xref: /btstack/src/classic/sdp_util.c (revision c1ab6cc1beb14b16b46e74a3723644016d8c3cc7)

/*
 * Copyright (C) 2014 BlueKitchen GmbH
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the copyright holders nor the names of
 *    contributors may be used to endorse or promote products derived
 *    from this software without specific prior written permission.
 * 4. Any redistribution, use, or modification is done solely for
 *    personal benefit and not for any commercial purpose or for
 *    monetary gain.
 *
 * THIS SOFTWARE IS PROVIDED BY BLUEKITCHEN GMBH AND CONTRIBUTORS
 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL MATTHIAS
 * RINGWALD OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
 * THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 * Please inquire about commercial licensing options at
 * [email protected]
 *
 */

#define BTSTACK_FILE__ "sdp_util.c"

/*
 *  sdp_util.c
 */

#include "bluetooth.h"
#include "btstack_config.h"
#include "btstack_util.h"
#include "classic/core.h"
#include "classic/sdp_util.h"

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdint.h>
#include <inttypes.h>   // PRIx32

#ifdef ENABLE_SDP_DES_DUMP
// workaround for missing PRIx32 on mspgcc (16-bit MCU)
#ifndef PRIx32
#warning Using own: #define PRIx32 "lx"
#define PRIx32 "lx"
#endif
// date element type names
const char * const type_names[] = { "NIL", "UINT", "INT", "UUID", "STRING", "BOOL", "DES", "DEA", "URL"};
#endif

static uint8_t des_serviceSearchPatternUUID16[]  = {0x35, 0x03, 0x19, 0x00, 0x00};
static uint8_t des_serviceSearchPatternUUID128[] = {
    0x35, 0x11, 0x1c,
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00};

// MARK: DataElement getter
de_size_t de_get_size_type(const uint8_t *header){
    return (de_size_t) (header[0] & 7);
}

de_type_t de_get_element_type(const uint8_t *header){
    return (de_type_t) (header[0] >> 3);
}

uint32_t de_get_header_size(const uint8_t * header){
    de_size_t de_size = de_get_size_type(header);
    if (de_size <= DE_SIZE_128) {
        return 1;
    }
    return 1 + (1 << (de_size-DE_SIZE_VAR_8));
}

uint32_t de_get_data_size(const uint8_t * header){
    uint32_t result = 0;
    de_type_t de_type = de_get_element_type(header);
    de_size_t de_size = de_get_size_type(header);
    switch (de_size){
        case DE_SIZE_VAR_8:
            result = header[1];
            break;
        case DE_SIZE_VAR_16:
            result = big_endian_read_16(header,1);
            break;
        case DE_SIZE_VAR_32:
            result = big_endian_read_32(header,1);
            break;
        default:
        // case DE_SIZE_8:
        // case DE_SIZE_16:
        // case DE_SIZE_32:
        // case DE_SIZE_64:
        // case DE_SIZE_128:
            if (de_type == DE_NIL) return 0;
            return 1 << de_size;
    }
    return result;
}

int de_get_len(const uint8_t *header){
    return de_get_header_size(header) + de_get_data_size(header);
}

// returns data element length if data element fits in size
uint32_t de_get_len_safe(const uint8_t * header, uint32_t size){
    if (1           > size) return 0;
    uint32_t header_size = de_get_header_size(header);
    if (header_size > size) return 0;
    uint32_t data_size   = de_get_data_size(header);
    if (data_size   > size) return 0;
    uint32_t de_len      = header_size + data_size;
    if (de_len      > size) return 0;
    return de_len;
}

// @returns OK, if UINT16 value was read
int de_element_get_uint16(const uint8_t * element, uint16_t * value){
    if (de_get_size_type(element) != DE_SIZE_16) return 0;
    *value = big_endian_read_16(element, de_get_header_size(element));
    return 1;
}

// @returns: element is valid UUID
int de_get_normalized_uuid(uint8_t *uuid128, const uint8_t *element){
    de_type_t uuidType = de_get_element_type(element);
    de_size_t uuidSize = de_get_size_type(element);
    if (uuidType != DE_UUID) return 0;
    uint32_t shortUUID;
    switch (uuidSize){
        case DE_SIZE_16:
            shortUUID = big_endian_read_16(element, 1);
            break;
        case DE_SIZE_32:
            shortUUID = big_endian_read_32(element, 1);
            break;
        case DE_SIZE_128:
            memcpy(uuid128, element+1, 16);
            return 1;
        default:
            return 0;
    }
    uuid_add_bluetooth_prefix(uuid128, shortUUID);
    return 1;
}

// @returns 0 if no UUID16 or UUID32 is present, and UUID32 otherwise
uint32_t de_get_uuid32(const uint8_t * element){
    uint8_t uuid128[16];
    int validUuid128 = de_get_normalized_uuid(uuid128, element);
    if (!validUuid128) return 0;
    int hasBlueoothBaseUuid = uuid_has_bluetooth_prefix(uuid128);
    if (!hasBlueoothBaseUuid) return 0;
    return big_endian_read_32(uuid128, 0);
}

const uint8_t * de_get_string(const uint8_t * element){
    if (de_get_element_type(element) != DE_STRING) return NULL;
    return &element[de_get_header_size(element)];
}

// functions to create record
static void de_store_descriptor(uint8_t * header, de_type_t type, de_size_t size){
    header[0] = (type << 3) | size;
}

void de_store_descriptor_with_len(uint8_t * header, de_type_t type, de_size_t size, uint32_t len){
    header[0] = (type << 3) | size;
    switch (size){
        case DE_SIZE_VAR_8:
            header[1] = len;
            break;
        case DE_SIZE_VAR_16:
            big_endian_store_16(header, 1, len);
            break;
        case DE_SIZE_VAR_32:
            big_endian_store_32(header, 1, len);
            break;
        default:
            break;
    }
}

// MARK: DataElement creation

/* starts a new sequence in empty buffer - first call */
void de_create_sequence(uint8_t *header){
    de_store_descriptor_with_len( header, DE_DES, DE_SIZE_VAR_16, 0); // DES, 2 Byte Length
};

/* starts a sub-sequence, @returns handle for sub-sequence */
uint8_t * de_push_sequence(uint8_t *header){
    int element_len = de_get_len(header);
    de_store_descriptor_with_len(header+element_len, DE_DES, DE_SIZE_VAR_16, 0); // DES, 2 Byte Length
    return header + element_len;
}

/* closes the current sequence and updates the parent sequence */
void de_pop_sequence(uint8_t * parent, uint8_t * child){
    int child_len = de_get_len(child);
    int data_size_parent = big_endian_read_16(parent,1);
    big_endian_store_16(parent, 1, data_size_parent + child_len);
}

/* adds a single number value and 16+32 bit UUID to the sequence */
void de_add_number(uint8_t *seq, de_type_t type, de_size_t size, uint32_t value){
    int data_size   = big_endian_read_16(seq,1);
    int element_size = 1;   // e.g. for DE_TYPE_NIL
    de_store_descriptor(seq+3+data_size, type, size);
    switch (size){
        case DE_SIZE_8:
            if (type != DE_NIL){
                seq[4+data_size] = value;
                element_size = 2;
            }
            break;
        case DE_SIZE_16:
            big_endian_store_16(seq, 4+data_size, value);
            element_size = 3;
            break;
        case DE_SIZE_32:
            big_endian_store_32(seq, 4+data_size, value);
            element_size = 5;
            break;
        default:
            break;
    }
    big_endian_store_16(seq, 1, data_size+element_size);
}

/* add a single block of data, e.g. as DE_STRING, DE_URL */
void de_add_data( uint8_t *seq, de_type_t type, uint16_t size, uint8_t *data){
    int data_size   = big_endian_read_16(seq,1);
    if (size > 0xff) {
        // use 16-bit lengh information (3 byte header)
        de_store_descriptor_with_len(seq+3+data_size, type, DE_SIZE_VAR_16, size);
        data_size += 3;
    } else {
        // use 8-bit lengh information (2 byte header)
        de_store_descriptor_with_len(seq+3+data_size, type, DE_SIZE_VAR_8, size);
        data_size += 2;
    }
    memcpy( seq + 3 + data_size, data, size);
    data_size += size;
    big_endian_store_16(seq, 1, data_size);
}

void de_add_uuid128(uint8_t * seq, uint8_t * uuid){
    int data_size   = big_endian_read_16(seq,1);
    de_store_descriptor(seq+3+data_size, DE_UUID, DE_SIZE_128);
    memcpy( seq + 4 + data_size, uuid, 16);
    big_endian_store_16(seq, 1, data_size+1+16);
}

// MARK: DES iterator
int des_iterator_init(des_iterator_t * it, uint8_t * element){
    de_type_t type = de_get_element_type(element);
    if (type != DE_DES) return 0;

    it->element = element;
    it->pos = de_get_header_size(element);
    it->length = de_get_len(element);
    // printf("des_iterator_init current pos %d, total len %d\n", it->pos, it->length);
    return 1;
}

de_type_t des_iterator_get_type (des_iterator_t * it){
    return de_get_element_type(&it->element[it->pos]);
}

uint16_t des_iterator_get_size (des_iterator_t * it){
    int length = de_get_len(&it->element[it->pos]);
    int header_size = de_get_header_size(&it->element[it->pos]);
    return length - header_size;
}

int des_iterator_has_more(des_iterator_t * it){
    return it->pos < it->length;
}

uint8_t * des_iterator_get_element(des_iterator_t * it){
    if (!des_iterator_has_more(it)) return NULL;
    return &it->element[it->pos];
}

void des_iterator_next(des_iterator_t * it){
    int element_len = de_get_len(&it->element[it->pos]);
    // printf("des_iterator_next element size %d, current pos %d, total len %d\n", element_len, it->pos, it->length);
    it->pos += element_len;
}

// MARK: DataElementSequence traversal
typedef int (*de_traversal_callback_t)(uint8_t * element, de_type_t type, de_size_t size, void *context);
static void de_traverse_sequence(uint8_t * element, de_traversal_callback_t handler, void *context){
    de_type_t type = de_get_element_type(element);
    if (type != DE_DES) return;
    int pos = de_get_header_size(element);
    int end_pos = de_get_len(element);
    while (pos < end_pos){
        de_type_t elemType = de_get_element_type(element + pos);
        de_size_t elemSize = de_get_size_type(element + pos);
        uint8_t done = (*handler)(element + pos, elemType, elemSize, context);
        if (done) break;
        pos += de_get_len(element + pos);
    }
}

// MARK: AttributeList traversal
typedef int (*sdp_attribute_list_traversal_callback_t)(uint16_t attributeID, uint8_t * attributeValue, de_type_t type, de_size_t size, void *context);
static void sdp_attribute_list_traverse_sequence(uint8_t * element, sdp_attribute_list_traversal_callback_t handler, void *context){
    de_type_t type = de_get_element_type(element);
    if (type != DE_DES) return;
    int pos = de_get_header_size(element);
    int end_pos = de_get_len(element);
    while (pos < end_pos){
        de_type_t idType = de_get_element_type(element + pos);
        de_size_t idSize = de_get_size_type(element + pos);
        if (idType != DE_UINT || idSize != DE_SIZE_16) break; // wrong type
        uint16_t attribute_id = big_endian_read_16(element, pos + 1);
        pos += 3;
        if (pos >= end_pos) break; // array out of bounds
        de_type_t valueType = de_get_element_type(element + pos);
        de_size_t valueSize = de_get_size_type(element + pos);
        uint8_t done = (*handler)(attribute_id, element + pos, valueType, valueSize, context);
        if (done) break;
        pos += de_get_len(element + pos);
    }
}

// MARK: AttributeID in AttributeIDList
// attribute ID in AttributeIDList
// context { result, attributeID }
struct sdp_context_attributeID_search {
    int result;
    uint16_t attributeID;
};
static int sdp_traversal_attributeID_search(uint8_t * element, de_type_t type, de_size_t size, void *my_context){
    struct sdp_context_attributeID_search * context = (struct sdp_context_attributeID_search *) my_context;
    if (type != DE_UINT) return 0;
    switch (size) {
        case DE_SIZE_16:
            if (big_endian_read_16(element, 1) == context->attributeID) {
                context->result = 1;
                return 1;
            }
            break;
        case DE_SIZE_32:
            if (big_endian_read_16(element, 1) <= context->attributeID
            &&  context->attributeID <= big_endian_read_16(element, 3)) {
                context->result = 1;
                return 1;
            }
            break;
        default:
            break;
    }
    return 0;
}

int sdp_attribute_list_constains_id(uint8_t *attributeIDList, uint16_t attributeID){
    struct sdp_context_attributeID_search attributeID_search;
    attributeID_search.result = 0;
    attributeID_search.attributeID = attributeID;
    de_traverse_sequence(attributeIDList, sdp_traversal_attributeID_search, &attributeID_search);
    return attributeID_search.result;
}

// MARK: Append Attributes for AttributeIDList
// pre: buffer contains DES with 2 byte length field
struct sdp_context_append_attributes {
    uint8_t * buffer;
    uint16_t startOffset;     // offset of when to start copying
    uint16_t maxBytes;
    uint16_t usedBytes;
    uint8_t *attributeIDList;
};

static int sdp_traversal_append_attributes(uint16_t attributeID, uint8_t * attributeValue, de_type_t de_type, de_size_t de_size, void *my_context){
    UNUSED(de_type);
    UNUSED(de_size);
    struct sdp_context_append_attributes * context = (struct sdp_context_append_attributes *) my_context;
    if (sdp_attribute_list_constains_id(context->attributeIDList, attributeID)) {
        // DES_HEADER(3) + DES_DATA + (UINT16(3) + attribute)
        uint16_t data_size = big_endian_read_16(context->buffer, 1);
        int attribute_len = de_get_len(attributeValue);
        if ((3 + data_size + (3 + attribute_len)) <= context->maxBytes) {
            // copy Attribute
            de_add_number(context->buffer, DE_UINT, DE_SIZE_16, attributeID);
            data_size += 3; // 3 bytes
            memcpy(context->buffer + 3 + data_size, attributeValue, attribute_len);
            big_endian_store_16(context->buffer,1,data_size+attribute_len);
        } else {
            // not enought space left -> continue with previous element
            return 1;
        }
    }
    return 0;
}

// maxBytes: maximal size of data element sequence
uint16_t sdp_append_attributes_in_attributeIDList(uint8_t *record, uint8_t *attributeIDList, uint16_t startOffset, uint16_t maxBytes, uint8_t *buffer){
    struct sdp_context_append_attributes context;
    context.buffer = buffer;
    context.maxBytes = maxBytes;
    context.usedBytes = 0;
    context.startOffset = startOffset;
    context.attributeIDList = attributeIDList;
    sdp_attribute_list_traverse_sequence(record, sdp_traversal_append_attributes, &context);
    return context.usedBytes;
}

// MARK: Filter attributes that match attribute list from startOffset and a max nr bytes
struct sdp_context_filter_attributes {
    uint8_t * buffer;
    uint16_t startOffset;     // offset of when to start copying
    uint16_t maxBytes;
    uint16_t usedBytes;
    uint8_t *attributeIDList;
    int      complete;
};

// copy data with given start offset and max bytes, returns OK if all data has been copied
static int spd_append_range(struct sdp_context_filter_attributes* context, uint16_t len, uint8_t *data){
    int ok = 1;
    uint16_t remainder_len = len - context->startOffset;
    if (context->maxBytes < remainder_len){
        remainder_len = context->maxBytes;
        ok = 0;
    }
    memcpy(context->buffer, &data[context->startOffset], remainder_len);
    context->usedBytes += remainder_len;
    context->buffer    += remainder_len;
    context->maxBytes  -= remainder_len;
    context->startOffset = 0;
    return ok;
}

static int sdp_traversal_filter_attributes(uint16_t attributeID, uint8_t * attributeValue, de_type_t de_type, de_size_t de_size, void *my_context){
    UNUSED(de_type);
    UNUSED(de_size);

    struct sdp_context_filter_attributes * context = (struct sdp_context_filter_attributes *) my_context;

    if (!sdp_attribute_list_constains_id(context->attributeIDList, attributeID)) return 0;

    // { Attribute ID (Descriptor, big endian 16-bit ID), AttributeValue (data)}

    // handle Attribute ID
    if (context->startOffset >= 3){
        context->startOffset -= 3;
    } else {
        uint8_t idBuffer[3];
        de_store_descriptor(idBuffer, DE_UINT,  DE_SIZE_16);
        big_endian_store_16(idBuffer,1,attributeID);

        int ok = spd_append_range(context, 3, idBuffer);
        if (!ok) {
            context->complete = 0;
            return 1;
        }
    }

    // handle Attribute Value
    int attribute_len = de_get_len(attributeValue);
    if (context->startOffset >= attribute_len) {
        context->startOffset -= attribute_len;
        return 0;
    }

    int ok = spd_append_range(context, attribute_len, attributeValue);
    if (!ok) {
        context->complete = 0;
        return 1;
    }
    return 0;
}

int sdp_filter_attributes_in_attributeIDList(uint8_t *record, uint8_t *attributeIDList, uint16_t startOffset, uint16_t maxBytes, uint16_t *usedBytes, uint8_t *buffer){

    struct sdp_context_filter_attributes context;
    context.buffer = buffer;
    context.maxBytes = maxBytes;
    context.usedBytes = 0;
    context.startOffset = startOffset;
    context.attributeIDList = attributeIDList;
    context.complete = 1;

    sdp_attribute_list_traverse_sequence(record, sdp_traversal_filter_attributes, &context);

    *usedBytes = context.usedBytes;
    return context.complete;
}

// MARK: Get sum of attributes matching attribute list
struct sdp_context_get_filtered_size {
    uint8_t *attributeIDList;
    uint16_t size;
};

static int sdp_traversal_get_filtered_size(uint16_t attributeID, uint8_t * attributeValue, de_type_t de_type, de_size_t de_size, void *my_context){
    UNUSED(de_type);
    UNUSED(de_size);

    struct sdp_context_get_filtered_size * context = (struct sdp_context_get_filtered_size *) my_context;
    if (sdp_attribute_list_constains_id(context->attributeIDList, attributeID)) {
        context->size += 3 + de_get_len(attributeValue);
    }
    return 0;
}

int spd_get_filtered_size(uint8_t *record, uint8_t *attributeIDList){
    struct sdp_context_get_filtered_size context;
    context.size = 0;
    context.attributeIDList = attributeIDList;
    sdp_attribute_list_traverse_sequence(record, sdp_traversal_get_filtered_size, &context);
    return context.size;
}

// MARK: Get AttributeValue for AttributeID
// find attribute (ELEMENT) by ID
struct sdp_context_attribute_by_id {
    uint16_t  attributeID;
    uint8_t * attributeValue;
};
static int sdp_traversal_attribute_by_id(uint16_t attributeID, uint8_t * attributeValue, de_type_t de_type, de_size_t de_size, void *my_context){
    UNUSED(de_type);
    UNUSED(de_size);

    struct sdp_context_attribute_by_id * context = (struct sdp_context_attribute_by_id *) my_context;
    if (attributeID == context->attributeID) {
        context->attributeValue = attributeValue;
        return 1;
    }
    return 0;
}

uint8_t * sdp_get_attribute_value_for_attribute_id(uint8_t * record, uint16_t attributeID){
    struct sdp_context_attribute_by_id context;
    context.attributeValue = NULL;
    context.attributeID = attributeID;
    sdp_attribute_list_traverse_sequence(record, sdp_traversal_attribute_by_id, &context);
    return context.attributeValue;
}

// MARK: Set AttributeValue for AttributeID
struct sdp_context_set_attribute_for_id {
    uint16_t  attributeID;
    uint32_t  attributeValue;
    uint8_t   attributeFound;
};
static int sdp_traversal_set_attribute_for_id(uint16_t attributeID, uint8_t * attributeValue, de_type_t attributeType, de_size_t size, void *my_context){
    struct sdp_context_set_attribute_for_id * context = (struct sdp_context_set_attribute_for_id *) my_context;
    if (attributeID == context->attributeID) {
        context->attributeFound = 1;
        switch (size){
            case DE_SIZE_8:
                if (attributeType != DE_NIL){
                    attributeValue[1] = context->attributeValue;
                }
                break;
            case DE_SIZE_16:
                big_endian_store_16(attributeValue, 1, context->attributeValue);
                break;
            case DE_SIZE_32:
                big_endian_store_32(attributeValue, 1, context->attributeValue);
                break;
                // Might want to support STRINGS to, copy upto original length
            default:
                break;
        }
        return 1;
    }
    return 0;
}
uint8_t sdp_set_attribute_value_for_attribute_id(uint8_t * record, uint16_t attributeID, uint32_t value){
    struct sdp_context_set_attribute_for_id context;
    context.attributeID = attributeID;
    context.attributeValue = value;
    context.attributeFound = 0;
    sdp_attribute_list_traverse_sequence(record, sdp_traversal_set_attribute_for_id, &context);
    return context.attributeFound;
}

// MARK: ServiceRecord contains UUID
// service record contains UUID
// context { normalizedUUID }
struct sdp_context_contains_uuid128 {
    uint8_t * uuid128;
    int result;
};
int sdp_record_contains_UUID128(uint8_t *record, uint8_t *uuid128);
static int sdp_traversal_contains_UUID128(uint8_t * element, de_type_t type, de_size_t de_size, void *my_context){
    UNUSED(de_size);

    struct sdp_context_contains_uuid128 * context = (struct sdp_context_contains_uuid128 *) my_context;
    uint8_t normalizedUUID[16];
    if (type == DE_UUID){
        uint8_t uuidOK = de_get_normalized_uuid(normalizedUUID, element);
        context->result = uuidOK && memcmp(context->uuid128, normalizedUUID, 16) == 0;
    }
    if (type == DE_DES){
        context->result = sdp_record_contains_UUID128(element, context->uuid128);
    }
    return context->result;
}
int sdp_record_contains_UUID128(uint8_t *record, uint8_t *uuid128){
    struct sdp_context_contains_uuid128 context;
    context.uuid128 = uuid128;
    context.result = 0;
    de_traverse_sequence(record, sdp_traversal_contains_UUID128, &context);
    return context.result;
}

// MARK: ServiceRecord matches SearchServicePattern
// if UUID in searchServicePattern is not found in record => false
// context { result, record }
struct sdp_context_match_pattern {
    uint8_t * record;
    int result;
};

int sdp_traversal_match_pattern(uint8_t * element, de_type_t de_type, de_size_t de_size, void *my_context){
    UNUSED(de_type);
    UNUSED(de_size);

    struct sdp_context_match_pattern * context = (struct sdp_context_match_pattern *) my_context;
    uint8_t normalizedUUID[16];
    uint8_t uuidOK = de_get_normalized_uuid(normalizedUUID, element);
    if (!uuidOK || !sdp_record_contains_UUID128(context->record, normalizedUUID)){
        context->result = 0;
        return 1;
    }
    return 0;
}
int sdp_record_matches_service_search_pattern(uint8_t *record, uint8_t *serviceSearchPattern){
    struct sdp_context_match_pattern context;
    context.record = record;
    context.result = 1;
    de_traverse_sequence(serviceSearchPattern, sdp_traversal_match_pattern, &context);
    return context.result;
}

// MARK: Dump DataElement
// context { indent }
#ifdef ENABLE_SDP_DES_DUMP
static int de_traversal_dump_data(uint8_t * element, de_type_t de_type, de_size_t de_size, void *my_context){
    int indent = *(int*) my_context;
    int i;
    for (i=0; i<indent;i++) printf("    ");
    unsigned int pos     = de_get_header_size(element);
    unsigned int end_pos = de_get_len(element);
    printf("type %5s (%u), element len %2u ", type_names[de_type], de_type, end_pos);
    if (de_type == DE_DES) {
		printf("\n");
        indent++;
        de_traverse_sequence(element, de_traversal_dump_data, (void *)&indent);
    } else if (de_type == DE_UUID && de_size == DE_SIZE_128) {
        printf(", value: %s\n", uuid128_to_str(element+1));
    } else if (de_type == DE_STRING) {
        unsigned int len = 0;
        switch (de_size){
            case DE_SIZE_VAR_8:
                len = element[1];
                break;
            case DE_SIZE_VAR_16:
                len = big_endian_read_16(element, 1);
                break;
            default:
                break;
        }
        printf("len %u (0x%02x)\n", len, len);
        printf_hexdump(&element[pos], len);
    } else {
        uint32_t value = 0;
        switch (de_size) {
            case DE_SIZE_8:
                if (de_type != DE_NIL){
                    value = element[pos];
                }
                break;
            case DE_SIZE_16:
				value = big_endian_read_16(element,pos);
                break;
            case DE_SIZE_32:
				value = big_endian_read_32(element,pos);
                break;
            default:
                break;
        }
        printf(", value: 0x%08" PRIx32 "\n", value);
    }
    return 0;
}
#endif

void de_dump_data_element(const uint8_t * record){
#ifdef ENABLE_SDP_DES_DUMP
    int indent = 0;
    // hack to get root DES, too.
    de_type_t type = de_get_element_type(record);
    de_size_t size = de_get_size_type(record);
    de_traversal_dump_data((uint8_t *) record, type, size, (void*) &indent);
#endif
}

uint8_t* sdp_service_search_pattern_for_uuid16(uint16_t uuid16){
    big_endian_store_16(des_serviceSearchPatternUUID16, 3, uuid16);
    return (uint8_t*)des_serviceSearchPatternUUID16;
}

uint8_t* sdp_service_search_pattern_for_uuid128(const uint8_t * uuid128){
    memcpy(&des_serviceSearchPatternUUID128[3], uuid128, 16);
    return (uint8_t*)des_serviceSearchPatternUUID128;
}