text: /** @file
   *  @brief Service Discovery Protocol handling.
   */
  
  /*
   * Copyright (c) 2016 Intel Corporation
   *
   * SPDX-License-Identifier: Apache-2.0
   */
  #ifndef __BT_SDP_H
  #define __BT_SDP_H
  
  /**
   * @brief Service Discovery Protocol (SDP)
   * @defgroup bt_sdp Service Discovery Protocol (SDP)
   * @ingroup bluetooth
   * @{
   */
  
  #ifdef __cplusplus
  extern "C" {
  #endif
  
  #include <bluetooth/uuid.h>
  #include <bluetooth/conn.h>
  
  /*
   * All definitions are based on Bluetooth Assigned Numbers
   * of the Bluetooth Specification
   */
  
  /*
   * Service class identifiers of standard services and service groups
   */
  #define BT_SDP_SDP_SERVER_SVCLASS           0x1000
  #define BT_SDP_BROWSE_GRP_DESC_SVCLASS      0x1001
  #define BT_SDP_PUBLIC_BROWSE_GROUP          0x1002
  #define BT_SDP_SERIAL_PORT_SVCLASS          0x1101
  #define BT_SDP_LAN_ACCESS_SVCLASS           0x1102
  #define BT_SDP_DIALUP_NET_SVCLASS           0x1103
  #define BT_SDP_IRMC_SYNC_SVCLASS            0x1104
  #define BT_SDP_OBEX_OBJPUSH_SVCLASS         0x1105
  #define BT_SDP_OBEX_FILETRANS_SVCLASS       0x1106
  #define BT_SDP_IRMC_SYNC_CMD_SVCLASS        0x1107
  #define BT_SDP_HEADSET_SVCLASS              0x1108
  #define BT_SDP_CORDLESS_TELEPHONY_SVCLASS   0x1109
  #define BT_SDP_AUDIO_SOURCE_SVCLASS         0x110a
  #define BT_SDP_AUDIO_SINK_SVCLASS           0x110b
  #define BT_SDP_AV_REMOTE_TARGET_SVCLASS     0x110c
  #define BT_SDP_ADVANCED_AUDIO_SVCLASS       0x110d
  #define BT_SDP_AV_REMOTE_SVCLASS            0x110e
  #define BT_SDP_AV_REMOTE_CONTROLLER_SVCLASS 0x110f
  #define BT_SDP_INTERCOM_SVCLASS             0x1110
  #define BT_SDP_FAX_SVCLASS                  0x1111
  #define BT_SDP_HEADSET_AGW_SVCLASS          0x1112
  #define BT_SDP_WAP_SVCLASS                  0x1113
  #define BT_SDP_WAP_CLIENT_SVCLASS           0x1114
  #define BT_SDP_PANU_SVCLASS                 0x1115
  #define BT_SDP_NAP_SVCLASS                  0x1116
  #define BT_SDP_GN_SVCLASS                   0x1117
  #define BT_SDP_DIRECT_PRINTING_SVCLASS      0x1118
  #define BT_SDP_REFERENCE_PRINTING_SVCLASS   0x1119
  #define BT_SDP_IMAGING_SVCLASS              0x111a
  #define BT_SDP_IMAGING_RESPONDER_SVCLASS    0x111b
  #define BT_SDP_IMAGING_ARCHIVE_SVCLASS      0x111c
  #define BT_SDP_IMAGING_REFOBJS_SVCLASS      0x111d
  #define BT_SDP_HANDSFREE_SVCLASS            0x111e
  #define BT_SDP_HANDSFREE_AGW_SVCLASS        0x111f
  #define BT_SDP_DIRECT_PRT_REFOBJS_SVCLASS   0x1120
  #define BT_SDP_REFLECTED_UI_SVCLASS         0x1121
  #define BT_SDP_BASIC_PRINTING_SVCLASS       0x1122
  #define BT_SDP_PRINTING_STATUS_SVCLASS      0x1123
  #define BT_SDP_HID_SVCLASS                  0x1124
  #define BT_SDP_HCR_SVCLASS                  0x1125
  #define BT_SDP_HCR_PRINT_SVCLASS            0x1126
  #define BT_SDP_HCR_SCAN_SVCLASS             0x1127
  #define BT_SDP_CIP_SVCLASS                  0x1128
  #define BT_SDP_VIDEO_CONF_GW_SVCLASS        0x1129
  #define BT_SDP_UDI_MT_SVCLASS               0x112a
  #define BT_SDP_UDI_TA_SVCLASS               0x112b
  #define BT_SDP_AV_SVCLASS                   0x112c
  #define BT_SDP_SAP_SVCLASS                  0x112d
  #define BT_SDP_PBAP_PCE_SVCLASS             0x112e
  #define BT_SDP_PBAP_PSE_SVCLASS             0x112f
  #define BT_SDP_PBAP_SVCLASS                 0x1130
  #define BT_SDP_MAP_MSE_SVCLASS              0x1132
  #define BT_SDP_MAP_MCE_SVCLASS              0x1133
  #define BT_SDP_MAP_SVCLASS                  0x1134
  #define BT_SDP_GNSS_SVCLASS                 0x1135
  #define BT_SDP_GNSS_SERVER_SVCLASS          0x1136
  #define BT_SDP_MPS_SC_SVCLASS               0x113a
  #define BT_SDP_MPS_SVCLASS                  0x113b
  #define BT_SDP_PNP_INFO_SVCLASS             0x1200
  #define BT_SDP_GENERIC_NETWORKING_SVCLASS   0x1201
  #define BT_SDP_GENERIC_FILETRANS_SVCLASS    0x1202
  #define BT_SDP_GENERIC_AUDIO_SVCLASS        0x1203
  #define BT_SDP_GENERIC_TELEPHONY_SVCLASS    0x1204
  #define BT_SDP_UPNP_SVCLASS                 0x1205
  #define BT_SDP_UPNP_IP_SVCLASS              0x1206
  #define BT_SDP_UPNP_PAN_SVCLASS             0x1300
  #define BT_SDP_UPNP_LAP_SVCLASS             0x1301
  #define BT_SDP_UPNP_L2CAP_SVCLASS           0x1302
  #define BT_SDP_VIDEO_SOURCE_SVCLASS         0x1303
  #define BT_SDP_VIDEO_SINK_SVCLASS           0x1304
  #define BT_SDP_VIDEO_DISTRIBUTION_SVCLASS   0x1305
  #define BT_SDP_HDP_SVCLASS                  0x1400
  #define BT_SDP_HDP_SOURCE_SVCLASS           0x1401
  #define BT_SDP_HDP_SINK_SVCLASS             0x1402
  #define BT_SDP_GENERIC_ACCESS_SVCLASS       0x1800
  #define BT_SDP_GENERIC_ATTRIB_SVCLASS       0x1801
  #define BT_SDP_APPLE_AGENT_SVCLASS          0x2112
  
  /*
   * Attribute identifier codes
   */
  #define BT_SDP_SERVER_RECORD_HANDLE 0x0000
  
  /*
   * Possible values for attribute-id are listed below.
   * See SDP Spec, section "Service Attribute Definitions" for more details.
   */
  #define BT_SDP_ATTR_RECORD_HANDLE               0x0000
  #define BT_SDP_ATTR_SVCLASS_ID_LIST             0x0001
  #define BT_SDP_ATTR_RECORD_STATE                0x0002
  #define BT_SDP_ATTR_SERVICE_ID                  0x0003
  #define BT_SDP_ATTR_PROTO_DESC_LIST             0x0004
  #define BT_SDP_ATTR_BROWSE_GRP_LIST             0x0005
  #define BT_SDP_ATTR_LANG_BASE_ATTR_ID_LIST      0x0006
  #define BT_SDP_ATTR_SVCINFO_TTL                 0x0007
  #define BT_SDP_ATTR_SERVICE_AVAILABILITY        0x0008
  #define BT_SDP_ATTR_PROFILE_DESC_LIST           0x0009
  #define BT_SDP_ATTR_DOC_URL                     0x000a
  #define BT_SDP_ATTR_CLNT_EXEC_URL               0x000b
  #define BT_SDP_ATTR_ICON_URL                    0x000c
  #define BT_SDP_ATTR_ADD_PROTO_DESC_LIST         0x000d
  
  #define BT_SDP_ATTR_GROUP_ID                    0x0200
  #define BT_SDP_ATTR_IP_SUBNET                   0x0200
  #define BT_SDP_ATTR_VERSION_NUM_LIST            0x0200
  #define BT_SDP_ATTR_SUPPORTED_FEATURES_LIST     0x0200
  #define BT_SDP_ATTR_GOEP_L2CAP_PSM              0x0200
  #define BT_SDP_ATTR_SVCDB_STATE                 0x0201
  
  #define BT_SDP_ATTR_MPSD_SCENARIOS              0x0200
  #define BT_SDP_ATTR_MPMD_SCENARIOS              0x0201
  #define BT_SDP_ATTR_MPS_DEPENDENCIES            0x0202
  
  #define BT_SDP_ATTR_SERVICE_VERSION             0x0300
  #define BT_SDP_ATTR_EXTERNAL_NETWORK            0x0301
  #define BT_SDP_ATTR_SUPPORTED_DATA_STORES_LIST  0x0301
  #define BT_SDP_ATTR_DATA_EXCHANGE_SPEC          0x0301
  #define BT_SDP_ATTR_NETWORK                     0x0301
  #define BT_SDP_ATTR_FAX_CLASS1_SUPPORT          0x0302
  #define BT_SDP_ATTR_REMOTE_AUDIO_VOLUME_CONTROL 0x0302
  #define BT_SDP_ATTR_MCAP_SUPPORTED_PROCEDURES   0x0302
  #define BT_SDP_ATTR_FAX_CLASS20_SUPPORT         0x0303
  #define BT_SDP_ATTR_SUPPORTED_FORMATS_LIST      0x0303
  #define BT_SDP_ATTR_FAX_CLASS2_SUPPORT          0x0304
  #define BT_SDP_ATTR_AUDIO_FEEDBACK_SUPPORT      0x0305
  #define BT_SDP_ATTR_NETWORK_ADDRESS             0x0306
  #define BT_SDP_ATTR_WAP_GATEWAY                 0x0307
  #define BT_SDP_ATTR_HOMEPAGE_URL                0x0308
  #define BT_SDP_ATTR_WAP_STACK_TYPE              0x0309
  #define BT_SDP_ATTR_SECURITY_DESC               0x030a
  #define BT_SDP_ATTR_NET_ACCESS_TYPE             0x030b
  #define BT_SDP_ATTR_MAX_NET_ACCESSRATE          0x030c
  #define BT_SDP_ATTR_IP4_SUBNET                  0x030d
  #define BT_SDP_ATTR_IP6_SUBNET                  0x030e
  #define BT_SDP_ATTR_SUPPORTED_CAPABILITIES      0x0310
  #define BT_SDP_ATTR_SUPPORTED_FEATURES          0x0311
  #define BT_SDP_ATTR_SUPPORTED_FUNCTIONS         0x0312
  #define BT_SDP_ATTR_TOTAL_IMAGING_DATA_CAPACITY 0x0313
  #define BT_SDP_ATTR_SUPPORTED_REPOSITORIES      0x0314
  #define BT_SDP_ATTR_MAS_INSTANCE_ID             0x0315
  #define BT_SDP_ATTR_SUPPORTED_MESSAGE_TYPES     0x0316
  #define BT_SDP_ATTR_PBAP_SUPPORTED_FEATURES     0x0317
  #define BT_SDP_ATTR_MAP_SUPPORTED_FEATURES      0x0317
  
  #define BT_SDP_ATTR_SPECIFICATION_ID            0x0200
  #define BT_SDP_ATTR_VENDOR_ID                   0x0201
  #define BT_SDP_ATTR_PRODUCT_ID                  0x0202
  #define BT_SDP_ATTR_VERSION                     0x0203
  #define BT_SDP_ATTR_PRIMARY_RECORD              0x0204
  #define BT_SDP_ATTR_VENDOR_ID_SOURCE            0x0205
  
  #define BT_SDP_ATTR_HID_DEVICE_RELEASE_NUMBER   0x0200
  #define BT_SDP_ATTR_HID_PARSER_VERSION          0x0201
  #define BT_SDP_ATTR_HID_DEVICE_SUBCLASS         0x0202
  #define BT_SDP_ATTR_HID_COUNTRY_CODE            0x0203
  #define BT_SDP_ATTR_HID_VIRTUAL_CABLE           0x0204
  #define BT_SDP_ATTR_HID_RECONNECT_INITIATE      0x0205
  #define BT_SDP_ATTR_HID_DESCRIPTOR_LIST         0x0206
  #define BT_SDP_ATTR_HID_LANG_ID_BASE_LIST       0x0207
  #define BT_SDP_ATTR_HID_SDP_DISABLE             0x0208
  #define BT_SDP_ATTR_HID_BATTERY_POWER           0x0209
  #define BT_SDP_ATTR_HID_REMOTE_WAKEUP           0x020a
  #define BT_SDP_ATTR_HID_PROFILE_VERSION         0x020b
  #define BT_SDP_ATTR_HID_SUPERVISION_TIMEOUT     0x020c
  #define BT_SDP_ATTR_HID_NORMALLY_CONNECTABLE    0x020d
  #define BT_SDP_ATTR_HID_BOOT_DEVICE             0x020e
  
  /*
   * These identifiers are based on the SDP spec stating that
   * "base attribute id of the primary (universal) language must be 0x0100"
   *
   * Other languages should have their own offset; e.g.:
   * #define XXXLangBase yyyy
   * #define AttrServiceName_XXX 0x0000+XXXLangBase
   */
  #define BT_SDP_PRIMARY_LANG_BASE  0x0100
  
  #define BT_SDP_ATTR_SVCNAME_PRIMARY (0x0000 + BT_SDP_PRIMARY_LANG_BASE)
  #define BT_SDP_ATTR_SVCDESC_PRIMARY (0x0001 + BT_SDP_PRIMARY_LANG_BASE)
  #define BT_SDP_ATTR_PROVNAME_PRIMARY (0x0002 + BT_SDP_PRIMARY_LANG_BASE)
  
  /*
   * The Data representation in SDP PDUs (pps 339, 340 of BT SDP Spec)
   * These are the exact data type+size descriptor values
   * that go into the PDU buffer.
   *
   * The datatype (leading 5bits) + size descriptor (last 3 bits)
   * is 8 bits. The size descriptor is critical to extract the
   * right number of bytes for the data value from the PDU.
   *
   * For most basic types, the datatype+size descriptor is
   * straightforward. However for constructed types and strings,
   * the size of the data is in the next "n" bytes following the
   * 8 bits (datatype+size) descriptor. Exactly what the "n" is
   * specified in the 3 bits of the data size descriptor.
   *
   * TextString and URLString can be of size 2^{8, 16, 32} bytes
   * DataSequence and DataSequenceAlternates can be of size 2^{8, 16, 32}
   * The size are computed post-facto in the API and are not known apriori
   */
  #define BT_SDP_DATA_NIL        0x00
  #define BT_SDP_UINT8           0x08
  #define BT_SDP_UINT16          0x09
  #define BT_SDP_UINT32          0x0a
  #define BT_SDP_UINT64          0x0b
  #define BT_SDP_UINT128         0x0c
  #define BT_SDP_INT8            0x10
  #define BT_SDP_INT16           0x11
  #define BT_SDP_INT32           0x12
  #define BT_SDP_INT64           0x13
  #define BT_SDP_INT128          0x14
  #define BT_SDP_UUID_UNSPEC     0x18
  #define BT_SDP_UUID16          0x19
  #define BT_SDP_UUID32          0x1a
  #define BT_SDP_UUID128         0x1c
  #define BT_SDP_TEXT_STR_UNSPEC 0x20
  #define BT_SDP_TEXT_STR8       0x25
  #define BT_SDP_TEXT_STR16      0x26
  #define BT_SDP_TEXT_STR32      0x27
  #define BT_SDP_BOOL            0x28
  #define BT_SDP_SEQ_UNSPEC      0x30
  #define BT_SDP_SEQ8            0x35
  #define BT_SDP_SEQ16           0x36
  #define BT_SDP_SEQ32           0x37
  #define BT_SDP_ALT_UNSPEC      0x38
  #define BT_SDP_ALT8            0x3d
  #define BT_SDP_ALT16           0x3e
  #define BT_SDP_ALT32           0x3f
  #define BT_SDP_URL_STR_UNSPEC  0x40
  #define BT_SDP_URL_STR8        0x45
  #define BT_SDP_URL_STR16       0x46
  #define BT_SDP_URL_STR32       0x47
  
  #define BT_SDP_TYPE_DESC_MASK 0xf8
  #define BT_SDP_SIZE_DESC_MASK 0x07
  #define BT_SDP_SIZE_INDEX_OFFSET 5
  
  /** @brief SDP Generic Data Element Value. */
  struct bt_sdp_data_elem {
  	u8_t        type;
  	u32_t       data_size;
  	u32_t       total_size;
  	const void *data;
  };
  
  /** @brief SDP Attribute Value. */
  struct bt_sdp_attribute {
  	u16_t                id;  /* Attribute ID */
  	struct bt_sdp_data_elem val; /* Attribute data */
  };
  
  /** @brief SDP Service Record Value. */
  struct bt_sdp_record {
  	u32_t                    handle;     /* Redundant, for quick ref */
  	struct bt_sdp_attribute *attrs;      /* Base addr of attr array */
  	size_t                   attr_count; /* Number of attributes */
  	u8_t                     index;      /* Index of the record in LL */
  	struct bt_sdp_record    *next;
  };
  
  /*
   * ---------------------------------------------------    ------------------
   * | Service Hdl | Attr list ptr | Attr count | Next | -> | Service Hdl | ...
   * ---------------------------------------------------    ------------------
   */
  
  /** @def BT_SDP_ARRAY_8
   *  @brief Declare an array of 8-bit elements in an attribute.
   */
  #define BT_SDP_ARRAY_8(...) ((u8_t[]) {__VA_ARGS__})
  
  /** @def BT_SDP_ARRAY_16
   *  @brief Declare an array of 16-bit elements in an attribute.
   */
  #define BT_SDP_ARRAY_16(...) ((u16_t[]) {__VA_ARGS__})
  
  /** @def BT_SDP_ARRAY_32
   *  @brief Declare an array of 32-bit elements in an attribute.
   */
  #define BT_SDP_ARRAY_32(...) ((u32_t[]) {__VA_ARGS__})
  
  /** @def BT_SDP_TYPE_SIZE
   *  @brief Declare a fixed-size data element header.
   *
   *  @param _type Data element header containing type and size descriptors.
   */
  #define BT_SDP_TYPE_SIZE(_type) .type = _type, \
  			.data_size = BIT(_type & BT_SDP_SIZE_DESC_MASK), \
  			.total_size = BIT(_type & BT_SDP_SIZE_DESC_MASK) + 1
  
  /** @def BT_SDP_TYPE_SIZE_VAR
   *  @brief Declare a variable-size data element header.
   *
   *  @param _type Data element header containing type and size descriptors.
   *  @param _size The actual size of the data.
   */
  #define BT_SDP_TYPE_SIZE_VAR(_type, _size) .type = _type, \
  			.data_size = _size, \
  			.total_size = BIT((_type & BT_SDP_SIZE_DESC_MASK) - \
  					  BT_SDP_SIZE_INDEX_OFFSET) + _size + 1
  
  /** @def BT_SDP_DATA_ELEM_LIST
   *  @brief Declare a list of data elements.
   */
  #define BT_SDP_DATA_ELEM_LIST(...) ((struct bt_sdp_data_elem[]) {__VA_ARGS__})
  
  
  /** @def BT_SDP_NEW_SERVICE
   *  @brief SDP New Service Record Declaration Macro.
   *
   *  Helper macro to declare a new service record.
   *  Default attributes: Record Handle, Record State,
   *  Language Base, Root Browse Group
   *
   */
  #define BT_SDP_NEW_SERVICE \
  { \
  	BT_SDP_ATTR_RECORD_HANDLE, \
  	{ BT_SDP_TYPE_SIZE(BT_SDP_UINT32), BT_SDP_ARRAY_32(0) } \
  }, \
  { \
  	BT_SDP_ATTR_RECORD_STATE, \
  	{ BT_SDP_TYPE_SIZE(BT_SDP_UINT32), BT_SDP_ARRAY_32(0) } \
  }, \
  { \
  	BT_SDP_ATTR_LANG_BASE_ATTR_ID_LIST, \
  	{ BT_SDP_TYPE_SIZE_VAR(BT_SDP_SEQ8, 9), \
  	  BT_SDP_DATA_ELEM_LIST( \
  		{ BT_SDP_TYPE_SIZE(BT_SDP_UINT16), BT_SDP_ARRAY_8('n', 'e') }, \
  		{ BT_SDP_TYPE_SIZE(BT_SDP_UINT16), BT_SDP_ARRAY_16(106) }, \
  		{ BT_SDP_TYPE_SIZE(BT_SDP_UINT16), \
  			BT_SDP_ARRAY_16(BT_SDP_PRIMARY_LANG_BASE) } \
  	  ), \
  	} \
  }, \
  { \
  	BT_SDP_ATTR_BROWSE_GRP_LIST, \
  	{ BT_SDP_TYPE_SIZE_VAR(BT_SDP_SEQ8, 3), \
  	  BT_SDP_DATA_ELEM_LIST( \
  		{ BT_SDP_TYPE_SIZE(BT_SDP_UUID16), \
  			BT_SDP_ARRAY_16(BT_SDP_PUBLIC_BROWSE_GROUP) }, \
  	  ), \
  	} \
  }
  
  
  /** @def BT_SDP_LIST
   *  @brief Generic SDP List Attribute Declaration Macro.
   *
   *  Helper macro to declare a list attribute.
   *
   *  @param _att_id List Attribute ID.
   *  @param _data_elem_seq Data element sequence for the list.
   *  @param _type_size SDP type and size descriptor.
   */
  #define BT_SDP_LIST(_att_id, _type_size, _data_elem_seq) \
  { \
  	_att_id, { _type_size, _data_elem_seq } \
  }
  
  /** @def BT_SDP_SERVICE_ID
   *  @brief SDP Service ID Attribute Declaration Macro.
   *
   *  Helper macro to declare a service ID attribute.
   *
   *  @param _uuid Service ID 16bit UUID.
   */
  #define BT_SDP_SERVICE_ID(_uuid) \
  { \
  	BT_SDP_ATTR_SERVICE_ID, \
  	{ BT_SDP_TYPE_SIZE(BT_SDP_UUID16), &((struct bt_uuid_16) _uuid) } \
  }
  
  /** @def BT_SDP_SERVICE_NAME
   *  @brief SDP Name Attribute Declaration Macro.
   *
   *  Helper macro to declare a service name attribute.
   *
   *  @param _name Service name as a string (up to 256 chars).
   */
  #define BT_SDP_SERVICE_NAME(_name) \
  { \
  	BT_SDP_ATTR_SVCNAME_PRIMARY, \
  	{ BT_SDP_TYPE_SIZE_VAR(BT_SDP_TEXT_STR8, (sizeof(_name)-1)), _name } \
  }
  
  /** @def BT_SDP_SUPPORTED_FEATURES
   *  @brief SDP Supported Features Attribute Declaration Macro.
   *
   *  Helper macro to declare supported features of a profile/protocol.
   *
   *  @param _features Feature mask as 16bit unsigned integer.
   */
  #define BT_SDP_SUPPORTED_FEATURES(_features) \
  { \
  	BT_SDP_ATTR_SUPPORTED_FEATURES, \
  	{ BT_SDP_TYPE_SIZE(BT_SDP_UINT16), BT_SDP_ARRAY_16(_features) } \
  }
  
  /** @def BT_SDP_RECORD
   *  @brief SDP Service Declaration Macro.
   *
   *  Helper macro to declare a service.
   *
   *  @param _attrs List of attributes for the service record.
   */
  #define BT_SDP_RECORD(_attrs) \
  { \
  	.attrs = _attrs, \
  	.attr_count = ARRAY_SIZE((_attrs)), \
  }
  
  /* Server API */
  
  /** @brief Register a Service Record.
   *
   *  Register a Service Record. Applications can make use of
   *  macros such as BT_SDP_DECLARE_SERVICE, BT_SDP_LIST,
   *  BT_SDP_SERVICE_ID, BT_SDP_SERVICE_NAME, etc.
   *  A service declaration must start with BT_SDP_NEW_SERVICE.
   *
   *  @param service Service record declared using BT_SDP_DECLARE_SERVICE.
   *
   * @return 0 in case of success or negative value in case of error.
   */
  int bt_sdp_register_service(struct bt_sdp_record *service);
  
  /* Client API */
  
  /** @brief Generic SDP Client Query Result data holder */
  struct bt_sdp_client_result {
  	/* buffer containing unparsed SDP record result for given UUID */
  	struct net_buf        *resp_buf;
  	/* flag pointing that there are more result chunks for given UUID */
  	bool                   next_record_hint;
  	/* Reference to UUID object on behalf one discovery was started */
  	const struct bt_uuid  *uuid;
  };
  
  /** @brief Helper enum to be used as return value of bt_sdp_discover_func_t.
   *  The value informs the caller to perform futher pending actions or stop them.
   */
  enum {
  	BT_SDP_DISCOVER_UUID_STOP = 0,
  	BT_SDP_DISCOVER_UUID_CONTINUE,
  };
  
  /** @typedef bt_sdp_discover_func_t
   *
   *  @brief Callback type reporting to user that there is a resolved result
   *  on remote for given UUID and the result record buffer can be used by user
   *  for futher inspection.
   *
   *  A function of this type is given by the user to the bt_sdp_discover_params
   *  object. It'll be called on each valid record discovery completion for given
   *  UUID. When UUID resolution gives back no records then NULL is passed
   *  to the user. Otherwise user can get valid record(s) and then the internal
   *  hint 'next record' is set to false saying the UUID resolution is complete or
   *  the hint can be set by caller to true meaning that next record is available
   *  for given UUID.
   *  The returned function value allows the user to control retrieving follow-up
   *  resolved records if any. If the user doesn't want to read more resolved
   *  records for given UUID since current record data fulfills its requirements
   *  then should return BT_SDP_DISCOVER_UUID_STOP. Otherwise returned value means
   *  more subcall iterations are allowable.
   *
   *  @param conn Connection object identifying connection to queried remote.
   *  @param result Object pointing to logical unparsed SDP record collected on
   *  base of response driven by given UUID.
   *
   *  @return BT_SDP_DISCOVER_UUID_STOP in case of no more need to read next
   *  record data and continue discovery for given UUID. By returning
   *  BT_SDP_DISCOVER_UUID_CONTINUE user allows this discovery continuation.
   */
  typedef u8_t (*bt_sdp_discover_func_t)
  		(struct bt_conn *conn, struct bt_sdp_client_result *result);
  
  /** @brief Main user structure used in SDP discovery of remote. */
  struct bt_sdp_discover_params {
  	sys_snode_t		_node;
  	/** UUID (service) to be discovered on remote SDP entity */
  	const struct bt_uuid   *uuid;
  	/** Discover callback to be called on resolved SDP record */
  	bt_sdp_discover_func_t  func;
  	/** Memory buffer enabled by user for SDP query results  */
  	struct net_buf_pool    *pool;
  };
  
  /** @brief Allows user to start SDP discovery session.
   *
   *  The function performs SDP service discovery on remote server driven by user
   *  delivered discovery parameters. Discovery session is made as soon as
   *  no SDP transaction is ongoing between peers and if any then this one
   *  is queued to be processed at discovery completion of previous one.
   *  On the service discovery completion the callback function will be
   *  called to get feedback to user about findings.
   *
   * @param conn Object identifying connection to remote.
   * @param params SDP discovery parameters.
   *
   * @return 0 in case of success or negative value in case of error.
   */
  
  int bt_sdp_discover(struct bt_conn *conn,
  		    const struct bt_sdp_discover_params *params);
  
  /** @brief Release waiting SDP discovery request.
   *
   *  It can cancel valid waiting SDP client request identified by SDP discovery
   *  parameters object.
   *
   * @param conn Object identifying connection to remote.
   * @param params SDP discovery parameters.
   *
   * @return 0 in case of success or negative value in case of error.
   */
  int bt_sdp_discover_cancel(struct bt_conn *conn,
  			   const struct bt_sdp_discover_params *params);
  
  
  /* Helper types & functions for SDP client to get essential data from server */
  
  /** @brief Protocols to be asked about specific parameters */
  enum bt_sdp_proto {
  	BT_SDP_PROTO_RFCOMM = BT_UUID_RFCOMM_VAL,
  	BT_SDP_PROTO_L2CAP  = BT_UUID_L2CAP_VAL,
  };
  
  /** @brief Give to user parameter value related to given stacked protocol UUID.
   *
   *  API extracts specific parameter associated with given protocol UUID
   *  available in Protocol Descriptor List attribute.
   *
   *  @param buf Original buffered raw record data.
   *  @param proto Known protocol to be checked like RFCOMM or L2CAP.
   *  @param param On success populated by found parameter value.
   *
   *  @return 0 on success when specific parameter associated with given protocol
   *  value is found, or negative if error occurred during processing.
   */
  int bt_sdp_get_proto_param(const struct net_buf *buf, enum bt_sdp_proto proto,
  			   u16_t *param);
  
  /** @brief Get profile version.
   *
   *  Helper API extracting remote profile version number. To get it proper
   *  generic profile parameter needs to be selected usually listed in SDP
   *  Interoperability Requirements section for given profile specification.
   *
   *  @param buf Original buffered raw record data.
   *  @param profile Profile family identifier the profile belongs.
   *  @param version On success populated by found version number.
   *
   *  @return 0 on success, negative value if error occurred during processing.
   */
  int bt_sdp_get_profile_version(const struct net_buf *buf, u16_t profile,
  			       u16_t *version);
  
  /** @brief Get SupportedFeatures attribute value
   *
   *  Allows if exposed by remote retrieve SupportedFeature attribute.
   *
   *  @param buf Buffer holding original raw record data from remote.
   *  @param features On success object to be populated with SupportedFeature
   *  mask.
   *
   *  @return 0 on success if feature found and valid, negative in case any error
   */
  int bt_sdp_get_features(const struct net_buf *buf, u16_t *features);
  #ifdef __cplusplus
  }
  #endif
  
  /**
   * @}
   */
  
  #endif /* __BT_SDP_H */
  