gb: Add bssgp_msgb_copy function

This function originates from openbsc/src/gprs but is just specific
to BSSGP/Gb on the same level like bssgp_msgb_alloc.

This commit puts the former gprs_msgb_copy function beside
bssgp_msgb_alloc.

Renamed function:

  gprs_msgb_copy -> bssgp_msgb_copy

Sponsored-by: On-Waves ehf

include/osmocom/gprs/gprs_bssgp.h

@@ -12,6 +12,7 @@
 /* gprs_bssgp_util.c */
 extern struct gprs_ns_inst *bssgp_nsi;
 struct msgb *bssgp_msgb_alloc(void);
+struct msgb *bssgp_msgb_copy(const struct msgb *msg, const char *name);
 const char *bssgp_cause_str(enum gprs_bssgp_cause cause);
 /* Transmit a simple response such as BLOCK/UNBLOCK/RESET ACK/NACK */
 int bssgp_tx_simple_bvci(uint8_t pdu_type, uint16_t nsei,

src/gb/gprs_bssgp_util.c

@@ -79,6 +79,36 @@ struct msgb *bssgp_msgb_alloc(void)
 	return msg;
 }
 
+struct msgb *bssgp_msgb_copy(const struct msgb *msg, const char *name)
+{
+	struct libgb_msgb_cb *old_cb, *new_cb;
+	struct msgb *new_msg;
+
+	new_msg = msgb_copy(msg, name);
+	if (!new_msg)
+		return NULL;
+
+	/* copy GB specific data */
+	old_cb = LIBGB_MSGB_CB(msg);
+	new_cb = LIBGB_MSGB_CB(new_msg);
+
+	if (old_cb->bssgph)
+		new_cb->bssgph = new_msg->_data + (old_cb->bssgph - msg->_data);
+	if (old_cb->llch)
+		new_cb->llch = new_msg->_data + (old_cb->llch - msg->_data);
+
+	/* bssgp_cell_id is a pointer into the old msgb, so we need to make
+	 * it a pointer into the new msgb */
+	if (old_cb->bssgp_cell_id)
+		new_cb->bssgp_cell_id = new_msg->_data +
+			(old_cb->bssgp_cell_id - msg->_data);
+	new_cb->nsei = old_cb->nsei;
+	new_cb->bvci = old_cb->bvci;
+	new_cb->tlli = old_cb->tlli;
+
+	return new_msg;
+}
+
 /* Transmit a simple response such as BLOCK/UNBLOCK/RESET ACK/NACK */
 int bssgp_tx_simple_bvci(uint8_t pdu_type, uint16_t nsei,
 			 uint16_t bvci, uint16_t ns_bvci)

src/gb/libosmogb.map

@@ -6,6 +6,7 @@ bssgp_fc_in;
 bssgp_fc_init;
 bssgp_fc_ms_init;
 bssgp_msgb_alloc;
+bssgp_msgb_copy;
 bssgp_msgb_tlli_put;
 bssgp_parse_cell_id;
 bssgp_tx_bvc_block;

tests/gb/gprs_bssgp_test.c

@@ -254,6 +254,39 @@ static void test_bssgp_flow_control_bvc(void)
 	printf("----- %s END\n", __func__);
 }
 
+static void test_bssgp_msgb_copy()
+{
+	struct msgb *msg, *msg2;
+	uint16_t bvci_be = htons(2);
+	uint8_t cause = BSSGP_CAUSE_OML_INTERV;
+
+	printf("----- %s START\n", __func__);
+	msg = bssgp_msgb_alloc();
+
+	msg->l3h = msgb_data(msg);
+	msgb_v_put(msg, BSSGP_PDUT_BVC_RESET);
+	msgb_tvlv_put(msg, BSSGP_IE_BVCI, sizeof(bvci_be), (uint8_t *)&bvci_be);
+	msgb_tvlv_put(msg, BSSGP_IE_CAUSE, sizeof(cause), &cause);
+
+	msgb_bvci(msg) = 0xbad;
+	msgb_nsei(msg) = 0xbee;
+
+	printf("Old msgb: %s\n", msgb_hexdump(msg));
+	msg2 = bssgp_msgb_copy(msg, "test");
+	printf("New msgb: %s\n", msgb_hexdump(msg2));
+
+	OSMO_ASSERT(msgb_bvci(msg2) == 0xbad);
+	OSMO_ASSERT(msgb_nsei(msg2) == 0xbee);
+	OSMO_ASSERT(msgb_l3(msg2) == msgb_data(msg2));
+	OSMO_ASSERT(msgb_bssgph(msg2) == msgb_data(msg2));
+	OSMO_ASSERT(msgb_bssgp_len(msg2) == msgb_length(msg2));
+
+	msgb_free(msg);
+	msgb_free(msg2);
+
+	printf("----- %s END\n", __func__);
+}
+
 static struct log_info info = {};
 
 int main(int argc, char **argv)
@@ -278,6 +311,7 @@ int main(int argc, char **argv)
 	test_bssgp_status();
 	test_bssgp_bad_reset();
 	test_bssgp_flow_control_bvc();
+	test_bssgp_msgb_copy();
 	printf("===== BSSGP test END\n\n");
 
 	exit(EXIT_SUCCESS);

tests/gb/gprs_bssgp_test.ok

@@ -13,5 +13,9 @@ BSSGP primitive, SAP 16777221, prim = 11, op = 2, msg = 41 07 81 05 04 82 04 d2
 Got message: 26 1e 81 2a 05 82 10 22 03 82 c0 40 01 82 08 11 1c 82 60 20 
 Got message: 26 1e 81 2a 05 82 10 22 03 82 c0 40 01 82 08 11 1c 82 60 20 3c 81 78 06 82 11 44 
 ----- test_bssgp_flow_control_bvc END
+----- test_bssgp_msgb_copy START
+Old msgb: [L3]> 22 04 82 00 02 07 81 08 
+New msgb: [L3]> 22 04 82 00 02 07 81 08 
+----- test_bssgp_msgb_copy END
 ===== BSSGP test END