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passt/tap.h
David Gibson 3f9bd867b5 udp: Split tap-bound UDP packets into multiple buffers using io vector
When sending to the tap device, currently we assemble the headers and
payload into a single contiguous buffer.  Those are described by a single
struct iovec, then a batch of frames is sent to the device with
tap_send_frames().

In order to better integrate the IPv4 and IPv6 paths, we want the IP
header in a different buffer that might not be contiguous with the
payload.  To prepare for that, split the UDP packet into an iovec of
buffers.  We use the same split that Laurent recently introduced for
TCP for convenience.

This removes the last use of tap_hdr_len_(), tap_frame_base() and
tap_frame_len(), so remove those too.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
2024-05-02 16:13:38 +02:00

74 lines
2.4 KiB
C

/* SPDX-License-Identifier: GPL-2.0-or-later
* Copyright (c) 2021 Red Hat GmbH
* Author: Stefano Brivio <sbrivio@redhat.com>
*/
#ifndef TAP_H
#define TAP_H
#define ETH_HDR_INIT(proto) { .h_proto = htons_constant(proto) }
/**
* struct tap_hdr - tap backend specific headers
* @vnet_len: Frame length (for qemu socket transport)
*/
struct tap_hdr {
uint32_t vnet_len;
} __attribute__((packed));
/**
* tap_hdr_iov() - struct iovec for a tap header
* @c: Execution context
* @taph: Pointer to tap specific header buffer
*
* Returns: A struct iovec covering the correct portion of @taph to use as the
* tap specific header in the current configuration.
*/
static inline struct iovec tap_hdr_iov(const struct ctx *c,
struct tap_hdr *thdr)
{
return (struct iovec){
.iov_base = thdr,
.iov_len = c->mode == MODE_PASST ? sizeof(*thdr) : 0,
};
}
/**
* tap_hdr_update() - Update the tap specific header for a frame
* @taph: Tap specific header buffer to update
* @l2len: Frame length (including L2 headers)
*/
static inline void tap_hdr_update(struct tap_hdr *thdr, size_t l2len)
{
thdr->vnet_len = htonl(l2len);
}
struct in_addr tap_ip4_daddr(const struct ctx *c);
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);
void tap_icmp4_send(const struct ctx *c, struct in_addr src, struct in_addr dst,
const void *in, size_t l4len);
const struct in6_addr *tap_ip6_daddr(const struct ctx *c,
const struct in6_addr *src);
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, const void *in, size_t dlen);
void tap_icmp6_send(const struct ctx *c,
const struct in6_addr *src, const struct in6_addr *dst,
const void *in, size_t l4len);
void tap_send_single(const struct ctx *c, const void *data, size_t l2len);
size_t tap_send_frames(const struct ctx *c, const struct iovec *iov,
size_t bufs_per_frame, size_t nframes);
void eth_update_mac(struct ethhdr *eh,
const unsigned char *eth_d, const unsigned char *eth_s);
void tap_listen_handler(struct ctx *c, uint32_t events);
void tap_handler_pasta(struct ctx *c, uint32_t events,
const struct timespec *now);
void tap_handler_passt(struct ctx *c, uint32_t events,
const struct timespec *now);
void tap_sock_init(struct ctx *c);
#endif /* TAP_H */