[RFC PATCH] ethdev: introduce NAT64 action

[Bing Zhao <bingz@nvidia.com>]

In order to support the communication between IPv4 and IPv6 nodes in
the network, different technologies are used, like dual-stacks,
tunneling and NAT64. In some IPv4-only clients, it is hard to deploy
new software and hardware to support IPv6.

NAT64 is a choice and it will also reduce the unnecessary overhead of
the traffic in the network. The NAT64 gateways take the
responsibility of the packet headers translation between the IPv6
clouds and IPv4-only clouds.

This action should support the offloading of the IP headers'
translation. The following fields should be reset correctly in the
translation.
  - Version
  - Traffic Class / TOS
  - Flow Label (0 in v4)
  - Payload Length / Total length
  - Next Header
  - Hop Limit / TTL

Since there are different mapping and translating modes of the
addresses, it will depend on the capabilities of each vendor.

The ICMP* and transport layers protocol is out of the scope of NAT64
rte_flow action.

Reference links:
  - https://datatracker.ietf.org/doc/html/rfc6146
  - https://datatracker.ietf.org/doc/html/rfc6052
  - https://datatracker.ietf.org/doc/html/rfc6145

Signed-off-by: Bing Zhao <bingz@nvidia.com>
---
 lib/ethdev/rte_flow.c |  1 +
 lib/ethdev/rte_flow.h | 27 +++++++++++++++++++++++++++
 2 files changed, 28 insertions(+)

diff --git a/lib/ethdev/rte_flow.c b/lib/ethdev/rte_flow.c
index 271d854f78..b60a4f6654 100644
--- a/lib/ethdev/rte_flow.c
+++ b/lib/ethdev/rte_flow.c
@@ -265,6 +265,7 @@ static const struct rte_flow_desc_data rte_flow_desc_action[] = {
 	MK_FLOW_ACTION(IPV6_EXT_REMOVE, sizeof(struct rte_flow_action_ipv6_ext_remove)),
 	MK_FLOW_ACTION(INDIRECT_LIST,
 		       sizeof(struct rte_flow_action_indirect_list)),
+	MK_FLOW_ACTION(NAT64, sizeof(struct rte_flow_action_nat64)),
 };
 
 int
diff --git a/lib/ethdev/rte_flow.h b/lib/ethdev/rte_flow.h
index 86ed98c562..2002999a35 100644
--- a/lib/ethdev/rte_flow.h
+++ b/lib/ethdev/rte_flow.h
@@ -2989,6 +2989,13 @@ enum rte_flow_action_type {
 	 * @see struct rte_flow_action_indirect_list
 	 */
 	RTE_FLOW_ACTION_TYPE_INDIRECT_LIST,
+
+	/**
+	 * Support the NAT64 translation.
+	 *
+	 * @see struct rte_flow_action_nat64
+	 */
+	RTE_FLOW_ACTION_TYPE_NAT64,
 };
 
 /**
@@ -4092,6 +4099,26 @@ rte_flow_dynf_metadata_set(struct rte_mbuf *m, uint32_t v)
 	*RTE_FLOW_DYNF_METADATA(m) = v;
 }
 
+/**
+ * NAT64 translation type for IP headers.
+ */
+enum rte_flow_nat64_type {
+	RTE_FLOW_NAT64_6TO4 = 0, /**< IPv6 to IPv4 headers translation. */
+	RTE_FLOW_NAT64_4TO6 = 1, /**< IPv4 to IPv6 headers translation. */
+};
+
+/**
+ * @warning
+ * @b EXPERIMENTAL: this structure may change without prior notice
+ *
+ * RTE_FLOW_ACTION_TYPE_NAT64
+ *
+ * Specify the NAT64 translation type.
+ */
+struct rte_flow_action_nat64 {
+	enum rte_flow_nat64_type type;
+};
+
 /**
  * Definition of a single action.
  *
-- 
2.34.1