sgsn: Select GGSN based on APN

Currently the APN IE in the Activate PDP Contex Request and the PDP
data that is stored with the subscriber is ignored completely.

This commit adds the sgsn_mm_ctx_find_ggsn_ctx that checks the APN IE
against the subscriber's PDP data entries if both are present. If
there is no match, the request is rejected.

If an APN IE has not been included but PDP data entries are present,
the function checks all of these entries against the static 'apn'
configuration to find a suitable entry.

If an APN has not been determined so far and any APN is allowed, the
configuration is checked with an empty APN string, to allow for
default configurations based on the IMSI prefix only.

If nothing of this succeeded but the request wasn't rejected either,
and there is no 'apn' configuration at all or if any APN is allowed
but a default configuration ist not present, the GGSN with id 0 is
used (if present).

Otherwise the request is rejected ('missing APN').

Ticket: OW#1334
Sponsored-by: On-Waves ehf

2 files changed, 136 insertions, 0 deletions

diff --git a/openbsc/tests/sgsn/sgsn_test.c b/openbsc/tests/sgsn/sgsn_test.c
index 5fa33a266..d55a0fc6a 100644
--- a/openbsc/tests/sgsn/sgsn_test.c
+++ b/openbsc/tests/sgsn/sgsn_test.c
@@ -26,6 +26,7 @@
 #include <openbsc/gsm_subscriber.h>
 #include <openbsc/gprs_gsup_messages.h>
 #include <openbsc/gprs_gsup_client.h>
+#include <openbsc/gprs_utils.h>
 
 #include <osmocom/gprs/gprs_bssgp.h>
 
@@ -1876,6 +1877,139 @@ static void test_apn_matching(void)
 	OSMO_ASSERT(actx == NULL);
 }
 
+struct sgsn_subscriber_pdp_data* sgsn_subscriber_pdp_data_alloc(
+	struct sgsn_subscriber_data *sdata);
+
+static void test_ggsn_selection(void)
+{
+	struct apn_ctx *actxs[4];
+	struct sgsn_ggsn_ctx *ggc, *ggcs[3];
+	struct gsm_subscriber *s1;
+	const char *imsi1 = "1234567890";
+	struct sgsn_mm_ctx *ctx;
+	struct gprs_ra_id raid = { 0, };
+	uint32_t local_tlli = 0xffeeddcc;
+	enum gsm48_gsm_cause gsm_cause;
+	struct tlv_parsed tp;
+	uint8_t apn_enc[GSM_APN_LENGTH + 10];
+	struct sgsn_subscriber_pdp_data *pdp_data;
+
+	printf("Testing GGSN selection\n");
+
+	gprs_gsup_client_send_cb = my_gprs_gsup_client_send_dummy;
+
+	/* Check for emptiness */
+	OSMO_ASSERT(gprs_subscr_get_by_imsi(imsi1) == NULL);
+
+	/* Create a context */
+	OSMO_ASSERT(count(gprs_llme_list()) == 0);
+	ctx = alloc_mm_ctx(local_tlli, &raid);
+	strncpy(ctx->imsi, imsi1, sizeof(ctx->imsi) - 1);
+
+	/* Allocate and attach a subscriber */
+	s1 = gprs_subscr_get_or_create_by_mmctx(ctx);
+	assert_subscr(s1, imsi1);
+
+	tp.lv[GSM48_IE_GSM_APN].len = 0;
+	tp.lv[GSM48_IE_GSM_APN].val = apn_enc;
+
+	/* TODO: Add PDP info entries to s1 */
+
+	ggcs[0] = sgsn_ggsn_ctx_find_alloc(0);
+	ggcs[1] = sgsn_ggsn_ctx_find_alloc(1);
+	ggcs[2] = sgsn_ggsn_ctx_find_alloc(2);
+
+	actxs[0] = sgsn_apn_ctx_find_alloc("test.apn", "123456");
+	actxs[0]->ggsn = ggcs[0];
+	actxs[1] = sgsn_apn_ctx_find_alloc("*.apn", "123456");
+	actxs[1]->ggsn = ggcs[1];
+	actxs[2] = sgsn_apn_ctx_find_alloc("*", "456789");
+	actxs[2]->ggsn = ggcs[2];
+
+	/* Resolve GGSNs */
+
+	tp.lv[GSM48_IE_GSM_APN].len =
+		gprs_str_to_apn(apn_enc, sizeof(apn_enc), "Test.Apn");
+
+	ggc = sgsn_mm_ctx_find_ggsn_ctx(ctx, &tp, &gsm_cause);
+	OSMO_ASSERT(ggc != NULL);
+	OSMO_ASSERT(ggc->id == 0);
+
+	tp.lv[GSM48_IE_GSM_APN].len =
+		gprs_str_to_apn(apn_enc, sizeof(apn_enc), "Other.Apn");
+
+	ggc = sgsn_mm_ctx_find_ggsn_ctx(ctx, &tp, &gsm_cause);
+	OSMO_ASSERT(ggc != NULL);
+	OSMO_ASSERT(ggc->id == 1);
+
+	tp.lv[GSM48_IE_GSM_APN].len = 0;
+	tp.lv[GSM48_IE_GSM_APN].val = NULL;
+
+	ggc = sgsn_mm_ctx_find_ggsn_ctx(ctx, &tp, &gsm_cause);
+	OSMO_ASSERT(ggc != NULL);
+	OSMO_ASSERT(ggc->id == 0);
+
+	actxs[3] = sgsn_apn_ctx_find_alloc("*", "123456");
+	actxs[3]->ggsn = ggcs[2];
+	ggc = sgsn_mm_ctx_find_ggsn_ctx(ctx, &tp, &gsm_cause);
+	OSMO_ASSERT(ggc != NULL);
+	OSMO_ASSERT(ggc->id == 2);
+
+	sgsn_apn_ctx_free(actxs[3]);
+	tp.lv[GSM48_IE_GSM_APN].val = apn_enc;
+
+	tp.lv[GSM48_IE_GSM_APN].len =
+		gprs_str_to_apn(apn_enc, sizeof(apn_enc), "Foo.Bar");
+
+	ggc = sgsn_mm_ctx_find_ggsn_ctx(ctx, &tp, &gsm_cause);
+	OSMO_ASSERT(ggc == NULL);
+	OSMO_ASSERT(gsm_cause == GSM_CAUSE_MISSING_APN);
+
+	tp.lv[GSM48_IE_GSM_APN].len = sizeof(apn_enc);
+	ggc = sgsn_mm_ctx_find_ggsn_ctx(ctx, &tp, &gsm_cause);
+	OSMO_ASSERT(ggc == NULL);
+	OSMO_ASSERT(gsm_cause == GSM_CAUSE_INV_MAND_INFO);
+
+	/* Add PDP data entry to subscriber */
+
+	pdp_data = sgsn_subscriber_pdp_data_alloc(s1->sgsn_data);
+	pdp_data->context_id = 1;
+
+	pdp_data->pdp_type = 0x0121;
+	strncpy(pdp_data->apn_str, "Test.Apn", sizeof(pdp_data->apn_str)-1);
+
+	tp.lv[GSM48_IE_GSM_APN].len =
+		gprs_str_to_apn(apn_enc, sizeof(apn_enc), "Test.Apn");
+
+	ggc = sgsn_mm_ctx_find_ggsn_ctx(ctx, &tp, &gsm_cause);
+	OSMO_ASSERT(ggc != NULL);
+	OSMO_ASSERT(ggc->id == 0);
+
+	tp.lv[GSM48_IE_GSM_APN].len =
+		gprs_str_to_apn(apn_enc, sizeof(apn_enc), "Other.Apn");
+
+	ggc = sgsn_mm_ctx_find_ggsn_ctx(ctx, &tp, &gsm_cause);
+	OSMO_ASSERT(ggc == NULL);
+	OSMO_ASSERT(gsm_cause == GSM_CAUSE_REQ_SERV_OPT_NOTSUB);
+
+	/* Cleanup */
+
+	subscr_put(s1);
+	sgsn_mm_ctx_cleanup_free(ctx);
+
+	assert_no_subscrs();
+
+	sgsn_apn_ctx_free(actxs[0]);
+	sgsn_apn_ctx_free(actxs[1]);
+	sgsn_apn_ctx_free(actxs[2]);
+
+	sgsn_ggsn_ctx_free(ggcs[0]);
+	sgsn_ggsn_ctx_free(ggcs[1]);
+	sgsn_ggsn_ctx_free(ggcs[2]);
+
+	gprs_gsup_client_send_cb = __real_gprs_gsup_client_send;
+}
+
 static struct log_info_cat gprs_categories[] = {
 	[DMM] = {
 		.name = "DMM",
@@ -1964,6 +2098,7 @@ int main(int argc, char **argv)
 	test_gmm_cancel();
 	test_gmm_ptmsi_allocation();
 	test_apn_matching();
+	test_ggsn_selection();
 	printf("Done\n");
 
 	talloc_report_full(osmo_sgsn_ctx, stderr);
diff --git a/openbsc/tests/sgsn/sgsn_test.ok b/openbsc/tests/sgsn/sgsn_test.ok
index 9f14721af..bef8c9897 100644
--- a/openbsc/tests/sgsn/sgsn_test.ok
+++ b/openbsc/tests/sgsn/sgsn_test.ok
@@ -27,4 +27,5 @@ Testing P-TMSI allocation
   - Repeated Attach Request
   - Repeated RA Update Request
 Testing APN matching
+Testing GGSN selection
 Done