Re: [BlueZ PATCH v6 2/6] adv_monitor: Implement Adv matching based on stored monitors

[Miao-chen Chou <mcchou@chromium.org>]

Hi Luiz,

I did think of adding pattern to bt_ad at the beginning, but here are
reasons why I ended up with hosting the definition of pattern in
adv_monitor.
(1)  Pattern is specific to monitoring purpose. An advertisement
should not include patterns as its fields due to that fact that a
pattern hosts an offset. So I wasn't sure about its justification to
be placed in shared/ad. But if you foresee that it would be reused,
then I am more than happy to add it to shared/ad.
(2) Introducing helpers as you suggested below indeed make it more
unittestable. However, it also implied that EIR data (this is in fact
AD data) needs to be parsed into a new bt_ad for pattern comparison,
and I didn't see an obvious benefit of converting EIR data into a
bt_ad just for the comparison.

Maybe we can add a struct bt_ad_pattern in shared/ad.h and introduce
the following two functions. What do you think?

struct bt_ad_pattern *bt_ad_pattern_new(uint8_t type, size_t offset,
size_t len, const void *data);
/* |data| is one single AD data field so that we can avoid converting
EIR data to bt_ad */
bool bt_ad_pattern bt_ad_pattern_match(struct bt_ad_pattern *pattern,
void *data, size_t len);

On Tue, Oct 6, 2020 at 11:21 PM Luiz Augusto von Dentz
<luiz.dentz@gmail.com> wrote:
>
> Hi Miao,
>
> On Tue, Oct 6, 2020 at 5:17 PM Miao-chen Chou <mcchou@chromium.org> wrote:
> >
> > This implements create an entry point in adapter to start the matching of
> > Adv based on all monitors and invoke the RSSI tracking for Adv reporting.
> >
> > Reviewed-by: Abhishek Pandit-Subedi <abhishekpandit@chromium.org>
> > Reviewed-by: Alain Michaud <alainm@chromium.org>
> > Reviewed-by: Manish Mandlik <mmandlik@chromium.org>
> > ---
> >
> > Changes in v6:
> > - Fix the termination condition of AD data paring and remove unnecessary
> > length check
> >
> > Changes in v5:
> > - Remove unittest helper functions
> >
> > Changes in v3:
> > - Remove unused variables
> > - Fix signature of queue_find()
> >
> >  src/adapter.c     |  35 ++++++--
> >  src/adv_monitor.c | 219 ++++++++++++++++++++++++++++++++++++++++------
> >  src/adv_monitor.h |  12 +++
> >  3 files changed, 234 insertions(+), 32 deletions(-)
> >
> > diff --git a/src/adapter.c b/src/adapter.c
> > index 6d0114a6b..fdd9b3808 100644
> > --- a/src/adapter.c
> > +++ b/src/adapter.c
> > @@ -6601,6 +6601,15 @@ static void update_found_devices(struct btd_adapter *adapter,
> >         bool name_known, discoverable;
> >         char addr[18];
> >         bool duplicate = false;
> > +       GSList *matched_monitors;
> > +
> > +       /* During the background scanning, update the device only when the data
> > +        * match at least one Adv monitor
> > +        */
> > +       matched_monitors = btd_adv_monitor_content_filter(
> > +                               adapter->adv_monitor_manager, data, data_len);
> > +       if (!adapter->discovering && !matched_monitors)
> > +               return;
> >
> >         memset(&eir_data, 0, sizeof(eir_data));
> >         eir_parse(&eir_data, data, data_len);
> > @@ -6646,18 +6655,22 @@ static void update_found_devices(struct btd_adapter *adapter,
> >                 device_store_cached_name(dev, eir_data.name);
> >
> >         /*
> > -        * Only skip devices that are not connected, are temporary and there
> > -        * is no active discovery session ongoing.
> > +        * Only skip devices that are not connected, are temporary, and there
> > +        * is no active discovery session ongoing and no matched Adv monitors
> >          */
> > -       if (!btd_device_is_connected(dev) && (device_is_temporary(dev) &&
> > -                                                !adapter->discovery_list)) {
> > +       if (!btd_device_is_connected(dev) &&
> > +               (device_is_temporary(dev) && !adapter->discovery_list) &&
> > +               !matched_monitors) {
> >                 eir_data_free(&eir_data);
> >                 return;
> >         }
> >
> > -       /* Don't continue if not discoverable or if filter don't match */
> > -       if (!discoverable || (adapter->filtered_discovery &&
> > -           !is_filter_match(adapter->discovery_list, &eir_data, rssi))) {
> > +       /* If there is no matched Adv monitors, don't continue if not
> > +        * discoverable or if active discovery filter don't match.
> > +        */
> > +       if (!matched_monitors && (!discoverable ||
> > +               (adapter->filtered_discovery && !is_filter_match(
> > +                               adapter->discovery_list, &eir_data, rssi)))) {
> >                 eir_data_free(&eir_data);
> >                 return;
> >         }
> > @@ -6714,6 +6727,14 @@ static void update_found_devices(struct btd_adapter *adapter,
> >
> >         eir_data_free(&eir_data);
> >
> > +       /* After the device is updated, notify the matched Adv monitors */
> > +       if (matched_monitors) {
> > +               btd_adv_monitor_notify_monitors(adapter->adv_monitor_manager,
> > +                                               dev, rssi, matched_monitors);
> > +               g_slist_free(matched_monitors);
> > +               matched_monitors = NULL;
> > +       }
> > +
> >         /*
> >          * Only if at least one client has requested discovery, maintain
> >          * list of found devices and name confirming for legacy devices.
> > diff --git a/src/adv_monitor.c b/src/adv_monitor.c
> > index 31ed30a00..fcb127cd4 100644
> > --- a/src/adv_monitor.c
> > +++ b/src/adv_monitor.c
> > @@ -29,15 +29,12 @@
> >  #include "device.h"
> >  #include "log.h"
> >  #include "src/error.h"
> > -#include "src/shared/ad.h"
> >  #include "src/shared/mgmt.h"
> >  #include "src/shared/queue.h"
> >  #include "src/shared/util.h"
> >
> >  #include "adv_monitor.h"
> >
> > -static void monitor_device_free(void *data);
> > -
> >  #define ADV_MONITOR_INTERFACE          "org.bluez.AdvertisementMonitor1"
> >  #define ADV_MONITOR_MGR_INTERFACE      "org.bluez.AdvertisementMonitorManager1"
> >
> > @@ -84,7 +81,7 @@ enum monitor_state {
> >         MONITOR_STATE_HONORED,  /* Accepted by kernel */
> >  };
> >
> > -struct pattern {
> > +struct btd_adv_monitor_pattern {
> >         uint8_t ad_type;
> >         uint8_t offset;
> >         uint8_t length;
> > @@ -133,6 +130,23 @@ struct app_match_data {
> >         const char *path;
> >  };
> >
> > +struct adv_content_filter_info {
> > +       uint8_t eir_len;
> > +       const uint8_t *eir;
> > +
> > +       bool matched;                   /* Intermediate state per monitor */
> > +       GSList *matched_monitors;       /* List of matched monitors */
>
> Please use struct queue on new code.
Addressed in my local v7.

>
> > +};
> > +
> > +struct adv_rssi_filter_info {
> > +       struct btd_device *device;
> > +       int8_t rssi;
> > +};
> > +
> > +static void monitor_device_free(void *data);
> > +static void adv_monitor_filter_rssi(struct adv_monitor *monitor,
> > +                                       struct btd_device *device, int8_t rssi);
> > +
> >  const struct adv_monitor_type {
> >         enum monitor_type type;
> >         const char *name;
> > @@ -155,7 +169,7 @@ static void app_reply_msg(struct adv_monitor_app *app, DBusMessage *reply)
> >  /* Frees a pattern */
> >  static void pattern_free(void *data)
> >  {
> > -       struct pattern *pattern = data;
> > +       struct btd_adv_monitor_pattern *pattern = data;
> >
> >         if (!pattern)
> >                 return;
> > @@ -435,6 +449,36 @@ failed:
> >         return false;
> >  }
> >
> > +/* Allocates and initiates a pattern with the given content */
> > +static struct btd_adv_monitor_pattern *pattern_create(
> > +       uint8_t ad_type, uint8_t offset, uint8_t length, const uint8_t *value)
> > +{
> > +       struct btd_adv_monitor_pattern *pattern;
> > +
> > +       if (offset > BT_AD_MAX_DATA_LEN - 1)
> > +               return NULL;
> > +
> > +       if ((ad_type > BT_AD_3D_INFO_DATA &&
> > +               ad_type != BT_AD_MANUFACTURER_DATA) ||
> > +               ad_type < BT_AD_FLAGS) {
> > +               return NULL;
> > +       }
> > +
> > +       if (!value || !length || offset + length > BT_AD_MAX_DATA_LEN)
> > +               return NULL;
> > +
> > +       pattern = new0(struct btd_adv_monitor_pattern, 1);
> > +       if (!pattern)
> > +               return NULL;
> > +
> > +       pattern->ad_type = ad_type;
> > +       pattern->offset = offset;
> > +       pattern->length = length;
> > +       memcpy(pattern->value, value, pattern->length);
>
> I wonder why you didn't add pattern matching into bt_ad directly, that
> should make it simpler to unit test such feature and enable using in
> other tools as well.
>
Please see my reply above.

> > +       return pattern;
> > +}
> > +
> >  /* Retrieves Patterns from the remote Adv Monitor object, verifies the values
> >   * and update the local Adv Monitor
> >   */
> > @@ -464,7 +508,7 @@ static bool parse_patterns(struct adv_monitor *monitor, const char *path)
> >                 int value_len;
> >                 uint8_t *value;
> >                 uint8_t offset, ad_type;
> > -               struct pattern *pattern;
> > +               struct btd_adv_monitor_pattern *pattern;
> >                 DBusMessageIter struct_iter, value_iter;
> >
> >                 dbus_message_iter_recurse(&array_iter, &struct_iter);
> > @@ -496,28 +540,10 @@ static bool parse_patterns(struct adv_monitor *monitor, const char *path)
> >                 dbus_message_iter_get_fixed_array(&value_iter, &value,
> >                                                         &value_len);
> >
> > -               // Verify the values
> > -               if (offset > BT_AD_MAX_DATA_LEN - 1)
> > -                       goto failed;
> > -
> > -               if ((ad_type > BT_AD_3D_INFO_DATA &&
> > -                       ad_type != BT_AD_MANUFACTURER_DATA) ||
> > -                       ad_type < BT_AD_FLAGS) {
> > -                       goto failed;
> > -               }
> > -
> > -               if (!value || value_len <= 0 || value_len > BT_AD_MAX_DATA_LEN)
> > -                       goto failed;
> > -
> > -               pattern = new0(struct pattern, 1);
> > +               pattern = pattern_create(ad_type, offset, value_len, value);
> >                 if (!pattern)
> >                         goto failed;
> >
> > -               pattern->ad_type = ad_type;
> > -               pattern->offset = offset;
> > -               pattern->length = value_len;
> > -               memcpy(pattern->value, value, pattern->length);
> > -
> >                 queue_push_tail(monitor->patterns, pattern);
> >
> >                 dbus_message_iter_next(&array_iter);
> > @@ -952,6 +978,149 @@ void btd_adv_monitor_manager_destroy(struct btd_adv_monitor_manager *manager)
> >         manager_destroy(manager);
> >  }
> >
> > +static bool pattern_match(const uint8_t *eir, uint8_t eir_len,
> > +                               const struct btd_adv_monitor_pattern *pattern)
> > +{
> > +       const uint8_t *data;
> > +       uint8_t idx = 0;
> > +       uint8_t field_len, data_len, data_type;
> > +
> > +       while (idx < eir_len - 1) {
> > +               field_len = eir[0];
> > +
> > +               /* Check for the end of EIR */
> > +               if (field_len == 0)
> > +                       break;
> > +
> > +               idx += field_len + 1;
> > +
> > +               /* Do not continue filtering if got incorrect length */
> > +               if (idx > eir_len)
> > +                       break;
> > +
> > +               data = &eir[2];
> > +               data_type = eir[1];
> > +               data_len = field_len - 1;
> > +
> > +               eir += field_len + 1;
> > +
> > +               if (data_type != pattern->ad_type)
> > +                       continue;
> > +
> > +               if (data_len < pattern->offset + pattern->length)
> > +                       continue;
> > +
> > +               if (!memcmp(data + pattern->offset, pattern->value,
> > +                               pattern->length))
> > +                       return true;
> > +       }
>
> Perhaps something like:
>
> struct bt_ad *bt_ad_new_with_data(uint8_t *data, uint8_t len);
>
> and
>
> bool bt_ad_has_pattern(struct bt_ad *ad, const struct bt_ad_pattern *pattern);
>
Please see my reply above.

> > +       return false;
> > +}
> > +
> > +/* Processes the content matching based on a pattern */
> > +static void adv_match_per_pattern(void *data, void *user_data)
> > +{
> > +       struct btd_adv_monitor_pattern *pattern = data;
> > +       struct adv_content_filter_info *info = user_data;
> > +
> > +       if (!pattern || info->matched)
> > +               return;
> > +
> > +       info->matched = pattern_match(info->eir, info->eir_len, pattern);
> > +}
> > +
> > +/* Processes the content matching based pattern(s) of a monitor */
> > +static void adv_match_per_monitor(void *data, void *user_data)
> > +{
> > +       struct adv_monitor *monitor = data;
> > +       struct adv_content_filter_info *info = user_data;
> > +
> > +       if (!monitor && monitor->state != MONITOR_STATE_HONORED)
> > +               return;
> > +
> > +       /* Reset the intermediate matched status */
> > +       info->matched = false;
> > +
> > +       if (monitor->type == MONITOR_TYPE_OR_PATTERNS) {
> > +               queue_foreach(monitor->patterns, adv_match_per_pattern, info);
> > +               if (info->matched)
> > +                       goto matched;
> > +       }
> > +
> > +       return;
> > +
> > +matched:
> > +       info->matched_monitors = g_slist_prepend(info->matched_monitors,
> > +                                                       monitor);
> > +}
> > +
> > +/* Processes the content matching for the monitor(s) of an app */
> > +static void adv_match_per_app(void *data, void *user_data)
> > +{
> > +       struct adv_monitor_app *app = data;
> > +
> > +       if (!app)
> > +               return;
> > +
> > +       queue_foreach(app->monitors, adv_match_per_monitor, user_data);
> > +}
> > +
> > +/* Processes the content matching for every app without RSSI filtering and
> > + * notifying monitors. The caller is responsible of releasing the memory of the
> > + * list but not the data.
> > + * Returns the list of monitors whose content match eir.
> > + */
> > +GSList *btd_adv_monitor_content_filter(struct btd_adv_monitor_manager *manager,
> > +                                       const uint8_t *eir, uint8_t eir_len)
> > +{
> > +       struct adv_content_filter_info info;
> > +
> > +       if (!manager || !eir || !eir_len)
> > +               return NULL;
> > +
> > +       info.eir_len = eir_len;
> > +       info.eir = eir;
> > +       info.matched_monitors = NULL;
> > +
> > +       queue_foreach(manager->apps, adv_match_per_app, &info);
> > +
> > +       return info.matched_monitors;
> > +}
> > +
> > +/* Wraps adv_monitor_filter_rssi() to processes the content-matched monitor with
> > + * RSSI filtering and notifies it on device found/lost event
> > + */
> > +static void monitor_filter_rssi(gpointer a, gpointer b)
> > +{
> > +       struct adv_monitor *monitor = a;
> > +       struct adv_rssi_filter_info *info = b;
> > +
> > +       if (!monitor || !info)
> > +               return;
> > +
> > +       adv_monitor_filter_rssi(monitor, info->device, info->rssi);
> > +}
> > +
> > +/* Processes every content-matched monitor with RSSI filtering and notifies on
> > + * device found/lost event. The caller is responsible of releasing the memory
> > + * of matched_monitors list but not its data.
> > + */
> > +void btd_adv_monitor_notify_monitors(struct btd_adv_monitor_manager *manager,
> > +                                       struct btd_device *device, int8_t rssi,
> > +                                       GSList *matched_monitors)
> > +{
> > +       struct adv_rssi_filter_info info;
> > +
> > +       if (!manager || !device || !matched_monitors)
> > +               return;
> > +
> > +       info.device = device;
> > +       info.rssi = rssi;
> > +
> > +       g_slist_foreach(matched_monitors, monitor_filter_rssi, &info);
> > +}
> > +
> >  /* Matches a device based on btd_device object */
> >  static bool monitor_device_match(const void *a, const void *b)
> >  {
> > diff --git a/src/adv_monitor.h b/src/adv_monitor.h
> > index 13d5d7282..e2482e11e 100644
> > --- a/src/adv_monitor.h
> > +++ b/src/adv_monitor.h
> > @@ -11,16 +11,28 @@
> >  #ifndef __ADV_MONITOR_H
> >  #define __ADV_MONITOR_H
> >
> > +#include <glib.h>
> > +
> > +#include "src/shared/ad.h"
> > +
> >  struct mgmt;
> >  struct btd_device;
> >  struct btd_adapter;
> >  struct btd_adv_monitor_manager;
> > +struct btd_adv_monitor_pattern;
> >
> >  struct btd_adv_monitor_manager *btd_adv_monitor_manager_create(
> >                                                 struct btd_adapter *adapter,
> >                                                 struct mgmt *mgmt);
> >  void btd_adv_monitor_manager_destroy(struct btd_adv_monitor_manager *manager);
> >
> > +GSList *btd_adv_monitor_content_filter(struct btd_adv_monitor_manager *manager,
> > +                                       const uint8_t *eir, uint8_t eir_len);
> > +
> > +void btd_adv_monitor_notify_monitors(struct btd_adv_monitor_manager *manager,
> > +                                       struct btd_device *device, int8_t rssi,
> > +                                       GSList *matched_monitors);
> > +
> >  void btd_adv_monitor_device_remove(struct btd_adv_monitor_manager *manager,
> >                                    struct btd_device *device);
> >
> > --
> > 2.26.2
> >
>
>
> --
> Luiz Augusto von Dentz

Thanks,
Miao