bpf/progs/test_xdp_vlan.c

4  * XDP/TC VLAN manipulation example
7  * else the VLAN tags are NOT inlined in the packet payload:
12  *  # ethtool -k ixgbe2 | grep rx-vlan-offload
13  *  rx-vlan-offload: off
30  *	struct vlan_hdr - vlan header
31  *	@h_vlan_TCI: priority and VLAN ID
42 #define VLAN_VID_MASK		0x0fff /* VLAN Identifier */
63 	/* Make sure packet is large enough for parsing eth + 2 VLAN headers */  in parse_eth_frame()
69 	/* Handle outer VLAN tag */  in parse_eth_frame()
82 	/* Handle inner (double) VLAN tag */  in parse_eth_frame()
115 	/* Drop specific VLAN ID example */  in xdp_prognum0()
127 Commands to setup VLAN on Linux to test packets gets dropped:
131  ip link add link $ROOTDEV name $ROOTDEV.$VLANID type vlan id $VLANID
144 /* Changing VLAN to zero, have same practical effect as removing the VLAN. */
157 	/* Change specific VLAN ID */  in xdp_prognum1()
161 		/* Modifying VLAN, preserve top 4 bits */  in xdp_prognum1()
171  * Show XDP+TC can cooperate, on creating a VLAN rewriter.
172  * 1. Create a XDP prog that can "pop"/remove a VLAN header.
173  * 2. Create a TC-bpf prog that egress can add a VLAN header.
192 	/* Skip packet if no outer VLAN was detected */  in xdp_prognum2()
230 	/* Assuming VLAN hdr present. The 4 bytes in p[3] that gets  in shift_mac_4bytes_32bit()
251 	/* Skip packet if no outer VLAN was detected */  in xdp_prognum3()