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 ASTERISK_FILE_VERSION(__FILE__, "$Revision$")
  33
  34 #include "asterisk/channel.h"
  35 #include "asterisk/linkedlists.h"
  36 #include "asterisk/framehook.h"
  37 #include "asterisk/frame.h"
  38
  39 struct ast_framehook {
  40         struct ast_framehook_interface i;
  41         /*! This pointer to ast_channel the framehook is attached to. */
  42         struct ast_channel *chan;
  43         /*! the id representing this framehook on a channel */
  44         unsigned int id;
  45         /*! when set, this signals the read and write function to detach the hook */
  46         int detach_and_destroy_me;
  47         /*! list entry for ast_framehook_list object */
  48         AST_LIST_ENTRY(ast_framehook) list;
  49 };
  50
  51 struct ast_framehook_list {
  52         /*! the number of hooks currently present */
  53         unsigned int count;
  54         /*! id for next framehook added */
  55         unsigned int id_count;
  56         AST_LIST_HEAD_NOLOCK(, ast_framehook) list;
  57 };
  58
  59 enum framehook_detachment_mode
  60 {
  61         /*! Destroy the framehook outright. */
  62         FRAMEHOOK_DETACH_DESTROY = 0,
  63         /*! Remove the framehook from the channel, but don't destroy the data since
  64          *  it will be used by a replacement framehook on another channel. */
  65         FRAMEHOOK_DETACH_PRESERVE,
  66 };
  67
  68 static void framehook_detach(struct ast_framehook *framehook, enum framehook_detachment_mode mode)
  69 {
  70         struct ast_frame *frame;
  71         frame = framehook->i.event_cb(framehook->chan, NULL, AST_FRAMEHOOK_EVENT_DETACHED, framehook->i.data);
  72         /* never assume anything about this function. If you can return a frame during
  73          * the detached event, then assume someone will. */
  74         if (frame) {
  75                 ast_frfree(frame);
  76         }
  77         framehook->chan = NULL;
  78
  79         if (mode == FRAMEHOOK_DETACH_DESTROY && framehook->i.destroy_cb) {
  80                 framehook->i.destroy_cb(framehook->i.data);
  81         }
  82         ast_free(framehook);
  83 }
  84
  85 static struct ast_frame *framehook_list_push_event(struct ast_framehook_list *framehooks, struct ast_frame *frame, enum ast_framehook_event event)
  86 {
  87         struct ast_framehook *framehook;
  88         struct ast_frame *original_frame;
  89         int *skip;
  90         size_t skip_size;
  91
  92         if (!framehooks) {
  93                 return frame;
  94         }
  95
  96         skip_size = sizeof(int) * framehooks->count;
  97         skip = ast_alloca(skip_size);
  98         memset(skip, 0, skip_size);
  99
 100         do {
 101                 unsigned int num = 0;
 102                 original_frame = frame;
 103
 104                 AST_LIST_TRAVERSE_SAFE_BEGIN(&framehooks->list, framehook, list) {
 105                         if (framehook->detach_and_destroy_me) {
 106                                 /* this guy is signaled for destruction */
 107                                 AST_LIST_REMOVE_CURRENT(list);
 108                                 framehook_detach(framehook, FRAMEHOOK_DETACH_DESTROY);
 109                                 continue;
 110                         }
 111
 112                         /* If this framehook has been marked as needing to be skipped, do so */
 113                         if (skip[num]) {
 114                                 num++;
 115                                 continue;
 116                         }
 117
 118                         frame = framehook->i.event_cb(framehook->chan, frame, event, framehook->i.data);
 119
 120                         if (frame != original_frame) {
 121                                 /* To prevent looping we skip any framehooks that have already provided a modified frame */
 122                                 skip[num] = 1;
 123                                 break;
 124                         }
 125
 126                         num++;
 127                 }
 128                 AST_LIST_TRAVERSE_SAFE_END;
 129         } while (frame != original_frame);
 130
 131         return frame;
 132 }
 133
 134 int ast_framehook_attach(struct ast_channel *chan, struct ast_framehook_interface *i)
 135 {
 136         struct ast_framehook *framehook;
 137         struct ast_framehook_list *fh_list;
 138         struct ast_frame *frame;
 139         if (i->version != AST_FRAMEHOOK_INTERFACE_VERSION) {
 140                 ast_log(LOG_ERROR, "Version '%hu' of framehook interface not what we compiled against (%hu)\n",
 141                         i->version, AST_FRAMEHOOK_INTERFACE_VERSION);
 142                 return -1;
 143         }
 144         if (!i->event_cb || !(framehook = ast_calloc(1, sizeof(*framehook)))) {
 145                 return -1;
 146         }
 147         framehook->i = *i;
 148         framehook->chan = chan;
 149
 150         /* create the framehook list if it didn't already exist */
 151         if (!ast_channel_framehooks(chan)) {
 152                 if (!(fh_list = ast_calloc(1, sizeof(*ast_channel_framehooks(chan))))) {
 153                         ast_free(framehook);
 154                         return -1;
 155                 }
 156                 ast_channel_framehooks_set(chan, fh_list);
 157         }
 158
 159         ast_channel_framehooks(chan)->count++;
 160         framehook->id = ++ast_channel_framehooks(chan)->id_count;
 161         AST_LIST_INSERT_TAIL(&ast_channel_framehooks(chan)->list, framehook, list);
 162
 163         /* Tell the event callback we're live and rocking */
 164         frame = framehook->i.event_cb(framehook->chan, NULL, AST_FRAMEHOOK_EVENT_ATTACHED, framehook->i.data);
 165
 166         /* Never assume anything about this function. If you can return a frame during
 167          * the attached event, then assume someone will. */
 168         if (frame) {
 169                 ast_frfree(frame);
 170         }
 171
 172         if (ast_channel_is_bridged(chan)) {
 173                 ast_channel_set_unbridged_nolock(chan, 1);
 174         }
 175
 176         return framehook->id;
 177 }
 178
 179 int ast_framehook_detach(struct ast_channel *chan, int id)
 180 {
 181         struct ast_framehook *framehook;
 182         int res = -1;
 183
 184         if (!ast_channel_framehooks(chan)) {
 185                 return res;
 186         }
 187
 188         AST_LIST_TRAVERSE_SAFE_BEGIN(&ast_channel_framehooks(chan)->list, framehook, list) {
 189                 if (framehook->id == id) {
 190                         /* we mark for detachment rather than doing explicitly here because
 191                          * it needs to be safe for this function to be called within the
 192                          * event callback.  If we allowed the hook to actually be destroyed
 193                          * immediately here, the event callback would crash on exit. */
 194                         framehook->detach_and_destroy_me = 1;
 195                         res = 0;
 196                         break;
 197                 }
 198         }
 199         AST_LIST_TRAVERSE_SAFE_END;
 200
 201         if (!res && ast_channel_is_bridged(chan)) {
 202                 ast_channel_set_unbridged_nolock(chan, 1);
 203         }
 204
 205         return res;
 206 }
 207
 208 int ast_framehook_list_destroy(struct ast_channel *chan)
 209 {
 210         struct ast_framehook *framehook;
 211
 212         if (!ast_channel_framehooks(chan)) {
 213                 return 0;
 214         }
 215         AST_LIST_TRAVERSE_SAFE_BEGIN(&ast_channel_framehooks(chan)->list, framehook, list) {
 216                 AST_LIST_REMOVE_CURRENT(list);
 217                 framehook_detach(framehook, FRAMEHOOK_DETACH_DESTROY);
 218         }
 219         AST_LIST_TRAVERSE_SAFE_END;
 220         ast_free(ast_channel_framehooks(chan));
 221         ast_channel_framehooks_set(chan, NULL);
 222         return 0;
 223 }
 224
 225 void ast_framehook_list_fixup(struct ast_channel *old_chan, struct ast_channel *new_chan)
 226 {
 227         struct ast_framehook *framehook;
 228         int moved_framehook_id;
 229
 230         if (ast_channel_framehooks(new_chan)) {
 231                 AST_LIST_TRAVERSE_SAFE_BEGIN(&ast_channel_framehooks(new_chan)->list, framehook, list) {
 232                         if (framehook->i.disable_inheritance) {
 233                                 ast_framehook_detach(new_chan, framehook->id);
 234                                 continue;
 235                         }
 236
 237                         if (framehook->i.chan_breakdown_cb) {
 238                                 framehook->i.chan_breakdown_cb(framehook->i.data, framehook->id,
 239                                         old_chan, new_chan);
 240                         }
 241                 }
 242                 AST_LIST_TRAVERSE_SAFE_END;
 243         }
 244
 245         if (!ast_channel_framehooks(old_chan)) {
 246                 return;
 247         }
 248
 249         if (!AST_LIST_EMPTY(&ast_channel_framehooks(old_chan)->list)
 250                 && ast_channel_is_bridged(old_chan)) {
 251                 ast_channel_set_unbridged_nolock(old_chan, 1);
 252         }
 253         while ((framehook = AST_LIST_REMOVE_HEAD(&ast_channel_framehooks(old_chan)->list, list))) {
 254                 /* If inheritance is not allowed for this framehook, just destroy it. */
 255                 if (framehook->i.disable_inheritance) {
 256                         framehook_detach(framehook, FRAMEHOOK_DETACH_DESTROY);
 257                         continue;
 258                 }
 259
 260                 /* Otherwise move it to the other channel and perform any fixups set by the framehook interface */
 261                 moved_framehook_id = ast_framehook_attach(new_chan, &framehook->i);
 262                 if (moved_framehook_id < 0) {
 263                         ast_log(LOG_WARNING, "Failed framehook copy during masquerade. Expect loss of features.\n");
 264                         framehook_detach(framehook, FRAMEHOOK_DETACH_DESTROY);
 265                 } else {
 266                         if (framehook->i.chan_fixup_cb) {
 267                                 framehook->i.chan_fixup_cb(framehook->i.data, moved_framehook_id,
 268                                         old_chan, new_chan);
 269                         }
 270
 271                         framehook_detach(framehook, FRAMEHOOK_DETACH_PRESERVE);
 272                 }
 273         }
 274 }
 275
 276 int ast_framehook_list_is_empty(struct ast_framehook_list *framehooks)
 277 {
 278         if (!framehooks) {
 279                 return 1;
 280         }
 281         return AST_LIST_EMPTY(&framehooks->list) ? 1 : 0;
 282 }
 283
 284 int ast_framehook_list_contains_no_active(struct ast_framehook_list *framehooks)
 285 {
 286         return ast_framehook_list_contains_no_active_of_type(framehooks, 0);
 287 }
 288
 289 int ast_framehook_list_contains_no_active_of_type(struct ast_framehook_list *framehooks,
 290         enum ast_frame_type type)
 291 {
 292         struct ast_framehook *cur;
 293
 294         if (!framehooks) {
 295                 return 1;
 296         }
 297
 298         if (AST_LIST_EMPTY(&framehooks->list)) {
 299                 return 1;
 300         }
 301
 302         AST_LIST_TRAVERSE(&framehooks->list, cur, list) {
 303                 if (cur->detach_and_destroy_me) {
 304                         continue;
 305                 }
 306                 if (type && cur->i.consume_cb && !cur->i.consume_cb(cur->i.data, type)) {
 307                         continue;
 308                 }
 309                 return 0;
 310         }
 311
 312         return 1;
 313 }
 314
 315 struct ast_frame *ast_framehook_list_write_event(struct ast_framehook_list *framehooks, struct ast_frame *frame)
 316 {
 317         return framehook_list_push_event(framehooks, frame, AST_FRAMEHOOK_EVENT_WRITE);
 318 }
 319
 320 struct ast_frame *ast_framehook_list_read_event(struct ast_framehook_list *framehooks, struct ast_frame *frame)
 321 {
 322         return framehook_list_push_event(framehooks, frame, AST_FRAMEHOOK_EVENT_READ);
 323 }