add support for gsm0808 HANDOVER REQUIRED message

Related: OS#2283 (inter-BSC Handover, BSC side, MO)
Change-Id: Idb6dc3eab0282158a17091d97ed77c1e2e3eb3c2

4 files changed, 130 insertions, 0 deletions

diff --git a/include/osmocom/gsm/gsm0808.h b/include/osmocom/gsm/gsm0808.h
index 369d713c..4f239e66 100644
--- a/include/osmocom/gsm/gsm0808.h
+++ b/include/osmocom/gsm/gsm0808.h
@@ -25,6 +25,7 @@
 
 #include "tlv.h"
 #include <osmocom/gsm/protocol/gsm_08_08.h>
+#include <osmocom/gsm/gsm0808_utils.h>
 #include <osmocom/gsm/gsm23003.h>
 
 struct sockaddr_storage;
@@ -80,6 +81,42 @@ struct msgb *gsm0808_create_paging(const char *imsi, const uint32_t *tmsi,
 				   const uint8_t *chan_needed)
 				   OSMO_DEPRECATED("use gsm0808_create_paging2 instead");
 
+/*! 3GPP TS 48.008 §3.2.2.5.8 Old BSS to New BSS information */
+struct gsm0808_old_bss_to_new_bss_info {
+	bool extra_information_present;
+	struct {
+		bool prec;
+		bool lcs;
+		bool ue_prob;
+	} extra_information;
+
+	bool current_channel_type_2_present;
+	struct {
+		uint8_t mode;
+		uint8_t field;
+	} current_channel_type_2;
+
+	/* more items are defined in the spec and may be added later */
+};
+
+/*! 3GPP TS 48.008 §3.2.1.9 HANDOVER REQUIRED */
+struct gsm0808_handover_required {
+	uint16_t cause;
+	struct gsm0808_cell_id_list2 cil;
+
+	bool current_channel_type_1_present;
+	uint8_t current_channel_type_1;
+
+	bool speech_version_used_present;
+	uint8_t speech_version_used;
+
+	bool old_bss_to_new_bss_info_present;
+	struct gsm0808_old_bss_to_new_bss_info old_bss_to_new_bss_info;
+
+	/* more items are defined in the spec and may be added later */
+};
+struct msgb *gsm0808_create_handover_required(const struct gsm0808_handover_required *params);
+
 struct msgb *gsm0808_create_dtap(struct msgb *msg, uint8_t link_id);
 void gsm0808_prepend_dtap_header(struct msgb *msg, uint8_t link_id);
 
diff --git a/include/osmocom/gsm/protocol/gsm_08_08.h b/include/osmocom/gsm/protocol/gsm_08_08.h
index b699080c..60b96812 100644
--- a/include/osmocom/gsm/protocol/gsm_08_08.h
+++ b/include/osmocom/gsm/protocol/gsm_08_08.h
@@ -295,6 +295,28 @@ enum GSM0808_IE_CODING {
 	GSM0808_IE_LAST_USED_EUTRAN_PLMN_ID	= 0x95,
 };
 
+/* 3GPP TS 48.008 3.2.3 Signalling Field Element Coding */
+enum GSM0808_SIGNALLING_FIELD_ELEMENT_CODING {
+	GSM0808_FE_IE_EXTRA_INFORMATION = 0x01, /*< 3.2.3.1  */
+	GSM0808_FE_IE_CURRENT_CHANNEL_TYPE_2 = 0x02, /*< 3.2.3.2  */
+	GSM0808_FE_IE_TARGET_CELL_RADIO_INFORMATION = 0x03, /*< 3.2.3.3  */
+	GSM0808_FE_IE_GPRS_SUSPEND_INFORMATION = 0x04, /*< 3.2.3.4  */
+	GSM0808_FE_IE_MULTIRATE_CONFIGURATION_INFORMATION = 0x05, /*< 3.2.3.5  */
+	GSM0808_FE_IE_DUAL_TRANSFER_MODE_INFORMATION = 0x06, /*< 3.2.3.6  */
+	GSM0808_FE_IE_INTER_RAT_HANDOVER_INFO = 0x07, /*< 3.2.3.7  */
+	GSM0808_FE_IE_CDMA2000_CAPABILITY_INFORMATION = 0x08, /*< 3.2.3.8  */
+	GSM0808_FE_IE_DOWNLINK_CELL_LOAD_INFORMATION = 0x09, /*< 3.2.3.9  */
+	GSM0808_FE_IE_UPLINK_CELL_LOAD_INFORMATION = 0x0a, /*< 3.2.3.10 */
+	GSM0808_FE_IE_CELL_LOAD_INFORMATION_GROUP = 0x0b, /*< 3.2.3.11 */
+	GSM0808_FE_IE_CELL_LOAD_INFORMATION = 0x0c, /*< 3.2.3.12 */
+	GSM0808_FE_IE_PS_INDICATION = 0x0d, /*< 3.2.3.13 */
+	GSM0808_FE_IE_DTM_HANDOVER_COMMAND_INDICATION = 0x0e, /*< 3.2.3.14 */
+	GSM0808_FE_IE_D_RNTI = 0xfe, /*< 3.2.3.15 */
+	GSM0808_FE_IE_IRAT_MEASUREMENT_CONFIGURATION = 0x0f, /*< 3.2.3.16 */
+	GSM0808_FE_IE_SOURCE_CELL_ID = 0x10, /*< 3.2.3.17 */
+	GSM0808_FE_IE_IRAT_MEASUREMENT_CONFIGURATION_EXTENDED_E_ARFCNS = 0x11, /*< 3.2.3.18 */
+};
+
 /* GSM 08.08 3.2.2.5 Cause */
 enum gsm0808_cause {
 	GSM0808_CAUSE_RADIO_INTERFACE_MESSAGE_FAILURE			= 0,
diff --git a/src/gsm/gsm0808.c b/src/gsm/gsm0808.c
index 47431756..80f5e6ce 100644
--- a/src/gsm/gsm0808.c
+++ b/src/gsm/gsm0808.c
@@ -609,6 +609,76 @@ struct msgb *gsm0808_create_paging(const char *imsi, const uint32_t *tmsi,
 	return gsm0808_create_paging2(imsi, tmsi, &cil2, chan_needed);
 }
 
+static uint8_t put_old_bss_to_new_bss_information(struct msgb *msg,
+						  const struct gsm0808_old_bss_to_new_bss_info *i)
+{
+	uint8_t *old_tail;
+	uint8_t *tlv_len;
+
+	msgb_put_u8(msg, GSM0808_IE_OLD_BSS_TO_NEW_BSS_INFORMATION);
+	tlv_len = msgb_put(msg, 1);
+	old_tail = msg->tail;
+
+	if (i->extra_information_present) {
+		uint8_t val = 0;
+		if (i->extra_information.prec)
+			val |= 1 << 0;
+		if (i->extra_information.lcs)
+			val |= 1 << 1;
+		if (i->extra_information.ue_prob)
+			val |= 1 << 2;
+		msgb_tlv_put(msg, GSM0808_FE_IE_EXTRA_INFORMATION, 1, &val);
+	}
+
+	if (i->current_channel_type_2_present) {
+		uint8_t val[2] = {
+			i->current_channel_type_2.mode,
+			i->current_channel_type_2.field,
+		};
+		msgb_tlv_put(msg, GSM0808_FE_IE_CURRENT_CHANNEL_TYPE_2, 2, val);
+	}
+
+	*tlv_len = (uint8_t) (msg->tail - old_tail);
+	return *tlv_len + 2;
+}
+
+/*! Create BSSMAP HANDOVER REQUIRED message.
+ * \param[in] params  All information to be encoded.
+ * \returns newly allocated msgb with BSSMAP REQUIRED message. */
+struct msgb *gsm0808_create_handover_required(const struct gsm0808_handover_required *params)
+{
+	struct msgb *msg;
+
+	msg = msgb_alloc_headroom(BSSMAP_MSG_SIZE, BSSMAP_MSG_HEADROOM, "BSSMAP-HANDOVER-REQUIRED");
+	if (!msg)
+		return NULL;
+
+	/* Message Type, 3.2.2.1 */
+	msgb_v_put(msg, BSS_MAP_MSG_HANDOVER_REQUIRED);
+
+	/* Cause, 3.2.2.5 */
+	msgb_tlv_put(msg, GSM0808_IE_CAUSE, params->cause & 0x80? 2 : 1, (const uint8_t*)&params->cause);
+
+	/* Cell Identifier List, 3.2.2.27 */
+	gsm0808_enc_cell_id_list2(msg, &params->cil);
+
+	/* Current Channel Type 1, 3.2.2.49 */
+	if (params->current_channel_type_1_present)
+		msgb_tv_fixed_put(msg, GSM0808_IE_CURRENT_CHANNEL_TYPE_1, 1, &params->current_channel_type_1);
+
+	/* Speech Version (Used), 3.2.2.51 */
+	if (params->speech_version_used_present)
+		msgb_tv_fixed_put(msg, GSM0808_IE_SPEECH_VERSION, 1, &params->speech_version_used);
+
+	if (params->old_bss_to_new_bss_info_present)
+		put_old_bss_to_new_bss_information(msg, &params->old_bss_to_new_bss_info);
+
+	/* pre-pend the header */
+	msg->l3h = msgb_tv_push(msg, BSSAP_MSG_BSS_MANAGEMENT, msgb_length(msg));
+
+	return msg;
+}
+
 /*! Prepend a DTAP header to given Message Buffer
  *  \param[in] msgb Message Buffer
  *  \param[in] link_id Link Identifier */
diff --git a/src/gsm/libosmogsm.map b/src/gsm/libosmogsm.map
index 5a574290..58a5bfe5 100644
--- a/src/gsm/libosmogsm.map
+++ b/src/gsm/libosmogsm.map
@@ -161,6 +161,7 @@ gsm0808_create_layer3_2;
 gsm0808_create_reset;
 gsm0808_create_reset_ack;
 gsm0808_create_sapi_reject;
+gsm0808_create_handover_required;
 gsm0808_prepend_dtap_header;
 gsm0808_enc_aoip_trasp_addr;
 gsm0808_dec_aoip_trasp_addr;