Hi Marcel,
On Thu, Jun 21, 2018 at 3:49 PM, Marcel Holtmann <marcel@xxxxxxxxxxxx> wrote:
> Hi Luiz,
>
>>> This uses a BPF filter to filter packets to specific index.
>>> ---
>>> monitor/control.c | 36 ++++++++++++++++++++++++++++++++++++
>>> monitor/control.h | 1 +
>>> monitor/packet.c | 9 ++-------
>>> 3 files changed, 39 insertions(+), 7 deletions(-)
>>>
>>> diff --git a/monitor/control.c b/monitor/control.c
>>> index 9bbdc37dc..05cfc3aaa 100644
>>> --- a/monitor/control.c
>>> +++ b/monitor/control.c
>>> @@ -28,6 +28,7 @@
>>>
>>> #include <stdio.h>
>>> #include <stdbool.h>
>>> +#include <stddef.h>
>>> #include <errno.h>
>>> #include <unistd.h>
>>> #include <stdlib.h>
>>> @@ -39,6 +40,7 @@
>>> #include <sys/stat.h>
>>> #include <termios.h>
>>> #include <fcntl.h>
>>> +#include <linux/filter.h>
>>>
>>> #include "lib/bluetooth.h"
>>> #include "lib/hci.h"
>>> @@ -58,6 +60,7 @@
>>> static struct btsnoop *btsnoop_file = NULL;
>>> static bool hcidump_fallback = false;
>>> static bool decode_control = true;
>>> +static uint16_t filter_index = HCI_DEV_NONE;
>>>
>>> struct control_data {
>>> uint16_t channel;
>>> @@ -1028,6 +1031,31 @@ static int open_socket(uint16_t channel)
>>> return fd;
>>> }
>>>
>>> +static void attach_index_filter(int fd, uint16_t index)
>>> +{
>>> + struct sock_filter filters[] = {
>>> + /* A <- MGMT index */
>>> + BPF_STMT(BPF_LD + BPF_B + BPF_ABS,
>>> + offsetof(struct mgmt_hdr, index)),
>>> + /* A == HCI_DEV_NONE */
>>> + BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, HCI_DEV_NONE, 0, 1),
>>> + /* return */
>>> + BPF_STMT(BPF_RET|BPF_K, 0x0fffffff), /* pass */
>>> + /* A == index */
>>> + BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, index, 0, 1),
>>> + /* returns */
>>> + BPF_STMT(BPF_RET|BPF_K, 0x0fffffff), /* pass */
>>> + BPF_STMT(BPF_RET|BPF_K, 0), /* reject */
>>> + };
>>> + struct sock_fprog fprog = {
>>> + .len = sizeof(filters) / sizeof(filters[0]),
>>> + /* casting const away: */
>>> + .filter = filters,
>>> + };
>>> +
>>> + setsockopt(fd, SOL_SOCKET, SO_ATTACH_FILTER, &fprog, sizeof(fprog));
>>> +}
>>> +
>
> I would prefer a bit more comments on what the program is doing. So allow packets from HCI_DEV_NONE, filter for index etc.
Sure I will update with what each instruction is doing.
> Regards
>
> Marcel
>
--
Luiz Augusto von Dentz
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