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/* Copyright (C) 2020 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <https://www.gnu.org/licenses/>.
*/
#pragma once
#include <stdbool.h>
#include <stdint.h>
#include <stdio.h>
#include <netinet/in.h>
#include "libknot/xdp/bpf-consts.h"
#ifdef ENABLE_XDP
#define KNOT_XDP_AVAILABLE 1
#endif
/*! \brief A packet with src & dst MAC & IP addrs + UDP payload. */
typedef struct knot_xdp_msg knot_xdp_msg_t;
struct knot_xdp_msg {
struct sockaddr_in6 ip_from;
struct sockaddr_in6 ip_to;
uint8_t *eth_from;
uint8_t *eth_to;
struct iovec payload;
};
/*!
* \brief Styles of loading BPF program.
*
* \note In *all* the cases loading can only succeed if at the end
* a compatible BPF program is loaded on the interface.
*/
typedef enum {
KNOT_XDP_LOAD_BPF_NEVER, /*!< Do not load; error out if not loaded already. */
KNOT_XDP_LOAD_BPF_ALWAYS, /*!< Always load a program (overwrite it). */
KNOT_XDP_LOAD_BPF_ALWAYS_UNLOAD, /*!< KNOT_XDP_LOAD_BPF_ALWAYS + unload previous. */
KNOT_XDP_LOAD_BPF_MAYBE, /*!< Try with present program or load if none. */
/* Implementation caveat: when re-using program in _MAYBE case, we get a message:
* libbpf: Kernel error message: XDP program already attached */
} knot_xdp_load_bpf_t;
/*! \brief Context structure for one XDP socket. */
typedef struct knot_xdp_socket knot_xdp_socket_t;
/*! \brief Offset of DNS payload inside ethernet frame (IPv4 and v6 variants). */
extern const size_t KNOT_XDP_PAYLOAD_OFFSET4;
extern const size_t KNOT_XDP_PAYLOAD_OFFSET6;
/*!
* \brief Initialize XDP socket.
*
* \param socket Socket ctx.
* \param if_name Name of the net iface (e.g. eth0).
* \param if_queue Network card queue to be used (normally 1 socket per each queue).
* \param listen_port Port to listen on, or KNOT_XDP_LISTEN_PORT_* flag.
* \param load_bpf Insert BPF program into packet processing.
*
* \return KNOT_E* or -errno
*/
int knot_xdp_init(knot_xdp_socket_t **socket, const char *if_name, int if_queue,
uint32_t listen_port, knot_xdp_load_bpf_t load_bpf);
/*!
* \brief De-init XDP socket.
*
* \param socket XDP socket.
*/
void knot_xdp_deinit(knot_xdp_socket_t *socket);
/*!
* \brief Return a file descriptor to be polled on for incomming packets.
*
* \param socket XDP socket.
*
* \return KNOT_E*
*/
int knot_xdp_socket_fd(knot_xdp_socket_t *socket);
/*!
* \brief Collect completed TX buffers, so they can be used by knot_xdp_send_alloc().
*
* \param socket XDP socket.
*/
void knot_xdp_send_prepare(knot_xdp_socket_t *socket);
/*!
* \brief Allocate one buffer for an outgoing packet.
*
* \param socket XDP socket.
* \param ipv6 The packet will use IPv6 (IPv4 otherwise).
* \param out Out: the allocated packet buffer.
* \param in_reply_to Optional: fill in addresses from this query.
*
* \return KNOT_E*
*/
int knot_xdp_send_alloc(knot_xdp_socket_t *socket, bool ipv6, knot_xdp_msg_t *out,
const knot_xdp_msg_t *in_reply_to);
/*!
* \brief Send multiple packets thru XDP.
*
* \note The packets all must have been allocated by knot_xdp_send_alloc()!
* \note Do not free the packets payloads afterwards.
* \note Packets with zero length will be skipped.
*
* \param socket XDP socket.
* \param msgs Packets to be sent.
* \param count Number of packets.
* \param sent Out: number of packet successfully sent.
*
* \return KNOT_E*
*/
int knot_xdp_send(knot_xdp_socket_t *socket, const knot_xdp_msg_t msgs[],
uint32_t count, uint32_t *sent);
/*!
* \brief Syscall to kernel to wake up the network card driver after knot_xdp_send().
*
* \param socket XDP socket.
*
* \return KNOT_E* or -errno
*/
int knot_xdp_send_finish(knot_xdp_socket_t *socket);
/*!
* \brief Receive multiple packets thru XDP.
*
* \param socket XDP socket.
* \param msgs Out: buffers to be filled in with incomming packets.
* \param max_count Limit for number of packets received at once.
* \param count Out: real number of received packets.
*
* \return KNOT_E*
*/
int knot_xdp_recv(knot_xdp_socket_t *socket, knot_xdp_msg_t msgs[],
uint32_t max_count, uint32_t *count);
/*!
* \brief Free buffers with received packets.
*
* \param socket XDP socket.
* \param msgs Buffers with received packets.
* \param count Number of received packets to free.
*/
void knot_xdp_recv_finish(knot_xdp_socket_t *socket, const knot_xdp_msg_t msgs[],
uint32_t count);
/*!
* \brief Print some info about the XDP socket.
*
* \param socket XDP socket.
* \param file Output file.
*/
void knot_xdp_info(const knot_xdp_socket_t *socket, FILE *file);
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