From 82a839be988ecfdb013b5823afc93211200a9f55 Mon Sep 17 00:00:00 2001 From: Jon Maloy Date: Thu, 6 Mar 2025 13:00:03 -0500 Subject: tap: break out building of udp header from tap_udp4_send function 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. Reviewed-by: David Gibson Signed-off-by: Jon Maloy Signed-off-by: Stefano Brivio --- tap.c | 34 +++++++++++++++++++++++++++------- tap.h | 5 +++++ 2 files changed, 32 insertions(+), 7 deletions(-) diff --git a/tap.c b/tap.c index 86d051e..6f7063e 100644 --- a/tap.c +++ b/tap.c @@ -163,7 +163,7 @@ 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 @@ -171,16 +171,14 @@ void *tap_push_ip4h(struct iphdr *ip4h, struct in_addr src, * @dport: UDP destination port * @in: UDP payload contents (not including UDP header) * @dlen: UDP payload length (not including UDP header) + * + * Return: pointer at which to write the packet's payload */ -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 @@ -191,8 +189,30 @@ 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 (char *)uh + sizeof(*uh); +} +/** + * 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 390ac12..a2cf9bc 100644 --- a/tap.h +++ b/tap.h @@ -6,6 +6,8 @@ #ifndef TAP_H #define TAP_H +struct udphdr; + /** * struct tap_hdr - tap backend specific headers * @vnet_len: Frame length (for qemu socket transport) @@ -45,6 +47,9 @@ static inline void tap_hdr_update(struct tap_hdr *thdr, size_t l2len) void *tap_push_l2h(const struct ctx *c, void *buf, uint16_t proto); void *tap_push_ip4h(struct iphdr *ip4h, struct in_addr src, struct in_addr dst, size_t l4len, uint8_t proto); +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); -- cgit v1.2.3