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udp: refactor UDP header update functions

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This commit refactors the udp_update_hdr4() and udp_update_hdr6() functions
to improve code portability by replacing the udp_meta_t parameter with
more specific parameters for the IPv4 and IPv6 headers (iphdr/ipv6hdr)
and the source socket address (sockaddr_in/sockaddr_in6).
It also moves the tap_hdr_update() function call inside the udp_tap_send()
function not to have to pass the TAP header to udp_update_hdr4() and
udp_update_hdr6()

This refactor reduces complexity by making the functions more modular and
ensuring that each function operates on more narrowly scoped data structures.
This will facilitate future backend introduction like vhost-user.

Signed-off-by: Laurent Vivier <lvivier@redhat.com>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
This commit is contained in:
Laurent Vivier 2024-06-13 14:36:51 +02:00 committed by Stefano Brivio
parent 9ecf7fedc5
commit e7ac995217
1 changed files with 34 additions and 26 deletions
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60
udp.c
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@ -555,7 +555,8 @@ static void udp_splice_sendfrom(const struct ctx *c, unsigned start, unsigned n,
/**
* udp_update_hdr4() - Update headers for one IPv4 datagram
* @c: Execution context
* @bm: Pointer to udp_meta_t to update
* @ip4h: Pre-filled IPv4 header (except for tot_len and saddr)
* @s_in: Source socket address, filled in by recvmmsg()
* @bp: Pointer to udp_payload_t to update
* @dstport: Destination port number
* @dlen: Length of UDP payload
@ -564,15 +565,16 @@ static void udp_splice_sendfrom(const struct ctx *c, unsigned start, unsigned n,
* Return: size of IPv4 payload (UDP header + data)
*/
static size_t udp_update_hdr4(const struct ctx *c,
struct udp_meta_t *bm, struct udp_payload_t *bp,
struct iphdr *ip4h, const struct sockaddr_in *s_in,
struct udp_payload_t *bp,
in_port_t dstport, size_t dlen,
const struct timespec *now)
{
in_port_t srcport = ntohs(bm->s_in.sa4.sin_port);
const struct in_addr dst = c->ip4.addr_seen;
struct in_addr src = bm->s_in.sa4.sin_addr;
in_port_t srcport = ntohs(s_in->sin_port);
size_t l4len = dlen + sizeof(bp->uh);
size_t l3len = l4len + sizeof(bm->ip4h);
size_t l3len = l4len + sizeof(*ip4h);
struct in_addr src = s_in->sin_addr;
if (!IN4_IS_ADDR_UNSPECIFIED(&c->ip4.dns_match) &&
IN4_ARE_ADDR_EQUAL(&src, &c->ip4.dns_host) && srcport == 53 &&
@ -593,24 +595,24 @@ static size_t udp_update_hdr4(const struct ctx *c,
src = c->ip4.gw;
}
bm->ip4h.tot_len = htons(l3len);
bm->ip4h.daddr = dst.s_addr;
bm->ip4h.saddr = src.s_addr;
bm->ip4h.check = csum_ip4_header(l3len, IPPROTO_UDP, src, dst);
ip4h->tot_len = htons(l3len);
ip4h->daddr = dst.s_addr;
ip4h->saddr = src.s_addr;
ip4h->check = csum_ip4_header(l3len, IPPROTO_UDP, src, dst);
bp->uh.source = bm->s_in.sa4.sin_port;
bp->uh.source = s_in->sin_port;
bp->uh.dest = htons(dstport);
bp->uh.len = htons(l4len);
csum_udp4(&bp->uh, src, dst, bp->data, dlen);
tap_hdr_update(&bm->taph, l3len + sizeof(udp4_eth_hdr));
return l4len;
}
/**
* udp_update_hdr6() - Update headers for one IPv6 datagram
* @c: Execution context
* @bm: Pointer to udp_meta_t to update
* @ip6h: Pre-filled IPv6 header (except for payload_len and addresses)
* @s_in: Source socket address, filled in by recvmmsg()
* @bp: Pointer to udp_payload_t to update
* @dstport: Destination port number
* @dlen: Length of UDP payload
@ -619,13 +621,14 @@ static size_t udp_update_hdr4(const struct ctx *c,
* Return: size of IPv6 payload (UDP header + data)
*/
static size_t udp_update_hdr6(const struct ctx *c,
struct udp_meta_t *bm, struct udp_payload_t *bp,
struct ipv6hdr *ip6h, struct sockaddr_in6 *s_in6,
struct udp_payload_t *bp,
in_port_t dstport, size_t dlen,
const struct timespec *now)
{
const struct in6_addr *src = &bm->s_in.sa6.sin6_addr;
const struct in6_addr *src = &s_in6->sin6_addr;
const struct in6_addr *dst = &c->ip6.addr_seen;
in_port_t srcport = ntohs(bm->s_in.sa6.sin6_port);
in_port_t srcport = ntohs(s_in6->sin6_port);
uint16_t l4len = dlen + sizeof(bp->uh);
if (IN6_IS_ADDR_LINKLOCAL(src)) {
@ -662,19 +665,18 @@ static size_t udp_update_hdr6(const struct ctx *c,
}
bm->ip6h.payload_len = htons(l4len);
bm->ip6h.daddr = *dst;
bm->ip6h.saddr = *src;
bm->ip6h.version = 6;
bm->ip6h.nexthdr = IPPROTO_UDP;
bm->ip6h.hop_limit = 255;
ip6h->payload_len = htons(l4len);
ip6h->daddr = *dst;
ip6h->saddr = *src;
ip6h->version = 6;
ip6h->nexthdr = IPPROTO_UDP;
ip6h->hop_limit = 255;
bp->uh.source = bm->s_in.sa6.sin6_port;
bp->uh.source = s_in6->sin6_port;
bp->uh.dest = htons(dstport);
bp->uh.len = bm->ip6h.payload_len;
bp->uh.len = ip6h->payload_len;
csum_udp6(&bp->uh, src, dst, bp->data, dlen);
tap_hdr_update(&bm->taph, l4len + sizeof(bm->ip6h) + sizeof(udp6_eth_hdr));
return l4len;
}
@ -707,11 +709,17 @@ static void udp_tap_send(const struct ctx *c,
size_t l4len;
if (v6) {
l4len = udp_update_hdr6(c, bm, bp, dstport,
l4len = udp_update_hdr6(c, &bm->ip6h,
&bm->s_in.sa6, bp, dstport,
udp6_l2_mh_sock[i].msg_len, now);
tap_hdr_update(&bm->taph, l4len + sizeof(bm->ip6h) +
sizeof(udp6_eth_hdr));
} else {
l4len = udp_update_hdr4(c, bm, bp, dstport,
l4len = udp_update_hdr4(c, &bm->ip4h,
&bm->s_in.sa4, bp, dstport,
udp4_l2_mh_sock[i].msg_len, now);
tap_hdr_update(&bm->taph, l4len + sizeof(bm->ip4h) +
sizeof(udp4_eth_hdr));
}
tap_iov[i][UDP_IOV_PAYLOAD].iov_len = l4len;
}