+
+/* Populates 'b' with an Ethernet II packet headed with the given 'eth_dst',
+ * 'eth_src' and 'eth_type' parameters. A payload of 'size' bytes is allocated
+ * in 'b' and returned. This payload may be populated with appropriate
+ * information by the caller.
+ *
+ * The returned packet has enough headroom to insert an 802.1Q VLAN header if
+ * desired. */
+void *
+eth_compose(struct ofpbuf *b, const uint8_t eth_dst[ETH_ADDR_LEN],
+ const uint8_t eth_src[ETH_ADDR_LEN], uint16_t eth_type,
+ size_t size)
+{
+ void *data;
+ struct eth_header *eth;
+
+ ofpbuf_clear(b);
+
+ ofpbuf_prealloc_tailroom(b, ETH_HEADER_LEN + VLAN_HEADER_LEN + size);
+ ofpbuf_reserve(b, VLAN_HEADER_LEN);
+ eth = ofpbuf_put_uninit(b, ETH_HEADER_LEN);
+ data = ofpbuf_put_uninit(b, size);
+
+ memcpy(eth->eth_dst, eth_dst, ETH_ADDR_LEN);
+ memcpy(eth->eth_src, eth_src, ETH_ADDR_LEN);
+ eth->eth_type = htons(eth_type);
+
+ return data;
+}
+
+/* Populates 'b' with an Ethernet LLC+SNAP packet headed with the given
+ * 'eth_dst', 'eth_src', 'snap_org', and 'snap_type'. A payload of 'size'
+ * bytes is allocated in 'b' and returned. This payload may be populated with
+ * appropriate information by the caller.
+ *
+ * The returned packet has enough headroom to insert an 802.1Q VLAN header if
+ * desired. */
+void *
+snap_compose(struct ofpbuf *b, const uint8_t eth_dst[ETH_ADDR_LEN],
+ const uint8_t eth_src[ETH_ADDR_LEN],
+ unsigned int oui, uint16_t snap_type, size_t size)
+{
+ struct eth_header *eth;
+ struct llc_snap_header *llc_snap;
+ void *payload;
+
+ /* Compose basic packet structure. (We need the payload size to stick into
+ * the 802.2 header.) */
+ ofpbuf_clear(b);
+ ofpbuf_prealloc_tailroom(b, ETH_HEADER_LEN + VLAN_HEADER_LEN
+ + LLC_SNAP_HEADER_LEN + size);
+ ofpbuf_reserve(b, VLAN_HEADER_LEN);
+ eth = ofpbuf_put_zeros(b, ETH_HEADER_LEN);
+ llc_snap = ofpbuf_put_zeros(b, LLC_SNAP_HEADER_LEN);
+ payload = ofpbuf_put_uninit(b, size);
+
+ /* Compose 802.2 header. */
+ memcpy(eth->eth_dst, eth_dst, ETH_ADDR_LEN);
+ memcpy(eth->eth_src, eth_src, ETH_ADDR_LEN);
+ eth->eth_type = htons(b->size - ETH_HEADER_LEN);
+
+ /* Compose LLC, SNAP headers. */
+ llc_snap->llc.llc_dsap = LLC_DSAP_SNAP;
+ llc_snap->llc.llc_ssap = LLC_SSAP_SNAP;
+ llc_snap->llc.llc_cntl = LLC_CNTL_SNAP;
+ llc_snap->snap.snap_org[0] = oui >> 16;
+ llc_snap->snap.snap_org[1] = oui >> 8;
+ llc_snap->snap.snap_org[2] = oui;
+ llc_snap->snap.snap_type = htons(snap_type);
+
+ return payload;
+}
+
+/* Populates 'pdu' with a LACP PDU comprised of 'actor' and 'partner'. */
+void
+compose_lacp_pdu(const struct lacp_info *actor,
+ const struct lacp_info *partner, struct lacp_pdu *pdu)
+{
+ memset(pdu, 0, sizeof *pdu);
+
+ pdu->subtype = 1;
+ pdu->version = 1;
+
+ pdu->actor_type = 1;
+ pdu->actor_len = 20;
+ pdu->actor = *actor;
+
+ pdu->partner_type = 2;
+ pdu->partner_len = 20;
+ pdu->partner = *partner;
+
+ pdu->collector_type = 3;
+ pdu->collector_len = 16;
+ pdu->collector_delay = htons(0);
+}
+
+/* Parses 'b' which represents a packet containing a LACP PDU. This function
+ * returns NULL if 'b' is malformed, or does not represent a LACP PDU format
+ * supported by OVS. Otherwise, it returns a pointer to the lacp_pdu contained
+ * within 'b'. */
+const struct lacp_pdu *
+parse_lacp_packet(const struct ofpbuf *b)
+{
+ const struct lacp_pdu *pdu;
+
+ pdu = ofpbuf_at(b, (uint8_t *)b->l3 - (uint8_t *)b->data, LACP_PDU_LEN);
+
+ if (pdu && pdu->subtype == 1
+ && pdu->actor_type == 1 && pdu->actor_len == 20
+ && pdu->partner_type == 2 && pdu->partner_len == 20) {
+ return pdu;
+ } else {
+ return NULL;
+ }
+}