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The filter is rebuilt each time an event is registered or unregistered, and only applies to non-stream (raw socket) connections. Assisted-by: Claude:claude-opus-4.6 --- src/shared/hci.c | 84 ++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 84 insertions(+) diff --git a/src/shared/hci.c b/src/shared/hci.c index 0faa6dea555d..5105b0b2f320 100644 --- a/src/shared/hci.c +++ b/src/shared/hci.c @@ -23,6 +23,7 @@ #include #include #include +#include #include "bluetooth/hci.h" #include "monitor/bt.h" @@ -565,6 +566,85 @@ bool bt_hci_flush(struct bt_hci *hci) return true; } +static void update_evt_filter(struct bt_hci *hci) +{ + const struct queue_entry *entry; + struct sock_filter *filters; + struct sock_fprog fprog; + unsigned int count, i; + int fd; + + fd = io_get_fd(hci->io); + if (fd < 0) + return; + + /* If stream-based (not a raw socket), no BPF filtering needed */ + if (hci->is_stream) + return; + + count = queue_length(hci->evt_list); + + /* Build filter: load event code, check defaults + registered events. + * Packet layout for HCI_CHANNEL_RAW: [H4 type (1 byte)][evt code (1)] + * So event code is at offset 1. + * + * Filter structure: + * [0] Load byte at offset 1 (event code) + * [1] JEQ BT_HCI_EVT_CMD_COMPLETE -> accept + * [2] JEQ BT_HCI_EVT_CMD_STATUS -> accept + * [3..3+count-1] JEQ registered_event -> accept + * [3+count] reject + * [4+count] accept + */ + filters = malloc(sizeof(*filters) * (count + 5)); + if (!filters) + return; + + i = 0; + + /* Load event code byte */ + filters[i++] = (struct sock_filter) + BPF_STMT(BPF_LD + BPF_B + BPF_ABS, 1); + + /* Check BT_HCI_EVT_CMD_COMPLETE (0x0e) */ + filters[i++] = (struct sock_filter) + BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, BT_HCI_EVT_CMD_COMPLETE, + count + 2, 0); + + /* Check BT_HCI_EVT_CMD_STATUS (0x0f) */ + filters[i++] = (struct sock_filter) + BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, BT_HCI_EVT_CMD_STATUS, + count + 1, 0); + + /* Check each registered event */ + entry = queue_get_entries(hci->evt_list); + while (entry) { + const struct evt *evt = entry->data; + unsigned int jump = count - (i - 3); + + filters[i] = (struct sock_filter) + BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, evt->event, + jump, 0); + i++; + entry = entry->next; + } + + /* Reject */ + filters[i++] = (struct sock_filter) + BPF_STMT(BPF_RET | BPF_K, 0); + + /* Accept */ + filters[i++] = (struct sock_filter) + BPF_STMT(BPF_RET | BPF_K, 0x0fffffff); + + fprog.len = i; + fprog.filter = filters; + + setsockopt(fd, SOL_SOCKET, SO_ATTACH_FILTER, &fprog, sizeof(fprog)); + + free(filters); +} + unsigned int bt_hci_register(struct bt_hci *hci, uint8_t event, bt_hci_callback_func_t callback, void *user_data, bt_hci_destroy_func_t destroy) @@ -591,6 +671,8 @@ unsigned int bt_hci_register(struct bt_hci *hci, uint8_t event, return 0; } + update_evt_filter(hci); + return evt->id; } @@ -657,6 +739,8 @@ bool bt_hci_unregister(struct bt_hci *hci, unsigned int id) evt_free(evt); + update_evt_filter(hci); + return true; } -- 2.53.0