Return-Path: MIME-Version: 1.0 In-Reply-To: References: <1415878033-6766-1-git-send-email-marcin.kraglak@tieto.com> <1415878033-6766-2-git-send-email-marcin.kraglak@tieto.com> Date: Tue, 18 Nov 2014 12:25:05 -0800 Message-ID: Subject: Re: [RFC 01/11] shared/gatt-client: Add read-by-uuid function From: Arman Uguray To: Marcin Kraglak Cc: Luiz Augusto von Dentz , "linux-bluetooth@vger.kernel.org" Content-Type: text/plain; charset=UTF-8 Sender: linux-bluetooth-owner@vger.kernel.org List-ID: Hi Marcin, > On Tue, Nov 18, 2014 at 8:33 AM, Marcin Kraglak wrote: > Hi Arman, > > On 18 November 2014 08:09, Marcin Kraglak wrote: >> Hi Arman, >> >> On 18 November 2014 00:36, Arman Uguray wrote: >>> Hi Luiz, >>> >>>> On Fri, Nov 14, 2014 at 5:51 AM, Luiz Augusto von Dentz wrote: >>>> Hi Marcin, >>>> >>>> On Fri, Nov 14, 2014 at 3:13 PM, Marcin Kraglak >>>> wrote: >>>>> Hi Luiz, >>>>> >>>>> On 14 November 2014 13:44, Luiz Augusto von Dentz wrote: >>>>>> Hi Marcin, >>>>>> >>>>>> On Thu, Nov 13, 2014 at 1:27 PM, Marcin Kraglak >>>>>> wrote: >>>>>>> This is exposed to allow client reading characteristic values >>>>>>> with known uuid. >>>>>>> --- >>>>>>> src/shared/gatt-client.c | 271 +++++++++++++++++++++++++++++++++++++++++++++++ >>>>>>> src/shared/gatt-client.h | 18 ++++ >>>>>>> 2 files changed, 289 insertions(+) >>>>>>> >>>>>>> diff --git a/src/shared/gatt-client.c b/src/shared/gatt-client.c >>>>>>> index 30b271e..0493b05 100644 >>>>>>> --- a/src/shared/gatt-client.c >>>>>>> +++ b/src/shared/gatt-client.c >>>>>>> @@ -44,6 +44,11 @@ >>>>>>> #define GATT_SVC_UUID 0x1801 >>>>>>> #define SVC_CHNGD_UUID 0x2a05 >>>>>>> >>>>>>> +static const uint8_t bt_base_uuid[16] = { >>>>>>> + 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x10, 0x00, >>>>>>> + 0x80, 0x00, 0x00, 0x80, 0x5F, 0x9B, 0x34, 0xFB >>>>>>> +}; >>>>>>> + >>>>>>> struct chrc_data { >>>>>>> /* The public characteristic entry. */ >>>>>>> bt_gatt_characteristic_t chrc_external; >>>>>>> @@ -122,6 +127,15 @@ struct bt_gatt_client { >>>>>>> bool in_svc_chngd; >>>>>>> }; >>>>>>> >>>>>>> +static bool is_bluetooth_uuid(const uint8_t uuid[BT_GATT_UUID_SIZE]) >>>>>>> +{ >>>>>>> + if (memcmp(uuid, bt_base_uuid, 2) || >>>>>>> + memcmp(&uuid[4], &bt_base_uuid[4], 12)) >>>>>>> + return false; >>>>>>> + >>>>>>> + return true; >>>>>>> +} >>>>>>> + >>>>>> >>>>>> Is this really different from uuid_cmp? Perhaps you use set uuid16 >>>>>> properly it should just do the same you are doing above. >>>>> Ok, I'll use it. >>>>>> >>>>>>> struct notify_data { >>>>>>> struct bt_gatt_client *client; >>>>>>> bool removed; >>>>>>> @@ -2001,6 +2015,263 @@ bool bt_gatt_client_read_long_value(struct bt_gatt_client *client, >>>>>>> return true; >>>>>>> } >>>>>>> >>>>>>> +struct read_by_uuid_res { >>>>>>> + uint16_t handle; >>>>>>> + uint8_t length; >>>>>>> + uint8_t *data; >>>>>>> + struct read_by_uuid_res *next; >>>>>>> +}; >>>>>>> + >>>>>>> +bool read_by_uuid_res_get(struct read_by_uuid_res *result, uint16_t *handle, >>>>>>> + uint8_t *length, uint8_t **data) >>>>>>> +{ >>>>>>> + if (!result) >>>>>>> + return false; >>>>>>> + >>>>>>> + *length = result->length; >>>>>>> + *handle = result->handle; >>>>>>> + *data = result->data; >>>>>>> + >>>>>>> + return true; >>>>>>> +} >>>>>>> + >>>>>>> +struct read_by_uuid_res *read_by_uuid_res_next(struct read_by_uuid_res *result) >>>>>>> +{ >>>>>>> + if (!result) >>>>>>> + return NULL; >>>>>>> + >>>>>>> + return result->next; >>>>>>> +} >>>>>>> + >>>>>>> +struct read_by_uuid_op { >>>>>>> + struct bt_gatt_client *client; >>>>>>> + bt_gatt_client_read_by_uuid_callback_t callback; >>>>>>> + int ref_count; >>>>>>> + uint16_t start_handle; >>>>>>> + uint16_t end_handle; >>>>>>> + uint8_t uuid[BT_GATT_UUID_SIZE]; >>>>>>> + struct read_by_uuid_res *result_head; >>>>>>> + struct read_by_uuid_res *result_tail; >>>>>>> + void *user_data; >>>>>>> + bt_gatt_client_destroy_func_t destroy; >>>>>>> +}; >>>>>> >>>>>> Im not really sure this lists are really helping us, perhaps this is >>>>>> the effect of using iterators in the API but that seems to create >>>>>> duplicated code. >>>>>> >>>>>>> +static bool append_read_by_uuid_result(struct read_by_uuid_op *op, >>>>>>> + uint16_t handle, uint16_t length, >>>>>>> + const uint8_t *data) >>>>>>> +{ >>>>>>> + struct read_by_uuid_res *result; >>>>>>> + >>>>>>> + result = new0(struct read_by_uuid_res, 1); >>>>>>> + if (!result) >>>>>>> + return false; >>>>>>> + >>>>>>> + result->data = malloc(length); >>>>>>> + if (!result->data) { >>>>>>> + free(result); >>>>>>> + return false; >>>>>>> + } >>>>>>> + >>>>>>> + result->handle = handle; >>>>>>> + result->length = length; >>>>>>> + memcpy(result->data, data, length); >>>>>>> + >>>>>>> + if (op->result_head) { >>>>>>> + op->result_tail->next = result; >>>>>>> + op->result_tail = result; >>>>>>> + } else { >>>>>>> + op->result_head = op->result_tail = result; >>>>>>> + } >>>>>>> + >>>>>>> + return true; >>>>>>> +} >>>>>>> + >>>>>>> +static void destroy_read_by_uuid_result(void *data) >>>>>>> +{ >>>>>>> + struct read_by_uuid_res *result = data; >>>>>>> + >>>>>>> + free(result->data); >>>>>>> + free(result); >>>>>>> +} >>>>>>> + >>>>>>> +static struct read_by_uuid_op *read_by_uuid_op_ref(struct read_by_uuid_op *op) >>>>>>> +{ >>>>>>> + __sync_fetch_and_add(&op->ref_count, 1); >>>>>>> + >>>>>>> + return op; >>>>>>> +} >>>>>>> + >>>>>>> +static void read_by_uuid_op_unref(void *data) >>>>>>> +{ >>>>>>> + struct read_by_uuid_res *next, *temp; >>>>>>> + struct read_by_uuid_op *op = data; >>>>>>> + >>>>>>> + if (__sync_sub_and_fetch(&op->ref_count, 1)) >>>>>>> + return; >>>>>>> + >>>>>>> + if (op->destroy) >>>>>>> + op->destroy(op->user_data); >>>>>>> + >>>>>>> + for (temp = op->result_head; temp; temp = next) { >>>>>>> + next = temp->next; >>>>>>> + destroy_read_by_uuid_result(temp); >>>>>>> + } >>>>>>> + >>>>>>> + free(op); >>>>>>> +} >>>>>>> + >>>>>>> +static void read_by_uuid_cb(uint8_t opcode, const void *pdu, >>>>>>> + uint16_t length, void *user_data) >>>>>>> +{ >>>>>>> + struct read_by_uuid_op *op = user_data; >>>>>>> + size_t data_length; >>>>>>> + uint8_t att_ecode; >>>>>>> + uint16_t offset, last_handle; >>>>>>> + const uint8_t *data; >>>>>>> + bool success; >>>>>>> + >>>>>>> + if (opcode == BT_ATT_OP_ERROR_RSP) { >>>>>>> + att_ecode = process_error(pdu, length); >>>>>>> + if (att_ecode == BT_ATT_ERROR_ATTRIBUTE_NOT_FOUND) >>>>>>> + success = true; >>>>>>> + else >>>>>>> + success = false; >>>>>>> + >>>>>>> + goto done; >>>>>>> + } >>>>>>> + >>>>>>> + if (opcode != BT_ATT_OP_READ_BY_TYPE_RSP || (!pdu && length)) { >>>>>>> + success = false; >>>>>>> + att_ecode = 0; >>>>>>> + goto done; >>>>>>> + } >>>>>>> + >>>>>>> + data_length = ((const uint8_t *) pdu)[0]; >>>>>>> + if ((length - 1) % data_length) { >>>>>>> + success = false; >>>>>>> + att_ecode = 0; >>>>>>> + goto done; >>>>>>> + } >>>>>>> + >>>>>>> + for (offset = 1; offset < length; offset += data_length) { >>>>>>> + data = pdu + offset; >>>>>>> + if (!append_read_by_uuid_result(op, get_le16(data), >>>>>>> + data_length - 2, data + 2)) { >>>>>>> + success = false; >>>>>>> + att_ecode = 0; >>>>>>> + goto done; >>>>>>> + } >>>>>>> + } >>>>>>> + >>>>>>> + last_handle = get_le16(pdu + length - data_length); >>>>>>> + if (last_handle < op->end_handle) { >>>>>>> + uint8_t pdu[20]; >>>>>>> + >>>>>>> + put_le16(last_handle + 1, pdu); >>>>>>> + put_le16(op->end_handle, pdu + 2); >>>>>>> + >>>>>>> + if (is_bluetooth_uuid(op->uuid)) { >>>>>>> + put_le16((op->uuid[2] << 8) + op->uuid[3], pdu + 4); >>>>>>> + /* >>>>>>> + * 2 octets - start handle >>>>>>> + * 2 octets - end handle >>>>>>> + * 2 octets - 16-bit uuid >>>>>>> + */ >>>>>>> + length = 6; >>>>>>> + } else { >>>>>>> + bswap_128(&op->uuid, pdu + 4); >>>>>>> + /* >>>>>>> + * 2 octets - start handle >>>>>>> + * 2 octets - end handle >>>>>>> + * 16 octets - 128-bit uuid >>>>>>> + */ >>>>>>> + length = 20; >>>>>>> + } >>>>>>> + >>>>>>> + if (!bt_att_send(op->client->att, BT_ATT_OP_READ_BY_TYPE_REQ, >>>>>>> + pdu, length, read_by_uuid_cb, >>>>>>> + read_by_uuid_op_ref(op), >>>>>>> + read_by_uuid_op_unref)) { >>>>>>> + read_by_uuid_op_unref(op); >>>>>>> + success = false; >>>>>>> + att_ecode = 0; >>>>>>> + goto done; >>>>>>> + } >>>>>>> + >>>>>>> + return; >>>>>>> + } >>>>>>> + >>>>>>> + success = true; >>>>>>> + att_ecode = 0; >>>>>>> + >>>>>>> +done: >>>>>>> + if (op->callback) >>>>>>> + op->callback(success, att_ecode, op->result_head, >>>>>>> + op->user_data); >>>>>>> +} >>>>>>> + >>>>>>> +bool bt_gatt_client_read_by_uuid(struct bt_gatt_client *client, >>>>>>> + uint16_t start_handle, uint16_t end_handle, >>>>>>> + const uint8_t uuid[BT_GATT_UUID_SIZE], >>>>>>> + bt_gatt_client_read_by_uuid_callback_t callback, >>>>>>> + void *user_data, >>>>>>> + bt_gatt_client_destroy_func_t destroy) >>>>>>> +{ >>>>>>> + struct read_by_uuid_op *op; >>>>>>> + uint16_t length; >>>>>>> + uint8_t pdu[20]; >>>>>>> + >>>>>>> + if (!client) >>>>>>> + return false; >>>>>>> + >>>>>>> + if (start_handle > end_handle || start_handle == 0x0000) >>>>>>> + return false; >>>>>>> + >>>>>>> + op = new0(struct read_by_uuid_op, 1); >>>>>>> + if (!op) >>>>>>> + return false; >>>>>>> + >>>>>>> + op->client = client; >>>>>>> + op->start_handle = start_handle; >>>>>>> + op->end_handle = end_handle; >>>>>>> + op->destroy = destroy; >>>>>>> + op->callback = callback; >>>>>>> + op->user_data = user_data; >>>>>>> + memcpy(&op->uuid, uuid, 16); >>>>>>> + >>>>>>> + /* Convert to 16-bit if it is Bluetooth UUID */ >>>>>>> + if (is_bluetooth_uuid(uuid)) { >>>>>>> + put_le16((uuid[2] << 8) + uuid[3], pdu + 4); >>>>>>> + /* >>>>>>> + * 2 octets - start handle >>>>>>> + * 2 octets - end handle >>>>>>> + * 2 octets - 16-bit uuid >>>>>>> + */ >>>>>>> + length = 6; >>>>>>> + } else { >>>>>>> + bswap_128(uuid, pdu + 4); >>>>>>> + /* >>>>>>> + * 2 octets - start handle >>>>>>> + * 2 octets - end handle >>>>>>> + * 16 octets - 128-bit uuid >>>>>>> + */ >>>>>>> + length = 20; >>>>>>> + } >>>>>>> + >>>>>>> + put_le16(start_handle, pdu); >>>>>>> + put_le16(end_handle, pdu + 2); >>>>>>> + >>>>>>> + if (!bt_att_send(client->att, BT_ATT_OP_READ_BY_TYPE_REQ, pdu, >>>>>>> + length, read_by_uuid_cb, >>>>>>> + read_by_uuid_op_ref(op), >>>>>>> + read_by_uuid_op_unref)) { >>>>>>> + free(op); >>>>>>> + return false; >>>>>>> + } >>>>>>> + >>>>>>> + return true; >>>>>>> +} >>>>>>> + >>>>>>> bool bt_gatt_client_write_without_response(struct bt_gatt_client *client, >>>>>>> uint16_t value_handle, >>>>>>> bool signed_write, >>>>>>> diff --git a/src/shared/gatt-client.h b/src/shared/gatt-client.h >>>>>>> index adccfc5..921ed75 100644 >>>>>>> --- a/src/shared/gatt-client.h >>>>>>> +++ b/src/shared/gatt-client.h >>>>>>> @@ -145,6 +145,24 @@ bool bt_gatt_client_read_long_value(struct bt_gatt_client *client, >>>>>>> void *user_data, >>>>>>> bt_gatt_client_destroy_func_t destroy); >>>>>>> >>>>>>> +struct read_by_uuid_res; >>>>>>> + >>>>>>> +struct read_by_uuid_res *read_by_uuid_res_next(struct read_by_uuid_res *result); >>>>>>> +bool read_by_uuid_res_get(struct read_by_uuid_res *result, uint16_t *handle, >>>>>>> + uint8_t *length, uint8_t **data); >>>>>>> + >>>>>>> +typedef void (*bt_gatt_client_read_by_uuid_callback_t)(bool success, >>>>>>> + uint8_t att_ecode, >>>>>>> + struct read_by_uuid_res *result, >>>>>>> + void *user_data); >>>>>>> + >>>>>>> +bool bt_gatt_client_read_by_uuid(struct bt_gatt_client *client, >>>>>>> + uint16_t start_handle, uint16_t end_handle, >>>>>>> + const uint8_t uuid[BT_GATT_UUID_SIZE], >>>>>>> + bt_gatt_client_read_by_uuid_callback_t callback, >>>>>>> + void *user_data, >>>>>>> + bt_gatt_client_destroy_func_t destroy); >>>>>> >>>>>> Isn't this essentially duplicating bt_gatt_service_iter_next_by_uuid? >>>>>> I mean we should be reading everything already but this doesn't seems >>>>>> to using the cache and in case it is just to fulfill a test perhaps it >>>>>> is better to do it in gatt-helpers so we keep bt_gatt_client API >>>>>> clean. >>>>> >>>>> It is functionality of GATT client described in chapter 4.8.2 "Read >>>>> Using Characteristic UUID". >>>>> Difference is that client can read attributes by passing UUID, and >>>>> results can contain >>>>> different valu lengths. And client interprets results instead of gatt-helpers. >>>>> I implemented it here because all read/write operations on >>>>> characteristics and descriptors >>>>> are exposed in bt_gatt_client, and all discovery stuff is implemented >>>>> in gatt_helpers. But if >>>>> you don't agree I can change it. >>>> >>>> I see, it does actually end up reading, perhaps it is a good idea to >>>> keep it here then. In the other hand this API seems to be going in the >>>> same direction that gatt-db had with access by handles, perhaps we >>>> should do an API facelift to access by attribute such as we did with >>>> gatt-db, also the iterator could be replaced with queues which I guess >>>> is not that different in the end. >>>> >>> >>> The reason we have the iterators and not queues is because Marcel >>> wanted to keep shared/queue as an internal utility of shared code >>> (although shared/gatt-db exposes it to upper layers). In this case >>> performing the read/write operations by handle isn't bad since the >>> code simply constructs the request and sends it out and doesn't need >>> to do an internal lookup for it. >>> >>> I commented on Marcin's new patch set that this code should go to >>> gatt-helpers. I don't think it makes sense to put it in gatt-client, >>> especially since the characteristic and include declaration discovery >> >> Include service discovery can't be based on that API, because it >> performs read_by_type >> and read requests during discovery. It can be shared by characteristic >> discovery only. >> Additionally in characteristic discovery gatt-client interprets >> results and cancel if length of >> response is not valid. Also, you will be able to use include service >> iterator and characteristic iterators >> to read results of read-by-uuid (because it checks type of response >> and length). I don't see benefit >> having this in one place. >> I guess you're right in that with what I'm proposing we can't do any of the early cancellations in case of malformed PDUs and I guess you have to perform the read requests in between read by type requests for included discovery? Anyway, I'm fine with a standalone API for now then, though I'd like to see us reduce duplicated code where we can. > > One more thing: I moved it to gatt-helpers, and once I've added public > API to read-by-type, > I had to write iterator to handle results, and next iterator in > gatt-client, to expose results there. > And it would make sense if it will be used somewhere else (I mean > read-by-uuid in gatt-helpers), > but it will be used only in read-by-uuid() in gatt-client. Any thoughts? > Actually what is the use case here? I think users of shared/gatt-client won't really need this API since gatt-client already will have populated its cache of handles and UUIDs, so the users can just iterate through that and send out a single read request to read only one handle. So I'm assuming this is mainly for the unit tests? Anyway, use your best judgement. I think it would be enough here to just have a function in gatt-helpers and none in gatt-client. We would then have a simple PDU iterator in gatt-helpers for getting the handles and values out. If we figure later that this belongs in gatt-client then we can move it over or wrap around it there. >>> procedures are already based on Read By Type and we can create a >>> cleaner API by having this in gatt-helpers and basing the char/incl >>> discovery functions on that instead. >>> >>>>>> >>>>>>> bool bt_gatt_client_write_without_response(struct bt_gatt_client *client, >>>>>>> uint16_t value_handle, >>>>>>> bool signed_write, >>>>>>> -- >>>>>>> 1.9.3 >>>>>>> >>>>>>> -- >>>>>>> To unsubscribe from this list: send the line "unsubscribe linux-bluetooth" in >>>>>>> the body of a message to majordomo@vger.kernel.org >>>>>>> More majordomo info at http://vger.kernel.org/majordomo-info.html >>>>>> >>>>>> >>>>>> >>>>>> -- >>>>>> Luiz Augusto von Dentz >>>>> >>>>> BR >>>>> Marcin >>>> >>>> >>>> >>>> -- >>>> Luiz Augusto von Dentz >>>> -- >>>> To unsubscribe from this list: send the line "unsubscribe linux-bluetooth" in >>>> the body of a message to majordomo@vger.kernel.org >>>> More majordomo info at http://vger.kernel.org/majordomo-info.html >>> >>> Cheers, >>> Arman >> >> BR >> Marcin > > BR > Marcin Cheers, Arman