tbf/test: Add test for DL LLC packet loss

Currently LLC frames are lost or even reordered when the TBF has be
established via the AGCH and the procedure fails for some reason.

This test tries to reproduce this behaviour by throwing away the
first TBF while calling the handle() method several times. The
results of create_dl_acked_block() are checked against expected
values (this is currently party disabled because the bug still
persists).

Ticket: #1759
Sponsored-by: On-Waves ehf

1 files changed, 70 insertions, 0 deletions

diff --git a/tests/tbf/TbfTest.cpp b/tests/tbf/TbfTest.cpp
index c7393f4a..5bc492ec 100644
--- a/tests/tbf/TbfTest.cpp
+++ b/tests/tbf/TbfTest.cpp
@@ -427,6 +427,75 @@ static void test_tbf_exhaustion()
 	gprs_bssgp_destroy();
 }
 
+static void test_tbf_dl_llc_loss()
+{
+	BTS the_bts;
+	gprs_rlcmac_bts *bts;
+	uint8_t ts_no = 4;
+	uint8_t ms_class = 45;
+	int rc = 0;
+	uint32_t tlli = 0xc0123456;
+	const char *imsi = "001001000123456";
+	unsigned delay_csec = 1000;
+	GprsMs *ms;
+
+	uint8_t buf[19];
+
+	printf("=== start %s ===\n", __func__);
+
+	bts = the_bts.bts_data();
+	setup_bts(&the_bts, ts_no);
+	bts->ms_idle_sec = 10; /* keep the MS object */
+
+	gprs_bssgp_create_and_connect(bts, 33001, 0, 33001,
+		1234, 1234, 1234, 1, 1, 0, 0, 0);
+
+	/* Handle LLC frame 1 */
+	memset(buf, 1, sizeof(buf));
+	rc = gprs_rlcmac_dl_tbf::handle(bts, tlli, 0, imsi, ms_class,
+		delay_csec, buf, sizeof(buf));
+	OSMO_ASSERT(rc >= 0);
+
+	ms = the_bts.ms_store().get_ms(0, 0, imsi);
+	OSMO_ASSERT(ms != NULL);
+	OSMO_ASSERT(ms->dl_tbf() != NULL);
+
+	/* Handle LLC frame 2 */
+	memset(buf, 2, sizeof(buf));
+	rc = gprs_rlcmac_dl_tbf::handle(bts, tlli, 0, imsi, ms_class,
+		delay_csec, buf, sizeof(buf));
+	OSMO_ASSERT(rc >= 0);
+
+	/* TBF establishment fails (timeout) */
+	tbf_free(ms->dl_tbf());
+
+	/* Handle LLC frame 3 */
+	memset(buf, 3, sizeof(buf));
+	rc = gprs_rlcmac_dl_tbf::handle(bts, tlli, 0, imsi, ms_class,
+		delay_csec, buf, sizeof(buf));
+	OSMO_ASSERT(rc >= 0);
+
+	OSMO_ASSERT(ms->dl_tbf() != NULL);
+
+	/* Get first BSN */
+	struct msgb *msg;
+	int fn = 0;
+	uint8_t expected_data = 1;
+
+	while (ms->dl_tbf()->have_data()) {
+		msg = ms->dl_tbf()->create_dl_acked_block(fn += 4, 7);
+		fprintf(stderr, "MSG = %s\n", msgb_hexdump(msg));
+		OSMO_ASSERT(msgb_length(msg) == 23);
+		/* OSMO_ASSERT(msgb_data(msg)[10] == expected_data); */
+		expected_data += 1;
+	}
+	/* OSMO_ASSERT(expected_data-1 == 3); */
+
+	printf("=== end %s ===\n", __func__);
+
+	gprs_bssgp_destroy();
+}
+
 static void test_tbf_single_phase()
 {
 	BTS the_bts;
@@ -605,6 +674,7 @@ int main(int argc, char **argv)
 	test_tbf_delayed_release();
 	test_tbf_imsi();
 	test_tbf_exhaustion();
+	test_tbf_dl_llc_loss();
 	test_tbf_single_phase();
 	test_tbf_two_phase();