Diff: btstack/sdp.c

Revision:

0:fccb789424fc

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/btstack/sdp.c	Mon Jun 10 16:01:50 2013 +0000
@@ -0,0 +1,662 @@
+/*
+ * Copyright (C) 2009-2012 by Matthias Ringwald
+ *
+ * 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 MATTHIAS RINGWALD 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 btstack@ringwald.ch
+ *
+ */
+
+/*
+ * Implementation of the Service Discovery Protocol Server 
+ */
+
+#include "sdp.h"
+
+
+#include <stdio.h>
+#include <string.h>
+
+#include <btstack/sdp_util.h>
+
+#include "hci_dump.h"
+#include "l2cap.h"
+
+#include "debug.h"
+
+// max reserved ServiceRecordHandle
+#define maxReservedServiceRecordHandle 0xffff
+
+// max SDP response
+#define SDP_RESPONSE_BUFFER_SIZE (HCI_ACL_BUFFER_SIZE-HCI_ACL_HEADER_SIZE)
+
+static void sdp_packet_handler(uint8_t packet_type, uint16_t channel, uint8_t *packet, uint16_t size);
+
+// registered service records
+static linked_list_t sdp_service_records = NULL;
+
+// our handles start after the reserved range
+static uint32_t sdp_next_service_record_handle = maxReservedServiceRecordHandle + 2;
+
+static uint8_t sdp_response_buffer[SDP_RESPONSE_BUFFER_SIZE];
+
+static void (*app_packet_handler)(void * connection, uint8_t packet_type,
+                                  uint16_t channel, uint8_t *packet, uint16_t size) = NULL;
+
+static uint16_t l2cap_cid = 0;
+static uint16_t sdp_response_size = 0;
+
+void sdp_init(){
+    // register with l2cap psm sevices - max MTU
+    l2cap_register_service_internal(NULL, sdp_packet_handler, PSM_SDP, 0xffff);
+}
+
+// register packet handler
+void sdp_register_packet_handler(void (*handler)(void * connection, uint8_t packet_type,
+                                                 uint16_t channel, uint8_t *packet, uint16_t size)){
+    app_packet_handler = handler;
+    l2cap_cid = 0;
+}
+
+uint32_t sdp_get_service_record_handle(uint8_t * record){
+    uint8_t * serviceRecordHandleAttribute = sdp_get_attribute_value_for_attribute_id(record, SDP_ServiceRecordHandle);
+    if (!serviceRecordHandleAttribute) return 0;
+    if (de_get_element_type(serviceRecordHandleAttribute) != DE_UINT) return 0;
+    if (de_get_size_type(serviceRecordHandleAttribute) != DE_SIZE_32) return 0;
+    return READ_NET_32(serviceRecordHandleAttribute, 1); 
+}
+
+// data: event(8), len(8), status(8), service_record_handle(32)
+static void sdp_emit_service_registered(void *connection, uint32_t handle, uint8_t status) {
+    if (!app_packet_handler) return;
+    uint8_t event[7];
+    event[0] = SDP_SERVICE_REGISTERED;
+    event[1] = sizeof(event) - 2;
+    event[2] = status;
+    bt_store_32(event, 3, handle);
+    hci_dump_packet(HCI_EVENT_PACKET, 0, event, sizeof(event));
+    (*app_packet_handler)(connection, HCI_EVENT_PACKET, 0, (uint8_t *) event, sizeof(event));
+}
+
+service_record_item_t * sdp_get_record_for_handle(uint32_t handle){
+    linked_item_t *it;
+    for (it = (linked_item_t *) sdp_service_records; it ; it = it->next){
+        service_record_item_t * item = (service_record_item_t *) it;
+        if (item->service_record_handle == handle){
+            return item;
+        }
+    }
+    return NULL;
+}
+
+// get next free, unregistered service record handle
+uint32_t sdp_create_service_record_handle(void){
+    uint32_t handle = 0;
+    do {
+        handle = sdp_next_service_record_handle++;
+        if (sdp_get_record_for_handle(handle)) handle = 0;
+    } while (handle == 0);
+    return handle;
+}
+
+#ifdef EMBEDDED
+
+// register service record internally - this special version doesn't copy the record, it should not be freeed
+// pre: AttributeIDs are in ascending order
+// pre: ServiceRecordHandle is first attribute and valid
+// pre: record
+// @returns ServiceRecordHandle or 0 if registration failed
+uint32_t sdp_register_service_internal(void *connection, service_record_item_t * record_item){
+    // get user record handle
+    uint32_t record_handle = record_item->service_record_handle;
+    // get actual record
+    uint8_t *record = record_item->service_record;
+    
+    // check for ServiceRecordHandle attribute, returns pointer or null
+    uint8_t * req_record_handle = sdp_get_attribute_value_for_attribute_id(record, SDP_ServiceRecordHandle);
+    if (!req_record_handle) {
+        log_error("SDP Error - record does not contain ServiceRecordHandle attribute\n");
+        return 0;
+    }
+    
+    // validate service record handle is not in reserved range
+    if (record_handle <= maxReservedServiceRecordHandle) record_handle = 0;
+    
+    // check if already in use
+    if (record_handle) {
+        if (sdp_get_record_for_handle(record_handle)) {
+            record_handle = 0;
+        }
+    }
+    
+    // create new handle if needed
+    if (!record_handle){
+        record_handle = sdp_create_service_record_handle();
+        // Write the handle back into the record too
+        record_item->service_record_handle = record_handle;
+        sdp_set_attribute_value_for_attribute_id(record, SDP_ServiceRecordHandle, record_handle);
+    }
+    
+    // add to linked list
+    linked_list_add(&sdp_service_records, (linked_item_t *) record_item);
+    
+    sdp_emit_service_registered(connection, 0, record_item->service_record_handle);
+    
+    return record_handle;
+}
+
+#else
+
+// AttributeIDList used to remove ServiceRecordHandle
+static const uint8_t removeServiceRecordHandleAttributeIDList[] = { 0x36, 0x00, 0x05, 0x0A, 0x00, 0x01, 0xFF, 0xFF };
+
+// register service record internally - the normal version creates a copy of the record
+// pre: AttributeIDs are in ascending order => ServiceRecordHandle is first attribute if present
+// @returns ServiceRecordHandle or 0 if registration failed
+uint32_t sdp_register_service_internal(void *connection, uint8_t * record){
+
+    // dump for now
+    // printf("Register service record\n");
+    // de_dump_data_element(record);
+    
+    // get user record handle
+    uint32_t record_handle = sdp_get_service_record_handle(record);
+
+    // validate service record handle is not in reserved range
+    if (record_handle <= maxReservedServiceRecordHandle) record_handle = 0;
+    
+    // check if already in use
+    if (record_handle) {
+        if (sdp_get_record_for_handle(record_handle)) {
+            record_handle = 0;
+        }
+    }
+    
+    // create new handle if needed
+    if (!record_handle){
+        record_handle = sdp_create_service_record_handle();
+    }
+    
+    // calculate size of new service record: DES (2 byte len) 
+    // + ServiceRecordHandle attribute (UINT16 UINT32) + size of existing attributes
+    uint16_t recordSize =  3 + (3 + 5) + de_get_data_size(record);
+        
+    // alloc memory for new service_record_item
+    service_record_item_t * newRecordItem = (service_record_item_t *) malloc(recordSize + sizeof(service_record_item_t));
+    if (!newRecordItem) {
+        sdp_emit_service_registered(connection, 0, BTSTACK_MEMORY_ALLOC_FAILED);
+        return 0;
+    }
+    // link new service item to client connection
+    newRecordItem->connection = connection;
+    
+    // set new handle
+    newRecordItem->service_record_handle = record_handle;
+
+    // create updated service record
+    uint8_t * newRecord = (uint8_t *) &(newRecordItem->service_record);
+    
+    // create DES for new record
+    de_create_sequence(newRecord);
+    
+    // set service record handle
+    de_add_number(newRecord, DE_UINT, DE_SIZE_16, 0);
+    de_add_number(newRecord, DE_UINT, DE_SIZE_32, record_handle);
+    
+    // add other attributes
+    sdp_append_attributes_in_attributeIDList(record, (uint8_t *) removeServiceRecordHandleAttributeIDList, 0, recordSize, newRecord);
+    
+    // dump for now
+    // de_dump_data_element(newRecord);
+    // printf("reserved size %u, actual size %u\n", recordSize, de_get_len(newRecord));
+    
+    // add to linked list
+    linked_list_add(&sdp_service_records, (linked_item_t *) newRecordItem);
+    
+    sdp_emit_service_registered(connection, 0, newRecordItem->service_record_handle);
+
+    return record_handle;
+}
+
+#endif
+
+// unregister service record internally
+// 
+// makes sure one client cannot remove service records of other clients
+//
+void sdp_unregister_service_internal(void *connection, uint32_t service_record_handle){
+    service_record_item_t * record_item = sdp_get_record_for_handle(service_record_handle);
+    if (record_item && record_item->connection == connection) {
+        linked_list_remove(&sdp_service_records, (linked_item_t *) record_item);
+    }
+}
+
+// remove all service record for a client connection
+void sdp_unregister_services_for_connection(void *connection){
+    linked_item_t *it = (linked_item_t *) &sdp_service_records;
+    while (it->next){
+        service_record_item_t *record_item = (service_record_item_t *) it->next;
+        if (record_item->connection == connection){
+            it->next = it->next->next;
+#ifndef EMBEDDED
+            free(record_item);
+#endif
+        } else {
+            it = it->next;
+        }
+    }
+}
+
+// PDU
+// PDU ID (1), Transaction ID (2), Param Length (2), Param 1, Param 2, ..
+
+int sdp_create_error_response(uint16_t transaction_id, uint16_t error_code){
+    sdp_response_buffer[0] = SDP_ErrorResponse;
+    net_store_16(sdp_response_buffer, 1, transaction_id);
+    net_store_16(sdp_response_buffer, 3, 2);
+    net_store_16(sdp_response_buffer, 5, error_code); // invalid syntax
+    return 7;
+}
+
+int sdp_handle_service_search_request(uint8_t * packet, uint16_t remote_mtu){
+    
+    // get request details
+    uint16_t  transaction_id = READ_NET_16(packet, 1);
+    // not used yet - uint16_t  param_len = READ_NET_16(packet, 3);
+    uint8_t * serviceSearchPattern = &packet[5];
+    uint16_t  serviceSearchPatternLen = de_get_len(serviceSearchPattern);
+    uint16_t  maximumServiceRecordCount = READ_NET_16(packet, 5 + serviceSearchPatternLen);
+    uint8_t * continuationState = &packet[5+serviceSearchPatternLen+2];
+    
+    // calc maxumumServiceRecordCount based on remote MTU
+    uint16_t maxNrServiceRecordsPerResponse = (remote_mtu - (9+3))/4;
+    
+    // continuation state contains index of next service record to examine
+    int      continuation = 0;
+    uint16_t continuation_index = 0;
+    if (continuationState[0] == 2){
+        continuation_index = READ_NET_16(continuationState, 1);
+    }
+    
+    // get and limit total count
+    linked_item_t *it;
+    uint16_t total_service_count   = 0;
+    for (it = (linked_item_t *) sdp_service_records; it ; it = it->next){
+        service_record_item_t * item = (service_record_item_t *) it;
+        if (!sdp_record_matches_service_search_pattern(item->service_record, serviceSearchPattern)) continue;
+        total_service_count++;
+    }
+    if (total_service_count > maximumServiceRecordCount){
+        total_service_count = maximumServiceRecordCount;
+    }
+    
+    // ServiceRecordHandleList at 9
+    uint16_t pos = 9;
+    uint16_t current_service_count  = 0;
+    uint16_t current_service_index  = 0;
+    uint16_t matching_service_count = 0;
+    for (it = (linked_item_t *) sdp_service_records; it ; it = it->next, ++current_service_index){
+        service_record_item_t * item = (service_record_item_t *) it;
+
+        if (!sdp_record_matches_service_search_pattern(item->service_record, serviceSearchPattern)) continue;
+        matching_service_count++;
+        
+        if (current_service_index < continuation_index) continue;
+
+        net_store_32(sdp_response_buffer, pos, item->service_record_handle);
+        pos += 4;
+        current_service_count++;
+        
+        if (matching_service_count >= total_service_count) break;
+
+        if (current_service_count >= maxNrServiceRecordsPerResponse){
+            continuation = 1;
+            continuation_index = current_service_index + 1;
+            break;
+        }
+    }
+    
+    // Store continuation state
+    if (continuation) {
+        sdp_response_buffer[pos++] = 2;
+        net_store_16(sdp_response_buffer, pos, continuation_index);
+        pos += 2;
+    } else {
+        sdp_response_buffer[pos++] = 0;
+    }
+
+    // header
+    sdp_response_buffer[0] = SDP_ServiceSearchResponse;
+    net_store_16(sdp_response_buffer, 1, transaction_id);
+    net_store_16(sdp_response_buffer, 3, pos - 5); // size of variable payload
+    net_store_16(sdp_response_buffer, 5, total_service_count);
+    net_store_16(sdp_response_buffer, 7, current_service_count);
+    
+    return pos;
+}
+
+int sdp_handle_service_attribute_request(uint8_t * packet, uint16_t remote_mtu){
+    
+    // get request details
+    uint16_t  transaction_id = READ_NET_16(packet, 1);
+    // not used yet - uint16_t  param_len = READ_NET_16(packet, 3);
+    uint32_t  serviceRecordHandle = READ_NET_32(packet, 5);
+    uint16_t  maximumAttributeByteCount = READ_NET_16(packet, 9);
+    uint8_t * attributeIDList = &packet[11];
+    uint16_t  attributeIDListLen = de_get_len(attributeIDList);
+    uint8_t * continuationState = &packet[11+attributeIDListLen];
+    
+    // calc maximumAttributeByteCount based on remote MTU
+    uint16_t maximumAttributeByteCount2 = remote_mtu - (7+3);
+    if (maximumAttributeByteCount2 < maximumAttributeByteCount) {
+        maximumAttributeByteCount = maximumAttributeByteCount2;
+    }
+    
+    // continuation state contains the offset into the complete response
+    uint16_t continuation_offset = 0;
+    if (continuationState[0] == 2){
+        continuation_offset = READ_NET_16(continuationState, 1);
+    }
+    
+    // get service record
+    service_record_item_t * item = sdp_get_record_for_handle(serviceRecordHandle);
+    if (!item){
+        // service record handle doesn't exist
+        return sdp_create_error_response(transaction_id, 0x0002); /// invalid Service Record Handle
+    }
+    
+    
+    // AttributeList - starts at offset 7
+    uint16_t pos = 7;
+    
+    if (continuation_offset == 0){
+        
+        // get size of this record
+        uint16_t filtered_attributes_size = spd_get_filtered_size(item->service_record, attributeIDList);
+        
+        // store DES
+        de_store_descriptor_with_len(&sdp_response_buffer[pos], DE_DES, DE_SIZE_VAR_16, filtered_attributes_size);
+        maximumAttributeByteCount -= 3;
+        pos += 3;
+    }
+
+    // copy maximumAttributeByteCount from record
+    uint16_t bytes_used;
+    int complete = sdp_filter_attributes_in_attributeIDList(item->service_record, attributeIDList, continuation_offset, maximumAttributeByteCount, &bytes_used, &sdp_response_buffer[pos]);
+    pos += bytes_used;
+    
+    uint16_t attributeListByteCount = pos - 7;
+
+    if (complete) {
+        sdp_response_buffer[pos++] = 0;
+    } else {
+        continuation_offset += bytes_used;
+        sdp_response_buffer[pos++] = 2;
+        net_store_16(sdp_response_buffer, pos, continuation_offset);
+        pos += 2;
+    }
+
+    // header
+    sdp_response_buffer[0] = SDP_ServiceAttributeResponse;
+    net_store_16(sdp_response_buffer, 1, transaction_id);
+    net_store_16(sdp_response_buffer, 3, pos - 5);  // size of variable payload
+    net_store_16(sdp_response_buffer, 5, attributeListByteCount); 
+    
+    return pos;
+}
+
+static uint16_t sdp_get_size_for_service_search_attribute_response(uint8_t * serviceSearchPattern, uint8_t * attributeIDList){
+    uint16_t total_response_size = 0;
+    linked_item_t *it;
+    for (it = (linked_item_t *) sdp_service_records; it ; it = it->next){
+        service_record_item_t * item = (service_record_item_t *) it;
+        
+        if (!sdp_record_matches_service_search_pattern(item->service_record, serviceSearchPattern)) continue;
+        
+        // for all service records that match
+        total_response_size += 3 + spd_get_filtered_size(item->service_record, attributeIDList);
+    }
+    return total_response_size;
+}
+
+int sdp_handle_service_search_attribute_request(uint8_t * packet, uint16_t remote_mtu){
+    
+    // SDP header before attribute sevice list: 7
+    // Continuation, worst case: 5
+    
+    // get request details
+    uint16_t  transaction_id = READ_NET_16(packet, 1);
+    // not used yet - uint16_t  param_len = READ_NET_16(packet, 3);
+    uint8_t * serviceSearchPattern = &packet[5];
+    uint16_t  serviceSearchPatternLen = de_get_len(serviceSearchPattern);
+    uint16_t  maximumAttributeByteCount = READ_NET_16(packet, 5 + serviceSearchPatternLen);
+    uint8_t * attributeIDList = &packet[5+serviceSearchPatternLen+2];
+    uint16_t  attributeIDListLen = de_get_len(attributeIDList);
+    uint8_t * continuationState = &packet[5+serviceSearchPatternLen+2+attributeIDListLen];
+    
+    // calc maximumAttributeByteCount based on remote MTU, SDP header and reserved Continuation block
+    uint16_t maximumAttributeByteCount2 = remote_mtu - 12;
+    if (maximumAttributeByteCount2 < maximumAttributeByteCount) {
+        maximumAttributeByteCount = maximumAttributeByteCount2;
+    }
+    
+    // continuation state contains: index of next service record to examine
+    // continuation state contains: byte offset into this service record
+    uint16_t continuation_service_index = 0;
+    uint16_t continuation_offset = 0;
+    if (continuationState[0] == 4){
+        continuation_service_index = READ_NET_16(continuationState, 1);
+        continuation_offset = READ_NET_16(continuationState, 3);
+    }
+
+    // printf("--> sdp_handle_service_search_attribute_request, cont %u/%u, max %u\n", continuation_service_index, continuation_offset, maximumAttributeByteCount);
+    
+    // AttributeLists - starts at offset 7
+    uint16_t pos = 7;
+    
+    // add DES with total size for first request
+    if (continuation_service_index == 0 && continuation_offset == 0){
+        uint16_t total_response_size = sdp_get_size_for_service_search_attribute_response(serviceSearchPattern, attributeIDList);
+        de_store_descriptor_with_len(&sdp_response_buffer[pos], DE_DES, DE_SIZE_VAR_16, total_response_size);
+        // log_info("total response size %u\n", total_response_size);
+        pos += 3;
+        maximumAttributeByteCount -= 3;
+    }
+    
+    // create attribute list
+    int      first_answer = 1;
+    int      continuation = 0;
+    uint16_t current_service_index = 0;
+    linked_item_t *it = (linked_item_t *) sdp_service_records;
+    for ( ; it ; it = it->next, ++current_service_index){
+        service_record_item_t * item = (service_record_item_t *) it;
+        
+        if (current_service_index < continuation_service_index ) continue;
+        if (!sdp_record_matches_service_search_pattern(item->service_record, serviceSearchPattern)) continue;
+
+        if (continuation_offset == 0){
+            
+            // get size of this record
+            uint16_t filtered_attributes_size = spd_get_filtered_size(item->service_record, attributeIDList);
+            
+            // stop if complete record doesn't fits into response but we already have a partial response
+            if ((filtered_attributes_size + 3 > maximumAttributeByteCount) && !first_answer) {
+                continuation = 1;
+                break;
+            }
+            
+            // store DES
+            de_store_descriptor_with_len(&sdp_response_buffer[pos], DE_DES, DE_SIZE_VAR_16, filtered_attributes_size);
+            pos += 3;
+            maximumAttributeByteCount -= 3;
+        }
+        
+        first_answer = 0;
+    
+        // copy maximumAttributeByteCount from record
+        uint16_t bytes_used;
+        int complete = sdp_filter_attributes_in_attributeIDList(item->service_record, attributeIDList, continuation_offset, maximumAttributeByteCount, &bytes_used, &sdp_response_buffer[pos]);
+        pos += bytes_used;
+        maximumAttributeByteCount -= bytes_used;
+        
+        if (complete) {
+            continuation_offset = 0;
+            continue;
+        }
+        
+        continuation = 1;
+        continuation_offset += bytes_used;
+        break;
+    }
+    
+    uint16_t attributeListsByteCount = pos - 7;
+    
+    // Continuation State
+    if (continuation){
+        sdp_response_buffer[pos++] = 4;
+        net_store_16(sdp_response_buffer, pos, (uint16_t) current_service_index);
+        pos += 2;
+        net_store_16(sdp_response_buffer, pos, continuation_offset);
+        pos += 2;
+    } else {
+        // complete
+        sdp_response_buffer[pos++] = 0;
+    }
+        
+    // create SDP header
+    sdp_response_buffer[0] = SDP_ServiceSearchAttributeResponse;
+    net_store_16(sdp_response_buffer, 1, transaction_id);
+    net_store_16(sdp_response_buffer, 3, pos - 5);  // size of variable payload
+    net_store_16(sdp_response_buffer, 5, attributeListsByteCount);
+    
+    return pos;
+}
+
+static void sdp_try_respond(void){
+    if (!sdp_response_size ) return;
+    if (!l2cap_cid) return;
+    if (!l2cap_can_send_packet_now(l2cap_cid)) return;
+    
+    // update state before sending packet (avoid getting called when new l2cap credit gets emitted)
+    uint16_t size = sdp_response_size;
+    sdp_response_size = 0;
+    l2cap_send_internal(l2cap_cid, sdp_response_buffer, size);
+}
+
+// we assume that we don't get two requests in a row
+static void sdp_packet_handler(uint8_t packet_type, uint16_t channel, uint8_t *packet, uint16_t size){
+    uint16_t transaction_id;
+    SDP_PDU_ID_t pdu_id;
+    uint16_t remote_mtu;
+    // uint16_t param_len;
+    
+    switch (packet_type) {
+            
+        case L2CAP_DATA_PACKET:
+            pdu_id = (SDP_PDU_ID_t) packet[0];
+            transaction_id = READ_NET_16(packet, 1);
+            // param_len = READ_NET_16(packet, 3);
+            remote_mtu = l2cap_get_remote_mtu_for_local_cid(channel);
+            // account for our buffer
+            if (remote_mtu > SDP_RESPONSE_BUFFER_SIZE){
+                remote_mtu = SDP_RESPONSE_BUFFER_SIZE;
+            }
+            
+            // printf("SDP Request: type %u, transaction id %u, len %u, mtu %u\n", pdu_id, transaction_id, param_len, remote_mtu);
+            switch (pdu_id){
+                    
+                case SDP_ServiceSearchRequest:
+                    sdp_response_size = sdp_handle_service_search_request(packet, remote_mtu);
+                    break;
+                                        
+                case SDP_ServiceAttributeRequest:
+                    sdp_response_size = sdp_handle_service_attribute_request(packet, remote_mtu);
+                    break;
+                    
+                case SDP_ServiceSearchAttributeRequest:
+                    sdp_response_size = sdp_handle_service_search_attribute_request(packet, remote_mtu);
+                    break;
+                    
+                default:
+                    sdp_response_size = sdp_create_error_response(transaction_id, 0x0003); // invalid syntax
+                    break;
+            }
+            
+            sdp_try_respond();
+            
+            break;
+            
+        case HCI_EVENT_PACKET:
+            
+            switch (packet[0]) {
+
+                case L2CAP_EVENT_INCOMING_CONNECTION:
+                    if (l2cap_cid) {
+                        // CONNECTION REJECTED DUE TO LIMITED RESOURCES 
+                        l2cap_decline_connection_internal(channel, 0x0d);
+                        break;
+                    }
+                    // accept
+                    l2cap_cid = channel;
+                    sdp_response_size = 0;
+                    l2cap_accept_connection_internal(channel);
+                    break;
+                    
+                case L2CAP_EVENT_CHANNEL_OPENED:
+                    if (packet[2]) {
+                        // open failed -> reset
+                        l2cap_cid = 0;
+                    }
+                    break;
+
+                case L2CAP_EVENT_CREDITS:
+                case DAEMON_EVENT_HCI_PACKET_SENT:
+                    sdp_try_respond();
+                    break;
+                
+                case L2CAP_EVENT_CHANNEL_CLOSED:
+                    if (channel == l2cap_cid){
+                        // reset
+                        l2cap_cid = 0;
+                    }
+                    break;
+                                        
+                default:
+                    // other event
+                    break;
+            }
+            break;
+            
+        default:
+            // other packet type
+            break;
+    }
+}
+