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Currently both the TCP and UDP code need to deal in various places with the details of the L2 headers, and also the tap-specific "vnet_len" header. This makes abstracting the tap interface to new backends (e.g. vhost-user or tun) more difficult. To improve this abstraction, create a new 'tap_hdr' structure which represents both L2 (always Ethernet at the moment, but might be vary in future) and any additional tap specific headers (such as the qemu socket's vnet_len field). Provide helper functions and macros to initialize, update and use it. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
82 lines
2.5 KiB
C
82 lines
2.5 KiB
C
/* SPDX-License-Identifier: AGPL-3.0-or-later
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* Copyright (c) 2021 Red Hat GmbH
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* Author: Stefano Brivio <sbrivio@redhat.com>
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*/
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#ifndef TAP_H
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#define TAP_H
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/**
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* struct tap_hdr - L2 and tap specific headers
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* @vnet_len: Frame length (for qemu socket transport)
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* @eh: Ethernet header
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*/
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struct tap_hdr {
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uint32_t vnet_len;
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struct ethhdr eh;
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} __attribute__((packed));
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#define TAP_HDR_INIT(proto) { .eh.h_proto = htons_constant(proto) }
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static inline size_t tap_hdr_len_(const struct ctx *c)
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{
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(void)c;
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return sizeof(struct tap_hdr);
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}
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/**
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* tap_iov_base() - Find start of tap frame
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* @c: Execution context
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* @taph: Pointer to L2 header buffer
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*
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* Returns: pointer to the start of tap frame - suitable for an
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* iov_base to be passed to tap_send_frames())
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*/
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static inline void *tap_iov_base(const struct ctx *c, struct tap_hdr *taph)
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{
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return (char *)(taph + 1) - tap_hdr_len_(c);
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}
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/**
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* tap_iov_len() - Finalize tap frame and return total length
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* @c: Execution context
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* @taph: Tap header to finalize
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* @plen: L2 payload length (excludes L2 and tap specific headers)
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*
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* Returns: length of the tap frame including L2 and tap specific
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* headers - suitable for an iov_len to be passed to
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* tap_send_frames()
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*/
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static inline size_t tap_iov_len(const struct ctx *c, struct tap_hdr *taph,
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size_t plen)
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{
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if (c->mode == MODE_PASST)
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taph->vnet_len = htonl(plen + sizeof(taph->eh));
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return plen + tap_hdr_len_(c);
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}
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struct in_addr tap_ip4_daddr(const struct ctx *c);
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void tap_udp4_send(const struct ctx *c, struct in_addr src, in_port_t sport,
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struct in_addr dst, in_port_t dport,
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const void *in, size_t len);
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void tap_icmp4_send(const struct ctx *c, struct in_addr src, struct in_addr dst,
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void *in, size_t len);
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const struct in6_addr *tap_ip6_daddr(const struct ctx *c,
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const struct in6_addr *src);
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void tap_udp6_send(const struct ctx *c,
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const struct in6_addr *src, in_port_t sport,
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const struct in6_addr *dst, in_port_t dport,
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uint32_t flow, const void *in, size_t len);
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void tap_icmp6_send(const struct ctx *c,
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const struct in6_addr *src, const struct in6_addr *dst,
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void *in, size_t len);
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int tap_send(const struct ctx *c, const void *data, size_t len);
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void tap_send_frames(struct ctx *c, const struct iovec *iov, size_t n);
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void tap_update_mac(struct tap_hdr *taph,
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const unsigned char *eth_d, const unsigned char *eth_s);
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void tap_handler(struct ctx *c, int fd, uint32_t events,
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const struct timespec *now);
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void tap_sock_init(struct ctx *c);
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#endif /* TAP_H */
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