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List: linux-bluetooth
Subject: Re: Receiving data in BLE non-connectable undirected advertisements
From: Benjamin Adler <benadler () gmx ! net>
Date: 2014-03-04 22:02:03
Message-ID: 53164D5B.3030903 () gmx ! net
[Download RAW message or body]
Marcel,
On 03.03.2014 15:28, Marcel Holtmann wrote:
> maybe you need to just read the HCI part of the Bluetooth Core specification. The \
> tools/ibeacon.c is a perfect example on how to get started with HCI commands. You \
> just need to figure out on how to do scanning instead of advertising.
during the last days, I fought through those 2600 pages, and I think I
now have a rough idea how things might work. The source of my
lescanner.c is attached, and it doesn't work yet. My questions are:
- why do you open urandom, but never use it?
- searching for the reason of "Failed to open HCI user channel", I found
a commit log from you, saying that the HCI user channel means exclusive
access to the device, so I'll have to disable e.g. bluetoothd. Is that a
limitation inherent to bluetooth, or just to bluez? Is there a way to
process those advertisements and still use bluetoothd, e.g. for skype?
- in bt_hci_register(), what is the "bt_hci_destroy_func_t destroy"
parameter used for? It seems it's always null when used in the examples?
- I was hoping that line 134 would cause advertising_report_callback()
to be called when advertisements are received. Unfortunately, that's not
the case, nothing happens. What am I missing?
- I'm also confused by how those btle advertisements are handled, they
seem to be a subevent/subtype of a generic btle event. How can I process
this correctly in advertising_report_callback()?
I'd be grateful if you could give me some hints to some of these questions.
Cheers,
ben
output from lescanner:
# ./tools/lescanner
Low Energy Passive Non-Connectable Undirected Advertisement Scanner 5.15
Registering for command-complete-events...
Registering for advertising-events...
Lets see whether we can provoke an error...
Setting bt event-mask...
Setting bt le event-mask...
Setting bt le scan parameters...
Enabling le scan...
check_error_callback: succeeded
check_error_callback: succeeded
check_error_callback: succeeded
check_error_callback: succeeded
["lescanner.c" (text/x-csrc)]
/*
*
* 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 <ctype.h>
#include <stdio.h>
#include <fcntl.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include <getopt.h>
#include <sys/ioctl.h>
#include <sys/socket.h>
#include "monitor/mainloop.h"
#include "monitor/bt.h"
#include "src/shared/util.h"
#include "src/shared/hci.h"
static int urandom_fd;
static struct bt_hci *hci_dev;
static void shutdown_timeout(int id, void *user_data)
{
fprintf(stdout, "shutdown_timeout()\n");
mainloop_remove_timeout(id);
mainloop_quit();
}
static void shutdown_complete(const void *data, uint8_t size, void *user_data)
{
fprintf(stdout, "shutdown_complete()\n");
unsigned int id = PTR_TO_UINT(user_data);
shutdown_timeout(id, NULL);
}
static void shutdown_device(void)
{
fprintf(stdout, "shutdown_device()\n");
uint8_t enable = 0x00;
unsigned int id;
bt_hci_flush(hci_dev);
id = mainloop_add_timeout(5, shutdown_timeout, NULL, NULL);
bt_hci_send(hci_dev, BT_HCI_CMD_LE_SET_ADV_ENABLE, &enable, 1, NULL, NULL, NULL);
bt_hci_send(hci_dev, BT_HCI_CMD_RESET, NULL, 0, shutdown_complete, UINT_TO_PTR(id), \
NULL); }
static void check_error_callback(const void *data, uint8_t size, void *user_data)
{
uint8_t status = *((uint8_t *) data);
if (status) {
fprintf(stderr, "check_error_callback: error occurred, status is %d\n", status);
shutdown_device();
return;
} else {
fprintf(stdout, "check_error_callback: succeeded\n");
}
}
static void advertising_report_callback(const void *data, uint8_t size, void \
*user_data) {
const struct bt_hci_evt_le_adv_report *report_adv = data;
fprintf(stdout, "Received %d reports, event-type %d.\n", report_adv->num_reports, \
report_adv->event_type); }
static void command_complete_callback(const void *data, uint8_t size, void \
*user_data) {
const struct bt_hci_evt_cmd_complete *report_cmd_complete = data;
fprintf(stdout, "command_complete, ncmd %d, opcode %d.\n", \
report_cmd_complete->ncmd, report_cmd_complete->opcode); }
static void local_features_callback(const void *data, uint8_t size, void *user_data)
{
const struct bt_hci_rsp_read_local_features *rsp = data;
if (rsp->status) {
fprintf(stderr, "Failed to read local features\n");
shutdown_device();
return;
}
if (!(rsp->features[4] & 0x40)) {
fprintf(stderr, "Controller without Low Energy support\n");
shutdown_device();
return;
}
//bt_hci_send(hci_dev, BT_HCI_CMD_LE_READ_ADV_TX_POWER, NULL, 0, \
adv_tx_power_callback, NULL, NULL);
// Register for command_complete events
fprintf(stdout, "Registering for command-complete-events...\n");
bt_hci_register(hci_dev,
BT_HCI_EVT_CMD_COMPLETE,
command_complete_callback, //bt_hci_callback_func_t callback,
NULL, //void *user_data,
NULL //bt_hci_destroy_func_t destroy TODO: ask what this does?
);
// Register for advertising events
fprintf(stdout, "Registering for advertising-events...\n");
bt_hci_register(hci_dev,
BT_HCI_EVT_LE_META_EVENT, // 0x3e is LE META Event, subevent code is 0x02 \
BT_HCI_EVT_LE_ADV_REPORT ?? advertising_report_callback, //bt_hci_callback_func_t \
callback, NULL, //void *user_data,
NULL //bt_hci_destroy_func_t destroy TODO: ask what this does?
);
fprintf(stdout, "Lets see whether we can provoke an error...\n");
bt_hci_register(hci_dev,
0xff, // 0xff seems to be undefined
advertising_report_callback, //bt_hci_callback_func_t callback,
NULL, //void *user_data,
NULL //bt_hci_destroy_func_t destroy TODO: ask what this does?
);
// #define BT_HCI_CMD_SET_EVENT_MASK 0x0c01
// struct bt_hci_cmd_set_event_mask {
// uint8_t mask[8];
// } __attribute__ ((packed));
struct bt_hci_cmd_set_event_mask event_mask;
memset(&event_mask, 0, sizeof(event_mask));
event_mask.mask[0] = 0x20; // receive LE meta events
// There is no BT_HCI_RSP_SET_EVENT_MASK, so we only check for errors in the \
callback fprintf(stdout, "Setting bt event-mask...\n");
bt_hci_send(hci_dev, BT_HCI_CMD_SET_EVENT_MASK, &event_mask, sizeof(event_mask), \
check_error_callback, NULL, NULL);
// #define BT_HCI_CMD_LE_SET_EVENT_MASK 0x2001
// struct bt_hci_cmd_le_set_event_mask {
// uint8_t mask[8];
// } __attribute__ ((packed));
struct bt_hci_cmd_le_set_event_mask event_mask_le;
memset(&event_mask_le, 0, sizeof(event_mask_le));
event_mask_le.mask[7] = 0x2; // receive only le_advertising_reports
// There is no BT_HCI_RSP_LE_SET_EVENT_MASK, so we only check for errors in the \
callback fprintf(stdout, "Setting bt le event-mask...\n");
bt_hci_send(hci_dev, BT_HCI_CMD_LE_SET_EVENT_MASK, &event_mask_le, \
sizeof(event_mask_le), check_error_callback, NULL, NULL);
// #define BT_HCI_CMD_LE_SET_SCAN_PARAMETERS 0x200b
// struct bt_hci_cmd_le_set_scan_parameters {
// uint8_t type;
// uint16_t interval;
// uint16_t window;
// uint8_t own_addr_type;
// uint8_t filter_policy;
// } __attribute__ ((packed));
struct bt_hci_cmd_le_set_scan_parameters scan_parameters;
memset(&scan_parameters, 0, sizeof(scan_parameters));
scan_parameters.type = 0; // bt-core-spec 4.1, pdf-page 1255: passive scanning
scan_parameters.interval = 0x0100; // Interval of minimum 0x10 is 16 * 0.625msec => \
10 msec. Interval of maximum 0x4000 is 16384 * 0.625msec => 10240msec \
scan_parameters.window = 0x0100; // window, must be less than or equal to interval \
scan_parameters.own_addr_type = 0x0; // // bt-core-spec 4.1, pdf-page 1256: public \
address scan_parameters.filter_policy = 0x0; // // bt-core-spec 4.1, pdf-page 1256: \
accept all advertisements, not just from whitelist // There is no \
BT_HCI_RSP_LE_SET_SCAN_PARAMETERS, so we only check for errors in the callback \
fprintf(stdout, "Setting bt le scan parameters...\n"); bt_hci_send(hci_dev, \
BT_HCI_CMD_LE_SET_SCAN_PARAMETERS, &scan_parameters, sizeof(scan_parameters), \
check_error_callback, NULL, NULL);
/* This is non-le scanning, so we try without first
// #define BT_HCI_CMD_WRITE_SCAN_ENABLE 0x0c1a
// struct bt_hci_cmd_write_scan_enable {
// uint8_t enable;
// } __attribute__ ((packed));
struct bt_hci_cmd_write_scan_enable scan_enable;
memset(&scan_enable, 0, sizeof(bt_hci_cmd_write_scan_enable));
scan_enable.enable = 1; // enable!
// There is no BT_HCI_RSP_WRITE_SCAN_ENABLE, so we only check for errors in the \
callback bt_hci_send(hci_dev, BT_HCI_CMD_WRITE_SCAN_ENABLE, &scan_enable, \
sizeof(bt_hci_cmd_write_scan_enable), check_error_callback, NULL, \
NULL);
*/
// #define BT_HCI_CMD_LE_SET_SCAN_ENABLE 0x200c
// struct bt_hci_cmd_le_set_scan_enable {
// uint8_t enable;
// uint8_t filter_dup;
// } __attribute__ ((packed));
struct bt_hci_cmd_le_set_scan_enable scan_enable_le;
memset(&scan_enable_le, 0, sizeof(scan_enable_le));
scan_enable_le.enable = 1; // enable!
scan_enable_le.filter_dup = 0; // do not filter out duplicates
// There is no BT_HCI_RSP_LE_SET_SCAN_ENABLE, so we only check for errors in the \
callback fprintf(stdout, "Enabling le scan...\n");
bt_hci_send(hci_dev, BT_HCI_CMD_LE_SET_SCAN_ENABLE, &scan_enable_le, \
sizeof(scan_enable_le), check_error_callback, NULL, NULL); }
static void start_scanning(void)
{
bt_hci_send(hci_dev, BT_HCI_CMD_RESET, NULL, 0, NULL, NULL, NULL);
#warning: bt-core-spec says not to issue commands while reset-in-progress?
bt_hci_send(hci_dev, BT_HCI_CMD_READ_LOCAL_FEATURES, NULL, 0, \
local_features_callback, NULL, NULL); }
static void signal_callback(int signum, void *user_data)
{
static bool terminated = false;
switch (signum) {
case SIGINT:
case SIGTERM:
if (!terminated) {
shutdown_device();
terminated = true;
}
break;
}
}
static void usage(void)
{
printf("lescanner - Low Energy Passive Non-Connectable Undirected Advertisement \
Scanner\n" "Usage:\n");
printf("\tlescanner [options]\n");
printf("Options:\n"
"\t-i, --index <num> Use specified controller\n"
"\t-h, --help Show help options\n");
}
static const struct option main_options[] = {
{ "index", required_argument, NULL, 'i' },
{ "version", no_argument, NULL, 'v' },
{ "help", no_argument, NULL, 'h' },
{ }
};
int main(int argc, char *argv[])
{
uint16_t index = 0;
const char *str;
sigset_t mask;
int exit_status;
for (;;) {
int opt;
opt = getopt_long(argc, argv, "i:vh", main_options, NULL);
if (opt < 0)
break;
switch (opt) {
case 'i':
if (strlen(optarg) > 3 && !strncmp(optarg, "hci", 3))
str = optarg + 3;
else
str = optarg;
if (!isdigit(*str)) {
usage();
return EXIT_FAILURE;
}
index = atoi(str);
break;
case 'v':
printf("%s\n", VERSION);
return EXIT_SUCCESS;
case 'h':
usage();
return EXIT_SUCCESS;
default:
return EXIT_FAILURE;
}
}
if (argc - optind > 0) {
fprintf(stderr, "Invalid command line parameters\n");
return EXIT_FAILURE;
}
urandom_fd = open("/dev/urandom", O_RDONLY);
if (urandom_fd < 0) {
fprintf(stderr, "Failed to open /dev/urandom device\n");
return EXIT_FAILURE;
}
mainloop_init();
sigemptyset(&mask);
sigaddset(&mask, SIGINT);
sigaddset(&mask, SIGTERM);
mainloop_set_signal(&mask, signal_callback, NULL, NULL);
printf("Low Energy Passive Non-Connectable Undirected Advertisement Scanner %s\n", \
VERSION);
hci_dev = bt_hci_new_user_channel(index);
if (!hci_dev) {
fprintf(stderr, "Failed to open HCI user channel\n");
exit_status = EXIT_FAILURE;
goto done;
}
start_scanning();
exit_status = mainloop_run();
bt_hci_unref(hci_dev);
done:
close(urandom_fd);
return exit_status;
}
--
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