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Asterisk developer's documentation


channel.h

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00001 /*
00002  * Asterisk -- An open source telephony toolkit.
00003  *
00004  * Copyright (C) 1999 - 2006, Digium, Inc.
00005  *
00006  * Mark Spencer <markster@digium.com>
00007  *
00008  * See http://www.asterisk.org for more information about
00009  * the Asterisk project. Please do not directly contact
00010  * any of the maintainers of this project for assistance;
00011  * the project provides a web site, mailing lists and IRC
00012  * channels for your use.
00013  *
00014  * This program is free software, distributed under the terms of
00015  * the GNU General Public License Version 2. See the LICENSE file
00016  * at the top of the source tree.
00017  */
00018 
00019 /*! \file
00020  * \brief General Asterisk PBX channel definitions.
00021  * \par See also:
00022  *  \arg \ref Def_Channel
00023  *  \arg \ref channel_drivers
00024  */
00025 
00026 /*! \page Def_Channel Asterisk Channels
00027    \par What is a Channel?
00028    A phone call through Asterisk consists of an incoming
00029    connection and an outbound connection. Each call comes
00030    in through a channel driver that supports one technology,
00031    like SIP, DAHDI, IAX2 etc.
00032    \par
00033    Each channel driver, technology, has it's own private
00034    channel or dialog structure, that is technology-dependent.
00035    Each private structure is "owned" by a generic Asterisk
00036    channel structure, defined in channel.h and handled by
00037    channel.c .
00038    \par Call scenario
00039    This happens when an incoming call arrives to Asterisk
00040    -# Call arrives on a channel driver interface
00041    -# Channel driver creates a PBX channel and starts a
00042       pbx thread on the channel
00043    -# The dial plan is executed
00044    -# At this point at least two things can happen:
00045       -# The call is answered by Asterisk and
00046          Asterisk plays a media stream or reads media
00047       -# The dial plan forces Asterisk to create an outbound
00048          call somewhere with the dial (see \ref app_dial.c)
00049          application
00050    .
00051 
00052    \par Bridging channels
00053    If Asterisk dials out this happens:
00054    -# Dial creates an outbound PBX channel and asks one of the
00055       channel drivers to create a call
00056    -# When the call is answered, Asterisk bridges the media streams
00057       so the caller on the first channel can speak with the callee
00058       on the second, outbound channel
00059    -# In some cases where we have the same technology on both
00060       channels and compatible codecs, a native bridge is used.
00061       In a native bridge, the channel driver handles forwarding
00062       of incoming audio to the outbound stream internally, without
00063       sending audio frames through the PBX.
00064    -# In SIP, theres an "external native bridge" where Asterisk
00065       redirects the endpoint, so audio flows directly between the
00066       caller's phone and the callee's phone. Signalling stays in
00067       Asterisk in order to be able to provide a proper CDR record
00068       for the call.
00069 
00070 
00071    \par Masquerading channels
00072    In some cases, a channel can masquerade itself into another
00073    channel. This happens frequently in call transfers, where
00074    a new channel takes over a channel that is already involved
00075    in a call. The new channel sneaks in and takes over the bridge
00076    and the old channel, now a zombie, is hung up.
00077 
00078    \par Reference
00079    \arg channel.c - generic functions
00080    \arg channel.h - declarations of functions, flags and structures
00081    \arg translate.h - Transcoding support functions
00082    \arg \ref channel_drivers - Implemented channel drivers
00083    \arg \ref Def_Frame Asterisk Multimedia Frames
00084    \arg \ref Def_Bridge
00085 
00086 */
00087 /*! \page Def_Bridge Asterisk Channel Bridges
00088 
00089    In Asterisk, there's several media bridges.
00090 
00091    The Core bridge handles two channels (a "phone call") and bridge
00092    them together.
00093 
00094    The conference bridge (meetme) handles several channels simultaneously
00095    with the support of an external timer (DAHDI timer). This is used
00096    not only by the Conference application (meetme) but also by the
00097    page application and the SLA system introduced in 1.4.
00098    The conference bridge does not handle video.
00099 
00100    When two channels of the same type connect, the channel driver
00101    or the media subsystem used by the channel driver (i.e. RTP)
00102    can create a native bridge without sending media through the
00103    core.
00104 
00105    Native briding can be disabled by a number of reasons,
00106    like DTMF being needed by the core or codecs being incompatible
00107    so a transcoding module is needed.
00108 
00109 References:
00110    \li \see ast_channel_early_bridge()
00111    \li \see ast_channel_bridge()
00112    \li \see app_meetme.c
00113    \li \ref AstRTPbridge
00114    \li \see ast_rtp_bridge()
00115    \li \ref Def_Channel
00116 */
00117 
00118 /*! \page AstFileDesc File descriptors
00119    Asterisk File descriptors are connected to each channel (see \ref Def_Channel)
00120    in the \ref ast_channel structure.
00121 */
00122 
00123 #ifndef _ASTERISK_CHANNEL_H
00124 #define _ASTERISK_CHANNEL_H
00125 
00126 #include "asterisk/abstract_jb.h"
00127 
00128 #include "asterisk/poll-compat.h"
00129 
00130 #if defined(__cplusplus) || defined(c_plusplus)
00131 extern "C" {
00132 #endif
00133 
00134 #define AST_MAX_EXTENSION  80 /*!< Max length of an extension */
00135 #define AST_MAX_CONTEXT    80 /*!< Max length of a context */
00136 #define AST_CHANNEL_NAME   80 /*!< Max length of an ast_channel name */
00137 #define MAX_LANGUAGE    20 /*!< Max length of the language setting */
00138 #define MAX_MUSICCLASS     80 /*!< Max length of the music class setting */
00139 
00140 #include "asterisk/frame.h"
00141 #include "asterisk/sched.h"
00142 #include "asterisk/chanvars.h"
00143 #include "asterisk/config.h"
00144 #include "asterisk/lock.h"
00145 #include "asterisk/cdr.h"
00146 #include "asterisk/utils.h"
00147 #include "asterisk/linkedlists.h"
00148 #include "asterisk/stringfields.h"
00149 #include "asterisk/datastore.h"
00150 
00151 #define DATASTORE_INHERIT_FOREVER   INT_MAX
00152 
00153 #define AST_MAX_FDS     10
00154 /*
00155  * We have AST_MAX_FDS file descriptors in a channel.
00156  * Some of them have a fixed use:
00157  */
00158 #define AST_ALERT_FD (AST_MAX_FDS-1)      /*!< used for alertpipe */
00159 #define AST_TIMING_FD   (AST_MAX_FDS-2)      /*!< used for timingfd */
00160 #define AST_AGENT_FD (AST_MAX_FDS-3)      /*!< used by agents for pass through */
00161 #define AST_GENERATOR_FD   (AST_MAX_FDS-4)   /*!< used by generator */
00162 
00163 enum ast_bridge_result {
00164    AST_BRIDGE_COMPLETE = 0,
00165    AST_BRIDGE_FAILED = -1,
00166    AST_BRIDGE_FAILED_NOWARN = -2,
00167    AST_BRIDGE_RETRY = -3,
00168 };
00169 
00170 typedef unsigned long long ast_group_t;
00171 
00172 /*! \todo Add an explanation of an Asterisk generator
00173 */
00174 struct ast_generator {
00175    void *(*alloc)(struct ast_channel *chan, void *params);
00176    void (*release)(struct ast_channel *chan, void *data);
00177    /*! This function gets called with the channel unlocked, but is called in
00178     *  the context of the channel thread so we know the channel is not going
00179     *  to disappear.  This callback is responsible for locking the channel as
00180     *  necessary. */
00181    int (*generate)(struct ast_channel *chan, void *data, int len, int samples);
00182    /*! This gets called when DTMF_END frames are read from the channel */
00183    void (*digit)(struct ast_channel *chan, char digit);
00184 };
00185 
00186 /*! \brief Structure for all kinds of caller ID identifications.
00187  * \note All string fields here are malloc'ed, so they need to be
00188  * freed when the structure is deleted.
00189  * Also, NULL and "" must be considered equivalent.
00190  *
00191  * SIP and IAX2 has utf8 encoded Unicode caller ID names.
00192  * In some cases, we also have an alternative (RPID) E.164 number that can be used
00193  * as caller ID on numeric E.164 phone networks (DAHDI or SIP/IAX2 to pstn gateway).
00194  *
00195  * \todo Implement settings for transliteration between UTF8 caller ID names in
00196  *       to Ascii Caller ID's (DAHDI). Östen Åsklund might be transliterated into
00197  *  Osten Asklund or Oesten Aasklund depending upon language and person...
00198  *  We need automatic routines for incoming calls and static settings for
00199  *     our own accounts.
00200  */
00201 struct ast_callerid {
00202    char *cid_dnid;      /*!< Malloc'd Dialed Number Identifier */
00203    char *cid_num;    /*!< Malloc'd Caller Number */
00204    char *cid_name;      /*!< Malloc'd Caller Name (ASCII) */
00205    char *cid_ani;    /*!< Malloc'd ANI */
00206    char *cid_rdnis;  /*!< Malloc'd RDNIS */
00207    int cid_pres;     /*!< Callerid presentation/screening */
00208    int cid_ani2;     /*!< Callerid ANI 2 (Info digits) */
00209    int cid_ton;      /*!< Callerid Type of Number */
00210    int cid_tns;      /*!< Callerid Transit Network Select */
00211 };
00212 
00213 /*! \brief
00214    Structure to describe a channel "technology", ie a channel driver
00215    See for examples:
00216    \arg chan_iax2.c - The Inter-Asterisk exchange protocol
00217    \arg chan_sip.c - The SIP channel driver
00218    \arg chan_dahdi.c - PSTN connectivity (TDM, PRI, T1/E1, FXO, FXS)
00219 
00220    If you develop your own channel driver, this is where you
00221    tell the PBX at registration of your driver what properties
00222    this driver supports and where different callbacks are
00223    implemented.
00224 */
00225 struct ast_channel_tech {
00226    const char * const type;
00227    const char * const description;
00228 
00229    int capabilities;    /*!< Bitmap of formats this channel can handle */
00230 
00231    int properties;         /*!< Technology Properties */
00232 
00233    /*! \brief Requester - to set up call data structures (pvt's) */
00234    struct ast_channel *(* const requester)(const char *type, int format, void *data, int *cause);
00235 
00236    int (* const devicestate)(void *data); /*!< Devicestate call back */
00237 
00238    /*!
00239     * \brief Start sending a literal DTMF digit
00240     *
00241     * \note The channel is not locked when this function gets called.
00242     */
00243    int (* const send_digit_begin)(struct ast_channel *chan, char digit);
00244 
00245    /*!
00246     * \brief Stop sending a literal DTMF digit
00247     *
00248     * \note The channel is not locked when this function gets called.
00249     */
00250    int (* const send_digit_end)(struct ast_channel *chan, char digit, unsigned int duration);
00251 
00252    /*! \brief Call a given phone number (address, etc), but don't
00253       take longer than timeout seconds to do so.  */
00254    int (* const call)(struct ast_channel *chan, char *addr, int timeout);
00255 
00256    /*! \brief Hangup (and possibly destroy) the channel */
00257    int (* const hangup)(struct ast_channel *chan);
00258 
00259    /*! \brief Answer the channel */
00260    int (* const answer)(struct ast_channel *chan);
00261 
00262    /*! \brief Read a frame, in standard format (see frame.h) */
00263    struct ast_frame * (* const read)(struct ast_channel *chan);
00264 
00265    /*! \brief Write a frame, in standard format (see frame.h) */
00266    int (* const write)(struct ast_channel *chan, struct ast_frame *frame);
00267 
00268    /*! \brief Display or transmit text */
00269    int (* const send_text)(struct ast_channel *chan, const char *text);
00270 
00271    /*! \brief Display or send an image */
00272    int (* const send_image)(struct ast_channel *chan, struct ast_frame *frame);
00273 
00274    /*! \brief Send HTML data */
00275    int (* const send_html)(struct ast_channel *chan, int subclass, const char *data, int len);
00276 
00277    /*! \brief Handle an exception, reading a frame */
00278    struct ast_frame * (* const exception)(struct ast_channel *chan);
00279 
00280    /*! \brief Bridge two channels of the same type together */
00281    enum ast_bridge_result (* const bridge)(struct ast_channel *c0, struct ast_channel *c1, int flags,
00282                   struct ast_frame **fo, struct ast_channel **rc, int timeoutms);
00283 
00284    /*! \brief Bridge two channels of the same type together (early) */
00285    enum ast_bridge_result (* const early_bridge)(struct ast_channel *c0, struct ast_channel *c1);
00286 
00287    /*! \brief Indicate a particular condition (e.g. AST_CONTROL_BUSY or AST_CONTROL_RINGING or AST_CONTROL_CONGESTION */
00288    int (* const indicate)(struct ast_channel *c, int condition, const void *data, size_t datalen);
00289 
00290    /*! \brief Fix up a channel:  If a channel is consumed, this is called.  Basically update any ->owner links */
00291    int (* const fixup)(struct ast_channel *oldchan, struct ast_channel *newchan);
00292 
00293    /*! \brief Set a given option */
00294    int (* const setoption)(struct ast_channel *chan, int option, void *data, int datalen);
00295 
00296    /*! \brief Query a given option */
00297    int (* const queryoption)(struct ast_channel *chan, int option, void *data, int *datalen);
00298 
00299    /*! \brief Blind transfer other side (see app_transfer.c and ast_transfer() */
00300    int (* const transfer)(struct ast_channel *chan, const char *newdest);
00301 
00302    /*! \brief Write a frame, in standard format */
00303    int (* const write_video)(struct ast_channel *chan, struct ast_frame *frame);
00304 
00305    /*! \brief Write a text frame, in standard format */
00306    int (* const write_text)(struct ast_channel *chan, struct ast_frame *frame);
00307 
00308    /*! \brief Find bridged channel */
00309    struct ast_channel *(* const bridged_channel)(struct ast_channel *chan, struct ast_channel *bridge);
00310 
00311    /*! \brief Provide additional read items for CHANNEL() dialplan function */
00312    int (* func_channel_read)(struct ast_channel *chan, const char *function, char *data, char *buf, size_t len);
00313 
00314    /*! \brief Provide additional write items for CHANNEL() dialplan function */
00315    int (* func_channel_write)(struct ast_channel *chan, const char *function, char *data, const char *value);
00316 
00317    /*! \brief Retrieve base channel (agent and local) */
00318    struct ast_channel* (* get_base_channel)(struct ast_channel *chan);
00319 
00320    /*! \brief Set base channel (agent and local) */
00321    int (* set_base_channel)(struct ast_channel *chan, struct ast_channel *base);
00322 
00323    /*! \brief Get the unique identifier for the PVT, i.e. SIP call-ID for SIP */
00324    const char * (* get_pvt_uniqueid)(struct ast_channel *chan);
00325 };
00326 
00327 struct ast_epoll_data;
00328 
00329 /*!
00330  * The high bit of the frame count is used as a debug marker, so
00331  * increments of the counters must be done with care.
00332  * Please use c->fin = FRAMECOUNT_INC(c->fin) and the same for c->fout.
00333  */
00334 #define  DEBUGCHAN_FLAG  0x80000000
00335 
00336 /* XXX not ideal to evaluate x twice... */
00337 #define  FRAMECOUNT_INC(x) ( ((x) & DEBUGCHAN_FLAG) | (((x)+1) & ~DEBUGCHAN_FLAG) )
00338 
00339 /*!
00340  * The current value of the debug flags is stored in the two
00341  * variables global_fin and global_fout (declared in main/channel.c)
00342  */
00343 extern unsigned long global_fin, global_fout;
00344 
00345 enum ast_channel_adsicpe {
00346    AST_ADSI_UNKNOWN,
00347    AST_ADSI_AVAILABLE,
00348    AST_ADSI_UNAVAILABLE,
00349    AST_ADSI_OFFHOOKONLY,
00350 };
00351 
00352 /*!
00353  * \brief ast_channel states
00354  *
00355  * \note Bits 0-15 of state are reserved for the state (up/down) of the line
00356  *       Bits 16-32 of state are reserved for flags
00357  */
00358 enum ast_channel_state {
00359    AST_STATE_DOWN,         /*!< Channel is down and available */
00360    AST_STATE_RESERVED,     /*!< Channel is down, but reserved */
00361    AST_STATE_OFFHOOK,      /*!< Channel is off hook */
00362    AST_STATE_DIALING,      /*!< Digits (or equivalent) have been dialed */
00363    AST_STATE_RING,         /*!< Line is ringing */
00364    AST_STATE_RINGING,      /*!< Remote end is ringing */
00365    AST_STATE_UP,        /*!< Line is up */
00366    AST_STATE_BUSY,         /*!< Line is busy */
00367    AST_STATE_DIALING_OFFHOOK, /*!< Digits (or equivalent) have been dialed while offhook */
00368    AST_STATE_PRERING,      /*!< Channel has detected an incoming call and is waiting for ring */
00369 
00370    AST_STATE_MUTE = (1 << 16),   /*!< Do not transmit voice data */
00371 };
00372 
00373 /*!
00374  * \brief Possible T38 states on channels
00375  */
00376 enum ast_t38_state {
00377    T38_STATE_UNAVAILABLE,  /*!< T38 is unavailable on this channel or disabled by configuration */
00378    T38_STATE_UNKNOWN,   /*!< The channel supports T38 but the current status is unknown */
00379    T38_STATE_NEGOTIATING,  /*!< T38 is being negotiated */
00380    T38_STATE_REJECTED,  /*!< Remote side has rejected our offer */
00381    T38_STATE_NEGOTIATED,   /*!< T38 established */
00382 };
00383 
00384 /*! \brief Main Channel structure associated with a channel.
00385  * This is the side of it mostly used by the pbx and call management.
00386  *
00387  * \note XXX It is important to remember to increment .cleancount each time
00388  *       this structure is changed. XXX
00389  *
00390  * \note When adding fields to this structure, it is important to add the field
00391  *       'in position' with like-aligned fields, so as to keep the compiler from
00392  *       having to add padding to align fields. The structure's fields are sorted
00393  *       in this order: pointers, structures, long, int/enum, short, char. This
00394  *       is especially important on 64-bit architectures, where mixing 4-byte
00395  *       and 8-byte fields causes 4 bytes of padding to be added before many
00396  *       8-byte fields.
00397  */
00398 
00399 struct ast_channel {
00400    const struct ast_channel_tech *tech;      /*!< Technology (point to channel driver) */
00401    void *tech_pvt;               /*!< Private data used by the technology driver */
00402    void *music_state;            /*!< Music State*/
00403    void *generatordata;          /*!< Current generator data if there is any */
00404    struct ast_generator *generator;    /*!< Current active data generator */
00405    struct ast_channel *_bridge;        /*!< Who are we bridged to, if we're bridged.
00406                           Who is proxying for us, if we are proxied (i.e. chan_agent).
00407                           Do not access directly, use ast_bridged_channel(chan) */
00408    struct ast_channel *masq;        /*!< Channel that will masquerade as us */
00409    struct ast_channel *masqr;       /*!< Who we are masquerading as */
00410    const char *blockproc;           /*!< Procedure causing blocking */
00411    const char *appl;          /*!< Current application */
00412    const char *data;          /*!< Data passed to current application */
00413    struct sched_context *sched;        /*!< Schedule context */
00414    struct ast_filestream *stream;         /*!< Stream itself. */
00415    struct ast_filestream *vstream;        /*!< Video Stream itself. */
00416    int (*timingfunc)(const void *data);
00417    void *timingdata;
00418    struct ast_pbx *pbx;          /*!< PBX private structure for this channel */
00419    struct ast_trans_pvt *writetrans;      /*!< Write translation path */
00420    struct ast_trans_pvt *readtrans;    /*!< Read translation path */
00421    struct ast_audiohook_list *audiohooks;
00422    struct ast_cdr *cdr;          /*!< Call Detail Record */
00423    struct tone_zone *zone;       /*!< Tone zone as set in indications.conf or
00424                           in the CHANNEL dialplan function */
00425    struct ast_channel_monitor *monitor;      /*!< Channel monitoring */
00426 #ifdef HAVE_EPOLL
00427    struct ast_epoll_data *epfd_data[AST_MAX_FDS];
00428 #endif
00429 
00430    AST_DECLARE_STRING_FIELDS(
00431       AST_STRING_FIELD(name);       /*!< ASCII unique channel name */
00432       AST_STRING_FIELD(language);      /*!< Language requested for voice prompts */
00433       AST_STRING_FIELD(musicclass);    /*!< Default music class */
00434       AST_STRING_FIELD(accountcode);      /*!< Account code for billing */
00435       AST_STRING_FIELD(call_forward);     /*!< Where to forward to if asked to dial on this interface */
00436       AST_STRING_FIELD(uniqueid);      /*!< Unique Channel Identifier */
00437       AST_STRING_FIELD(parkinglot);    /*! Default parking lot, if empty, default parking lot  */
00438       AST_STRING_FIELD(dialcontext);      /*!< Dial: Extension context that we were called from */
00439    );
00440 
00441    struct timeval whentohangup;              /*!< Non-zero, set to actual time when channel is to be hung up */
00442    pthread_t blocker;            /*!< If anyone is blocking, this is them */
00443    ast_mutex_t lock_dont_use;       /*!< Lock a channel for some operations. See ast_channel_lock() */
00444    struct ast_callerid cid;         /*!< Caller ID, name, presentation etc */
00445    struct ast_frame dtmff;          /*!< DTMF frame */
00446    struct varshead varshead;        /*!< A linked list for channel variables. See \ref AstChanVar */
00447    ast_group_t callgroup;           /*!< Call group for call pickups */
00448    ast_group_t pickupgroup;         /*!< Pickup group - which calls groups can be picked up? */
00449    AST_LIST_HEAD_NOLOCK(, ast_frame) readq;
00450    AST_LIST_ENTRY(ast_channel) chan_list;    /*!< For easy linking */
00451    struct ast_jb jb;          /*!< The jitterbuffer state */
00452    struct timeval dtmf_tv;          /*!< The time that an in process digit began, or the last digit ended */
00453    AST_LIST_HEAD_NOLOCK(datastores, ast_datastore) datastores; /*!< Data stores on the channel */
00454 
00455    unsigned long insmpl;            /*!< Track the read/written samples for monitor use */
00456    unsigned long outsmpl;           /*!< Track the read/written samples for monitor use */
00457 
00458    int fds[AST_MAX_FDS];            /*!< File descriptors for channel -- Drivers will poll on
00459                           these file descriptors, so at least one must be non -1.
00460                           See \arg \ref AstFileDesc */
00461    int cdrflags;              /*!< Call Detail Record Flags */
00462    int _softhangup;           /*!< Whether or not we have been hung up...  Do not set this value
00463                           directly, use ast_softhangup() */
00464    int fdno;               /*!< Which fd had an event detected on */
00465    int streamid;              /*!< For streaming playback, the schedule ID */
00466    int vstreamid;             /*!< For streaming video playback, the schedule ID */
00467    int oldwriteformat;           /*!< Original writer format */
00468    int timingfd;              /*!< Timing fd */
00469    enum ast_channel_state _state;         /*!< State of line -- Don't write directly, use ast_setstate() */
00470    int rings;              /*!< Number of rings so far */
00471    int priority;              /*!< Dialplan: Current extension priority */
00472    int macropriority;            /*!< Macro: Current non-macro priority. See app_macro.c */
00473    int amaflags;              /*!< Set BEFORE PBX is started to determine AMA flags */
00474    enum ast_channel_adsicpe adsicpe;      /*!< Whether or not ADSI is detected on CPE */
00475    unsigned int fin;          /*!< Frames in counters. The high bit is a debug mask, so
00476                           the counter is only in the remaining bits */
00477    unsigned int fout;            /*!< Frames out counters. The high bit is a debug mask, so
00478                           the counter is only in the remaining bits */
00479    int hangupcause;           /*!< Why is the channel hanged up. See causes.h */
00480    unsigned int flags;           /*!< channel flags of AST_FLAG_ type */
00481    int alertpipe[2];
00482    int nativeformats;            /*!< Kinds of data this channel can natively handle */
00483    int readformat;               /*!< Requested read format */
00484    int writeformat;           /*!< Requested write format */
00485    int rawreadformat;            /*!< Raw read format */
00486    int rawwriteformat;           /*!< Raw write format */
00487    unsigned int emulate_dtmf_duration;    /*!< Number of ms left to emulate DTMF for */
00488 #ifdef HAVE_EPOLL
00489    int epfd;
00490 #endif
00491    int visible_indication;                         /*!< Indication currently playing on the channel */
00492 
00493    unsigned short transfercapability;     /*!< ISDN Transfer Capbility - AST_FLAG_DIGITAL is not enough */
00494 
00495    union {
00496       char unused_old_dtmfq[AST_MAX_EXTENSION];       /*!< (deprecated, use readq instead) Any/all queued DTMF characters */
00497       struct {
00498          struct ast_timer *timer;            /*!< timer object that provided timingfd */
00499       };
00500    };
00501 
00502    char context[AST_MAX_CONTEXT];         /*!< Dialplan: Current extension context */
00503    char exten[AST_MAX_EXTENSION];         /*!< Dialplan: Current extension number */
00504    char macrocontext[AST_MAX_CONTEXT];    /*!< Macro: Current non-macro context. See app_macro.c */
00505    char macroexten[AST_MAX_EXTENSION];    /*!< Macro: Current non-macro extension. See app_macro.c */
00506    char emulate_dtmf_digit;         /*!< Digit being emulated */
00507 };
00508 
00509 /*! \brief ast_channel_tech Properties */
00510 enum {
00511    /*! \brief Channels have this property if they can accept input with jitter;
00512     *         i.e. most VoIP channels */
00513    AST_CHAN_TP_WANTSJITTER = (1 << 0),
00514    /*! \brief Channels have this property if they can create jitter;
00515     *         i.e. most VoIP channels */
00516    AST_CHAN_TP_CREATESJITTER = (1 << 1),
00517 };
00518 
00519 /*! \brief ast_channel flags */
00520 enum {
00521    /*! Queue incoming dtmf, to be released when this flag is turned off */
00522    AST_FLAG_DEFER_DTMF =    (1 << 1),
00523    /*! write should be interrupt generator */
00524    AST_FLAG_WRITE_INT =     (1 << 2),
00525    /*! a thread is blocking on this channel */
00526    AST_FLAG_BLOCKING =      (1 << 3),
00527    /*! This is a zombie channel */
00528    AST_FLAG_ZOMBIE =        (1 << 4),
00529    /*! There is an exception pending */
00530    AST_FLAG_EXCEPTION =     (1 << 5),
00531    /*! Listening to moh XXX anthm promises me this will disappear XXX */
00532    AST_FLAG_MOH =           (1 << 6),
00533    /*! This channel is spying on another channel */
00534    AST_FLAG_SPYING =        (1 << 7),
00535    /*! This channel is in a native bridge */
00536    AST_FLAG_NBRIDGE =       (1 << 8),
00537    /*! the channel is in an auto-incrementing dialplan processor,
00538     *  so when ->priority is set, it will get incremented before
00539     *  finding the next priority to run */
00540    AST_FLAG_IN_AUTOLOOP =   (1 << 9),
00541    /*! This is an outgoing call */
00542    AST_FLAG_OUTGOING =      (1 << 10),
00543    /*! A DTMF_BEGIN frame has been read from this channel, but not yet an END */
00544    AST_FLAG_IN_DTMF =       (1 << 12),
00545    /*! A DTMF_END was received when not IN_DTMF, so the length of the digit is
00546     *  currently being emulated */
00547    AST_FLAG_EMULATE_DTMF =  (1 << 13),
00548    /*! This is set to tell the channel not to generate DTMF begin frames, and
00549     *  to instead only generate END frames. */
00550    AST_FLAG_END_DTMF_ONLY = (1 << 14),
00551    /*! Flag to show channels that this call is hangup due to the fact that the call
00552        was indeed anwered, but in another channel */
00553    AST_FLAG_ANSWERED_ELSEWHERE = (1 << 15),
00554    /*! This flag indicates that on a masquerade, an active stream should not
00555     *  be carried over */
00556    AST_FLAG_MASQ_NOSTREAM = (1 << 16),
00557    /*! This flag indicates that the hangup exten was run when the bridge terminated,
00558     *  a message aimed at preventing a subsequent hangup exten being run at the pbx_run
00559     *  level */
00560    AST_FLAG_BRIDGE_HANGUP_RUN = (1 << 17),
00561    /*! This flag indicates that the hangup exten should NOT be run when the
00562     *  bridge terminates, this will allow the hangup in the pbx loop to be run instead.
00563     *  */
00564    AST_FLAG_BRIDGE_HANGUP_DONT = (1 << 18),
00565    /*! This flag indicates whether the channel is in the channel list or not. */
00566    AST_FLAG_IN_CHANNEL_LIST = (1 << 19),
00567    /*! Disable certain workarounds.  This reintroduces certain bugs, but allows
00568     *  some non-traditional dialplans (like AGI) to continue to function.
00569     */
00570    AST_FLAG_DISABLE_WORKAROUNDS = (1 << 20),
00571 };
00572 
00573 /*! \brief ast_bridge_config flags */
00574 enum {
00575    AST_FEATURE_PLAY_WARNING = (1 << 0),
00576    AST_FEATURE_REDIRECT =     (1 << 1),
00577    AST_FEATURE_DISCONNECT =   (1 << 2),
00578    AST_FEATURE_ATXFER =       (1 << 3),
00579    AST_FEATURE_AUTOMON =      (1 << 4),
00580    AST_FEATURE_PARKCALL =     (1 << 5),
00581    AST_FEATURE_AUTOMIXMON =   (1 << 6),
00582    AST_FEATURE_NO_H_EXTEN =   (1 << 7),
00583    AST_FEATURE_WARNING_ACTIVE = (1 << 8),
00584 };
00585 
00586 /*! \brief bridge configuration */
00587 struct ast_bridge_config {
00588    struct ast_flags features_caller;
00589    struct ast_flags features_callee;
00590    struct timeval start_time;
00591    struct timeval nexteventts;
00592    struct timeval partialfeature_timer;
00593    long feature_timer;
00594    long timelimit;
00595    long play_warning;
00596    long warning_freq;
00597    const char *warning_sound;
00598    const char *end_sound;
00599    const char *start_sound;
00600    int firstpass;
00601    unsigned int flags;
00602    void (* end_bridge_callback)(void *);   /*!< A callback that is called after a bridge attempt */
00603    void *end_bridge_callback_data;         /*!< Data passed to the callback */
00604    /*! If the end_bridge_callback_data refers to a channel which no longer is going to
00605     * exist when the end_bridge_callback is called, then it needs to be fixed up properly
00606     */
00607    void (*end_bridge_callback_data_fixup)(struct ast_bridge_config *bconfig, struct ast_channel *originator, struct ast_channel *terminator);
00608 };
00609 
00610 struct chanmon;
00611 
00612 struct outgoing_helper {
00613    const char *context;
00614    const char *exten;
00615    int priority;
00616    const char *cid_num;
00617    const char *cid_name;
00618    const char *account;
00619    struct ast_variable *vars;
00620    struct ast_channel *parent_channel;
00621 };
00622 
00623 enum {
00624    AST_CDR_TRANSFER =   (1 << 0),
00625    AST_CDR_FORWARD =    (1 << 1),
00626    AST_CDR_CALLWAIT =   (1 << 2),
00627    AST_CDR_CONFERENCE = (1 << 3),
00628 };
00629 
00630 enum {
00631    /*! Soft hangup by device */
00632    AST_SOFTHANGUP_DEV =       (1 << 0),
00633    /*! Soft hangup for async goto */
00634    AST_SOFTHANGUP_ASYNCGOTO = (1 << 1),
00635    AST_SOFTHANGUP_SHUTDOWN =  (1 << 2),
00636    AST_SOFTHANGUP_TIMEOUT =   (1 << 3),
00637    AST_SOFTHANGUP_APPUNLOAD = (1 << 4),
00638    AST_SOFTHANGUP_EXPLICIT =  (1 << 5),
00639    AST_SOFTHANGUP_UNBRIDGE =  (1 << 6),
00640 };
00641 
00642 
00643 /*! \brief Channel reload reasons for manager events at load or reload of configuration */
00644 enum channelreloadreason {
00645    CHANNEL_MODULE_LOAD,
00646    CHANNEL_MODULE_RELOAD,
00647    CHANNEL_CLI_RELOAD,
00648    CHANNEL_MANAGER_RELOAD,
00649 };
00650 
00651 /*!
00652  * \note None of the datastore API calls lock the ast_channel they are using.
00653  *       So, the channel should be locked before calling the functions that
00654  *       take a channel argument.
00655  */
00656 
00657 /*!
00658  * \brief Create a channel data store object
00659  * \deprecated You should use the ast_datastore_alloc() generic function instead.
00660  * \version 1.6.1 deprecated
00661  */
00662 struct ast_datastore * attribute_malloc ast_channel_datastore_alloc(const struct ast_datastore_info *info, const char *uid)
00663    __attribute__((deprecated));
00664 
00665 /*!
00666  * \brief Free a channel data store object
00667  * \deprecated You should use the ast_datastore_free() generic function instead.
00668  * \version 1.6.1 deprecated
00669  */
00670 int ast_channel_datastore_free(struct ast_datastore *datastore)
00671    __attribute__((deprecated));
00672 
00673 /*! \brief Inherit datastores from a parent to a child. */
00674 int ast_channel_datastore_inherit(struct ast_channel *from, struct ast_channel *to);
00675 
00676 /*!
00677  * \brief Add a datastore to a channel
00678  *
00679  * \note The channel should be locked before calling this function.
00680  *
00681  * \retval 0 success
00682  * \retval non-zero failure
00683  */
00684 
00685 int ast_channel_datastore_add(struct ast_channel *chan, struct ast_datastore *datastore);
00686 
00687 /*!
00688  * \brief Remove a datastore from a channel
00689  *
00690  * \note The channel should be locked before calling this function.
00691  *
00692  * \retval 0 success
00693  * \retval non-zero failure
00694  */
00695 int ast_channel_datastore_remove(struct ast_channel *chan, struct ast_datastore *datastore);
00696 
00697 /*!
00698  * \brief Find a datastore on a channel
00699  *
00700  * \note The channel should be locked before calling this function.
00701  *
00702  * \note The datastore returned from this function must not be used if the
00703  *       reference to the channel is released.
00704  *
00705  * \retval pointer to the datastore if found
00706  * \retval NULL if not found
00707  */
00708 struct ast_datastore *ast_channel_datastore_find(struct ast_channel *chan, const struct ast_datastore_info *info, const char *uid);
00709 
00710 /*! \brief Change the state of a channel */
00711 int ast_setstate(struct ast_channel *chan, enum ast_channel_state);
00712 
00713 /*!
00714  * \brief Create a channel structure
00715  *
00716  * \retval NULL failure
00717  * \retval non-NULL successfully allocated channel
00718  *
00719  * \note By default, new channels are set to the "s" extension
00720  *       and "default" context.
00721  */
00722 struct ast_channel * attribute_malloc __attribute__((format(printf, 12, 13)))
00723    __ast_channel_alloc(int needqueue, int state, const char *cid_num,
00724              const char *cid_name, const char *acctcode,
00725              const char *exten, const char *context,
00726              const int amaflag, const char *file, int line,
00727              const char *function, const char *name_fmt, ...);
00728 
00729 #define ast_channel_alloc(needqueue, state, cid_num, cid_name, acctcode, exten, context, amaflag, ...) \
00730    __ast_channel_alloc(needqueue, state, cid_num, cid_name, acctcode, exten, context, amaflag, \
00731              __FILE__, __LINE__, __FUNCTION__, __VA_ARGS__)
00732 
00733 /*!
00734  * \brief Queue one or more frames to a channel's frame queue
00735  *
00736  * \param chan the channel to queue the frame(s) on
00737  * \param f the frame(s) to queue.  Note that the frame(s) will be duplicated
00738  *        by this function.  It is the responsibility of the caller to handle
00739  *        freeing the memory associated with the frame(s) being passed if
00740  *        necessary.
00741  *
00742  * \retval 0 success
00743  * \retval non-zero failure
00744  */
00745 int ast_queue_frame(struct ast_channel *chan, struct ast_frame *f);
00746 
00747 /*!
00748  * \brief Queue one or more frames to the head of a channel's frame queue
00749  *
00750  * \param chan the channel to queue the frame(s) on
00751  * \param f the frame(s) to queue.  Note that the frame(s) will be duplicated
00752  *        by this function.  It is the responsibility of the caller to handle
00753  *        freeing the memory associated with the frame(s) being passed if
00754  *        necessary.
00755  *
00756  * \retval 0 success
00757  * \retval non-zero failure
00758  */
00759 int ast_queue_frame_head(struct ast_channel *chan, struct ast_frame *f);
00760 
00761 /*!
00762  * \brief Queue a hangup frame
00763  *
00764  * \note The channel does not need to be locked before calling this function.
00765  */
00766 int ast_queue_hangup(struct ast_channel *chan);
00767 
00768 /*!
00769  * \brief Queue a hangup frame with hangupcause set
00770  *
00771  * \note The channel does not need to be locked before calling this function.
00772  * \param[in] chan channel to queue frame onto
00773  * \param[in] cause the hangup cause
00774  * \return 0 on success, -1 on error
00775  * \since 1.6.1
00776  */
00777 int ast_queue_hangup_with_cause(struct ast_channel *chan, int cause);
00778 
00779 /*!
00780  * \brief Queue a control frame with payload
00781  *
00782  * \param chan channel to queue frame onto
00783  * \param control type of control frame
00784  *
00785  * \note The channel does not need to be locked before calling this function.
00786  *
00787  * \retval zero on success
00788  * \retval non-zero on failure
00789  */
00790 int ast_queue_control(struct ast_channel *chan, enum ast_control_frame_type control);
00791 
00792 /*!
00793  * \brief Queue a control frame with payload
00794  *
00795  * \param chan channel to queue frame onto
00796  * \param control type of control frame
00797  * \param data pointer to payload data to be included in frame
00798  * \param datalen number of bytes of payload data
00799  *
00800  * \retval 0 success
00801  * \retval non-zero failure
00802  *
00803  * The supplied payload data is copied into the frame, so the caller's copy
00804  * is not modified nor freed, and the resulting frame will retain a copy of
00805  * the data even if the caller frees their local copy.
00806  *
00807  * \note This method should be treated as a 'network transport'; in other
00808  * words, your frames may be transferred across an IAX2 channel to another
00809  * system, which may be a different endianness than yours. Because of this,
00810  * you should ensure that either your frames will never be expected to work
00811  * across systems, or that you always put your payload data into 'network byte
00812  * order' before calling this function.
00813  *
00814  * \note The channel does not need to be locked before calling this function.
00815  */
00816 int ast_queue_control_data(struct ast_channel *chan, enum ast_control_frame_type control,
00817             const void *data, size_t datalen);
00818 
00819 /*!
00820  * \brief Change channel name
00821  *
00822  * \note The channel must be locked before calling this function.
00823  */
00824 void ast_change_name(struct ast_channel *chan, char *newname);
00825 
00826 /*! \brief Free a channel structure */
00827 void  ast_channel_free(struct ast_channel *);
00828 
00829 /*!
00830  * \brief Requests a channel
00831  *
00832  * \param type type of channel to request
00833  * \param format requested channel format (codec)
00834  * \param data data to pass to the channel requester
00835  * \param status status
00836  *
00837  * Request a channel of a given type, with data as optional information used
00838  * by the low level module
00839  *
00840  * \retval NULL failure
00841  * \retval non-NULL channel on success
00842  */
00843 struct ast_channel *ast_request(const char *type, int format, void *data, int *status);
00844 
00845 /*!
00846  * \brief Request a channel of a given type, with data as optional information used
00847  *        by the low level module and attempt to place a call on it
00848  *
00849  * \param type type of channel to request
00850  * \param format requested channel format
00851  * \param data data to pass to the channel requester
00852  * \param timeout maximum amount of time to wait for an answer
00853  * \param reason why unsuccessful (if unsuccessful)
00854  * \param cid_num Caller-ID Number
00855  * \param cid_name Caller-ID Name (ascii)
00856  *
00857  * \return Returns an ast_channel on success or no answer, NULL on failure.  Check the value of chan->_state
00858  * to know if the call was answered or not.
00859  */
00860 struct ast_channel *ast_request_and_dial(const char *type, int format, void *data,
00861    int timeout, int *reason, const char *cid_num, const char *cid_name);
00862 
00863 /*!
00864  * \brief Request a channel of a given type, with data as optional information used
00865  * by the low level module and attempt to place a call on it
00866  * \param type type of channel to request
00867  * \param format requested channel format
00868  * \param data data to pass to the channel requester
00869  * \param timeout maximum amount of time to wait for an answer
00870  * \param reason why unsuccessful (if unsuccessful)
00871  * \param cid_num Caller-ID Number
00872  * \param cid_name Caller-ID Name (ascii)
00873  * \param oh Outgoing helper
00874  * \return Returns an ast_channel on success or no answer, NULL on failure.  Check the value of chan->_state
00875  * to know if the call was answered or not.
00876  */
00877 struct ast_channel *__ast_request_and_dial(const char *type, int format, void *data,
00878    int timeout, int *reason, const char *cid_num, const char *cid_name, struct outgoing_helper *oh);
00879 /*!
00880 * \brief Forwards a call to a new channel specified by the original channel's call_forward str.  If possible, the new forwarded channel is created and returned while the original one is terminated.
00881 * \param caller in channel that requested orig
00882 * \param orig channel being replaced by the call forward channel
00883 * \param timeout maximum amount of time to wait for setup of new forward channel
00884 * \param format requested channel format
00885 * \param oh outgoing helper used with original channel
00886 * \param outstate reason why unsuccessful (if uncuccessful)
00887 * \return Returns the forwarded call's ast_channel on success or NULL on failure
00888 */
00889 struct ast_channel *ast_call_forward(struct ast_channel *caller, struct ast_channel *orig, int *timeout, int format, struct outgoing_helper *oh, int *outstate);
00890 
00891 /*!\brief Register a channel technology (a new channel driver)
00892  * Called by a channel module to register the kind of channels it supports.
00893  * \param tech Structure defining channel technology or "type"
00894  * \return Returns 0 on success, -1 on failure.
00895  */
00896 int ast_channel_register(const struct ast_channel_tech *tech);
00897 
00898 /*! \brief Unregister a channel technology
00899  * \param tech Structure defining channel technology or "type" that was previously registered
00900  * \return No return value.
00901  */
00902 void ast_channel_unregister(const struct ast_channel_tech *tech);
00903 
00904 /*! \brief Get a channel technology structure by name
00905  * \param name name of technology to find
00906  * \return a pointer to the structure, or NULL if no matching technology found
00907  */
00908 const struct ast_channel_tech *ast_get_channel_tech(const char *name);
00909 
00910 #ifdef CHANNEL_TRACE
00911 /*! \brief Update the context backtrace if tracing is enabled
00912  * \return Returns 0 on success, -1 on failure
00913  */
00914 int ast_channel_trace_update(struct ast_channel *chan);
00915 
00916 /*! \brief Enable context tracing in the channel
00917  * \return Returns 0 on success, -1 on failure
00918  */
00919 int ast_channel_trace_enable(struct ast_channel *chan);
00920 
00921 /*! \brief Disable context tracing in the channel.
00922  * \note Does not remove current trace entries
00923  * \return Returns 0 on success, -1 on failure
00924  */
00925 int ast_channel_trace_disable(struct ast_channel *chan);
00926 
00927 /*! \brief Whether or not context tracing is enabled
00928  * \return Returns -1 when the trace is enabled. 0 if not.
00929  */
00930 int ast_channel_trace_is_enabled(struct ast_channel *chan);
00931 
00932 /*! \brief Put the channel backtrace in a string
00933  * \return Returns the amount of lines in the backtrace. -1 on error.
00934  */
00935 int ast_channel_trace_serialize(struct ast_channel *chan, struct ast_str **out);
00936 #endif
00937 
00938 /*! \brief Hang up a channel
00939  * \note This function performs a hard hangup on a channel.  Unlike the soft-hangup, this function
00940  * performs all stream stopping, etc, on the channel that needs to end.
00941  * chan is no longer valid after this call.
00942  * \param chan channel to hang up
00943  * \return Returns 0 on success, -1 on failure.
00944  */
00945 int ast_hangup(struct ast_channel *chan);
00946 
00947 /*!
00948  * \brief Softly hangup up a channel
00949  *
00950  * \param chan channel to be soft-hung-up
00951  * \param reason an AST_SOFTHANGUP_* reason code
00952  *
00953  * Call the protocol layer, but don't destroy the channel structure
00954  * (use this if you are trying to
00955  * safely hangup a channel managed by another thread.
00956  *
00957  * \note The channel passed to this function does not need to be locked.
00958  *
00959  * \return Returns 0 regardless
00960  */
00961 int ast_softhangup(struct ast_channel *chan, int reason);
00962 
00963 /*! \brief Softly hangup up a channel (no channel lock)
00964  * \param chan channel to be soft-hung-up
00965  * \param reason an AST_SOFTHANGUP_* reason code
00966  */
00967 int ast_softhangup_nolock(struct ast_channel *chan, int reason);
00968 
00969 /*! \brief Check to see if a channel is needing hang up
00970  * \param chan channel on which to check for hang up
00971  * This function determines if the channel is being requested to be hung up.
00972  * \return Returns 0 if not, or 1 if hang up is requested (including time-out).
00973  */
00974 int ast_check_hangup(struct ast_channel *chan);
00975 
00976 /*!
00977  * \brief Compare a offset with the settings of when to hang a channel up
00978  * \param chan channel on which to check for hang up
00979  * \param offset offset in seconds from current time
00980  * \return 1, 0, or -1
00981  * This function compares a offset from current time with the absolute time
00982  * out on a channel (when to hang up). If the absolute time out on a channel
00983  * is earlier than current time plus the offset, it returns 1, if the two
00984  * time values are equal, it return 0, otherwise, it return -1.
00985  * \sa ast_channel_cmpwhentohangup_tv()
00986  * \version 1.6.1 deprecated function (only had seconds precision)
00987  */
00988 int ast_channel_cmpwhentohangup(struct ast_channel *chan, time_t offset) __attribute__((deprecated));
00989 
00990 /*!
00991  * \brief Compare a offset with the settings of when to hang a channel up
00992  * \param chan channel on which to check for hangup
00993  * \param offset offset in seconds and microseconds from current time
00994  * \return 1, 0, or -1
00995  * This function compares a offset from current time with the absolute time
00996  * out on a channel (when to hang up). If the absolute time out on a channel
00997  * is earlier than current time plus the offset, it returns 1, if the two
00998  * time values are equal, it return 0, otherwise, it return -1.
00999  * \since 1.6.1
01000  */
01001 int ast_channel_cmpwhentohangup_tv(struct ast_channel *chan, struct timeval offset);
01002 
01003 /*! \brief Set when to hang a channel up
01004  *
01005  * \param chan channel on which to check for hang up
01006  * \param offset offset in seconds relative to the current time of when to hang up
01007  *
01008  * This function sets the absolute time out on a channel (when to hang up).
01009  *
01010  * \note This function does not require that the channel is locked before
01011  *       calling it.
01012  *
01013  * \return Nothing
01014  * \sa ast_channel_setwhentohangup_tv()
01015  * \version 1.6.1 deprecated function (only had seconds precision)
01016  */
01017 void ast_channel_setwhentohangup(struct ast_channel *chan, time_t offset) __attribute__((deprecated));
01018 
01019 /*! \brief Set when to hang a channel up
01020  *
01021  * \param chan channel on which to check for hang up
01022  * \param offset offset in seconds and useconds relative to the current time of when to hang up
01023  *
01024  * This function sets the absolute time out on a channel (when to hang up).
01025  *
01026  * \note This function does not require that the channel is locked before
01027  * calling it.
01028  *
01029  * \return Nothing
01030  * \since 1.6.1
01031  */
01032 void ast_channel_setwhentohangup_tv(struct ast_channel *chan, struct timeval offset);
01033 
01034 /*!
01035  * \brief Answer a channel
01036  *
01037  * \param chan channel to answer
01038  *
01039  * This function answers a channel and handles all necessary call
01040  * setup functions.
01041  *
01042  * \note The channel passed does not need to be locked, but is locked
01043  * by the function when needed.
01044  *
01045  * \note This function will wait up to 500 milliseconds for media to
01046  * arrive on the channel before returning to the caller, so that the
01047  * caller can properly assume the channel is 'ready' for media flow.
01048  *
01049  * \retval 0 on success
01050  * \retval non-zero on failure
01051  */
01052 int ast_answer(struct ast_channel *chan);
01053 
01054 /*!
01055  * \brief Answer a channel
01056  *
01057  * \param chan channel to answer
01058  * \param cdr_answer flag to control whether any associated CDR should be marked as 'answered'
01059  *
01060  * This function answers a channel and handles all necessary call
01061  * setup functions.
01062  *
01063  * \note The channel passed does not need to be locked, but is locked
01064  * by the function when needed.
01065  *
01066  * \note Unlike ast_answer(), this function will not wait for media
01067  * flow to begin. The caller should be careful before sending media
01068  * to the channel before incoming media arrives, as the outgoing
01069  * media may be lost.
01070  *
01071  * \retval 0 on success
01072  * \retval non-zero on failure
01073  */
01074 int ast_raw_answer(struct ast_channel *chan, int cdr_answer);
01075 
01076 /*!
01077  * \brief Answer a channel, with a selectable delay before returning
01078  *
01079  * \param chan channel to answer
01080  * \param delay maximum amount of time to wait for incoming media
01081  * \param cdr_answer flag to control whether any associated CDR should be marked as 'answered'
01082  *
01083  * This function answers a channel and handles all necessary call
01084  * setup functions.
01085  *
01086  * \note The channel passed does not need to be locked, but is locked
01087  * by the function when needed.
01088  *
01089  * \note This function will wait up to 'delay' milliseconds for media to
01090  * arrive on the channel before returning to the caller, so that the
01091  * caller can properly assume the channel is 'ready' for media flow. If
01092  * 'delay' is less than 500, the function will wait up to 500 milliseconds.
01093  *
01094  * \retval 0 on success
01095  * \retval non-zero on failure
01096  */
01097 int __ast_answer(struct ast_channel *chan, unsigned int delay, int cdr_answer);
01098 
01099 /*! \brief Make a call
01100  * \param chan which channel to make the call on
01101  * \param addr destination of the call
01102  * \param timeout time to wait on for connect
01103  * Place a call, take no longer than timeout ms.
01104    \return Returns -1 on failure, 0 on not enough time
01105    (does not automatically stop ringing), and
01106    the number of seconds the connect took otherwise.
01107    */
01108 int ast_call(struct ast_channel *chan, char *addr, int timeout);
01109 
01110 /*! \brief Indicates condition of channel
01111  * \note Indicate a condition such as AST_CONTROL_BUSY, AST_CONTROL_RINGING, or AST_CONTROL_CONGESTION on a channel
01112  * \param chan channel to change the indication
01113  * \param condition which condition to indicate on the channel
01114  * \return Returns 0 on success, -1 on failure
01115  */
01116 int ast_indicate(struct ast_channel *chan, int condition);
01117 
01118 /*! \brief Indicates condition of channel, with payload
01119  * \note Indicate a condition such as AST_CONTROL_HOLD with payload being music on hold class
01120  * \param chan channel to change the indication
01121  * \param condition which condition to indicate on the channel
01122  * \param data pointer to payload data
01123  * \param datalen size of payload data
01124  * \return Returns 0 on success, -1 on failure
01125  */
01126 int ast_indicate_data(struct ast_channel *chan, int condition, const void *data, size_t datalen);
01127 
01128 /* Misc stuff ------------------------------------------------ */
01129 
01130 /*! \brief Wait for input on a channel
01131  * \param chan channel to wait on
01132  * \param ms length of time to wait on the channel
01133  * Wait for input on a channel for a given # of milliseconds (<0 for indefinite).
01134   \return Returns < 0 on  failure, 0 if nothing ever arrived, and the # of ms remaining otherwise */
01135 int ast_waitfor(struct ast_channel *chan, int ms);
01136 
01137 /*! \brief Wait for a specified amount of time, looking for hangups
01138  * \param chan channel to wait for
01139  * \param ms length of time in milliseconds to sleep
01140  * Waits for a specified amount of time, servicing the channel as required.
01141  * \return returns -1 on hangup, otherwise 0.
01142  */
01143 int ast_safe_sleep(struct ast_channel *chan, int ms);
01144 
01145 /*! \brief Wait for a specified amount of time, looking for hangups and a condition argument
01146  * \param chan channel to wait for
01147  * \param ms length of time in milliseconds to sleep
01148  * \param cond a function pointer for testing continue condition
01149  * \param data argument to be passed to the condition test function
01150  * \return returns -1 on hangup, otherwise 0.
01151  * Waits for a specified amount of time, servicing the channel as required. If cond
01152  * returns 0, this function returns.
01153  */
01154 int ast_safe_sleep_conditional(struct ast_channel *chan, int ms, int (*cond)(void*), void *data );
01155 
01156 /*! \brief Waits for activity on a group of channels
01157  * \param chan an array of pointers to channels
01158  * \param n number of channels that are to be waited upon
01159  * \param fds an array of fds to wait upon
01160  * \param nfds the number of fds to wait upon
01161  * \param exception exception flag
01162  * \param outfd fd that had activity on it
01163  * \param ms how long the wait was
01164  * Big momma function here.  Wait for activity on any of the n channels, or any of the nfds
01165    file descriptors.
01166    \return Returns the channel with activity, or NULL on error or if an FD
01167    came first.  If the FD came first, it will be returned in outfd, otherwise, outfd
01168    will be -1 */
01169 struct ast_channel *ast_waitfor_nandfds(struct ast_channel **chan, int n,
01170    int *fds, int nfds, int *exception, int *outfd, int *ms);
01171 
01172 /*! \brief Waits for input on a group of channels
01173    Wait for input on an array of channels for a given # of milliseconds.
01174    \return Return channel with activity, or NULL if none has activity.
01175    \param chan an array of pointers to channels
01176    \param n number of channels that are to be waited upon
01177    \param ms time "ms" is modified in-place, if applicable */
01178 struct ast_channel *ast_waitfor_n(struct ast_channel **chan, int n, int *ms);
01179 
01180 /*! \brief Waits for input on an fd
01181    This version works on fd's only.  Be careful with it. */
01182 int ast_waitfor_n_fd(int *fds, int n, int *ms, int *exception);
01183 
01184 
01185 /*! \brief Reads a frame
01186  * \param chan channel to read a frame from
01187  * \return Returns a frame, or NULL on error.  If it returns NULL, you
01188    best just stop reading frames and assume the channel has been
01189    disconnected. */
01190 struct ast_frame *ast_read(struct ast_channel *chan);
01191 
01192 /*! \brief Reads a frame, returning AST_FRAME_NULL frame if audio.
01193    \param chan channel to read a frame from
01194    \return  Returns a frame, or NULL on error.  If it returns NULL, you
01195       best just stop reading frames and assume the channel has been
01196       disconnected.
01197    \note Audio is replaced with AST_FRAME_NULL to avoid
01198    transcode when the resulting audio is not necessary. */
01199 struct ast_frame *ast_read_noaudio(struct ast_channel *chan);
01200 
01201 /*! \brief Write a frame to a channel
01202  * This function writes the given frame to the indicated channel.
01203  * \param chan destination channel of the frame
01204  * \param frame frame that will be written
01205  * \return It returns 0 on success, -1 on failure.
01206  */
01207 int ast_write(struct ast_channel *chan, struct ast_frame *frame);
01208 
01209 /*! \brief Write video frame to a channel
01210  * This function writes the given frame to the indicated channel.
01211  * \param chan destination channel of the frame
01212  * \param frame frame that will be written
01213  * \return It returns 1 on success, 0 if not implemented, and -1 on failure.
01214  */
01215 int ast_write_video(struct ast_channel *chan, struct ast_frame *frame);
01216 
01217 /*! \brief Write text frame to a channel
01218  * This function writes the given frame to the indicated channel.
01219  * \param chan destination channel of the frame
01220  * \param frame frame that will be written
01221  * \return It returns 1 on success, 0 if not implemented, and -1 on failure.
01222  */
01223 int ast_write_text(struct ast_channel *chan, struct ast_frame *frame);
01224 
01225 /*! \brief Send empty audio to prime a channel driver */
01226 int ast_prod(struct ast_channel *chan);
01227 
01228 /*! \brief Sets read format on channel chan
01229  * Set read format for channel to whichever component of "format" is best.
01230  * \param chan channel to change
01231  * \param format format to change to
01232  * \return Returns 0 on success, -1 on failure
01233  */
01234 int ast_set_read_format(struct ast_channel *chan, int format);
01235 
01236 /*! \brief Sets write format on channel chan
01237  * Set write format for channel to whichever component of "format" is best.
01238  * \param chan channel to change
01239  * \param format new format for writing
01240  * \return Returns 0 on success, -1 on failure
01241  */
01242 int ast_set_write_format(struct ast_channel *chan, int format);
01243 
01244 /*!
01245  * \brief Sends text to a channel
01246  *
01247  * \param chan channel to act upon
01248  * \param text string of text to send on the channel
01249  *
01250  * Write text to a display on a channel
01251  *
01252  * \note The channel does not need to be locked before calling this function.
01253  *
01254  * \retval 0 on success
01255  * \retval -1 on failure
01256  */
01257 int ast_sendtext(struct ast_channel *chan, const char *text);
01258 
01259 /*! \brief Receives a text character from a channel
01260  * \param chan channel to act upon
01261  * \param timeout timeout in milliseconds (0 for infinite wait)
01262  * Read a char of text from a channel
01263  * Returns 0 on success, -1 on failure
01264  */
01265 int ast_recvchar(struct ast_channel *chan, int timeout);
01266 
01267 /*! \brief Send a DTMF digit to a channel
01268  * Send a DTMF digit to a channel.
01269  * \param chan channel to act upon
01270  * \param digit the DTMF digit to send, encoded in ASCII
01271  * \param duration the duration of the digit ending in ms
01272  * \return Returns 0 on success, -1 on failure
01273  */
01274 int ast_senddigit(struct ast_channel *chan, char digit, unsigned int duration);
01275 
01276 /*! \brief Send a DTMF digit to a channel
01277  * Send a DTMF digit to a channel.
01278  * \param chan channel to act upon
01279  * \param digit the DTMF digit to send, encoded in ASCII
01280  * \return Returns 0 on success, -1 on failure
01281  */
01282 int ast_senddigit_begin(struct ast_channel *chan, char digit);
01283 
01284 /*! \brief Send a DTMF digit to a channel
01285 
01286  * Send a DTMF digit to a channel.
01287  * \param chan channel to act upon
01288  * \param digit the DTMF digit to send, encoded in ASCII
01289  * \param duration the duration of the digit ending in ms
01290  * \return Returns 0 on success, -1 on failure
01291  */
01292 int ast_senddigit_end(struct ast_channel *chan, char digit, unsigned int duration);
01293 
01294 /*! \brief Receives a text string from a channel
01295  * Read a string of text from a channel
01296  * \param chan channel to act upon
01297  * \param timeout timeout in milliseconds (0 for infinite wait)
01298  * \return the received text, or NULL to signify failure.
01299  */
01300 char *ast_recvtext(struct ast_channel *chan, int timeout);
01301 
01302 /*! \brief Browse channels in use
01303  * Browse the channels currently in use
01304  * \param prev where you want to start in the channel list
01305  * \return Returns the next channel in the list, NULL on end.
01306  *    If it returns a channel, that channel *has been locked*!
01307  */
01308 struct ast_channel *ast_channel_walk_locked(const struct ast_channel *prev);
01309 
01310 /*! \brief Get channel by name or uniqueid (locks channel) */
01311 struct ast_channel *ast_get_channel_by_name_locked(const char *chan);
01312 
01313 /*! \brief Get channel by name or uniqueid prefix (locks channel) */
01314 struct ast_channel *ast_get_channel_by_name_prefix_locked(const char *name, const int namelen);
01315 
01316 /*! \brief Get channel by name or uniqueid prefix (locks channel) */
01317 struct ast_channel *ast_walk_channel_by_name_prefix_locked(const struct ast_channel *chan, const char *name, const int namelen);
01318 
01319 /*! \brief Get channel by exten (and optionally context) and lock it */
01320 struct ast_channel *ast_get_channel_by_exten_locked(const char *exten, const char *context);
01321 
01322 /*! \brief Get next channel by exten (and optionally context) and lock it */
01323 struct ast_channel *ast_walk_channel_by_exten_locked(const struct ast_channel *chan, const char *exten,
01324                        const char *context);
01325 
01326 /*! ! \brief Waits for a digit
01327  * \param c channel to wait for a digit on
01328  * \param ms how many milliseconds to wait
01329  * \return Returns <0 on error, 0 on no entry, and the digit on success. */
01330 int ast_waitfordigit(struct ast_channel *c, int ms);
01331 
01332 /*! \brief Wait for a digit
01333  Same as ast_waitfordigit() with audio fd for outputting read audio and ctrlfd to monitor for reading.
01334  * \param c channel to wait for a digit on
01335  * \param ms how many milliseconds to wait
01336  * \param audiofd audio file descriptor to write to if audio frames are received
01337  * \param ctrlfd control file descriptor to monitor for reading
01338  * \return Returns 1 if ctrlfd becomes available */
01339 int ast_waitfordigit_full(struct ast_channel *c, int ms, int audiofd, int ctrlfd);
01340 
01341 /*! Reads multiple digits
01342  * \param c channel to read from
01343  * \param s string to read in to.  Must be at least the size of your length
01344  * \param len how many digits to read (maximum)
01345  * \param timeout how long to timeout between digits
01346  * \param rtimeout timeout to wait on the first digit
01347  * \param enders digits to end the string
01348  * Read in a digit string "s", max length "len", maximum timeout between
01349    digits "timeout" (-1 for none), terminated by anything in "enders".  Give them rtimeout
01350    for the first digit.  Returns 0 on normal return, or 1 on a timeout.  In the case of
01351    a timeout, any digits that were read before the timeout will still be available in s.
01352    RETURNS 2 in full version when ctrlfd is available, NOT 1*/
01353 int ast_readstring(struct ast_channel *c, char *s, int len, int timeout, int rtimeout, char *enders);
01354 int ast_readstring_full(struct ast_channel *c, char *s, int len, int timeout, int rtimeout, char *enders, int audiofd, int ctrlfd);
01355 
01356 /*! \brief Report DTMF on channel 0 */
01357 #define AST_BRIDGE_DTMF_CHANNEL_0      (1 << 0)
01358 /*! \brief Report DTMF on channel 1 */
01359 #define AST_BRIDGE_DTMF_CHANNEL_1      (1 << 1)
01360 /*! \brief Return all voice frames on channel 0 */
01361 #define AST_BRIDGE_REC_CHANNEL_0    (1 << 2)
01362 /*! \brief Return all voice frames on channel 1 */
01363 #define AST_BRIDGE_REC_CHANNEL_1    (1 << 3)
01364 /*! \brief Ignore all signal frames except NULL */
01365 #define AST_BRIDGE_IGNORE_SIGS         (1 << 4)
01366 
01367 
01368 /*! \brief Makes two channel formats compatible
01369  * \param c0 first channel to make compatible
01370  * \param c1 other channel to make compatible
01371  * Set two channels to compatible formats -- call before ast_channel_bridge in general .
01372  * \return Returns 0 on success and -1 if it could not be done */
01373 int ast_channel_make_compatible(struct ast_channel *c0, struct ast_channel *c1);
01374 
01375 /*! Bridge two channels together (early)
01376  * \param c0 first channel to bridge
01377  * \param c1 second channel to bridge
01378  * Bridge two channels (c0 and c1) together early. This implies either side may not be answered yet.
01379  * \return Returns 0 on success and -1 if it could not be done */
01380 int ast_channel_early_bridge(struct ast_channel *c0, struct ast_channel *c1);
01381 
01382 /*! Bridge two channels together
01383  * \param c0 first channel to bridge
01384  * \param c1 second channel to bridge
01385  * \param config config for the channels
01386  * \param fo destination frame(?)
01387  * \param rc destination channel(?)
01388  * Bridge two channels (c0 and c1) together.  If an important frame occurs, we return that frame in
01389    *rf (remember, it could be NULL) and which channel (0 or 1) in rc */
01390 /* int ast_channel_bridge(struct ast_channel *c0, struct ast_channel *c1, int flags, struct ast_frame **fo, struct ast_channel **rc); */
01391 int ast_channel_bridge(struct ast_channel *c0,struct ast_channel *c1,
01392    struct ast_bridge_config *config, struct ast_frame **fo, struct ast_channel **rc);
01393 
01394 /*!
01395  * \brief Weird function made for call transfers
01396  *
01397  * \param original channel to make a copy of
01398  * \param clone copy of the original channel
01399  *
01400  * This is a very strange and freaky function used primarily for transfer.  Suppose that
01401  * "original" and "clone" are two channels in random situations.  This function takes
01402  * the guts out of "clone" and puts them into the "original" channel, then alerts the
01403  * channel driver of the change, asking it to fixup any private information (like the
01404  * p->owner pointer) that is affected by the change.  The physical layer of the original
01405  * channel is hung up.
01406  *
01407  * \note Neither channel passed here needs to be locked before calling this function.
01408  */
01409 int ast_channel_masquerade(struct ast_channel *original, struct ast_channel *clone);
01410 
01411 /*! Gives the string form of a given cause code */
01412 /*!
01413  * \param state cause to get the description of
01414  * Give a name to a cause code
01415  * Returns the text form of the binary cause code given
01416  */
01417 const char *ast_cause2str(int state) attribute_pure;
01418 
01419 /*! Convert the string form of a cause code to a number */
01420 /*!
01421  * \param name string form of the cause
01422  * Returns the cause code
01423  */
01424 int ast_str2cause(const char *name) attribute_pure;
01425 
01426 /*! Gives the string form of a given channel state */
01427 /*!
01428  * \param ast_channel_state state to get the name of
01429  * Give a name to a state
01430  * Returns the text form of the binary state given
01431  */
01432 const char *ast_state2str(enum ast_channel_state);
01433 
01434 /*! Gives the string form of a given transfer capability */
01435 /*!
01436  * \param transfercapability transfercapabilty to get the name of
01437  * Give a name to a transfercapbility
01438  * See above
01439  * Returns the text form of the binary transfer capability
01440  */
01441 char *ast_transfercapability2str(int transfercapability) attribute_const;
01442 
01443 /* Options: Some low-level drivers may implement "options" allowing fine tuning of the
01444    low level channel.  See frame.h for options.  Note that many channel drivers may support
01445    none or a subset of those features, and you should not count on this if you want your
01446    asterisk application to be portable.  They're mainly useful for tweaking performance */
01447 
01448 /*! Sets an option on a channel */
01449 /*!
01450  * \param channel channel to set options on
01451  * \param option option to change
01452  * \param data data specific to option
01453  * \param datalen length of the data
01454  * \param block blocking or not
01455  * Set an option on a channel (see frame.h), optionally blocking awaiting the reply
01456  * Returns 0 on success and -1 on failure
01457  */
01458 int ast_channel_setoption(struct ast_channel *channel, int option, void *data, int datalen, int block);
01459 
01460 /*! Pick the best codec  */
01461 /* Choose the best codec...  Uhhh...   Yah. */
01462 int ast_best_codec(int fmts);
01463 
01464 
01465 /*! Checks the value of an option */
01466 /*!
01467  * Query the value of an option
01468  * Works similarly to setoption except only reads the options.
01469  */
01470 int ast_channel_queryoption(struct ast_channel *channel, int option, void *data, int *datalen, int block);
01471 
01472 /*! Checks for HTML support on a channel */
01473 /*! Returns 0 if channel does not support HTML or non-zero if it does */
01474 int ast_channel_supports_html(struct ast_channel *channel);
01475 
01476 /*! Sends HTML on given channel */
01477 /*! Send HTML or URL on link.  Returns 0 on success or -1 on failure */
01478 int ast_channel_sendhtml(struct ast_channel *channel, int subclass, const char *data, int datalen);
01479 
01480 /*! Sends a URL on a given link */
01481 /*! Send URL on link.  Returns 0 on success or -1 on failure */
01482 int ast_channel_sendurl(struct ast_channel *channel, const char *url);
01483 
01484 /*! Defers DTMF */
01485 /*! Defer DTMF so that you only read things like hangups and audio.  Returns
01486    non-zero if channel was already DTMF-deferred or 0 if channel is just now
01487    being DTMF-deferred */
01488 int ast_channel_defer_dtmf(struct ast_channel *chan);
01489 
01490 /*! Undo defer.  ast_read will return any dtmf characters that were queued */
01491 void ast_channel_undefer_dtmf(struct ast_channel *chan);
01492 
01493 /*! Initiate system shutdown -- prevents new channels from being allocated.
01494     If "hangup" is non-zero, all existing channels will receive soft
01495      hangups */
01496 void ast_begin_shutdown(int hangup);
01497 
01498 /*! Cancels an existing shutdown and returns to normal operation */
01499 void ast_cancel_shutdown(void);
01500 
01501 /*! Returns number of active/allocated channels */
01502 int ast_active_channels(void);
01503 
01504 /*! Returns non-zero if Asterisk is being shut down */
01505 int ast_shutting_down(void);
01506 
01507 /*! Activate a given generator */
01508 int ast_activate_generator(struct ast_channel *chan, struct ast_generator *gen, void *params);
01509 
01510 /*! Deactivate an active generator */
01511 void ast_deactivate_generator(struct ast_channel *chan);
01512 
01513 /*!
01514  * \brief Set caller ID number, name and ANI
01515  *
01516  * \note The channel does not need to be locked before calling this function.
01517  */
01518 void ast_set_callerid(struct ast_channel *chan, const char *cid_num, const char *cid_name, const char *cid_ani);
01519 
01520 /*! Set the file descriptor on the channel */
01521 void ast_channel_set_fd(struct ast_channel *chan, int which, int fd);
01522 
01523 /*! Add a channel to an optimized waitfor */
01524 void ast_poll_channel_add(struct ast_channel *chan0, struct ast_channel *chan1);
01525 
01526 /*! Delete a channel from an optimized waitfor */
01527 void ast_poll_channel_del(struct ast_channel *chan0, struct ast_channel *chan1);
01528 
01529 /*! Start a tone going */
01530 int ast_tonepair_start(struct ast_channel *chan, int freq1, int freq2, int duration, int vol);
01531 /*! Stop a tone from playing */
01532 void ast_tonepair_stop(struct ast_channel *chan);
01533 /*! Play a tone pair for a given amount of time */
01534 int ast_tonepair(struct ast_channel *chan, int freq1, int freq2, int duration, int vol);
01535 
01536 /*!
01537  * \brief Automatically service a channel for us...
01538  *
01539  * \retval 0 success
01540  * \retval -1 failure, or the channel is already being autoserviced
01541  */
01542 int ast_autoservice_start(struct ast_channel *chan);
01543 
01544 /*!
01545  * \brief Stop servicing a channel for us...
01546  *
01547  * \note if chan is locked prior to calling ast_autoservice_stop, it
01548  * is likely that there will be a deadlock between the thread that calls
01549  * ast_autoservice_stop and the autoservice thread. It is important
01550  * that chan is not locked prior to this call
01551  *
01552  * \retval 0 success
01553  * \retval -1 error, or the channel has been hungup
01554  */
01555 int ast_autoservice_stop(struct ast_channel *chan);
01556 
01557 /*!
01558  * \brief Enable or disable timer ticks for a channel
01559  *
01560  * \param rate number of timer ticks per second
01561  *
01562  * If timers are supported, force a scheduled expiration on the
01563  * timer fd, at which point we call the callback function / data
01564  *
01565  * Call this function with a rate of 0 to turn off the timer ticks
01566  *
01567  * \version 1.6.1 changed samples parameter to rate, accomodates new timing methods
01568  */
01569 int ast_settimeout(struct ast_channel *c, unsigned int rate, int (*func)(const void *data), void *data);
01570 
01571 /*!   \brief Transfer a channel (if supported).  Returns -1 on error, 0 if not supported
01572    and 1 if supported and requested
01573    \param chan current channel
01574    \param dest destination extension for transfer
01575 */
01576 int ast_transfer(struct ast_channel *chan, char *dest);
01577 
01578 /*!   \brief  Start masquerading a channel
01579    XXX This is a seriously whacked out operation.  We're essentially putting the guts of
01580            the clone channel into the original channel.  Start by killing off the original
01581            channel's backend.   I'm not sure we're going to keep this function, because
01582            while the features are nice, the cost is very high in terms of pure nastiness. XXX
01583    \param chan    Channel to masquerade
01584 */
01585 int ast_do_masquerade(struct ast_channel *chan);
01586 
01587 /*!   \brief Find bridged channel
01588    \param chan Current channel
01589 */
01590 struct ast_channel *ast_bridged_channel(struct ast_channel *chan);
01591 
01592 /*!
01593   \brief Inherits channel variable from parent to child channel
01594   \param parent Parent channel
01595   \param child Child channel
01596 
01597   Scans all channel variables in the parent channel, looking for those
01598   that should be copied into the child channel.
01599   Variables whose names begin with a single '_' are copied into the
01600   child channel with the prefix removed.
01601   Variables whose names begin with '__' are copied into the child
01602   channel with their names unchanged.
01603 */
01604 void ast_channel_inherit_variables(const struct ast_channel *parent, struct ast_channel *child);
01605 
01606 /*!
01607   \brief adds a list of channel variables to a channel
01608   \param chan the channel
01609   \param vars a linked list of variables
01610 
01611   Variable names can be for a regular channel variable or a dialplan function
01612   that has the ability to be written to.
01613 */
01614 void ast_set_variables(struct ast_channel *chan, struct ast_variable *vars);
01615 
01616 /*!
01617   \brief An opaque 'object' structure use by silence generators on channels.
01618  */
01619 struct ast_silence_generator;
01620 
01621 /*!
01622   \brief Starts a silence generator on the given channel.
01623   \param chan The channel to generate silence on
01624   \return An ast_silence_generator pointer, or NULL if an error occurs
01625 
01626   This function will cause SLINEAR silence to be generated on the supplied
01627   channel until it is disabled; if the channel cannot be put into SLINEAR
01628   mode then the function will fail.
01629 
01630   The pointer returned by this function must be preserved and passed to
01631   ast_channel_stop_silence_generator when you wish to stop the silence
01632   generation.
01633  */
01634 struct ast_silence_generator *ast_channel_start_silence_generator(struct ast_channel *chan);
01635 
01636 /*!
01637   \brief Stops a previously-started silence generator on the given channel.
01638   \param chan The channel to operate on
01639   \param state The ast_silence_generator pointer return by a previous call to
01640   ast_channel_start_silence_generator.
01641   \return nothing
01642 
01643   This function will stop the operating silence generator and return the channel
01644   to its previous write format.
01645  */
01646 void ast_channel_stop_silence_generator(struct ast_channel *chan, struct ast_silence_generator *state);
01647 
01648 /*!
01649   \brief Check if the channel can run in internal timing mode.
01650   \param chan The channel to check
01651   \return boolean
01652 
01653   This function will return 1 if internal timing is enabled and the timing
01654   device is available.
01655  */
01656 int ast_internal_timing_enabled(struct ast_channel *chan);
01657 
01658 /* Misc. functions below */
01659 
01660 /*! \brief if fd is a valid descriptor, set *pfd with the descriptor
01661  * \return Return 1 (not -1!) if added, 0 otherwise (so we can add the
01662  * return value to the index into the array)
01663  */
01664 static inline int ast_add_fd(struct pollfd *pfd, int fd)
01665 {
01666    pfd->fd = fd;
01667    pfd->events = POLLIN | POLLPRI;
01668    return fd >= 0;
01669 }
01670 
01671 /*! \brief Helper function for migrating select to poll */
01672 static inline int ast_fdisset(struct pollfd *pfds, int fd, int maximum, int *start)
01673 {
01674    int x;
01675    int dummy = 0;
01676 
01677    if (fd < 0)
01678       return 0;
01679    if (!start)
01680       start = &dummy;
01681    for (x = *start; x < maximum; x++)
01682       if (pfds[x].fd == fd) {
01683          if (x == *start)
01684             (*start)++;
01685          return pfds[x].revents;
01686       }
01687    return 0;
01688 }
01689 
01690 #ifndef HAVE_TIMERSUB
01691 static inline void timersub(struct timeval *tvend, struct timeval *tvstart, struct timeval *tvdiff)
01692 {
01693    tvdiff->tv_sec = tvend->tv_sec - tvstart->tv_sec;
01694    tvdiff->tv_usec = tvend->tv_usec - tvstart->tv_usec;
01695    if (tvdiff->tv_usec < 0) {
01696       tvdiff->tv_sec --;
01697       tvdiff->tv_usec += 1000000;
01698    }
01699 
01700 }
01701 #endif
01702 
01703 /*! \brief Waits for activity on a group of channels
01704  * \param nfds the maximum number of file descriptors in the sets
01705  * \param rfds file descriptors to check for read availability
01706  * \param wfds file descriptors to check for write availability
01707  * \param efds file descriptors to check for exceptions (OOB data)
01708  * \param tvp timeout while waiting for events
01709  * This is the same as a standard select(), except it guarantees the
01710  * behaviour where the passed struct timeval is updated with how much
01711  * time was not slept while waiting for the specified events
01712  */
01713 static inline int ast_select(int nfds, fd_set *rfds, fd_set *wfds, fd_set *efds, struct timeval *tvp)
01714 {
01715 #ifdef __linux__
01716    return select(nfds, rfds, wfds, efds, tvp);
01717 #else
01718    if (tvp) {
01719       struct timeval tv, tvstart, tvend, tvlen;
01720       int res;
01721 
01722       tv = *tvp;
01723       gettimeofday(&tvstart, NULL);
01724       res = select(nfds, rfds, wfds, efds, tvp);
01725       gettimeofday(&tvend, NULL);
01726       timersub(&tvend, &tvstart, &tvlen);
01727       timersub(&tv, &tvlen, tvp);
01728       if (tvp->tv_sec < 0 || (tvp->tv_sec == 0 && tvp->tv_usec < 0)) {
01729          tvp->tv_sec = 0;
01730          tvp->tv_usec = 0;
01731       }
01732       return res;
01733    }
01734    else
01735       return select(nfds, rfds, wfds, efds, NULL);
01736 #endif
01737 }
01738 
01739 /*! \brief Retrieves the current T38 state of a channel */
01740 static inline enum ast_t38_state ast_channel_get_t38_state(struct ast_channel *chan)
01741 {
01742    enum ast_t38_state state = T38_STATE_UNAVAILABLE;
01743    int datalen = sizeof(state);
01744 
01745    ast_channel_queryoption(chan, AST_OPTION_T38_STATE, &state, &datalen, 0);
01746 
01747    return state;
01748 }
01749 
01750 #define CHECK_BLOCKING(c) do {    \
01751    if (ast_test_flag(c, AST_FLAG_BLOCKING)) {\
01752       if (option_debug) \
01753          ast_log(LOG_DEBUG, "Thread %ld Blocking '%s', already blocked by thread %ld in procedure %s\n", (long) pthread_self(), (c)->name, (long) (c)->blocker, (c)->blockproc); \
01754    } else { \
01755       (c)->blocker = pthread_self(); \
01756       (c)->blockproc = __PRETTY_FUNCTION__; \
01757       ast_set_flag(c, AST_FLAG_BLOCKING); \
01758    } } while (0)
01759 
01760 ast_group_t ast_get_group(const char *s);
01761 
01762 /*! \brief print call- and pickup groups into buffer */
01763 char *ast_print_group(char *buf, int buflen, ast_group_t group);
01764 
01765 /*! \brief Convert enum channelreloadreason to text string for manager event
01766    \param reason  Enum channelreloadreason - reason for reload (manager, cli, start etc)
01767 */
01768 const char *channelreloadreason2txt(enum channelreloadreason reason);
01769 
01770 /*! \brief return an ast_variable list of channeltypes */
01771 struct ast_variable *ast_channeltype_list(void);
01772 
01773 /*!
01774   \brief return an english explanation of the code returned thru __ast_request_and_dial's 'outstate' argument
01775   \param reason  The integer argument, usually taken from AST_CONTROL_ macros
01776   \return char pointer explaining the code
01777  */
01778 const char *ast_channel_reason2str(int reason);
01779 
01780 /*! \brief channel group info
01781  */
01782 struct ast_group_info {
01783    struct ast_channel *chan;
01784    char *category;
01785    char *group;
01786    AST_LIST_ENTRY(ast_group_info) group_list;
01787 };
01788 
01789 
01790 #if defined(__cplusplus) || defined(c_plusplus)
01791 }
01792 #endif
01793 
01794 #endif /* _ASTERISK_CHANNEL_H */

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