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.TH "hci" "7" "October 2024" "BlueZ" "Linux System Administration"
.SH Name
hci \- Bluetooth HCI protocol
.SH SYNOPSIS
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.INDENT 3.5
.sp
.EX
#include <sys/socket.h>
#include <bluetooth/bluetooth.h>
#include <bluetooth/hci.h>

hci_socket = socket(PF_BLUETOOTH, SOCK_RAW, BTPROTO_HCI);
.EE
.UNINDENT
.UNINDENT
.SH DESCRIPTION
.sp
Bluetooth Host Controller Interface (HCI) is the standard protocol to
communicate with Bluetooth adapters. HCI protocol provides a uniform command
method for the Host to access Controller capabilities and to control connections
to other Controllers.
.SH SOCKET ADDRESS
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.INDENT 3.5
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.EX
struct sockaddr_hci {
    sa_family_t    hci_family;
    unsigned short hci_dev;
    unsigned short hci_channel;
};
.EE
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.UNINDENT
.sp
Possible values for hci_channel:
.TS
box center;
l|l|l.
T{
Define
T}	T{
Value
T}	T{
Description
T}
_
T{
\fBHCI_CHANNEL_RAW\fP
T}	T{
0x00
T}	T{
Raw channel \- Used for raw HCI communication
T}
_
T{
\fBHCI_CHANNEL_USER\fP
T}	T{
0x01
T}	T{
User channel \- Used for userspace HCI communication (disables kernel processing)
T}
_
T{
\fBHCI_CHANNEL_MONITOR\fP
T}	T{
0x02
T}	T{
Monitor channel \- Used for monitoring HCI traffic (btmon(1))
T}
_
T{
\fBHCI_CHANNEL_CONTROL\fP
T}	T{
0x03
T}	T{
Control channel \- Used to manage local adapters (bluetoothd(7))
T}
_
T{
\fBHCI_CHANNEL_LOGGING\fP
T}	T{
0x04
T}	T{
Logging channel \- Used to inject logging messages (bluetoothd(7))
T}
.TE
.sp
Example:
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.EX
struct sockaddr_hci addr;

memset(&addr, 0, sizeof(addr));
addr.hci_family = AF_BLUETOOTH;
addr.hci_dev = HCI_DEV_NONE;
addr.hci_channel = HCI_CHANNEL_CONTROL;
.EE
.UNINDENT
.UNINDENT
.SH SOCKET OPTIONS
.sp
The socket options listed below can be set by using \fBsetsockopt(2)\fP and read
with \fBgetsockopt(2)\fP with the socket level set to SOL_BLUETOOTH or SOL_HCI
(HCI_FILTER).
.SS HCI_FILTER (since Linux 2.6)
.sp
Filter by HCI events, requires hci_channel to be set to HCI_CHANNEL_RAW,
possible values:
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.EX
struct hci_filter {
    uint32_t type_mask;
    uint32_t event_mask[2];
    uint16_t opcode;
};
.EE
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Example:
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.EX
struct hci_filter flt;

memset(&flt, 0, sizeof(flt));
flt.type_mask = 1 << BT_H4_EVT_PKT;
flt.event_mask[0] = 0xffffffff;
flt.event_mask[1] = 0xffffffff;

setsockopt(fd, SOL_HCI, HCI_FILTER, &flt, sizeof(flt));
.EE
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.SS BT_SNDBUF (since Linux 5.16)
.sp
Set send buffer size, requires hci_channel to be set to HCI_CHANNEL_MONITOR,
HCI_CHANNEL_CONTROL or HCI_CHANNEL_LOGGING.
.sp
Default value is 1028.
.sp
Example:
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.EX
uint16_t mtu = UINT16_MAX;
int err;

err = setsockopt(fd, SOL_BLUETOOTH, BT_SNDMTU, &mtu, sizeof(mtu));
.EE
.UNINDENT
.UNINDENT
.SS BT_RCVBUF (since Linux 5.16)
.sp
Set receive buffer size, requires hci_channel to be set to HCI_CHANNEL_MONITOR,
HCI_CHANNEL_CONTROL or HCI_CHANNEL_LOGGING.
.sp
Default value is 1028.
.sp
Example:
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.sp
.EX
uint16_t mtu;
socklen_t len;
int err;

len = sizeof(mtu);
err = getsockopt(sock, SOL_BLUETOOTH, BT_RCVMTU, mtu, &len);
.EE
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.SH RESOURCES
.sp
\%<http://\:www\:.bluez\:.org>
.SH REPORTING BUGS
.sp
\%<linux-bluetooth@\:vger\:.kernel\:.org>
.SH SEE ALSO
.sp
socket(7)
.SH Copyright
Free use of this software is granted under the terms of the GNU
Lesser General Public Licenses (LGPL).
.\" End of generated man page.