Structure to describe a channel "technology", ie a channel driver See for examples: More...

#include <channel.h>

Collaboration diagram for ast_channel_tech:

Data Fields
int(*const	answer )(struct ast_channel *chan)
	Answer the channel.
enum ast_bridge_result(*const	bridge )(struct ast_channel c0, struct ast_channel c1, int flags, struct ast_frame fo, struct ast_channel rc, int timeoutms)
	Bridge two channels of the same type together.
struct ast_channel (const	bridged_channel )(struct ast_channel chan, struct ast_channel bridge)
	Find bridged channel.
int(*const	call )(struct ast_channel chan, const char addr, int timeout)
	Make a call.
struct ast_format_cap *	capabilities
int(*	cc_callback )(struct ast_channel inbound, const char dest, ast_cc_callback_fn callback)
	Call a function with cc parameters as a function parameter.
const char *const	description
int(*const	devicestate )(const char *device_number)
enum ast_bridge_result(*const	early_bridge )(struct ast_channel c0, struct ast_channel c1)
	Bridge two channels of the same type together (early)
struct ast_frame (const	exception )(struct ast_channel *chan)
	Handle an exception, reading a frame.
int(*const	fixup )(struct ast_channel oldchan, struct ast_channel newchan)
	Fix up a channel: If a channel is consumed, this is called. Basically update any ->owner links.
int(*	func_channel_read )(struct ast_channel chan, const char function, char data, char buf, size_t len)
	Provide additional read items for CHANNEL() dialplan function.
int(*	func_channel_write )(struct ast_channel chan, const char function, char data, const char value)
	Provide additional write items for CHANNEL() dialplan function.
struct ast_channel (	get_base_channel )(struct ast_channel *chan)
	Retrieve base channel (agent and local)
const char (	get_pvt_uniqueid )(struct ast_channel *chan)
	Get the unique identifier for the PVT, i.e. SIP call-ID for SIP.
int(*const	hangup )(struct ast_channel *chan)
	Hangup (and possibly destroy) the channel.
int(*const	indicate )(struct ast_channel c, int condition, const void data, size_t datalen)
	Indicate a particular condition (e.g. AST_CONTROL_BUSY or AST_CONTROL_RINGING or AST_CONTROL_CONGESTION.
int(*	pre_call )(struct ast_channel chan, const char sub_args)
	Execute a Gosub call on the channel in a technology specific way before a call is placed.
int	properties
int(*const	queryoption )(struct ast_channel chan, int option, void data, int *datalen)
	Query a given option. Called with chan locked.
struct ast_frame (const	read )(struct ast_channel *chan)
	Read a frame, in standard format (see frame.h)
struct ast_channel (const	requester )(const char type, struct ast_format_cap cap, const struct ast_channel requestor, const char addr, int *cause)
	Requester - to set up call data structures (pvt's)
int(*const	send_digit_begin )(struct ast_channel *chan, char digit)
	Start sending a literal DTMF digit.
int(*const	send_digit_end )(struct ast_channel *chan, char digit, unsigned int duration)
	Stop sending a literal DTMF digit.
int(*const	send_html )(struct ast_channel chan, int subclass, const char data, int len)
	Send HTML data.
int(*const	send_image )(struct ast_channel chan, struct ast_frame frame)
	Display or send an image.
int(*const	send_text )(struct ast_channel chan, const char text)
	Display or transmit text.
int(*	set_base_channel )(struct ast_channel chan, struct ast_channel base)
	Set base channel (agent and local)
int(*const	setoption )(struct ast_channel chan, int option, void data, int datalen)
	Set a given option. Called with chan locked.
int(*const	transfer )(struct ast_channel chan, const char newdest)
	Blind transfer other side (see app_transfer.c and ast_transfer()
const char *const	type
int(*const	write )(struct ast_channel chan, struct ast_frame frame)
	Write a frame, in standard format (see frame.h)
int(*const	write_text )(struct ast_channel chan, struct ast_frame frame)
	Write a text frame, in standard format.
int(*const	write_video )(struct ast_channel chan, struct ast_frame frame)
	Write a frame, in standard format.

Detailed Description

Structure to describe a channel "technology", ie a channel driver See for examples:

chan_iax2.c - The Inter-Asterisk exchange protocol
chan_sip.c - The SIP channel driver
chan_dahdi.c - PSTN connectivity (TDM, PRI, T1/E1, FXO, FXS)

If you develop your own channel driver, this is where you tell the PBX at registration of your driver what properties this driver supports and where different callbacks are implemented.

Definition at line 553 of file channel.h.

Field Documentation

int(* const answer)(struct ast_channel *chan)

Answer the channel.

Definition at line 610 of file channel.h.

Referenced by ast_raw_answer().

enum ast_bridge_result(* const bridge)(struct ast_channel *c0, struct ast_channel *c1, int flags, struct ast_frame **fo, struct ast_channel **rc, int timeoutms)

Bridge two channels of the same type together.

Definition at line 631 of file channel.h.

struct ast_channel*(* const bridged_channel)(struct ast_channel *chan, struct ast_channel *bridge) [read]

Find bridged channel.

Definition at line 659 of file channel.h.

Referenced by ast_bridged_channel(), destroy_conference_bridge(), and play_sound_helper().

int(* const call)(struct ast_channel *chan, const char *addr, int timeout)

Make a call.

Note:: The channel is locked when called.

Parameters:

chan	which channel to make the call on
addr	destination of the call
timeout	time to wait on for connect (Doesn't seem to be used.)

Return values:

0	on success
-1	on failure

Definition at line 604 of file channel.h.

Referenced by ast_call().

struct ast_format_cap* capabilities

format capabilities this channel can handle

Definition at line 557 of file channel.h.

Referenced by __unload_module(), console_request(), load_module(), phone_request(), and unload_module().

int(* cc_callback)(struct ast_channel *inbound, const char *dest, ast_cc_callback_fn callback)

Call a function with cc parameters as a function parameter.

This is a highly specialized callback that is not likely to be needed in many channel drivers. When dealing with a busy channel, for instance, most channel drivers will successfully return a channel to the requester. Once called, the channel can then queue a busy frame when it receives an appropriate message from the far end. In such a case, the channel driver has the opportunity to also queue a CC frame. The parameters for the CC channel can be retrieved from the channel structure.

For other channel drivers, notably those that deal with "dumb" phones, the channel driver will not return a channel when one is requested. In such a scenario, there is never an opportunity for the channel driver to queue a CC frame since the channel is never called. Furthermore, it is not possible to retrieve the CC configuration parameters for the desired channel because no channel is ever allocated or returned to the requester. In such a case, call completion may still be a viable option. What we do is pass the same string that the requester used originally to request the channel to the channel driver. The channel driver can then find any potential channels/devices that match the input and return call the designated callback with the device's call completion parameters as a parameter.

Definition at line 703 of file channel.h.

Referenced by ast_cc_callback().

const char* const description

Definition at line 555 of file channel.h.

Referenced by ast_var_channel_types_table().

int(* const devicestate)(const char *device_number)

Devicestate call back

Definition at line 579 of file channel.h.

Referenced by _ast_device_state(), and ast_var_channel_types_table().

enum ast_bridge_result(* const early_bridge)(struct ast_channel *c0, struct ast_channel *c1)

Bridge two channels of the same type together (early)

Definition at line 635 of file channel.h.

Referenced by ast_channel_early_bridge().

struct ast_frame*(* const exception)(struct ast_channel *chan) [read]

Handle an exception, reading a frame.

Definition at line 628 of file channel.h.

Referenced by __ast_read().

int(* const fixup)(struct ast_channel *oldchan, struct ast_channel *newchan)

Fix up a channel: If a channel is consumed, this is called. Basically update any ->owner links.

Definition at line 641 of file channel.h.

int(* func_channel_read)(struct ast_channel *chan, const char *function, char *data, char *buf, size_t len)

Provide additional read items for CHANNEL() dialplan function.

Note:: data should be treated as a const char *.

Definition at line 665 of file channel.h.

int(* func_channel_write)(struct ast_channel *chan, const char *function, char *data, const char *value)

Provide additional write items for CHANNEL() dialplan function.

Note:: data should be treated as a const char *.

Definition at line 671 of file channel.h.

struct ast_channel*(* get_base_channel)(struct ast_channel *chan) [read]

Retrieve base channel (agent and local)

Definition at line 674 of file channel.h.

const char*(* get_pvt_uniqueid)(struct ast_channel *chan)

Get the unique identifier for the PVT, i.e. SIP call-ID for SIP.

Definition at line 680 of file channel.h.

int(* const hangup)(struct ast_channel *chan)

Hangup (and possibly destroy) the channel.

Definition at line 607 of file channel.h.

Referenced by ast_hangup().

int(* const indicate)(struct ast_channel *c, int condition, const void *data, size_t datalen)

Indicate a particular condition (e.g. AST_CONTROL_BUSY or AST_CONTROL_RINGING or AST_CONTROL_CONGESTION.

Definition at line 638 of file channel.h.

Referenced by agent_indicate(), ast_indicate_data(), ast_var_channel_types_table(), and ast_write().

int(* pre_call)(struct ast_channel *chan, const char *sub_args)

Execute a Gosub call on the channel in a technology specific way before a call is placed.

Since:: 11.0

Parameters:

chan	Channel to execute Gosub in a tech specific way.
sub_args	Gosub application parameter string.

Note:: The chan is locked before calling.

Return values:

0	on success.
-1	on error.

Definition at line 717 of file channel.h.

Referenced by ast_pre_call().

int properties

Technology Properties

Definition at line 559 of file channel.h.

Referenced by ast_jb_do_usecheck().

int(* const queryoption)(struct ast_channel *chan, int option, void *data, int *datalen)

Query a given option. Called with chan locked.

Definition at line 647 of file channel.h.

Referenced by ast_channel_queryoption().

struct ast_frame*(* const read)(struct ast_channel *chan) [read]

Read a frame, in standard format (see frame.h)

Definition at line 613 of file channel.h.

Referenced by __ast_read().

struct ast_channel*(* const requester)(const char *type, struct ast_format_cap *cap, const struct ast_channel *requestor, const char *addr, int *cause) [read]

Requester - to set up call data structures (pvt's)

Parameters:

type	type of channel to request
cap	Format capabilities for requested channel
requestor	channel asking for data
addr	destination of the call
cause	Cause of failure