[PATCH v4 1/2] net: add functions to calculate UDP/TCP cksum in mbuf
Li, Xiaoyun
xiaoyun.li at intel.com
Tue Jan 4 16:40:48 CET 2022
Hi
> -----Original Message-----
> From: Li, Xiaoyun <xiaoyun.li at intel.com>
> Sent: Tuesday, January 4, 2022 15:19
> To: Singh, Aman Deep <aman.deep.singh at intel.com>; Yigit, Ferruh
> <ferruh.yigit at intel.com>; olivier.matz at 6wind.com;
> mb at smartsharesystems.com; Ananyev, Konstantin
> <konstantin.ananyev at intel.com>; stephen at networkplumber.org;
> Medvedkin, Vladimir <vladimir.medvedkin at intel.com>
> Cc: dev at dpdk.org
> Subject: RE: [PATCH v4 1/2] net: add functions to calculate UDP/TCP cksum in
> mbuf
>
> Hi
>
> > -----Original Message-----
> > From: Singh, Aman Deep <aman.deep.singh at intel.com>
> > Sent: Wednesday, December 15, 2021 11:34
> > To: Li, Xiaoyun <xiaoyun.li at intel.com>; Yigit, Ferruh
> > <ferruh.yigit at intel.com>; olivier.matz at 6wind.com;
> > mb at smartsharesystems.com; Ananyev, Konstantin
> > <konstantin.ananyev at intel.com>; stephen at networkplumber.org;
> Medvedkin,
> > Vladimir <vladimir.medvedkin at intel.com>
> > Cc: dev at dpdk.org
> > Subject: Re: [PATCH v4 1/2] net: add functions to calculate UDP/TCP
> > cksum in mbuf
> >
> >
> > 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);"
>
> Will use it in next version. Thanks.
>
> Also, not related to this patch. It means that __rte_ipv4_udptcp_cksum and
> __rte_ipv6_udptcp_cksum have the same issue, right?
> Should anyone fix that?
Forgot the intent here.
rte_raw_cksum_mbuf() already calls __rte_raw_cksum_reduce().
So actually, it's a result of uint16_t + uint16_t. So it's impossible of your case. There's no need to call __rte_raw_cksum_reduce().
>
> > > +
> > > + 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.
>
> This is the intent. This function is to verify if the cksum in the packet is correct.
>
> It's different from calling rte_ipv4/6_udptcp_cksum_mbuf(). When calling
> rte_ipv4/6_udptcp_cksum_mbuf(), you need to set the cksum in udp/tcp
> header as 0. Then calculate the cksum.
>
> But here, user should directly call this function with the original packet. Then
> if the udp/tcp cksum is correct, after the calculation (please note that, this is
> calling __rte_ipv4_udptcp_cksum_mbuf(), so the result needs to be ~), it
> should be 0xffff, namely, ~cksum = 0 which means cksum is correct. You can
> see rte_ipv4/6_udptcp_cksum_verify() is doing the same.
>
> > > +
> > > + 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;
> > > +};
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