monitor: Use BPF to filter packets by index

This uses a BPF filter to filter packets to specific index.

Change-Id: Ie73c025483c18a40de803e79a24e3a346d5156ce
Signed-off-by: himanshu <h.himanshu@samsung.com>

diff --git a/monitor/control.c b/monitor/control.c
index ebdd336..4bbaa62 100755 (executable)
--- 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 +1031,37 @@ static int open_socket(uint16_t channel)
        return fd;
 }
 
+static void attach_index_filter(int fd, uint16_t index)
+{
+       struct sock_filter filters[] = {
+               /* Load MGMT index:
+                * A <- MGMT index
+                */
+               BPF_STMT(BPF_LD + BPF_B + BPF_ABS,
+                                       offsetof(struct mgmt_hdr, index)),
+               /* Accept if index is HCI_DEV_NONE:
+                * 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 */
+               /* Accept if index match:
+                * 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));
+}
+
 static int open_channel(uint16_t channel)
 {
        struct control_data *data;
@@ -1045,6 +1079,9 @@ static int open_channel(uint16_t channel)
                return -1;
        }
 
+       if (filter_index != HCI_DEV_NONE)
+               attach_index_filter(data->fd, filter_index);
+
        mainloop_add_fd(data->fd, EPOLLIN, data_callback, data, free_data);
 
        return 0;
@@ -1480,3 +1517,8 @@ void control_disable_decoding(void)
 {
        decode_control = false;
 }
+
+void control_filter_index(uint16_t index)
+{
+       filter_index = index;
+}

diff --git a/monitor/control.h b/monitor/control.h
index a265b8e..8e22138 100755 (executable)
--- a/monitor/control.h
+++ b/monitor/control.h
@@ -34,5 +34,6 @@ void control_server(const char *path);
 int control_tty(const char *path, unsigned int speed);
 int control_tracing(void);
 void control_disable_decoding(void);
+void control_filter_index(uint16_t index);
 
 void control_message(uint16_t opcode, const void *data, uint16_t size);

diff --git a/monitor/packet.c b/monitor/packet.c
index 00e78cb..fff04b4 100755 (executable)
--- a/monitor/packet.c
+++ b/monitor/packet.c
@@ -107,7 +107,6 @@ static time_t time_offset = ((time_t) -1);
 static int priority_level = BTSNOOP_PRIORITY_INFO;
 static unsigned long filter_mask = 0;
 static bool index_filter = false;
-static uint16_t index_number = 0;
 static uint16_t index_current = 0;
 static uint16_t fallback_manufacturer = UNKNOWN_MANUFACTURER;
 
@@ -261,8 +260,9 @@ void packet_select_index(uint16_t index)
 {
        filter_mask &= ~PACKET_FILTER_SHOW_INDEX;
 
+       control_filter_index(index);
+
        index_filter = true;
-       index_number = index;
 }
 
 #define print_space(x) printf("%*c", (x), ' ');
@@ -3982,9 +3982,6 @@ void packet_control(struct timeval *tv, struct ucred *cred,
                                        uint16_t index, uint16_t opcode,
                                        const void *data, uint16_t size)
 {
-       if (index_filter && index_number != index)
-               return;
-
        control_message(opcode, data, size);
 }
 
@@ -4006,8 +4003,6 @@ void packet_monitor(struct timeval *tv, struct ucred *cred,
        const char *ident;
 
        if (index != HCI_DEV_NONE) {
-               if (index_filter && index_number != index)
-                       return;
                index_current = index;
        }