/*
 * Copyright (c) 2018 Yubico AB. All rights reserved.
 * Use of this source code is governed by a BSD-style
 * license that can be found in the LICENSE file.
 */

#include "fido.h"
#include "packed.h"

PACKED_TYPE(frame_t,
struct frame {
        uint32_t cid; /* channel id */
        union {
                uint8_t type;
                struct {
                        uint8_t cmd;
                        uint8_t bcnth;
                        uint8_t bcntl;
                        uint8_t data[CTAP_MAX_REPORT_LEN - CTAP_INIT_HEADER_LEN];
                } init;
                struct {
                        uint8_t seq;
                        uint8_t data[CTAP_MAX_REPORT_LEN - CTAP_CONT_HEADER_LEN];
                } cont;
        } body;
})

#ifndef MIN
#define MIN(x, y) ((x) > (y) ? (y) : (x))
#endif

static int
tx_pkt(fido_dev_t *d, const void *pkt, size_t len, int *ms)
{
        struct timespec ts;
        int n;

        if (fido_time_now(&ts) != 0)
                return (-1);

        n = d->io.write(d->io_handle, pkt, len);

        if (fido_time_delta(&ts, ms) != 0)
                return (-1);

        return (n);
}

static int
tx_empty(fido_dev_t *d, uint8_t cmd, int *ms)
{
        struct frame    *fp;
        unsigned char    pkt[sizeof(*fp) + 1];
        const size_t     len = d->tx_len + 1;
        int              n;

        memset(&pkt, 0, sizeof(pkt));
        fp = (struct frame *)(pkt + 1);
        fp->cid = d->cid;
        fp->body.init.cmd = CTAP_FRAME_INIT | cmd;

        if (len > sizeof(pkt) || (n = tx_pkt(d, pkt, len, ms)) < 0 ||
            (size_t)n != len)
                return (-1);

        return (0);
}

static size_t
tx_preamble(fido_dev_t *d, uint8_t cmd, const void *buf, size_t count, int *ms)
{
        struct frame    *fp;
        unsigned char    pkt[sizeof(*fp) + 1];
        const size_t     len = d->tx_len + 1;
        int              n;

        if (d->tx_len - CTAP_INIT_HEADER_LEN > sizeof(fp->body.init.data))
                return (0);

        memset(&pkt, 0, sizeof(pkt));
        fp = (struct frame *)(pkt + 1);
        fp->cid = d->cid;
        fp->body.init.cmd = CTAP_FRAME_INIT | cmd;
        fp->body.init.bcnth = (count >> 8) & 0xff;
        fp->body.init.bcntl = count & 0xff;
        count = MIN(count, d->tx_len - CTAP_INIT_HEADER_LEN);
        memcpy(&fp->body.init.data, buf, count);

        if (len > sizeof(pkt) || (n = tx_pkt(d, pkt, len, ms)) < 0 ||
            (size_t)n != len)
                return (0);

        return (count);
}

static size_t
tx_frame(fido_dev_t *d, uint8_t seq, const void *buf, size_t count, int *ms)
{
        struct frame    *fp;
        unsigned char    pkt[sizeof(*fp) + 1];
        const size_t     len = d->tx_len + 1;
        int              n;

        if (d->tx_len - CTAP_CONT_HEADER_LEN > sizeof(fp->body.cont.data))
                return (0);

        memset(&pkt, 0, sizeof(pkt));
        fp = (struct frame *)(pkt + 1);
        fp->cid = d->cid;
        fp->body.cont.seq = seq;
        count = MIN(count, d->tx_len - CTAP_CONT_HEADER_LEN);
        memcpy(&fp->body.cont.data, buf, count);

        if (len > sizeof(pkt) || (n = tx_pkt(d, pkt, len, ms)) < 0 ||
            (size_t)n != len)
                return (0);

        return (count);
}

static int
tx(fido_dev_t *d, uint8_t cmd, const unsigned char *buf, size_t count, int *ms)
{
        size_t n, sent;

        if ((sent = tx_preamble(d, cmd, buf, count, ms)) == 0) {
                fido_log_debug("%s: tx_preamble", __func__);
                return (-1);
        }

        for (uint8_t seq = 0; sent < count; sent += n) {
                if (seq & 0x80) {
                        fido_log_debug("%s: seq & 0x80", __func__);
                        return (-1);
                }
                if ((n = tx_frame(d, seq++, buf + sent, count - sent,
                    ms)) == 0) {
                        fido_log_debug("%s: tx_frame", __func__);
                        return (-1);
                }
        }

        return (0);
}

static int
transport_tx(fido_dev_t *d, uint8_t cmd, const void *buf, size_t count, int *ms)
{
        struct timespec ts;
        int n;

        if (fido_time_now(&ts) != 0)
                return (-1);

        n = d->transport.tx(d, cmd, buf, count);

        if (fido_time_delta(&ts, ms) != 0)
                return (-1);

        return (n);
}

int
fido_tx(fido_dev_t *d, uint8_t cmd, const void *buf, size_t count, int *ms)
{
        fido_log_debug("%s: dev=%p, cmd=0x%02x", __func__, (void *)d, cmd);
        fido_log_xxd(buf, count, "%s", __func__);

        if (d->transport.tx != NULL)
                return (transport_tx(d, cmd, buf, count, ms));
        if (d->io_handle == NULL || d->io.write == NULL || count > UINT16_MAX) {
                fido_log_debug("%s: invalid argument", __func__);
                return (-1);
        }

        return (count == 0 ? tx_empty(d, cmd, ms) : tx(d, cmd, buf, count, ms));
}

static int
rx_frame(fido_dev_t *d, struct frame *fp, int *ms)
{
        struct timespec ts;
        int n;

        memset(fp, 0, sizeof(*fp));

        if (fido_time_now(&ts) != 0)
                return (-1);

        if (d->rx_len > sizeof(*fp) || (n = d->io.read(d->io_handle,
            (unsigned char *)fp, d->rx_len, *ms)) < 0 || (size_t)n != d->rx_len)
                return (-1);

        return (fido_time_delta(&ts, ms));
}

static int
rx_preamble(fido_dev_t *d, uint8_t cmd, struct frame *fp, int *ms)
{
        do {
                if (rx_frame(d, fp, ms) < 0)
                        return (-1);
#ifdef FIDO_FUZZ
                fp->cid = d->cid;
#endif
        } while (fp->cid != d->cid || (fp->cid == d->cid &&
            fp->body.init.cmd == (CTAP_FRAME_INIT | CTAP_KEEPALIVE)));

        if (d->rx_len > sizeof(*fp))
                return (-1);

        fido_log_xxd(fp, d->rx_len, "%s", __func__);
#ifdef FIDO_FUZZ
        fp->body.init.cmd = (CTAP_FRAME_INIT | cmd);
#endif

        if (fp->cid != d->cid || fp->body.init.cmd != (CTAP_FRAME_INIT | cmd)) {
                fido_log_debug("%s: cid (0x%x, 0x%x), cmd (0x%02x, 0x%02x)",
                    __func__, fp->cid, d->cid, fp->body.init.cmd, cmd);
                return (-1);
        }

        return (0);
}

static int
rx(fido_dev_t *d, uint8_t cmd, unsigned char *buf, size_t count, int *ms)
{
        struct frame f;
        size_t r, payload_len, init_data_len, cont_data_len;

        if (d->rx_len <= CTAP_INIT_HEADER_LEN ||
            d->rx_len <= CTAP_CONT_HEADER_LEN)
                return (-1);

        init_data_len = d->rx_len - CTAP_INIT_HEADER_LEN;
        cont_data_len = d->rx_len - CTAP_CONT_HEADER_LEN;

        if (init_data_len > sizeof(f.body.init.data) ||
            cont_data_len > sizeof(f.body.cont.data))
                return (-1);

        if (rx_preamble(d, cmd, &f, ms) < 0) {
                fido_log_debug("%s: rx_preamble", __func__);
                return (-1);
        }

        payload_len = (size_t)((f.body.init.bcnth << 8) | f.body.init.bcntl);
        fido_log_debug("%s: payload_len=%zu", __func__, payload_len);

        if (count < payload_len) {
                fido_log_debug("%s: count < payload_len", __func__);
                return (-1);
        }

        if (payload_len < init_data_len) {
                memcpy(buf, f.body.init.data, payload_len);
                return ((int)payload_len);
        }

        memcpy(buf, f.body.init.data, init_data_len);
        r = init_data_len;

        for (int seq = 0; r < payload_len; seq++) {
                if (rx_frame(d, &f, ms) < 0) {
                        fido_log_debug("%s: rx_frame", __func__);
                        return (-1);
                }

                fido_log_xxd(&f, d->rx_len, "%s", __func__);
#ifdef FIDO_FUZZ
                f.cid = d->cid;
                f.body.cont.seq = (uint8_t)seq;
#endif

                if (f.cid != d->cid || f.body.cont.seq != seq) {
                        fido_log_debug("%s: cid (0x%x, 0x%x), seq (%d, %d)",
                            __func__, f.cid, d->cid, f.body.cont.seq, seq);
                        return (-1);
                }

                if (payload_len - r > cont_data_len) {
                        memcpy(buf + r, f.body.cont.data, cont_data_len);
                        r += cont_data_len;
                } else {
                        memcpy(buf + r, f.body.cont.data, payload_len - r);
                        r += payload_len - r; /* break */
                }
        }

        return ((int)r);
}

static int
transport_rx(fido_dev_t *d, uint8_t cmd, void *buf, size_t count, int *ms)
{
        struct timespec ts;
        int n;

        if (fido_time_now(&ts) != 0)
                return (-1);

        n = d->transport.rx(d, cmd, buf, count, *ms);

        if (fido_time_delta(&ts, ms) != 0)
                return (-1);

        return (n);
}

int
fido_rx(fido_dev_t *d, uint8_t cmd, void *buf, size_t count, int *ms)
{
        int n;

        fido_log_debug("%s: dev=%p, cmd=0x%02x, ms=%d", __func__, (void *)d,
            cmd, *ms);

        if (d->transport.rx != NULL)
                return (transport_rx(d, cmd, buf, count, ms));
        if (d->io_handle == NULL || d->io.read == NULL || count > UINT16_MAX) {
                fido_log_debug("%s: invalid argument", __func__);
                return (-1);
        }
        if ((n = rx(d, cmd, buf, count, ms)) >= 0)
                fido_log_xxd(buf, (size_t)n, "%s", __func__);

        return (n);
}

int
fido_rx_cbor_status(fido_dev_t *d, int *ms)
{
        unsigned char   reply[FIDO_MAXMSG];
        int             reply_len;

        if ((reply_len = fido_rx(d, CTAP_CMD_CBOR, &reply, sizeof(reply),
            ms)) < 0 || (size_t)reply_len < 1) {
                fido_log_debug("%s: fido_rx", __func__);
                return (FIDO_ERR_RX);
        }

        return (reply[0]);
}