Wed Aug 7 17:15:53 2019

Asterisk developer's documentation


chan_bridge.c File Reference

Bridge Interaction Channel. More...

#include "asterisk.h"
#include <fcntl.h>
#include <sys/signal.h>
#include "asterisk/lock.h"
#include "asterisk/channel.h"
#include "asterisk/config.h"
#include "asterisk/module.h"
#include "asterisk/pbx.h"
#include "asterisk/sched.h"
#include "asterisk/io.h"
#include "asterisk/acl.h"
#include "asterisk/callerid.h"
#include "asterisk/file.h"
#include "asterisk/cli.h"
#include "asterisk/app.h"
#include "asterisk/bridging.h"

Go to the source code of this file.

Data Structures

struct  bridge_pvt

Functions

 AST_MODULE_INFO (ASTERISK_GPL_KEY, AST_MODFLAG_LOAD_ORDER,"Bridge Interaction Channel",.load=load_module,.unload=unload_module,.load_pri=AST_MODPRI_CHANNEL_DRIVER,)
static struct ast_channelbridge_bridgedchannel (struct ast_channel *chan, struct ast_channel *bridge)
 Called when the user of this channel wants to get the actual channel in the bridge.
static int bridge_call (struct ast_channel *ast, char *dest, int timeout)
 Called when the channel should actually be dialed.
static int bridge_hangup (struct ast_channel *ast)
 Called when a channel should be hung up.
static void bridge_queue_hangup (struct bridge_pvt *p, struct ast_channel *us)
 Helper function to not deadlock when queueing the hangup frame.
static struct ast_framebridge_read (struct ast_channel *ast)
 Called when a frame should be read from the channel.
static struct ast_channelbridge_request (const char *type, format_t format, const struct ast_channel *requestor, void *data, int *cause)
 Called when we want to place a call somewhere, but not actually call it... yet.
static int bridge_write (struct ast_channel *ast, struct ast_frame *f)
 Called when a frame should be written out to a channel.
static int load_module (void)
 Load module into PBX, register channel.
static int unload_module (void)
 Unload the bridge interaction channel from Asterisk.

Variables

static struct ast_channel_tech bridge_tech

Detailed Description

Bridge Interaction Channel.

Author:
Joshua Colp <jcolp@digium.com>

Definition in file chan_bridge.c.


Function Documentation

AST_MODULE_INFO ( ASTERISK_GPL_KEY  ,
AST_MODFLAG_LOAD_ORDER  ,
"Bridge Interaction Channel"  ,
load = load_module,
unload = unload_module,
load_pri = AST_MODPRI_CHANNEL_DRIVER 
)
static struct ast_channel * bridge_bridgedchannel ( struct ast_channel chan,
struct ast_channel bridge 
) [static, read]

Called when the user of this channel wants to get the actual channel in the bridge.

Definition at line 81 of file chan_bridge.c.

References bridge_pvt::input, bridge_pvt::output, and ast_channel::tech_pvt.

00082 {
00083    struct bridge_pvt *p = chan->tech_pvt;
00084    return (chan == p->input) ? p->output : bridge;
00085 }

static int bridge_call ( struct ast_channel ast,
char *  dest,
int  timeout 
) [static]

Called when the channel should actually be dialed.

Definition at line 123 of file chan_bridge.c.

References ast_bridge_impart(), ast_channel::bridge, bridge_pvt::input, bridge_pvt::output, and ast_channel::tech_pvt.

00124 {
00125    struct bridge_pvt *p = ast->tech_pvt;
00126 
00127    /* If no bridge has been provided on the input channel, bail out */
00128    if (!ast->bridge) {
00129       return -1;
00130    }
00131 
00132    /* Impart the output channel upon the given bridge of the input channel */
00133    ast_bridge_impart(p->input->bridge, p->output, NULL, NULL);
00134 
00135    return 0;
00136 }

static int bridge_hangup ( struct ast_channel ast  )  [static]

Called when a channel should be hung up.

Definition at line 161 of file chan_bridge.c.

References ast_free, ast_mutex_destroy, ast_mutex_lock, ast_mutex_unlock, bridge_queue_hangup(), bridge_pvt::input, bridge_pvt::lock, bridge_pvt::output, and ast_channel::tech_pvt.

00162 {
00163    struct bridge_pvt *p = ast->tech_pvt;
00164 
00165    ast_mutex_lock(&p->lock);
00166 
00167    /* Figure out which channel this is... and set it to NULL as it has gone, but also queue up a hangup frame. */
00168    if (p->input == ast) {
00169       if (p->output) {
00170          bridge_queue_hangup(p, ast);
00171       }
00172       p->input = NULL;
00173    } else if (p->output == ast) {
00174       if (p->input) {
00175          bridge_queue_hangup(p, ast);
00176       }
00177       p->output = NULL;
00178    }
00179 
00180    /* Deal with the Asterisk portion of it */
00181    ast->tech_pvt = NULL;
00182 
00183    /* If both sides have been terminated free the structure and be done with things */
00184    if (!p->input && !p->output) {
00185       ast_mutex_unlock(&p->lock);
00186       ast_mutex_destroy(&p->lock);
00187       ast_free(p);
00188    } else {
00189       ast_mutex_unlock(&p->lock);
00190    }
00191 
00192    return 0;
00193 }

static void bridge_queue_hangup ( struct bridge_pvt p,
struct ast_channel us 
) [static]

Helper function to not deadlock when queueing the hangup frame.

Definition at line 139 of file chan_bridge.c.

References ast_channel_trylock, ast_channel_unlock, ast_mutex_trylock, ast_mutex_unlock, ast_queue_hangup(), CHANNEL_DEADLOCK_AVOIDANCE, bridge_pvt::input, bridge_pvt::lock, and bridge_pvt::output.

Referenced by bridge_hangup().

00140 {
00141    struct ast_channel *other = (p->input == us ? p->output : p->input);
00142 
00143    while (other && ast_channel_trylock(other)) {
00144       ast_mutex_unlock(&p->lock);
00145       do {
00146          CHANNEL_DEADLOCK_AVOIDANCE(us);
00147       } while (ast_mutex_trylock(&p->lock));
00148       other = (p->input == us ? p->output : p->input);
00149    }
00150 
00151    /* We basically queue the frame up on the other channel if present */
00152    if (other) {
00153       ast_queue_hangup(other);
00154       ast_channel_unlock(other);
00155    }
00156 
00157    return;
00158 }

static struct ast_frame * bridge_read ( struct ast_channel ast  )  [static, read]

Called when a frame should be read from the channel.

Definition at line 88 of file chan_bridge.c.

References ast_null_frame.

00089 {
00090    return &ast_null_frame;
00091 }

static struct ast_channel * bridge_request ( const char *  type,
format_t  format,
const struct ast_channel requestor,
void *  data,
int *  cause 
) [static, read]

Called when we want to place a call somewhere, but not actually call it... yet.

Definition at line 196 of file chan_bridge.c.

References ast_calloc, ast_channel_alloc, ast_channel_release(), AST_FORMAT_SLINEAR, ast_free, ast_mutex_init, AST_STATE_UP, bridge_pvt::input, bridge_pvt::lock, ast_channel::nativeformats, bridge_pvt::output, ast_channel::rawreadformat, ast_channel::rawwriteformat, ast_channel::readformat, ast_channel::tech, ast_channel::tech_pvt, and ast_channel::writeformat.

00197 {
00198    struct bridge_pvt *p = NULL;
00199 
00200    /* Try to allocate memory for our very minimal pvt structure */
00201    if (!(p = ast_calloc(1, sizeof(*p)))) {
00202       return NULL;
00203    }
00204 
00205    /* Try to grab two Asterisk channels to use as input and output channels */
00206    if (!(p->input = ast_channel_alloc(1, AST_STATE_UP, 0, 0, "", "", "", requestor ? requestor->linkedid : NULL, 0, "Bridge/%p-input", p))) {
00207       ast_free(p);
00208       return NULL;
00209    }
00210    if (!(p->output = ast_channel_alloc(1, AST_STATE_UP, 0, 0, "", "", "", requestor ? requestor->linkedid : NULL, 0, "Bridge/%p-output", p))) {
00211       p->input = ast_channel_release(p->input);
00212       ast_free(p);
00213       return NULL;
00214    }
00215 
00216    /* Setup the lock on the pvt structure, we will need that */
00217    ast_mutex_init(&p->lock);
00218 
00219    /* Setup parameters on both new channels */
00220    p->input->tech = p->output->tech = &bridge_tech;
00221    p->input->tech_pvt = p->output->tech_pvt = p;
00222    p->input->nativeformats = p->output->nativeformats = AST_FORMAT_SLINEAR;
00223    p->input->readformat = p->output->readformat = AST_FORMAT_SLINEAR;
00224    p->input->rawreadformat = p->output->rawreadformat = AST_FORMAT_SLINEAR;
00225    p->input->writeformat = p->output->writeformat = AST_FORMAT_SLINEAR;
00226    p->input->rawwriteformat = p->output->rawwriteformat = AST_FORMAT_SLINEAR;
00227 
00228    return p->input;
00229 }

static int bridge_write ( struct ast_channel ast,
struct ast_frame f 
) [static]

Called when a frame should be written out to a channel.

Definition at line 94 of file chan_bridge.c.

References ast_channel_trylock, ast_channel_unlock, ast_mutex_lock, ast_mutex_trylock, ast_mutex_unlock, ast_queue_frame(), CHANNEL_DEADLOCK_AVOIDANCE, bridge_pvt::input, bridge_pvt::lock, bridge_pvt::output, and ast_channel::tech_pvt.

00095 {
00096    struct bridge_pvt *p = ast->tech_pvt;
00097    struct ast_channel *other;
00098 
00099    ast_mutex_lock(&p->lock);
00100 
00101    other = (p->input == ast ? p->output : p->input);
00102 
00103    while (other && ast_channel_trylock(other)) {
00104       ast_mutex_unlock(&p->lock);
00105       do {
00106          CHANNEL_DEADLOCK_AVOIDANCE(ast);
00107       } while (ast_mutex_trylock(&p->lock));
00108       other = (p->input == ast ? p->output : p->input);
00109    }
00110 
00111    /* We basically queue the frame up on the other channel if present */
00112    if (other) {
00113       ast_queue_frame(other, f);
00114       ast_channel_unlock(other);
00115    }
00116 
00117    ast_mutex_unlock(&p->lock);
00118 
00119    return 0;
00120 }

static int load_module ( void   )  [static]

Load module into PBX, register channel.

Definition at line 232 of file chan_bridge.c.

References ast_channel_register(), ast_log(), AST_MODULE_LOAD_FAILURE, AST_MODULE_LOAD_SUCCESS, and LOG_ERROR.

00233 {
00234    /* Make sure we can register our channel type */
00235    if (ast_channel_register(&bridge_tech)) {
00236       ast_log(LOG_ERROR, "Unable to register channel class 'Bridge'\n");
00237       return AST_MODULE_LOAD_FAILURE;
00238    }
00239    return AST_MODULE_LOAD_SUCCESS;
00240 }

static int unload_module ( void   )  [static]

Unload the bridge interaction channel from Asterisk.

Definition at line 243 of file chan_bridge.c.

References ast_channel_unregister().

00244 {
00245    ast_channel_unregister(&bridge_tech);
00246    return 0;
00247 }


Variable Documentation

struct ast_channel_tech bridge_tech [static]

Definition at line 60 of file chan_bridge.c.


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