[dpdk-dev] [RFC v3] ethdev: add extensions attributes to IPv6 item

[Dekel Peled <dekelp@mellanox.com>]

Using the current implementation of DPDK, an application cannot match on
IPv6 packets, based on the existing extension headers, in a simple way.

Field 'Next Header' in IPv6 header indicates type of the first extension
header only. Following extension headers can't be identified by
inspecting the IPv6 header.
As a result, the existence or absence of specific extension headers
can't be used for packet matching.

For example, fragmented IPv6 packets contain a dedicated extension header,
as detailed in RFC [1], which is not yet supported in rte_flow.
Non-fragmented packets don't contain the fragment extension header.
For an application to match on non-fragmented IPv6 packets, the current
implementation doesn't provide a suitable solution.
Matching on the Next Header field is not sufficient, since additional
extension headers might be present in the same packet.
To match on fragmented IPv6 packets, the same difficulty exists.

Proposed update:
A set of additional values will be added to IPv6 header struct.
These values will indicate the existence of every defined extension
header type, providing simple means for identification of existing
extensions in the packet header.
Continuing the above example, fragmented packets can be identified using
the specific value indicating existence of fragment extension header.

This update changes ABI, and is proposed for the 20.11 LTS version.

[1] http://mails.dpdk.org/archives/dev/2020-March/160255.html

---
v3: Fix checkpatch comments.
v2: Update from fragment attribute to all extensions attributes.
---

Signed-off-by: Dekel Peled <dekelp@mellanox.com>
---
 lib/librte_ethdev/rte_flow.h | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/lib/librte_ethdev/rte_flow.h b/lib/librte_ethdev/rte_flow.h
index da8bfa5..246918e 100644
--- a/lib/librte_ethdev/rte_flow.h
+++ b/lib/librte_ethdev/rte_flow.h
@@ -792,11 +792,33 @@ struct rte_flow_item_ipv4 {
  *
  * Matches an IPv6 header.
  *
+ * Dedicated flags indicate existence of specific extension headers.
+ *
  * Note: IPv6 options are handled by dedicated pattern items, see
  * RTE_FLOW_ITEM_TYPE_IPV6_EXT.
  */
 struct rte_flow_item_ipv6 {
 	struct rte_ipv6_hdr hdr; /**< IPv6 header definition. */
+	uint64_t hop_ext_exist:1;
+	/**< Hop-by-Hop Options extension header exists. */
+	uint64_t rout_ext_exist:1;
+	/**< Routing extension header exists. */
+	uint64_t frag_ext_exist:1;
+	/**< Fragment extension header exists. */
+	uint64_t auth_ext_exist:1;
+	/**< Authentication extension header exists. */
+	uint64_t esp_ext_exist:1;
+	/**< Encapsulation Security Payload extension header exists. */
+	uint64_t dest_ext_exist:1;
+	/**< Destination Options extension header exists. */
+	uint64_t mobil_ext_exist:1;
+	/**< Mobility extension header exists. */
+	uint64_t hip_ext_exist:1;
+	/**< Host Identity Protocol extension header exists. */
+	uint64_t shim6_ext_exist:1;
+	/**< Shim6 Protocol extension header exists. */
+	uint64_t reserved:55;
+	/**< Reserved for future extension headers, must be zero. */
 };
 
 /** Default mask for RTE_FLOW_ITEM_TYPE_IPV6. */
-- 
1.8.3.1