Add option to cross-connect calls; Calls between mobiles are now possible

Use -x to enable call cross-connect. No MNCC socket, no call device must
be specified!

Be sure to have at least one control channel and two voice channels.
Alternatively you can use one combined control/voice channel and one
voice channel.

4 files changed, 291 insertions, 6 deletions

diff --git a/src/common/Makefile.am b/src/common/Makefile.am
index 3b3375e..6005e56 100644
--- a/src/common/Makefile.am
+++ b/src/common/Makefile.am
@@ -28,6 +28,7 @@ libmobile_a_SOURCES = \
 	call.c \
 	testton.c \
 	mncc_console.c \
+	mncc_cross.c \
 	mncc_sock.c \
 	hagelbarger.c \
 	display_status.c \
diff --git a/src/common/main_mobile.c b/src/common/main_mobile.c
index bab9579..0be77d2 100644
--- a/src/common/main_mobile.c
+++ b/src/common/main_mobile.c
@@ -37,6 +37,7 @@
 #include "call.h"
 #include "mncc_console.h"
 #include "mncc_sock.h"
+#include "mncc_cross.h"
 #ifdef HAVE_SDR
 #include "sdr.h"
 #include "sdr_config.h"
@@ -61,6 +62,7 @@ int do_de_emphasis = 0;
 double rx_gain = 1.0;
 static int echo_test = 0;
 static int use_mncc_sock = 0;
+static int use_mncc_cross = 0;
 const char *mncc_name = "";
 static int send_patterns = 1;
 static int release_on_disconnect = 1;
@@ -124,6 +126,10 @@ void main_mobile_print_help(const char *arg0, const char *ext_usage)
 	printf("        Sound card and device number for headset (default = '%s')\n", call_audiodev);
 	printf("    --call-samplerate <rate>\n");
 	printf("        Sample rate of sound device for headset (default = '%d')\n", call_samplerate);
+	printf(" -x --mncc-cross\n");
+	printf("        Enable built-in call forwarding between mobiles. Be sure to have\n");
+	printf("        at least one control channel and two voice channels. Alternatively\n");
+	printf("        use one combined control+voice channel and one voice channels.\n");
 	printf(" -m --mncc-sock\n");
 	printf("        Disable built-in call contol and offer socket (to LCR)\n");
 	printf(" --mncc-name <name>\n");
@@ -184,6 +190,7 @@ static struct option main_mobile_long_options[] = {
 	{"de-emphasis", 0, 0, 'd'},
 	{"rx-gain", 1, 0, 'g'},
 	{"echo-test", 0, 0, 'e'},
+	{"mncc-cross", 0, 0, 'x'},
 	{"mncc-sock", 0, 0, 'm'},
 	{"mncc-name", 1, 0, OPT_MNCC_NAME},
 	{"call-device", 1, 0, 'c'},
@@ -198,7 +205,7 @@ static struct option main_mobile_long_options[] = {
 	{0, 0, 0, 0}
 };
 
-static const char *main_mobile_optstring = "hv:k:a:s:i:b:pdg:mec:t:l:r:";
+static const char *main_mobile_optstring = "hv:k:a:s:i:b:pdg:exmc:t:l:r:";
 
 struct option *long_options;
 char *optstring;
@@ -320,6 +327,10 @@ void main_mobile_opt_switch(int c, char *arg0, int *skip_args)
 		echo_test = 1;
 		*skip_args += 1;
 		break;
+	case 'x':
+		use_mncc_cross = 1;
+		*skip_args += 1;
+		break;
 	case 'm':
 		use_mncc_sock = 1;
 		*skip_args += 1;
@@ -427,16 +438,32 @@ void main_mobile(int *quit, int latency, int interval, void (*myhandler)(void),
 	latspl = samplerate * latency / 1000;
 
 	/* check MNCC support */
+	if (use_mncc_cross && num_kanal == 1) {
+		fprintf(stderr, "You selected built-in call forwarding, but only channel is used. Does this makes sense?\n");
+		return;
+	}
+	if (use_mncc_sock && use_mncc_cross) {
+		fprintf(stderr, "You selected MNCC socket interface and built-in call forwarding, but only one can be selected.\n");
+		return;
+	}
+	if (echo_test && call_audiodev[0]) {
+		fprintf(stderr, "You selected call device (headset) and echo test, but only one can be selected.\n");
+		return;
+	}
 	if (use_mncc_sock && call_audiodev[0]) {
-		fprintf(stderr, "You selected MNCC interface, but it cannot be used with call device (headset).\n");
+		fprintf(stderr, "You selected MNCC socket interface, but it cannot be used with call device (headset).\n");
+		return;
+	}
+	if (use_mncc_cross && call_audiodev[0]) {
+		fprintf(stderr, "You selected built-in call forwarding, but it cannot be used with call device (headset).\n");
 		return;
 	}
 	if (use_mncc_sock && echo_test) {
-		fprintf(stderr, "You selected MNCC interface, but it cannot be used with echo test.\n");
+		fprintf(stderr, "You selected MNCC socket interface, but it cannot be used with echo test.\n");
 		return;
 	}
-	if (echo_test && call_audiodev[0]) {
-		fprintf(stderr, "You selected call device (headset), but it cannot be used with echo test.\n");
+	if (use_mncc_cross && echo_test) {
+		fprintf(stderr, "You selected built-in call forwarding, but it cannot be used with echo test.\n");
 		return;
 	}
 
@@ -453,6 +480,12 @@ void main_mobile(int *quit, int latency, int interval, void (*myhandler)(void),
 			fprintf(stderr, "Failed to setup MNCC socket. Quitting!\n");
 			return;
 		}
+	} else if (use_mncc_cross) {
+		rc = mncc_cross_init();
+		if (rc < 0) {
+			fprintf(stderr, "Failed to setup MNCC crossing process. Quitting!\n");
+			return;
+		}
 	} else {
 		console_init(station_id, call_audiodev, call_samplerate, latency, station_id_digits, loopback, echo_test);
 	}
@@ -598,6 +631,8 @@ next_char:
 		/* process call control */
 		if (use_mncc_sock)
 			mncc_sock_handle();
+		else if (use_mncc_cross)
+			mncc_cross_handle();
 		else
 			process_console(c);
 
@@ -639,11 +674,15 @@ next_char:
 	}
 
 	/* cleanup call control */
-	if (!use_mncc_sock)
+	if (!use_mncc_sock && !use_mncc_cross)
 		console_cleanup();
 
 	/* close mncc socket */
 	if (use_mncc_sock)
 		mncc_sock_exit();
+
+	/* close mncc forwarding */
+	if (use_mncc_cross)
+		mncc_cross_exit();
 }
 
diff --git a/src/common/mncc_cross.c b/src/common/mncc_cross.c
new file mode 100644
index 0000000..5ca51ac
--- /dev/null
+++ b/src/common/mncc_cross.c
@@ -0,0 +1,240 @@
+/* Mobie Network Call Control (MNCC) cross connecting mobiles
+ *
+ * (C) 2017 by Andreas Eversberg <jolly@eversberg.eu>
+ * All Rights Reserved
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <stdio.h>
+#include <stdint.h>
+#include <errno.h>
+#include <string.h>
+#include <stdlib.h>
+#include "sample.h"
+#include "debug.h"
+#include "call.h"
+#include "cause.h"
+#include "mncc.h"
+#include "mncc_cross.h"
+
+int new_callref = 0; /* toward mobile */
+
+typedef struct cross {
+	struct cross	*next;
+	int		callref1;
+	int		callref2;
+} cross_t;
+
+static cross_t *cross_head = NULL;
+
+static int create_cross(int callref)
+{
+	cross_t *cross;
+
+	cross = calloc(1, sizeof(*cross));
+	if (!cross) {
+		PDEBUG(DMNCC, DEBUG_ERROR, "No memory!\n");
+		abort();
+	}
+
+	cross->callref1 = callref;
+	cross->callref2 = ++new_callref;
+
+	/* attach to list */
+	cross->next = cross_head;
+	cross_head = cross;
+
+	PDEBUG(DMNCC, DEBUG_INFO, "Cross connection created\n");
+
+	return cross->callref2;
+}
+
+static void destroy_cross(cross_t *cross)
+{
+	cross_t **crossp;
+
+	/* detach from list */
+	crossp = &cross_head;
+	while (*crossp && *crossp != cross)
+		crossp = &((*crossp)->next);
+	if (!(*crossp)) {
+		PDEBUG(DMNCC, DEBUG_ERROR, "Transaction not in list, please fix!!\n");
+		abort();
+	}
+	*crossp = cross->next;
+
+	free(cross);
+
+	PDEBUG(DMNCC, DEBUG_INFO, "Cross connection destroyed\n");
+}
+
+typedef struct queue {
+	struct queue	*next;
+	int		length;
+	uint8_t		buf[0];
+} queue_t;
+
+static queue_t *queue_head;
+
+static void cross_mncc_up(uint8_t *buf, int length);
+
+static int cross_mncc_up_queue(uint8_t *buf, int length)
+{
+	struct gsm_mncc *mncc = (struct gsm_mncc *)buf;
+	queue_t *queue, **queuep;
+
+	/* directly forward voice */
+	if (mncc->msg_type == ANALOG_8000HZ) {
+		cross_mncc_up(buf, length);
+		return 0;
+	}
+
+	/* queue all other messages */
+	queue = calloc(1, sizeof(*queue) + length);
+	if (!queue) {
+		PDEBUG(DMNCC, DEBUG_ERROR, "No memory!\n");
+		return -CAUSE_TEMPFAIL;
+	}
+	queue->length = length;
+	memcpy(queue->buf, buf, length);
+	
+	/* add tail */
+	queuep = &queue_head;
+	while (*queuep)
+		queuep = &((*queuep)->next);
+	*queuep = queue;
+
+	return 0;
+}
+
+static void cross_mncc_up(uint8_t *buf, int length)
+{
+	struct gsm_mncc *mncc = (struct gsm_mncc *)buf;
+	cross_t *cross = NULL;
+	int callref = mncc->callref, remote = 0;
+
+	/* find cross instance */
+	for (cross = cross_head; cross; cross = cross->next) {
+		if (cross->callref1 == callref) {
+			remote = cross->callref2;
+			break;
+		}
+		if (cross->callref2 == callref) {
+			remote = cross->callref1;
+			break;
+		}
+	}
+
+	if (mncc->msg_type == MNCC_REL_CNF) {
+		if (cross)
+			destroy_cross(cross);
+		return;
+	}
+
+	if (!remote && mncc->msg_type != MNCC_SETUP_IND) {
+		PDEBUG(DMNCC, DEBUG_ERROR, "invalid call ref.\n");
+		/* send down reused MNCC */
+		mncc->msg_type = MNCC_REL_REQ;
+		mncc->fields |= MNCC_F_CAUSE;
+		mncc->cause.location = LOCATION_USER;
+		mncc->cause.value = CAUSE_INVALCALLREF;
+		mncc_down(buf, length);
+		return;
+	}
+
+	switch (mncc->msg_type) {
+	case ANALOG_8000HZ:
+		/* send down reused MNCC */
+		mncc->callref = remote;
+		mncc_down(buf, length);
+		break;
+	case MNCC_SETUP_IND:
+		remote = create_cross(callref);
+		/* send down reused MNCC */
+		mncc->msg_type = MNCC_SETUP_REQ;
+		mncc->callref = remote;
+		mncc_down(buf, length);
+		break;
+	case MNCC_CALL_CONF_IND:
+		/* send down reused MNCC */
+		mncc->msg_type = MNCC_CALL_PROC_REQ;
+		mncc->callref = remote;
+		mncc_down(buf, length);
+		break;
+	case MNCC_ALERT_IND:
+		/* send down reused MNCC */
+		mncc->msg_type = MNCC_ALERT_REQ;
+		mncc->callref = remote;
+		mncc_down(buf, length);
+		break;
+	case MNCC_SETUP_CNF:
+		/* send down reused MNCC */
+		mncc->msg_type = MNCC_SETUP_RSP;
+		mncc->callref = remote;
+		mncc_down(buf, length);
+		break;
+	case MNCC_SETUP_COMPL_IND:
+		/* send down reused MNCC */
+		mncc->msg_type = MNCC_SETUP_COMPL_REQ;
+		mncc->callref = remote;
+		mncc_down(buf, length);
+		break;
+	case MNCC_DISC_IND:
+		/* send down reused MNCC */
+		mncc->msg_type = MNCC_DISC_REQ;
+		mncc->callref = remote;
+		mncc_down(buf, length);
+		break;
+	case MNCC_REL_IND:
+		/* send down reused MNCC */
+		mncc->msg_type = MNCC_REL_REQ;
+		mncc->callref = remote;
+		mncc_down(buf, length);
+		destroy_cross(cross);
+		break;
+	}
+}
+
+void mncc_cross_handle(void)
+{
+	queue_t *queue;
+
+	while (queue_head) {
+		/* remove from head */
+		queue = queue_head;
+		queue_head = queue->next;
+
+		cross_mncc_up(queue->buf, queue->length);
+		free(queue);
+	}
+}
+
+int mncc_cross_init(void)
+{
+	mncc_up = cross_mncc_up_queue;
+
+	PDEBUG(DMNCC, DEBUG_DEBUG, "MNCC crossconnect initialized, waiting for connection.\n");
+
+	return 0;
+}
+
+void mncc_cross_exit(void)
+{
+	while (cross_head)
+		destroy_cross(cross_head);
+
+	PDEBUG(DMNCC, DEBUG_DEBUG, "MNCC crossconnect removed.\n");
+}
+
diff --git a/src/common/mncc_cross.h b/src/common/mncc_cross.h
new file mode 100644
index 0000000..10f2b0d
--- /dev/null
+++ b/src/common/mncc_cross.h
@@ -0,0 +1,5 @@
+
+void mncc_cross_handle(void);
+int mncc_cross_init(void);
+void mncc_cross_exit(void);
+