Querying

Query Song

The querySong function provides the users the song is provisioned to play for, along with the regions the song is provisioned to play in.

querySong only has one parameter:

• char *songName - The name of the song to query.

void querySong(char *songName) {}

The first step to showing the provisioned users is to get the songs owner. Since we keep track of users by ID, we need to relate that ID back to a name from the device_secrets.

// First, get the songs owner
printf("Provisioned Users: ");
for (int j = 0; j < (sizeof(user_data) / sizeof(user_data[1])); j++) {
    if (user_data[j].id == meta.owner_id) {
        printf("%s (owner), ", user_data[j].name);
    }
}

The rest of the users the song has been provisioned for can be found in the sharedInfo field of the metadata structure. We can see which users the song has been shared with by checking which indices of sharedInfo have data. The index in the array plus one (as provisioned users have a uid > 0) corresponds to the users ID. For example, if the song is shared with the user of ID 6, the sharedInfo will be stored at index 5.

// Next, get the users it's shared with
for(int i = 0; i < sizeof(meta.sharedInfo)/sizeof(meta.sharedInfo[0]); i++) {
    if (meta.sharedInfo[i][0] != NULL){
        for (int j = 0; j < (sizeof(user_data) / sizeof(user_data[1])); j++) {
            if (user_data[j].id == (i + 1)) {
                printf("%s, ", user_data[j].name);
            }
        }
    }
}

Finally, we can tell which regions the song has been provisioned for by looking at the region_ids field of the metadata. These ID's are stored sequentially, so we can break early when we hit a null. We then relate the ID back to a friendly name by using the region_data from the device_secrets as shown below:

// Print provisioned regions
printf("Provisioned Regions: ");
for(int i = 0; i < sizeof(meta.region_ids)/sizeof(meta.region_ids[0]); i++) {
    if (meta.region_ids[i] == NULL){
        break;
    } else {
        for (int j = 0; j < (sizeof(region_data) / sizeof(region_data[1])); j++) {
            if (region_data[j].id == meta.region_ids[i]) {
                printf("%s, ", region_data[j].name);
            }
        }
    }
}

Query Player

This function runs once at device startup; telling the user what region(s) their miPod is provisioned and lists all the authorized usernames for the device. query_player has no parameters and returns void.

void query_player() {
    c->query.num_regions = PROVISIONED_REGIONS;
    c->query.num_users = PROVISIONED_USERS;

    for (int i = 0; i < PROVISIONED_REGIONS; i++) {
        strcpy((char *)q_region_lookup(c->query, i), region_data[i].name);
    }

    for (int i = 0; i < PROVISIONED_USERS; i++) {
        strcpy((char *)q_user_lookup(c->query, i), user_data[i].name);
    }

    mb_printf("Queried player (%d regions, %d users)\r\n", c->query.num_regions, c->query.num_users);
}