On Sun, Feb 23, 2025 at 05:59:50PM -0500, Jon Maloy wrote:We will need to build the UDP header at other locations than in function tap_udp6_send(), so we break that part out to a separate function. Signed-off-by: Jon Maloy <jmaloy(a)redhat.com>Reviewed-by: David Gibson <david(a)gibson.dropbear.id.au> ...minus one nit.--- tap.c | 40 ++++++++++++++++++++++++++++++---------- tap.h | 4 ++++ 2 files changed, 34 insertions(+), 10 deletions(-) diff --git a/tap.c b/tap.c index 3daba28..380a7b9 100644 --- a/tap.c +++ b/tap.c @@ -266,7 +266,7 @@ static void *tap_push_ip6h(struct ipv6hdr *ip6h, } /** - * tap_udp6_send() - Send UDP over IPv6 packet + * tap_push_uh6() - Build UDPv6 header with checksum * @c: Execution context * @src: IPv6 source address * @sport: UDP source port @@ -276,19 +276,14 @@ static void *tap_push_ip6h(struct ipv6hdr *ip6h, * @in: UDP payload contents (not including UDP header) * @dlen: UDP payload length (not including UDP header) */ -void tap_udp6_send(const struct ctx *c, +void *tap_push_uh6(struct udphdr *uh, const struct in6_addr *src, in_port_t sport, const struct in6_addr *dst, in_port_t dport, - uint32_t flow, void *in, size_t dlen) + void *in, size_t dlen) { size_t l4len = dlen + sizeof(struct udphdr); - char buf[USHRT_MAX]; - struct ipv6hdr *ip6h = tap_push_l2h(c, buf, ETH_P_IPV6); - struct udphdr *uh = tap_push_ip6h(ip6h, src, dst, - l4len, IPPROTO_UDP, flow); - char *data = (char *)(uh + 1); const struct iovec iov = { - .iov_base = in, + .iov_base = (void *)in,'in' is already a void * so the cast is not necessary (even ignoring the fact that you can generall coerce to and from void * without a cast)..iov_len = dlen }; struct iov_tail payload = IOV_TAIL(&iov, 1, 0); @@ -297,8 +292,33 @@ void tap_udp6_send(const struct ctx *c, uh->dest = htons(dport); uh->len = htons(l4len); csum_udp6(uh, src, dst, &payload); - memcpy(data, in, dlen); + return uh + 1; +} + +/** + * tap_udp6_send() - Send UDP over IPv6 packet + * @c: Execution context + * @src: IPv6 source address + * @sport: UDP source port + * @dst: IPv6 destination address + * @dport: UDP destination port + * @flow: Flow label + * @in: UDP payload contents (not including UDP header) + * @dlen: UDP payload length (not including UDP header) + */ +void tap_udp6_send(const struct ctx *c, + const struct in6_addr *src, in_port_t sport, + const struct in6_addr *dst, in_port_t dport, + uint32_t flow, void *in, size_t dlen) +{ + size_t l4len = dlen + sizeof(struct udphdr); + char buf[USHRT_MAX]; + struct ipv6hdr *ip6h = tap_push_l2h(c, buf, ETH_P_IPV6); + struct udphdr *uh = tap_push_ip6h(ip6h, src, dst, + l4len, IPPROTO_UDP, flow); + char *data = tap_push_uh6(uh, src, sport, dst, dport, in, dlen); + memcpy(data, in, dlen); tap_send_single(c, buf, dlen + (data - buf)); } diff --git a/tap.h b/tap.h index 37da21d..b7b8cef 100644 --- a/tap.h +++ b/tap.h @@ -47,6 +47,10 @@ static inline void tap_hdr_update(struct tap_hdr *thdr, size_t l2len) void *tap_push_uh4(struct udphdr *uh, struct in_addr src, in_port_t sport, struct in_addr dst, in_port_t dport, const void *in, size_t dlen); +void *tap_push_uh6(struct udphdr *uh, + const struct in6_addr *src, in_port_t sport, + const struct in6_addr *dst, in_port_t dport, + void *in, size_t dlen); void *tap_push_ip4h(struct iphdr *ip4h, struct in_addr src, struct in_addr dst, size_t l4len, uint8_t proto); void tap_udp4_send(const struct ctx *c, struct in_addr src, in_port_t sport,-- David Gibson (he or they) | 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