frr: add smoke test for bgp6 with vpn4 srv6

[maxime-leroy]

Add a smoke test that brings up a FRR+Grout router and an FRR BGP peer connected over IPv6 (BGP6) and exchanges VPNv4 routes using SRv6. The test passes when both sides learn the remote IPv4 /24 and hosts in each VRF can ping each other.

Summary by CodeRabbit

• Tests

  • Added an end-to-end shell test that validates VPNv4 route exchange over BGP6 with SRv6 across multi-namespace FRR deployments, automating topology and SRv6/BGP setup, route-learning checks with timeouts, connectivity verification, and clear failure reporting.

• Bug Fixes

  • Simplified datapath handling to consistently derive interface, stats, and tracing from the actual packet interface, improving VRF and stats reporting and removing an obsolete invalid-interface code path.

_{✏️ Tip: You can customize this high-level summary in your review settings.}

[coderabbitai]

Caution

Review failed

The pull request is closed.

📝 Walkthrough

Walkthrough

Adds smoke/bgp6_srv6_frr_test.sh, a shell test that builds multi-namespace FRR instances, configures IPv6/SRv6 locators, VRFs, and BGP6/VPNv4 sessions via vtysh/grcli, polls for VPNv4 route exchange with timeouts, and verifies end-to-end connectivity with pings. Updates modules/infra/datapath/loop_xvrf.c to remove the INVALID_IFACE path and use eth_data->iface consistently for interface selection, stats, tracing flags, and VRF id.

Pre-merge checks

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	You can run @coderabbitai generate docstrings to improve docstring coverage.

✅ Passed checks (2 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately summarizes the main change: adding a smoke test for BGP6 with VPN4 SRv6, which matches the primary file addition and PR objectives.

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• modules/infra/datapath/loop_xvrf.c (1 hunks)
• smoke/bgp6_srv6_frr_test.sh (1 hunks)

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[coderabbitai]

Actionable comments posted: 1

🧹 Nitpick comments (1)

smoke/bgp6_srv6_frr_test.sh (1)

72-72: Remove duplicate command.

Line 72 duplicates the link-up command from line 69 with no intervening changes. This is harmless but unnecessary.

 ip -n ns-a link set eth0 up
-ip -n ns-a link set eth0 up
 ip -n ns-a addr add 16.0.0.2/24 dev eth0

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Reviewing files that changed from the base of the PR and between 37521c7 and 3e24d96.

📒 Files selected for processing (1)

• smoke/bgp6_srv6_frr_test.sh (1 hunks)

🧰 Additional context used

📓 Path-based instructions (1)

**/*.sh

⚙️ CodeRabbit configuration file

**/*.sh: - Don't bother about unquoted shell variables.

Files:

• smoke/bgp6_srv6_frr_test.sh

🧠 Learnings (2)

📓 Common learnings

Learnt from: maxime-leroy
Repo: DPDK/grout PR: 372
File: smoke/cross_vrf_forward_test.sh:18-18
Timestamp: 2025-11-05T13:55:26.189Z
Learning: In the DPDK/grout codebase, VRF interfaces (named gr-vrf<id>) are automatically created when an interface is added to a non-existing VRF using port_add. The VRF creation is handled automatically by the event system in vrf_netlink.c, so no explicit VRF interface creation commands are needed in test scripts.

Learnt from: maxime-leroy
Repo: DPDK/grout PR: 309
File: modules/srv6/datapath/srv6_local.c:88-122
Timestamp: 2025-09-09T06:02:47.703Z
Learning: When parsing IPv6 routing headers in SRv6 processing, bounds checking for the full extension header length and validation of the routing header structure is needed before accessing fields like hdr_len, last_entry, segments_left, and type.

📚 Learning: 2025-11-05T13:55:26.189Z

Learnt from: maxime-leroy
Repo: DPDK/grout PR: 372
File: smoke/cross_vrf_forward_test.sh:18-18
Timestamp: 2025-11-05T13:55:26.189Z
Learning: In the DPDK/grout codebase, VRF interfaces (named gr-vrf<id>) are automatically created when an interface is added to a non-existing VRF using port_add. The VRF creation is handled automatically by the event system in vrf_netlink.c, so no explicit VRF interface creation commands are needed in test scripts.

Applied to files:

• smoke/bgp6_srv6_frr_test.sh

🧬 Code graph analysis (1)

smoke/bgp6_srv6_frr_test.sh (2)

smoke/_init_frr.sh (5)

• create_interface (8-23)
• set_vrf_iface (68-77)
• set_ip_address (25-56)
• set_ip_route (79-119)
• start_frr_on_namespace (239-286)

smoke/_init.sh (2)

• netns_add (113-121)
• fail (104-107)

🪛 Shellcheck (0.11.0)

smoke/bgp6_srv6_frr_test.sh

[warning] 38-38: Quote this to prevent word splitting.

(SC2046)

⏰ Context from checks skipped due to timeout of 90000ms. You can increase the timeout in your CodeRabbit configuration to a maximum of 15 minutes (900000ms). (7)

• GitHub Check: build-and-tests (clang-16, none, debugoptimized, ubuntu-24.04, false)
• GitHub Check: build-and-tests (clang-15, none, debugoptimized, ubuntu-22.04, false)
• GitHub Check: build-and-tests (clang-18, none, debugoptimized, ubuntu-24.04, false)
• GitHub Check: build-and-tests (gcc-14, address, debug, ubuntu-24.04, -Dfrr=enabled, true)
• GitHub Check: build-and-tests (gcc-13, none, debugoptimized, ubuntu-24.04, -Dfrr=enabled, false)
• GitHub Check: rpm
• GitHub Check: deb

🔇 Additional comments (1)

smoke/bgp6_srv6_frr_test.sh (1)

40-46: Verify whether set_vrf_iface call is necessary.

Based on prior learnings from this codebase, VRF interfaces (gr-vrf) are automatically created when an interface is added to a non-existing VRF via port_add. Line 42 calls set_vrf_iface 1 explicitly after line 41 creates interface p1 in vrf 1. Verify whether line 42 is still needed or if it is now redundant given automatic VRF creation.

[coderabbitai]

Actionable comments posted: 0

🧹 Nitpick comments (1)

modules/infra/datapath/loop_xvrf.c (1)

35-56: Iface/ptype invariants and minor stats comment nit

• Lines 38–41: with the else falling through to IP6_INPUT, any packet that is not tagged RTE_PTYPE_L3_IPV4 will now be treated as IPv6. This assumes only IPv4/IPv6 L3 traffic ever reaches loop_xvrf. Please confirm that there is no path that could deliver non‑L3 or other types here (e.g. ARP, unknown), otherwise they’d be misrouted to ip6_input instead of being dropped/handled via a dedicated edge.
• Lines 47–54: we now unconditionally dereference eth_data->iface for stats and tracing (id, flags, vrf_id). That’s fine if the graph always sets eth_data->iface before reaching this node, but it removes the previous safety net (INVALID_IFACE/GR_VRF_ID_ALL). Worth double‑checking that there is no control‑plane or corner path where eth_data->iface could be NULL or carry a dummy iface, otherwise this becomes a hard crash. If the invariant holds, an inline comment or an assert(eth_data->iface != NULL); could make it explicit.
• Line 46–49: the comment says “increment tx stats” but the code updates rx_packets/rx_bytes. If that’s intentional (RX from the VRF’s perspective), consider clarifying the comment to avoid confusion.

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📥 Commits

Reviewing files that changed from the base of the PR and between 76ea8c9 and d0142b9.

⛔ Files ignored due to path filters (1)

• docs/graph.svg is excluded by !**/*.svg

📒 Files selected for processing (1)

• modules/infra/datapath/loop_xvrf.c (1 hunks)

🧰 Additional context used

📓 Path-based instructions (1)

**/*.{c,h}

⚙️ CodeRabbit configuration file

**/*.{c,h}: - gr_vec_*() functions cannot fail. No need to check their return value.

• gr_vec_free(x) always sets x = NULL. There is no risk of double free.
• ec_node_*() functions consume their ec_node arguments. No leaks on error.
• rte_node->ctx is an uint8_t array of size 16, not a pointer.
• Don't suggest to replace assert() with graceful error checking.
• We compile with -std=gnu2x. Unnamed parameters in function definitions are valid.

Files:

• modules/infra/datapath/loop_xvrf.c

🧠 Learnings (5)

📓 Common learnings

Learnt from: maxime-leroy
Repo: DPDK/grout PR: 372
File: smoke/cross_vrf_forward_test.sh:18-18
Timestamp: 2025-11-05T13:55:26.189Z
Learning: In the DPDK/grout codebase, VRF interfaces (named gr-vrf<id>) are automatically created when an interface is added to a non-existing VRF using port_add. The VRF creation is handled automatically by the event system in vrf_netlink.c, so no explicit VRF interface creation commands are needed in test scripts.

📚 Learning: 2025-11-05T14:28:28.817Z

Learnt from: rjarry
Repo: DPDK/grout PR: 372
File: modules/infra/datapath/loop_input.c:53-56
Timestamp: 2025-11-05T14:28:28.817Z
Learning: In modules/infra/datapath/loop_input.c, the l3_edges array is intentionally indexed using network byte order (rte_be16_t) for EtherType values. Both loopback_input_add_type() registration and loopback_input_process() lookup use network byte order consistently, so no byte order conversion is needed when accessing l3_edges.

Applied to files:

• modules/infra/datapath/loop_xvrf.c

📚 Learning: 2025-11-05T13:55:26.189Z

Learnt from: maxime-leroy
Repo: DPDK/grout PR: 372
File: smoke/cross_vrf_forward_test.sh:18-18
Timestamp: 2025-11-05T13:55:26.189Z
Learning: In the DPDK/grout codebase, VRF interfaces (named gr-vrf<id>) are automatically created when an interface is added to a non-existing VRF using port_add. The VRF creation is handled automatically by the event system in vrf_netlink.c, so no explicit VRF interface creation commands are needed in test scripts.

Applied to files:

• modules/infra/datapath/loop_xvrf.c

📚 Learning: 2025-09-09T09:22:31.596Z

Learnt from: maxime-leroy
Repo: DPDK/grout PR: 309
File: modules/srv6/datapath/srv6_local.c:97-101
Timestamp: 2025-09-09T09:22:31.596Z
Learning: In SRv6 IPv6 extension header parsing, when is_ipv6_ext[proto] is true, rte_ipv6_get_next_ext() will not return a negative value, making error checking unnecessary. An assert can be used as a defensive measure for future DPDK compatibility.

Applied to files:

• modules/infra/datapath/loop_xvrf.c

📚 Learning: 2025-11-03T13:28:19.489Z

Learnt from: rjarry
Repo: DPDK/grout PR: 379
File: modules/infra/datapath/port_tx.c:36-46
Timestamp: 2025-11-03T13:28:19.489Z
Learning: In DPDK graph node process callbacks, the return value is only used for statistics and does not affect packet flow or scheduling through the graph. Nodes can return 0 when they haven't processed packets (e.g., when dropping or redirecting due to port state).

Applied to files:

• modules/infra/datapath/loop_xvrf.c

🧬 Code graph analysis (1)

modules/infra/datapath/loop_xvrf.c (3)

modules/infra/control/gr_iface.h (1)

• iface_get_stats (102-104)

modules/infra/datapath/gr_mbuf.h (1)

• gr_mbuf_is_traced (52-54)

modules/infra/datapath/trace.c (1)

• gr_mbuf_trace_add (592-619)