[Asterisk-code-review] chan_dahdi: Add POLARITY function. (asterisk[19])

[George Joseph]

George Joseph has submitted this change. ( https://gerrit.asterisk.org/c/asterisk/+/18801 )

Change subject: chan_dahdi: Add POLARITY function.
......................................................................

chan_dahdi: Add POLARITY function.

Adds a POLARITY function which can be used to
retrieve the current polarity of an FXS channel
as well as set the polarity of an FXS channel
to idle or reverse at any point during a call.

ASTERISK-30000 #close

Change-Id: If6f50998f723e4484bf68e2473f5cedfeaf9b8f1
---
M channels/chan_dahdi.c
A doc/CHANGES-staging/chan_dahdi_polarity.txt
2 files changed, 118 insertions(+), 0 deletions(-)

Approvals:
  Kevin Harwell: Looks good to me, but someone else must approve
  George Joseph: Looks good to me, approved; Approved for Submit



diff --git a/channels/chan_dahdi.c b/channels/chan_dahdi.c
index e6f8c62..5adb797 100644
--- a/channels/chan_dahdi.c
+++ b/channels/chan_dahdi.c
@@ -177,6 +177,35 @@
 			<para>This application will Accept the R2 call either with charge or no charge.</para>
 		</description>
 	</application>
+	<function name="POLARITY" language="en_US">
+		<synopsis>
+			Set or get the polarity of a DAHDI channel.
+		</synopsis>
+		<syntax />
+		<description>
+			<para>The POLARITY function can be used to set the polarity of a DAHDI channel.</para>
+			<para>Applies only to FXS channels (using FXO signalling) with supporting hardware.</para>
+			<para>The polarity can be set to the following numeric or named values:</para>
+			<enumlist>
+				<enum name="0" />
+				<enum name="idle" />
+				<enum name="1" />
+				<enum name="reverse" />
+			</enumlist>
+			<para>However, when read, the function will always return 0 or 1.</para>
+			<example title="Set idle polarity">
+			same => n,Set(POLARITY()=0)
+			</example>
+			<example title="Set reverse polarity">
+			same => n,NoOp(Current Polarity: ${POLARITY()})
+			same => n,Set(POLARITY()=reverse)
+			same => n,NoOp(New Polarity: ${POLARITY()})
+			</example>
+			<example title="Reverse the polarity from whatever it is currently">
+			same => n,Set(POLARITY()=${IF($[ "${POLARITY()}" = "1" ]?0:1)})
+			</example>
+		</description>
+	</function>
 	<info name="CHANNEL" language="en_US" tech="DAHDI">
 		<enumlist>
 			<enum name="dahdi_channel">
@@ -2704,6 +2733,86 @@
 	}
 }
 
+/*! \brief Return DAHDI pivot if channel is FXO signalled */
+static struct dahdi_pvt *fxo_pvt(struct ast_channel *chan)
+{
+	int res;
+	struct dahdi_params dahdip;
+	struct dahdi_pvt *pvt = NULL;
+
+	if (strcasecmp(ast_channel_tech(chan)->type, "DAHDI")) {
+		ast_log(LOG_WARNING, "%s is not a DAHDI channel\n", ast_channel_name(chan));
+		return NULL;
+	}
+
+	memset(&dahdip, 0, sizeof(dahdip));
+	res = ioctl(ast_channel_fd(chan, 0), DAHDI_GET_PARAMS, &dahdip);
+
+	if (res) {
+		ast_log(LOG_WARNING, "Unable to get parameters of %s: %s\n", ast_channel_name(chan), strerror(errno));
+		return NULL;
+	}
+	if (!(dahdip.sigtype & __DAHDI_SIG_FXO)) {
+		ast_log(LOG_WARNING, "%s is not FXO signalled\n", ast_channel_name(chan));
+		return NULL;
+	}
+
+	pvt = ast_channel_tech_pvt(chan);
+	if (!dahdi_analog_lib_handles(pvt->sig, 0, 0)) {
+		ast_log(LOG_WARNING, "Channel signalling is not analog");
+		return NULL;
+	}
+
+	return pvt;
+}
+
+static int polarity_read(struct ast_channel *chan, const char *cmd, char *data, char *buffer, size_t buflen)
+{
+	struct dahdi_pvt *pvt;
+
+	pvt = fxo_pvt(chan);
+	if (!pvt) {
+		return -1;
+	}
+
+	snprintf(buffer, buflen, "%d", pvt->polarity);
+
+	return 0;
+}
+
+static int polarity_write(struct ast_channel *chan, const char *cmd, char *data, const char *value)
+{
+	struct dahdi_pvt *pvt;
+	int polarity;
+
+	pvt = fxo_pvt(chan);
+	if (!pvt) {
+		return -1;
+	}
+
+	if (!strcasecmp(value, "idle")) {
+		polarity = POLARITY_IDLE;
+	} else if (!strcasecmp(value, "reverse")) {
+		polarity = POLARITY_REV;
+	} else {
+		polarity = atoi(value);
+	}
+
+	if (polarity != POLARITY_IDLE && polarity != POLARITY_REV) {
+		ast_log(LOG_WARNING, "Invalid polarity: '%s'\n", value);
+		return -1;
+	}
+
+	my_set_polarity(pvt, polarity);
+	return 0;
+}
+
+static struct ast_custom_function polarity_function = {
+	.name = "POLARITY",
+	.write = polarity_write,
+	.read = polarity_read,
+};
+
 static int my_start(void *pvt)
 {
 	struct dahdi_pvt *p = pvt;
@@ -17615,6 +17724,8 @@
 	ast_unregister_application(dahdi_accept_r2_call_app);
 #endif
 
+	ast_custom_function_unregister(&polarity_function);
+
 	ast_cli_unregister_multiple(dahdi_cli, ARRAY_LEN(dahdi_cli));
 	ast_manager_unregister("DAHDIDialOffhook");
 	ast_manager_unregister("DAHDIHangup");
@@ -19803,6 +19914,8 @@
 	ast_register_application_xml(dahdi_accept_r2_call_app, dahdi_accept_r2_call_exec);
 #endif
 
+	ast_custom_function_register(&polarity_function);
+
 	ast_cli_register_multiple(dahdi_cli, ARRAY_LEN(dahdi_cli));
 	memset(round_robin, 0, sizeof(round_robin));
 	ast_manager_register_xml("DAHDITransfer", 0, action_transfer);
diff --git a/doc/CHANGES-staging/chan_dahdi_polarity.txt b/doc/CHANGES-staging/chan_dahdi_polarity.txt
new file mode 100644
index 0000000..365ab20
--- /dev/null
+++ b/doc/CHANGES-staging/chan_dahdi_polarity.txt
@@ -0,0 +1,5 @@
+Subject: chan_dahdi
+
+A POLARITY function is now available that allows
+getting or setting the polarity on a channel
+from the dialplan.

-- 
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Gerrit-Project: asterisk
Gerrit-Branch: 19
Gerrit-Change-Id: If6f50998f723e4484bf68e2473f5cedfeaf9b8f1
Gerrit-Change-Number: 18801
Gerrit-PatchSet: 2
Gerrit-Owner: N A <mail at interlinked.x10host.com>
Gerrit-Reviewer: Friendly Automation
Gerrit-Reviewer: George Joseph <gjoseph at digium.com>
Gerrit-Reviewer: Kevin Harwell <kharwell at digium.com>
Gerrit-MessageType: merged
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