2 * Copyright 2022-2023 The OpenSSL Project Authors. All Rights Reserved.
4 * Licensed under the Apache License 2.0 (the "License"). You may not use
5 * this file except in compliance with the License. You can obtain a copy
6 * in the file LICENSE in the source distribution or at
7 * https://www.openssl.org/source/license.html
9 #ifndef OSSL_QUIC_ACKM_H
10 # define OSSL_QUIC_ACKM_H
12 # include "internal/quic_statm.h"
13 # include "internal/quic_cc.h"
14 # include "internal/quic_types.h"
15 # include "internal/quic_wire.h"
16 # include "internal/quic_predef.h"
17 # include "internal/time.h"
18 # include "internal/list.h"
20 # ifndef OPENSSL_NO_QUIC
22 OSSL_ACKM *ossl_ackm_new(OSSL_TIME (*now)(void *arg),
25 const OSSL_CC_METHOD *cc_method,
26 OSSL_CC_DATA *cc_data);
27 void ossl_ackm_free(OSSL_ACKM *ackm);
29 void ossl_ackm_set_loss_detection_deadline_callback(OSSL_ACKM *ackm,
30 void (*fn)(OSSL_TIME deadline,
34 void ossl_ackm_set_ack_deadline_callback(OSSL_ACKM *ackm,
35 void (*fn)(OSSL_TIME deadline,
41 * Configures the RX-side maximum ACK delay. This is the maximum amount of time
42 * the peer is allowed to delay sending an ACK frame after receiving an
43 * ACK-eliciting packet. The peer communicates this value via a transport
44 * parameter and it must be provided to the ACKM.
46 void ossl_ackm_set_rx_max_ack_delay(OSSL_ACKM *ackm, OSSL_TIME rx_max_ack_delay);
49 * Configures the TX-side maximum ACK delay. This is the maximum amount of time
50 * we are allowed to delay sending an ACK frame after receiving an ACK-eliciting
51 * packet. Note that this cannot be changed after a connection is established as
52 * it must be accurately reported in the transport parameters we send to our
55 void ossl_ackm_set_tx_max_ack_delay(OSSL_ACKM *ackm, OSSL_TIME tx_max_ack_delay);
57 typedef struct ossl_ackm_tx_pkt_st OSSL_ACKM_TX_PKT;
58 struct ossl_ackm_tx_pkt_st {
59 /* The packet number of the transmitted packet. */
62 /* The number of bytes in the packet which was sent. */
65 /* The time at which the packet was sent. */
69 * If the packet being described by this structure contains an ACK frame,
70 * this must be set to the largest PN ACK'd by that frame.
72 * Otherwise, it should be set to QUIC_PN_INVALID.
74 * This is necessary to bound the number of PNs we have to keep track of on
75 * the RX side (RFC 9000 s. 13.2.4). It allows older PN tracking information
76 * on the RX side to be discarded.
78 QUIC_PN largest_acked;
81 * One of the QUIC_PN_SPACE_* values. This qualifies the pkt_num field
82 * into a packet number space.
84 unsigned int pkt_space :2;
87 * 1 if the packet is in flight. A packet is considered 'in flight' if it is
88 * counted for purposes of congestion control and 'bytes in flight' counts.
89 * Most packets are considered in flight. The only circumstance where a
90 * numbered packet is not considered in flight is if it contains only ACK
91 * frames (not even PADDING frames), as these frames can bypass CC.
93 unsigned int is_inflight :1;
96 * 1 if the packet has one or more ACK-eliciting frames.
97 * Note that if this is set, is_inflight must be set.
99 unsigned int is_ack_eliciting :1;
101 /* 1 if the packet is a PTO probe. */
102 unsigned int is_pto_probe :1;
104 /* 1 if the packet is an MTU probe. */
105 unsigned int is_mtu_probe :1;
107 /* Callback called if frames in this packet are lost. arg is cb_arg. */
108 void (*on_lost)(void *arg);
109 /* Callback called if frames in this packet are acked. arg is cb_arg. */
110 void (*on_acked)(void *arg);
112 * Callback called if frames in this packet are neither acked nor lost. arg
115 void (*on_discarded)(void *arg);
119 * (Internal use fields; must be zero-initialized.)
121 * Keep a TX history list, anext is used to manifest
122 * a singly-linked list of newly-acknowledged packets, and lnext is used to
123 * manifest a singly-linked list of newly lost packets.
125 OSSL_LIST_MEMBER(tx_history, OSSL_ACKM_TX_PKT);
127 struct ossl_ackm_tx_pkt_st *anext;
128 struct ossl_ackm_tx_pkt_st *lnext;
131 int ossl_ackm_on_tx_packet(OSSL_ACKM *ackm, OSSL_ACKM_TX_PKT *pkt);
132 int ossl_ackm_on_rx_datagram(OSSL_ACKM *ackm, size_t num_bytes);
134 # define OSSL_ACKM_ECN_NONE 0
135 # define OSSL_ACKM_ECN_ECT1 1
136 # define OSSL_ACKM_ECN_ECT0 2
137 # define OSSL_ACKM_ECN_ECNCE 3
139 typedef struct ossl_ackm_rx_pkt_st {
140 /* The packet number of the received packet. */
143 /* The time at which the packet was received. */
147 * One of the QUIC_PN_SPACE_* values. This qualifies the pkt_num field
148 * into a packet number space.
150 unsigned int pkt_space :2;
152 /* 1 if the packet has one or more ACK-eliciting frames. */
153 unsigned int is_ack_eliciting :1;
156 * One of the OSSL_ACKM_ECN_* values. This is the ECN labelling applied to
157 * the received packet. If unknown, use OSSL_ACKM_ECN_NONE.
162 int ossl_ackm_on_rx_packet(OSSL_ACKM *ackm, const OSSL_ACKM_RX_PKT *pkt);
164 int ossl_ackm_on_rx_ack_frame(OSSL_ACKM *ackm, const OSSL_QUIC_FRAME_ACK *ack,
165 int pkt_space, OSSL_TIME rx_time);
168 * Discards a PN space. This must be called for a PN space before freeing the
169 * ACKM if you want in-flight packets to have their discarded callbacks called.
170 * This should never be called in ordinary QUIC usage for the Application Data
171 * PN space, but it may be called for the Application Data PN space prior to
172 * freeing the ACKM to simplify teardown implementations.
174 int ossl_ackm_on_pkt_space_discarded(OSSL_ACKM *ackm, int pkt_space);
176 int ossl_ackm_on_handshake_confirmed(OSSL_ACKM *ackm);
177 int ossl_ackm_on_timeout(OSSL_ACKM *ackm);
179 OSSL_TIME ossl_ackm_get_loss_detection_deadline(OSSL_ACKM *ackm);
182 * Generates an ACK frame, regardless of whether the ACK manager thinks
183 * one should currently be sent.
185 * This clears the flag returned by ossl_ackm_is_ack_desired and the deadline
186 * returned by ossl_ackm_get_ack_deadline.
188 const OSSL_QUIC_FRAME_ACK *ossl_ackm_get_ack_frame(OSSL_ACKM *ackm,
192 * Returns the deadline after which an ACK frame should be generated by calling
193 * ossl_ackm_get_ack_frame, or OSSL_TIME_INFINITY if no deadline is currently
194 * applicable. If the deadline has already passed, this function may return that
195 * deadline, or may return OSSL_TIME_ZERO.
197 OSSL_TIME ossl_ackm_get_ack_deadline(OSSL_ACKM *ackm, int pkt_space);
200 * Returns 1 if the ACK manager thinks an ACK frame ought to be generated and
201 * sent at this time. ossl_ackm_get_ack_frame will always provide an ACK frame
202 * whether or not this returns 1, so it is suggested that you call this function
203 * first to determine whether you need to generate an ACK frame.
205 * The return value of this function can change based on calls to
206 * ossl_ackm_on_rx_packet and based on the passage of time (see
207 * ossl_ackm_get_ack_deadline).
209 int ossl_ackm_is_ack_desired(OSSL_ACKM *ackm, int pkt_space);
212 * Returns 1 if the given RX PN is 'processable'. A processable PN is one that
215 * - duplicate, meaning that we have already been passed such a PN in a call
216 * to ossl_ackm_on_rx_packet; or
218 * - written off, meaning that the PN is so old we have stopped tracking state
219 * for it (meaning that we cannot tell whether it is a duplicate and cannot
220 * process it safely).
222 * This should be called for a packet before attempting to process its contents.
223 * Failure to do so may result in processing a duplicated packet in violation of
226 * The return value of this function transitions from 1 to 0 for a given PN once
227 * that PN is passed to ossl_ackm_on_rx_packet, thus this function must be used
228 * before calling ossl_ackm_on_rx_packet.
230 int ossl_ackm_is_rx_pn_processable(OSSL_ACKM *ackm, QUIC_PN pn, int pkt_space);
232 typedef struct ossl_ackm_probe_info_st {
234 * The following two probe request types are used only for anti-deadlock
235 * purposes in relation to the anti-amplification logic, by generating
236 * packets to buy ourselves more anti-amplification credit with the server
237 * until a client address is verified. Note that like all Initial packets,
238 * any Initial probes are padded.
240 * Note: The ACKM will only ever increase these by one at a time,
241 * as only one probe packet should be generated for these cases.
243 uint32_t anti_deadlock_initial, anti_deadlock_handshake;
246 * Send an ACK-eliciting packet for each count here.
248 * Note: The ACKM may increase this by either one or two for each probe
249 * request, depending on how many probe packets it thinks should be
252 uint32_t pto[QUIC_PN_SPACE_NUM];
253 } OSSL_ACKM_PROBE_INFO;
256 * Returns a pointer to a structure counting any pending probe requests which
257 * have been generated by the ACKM. The fields in the structure are incremented
258 * by one every time the ACKM wants another probe of the given type to be sent.
259 * If the ACKM thinks two packets should be generated for a probe, it will
260 * increment the field twice.
262 * It is permissible for the caller to decrement or zero these fields to keep
263 * track of when it has generated a probe as asked. The returned structure
264 * has the same lifetime as the ACKM.
266 * This function should be called after calling e.g. ossl_ackm_on_timeout
267 * to determine if any probe requests have been generated.
269 OSSL_ACKM_PROBE_INFO *ossl_ackm_get0_probe_request(OSSL_ACKM *ackm);
271 int ossl_ackm_get_largest_unacked(OSSL_ACKM *ackm, int pkt_space, QUIC_PN *pn);
274 * Forces the ACKM to consider a packet with the given PN in the given PN space
275 * as having been pseudo-lost. The main reason to use this is during a Retry, to
276 * force any resources sent in the first Initial packet to be resent.
278 * The lost callback is called for the packet, but the packet is NOT considered
279 * lost for congestion control purposes. Thus this is not exactly the same as a
280 * true loss situation.
282 int ossl_ackm_mark_packet_pseudo_lost(OSSL_ACKM *ackm,
283 int pkt_space, QUIC_PN pn);
286 * Returns the PTO duration as currently calculated. This is a quantity of time.
287 * This duration is used in various parts of QUIC besides the ACKM.
289 OSSL_TIME ossl_ackm_get_pto_duration(OSSL_ACKM *ackm);
291 /* Returns the largest acked PN in the given PN space. */
292 QUIC_PN ossl_ackm_get_largest_acked(OSSL_ACKM *ackm, int pkt_space);