static int send_seg()

in nimble/host/mesh/src/transport.c [459:604]

• 111 lines of code
• 22 McCabe index (conditional complexity)

static int send_seg(struct bt_mesh_net_tx *net_tx, struct os_mbuf *sdu,
		    const struct bt_mesh_send_cb *cb, void *cb_data,
		    uint8_t *ctl_op)
{
	bool blocked = false;
	struct seg_tx *tx;
	uint8_t seg_o;
	int i;

	BT_DBG("src 0x%04x dst 0x%04x app_idx 0x%04x aszmic %u sdu_len %u",
	       net_tx->src, net_tx->ctx->addr, net_tx->ctx->app_idx,
	       net_tx->aszmic, sdu->om_len);

	for (tx = NULL, i = 0; i < ARRAY_SIZE(seg_tx); i++) {
		if (seg_tx[i].nack_count) {
			blocked |= seg_tx_blocks(&seg_tx[i], net_tx->src,
						 net_tx->ctx->addr);
		} else if (!tx) {
			tx = &seg_tx[i];
		}
	}

	if (!tx) {
		BT_ERR("No multi-segment message contexts available");
		return -EBUSY;
	}

	if (ctl_op) {
		tx->hdr = TRANS_CTL_HDR(*ctl_op, 1);
	} else if (BT_MESH_IS_DEV_KEY(net_tx->ctx->app_idx)) {
		tx->hdr = SEG_HDR(0, 0);
	} else {
		tx->hdr = SEG_HDR(1, net_tx->aid);
	}

	tx->src = net_tx->src;
	tx->dst = net_tx->ctx->addr;
	tx->seg_n = (sdu->om_len - 1) / seg_len(!!ctl_op);
	tx->seg_o = 0;
	tx->len = sdu->om_len;
	tx->nack_count = tx->seg_n + 1;
	tx->seq_auth = SEQ_AUTH(BT_MESH_NET_IVI_TX, bt_mesh.seq);
	tx->sub = net_tx->sub;
	tx->cb = cb;
	tx->cb_data = cb_data;
	tx->attempts = SEG_RETRANSMIT_ATTEMPTS;
	tx->seg_pending = 0;
	tx->xmit = net_tx->xmit;
	tx->aszmic = net_tx->aszmic;
	tx->friend_cred = net_tx->friend_cred;
	tx->blocked = blocked;
	tx->started = 0;
	tx->ctl = !!ctl_op;

	tx->ttl = net_tx->ctx->send_ttl;

	BT_DBG("SeqZero 0x%04x (segs: %u)",
	       (uint16_t)(tx->seq_auth & TRANS_SEQ_ZERO_MASK), tx->nack_count);

	if (IS_ENABLED(CONFIG_BT_MESH_FRIEND) &&
	    !bt_mesh_friend_queue_has_space(tx->sub->net_idx, net_tx->src,
					    tx->dst, &tx->seq_auth,
					    tx->seg_n + 1) &&
	    BT_MESH_ADDR_IS_UNICAST(tx->dst)) {
		BT_ERR("Not enough space in Friend Queue for %u segments",
		       tx->seg_n + 1);
		seg_tx_reset(tx);
		return -ENOBUFS;
	}

	for (seg_o = 0; sdu->om_len; seg_o++) {
		void *buf;
		uint16_t len;
		int err;

		err = k_mem_slab_alloc(&segs, &buf);
		if (err) {
			BT_ERR("Out of segment buffers");
			seg_tx_reset(tx);
			return -ENOBUFS;
		}

		len = MIN(sdu->om_len, seg_len(!!ctl_op));
		memcpy(buf, net_buf_simple_pull_mem(sdu, len), len);
		BT_DBG("seg %u: %s", seg_o, bt_hex(buf, len));

		tx->seg[seg_o] = buf;

		if (IS_ENABLED(CONFIG_BT_MESH_FRIEND)) {
			enum bt_mesh_friend_pdu_type type;

			struct os_mbuf *seg = NET_BUF_SIMPLE(16);
			seg_tx_buf_build(tx, seg_o, seg);

			if (seg_o == tx->seg_n) {
				type = BT_MESH_FRIEND_PDU_COMPLETE;
			} else {
				type = BT_MESH_FRIEND_PDU_PARTIAL;
			}

			if (bt_mesh_friend_enqueue_tx(
				    net_tx, type, ctl_op ? NULL : &tx->seq_auth,
				    tx->seg_n + 1, seg) &&
			    BT_MESH_ADDR_IS_UNICAST(net_tx->ctx->addr)) {
				/* PDUs for a specific Friend should only go
				 * out through the Friend Queue.
				 */
				k_mem_slab_free(&segs, &buf);
				tx->seg[seg_o] = NULL;
			}
			os_mbuf_free_chain(seg);
		}

	}

	/* This can happen if segments only went into the Friend Queue */
	if (IS_ENABLED(CONFIG_BT_MESH_FRIEND) && !tx->seg[0]) {
		seg_tx_reset(tx);

		/* If there was a callback notify sending immediately since
		 * there's no other way to track this (at least currently)
		 * with the Friend Queue.
		 */
		send_cb_finalize(cb, cb_data);
		return 0;
	}

	if (blocked) {
		/* Move the sequence number, so we don't end up creating
		 * another segmented transmission with the same SeqZero while
		 * this one is blocked.
		 */
		bt_mesh_next_seq();
		BT_DBG("Blocked.");
		return 0;
	}

	seg_tx_send_unacked(tx);

	if (IS_ENABLED(CONFIG_BT_MESH_LOW_POWER) &&
	    bt_mesh_lpn_established()) {
		bt_mesh_lpn_poll();
	}

	return 0;
}