Iniatial gsmtap support

This requires a wireshark with support for passing the new gsmtap V5
format into the existing wireshark dissectors for V5.

main.c

@@ -35,6 +35,8 @@
 #include <osmocom/core/stats.h>
 #include <osmocom/core/rate_ctr.h>
 #include <osmocom/core/socket.h>
+#include <osmocom/core/gsmtap.h>
+#include <osmocom/core/gsmtap_util.h>
 
 #include <osmocom/ctrl/control_vty.h>
 
@@ -62,8 +64,14 @@
 #define OSMO_CTRL_PORT_MGW 4267
 #endif
 
+/* only temporarily until this is in libosmocore gsmtap.h */
+#ifndef GSMTAP_E1T1_V5EF
+#define GSMTAP_E1T1_V5EF	0x06
+#endif
+
 void *tall_v5le_ctx = NULL;
 struct v5x_instance *v5i = NULL;
+static struct gsmtap_inst *g_gti;
 
 struct v5le_config {
 };
@@ -102,6 +110,10 @@ static void hdlc_rx_cb(struct e1inp_ts *ts, struct msgb *msg)
 
 	LOGP(DLINP, LOGL_NOTICE, "L1->L2: %s\n", msgb_hexdump(msg));
 
+	/* send V5 data via gsmtap so wireshark can receive + decode it */
+	gsmtap_send_ex(g_gti, GSMTAP_TYPE_E1T1, GSMTAP_ARFCN_F_UPLINK, ts->num, GSMTAP_E1T1_V5EF,
+			0, 0, 0, 0, msgb_data(msg), msgb_length(msg));
+
 	lapv5ef_rx(v5if->primary_link, msg);
 }
 
@@ -117,6 +129,10 @@ int ph_data_req(struct msgb *msg, void *cbdata)
 		struct e1inp_line *e1_line = e1inp_line_find(0);
 		struct e1inp_ts *ts = &e1_line->ts[16-1];
 
+	/* send V5 data via gsmtap so wireshark can receive + decode it */
+	gsmtap_send_ex(g_gti, GSMTAP_TYPE_E1T1, 0, ts->num, GSMTAP_E1T1_V5EF,
+			0, 0, 0, 0, msgb_data(msg), msgb_length(msg));
+
 	return e1inp_ts_send_hdlc(ts, msg);
 }
 
@@ -318,6 +334,10 @@ int main(int argc, char **argv)
 	if (rc < 0)
 		return rc;
 
+	g_gti = gsmtap_source_init("localhost", GSMTAP_UDP_PORT, 0);
+	OSMO_ASSERT(g_gti);
+	gsmtap_source_add_sink(g_gti);
+
 	rc = e1_init();
 	OSMO_ASSERT(rc == 0);