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 static void framehook_detach_and_destroy(struct ast_framehook *framehook)
  60 {
  61         struct ast_frame *frame;
  62         frame = framehook->i.event_cb(framehook->chan, NULL, AST_FRAMEHOOK_EVENT_DETACHED, framehook->i.data);
  63         /* never assume anything about this function. If you can return a frame during
  64          * the detached event, then assume someone will. */
  65         if (frame) {
  66                 ast_frfree(frame);
  67         }
  68         framehook->chan = NULL;
  69
  70         if (framehook->i.destroy_cb) {
  71                 framehook->i.destroy_cb(framehook->i.data);
  72         }
  73         ast_free(framehook);
  74 }
  75
  76 static struct ast_frame *framehook_list_push_event(struct ast_framehook_list *framehooks, struct ast_frame *frame, enum ast_framehook_event event)
  77 {
  78         struct ast_framehook *framehook;
  79         struct ast_frame *original_frame;
  80         int *skip;
  81         size_t skip_size;
  82
  83         if (!framehooks) {
  84                 return frame;
  85         }
  86
  87         skip_size = sizeof(int) * framehooks->count;
  88         skip = alloca(skip_size);
  89         memset(skip, 0, skip_size);
  90
  91         do {
  92                 unsigned int num = 0;
  93                 original_frame = frame;
  94
  95                 AST_LIST_TRAVERSE_SAFE_BEGIN(&framehooks->list, framehook, list) {
  96                         if (framehook->detach_and_destroy_me) {
  97                                 /* this guy is signaled for destruction */
  98                                 AST_LIST_REMOVE_CURRENT(list);
  99                                 framehook_detach_and_destroy(framehook);
 100                                 continue;
 101                         }
 102
 103                         /* If this framehook has been marked as needing to be skipped, do so */
 104                         if (skip[num]) {
 105                                 num++;
 106                                 continue;
 107                         }
 108
 109                         frame = framehook->i.event_cb(framehook->chan, frame, event, framehook->i.data);
 110
 111                         if (frame != original_frame) {
 112                                 /* To prevent looping we skip any framehooks that have already provided a modified frame */
 113                                 skip[num] = 1;
 114                                 break;
 115                         }
 116
 117                         num++;
 118                 }
 119                 AST_LIST_TRAVERSE_SAFE_END;
 120         } while (frame != original_frame);
 121
 122         return frame;
 123 }
 124
 125 int ast_framehook_attach(struct ast_channel *chan, struct ast_framehook_interface *i)
 126 {
 127         struct ast_framehook *framehook;
 128         struct ast_framehook_list *fh_list;
 129         struct ast_frame *frame;
 130         if (i->version != AST_FRAMEHOOK_INTERFACE_VERSION) {
 131                 ast_log(LOG_ERROR, "Version '%hu' of framehook interface not what we compiled against (%hu)\n",
 132                         i->version, AST_FRAMEHOOK_INTERFACE_VERSION);
 133                 return -1;
 134         }
 135         if (!i->event_cb || !(framehook = ast_calloc(1, sizeof(*framehook)))) {
 136                 return -1;
 137         }
 138         framehook->i = *i;
 139         framehook->chan = chan;
 140
 141         /* create the framehook list if it didn't already exist */
 142         if (!ast_channel_framehooks(chan)) {
 143                 if (!(fh_list = ast_calloc(1, sizeof(*ast_channel_framehooks(chan))))) {
 144                         ast_free(framehook);
 145                         return -1;
 146                 }
 147                 ast_channel_framehooks_set(chan, fh_list);
 148         }
 149
 150         ast_channel_framehooks(chan)->count++;
 151         framehook->id = ++ast_channel_framehooks(chan)->id_count;
 152         AST_LIST_INSERT_TAIL(&ast_channel_framehooks(chan)->list, framehook, list);
 153
 154         /* Tell the event callback we're live and rocking */
 155         frame = framehook->i.event_cb(framehook->chan, NULL, AST_FRAMEHOOK_EVENT_ATTACHED, framehook->i.data);
 156
 157         /* Never assume anything about this function. If you can return a frame during
 158          * the attached event, then assume someone will. */
 159         if (frame) {
 160                 ast_frfree(frame);
 161         }
 162
 163         if (ast_channel_is_bridged(chan)) {
 164                 ast_softhangup_nolock(chan, AST_SOFTHANGUP_UNBRIDGE);
 165         }
 166
 167         return framehook->id;
 168 }
 169
 170 int ast_framehook_detach(struct ast_channel *chan, int id)
 171 {
 172         struct ast_framehook *framehook;
 173         int res = -1;
 174
 175         if (!ast_channel_framehooks(chan)) {
 176                 return res;
 177         }
 178
 179         AST_LIST_TRAVERSE_SAFE_BEGIN(&ast_channel_framehooks(chan)->list, framehook, list) {
 180                 if (framehook->id == id) {
 181                         /* we mark for detachment rather than doing explicitly here because
 182                          * it needs to be safe for this function to be called within the
 183                          * event callback.  If we allowed the hook to actually be destroyed
 184                          * immediately here, the event callback would crash on exit. */
 185                         framehook->detach_and_destroy_me = 1;
 186                         res = 0;
 187                         break;
 188                 }
 189         }
 190         AST_LIST_TRAVERSE_SAFE_END;
 191
 192         return res;
 193 }
 194
 195 int ast_framehook_list_destroy(struct ast_channel *chan)
 196 {
 197         struct ast_framehook *framehook;
 198
 199         if (!ast_channel_framehooks(chan)) {
 200                 return 0;
 201         }
 202         AST_LIST_TRAVERSE_SAFE_BEGIN(&ast_channel_framehooks(chan)->list, framehook, list) {
 203                 AST_LIST_REMOVE_CURRENT(list);
 204                 framehook_detach_and_destroy(framehook);
 205         }
 206         AST_LIST_TRAVERSE_SAFE_END;
 207         ast_free(ast_channel_framehooks(chan));
 208         ast_channel_framehooks_set(chan, NULL);
 209         return 0;
 210 }
 211
 212 int ast_framehook_list_is_empty(struct ast_framehook_list *framehooks)
 213 {
 214         if (!framehooks) {
 215                 return 1;
 216         }
 217         return AST_LIST_EMPTY(&framehooks->list) ? 1 : 0;
 218 }
 219
 220 int ast_framehook_list_contains_no_active(struct ast_framehook_list *framehooks)
 221 {
 222         return ast_framehook_list_contains_no_active_of_type(framehooks, 0);
 223 }
 224
 225 int ast_framehook_list_contains_no_active_of_type(struct ast_framehook_list *framehooks,
 226         enum ast_frame_type type)
 227 {
 228         struct ast_framehook *cur;
 229
 230         if (!framehooks) {
 231                 return 1;
 232         }
 233
 234         if (AST_LIST_EMPTY(&framehooks->list)) {
 235                 return 1;
 236         }
 237
 238         AST_LIST_TRAVERSE(&framehooks->list, cur, list) {
 239                 if (cur->detach_and_destroy_me) {
 240                         continue;
 241                 }
 242                 if (type && cur->i.consume_cb && !cur->i.consume_cb(cur->i.data, type)) {
 243                         continue;
 244                 }
 245                 return 0;
 246         }
 247
 248         return 1;
 249 }
 250
 251 struct ast_frame *ast_framehook_list_write_event(struct ast_framehook_list *framehooks, struct ast_frame *frame)
 252 {
 253         return framehook_list_push_event(framehooks, frame, AST_FRAMEHOOK_EVENT_WRITE);
 254 }
 255
 256 struct ast_frame *ast_framehook_list_read_event(struct ast_framehook_list *framehooks, struct ast_frame *frame)
 257 {
 258         return framehook_list_push_event(framehooks, frame, AST_FRAMEHOOK_EVENT_READ);
 259 }