_EVENT_WRITE);
 316 }
 317
 318 struct ast_frame *ast_framehook_list_read_event(struct ast_framehook_list *framehooks, struct ast_frame *frame)
 319 {
 320         return framehook_list_push_event(framehooks, frame, AST_FRAMEHOOK_EVENT_READ);
 321 }