layer23: Support configuring GSMTAP through VTY in l23 apps.

This allow all l23 apps supporting L23_OPT_VTY and L23_OPT_TAP to
dynamically configure gsmtap through a "gsmtap" VTY node:

gsmtap
 remote-host 127.0.0.1
 lchan sacch
 lchan lsacch
 lchan sacch/4
 lchan sacch/8
 lchan sacch/f
 lchan sacch/h
 lchan unknown
 lchan bcch
 lchan ccch
 lchan rach
 lchan agch
 lchan pch
 lchan sdcch
 lchan sdcch/4
 lchan sdcch/8
 lchan facch/f
 lchan facch/h
 lchan pacch
 lchan cbch
 lchan pdch
 lchan pttch
 lchan cbch
 lchan tch/f
 lchan tch/h
 category gprs dl-unknown
 category gprs dl-dummy
 category gprs dl-ctrl
 category gprs dl-data-gprs
 category gprs dl-data-egprs
 category gprs ul-unknown
 category gprs ul-dummy
 category gprs ul-ctrl
 category gprs ul-data-gprs
 category gprs ul-data-egprs

VTY cmd "lchan" enables/disables tapping on general channel types,
while "category" allows fine-grained selection of messages being
tapped within the enabled lchan which would tap those messages.

Change-Id: I2582a1633d37d350a7f4c2bb5e03793bdf46e839

7 files changed, 335 insertions, 20 deletions

diff --git a/src/host/layer23/include/osmocom/bb/common/l23_app.h b/src/host/layer23/include/osmocom/bb/common/l23_app.h
index d442e7e2..290a09b4 100644
--- a/src/host/layer23/include/osmocom/bb/common/l23_app.h
+++ b/src/host/layer23/include/osmocom/bb/common/l23_app.h
@@ -2,6 +2,7 @@
 #define _L23_APP_H
 
 #include <osmocom/core/tun.h>
+#include <osmocom/core/gsmtap.h>
 
 struct option;
 struct vty_app_info;
@@ -15,6 +16,33 @@ enum {
 	L23_OPT_DBG	= 1 << 4,
 };
 
+/* see (struct l23_global_config)->gsmtap.categ_gprs_mask */
+enum l23_gsmtap_gprs_category {
+	L23_GSMTAP_GPRS_C_DL_UNKNOWN	= 0,	/* unknown or undecodable downlink blocks */
+	L23_GSMTAP_GPRS_C_DL_DUMMY	= 1,	/* downlink dummy blocks */
+	L23_GSMTAP_GPRS_C_DL_CTRL	= 2,	/* downlink control blocks */
+	L23_GSMTAP_GPRS_C_DL_DATA_GPRS	= 3,	/* downlink GPRS data blocks */
+	L23_GSMTAP_GPRS_C_DL_DATA_EGPRS	= 4,	/* downlink EGPRS data blocks */
+
+	L23_GSMTAP_GPRS_C_UL_UNKNOWN	= 5,	/* unknown or undecodable uplink blocks */
+	L23_GSMTAP_GPRS_C_UL_DUMMY	= 6,	/* uplink dummy blocks */
+	L23_GSMTAP_GPRS_C_UL_CTRL	= 7,	/* uplink control blocks */
+	L23_GSMTAP_GPRS_C_UL_DATA_GPRS	= 8,	/* uplink GPRS data blocks */
+	L23_GSMTAP_GPRS_C_UL_DATA_EGPRS	= 9,	/* uplink EGPRS data blocks */
+};
+
+struct l23_global_config {
+	struct {
+		char *remote_host;
+		uint32_t lchan_mask; /* see l23_gsmtap_gprs_category */
+		uint32_t lchan_acch_mask; /* see l23_gsmtap_gprs_category */
+		bool lchan_acch;
+		uint32_t categ_gprs_mask;
+		struct gsmtap_inst *inst;
+	} gsmtap;
+};
+extern struct l23_global_config l23_cfg;
+
 extern void *l23_ctx;
 
 /* initialization, called once when starting the app, before reading VTY config */
diff --git a/src/host/layer23/include/osmocom/bb/common/vty.h b/src/host/layer23/include/osmocom/bb/common/vty.h
index 259725eb..4ff96fe5 100644
--- a/src/host/layer23/include/osmocom/bb/common/vty.h
+++ b/src/host/layer23/include/osmocom/bb/common/vty.h
@@ -10,6 +10,7 @@ struct osmocom_ms;
 
 enum l23_vty_node {
 	MS_NODE = _LAST_OSMOVTY_NODE + 1,
+	GSMTAP_NODE,
 	_LAST_L23VTY_NODE,
 };
 
diff --git a/src/host/layer23/src/common/l1ctl.c b/src/host/layer23/src/common/l1ctl.c
index 5ba1a1fb..34051fdb 100644
--- a/src/host/layer23/src/common/l1ctl.c
+++ b/src/host/layer23/src/common/l1ctl.c
@@ -39,14 +39,13 @@
 #include <osmocom/gsm/rsl.h>
 
 #include <osmocom/bb/common/l1ctl.h>
+#include <osmocom/bb/common/l23_app.h>
 #include <osmocom/bb/common/osmocom_data.h>
 #include <osmocom/bb/common/ms.h>
 #include <osmocom/bb/common/l1l2_interface.h>
 #include <osmocom/gsm/lapdm.h>
 #include <osmocom/bb/common/logging.h>
 
-extern struct gsmtap_inst *gsmtap_inst;
-
 #define CB_FCCH		-1
 #define CB_SCH		-2
 #define CB_BCCH		-3
@@ -317,7 +316,7 @@ static int rx_ph_data_ind(struct osmocom_ms *ms, struct msgb *msg)
 	 * to clog up your logs */
 	if (!is_fill_frame(gsmtap_chan_type, ccch->data)) {
 		/* send CCCH data via GSMTAP */
-		gsmtap_send(gsmtap_inst, ntohs(dl->band_arfcn), chan_ts,
+		gsmtap_send(l23_cfg.gsmtap.inst, ntohs(dl->band_arfcn), chan_ts,
 			    gsmtap_chan_type, chan_ss, tm.fn, dl->rx_level-110,
 			    dl->snr, ccch->data, sizeof(ccch->data));
 	}
@@ -394,7 +393,7 @@ int l1ctl_tx_data_req(struct osmocom_ms *ms, struct msgb *msg,
 	/* send copy via GSMTAP */
 	if (rsl_dec_chan_nr(chan_nr, &chan_type, &chan_ss, &chan_ts) == 0) {
 		uint8_t gsmtap_chan_type = chantype_rsl2gsmtap2(chan_type, link_id, false);
-		gsmtap_send(gsmtap_inst, ms->rrlayer.cd_now.arfcn | GSMTAP_ARFCN_F_UPLINK,
+		gsmtap_send(l23_cfg.gsmtap.inst, ms->rrlayer.cd_now.arfcn | GSMTAP_ARFCN_F_UPLINK,
 			    chan_ts, gsmtap_chan_type, chan_ss, 0, 127, 0,
 			    msg->l2h, msgb_l2len(msg));
 	} else {
diff --git a/src/host/layer23/src/common/main.c b/src/host/layer23/src/common/main.c
index c456488b..e82457fb 100644
--- a/src/host/layer23/src/common/main.c
+++ b/src/host/layer23/src/common/main.c
@@ -33,7 +33,6 @@
 #include <osmocom/core/linuxlist.h>
 #include <osmocom/core/application.h>
 #include <osmocom/core/gsmtap_util.h>
-#include <osmocom/core/gsmtap.h>
 #include <osmocom/core/utils.h>
 #include <osmocom/vty/vty.h>
 #include <osmocom/vty/logging.h>
@@ -53,6 +52,7 @@
 #include "config.h"
 
 void *l23_ctx = NULL;
+struct l23_global_config l23_cfg;
 
 static char *sap_socket_path = "/tmp/osmocom_sap";
 struct llist_head ms_list;
@@ -63,7 +63,6 @@ int (*l23_app_start)(void) = NULL;
 int (*l23_app_work)(void) = NULL;
 int (*l23_app_exit)(void) = NULL;
 int quit = 0;
-struct gsmtap_inst *gsmtap_inst;
 
 static void print_usage(const char *app)
 {
@@ -285,13 +284,29 @@ int main(int argc, char **argv)
 			exit(1);
 	}
 
-	if (gsmtap_ip) {
-		gsmtap_inst = gsmtap_source_init(gsmtap_ip, GSMTAP_UDP_PORT, 1);
-		if (!gsmtap_inst) {
-			fprintf(stderr, "Failed during gsmtap_init()\n");
-			exit(1);
+	if (app_supp_opt & L23_OPT_TAP) {
+		if (gsmtap_ip) {
+			if (l23_cfg.gsmtap.remote_host != NULL) {
+				LOGP(DLGLOBAL, LOGL_NOTICE,
+				     "Command line argument '-i %s' overrides node "
+				     "'gsmtap' cmd 'remote-host %s' from the config file\n",
+				     gsmtap_ip, l23_cfg.gsmtap.remote_host);
+				talloc_free(l23_cfg.gsmtap.remote_host);
+			}
+			l23_cfg.gsmtap.remote_host = talloc_strdup(l23_ctx, gsmtap_ip);
+		}
+
+		if (l23_cfg.gsmtap.remote_host) {
+			LOGP(DLGLOBAL, LOGL_NOTICE,
+			     "Setting up GSMTAP Um forwarding to '%s:%u'\n",
+			     l23_cfg.gsmtap.remote_host, GSMTAP_UDP_PORT);
+			l23_cfg.gsmtap.inst = gsmtap_source_init(l23_cfg.gsmtap.remote_host, GSMTAP_UDP_PORT, 1);
+			if (!l23_cfg.gsmtap.inst) {
+				fprintf(stderr, "Failed during gsmtap_init()\n");
+				exit(1);
+			}
+			gsmtap_source_add_sink(l23_cfg.gsmtap.inst);
 		}
-		gsmtap_source_add_sink(gsmtap_inst);
 	}
 
 	if (l23_app_start) {
diff --git a/src/host/layer23/src/common/sim.c b/src/host/layer23/src/common/sim.c
index bd50f627..4a4144ab 100644
--- a/src/host/layer23/src/common/sim.c
+++ b/src/host/layer23/src/common/sim.c
@@ -24,12 +24,11 @@
 #include <osmocom/core/gsmtap.h>
 
 #include <osmocom/bb/common/logging.h>
+#include <osmocom/bb/common/l23_app.h>
 #include <osmocom/bb/common/osmocom_data.h>
 #include <osmocom/bb/common/ms.h>
 #include <osmocom/bb/common/l1ctl.h>
 
-extern struct gsmtap_inst *gsmtap_inst;
-
 static int sim_process_job(struct osmocom_ms *ms);
 
 /*
@@ -874,7 +873,7 @@ int sim_apdu_resp(struct osmocom_ms *ms, struct msgb *msg)
 		if ((ms->sim.apdu_len + length) <= sizeof(ms->sim.apdu_data)) {
 			memcpy(ms->sim.apdu_data + ms->sim.apdu_len, data, length);
 			ms->sim.apdu_len += length;
-			gsmtap_send_ex(gsmtap_inst, GSMTAP_TYPE_SIM,
+			gsmtap_send_ex(l23_cfg.gsmtap.inst, GSMTAP_TYPE_SIM,
 				0, 0, 0, 0, 0, 0, 0, ms->sim.apdu_data, ms->sim.apdu_len);
 		}
 	}
diff --git a/src/host/layer23/src/common/vty.c b/src/host/layer23/src/common/vty.c
index 2e7dea88..48d07b35 100644
--- a/src/host/layer23/src/common/vty.c
+++ b/src/host/layer23/src/common/vty.c
@@ -26,9 +26,12 @@
 #include <osmocom/gsm/gsm48.h>
 #include <osmocom/core/talloc.h>
 #include <osmocom/core/signal.h>
+#include <osmocom/core/gsmtap.h>
+#include <osmocom/core/gsmtap_util.h>
 #include <osmocom/crypt/auth.h>
 
 #include <osmocom/bb/common/vty.h>
+#include <osmocom/bb/common/l23_app.h>
 #include <osmocom/bb/common/osmocom_data.h>
 #include <osmocom/bb/common/ms.h>
 #include <osmocom/bb/common/networks.h>
@@ -38,7 +41,6 @@
 #include <osmocom/bb/mobile/mncc_ms.h>
 #include <osmocom/bb/mobile/transaction.h>
 #include <osmocom/bb/mobile/vty.h>
-#include <osmocom/bb/mobile/app_mobile.h>
 #include <osmocom/bb/mobile/gsm480_ss.h>
 #include <osmocom/bb/mobile/gsm411_sms.h>
 #include <osmocom/vty/telnet_interface.h>
@@ -52,6 +54,12 @@ static struct cmd_node ms_node = {
 	1
 };
 
+static struct cmd_node gsmtap_node = {
+	GSMTAP_NODE,
+	"%s(gsmtap)# ",
+	1
+};
+
 static void l23_vty_restart_required_warn(struct vty *vty, struct osmocom_ms *ms)
 {
 	if (l23_vty_reading)
@@ -120,6 +128,171 @@ void l23_ms_dump(struct osmocom_ms *ms, struct vty *vty)
 		VTY_NEWLINE);
 }
 
+/* "gsmtap" config */
+gDEFUN(l23_cfg_gsmtap, l23_cfg_gsmtap_cmd, "gsmtap",
+	"Configure GSMTAP\n")
+{
+	vty->node = GSMTAP_NODE;
+	return CMD_SUCCESS;
+}
+
+static const struct value_string gsmtap_categ_gprs_names[] = {
+	{ L23_GSMTAP_GPRS_C_DL_UNKNOWN,		"dl-unknown" },
+	{ L23_GSMTAP_GPRS_C_DL_DUMMY,		"dl-dummy" },
+	{ L23_GSMTAP_GPRS_C_DL_CTRL,		"dl-ctrl" },
+	{ L23_GSMTAP_GPRS_C_DL_DATA_GPRS,	"dl-data-gprs" },
+	{ L23_GSMTAP_GPRS_C_DL_DATA_EGPRS,	"dl-data-egprs" },
+	{ L23_GSMTAP_GPRS_C_UL_UNKNOWN,		"ul-unknown" },
+	{ L23_GSMTAP_GPRS_C_UL_DUMMY,		"ul-dummy" },
+	{ L23_GSMTAP_GPRS_C_UL_CTRL,		"ul-ctrl" },
+	{ L23_GSMTAP_GPRS_C_UL_DATA_GPRS,	"ul-data-gprs" },
+	{ L23_GSMTAP_GPRS_C_UL_DATA_EGPRS,	"ul-data-egprs" },
+	{ 0, NULL }
+};
+
+static const struct value_string gsmtap_categ_gprs_help[] = {
+	{ L23_GSMTAP_GPRS_C_DL_UNKNOWN,		"Unknown / Unparseable / Erroneous Downlink Blocks" },
+	{ L23_GSMTAP_GPRS_C_DL_DUMMY,		"Downlink Dummy Blocks" },
+	{ L23_GSMTAP_GPRS_C_DL_CTRL,		"Downlink Control Blocks" },
+	{ L23_GSMTAP_GPRS_C_DL_DATA_GPRS,	"Downlink Data Blocks (GPRS)" },
+	{ L23_GSMTAP_GPRS_C_DL_DATA_EGPRS,	"Downlink Data Blocks (EGPRS)" },
+	{ L23_GSMTAP_GPRS_C_UL_UNKNOWN,		"Unknown / Unparseable / Erroneous Downlink Blocks" },
+	{ L23_GSMTAP_GPRS_C_UL_DUMMY,		"Uplink Dummy Blocks" },
+	{ L23_GSMTAP_GPRS_C_UL_CTRL,		"Uplink Control Blocks" },
+	{ L23_GSMTAP_GPRS_C_UL_DATA_GPRS,	"Uplink Data Blocks (GPRS)" },
+	{ L23_GSMTAP_GPRS_C_UL_DATA_EGPRS,	"Uplink Data Blocks (EGPRS)" },
+	{ 0, NULL }
+};
+
+DEFUN(cfg_gsmtap_gsmtap_remote_host,
+      cfg_gsmtap_gsmtap_remote_host_cmd,
+      "remote-host [HOSTNAME]",
+      "Enable GSMTAP Um logging\n"
+      "Remote IP address or hostname ('localhost' if omitted)\n")
+{
+	osmo_talloc_replace_string(l23_ctx, &l23_cfg.gsmtap.remote_host,
+				   argc > 0 ? argv[0] : "localhost");
+
+	if (vty->type != VTY_FILE)
+		vty_out(vty, "%% This command requires restart%s", VTY_NEWLINE);
+
+	return CMD_SUCCESS;
+}
+
+DEFUN(cfg_gsmtap_no_gsmtap_remote_host,
+      cfg_gsmtap_no_gsmtap_remote_host_cmd,
+      "no remote-host",
+      NO_STR "Disable GSMTAP Um logging\n")
+{
+	TALLOC_FREE(l23_cfg.gsmtap.remote_host);
+	if (vty->type != VTY_FILE)
+		vty_out(vty, "%% This command requires restart%s", VTY_NEWLINE);
+
+	return CMD_SUCCESS;
+}
+
+DEFUN(cfg_gsmtap_gsmtap_lchan_all, cfg_gsmtap_gsmtap_lchan_all_cmd,
+	"lchan (enable-all|disable-all)",
+	"Enable/disable sending of UL/DL messages over GSMTAP\n"
+	"Enable all kinds of messages (all LCHAN)\n"
+	"Disable all kinds of messages (all LCHAN)\n")
+{
+	if (argv[0][0] == 'e') {
+		l23_cfg.gsmtap.lchan_mask = UINT32_MAX;
+		l23_cfg.gsmtap.lchan_acch_mask = UINT32_MAX;
+		l23_cfg.gsmtap.lchan_acch = true;
+	} else {
+		l23_cfg.gsmtap.lchan_mask = 0x00;
+		l23_cfg.gsmtap.lchan_acch_mask = 0x00;
+		l23_cfg.gsmtap.lchan_acch = false;
+	}
+
+	return CMD_SUCCESS;
+}
+
+DEFUN(cfg_gsmtap_gsmtap_lchan, cfg_gsmtap_gsmtap_lchan_cmd,
+	"HIDDEN", "HIDDEN")
+{
+	unsigned int channel;
+
+	if (osmo_str_startswith(argv[0], "sacch")) {
+		if (strcmp(argv[0], "sacch") == 0) {
+			l23_cfg.gsmtap.lchan_acch = true;
+		} else {
+			channel = get_string_value(gsmtap_gsm_channel_names, argv[0]);
+			channel &= ~GSMTAP_CHANNEL_ACCH;
+			l23_cfg.gsmtap.lchan_acch_mask |= (1 << channel);
+		}
+	} else {
+		channel = get_string_value(gsmtap_gsm_channel_names, argv[0]);
+		l23_cfg.gsmtap.lchan_mask |= (1 << channel);
+	}
+
+	return CMD_SUCCESS;
+}
+
+DEFUN(cfg_gsmtap_no_gsmtap_lchan, cfg_gsmtap_no_gsmtap_lchan_cmd,
+	"HIDDEN", "HIDDEN")
+{
+	unsigned int channel;
+
+	if (osmo_str_startswith(argv[0], "sacch")) {
+		if (strcmp(argv[0], "sacch") == 0) {
+			l23_cfg.gsmtap.lchan_acch = false;
+		} else {
+			channel = get_string_value(gsmtap_gsm_channel_names, argv[0]);
+			channel &= ~GSMTAP_CHANNEL_ACCH;
+			l23_cfg.gsmtap.lchan_acch_mask &= ~(1 << channel);
+		}
+	} else {
+		channel = get_string_value(gsmtap_gsm_channel_names, argv[0]);
+		l23_cfg.gsmtap.lchan_mask &= ~(1 << channel);
+	}
+
+	return CMD_SUCCESS;
+}
+
+DEFUN(cfg_gsmtap_gsmtap_categ_gprs_all, cfg_gsmtap_gsmtap_categ_gprs_all_cmd,
+	"category gprs (enable-all|disable-all)",
+	"Enable/disable sending of UL/DL messages over GSMTAP\n"
+	"Enable all kinds of messages (all categories)\n"
+	"Disable all kinds of messages (all categories)\n")
+{
+
+	if (strcmp(argv[0], "enable-all") == 0)
+		l23_cfg.gsmtap.categ_gprs_mask = UINT32_MAX;
+	else
+		l23_cfg.gsmtap.categ_gprs_mask = 0x00;
+
+	return CMD_SUCCESS;
+}
+
+DEFUN(cfg_gsmtap_gsmtap_categ_gprs, cfg_gsmtap_gsmtap_categ_gprs_cmd, "HIDDEN", "HIDDEN")
+{
+	int categ;
+
+	categ = get_string_value(gsmtap_categ_gprs_names, argv[0]);
+	if (categ < 0)
+		return CMD_WARNING;
+
+	l23_cfg.gsmtap.categ_gprs_mask |= (1 << categ);
+
+	return CMD_SUCCESS;
+}
+
+DEFUN(cfg_gsmtap_no_gsmtap_categ_gprs, cfg_gsmtap_no_gsmtap_categ_gprs_cmd, "HIDDEN", "HIDDEN")
+{
+	int categ;
+
+	categ = get_string_value(gsmtap_categ_gprs_names, argv[0]);
+	if (categ < 0)
+		return CMD_WARNING;
+
+	l23_cfg.gsmtap.categ_gprs_mask &= ~(1 << categ);
+
+	return CMD_SUCCESS;
+}
+
 
 gDEFUN(l23_show_ms, l23_show_ms_cmd, "show ms [MS_NAME]",
 	SHOW_STR "Display available MS entities\n")
@@ -228,6 +401,53 @@ DEFUN(cfg_ms_shutdown_force, cfg_ms_shutdown_force_cmd, "shutdown force",
 	return data.ms_stop.rc;
 }
 
+static int l23_vty_config_write_gsmtap_node(struct vty *vty)
+{
+	const char *chan_buf;
+	unsigned int i;
+
+	vty_out(vty, "gsmtap%s", VTY_NEWLINE);
+
+	if (l23_cfg.gsmtap.remote_host)
+		vty_out(vty, " remote-host %s%s", l23_cfg.gsmtap.remote_host, VTY_NEWLINE);
+	else
+		vty_out(vty, " no remote-host%s", VTY_NEWLINE);
+
+	if (l23_cfg.gsmtap.lchan_acch)
+		vty_out(vty, " lchan sacch%s", VTY_NEWLINE);
+
+	for (i = 0; i < sizeof(uint32_t) * 8; i++) {
+		if (l23_cfg.gsmtap.lchan_acch_mask & ((uint32_t) 1 << i)) {
+			chan_buf = get_value_string_or_null(gsmtap_gsm_channel_names, GSMTAP_CHANNEL_ACCH | i);
+			if (chan_buf == NULL)
+				continue;
+			chan_buf = osmo_str_tolower(chan_buf);
+			vty_out(vty, " lchan %s%s", chan_buf, VTY_NEWLINE);
+		}
+	}
+
+	for (i = 0; i < sizeof(uint32_t) * 8; i++) {
+		if (l23_cfg.gsmtap.lchan_mask & ((uint32_t) 1 << i)) {
+			chan_buf = get_value_string_or_null(gsmtap_gsm_channel_names, i);
+			if (chan_buf == NULL)
+				continue;
+			chan_buf = osmo_str_tolower(chan_buf);
+			vty_out(vty, " lchan %s%s", chan_buf, VTY_NEWLINE);
+		}
+	}
+
+	for (i = 0; i < 32; i++) {
+		if (l23_cfg.gsmtap.categ_gprs_mask & ((uint32_t)1 << i)) {
+			const char *category_buf;
+			if (!(category_buf = get_value_string_or_null(gsmtap_categ_gprs_names, i)))
+				continue;
+			vty_out(vty, " category gprs %s%s", category_buf, VTY_NEWLINE);
+		}
+	}
+
+	return CMD_SUCCESS;
+}
+
 void l23_vty_config_write_ms_node(struct vty *vty, const struct osmocom_ms *ms, const char *prefix)
 {
 	size_t prefix_len = strlen(prefix);
@@ -260,9 +480,62 @@ void l23_vty_config_write_ms_node_contents_final(struct vty *vty, const struct o
 	vty_out(vty, "!%s", VTY_NEWLINE);
 }
 
+static void l23_vty_init_gsmtap(void)
+{
+	cfg_gsmtap_gsmtap_lchan_cmd.string = vty_cmd_string_from_valstr(l23_ctx, gsmtap_gsm_channel_names,
+						"lchan (sacch|",
+						"|", ")", VTY_DO_LOWER);
+	cfg_gsmtap_gsmtap_lchan_cmd.doc = vty_cmd_string_from_valstr(l23_ctx, gsmtap_gsm_channel_names,
+						"Enable sending of UL/DL messages over GSMTAP\n" "SACCH\n",
+						"\n", "", 0);
+
+	cfg_gsmtap_no_gsmtap_lchan_cmd.string = vty_cmd_string_from_valstr(l23_ctx, gsmtap_gsm_channel_names,
+						"no lchan (sacch|",
+						"|", ")", VTY_DO_LOWER);
+	cfg_gsmtap_no_gsmtap_lchan_cmd.doc = vty_cmd_string_from_valstr(l23_ctx, gsmtap_gsm_channel_names,
+						NO_STR "Disable sending of UL/DL messages over GSMTAP\n" "SACCH\n",
+						"\n", "", 0);
+
+
+	cfg_gsmtap_gsmtap_categ_gprs_cmd.string = vty_cmd_string_from_valstr(l23_ctx, gsmtap_categ_gprs_names,
+						"category gprs (",
+						"|", ")", VTY_DO_LOWER);
+	cfg_gsmtap_gsmtap_categ_gprs_cmd.doc = vty_cmd_string_from_valstr(l23_ctx, gsmtap_categ_gprs_help,
+						"GSMTAP Category\n" "GPRS\n",
+						"\n", "", 0);
+	cfg_gsmtap_no_gsmtap_categ_gprs_cmd.string = vty_cmd_string_from_valstr(l23_ctx, gsmtap_categ_gprs_names,
+						"no category gprs (",
+						"|", ")", VTY_DO_LOWER);
+	cfg_gsmtap_no_gsmtap_categ_gprs_cmd.doc = vty_cmd_string_from_valstr(l23_ctx, gsmtap_categ_gprs_help,
+						NO_STR "GSMTAP Category\n" "GPRS\n",
+						"\n", "", 0);
+
+	install_element(CONFIG_NODE, &l23_cfg_gsmtap_cmd);
+
+	install_node(&gsmtap_node, l23_vty_config_write_gsmtap_node);
+	install_element(GSMTAP_NODE, &cfg_gsmtap_gsmtap_remote_host_cmd);
+	install_element(GSMTAP_NODE, &cfg_gsmtap_no_gsmtap_remote_host_cmd);
+	install_element(GSMTAP_NODE, &cfg_gsmtap_gsmtap_lchan_all_cmd);
+	install_element(GSMTAP_NODE, &cfg_gsmtap_gsmtap_lchan_cmd);
+	install_element(GSMTAP_NODE, &cfg_gsmtap_no_gsmtap_lchan_cmd);
+	install_element(GSMTAP_NODE, &cfg_gsmtap_gsmtap_categ_gprs_all_cmd);
+	install_element(GSMTAP_NODE, &cfg_gsmtap_gsmtap_categ_gprs_cmd);
+	install_element(GSMTAP_NODE, &cfg_gsmtap_no_gsmtap_categ_gprs_cmd);
+}
+
 int l23_vty_init(int (*config_write_ms_node_cb)(struct vty *), osmo_signal_cbfn *l23_vty_signal_cb)
 {
+	struct l23_app_info *app;
+	unsigned int app_supp_opt = 0x00;
 	int rc = 0;
+
+	app = l23_app_info();
+	if (app && app->cfg_supported != NULL)
+		app_supp_opt = app->cfg_supported();
+
+	if (app_supp_opt & L23_OPT_TAP)
+		l23_vty_init_gsmtap();
+
 	install_node(&ms_node, config_write_ms_node_cb);
 	install_element(MS_NODE, &cfg_ms_layer2_cmd);
 	install_element(MS_NODE, &cfg_ms_shutdown_cmd);
diff --git a/src/host/layer23/src/mobile/main.c b/src/host/layer23/src/mobile/main.c
index 8938e309..deb7948f 100644
--- a/src/host/layer23/src/mobile/main.c
+++ b/src/host/layer23/src/mobile/main.c
@@ -51,10 +51,10 @@
 #include "config.h"
 
 void *l23_ctx = NULL;
+struct l23_global_config l23_cfg;
 struct llist_head ms_list;
 static char *gsmtap_ip = 0;
 static const char *custom_cfg_file = NULL;
-struct gsmtap_inst *gsmtap_inst = NULL;
 static char *config_file = NULL;
 char *config_dir = NULL;
 int daemonize = 0;
@@ -312,12 +312,12 @@ int main(int argc, char **argv)
 	}
 
 	if (gsmtap_ip) {
-		gsmtap_inst = gsmtap_source_init(gsmtap_ip, GSMTAP_UDP_PORT, 1);
-		if (!gsmtap_inst) {
+		l23_cfg.gsmtap.inst = gsmtap_source_init(gsmtap_ip, GSMTAP_UDP_PORT, 1);
+		if (!l23_cfg.gsmtap.inst) {
 			fprintf(stderr, "Failed during gsmtap_init()\n");
 			exit(1);
 		}
-		gsmtap_source_add_sink(gsmtap_inst);
+		gsmtap_source_add_sink(l23_cfg.gsmtap.inst);
 	}
 
 	if (l23_app_start) {