EGPRS: add test case to show EPDAN BSN out of window bug

This patch adds a test case test_tbf_epdan_out_of_rx_window,
which expects a current bug with EPDAN for interpretation of the
bitmap explained in section 9.1.8.2.4 in 44.060 version 7.27.0
Release 7. The specification explains that a bit within the
uncompressed bitmap whose corresponding BSN is not within the
transmit window shall be ignored. But current PCU implementation
drops the EPDAN and does not update status of the BSN which are
inside the window. The test's expectation is corrected along with
the bug fix in a subsequent commit.

Related: OS#1789

Change-Id: If32b67f5c05707155281128b776a90a1e3d587b2

1 files changed, 102 insertions, 0 deletions

diff --git a/tests/tbf/TbfTest.cpp b/tests/tbf/TbfTest.cpp
index c716a558..8fb8bfe9 100644
--- a/tests/tbf/TbfTest.cpp
+++ b/tests/tbf/TbfTest.cpp
@@ -26,6 +26,7 @@
 #include "pcu_utils.h"
 #include "gprs_bssgp_pcu.h"
 #include "pcu_l1_if.h"
+#include "decoding.h"
 
 extern "C" {
 #include "pcu_vty.h"
@@ -2017,6 +2018,106 @@ static void test_tbf_li_decoding(void)
 	printf("=== end %s ===\n", __func__);
 }
 
+/*
+ * Test that a bit within the uncompressed bitmap whose BSN is not within
+ * the transmit window shall be ignored. See section 9.1.8.2.4 of 44.060
+ * version 7.27.0 Release 7.
+ */
+static void test_tbf_epdan_out_of_rx_window(void)
+{
+	BTS the_bts;
+	gprs_rlcmac_bts *bts;
+	uint8_t ms_class = 11;
+	uint8_t egprs_ms_class = 11;
+	uint8_t trx_no;
+	uint32_t tlli = 0xffeeddcc;
+	gprs_rlcmac_dl_tbf *dl_tbf;
+	int ts_no = 4;
+	bitvec *block;
+	uint8_t bits_data[RLC_EGPRS_MAX_WS/8];
+	bitvec bits;
+	int bsn_begin, bsn_end;
+	EGPRS_PD_AckNack_t *ack_nack;
+	RlcMacUplink_t ul_control_block;
+	gprs_rlc_v_b *prlcmvb;
+	gprs_rlc_dl_window *prlcdlwindow;
+
+	printf("=== start %s ===\n", __func__);
+
+	bts = the_bts.bts_data();
+
+	setup_bts(&the_bts, ts_no);
+	bts->dl_tbf_idle_msec = 200;
+	bts->egprs_enabled = 1;
+	/* ARQ II */
+	bts->dl_arq_type = EGPRS_ARQ2;
+
+	/*
+	 * Simulate a message captured during over-the-air testing,
+	 * where the following values were observed:
+	 * v_a = 1176, vs = 1288, max sns = 2048, window size = 480.
+	 */
+	uint8_t data_msg[23] = {0x40, 0x20, 0x0b, 0xff, 0xd1,
+				0x61, 0x00, 0x3e, 0x0e, 0x51, 0x9f,
+				0xff, 0xff, 0xfb, 0x80, 0x00, 0x00,
+				0x00, 0x00, 0x00, 0x00, 0x00, 0x00};
+
+	dl_tbf = create_dl_tbf(&the_bts, ms_class, egprs_ms_class, &trx_no);
+	dl_tbf->update_ms(tlli, GPRS_RLCMAC_DL_TBF);
+	prlcdlwindow = &dl_tbf->m_window;
+	prlcmvb = &prlcdlwindow->m_v_b;
+	prlcdlwindow->m_v_s = 1288;
+	prlcdlwindow->m_v_a = 1176;
+	prlcdlwindow->set_sns(2048);
+	prlcdlwindow->set_ws(480);
+	prlcmvb->mark_unacked(1176);
+	prlcmvb->mark_unacked(1177);
+	prlcmvb->mark_unacked(1286);
+	prlcmvb->mark_unacked(1287);
+
+	OSMO_ASSERT(dl_tbf->state_is(GPRS_RLCMAC_FLOW));
+
+	block = bitvec_alloc(23);
+
+	bitvec_unpack(block, data_msg);
+
+	bits.data = bits_data;
+	bits.data_len = sizeof(bits_data);
+	bits.cur_bit = 0;
+
+	decode_gsm_rlcmac_uplink(block, &ul_control_block);
+
+	ack_nack = &ul_control_block.u.Egprs_Packet_Downlink_Ack_Nack;
+
+	OSMO_ASSERT(prlcmvb->is_unacked(1176));
+	OSMO_ASSERT(prlcmvb->is_unacked(1177));
+	OSMO_ASSERT(prlcmvb->is_unacked(1286));
+	OSMO_ASSERT(prlcmvb->is_unacked(1287));
+
+	Decoding::decode_egprs_acknack_bits(
+		&ack_nack->EGPRS_AckNack.Desc, &bits,
+		&bsn_begin, &bsn_end, &dl_tbf->m_window);
+
+	dl_tbf->rcvd_dl_ack(
+		ack_nack->EGPRS_AckNack.Desc.FINAL_ACK_INDICATION,
+		bsn_begin, &bits);
+	/*
+	 * TODO:status of BSN:1176,1177 shall be invalid
+	 * status of BSN:1286,1287 shall be acked.
+	 * both condition fails because of existing bug. Which shall be
+	 * fixed in subsequent commit
+	 */
+
+	OSMO_ASSERT(prlcmvb->is_unacked(1176));
+	OSMO_ASSERT(prlcmvb->is_unacked(1177));
+	OSMO_ASSERT(prlcmvb->is_unacked(1286));
+	OSMO_ASSERT(prlcmvb->is_unacked(1287));
+
+	bitvec_free(block);
+	tbf_free(dl_tbf);
+	printf("=== end %s ===\n", __func__);
+}
+
 static void test_tbf_egprs_two_phase_spb(void)
 {
 	BTS the_bts;
@@ -2695,6 +2796,7 @@ int main(int argc, char **argv)
 	test_tbf_puan_urbb_len();
 	test_tbf_update_ws();
 	test_tbf_li_decoding();
+	test_tbf_epdan_out_of_rx_window();
 
 	if (getenv("TALLOC_REPORT_FULL"))
 		talloc_report_full(tall_pcu_ctx, stderr);