/*
 * Copyright (c) 2017 Fastly, Kazuho Oku
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to
 * deal in the Software without restriction, including without limitation the
 * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
 * sell copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
 * IN THE SOFTWARE.
 */
#include <assert.h>
#include <string.h>
#include "quicly/frame.h"

uint8_t *quicly_encode_path_challenge_frame(uint8_t *dst, int is_response, const uint8_t *data)
{
    *dst++ = is_response ? QUICLY_FRAME_TYPE_PATH_RESPONSE : QUICLY_FRAME_TYPE_PATH_CHALLENGE;
    memcpy(dst, data, QUICLY_PATH_CHALLENGE_DATA_LEN);
    dst += QUICLY_PATH_CHALLENGE_DATA_LEN;
    return dst;
}

uint8_t *quicly_encode_ack_frame(uint8_t *dst, uint8_t *dst_end, quicly_ranges_t *ranges, uint64_t *ecn_counts, uint64_t ack_delay)
{
#define WRITE_BLOCK(start, end)                                                                                                    \
    do {                                                                                                                           \
        uint64_t _start = (start), _end = (end);                                                                                   \
        assert(_start < _end);                                                                                                     \
        if (dst_end - dst < 8)                                                                                                     \
            return NULL;                                                                                                           \
        dst = quicly_encodev(dst, _end - _start - 1);                                                                              \
    } while (0)

    /* emit ACK_ECN frame if any of the three ECN counts are non-zero */
    uint8_t frame_type = (ecn_counts[0] | ecn_counts[1] | ecn_counts[2]) != 0 ? QUICLY_FRAME_TYPE_ACK_ECN : QUICLY_FRAME_TYPE_ACK;
    size_t range_index = ranges->num_ranges - 1;

    assert(ranges->num_ranges != 0);

    /* number of bytes being emitted without space check are 1 + 8 + 8 + 1 bytes (as defined in QUICLY_ACK_FRAME_CAPACITY) */
    *dst++ = frame_type;
    dst = quicly_encodev(dst, ranges->ranges[range_index].end - 1); /* largest acknowledged */
    dst = quicly_encodev(dst, ack_delay);                           /* ack delay */
    PTLS_BUILD_ASSERT(QUICLY_MAX_ACK_BLOCKS - 1 <= 63);
    *dst++ = (uint8_t)(ranges->num_ranges - 1); /* ack blocks */

    while (1) {
        WRITE_BLOCK(ranges->ranges[range_index].start, ranges->ranges[range_index].end); /* ACK block count */
        if (range_index-- == 0)
            break;
        WRITE_BLOCK(ranges->ranges[range_index].end, ranges->ranges[range_index + 1].start);
    }

    if (frame_type == QUICLY_FRAME_TYPE_ACK_ECN) {
        uint8_t buf[24], *p = buf;
        for (size_t i = 0; i < 3; ++i)
            p = quicly_encodev(p, ecn_counts[i]);
        size_t len = p - buf;
        if (dst_end - dst < len)
            return NULL;
        memcpy(dst, buf, len);
        dst += len;
    }

    return dst;

#undef WRITE_BLOCK
}

int quicly_decode_ack_frame(const uint8_t **src, const uint8_t *end, quicly_ack_frame_t *frame, int is_ack_ecn)
{
    uint64_t i, num_gaps, gap, ack_range;

    if ((frame->largest_acknowledged = quicly_decodev(src, end)) == UINT64_MAX)
        goto Error;
    if ((frame->ack_delay = quicly_decodev(src, end)) == UINT64_MAX)
        goto Error;
    if ((num_gaps = quicly_decodev(src, end)) == UINT64_MAX)
        goto Error;

    if ((ack_range = quicly_decodev(src, end)) == UINT64_MAX)
        goto Error;
    if (frame->largest_acknowledged < ack_range)
        goto Error;
    frame->smallest_acknowledged = frame->largest_acknowledged - ack_range;
    frame->ack_block_lengths[0] = ack_range + 1;
    frame->num_gaps = 0;

    for (i = 0; i != num_gaps; ++i) {
        if ((gap = quicly_decodev(src, end)) == UINT64_MAX)
            goto Error;
        if ((ack_range = quicly_decodev(src, end)) == UINT64_MAX)
            goto Error;
        if (i < QUICLY_ACK_MAX_GAPS) {
            if (frame->smallest_acknowledged < gap + ack_range + 2)
                goto Error;
            frame->gaps[i] = gap + 1;
            frame->ack_block_lengths[i + 1] = ack_range + 1;
            frame->smallest_acknowledged -= gap + ack_range + 2;
            ++frame->num_gaps;
        }
    }

    if (is_ack_ecn) {
        for (i = 0; i < PTLS_ELEMENTSOF(frame->ecn_counts); ++i)
            if ((frame->ecn_counts[i] = quicly_decodev(src, end)) == UINT64_MAX)
                goto Error;
    } else {
        for (i = 0; i < PTLS_ELEMENTSOF(frame->ecn_counts); ++i)
            frame->ecn_counts[i] = 0;
    }

    return 0;
Error:
    return QUICLY_TRANSPORT_ERROR_FRAME_ENCODING;
}

uint8_t *quicly_encode_close_frame(uint8_t *const base, uint64_t error_code, uint64_t offending_frame_type,
                                   const char *reason_phrase)
{
    size_t offset = 0, reason_phrase_len = strlen(reason_phrase);

#define PUSHV(v)                                                                                                                   \
    do {                                                                                                                           \
        if (base != NULL) {                                                                                                        \
            offset = quicly_encodev(base + offset, (v)) - base;                                                                    \
        } else {                                                                                                                   \
            offset += quicly_encodev_capacity(v);                                                                                  \
        }                                                                                                                          \
    } while (0)

    PUSHV(offending_frame_type == UINT64_MAX ? QUICLY_FRAME_TYPE_APPLICATION_CLOSE : QUICLY_FRAME_TYPE_TRANSPORT_CLOSE);
    PUSHV(error_code);
    if (offending_frame_type != UINT64_MAX)
        PUSHV(offending_frame_type);
    PUSHV(reason_phrase_len);
    if (base != NULL)
        memcpy(base + offset, reason_phrase, reason_phrase_len);
    offset += reason_phrase_len;

#undef PUSHV

    return base + offset;
}
