Get real channel of a DAHDI call.

Starting with Asterisk v1.8, the DAHDI channel name format was changed for
ISDN calls to: DAHDI/i<span>/<number>[:<subaddress>]-<sequence-number>

There were several reasons that the channel name had to change.

1) Call completion requires a device state for ISDN phones.  The generic
device state uses the channel name.

2) Calls do not necessarily have B channels.  Calls placed on hold by an
ISDN phone do not have B channels.

3) The B channel a call initially requests may not be the B channel the
call ultimately uses.  Changes to the internal implementation of the
Asterisk master channel list caused deadlock problems for chan_dahdi if it
needed to change the channel name.  Chan_dahdi no longer changes the
channel name.

4) DTMF attended transfers now work with ISDN phones because the channel
name is "dialable" like the chan_sip channel names.

For various reasons, some people need to know which B channel a DAHDI call
is using.

* Added CHANNEL(dahdi_span), CHANNEL(dahdi_channel), and
CHANNEL(dahdi_type) so the dialplan can determine the B channel currently
in use by the channel.  Use CHANNEL(no_media_path) to determine if the
channel even has a B channel.

* Added AMI event DAHDIChannel to associate a DAHDI channel with an
Asterisk channel so AMI applications can passively determine the B channel
currently in use.  Calls with "no-media" as the DAHDIChannel do not have
an associated B channel.  No-media calls are either on hold or
call-waiting.

(closes issue #17683)
Reported by: mrwho
Tested by: rmudgett

(closes issue #18603)
Reported by: arjankroon
Patches:
      issue17683_18603_v1.8_v2.patch uploaded by rmudgett (license 664)
Tested by: stever28, rmudgett


git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/1.8@309445 65c4cc65-6c06-0410-ace0-fbb531ad65f3

UPGRADE.txt

@@ -72,6 +72,15 @@ From 1.6.2 to 1.8:
   The new channel naming for PRI channels is:
   DAHDI/i<span>/<number>[:<subaddress>]-<sequence-number>
 
+* Added CHANNEL(dahdi_span), CHANNEL(dahdi_channel), and CHANNEL(dahdi_type)
+  so the dialplan can determine the B channel currently in use by the channel.
+  Use CHANNEL(no_media_path) to determine if the channel even has a B channel.
+
+* Added AMI event DAHDIChannel to associate a DAHDI channel with an Asterisk
+  channel so AMI applications can passively determine the B channel currently
+  in use.  Calls with "no-media" as the DAHDIChannel do not have an associated
+  B channel.  No-media calls are either on hold or call-waiting.
+
 * The ChanIsAvail application has been changed so the AVAILSTATUS variable
   no longer contains both the device state and cause code. The cause code
   is now available in the AVAILCAUSECODE variable. If existing dialplan logic

channels/chan_dahdi.c

@@ -2087,6 +2087,58 @@ static void my_deadlock_avoidance_private(void *pvt)
 	DEADLOCK_AVOIDANCE(&p->lock);
 }
 
+/*!
+ * \internal
+ * \brief Post an AMI DAHDI channel association event.
+ * \since 1.8
+ *
+ * \param p DAHDI private pointer
+ * \param chan Channel associated with the private pointer
+ *
+ * \return Nothing
+ */
+static void dahdi_ami_channel_event(struct dahdi_pvt *p, struct ast_channel *chan)
+{
+	char ch_name[20];
+
+	if (p->channel < CHAN_PSEUDO) {
+		/* No B channel */
+		snprintf(ch_name, sizeof(ch_name), "no-media (%d)", p->channel);
+	} else if (p->channel == CHAN_PSEUDO) {
+		/* Pseudo channel */
+		strcpy(ch_name, "pseudo");
+	} else {
+		/* Real channel */
+		snprintf(ch_name, sizeof(ch_name), "%d", p->channel);
+	}
+	ast_manager_event(chan, EVENT_FLAG_CALL, "DAHDIChannel",
+		"Channel: %s\r\n"
+		"Uniqueid: %s\r\n"
+		"DAHDISpan: %d\r\n"
+		"DAHDIChannel: %s\r\n",
+		chan->name,
+		chan->uniqueid,
+		p->span,
+		ch_name);
+}
+
+/*!
+ * \internal
+ * \brief Post an AMI DAHDI channel association event.
+ * \since 1.8
+ *
+ * \param pvt DAHDI private pointer
+ * \param chan Channel associated with the private pointer
+ *
+ * \return Nothing
+ */
+static void my_ami_channel_event(void *pvt, struct ast_channel *chan)
+{
+	struct dahdi_pvt *p = pvt;
+
+	dahdi_ami_channel_event(p, chan);
+}
+
 /* linear_mode = 0 - turn linear mode off, >0 - turn linear mode on
 * 	returns the last value of the linear setting 
 */ 
@@ -3272,6 +3324,7 @@ static struct sig_pri_callback dahdi_pri_callbacks =
 	.module_ref = my_module_ref,
 	.module_unref = my_module_unref,
 	.open_media = my_pri_open_media,
+	.ami_channel_event = my_ami_channel_event,
 };
 #endif	/* defined(HAVE_PRI) */
 
@@ -6742,6 +6795,41 @@ static int dahdi_func_read(struct ast_channel *chan, const char *function, char
 		ast_mutex_lock(&p->lock);
 		snprintf(buf, len, "%f", p->txgain);
 		ast_mutex_unlock(&p->lock);
+	} else if (!strcasecmp(data, "dahdi_channel")) {
+		ast_mutex_lock(&p->lock);
+		snprintf(buf, len, "%d", p->channel);
+		ast_mutex_unlock(&p->lock);
+	} else if (!strcasecmp(data, "dahdi_span")) {
+		ast_mutex_lock(&p->lock);
+		snprintf(buf, len, "%d", p->span);
+		ast_mutex_unlock(&p->lock);
+	} else if (!strcasecmp(data, "dahdi_type")) {
+		ast_mutex_lock(&p->lock);
+		switch (p->sig) {
+#if defined(HAVE_OPENR2)
+		case SIG_MFCR2:
+			ast_copy_string(buf, "mfc/r2", len);
+			break;
+#endif	/* defined(HAVE_OPENR2) */
+#if defined(HAVE_PRI)
+		case SIG_PRI_LIB_HANDLE_CASES:
+			ast_copy_string(buf, "pri", len);
+			break;
+#endif	/* defined(HAVE_PRI) */
+		case 0:
+			ast_copy_string(buf, "pseudo", len);
+			break;
+#if defined(HAVE_SS7)
+		case SIG_SS7:
+			ast_copy_string(buf, "ss7", len);
+			break;
+#endif	/* defined(HAVE_SS7) */
+		default:
+			/* The only thing left is analog ports. */
+			ast_copy_string(buf, "analog", len);
+			break;
+		}
+		ast_mutex_unlock(&p->lock);
 #if defined(HAVE_PRI)
 #if defined(HAVE_PRI_REVERSE_CHARGE)
 	} else if (!strcasecmp(data, "reversecharge")) {
@@ -9463,6 +9551,7 @@ static struct ast_channel *dahdi_new(struct dahdi_pvt *i, int state, int startpb
 
 	ast_module_ref(ast_module_info->self);
 
+	dahdi_ami_channel_event(i, tmp);
 	if (startpbx) {
 #ifdef HAVE_OPENR2
 		if (i->mfcr2call) {
@@ -13003,6 +13092,7 @@ static int dahdi_new_pri_nobch_channel(struct sig_pri_span *pri)
 		nobch_channel = CHAN_PSEUDO - 1;
 	}
 	pvt->channel = nobch_channel;
+	pvt->span = pri->span;
 	chan->channel = pvt->channel;
 
 	dahdi_nobch_insert(pri, pvt);

channels/sig_pri.c

@@ -913,6 +913,24 @@ static void sig_pri_open_media(struct sig_pri_chan *p)
 	}
 }
 
+/*!
+ * \internal
+ * \brief Post an AMI B channel association event.
+ * \since 1.8
+ *
+ * \param p Channel private control structure.
+ *
+ * \note Assumes the private and owner are locked.
+ *
+ * \return Nothing
+ */
+static void sig_pri_ami_channel_event(struct sig_pri_chan *p)
+{
+	if (p->calls->ami_channel_event) {
+		p->calls->ami_channel_event(p->chan_pvt, p->owner);
+	}
+}
+
 struct ast_channel *sig_pri_request(struct sig_pri_chan *p, enum sig_pri_law law, const struct ast_channel *requestor, int transfercapability)
 {
 	struct ast_channel *ast;
@@ -1291,6 +1309,10 @@ static int pri_fixup_principle(struct sig_pri_span *pri, int principle, q931_cal
 			sig_pri_open_media(new_chan);
 		}
 
+		if (new_chan->owner) {
+			sig_pri_ami_channel_event(new_chan);
+		}
+
 		sig_pri_unlock_private(old_chan);
 		if (new_chan->owner) {
 			ast_channel_unlock(new_chan->owner);

channels/sig_pri.h

@@ -139,6 +139,16 @@ struct sig_pri_callback {
 
 	void (* const open_media)(void *pvt);
 
+	/*!
+	 * \brief Post an AMI B channel association event.
+	 *
+	 * \param pvt Private structure of the user of this module.
+	 * \param chan Channel associated with the private pointer
+	 *
+	 * \return Nothing
+	 */
+	void (* const ami_channel_event)(void *pvt, struct ast_channel *chan);
+
 	/*! Reference the parent module. */
 	void (*module_ref)(void);
 	/*! Unreference the parent module. */

funcs/func_channel.c

@@ -224,6 +224,22 @@ ASTERISK_FILE_VERSION(__FILE__, "$Revision$")
 				</enumlist>
 				<para><emphasis>chan_dahdi</emphasis> provides the following additional options:</para>
 				<enumlist>
+					<enum name="dahdi_channel">
+						<para>R/O DAHDI channel related to this channel.</para>
+					</enum>
+					<enum name="dahdi_span">
+						<para>R/O DAHDI span related to this channel.</para>
+					</enum>
+					<enum name="dahdi_type">
+						<para>R/O DAHDI channel type, one of:</para>
+						<enumlist>
+							<enum name="analog" />
+							<enum name="mfc/r2" />
+							<enum name="pri" />
+							<enum name="pseudo" />
+							<enum name="ss7" />
+						</enumlist>
+					</enum>
 					<enum name="keypad_digits">
 						<para>R/O PRI Keypad digits that came in with the SETUP message.</para>
 					</enum>