> From: Dengdui Huang [mailto:huangdeng...@huawei.com]
> Sent: Thursday, 3 July 2025 11.30
>
> The current rte_net_get_ptype() only supports parsing packets with
> one 0x8100 VLAN tag or two 0x88a8 VLAN tags. This patch extends it
> to support parsing packets with two 0x8100 VLAN tags.
>
> Signed-off-by: Dengdui Huang <huangdeng...@huawei.com>
> ---
> lib/net/rte_net.c | 34 ++++++++++++++++++++++------------
> lib/net/rte_net.h | 2 ++
> 2 files changed, 24 insertions(+), 12 deletions(-)
>
> diff --git a/lib/net/rte_net.c b/lib/net/rte_net.c
> index 44fb6c0f51..fa8d023ca7 100644
> --- a/lib/net/rte_net.c
> +++ b/lib/net/rte_net.c
> @@ -352,14 +352,19 @@ uint32_t rte_net_get_ptype(const struct rte_mbuf
> *m,
> if (proto == rte_cpu_to_be_16(RTE_ETHER_TYPE_VLAN)) {
> const struct rte_vlan_hdr *vh;
> struct rte_vlan_hdr vh_copy;
> + uint8_t vlan_num = 1;
>
> pkt_type = RTE_PTYPE_L2_ETHER_VLAN;
> - vh = rte_pktmbuf_read(m, off, sizeof(*vh), &vh_copy);
> - if (unlikely(vh == NULL))
> - return pkt_type;
> - off += sizeof(*vh);
> - hdr_lens->l2_len += sizeof(*vh);
> - proto = vh->eth_proto;
> + while (proto == rte_cpu_to_be_16(RTE_ETHER_TYPE_VLAN) &&
> + vlan_num <= MAX_VLAN_STACKING_TAGS) {
> + vh = rte_pktmbuf_read(m, off, sizeof(*vh), &vh_copy);
> + if (unlikely(vh == NULL))
> + return pkt_type;
> + off += sizeof(*vh);
> + hdr_lens->l2_len += sizeof(*vh);
> + proto = vh->eth_proto;
> + vlan_num++;
> + }
It's not that simple.
VLAN tags are not like MPLS labels.
With the MPLS packet type, we expect a stack of labels.
But with VLAN tagged packets, we expect exactly one VLAN tag at each
outer/inner layer of headers. (Or no VLAN tag at the inner layer.)
This function already supports packets with 2 VLAN tags:
A stack of 2 VLAN tags is currently detected as 1 outer VLAN tag, adjusting
hdr_lens->l2_len accordingly, and 1 inner VLAN tag, adjusting
hdr_lens->inner_l2_len accordingly.
This behavior should not be changed.
I don't have a firm idea about how to better represent packets with a stack of
3+ VLAN tags than what we do today, so suggestions are welcome.
Which use case is this patch addressing?
Maybe information about the use case could guide us in some direction.
> } else if (proto == rte_cpu_to_be_16(RTE_ETHER_TYPE_QINQ)) {
> const struct rte_vlan_hdr *vh;
> struct rte_vlan_hdr vh_copy;
> @@ -504,15 +509,20 @@ uint32_t rte_net_get_ptype(const struct rte_mbuf
> *m,
> if (proto == rte_cpu_to_be_16(RTE_ETHER_TYPE_VLAN)) {
> const struct rte_vlan_hdr *vh;
> struct rte_vlan_hdr vh_copy;
> + uint8_t vlan_num = 1;
>
> pkt_type &= ~RTE_PTYPE_INNER_L2_MASK;
> pkt_type |= RTE_PTYPE_INNER_L2_ETHER_VLAN;
> - vh = rte_pktmbuf_read(m, off, sizeof(*vh), &vh_copy);
> - if (unlikely(vh == NULL))
> - return pkt_type;
> - off += sizeof(*vh);
> - hdr_lens->inner_l2_len += sizeof(*vh);
> - proto = vh->eth_proto;
> + while (proto == rte_cpu_to_be_16(RTE_ETHER_TYPE_VLAN) &&
> + vlan_num <= MAX_VLAN_STACKING_TAGS) {
> + vh = rte_pktmbuf_read(m, off, sizeof(*vh), &vh_copy);
> + if (unlikely(vh == NULL))
> + return pkt_type;
> + off += sizeof(*vh);
> + hdr_lens->inner_l2_len += sizeof(*vh);
> + proto = vh->eth_proto;
> + vlan_num++;
> + }
> } else if (proto == rte_cpu_to_be_16(RTE_ETHER_TYPE_QINQ)) {
> const struct rte_vlan_hdr *vh;
> struct rte_vlan_hdr vh_copy;
> diff --git a/lib/net/rte_net.h b/lib/net/rte_net.h
> index 65d724b84b..fdd55d57c8 100644
> --- a/lib/net/rte_net.h
> +++ b/lib/net/rte_net.h
> @@ -13,6 +13,8 @@
> extern "C" {
> #endif
>
> +#define MAX_VLAN_STACKING_TAGS 2
> +
> /**
> * Structure containing header lengths associated to a packet, filled
> * by rte_net_get_ptype().
> --
> 2.33.0
