[PATCH v5 1/2] net: add functions to calculate UDP/TCP cksum in mbuf

[Xiaoyun Li <xiaoyun.li@intel.com>]

Add functions to call rte_raw_cksum_mbuf() to calculate IPv4/6
UDP/TCP checksum in mbuf which can be over multi-segments.

Signed-off-by: Xiaoyun Li <xiaoyun.li@intel.com>
Acked-by: Aman Singh <aman.deep.singh@intel.com>
Tested-by: Sunil Pai G <sunil.pai.g@intel.com>
---
 doc/guides/rel_notes/release_22_03.rst |  11 ++
 lib/net/rte_ip.h                       | 186 +++++++++++++++++++++++++
 2 files changed, 197 insertions(+)

diff --git a/doc/guides/rel_notes/release_22_03.rst b/doc/guides/rel_notes/release_22_03.rst
index 6d99d1eaa9..785fd22001 100644
--- a/doc/guides/rel_notes/release_22_03.rst
+++ b/doc/guides/rel_notes/release_22_03.rst
@@ -55,6 +55,14 @@ New Features
      Also, make sure to start the actual text at the margin.
      =======================================================
 
+* **Added functions to calculate UDP/TCP checksum in mbuf.**
+
+  * Added the following functions to calculate UDP/TCP checksum of packets
+    which can be over multi-segments:
+    - ``rte_ipv4_udptcp_cksum_mbuf()``
+    - ``rte_ipv4_udptcp_cksum_mbuf_verify()``
+    - ``rte_ipv6_udptcp_cksum_mbuf()``
+    - ``rte_ipv6_udptcp_cksum_mbuf_verify()``
 
 Removed Items
 -------------
@@ -84,6 +92,9 @@ API Changes
    Also, make sure to start the actual text at the margin.
    =======================================================
 
+* net: added experimental functions ``rte_ipv4_udptcp_cksum_mbuf()``,
+  ``rte_ipv4_udptcp_cksum_mbuf_verify()``, ``rte_ipv6_udptcp_cksum_mbuf()``,
+  ``rte_ipv6_udptcp_cksum_mbuf_verify()``
 
 ABI Changes
 -----------
diff --git a/lib/net/rte_ip.h b/lib/net/rte_ip.h
index c575250852..534f401d26 100644
--- a/lib/net/rte_ip.h
+++ b/lib/net/rte_ip.h
@@ -400,6 +400,65 @@ rte_ipv4_udptcp_cksum(const struct rte_ipv4_hdr *ipv4_hdr, const void *l4_hdr)
 	return cksum;
 }
 
+/**
+ * @internal Calculate the non-complemented IPv4 L4 checksum of a packet
+ */
+static inline uint16_t
+__rte_ipv4_udptcp_cksum_mbuf(const struct rte_mbuf *m,
+			     const struct rte_ipv4_hdr *ipv4_hdr,
+			     uint16_t l4_off)
+{
+	uint16_t raw_cksum;
+	uint32_t cksum;
+
+	if (l4_off > m->pkt_len)
+		return 0;
+
+	if (rte_raw_cksum_mbuf(m, l4_off, m->pkt_len - l4_off, &raw_cksum))
+		return 0;
+
+	cksum = raw_cksum + rte_ipv4_phdr_cksum(ipv4_hdr, 0);
+
+	cksum = ((cksum & 0xffff0000) >> 16) + (cksum & 0xffff);
+
+	return (uint16_t)cksum;
+}
+
+/**
+ * @warning
+ * @b EXPERIMENTAL: this API may change without prior notice.
+ *
+ * Compute the IPv4 UDP/TCP checksum of a packet.
+ *
+ * @param m
+ *   The pointer to the mbuf.
+ * @param ipv4_hdr
+ *   The pointer to the contiguous IPv4 header.
+ * @param l4_off
+ *   The offset in bytes to start L4 checksum.
+ * @return
+ *   The complemented checksum to set in the L4 header.
+ */
+__rte_experimental
+static inline uint16_t
+rte_ipv4_udptcp_cksum_mbuf(const struct rte_mbuf *m,
+			   const struct rte_ipv4_hdr *ipv4_hdr, uint16_t l4_off)
+{
+	uint16_t cksum = __rte_ipv4_udptcp_cksum_mbuf(m, ipv4_hdr, l4_off);
+
+	cksum = ~cksum;
+
+	/*
+	 * Per RFC 768: If the computed checksum is zero for UDP,
+	 * it is transmitted as all ones
+	 * (the equivalent in one's complement arithmetic).
+	 */
+	if (cksum == 0 && ipv4_hdr->next_proto_id == IPPROTO_UDP)
+		cksum = 0xffff;
+
+	return cksum;
+}
+
 /**
  * Validate the IPv4 UDP or TCP checksum.
  *
@@ -426,6 +485,38 @@ rte_ipv4_udptcp_cksum_verify(const struct rte_ipv4_hdr *ipv4_hdr,
 	return 0;
 }
 
+/**
+ * @warning
+ * @b EXPERIMENTAL: this API may change without prior notice.
+ *
+ * Verify the IPv4 UDP/TCP checksum of a packet.
+ *
+ * In case of UDP, the caller must first check if udp_hdr->dgram_cksum is 0
+ * (i.e. no checksum).
+ *
+ * @param m
+ *   The pointer to the mbuf.
+ * @param ipv4_hdr
+ *   The pointer to the contiguous IPv4 header.
+ * @param l4_off
+ *   The offset in bytes to start L4 checksum.
+ * @return
+ *   Return 0 if the checksum is correct, else -1.
+ */
+__rte_experimental
+static inline uint16_t
+rte_ipv4_udptcp_cksum_mbuf_verify(const struct rte_mbuf *m,
+				  const struct rte_ipv4_hdr *ipv4_hdr,
+				  uint16_t l4_off)
+{
+	uint16_t cksum = __rte_ipv4_udptcp_cksum_mbuf(m, ipv4_hdr, l4_off);
+
+	if (cksum != 0xffff)
+		return -1;
+
+	return 0;
+}
+
 /**
  * IPv6 Header
  */
@@ -538,6 +629,68 @@ rte_ipv6_udptcp_cksum(const struct rte_ipv6_hdr *ipv6_hdr, const void *l4_hdr)
 	return cksum;
 }
 
+/**
+ * @internal Calculate the non-complemented IPv6 L4 checksum of a packet
+ */
+static inline uint16_t
+__rte_ipv6_udptcp_cksum_mbuf(const struct rte_mbuf *m,
+			     const struct rte_ipv6_hdr *ipv6_hdr,
+			     uint16_t l4_off)
+{
+	uint16_t raw_cksum;
+	uint32_t cksum;
+
+	if (l4_off > m->pkt_len)
+		return 0;
+
+	if (rte_raw_cksum_mbuf(m, l4_off, m->pkt_len - l4_off, &raw_cksum))
+		return 0;
+
+	cksum = raw_cksum + rte_ipv6_phdr_cksum(ipv6_hdr, 0);
+
+	cksum = ((cksum & 0xffff0000) >> 16) + (cksum & 0xffff);
+
+	return (uint16_t)cksum;
+}
+
+/**
+ * @warning
+ * @b EXPERIMENTAL: this API may change without prior notice.
+ *
+ * Process the IPv6 UDP or TCP checksum of a packet.
+ *
+ * The IPv6 header must not be followed by extension headers. The layer 4
+ * checksum must be set to 0 in the L4 header by the caller.
+ *
+ * @param m
+ *   The pointer to the mbuf.
+ * @param ipv6_hdr
+ *   The pointer to the contiguous IPv6 header.
+ * @param l4_off
+ *   The offset in bytes to start L4 checksum.
+ * @return
+ *   The complemented checksum to set in the L4 header.
+ */
+__rte_experimental
+static inline uint16_t
+rte_ipv6_udptcp_cksum_mbuf(const struct rte_mbuf *m,
+			   const struct rte_ipv6_hdr *ipv6_hdr, uint16_t l4_off)
+{
+	uint16_t cksum = __rte_ipv6_udptcp_cksum_mbuf(m, ipv6_hdr, l4_off);
+
+	cksum = ~cksum;
+
+	/*
+	 * Per RFC 768: If the computed checksum is zero for UDP,
+	 * it is transmitted as all ones
+	 * (the equivalent in one's complement arithmetic).
+	 */
+	if (cksum == 0 && ipv6_hdr->proto == IPPROTO_UDP)
+		cksum = 0xffff;
+
+	return cksum;
+}
+
 /**
  * Validate the IPv6 UDP or TCP checksum.
  *
@@ -565,6 +718,39 @@ rte_ipv6_udptcp_cksum_verify(const struct rte_ipv6_hdr *ipv6_hdr,
 	return 0;
 }
 
+/**
+ * @warning
+ * @b EXPERIMENTAL: this API may change without prior notice.
+ *
+ * Validate the IPv6 UDP or TCP checksum of a packet.
+ *
+ * In case of UDP, the caller must first check if udp_hdr->dgram_cksum is 0:
+ * this is either invalid or means no checksum in some situations. See 8.1
+ * (Upper-Layer Checksums) in RFC 8200.
+ *
+ * @param m
+ *   The pointer to the mbuf.
+ * @param ipv6_hdr
+ *   The pointer to the contiguous IPv6 header.
+ * @param l4_off
+ *   The offset in bytes to start L4 checksum.
+ * @return
+ *   Return 0 if the checksum is correct, else -1.
+ */
+__rte_experimental
+static inline int
+rte_ipv6_udptcp_cksum_mbuf_verify(const struct rte_mbuf *m,
+				  const struct rte_ipv6_hdr *ipv6_hdr,
+				  uint16_t l4_off)
+{
+	uint16_t cksum = __rte_ipv6_udptcp_cksum_mbuf(m, ipv6_hdr, l4_off);
+
+	if (cksum != 0xffff)
+		return -1;
+
+	return 0;
+}
+
 /** IPv6 fragment extension header. */
 #define	RTE_IPV6_EHDR_MF_SHIFT	0
 #define	RTE_IPV6_EHDR_MF_MASK	1
-- 
2.25.1