/*

 * Copyright 2022-2025 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

 */

#include "internal/packet_quic.h"

#include "internal/nelem.h"

#include "internal/quic_wire.h"

#include "internal/quic_record_rx.h"

#include "internal/quic_ackm.h"

#include "internal/quic_rx_depack.h"

#include "internal/quic_error.h"

#include "internal/quic_fc.h"

#include "internal/quic_channel.h"

#include "internal/sockets.h"

#include "quic_local.h"

#include "quic_channel_local.h"

#include "../ssl_local.h"

/*

 * Helper functions to process different frame types.

 *

 * Typically, those that are ACK eliciting will take an OSSL_ACKM_RX_PKT

 * pointer argument, the few that aren't ACK eliciting will not.  This makes

 * them a verifiable pattern against tables where this is specified.

 */

static int depack_do_implicit_stream_create(QUIC_CHANNEL *ch,

                                            uint64_t stream_id,

                                            uint64_t frame_type,

                                            QUIC_STREAM **result);

static int depack_do_frame_padding(PACKET *pkt)

{

    /* We ignore this frame */

    ossl_quic_wire_decode_padding(pkt);

    return 1;

}

static int depack_do_frame_ping(PACKET *pkt, QUIC_CHANNEL *ch,

                                uint32_t enc_level,

                                OSSL_ACKM_RX_PKT *ackm_data)

{

    /* We ignore this frame, apart from eliciting an ACK */

    if (!ossl_quic_wire_decode_frame_ping(pkt)) {

        ossl_quic_channel_raise_protocol_error(ch,

                                               OSSL_QUIC_ERR_FRAME_ENCODING_ERROR,

                                               OSSL_QUIC_FRAME_TYPE_PING,

                                               "decode error");

        return 0;

    }

    ossl_quic_tx_packetiser_schedule_ack_eliciting(ch->txp, enc_level);

    return 1;

}

static int depack_do_frame_ack(PACKET *pkt, QUIC_CHANNEL *ch,

                               int packet_space, OSSL_TIME received,

                               uint64_t frame_type,

                               OSSL_QRX_PKT *qpacket)

{

    OSSL_QUIC_FRAME_ACK ack;

    OSSL_QUIC_ACK_RANGE *p;

    uint64_t total_ranges = 0;

    uint32_t ack_delay_exp = ch->rx_ack_delay_exp;

    if (!ossl_quic_wire_peek_frame_ack_num_ranges(pkt, &total_ranges)

        /* In case sizeof(uint64_t) > sizeof(size_t) */

        || total_ranges > SIZE_MAX / sizeof(OSSL_QUIC_ACK_RANGE))

        goto malformed;

    if (ch->num_ack_range_scratch < (size_t)total_ranges) {

        if ((p = OPENSSL_realloc(ch->ack_range_scratch,

                                 sizeof(OSSL_QUIC_ACK_RANGE)

                                 * (size_t)total_ranges)) == NULL)

            goto malformed;

        ch->ack_range_scratch       = p;

        ch->num_ack_range_scratch   = (size_t)total_ranges;

    }

    ack.ack_ranges = ch->ack_range_scratch;

    ack.num_ack_ranges = (size_t)total_ranges;

    if (!ossl_quic_wire_decode_frame_ack(pkt, ack_delay_exp, &ack, NULL))

        goto malformed;

    if (qpacket->hdr->type == QUIC_PKT_TYPE_1RTT

        && (qpacket->key_epoch < ossl_qrx_get_key_epoch(ch->qrx)

            || ch->rxku_expected)

        && ack.ack_ranges[0].end >= ch->txku_pn) {

        /*

         * RFC 9001 s. 6.2: An endpoint that receives an acknowledgment that is

         * carried in a packet protected with old keys where any acknowledged

         * packet was protected with newer keys MAY treat that as a connection

         * error of type KEY_UPDATE_ERROR.

         *

         * Two cases to handle here:

         *

         *   - We did spontaneous TXKU, the peer has responded in kind and we

         *     have detected RXKU; !ch->rxku_expected, but then it sent a packet

         *     with old keys acknowledging a packet in the new key epoch.

         *

         *     This also covers the case where we got RXKU and triggered

         *     solicited TXKU, and then for some reason the peer sent an ACK of

         *     a PN in our new TX key epoch with old keys.

         *

         *   - We did spontaneous TXKU; ch->txku_pn is the starting PN of our

         *     new TX key epoch; the peer has not initiated a solicited TXKU in

         *     response (so we have not detected RXKU); in this case the RX key

         *     epoch has not incremented and ch->rxku_expected is still 1.

         */

        ossl_quic_channel_raise_protocol_error(ch,

                                               OSSL_QUIC_ERR_KEY_UPDATE_ERROR,

                                               frame_type,

                                               "acked packet which initiated a "

                                               "key update without a "

                                               "corresponding key update");

        return 0;

    }

    if (!ossl_ackm_on_rx_ack_frame(ch->ackm, &ack,

                                   packet_space, received))

        goto malformed;

    ++ch->diag_num_rx_ack;

    return 1;

malformed:

    ossl_quic_channel_raise_protocol_error(ch,

                                           OSSL_QUIC_ERR_FRAME_ENCODING_ERROR,

                                           frame_type,

                                           "decode error");

    return 0;

}

static int depack_do_frame_reset_stream(PACKET *pkt,

                                        QUIC_CHANNEL *ch,

                                        OSSL_ACKM_RX_PKT *ackm_data)

{

    OSSL_QUIC_FRAME_RESET_STREAM frame_data;

    QUIC_STREAM *stream = NULL;

    uint64_t fce;

    if (!ossl_quic_wire_decode_frame_reset_stream(pkt, &frame_data)) {

        ossl_quic_channel_raise_protocol_error(ch,

                                               OSSL_QUIC_ERR_FRAME_ENCODING_ERROR,

                                               OSSL_QUIC_FRAME_TYPE_RESET_STREAM,

                                               "decode error");

        return 0;

    }

    if (!depack_do_implicit_stream_create(ch, frame_data.stream_id,

                                          OSSL_QUIC_FRAME_TYPE_RESET_STREAM,

                                          &stream))

        return 0; /* error already raised for us */

    if (stream == NULL)

        return 1; /* old deleted stream, not a protocol violation, ignore */

    if (!ossl_quic_stream_has_recv(stream)) {

        ossl_quic_channel_raise_protocol_error(ch,

                                               OSSL_QUIC_ERR_STREAM_STATE_ERROR,

                                               OSSL_QUIC_FRAME_TYPE_RESET_STREAM,

                                               "RESET_STREAM frame for "

                                               "TX only stream");

        return 0;

    }

    /*

     * The final size field of the RESET_STREAM frame must be used to determine

     * how much flow control credit the aborted stream was considered to have

     * consumed.

     *

     * We also need to ensure that if we already have a final size for the

     * stream, the RESET_STREAM frame's Final Size field matches this; we SHOULD

     * terminate the connection otherwise (RFC 9000 s. 4.5). The RXFC takes care

     * of this for us.

     */

    if (!ossl_quic_rxfc_on_rx_stream_frame(&stream->rxfc,

                                           frame_data.final_size, /*is_fin=*/1)) {

        ossl_quic_channel_raise_protocol_error(ch,

                                               OSSL_QUIC_ERR_INTERNAL_ERROR,

                                               OSSL_QUIC_FRAME_TYPE_RESET_STREAM,

                                               "internal error (flow control)");

        return 0;

    }

    /* Has a flow control error occurred? */

    fce = ossl_quic_rxfc_get_error(&stream->rxfc, 0);

    if (fce != OSSL_QUIC_ERR_NO_ERROR) {

        ossl_quic_channel_raise_protocol_error(ch,

                                               fce,

                                               OSSL_QUIC_FRAME_TYPE_RESET_STREAM,

                                               "flow control violation");

        return 0;

    }

    /*

     * Depending on the receive part state this is handled either as a reset

     * transition or a no-op (e.g. if a reset has already been received before,

     * or the application already retired a FIN). Best effort - there are no

     * protocol error conditions we need to check for here.

     */

    ossl_quic_stream_map_notify_reset_recv_part(&ch->qsm, stream,

                                                frame_data.app_error_code,

                                                frame_data.final_size);

    ossl_quic_stream_map_update_state(&ch->qsm, stream);

    return 1;

}

static int depack_do_frame_stop_sending(PACKET *pkt,

                                        QUIC_CHANNEL *ch,

                                        OSSL_ACKM_RX_PKT *ackm_data)

{

    OSSL_QUIC_FRAME_STOP_SENDING frame_data;

    QUIC_STREAM *stream = NULL;

    if (!ossl_quic_wire_decode_frame_stop_sending(pkt, &frame_data)) {

        ossl_quic_channel_raise_protocol_error(ch,

                                               OSSL_QUIC_ERR_FRAME_ENCODING_ERROR,

                                               OSSL_QUIC_FRAME_TYPE_STOP_SENDING,

                                               "decode error");

        return 0;

    }

    if (!depack_do_implicit_stream_create(ch, frame_data.stream_id,

                                          OSSL_QUIC_FRAME_TYPE_STOP_SENDING,

                                          &stream))

        return 0; /* error already raised for us */

    if (stream == NULL)

        return 1; /* old deleted stream, not a protocol violation, ignore */

    if (!ossl_quic_stream_has_send(stream)) {

        ossl_quic_channel_raise_protocol_error(ch,

                                               OSSL_QUIC_ERR_STREAM_STATE_ERROR,

                                               OSSL_QUIC_FRAME_TYPE_STOP_SENDING,

                                               "STOP_SENDING frame for "

                                               "RX only stream");

        return 0;

    }

    stream->peer_stop_sending       = 1;

    stream->peer_stop_sending_aec   = frame_data.app_error_code;

    /*

     * RFC 9000 s. 3.5: Receiving a STOP_SENDING frame means we must respond in

     * turn with a RESET_STREAM frame for the same part of the stream. The other

     * part is unaffected.

     */

    ossl_quic_stream_map_reset_stream_send_part(&ch->qsm, stream,

                                                frame_data.app_error_code);

    return 1;

}

static int depack_do_frame_crypto(PACKET *pkt, QUIC_CHANNEL *ch,

                                  OSSL_QRX_PKT *parent_pkt,

                                  OSSL_ACKM_RX_PKT *ackm_data,

                                  uint64_t *datalen)

{

    OSSL_QUIC_FRAME_CRYPTO f;

    QUIC_RSTREAM *rstream;

    QUIC_RXFC *rxfc;

    *datalen = 0;

    if (!ossl_quic_wire_decode_frame_crypto(pkt, 0, &f)) {

        ossl_quic_channel_raise_protocol_error(ch,

                                               OSSL_QUIC_ERR_FRAME_ENCODING_ERROR,

                                               OSSL_QUIC_FRAME_TYPE_CRYPTO,

                                               "decode error");

        return 0;

    }

    if (f.len == 0)

        return 1; /* nothing to do */

    rstream = ch->crypto_recv[ackm_data->pkt_space];

    if (!ossl_assert(rstream != NULL))

        /*

         * This should not happen; we should only have a NULL stream here if

         * the EL has been discarded, and if the EL has been discarded we

         * shouldn't be here.

         */

        return 0;

    rxfc = &ch->crypto_rxfc[ackm_data->pkt_space];

    if (!ossl_quic_rxfc_on_rx_stream_frame(rxfc, f.offset + f.len,

                                           /*is_fin=*/0)) {

        ossl_quic_channel_raise_protocol_error(ch,

                                               OSSL_QUIC_ERR_INTERNAL_ERROR,

                                               OSSL_QUIC_FRAME_TYPE_CRYPTO,

                                               "internal error (crypto RXFC)");

        return 0;

    }

    if (ossl_quic_rxfc_get_error(rxfc, 0) != OSSL_QUIC_ERR_NO_ERROR) {

        ossl_quic_channel_raise_protocol_error(ch, OSSL_QUIC_ERR_CRYPTO_BUFFER_EXCEEDED,

                                               OSSL_QUIC_FRAME_TYPE_CRYPTO,

                                               "exceeded maximum crypto buffer");

        return 0;

    }

    if (!ossl_quic_rstream_queue_data(rstream, parent_pkt,

                                      f.offset, f.data, f.len, 0)) {

        ossl_quic_channel_raise_protocol_error(ch,

                                               OSSL_QUIC_ERR_INTERNAL_ERROR,

                                               OSSL_QUIC_FRAME_TYPE_CRYPTO,

                                               "internal error (rstream queue)");

        return 0;

    }

    ch->did_crypto_frame = 1;

    *datalen = f.len;

    return 1;

}

static int depack_do_frame_new_token(PACKET *pkt, QUIC_CHANNEL *ch,

                                     OSSL_ACKM_RX_PKT *ackm_data)

{

    const uint8_t *token;

    size_t token_len;

    if (!ossl_quic_wire_decode_frame_new_token(pkt, &token, &token_len)) {

        ossl_quic_channel_raise_protocol_error(ch,

                                               OSSL_QUIC_ERR_FRAME_ENCODING_ERROR,

                                               OSSL_QUIC_FRAME_TYPE_NEW_TOKEN,

                                               "decode error");

        return 0;

    }

    if (token_len == 0) {

        /*

         * RFC 9000 s. 19.7: "A client MUST treat receipt of a NEW_TOKEN frame

         * with an empty Token field as a connection error of type

         * FRAME_ENCODING_ERROR."

         */

        ossl_quic_channel_raise_protocol_error(ch,

                                               OSSL_QUIC_ERR_FRAME_ENCODING_ERROR,

                                               OSSL_QUIC_FRAME_TYPE_NEW_TOKEN,

                                               "zero-length NEW_TOKEN");

        return 0;

    }

    /* store the new token in our token cache */

    if (!ossl_quic_set_peer_token(ossl_quic_port_get_channel_ctx(ch->port),

                                  &ch->cur_peer_addr, token, token_len))

        return 0;

    return 1;

}

/*

 * Returns 1 if no protocol violation has occurred. In this case *result will be

 * non-NULL unless this is an old deleted stream and we should ignore the frame

 * causing this function to be called. Returns 0 on protocol violation.

 */

static int depack_do_implicit_stream_create(QUIC_CHANNEL *ch,

                                            uint64_t stream_id,

                                            uint64_t frame_type,

                                            QUIC_STREAM **result)

{

    QUIC_STREAM *stream;

    uint64_t peer_role, stream_ordinal;

    uint64_t *p_next_ordinal_local, *p_next_ordinal_remote;

    QUIC_RXFC *max_streams_fc;

    int is_uni, is_remote_init;

    stream = ossl_quic_stream_map_get_by_id(&ch->qsm, stream_id);

    if (stream != NULL) {

        *result = stream;

        return 1;

    }

    /*

     * If we do not yet have a stream with the given ID, there are three

     * possibilities:

     *

     *   (a) The stream ID is for a remotely-created stream and the peer

     *       is creating a stream.

     *

     *   (b) The stream ID is for a locally-created stream which has

     *       previously been deleted.

     *

     *   (c) The stream ID is for a locally-created stream which does

     *       not exist yet. This is a protocol violation and we must

     *       terminate the connection in this case.

     *

     * We distinguish between (b) and (c) using the stream ID allocator

     * variable. Since stream ordinals are allocated monotonically, we

     * simply determine if the stream ordinal is in the future.

     */

    peer_role = ch->is_server

        ? QUIC_STREAM_INITIATOR_CLIENT

        : QUIC_STREAM_INITIATOR_SERVER;

    is_remote_init = ((stream_id & QUIC_STREAM_INITIATOR_MASK) == peer_role);

    is_uni = ((stream_id & QUIC_STREAM_DIR_MASK) == QUIC_STREAM_DIR_UNI);

    stream_ordinal = stream_id >> 2;

    if (is_remote_init) {

        /*

         * Peer-created stream which does not yet exist. Create it. QUIC stream

         * ordinals within a given stream type MUST be used in sequence and

         * receiving a STREAM frame for ordinal n must implicitly create streams

         * with ordinals [0, n) within that stream type even if no explicit

         * STREAM frames are received for those ordinals.

         */

        p_next_ordinal_remote = is_uni

            ? &ch->next_remote_stream_ordinal_uni

            : &ch->next_remote_stream_ordinal_bidi;

        /* Check this isn't violating stream count flow control. */

        max_streams_fc = is_uni

            ? &ch->max_streams_uni_rxfc

            : &ch->max_streams_bidi_rxfc;

        if (!ossl_quic_rxfc_on_rx_stream_frame(max_streams_fc,

                                               stream_ordinal + 1,

                                               /*is_fin=*/0)) {

            ossl_quic_channel_raise_protocol_error(ch,

                                                   OSSL_QUIC_ERR_INTERNAL_ERROR,

                                                   frame_type,

                                                   "internal error (stream count RXFC)");

            return 0;

        }

        if (ossl_quic_rxfc_get_error(max_streams_fc, 0) != OSSL_QUIC_ERR_NO_ERROR) {

            ossl_quic_channel_raise_protocol_error(ch, OSSL_QUIC_ERR_STREAM_LIMIT_ERROR,

                                                   frame_type,

                                                   "exceeded maximum allowed streams");

            return 0;

        }

        /*

         * Create the named stream and any streams coming before it yet to be

         * created.

         */

        while (*p_next_ordinal_remote <= stream_ordinal) {

            uint64_t cur_stream_id = (*p_next_ordinal_remote << 2) |

                (stream_id

                 & (QUIC_STREAM_DIR_MASK | QUIC_STREAM_INITIATOR_MASK));

            stream = ossl_quic_channel_new_stream_remote(ch, cur_stream_id);

            if (stream == NULL) {

                ossl_quic_channel_raise_protocol_error(ch,

                                                       OSSL_QUIC_ERR_INTERNAL_ERROR,

                                                       frame_type,

                                                       "internal error (stream allocation)");

                return 0;

            }

            ++*p_next_ordinal_remote;

        }

        *result = stream;

    } else {

        /* Locally-created stream which does not yet exist. */

        p_next_ordinal_local = is_uni

            ? &ch->next_local_stream_ordinal_uni

            : &ch->next_local_stream_ordinal_bidi;

        if (stream_ordinal >= *p_next_ordinal_local) {

            /*

             * We never created this stream yet, this is a protocol

             * violation.

             */

            ossl_quic_channel_raise_protocol_error(ch,

                                                   OSSL_QUIC_ERR_STREAM_STATE_ERROR,

                                                   frame_type,

                                                   "STREAM frame for nonexistent "

                                                   "stream");

            return 0;

        }

        /*

         * Otherwise this is for an old locally-initiated stream which we

         * have subsequently deleted. Ignore the data; it may simply be a

         * retransmission. We already take care of notifying the peer of the

         * termination of the stream during the stream deletion lifecycle.

         */

        *result = NULL;

    }

    return 1;

}

static int depack_do_frame_stream(PACKET *pkt, QUIC_CHANNEL *ch,

                                  OSSL_QRX_PKT *parent_pkt,

                                  OSSL_ACKM_RX_PKT *ackm_data,

                                  uint64_t frame_type,

                                  uint64_t *datalen)

{

    OSSL_QUIC_FRAME_STREAM frame_data;

    QUIC_STREAM *stream;

    uint64_t fce;

    size_t rs_avail;

    int rs_fin = 0;

    *datalen = 0;

    if (!ossl_quic_wire_decode_frame_stream(pkt, 0, &frame_data)) {

        ossl_quic_channel_raise_protocol_error(ch,

                                               OSSL_QUIC_ERR_FRAME_ENCODING_ERROR,

                                               frame_type,

                                               "decode error");

        return 0;

    }

    if (!depack_do_implicit_stream_create(ch, frame_data.stream_id,

                                          frame_type, &stream))

        return 0; /* protocol error raised by above call */

    if (stream == NULL)

        /*

         * Data for old stream which is not a protocol violation but should be

         * ignored, so stop here.

         */

        return 1;

    if (!ossl_quic_stream_has_recv(stream)) {

        ossl_quic_channel_raise_protocol_error(ch,

                                               OSSL_QUIC_ERR_STREAM_STATE_ERROR,

                                               frame_type,

                                               "STREAM frame for TX only "

                                               "stream");

        return 0;

    }

    /* Notify stream flow controller. */

    if (!ossl_quic_rxfc_on_rx_stream_frame(&stream->rxfc,

                                           frame_data.offset + frame_data.len,

                                           frame_data.is_fin)) {

        ossl_quic_channel_raise_protocol_error(ch,

                                               OSSL_QUIC_ERR_INTERNAL_ERROR,

                                               frame_type,

                                               "internal error (flow control)");

        return 0;

    }

    /* Has a flow control error occurred? */

    fce = ossl_quic_rxfc_get_error(&stream->rxfc, 0);

    if (fce != OSSL_QUIC_ERR_NO_ERROR) {

        ossl_quic_channel_raise_protocol_error(ch,

                                               fce,

                                               frame_type,

                                               "flow control violation");

        return 0;

    }

    switch (stream->recv_state) {

    case QUIC_RSTREAM_STATE_RECV:

    case QUIC_RSTREAM_STATE_SIZE_KNOWN:

        /*

         * It only makes sense to process incoming STREAM frames in these

         * states.

         */

        break;

    case QUIC_RSTREAM_STATE_DATA_RECVD:

    case QUIC_RSTREAM_STATE_DATA_READ:

    case QUIC_RSTREAM_STATE_RESET_RECVD:

    case QUIC_RSTREAM_STATE_RESET_READ:

    default:

        /*

         * We have no use for STREAM frames once the receive part reaches any of

         * these states, so just ignore.

         */

        return 1;

    }

    /* If we are in RECV, auto-transition to SIZE_KNOWN on FIN. */

    if (frame_data.is_fin

        && !ossl_quic_stream_recv_get_final_size(stream, NULL)) {

        /* State was already checked above, so can't fail. */

        ossl_quic_stream_map_notify_size_known_recv_part(&ch->qsm, stream,

                                                         frame_data.offset

                                                         + frame_data.len);

    }

    /*

     * If we requested STOP_SENDING do not bother buffering the data. Note that

     * this must happen after RXFC checks above as even if we sent STOP_SENDING

     * we must still enforce correct flow control (RFC 9000 s. 3.5).

     */

    if (stream->stop_sending)

        return 1; /* not an error - packet reordering, etc. */

    /*

     * The receive stream buffer may or may not choose to consume the data

     * without copying by reffing the OSSL_QRX_PKT. In this case

     * ossl_qrx_pkt_release() will be eventually called when the data is no

     * longer needed.

     *

     * It is OK for the peer to send us a zero-length non-FIN STREAM frame,

     * which is a no-op, aside from the fact that it ensures the stream exists.

     * In this case we have nothing to report to the receive buffer.

     */

    if ((frame_data.len > 0 || frame_data.is_fin)

        && !ossl_quic_rstream_queue_data(stream->rstream, parent_pkt,

                                      frame_data.offset,

                                      frame_data.data,

                                      frame_data.len,

                                      frame_data.is_fin)) {

        ossl_quic_channel_raise_protocol_error(ch,

                                               OSSL_QUIC_ERR_INTERNAL_ERROR,

                                               frame_type,

                                               "internal error (rstream queue)");

        return 0;

    }

    /*

     * rs_fin will be 1 only if we can read all data up to and including the FIN

     * without any gaps before it; this implies we have received all data. Avoid

     * calling ossl_quic_rstream_available() where it is not necessary as it is

     * more expensive.

     */

    if (stream->recv_state == QUIC_RSTREAM_STATE_SIZE_KNOWN

        && !ossl_quic_rstream_available(stream->rstream, &rs_avail, &rs_fin)) {

        ossl_quic_channel_raise_protocol_error(ch,

                                               OSSL_QUIC_ERR_INTERNAL_ERROR,

                                               frame_type,

                                               "internal error (rstream available)");

        return 0;

    }

    if (rs_fin)

        ossl_quic_stream_map_notify_totally_received(&ch->qsm, stream);

    *datalen = frame_data.len;

    return 1;

}

static void update_streams(QUIC_STREAM *s, void *arg)

{

    QUIC_CHANNEL *ch = arg;

    ossl_quic_stream_map_update_state(&ch->qsm, s);

}

static void update_streams_bidi(QUIC_STREAM *s, void *arg)

{

    QUIC_CHANNEL *ch = arg;

    if (!ossl_quic_stream_is_bidi(s))

        return;

    ossl_quic_stream_map_update_state(&ch->qsm, s);

}

static void update_streams_uni(QUIC_STREAM *s, void *arg)

{

    QUIC_CHANNEL *ch = arg;

    if (ossl_quic_stream_is_bidi(s))

        return;

    ossl_quic_stream_map_update_state(&ch->qsm, s);

}

static int depack_do_frame_max_data(PACKET *pkt, QUIC_CHANNEL *ch,

                                    OSSL_ACKM_RX_PKT *ackm_data)

{

    uint64_t max_data = 0;

    if (!ossl_quic_wire_decode_frame_max_data(pkt, &max_data)) {

        ossl_quic_channel_raise_protocol_error(ch,

                                               OSSL_QUIC_ERR_FRAME_ENCODING_ERROR,

                                               OSSL_QUIC_FRAME_TYPE_MAX_DATA,

                                               "decode error");

        return 0;

    }

    ossl_quic_txfc_bump_cwm(&ch->conn_txfc, max_data);

    ossl_quic_stream_map_visit(&ch->qsm, update_streams, ch);

    return 1;

}

static int depack_do_frame_max_stream_data(PACKET *pkt,

                                           QUIC_CHANNEL *ch,

                                           OSSL_ACKM_RX_PKT *ackm_data)

{

    uint64_t stream_id = 0;

    uint64_t max_stream_data = 0;

    QUIC_STREAM *stream;

    if (!ossl_quic_wire_decode_frame_max_stream_data(pkt, &stream_id,

                                                     &max_stream_data)) {

        ossl_quic_channel_raise_protocol_error(ch,

                                               OSSL_QUIC_ERR_FRAME_ENCODING_ERROR,

                                               OSSL_QUIC_FRAME_TYPE_MAX_STREAM_DATA,

                                               "decode error");

        return 0;

    }

    if (!depack_do_implicit_stream_create(ch, stream_id,

                                          OSSL_QUIC_FRAME_TYPE_MAX_STREAM_DATA,

                                          &stream))

        return 0; /* error already raised for us */

    if (stream == NULL)

        return 1; /* old deleted stream, not a protocol violation, ignore */

    if (!ossl_quic_stream_has_send(stream)) {

        ossl_quic_channel_raise_protocol_error(ch,

                                               OSSL_QUIC_ERR_STREAM_STATE_ERROR,

                                               OSSL_QUIC_FRAME_TYPE_MAX_STREAM_DATA,

                                               "MAX_STREAM_DATA for TX only "

                                               "stream");

        return 0;

    }

    ossl_quic_txfc_bump_cwm(&stream->txfc, max_stream_data);

    ossl_quic_stream_map_update_state(&ch->qsm, stream);

    return 1;

}

static int depack_do_frame_max_streams(PACKET *pkt,

                                       QUIC_CHANNEL *ch,

                                       OSSL_ACKM_RX_PKT *ackm_data,

                                       uint64_t frame_type)

{

    uint64_t max_streams = 0;

    if (!ossl_quic_wire_decode_frame_max_streams(pkt, &max_streams)) {

        ossl_quic_channel_raise_protocol_error(ch,

                                               OSSL_QUIC_ERR_FRAME_ENCODING_ERROR,

                                               frame_type,

                                               "decode error");

        return 0;

    }

    if (max_streams > (((uint64_t)1) << 60)) {

        ossl_quic_channel_raise_protocol_error(ch,

                                               OSSL_QUIC_ERR_FRAME_ENCODING_ERROR,

                                               frame_type,

                                               "invalid max streams value");

        return 0;

    }

    switch (frame_type) {

    case OSSL_QUIC_FRAME_TYPE_MAX_STREAMS_BIDI:

        if (max_streams > ch->max_local_streams_bidi)

            ch->max_local_streams_bidi = max_streams;

        /* Some streams may now be able to send. */

        ossl_quic_stream_map_visit(&ch->qsm, update_streams_bidi, ch);

        break;

    case OSSL_QUIC_FRAME_TYPE_MAX_STREAMS_UNI:

        if (max_streams > ch->max_local_streams_uni)

            ch->max_local_streams_uni = max_streams;

        /* Some streams may now be able to send. */

        ossl_quic_stream_map_visit(&ch->qsm, update_streams_uni, ch);

        break;

    default:

        ossl_quic_channel_raise_protocol_error(ch,

                                               OSSL_QUIC_ERR_FRAME_ENCODING_ERROR,

                                               frame_type,

                                               "decode error");

        return 0;

    }

    return 1;

}

static int depack_do_frame_data_blocked(PACKET *pkt,

                                        QUIC_CHANNEL *ch,

                                        OSSL_ACKM_RX_PKT *ackm_data)

{

    uint64_t max_data = 0;

    if (!ossl_quic_wire_decode_frame_data_blocked(pkt, &max_data)) {

        ossl_quic_channel_raise_protocol_error(ch,

                                               OSSL_QUIC_ERR_FRAME_ENCODING_ERROR,

                                               OSSL_QUIC_FRAME_TYPE_DATA_BLOCKED,

                                               "decode error");

        return 0;

    }

    /* No-op - informative/debugging frame. */

    return 1;

}

static int depack_do_frame_stream_data_blocked(PACKET *pkt,

                                               QUIC_CHANNEL *ch,

                                               OSSL_ACKM_RX_PKT *ackm_data)

{

    uint64_t stream_id = 0;

    uint64_t max_data = 0;

    QUIC_STREAM *stream;

    if (!ossl_quic_wire_decode_frame_stream_data_blocked(pkt, &stream_id,

                                                         &max_data)) {

        ossl_quic_channel_raise_protocol_error(ch,

                                               OSSL_QUIC_ERR_FRAME_ENCODING_ERROR,

                                               OSSL_QUIC_FRAME_TYPE_STREAM_DATA_BLOCKED,

                                               "decode error");

        return 0;

    }

    /*

     * This is an informative/debugging frame, so we don't have to do anything,

     * but it does trigger stream creation.

     */

    if (!depack_do_implicit_stream_create(ch, stream_id,

                                          OSSL_QUIC_FRAME_TYPE_STREAM_DATA_BLOCKED,

                                          &stream))

        return 0; /* error already raised for us */

    if (stream == NULL)

        return 1; /* old deleted stream, not a protocol violation, ignore */

    if (!ossl_quic_stream_has_recv(stream)) {

        /*

         * RFC 9000 s. 19.14: "An endpoint that receives a STREAM_DATA_BLOCKED

         * frame for a send-only stream MUST terminate the connection with error

         * STREAM_STATE_ERROR."

         */

        ossl_quic_channel_raise_protocol_error(ch,

                                               OSSL_QUIC_ERR_STREAM_STATE_ERROR,

                                               OSSL_QUIC_FRAME_TYPE_STREAM_DATA_BLOCKED,

                                               "STREAM_DATA_BLOCKED frame for "

                                               "TX only stream");

        return 0;

    }

    /* No-op - informative/debugging frame. */

    return 1;

}

static int depack_do_frame_streams_blocked(PACKET *pkt,

                                           QUIC_CHANNEL *ch,

                                           OSSL_ACKM_RX_PKT *ackm_data,

                                           uint64_t frame_type)

{

    uint64_t max_data = 0;

    if (!ossl_quic_wire_decode_frame_streams_blocked(pkt, &max_data)) {

        ossl_quic_channel_raise_protocol_error(ch,

                                               OSSL_QUIC_ERR_FRAME_ENCODING_ERROR,

                                               frame_type,

                                               "decode error");

        return 0;

    }

    if (max_data > (((uint64_t)1) << 60)) {

        /*

         * RFC 9000 s. 19.14: "This value cannot exceed 2**60, as it is not

         * possible to encode stream IDs larger than 2**62 - 1. Receipt of a

         * frame that encodes a larger stream ID MUST be treated as a connection

         * error of type STREAM_LIMIT_ERROR or FRAME_ENCODING_ERROR."

         */

        ossl_quic_channel_raise_protocol_error(ch,

                                               OSSL_QUIC_ERR_STREAM_LIMIT_ERROR,

                                               frame_type,

                                               "invalid stream count limit");

        return 0;

    }

    /* No-op - informative/debugging frame. */

    return 1;

}

static int depack_do_frame_new_conn_id(PACKET *pkt,

                                       QUIC_CHANNEL *ch,

                                       OSSL_ACKM_RX_PKT *ackm_data)

{

    OSSL_QUIC_FRAME_NEW_CONN_ID frame_data;

    if (!ossl_quic_wire_decode_frame_new_conn_id(pkt, &frame_data)) {

        ossl_quic_channel_raise_protocol_error(ch,

                                               OSSL_QUIC_ERR_FRAME_ENCODING_ERROR,

                                               OSSL_QUIC_FRAME_TYPE_NEW_CONN_ID,

                                               "decode error");

        return 0;

    }

    ossl_quic_channel_on_new_conn_id(ch, &frame_data);

    return 1;

}

static int depack_do_frame_retire_conn_id(PACKET *pkt,

                                          QUIC_CHANNEL *ch,

                                          OSSL_ACKM_RX_PKT *ackm_data)

{

    uint64_t seq_num;

    if (!ossl_quic_wire_decode_frame_retire_conn_id(pkt, &seq_num)) {

        ossl_quic_channel_raise_protocol_error(ch,

                                               OSSL_QUIC_ERR_FRAME_ENCODING_ERROR,

                                               OSSL_QUIC_FRAME_TYPE_RETIRE_CONN_ID,

                                               "decode error");

        return 0;

    }

    /*

     * RFC 9000 s. 19.16: "An endpoint cannot send this frame if it was provided

     * with a zero-length connection ID by its peer. An endpoint that provides a

     * zero-length connection ID MUST treat receipt of a RETIRE_CONNECTION_ID

     * frame as a connection error of type PROTOCOL_VIOLATION."

     *

     * Since we always use a zero-length SCID as a client, there is no case

     * where it is valid for a server to send this. Our server support is

     * currently non-conformant and for internal testing use; simply handle it

     * as a no-op in this case.

     *

     * TODO(QUIC FUTURE): Revise and implement correctly for server support.

     */

    if (!ch->is_server) {

        ossl_quic_channel_raise_protocol_error(ch,

                                               OSSL_QUIC_ERR_PROTOCOL_VIOLATION,

                                               OSSL_QUIC_FRAME_TYPE_RETIRE_CONN_ID,

                                               "conn has zero-length CID");

        return 0;

    }

    return 1;

}

static void free_path_response(unsigned char *buf, size_t buf_len, void *arg)

{

    OPENSSL_free(buf);

}

static int depack_do_frame_path_challenge(PACKET *pkt,

                                          QUIC_CHANNEL *ch,

                                          OSSL_ACKM_RX_PKT *ackm_data)

{

    uint64_t frame_data = 0;

    unsigned char *encoded = NULL;

    size_t encoded_len;

    WPACKET wpkt;

    if (!ossl_quic_wire_decode_frame_path_challenge(pkt, &frame_data)) {

        ossl_quic_channel_raise_protocol_error(ch,

                                               OSSL_QUIC_ERR_FRAME_ENCODING_ERROR,

                                               OSSL_QUIC_FRAME_TYPE_PATH_CHALLENGE,

                                               "decode error");

        return 0;

    }

    /*

     * RFC 9000 s. 8.2.2: On receiving a PATH_CHALLENGE frame, an endpoint MUST

     * respond by echoing the data contained in the PATH_CHALLENGE frame in a

     * PATH_RESPONSE frame.

     *

     * TODO(QUIC FUTURE): We should try to avoid allocation here in the future.

     */

    encoded_len = sizeof(uint64_t) + 1;

    if ((encoded = OPENSSL_malloc(encoded_len)) == NULL)

        goto err;

    if (!WPACKET_init_static_len(&wpkt, encoded, encoded_len, 0))

        goto err;

    if (!ossl_quic_wire_encode_frame_path_response(&wpkt, frame_data)) {

        WPACKET_cleanup(&wpkt);

        goto err;

    }

    WPACKET_finish(&wpkt);

    if (!ossl_quic_cfq_add_frame(ch->cfq, 0, QUIC_PN_SPACE_APP,

                                 OSSL_QUIC_FRAME_TYPE_PATH_RESPONSE,

                                 QUIC_CFQ_ITEM_FLAG_UNRELIABLE,

                                 encoded, encoded_len,

                                 free_path_response, NULL))

        goto err;

    return 1;

err:

    OPENSSL_free(encoded);

    ossl_quic_channel_raise_protocol_error(ch, OSSL_QUIC_ERR_INTERNAL_ERROR,

                                           OSSL_QUIC_FRAME_TYPE_PATH_CHALLENGE,

                                           "internal error");

    return 0;

}

static int depack_do_frame_path_response(PACKET *pkt,

                                         QUIC_CHANNEL *ch,

                                         OSSL_ACKM_RX_PKT *ackm_data)

{

    uint64_t frame_data = 0;

    if (!ossl_quic_wire_decode_frame_path_response(pkt, &frame_data)) {

        ossl_quic_channel_raise_protocol_error(ch,

                                               OSSL_QUIC_ERR_FRAME_ENCODING_ERROR,

                                               OSSL_QUIC_FRAME_TYPE_PATH_RESPONSE,

                                               "decode error");

        return 0;

    }

    /* TODO(QUIC MULTIPATH): ADD CODE to send |frame_data| to the ch manager */

    return 1;

}

static int depack_do_frame_conn_close(PACKET *pkt, QUIC_CHANNEL *ch,

                                      uint64_t frame_type)

{

    OSSL_QUIC_FRAME_CONN_CLOSE frame_data;

    if (!ossl_quic_wire_decode_frame_conn_close(pkt, &frame_data)) {

        ossl_quic_channel_raise_protocol_error(ch,

                                               OSSL_QUIC_ERR_FRAME_ENCODING_ERROR,

                                               frame_type,

                                               "decode error");

        return 0;

    }

    ossl_quic_channel_on_remote_conn_close(ch, &frame_data);

    return 1;

}

static int depack_do_frame_handshake_done(PACKET *pkt,

                                          QUIC_CHANNEL *ch,

                                          OSSL_ACKM_RX_PKT *ackm_data)

{