This patch implements the ATT protocol "Read By Type" request for
shared/gatt-server. Logic is implemented that allows asynchronous
reading of non-standard attribute values via the registered read and
read completion callbacks.
---
src/shared/gatt-server.c | 246 ++++++++++++++++++++++++++++++++++++++++++++++-
1 file changed, 243 insertions(+), 3 deletions(-)
diff --git a/src/shared/gatt-server.c b/src/shared/gatt-server.c
index 18f82c4..ddb0be1 100644
--- a/src/shared/gatt-server.c
+++ b/src/shared/gatt-server.c
@@ -40,6 +40,16 @@
#define MIN(a, b) ((a) < (b) ? (a) : (b))
#endif
+struct async_read_op {
+ struct bt_gatt_server *server;
+ uint8_t opcode;
+ bool done;
+ uint8_t *pdu;
+ size_t pdu_len;
+ size_t value_len;
+ struct queue *db_data;
+};
+
struct bt_gatt_server {
struct gatt_db *db;
struct bt_att *att;
@@ -48,6 +58,9 @@ struct bt_gatt_server {
unsigned int mtu_id;
unsigned int read_by_grp_type_id;
+ unsigned int read_by_type_id;
+
+ struct async_read_op *pending_read_op;
bt_gatt_server_debug_func_t debug_callback;
bt_gatt_server_destroy_func_t debug_destroy;
@@ -61,11 +74,23 @@ static void bt_gatt_server_free(struct bt_gatt_server *server)
bt_att_unregister(server->att, server->mtu_id);
bt_att_unregister(server->att, server->read_by_grp_type_id);
+ bt_att_unregister(server->att, server->read_by_type_id);
bt_att_unref(server->att);
+ if (server->pending_read_op)
+ server->pending_read_op->server = NULL;
+
free(server);
}
+static uint8_t att_ecode_from_error(int err)
+{
+ if (err < 0 || err > UINT8_MAX)
+ return 0xff;
+
+ return err;
+}
+
static void encode_error_rsp(uint8_t opcode, uint16_t handle, uint8_t ecode,
uint8_t pdu[4])
{
@@ -136,14 +161,15 @@ static bool encode_read_by_grp_type_rsp(struct gatt_db *db, struct queue *q,
* value is seen.
*/
if (iter == 0) {
- data_val_len = value.iov_len;
+ data_val_len = MIN(MIN((unsigned)mtu - 6, 251),
+ value.iov_len);
pdu[0] = data_val_len + 4;
iter++;
} else if (value.iov_len != data_val_len)
break;
/* Stop if this unit would surpass the MTU */
- if (iter + data_val_len + 4 > mtu)
+ if (iter + data_val_len + 4 > mtu - 1)
break;
gatt_db_attribute_get_service_handles(attrib, &start_handle,
@@ -151,7 +177,7 @@ static bool encode_read_by_grp_type_rsp(struct gatt_db *db, struct queue *q,
put_le16(start_handle, pdu + iter);
put_le16(end_handle, pdu + iter + 2);
- memcpy(pdu + iter + 4, value.iov_base, value.iov_len);
+ memcpy(pdu + iter + 4, value.iov_base, data_val_len);
iter += data_val_len + 4;
}
@@ -248,6 +274,212 @@ done:
NULL, NULL, NULL);
}
+static void async_read_op_destroy(struct async_read_op *op)
+{
+ if (op->server)
+ op->server->pending_read_op = NULL;
+
+ queue_destroy(op->db_data, NULL);
+ free(op->pdu);
+ free(op);
+}
+
+static void process_read_by_type(struct async_read_op *op);
+
+static void read_by_type_read_complete_cb(struct gatt_db_attribute *attr,
+ int err, const uint8_t *value,
+ size_t len, void *user_data)
+{
+ struct async_read_op *op = user_data;
+ struct bt_gatt_server *server = op->server;
+ uint16_t mtu;
+ uint16_t handle;
+
+ if (!server) {
+ async_read_op_destroy(op);
+ return;
+ }
+
+ mtu = bt_att_get_mtu(server->att);
+ handle = gatt_db_attribute_get_handle(attr);
+
+ /* Terminate the operation if there was an error */
+ if (err) {
+ uint8_t pdu[4];
+ uint8_t att_ecode = att_ecode_from_error(err);
+
+ encode_error_rsp(BT_ATT_OP_READ_BY_TYPE_REQ, handle, att_ecode,
+ pdu);
+ bt_att_send(server->att, BT_ATT_OP_ERROR_RSP, pdu, 4, NULL,
+ NULL, NULL);
+ async_read_op_destroy(op);
+ return;
+ }
+
+ if (op->pdu_len == 0) {
+ op->value_len = MIN(MIN((unsigned) mtu - 4, 253), len);
+ op->pdu[0] = op->value_len + 2;
+ op->pdu_len++;
+ } else if (len != op->value_len) {
+ op->done = true;
+ goto done;
+ }
+
+ /* Stop if this would surpass the MTU */
+ if (op->pdu_len + op->value_len + 2 > (unsigned) mtu - 1) {
+ op->done = true;
+ goto done;
+ }
+
+ /* Encode the current value */
+ put_le16(handle, op->pdu + op->pdu_len);
+ memcpy(op->pdu + op->pdu_len + 2, value, op->value_len);
+
+ op->pdu_len += op->value_len + 2;
+
+ if (op->pdu_len == (unsigned) mtu - 1)
+ op->done = true;
+
+done:
+ process_read_by_type(op);
+}
+
+static void process_read_by_type(struct async_read_op *op)
+{
+ struct bt_gatt_server *server = op->server;
+ uint8_t rsp_opcode;
+ uint8_t rsp_len;
+ uint8_t ecode;
+ uint16_t ehandle;
+ struct gatt_db_attribute *attr;
+ uint32_t perm;
+
+ attr = queue_pop_head(op->db_data);
+
+ if (op->done || !attr) {
+ rsp_opcode = BT_ATT_OP_READ_BY_TYPE_RSP;
+ rsp_len = op->pdu_len;
+ goto done;
+ }
+
+ if (!gatt_db_attribute_get_permissions(attr, &perm)) {
+ ecode = BT_ATT_ERROR_UNLIKELY;
+ goto error;
+ }
+
+ /*
+ * Check for the READ access permission. Encryption,
+ * authentication, and authorization permissions need to be
+ * checked by the read handler, since bt_att is agnostic to
+ * connection type and doesn't have security information on it.
+ */
+ if (perm && !(perm & BT_ATT_PERM_READ)) {
+ ecode = BT_ATT_ERROR_READ_NOT_PERMITTED;
+ goto error;
+ }
+
+ if (gatt_db_attribute_read(attr, 0, op->opcode, NULL,
+ read_by_type_read_complete_cb, op))
+ return;
+
+ ecode = BT_ATT_ERROR_UNLIKELY;
+
+error:
+ ehandle = gatt_db_attribute_get_handle(attr);
+ rsp_opcode = BT_ATT_OP_ERROR_RSP;
+ rsp_len = 4;
+ encode_error_rsp(BT_ATT_OP_READ_BY_TYPE_REQ, ehandle, ecode, op->pdu);
+
+done:
+ bt_att_send(server->att, rsp_opcode, op->pdu, rsp_len, NULL,
+ NULL, NULL);
+ async_read_op_destroy(op);
+}
+
+static void read_by_type_cb(uint8_t opcode, const void *pdu,
+ uint16_t length, void *user_data)
+{
+ struct bt_gatt_server *server = user_data;
+ uint16_t start, end;
+ bt_uuid_t type;
+ uint8_t rsp_pdu[4];
+ uint16_t ehandle = 0;
+ uint8_t ecode;
+ struct queue *q = NULL;
+ struct async_read_op *op;
+
+ if (length != 6 && length != 20) {
+ ecode = BT_ATT_ERROR_INVALID_PDU;
+ goto error;
+ }
+
+ q = queue_new();
+ if (!q) {
+ ecode = BT_ATT_ERROR_INSUFFICIENT_RESOURCES;
+ goto error;
+ }
+
+ start = get_le16(pdu);
+ end = get_le16(pdu + 2);
+ get_uuid_le(pdu + 4, length - 4, &type);
+
+ util_debug(server->debug_callback, server->debug_data,
+ "Read By Type - start: 0x%04x end: 0x%04x",
+ start, end);
+
+ if (!start || !end) {
+ ecode = BT_ATT_ERROR_INVALID_HANDLE;
+ goto error;
+ }
+
+ ehandle = start;
+
+ if (start > end) {
+ ecode = BT_ATT_ERROR_INVALID_HANDLE;
+ goto error;
+ }
+
+ gatt_db_read_by_type(server->db, start, end, type, q);
+
+ if (queue_isempty(q)) {
+ ecode = BT_ATT_ERROR_ATTRIBUTE_NOT_FOUND;
+ goto error;
+ }
+
+ if (server->pending_read_op) {
+ ecode = BT_ATT_ERROR_UNLIKELY;
+ goto error;
+ }
+
+ op = new0(struct async_read_op, 1);
+ if (!op) {
+ ecode = BT_ATT_ERROR_INSUFFICIENT_RESOURCES;
+ goto error;
+ }
+
+ op->pdu = malloc(bt_att_get_mtu(server->att));
+ if (!op->pdu) {
+ free(op);
+ ecode = BT_ATT_ERROR_INSUFFICIENT_RESOURCES;
+ goto error;
+ }
+
+ op->opcode = opcode;
+ op->server = server;
+ op->db_data = q;
+ server->pending_read_op = op;
+
+ process_read_by_type(op);
+
+ return;
+
+error:
+ encode_error_rsp(opcode, ehandle, ecode, rsp_pdu);
+ queue_destroy(q, NULL);
+ bt_att_send(server->att, BT_ATT_OP_ERROR_RSP, rsp_pdu, 4,
+ NULL, NULL, NULL);
+}
+
static void exchange_mtu_cb(uint8_t opcode, const void *pdu,
uint16_t length, void *user_data)
{
@@ -296,6 +528,14 @@ static bool gatt_server_register_att_handlers(struct bt_gatt_server *server)
if (!server->read_by_grp_type_id)
return false;
+ /* Read By Type */
+ server->read_by_type_id = bt_att_register(server->att,
+ BT_ATT_OP_READ_BY_TYPE_REQ,
+ read_by_type_cb,
+ server, NULL);
+ if (!server->read_by_type_id)
+ return false;
+
return true;
}
--
2.1.0.rc2.206.gedb03e5
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