+static struct stp_port *
+xport_get_stp_port(const struct xport *xport)
+{
+ return xport->xbridge->stp && xport->stp_port_no
+ ? stp_get_port(xport->xbridge->stp, xport->stp_port_no)
+ : NULL;
+}
+
+static enum stp_state
+xport_stp_learn_state(const struct xport *xport)
+{
+ struct stp_port *sp = xport_get_stp_port(xport);
+ return stp_learn_in_state(sp ? stp_port_get_state(sp) : STP_DISABLED);
+}
+
+static bool
+xport_stp_forward_state(const struct xport *xport)
+{
+ struct stp_port *sp = xport_get_stp_port(xport);
+ return stp_forward_in_state(sp ? stp_port_get_state(sp) : STP_DISABLED);
+}
+
+/* Returns true if STP should process 'flow'. Sets fields in 'wc' that
+ * were used to make the determination.*/
+static bool
+stp_should_process_flow(const struct flow *flow, struct flow_wildcards *wc)
+{
+ memset(&wc->masks.dl_dst, 0xff, sizeof wc->masks.dl_dst);
+ return eth_addr_equals(flow->dl_dst, eth_addr_stp);
+}
+
+static void
+stp_process_packet(const struct xport *xport, const struct ofpbuf *packet)
+{
+ struct stp_port *sp = xport_get_stp_port(xport);
+ struct ofpbuf payload = *packet;
+ struct eth_header *eth = payload.data;
+
+ /* Sink packets on ports that have STP disabled when the bridge has
+ * STP enabled. */
+ if (!sp || stp_port_get_state(sp) == STP_DISABLED) {
+ return;
+ }
+
+ /* Trim off padding on payload. */
+ if (payload.size > ntohs(eth->eth_type) + ETH_HEADER_LEN) {
+ payload.size = ntohs(eth->eth_type) + ETH_HEADER_LEN;
+ }
+
+ if (ofpbuf_try_pull(&payload, ETH_HEADER_LEN + LLC_HEADER_LEN)) {
+ stp_received_bpdu(sp, payload.data, payload.size);
+ }
+}
+