/*

 * 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

 */

#include <openssl/err.h>

#include "internal/common.h"

#include "internal/time.h"

#include "internal/quic_stream.h"

#include "internal/quic_sf_list.h"

#include "internal/ring_buf.h"

struct quic_rstream_st {

    SFRAME_LIST fl;

    QUIC_RXFC *rxfc;

    OSSL_STATM *statm;

    UINT_RANGE head_range;

    struct ring_buf rbuf;

};

QUIC_RSTREAM *ossl_quic_rstream_new(QUIC_RXFC *rxfc,

    OSSL_STATM *statm, size_t rbuf_size)

{

    QUIC_RSTREAM *ret = OPENSSL_zalloc(sizeof(*ret));

    if (ret == NULL)

        return NULL;

    ring_buf_init(&ret->rbuf);

    if (!ring_buf_resize(&ret->rbuf, rbuf_size, 0)) {

        OPENSSL_free(ret);

        return NULL;

    }

    ossl_sframe_list_init(&ret->fl);

    ret->rxfc = rxfc;

    ret->statm = statm;

    return ret;

}

void ossl_quic_rstream_free(QUIC_RSTREAM *qrs)

{

    int cleanse;

    if (qrs == NULL)

        return;

    cleanse = qrs->fl.cleanse;

    ossl_sframe_list_destroy(&qrs->fl);

    ring_buf_destroy(&qrs->rbuf, cleanse);

    OPENSSL_free(qrs);

}

int ossl_quic_rstream_queue_data(QUIC_RSTREAM *qrs, OSSL_QRX_PKT *pkt,

    uint64_t offset,

    const unsigned char *data, uint64_t data_len,

    int fin)

{

    UINT_RANGE range;

    if ((data == NULL && data_len != 0) || (data_len == 0 && fin == 0)) {

        /* empty frame allowed only at the end of the stream */

        ERR_raise(ERR_LIB_SSL, ERR_R_INTERNAL_ERROR);

        return 0;

    }

    range.start = offset;

    range.end = offset + data_len;

    return ossl_sframe_list_insert(&qrs->fl, &range, pkt, data, fin);

}

static int read_internal(QUIC_RSTREAM *qrs, unsigned char *buf, size_t size,

    size_t *readbytes, int *fin, int drop)

{

    void *iter = NULL;

    UINT_RANGE range;

    const unsigned char *data;

    uint64_t offset = 0;

    size_t readbytes_ = 0;

    int fin_ = 0, ret = 1;

    while (ossl_sframe_list_peek(&qrs->fl, &iter, &range, &data, &fin_)) {

        size_t l = (size_t)(range.end - range.start);

        if (l > size) {

            l = size;

            fin_ = 0;

        }

        offset = range.start + l;

        if (l == 0)

            break;

        if (data == NULL) {

            size_t max_len;

            data = ring_buf_get_ptr(&qrs->rbuf, range.start, &max_len);

            if (!ossl_assert(data != NULL))

                return 0;

            if (max_len < l) {

                memcpy(buf, data, max_len);

                size -= max_len;

                buf += max_len;

                readbytes_ += max_len;

                l -= max_len;

                data = ring_buf_get_ptr(&qrs->rbuf, range.start + max_len,

                    &max_len);

                if (!ossl_assert(data != NULL) || !ossl_assert(max_len > l))

                    return 0;

            }

        }

        memcpy(buf, data, l);

        size -= l;

        buf += l;

        readbytes_ += l;

        if (size == 0)

            break;

    }

    if (drop && offset != 0) {

        ret = ossl_sframe_list_drop_frames(&qrs->fl, offset);

        ring_buf_cpop_range(&qrs->rbuf, 0, offset - 1, qrs->fl.cleanse);

    }

    if (ret) {

        *readbytes = readbytes_;

        *fin = fin_;

    }

    return ret;

}

static OSSL_TIME get_rtt(QUIC_RSTREAM *qrs)

{

    OSSL_TIME rtt;

    if (qrs->statm != NULL) {

        OSSL_RTT_INFO rtt_info;

        ossl_statm_get_rtt_info(qrs->statm, &rtt_info);

        rtt = rtt_info.smoothed_rtt;

    } else {

        rtt = ossl_time_zero();

    }

    return rtt;

}

int ossl_quic_rstream_read(QUIC_RSTREAM *qrs, unsigned char *buf, size_t size,

    size_t *readbytes, int *fin)

{

    OSSL_TIME rtt = get_rtt(qrs);

    if (!read_internal(qrs, buf, size, readbytes, fin, 1))

        return 0;

    if (qrs->rxfc != NULL

        && !ossl_quic_rxfc_on_retire(qrs->rxfc, *readbytes, rtt))

        return 0;

    return 1;

}

int ossl_quic_rstream_peek(QUIC_RSTREAM *qrs, unsigned char *buf, size_t size,

    size_t *readbytes, int *fin)

{

    return read_internal(qrs, buf, size, readbytes, fin, 0);

}

int ossl_quic_rstream_available(QUIC_RSTREAM *qrs, size_t *avail, int *fin)

{

    void *iter = NULL;

    UINT_RANGE range;

    const unsigned char *data;

    uint64_t avail_ = 0;

    while (ossl_sframe_list_peek(&qrs->fl, &iter, &range, &data, fin))

        avail_ += range.end - range.start;

#if SIZE_MAX < UINT64_MAX

    *avail = avail_ > SIZE_MAX ? SIZE_MAX : (size_t)avail_;

#else

    *avail = (size_t)avail_;

#endif

    return 1;

}

int ossl_quic_rstream_get_record(QUIC_RSTREAM *qrs,

    const unsigned char **record, size_t *rec_len,

    int *fin)

{

    const unsigned char *record_ = NULL;

    size_t rec_len_, max_len;

    if (!ossl_sframe_list_lock_head(&qrs->fl, &qrs->head_range, &record_, fin)) {

        /* No head frame to lock and return */

        *record = NULL;

        *rec_len = 0;

        return 1;

    }

    /* if final empty frame, we drop it immediately */

    if (qrs->head_range.end == qrs->head_range.start) {

        if (!ossl_assert(*fin))

            return 0;

        if (!ossl_sframe_list_drop_frames(&qrs->fl, qrs->head_range.end))

            return 0;

    }

    rec_len_ = (size_t)(qrs->head_range.end - qrs->head_range.start);

    if (record_ == NULL && rec_len_ != 0) {

        record_ = ring_buf_get_ptr(&qrs->rbuf, qrs->head_range.start,

            &max_len);

        if (!ossl_assert(record_ != NULL))

            return 0;

        if (max_len < rec_len_) {

            rec_len_ = max_len;

            qrs->head_range.end = qrs->head_range.start + max_len;

        }

    }

    *rec_len = rec_len_;

    *record = record_;

    return 1;

}

int ossl_quic_rstream_release_record(QUIC_RSTREAM *qrs, size_t read_len)

{

    uint64_t offset;

    if (!ossl_sframe_list_is_head_locked(&qrs->fl))

        return 0;

    if (read_len > qrs->head_range.end - qrs->head_range.start) {

        if (read_len != SIZE_MAX)

            return 0;

        offset = qrs->head_range.end;

    } else {

        offset = qrs->head_range.start + read_len;

    }

    if (!ossl_sframe_list_drop_frames(&qrs->fl, offset))

        return 0;

    if (offset > 0)

        ring_buf_cpop_range(&qrs->rbuf, 0, offset - 1, qrs->fl.cleanse);

    if (qrs->rxfc != NULL) {

        OSSL_TIME rtt = get_rtt(qrs);

        if (!ossl_quic_rxfc_on_retire(qrs->rxfc, offset, rtt))

            return 0;

    }

    return 1;

}

static int write_at_ring_buf_cb(uint64_t logical_offset,

    const unsigned char *buf,

    size_t buf_len,

    void *cb_arg)

{

    struct ring_buf *rbuf = cb_arg;

    return ring_buf_write_at(rbuf, logical_offset, buf, buf_len);

}

int ossl_quic_rstream_move_to_rbuf(QUIC_RSTREAM *qrs)

{

    if (ring_buf_avail(&qrs->rbuf) == 0)

        return 0;

    return ossl_sframe_list_move_data(&qrs->fl,

        write_at_ring_buf_cb, &qrs->rbuf);

}

int ossl_quic_rstream_resize_rbuf(QUIC_RSTREAM *qrs, size_t rbuf_size)

{

    if (ossl_sframe_list_is_head_locked(&qrs->fl))

        return 0;

    if (!ring_buf_resize(&qrs->rbuf, rbuf_size, qrs->fl.cleanse))

        return 0;

    return 1;

}

void ossl_quic_rstream_set_cleanse(QUIC_RSTREAM *qrs, int cleanse)

{

    qrs->fl.cleanse = cleanse;

}