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/* Copyright (C) 2024 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/>.
*/
/*!
* \file
*
* \brief XDP IO interface.
*
* \addtogroup xdp
* @{
*/
#pragma once
#include <stdbool.h>
#include <stdint.h>
#include <stdio.h>
#include <netinet/in.h>
#include "libknot/xdp/bpf-consts.h"
#include "libknot/xdp/msg.h"
/*!
* \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 Configuration of XDP socket. */
struct knot_xdp_config {
uint16_t ring_size; /*!< Size of RX and TX rings (must be power of 2). */
bool force_generic; /*!< Use generic XDP mode (avoid driver/hardware implementation). */
bool force_copy; /*!< Force copying packet data between kernel and user-space (avoid zero-copy). */
unsigned busy_poll_timeout; /*!< Preferred busy poll budget (0 means disabled). */
unsigned busy_poll_budget; /*!< Preferred busy poll timeout (in microseconds) . */
};
/*! \brief Configuration of XDP socket. */
typedef struct knot_xdp_config knot_xdp_config_t;
/*! \brief Various statistics of an XDP socket (optimally kernel >=5.9). */
typedef struct {
/*! Interface name. */
const char *if_name;
/*! Interface name index (derived from ifname). */
int if_index;
/*! Network card queue id. */
unsigned if_queue;
/*! Counters (xdp_statistics) retrieved from the kernel via XDP_STATISTICS. */
struct {
/*! Dropped for other reasons. */
uint64_t rx_dropped;
/*! Dropped due to invalid descriptor. */
uint64_t rx_invalid;
/*! Dropped due to invalid descriptor. */
uint64_t tx_invalid;
/*! Dropped due to rx ring being full. */
uint64_t rx_full;
/*! Failed to retrieve item from fill ring. */
uint64_t fq_empty;
/*! Failed to retrieve item from tx ring. */
uint64_t tx_empty;
} socket;
/*! States of rings of the XDP socket. */
struct {
/*! Busy TX buffers. */
uint16_t tx_busy;
/*! Free buffers to consume from FQ ring. */
uint16_t fq_fill;
/*! Pending buffers in TX ring. */
uint16_t rx_fill;
/*! Pending buffers in RX ring. */
uint16_t tx_fill;
/*! Pending buffers in CQ ring. */
uint16_t cq_fill;
} rings;
} knot_xdp_stats_t;
/*!
* \brief Initialize XDP socket.
*
* \param socket XDP socket.
* \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 flags XDP filter configuration flags.
* \param udp_port UDP and/or TCP port to listen on if enabled via \a opts.
* \param quic_port QUIC/UDP port to listen on if enabled via \a opts.
* \param load_bpf Insert BPF program into packet processing.
* \param xdp_config Optional XDP socket configuration.
*
* \return KNOT_E* or -errno
*/
int knot_xdp_init(knot_xdp_socket_t **socket, const char *if_name, int if_queue,
knot_xdp_filter_flag_t flags, uint16_t udp_port, uint16_t quic_port,
knot_xdp_load_bpf_t load_bpf, const knot_xdp_config_t *xdp_config);
/*!
* \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 incoming 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 flags Flags for new message.
* \param out Out: the allocated packet buffer.
*
* \return KNOT_E*
*/
int knot_xdp_send_alloc(knot_xdp_socket_t *socket, knot_xdp_msg_flag_t flags,
knot_xdp_msg_t *out);
/*!
* \brief Allocate one buffer for a reply packet.
*
* \param socket XDP socket.
* \param query The packet to be replied to.
* \param out Out: the allocated packet buffer.
*
* \return KNOT_E*
*/
int knot_xdp_reply_alloc(knot_xdp_socket_t *socket, const knot_xdp_msg_t *query,
knot_xdp_msg_t *out);
/*!
* \brief Send multiple packets thru XDP.
*
* \note The packets all must have been allocated by knot_xdp_send_alloc()!
* \note Do not free the packet 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 Cleanup messages that have not been knot_xdp_send().
*
* ...possibly due to some error.
*
* \param socket XDP socket.
* \param msgs Messages to be freed.
* \param count Number of messages.
*/
void knot_xdp_send_free(knot_xdp_socket_t *socket, const knot_xdp_msg_t msgs[],
uint32_t count);
/*!
* \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 incoming packets.
* \param max_count Limit for number of packets received at once.
* \param count Out: real number of received packets.
* \param wire_size Out: (optional) total wire size 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, size_t *wire_size);
/*!
* \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_socket_info(const knot_xdp_socket_t *socket, FILE *file);
/*!
* \brief Gets various statistics of the XDP socket.
*
* \param socket XDP socket.
* \param stats Output structure.
*
* \return KNOT_E*
*/
int knot_xdp_socket_stats(knot_xdp_socket_t *socket, knot_xdp_stats_t *stats);
/*! @} */
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