virt_phy: implement GSMTAP_CHANNEL_VOICE

GSMTAP_CHANNEL_VOICE is the mechanism by which GSMTAP can [finally!]
be used to transport circuit-switched voice codec payload, and not
just signalling.

Original patch by Neels Hofmeyr, heavily extended by Harald Welte.

Change-Id: Id72cf23b7c6587efae4cdaa7b50ab4d85b8c8d22

3 files changed, 63 insertions, 14 deletions

diff --git a/src/host/virt_phy/configure.ac b/src/host/virt_phy/configure.ac
index a2c2bf65..fbff2c11 100644
--- a/src/host/virt_phy/configure.ac
+++ b/src/host/virt_phy/configure.ac
@@ -12,6 +12,8 @@ AC_PROG_CC
 AC_PROG_INSTALL
 
 dnl checks for libraries
+dnl TODO: insert libosmocore version with GSMTAP_CHANNEL_VOICE: PKG_CHECK_MODULES(LIBOSMOCORE, libosmocore >= 1.4.0)
+dnl       (at time of writing not released yet)
 PKG_CHECK_MODULES(LIBOSMOCORE, libosmocore)
 PKG_CHECK_MODULES(LIBOSMOGSM, libosmogsm)
 
diff --git a/src/host/virt_phy/src/gsmtapl1_if.c b/src/host/virt_phy/src/gsmtapl1_if.c
index 30f88ff4..3fa69c4f 100644
--- a/src/host/virt_phy/src/gsmtapl1_if.c
+++ b/src/host/virt_phy/src/gsmtapl1_if.c
@@ -26,6 +26,7 @@
 #include <osmocom/gsm/rsl.h>
 #include <osmocom/gsm/gsm_utils.h>
 #include <osmocom/gsm/protocol/gsm_08_58.h>
+#include <osmocom/gsm/protocol/gsm_04_08.h>
 #include <osmocom/core/msgb.h>
 #include <stddef.h>
 #include <stdlib.h>
@@ -48,6 +49,29 @@ static char *pseudo_lchan_name(uint16_t arfcn, uint8_t ts, uint8_t ss, uint8_t s
 	return lname;
 }
 
+/* Return gsmtap_um_voice_type or -1 on error */
+static int get_um_voice_type(enum gsm48_chan_mode tch_mode, uint8_t rsl_chantype)
+{
+	switch (tch_mode) {
+	case GSM48_CMODE_SPEECH_V1:
+		switch (rsl_chantype) {
+		case RSL_CHAN_Bm_ACCHs:
+			return GSMTAP_UM_VOICE_FR;
+		case RSL_CHAN_Lm_ACCHs:
+			return GSMTAP_UM_VOICE_HR;
+		default:
+			return -1;
+		}
+		break;
+	case GSM48_CMODE_SPEECH_EFR:
+		return GSMTAP_UM_VOICE_EFR;
+	case GSM48_CMODE_SPEECH_AMR:
+		return GSMTAP_UM_VOICE_AMR;
+	default:
+		return -1;
+	}
+}
+
 /**
  * Replace l11 header of given msgb by a gsmtap header and send it over the virt um.
  */
@@ -74,12 +98,25 @@ void gsmtapl1_tx_to_virt_um_inst(struct l1_model_ms *ms, uint32_t fn, uint8_t tn
 		rsl_chantype = RSL_CHAN_OSMO_PDCH;
 		timeslot = tn;
 		subslot = 0;
-		gsmtap_chan = chantype_rsl2gsmtap(rsl_chantype, 0);
+		gsmtap_chan = chantype_rsl2gsmtap2(rsl_chantype, 0, false);
+		break;
+	case L1CTL_TRAFFIC_REQ:
+		ul = (struct l1ctl_info_ul *)l1h->data;
+		rsl_dec_chan_nr(ul->chan_nr, &rsl_chantype, &subslot, &timeslot);
+		gsmtap_chan = chantype_rsl2gsmtap2(rsl_chantype, 0, true);
+		/* the first byte indicates the type of voice codec (gsmtap_um_voice_type);
+		 * let's first strip any data in front of the l2 header, then push this extra
+		 * byte to the front and finally adjust the l2h pointer */
+		msgb_pull_to_l2(msg);
+		msgb_push_u8(msg, get_um_voice_type(ms->state.tch_mode, rsl_chantype));
+		msg->l2h = msg->data;
+		data = msgb_l2(msg);
+		data_len = msgb_l2len(msg);
 		break;
 	default:
 		ul = (struct l1ctl_info_ul *)l1h->data;
 		rsl_dec_chan_nr(ul->chan_nr, &rsl_chantype, &subslot, &timeslot);
-		gsmtap_chan = chantype_rsl2gsmtap(rsl_chantype, ul->link_id);
+		gsmtap_chan = chantype_rsl2gsmtap2(rsl_chantype, ul->link_id, false);
 		break;
 	}
 
@@ -219,13 +256,7 @@ static void l1ctl_from_virt_um(struct l1ctl_sock_client *lsc, struct msgb *msg,
 	switch (gsmtap_chantype & ~GSMTAP_CHANNEL_ACCH & 0xff) {
 	case GSMTAP_CHANNEL_TCH_H:
 	case GSMTAP_CHANNEL_TCH_F:
-#if 0
-		/* TODO: handle voice */
-		if (!facch && !tch_acch) {
-			l1ctl_tx_traffic_ind(msg, arfcn, link_id, chan_nr, fn,
-					     snr, signal_dbm, 0, 0);
-		}
-#endif
+		/* This is TCH signalling, for voice frames see GSMTAP_CHANNEL_VOICE */
 	case GSMTAP_CHANNEL_SDCCH4:
 	case GSMTAP_CHANNEL_SDCCH8:
 		/* only forward messages on dedicated channels to l2, if
@@ -235,6 +266,16 @@ static void l1ctl_from_virt_um(struct l1ctl_sock_client *lsc, struct msgb *msg,
 			l1ctl_tx_data_ind(ms, msg, arfcn, link_id, chan_nr, fn, snr_db, signal_dbm, 0, 0);
 		}
 		break;
+	case GSMTAP_CHANNEL_VOICE_F:
+	case GSMTAP_CHANNEL_VOICE_H:
+		/* only forward messages on dedicated channels to l2, if
+		 * the timeslot and subslot is fitting */
+		if (ms->state.dedicated.tn == timeslot
+		    && ms->state.dedicated.subslot == subslot) {
+			l1ctl_tx_traffic_ind(ms, msg, arfcn, link_id, chan_nr, fn,
+					     snr_db, signal_dbm, 0, 0);
+		}
+		break;
 	case GSMTAP_CHANNEL_CBCH51:
 		/* only pass CBCH data if the user application actually indicated that a CBCH
 		 * is present */
diff --git a/src/host/virt_phy/src/virt_prim_traffic.c b/src/host/virt_phy/src/virt_prim_traffic.c
index 5f6b273b..3d2b2b15 100644
--- a/src/host/virt_phy/src/virt_prim_traffic.c
+++ b/src/host/virt_phy/src/virt_prim_traffic.c
@@ -84,7 +84,8 @@ void l1ctl_tx_traffic_ind(struct l1_model_ms *ms, struct msgb *msg, uint16_t arf
 	struct msgb *l1ctl_msg = NULL;
 	struct l1ctl_traffic_ind * l1ti;
 	struct l1ctl_info_dl * l1dl;
-	uint8_t *frame, frame_len;
+	uint8_t *frame;
+	int frame_len;
 	uint8_t rsl_chan_type, subchan, timeslot;
 	l1ctl_msg = l1ctl_msgb_alloc(L1CTL_TRAFFIC_IND);
 	l1dl = (struct l1ctl_info_dl *) msgb_put(l1ctl_msg, sizeof(*l1dl));
@@ -101,11 +102,16 @@ void l1ctl_tx_traffic_ind(struct l1_model_ms *ms, struct msgb *msg, uint16_t arf
 	l1dl->num_biterr = 0; /* no biterrors */
 	l1dl->fire_crc = 0;
 
-	/* TODO: traffic decoding and decryption */
-
-	frame_len = msgb_length(msg);
+	/* The first byte indicates the type of voice frame (enum gsmtap_um_voice_type),
+	 * which we simply ignore here and pass on the frame without that byte.
+	 * TODO: Check for consistency with ms->state.tch_mode ? */
+	frame_len = msgb_length(msg) - 1;
+	if (frame_len < 0) {
+		msgb_free(l1ctl_msg);
+		return;
+	}
 	frame = (uint8_t *) msgb_put(l1ctl_msg, frame_len);
-	memcpy(frame, msgb_data(msg), frame_len);
+	memcpy(frame, msgb_data(msg)+1, frame_len);
 
 	DEBUGPMS(DL1P, ms, "Tx L1CTL_TRAFFIC_IND (chan_nr=0x%02x, link_id=0x%02x)\n", chan_nr, link_id);
 	l1ctl_sap_tx_to_l23_inst(ms, l1ctl_msg);