Re: [PATCH 06/24] ip: move duplicate IPv4 checksum function to ip.h

[David Gibson <david@gibson.dropbear.id.au>]

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On Fri, Feb 02, 2024 at 03:11:33PM +0100, Laurent Vivier wrote:
> We can find the same function to compute the IPv4 header
> checksum in tcp.c and udp.c
> 
> Signed-off-by: Laurent Vivier <lvivier@redhat.com>

Reviewed-by: David Gibson <david@gibson.dropbear.id.au>

Nice clean up.

> ---
>  ip.h  | 14 ++++++++++++++
>  tcp.c | 23 ++---------------------
>  udp.c | 19 +------------------
>  3 files changed, 17 insertions(+), 39 deletions(-)
> 
> diff --git a/ip.h b/ip.h
> index b2e08bc049f3..ff7902c45a95 100644
> --- a/ip.h
> +++ b/ip.h
> @@ -9,6 +9,8 @@
>  #include <netinet/ip.h>
>  #include <netinet/ip6.h>
>  
> +#include "checksum.h"
> +
>  #define IN4_IS_ADDR_UNSPECIFIED(a) \
>  	((a)->s_addr == htonl_constant(INADDR_ANY))
>  #define IN4_IS_ADDR_BROADCAST(a) \
> @@ -83,4 +85,16 @@ struct ipv6_opt_hdr {
>  
>  char *ipv6_l4hdr(const struct pool *p, int idx, size_t offset, uint8_t *proto,
>  		 size_t *dlen);
> +static inline uint16_t ipv4_hdr_checksum(struct iphdr *iph, int proto)
> +{
> +	uint32_t sum = L2_BUF_IP4_PSUM(proto);
> +
> +	sum += iph->tot_len;
> +	sum += (iph->saddr >> 16) & 0xffff;
> +	sum += iph->saddr & 0xffff;
> +	sum += (iph->daddr >> 16) & 0xffff;
> +	sum += iph->daddr & 0xffff;
> +
> +	return ~csum_fold(sum);
> +}
>  #endif /* IP_H */
> diff --git a/tcp.c b/tcp.c
> index 4c9c5fb51c60..293ab12d8c21 100644
> --- a/tcp.c
> +++ b/tcp.c
> @@ -934,23 +934,6 @@ 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
> @@ -1393,10 +1376,8 @@ 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 :
> +				       ipv4_hdr_checksum(&b->iph, IPPROTO_TCP);
>  
>  		SET_TCP_HEADER_COMMON_V4_V6(b, conn, seq);
>  
> diff --git a/udp.c b/udp.c
> index d514c864ab5b..6f867df81c05 100644
> --- a/udp.c
> +++ b/udp.c
> @@ -270,23 +270,6 @@ static void udp_invert_portmap(struct udp_port_fwd *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
> @@ -614,7 +597,7 @@ static size_t udp_update_hdr4(const struct ctx *c, int n, in_port_t dstport,
>  		b->iph.saddr = b->s_in.sin_addr.s_addr;
>  	}
>  
> -	udp_update_check4(b);
> +	b->iph.check = ipv4_hdr_checksum(&b->iph, IPPROTO_UDP);
>  	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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