lapd_test: add a test checking SAPI0/SAPI3 prioritization
Recently we've encountered a situation where during MT SMS delivery,
the func=SABM for SAPI=3 was sent on Downlink *before* the BTS
replied with the func=UA for SAPI=0 (contetion resolution procedure,
where we echo the (RR) Paging Response back to the MS).
This change adds a unit test reprodicing the problem.
Change-Id: Ied0f8bb683de8e37bcfa984c2877aa1cec1c0b4b
Related: SYS#5047, OS#4731
diff --git a/tests/lapd/lapd_test.c b/tests/lapd/lapd_test.c
index 3ea2706..48851f4 100644
--- a/tests/lapd/lapd_test.c
+++ b/tests/lapd/lapd_test.c
@@ -73,6 +73,17 @@
0x00, 0x00, 0x80, 0x2b, 0x2b, 0x2b, 0x2b
};
+static const uint8_t pr[] = {
+ 0x06, 0x27, 0x07, 0x03, 0x50, 0x58, 0x92, 0x05,
+ 0xf4, 0x44, 0x59, 0xba, 0x63,
+};
+
+static const uint8_t ua_pr[] = {
+ 0x01, 0x73, 0x35, 0x06, 0x27, 0x07, 0x03, 0x50,
+ 0x58, 0x92, 0x05, 0xf4, 0x44, 0x59, 0xba, 0x63,
+ 0x2b, 0x2b, 0x2b, 0x2b, 0x2b, 0x2b, 0x2b,
+};
+
static const uint8_t mm[] = {
0x00, 0x0c, 0x00, 0x03, 0x01, 0x01, 0x20, 0x02,
0x00, 0x0b, 0x00, 0x03, 0x05, 0x04, 0x0d
@@ -757,6 +768,63 @@
lapdm_channel_exit(&bts_to_ms_channel);
}
+static void test_lapdm_sapi_prio(void)
+{
+ static const uint8_t dl_sabm[] = { 0x0f, 0x3f, 0x01 };
+ struct osmo_phsap_prim pp1, pp2;
+ struct lapdm_channel lc = { };
+ struct msgb *msg;
+ int rc;
+
+ printf("\n=== I test SAPI0/SAPI3 prioritization ===\n\n");
+
+ /* BTS to MS in polling mode */
+ lapdm_channel_init(&lc, LAPDM_MODE_BTS);
+ lapdm_channel_set_flags(&lc, LAPDM_ENT_F_POLLING_ONLY);
+ lapdm_channel_set_l1(&lc, NULL, NULL);
+ lapdm_channel_set_l3(&lc, bts_to_ms_dummy_tx_cb, NULL);
+
+ /* MS establishes a SAPI=0 link by sending func=SABM on SDCCH */
+ printf("MS is establishing a SAPI=0 link\n");
+ send_sabm(&lc, 0, pr, sizeof(pr));
+
+ /* BTS establishes a SAPI=3 link by sending func=SABM on SDCCH */
+ msg = create_est_req(est_req_sdcch_sapi3, sizeof(est_req_sdcch_sapi3));
+ printf("BTS is establishing a SAPI=3 link\n");
+ rc = lapdm_rslms_recvmsg(msg, &lc);
+ OSMO_ASSERT(rc == 0);
+
+ /* Make sure that we get func=UA on SDCCH from the BTS first */
+ rc = dequeue_prim(&lc.lapdm_dcch, &pp1, "DCCH");
+ CHECK_RC(rc);
+
+ /* Contention resolution is completed, we should get func=SABM now */
+ rc = dequeue_prim(&lc.lapdm_dcch, &pp2, "DCCH");
+ CHECK_RC(rc);
+
+ /* Check the actual message payload */
+ rc = memcmp(pp1.oph.msg->l2h, ua_pr, sizeof(ua_pr));
+ printf("Checking the func=UA message: %s\n", rc == 0 ? "OK" : "FAIL");
+ rc = memcmp(pp2.oph.msg->l2h, dl_sabm, sizeof(dl_sabm));
+ printf("Checking the func=SABM message: %s\n", rc == 0 ? "OK" : "FAIL");
+
+ msgb_free(pp1.oph.msg);
+ msgb_free(pp2.oph.msg);
+
+ /* Make sure that the queues are empty now */
+ printf("\nChecking whether the DCCH/SACCH queues are empty\n");
+ rc = dequeue_prim(&lc.lapdm_dcch, &pp1, "DCCH");
+ OSMO_ASSERT(rc < 0);
+ rc = dequeue_prim(&lc.lapdm_dcch, &pp2, "SACCH");
+ OSMO_ASSERT(rc < 0);
+
+ /* Clean up */
+ lapdm_channel_exit(&lc);
+
+ /* Check if exit is idempotent */
+ lapdm_channel_exit(&lc);
+}
+
int main(int argc, char **argv)
{
void *ctx = talloc_named_const(NULL, 0, "lapd_test");
@@ -773,6 +841,7 @@
test_lapdm_contention_resolution();
test_lapdm_establishment();
test_lapdm_desync();
+ test_lapdm_sapi_prio();
printf("Success.\n");