[PATCH v4 1/2] net: add functions to calculate UDP/TCP cksum in mbuf

[Singh, Aman Deep]

On 12/3/2021 5:08 PM, Xiaoyun Li wrote:
> 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 at intel.com>
> ---
>   doc/guides/rel_notes/release_22_03.rst |  10 ++
>   lib/net/rte_ip.h                       | 186 +++++++++++++++++++++++++
>   lib/net/version.map                    |  10 ++
>   3 files changed, 206 insertions(+)
>
> diff --git a/doc/guides/rel_notes/release_22_03.rst b/doc/guides/rel_notes/release_22_03.rst
> index 6d99d1eaa9..7a082c4427 100644
> --- a/doc/guides/rel_notes/release_22_03.rst
> +++ b/doc/guides/rel_notes/release_22_03.rst
> @@ -55,6 +55,13 @@ 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 +91,9 @@ 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);
At times, even after above operation "cksum" might stay above 16-bits, 
ex "cksum = 0x1FFFF" to start with.
Can we consider using "return __rte_raw_cksum_reduce(cksum);"
> +
> +	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;
cksum other than 0xffff, should return error. Is that the intent or I am 
missing something obvious.
> +
> +	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);
Same, please check if we can opt for __rte_raw_cksum_reduce(cksum)
> +
> +	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
> diff --git a/lib/net/version.map b/lib/net/version.map
> index 4f4330d1c4..0f2aacdef8 100644
> --- a/lib/net/version.map
> +++ b/lib/net/version.map
> @@ -12,3 +12,13 @@ DPDK_22 {
>   
>   	local: *;
>   };
> +
> +EXPERIMENTAL {
> +	global:
> +
> +	# added in 22.03
> +	rte_ipv4_udptcp_cksum_mbuf;
> +	rte_ipv4_udptcp_cksum_mbuf_verify;
> +	rte_ipv6_udptcp_cksum_mbuf;
> +	rte_ipv6_udptcp_cksum_mbuf_verify;
> +};