Re: [PATCH 14/24] udp: move udpX_l2_buf_t and udpX_l2_mh_sock out of udp_update_hdrX()

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

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On Fri, Feb 02, 2024 at 03:11:41PM +0100, Laurent Vivier wrote:

Commit message please.

> Signed-off-by: Laurent Vivier <lvivier@redhat.com>
> ---
>  udp.c | 126 ++++++++++++++++++++++++++++++++++------------------------
>  1 file changed, 73 insertions(+), 53 deletions(-)
> 
> diff --git a/udp.c b/udp.c
> index db635742319b..77168fb0a2af 100644
> --- a/udp.c
> +++ b/udp.c
> @@ -562,47 +562,48 @@ static void udp_splice_sendfrom(const struct ctx *c, unsigned start, unsigned n,
>   *
>   * Return: size of tap frame with headers
>   */
> -static size_t udp_update_hdr4(const struct ctx *c, int n, in_port_t dstport,
> -			      const struct timespec *now)
> +static size_t udp_update_hdr4(const struct ctx *c, struct iphdr *iph,
> +			      size_t data_len, struct sockaddr_in *s_in,
> +			      in_port_t dstport, const struct timespec *now)

This is a much better interface, nice change.

>  {
> -	struct udp4_l2_buf_t *b = &udp4_l2_buf[n];
> +	struct udphdr *uh = (struct udphdr *)(iph + 1);
>  	in_port_t src_port;
>  	size_t ip_len;
>  
> -	ip_len = udp4_l2_mh_sock[n].msg_len + sizeof(b->iph) + sizeof(b->uh);
> +	ip_len = data_len + sizeof(struct iphdr) + sizeof(struct udphdr);
>  
> -	b->iph.tot_len = htons(ip_len);
> -	b->iph.daddr = c->ip4.addr_seen.s_addr;
> +	iph->tot_len = htons(ip_len);
> +	iph->daddr = c->ip4.addr_seen.s_addr;
>  
> -	src_port = ntohs(b->s_in.sin_port);
> +	src_port = ntohs(s_in->sin_port);
>  
>  	if (!IN4_IS_ADDR_UNSPECIFIED(&c->ip4.dns_match) &&
> -	    IN4_ARE_ADDR_EQUAL(&b->s_in.sin_addr, &c->ip4.dns_host) &&
> +	    IN4_ARE_ADDR_EQUAL(&s_in->sin_addr, &c->ip4.dns_host) &&
>  	    src_port == 53) {
> -		b->iph.saddr = c->ip4.dns_match.s_addr;
> -	} else if (IN4_IS_ADDR_LOOPBACK(&b->s_in.sin_addr) ||
> -		   IN4_IS_ADDR_UNSPECIFIED(&b->s_in.sin_addr)||
> -		   IN4_ARE_ADDR_EQUAL(&b->s_in.sin_addr, &c->ip4.addr_seen)) {
> -		b->iph.saddr = c->ip4.gw.s_addr;
> +		iph->saddr = c->ip4.dns_match.s_addr;
> +	} else if (IN4_IS_ADDR_LOOPBACK(&s_in->sin_addr) ||
> +		   IN4_IS_ADDR_UNSPECIFIED(&s_in->sin_addr)||
> +		   IN4_ARE_ADDR_EQUAL(&s_in->sin_addr, &c->ip4.addr_seen)) {
> +		iph->saddr = c->ip4.gw.s_addr;
>  		udp_tap_map[V4][src_port].ts = now->tv_sec;
>  		udp_tap_map[V4][src_port].flags |= PORT_LOCAL;
>  
> -		if (IN4_ARE_ADDR_EQUAL(&b->s_in.sin_addr.s_addr, &c->ip4.addr_seen))
> +		if (IN4_ARE_ADDR_EQUAL(&s_in->sin_addr.s_addr, &c->ip4.addr_seen))
>  			udp_tap_map[V4][src_port].flags &= ~PORT_LOOPBACK;
>  		else
>  			udp_tap_map[V4][src_port].flags |= PORT_LOOPBACK;
>  
>  		bitmap_set(udp_act[V4][UDP_ACT_TAP], src_port);
>  	} else {
> -		b->iph.saddr = b->s_in.sin_addr.s_addr;
> +		iph->saddr = s_in->sin_addr.s_addr;
>  	}
>  
> -	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));
> +	iph->check = ipv4_hdr_checksum(iph, IPPROTO_UDP);
> +	uh->source = s_in->sin_port;
> +	uh->dest = htons(dstport);
> +	uh->len= htons(data_len + sizeof(struct udphdr));
>  
> -	return tap_iov_len(c, &b->taph, ip_len);
> +	return ip_len;
>  }
>  
>  /**
> @@ -614,38 +615,39 @@ static size_t udp_update_hdr4(const struct ctx *c, int n, in_port_t dstport,
>   *
>   * Return: size of tap frame with headers
>   */
> -static size_t udp_update_hdr6(const struct ctx *c, int n, in_port_t dstport,
> -			      const struct timespec *now)
> +static size_t udp_update_hdr6(const struct ctx *c, struct ipv6hdr *ip6h,
> +			      size_t data_len, struct sockaddr_in6 *s_in6,
> +			      in_port_t dstport, const struct timespec *now)
>  {
> -	struct udp6_l2_buf_t *b = &udp6_l2_buf[n];
> +	struct udphdr *uh = (struct udphdr *)(ip6h + 1);
>  	struct in6_addr *src;
>  	in_port_t src_port;
>  	size_t ip_len;
>  
> -	src = &b->s_in6.sin6_addr;
> -	src_port = ntohs(b->s_in6.sin6_port);
> +	src = &s_in6->sin6_addr;
> +	src_port = ntohs(s_in6->sin6_port);
>  
> -	ip_len = udp6_l2_mh_sock[n].msg_len + sizeof(b->ip6h) + sizeof(b->uh);
> +	ip_len = data_len + sizeof(struct ipv6hdr) + sizeof(struct udphdr);
>  
> -	b->ip6h.payload_len = htons(udp6_l2_mh_sock[n].msg_len + sizeof(b->uh));
> +	ip6h->payload_len = htons(data_len + sizeof(struct udphdr));
>  
>  	if (IN6_IS_ADDR_LINKLOCAL(src)) {
> -		b->ip6h.daddr = c->ip6.addr_ll_seen;
> -		b->ip6h.saddr = b->s_in6.sin6_addr;
> +		ip6h->daddr = c->ip6.addr_ll_seen;
> +		ip6h->saddr = s_in6->sin6_addr;
>  	} else if (!IN6_IS_ADDR_UNSPECIFIED(&c->ip6.dns_match) &&
>  		   IN6_ARE_ADDR_EQUAL(src, &c->ip6.dns_host) &&
>  		   src_port == 53) {
> -		b->ip6h.daddr = c->ip6.addr_seen;
> -		b->ip6h.saddr = c->ip6.dns_match;
> +		ip6h->daddr = c->ip6.addr_seen;
> +		ip6h->saddr = c->ip6.dns_match;
>  	} else if (IN6_IS_ADDR_LOOPBACK(src)			||
>  		   IN6_ARE_ADDR_EQUAL(src, &c->ip6.addr_seen)	||
>  		   IN6_ARE_ADDR_EQUAL(src, &c->ip6.addr)) {
> -		b->ip6h.daddr = c->ip6.addr_ll_seen;
> +		ip6h->daddr = c->ip6.addr_ll_seen;
>  
>  		if (IN6_IS_ADDR_LINKLOCAL(&c->ip6.gw))
> -			b->ip6h.saddr = c->ip6.gw;
> +			ip6h->saddr = c->ip6.gw;
>  		else
> -			b->ip6h.saddr = c->ip6.addr_ll;
> +			ip6h->saddr = c->ip6.addr_ll;
>  
>  		udp_tap_map[V6][src_port].ts = now->tv_sec;
>  		udp_tap_map[V6][src_port].flags |= PORT_LOCAL;
> @@ -662,20 +664,20 @@ static size_t udp_update_hdr6(const struct ctx *c, int n, in_port_t dstport,
>  
>  		bitmap_set(udp_act[V6][UDP_ACT_TAP], src_port);
>  	} else {
> -		b->ip6h.daddr = c->ip6.addr_seen;
> -		b->ip6h.saddr = b->s_in6.sin6_addr;
> +		ip6h->daddr = c->ip6.addr_seen;
> +		ip6h->saddr = s_in6->sin6_addr;
>  	}
>  
> -	b->uh.source = b->s_in6.sin6_port;
> -	b->uh.dest = htons(dstport);
> -	b->uh.len = b->ip6h.payload_len;
> -	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;
> +	uh->source = s_in6->sin6_port;
> +	uh->dest = htons(dstport);
> +	uh->len = ip6h->payload_len;
> +	uh->check = csum(uh, ntohs(ip6h->payload_len),
> +			 proto_ipv6_header_checksum(ip6h, IPPROTO_UDP));
> +	ip6h->version = 6;
> +	ip6h->nexthdr = IPPROTO_UDP;
> +	ip6h->hop_limit = 255;
>  
> -	return tap_iov_len(c, &b->taph, ip_len);
> +	return ip_len;
>  }
>  
>  /**
> @@ -689,6 +691,11 @@ static size_t udp_update_hdr6(const struct ctx *c, int n, in_port_t dstport,
>   *
>   * Return: size of tap frame with headers
>   */
> +#pragma GCC diagnostic push
> +/* ignore unaligned pointer value warning for &udp6_l2_buf[i].ip6h and 
> + * &udp4_l2_buf[i].iph

I feel like this needs more explanation: why is it unaligned?  why
can't we make it aligned?  why is it safe to ignore the warning?

> + */
> +#pragma GCC diagnostic ignored "-Waddress-of-packed-member"
>  static void udp_tap_send(const struct ctx *c,
>  			 unsigned int start, unsigned int n,
>  			 in_port_t dstport, bool v6, const struct timespec *now)
> @@ -702,18 +709,31 @@ static void udp_tap_send(const struct ctx *c,
>  		tap_iov = udp4_l2_iov_tap;
>  
>  	for (i = start; i < start + n; i++) {
> -		size_t buf_len;
> -
> -		if (v6)
> -			buf_len = udp_update_hdr6(c, i, dstport, now);
> -		else
> -			buf_len = udp_update_hdr4(c, i, dstport, now);
> -
> -		tap_iov[i].iov_len = buf_len;
> +		size_t ip_len;
> +
> +		if (v6) {
> +			ip_len = udp_update_hdr6(c, &udp6_l2_buf[i].ip6h,
> +						 udp6_l2_mh_sock[i].msg_len,
> +						 &udp6_l2_buf[i].s_in6, dstport,
> +						 now);
> +			tap_iov[i].iov_len = tap_iov_len(c,
> +							 &udp6_l2_buf[i].taph,
> +							 ip_len);
> +		} else {
> +			ip_len = udp_update_hdr4(c, &udp4_l2_buf[i].iph,
> +						 udp4_l2_mh_sock[i].msg_len,
> +						 &udp4_l2_buf[i].s_in,
> +						 dstport, now);
> +
> +			tap_iov[i].iov_len = tap_iov_len(c,
> +							 &udp4_l2_buf[i].taph,
> +							 ip_len);
> +		}
>  	}
>  
>  	tap_send_frames(c, tap_iov + start, n);
>  }
> +#pragma GCC diagnostic pop
>  
>  /**
>   * udp_sock_handler() - Handle new data from socket

-- 
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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