On Wed, Feb 19, 2025 at 02:30:06PM -0500, Jon Maloy wrote:We will need to build the UDP header at other locations than in function tap_udp4_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>--- tap.c | 32 +++++++++++++++++++++++++------- tap.h | 6 +++++- 2 files changed, 30 insertions(+), 8 deletions(-) diff --git a/tap.c b/tap.c index dfe6dcf..95d64bf 100644 --- a/tap.c +++ b/tap.c @@ -162,7 +162,7 @@ static void *tap_push_ip4h(struct iphdr *ip4h, struct in_addr src, } /** - * tap_udp4_send() - Send UDP over IPv4 packet + * tap_push_uh4() - Build UDPv4 header with checksum * @c: Execution context * @src: IPv4 source address * @sport: UDP source port @@ -171,15 +171,11 @@ static void *tap_push_ip4h(struct iphdr *ip4h, struct in_addr src, * @in: UDP payload contents (not including UDP header) * @dlen: UDP payload length (not including UDP header) */ -void tap_udp4_send(const struct ctx *c, struct in_addr src, in_port_t sport, +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) { size_t l4len = dlen + sizeof(struct udphdr); - char buf[USHRT_MAX]; - struct iphdr *ip4h = tap_push_l2h(c, buf, ETH_P_IP); - struct udphdr *uh = tap_push_ip4h(ip4h, src, dst, l4len, IPPROTO_UDP); - char *data = (char *)(uh + 1); const struct iovec iov = { .iov_base = (void *)in, .iov_len = dlen @@ -190,8 +186,30 @@ void tap_udp4_send(const struct ctx *c, struct in_addr src, in_port_t sport, uh->dest = htons(dport); uh->len = htons(l4len); csum_udp4(uh, src, dst, &payload); - memcpy(data, in, dlen); + return uh + 1; +} + +/** + * tap_udp4_send() - Send UDP over IPv4 packet + * @c: Execution context + * @src: IPv4 source address + * @sport: UDP source port + * @dst: IPv4 destination address + * @dport: UDP destination port + * @in: UDP payload contents (not including UDP header) + * @dlen: UDP payload length (not including UDP header) + */ +void tap_udp4_send(const struct ctx *c, struct in_addr src, in_port_t sport, + struct in_addr dst, in_port_t dport, + const void *in, size_t dlen) +{ + size_t l4len = dlen + sizeof(struct udphdr); + char buf[USHRT_MAX]; + struct iphdr *ip4h = tap_push_l2h(c, buf, ETH_P_IP); + struct udphdr *uh = tap_push_ip4h(ip4h, src, dst, l4len, IPPROTO_UDP); + char *data = tap_push_uh4(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 dfbd8b9..3451343 100644 --- a/tap.h +++ b/tap.h @@ -8,6 +8,8 @@ #define ETH_HDR_INIT(proto) { .h_proto = htons_constant(proto) } +struct udphdr; + /** * struct tap_hdr - tap backend specific headers * @vnet_len: Frame length (for qemu socket transport) @@ -43,7 +45,9 @@ static inline void tap_hdr_update(struct tap_hdr *thdr, size_t l2len) if (thdr) thdr->vnet_len = htonl(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_udp4_send(const struct ctx *c, struct in_addr src, in_port_t sport, struct in_addr dst, in_port_t dport, const void *in, size_t dlen);-- 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