l4: ensure packet type is set before L4 processing

[rjarry]

The L4 nodes (l4_input_local, l4_loopback_output, ospf_redirect) use mbuf->packet_type to determine whether a packet comes from IPv4 or IPv6. However, the ip_input_local and ip6_input_local nodes never set this field explicitly before forwarding to L4. When the NIC does not classify packets or when the value is stale, L4 nodes cannot determine the correct protocol and drop the packet.

Set packet_type to RTE_PTYPE_L3_IPV4 or RTE_PTYPE_L3_IPV6 in each ip*_input_local node before stripping the IP header.

Link: #625

L4 nodes rely on mbuf->packet_type to determine whether packets originate from IPv4 or IPv6. The ip_input_local and ip6_input_local nodes did not explicitly set this field before forwarding to L4, causing packets to be dropped when NICs lack packet classification or the value is stale.

modules/ip/datapath/ip_local.c: Set mbuf->packet_type to RTE_PTYPE_L3_IPV4 after populating per-packet metadata fields (src/dst/len/vrf_id/proto/ttl) and before stripping the IPv4 header with rte_pktmbuf_adj().

modules/ip6/datapath/ip6_local.c: Set m->packet_type to RTE_PTYPE_L3_IPV6 when handling L4 protocols (IPPROTO_UDP, IPPROTO_TCP, IPPROTO_SCTP, IPPROTO_DCCP) and before checksum verification.

[coderabbitai]

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📥 Commits

Reviewing files that changed from the base of the PR and between fe0c7f9 and 3bb2c7c.

📒 Files selected for processing (2)

• modules/ip/datapath/ip_local.c
• modules/ip6/datapath/ip6_local.c

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📝 Walkthrough

Walkthrough

This PR adds packet type annotations to the datapath for both IPv4 and IPv6 local input processing. The IPv4 path marks each matched packet as RTE_PTYPE_L3_IPV4 after populating per-packet metadata and before forwarding. The IPv6 path marks L4 protocol packets as RTE_PTYPE_L3_IPV6 during checksum verification handling. Both changes occur at single, focused points in their respective protocol stacks with no control-flow modifications.

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