GSUP: add CHECK-IMEI message

Implement necessary messages for Procedure Check_IMEI_VLR (TS 23.018
Chapter 7.1.2.9). This lets the VLR ask the EIR to check if an IMEI
is valid. In the Osmocom stack, we don't have an EIR and this request
will be handled by the HLR. We will be able to store the IMEI in the
HLR as side-effect (OS#2541).

This is roughly based on TS 29.002 8.7.1 MAP_CHECK_IMEI service, but
only implements the bare minimum required IEs (imei and imei_result).

Related: OS#3733
Change-Id: I085819df0ea7f3bfeb0cabebb5fd1942a23c6155

5 files changed, 93 insertions, 0 deletions

diff --git a/include/osmocom/gsm/gsup.h b/include/osmocom/gsm/gsup.h
index 37e474c2..6adb0bfd 100644
--- a/include/osmocom/gsm/gsup.h
+++ b/include/osmocom/gsm/gsup.h
@@ -99,6 +99,9 @@ enum osmo_gsup_iei {
 	OSMO_GSUP_SM_RP_MMS_IE			= 0x45,
 	OSMO_GSUP_SM_ALERT_RSN_IE		= 0x46,
 
+	OSMO_GSUP_IMEI_IE			= 0x50,
+	OSMO_GSUP_IMEI_RESULT_IE		= 0x51,
+
 	_OSMO_GSUP_IEI_END_MARKER
 };
 
@@ -145,6 +148,10 @@ enum osmo_gsup_message_type {
 	OSMO_GSUP_MSGT_READY_FOR_SM_REQUEST	= 0b00101100,
 	OSMO_GSUP_MSGT_READY_FOR_SM_ERROR	= 0b00101101,
 	OSMO_GSUP_MSGT_READY_FOR_SM_RESULT	= 0b00101110,
+
+	OSMO_GSUP_MSGT_CHECK_IMEI_REQUEST	= 0b00110000,
+	OSMO_GSUP_MSGT_CHECK_IMEI_ERROR		= 0b00110001,
+	OSMO_GSUP_MSGT_CHECK_IMEI_RESULT	= 0b00110010,
 };
 
 #define OSMO_GSUP_IS_MSGT_REQUEST(msgt) (((msgt) & 0b00000011) == 0b00)
@@ -166,6 +173,11 @@ enum osmo_gsup_cn_domain {
 	OSMO_GSUP_CN_DOMAIN_CS			= 2,
 };
 
+enum osmo_gsup_imei_result {
+	OSMO_GSUP_IMEI_RESULT_ACK		= 1,
+	OSMO_GSUP_IMEI_RESULT_NACK		= 2,
+};
+
 /*! TCAP-like session state */
 enum osmo_gsup_session_state {
 	/*! Undefined session state */
@@ -259,6 +271,10 @@ struct osmo_gsup_message {
 	const uint8_t			*sm_rp_mms;
 	/*! Alert reason (see 3GPP TS 29.002, 7.6.8.8) */
 	enum osmo_gsup_sms_sm_alert_rsn_t	sm_alert_rsn;
+
+	const uint8_t			*imei_enc;
+	size_t				imei_enc_len;
+	enum osmo_gsup_imei_result	imei_result;
 };
 
 int osmo_gsup_decode(const uint8_t *data, size_t data_len,
diff --git a/src/gsm/gsup.c b/src/gsm/gsup.c
index 3b31d03c..3d2a8e2e 100644
--- a/src/gsm/gsup.c
+++ b/src/gsm/gsup.c
@@ -79,6 +79,10 @@ const struct value_string osmo_gsup_message_type_names[] = {
 	OSMO_VALUE_STRING(OSMO_GSUP_MSGT_READY_FOR_SM_ERROR),
 	OSMO_VALUE_STRING(OSMO_GSUP_MSGT_READY_FOR_SM_RESULT),
 
+	OSMO_VALUE_STRING(OSMO_GSUP_MSGT_CHECK_IMEI_REQUEST),
+	OSMO_VALUE_STRING(OSMO_GSUP_MSGT_CHECK_IMEI_ERROR),
+	OSMO_VALUE_STRING(OSMO_GSUP_MSGT_CHECK_IMEI_RESULT),
+
 	{ 0, NULL }
 };
 
@@ -116,6 +120,8 @@ int osmo_gsup_get_err_msg_type(enum osmo_gsup_message_type type_in)
 		return OSMO_GSUP_MSGT_MT_FORWARD_SM_ERROR;
 	case OSMO_GSUP_MSGT_READY_FOR_SM_REQUEST:
 		return OSMO_GSUP_MSGT_READY_FOR_SM_ERROR;
+	case OSMO_GSUP_MSGT_CHECK_IMEI_REQUEST:
+		return OSMO_GSUP_MSGT_CHECK_IMEI_ERROR;
 	default:
 		return -1;
 	}
@@ -487,6 +493,15 @@ int osmo_gsup_decode(const uint8_t *const_data, size_t data_len,
 			gsup_msg->sm_alert_rsn = *value;
 			break;
 
+		case OSMO_GSUP_IMEI_IE:
+			gsup_msg->imei_enc = value;
+			gsup_msg->imei_enc_len = value_len;
+			break;
+
+		case OSMO_GSUP_IMEI_RESULT_IE:
+			gsup_msg->imei_result = osmo_decode_big_endian(value, value_len) + 1;
+			break;
+
 		default:
 			LOGP(DLGSUP, LOGL_NOTICE,
 			     "GSUP IE type %d unknown\n", iei);
@@ -720,6 +735,14 @@ int osmo_gsup_encode(struct msgb *msg, const struct osmo_gsup_message *gsup_msg)
 				sizeof(u8), &u8);
 	}
 
+	if (gsup_msg->imei_enc)
+		msgb_tlv_put(msg, OSMO_GSUP_IMEI_IE, gsup_msg->imei_enc_len, gsup_msg->imei_enc);
+
+	if ((u8 = gsup_msg->imei_result)) {
+		u8 -= 1;
+		msgb_tlv_put(msg, OSMO_GSUP_IMEI_RESULT_IE, sizeof(u8), &u8);
+	}
+
 	return 0;
 }
 
diff --git a/tests/gsup/gsup_test.c b/tests/gsup/gsup_test.c
index 079a7031..f1945735 100644
--- a/tests/gsup/gsup_test.c
+++ b/tests/gsup/gsup_test.c
@@ -289,6 +289,33 @@ static void test_gsup_messages_dec_enc(void)
 			0x02, /* Memory Available (SMMA) */
 	};
 
+	static const uint8_t send_check_imei_req[] = {
+		0x30, /* OSMO_GSUP_MSGT_CHECK_IMEI_REQUEST */
+		TEST_IMSI_IE,
+
+		/* imei */
+		0x50, 0x09,
+			0x42, 0x42, 0x42, 0x42, 0x42, 0x42, 0x42, 0x42, 0x42,
+	};
+
+	static const uint8_t send_check_imei_err[] = {
+		0x31, /* OSMO_GSUP_MSGT_CHECK_IMEI_ERROR */
+		TEST_IMSI_IE,
+
+		/* cause */
+		0x02, 0x01,
+			0x60, /* GMM_CAUSE_INV_MAND_INFO */
+	};
+
+	static const uint8_t send_check_imei_res[] = {
+		0x32, /* OSMO_GSUP_MSGT_CHECK_IMEI_RESULT */
+		TEST_IMSI_IE,
+
+		/* imei_result */
+		0x51, 0x01,
+			0x00, /* OSMO_GSUP_IMEI_RESULT_ACK */
+	};
+
 	static const struct test {
 		char *name;
 		const uint8_t *data;
@@ -338,6 +365,12 @@ static void test_gsup_messages_dec_enc(void)
 			send_mo_mt_forward_sm_err, sizeof(send_mo_mt_forward_sm_err)},
 		{"ReadyForSM (MSC -> SMSC) Indication",
 			send_ready_for_sm_ind, sizeof(send_ready_for_sm_ind)},
+		{"Check IMEI Request",
+			send_check_imei_req, sizeof(send_check_imei_req)},
+		{"Check IMEI Error",
+			send_check_imei_err, sizeof(send_check_imei_err)},
+		{"Check IMEI Result",
+			send_check_imei_res, sizeof(send_check_imei_res)},
 	};
 
 	printf("Test GSUP message decoding/encoding\n");
diff --git a/tests/gsup/gsup_test.err b/tests/gsup/gsup_test.err
index 236c38a9..73b35fc5 100644
--- a/tests/gsup/gsup_test.err
+++ b/tests/gsup/gsup_test.err
@@ -64,6 +64,15 @@
   generated message: 2c 01 08 21 43 65 87 09 21 43 f5 46 01 02 
   original message:  2c 01 08 21 43 65 87 09 21 43 f5 46 01 02 
   IMSI:              123456789012345
+  generated message: 30 01 08 21 43 65 87 09 21 43 f5 50 09 42 42 42 42 42 42 42 42 42 
+  original message:  30 01 08 21 43 65 87 09 21 43 f5 50 09 42 42 42 42 42 42 42 42 42 
+  IMSI:              123456789012345
+  generated message: 31 01 08 21 43 65 87 09 21 43 f5 02 01 60 
+  original message:  31 01 08 21 43 65 87 09 21 43 f5 02 01 60 
+  IMSI:              123456789012345
+  generated message: 32 01 08 21 43 65 87 09 21 43 f5 51 01 00 
+  original message:  32 01 08 21 43 65 87 09 21 43 f5 51 01 00 
+  IMSI:              123456789012345
   message 0: tested 11 truncations, 11 parse failures
   message 1: tested 14 truncations, 13 parse failures
   message 2: tested 83 truncations, 81 parse failures
@@ -86,6 +95,9 @@
   message 19: tested 20 truncations, 18 parse failures
   message 20: tested 26 truncations, 22 parse failures
   message 21: tested 14 truncations, 13 parse failures
+  message 22: tested 22 truncations, 21 parse failures
+  message 23: tested 14 truncations, 13 parse failures
+  message 24: tested 14 truncations, 13 parse failures
 DLGSUP Stopping DLGSUP logging
   message 0: tested 2816 modifications, 510 parse failures
   message 1: tested 3584 modifications, 770 parse failures
@@ -109,3 +121,6 @@ DLGSUP Stopping DLGSUP logging
   message 19: tested 5120 modifications, 1031 parse failures
   message 20: tested 6656 modifications, 1546 parse failures
   message 21: tested 3584 modifications, 771 parse failures
+  message 22: tested 5632 modifications, 771 parse failures
+  message 23: tested 3584 modifications, 770 parse failures
+  message 24: tested 3584 modifications, 771 parse failures
diff --git a/tests/gsup/gsup_test.ok b/tests/gsup/gsup_test.ok
index 36e35c8b..70f723c0 100644
--- a/tests/gsup/gsup_test.ok
+++ b/tests/gsup/gsup_test.ok
@@ -43,4 +43,10 @@ Test GSUP message decoding/encoding
           MO-/MT-ForwardSM Error OK
   Testing ReadyForSM (MSC -> SMSC) Indication
           ReadyForSM (MSC -> SMSC) Indication OK
+  Testing Check IMEI Request
+          Check IMEI Request OK
+  Testing Check IMEI Error
+          Check IMEI Error OK
+  Testing Check IMEI Result
+          Check IMEI Result OK
 Done.