a66fceb280
To be able to provide pointers to TCP headers and IP headers without worrying about alignment in the structure, split the structure into several arrays and point to each part of the frame using an iovec array. Using iovec also allows us to simply ignore the first entry when the vnet length header is not needed. And as the payload buffer contains only the TCP header and the TCP data we can increase the size of the TCP data to USHRT_MAX - sizeof(struct tcphdr). As a side effect, these changes improve performance by a factor of x1.5. Signed-off-by: Laurent Vivier <lvivier@redhat.com>
102 lines
3.2 KiB
C
102 lines
3.2 KiB
C
/* SPDX-License-Identifier: GPL-2.0-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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* TCP frame iovec array:
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* TCP_IOV_VNET vnet length
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* TCP_IOV_ETH ethernet header
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* TCP_IOV_IP IP (v4/v6) header
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* TCP_IOV_PAYLOAD IP payload (TCP header + data)
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* TCP_IOV_NUM is the number of entries in the iovec array
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*/
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#define TCP_IOV_VNET 0
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#define TCP_IOV_ETH 1
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#define TCP_IOV_IP 2
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#define TCP_IOV_PAYLOAD 3
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#define TCP_IOV_NUM 4
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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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if (c->mode == MODE_PASST)
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return sizeof(struct tap_hdr);
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else
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return sizeof(struct ethhdr);
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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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const 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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const 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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size_t tap_send_frames(const struct ctx *c, const struct iovec *iov, size_t n);
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size_t tap_send_iov(const struct ctx *c, struct iovec iov[][TCP_IOV_NUM],
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size_t n);
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void eth_update_mac(struct ethhdr *eh,
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const unsigned char *eth_d, const unsigned char *eth_s);
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void tap_listen_handler(struct ctx *c, uint32_t events);
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void tap_handler_pasta(struct ctx *c, uint32_t events,
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const struct timespec *now);
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void tap_handler_passt(struct ctx *c, 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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