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From: David Gibson <david@gibson.dropbear.id.au>
To: Laurent Vivier <lvivier@redhat.com>
Cc: passt-dev@passt.top
Subject: Re: [PATCH 07/24] ip: introduce functions to compute the header part checksum for TCP/UDP
Date: Mon, 5 Feb 2024 17:20:49 +1100	[thread overview]
Message-ID: <ZcB-QagPCyZhD9OH@zatzit> (raw)
In-Reply-To: <20240202141151.3762941-8-lvivier@redhat.com>

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On Fri, Feb 02, 2024 at 03:11:34PM +0100, Laurent Vivier wrote:
> The TCP and UDP checksums are computed using the data in the TCP/UDP
> payload but also some informations in the IP header (protocol,
> length, source and destination addresses).
> 
> We add two functions, proto_ipv4_header_checksum() and
> proto_ipv6_header_checksum(), to compute the checksum of the IP
> header part.
> 
> Signed-off-by: Laurent Vivier <lvivier@redhat.com>
> ---
>  ip.h  | 24 ++++++++++++++++++++++++
>  tcp.c | 40 +++++++++++++++-------------------------
>  udp.c |  6 ++----
>  3 files changed, 41 insertions(+), 29 deletions(-)
> 
> diff --git a/ip.h b/ip.h
> index ff7902c45a95..87cb8dd21d2e 100644
> --- a/ip.h
> +++ b/ip.h
> @@ -97,4 +97,28 @@ static inline uint16_t ipv4_hdr_checksum(struct iphdr *iph, int proto)
>  
>  	return ~csum_fold(sum);
>  }
> +

Function comment.

> +static inline uint32_t proto_ipv4_header_checksum(struct iphdr *iph, int proto)

Logic looks fine, but I don't love the name, since this isn't a
complete checksum, but just an intermediate result we use to compute
the final checksum.  Maybe use the 'psum' name we have in some other
places for "partial sum".

> +{
> +	uint32_t sum = htons(proto);
> +
> +	sum += (iph->saddr >> 16) & 0xffff;
> +	sum += iph->saddr & 0xffff;
> +	sum += (iph->daddr >> 16) & 0xffff;
> +	sum += iph->daddr & 0xffff;
> +	sum += htons(ntohs(iph->tot_len) - 20);
> +
> +	return sum;
> +}
> +
> +static inline uint32_t proto_ipv6_header_checksum(struct ipv6hdr *ip6h,
> +						  int proto)
> +{
> +	uint32_t sum = htons(proto) + ip6h->payload_len;
> +
> +	sum += sum_16b(&ip6h->saddr, sizeof(ip6h->saddr));
> +	sum += sum_16b(&ip6h->daddr, sizeof(ip6h->daddr));
> +
> +	return sum;
> +}
>  #endif /* IP_H */
> diff --git a/tcp.c b/tcp.c
> index 293ab12d8c21..2fd6bc2eda53 100644
> --- a/tcp.c
> +++ b/tcp.c
> @@ -938,39 +938,25 @@ static void tcp_sock_set_bufsize(const struct ctx *c, int s)
>   * tcp_update_check_tcp4() - Update TCP checksum from stored one
>   * @buf:	L2 packet buffer with final IPv4 header
>   */
> -static void tcp_update_check_tcp4(struct tcp4_l2_buf_t *buf)
> +static uint16_t tcp_update_check_tcp4(struct iphdr *iph)
>  {
> -	uint16_t tlen = ntohs(buf->iph.tot_len) - 20;
> -	uint32_t sum = htons(IPPROTO_TCP);
> +	struct tcphdr *th = (void *)(iph + 1);
> +	uint16_t tlen = ntohs(iph->tot_len) - 20;
> +	uint32_t sum = proto_ipv4_header_checksum(iph, IPPROTO_TCP);
>  
> -	sum += (buf->iph.saddr >> 16) & 0xffff;
> -	sum += buf->iph.saddr & 0xffff;
> -	sum += (buf->iph.daddr >> 16) & 0xffff;
> -	sum += buf->iph.daddr & 0xffff;
> -	sum += htons(ntohs(buf->iph.tot_len) - 20);
> -
> -	buf->th.check = 0;
> -	buf->th.check = csum(&buf->th, tlen, sum);
> +	return csum(th, tlen, sum);
>  }
>  
>  /**
>   * tcp_update_check_tcp6() - Calculate TCP checksum for IPv6
>   * @buf:	L2 packet buffer with final IPv6 header
>   */
> -static void tcp_update_check_tcp6(struct tcp6_l2_buf_t *buf)
> +static uint16_t tcp_update_check_tcp6(struct ipv6hdr *ip6h)
>  {
> -	int len = ntohs(buf->ip6h.payload_len) + sizeof(struct ipv6hdr);
> -
> -	buf->ip6h.hop_limit = IPPROTO_TCP;
> -	buf->ip6h.version = 0;
> -	buf->ip6h.nexthdr = 0;
> +	struct tcphdr *th = (void *)(ip6h + 1);
> +	uint32_t sum = proto_ipv6_header_checksum(ip6h, IPPROTO_TCP);
>  
> -	buf->th.check = 0;
> -	buf->th.check = csum(&buf->ip6h, len, 0);
> -
> -	buf->ip6h.hop_limit = 255;
> -	buf->ip6h.version = 6;
> -	buf->ip6h.nexthdr = IPPROTO_TCP;
> +	return csum(th, ntohs(ip6h->payload_len), sum);
>  }
>  
>  /**
> @@ -1381,7 +1367,7 @@ do {									\
>  
>  		SET_TCP_HEADER_COMMON_V4_V6(b, conn, seq);
>  
> -		tcp_update_check_tcp4(b);
> +		b->th.check = tcp_update_check_tcp4(&b->iph);
>  
>  		tlen = tap_iov_len(c, &b->taph, ip_len);
>  	} else {
> @@ -1400,7 +1386,11 @@ do {									\
>  
>  		SET_TCP_HEADER_COMMON_V4_V6(b, conn, seq);
>  
> -		tcp_update_check_tcp6(b);
> +		b->th.check = tcp_update_check_tcp6(&b->ip6h);
> +
> +		b->ip6h.hop_limit = 255;
> +		b->ip6h.version = 6;
> +		b->ip6h.nexthdr = IPPROTO_TCP;
>  
>  		b->ip6h.flow_lbl[0] = (conn->sock >> 16) & 0xf;
>  		b->ip6h.flow_lbl[1] = (conn->sock >> 8) & 0xff;
> diff --git a/udp.c b/udp.c
> index 6f867df81c05..96b4e6ca9a85 100644
> --- a/udp.c
> +++ b/udp.c
> @@ -669,10 +669,8 @@ static size_t udp_update_hdr6(const struct ctx *c, int n, in_port_t dstport,
>  	b->uh.source = b->s_in6.sin6_port;
>  	b->uh.dest = htons(dstport);
>  	b->uh.len = b->ip6h.payload_len;
> -
> -	b->ip6h.hop_limit = IPPROTO_UDP;
> -	b->ip6h.version = b->ip6h.nexthdr = b->uh.check = 0;
> -	b->uh.check = csum(&b->ip6h, ip_len, 0);
> +	b->uh.check = csum(&b->uh, ntohs(b->ip6h.payload_len),
> +			 proto_ipv6_header_checksum(&b->ip6h, IPPROTO_UDP));
>  	b->ip6h.version = 6;
>  	b->ip6h.nexthdr = IPPROTO_UDP;
>  	b->ip6h.hop_limit = 255;

-- 
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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  reply	other threads:[~2024-02-05  6:21 UTC|newest]

Thread overview: 83+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-02-02 14:11 [PATCH 00/24] Add vhost-user support to passt Laurent Vivier
2024-02-02 14:11 ` [PATCH 01/24] iov: add some functions to manage iovec Laurent Vivier
2024-02-05  5:57   ` David Gibson
2024-02-06 14:28     ` Laurent Vivier
2024-02-07  1:01       ` David Gibson
2024-02-07 10:00         ` Laurent Vivier
2024-02-06 16:10   ` Stefano Brivio
2024-02-07 14:02     ` Laurent Vivier
2024-02-07 14:57       ` Stefano Brivio
2024-02-02 14:11 ` [PATCH 02/24] pcap: add pcap_iov() Laurent Vivier
2024-02-05  6:25   ` David Gibson
2024-02-06 16:10   ` Stefano Brivio
2024-02-02 14:11 ` [PATCH 03/24] checksum: align buffers Laurent Vivier
2024-02-05  6:02   ` David Gibson
2024-02-07  9:01     ` Stefano Brivio
2024-02-02 14:11 ` [PATCH 04/24] checksum: add csum_iov() Laurent Vivier
2024-02-05  6:07   ` David Gibson
2024-02-07  9:02   ` Stefano Brivio
2024-02-02 14:11 ` [PATCH 05/24] util: move IP stuff from util.[ch] to ip.[ch] Laurent Vivier
2024-02-05  6:13   ` David Gibson
2024-02-07  9:03     ` Stefano Brivio
2024-02-08  0:04       ` David Gibson
2024-02-02 14:11 ` [PATCH 06/24] ip: move duplicate IPv4 checksum function to ip.h Laurent Vivier
2024-02-05  6:16   ` David Gibson
2024-02-07 10:40   ` Stefano Brivio
2024-02-07 23:43     ` David Gibson
2024-02-02 14:11 ` [PATCH 07/24] ip: introduce functions to compute the header part checksum for TCP/UDP Laurent Vivier
2024-02-05  6:20   ` David Gibson [this message]
2024-02-07 10:41   ` Stefano Brivio
2024-02-02 14:11 ` [PATCH 08/24] tcp: extract buffer management from tcp_send_flag() Laurent Vivier
2024-02-06  0:24   ` David Gibson
2024-02-08 16:57   ` Stefano Brivio
2024-02-02 14:11 ` [PATCH 09/24] tcp: extract buffer management from tcp_conn_tap_mss() Laurent Vivier
2024-02-06  0:47   ` David Gibson
2024-02-08 16:59   ` Stefano Brivio
2024-02-02 14:11 ` [PATCH 10/24] tcp: rename functions that manage buffers Laurent Vivier
2024-02-06  1:48   ` David Gibson
2024-02-08 17:10     ` Stefano Brivio
2024-02-02 14:11 ` [PATCH 11/24] tcp: move buffers management functions to their own file Laurent Vivier
2024-02-02 14:11 ` [PATCH 12/24] tap: make tap_update_mac() generic Laurent Vivier
2024-02-06  1:49   ` David Gibson
2024-02-08 17:10     ` Stefano Brivio
2024-02-09  5:02       ` David Gibson
2024-02-02 14:11 ` [PATCH 13/24] tap: export pool_flush()/tapX_handler()/packet_add() Laurent Vivier
2024-02-02 14:29   ` Laurent Vivier
2024-02-06  1:52   ` David Gibson
2024-02-11 23:15   ` Stefano Brivio
2024-02-12  2:22     ` David Gibson
2024-02-02 14:11 ` [PATCH 14/24] udp: move udpX_l2_buf_t and udpX_l2_mh_sock out of udp_update_hdrX() Laurent Vivier
2024-02-06  1:59   ` David Gibson
2024-02-11 23:16   ` Stefano Brivio
2024-02-02 14:11 ` [PATCH 15/24] udp: rename udp_sock_handler() to udp_buf_sock_handler() Laurent Vivier
2024-02-06  2:14   ` David Gibson
2024-02-11 23:17     ` Stefano Brivio
2024-02-02 14:11 ` [PATCH 16/24] packet: replace struct desc by struct iovec Laurent Vivier
2024-02-06  2:25   ` David Gibson
2024-02-11 23:18     ` Stefano Brivio
2024-02-02 14:11 ` [PATCH 17/24] vhost-user: compare mode MODE_PASTA and not MODE_PASST Laurent Vivier
2024-02-06  2:29   ` David Gibson
2024-02-02 14:11 ` [PATCH 18/24] vhost-user: introduce virtio API Laurent Vivier
2024-02-06  3:51   ` David Gibson
2024-02-11 23:18     ` Stefano Brivio
2024-02-12  2:26       ` David Gibson
2024-02-02 14:11 ` [PATCH 19/24] vhost-user: introduce vhost-user API Laurent Vivier
2024-02-07  2:13   ` David Gibson
2024-02-02 14:11 ` [PATCH 20/24] vhost-user: add vhost-user Laurent Vivier
2024-02-07  2:40   ` David Gibson
2024-02-11 23:19     ` Stefano Brivio
2024-02-12  2:47       ` David Gibson
2024-02-13 15:22         ` Stefano Brivio
2024-02-14  2:05           ` David Gibson
2024-02-11 23:19   ` Stefano Brivio
2024-02-12  2:49     ` David Gibson
2024-02-12 10:02       ` Laurent Vivier
2024-02-12 16:56         ` Stefano Brivio
2024-02-02 14:11 ` [PATCH 21/24] vhost-user: use guest buffer directly in vu_handle_tx() Laurent Vivier
2024-02-09  4:26   ` David Gibson
2024-02-02 14:11 ` [PATCH 22/24] tcp: vhost-user RX nocopy Laurent Vivier
2024-02-09  4:57   ` David Gibson
2024-02-02 14:11 ` [PATCH 23/24] udp: " Laurent Vivier
2024-02-09  5:00   ` David Gibson
2024-02-02 14:11 ` [PATCH 24/24] vhost-user: remove tap_send_frames_vu() Laurent Vivier
2024-02-09  5:01   ` David Gibson

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