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/*
* 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 <stdint.h>
#include <stdio.h>
#include <string.h>
#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_RPT_SIZE - 7];
} init;
struct {
uint8_t seq;
uint8_t data[CTAP_RPT_SIZE - 5];
} cont;
} body;
})
#ifndef MIN
#define MIN(x, y) ((x) > (y) ? (y) : (x))
#endif
static size_t
tx_preamble(fido_dev_t *d, uint8_t cmd, const void *buf, size_t count)
{
struct frame *fp;
unsigned char pkt[sizeof(*fp) + 1];
int n;
if (d->io.write == NULL || (cmd & 0x80) == 0)
return (0);
memset(&pkt, 0, sizeof(pkt));
fp = (struct frame *)(pkt + 1);
fp->cid = d->cid;
fp->body.init.cmd = 0x80 | cmd;
fp->body.init.bcnth = (count >> 8) & 0xff;
fp->body.init.bcntl = count & 0xff;
count = MIN(count, sizeof(fp->body.init.data));
if (count)
memcpy(&fp->body.init.data, buf, count);
n = d->io.write(d->io_handle, pkt, sizeof(pkt));
if (n < 0 || (size_t)n != sizeof(pkt))
return (0);
return (count);
}
static size_t
tx_frame(fido_dev_t *d, int seq, const void *buf, size_t count)
{
struct frame *fp;
unsigned char pkt[sizeof(*fp) + 1];
int n;
if (d->io.write == NULL || seq < 0 || seq > UINT8_MAX)
return (0);
memset(&pkt, 0, sizeof(pkt));
fp = (struct frame *)(pkt + 1);
fp->cid = d->cid;
fp->body.cont.seq = (uint8_t)seq;
count = MIN(count, sizeof(fp->body.cont.data));
memcpy(&fp->body.cont.data, buf, count);
n = d->io.write(d->io_handle, pkt, sizeof(pkt));
if (n < 0 || (size_t)n != sizeof(pkt))
return (0);
return (count);
}
int
fido_tx(fido_dev_t *d, uint8_t cmd, const void *buf, size_t count)
{
int seq = 0;
size_t sent;
fido_log_debug("%s: d=%p, cmd=0x%02x, buf=%p, count=%zu", __func__,
(void *)d, cmd, buf, count);
fido_log_xxd(buf, count);
if (d->io_handle == NULL || count > UINT16_MAX) {
fido_log_debug("%s: invalid argument (%p, %zu)", __func__,
d->io_handle, count);
return (-1);
}
if ((sent = tx_preamble(d, cmd, buf, count)) == 0) {
fido_log_debug("%s: tx_preamble", __func__);
return (-1);
}
while (sent < count) {
if (seq & 0x80) {
fido_log_debug("%s: seq & 0x80", __func__);
return (-1);
}
const uint8_t *p = (const uint8_t *)buf + sent;
size_t n = tx_frame(d, seq++, p, count - sent);
if (n == 0) {
fido_log_debug("%s: tx_frame", __func__);
return (-1);
}
sent += n;
}
return (0);
}
static int
rx_frame(fido_dev_t *d, struct frame *fp, int ms)
{
int n;
if (d->io.read == NULL)
return (-1);
n = d->io.read(d->io_handle, (unsigned char *)fp, sizeof(*fp), ms);
if (n < 0 || (size_t)n != sizeof(*fp))
return (-1);
return (0);
}
static int
rx_preamble(fido_dev_t *d, 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->body.init.cmd == (CTAP_FRAME_INIT | CTAP_KEEPALIVE));
return (0);
}
int
fido_rx(fido_dev_t *d, uint8_t cmd, void *buf, size_t count, int ms)
{
struct frame f;
uint16_t r;
uint16_t flen;
int seq;
if (d->io_handle == NULL || (cmd & 0x80) == 0) {
fido_log_debug("%s: invalid argument (%p, 0x%02x)", __func__,
d->io_handle, cmd);
return (-1);
}
if (rx_preamble(d, &f, ms) < 0) {
fido_log_debug("%s: rx_preamble", __func__);
return (-1);
}
fido_log_debug("%s: initiation frame at %p, len %zu", __func__,
(void *)&f, sizeof(f));
fido_log_xxd(&f, sizeof(f));
#ifdef FIDO_FUZZ
f.cid = d->cid;
f.body.init.cmd = cmd;
#endif
if (f.cid != d->cid || f.body.init.cmd != cmd) {
fido_log_debug("%s: cid (0x%x, 0x%x), cmd (0x%02x, 0x%02x)",
__func__, f.cid, d->cid, f.body.init.cmd, cmd);
return (-1);
}
flen = (f.body.init.bcnth << 8) | f.body.init.bcntl;
if (count < (size_t)flen) {
fido_log_debug("%s: count < flen (%zu, %zu)", __func__, count,
(size_t)flen);
return (-1);
}
if (flen < sizeof(f.body.init.data)) {
memcpy(buf, f.body.init.data, flen);
return (flen);
}
memcpy(buf, f.body.init.data, sizeof(f.body.init.data));
r = sizeof(f.body.init.data);
seq = 0;
while ((size_t)r < flen) {
if (rx_frame(d, &f, ms) < 0) {
fido_log_debug("%s: rx_frame", __func__);
return (-1);
}
fido_log_debug("%s: continuation frame at %p, len %zu",
__func__, (void *)&f, sizeof(f));
fido_log_xxd(&f, sizeof(f));
#ifdef FIDO_FUZZ
f.cid = d->cid;
f.body.cont.seq = 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);
}
uint8_t *p = (uint8_t *)buf + r;
if ((size_t)(flen - r) > sizeof(f.body.cont.data)) {
memcpy(p, f.body.cont.data, sizeof(f.body.cont.data));
r += sizeof(f.body.cont.data);
} else {
memcpy(p, f.body.cont.data, flen - r);
r += (flen - r); /* break */
}
}
fido_log_debug("%s: payload at %p, len %zu", __func__, buf, (size_t)r);
fido_log_xxd(buf, r);
return (r);
}
int
fido_rx_cbor_status(fido_dev_t *d, int ms)
{
const uint8_t cmd = CTAP_FRAME_INIT | CTAP_CMD_CBOR;
unsigned char reply[2048];
int reply_len;
if ((reply_len = fido_rx(d, cmd, &reply, sizeof(reply), ms)) < 0 ||
(size_t)reply_len < 1) {
fido_log_debug("%s: fido_rx", __func__);
return (FIDO_ERR_RX);
}
return (reply[0]);
}
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