static void bt_mesh_net_relay()

in nimble/host/mesh/src/net.c [657:738]

• 53 lines of code
• 16 McCabe index (conditional complexity)

static void bt_mesh_net_relay(struct os_mbuf *sbuf,
			      struct bt_mesh_net_rx *rx)
{
	const struct bt_mesh_net_cred *cred;
	struct os_mbuf *buf;
	uint8_t transmit;

	if (rx->ctx.recv_ttl <= 1U) {
		return;
	}

	if (rx->net_if == BT_MESH_NET_IF_ADV &&
	    !rx->friend_cred &&
	    bt_mesh_relay_get() != BT_MESH_RELAY_ENABLED &&
	    bt_mesh_gatt_proxy_get() != BT_MESH_GATT_PROXY_ENABLED) {
		return;
	}

	BT_DBG("TTL %u CTL %u dst 0x%04x", rx->ctx.recv_ttl, rx->ctl,
	       rx->ctx.recv_dst);

	/* The Relay Retransmit state is only applied to adv-adv relaying.
	 * Anything else (like GATT to adv, or locally originated packets)
	 * use the Network Transmit state.
	 */
	if (rx->net_if == BT_MESH_NET_IF_ADV && !rx->friend_cred) {
		transmit = bt_mesh_relay_retransmit_get();
	} else {
		transmit = bt_mesh_net_transmit_get();
	}

	buf = bt_mesh_adv_create(BT_MESH_ADV_DATA, transmit, K_NO_WAIT);
	if (!buf) {
		BT_ERR("Out of relay buffers");
		return;
	}

	/* Leave CTL bit intact */
	sbuf->om_data[1] &= 0x80;
	sbuf->om_data[1] |= rx->ctx.recv_ttl - 1U;

	net_buf_add_mem(buf, sbuf->om_data, sbuf->om_len);

	cred = &rx->sub->keys[SUBNET_KEY_TX_IDX(rx->sub)].msg;

	BT_DBG("Relaying packet. TTL is now %u", TTL(buf->om_data));

	/* Update NID if RX or RX was with friend credentials */
	if (rx->friend_cred) {
		buf->om_data[0] &= 0x80; /* Clear everything except IVI */
		buf->om_data[0] |= cred->nid;
	}

	/* We re-encrypt and obfuscate using the received IVI rather than
	 * the normal TX IVI (which may be different) since the transport
	 * layer nonce includes the IVI.
	 */
	if (net_encrypt(buf, cred, BT_MESH_NET_IVI_RX(rx), false)) {
		BT_ERR("Re-encrypting failed");
		goto done;
	}

	BT_DBG("encoded %u bytes: %s", buf->om_len,
	       bt_hex(buf->om_data, buf->om_len));

	/* When the Friend node relays message for lpn, the message will be
	 * retransmitted using the managed flooding security credentials and
	 * the Network PDU shall be retransmitted to all network interfaces.
	 */
	if (IS_ENABLED(CONFIG_BT_MESH_GATT_PROXY) &&
	    (rx->friend_cred ||
	     bt_mesh_gatt_proxy_get() == BT_MESH_GATT_PROXY_ENABLED)) {
		bt_mesh_proxy_relay(buf, rx->ctx.recv_dst);
	}

	if (relay_to_adv(rx->net_if) || rx->friend_cred) {
		bt_mesh_adv_send(buf, NULL, NULL);
	}

done:
	net_buf_unref(buf);
}