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, 45 insertions, 10 deletions

diff --git a/openbsc/src/osmo-bsc_nat/bsc_nat.c b/openbsc/src/osmo-bsc_nat/bsc_nat.c
index 2146da1c4..ba273417a 100644
--- a/openbsc/src/osmo-bsc_nat/bsc_nat.c
+++ b/openbsc/src/osmo-bsc_nat/bsc_nat.c
@@ -549,6 +549,50 @@ send_refuse:
 	bsc_write(bsc, refuse, IPAC_PROTO_SCCP);
 }
 
+static void bsc_nat_send_paging(struct bsc_connection *bsc, struct msgb *msg)
+{
+	if (bsc->cfg->forbid_paging) {
+		LOGP(DNAT, LOGL_DEBUG, "Paging forbidden for BTS: %d\n", bsc->cfg->nr);
+		return;
+	}
+
+	bsc_send_data(bsc, msg->l2h, msgb_l2len(msg), IPAC_PROTO_SCCP);
+}
+
+static void bsc_nat_handle_paging(struct bsc_nat *nat, struct msgb *msg)
+{
+	struct bsc_connection *bsc;
+	const uint8_t *paging_start;
+	int paging_length, i;
+
+	if (bsc_nat_find_paging(msg, &paging_start, &paging_length) != 0) {
+		LOGP(DNAT, LOGL_ERROR, "Could not parse paging message.\n");
+		return;
+	}
+
+	/* This is quite expensive now */
+	for (i = 0; i < paging_length; i += 2) {
+		unsigned int _lac = ntohs(*(unsigned int *) &paging_start[i]);
+		unsigned int paged = 0;
+		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;
+			bsc_nat_send_paging(bsc, msg);
+			paged += 1;
+		}
+
+		/* highlight a possible config issue */
+		if (paged == 0)
+			LOGP(DNAT, LOGL_ERROR, "No BSC for LAC %d/0x%d\n", _lac, _lac);
+
+	}
+}
+
+
 /*
  * Update the auth status. This can be either a CIPHER MODE COMAMND or
  * a CM Serivce Accept. Maybe also LU Accept or such in the future.
@@ -677,16 +721,7 @@ send_to_all:
 	 * message and then send it to the authenticated messages...
 	 */
 	if (parsed->ipa_proto == IPAC_PROTO_SCCP && parsed->gsm_type == BSS_MAP_MSG_PAGING) {
-		int lac;
-		bsc = bsc_nat_find_bsc(nat, msg, &lac);
-		if (bsc && bsc->cfg->forbid_paging)
-			LOGP(DNAT, LOGL_DEBUG, "Paging forbidden for BTS: %d\n", bsc->cfg->nr);
-		else if (bsc)
-			bsc_send_data(bsc, msg->l2h, msgb_l2len(msg), parsed->ipa_proto);
-		else if (lac != -1)
-			LOGP(DNAT, LOGL_ERROR, "Could not determine BSC for paging on lac: %d/0x%x\n",
-			     lac, lac);
-
+		bsc_nat_handle_paging(nat, msg);
 		goto exit;
 	}
 	/* currently send this to every BSC connected */