nat: Implement clearing of TP-SRR flags from TPDUs

Match IMSI and destination address against a set of entries, if it
is matching the header will be modified and no sender report will be
requested. Change the test case to request the sender report and then
verify that this bit is reset to 0.

1 files changed, 39 insertions, 4 deletions

diff --git a/openbsc/src/osmo-bsc_nat/bsc_nat_utils.c b/openbsc/src/osmo-bsc_nat/bsc_nat_utils.c
index 1d67c350c..3d0c30d2f 100644
--- a/openbsc/src/osmo-bsc_nat/bsc_nat_utils.c
+++ b/openbsc/src/osmo-bsc_nat/bsc_nat_utils.c
@@ -98,6 +98,7 @@ struct bsc_nat *bsc_nat_alloc(void)
 	INIT_LLIST_HEAD(&nat->num_rewr);
 	INIT_LLIST_HEAD(&nat->smsc_rewr);
 	INIT_LLIST_HEAD(&nat->tpdest_match);
+	INIT_LLIST_HEAD(&nat->sms_clear_tp_srr);
 
 	nat->stats.sccp.conn = osmo_counter_alloc("nat.sccp.conn");
 	nat->stats.sccp.calls = osmo_counter_alloc("nat.sccp.calls");
@@ -954,11 +955,35 @@ static char *find_new_smsc(struct bsc_nat *nat, void *ctx, const char *imsi,
 	return new_number;
 }
 
+/**
+ * Clear the TP-SRR from the TPDU header
+ */
+static uint8_t sms_new_tpdu_hdr(struct bsc_nat *nat, const char *imsi,
+				const char *dest_nr, uint8_t hdr)
+{
+	struct bsc_nat_num_rewr_entry *entry;
+
+	/* We will find a new number now */
+	llist_for_each_entry(entry, &nat->sms_clear_tp_srr, list) {
+		/* check the IMSI match */
+		if (regexec(&entry->msisdn_reg, imsi, 0, NULL, 0) != 0)
+			continue;
+		if (regexec(&entry->num_reg, dest_nr, 0, NULL, 0) != 0)
+			continue;
+
+		/* matched phone number and imsi */
+		return hdr & ~0x20;
+	}
+
+	return hdr;
+}
+
 static struct msgb *sms_create_new(uint8_t type, uint8_t ref,
 				   struct gsm48_hdr *old_hdr48,
 				   const uint8_t *orig_addr_ptr,
 				   int orig_addr_len, const char *new_number,
-				   const uint8_t *data_ptr, int data_len)
+				   const uint8_t *data_ptr, int data_len,
+				   uint8_t tpdu_first_byte)
 {
 	uint8_t new_addr_len;
 	struct gsm48_hdr *new_hdr48;
@@ -991,8 +1016,11 @@ static struct msgb *sms_create_new(uint8_t type, uint8_t ref,
 	new_addr[1] = 0x91;
 	msgb_lv_put(out, new_addr_len - 1, new_addr + 1);
 
-	msgb_lv_put(out, data_len, data_ptr);
+	/* patch in the new TPDU header value */
+	msgb_v_put(out, data_len);
+	msgb_tv_fixed_put(out, tpdu_first_byte, data_len - 1, &data_ptr[1]);
 
+	/* prepend GSM 04.08 header */
 	new_hdr48 = (struct gsm48_hdr *) msgb_push(out, sizeof(*new_hdr48) + 1);
 	memcpy(new_hdr48, old_hdr48, sizeof(*old_hdr48));
 	new_hdr48->data[0] = msgb_l3len(out);
@@ -1022,6 +1050,7 @@ static struct msgb *rewrite_sms(struct bsc_nat *nat, struct msgb *msg,
 	char *dest_nr;
 
 	char *new_number = NULL;
+	uint8_t tpdu_hdr;
 	struct msgb *out;
 
 	payload_len = len - sizeof(*hdr48);
@@ -1107,13 +1136,19 @@ static struct msgb *rewrite_sms(struct bsc_nat *nat, struct msgb *msg,
 		dest_nr = &_dest_nr[2];
 	}
 
+	/**
+	 * Call functions to rewrite the data
+	 */
+	tpdu_hdr = sms_new_tpdu_hdr(nat, imsi, dest_nr, data_ptr[0]);
 	new_number = find_new_smsc(nat, msg, imsi, smsc_addr, dest_nr);
-	if (!new_number)
+
+	if (tpdu_hdr == data_ptr[0] && !new_number)
 		return NULL;
 
 	out = sms_create_new(GSM411_MT_RP_DATA_MO, ref, hdr48,
 			orig_addr_ptr, orig_addr_len,
-			new_number, data_ptr, data_len);
+			new_number ? new_number : smsc_addr,
+			data_ptr, data_len, tpdu_hdr);
 	talloc_free(new_number);
 	return out;
 }