From: David Gibson <david@gibson.dropbear.id.au>
To: Laurent Vivier <lvivier@redhat.com>
Cc: passt-dev@passt.top
Subject: Re: [PATCH v4 5/8] checksum: use csum_ip4_header() in udp.c and tcp.c
Date: Fri, 1 Mar 2024 10:25:02 +1100 [thread overview]
Message-ID: <ZeESTj6olXE6NGti@zatzit> (raw)
In-Reply-To: <20240229165955.829476-6-lvivier@redhat.com>
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On Thu, Feb 29, 2024 at 05:59:52PM +0100, Laurent Vivier wrote:
> We can find the same function to compute the IPv4 header
> checksum in tcp.c, udp.c and tap.c
>
> Use the function defined for tap.c, csum_ip4_header(), but
> with the code used in tcp.c and udp.c as it doesn't need a fully
> initialiazed IPv4 header, only protocol, tot_len, saddr and daddr.
>
> Signed-off-by: Laurent Vivier <lvivier@redhat.com>
> Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
> ---
>
> Notes:
> v4:
> - rebase
>
> v3:
> - function parameters provide tot_len, saddr, daddr and protocol
> rather than an iphdr
>
> v2:
> - use csum_ip4_header() from checksum.c
> - use code from tcp.c and udp.c in csum_ip4_header()
> - use "const struct iphfr *", check is not updated by the
> function but by the caller.
>
> checksum.c | 17 +++++++++++++----
> checksum.h | 3 ++-
> tap.c | 3 ++-
> tcp.c | 24 +++---------------------
> udp.c | 20 ++------------------
> 5 files changed, 22 insertions(+), 45 deletions(-)
>
> diff --git a/checksum.c b/checksum.c
> index 74e3742bc6f6..511b296a9a80 100644
> --- a/checksum.c
> +++ b/checksum.c
> @@ -57,6 +57,7 @@
> #include <linux/icmpv6.h>
>
> #include "util.h"
> +#include "ip.h"
> #include "checksum.h"
>
> /* Checksums are optional for UDP over IPv4, so we usually just set
> @@ -116,13 +117,21 @@ uint16_t csum_fold(uint32_t sum)
> uint16_t csum(const void *buf, size_t len, uint32_t init);
>
> /**
> - * csum_ip4_header() - Calculate and set IPv4 header checksum
> + * csum_ip4_header() - Calculate IPv4 header checksum
> * @ip4h: IPv4 header
Function comment needs to be updated for the new parameters. In
particular it needs to note that tot_len, saddr and daddr are all
passed in network order.
As noted elsewhere, I kind of hate passing non-host-endian values in
plain integer types, but I can see why doing otherwise here would be
very awkward.
> */
> -void csum_ip4_header(struct iphdr *ip4h)
> +uint16_t csum_ip4_header(uint16_t tot_len, uint8_t protocol,
> + uint32_t saddr, uint32_t daddr)
> {
> - ip4h->check = 0;
> - ip4h->check = csum(ip4h, (size_t)ip4h->ihl * 4, 0);
> + uint32_t sum = L2_BUF_IP4_PSUM(protocol);
> +
> + sum += tot_len;
> + sum += (saddr >> 16) & 0xffff;
> + sum += saddr & 0xffff;
> + sum += (daddr >> 16) & 0xffff;
> + sum += daddr & 0xffff;
> +
> + return ~csum_fold(sum);
> }
>
> /**
> diff --git a/checksum.h b/checksum.h
> index dfa705a04a24..92db73612b6e 100644
> --- a/checksum.h
> +++ b/checksum.h
> @@ -13,7 +13,8 @@ struct icmp6hdr;
> uint32_t sum_16b(const void *buf, size_t len);
> uint16_t csum_fold(uint32_t sum);
> uint16_t csum_unaligned(const void *buf, size_t len, uint32_t init);
> -void csum_ip4_header(struct iphdr *ip4h);
> +uint16_t csum_ip4_header(uint16_t tot_len, uint8_t protocol,
> + uint32_t saddr, uint32_t daddr);
> void csum_udp4(struct udphdr *udp4hr,
> struct in_addr saddr, struct in_addr daddr,
> const void *payload, size_t len);
> diff --git a/tap.c b/tap.c
> index d35d8944fc41..d4649f0167ab 100644
> --- a/tap.c
> +++ b/tap.c
> @@ -161,7 +161,8 @@ static void *tap_push_ip4h(char *buf, struct in_addr src, struct in_addr dst,
> ip4h->protocol = proto;
> ip4h->saddr = src.s_addr;
> ip4h->daddr = dst.s_addr;
> - csum_ip4_header(ip4h);
> + ip4h->check = csum_ip4_header(ip4h->tot_len, proto,
> + src.s_addr, dst.s_addr);
> return ip4h + 1;
> }
>
> diff --git a/tcp.c b/tcp.c
> index e0588f92e65f..ea0802c6b102 100644
> --- a/tcp.c
> +++ b/tcp.c
> @@ -935,23 +935,6 @@ static void tcp_sock_set_bufsize(const struct ctx *c, int s)
> trace("TCP: failed to set SO_SNDBUF to %i", v);
> }
>
> -/**
> - * tcp_update_check_ip4() - Update IPv4 with variable parts from stored one
> - * @buf: L2 packet buffer with final IPv4 header
> - */
> -static void tcp_update_check_ip4(struct tcp4_l2_buf_t *buf)
> -{
> - uint32_t sum = L2_BUF_IP4_PSUM(IPPROTO_TCP);
> -
> - sum += buf->iph.tot_len;
> - sum += (buf->iph.saddr >> 16) & 0xffff;
> - sum += buf->iph.saddr & 0xffff;
> - sum += (buf->iph.daddr >> 16) & 0xffff;
> - sum += buf->iph.daddr & 0xffff;
> -
> - buf->iph.check = (uint16_t)~csum_fold(sum);
> -}
> -
> /**
> * tcp_update_check_tcp4() - Update TCP checksum from stored one
> * @buf: L2 packet buffer with final IPv4 header
> @@ -1394,10 +1377,9 @@ do { \
> b->iph.saddr = a4->s_addr;
> b->iph.daddr = c->ip4.addr_seen.s_addr;
>
> - if (check)
> - b->iph.check = *check;
> - else
> - tcp_update_check_ip4(b);
> + b->iph.check = check ? *check :
> + csum_ip4_header(b->iph.tot_len, IPPROTO_TCP,
> + b->iph.saddr, b->iph.daddr);
>
> SET_TCP_HEADER_COMMON_V4_V6(b, conn, seq);
>
> diff --git a/udp.c b/udp.c
> index 26774df7018c..d517c99dcc69 100644
> --- a/udp.c
> +++ b/udp.c
> @@ -275,23 +275,6 @@ static void udp_invert_portmap(struct udp_fwd_ports *fwd)
> }
> }
>
> -/**
> - * udp_update_check4() - Update checksum with variable parts from stored one
> - * @buf: L2 packet buffer with final IPv4 header
> - */
> -static void udp_update_check4(struct udp4_l2_buf_t *buf)
> -{
> - uint32_t sum = L2_BUF_IP4_PSUM(IPPROTO_UDP);
> -
> - sum += buf->iph.tot_len;
> - sum += (buf->iph.saddr >> 16) & 0xffff;
> - sum += buf->iph.saddr & 0xffff;
> - sum += (buf->iph.daddr >> 16) & 0xffff;
> - sum += buf->iph.daddr & 0xffff;
> -
> - buf->iph.check = (uint16_t)~csum_fold(sum);
> -}
> -
> /**
> * udp_update_l2_buf() - Update L2 buffers with Ethernet and IPv4 addresses
> * @eth_d: Ethernet destination address, NULL if unchanged
> @@ -619,7 +602,8 @@ static size_t udp_update_hdr4(const struct ctx *c, int n, in_port_t dstport,
> b->iph.saddr = src->s_addr;
> }
>
> - udp_update_check4(b);
> + b->iph.check = csum_ip4_header(b->iph.tot_len, IPPROTO_UDP,
> + b->iph.saddr, b->iph.daddr);
> b->uh.source = b->s_in.sin_port;
> b->uh.dest = htons(dstport);
> b->uh.len = htons(udp4_l2_mh_sock[n].msg_len + sizeof(b->uh));
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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next prev parent reply other threads:[~2024-02-29 23:42 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-02-29 16:59 [PATCH v4 0/8] Add vhost-user support to passt (part 1) Laurent Vivier
2024-02-29 16:59 ` [PATCH v4 1/8] pcap: add pcap_iov() Laurent Vivier
2024-02-29 23:16 ` David Gibson
2024-02-29 16:59 ` [PATCH v4 2/8] checksum: align buffers Laurent Vivier
2024-02-29 16:59 ` [PATCH v4 3/8] checksum: add csum_iov() Laurent Vivier
2024-02-29 16:59 ` [PATCH v4 4/8] util: move IP stuff from util.[ch] to ip.[ch] Laurent Vivier
2024-02-29 23:19 ` David Gibson
2024-03-01 12:06 ` Laurent Vivier
2024-02-29 16:59 ` [PATCH v4 5/8] checksum: use csum_ip4_header() in udp.c and tcp.c Laurent Vivier
2024-02-29 23:25 ` David Gibson [this message]
2024-03-01 12:31 ` Laurent Vivier
2024-02-29 16:59 ` [PATCH v4 6/8] checksum: introduce functions to compute the header part checksum for TCP/UDP Laurent Vivier
2024-02-29 23:42 ` David Gibson
2024-02-29 16:59 ` [PATCH v4 7/8] tap: make tap_update_mac() generic Laurent Vivier
2024-02-29 16:59 ` [PATCH v4 8/8] tcp: Introduce ipv4_fill_headers()/ipv6_fill_headers() Laurent Vivier
2024-02-29 23:54 ` David Gibson
2024-03-03 13:50 ` Laurent Vivier
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