+/* tipc_link_build_bc_proto_msg() - create broadcast protocol message
+ */
+static bool tipc_link_build_bc_proto_msg(struct tipc_link *l, bool bcast,
+ u16 peers_snd_nxt,
+ struct sk_buff_head *xmitq)
+{
+ struct sk_buff *skb;
+ struct tipc_msg *hdr;
+ struct sk_buff *dfrd_skb = skb_peek(&l->deferdq);
+ u16 ack = l->rcv_nxt - 1;
+ u16 gap_to = peers_snd_nxt - 1;
+
+ skb = tipc_msg_create(BCAST_PROTOCOL, STATE_MSG, INT_H_SIZE,
+ 0, l->addr, link_own_addr(l), 0, 0, 0);
+ if (!skb)
+ return false;
+ hdr = buf_msg(skb);
+ msg_set_last_bcast(hdr, l->bc_sndlink->snd_nxt - 1);
+ msg_set_bcast_ack(hdr, ack);
+ msg_set_bcgap_after(hdr, ack);
+ if (dfrd_skb)
+ gap_to = buf_seqno(dfrd_skb) - 1;
+ msg_set_bcgap_to(hdr, gap_to);
+ msg_set_non_seq(hdr, bcast);
+ __skb_queue_tail(xmitq, skb);
+ return true;
+}
+
+/* tipc_link_build_bc_init_msg() - synchronize broadcast link endpoints.
+ *
+ * Give a newly added peer node the sequence number where it should
+ * start receiving and acking broadcast packets.
+ */
+static void tipc_link_build_bc_init_msg(struct tipc_link *l,
+ struct sk_buff_head *xmitq)
+{
+ struct sk_buff_head list;
+
+ __skb_queue_head_init(&list);
+ if (!tipc_link_build_bc_proto_msg(l->bc_rcvlink, false, 0, &list))
+ return;
+ tipc_link_xmit(l, &list, xmitq);
+}
+
+/* tipc_link_bc_init_rcv - receive initial broadcast synch data from peer
+ */
+void tipc_link_bc_init_rcv(struct tipc_link *l, struct tipc_msg *hdr)
+{
+ int mtyp = msg_type(hdr);
+ u16 peers_snd_nxt = msg_bc_snd_nxt(hdr);
+
+ if (link_is_up(l))
+ return;
+
+ if (msg_user(hdr) == BCAST_PROTOCOL) {
+ l->rcv_nxt = peers_snd_nxt;
+ l->state = LINK_ESTABLISHED;
+ return;
+ }
+
+ if (l->peer_caps & TIPC_BCAST_SYNCH)
+ return;
+
+ if (msg_peer_node_is_up(hdr))
+ return;
+
+ /* Compatibility: accept older, less safe initial synch data */
+ if ((mtyp == RESET_MSG) || (mtyp == ACTIVATE_MSG))
+ l->rcv_nxt = peers_snd_nxt;
+}
+
+/* tipc_link_bc_sync_rcv - update rcv link according to peer's send state
+ */
+void tipc_link_bc_sync_rcv(struct tipc_link *l, struct tipc_msg *hdr,
+ struct sk_buff_head *xmitq)
+{
+ u16 peers_snd_nxt = msg_bc_snd_nxt(hdr);
+
+ if (!link_is_up(l))
+ return;
+
+ if (!msg_peer_node_is_up(hdr))
+ return;
+
+ l->bc_peer_is_up = true;
+
+ /* Ignore if peers_snd_nxt goes beyond receive window */
+ if (more(peers_snd_nxt, l->rcv_nxt + l->window))
+ return;
+
+ if (!more(peers_snd_nxt, l->rcv_nxt)) {
+ l->nack_state = BC_NACK_SND_CONDITIONAL;
+ return;
+ }
+
+ /* Don't NACK if one was recently sent or peeked */
+ if (l->nack_state == BC_NACK_SND_SUPPRESS) {
+ l->nack_state = BC_NACK_SND_UNCONDITIONAL;
+ return;
+ }
+
+ /* Conditionally delay NACK sending until next synch rcv */
+ if (l->nack_state == BC_NACK_SND_CONDITIONAL) {
+ l->nack_state = BC_NACK_SND_UNCONDITIONAL;
+ if ((peers_snd_nxt - l->rcv_nxt) < TIPC_MIN_LINK_WIN)
+ return;
+ }
+
+ /* Send NACK now but suppress next one */
+ tipc_link_build_bc_proto_msg(l, true, peers_snd_nxt, xmitq);
+ l->nack_state = BC_NACK_SND_SUPPRESS;
+}
+
+void tipc_link_bc_ack_rcv(struct tipc_link *l, u16 acked,
+ struct sk_buff_head *xmitq)
+{
+ struct sk_buff *skb, *tmp;
+ struct tipc_link *snd_l = l->bc_sndlink;
+
+ if (!link_is_up(l) || !l->bc_peer_is_up)
+ return;
+
+ if (!more(acked, l->acked))
+ return;
+
+ /* Skip over packets peer has already acked */
+ skb_queue_walk(&snd_l->transmq, skb) {
+ if (more(buf_seqno(skb), l->acked))
+ break;
+ }
+
+ /* Update/release the packets peer is acking now */
+ skb_queue_walk_from_safe(&snd_l->transmq, skb, tmp) {
+ if (more(buf_seqno(skb), acked))
+ break;
+ if (!--TIPC_SKB_CB(skb)->ackers) {
+ __skb_unlink(skb, &snd_l->transmq);
+ kfree_skb(skb);
+ }
+ }
+ l->acked = acked;
+ tipc_link_advance_backlog(snd_l, xmitq);
+ if (unlikely(!skb_queue_empty(&snd_l->wakeupq)))
+ link_prepare_wakeup(snd_l);
+}
+
+/* tipc_link_bc_nack_rcv(): receive broadcast nack message
+ */
+int tipc_link_bc_nack_rcv(struct tipc_link *l, struct sk_buff *skb,
+ struct sk_buff_head *xmitq)
+{
+ struct tipc_msg *hdr = buf_msg(skb);
+ u32 dnode = msg_destnode(hdr);
+ int mtyp = msg_type(hdr);
+ u16 acked = msg_bcast_ack(hdr);
+ u16 from = acked + 1;
+ u16 to = msg_bcgap_to(hdr);
+ u16 peers_snd_nxt = to + 1;
+ int rc = 0;
+
+ kfree_skb(skb);
+
+ if (!tipc_link_is_up(l) || !l->bc_peer_is_up)
+ return 0;
+
+ if (mtyp != STATE_MSG)
+ return 0;
+
+ if (dnode == link_own_addr(l)) {
+ tipc_link_bc_ack_rcv(l, acked, xmitq);
+ rc = tipc_link_retrans(l->bc_sndlink, from, to, xmitq);
+ l->stats.recv_nacks++;
+ return rc;
+ }
+
+ /* Msg for other node => suppress own NACK at next sync if applicable */
+ if (more(peers_snd_nxt, l->rcv_nxt) && !less(l->rcv_nxt, from))
+ l->nack_state = BC_NACK_SND_SUPPRESS;
+
+ return 0;
+}
+