/*
* Copyright 2022-2023 The OpenSSL Project Authors. All Rights Reserved.
*
* Licensed under the Apache License 2.0 (the "License"). You may not use
* this file except in compliance with the License. You can obtain a copy
* in the file LICENSE in the source distribution or at
* https://www.openssl.org/source/license.html
*/
#ifndef OSSL_QUIC_ACKM_H
# define OSSL_QUIC_ACKM_H
# include "internal/quic_statm.h"
# include "internal/quic_cc.h"
# include "internal/quic_types.h"
# include "internal/quic_wire.h"
# include "internal/time.h"
# include "internal/list.h"
# ifndef OPENSSL_NO_QUIC
typedef struct ossl_ackm_st OSSL_ACKM;
OSSL_ACKM *ossl_ackm_new(OSSL_TIME (*now)(void *arg),
void *now_arg,
OSSL_STATM *statm,
const OSSL_CC_METHOD *cc_method,
OSSL_CC_DATA *cc_data);
void ossl_ackm_free(OSSL_ACKM *ackm);
void ossl_ackm_set_loss_detection_deadline_callback(OSSL_ACKM *ackm,
void (*fn)(OSSL_TIME deadline,
void *arg),
void *arg);
void ossl_ackm_set_ack_deadline_callback(OSSL_ACKM *ackm,
void (*fn)(OSSL_TIME deadline,
int pkt_space,
void *arg),
void *arg);
/*
* Configures the RX-side maximum ACK delay. This is the maximum amount of time
* the peer is allowed to delay sending an ACK frame after receiving an
* ACK-eliciting packet. The peer communicates this value via a transport
* parameter and it must be provided to the ACKM.
*/
void ossl_ackm_set_rx_max_ack_delay(OSSL_ACKM *ackm, OSSL_TIME rx_max_ack_delay);
/*
* Configures the TX-side maximum ACK delay. This is the maximum amount of time
* we are allowed to delay sending an ACK frame after receiving an ACK-eliciting
* packet. Note that this cannot be changed after a connection is established as
* it must be accurately reported in the transport parameters we send to our
* peer.
*/
void ossl_ackm_set_tx_max_ack_delay(OSSL_ACKM *ackm, OSSL_TIME tx_max_ack_delay);
typedef struct ossl_ackm_tx_pkt_st OSSL_ACKM_TX_PKT;
struct ossl_ackm_tx_pkt_st {
/* The packet number of the transmitted packet. */
QUIC_PN pkt_num;
/* The number of bytes in the packet which was sent. */
size_t num_bytes;
/* The time at which the packet was sent. */
OSSL_TIME time;
/*
* If the packet being described by this structure contains an ACK frame,
* this must be set to the largest PN ACK'd by that frame.
*
* Otherwise, it should be set to QUIC_PN_INVALID.
*
* This is necessary to bound the number of PNs we have to keep track of on
* the RX side (RFC 9000 s. 13.2.4). It allows older PN tracking information
* on the RX side to be discarded.
*/
QUIC_PN largest_acked;
/*
* One of the QUIC_PN_SPACE_* values. This qualifies the pkt_num field
* into a packet number space.
*/
unsigned int pkt_space :2;
/*
* 1 if the packet is in flight. A packet is considered 'in flight' if it is
* counted for purposes of congestion control and 'bytes in flight' counts.
* Most packets are considered in flight. The only circumstance where a
* numbered packet is not considered in flight is if it contains only ACK
* frames (not even PADDING frames), as these frames can bypass CC.
*/
unsigned int is_inflight :1;
/*
* 1 if the packet has one or more ACK-eliciting frames.
* Note that if this is set, is_inflight must be set.
*/
unsigned int is_ack_eliciting :1;
/* 1 if the packet is a PTO probe. */
unsigned int is_pto_probe :1;
/* 1 if the packet is an MTU probe. */
unsigned int is_mtu_probe :1;
/* Callback called if frames in this packet are lost. arg is cb_arg. */
void (*on_lost)(void *arg);
/* Callback called if frames in this packet are acked. arg is cb_arg. */
void (*on_acked)(void *arg);
/*
* Callback called if frames in this packet are neither acked nor lost. arg
* is cb_arg.
*/
void (*on_discarded)(void *arg);
void *cb_arg;
/*
* (Internal use fields; must be zero-initialized.)
*
* Keep a TX history list, anext is used to manifest
* a singly-linked list of newly-acknowledged packets, and lnext is used to
* manifest a singly-linked list of newly lost packets.
*/
OSSL_LIST_MEMBER(tx_history, OSSL_ACKM_TX_PKT);
struct ossl_ackm_tx_pkt_st *anext;
struct ossl_ackm_tx_pkt_st *lnext;
};
int ossl_ackm_on_tx_packet(OSSL_ACKM *ackm, OSSL_ACKM_TX_PKT *pkt);
int ossl_ackm_on_rx_datagram(OSSL_ACKM *ackm, size_t num_bytes);
# define OSSL_ACKM_ECN_NONE 0
# define OSSL_ACKM_ECN_ECT1 1
# define OSSL_ACKM_ECN_ECT0 2
# define OSSL_ACKM_ECN_ECNCE 3
typedef struct ossl_ackm_rx_pkt_st {
/* The packet number of the received packet. */
QUIC_PN pkt_num;
/* The time at which the packet was received. */
OSSL_TIME time;
/*
* One of the QUIC_PN_SPACE_* values. This qualifies the pkt_num field
* into a packet number space.
*/
unsigned int pkt_space :2;
/* 1 if the packet has one or more ACK-eliciting frames. */
unsigned int is_ack_eliciting :1;
/*
* One of the OSSL_ACKM_ECN_* values. This is the ECN labelling applied to
* the received packet. If unknown, use OSSL_ACKM_ECN_NONE.
*/
unsigned int ecn :2;
} OSSL_ACKM_RX_PKT;
int ossl_ackm_on_rx_packet(OSSL_ACKM *ackm, const OSSL_ACKM_RX_PKT *pkt);
int ossl_ackm_on_rx_ack_frame(OSSL_ACKM *ackm, const OSSL_QUIC_FRAME_ACK *ack,
int pkt_space, OSSL_TIME rx_time);
/*
* Discards a PN space. This must be called for a PN space before freeing the
* ACKM if you want in-flight packets to have their discarded callbacks called.
* This should never be called in ordinary QUIC usage for the Application Data
* PN space, but it may be called for the Application Data PN space prior to
* freeing the ACKM to simplify teardown implementations.
*/
int ossl_ackm_on_pkt_space_discarded(OSSL_ACKM *ackm, int pkt_space);
int ossl_ackm_on_handshake_confirmed(OSSL_ACKM *ackm);
int ossl_ackm_on_timeout(OSSL_ACKM *ackm);
OSSL_TIME ossl_ackm_get_loss_detection_deadline(OSSL_ACKM *ackm);
/*
* Generates an ACK frame, regardless of whether the ACK manager thinks
* one should currently be sent.
*
* This clears the flag returned by ossl_ackm_is_ack_desired and the deadline
* returned by ossl_ackm_get_ack_deadline.
*/
const OSSL_QUIC_FRAME_ACK *ossl_ackm_get_ack_frame(OSSL_ACKM *ackm,
int pkt_space);
/*
* Returns the deadline after which an ACK frame should be generated by calling
* ossl_ackm_get_ack_frame, or OSSL_TIME_INFINITY if no deadline is currently
* applicable. If the deadline has already passed, this function may return that
* deadline, or may return OSSL_TIME_ZERO.
*/
OSSL_TIME ossl_ackm_get_ack_deadline(OSSL_ACKM *ackm, int pkt_space);
/*
* Returns 1 if the ACK manager thinks an ACK frame ought to be generated and
* sent at this time. ossl_ackm_get_ack_frame will always provide an ACK frame
* whether or not this returns 1, so it is suggested that you call this function
* first to determine whether you need to generate an ACK frame.
*
* The return value of this function can change based on calls to
* ossl_ackm_on_rx_packet and based on the passage of time (see
* ossl_ackm_get_ack_deadline).
*/
int ossl_ackm_is_ack_desired(OSSL_ACKM *ackm, int pkt_space);
/*
* Returns 1 if the given RX PN is 'processable'. A processable PN is one that
* is not either
*
* - duplicate, meaning that we have already been passed such a PN in a call
* to ossl_ackm_on_rx_packet; or
*
* - written off, meaning that the PN is so old we have stopped tracking state
* for it (meaning that we cannot tell whether it is a duplicate and cannot
* process it safely).
*
* This should be called for a packet before attempting to process its contents.
* Failure to do so may result in processing a duplicated packet in violation of
* the RFC.
*
* The return value of this function transitions from 1 to 0 for a given PN once
* that PN is passed to ossl_ackm_on_rx_packet, thus this function must be used
* before calling ossl_ackm_on_rx_packet.
*/
int ossl_ackm_is_rx_pn_processable(OSSL_ACKM *ackm, QUIC_PN pn, int pkt_space);
typedef struct ossl_ackm_probe_info_st {
/*
* The following two probe request types are used only for anti-deadlock
* purposes in relation to the anti-amplification logic, by generating
* packets to buy ourselves more anti-amplification credit with the server
* until a client address is verified. Note that like all Initial packets,
* any Initial probes are padded.
*
* Note: The ACKM will only ever increase these by one at a time,
* as only one probe packet should be generated for these cases.
*/
uint32_t anti_deadlock_initial, anti_deadlock_handshake;
/*
* Send an ACK-eliciting packet for each count here.
*
* Note: The ACKM may increase this by either one or two for each probe
* request, depending on how many probe packets it thinks should be
* generated.
*/
uint32_t pto[QUIC_PN_SPACE_NUM];
} OSSL_ACKM_PROBE_INFO;
/*
* Returns a pointer to a structure counting any pending probe requests which
* have been generated by the ACKM. The fields in the structure are incremented
* by one every time the ACKM wants another probe of the given type to be sent.
* If the ACKM thinks two packets should be generated for a probe, it will
* increment the field twice.
*
* It is permissible for the caller to decrement or zero these fields to keep
* track of when it has generated a probe as asked. The returned structure
* has the same lifetime as the ACKM.
*
* This function should be called after calling e.g. ossl_ackm_on_timeout
* to determine if any probe requests have been generated.
*/
OSSL_ACKM_PROBE_INFO *ossl_ackm_get0_probe_request(OSSL_ACKM *ackm);
int ossl_ackm_get_largest_unacked(OSSL_ACKM *ackm, int pkt_space, QUIC_PN *pn);
/*
* Forces the ACKM to consider a packet with the given PN in the given PN space
* as having been pseudo-lost. The main reason to use this is during a Retry, to
* force any resources sent in the first Initial packet to be resent.
*
* The lost callback is called for the packet, but the packet is NOT considered
* lost for congestion control purposes. Thus this is not exactly the same as a
* true loss situation.
*/
int ossl_ackm_mark_packet_pseudo_lost(OSSL_ACKM *ackm,
int pkt_space, QUIC_PN pn);
/*
* Returns the PTO duration as currently calculated. This is a quantity of time.
* This duration is used in various parts of QUIC besides the ACKM.
*/
OSSL_TIME ossl_ackm_get_pto_duration(OSSL_ACKM *ackm);
/* Returns the largest acked PN in the given PN space. */
QUIC_PN ossl_ackm_get_largest_acked(OSSL_ACKM *ackm, int pkt_space);
# endif
#endif