bluez/monitor/btsnoop.c

/*
 *
 *  BlueZ - Bluetooth protocol stack for Linux
 *
 *  Copyright (C) 2011-2012  Intel Corporation
 *  Copyright (C) 2004-2010  Marcel Holtmann <marcel@holtmann.org>
 *
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 *
 */

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#include <stdio.h>
#include <errno.h>
#include <fcntl.h>
#include <unistd.h>
#include <stdint.h>
#include <string.h>
#include <sys/stat.h>
#include <arpa/inet.h>

#include "packet.h"
#include "btsnoop.h"

static inline uint64_t ntoh64(uint64_t n)
{
	uint64_t h;
	uint64_t tmp = ntohl(n & 0x00000000ffffffff);

	h = ntohl(n >> 32);
	h |= tmp << 32;

	return h;
}

#define hton64(x)     ntoh64(x)

struct btsnoop_hdr {
	uint8_t		id[8];		/* Identification Pattern */
	uint32_t	version;	/* Version Number = 1 */
	uint32_t	type;		/* Datalink Type */
} __attribute__ ((packed));
#define BTSNOOP_HDR_SIZE (sizeof(struct btsnoop_hdr))

struct btsnoop_pkt {
	uint32_t	size;		/* Original Length */
	uint32_t	len;		/* Included Length */
	uint32_t	flags;		/* Packet Flags */
	uint32_t	drops;		/* Cumulative Drops */
	uint64_t	ts;		/* Timestamp microseconds */
	uint8_t		data[0];	/* Packet Data */
} __attribute__ ((packed));
#define BTSNOOP_PKT_SIZE (sizeof(struct btsnoop_pkt))

static const uint8_t btsnoop_id[] = { 0x62, 0x74, 0x73, 0x6e,
				      0x6f, 0x6f, 0x70, 0x00 };

static const uint32_t btsnoop_version = 1;
static uint32_t btsnoop_type = 0;

static int btsnoop_fd = -1;
static uint16_t btsnoop_index = 0xffff;

void btsnoop_create(const char *path)
{
	struct btsnoop_hdr hdr;
	ssize_t written;

	if (btsnoop_fd >= 0)
		return;

	btsnoop_fd = open(path, O_WRONLY | O_CREAT | O_TRUNC | O_CLOEXEC,
				S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH);
	if (btsnoop_fd < 0)
		return;

	btsnoop_type = 2001;

	memcpy(hdr.id, btsnoop_id, sizeof(btsnoop_id));
	hdr.version = htonl(btsnoop_version);
	hdr.type = htonl(btsnoop_type);

	written = write(btsnoop_fd, &hdr, BTSNOOP_HDR_SIZE);
	if (written < 0) {
		close(btsnoop_fd);
		btsnoop_fd = -1;
		return;
	}
}

void btsnoop_write(struct timeval *tv, uint16_t index, uint16_t opcode,
					const void *data, uint16_t size)
{
	struct btsnoop_pkt pkt;
	uint32_t flags;
	uint64_t ts;
	ssize_t written;

	if (!tv)
		return;

	if (btsnoop_fd < 0)
		return;

	switch (btsnoop_type) {
	case 1001:
		if (btsnoop_index == 0xffff)
			btsnoop_index = index;

		if (index != btsnoop_index)
			return;

		flags = packet_get_flags(opcode);
		if (flags == 0xff)
			return;
		break;

	case 2001:
		flags = (index << 16) | opcode;
		break;

	default:
		return;
	}

	ts = (tv->tv_sec - 946684800ll) * 1000000ll + tv->tv_usec;

	pkt.size  = htonl(size);
	pkt.len   = htonl(size);
	pkt.flags = htonl(flags);
	pkt.drops = htonl(0);
	pkt.ts    = hton64(ts + 0x00E03AB44A676000ll);

	written = write(btsnoop_fd, &pkt, BTSNOOP_PKT_SIZE);
	if (written < 0)
		return;

	if (data && size > 0) {
		written = write(btsnoop_fd, data, size);
		if (written < 0)
			return;
	}
}

int btsnoop_open(const char *path)
{
	struct btsnoop_hdr hdr;
	ssize_t len;

	if (btsnoop_fd >= 0) {
		fprintf(stderr, "Too many open files\n");
		return -1;
	}

	btsnoop_fd = open(path, O_RDONLY | O_CLOEXEC);
	if (btsnoop_fd < 0) {
		perror("Failed to open file");
		return -1;
	}

	len = read(btsnoop_fd, &hdr, BTSNOOP_HDR_SIZE);
	if (len < 0 || len != BTSNOOP_HDR_SIZE) {
		perror("Failed to read header");
		close(btsnoop_fd);
		btsnoop_fd = -1;
		return -1;
	}

	if (memcmp(hdr.id, btsnoop_id, sizeof(btsnoop_id))) {
		fprintf(stderr, "Invalid btsnoop header\n");
		close(btsnoop_fd);
		btsnoop_fd = -1;
		return -1;
	}

	if (ntohl(hdr.version) != btsnoop_version) {
		fprintf(stderr, "Invalid btsnoop version\n");
		close(btsnoop_fd);
		btsnoop_fd = -1;
		return -1;
	}

	btsnoop_type = ntohl(hdr.type);

	switch (btsnoop_type) {
	case 1001:
	case 1002:
		packet_del_filter(PACKET_FILTER_SHOW_INDEX);
		break;

	case 2001:
		packet_add_filter(PACKET_FILTER_SHOW_INDEX);
		break;
	}

	return 0;
}

int btsnoop_read(struct timeval *tv, uint16_t *index, uint16_t *opcode,
						void *data, uint16_t *size)
{
	struct btsnoop_pkt pkt;
	uint32_t toread, flags;
	uint64_t ts;
	uint8_t pkt_type;
	ssize_t len;

	if (btsnoop_fd < 0)
		return -1;

	len = read(btsnoop_fd, &pkt, BTSNOOP_PKT_SIZE);
	if (len == 0)
		return -1;

	if (len < 0 || len != BTSNOOP_PKT_SIZE) {
		perror("Failed to read packet");
		close(btsnoop_fd);
		btsnoop_fd = -1;
		return -1;
	}

	toread = ntohl(pkt.size);
	flags = ntohl(pkt.flags);

	ts = ntoh64(pkt.ts) - 0x00E03AB44A676000ll;
	tv->tv_sec = (ts / 1000000ll) + 946684800ll;
	tv->tv_usec = ts % 1000000ll;

	switch (btsnoop_type) {
	case 1001:
		*index = 0;
		*opcode = packet_get_opcode(0xff, flags);
		break;

	case 1002:
		len = read(btsnoop_fd, &pkt_type, 1);
		if (len < 0) {
			perror("Failed to read packet type");
			close(btsnoop_fd);
			btsnoop_fd = -1;
			return -1;
		}
		toread--;

		*index = 0;
		*opcode = packet_get_opcode(pkt_type, flags);
		break;

	case 2001:
		*index = flags >> 16;
		*opcode = flags & 0xffff;
		break;

	default:
		fprintf(stderr, "Unknown packet type\n");
		close(btsnoop_fd);
		btsnoop_fd = -1;
		return -1;
	}

	len = read(btsnoop_fd, data, toread);
	if (len < 0) {
		perror("Failed to read data");
		close(btsnoop_fd);
		btsnoop_fd = -1;
		return -1;
	}

	*size = toread;

	return 0;
}

void btsnoop_close(void)
{
	if (btsnoop_fd < 0)
		return;

	close(btsnoop_fd);
	btsnoop_fd = -1;

	btsnoop_index = 0xffff;
}