// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (C) 2020 Google Corporation
 */

#include <net/bluetooth/bluetooth.h>
#include <net/bluetooth/hci_core.h>
#include <net/bluetooth/mgmt.h>

#include "hci_request.h"
#include "mgmt_util.h"
#include "msft.h"

#define MSFT_RSSI_THRESHOLD_VALUE_MIN           -127
#define MSFT_RSSI_THRESHOLD_VALUE_MAX           20
#define MSFT_RSSI_LOW_TIMEOUT_MAX               0x3C

#define MSFT_OP_READ_SUPPORTED_FEATURES         0x00
struct msft_cp_read_supported_features {
        __u8   sub_opcode;
} __packed;

struct msft_rp_read_supported_features {
        __u8   status;
        __u8   sub_opcode;
        __le64 features;
        __u8   evt_prefix_len;
        __u8   evt_prefix[];
} __packed;

#define MSFT_OP_LE_MONITOR_ADVERTISEMENT        0x03
#define MSFT_MONITOR_ADVERTISEMENT_TYPE_PATTERN 0x01
struct msft_le_monitor_advertisement_pattern {
        __u8 length;
        __u8 data_type;
        __u8 start_byte;
        __u8 pattern[0];
};

struct msft_le_monitor_advertisement_pattern_data {
        __u8 count;
        __u8 data[0];
};

struct msft_cp_le_monitor_advertisement {
        __u8 sub_opcode;
        __s8 rssi_high;
        __s8 rssi_low;
        __u8 rssi_low_interval;
        __u8 rssi_sampling_period;
        __u8 cond_type;
        __u8 data[0];
} __packed;

struct msft_rp_le_monitor_advertisement {
        __u8 status;
        __u8 sub_opcode;
        __u8 handle;
} __packed;

#define MSFT_OP_LE_CANCEL_MONITOR_ADVERTISEMENT 0x04
struct msft_cp_le_cancel_monitor_advertisement {
        __u8 sub_opcode;
        __u8 handle;
} __packed;

struct msft_rp_le_cancel_monitor_advertisement {
        __u8 status;
        __u8 sub_opcode;
} __packed;

#define MSFT_OP_LE_SET_ADVERTISEMENT_FILTER_ENABLE      0x05
struct msft_cp_le_set_advertisement_filter_enable {
        __u8 sub_opcode;
        __u8 enable;
} __packed;

struct msft_rp_le_set_advertisement_filter_enable {
        __u8 status;
        __u8 sub_opcode;
} __packed;

struct msft_monitor_advertisement_handle_data {
        __u8  msft_handle;
        __u16 mgmt_handle;
        struct list_head list;
};

struct msft_data {
        __u64 features;
        __u8  evt_prefix_len;
        __u8  *evt_prefix;
        struct list_head handle_map;
        __u16 pending_add_handle;
        __u16 pending_remove_handle;
        __u8 reregistering;
        __u8 filter_enabled;
};

static int __msft_add_monitor_pattern(struct hci_dev *hdev,
                                      struct adv_monitor *monitor);

bool msft_monitor_supported(struct hci_dev *hdev)
{
        return !!(msft_get_features(hdev) & MSFT_FEATURE_MASK_LE_ADV_MONITOR);
}

static bool read_supported_features(struct hci_dev *hdev,
                                    struct msft_data *msft)
{
        struct msft_cp_read_supported_features cp;
        struct msft_rp_read_supported_features *rp;
        struct sk_buff *skb;

        cp.sub_opcode = MSFT_OP_READ_SUPPORTED_FEATURES;

        skb = __hci_cmd_sync(hdev, hdev->msft_opcode, sizeof(cp), &cp,
                             HCI_CMD_TIMEOUT);
        if (IS_ERR(skb)) {
                bt_dev_err(hdev, "Failed to read MSFT supported features (%ld)",
                           PTR_ERR(skb));
                return false;
        }

        if (skb->len < sizeof(*rp)) {
                bt_dev_err(hdev, "MSFT supported features length mismatch");
                goto failed;
        }

        rp = (struct msft_rp_read_supported_features *)skb->data;

        if (rp->sub_opcode != MSFT_OP_READ_SUPPORTED_FEATURES)
                goto failed;

        if (rp->evt_prefix_len > 0) {
                msft->evt_prefix = kmemdup(rp->evt_prefix, rp->evt_prefix_len,
                                           GFP_KERNEL);
                if (!msft->evt_prefix)
                        goto failed;
        }

        msft->evt_prefix_len = rp->evt_prefix_len;
        msft->features = __le64_to_cpu(rp->features);

        kfree_skb(skb);
        return true;

failed:
        kfree_skb(skb);
        return false;
}

/* This function requires the caller holds hdev->lock */
static void reregister_monitor_on_restart(struct hci_dev *hdev, int handle)
{
        struct adv_monitor *monitor;
        struct msft_data *msft = hdev->msft_data;
        int err;

        while (1) {
                monitor = idr_get_next(&hdev->adv_monitors_idr, &handle);
                if (!monitor) {
                        /* All monitors have been reregistered */
                        msft->reregistering = false;
                        hci_update_background_scan(hdev);
                        return;
                }

                msft->pending_add_handle = (u16)handle;
                err = __msft_add_monitor_pattern(hdev, monitor);

                /* If success, we return and wait for monitor added callback */
                if (!err)
                        return;

                /* Otherwise remove the monitor and keep registering */
                hci_free_adv_monitor(hdev, monitor);
                handle++;
        }
}

void msft_do_open(struct hci_dev *hdev)
{
        struct msft_data *msft;

        if (hdev->msft_opcode == HCI_OP_NOP)
                return;

        bt_dev_dbg(hdev, "Initialize MSFT extension");

        msft = kzalloc(sizeof(*msft), GFP_KERNEL);
        if (!msft)
                return;

        if (!read_supported_features(hdev, msft)) {
                kfree(msft);
                return;
        }

        INIT_LIST_HEAD(&msft->handle_map);
        hdev->msft_data = msft;

        if (msft_monitor_supported(hdev)) {
                msft->reregistering = true;
                msft_set_filter_enable(hdev, true);
                reregister_monitor_on_restart(hdev, 0);
        }
}

void msft_do_close(struct hci_dev *hdev)
{
        struct msft_data *msft = hdev->msft_data;
        struct msft_monitor_advertisement_handle_data *handle_data, *tmp;
        struct adv_monitor *monitor;

        if (!msft)
                return;

        bt_dev_dbg(hdev, "Cleanup of MSFT extension");

        hdev->msft_data = NULL;

        list_for_each_entry_safe(handle_data, tmp, &msft->handle_map, list) {
                monitor = idr_find(&hdev->adv_monitors_idr,
                                   handle_data->mgmt_handle);

                if (monitor && monitor->state == ADV_MONITOR_STATE_OFFLOADED)
                        monitor->state = ADV_MONITOR_STATE_REGISTERED;

                list_del(&handle_data->list);
                kfree(handle_data);
        }

        kfree(msft->evt_prefix);
        kfree(msft);
}

void msft_vendor_evt(struct hci_dev *hdev, struct sk_buff *skb)
{
        struct msft_data *msft = hdev->msft_data;
        u8 event;

        if (!msft)
                return;

        /* When the extension has defined an event prefix, check that it
         * matches, and otherwise just return.
         */
        if (msft->evt_prefix_len > 0) {
                if (skb->len < msft->evt_prefix_len)
                        return;

                if (memcmp(skb->data, msft->evt_prefix, msft->evt_prefix_len))
                        return;

                skb_pull(skb, msft->evt_prefix_len);
        }

        /* Every event starts at least with an event code and the rest of
         * the data is variable and depends on the event code.
         */
        if (skb->len < 1)
                return;

        event = *skb->data;
        skb_pull(skb, 1);

        bt_dev_dbg(hdev, "MSFT vendor event %u", event);
}

__u64 msft_get_features(struct hci_dev *hdev)
{
        struct msft_data *msft = hdev->msft_data;

        return msft ? msft->features : 0;
}

/* is_mgmt = true matches the handle exposed to userspace via mgmt.
 * is_mgmt = false matches the handle used by the msft controller.
 * This function requires the caller holds hdev->lock
 */
static struct msft_monitor_advertisement_handle_data *msft_find_handle_data
                                (struct hci_dev *hdev, u16 handle, bool is_mgmt)
{
        struct msft_monitor_advertisement_handle_data *entry;
        struct msft_data *msft = hdev->msft_data;

        list_for_each_entry(entry, &msft->handle_map, list) {
                if (is_mgmt && entry->mgmt_handle == handle)
                        return entry;
                if (!is_mgmt && entry->msft_handle == handle)
                        return entry;
        }

        return NULL;
}

static void msft_le_monitor_advertisement_cb(struct hci_dev *hdev,
                                             u8 status, u16 opcode,
                                             struct sk_buff *skb)
{
        struct msft_rp_le_monitor_advertisement *rp;
        struct adv_monitor *monitor;
        struct msft_monitor_advertisement_handle_data *handle_data;
        struct msft_data *msft = hdev->msft_data;

        hci_dev_lock(hdev);

        monitor = idr_find(&hdev->adv_monitors_idr, msft->pending_add_handle);
        if (!monitor) {
                bt_dev_err(hdev, "msft add advmon: monitor %d is not found!",
                           msft->pending_add_handle);
                status = HCI_ERROR_UNSPECIFIED;
                goto unlock;
        }

        if (status)
                goto unlock;

        rp = (struct msft_rp_le_monitor_advertisement *)skb->data;
        if (skb->len < sizeof(*rp)) {
                status = HCI_ERROR_UNSPECIFIED;
                goto unlock;
        }

        handle_data = kmalloc(sizeof(*handle_data), GFP_KERNEL);
        if (!handle_data) {
                status = HCI_ERROR_UNSPECIFIED;
                goto unlock;
        }

        handle_data->mgmt_handle = monitor->handle;
        handle_data->msft_handle = rp->handle;
        INIT_LIST_HEAD(&handle_data->list);
        list_add(&handle_data->list, &msft->handle_map);

        monitor->state = ADV_MONITOR_STATE_OFFLOADED;

unlock:
        if (status && monitor)
                hci_free_adv_monitor(hdev, monitor);

        /* If in restart/reregister sequence, keep registering. */
        if (msft->reregistering)
                reregister_monitor_on_restart(hdev,
                                              msft->pending_add_handle + 1);

        hci_dev_unlock(hdev);

        if (!msft->reregistering)
                hci_add_adv_patterns_monitor_complete(hdev, status);
}

static void msft_le_cancel_monitor_advertisement_cb(struct hci_dev *hdev,
                                                    u8 status, u16 opcode,
                                                    struct sk_buff *skb)
{
        struct msft_cp_le_cancel_monitor_advertisement *cp;
        struct msft_rp_le_cancel_monitor_advertisement *rp;
        struct adv_monitor *monitor;
        struct msft_monitor_advertisement_handle_data *handle_data;
        struct msft_data *msft = hdev->msft_data;
        int err;
        bool pending;

        if (status)
                goto done;

        rp = (struct msft_rp_le_cancel_monitor_advertisement *)skb->data;
        if (skb->len < sizeof(*rp)) {
                status = HCI_ERROR_UNSPECIFIED;
                goto done;
        }

        hci_dev_lock(hdev);

        cp = hci_sent_cmd_data(hdev, hdev->msft_opcode);
        handle_data = msft_find_handle_data(hdev, cp->handle, false);

        if (handle_data) {
                monitor = idr_find(&hdev->adv_monitors_idr,
                                   handle_data->mgmt_handle);
                if (monitor)
                        hci_free_adv_monitor(hdev, monitor);

                list_del(&handle_data->list);
                kfree(handle_data);
        }

        /* If remove all monitors is required, we need to continue the process
         * here because the earlier it was paused when waiting for the
         * response from controller.
         */
        if (msft->pending_remove_handle == 0) {
                pending = hci_remove_all_adv_monitor(hdev, &err);
                if (pending) {
                        hci_dev_unlock(hdev);
                        return;
                }

                if (err)
                        status = HCI_ERROR_UNSPECIFIED;
        }

        hci_dev_unlock(hdev);

done:
        hci_remove_adv_monitor_complete(hdev, status);
}

static void msft_le_set_advertisement_filter_enable_cb(struct hci_dev *hdev,
                                                       u8 status, u16 opcode,
                                                       struct sk_buff *skb)
{
        struct msft_cp_le_set_advertisement_filter_enable *cp;
        struct msft_rp_le_set_advertisement_filter_enable *rp;
        struct msft_data *msft = hdev->msft_data;

        rp = (struct msft_rp_le_set_advertisement_filter_enable *)skb->data;
        if (skb->len < sizeof(*rp))
                return;

        /* Error 0x0C would be returned if the filter enabled status is
         * already set to whatever we were trying to set.
         * Although the default state should be disabled, some controller set
         * the initial value to enabled. Because there is no way to know the
         * actual initial value before sending this command, here we also treat
         * error 0x0C as success.
         */
        if (status != 0x00 && status != 0x0C)
                return;

        hci_dev_lock(hdev);

        cp = hci_sent_cmd_data(hdev, hdev->msft_opcode);
        msft->filter_enabled = cp->enable;

        if (status == 0x0C)
                bt_dev_warn(hdev, "MSFT filter_enable is already %s",
                            cp->enable ? "on" : "off");

        hci_dev_unlock(hdev);
}

static bool msft_monitor_rssi_valid(struct adv_monitor *monitor)
{
        struct adv_rssi_thresholds *r = &monitor->rssi;

        if (r->high_threshold < MSFT_RSSI_THRESHOLD_VALUE_MIN ||
            r->high_threshold > MSFT_RSSI_THRESHOLD_VALUE_MAX ||
            r->low_threshold < MSFT_RSSI_THRESHOLD_VALUE_MIN ||
            r->low_threshold > MSFT_RSSI_THRESHOLD_VALUE_MAX)
                return false;

        /* High_threshold_timeout is not supported,
         * once high_threshold is reached, events are immediately reported.
         */
        if (r->high_threshold_timeout != 0)
                return false;

        if (r->low_threshold_timeout > MSFT_RSSI_LOW_TIMEOUT_MAX)
                return false;

        /* Sampling period from 0x00 to 0xFF are all allowed */
        return true;
}

static bool msft_monitor_pattern_valid(struct adv_monitor *monitor)
{
        return msft_monitor_rssi_valid(monitor);
        /* No additional check needed for pattern-based monitor */
}

/* This function requires the caller holds hdev->lock */
static int __msft_add_monitor_pattern(struct hci_dev *hdev,
                                      struct adv_monitor *monitor)
{
        struct msft_cp_le_monitor_advertisement *cp;
        struct msft_le_monitor_advertisement_pattern_data *pattern_data;
        struct msft_le_monitor_advertisement_pattern *pattern;
        struct adv_pattern *entry;
        struct hci_request req;
        struct msft_data *msft = hdev->msft_data;
        size_t total_size = sizeof(*cp) + sizeof(*pattern_data);
        ptrdiff_t offset = 0;
        u8 pattern_count = 0;
        int err = 0;

        if (!msft_monitor_pattern_valid(monitor))
                return -EINVAL;

        list_for_each_entry(entry, &monitor->patterns, list) {
                pattern_count++;
                total_size += sizeof(*pattern) + entry->length;
        }

        cp = kmalloc(total_size, GFP_KERNEL);
        if (!cp)
                return -ENOMEM;

        cp->sub_opcode = MSFT_OP_LE_MONITOR_ADVERTISEMENT;
        cp->rssi_high = monitor->rssi.high_threshold;
        cp->rssi_low = monitor->rssi.low_threshold;
        cp->rssi_low_interval = (u8)monitor->rssi.low_threshold_timeout;
        cp->rssi_sampling_period = monitor->rssi.sampling_period;

        cp->cond_type = MSFT_MONITOR_ADVERTISEMENT_TYPE_PATTERN;

        pattern_data = (void *)cp->data;
        pattern_data->count = pattern_count;

        list_for_each_entry(entry, &monitor->patterns, list) {
                pattern = (void *)(pattern_data->data + offset);
                /* the length also includes data_type and offset */
                pattern->length = entry->length + 2;
                pattern->data_type = entry->ad_type;
                pattern->start_byte = entry->offset;
                memcpy(pattern->pattern, entry->value, entry->length);
                offset += sizeof(*pattern) + entry->length;
        }

        hci_req_init(&req, hdev);
        hci_req_add(&req, hdev->msft_opcode, total_size, cp);
        err = hci_req_run_skb(&req, msft_le_monitor_advertisement_cb);
        kfree(cp);

        if (!err)
                msft->pending_add_handle = monitor->handle;

        return err;
}

/* This function requires the caller holds hdev->lock */
int msft_add_monitor_pattern(struct hci_dev *hdev, struct adv_monitor *monitor)
{
        struct msft_data *msft = hdev->msft_data;

        if (!msft)
                return -EOPNOTSUPP;

        if (msft->reregistering)
                return -EBUSY;

        return __msft_add_monitor_pattern(hdev, monitor);
}

/* This function requires the caller holds hdev->lock */
int msft_remove_monitor(struct hci_dev *hdev, struct adv_monitor *monitor,
                        u16 handle)
{
        struct msft_cp_le_cancel_monitor_advertisement cp;
        struct msft_monitor_advertisement_handle_data *handle_data;
        struct hci_request req;
        struct msft_data *msft = hdev->msft_data;
        int err = 0;

        if (!msft)
                return -EOPNOTSUPP;

        if (msft->reregistering)
                return -EBUSY;

        handle_data = msft_find_handle_data(hdev, monitor->handle, true);

        /* If no matched handle, just remove without telling controller */
        if (!handle_data)
                return -ENOENT;

        cp.sub_opcode = MSFT_OP_LE_CANCEL_MONITOR_ADVERTISEMENT;
        cp.handle = handle_data->msft_handle;

        hci_req_init(&req, hdev);
        hci_req_add(&req, hdev->msft_opcode, sizeof(cp), &cp);
        err = hci_req_run_skb(&req, msft_le_cancel_monitor_advertisement_cb);

        if (!err)
                msft->pending_remove_handle = handle;

        return err;
}

void msft_req_add_set_filter_enable(struct hci_request *req, bool enable)
{
        struct hci_dev *hdev = req->hdev;
        struct msft_cp_le_set_advertisement_filter_enable cp;

        cp.sub_opcode = MSFT_OP_LE_SET_ADVERTISEMENT_FILTER_ENABLE;
        cp.enable = enable;

        hci_req_add(req, hdev->msft_opcode, sizeof(cp), &cp);
}

int msft_set_filter_enable(struct hci_dev *hdev, bool enable)
{
        struct hci_request req;
        struct msft_data *msft = hdev->msft_data;
        int err;

        if (!msft)
                return -EOPNOTSUPP;

        hci_req_init(&req, hdev);
        msft_req_add_set_filter_enable(&req, enable);
        err = hci_req_run_skb(&req, msft_le_set_advertisement_filter_enable_cb);

        return err;
}