Wed Oct 28 15:47:51 2009

Asterisk developer's documentation


chan_nbs.c

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00001 /*
00002  * Asterisk -- An open source telephony toolkit.
00003  *
00004  * Copyright (C) 1999 - 2005, 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  *
00021  * \brief Network broadcast sound support channel driver
00022  * 
00023  * \author Mark Spencer <markster@digium.com>
00024  *
00025  * \ingroup channel_drivers
00026  */
00027 
00028 #include <stdio.h>
00029 #include <string.h>
00030 #include <sys/socket.h>
00031 #include <sys/time.h>
00032 #include <errno.h>
00033 #include <unistd.h>
00034 #include <stdlib.h>
00035 #include <arpa/inet.h>
00036 #include <fcntl.h>
00037 #include <sys/ioctl.h>
00038 #include <nbs.h>
00039 
00040 #include "asterisk.h"
00041 
00042 ASTERISK_FILE_VERSION(__FILE__, "$Revision: 7221 $")
00043 
00044 #include "asterisk/lock.h"
00045 #include "asterisk/channel.h"
00046 #include "asterisk/config.h"
00047 #include "asterisk/logger.h"
00048 #include "asterisk/module.h"
00049 #include "asterisk/pbx.h"
00050 #include "asterisk/options.h"
00051 #include "asterisk/utils.h"
00052 
00053 static const char desc[] = "Network Broadcast Sound Support";
00054 static const char type[] = "NBS";
00055 static const char tdesc[] = "Network Broadcast Sound Driver";
00056 
00057 static int usecnt =0;
00058 
00059 /* Only linear is allowed */
00060 static int prefformat = AST_FORMAT_SLINEAR;
00061 
00062 AST_MUTEX_DEFINE_STATIC(usecnt_lock);
00063 
00064 static char context[AST_MAX_EXTENSION] = "default";
00065 
00066 /* NBS creates private structures on demand */
00067    
00068 struct nbs_pvt {
00069    NBS *nbs;
00070    struct ast_channel *owner;    /* Channel we belong to, possibly NULL */
00071    char app[16];              /* Our app */
00072    char stream[80];           /* Our stream */
00073    struct ast_frame fr;       /* "null" frame */
00074 };
00075 
00076 static struct ast_channel *nbs_request(const char *type, int format, void *data, int *cause);
00077 static int nbs_call(struct ast_channel *ast, char *dest, int timeout);
00078 static int nbs_hangup(struct ast_channel *ast);
00079 static struct ast_frame *nbs_xread(struct ast_channel *ast);
00080 static int nbs_xwrite(struct ast_channel *ast, struct ast_frame *frame);
00081 
00082 static const struct ast_channel_tech nbs_tech = {
00083    .type = type,
00084    .description = tdesc,
00085    .capabilities = AST_FORMAT_SLINEAR,
00086    .requester = nbs_request,
00087    .call = nbs_call,
00088    .hangup = nbs_hangup,
00089    .read = nbs_xread,
00090    .write = nbs_xwrite,
00091 };
00092 
00093 static int nbs_call(struct ast_channel *ast, char *dest, int timeout)
00094 {
00095    struct nbs_pvt *p;
00096 
00097    p = ast->tech_pvt;
00098 
00099    if ((ast->_state != AST_STATE_DOWN) && (ast->_state != AST_STATE_RESERVED)) {
00100       ast_log(LOG_WARNING, "nbs_call called on %s, neither down nor reserved\n", ast->name);
00101       return -1;
00102    }
00103    /* When we call, it just works, really, there's no destination...  Just
00104       ring the phone and wait for someone to answer */
00105    if (option_debug)
00106       ast_log(LOG_DEBUG, "Calling %s on %s\n", dest, ast->name);
00107 
00108    /* If we can't connect, return congestion */
00109    if (nbs_connect(p->nbs)) {
00110       ast_log(LOG_WARNING, "NBS Connection failed on %s\n", ast->name);
00111       ast_queue_control(ast, AST_CONTROL_CONGESTION);
00112    } else {
00113       ast_setstate(ast, AST_STATE_RINGING);
00114       ast_queue_control(ast, AST_CONTROL_ANSWER);
00115    }
00116 
00117    return 0;
00118 }
00119 
00120 static void nbs_destroy(struct nbs_pvt *p)
00121 {
00122    if (p->nbs)
00123       nbs_delstream(p->nbs);
00124    free(p);
00125 }
00126 
00127 static struct nbs_pvt *nbs_alloc(void *data)
00128 {
00129    struct nbs_pvt *p;
00130    int flags = 0;
00131    char stream[256] = "";
00132    char *opts;
00133    strncpy(stream, data, sizeof(stream) - 1);
00134    if ((opts = strchr(stream, ':'))) {
00135       *opts = '\0';
00136       opts++;
00137    } else
00138       opts = "";
00139    p = malloc(sizeof(struct nbs_pvt));
00140    if (p) {
00141       memset(p, 0, sizeof(struct nbs_pvt));
00142       if (!ast_strlen_zero(opts)) {
00143          if (strchr(opts, 'm'))
00144             flags |= NBS_FLAG_MUTE;
00145          if (strchr(opts, 'o'))
00146             flags |= NBS_FLAG_OVERSPEAK;
00147          if (strchr(opts, 'e'))
00148             flags |= NBS_FLAG_EMERGENCY;
00149          if (strchr(opts, 'O'))
00150             flags |= NBS_FLAG_OVERRIDE;
00151       } else
00152          flags = NBS_FLAG_OVERSPEAK;
00153       
00154       strncpy(p->stream, stream, sizeof(p->stream) - 1);
00155       p->nbs = nbs_newstream("asterisk", stream, flags);
00156       if (!p->nbs) {
00157          ast_log(LOG_WARNING, "Unable to allocate new NBS stream '%s' with flags %d\n", stream, flags);
00158          free(p);
00159          p = NULL;
00160       } else {
00161          /* Set for 8000 hz mono, 640 samples */
00162          nbs_setbitrate(p->nbs, 8000);
00163          nbs_setchannels(p->nbs, 1);
00164          nbs_setblocksize(p->nbs, 640);
00165          nbs_setblocking(p->nbs, 0);
00166       }
00167    }
00168    return p;
00169 }
00170 
00171 static int nbs_hangup(struct ast_channel *ast)
00172 {
00173    struct nbs_pvt *p;
00174    p = ast->tech_pvt;
00175    if (option_debug)
00176       ast_log(LOG_DEBUG, "nbs_hangup(%s)\n", ast->name);
00177    if (!ast->tech_pvt) {
00178       ast_log(LOG_WARNING, "Asked to hangup channel not connected\n");
00179       return 0;
00180    }
00181    nbs_destroy(p);
00182    ast->tech_pvt = NULL;
00183    ast_setstate(ast, AST_STATE_DOWN);
00184    return 0;
00185 }
00186 
00187 static struct ast_frame  *nbs_xread(struct ast_channel *ast)
00188 {
00189    struct nbs_pvt *p = ast->tech_pvt;
00190    
00191 
00192    /* Some nice norms */
00193    p->fr.datalen = 0;
00194    p->fr.samples = 0;
00195    p->fr.data =  NULL;
00196    p->fr.src = type;
00197    p->fr.offset = 0;
00198    p->fr.mallocd=0;
00199    p->fr.delivery.tv_sec = 0;
00200    p->fr.delivery.tv_usec = 0;
00201 
00202    ast_log(LOG_DEBUG, "Returning null frame on %s\n", ast->name);
00203 
00204    return &p->fr;
00205 }
00206 
00207 static int nbs_xwrite(struct ast_channel *ast, struct ast_frame *frame)
00208 {
00209    struct nbs_pvt *p = ast->tech_pvt;
00210    /* Write a frame of (presumably voice) data */
00211    if (frame->frametype != AST_FRAME_VOICE) {
00212       if (frame->frametype != AST_FRAME_IMAGE)
00213          ast_log(LOG_WARNING, "Don't know what to do with  frame type '%d'\n", frame->frametype);
00214       return 0;
00215    }
00216    if (!(frame->subclass &
00217       (AST_FORMAT_SLINEAR))) {
00218       ast_log(LOG_WARNING, "Cannot handle frames in %d format\n", frame->subclass);
00219       return 0;
00220    }
00221    if (ast->_state != AST_STATE_UP) {
00222       /* Don't try tos end audio on-hook */
00223       return 0;
00224    }
00225    if (nbs_write(p->nbs, frame->data, frame->datalen / 2) < 0) 
00226       return -1;
00227    return 0;
00228 }
00229 
00230 static struct ast_channel *nbs_new(struct nbs_pvt *i, int state)
00231 {
00232    struct ast_channel *tmp;
00233    tmp = ast_channel_alloc(1);
00234    if (tmp) {
00235       tmp->tech = &nbs_tech;
00236       snprintf(tmp->name, sizeof(tmp->name), "NBS/%s", i->stream);
00237       tmp->type = type;
00238       tmp->fds[0] = nbs_fd(i->nbs);
00239       tmp->nativeformats = prefformat;
00240       tmp->rawreadformat = prefformat;
00241       tmp->rawwriteformat = prefformat;
00242       tmp->writeformat = prefformat;
00243       tmp->readformat = prefformat;
00244       ast_setstate(tmp, state);
00245       if (state == AST_STATE_RING)
00246          tmp->rings = 1;
00247       tmp->tech_pvt = i;
00248       strncpy(tmp->context, context, sizeof(tmp->context)-1);
00249       strncpy(tmp->exten, "s",  sizeof(tmp->exten) - 1);
00250       tmp->language[0] = '\0';
00251       i->owner = tmp;
00252       ast_mutex_lock(&usecnt_lock);
00253       usecnt++;
00254       ast_mutex_unlock(&usecnt_lock);
00255       ast_update_use_count();
00256       if (state != AST_STATE_DOWN) {
00257          if (ast_pbx_start(tmp)) {
00258             ast_log(LOG_WARNING, "Unable to start PBX on %s\n", tmp->name);
00259             ast_hangup(tmp);
00260          }
00261       }
00262    } else
00263       ast_log(LOG_WARNING, "Unable to allocate channel structure\n");
00264    return tmp;
00265 }
00266 
00267 
00268 static struct ast_channel *nbs_request(const char *type, int format, void *data, int *cause)
00269 {
00270    int oldformat;
00271    struct nbs_pvt *p;
00272    struct ast_channel *tmp = NULL;
00273    
00274    oldformat = format;
00275    format &= (AST_FORMAT_SLINEAR);
00276    if (!format) {
00277       ast_log(LOG_NOTICE, "Asked to get a channel of unsupported format '%d'\n", oldformat);
00278       return NULL;
00279    }
00280    p = nbs_alloc(data);
00281    if (p) {
00282       tmp = nbs_new(p, AST_STATE_DOWN);
00283       if (!tmp)
00284          nbs_destroy(p);
00285    }
00286    return tmp;
00287 }
00288 
00289 static int __unload_module(void)
00290 {
00291    /* First, take us out of the channel loop */
00292    ast_channel_unregister(&nbs_tech);
00293    return 0;
00294 }
00295 
00296 int unload_module(void)
00297 {
00298    return __unload_module();
00299 }
00300 
00301 int load_module()
00302 {
00303    /* Make sure we can register our channel type */
00304    if (ast_channel_register(&nbs_tech)) {
00305       ast_log(LOG_ERROR, "Unable to register channel class %s\n", type);
00306       __unload_module();
00307       return -1;
00308    }
00309    return 0;
00310 }
00311 
00312 int usecount()
00313 {
00314    return usecnt;
00315 }
00316 
00317 char *description()
00318 {
00319    return (char *) desc;
00320 }
00321 
00322 char *key()
00323 {
00324    return ASTERISK_GPL_KEY;
00325 }

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