Support sending OML Alerts via BTS

* extend BTS <-> PCU protocol with TXT messages
* use it to implement OML alerts support
* use it to implement version message
* add function to transmit both of them them
* send alerts for internal encoding problems as an example
* send version when BTS socket is connected

Note: requires corresponding change
If57459c0610f2c7b36d599b13087c8deef8bdd9e in libosmocore.

Related: OS#1614, 1615
Change-Id: If4ea5b3f7409df2fb030681ad468df6b711790a7

include/osmocom/pcu/pcuif_proto.h

@@ -4,6 +4,7 @@
 #include <osmocom/gsm/l1sap.h>
 
 #define PCU_IF_VERSION		0x07
+#define TXT_MAX_LEN	128
 
 /* msg_type */
 #define PCU_IF_MSG_DATA_REQ	0x00	/* send data to given channel */
@@ -15,6 +16,7 @@
 #define PCU_IF_MSG_ACT_REQ	0x40	/* activate/deactivate PDCH */
 #define PCU_IF_MSG_TIME_IND	0x52	/* GSM time indication */
 #define PCU_IF_MSG_PAG_REQ	0x60	/* paging request */
+#define PCU_IF_MSG_TXT_IND	0x70	/* Text indication for BTS */
 
 /* sapi */
 #define PCU_IF_SAPI_RACH	0x01	/* channel request on CCCH */
@@ -42,6 +44,16 @@
 #define PCU_IF_FLAG_MCS8	(1 << 27)
 #define PCU_IF_FLAG_MCS9	(1 << 28)
 
+enum gsm_pcu_if_text_type {
+	PCU_VERSION,
+	PCU_OML_ALERT,
+};
+
+struct gsm_pcu_if_txt_ind {
+	uint8_t		type; /* gsm_pcu_if_text_type */
+	char		text[TXT_MAX_LEN]; /* Text to be transmitted to BTS */
+} __attribute__ ((packed));
+
 struct gsm_pcu_if_data {
 	uint8_t		sapi;
 	uint8_t		len;
@@ -150,6 +162,7 @@ struct gsm_pcu_if {
 		struct gsm_pcu_if_data		data_ind;
 		struct gsm_pcu_if_rts_req	rts_req;
 		struct gsm_pcu_if_rach_ind	rach_ind;
+		struct gsm_pcu_if_txt_ind	txt_ind;
 		struct gsm_pcu_if_info_ind	info_ind;
 		struct gsm_pcu_if_act_req	act_req;
 		struct gsm_pcu_if_time_ind	time_ind;

src/encoding.cpp

@@ -320,6 +320,13 @@ int Encoding::write_immediate_assignment_reject(
 	return plen;
 }
 
+static inline void log_alert_exit(const char * error)
+{
+	LOGP(DRLCMACUL, LOGL_ERROR, error);
+	pcu_tx_txt_ind(PCU_OML_ALERT, error);
+	exit(1);
+}
+
 /*
  * Immediate assignment, sent on the CCCH/AGCH
  * see GSM 04.08, 9.1.18 and GSM 44.018, 9.1.18 + 10.5.2.16
@@ -374,11 +381,10 @@ int Encoding::write_immediate_assignment(
 	// A zero-length LV.  Just write L=0.
 	bitvec_write_field(dest, wp,0,8);
 
-	if ((wp % 8)) {
-		LOGP(DRLCMACUL, LOGL_ERROR, "Length of IMM.ASS without rest "
-			"octets is not multiple of 8 bits, PLEASE FIX!\n");
-		exit (0);
-	}
+	if ((wp % 8))
+		log_alert_exit("Length of IMM.ASS without rest octets is not "
+			       "multiple of 8 bits, PLEASE FIX!\n");
+
 	plen = wp / 8;
 
 	if (downlink)
@@ -618,11 +624,11 @@ int Encoding::write_paging_request(bitvec * dest, uint8_t *ptmsi, uint16_t ptmsi
 	{
 		bitvec_write_field(dest, wp,ptmsi[i],8); // PTMSI
 	}
-	if ((wp % 8)) {
-		LOGP(DRLCMACUL, LOGL_ERROR, "Length of PAG.REQ without rest "
-			"octets is not multiple of 8 bits, PLEASE FIX!\n");
-		exit (0);
-	}
+
+	if ((wp % 8))
+		log_alert_exit("Length of PAG.REQ without rest octets is not "
+			       "multiple of 8 bits, PLEASE FIX!\n");
+
 	plen = wp / 8;
 	bitvec_write_field(dest, wp,0x0,1); // "L" NLN(PCH) = off
 	bitvec_write_field(dest, wp,0x0,1); // "L" Priority1 = off

src/osmobts_sock.cpp

@@ -287,6 +287,9 @@ int pcu_l1if_open(void)
 
 	pcu_sock_state = state;
 
+	LOGP(DL1IF, LOGL_INFO, "Sending version %s to BTS.\n", PACKAGE_VERSION);
+	pcu_tx_txt_ind(PCU_VERSION, "%s", PACKAGE_VERSION);
+
 	return 0;
 }
 

src/pcu_l1_if.cpp

@@ -73,6 +73,42 @@ struct msgb *pcu_msgb_alloc(uint8_t msg_type, uint8_t bts_nr)
 	return msg;
 }
 
+const struct value_string gsm_pcu_if_text_type_names[] = {
+	OSMO_VALUE_STRING(PCU_VERSION),
+	OSMO_VALUE_STRING(PCU_OML_ALERT),
+	{ 0, NULL }
+};
+
+int pcu_tx_txt_ind(enum gsm_pcu_if_text_type t, const char *fmt, ...)
+{
+	struct gsm_pcu_if *pcu_prim;
+	struct gsm_pcu_if_txt_ind *txt;
+	va_list ap;
+	char *rep;
+	struct msgb *msg = pcu_msgb_alloc(PCU_IF_MSG_TXT_IND, 0);
+	if (!msg)
+		return -ENOMEM;
+
+	pcu_prim = (struct gsm_pcu_if *) msg->data;
+	txt = &pcu_prim->u.txt_ind;
+	txt->type = t;
+
+	va_start(ap, fmt);
+	rep = talloc_vasprintf(tall_pcu_ctx, fmt, ap);
+	va_end(ap);
+
+	if (!rep)
+		return -ENOMEM;
+
+	osmo_strlcpy(txt->text, rep, TXT_MAX_LEN);
+	talloc_free(rep);
+
+	LOGP(DL1IF, LOGL_INFO, "Sending %s TXT as %s to BTS\n", txt->text,
+	     get_value_string(gsm_pcu_if_text_type_names, t));
+
+	return pcu_sock_send(msg);
+}
+
 static int pcu_tx_act_req(uint8_t trx, uint8_t ts, uint8_t activate)
 {
 	struct msgb *msg;

src/pcu_l1_if.h

@@ -29,6 +29,7 @@ extern "C" {
 #include <osmocom/core/timer.h>
 #include <osmocom/core/bitvec.h>
 #include <osmocom/gsm/gsm_utils.h>
+#include <osmocom/pcu/pcuif_proto.h>
 #ifdef __cplusplus
 }
 #endif
@@ -131,6 +132,8 @@ void pcu_l1if_tx_agch(bitvec * block, int len);
 
 void pcu_l1if_tx_pch(bitvec * block, int plen, const char *imsi);
 
+int pcu_tx_txt_ind(enum gsm_pcu_if_text_type t, const char *fmt, ...);
+
 int pcu_l1if_open(void);
 void pcu_l1if_close(void);