res_telos_1a2: Add workaround optimized for local FXS stations.

For lines served by analog Digium cards, regardless of the technology
behind the FXO port used, the fxodevice option (formerly just 'device')
does not work. This seems to be due to the high resistance of the line,
which prevents audio from passing through from an FXO port to the line.
In reality, the whole premise of using an FXO port the way we are is
completely non-standard and outside the scope of what should work, so
it's not surprising this can be undefined or varying behavior.

However, if the line itself is served by the system, as is likely in
the case of a Digium analog card, we don't need to use an FXO port in
order to bridge in music on hold; we can simply have Asterisk generate
it towards the caller. That is what the new 'fxsdevice' option does;
it queues hold on the channel along with the configured music on hold
class. This also results in better quality, since it eliminates an
additional analog connection and the volume is normal loudness.

UpgradeNote: The 'device' option has been renamed to 'fxodevice',
and this change is not backwards-compatible. The change was made
because, with the addition of the 'fxsdevice' option, having an
option simply named 'device' is somewhat ambiguous.

Additionally, the serial device no longer has a default, which ensures
the module does not load if it is not needed by the user.

Author: InterLinked1

configs/samples/res_telos_1a2.conf.sample

@@ -2,15 +2,16 @@
 ; Configuration file for Asterisk resource module for Telos 1A2 Module Interface
 
 ;[general]
-;device = /dev/ttyS0 ; Serial device to use (at 1200 baud). Default is /dev/ttyS0
+;device = /dev/ttyS0 ; Serial device to use (at 1200 baud). There is no default (however, on most systems, the default serial port is /dev/ttyS0)
 
 ;[line1]
 ;line = 1 ; 1A2 line number
-;device = DAHDI/1 ; FXO device that can be used to access this line
+;fxodevice = DAHDI/1 ; FXO device that can be used to access this line. The line does not need to be served by Asterisk. Music on hold volume is rather low by default with this option.
 ;moh_class = default ; Music on hold class, to play music on hold when this 1A2 line is on hold (via the FXO device). There is no default.
 ;hold_context = 1a2hold ; Dialplan context to execute for 1A2 lines on hold. Extension s will be executed at priority 1. If moh_class is also specified, hold_context takes precedence.
+                        ; hold_context can only be used with 'fxodevice', not 'fxsdevice'.
 
 ;[line2]
 ;line = 2
-;device = DAHDI/2
+;fxsdevice = DAHDI/22 ; FXS device that services this line. Music on hold volume and quality is better using fxsdevice as compared to fxodevice; however, the line must be on this system.
 ;moh_class = default

res/res_telos_1a2.c

@@ -63,11 +63,36 @@
 						<para>Line number of 1A2 channel (e.g. 1, 2, 3, 4, etc.)</para>
 					</description>
 				</configOption>
-				<configOption name="device">
-					<synopsis>Asterisk device</synopsis>
+				<configOption name="fxodevice">
+					<synopsis>Asterisk FXO device</synopsis>
 					<description>
 						<para>Asterisk FXO device corresponding to this 1A2 line.</para>
 						<para>Music on hold will be streamed onto the line using this FXO port.</para>
+						<para>This does not require that the FXS line be served by this Asterisk system,
+						but it may not work with all equipment. If you do not hear music on hold when
+						putting a call on hold from the 1A2 system, the resistance may be too high
+						for audio to pass. If the line is served by Asterisk, you can use
+						<literal>fxsdevice</literal> instead.</para>
+						<para>Music on hold provided using this option will generally have
+						very low volume, due to the high resistance of the 1A2 line on hold.
+						For better quality, use <literal>fxsdevice</literal> if the line is
+						served by Asterisk.</para>
+					</description>
+				</configOption>
+				<configOption name="fxsdevice">
+					<synopsis>Asterisk FXS device</synopsis>
+					<description>
+						<para>Asterisk FXS device corresponding to this 1A2 line. This is specified
+						to indicate that this 1A2 line obtains dial tone from this FXS device.</para>
+						<para>If provided, music on hold will be queued on the active channel
+						of this device, rather than using the FXO device. This may be necessary
+						if simply specifying the FXO <literal>device</literal> does not work;
+						for instance, on Digium analog cards, the resistance may be too high for
+						music on hold audio to pass while a line is on hold by the 1A2 system.
+						This option furnishes music on hold directly on the Asterisk channel,
+						thus resulting in better quality and compatibility. However, this option
+						only works for lines served by the specified Asterisk FXS device.</para>
+						<para>Currently, only DAHDI devices are supported for this setting.</para>
 					</description>
 				</configOption>
 				<configOption name="moh_class">
@@ -159,12 +184,14 @@ enum line_state {
 
 struct telos_line {
 	int lineno;							/*!< Line number on telos system */
-	const char *device;					/*!< Asterisk device */
+	const char *fxodevice;				/*!< Asterisk FXO device */
+	const char *fxsdevice;				/*!< Asterisk FXS device */
 	const char *moh_class;				/*!< Music on hold class */
 	const char *hold_context;			/*!< Hold dialplan context */
 	struct ast_channel *moh_chan;		/*!< Music on hold channel */
 	enum line_state state;				/*!< Current line state */
 	AST_LIST_ENTRY(telos_line) entry;	/*!< Next channel */
+	char fxs_activechan[80];			/*!< Channel on which hold was queued */
 	char data[];
 };
 
@@ -175,7 +202,7 @@ static int thread_running = 0;
 
 #define MAX_POLL_DELAY 2000
 
-static char serial_device[256] = "/dev/ttyS0"; /* Default serial port on a Linux system (especially if there's only one) */
+static char serial_device[256] = "";
 static int serial_fd = -1;
 static int query_success = 0;
 static int unloading = 0;
@@ -276,6 +303,15 @@ static void cleanup_moh_chan(struct ast_channel *chan)
 		ast_verb(5, "Stopping music on hold for 1A2 line %d\n", t->lineno); \
 		cleanup_moh_chan(t->moh_chan); \
 		t->moh_chan = NULL; \
+	} else if (t->fxs_activechan[0]) { \
+		struct ast_channel *ochan = ast_channel_get_by_name(t->fxs_activechan); \
+		if (ochan) { \
+			ast_queue_unhold(ochan); \
+			ast_channel_unref(ochan); \
+		} else { \
+			ast_debug(2, "Channel %s doesn't exist anymore\n", t->fxs_activechan); \
+		} \
+		t->fxs_activechan[0] = '\0'; \
 	}
 
 static int start_moh(struct telos_line *t)
@@ -290,7 +326,40 @@ static int start_moh(struct telos_line *t)
 	}
 
 	/* We need an FXO device (though not necessarily a DAHDI device) for music on hold */
-	if (ast_strlen_zero(t->device)) {
+	if (!ast_strlen_zero(t->fxsdevice)) {
+		if (!strncasecmp(t->fxsdevice, "DAHDI/", 6)) {
+			struct ast_channel *chan;
+			char active_channel[80] = ""; /* AST_MAX_CHANNEL */
+			char func_args[64];
+			int dahdichan = atoi(t->fxsdevice + 6);
+			/* We need to obtain the Asterisk channel that is currently in the "foreground"
+			 * on this DAHDI channel - that would be the owner.
+			 * This is first and foremost because we need an Asterisk channel onto which to queue MOH,
+			 * not just a DAHDI channel, but also so we can stop MOH on the right channel
+			 * if the subchannels switch around while the 1A2 line is on hold. */
+			snprintf(func_args, sizeof(func_args), "DAHDI_CHANNEL(owner,%d)", dahdichan);
+			if (ast_func_read(NULL, func_args, active_channel, sizeof(active_channel))) {
+				ast_log(LOG_WARNING, "Couldn't obtain active Asterisk channel on DAHDI channel %d\n", dahdichan);
+				return -1;
+			}
+			chan = ast_channel_get_by_name(active_channel);
+			if (chan) {
+				/* Indicate music on hold by queuing a HOLD on the active channel for this device */
+				ast_verb(5, "Queued hold on %s using class '%s'\n", active_channel, t->moh_class);
+				ast_queue_hold(chan, t->moh_class);
+				ast_channel_unref(chan);
+				ast_copy_string(t->fxs_activechan, active_channel, sizeof(t->fxs_activechan));
+				return 0;
+			} else {
+				ast_log(LOG_ERROR, "Couldn't find channel %s\n", active_channel);
+				return -1;
+			}
+		} else {
+			ast_log(LOG_ERROR, "Only DAHDI channels are supported for fxsdevice\n");
+			return -1;
+		}
+	}
+	if (ast_strlen_zero(t->fxodevice)) {
 		ast_log(LOG_ERROR, "Music on hold requested for line %d, but no FXO device specified\n", t->lineno);
 		return -1;
 	}
@@ -300,10 +369,10 @@ static int start_moh(struct telos_line *t)
 		STOP_MOH(t); /* If we already have one, for some reason, get rid of it */
 	}
 
-	chandata = ast_strdupa(t->device);
+	chandata = ast_strdupa(t->fxodevice);
 	chantech = strsep(&chandata, "/");
 	if (!chandata) {
-		ast_log(LOG_ERROR, "No data provided after channel type (%s)\n", t->device);
+		ast_log(LOG_ERROR, "No data provided after channel type (%s)\n", t->fxodevice);
 		return -1;
 	}
 
@@ -342,7 +411,7 @@ static int start_moh(struct telos_line *t)
 			desc = "Unknown";
 			break;
 		}
-		ast_log(LOG_WARNING, "Couldn't dial %s (%s)\n", t->device, desc);
+		ast_log(LOG_WARNING, "Couldn't dial %s (%s)\n", t->fxodevice, desc);
 	} else {
 		ast_channel_unlock(t->moh_chan); /* Was returned locked and reference bumped */
 		ast_verb(5, "%s (%s) for 1A2 line %d\n", !ast_strlen_zero(t->hold_context) ? "Launched hold dialplan" : "Started music on hold", S_OR(t->hold_context, t->moh_class), t->lineno);
@@ -707,10 +776,11 @@ static char *handle_show_lines(struct ast_cli_entry *e, int cmd, struct ast_cli_
 
 	ast_cli(a->fd, "Serial device is %s (fd %d)\n", serial_device, serial_fd);
 	ast_cli(a->fd, "Serial status is %s\n", thread_running ? query_success ? "RUNNING" : "STALLED" : "ABORTED");
-	ast_cli(a->fd, "%4s %-8s %17s %20s %s\n", "Line", "State", "Associated Device", "MOH Class", "Hold Context");
+	ast_cli(a->fd, "%4s %-8s %17s %17s %20s %s\n", "Line", "State", "FXO Device", "FXS Device/Chan", "MOH Class", "Hold Context");
 	AST_RWLIST_RDLOCK(&lines);
 	AST_RWLIST_TRAVERSE(&lines, t, entry) {
-		ast_cli(a->fd, "%4d %-8s %17s %20s %s\n", t->lineno, state_str_cli(t->state), S_OR(t->device, ""), S_OR(t->moh_class, ""), S_OR(t->hold_context, ""));
+		const char *fxschannel = S_OR(t->fxs_activechan, S_OR(t->fxsdevice, "")); /* If we have an active FXS channel, use that as it's more specific, otherwise just the device itself */
+		ast_cli(a->fd, "%4d %-8s %17s %17s %20s %s\n", t->lineno, state_str_cli(t->state), S_OR(t->fxodevice, ""), fxschannel, S_OR(t->moh_class, ""), S_OR(t->hold_context, ""));
 	}
 	AST_RWLIST_UNLOCK(&lines);
 
@@ -782,16 +852,22 @@ static int load_config(void)
 		} else { /* it's a line definition */
 			struct telos_line *t;
 			char *data;
-			const char *device = NULL, *moh_class = NULL, *hold_context = NULL;
+			const char *fxodevice = NULL, *fxsdevice = NULL, *moh_class = NULL, *hold_context = NULL;
 			for (var = ast_variable_browse(cfg, cat); var; var = var->next) {
 				if (!strcasecmp(var->name, "line")) {
 					if (ast_str_to_int(var->value, &tmp)) {
 						ast_log(LOG_WARNING, "Invalid line number '%s'\n", var->value);
 						ast_config_destroy(cfg);
 						return -1;
 					}
-				} else if (!strcasecmp(var->name, "device")) {
-					device = var->value;
+				} else if (!strcasecmp(var->name, "fxodevice")) {
+					fxodevice = var->value;
+				} else if (!strcasecmp(var->name, "fxsdevice")) {
+					if (strncasecmp(var->value, "DAHDI/", 6)) {
+						ast_log(LOG_WARNING, "Only DAHDI devices are supported for fxsdevice\n");
+						continue;
+					}
+					fxsdevice = var->value;
 				} else if (!strcasecmp(var->name, "moh_class")) {
 					moh_class = var->value;
 				} else if (!strcasecmp(var->name, "hold_context")) {
@@ -806,39 +882,71 @@ static int load_config(void)
 					return -1;
 				}
 			}
-			t = ast_calloc(1, sizeof(*t) + (device ? strlen(device) + 1 : 0) + (moh_class ? strlen(moh_class) + 1 : 0) + (hold_context ? strlen(hold_context) + 1 : 0));
+			t = ast_calloc(1, sizeof(*t) + (fxodevice ? strlen(fxodevice) + 1 : 0) + (fxsdevice ? strlen(fxsdevice) + 1 : 0)
+				+ (moh_class ? strlen(moh_class) + 1 : 0) + (hold_context ? strlen(hold_context) + 1 : 0));
 			if (!t) {
 				ast_config_destroy(cfg);
 				return -1;
 			}
 			t->lineno = tmp;
 			data = t->data;
-			if (!ast_strlen_zero(device)) {
-				strcpy(data, device); /* Safe */
-				t->device = data;
-				data += strlen(device) + 1;
+			if (!ast_strlen_zero(fxodevice)) {
+				strcpy(data, fxodevice); /* Safe */
+				t->fxodevice = data;
+				data += strlen(fxodevice) + 1;
+			}
+			if (!ast_strlen_zero(fxsdevice)) {
+				strcpy(data, fxsdevice); /* Safe */
+				t->fxsdevice = data;
+				data += strlen(fxsdevice) + 1;
 			}
 			if (!ast_strlen_zero(moh_class)) {
-				strcpy(data, moh_class);
+				strcpy(data, moh_class); /* Safe */
 				t->moh_class = data;
 				data += strlen(moh_class) + 1;
 			}
 			if (!ast_strlen_zero(hold_context)) {
-				strcpy(data, hold_context);
+				strcpy(data, hold_context); /* Safe */
 				t->hold_context = data;
 			}
+			if (ast_strlen_zero(fxodevice) && !ast_strlen_zero(hold_context)) {
+				ast_log(LOG_ERROR, "The 'hold_context' setting requires 'fxodevice' to be set\n");
+			}
+			if (!ast_strlen_zero(fxsdevice) && ast_strlen_zero(moh_class)) {
+				ast_log(LOG_WARNING, "The 'fxsdevice' setting requires 'moh_class' to be set to customize music on hold\n");
+			}
 			AST_RWLIST_INSERT_TAIL(&lines, t, entry);
 		}
 	}
 
 	ast_config_destroy(cfg);
+
+	/* This option intentionally has no default,
+	 * so that if the stock config file has not been modified,
+	 * we assume this module isn't needed and decline to load,
+	 * since we can't do anything useful without the associated equipment. */
+	if (ast_strlen_zero(serial_device)) {
+		ast_log(LOG_NOTICE, "No serial device specified, declining to load\n");
+		return -1;
+	}
+
 	return 0;
 }
 
-static int unload_module(void)
+static void free_lines(void)
 {
 	struct telos_line *t;
 
+	AST_RWLIST_WRLOCK(&lines);
+	while ((t = AST_RWLIST_REMOVE_HEAD(&lines, entry))) {
+		STOP_MOH(t);
+		ast_free(t);
+	}
+	AST_RWLIST_UNLOCK(&lines);
+}
+
+static int unload_module(void)
+{
 	unloading = 1;
 	ast_cli_unregister_multiple(telos_cli, ARRAY_LEN(telos_cli));
 	ast_custom_function_unregister(&acf_telos);
@@ -857,13 +965,7 @@ static int unload_module(void)
 		serial_fd = -1;
 	}
 
-	AST_RWLIST_WRLOCK(&lines);
-	while ((t = AST_RWLIST_REMOVE_HEAD(&lines, entry))) {
-		STOP_MOH(t);
-		ast_free(t);
-	}
-	AST_RWLIST_UNLOCK(&lines);
-
+	free_lines();
 	return 0;
 }
 
@@ -873,7 +975,7 @@ static int load_module(void)
 	struct termios attr;
 
 	if (load_config()) {
-		unload_module();
+		free_lines();
 		return AST_MODULE_LOAD_DECLINE;
 	}