nat: Rewrite the paging handling.

The current code tries to find _one_ bsc for a paging message
and then continues. The new code will try to find multiple BSCs
for each LAC. This is done in preparation of having two BSCs
handle the same LAC. This code right now is O(m*n) but it will
be worse once paging groups are landed.
The code to test the function was reduced to just test the lac
lookup code as the other part can not be tested in a standalone
setup anymore.

1 files changed, 10 insertions, 26 deletions

diff --git a/openbsc/src/osmo-bsc_nat/bsc_nat_utils.c b/openbsc/src/osmo-bsc_nat/bsc_nat_utils.c
index 4d1afe2df..0a565a9b7 100644
--- a/openbsc/src/osmo-bsc_nat/bsc_nat_utils.c
+++ b/openbsc/src/osmo-bsc_nat/bsc_nat_utils.c
@@ -208,25 +208,23 @@ void sccp_connection_destroy(struct sccp_connections *conn)
 	talloc_free(conn);
 }
 
-struct bsc_connection *bsc_nat_find_bsc(struct bsc_nat *nat, struct msgb *msg, int *lac_out)
+
+int bsc_nat_find_paging(struct msgb *msg,
+			const uint8_t **out_data, int *out_leng)
 {
-	struct bsc_connection *bsc;
 	int data_length;
 	const uint8_t *data;
 	struct tlv_parsed tp;
-	int i = 0;
-
-	*lac_out = -1;
 
 	if (!msg->l3h || msgb_l3len(msg) < 3) {
 		LOGP(DNAT, LOGL_ERROR, "Paging message is too short.\n");
-		return NULL;
+		return -1;
 	}
 
 	tlv_parse(&tp, gsm0808_att_tlvdef(), msg->l3h + 3, msgb_l3len(msg) - 3, 0, 0);
 	if (!TLVP_PRESENT(&tp, GSM0808_IE_CELL_IDENTIFIER_LIST)) {
 		LOGP(DNAT, LOGL_ERROR, "No CellIdentifier List inside paging msg.\n");
-		return NULL;
+		return -2;
 	}
 
 	data_length = TLVP_LEN(&tp, GSM0808_IE_CELL_IDENTIFIER_LIST);
@@ -234,29 +232,15 @@ struct bsc_connection *bsc_nat_find_bsc(struct bsc_nat *nat, struct msgb *msg, i
 
 	/* No need to try a different BSS */
 	if (data[0] == CELL_IDENT_BSS) {
-		return NULL;
+		return -3;
 	} else if (data[0] != CELL_IDENT_LAC) {
 		LOGP(DNAT, LOGL_ERROR, "Unhandled cell ident discrminator: %d\n", data[0]);
-		return NULL;
+		return -4;
 	}
 
-	/* Currently we only handle one BSC */
-	for (i = 1; i < data_length - 1; i += 2) {
-		unsigned int _lac = ntohs(*(unsigned int *) &data[i]);
-		*lac_out = _lac;
-		llist_for_each_entry(bsc, &nat->bsc_connections, list_entry) {
-			if (!bsc->cfg)
-				continue;
-			if (!bsc->authenticated)
-				continue;
-			if (!bsc_config_handles_lac(bsc->cfg, _lac))
-				continue;
-
-			return bsc;
-		}
-	}
-
-	return NULL;
+	*out_data = &data[1];
+	*out_leng = data_length - 1;
+	return 0;
 }
 
 int bsc_write_mgcp(struct bsc_connection *bsc, const uint8_t *data, unsigned int length)