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

3 files changed, 132 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();
 
diff --git a/tests/tbf/TbfTest.err b/tests/tbf/TbfTest.err
index 65387241..fe1b6adf 100644
--- a/tests/tbf/TbfTest.err
+++ b/tests/tbf/TbfTest.err
@@ -1108,6 +1108,66 @@ Searching for first unallocated TFI: TRX=0 first TS=4
 No TFI available.
 No PDCH resource
 BSSGP (BVCI=1234) Tx LLC-DISCARDED TLLI=0xc0000020, FRAMES=1, OCTETS=256
+Searching for first unallocated TFI: TRX=0 first TS=4
+ Found TFI=0.
+********** TBF starts here **********
+Allocating DL TBF: TFI=0 TRX=0 MS_CLASS=45
+Slot Allocation (Algorithm A) for class 45
+- Skipping TS 0, because not enabled
+- Skipping TS 1, because not enabled
+- Skipping TS 2, because not enabled
+- Skipping TS 3, because not enabled
+- Assign downlink TS=4
+- Setting Control TS 4
+Creating MS object, TLLI = 0x00000000
+The MS object cannot fully confirm an unexpected TLLI: 0xc0123456, partly confirmed
+Modifying MS object, TLLI = 0xc0123456, MS class 0 -> 45
+Attaching TBF to MS object, TLLI = 0xc0123456, TBF = TBF(TFI=0 TLLI=0xc0123456 DIR=DL STATE=NULL)
+TBF(TFI=0 TLLI=0xc0123456 DIR=DL STATE=NULL) [DOWNLINK] START
+Modifying MS object, TLLI = 0xc0123456, IMSI '' -> '001001000123456'
+Send dowlink assignment for TBF(TFI=0 TLLI=0xc0123456 DIR=DL STATE=NULL) on PCH, no TBF exist (IMSI=001001000123456)
+TBF(TFI=0 TLLI=0xc0123456 DIR=DL STATE=NULL) changes state from NULL to ASSIGN
+TX: START TBF(TFI=0 TLLI=0xc0123456 DIR=DL STATE=ASSIGN) Immediate Assignment Downlink (PCH)
+Sending data request: trx=0 ts=0 sapi=3 arfcn=0 fn=0 block=0 data=34 35 36 2d 06 3f 30 0c 00 00 7d 80 00 00 00 dc 01 23 45 68 00 23 2b 2b 2b 2b 
+TBF(TFI=0 TLLI=0xc0123456 DIR=DL STATE=ASSIGN) append
+TBF(TFI=0 TLLI=0xc0123456 DIR=DL STATE=ASSIGN) free
+Detaching TBF from MS object, TLLI = 0xc0123456, TBF = TBF(TFI=0 TLLI=0xc0123456 DIR=DL STATE=ASSIGN)
+********** TBF ends here **********
+Searching for first unallocated TFI: TRX=0 first TS=4
+ Found TFI=0.
+********** TBF starts here **********
+Allocating DL TBF: TFI=0 TRX=0 MS_CLASS=45
+Slot Allocation (Algorithm A) for class 45
+- Skipping TS 0, because not enabled
+- Skipping TS 1, because not enabled
+- Skipping TS 2, because not enabled
+- Skipping TS 3, because not enabled
+- Assign downlink TS=4
+- Setting Control TS 4
+Attaching TBF to MS object, TLLI = 0xc0123456, TBF = TBF(TFI=0 TLLI=0xc0123456 DIR=DL STATE=NULL)
+TBF(TFI=0 TLLI=0xc0123456 DIR=DL STATE=NULL) [DOWNLINK] START
+Send dowlink assignment for TBF(TFI=0 TLLI=0xc0123456 DIR=DL STATE=NULL) on PCH, no TBF exist (IMSI=001001000123456)
+TBF(TFI=0 TLLI=0xc0123456 DIR=DL STATE=NULL) changes state from NULL to ASSIGN
+TX: START TBF(TFI=0 TLLI=0xc0123456 DIR=DL STATE=ASSIGN) Immediate Assignment Downlink (PCH)
+Sending data request: trx=0 ts=0 sapi=3 arfcn=0 fn=0 block=0 data=34 35 36 2d 06 3f 30 0c 00 00 7d 80 00 00 00 dc 01 23 45 68 00 23 2b 2b 2b 2b 
+TBF(TFI=0 TLLI=0xc0123456 DIR=DL STATE=ASSIGN) downlink (V(A)==0 .. V(S)==0)
+- Sending new block at BSN 0, CS=1
+-- Chunk with length 19 is less than remaining space (20): add length header to to delimit LLC frame
+Complete DL frame for TBF(TFI=0 TLLI=0xc0123456 DIR=DL STATE=ASSIGN)len=19
+- Dequeue next LLC for TBF(TFI=0 TLLI=0xc0123456 DIR=DL STATE=ASSIGN) (len=19)
+-- No space left, so we are done.
+data block: 07 00 00 4d 03 03 03 03 03 03 03 03 03 03 03 03 03 03 03 03 03 03 03 
+MSG = 07 00 00 4d 03 03 03 03 03 03 03 03 03 03 03 03 03 03 03 03 03 03 03 
+TBF(TFI=0 TLLI=0xc0123456 DIR=DL STATE=ASSIGN) downlink (V(A)==0 .. V(S)==1)
+- Sending new block at BSN 1, CS=1
+-- Chunk with length 19 is less than remaining space (20): add length header to to delimit LLC frame
+Complete DL frame for TBF(TFI=0 TLLI=0xc0123456 DIR=DL STATE=ASSIGN)len=19
+-- Final block, so we done.
+TBF(TFI=0 TLLI=0xc0123456 DIR=DL STATE=ASSIGN) changes state from ASSIGN to FINISHED
+data block: 07 01 02 4d 02 02 02 02 02 02 02 02 02 02 02 02 02 02 02 02 02 02 02 
+- Scheduling Ack/Nack polling, because is was requested explicitly (e.g. first final block sent).
+Polling cannot be sheduled in this TS 7, waiting for TS 4
+MSG = 07 01 02 4d 02 02 02 02 02 02 02 02 02 02 02 02 02 02 02 02 02 02 02 
 Searching for first unallocated TFI: TRX=0 first TS=7
  Found TFI=0.
 MS requests UL TBF on RACH, so we provide one:
diff --git a/tests/tbf/TbfTest.ok b/tests/tbf/TbfTest.ok
index 831a3dd3..8c2c0e77 100644
--- a/tests/tbf/TbfTest.ok
+++ b/tests/tbf/TbfTest.ok
@@ -4,6 +4,8 @@
 === end test_tbf_imsi ===
 === start test_tbf_exhaustion ===
 === end test_tbf_exhaustion ===
+=== start test_tbf_dl_llc_loss ===
+=== end test_tbf_dl_llc_loss ===
 === start test_tbf_single_phase ===
 === end test_tbf_single_phase ===
 === start test_tbf_two_phase ===